20. Internationales Stuttgarter Symposium : Automobil- und Motorentechnik [1. Aufl.] 9783658299422, 9783658299439

Table of contents :
Front Matter ....Pages I-XIX
Passenger car powertrains and future energy scenarios: CO2 compliance versus affordability and lifecycle emissions (Günter Fraidl, B. Enzi, Ch. Martin, Martin Rothbart)....Pages 1-3
The challenges of WLTP emission regulations from the vehicle manufacturer’s point of view (Roland Kemmler, Christoph Müller, Timo Deuschle, Manuel Liebing, Sarah Tyslik, Volker Blum)....Pages 5-27
Are hybrid-powertrains the right solutions to meet the EU-emission-targets 2030? (Gerald Eifler, Alexander Dau, Markus Wetscher)....Pages 29-51
A mobility study in commercial and industrial areas of Stuttgart – Experiences and conclusions promoting intermodality of commuters (Günter Sabow)....Pages 53-53
MobiLab – The mobility living lab at the University of Stuttgart (Wolfram Ressel)....Pages 55-55
Future of multi-modal mobility (Jürgen Schlaht)....Pages 57-65
Increasing Mobility (Rainer Röck)....Pages 67-67
Concept people mover of tomorrow (Felix Jakob, Giovanni Sapio, Nicole Starr)....Pages 69-79
Downtown delivery last mile with E-van and box body with integral batteries (Jürgen Erhardt)....Pages 81-85
Emission-free driving (Gunnar-Marcel Klein)....Pages 87-87
Pathways to a CO2-free mobility system in Germany from a technological point of view (Michael Kühn, Peter Burghardt, Hans-Georg Hummel)....Pages 89-104
Potentials for the implementation of emission free autonomous delivery traffic in inner cities (Dennis Wedler, Thomas Vietor)....Pages 105-116
The role of virtual simulation in aero development of Lamborghini SuperCars (Antonio Torluccio, Gilberto Arzilli)....Pages 117-133
Active aerodynamics to increase the features of a motorcycle (Giovanni Lombardi, Marco Maganzi, Elena Pasqualetto)....Pages 135-149
Efficient CFD methods for assessment of water management (Martin Novák, Rene Devaradja, Jacques Papper, Martin Černý)....Pages 151-170
Insulation of electrical motors – Potential to increase performance of future electrical powertrains (Moritz Kilper, Hristian Naumoski)....Pages 171-183
eAxle development and optimization regarding NVH, efficiency and power density (Andreas Höfer, Marc Herbel, Diego Schierle, Wladislaw Peschkow, Philippe Hamon)....Pages 185-196
FE-based sensitivity analysis of stator winding geometries regarding bending behavior using flatpack bending technology (David Wüterich, Michael Kopp, Mathias Liewald)....Pages 197-207
Influence of body-in-white stiffness on elastokinematics (Naser Jafarzadehpour, M. Bidlingmaier, B. Corves)....Pages 209-221
Ride comfort evaluation of predictive ride height and damper control adaptation on single obstacles (Konstantin Riedl, Sebastian Schaer, Julian Kreibich, Markus Lienkamp, Shane Cannon, Christian Schimmel)....Pages 223-235
Objectification of the feeling of safety at high speed based on the human perception of vehicle motions (Martin Heiderich, Frank Zantner, Hideaki Shibue, Robert Kastner, Jens Neubeck, Jochen Wiedemann et al.)....Pages 237-249
Wet clutch as an enabler of cost-efficient hybrid drive systems – Decoupling as functional extension (A. Albers, Arne Bischofberger, S. Ott)....Pages 251-265
Objectified evaluation of shifting quality of manual transmissions during real operation (Daniel Trost, E. Brosch, Hans-Christian Reuss)....Pages 267-279
Gearbox simulation for EVs: Optimization between gear rating, available space and NVH requirements (Chhaya Chavan, T. Heidlauf, J. Langhart)....Pages 281-295
Leveraging big data analysis to enhance the validation of EGT-Systems (Nicolas Ide, A. Serout, T. Rankel, T. Dengler)....Pages 297-313
Fundamental research on pre-turbo exhaust gas aftertreatment systems (Martin Angerbauer, M. Grill, M. Bargende, F. Inci)....Pages 315-336
Pre-turbo DeNOx exhaust gas aftertreatment system for future 48V Diesel powertrains (C. Beidl, J. Hipp, D. Knaf, R. Anselm, G. Hohenberg, M. Conin et al.)....Pages 337-355
Reconstruction of traffic accidents with automated and electrified vehicles (Daniel Paula, Hans-Georg Schweiger, Klaus Böhm)....Pages 357-371
Efficient usage of abstract scenarios for the development of highly-automated driving functions (Florian Bock, Aaron Heinz, Jens Lorenz)....Pages 373-387
Vehicle endurance testing through automated test driving (Felix Kistler, Michael Nadj, Hans-Peter Reifenrath, Stefan Staudacher, Michael Keckeisen)....Pages 389-401
AI for new ADAS user interfaces: Opportunities through collaboration or risks? (Ulrich Bodenhausen)....Pages 403-410
Determination of secured lane information for highly automated vehicles (Sven Eckelmann, Toralf Trautmann, Jonas Fabich)....Pages 411-417
Virtual validation of autonomous vehicle safety through simulation-based testing (Mustafa Saraoğlu, Qihang Shi, Andrey Morozov, Klaus Janschek)....Pages 419-434
Empathic assistants – Methods and use cases in automated and non-automated driving (Anna-Antonia Pape, Sonja Cornelsen, Victor Faeßler, Klas Ihme, Michael Oehl, Uwe Drewitz et al.)....Pages 435-449
Approach to objective evaluation of driving behavior with ESC-interventions demonstrated by a lane change maneuver (Fabian Fontana, Jens Neubeck, Andreas Wagner, Jochen Wiedemann, Uli Schaaf, Ingo Scharfenbaum)....Pages 451-467
Mechatronic system design for EPS systems with residual modes and variable, nonlinear plant behavior (Marcus Irmer, Hermann Henrichfreise, Michael Haßenberg, Hermann Briese)....Pages 469-482
Design optimization of water-injection-SI engines by virtual engine development (Antonino Vacca, Francesco Cupo, Edoardo Rossi, Marco Chiodi, Michael Bargende)....Pages 483-498
Intake port condensed water injection for a clean natural gas engine: Strategies and restrictions (Youssef Beltaifa, Jörn Judith, Maurice Kettner, Peter Eilts, Markus Klaissle, Volker Wiersbitzki)....Pages 499-518
Experimental study of a free piston linear alternator with an opposed piston combustion chamber (Alex Heron-Himmel, Stephan Schneider, Marco Chiodi)....Pages 519-532
SkELInG – Scalable EV charging system with central infrastructure and DC distribution grid (Taleb Janbein, Erik Hoevenaars, Thomas Weil, Bernd Bohnet)....Pages 533-542
100+ charging points – Grid friendly intelligent load & charge management – ChargeBIG in operation (Sebastian Ewert, Walter Krepulat, Max Gerstadt, Hauke Stamer)....Pages 543-556
Energy and automotive (Ursel Willrett)....Pages 557-567
Digitalization of flow measurement systems, in particular of fuel consumption measurement (Heribert Kammerstetter, Josef Moik, Michael Sammer, Manuel Berglez, Daniel Leitner)....Pages 569-578
Solution of trade-offs in the development of powertrains by use of online measurement technologies (Peter Berlet, A. Jäger)....Pages 579-588
Study to assess the suitability of C/C-SiC as material for piston rings (Alex Heron-Himmel, Fiona Kessel, Yuan Shi)....Pages 589-602
Experimental and numerical investigations of NO2 and HCHO formation in lean gas engines (Denis Notheis, U. Wagner, A. Velji, T. Koch, Felix Poschen, M. Olzmann)....Pages 603-603
Investigations of interactions between fuels and fuels leading components of plug-inhybrid electrical vehicles (Wilfried Plum, Sebastian Feldhoff, Markus Jakob, Jens Staufenbiel)....Pages 605-619
(Bio-)Methyl ethers as alternative fuels in bivalent Diesel combustion (Kai Gaukel, Martin Härtl, Dominik Pélerin, Georg Wachtmeister, Benedikt Heuser, Bastian Lehrheuer et al.)....Pages 621-668

Citation preview

Proceedings

Michael Bargende · Hans-Christian Reuss Andreas Wagner Hrsg.

20. Internationales Stuttgarter Symposium Automobil- und Motorentechnik Band 1

Proceedings

Ein stetig steigender Fundus an Informationen ist heute notwendig, um die immer komplexer werdende Technik heutiger Kraftfahrzeuge zu verstehen. Funktionen, Arbeitsweise, Komponenten und Systeme entwickeln sich rasant. In immer schnelleren Zyklen verbreitet sich aktuelles Wissen gerade aus Konferenzen, Tagungen und Symposien in die Fachwelt. Den raschen Zugriff auf diese Informationen bietet diese Reihe Proceedings, die sich zur Aufgabe gestellt hat, das zum Verständnis topaktueller Technik rund um das Automobil erforderliche spezielle Wissen in der Systematik aus Konferenzen und Tagungen zusammen zu stellen und als Buch in Springer.com wie auch elektronisch in Springer Link und Springer Professional bereit zu stellen. Die Reihe wendet sich an Fahrzeug- und Motoreningenieure sowie Studierende, die aktuelles Fachwissen im Zusammenhang mit Fragestellungen ihres Arbeitsfeldes suchen. Professoren und Dozenten an Universitäten und Hochschulen mit Schwerpunkt Kraftfahrzeug- und Motorentechnik finden hier die Zusammenstellung von Veranstaltungen, die sie selber nicht besuchen konnten. Gutachtern, Forschern und Entwicklungsingenieuren in der Automobil- und Zulieferindustrie sowie Dienstleistern können die Proceedings wertvolle Antworten auf topaktuelle Fragen geben. Today, a steadily growing store of information is called for in order to understand the increasingly complex technologies used in modern automobiles. Functions, modes of operation, components and systems are rapidly evolving, while at the same time the latest expertise is disseminated directly from conferences, congresses and symposia to the professional world in ever-faster cycles. This series of proceedings offers rapid access to this information, gathering the specific knowledge needed to keep up with cutting-edge advances in automotive technologies, employing the same systematic approach used at conferences and congresses and presenting it in print (available at Springer.com) and electronic (at Springer Link and Springer Professional) formats. The series addresses the needs of automotive engineers, motor design engineers and students looking for the latest expertise in connection with key questions in their field, while professors and instructors working in the areas of automotive and motor design engineering will also find summaries of industry events they weren’t able to attend. The proceedings also offer valuable answers to the topical questions that concern assessors, researchers and developmental engineers in the automotive and supplier industry, as well as service providers.

Weitere Bände in der Reihe http://www.springer.com/series/13360

Michael Bargende · Hans-Christian Reuss · Andreas Wagner (Hrsg.)

20. Internationales Stuttgarter Symposium Automobil- und Motorentechnik Band 1

Hrsg. Michael Bargende FKFS/IVK Universität Stuttgart Stuttgart, Deutschland

Hans-Christian Reuss FKFS/IVK Universität Stuttgart Stuttgart, Deutschland

Andreas Wagner FKFS/IVK Universität Stuttgart Stuttgart, Deutschland

ISSN 2198-7440  (electronic) ISSN 2198-7432 Proceedings ISBN 978-3-658-29942-2 ISBN 978-3-658-29943-9  (eBook) https://doi.org/10.1007/978-3-658-29943-9 Die Deutsche Nationalbibliothek verzeichnet diese Publikation in der Deutschen National­ bibliografie; detaillierte bibliografische Daten sind im Internet über http://dnb.d-nb.de abrufbar. © Springer Fachmedien Wiesbaden GmbH, ein Teil von Springer Nature 2020 Das Werk einschließlich aller seiner Teile ist urheberrechtlich geschützt. Jede Verwertung, die nicht ausdrücklich vom Urheberrechtsgesetz zugelassen ist, bedarf der vorherigen Zustimmung des Verlags. Das gilt insbesondere für Vervielfältigungen, Bearbeitungen, Übersetzungen, Mikroverfilmungen und die Einspeicherung und Verarbeitung in elektronischen Systemen. Die Wiedergabe von allgemein beschreibenden Bezeichnungen, Marken, Unternehmensnamen etc. in diesem Werk bedeutet nicht, dass diese frei durch jedermann benutzt werden dürfen. Die Berechtigung zur Benutzung unterliegt, auch ohne gesonderten Hinweis hierzu, den Regeln des Markenrechts. Die Rechte des jeweiligen Zeicheninhabers sind zu beachten. Der Verlag, die Autoren und die Herausgeber gehen davon aus, dass die Angaben und Informa­ tionen in diesem Werk zum Zeitpunkt der Veröffentlichung vollständig und korrekt sind. Weder der Verlag, noch die Autoren oder die Herausgeber übernehmen, ausdrücklich oder implizit, Gewähr für den Inhalt des Werkes, etwaige Fehler oder Äußerungen. Der Verlag bleibt im Hinblick auf geografische Zuordnungen und Gebietsbezeichnungen in veröffentlichten Karten und Institutionsadressen neutral. Verantwortlich im Verlag: Markus Braun Springer Vieweg ist ein Imprint der eingetragenen Gesellschaft Springer Fachmedien Wiesbaden GmbH und ist ein Teil von Springer Nature. Die Anschrift der Gesellschaft ist: Abraham-Lincoln-Str. 46, 65189 Wiesbaden, Germany

WELCOME IN STUTTGART The car is currently undergoing a complete reinvention. And for us there is a lot at stake: our role as technological pioneers, our economic strength, many jobs and conservation of our natural resources. The Stuttgart International Symposium for Automotive and Engine Technology, now in its 20th year, is intended to enable a fruitful exchange of expertise and creative ideas in order to meet this great challenge. I am delighted to be the patron for this event, and I welcome the participants from all around the world to our state capital! The automotive industry is an especially important component of our economic power, particularly in Baden-Württemberg. Going forward, these key industries must adapt to ecological and political climate requirements. But we can only shape the future of our automotive economy by working together with everyone involved in this process. My state government is also supporting this development with the cross-sector “Baden-Württemberg Automotive Industry Strategic Dialog”, because the transition to sustainable and digital mobility requires expertise from diverse areas – from business, science, trade unions, associations, civil society and politics. With more than 100 lectures and 800 participants, the Stuttgart International Symposium is one of the largest congresses for vehicle and engine development in Europe. So I would like to take the opportunity to thank the organizers of this congress, and wish all the guests inspiring conversations and exciting new knowledge! Winfried Kretschmann Prime Minister of the State of Baden-Württemberg

V

A WARM WELCOME The zero carbon car – technical challenges of the future The mobility transition and intermodal mobility; car sharing versus shared space, digitalization, automation and networking, e-fuels, batteries or fuel cells after all? The current discussions concerning the future of personal transport are generally characterized by uncertainty and open questions, rather than clear answers and confidence. This is perturbing the industry: unsettling it on the one hand and on the other hand making it more important than ever to get to grips with the issues involved. With its focus on “The challenges of future technology” and its diverse program of lectures, the 20th Stuttgart International Symposium grapples with these questions. It hopes to help the industry approach these future-related topics and provide a platform for – potentially controversial – discussions. The program structure has also changed. In response to requests from our participants we are now offering more opportunities for collaboration and networking: » In the World Café, you can work on specific solutions for current problems in our industry. The results of this creative unit will be presented directly to a wide audience directly before the podium discussion. » We'll be celebrating the Stuttgart International Symposium's 25th birthday with a stand party in the exhibition. » A poster session and a tour of the exhibition are further new features. You can also expect some optical changes on location, along with some familiar elements! We are curious to hear your feedback and look forward to seeing you in Stuttgart on March 17 and 18, 2020! Prof. Dr. Michael Bargende Prof. Dr. Hans-Christian Reuss Prof. Dr. Andreas Wagner

VI

INDEX – Volume 1 SECTION 1

STRATEGIES FOR PASSENGER CAR DRIVETRAINS 2030 Chairperson: Prof. Dr. Michael Bargende Passenger car powertrains and future energy scenarios: CO2 compliance versus affordability and lifecycle emissions Günter Fraidl, B. Enzi, Ch. Martin, M. Rothbart, AVL List GmbH

1

The challenges of WLTP emission regulations from the vehicle manufacturer’s point of view Roland Kemmler, C. Müller, T. Deuschle, M. Liebing, S. Tyslik, V. Blum, Mercedes-Benz AG

5

Are hybrid-powertrains the right solutions to meet the EU-emission-targets 2030? Gerald Eifler, A. Dau, M. Wetscher, ElringKlinger Motortechnik GmbH

29

NEXT GENERATION MOBILITY Chairperson: Prof. Dr. Hans-Christian Reuss A mobility study in commercial and industrial areas of Stuttgart – Experiences and conclusions promoting intermodality of commuters Günter Sabow, Wirtschafts- und Industrievereinigung Stuttgart e.V.

53

MobiLab – The mobility living lab at the University of Stuttgart Wolfram Ressel, Universität Stuttgart

55

Future of multi-modal mobility Jürgen Schlaht, Siemens Mobility GmbH

57

VII

INDEX – Volume 1 MOBILITY I Chairperson: Prof. Dr. Ferit Küçükay Increasing Mobility Rainer Röck, Ingenieurbüro Röck

67

Concept people mover of tomorrow Felix Jakob, G. Sapio, N. Starr, AKKA Technologies

69

Downtown delivery last mile with E-van and box body with integral batteries Jürgen Erhardt, Erhardt GmbH Fahrzeug + Teile

81

MOBILITY II Chairperson: Prof. Dr. Lutz Eckstein Emission-free driving Gunnar-Marcel Klein, MANN+HUMMEL International GmbH & Co. KG

87

Pathways to a CO2-free mobility system in Germany from a technological point of view Michael Kühn, P. Burghardt, H.-G. Hummel, E@motion GmbH

89

Potentials for the implementation of emission free autonomous delivery traffic in inner cities Dennis Wedler, T. Vietor, IKT, TU Braunschweig

VIII

105

INDEX – Volume 1 SECTION 2

AERODYNAMICS Chairperson: Dr. Teddy Woll The role of virtual simulation in aero development of Lamborghini SuperCars Antonio Torluccio, G. Arzilli, Automobili Lamborghini S.p.a.

117

Active aerodynamics to increase the features of a motorcycle Giovanni Lombardi, University of Pisa; M. Maganzi, E. Pasqualetto, CUBIT S.c.a.r.l.

135

Efficient CFD methods for assessment of water management Martin Novák, R. Devaradja, J. Papper, Icon Technology & Process Consulting Ltd.; M. Černý, ŠKODA Auto a.s.

151

ELECTRIC MOTORS Chairperson: Prof. Dr. Nejila Parspour Insulation of electrical motors – Potential to increase performance of future electrical powertrains Moritz Kilper, H. Naumoski, Daimler AG

171

eAxle development and optimization regarding NVH, efficiency and power density Andreas Höfer, M. Herbel, D. Schierle, W. Peschkow, P. Hamon, Valeo Siemens eAutomotive Germany GmbH

185

FE-based sensitivity analysis of stator winding geometries regarding bending behavior using flatpack bending technology David Wüterich, M. Kopp, SEG Automotive GmbH; M. Liewald, IFU, Universität Stuttgart

197

IX

INDEX – Volume 1 DRIVING CHARACTERISTICS II Chairperson: Prof. Dr. Frank Gauterin Influence of body-in-white stiffness on elastokinematics Naser Jafarzadehpour, M. Bidlingmaier, Mercedes-AMG GmbH; B. Corves, RWTH Aachen University

209

Ride comfort evaluation of predictive ride height and damper control adaptation on single obstacles Konstantin Riedl, S. Schaer, J. Kreibich, M. Lienkamp, FTM, TU München; S. Cannon, C. Schimmel, AUDI AG

223

Objectification of the feeling of safety at high speed based on the human perception of vehicle motions Martin Heiderich, F. Zantner, H. Shibue, R. Kastner, Honda R&D Europe (Deutschland) GmbH; J. Neubeck, J. Wiedemann, A. Wagner, FKFS

237

TRANSMISSIONS Chairperson: Prof. Dr. Bernhard Geringer Wet clutch as an enabler of cost-efficient hybrid drive systems – Decoupling as functional extension Arne Bischofberger, A. Albers, S. Ott, IPEK, Karlsruher Institut für Technologie (KIT)

251

Objectified evaluation of shifting quality of manual transmissions during real operation Daniel Trost, E. Brosch, H.-C. Reuss, FKFS

267

Gearbox simulation for EVs: Optimization between gear rating, available space and NVH requirements Chhaya Chavan, T. Heidlauf, hofer-pdc GmbH; J. Langhart, KISSsoft AG

281

X

INDEX – Volume 1 EXHAUST GAS AFTERTREATMENT Chairperson: Prof. Dr. Peter Eilts Leveraging big data analysis to enhance the validation of EGT-Systems Nicolas Ide, A. Serout, T. Rankel, T. Dengler, Robert Bosch GmbH

297

Fundamental research on pre-turbo exhaust gas aftertreatment systems Martin Angerbauer, M. Grill, M. Bargende, IVK, Universität Stuttgart; F. Inci, FZA, TU Berlin

315

Pre-turbo DeNOx exhaust gas aftertreatment system for future 48V Diesel powertrains Johannes Hipp, C. Beidl, VKM, TU Darmstadt; D. Knaf, R. Anselm, BIN Boysen Innovationszentrum Nagold GmbH & Co. KG; G. Hohenberg, M. Conin, IVD Deutschland GmbH; J. Kreuz, U. Goebel, Umicore AG & Co. KG

337

VALIDATION Chairperson: Prof. Dr. Klaus Dietmayer Reconstruction of traffic accidents with automated and electrified vehicles Daniel Paula, H.-G. Schweiger, CARISSMA, TH Ingolstadt; K. Böhm, DEKRA Automobil GmbH

357

Efficient usage of abstract scenarios for the development of highlyautomated driving functions Florian Bock, A. Heinz, AUDI AG; J. Lorenz, Luxoft GmbH

373

Vehicle endurance testing through automated test driving Felix Kistler, S. Staudacher, M. Keckeisen, TMT GmbH; Michael Nadj, H.-P. Reifenrath, Mercedes-Benz AG

389

XI

INDEX – Volume 1 SECTION 3

ADAS & AUTONOMOUS DRIVING Chairperson: Prof. Dr. Michael Weyrich AI for new ADAS user interfaces: Opportunities through collaboration or risks? Ulrich Bodenhausen, Vector Consulting Services GmbH and Ulrich Bodenhausen AI Coaching

403

Determination of secured lane information for highly automated vehicles Sven Eckelmann, T. Trautmann, J. Fabich, Hochschule für Technik und Wirtschaft Dresden

411

Virtual validation of autonomous vehicle safety through simulationbased testing Mustafa Saraoğlu, Q. Shi, A. Morozov, K. Janschek, IfA, TU Dresden

419

DRIVING CHARACTERISTICS I Chairperson: Dr. Jens König Empathic assistants – Methods and use cases in automated and nonautomated driving Anna-Antonia Pape, Sonja Cornelsen, V. Faeßler, TWT GmbH; K. Ihme, M. Oehl, U. Drewitz, Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR); F. Hartwich, TU Chemnitz; F. Schrödel, IAV Automotive Engineering; A. Lüdtke, OFFIS, Institut für Informatik; M. Schramm, Soundreply GmbH

435

Approach to objective evaluation of driving behavior with ESCinterventions demonstrated by a lane change maneuver Fabian Fontana, J. Neubeck, A. Wagner, J. Wiedemann, FKFS/IVK, Universität Stuttgart; U. Schaaf, I. Scharfenbaum, AUDI AG

451

Mechatronic system design for EPS systems with residual modes and variable, nonlinear plant behavior Marcus Irmer, H. Henrichfreise, CLM, TH Köln; M. Haßenberg, H. Briese, DMecS GmbH & Co. KG

469

XII

INDEX – Volume 1 SI-ENGINES Chairperson: Prof. Dr. Hermann Rottengruber Design optimization of water-injection-SI-engines by virtual engine development Antonino Vacca, F. Cupo, E. Rossi, M. Chiodi, M. Bargende, FKFS

483

Intake port condensed water injection for a clean natural gas engine: Strategies and restrictions Youssef Beltaifa, J. Judith, M. Kettner, Hochschule Karlsruhe; P. Eilts, TU Braunschweig; M. Klaissle, SenerTec Kraft-Wärme-Energiesysteme GmbH; V. Wiersbitzki, BOMAT Heiztechnik GmbH

499

Experimental study of a free piston linear alternator with an opposed piston combustion chamber Alex Heron-Himmel, S. Schneider, FK, Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR); M. Chiodi, FKFS

519

CHARGING Chairperson: Prof. Dr. Bernard Bäker SkELInG – Scalable EV charging system with central infrastructure and DC distribution grid Taleb Janbein, E. Hoevenaars, T. Weil, B. Bohnet, Robert Bosch GmbH

533

100+ charging points – Grid friendly intelligent load & charge management – ChargeBIG in operation Sebastian Ewert, W. Krepulat, M. Gerstadt, MAHLE GmbH; H. Stamer, eliso GmbH

543

Energy and automotive Ursel Willrett, IAV GmbH

557

XIII

INDEX – Volume 1 ENGINE MECHANICS & MEASUREMENT TECHNOLOGY Chairperson: Prof. Dr. Frank Atzler Digitalization of flow measurement systems, in particular of fuel consumption measurement Heribert Kammerstetter, J. Moik, M. Sammer, M. Berglez, D. Leitner, AVL List GmbH

569

Solution of trade-offs in the development of powertrains by use of online measurement technologies Peter Berlet, A. Jäger, IAVF Antriebstechnik GmbH

579

Study to assess the suitability of C/C-SiC as material for piston rings Alex Heron-Himmel, F. Kessel, Y. Shi, Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR)

589

REPORTS FROM FVV PROJECTS Chairperson: Dietmar Goericke Experimental and numerical investigations of NO2 and HCHO formation in lean gas engines Denis Notheis, U. Wagner, A. Velji, T. Koch, IFKM, Karlsruher Institut für Technologie (KIT); Felix Poschen, M. Olzmann, IPC, Karlsruher Institut für Technologie (KIT)

603

Investigations of interactions between fuels and fuels leading components of plug-in-hybrid electrical vehicles Wilfried Plum, S. Feldhoff, OWI gGmbH; M. Jakob, J. Staufenbiel, Hochschule Coburg

605

(Bio-)Methyl ethers as alternative fuels in bivalent Diesel combustion Martin Härtl, K. Gaukel, D. Pélerin, G. Wachtmeister, TU München; B. Heuser, B. Lehrheuer, T. Ottenwälder, M. Zubel, S. Pischinger, RWTH Aachen University; G. Lautrich, M. Pannwitz, T. Tietze, IAV GmbH; J. Weber, DENSO AUTOMOTIVE Deutschland GmbH; W. Willems Ford Forschungszentrum Aachen

621

XIV

SPEAKERS, CHAIRPERSONS Dr. Rafael Abel TWT GmbH

Lukas Block IAT, Universität Stuttgart

Dr. Tobias Abthoff NorCom Information Technology GmbH & Co. KGaA

Florian Bock AUDI AG

Martin Angerbauer IVK, Universität Stuttgart

Dr. Ulrich Bodenhausen Vector Consulting Services GmbH und Ulrich Bodenhausen AI Coaching

Pier Giuseppe Anselma Politecnico di Torino

Hendrik Bohlen WERUM Software & Systems AG

Thomas Arnold IAV GmbH

Prof. Dr. Stefan Böttinger Universität Hohenheim

Prof. Dr. Frank Atzler TU Dresden

Adrian Braumandl Karlsruher Institut für Technologie (KIT)

Prof. Dr. Michael Auerbach Hochschule Esslingen

Dr. Lisa Braun EvoBus GmbH

Prof. Dr. Bernard Bäker TU Dresden

Chhaya Chavan hofer-pdc GmbH

Thomas Bareiß MdB Federico Coren Bundesministerium für Wirtschaft und Energie TU Graz Prof. Dr. Michael Bargende FKFS/IVK, Universität Stuttgart

Abdülkerim Dagli MicroNova AG

Prof. Dr. Christian Beidl TU Darmstadt

Prof. Dr. Klaus Dietmayer Universität Ulm

Youssef Beltaifa Hochschule Karlsruhe

Prof. Dr. Christof Ebert Vector Consulting Services

Dr. Peter Berlet IAVF Antriebstechnik GmbH

Sven Eckelmann Hochschule für Technik und Wirtschaft Dresden

Lutz Berners Berners Consulting GmbH

Prof. Dr. Lutz Eckstein RWTH Aachen University

Tobias Bieniek Daimler AG

Dr. Torsten Eder Mercedes-Benz AG

Arne Bischofberger Dr. Ulrich Eichhorn IPEK, Karlsruher Institut für Technologie (KIT) IAV GmbH

XV

SPEAKERS, CHAIRPERSONS

Prof. Dr. Helmut Eichlseder TU Graz

Prof. Dr. Bernhard Geringer TU Wien

Dr. Gerald Eifler ElringKlinger Motortechnik GmbH

Dr. Martin Gießler Karlsruher Institut für Technologie (KIT)

Martin Enenkel Jenoptik Optical Systems GmbH

Dietmar Goericke Forschungsvereinigung Verbrennungskraftmaschinen e. V.

Jürgen Erhardt Erhardt GmbH Fahrzeug + Teile Sören Erichsen Ibeo Automotive Systems GmbH Carl Esselborn Dr. Ing. h.c. F. Porsche AG Sebastian Ewert MAHLE GmbH Robert Fechert TU Dresden Prof. Dr. Tobias Flämig DHBW Stuttgart Fabian Fontana IVK, Universität Stuttgart Daniel Förster Mercedes-Benz AG Dr. Günter Fraidl AVL List GmbH Neil Fraser MAHLE International GmbH Prof. Dr. Andreas Friedrich Deutsches Zentrum für Luft-und Raumfahrt e.V. (DLR)

Marcus Goth IVK, Universität Stuttgart Andreas Graf itemis AG Dr. Sebastian Grams SEAT S.A., VW Group Dr. Michael Grill FKFS Moritz Grüninger Karlsruher Institut für Technologie (KIT) Andy Günther TU Dresden Dr. Andreas Haag Robert Bosch Automotive Steering GmbH Walter Haas HUAWEI TECHNOLOGIES Deutschland GmbH Sergei Hahn Robert Bosch GmbH Prof. Dr. Karl-Ludwig Haken Hochschule Esslingen Dr. Michael Harenbrock MANN+HUMMEL GmbH

Prof. Dr. Frank Gauterin Karlsruher Institut für Technologie (KIT)

Dr. Martin Härtl TU München

Markus Geiger csi entwicklungstechnik GmbH

Frank Heidemann SET GmbH

XVI

SPEAKERS, CHAIRPERSONS

Martin Heiderich Honda R&D Europe (Deutschland) GmbH

Pascal Janke HELLA GmbH & Co. KGaA

Alex Heron-Himmel Dr. Heribert Kammerstetter Deutsches Zentrum für Luft-und Raumfahrt e.V. AVL List GmbH (DLR) Satheesh Kandasamy SIMULIA Corporation, A DASSAULT Dr. Alexander Herzog SYSTEMES Company IAV GmbH Daniel Heß IAV GmbH

Roland Kemmler Mercedes-Benz AG

Prof. Dr. Dr. Gerhard Hettich EAST Consulting

Moritz Kilper Daimler AG

Carl Friedrich Hettig FEV Europe GmbH

Dr. Felix Kistler TWT GmbH

Johannes Hipp TU Darmstadt

Manuel Klauß NTT DATA Deutschland GmbH

Christian Hochfeld Agora Verkehrswende

Gunnar-Marcel Klein MANN+HUMMEL International GmbH & Co. KG

Dr. Andreas Höfer Valeo Siemens eAutomotive Germany GmbH Prof. em. Dr. Günter Hohenberg Simon Hummel IVK, Universität Stuttgart Nicolas Ide Robert Bosch GmbH Marcus Irmer CLM, TH Köln Naser Jafarzadehpour Mercedes-AMG GmbH Felix Jakob AKKA Technologies Taleb Janbein Robert Bosch GmbH

Prof. Dr. Thomas Koch Karlsruher Institut für Technologie (KIT) Bernhard Kockoth ViGEM GmbH Dr. Mila Kölbig Deutsches Zentrum für Luft-und Raumfahrt e.V. (DLR) Dr. Jürgen Kölch EVA Fahrzeugtechnik GmbH Dr. Jens König Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR) Felix Korthals Daimler AG Frank Kraemer IBM

XVII

SPEAKERS, CHAIRPERSONS

Prof. Dr. Karl-Ludwig Krieger Universität Bremen

Marius Panzer MANN+HUMMEL International GmbH & Co. KG

Prof. Dr. Ferit Küçükay TU Braunschweig

Dr. Anna-Antonia Pape TWT GmbH

Michael Kühn E@motion GmbH

Prof. Dr. Nejila Parspour Universität Stuttgart

Sebastian Lachenmaier Robert Bosch GmbH

Daniel Paula CARISSMA, TH Ingolstadt

Dr. Andreas Leich Deutsches Zentrum für Luft-und Raumfahrt e.V. (DLR)

Eugen Pfeifer AUTOMOTEAM GmbH

Stefan Lindner Outokumpu Nirosta GmbH Prof. Lennart Löfdahl Chalmers University of Technology Prof. Giovanni Lombardi University of Pisa Sebastian Lutz Karlsruher Institut für Technologie (KIT) Florian Mandl IVK, Universität Stuttgart Nicolas Marmann SET GmbH Wolfgang Müller-Pietralla Volkswagen AG Eiji Nakai Mazda Motor Corporation Dennis Niedballa IVK, Universität Stuttgart Denis Notheis Karlsruher Institut für Technologie (KIT) Martin Novák Icon Technology & Process Consulting Ltd.

XVIII

Prof. Dr. Stefan Pischinger FEV Group GmbH Dr. Wilfried Plum OWI gGmbH Dr. Christoph Pötsch AVL List GmbH Indrasen Raghupatruni Robert Bosch GmbH Joscha Reber EvoBus GmbH Prof. Dr. Dr. Wolfram Ressel Universität Stuttgart Prof. Dr. Hans-Christian Reuss FKFS/IVK, Universität Stuttgart Konstantin Riedl TU München Rainer Röck Ingenieurbüro Röck Martin Rothbart AVL List GmbH Prof. Dr. Hermann Rottengruber OvGU Magdeburg

SPEAKERS, CHAIRPERSONS

Prof. Dr. Günter Sabow Wirtschafts- und Industrievereinigung Stuttgart e.V. Mustafa Saraoğlu IfA,TU Dresden Prof. Dr. Eric Sax Karlsruher Institut für Technologie (KIT) Philip Scarth FPT Motorenforschung AG Jürgen Schenk P3 automotive GmbH Paul Schiffbänker AVL List GmbH Jürgen Schlaht Siemens Mobility GmbH Prof. Dr. Siegfried Schmauder IMWF, Universität Stuttgart Christian Stach Robert Bosch GmbH Robert Stanek P3 automotive GmbH Ulrich Steinbach Ministerium für Wissenschaft, Forschung und Kunst Baden-Württemberg Dr. Antonio Torluccio Automobili Lamborghini S.p.a. Rodolfo Tromellini IVK, Universität Stuttgart Daniel Trost FKFS Antonino Vacca IVK, Universität Stuttgart


Dr. Dig Vijay Gamma Technologies GmbH Prof. Dr. Georg Wachtmeister TU München Prof. Dr. Andreas Wagner FKFS/IVK, Universität Stuttgart Till Wagner Eaton Dennis Wedler IK, TU Braunschweig Dr. Andreas Wegmann J.M. Voith SE & Co. KG | VTA Dr. Christian Weiskirch TRATON GROUP Prof. Dr. Dr. Michael Weyrich Universität Stuttgart Wilhelm Wiebe DHBW Mannheim Ursel Willrett IAV GmbH Johannes Winterhagen Redaktionsbüro delta eta Dr. Teddy Woll Daimler AG Frank Wolter FEV Europe GmbH Kai Wolter Karlsruher Institut für Technologie (KIT) Dr. Johann Wurzenberger AVL List GmbH David Wüterich SEG Autmotive GmbH

XIX

Passenger car powertrains and future energy scenarios: CO2 compliance versus affordability and lifecycle emissions G. Fraidl, B. Enzi, Ch. Martin, M. Rothbart AVL List GmbH

© Springer Fachmedien Wiesbaden GmbH, ein Teil von Springer Nature 2020 M. Bargende et al. (Hrsg.), 20. Internationales Stuttgarter Symposium, Proceedings, https://doi.org/10.1007/978-3-658-29943-9_1

1

Passenger car powertrains and future energy scenarios: CO2 compliance versus …

Abstract Whereas in the past the air quality in metropolitan areas has been in the center of environmental discussions, today global warming and thus reduction of CO2 emissions is the key focus of public interest. Regarding pollutant emissions, the legal limits have been continuously reduced since the 1970s, however, due to a non-representative reference basis – the (N) EFZ test, the actual effect on air quality was significantly under-proportional. Just the transition to more representative test conditions (WLTP, RDE) has brought since 2018 a really significant reduction of actual real-world emissions from new vehicles, even exceeding the nominal reduction of the legal limits by far. As with the definition of RDE legislation, at least initially the focus was on statistically relevant operating conditions, significant improvements of real-world emissions could be achieved within still marketable add-on cost. The actual discussions about post-EU6 legislation, however, seem to be largely detached from cost-benefit considerations and being on a more idealized and emotional level. The requirement to achieve lowest possible emissions under all, i.e. also statistically irrelevant operating conditions, would result in a disproportionate cost increase especially with smaller vehicles, without an adequate improvement of air quality. This would not only eliminate the category of “cheap vehicles” from the market but would also increase the risk of a “loose-loose-loose” situation: reduced affordability of new vehicles (end customer) → extended holding period of old, highly -polluting vehicles → increased fleet emissions (environment) and reduced sales of new vehicles (OEM). A quick and efficient improvement of the imission situation therefore does less require a further tightening of the limit values, but rather a replacement of old vehicles with high emission levels as quickly as possible. With regard to CO2 emissions, the dominance of ICE in the past has given a clear relationship between fuel consumption and climate-relevant CO2 emissions. With batteryelectric or fuel cell vehicles, however, the climate relevance is only precisely characterized by the lifecycle CO2 emission and, at least approximately, described by a Well to Wheel (WtW) analysis. Whereas in Europe a somewhat realistic test cycle (WLTP) was adopted for the future CO2 fleet limit values, the crucial CO2 assessment basis was still retained with Tank to Wheel (TtW). Although this allows impressive “political improvements” (e.g. Europe: 37.5% TtW CO2 reduction by 2030), the actual reduction in climate-relevant CO2 emissions (lifecycle) will only comprise a fraction of these nominal values under the currently foreseeable boundary conditions. Regarding a climate-relevant CO2 reduction, not only the powertrain technology, but above all, the energy supply plays a very central role. If one looks at the diverse aspects

2

Passenger car powertrains and future energy scenarios: CO2 compliance versus … of primary energy generation, storage and provision, it quickly becomes clear that a comprehensive solution does not allow a concentration on just one energy source and one powertrain technology. A completely regenerative energy scenario requires a high degree of storage and transport of energy over longer periods and distances. Consequently, in addition to batteries, chemical energy storage is essential. When using regenerative electrical energy to a large extent directly, battery-electric drives are the best solution for many applications. Based on chemical energy storage, however, both hydrogen-based fuel cells and especially ICE with e-fuels are a much more attractive solution than the current political climate suggests. This makes a close coupling of the transport, energy supply and vehicle production sectors crucial for a fast and effective reduction of climate-relevant CO2 emissions. In the recent years, electrification has led to incredible progress in powertrain technology. By consistently utilizing synergy effects, especially hybridization enables further improvements of the ICE that were considered impossible just a few years ago: 45% maximum efficiency and “zero impact emission” can be represented in the passenger car from a purely technical viewpoint. But this also widens the gap between “technically possible” and “economically reasonable and feasible”. Thus, less the technical feasibility, but rather the best compromise between technical result and affordability becomes the dominant objective for future developments. For a rapid improvement of air quality in cities as well as of climate-relevant CO2 emissions, it is crucial to replace old vehicles with high emission levels by new low emission vehicles as quickly as possible. Regarding the still high emissions from energy supply and the negligible pollutant emissions of future hybrids, in the next few years it will be rather secondary, whether this will be done with pure BEVs, PHEVs or emission- and CO2-optimized hybrids. Consequently, in addition to their specific reduction potential, the affordability of new technologies and thus their fast market penetration are crucial for a rapid improvement in both, air quality and climate-relevant CO2 emissions. Such a comprehensive view and in particular a sufficient consideration of economic and social aspects is difficult to recognize in the current orientation of the European emission legislation. An efficient and effective solution to the core problem of future mobility - sustainability versus affordability - requires an extended definition of sustainability. “Comprehensive sustainability” not only takes environmental aspects into account, but also includes socio-ecological consequences. Such an approach leads to a complementary coexistence of both various energy sources and powertrain technologies. This positive competition will therefore continue to exist over the next few decades.

3

The challenges of WLTP emission regulations from the vehicle manufacturer’s point of view Roland Kemmler, Christoph Müller, Dr. Timo Deuschle, Dr. Manuel Liebing, Sarah Tyslik, Dr. Volker Blum Mercedes-Benz AG

© Springer Fachmedien Wiesbaden GmbH, ein Teil von Springer Nature 2020 M. Bargende et al. (Hrsg.), 20. Internationales Stuttgarter Symposium, Proceedings, https://doi.org/10.1007/978-3-658-29943-9_2

5

The challenges of WLTP emission regulations from the vehicle manufacturer’s point …

1
Introduction Sustainability is one of the basic principles of the Daimler AG corporate strategy and a benchmark for its success concerning the entire value chain - from suppliers to products. A central aspect of Mercedes-Benz Cars is the “path to zero-emission driving” that merges three paths leading to the future of mobility: the combination of very efficient high-tech internal combustion engines, hybrid models as well as electric drives with battery or fuel cell. The focus to which we have committed through Ambition2039: Building vehicles that are attractive to customers and at the same time achieve the own ambitious and go even beyond the legally prescribed sustainability goals. [1, 13] A decisive step to achieve these objectives is a type-approval through emission certification. These certificates are obligatory for the sale of car models, for example in the European Union. In many EU countries, the calculated vehicle tax also depends on certified technical consumption data. Moreover, the EU checks compliance with its own climate protection goals by annually calculating an average EU fleet CO
value for each vehicle manufacturer. In addition, the context of test procedures for newly certified passenger car models in the EU has recently seen a major change. Due to the severe implications this change has for vehicle manufacturers, it is necessary to have a closer look at it. [2] Since 2017, the new Worldwide Harmonized Light Vehicles Test Procedure (WLTP) subsequently replaced the New European Driving Cycle (NEDC) after 25 years, as the valid test cycle for vehicles in the European Union. The purpose of WLTP is to provide realistic test results for fuel consumption and exhaust emissions. WLTP is a standardized laboratory test procedure and as such enables a direct comparison of different vehicles (e.g. regarding vehicle efficiency). This article gives an overview about the new requirements introduced with WLTP in the EU and the challenges it raises for vehicle manufacturers, using the example of Mercedes-Benz Cars.

1.1
A complicated world might be confusing Vehicle efficiency, automotive and CO2 emissions are currently a controversy of the media, politics and in society. The public perception of vehicle manufacturers is often a picture painted by different topics with various contents. This is worth keeping in mind when analyzing the following three aspects, as each of them has two perspectives themselves: fuel consumption on the one and exhaust emissions on the other hand: –
Certification: Testing vehicles on a test bench in the laboratory –
Certification of Real Driving Emissions (RDE) / driving on the road by the customer –
Annual average of each vehicle manufacturers’ fleet (so-called fleet compliance)

6

The challenges of WLTP emission regulations from the vehicle manufacturer’s point …

Figure 1: Consumption-emission matrix.

The technical classification of articles to one of the described topics is often difficult. Therefore, it is important to know how to evaluate them. Figure 1 shows the previously described ‘consumption-emission matrix’ which can be used for classification. The matrix allows distinguishing between different topics such as a communicated standard fuel consumption value (e.g. on a motor show) (topic 1) and certification results of Real Driving Emissions (RDE) (topic 5). The following sections focus on the first column: Vehicle emission certification regarding fuel consumption (topic 1) and exhaust emissions (topic 4) and will only briefly address the remaining points. The distinction between the quantity of fuel consumed (and thus carbon dioxide (CO2) emissions) and the cleanliness of combustion (NOx, etc.) is an important fact: [3] –
Fuel consumption: Depending on many different parameters (combustion engine, the size of the vehicle, driving style of each customer, …) a significant variation in the required amount of fuel consumed can be observed. A main cause of climate change is the increasing concentration of CO
in the atmosphere. For this reason, there is a political and social ambition to reduce further the global average CO2 emissions of future passenger cars and light commercial vehicles. In principle, carbon dioxide is not classified as a pollutant. –
Exhaust emissions: Apart from CO
emissions, other constituents of the exhaust gas are in scope of emission regulations. This refers in particular to nitrogen oxides (NOx) and particulate emissions (PM: particulate matter, PN: particulate number)1, which are taken into account in the assessment of diesel and gasoline engines. Emissions of hydrocarbons (HC) and carbon monoxide (CO) are also limited. 1

All matter distributed in the air and perceptible on filters is termed particulate. Apart from particulate mass, the legislations also set limits for the number of particles.

7

The challenges of WLTP emission regulations from the vehicle manufacturer’s point … Based on these explanations, each field in the ‘consumption-emission-matrix’ contains individual challenges that are holistically related. Due to a combination of stricter standards, continuous development and using complex technology, gaseous emissions have been significantly reduced over the course of the last three decades.

2
Legislation For an overall assessment, it is necessary to have a short look on the steps towards WLTP and the development of legal requirements during the last decades. Figure 2 shows the most important milestones since the beginning in 1967 to the newest regulation – the so-called WLTP 2nd Act.

2.1
Emission timeline The first studies on fuel consumption and exhaust emissions date back to the early 50s of the last century. The results showed that combustion products of passenger cars are contributing to smog formation. As a result, the California Air Resources Board (CARB) was founded in 1967. Simultaneously, the first exhaust legislation for gasoline engines of passenger cars and light commercial vehicles entered into force. [4] On March 20, 1970, the Regulation 70/220/EWG was published in Europe including the first emission limits for gasoline engines regarding CO and HC. In the same decade, in 1978, the DIN 70030, version 07/78 regulated the fuel consumption determination. The next significant step forward followed in 1991 with the Regulation 91/441/EWG.

Figure 2: Development of emission testing requirements (focus EU).

8

The challenges of WLTP emission regulations from the vehicle manufacturer’s point … In 1992, both the New European Driving Cycle (NEDC) as well as the emission standard Euro 1, an exhaust legislations for passenger cars and light commercial vehicles entered into force. In order to check vehicles compliance with emission standards, they were tested according to a standardized and reproducible test procedure. Since the introduction of this Regulation, the limit values of exhaust emissions have steadily tightened. In the 2000s, the Regulation 715/2007, describing PM and NOx emission standards Euro 5 and 6, followed. Euro 6 requirements (laboratory test procedure) became mandatory for new emission types and for all new vehicle registrations in the European Union in September 2014 and September 2015, respectively. The verification of road emissions in RDE levels 1 and 2 is a further tightening. [5] More than 10 years ago, the development of a new worldwide-harmonized test procedure on UNECE level (United Nations Economic Commission for Europe) started. Participants are the EU (represented by the European Commission), Japan, India, South Korea and parties represented by transport & environment. The Global Technical Regulation (GTR No.15) is developed in multiple steps (some of them are still in preparation as of today) and represents a harmonized regulatory technical framework for vehicle emission tests. It functions as a baseline for further national regulations and has several options for the contracting parties (i.e. the regions that decide to apply this regulation). One major challenge in the development of the “UN-WLTP” version are the diverging interests of the different parties involved. This often results in an additional testing burden for manufacturers in practice. Finally, in 2016 - 2017 the European Parliament and EU council/member states decided on the Regulation 2017/1151: type-approval of motor vehicles with respect to emissions from light passenger and commercial vehicles. In July 2017, the final rule of the EU regulation 2017/1151 was released with more than 700 pages. It includes a precise description of testing conditions, testing evaluation and documentation required for passenger car (M12) or light commercial vehicle (N1) emission certification. [5] The timeline for the transition from NEDC to WLTP consists of three steps for Europe (EU27 and UK, also Turkey, Israel, Iceland, Norway, Switzerland): [2] –
September 1st, 2017: The WLTP became mandatory for emission type approval of a new emission type vehicle - class M1. However, the NEDC is still obligatory in some European Member states for checking fleet compliance, customer information and vehicle taxes. In addition to the emission tests in the laboratory, for all new types the exhaust emissions have also to be tested on the road under Real Driving Emissions procedure (RDE).

2

Vehicles for passenger transport with a maximum of eight seats next to the driver's seat - i.e. V-Class.

9

The challenges of WLTP emission regulations from the vehicle manufacturer’s point … –
September 1st, 2018: The entire M1 vehicle portfolio (AT: All types, i.e. all new vehicle registrations) had to be certified according to WLTP. In addition, all new M1 vehicles have to fulfill the PN limit (including conformity factors) in RDE testing. For light commercial vehicles (N1, class II/III), the dates for testing exhaust emissions and CO2 under WLTP and RDE are one year later. –
September 1st, 2019: All new M1 vehicles have to fulfill the NOx limit (including conformity factors, Euro 6d-TEMP) in RDE testing. –
Some member states have different timelines for switching from NEDC to WLTP for vehicle taxation, registration fees and customer information, e.g. customer information is still based on NEDC in Germany. In summary, the lead-time from publication to application of the Regulation has been very short for vehicle manufacturers to convert their entire fleet. As certification tests are usually conducted a few months ahead of market introduction, the effective leadtime was even less than one year, leading to the challenges discussed in this paper. The following chapters explain the contents of WLTP in detail and the associated changes.

2.2
Introduction of the WLTP There are multiple reasons for developing a new worldwide test procedure. The motivation to introduce the WLTP as the future laboratory test procedure for vehicle emissions and CO2/energy consumption is described by three key aspects: [1] –
Consumer interest: Improved consumer information/comparison fuel consumption –
Industry interest: Harmonization of tests and requirements –
Social interest: Incentives to develop most efficient technologies under real-life conditions to reduce fuel consumption As described in chapter 2.1, the motivation to develop this test procedure on UNECE level was the introduction of a globally harmonized test procedure for the determination of exhaust emissions and energy consumption of passenger cars and light commercial vehicles (up to approx. 3,5 tons). This procedure should be valid for a broad range of powertrains from pure internal combustion engines over multiple types of hybrid vehicles up to pure electric and fuel cell vehicles. Especially for vehicles with an electric motor and a rechargeable electric energy storage system, REESS, detailed additional provisions are required. The new test procedure for roller dynamometer test benches consists of two parts: First, a defined driving cycle and second, a precise test procedure describing how tests have to be prepared, driven and analyzed.

10

The challenges of WLTP emission regulations from the vehicle manufacturer’s point … The vehicle is driving the cycle on the test bench in the emission laboratory with a standardized speed curve. The test procedure includes, for example, precise requirements on temperatures (oil, cooling water, test bench, etc.) as well as the state of charge (SOC) of the vehicle service battery. Under WLTP, vehicles with a manual transmission have individual gearshift points in contrast to the NEDC. This new test procedure provides comparable, reproducible and more realistic results under laboratory conditions. The development of WLTP (Worldwide Harmonized Light Vehicles Test Procedure) started with the ambition of establishing a globally valid test cycle. However, things look different in 2020. The WLTP standard applies in several regions (e.g. EU, Japan, South Korea and China) but the testing conditions are differing in detail between markets, as some did either not decide to apply the WLTP at all (e.g. the US) or are still using the previous NEDC (ECE-countries such as Russia or Australia).

2.2.1
Worldwide Harmonized Light Vehicles Test Cycle (WLTC) Testing in the laboratory under standardized conditions is a fundamental element of emission certification. An operator drives a representative vehicle of an emission type on a roller dynamometer, with a predetermined testing mass. The legally prescribed velocity-time-profile defines the driving cycle and the driver has to follow the target curve as closely as possible. All deviations are corrected in the CO2 value afterwards. The previous test procedure NEDC was not based on real-driving data and lead to a deviation between certification requirements and customer driving on the road. For this reason, the WLTC derives from real-life driving data. Multiple road tests have been analyzed and aggregated to a representative speed profile. As a result, a cycle of four phases was created for Europe. The key innovations are higher loads, greater dynamics and less idle times in the cycle. All phases of this WLTC and the differences in comparison to the NEDC are displayed in detail in figure 3. In contrast to the NEDC, the WLTP driving cycle lasts ten minutes longer and includes only 13 % stopping time. The length of the entire cycle is more than 23 kilometers, i.e. more than twice the distance of the NEDC (11 kilometers). A broader range of driving situations, e.g. more frequent but shorter stand phases (stop-and-go traffic in the city) characterize the WLTC. It also subjects the vehicle to stronger variations in speed with more dynamic and representative acceleration and braking processes and at higher average speeds of up to 131 km/h. [2] As already mentioned before, the determination of the gearshift points for cars with manual transmission is another new feature because the gear ratio set in every driving situation is essential for fuel consumption. While fixed shift points had been specified in the NEDC, WLTC uses an algorithm to specify an individual shift behavior for each vehicle, depending on the respective powertrain characteristic.

11

The challenges of WLTP emission regulations from the vehicle manufacturer’s point …

Figure 3: NEDC vs. WLTC. [2]

2.2.2
Worldwide Harmonized Light Vehicles Test Procedure (WLTP) In addition to the new test cycle, the underlying test conditions and test procedures are essential for the emission results. To increase reproducibility, tolerances are tighter and provisions are more detailed (compared to NEDC). Under NEDC, after vehicle soaking (6 – 36 hours), the temperature at the beginning of the test has to be between 20 °C and 30 °C with a deviation of ± 2 K compared to the test bench temperature. WLTP in comparison states, that vehicle soaking (6 – 36 hours) takes place at a set point of 23 °C ± 3 K. Moreover, when starting a WLTC test, the temperature of motor oil and cooling water has to be 23 °C ± 2 K. [5] WLTP type 1 measurements (i.e. tests for determination of exhaust emissions including CO2 emissions) take place at 23 °C instead of the European average temperature of 14 °C. An implementation of the complete certification at 14 °C would not make sense from an energetic point of view (conditioning of test benches). Nevertheless, testing at 14 °C provides CO2 emission results that are more realistic as the test corresponds to the average annual real driving situations in the European Union. In order to describe the deviation of CO2 results between 14 °C and 23 °C, the ambient temperature correction test (ATCT) was introduced. It determines a so-called family correction factor (FCF) which is applied to all test results at 23 °C afterwards. [5] Under NEDC, only base variants (e.g. tires and different body types) testing was needed for emission type approval. Therefore, all other optional equipment was out-of-scope. In comparison, WLTP reflects optional equipment in the CO2 test results. Vehicles with similar powertrain characteristics (e.g. same combustion type and engine displacement, same gearbox type and axle ratio, similar or same exhaust after-treatment components) are bundled in so-called interpolation families. This leaves manufacturers to options:

12

The challenges of WLTP emission regulations from the vehicle manufacturer’s point … 1.
Test only the vehicle with highest energy consumption and certify all other vehicles based on its values. 2.
Test the vehicles with the lowest (VL: “Vehicle Low”) and the highest (VH: “Vehicle High”) consumption out of all variants in this family (based on body type and optional equipment with impact on rolling resistance, aerodynamics and vehicle mass). Then interpolate the values for CO2, fuel consumption and electric energy consumption/ electric range based on their amount of equipment for all other vehicles. This way, every vehicle gets individual values. The CO2 emissions per family cannot deviate by more than 30 gCO2/km for conventional vehicles - even lower ranges apply for hybrid vehicles. Otherwise, additional families have to be tested. Figure 4 illustrates an individual customer vehicle between the minimum (VL) and the maximum (VH) scenario of mass, aerodynamics and roll resistance (passenger car tests work with a load of 15 %). The point in the middle of the cube represents an individual configuration for equipment variants with a consumption value higher than the Vehicle Low value in the same family. This method allows covering several components relevant for emission and fuel consumption, incl. any combination of optional equipment. The responsible type approval authority has audited the entire process of determination, calculation and documentation of emission values for every vehicle prior to first WLTP approvals.

Figure 4: CO2-family.

2.2.3
CO2MPAS-Tool In 2014, the European Parliament decided to apply NEDC-based targets until 2020. This leads to a potential double testing for manufacturers, as both NEDC and WLTP are in effect for the time since the introduction of WLTP until 2020. However, the complex simulation tool CO2MPAS can be used to derive NEDC values out of WLTP type

13

The challenges of WLTP emission regulations from the vehicle manufacturer’s point … 1 tests for all conventional vehicles (with a combustion engine only). The technical service (TS) document a large number of signals in the certification tests that are required for CO2MPAS input files. If this simulation tool does not confirm the value declared by the manufacturer, a physical test according to current NEDC provisions is required. Hybrid electric vehicles always require physical testing. Besides this requirement, CO2MPAS input files are also mandatory for all hybrid electric vehicles from 2020 onwards, requiring further signal documentation resulting in an additional testing burden for manufacturers.

2.3
WLTP – 2nd Act In November 2018, the EU published an overall update of the WLTP regulation, which, after a lead-time of less than two months, came into effect for new emissions types in 2019. The new EU Regulation 2018/1832, the so-called WLTP 2nd Act, adds another 300 pages to the EU regulation 2017/1151. It includes all recent requirements on UNECE-level of the WLTP Global Technical Regulation No. 15 (up to Amendment 4) as well as many EU-specific requirements. This overall WLTP regulation update results in a recertification of the entire vehicle portfolio. Following, some detailed information about the WLTP 2nd Act: [5] –
Introduction of new provisions for the determination of gearshift points (manual transmission vehicles) to improve drivability of target curve for vehicles with low engine power in relation to vehicle mass. The modifications of calculation lead to new gearshift points for most manual transmission vehicles. This makes it difficult for manufacturers to get approvals under the WLTP 2nd Act for gearshift tests performed under the WLTP 1st Act regulations. From a testing perspective, it is almost impossible to re-certify all manual transmission vehicles within lead-time. –
Implementation of the concept of drive trace indices (DTI): these coefficients are calculated for every WLTC test driven on test benches for all types of powertrain and have to remain within ranges specified under the WLTP 2nd Act regulation. They analyze whether a driver follows the target curve too aggressively or in a conservative way. In the EU, two coefficients (IWR: Inertial Work Rating, RMSSE: Root Mean Squared Speed Error) must remain within a predetermined range, otherwise the test is not valid. This is an additional aspect of tightened tolerances under WLTP. DTIs can be calculated ex-post for tests performed under WLTP 1st Act. If they are valid, a drive trace correction for CO2 is calculated (for all conventional driven vehicles), as described in chapter 4. If the DTI exceed the limits, the test is not valid and additional tests are required. –
The EU commission wants to analyze the deviation between certified values and on the road values (over time) of fuel consumption. The new EU Regulation on CO2-

14

The challenges of WLTP emission regulations from the vehicle manufacturer’s point … fleet targets (2019/631) details this further. All newly type approved passenger cars must be equipped with an On Board Fuel Consumption Meter (OBFCM) by 2020. One-year later, all newly registered vehicles must be equipped with this system. It accumulates the total fuel- and energy consumption over the vehicle lifetime and its data can be readout via the On Board Diagnostic (OBD)-interface. Delegated acts of EU regulation 2019/631 will detail this further. [6] Manufacturers demonstrate the accuracy of this system in WLTP certification tests. For this purpose, the fuel consumption value calculated out of the gaseous WLTP Type 1 test results should not deviate by more than ± 5% from the value calculated by the OBFCM device for Vehicle Low and High. –
Besides the emission roller test benches (where a driver follows a target curve), WLTP 2nd Act tightened another laboratory test. A new test procedure with a separate GTR (No.19) for evaporative emissions (also called Sealed Housing for Evaporative Determination (SHED)/ Type 4-Test) was developed during the last years on UNECE-level. According to WLTP 2nd Act, every new vehicle registered in the EU with a gasoline engine from September 2019 onwards, has to be certified according to the new requirements. –
Vehicles in the market with a driving range of 15,000 - 100,000 km and an age between 6 months and 5 years are tested under In-Service-Conformity conditions. These requirements were also tightened with the WLTP 2nd Act and the evaluation procedure of the tests became more stringent. The manufacturers perform, and the type-approval authority audit these tests. In the future, an EU-wide platform will be available, providing data for independent third party testing. –
The EU also published the Real Driving Emissions (RDE) Package 4 as part of the WLTP 2nd Act. Chapter 4.3 provides further information on RDE. All those requirements, in particular the new evaporative emissions test procedure and the new In-Service, led to a re-certification of the entire vehicle fleet between 2018 and 2019, even though the WLTP was introduced just one year before. After summarizing WLTP 1st and 2nd Act, it becomes clear that the transition to a more dynamic driving cycle was only one aspect challenging vehicle manufacturers. All these requirements have a significant impact on test procedures in the laboratory themselves and the amount of testing. In Addition, the shorter lead-times from announcement to implementation of legislative requirements raise the need for parallel testing.

15

The challenges of WLTP emission regulations from the vehicle manufacturer’s point …

3 Three paths lead to the future of mobility Mercedes-Benz Cars relies on a three-lane strategy to reduce emissions sustainably and to comply with stricter emission regulations for CO2 and other pollutants. These three paths include different powertrains with state-of-the-art engines and exhaust technology. Together they form the new product and technology brand EQ: EQ Boost (electrified combustion engines), EQ Power (plug-in hybrids) and EQ (pure electric vehicles). EQ Boost and the EQ Power both include gasoline and diesel engines. [1] With this strategy, Mercedes-Benz underlines the importance of internal combustion engines. Its modular electrification offers a variety of possibilities, like the equipment with a 48-volt technology. The focus is on a proportional increase of purely electric vehicles in the portfolio. With this multi path approach, Mercedes-Benz is able to make a successful transition to the future of mobility. This transformation is associated with an immense R&D and certification effort. Especially if there is a major change in legislation, like the update of WLTP 1st to 2nd Act. Many processes and measuring techniques (combustion engines: emission measurement technology, pure e-vehicles: charging current measurement equipment) show the additional expenditure. The same development goal applies to all three paths: Full compliance with all WLTP legal requirements and successful confirmation in the certification measurements.

3.1 Everything new to the old – Highly efficient internal combustion engines with increasing electrification The optimization of modern internal combustion engines is an important part in the corporate strategy for sustainable mobility at Mercedes-Benz Cars. Due to the considerable advances in emission reduction technologies in recent years, further optimization of both gasoline and diesel technologies during this transition period are beneficial. Highly efficient high-tech combustion engines with partially increasing electrification have a significant impact on reducing CO2 emissions and at the same time comply with the strict emission regulations, shown on the example of the M 264 and the OM 654q: About two years ago, Mercedes-Benz introduced the new 4-cylinder gasoline engine generation M 264 with the E-Class Coupé. In addition to the twin-scroll turbocharger, the engine's special features include a belt-driven 48-volt starter generator (BSG). The combination of starter and generator supports the internal combustion engine with an output of approx. 10 kW at start, acceleration and recuperation. Consistent downsizing in combination with improved engine friction, the use of the valve lift switchover CAMTRONIC and the BSG in particular, has led to a considerably consumption improvement to equivalent 6-cylinder engines. The further development of the proven

16

The challenges of WLTP emission regulations from the vehicle manufacturer’s point … BlueDIRECT combustion process with the piezo injectors and good mixture preparation, combined with the gasoline particulate filter ensure low emission levels. [7] The OM 654q diesel engine is the latest member of the current Mercedes-Benz engine family FAME (Family of Modular Engines) and was introduced in January 2019 together with the newly developed 8-shift 8G-DCT dual-clutch transmission. As one of the first engines ever, the two-liter diesel (OM 654q) in the B 200 d/B 220 d (combined fuel consumption: 4.5-4.2 l/100 km; combined CO2 emissions: 119-112 g/km) complies with the Euro 6d standard (RDE stage 2), which is required for new types since the beginning of 2020. State-of-the-art engine technologies (e.g. nanoslide coating cylinder runways, steel pistons with stepped piston trough, multi-way EGR, etc.) and additional exhaust after-treatment components (such as the near-motor SCR exhaust system and the underbody SCR/ASC catalytic converter (see figure 5)) comply with the highest exhaust emission standard EU6d and therefore are inconspicuous even under real conditions with regard to NO2 emissions. Strong efforts in engine application, OBD monitoring and emission protection support the hardware components. With the lowest emissions and CO2 values, modern diesel engines like the OM 654q will continue to be an important component in Mercedes-Benz's portfolio in the future. [1, 8]

Figure 5: OM 654q: Near-engine-mounted components. [8]

3.2 EQ Power and EQ: The best of two worlds and the next level The label EQ Power offers even more electrics: Plug-in hybrids are a key technology on the way to a locally emission-free automotive future. Mercedes-Benz Cars is one of the few manufacturers on the market to combine gasoline and diesel engines with plugin technology and offer the best possible combination of combustion and electric drive. Plug-in hybrids offer the benefits of two worlds: In urban conurbations, they drive purely electrically, whereas for long distances they benefit from the range of the internal

17

The challenges of WLTP emission regulations from the vehicle manufacturer’s point … combustion engine. They increase the vehicle efficiency even further, because they can recuperate energy and allow the internal combustion engine to drive at low operating points. The intelligent, route-based operating strategy takes navigation data, topography, speed regulations and traffic conditions into account for the planned route. [1] The largest member of the EQ Power family, the Mercedes-Benz GLE 350 de 4MATIC (weighted fuel consumption 1.1 l/100 km, weighted CO2 emissions 29 g/km, weighted power consumption 25.4 kWh/100 km) combines the new diesel engine OM 654 with the new 9-shift hybrid transmission 9G-TRONIC to make the next leap in range. High potential comes from recuperation over all four wheels with a maximum recuperation torque of 1,800 Nm and a large battery (a special shell and a modified rear axle create battery space) that enables a range of around 100 km. The GLE 350 de 4MATIC promises to increase the experience of locally emission-free mobility and at the same time offers emotional driving pleasure. The plug-in hybrid powertrain from Mercedes-Benz in the compact car segment is based on the 1.33-litres 4-cylinder gasoline engine M 282 (figure 6). It combines sustainable mobility with driving dynamics and comfort and sets standards for electric suitability for everyday use with a minimum fuel consumption. The powertrain offers about 70 km of electric range and an innovative frontend exhaust system, an engine-related close coupled catalyst as well as a gasoline particle filter also ensure low emission levels for EQ Power vehicle. [9, 10] The third path, the brand EQ completes the electric offensive at Mercedes-Benz Cars. After the smart EQ models, the Mercedes-Benz EQC is the first electric SUV. Smart is also the first automotive brand to strive for a consistent switch from the incinerator to the electric drive. Even light commercial vehicles are already part of locally emissionfree electric mobility (e.g. eVito, eSprinter). By 2030, total sales of plug-in hybrids and all-electric vehicles from Mercedes-Benz Cars make up more than 50 %, depending on customer preferences and the development of public infrastructure. [1, 11, 13]

Figure 6: Plug-in hybrid powertrain from Mercedes-Benz for the compact car segment. [10]

18

The challenges of WLTP emission regulations from the vehicle manufacturer’s point …

4 Challenges for certification procedure The previous chapters show the impact of the new WEU-certification process for Mercedes-Benz Cars as a vehicle manufacturer. The following pages explain in detail the fuel consumption and emission certification scopes with focus on the certification laboratory.

4.1 Challenge across all departments Type-approvals confirm that the legal safety and environmental standards are met. The whole process for type-approval of fuel consumption and exhaust emission consists of four main steps with a variety of requirements, as shown in figure 7. The performance of certification tests in the laboratory is only one aspect, but it is this topic, that the public associates with the changes made by WLTP. However, its effects are much broader.

Figure 7: Consumption – emission – type approval.

4.2 Challenges in the laboratory A fundamental step in the approval procedure is the emission certification. It is granted through emission and consumption tests in the presence of a technical service on roller test benches in the emission laboratory. In addition, road trips are conducted in accordance with the RDE regulations. Figure 8 summarizes the key topics with the intent to explain the challenge of WLTP for the laboratory and its interfaces. The effects are additional work, longer testing processes, post-processing as well as documentation.

19

The challenges of WLTP emission regulations from the vehicle manufacturer’s point …

Figure 8: Challenges of WLTP for the laboratory and its interfaces.

Besides roller test benches, the emission laboratories have another test facility: the socalled SHED chambers to measure evaporative emissions within the new WLTP EVAP regulation (short for evaporation emission). The GTR No. 19 as a part of WLTP 2nd Act offers detailed descriptions. Combined with PEMS (Portable emissions measurement system), which determines the real driving emissions (RDE), these measurement technologies form the pillars of measurement compliance with the EU Regulations.

4.2.1 Roller test bench Mercedes-Benz uses more than three dozen roller test benches for development, certification and quality management on three continents (Europe, USA and China). With the introduction of the new WLTP legislation and the associated new test cycle WLTC (see chapter 2), the certification effort has increased considerably, also because of the special requirements for new technologies, such as plug-in hybrids and electric vehicles (see chapter 3). The certification measurements in the Mercedes-Benz emission laboratory are not carried out for only EU type-approvals, but also for almost all markets worldwide. This means that the WLTP is only one of several large-scale projects of the regulations worldwide and requires continuous development and revision of existing plants and processes. All this applies, of course, for the entire Mercedes-Benz Cars and Vans model range. The cost of certification has increased drastically during the WLTP phase-in over the last years. The required total dynamometer time, for example, almost tripled between 2016 and 2018 and is still rising. The main reason for this besides quality checks is the necessary recertification of many vehicles in order to meet WLTP regulations and the 50 % increased time of WLTC as well as the more complex range tests for electrified

20

The challenges of WLTP emission regulations from the vehicle manufacturer’s point … vehicles. Repeated measurements are potentially possible due to more tightened boundary conditions and CO2MPAS NEDC validation measurements. Especially the new additional measurements account for a significant part of the total expenditure (for example, recording vehicle energy charging and cooling behavior). Quality verification require a high additional amount of laboratory work. It is essential for certification operation to present a periodical inspection of measuring devices, including required documentation. Special measuring instruments check the accuracy of the test equipment daily and automated maintenance is carried out across the whole test field. Due to the increasing demands, Mercedes-Benz invested heavily in more capacity. The vast majority of roller-wheel-drive test benches in the Mercedes-Benz emission laboratory are all-wheel-drive test benches to meet the latest requirements of certification and development work. In order to facilitate a three-shift, the certification laboratory includes a large vehicle storage area for more than one hundred vehicles over several floors with an automated storage system (elevator). There, the vehicles including all equipment (coolants, oils), are pre-conditioned for the measurements; this procedure is called “soak”. The pre-conditioning happens on respective soak surfaces with temperatures defined by the certification requirements (-7 °C to 23 °C). The complexity arises from the interaction of all facilities for laboratory operation: vehicle preparation and documentation area, vehicle soak points, emission roller test benches, particulate weighing system, fuel depot, evaporation chambers (SHED), etc. Figure 9 gives some impressions of the Mercedes-Benz emission laboratory.

Figure 9: Emission laboratory. [1]

21

The challenges of WLTP emission regulations from the vehicle manufacturer’s point … At least two vehicle variants are tested per vehicle family during a certification process with only one physical vehicle over different inertia classes: the configuration with the lowest CO2 emissions (VL) and those with the highest (VH) (see chapter 2). A WLTC emission measurement on the roller dynamometer, including installation and dismantling, takes more than one hour. However, testing one single cycle is not enough: The WLTP certification includes an extensive test program, from test preparation and vehicle checks by the technical service to the completion of all required measurements, including additional RDE measurements on the road. Figure 10 shows an exemplary certification process including various tests. However, each process differs based on the market and technology. Depending on the vehicle type and vehicle family, the certification of a single vehicle model on emission rollers can take up to several months. Subsequent processes of approval and documentation are following. The time and effort to certify a vehicle with internal combustion engine can be exemplified by a short summary (see following list). The complexity of this process will rise with increasing electrification of the powertrain. If the provision for the temperature changes, a longer soak period between individual tests will be required. Figure 10 points out one more challenge for vehicle manufacturers that is not obvious at first sight: Linked complicated individual process steps. The following list outlines the main steps of the procedure just for emission certification on roller dynamometers of a conventional vehicle without electrification for WEU-certification (without RDE road measurements and without EVAP measurements (Type 4)): –
Certification assignment and vehicle are received –
Parts and vehicle check as well as documentation of the data status are checked along with a technical service to monitors certification –
Further preparatory steps, for example fueling up on standardized certification fuel –
ATCT test (Ambient Temperature Correction Test): Reference test for standardization of the CO2 measurements in line with the average European temperature of 14 °C using a “family correction factor” (FCF) –
Type 1 measurement: WLTP with low and high load parameters, in some cases also a supporting point VM (Vehicle Middle). Optional: NEDC measurement: with different load parameters (VL and VH) –
Type II/III measurements (idle CO and crankcase emissions) after a WLTP VL test –
Logging a vehicle’s cooling behavior following a WLTP VH test –
Type VI measurement: Cold-start emissions at -7 °C –
Determining idle consumption

22

The challenges of WLTP emission regulations from the vehicle manufacturer’s point …

Figure 10: Exemplary certification process.

The certification tests of plug-in hybrids and electric vehicles take a particularly long time and may take place on the same test benches as conventional vehicles. Determining the electrical range of plug-in hybrids and electric vehicles is extremely time-consuming. One part of the certification stipulates that the test cycle must be driven until the internal combustion engine starts up, either because the battery is empty (plug-in hybrids) or until the power output of the battery is no longer sufficient for speed requirements of the cycle (electric vehicles). Depending on the performance of the vehicle and the battery capacity, this may take several hours: For example, the EQC was continuously on the emission roller dynamometer for more than 15 hours until its 80 kWh battery was exhausted. The result: A standard range of more than 400 kilometers (according to NEDC). In addition to determining the electrical range, the battery is used to determine the representative power consumption (required charging energy in Wh up to the full charge of the battery in relation to the distance travelled during the test in km). [1, 11] Figure 11 shows another step in more detail. Each block in figure 10 represents a single certification task which again corresponds to a complex laboratory process. In contrast to vehicles with internal combustion engines, WLTP certification of plug-in hybrids include testing in two modes. High levels of attention are necessary to ensure process reliability, which then implicates an increased personnel requirement. Figure 11 illustrates test cycle, soak time, state-of-charge and temperature and their interactions and interrelationships. The charge-depleting mode (CD) is active when the battery’s energy is used to power the vehicle, gradually depleting the battery’s state-of-charge.

23

The challenges of WLTP emission regulations from the vehicle manufacturer’s point …

Figure 11: Exemplary certification procedure for plug-in hybrids.

In contrast, in charge-sustaining mode (CS) the battery’s state-of-charge is sustained by relying primarily on the internal combustion engine to drive the vehicle, using the battery and electric motor only to increase efficiency and recapture kinetic energy. At various process steps, the battery is charged according to the legal specification.

4.2.2 Test evaluation In addition to the compilation of the various documents, the legally prescribed postprocessing of test results is another important step for type approval. As described in chapter 2, corrections of the measured CO2 value is mandatory required by law and described in the WLTP regulation. Depending on the vehicle’s powertrain, two different evaluation paths exist (see figure 12). One for internal combustion engines with 12volt architecture and one for mild hybrids (48-volt) and plug-in hybrids. In all cases, the relationship between the state-of-charge (SOC) of the vehicle’s batteries compared to the resulting CO2 value must be determined. This complex correction procedure is based on the change in the electrical energy of the REESS (Rechargeable Energy Storage system) and differs between both paths. [5]

Figure 12: Test evaluation procedure. [5]

24

The challenges of WLTP emission regulations from the vehicle manufacturer’s point …

4.2.3 Evaporation emission measurement in SHED chambers Evaporative emission testing is regulated by a separate GTR (No.19) (SHED/Type 4Test) under WLTP 2nd Act (see chapter 2). The GTR No. 19 test procedure includes two sub-tests, the „Diurnal testing“ and the „Canister puff loss loading“ („48 h-Test“). The active charcoal filter is aged prior to those tests, optionally having the type approval authority as witness. Plug-In Hybrid Vehicles have to pass this test with a fully charged traction battery. As the combustion engine may be deactivated for a longer period (i.e. the active charcoal filter cannot be purged), the evaporated fuel has to be stored in sealed tanks.

4.3 RDE According to the Euro 6d-TEMP/ Euro 6d standard, in the WLTP regulation RDE (Real Driving Emissions) tests supplement the laboratory measurements on roller dynamometers. In order to evaluate and limit the actual emissions of vehicles on the road (including nitrogen oxides and particulates), the European Commission has introduced real world testing using portable emissions measurement system (PEMS). In contrast to laboratory testing, the RDE test does not follow a defined driving cycle. Instead, the emission behavior under real driving conditions is checked with legally defined permissible boundary conditions (e.g. temperature, altitude, driving dynamics). The type authority grants a WLTP type-approval only if the manufacturer presents valid RDE test runs and confirms compliance with the RDE requirements. Currently, at least 50 percent of the RDE tests have to be performed by technical services. The process of obtaining valid road emission data can be divided into five process steps and is followed for certification-related development measurements at Mercedes-Benz (figure 13). PEMS are conducted in real traffic. Mercedes-Benz uses various routes and different test drivers. [1, 12]

Figure 13: Procedure of a portable emissions measurement systems test series. [12]

25

The challenges of WLTP emission regulations from the vehicle manufacturer’s point …

5 Conclusion and next challenges In December 2017, Mercedes-Benz presented the new CLS at the LA Motor Show: Daimler’s first passenger car certified according to EU6d TEMP and therefore the new test procedure WLTP. However, this was only the beginning. Since the introduction of WLTP, Mercedes-Benz Cars has been at the top of the registration statistic for vehicles with EU 6d TEMP emission classification. The next level was achieved with the new OM 654q that reaches the Euro 6d standard (RDE stage 2). EQ Power’s GLE with OM 654 sets the benchmark: 100 km of electric range with emission-free driving. And the Mercedes-Benz EQC pioneers the new EQ brand (CO2 emissions combined: 0 g/km). To summarize, many tasks and new complex process steps were introduced with the Worldwide Light vehicles Test Procedure, which are much more than just a new cycle: ATCT, CO2MPAS-Tool, DTIs, OBFCM, RCB and RDE are just a few examples. Together with a demanding timeline, the entire Mercedes-Benz fleet faced and overcame a huge challenge. Key alliance for success has been a motivated and extended team, fabulous cooperation, huge investment in facility and measurement equipment and the trust in Mercedes-Benz attitude „first move the world”. With the beginning of 2020, we can proudly say that the introduction of WLTP has been mastered successfully. However, this is not the end of the line. Further challenges are ahead: US-§1066 legislation, CO2MPAS version 4 for WEU, WLTP introduction in China and Japan. Also further emission reduction in Europe (post EU6 standards) are possible scenarios. The future remains exciting for Mercedes-Benz Cars. But one thing is certain - our path to sustainable mobility: Ambition2039. This means offering our customers performance and luxury from Mercedes and at the same time significantly reducing CO2 emissions per vehicle.

Acknowledgements At this point, we would like to thank all those who, through their support, have contributed to the success of this article. Special thanks goes to Mario Becker, Dr. Christiane Betz, Volker Müller, René Olma and the entire Mercedes-Benz Cars WLTP project team, which has contributed to the success of this challenge.

26

The challenges of WLTP emission regulations from the vehicle manufacturer’s point …

6 Bibliography 1.
TecTalk: Mercedes-Benz Cars Technology Strategy and Emissions: On the road to zero-emission driving, Daimler AG, Stuttgart, February 2019. 2.
https://www.daimler.com/nachhaltigkeit/klima/wltp/, abgerufen am 20.01.2020. 3.
https://www.mercedes-benz.com/de/vehicles/wltp/, abgerufen am 20.01.2020. 4.
https://ww2.arb.ca.gov/about/history, abgerufen am 20.01.2020. 5.
https://eur-lex.europa.eu/, abgerufen am 20.01.2020. 6.
https://ec.europa.eu/clima/policies/transport/vehicles/regulation_en#tab-0-0, abgerufen am 20.01.2020. 7.
Kemmler, R; Kreitmann, F.; Werner, M.; Inderka, R. et al.; Daimler AG: „M 264 – Der neue Mercedes-Benz 4-Zylinder Toptype-Ottomotor mit 48V-Elektrifizierung“; 38. Wiener Symposium, 2017. 8.
Nun, J.; Wieler, A.; Andres, C.; Betz, T.; Daimler AG: „OM 654q – Der erste Mercedes-Benz Vierzylinder-Dieselmotor mit RDE Stufe 2“, in: MTZ 80 (2019), Nr. 7/8, S. 52-60. 9.
https://www.daimler.com/produkte/pkw/mercedes-benz/gle-350-de.html, fen am 20.01.2020.

abgeru-

10.
Gödecke, T.; Schildhauer, C.; Weinert, F.; Frick, A.; Daimler AG: „Der Plug-inHybridantrieb für Kompaktwagen von Mercedes-Benz“, in: MTZ 80 (2019), Nr. 11, S. 32-41. 11.
Schenk, J.; Gauger, J.; Daimler AG: „Mercedes-Benz Goes Electric – such as with the EQC”, 40. Internationales Wiener Motorensymposium 2019. 12.
Betz, C.; Ziegler, A.; Nitzschke, E.; Behrendt, H.: „Einblicke in den Entwicklungsprozess mit portabler Emissionsmesstechnik“, in: MTZ 80 (2019), Nr. 10, S. 50-56. 13.
https://www.daimler.com/investoren/berichte-news/finanznachrichten/20190513ambition-2039.html, abgerufen am 20.01.2020.

27

Are hybrid-powertrains the right solutions to meet the EU-emission-targets 2030? Dr. Ing. Gerald Eifler, Dipl.-Ing. Alexander Dau, Ing. Bachelor Markus Wetscher ElringKlinger Motortechnik GmbH

© Springer Fachmedien Wiesbaden GmbH, ein Teil von Springer Nature 2020 M. Bargende et al. (Hrsg.), 20. Internationales Stuttgarter Symposium, Proceedings, https://doi.org/10.1007/978-3-658-29943-9_3

29

Are hybrid-powertrains the right solutions to meet the EU-emission-targets 2030?

1 Challenge for Future Vehicle Applications In order to keep the global temperature rise within this century below 2°C above preindustrial level, 196 state parties ratified the Paris Agreement in November 2015 [1]. Under this agreement, each country has to determine and plan appropriate measures to mitigate the effects on global warming. The light duty vehicle sector of the European Union has to substantially contribute to these measures since it is responsible for 12% of the total carbon dioxide emissions, which has a main influence on global warming [2]. Based on that, the European Union defined ambitious targets for the next couple of years. Starting in 2020, the entire fleet of a vehicle manufacturer must not exceed an emission of 95 g/km CO2 per car which is equivalent to 4.1 L/100 km or 57.3 mpg. In 2030 the limit will be 60 g/km CO2 per car which is an equivalent to 2.58 L/100 km or 91.2 mpg. These limits have to be met in the WLTP, otherwise the OEMs will be charged a penalty of 95 €/g per car which could easily sum up to several billion Euro in case of violating the targets [3]. There are other air pollutants such as nitrogen oxides (NOx) and particulate matter (PM) that are known for potential health issues. Due to that there is also a strict regulation of these emissions inside the EURO-emission standards. In order to cope with these targets, modern vehicles have to be equipped with complex exhaust aftertreatment systems such as catalytic converters, particulate filters and SCR-systems (selective catalytic reaction). The current EURO-6 standard sets a limit of 60 mg NOx/km for gasoline applications and a maximum particulate number (PN) of 6
1011 #/km [4]. This has to be proven on the road according to RDE-requirements (Real Driving Emissions). Even though there are RDE-conformity factors applied which allow the vehicle to exceed the real world condition by this factor (Figure 1).

Figure 1: European Light Duty Emission Goals until 2030 [5] & [6]

30

Are hybrid-powertrains the right solutions to meet the EU-emission-targets 2030? Nonetheless, these factors will be reduced within the next few years, which challenges the conventional powertrains such as diesel- and gasoline-engines. It is very likely that vehicles with standard powertrains will not achieve the targets, neither in terms of CO2-emission, nor for other pollutants. In order to cope with these issues, the automotive manufacturers invest a lot in research and development of new propulsion systems such as battery electric vehicles (BEV) and hydrogen fuel cells. Both technologies did not achieve a breakthrough yet due to higher costs and insufficient infrastructure. Especially BEV cannot yet compete with conventional powertrains in terms of range and charging-time, which concerns potential customers [7]. A sufficient range can only be achieved by installing a reasonable sized battery pack which increases the weight and costs for the vehicle significantly. Currently, the specific cost for a lithium-ion battery is about 200 $/kWh [8]. Considering a Chevrolet Bolt that has a 60 kWh battery pack, it allows a driving range of 238 miles [9] and the estimated costs for the battery only are quite high, approximately $12,000. Hybrid powertrains are perceived as a proper bridge technology since they combine the advantages of both, conventional and battery electric powertrains. They allow full electric driving for daily use, e.g. to work, and when longer distances need to be overcome, the conventional combustion engine ensures a sufficient range. Hence, the battery of a hybrid car can be designed smaller and the powertrain costs are usually lower than for comparable battery electric vehicles. Also, the hybrid powertrain can be more efficient than conventional ones since they allow to recuperate electrical power while braking the vehicle. Depending on the architecture and system set-up the combustion engine can operate in an optimal operating condition. That is why many investigations predict a significant share for hybrid powertrains up to 76% in the next 10 years (Figure 2).

Figure 2: Scenarios of Future Powertrains in Light Duty Vehicles [10]

31

Are hybrid-powertrains the right solutions to meet the EU-emission-targets 2030?

2 Types of Hybrid Powertrains A hybrid powertrain is defined by the fact that different types of propulsion technology are used to drive the car. Typically it refers to a vehicle that combines a battery electric powertrain and an internal combustion engine. There are several ways to distinguish between different types of hybrid systems. For instance, they can be differed by systems architecture (Figure 3).

Figure 3: Hybrid Powertrains by System Architecture [11]

In a series hybrid, the internal combustion engine has no direct mechanical connection to the wheels but drives a generator which delivers electrical power to an electric motor and charges the battery. The advantage is that the combustion engine can be designed and configured to run in an operating condition with highest possible efficiency. On the other hand, there is always an efficiency chain since the combustion engine needs to transform chemical energy into mechanical energy and the generator into electrical energy. Furthermore, the electrical motor needs to be designed to cover the entire demand of torque and power to sufficiently move the vehicle. An example is the BMW i3 which has an optional two-cylinder gasoline engine available as a range extender. In a parallel hybrid the combustion engine and the electrical motor are mechanically connected by a clutch thus, both can deliver power to the wheels directly. Especially at higher vehicle speeds it has efficiency advantages over the series hybrid since it eliminates the inefficiency of converting mechanical energy to electrical energy.

32

Are hybrid-powertrains the right solutions to meet the EU-emission-targets 2030? Depending on the complexity of the parallel set-up it could be more expensive and complicated in design. Nonetheless, it is the more common type in automotive sector compared to the series version. Examples for parallel hybrids are Chevrolet Malibu PHEV, Honda Accord PHEV and BMW X5 40e PHEV. A mixture of these two types is the power-split hybrid. It can operate in series mode by decoupling the e-drive from the combustion engine which means the combustion engine can charge the battery in optimal operating conditions without a mechanical connection to the axles. At higher vehicle speeds it can be run in a tandem with the e-drive and directly deliver torque to the axles similar to the parallel hybrid layout. This concept allows many different operating modes in order to increase the overall efficiency throughout the required vehicle speed- and load-conditions. Toyota Prius and Chevrolet Volt are designed in this way. Another way to distinguish between hybrid systems is the location of the electric motor (Figure 4) defined as Px-configuration [12]. P0 and P1 are typically mild or micro-hybrid systems with low functionality and a voltage-range between 12 and 48 volt. In the future they will be used mainly in small and compact car segment since they deliver a benefit in fuel economy at low cost and small weight increase. P2 and P3 allow higher functionalities such as energy recuperation during deceleration of the vehicle. They operate in a higher voltage range from 48 volt up to high voltages (~400 volt). P4 and P5 configuration even allow the all-wheel drive functionality since the e-drive is located at the rear-axle and supports the conventional driven front-axle. This concept can be combined with a P2 or P3 configuration to allow high system power in performance cars such as Porsche 918 that has a P2 configuration at the rear-axle and an additional e-drive at the front-axle [13].

Figure 4: Hybrid Configuration by E-Drive Positioning [12]

33

Are hybrid-powertrains the right solutions to meet the EU-emission-targets 2030?

3 European Emission Regulation The European type approval of light duty vehicles regarding to fuel consumption and tail pipe emissions such as HC, CO, NOx remains a continuous challenge for almost five decades. In 1992 the New European Driving Cycle (NEDC) was established in order to determine the fuel efficiency of light duty vehicles considering a mixture of driving conditions to cover urban, extra-urban and highway driving (Figure 5). However, the cycle was defined when the majority of the vehicles where much lighter and less powerful and the roads less frequented. Hence, the correlation between real world fuel consumption and the values determined in the NEDC did not work well.

Figure 5: New European Driving Cycle (NEDC) [11]

The ADAC (German Automobile Club) figured out that the actual fuel consumption of many cars exceed the NEDC-values by up to 40% [14]. Due to public controversies, the necessity of an improved driving cycle has become obvious and led to the conception of the new Worldwide Harmonized Light Vehicles Test Procedure (WLTP – Figure 6) which becomes effective on September 2017 for new type approvals. It contains more severe acceleration and speed conditions and requires the OEMs to consider all possible vehicle options that may have an impact on fuel consumption (e.g. different wheel sizes).

34

Are hybrid-powertrains the right solutions to meet the EU-emission-targets 2030?

Figure 6: Worldwide Harmonized Light Vehicles Test Procedure [11]

Since the NEDC and WLTP are conducted on temperature controlled roller dynos, the vehicle manufacturers usually tend to optimize the exhaust aftertreatment systems only in small operating windows (e.g. temperatures between 20°C…30°C as well as limited speeds and loads). The International Counsel on Clean Transportation (ICCT) released a study in 2014 which revealed that the nitrogen oxides emissions of diesel cars on the road are on average seven times higher than the limit set by Euro-6 emission regulation [15]. Furthermore, the Environmental Protection Agency (EPA) discovered a severe violation of the Volkswagen Group which was using defeat devices in order to operate the engine in an optimal condition when being tested on a roller dyno under certain conditions [16]. These issues emphasized the need of having an additional testing mode for tailpipe emissions closer to real world condition. In 2015, the European Union decided to develop a procedure for Real Driving Emissions (RDE) which became effective as a regulation in September 2017 for new type approvals. It covers a wider range of accelerations, speed and ambient temperatures (Table 1) and ensures a realistic determination of tailpipe emissions. Table 1: Overview of European Emission Testing Cycles [5] & [6] NEDC Applied since 06/1992 Cycle Time 20 min 11 km Cycle Distance Temperature 20°C…30°C 25% Stopping-time 120 kph Max Speed Not allowed Auxilliary Units dyno Test performed on Focus on fuel consumption (CO2)

WLTC 09/2017 30 min 23.25 km 23°C 13% 131 kph No A/C dyno fuel consumption (CO2)

RDE 09/2017 (Pack1) 90…120 min varying -7°C…35°C min. 10 % up to 160 kph all allowed road gaseous and particulate emissions

35

Are hybrid-powertrains the right solutions to meet the EU-emission-targets 2030?

4 Test vehicle Nowadays, the sports utility vehicle segment (SUV) is the most important light duty market for automotive companies. In Germany the share of SUV grew from 2% in 1995 to 31% in 2019 [17] and is expected to keep growing throughout the next years. Hence, it is preferred to choose a SUV for the test campaign. Furthermore, it should be a vehicle which is available with plug-in hybrid-powertrain as well as a conventional powertrain in order to be able to compare both concepts in similar conditions. For the test campaign, the BMW X5 F15 (2018) has been selected. It is available with diesel, gasoline and hybrid powertrains. For the reference measurement, the V6 3.0 TDI was chosen which shows a similar performance to the plug-in hybrid. The technical specifications of both powertrains are shown in Table 2.

Figure 7: BMW X5 F15 / 2018

Table 2: BMW X5 Test Vehicles - Overview of Technical Specifications 



    #
&! $"#
 
! $ ##!'
#' !""" # #'

#
!#
.2+322
/ " $
"$#
. /  4-""
. /

36

3;2
 8-'!
" "#)
4(;;5
< 782
 :
"
$## &-!% 4(367
 8*;
"" 452
 8*4
,322
 384
,



    3:2

./ :5

.-#!/ 6-'!
" "#)
3(;;9
< 572

./ 472

.-#!/ ;*4
,
8*:

.!"",#/ :

$## 4-$!#

-#! &-!% 573

4(527
 8*:
"" 432
 5*6
,322
 9:
,

Are hybrid-powertrains the right solutions to meet the EU-emission-targets 2030?

5 Test Set-Up Figure 8 shows the vehicle set-up for the road tests. The PEM-System was installed at the trailer hitch of the vehicle and connected to the exhaust pipes of the test vehicles. The system furthermore contains a weather station for ambient pressure and temperature which was mounted on the roof as well as a GPS. The high voltage battery of the vehicle which is located in the trunk has been connected with a Klaric High-Voltage measuring-device (Klari-One) to determine the battery energy flow during the test. For calculation of CO2 which results from electrical power grid, the charging efficiency at a standard power socket was determined by an energy logger. Based on that, an efficiency of 71% was measured at a charging power of 2.2 kW (220 Volts / 10 Amps). For the German power mix a CO2 emission factor of 474 g/kWh was considered [18].

Figure 8: Test Set-Up

Figure 9 shows the vehicle speed throughout the RDE-test on the Idstein-route. Urban

(Mainly) Extra-Urban

(Mainly) Highway

Figure 9: Vehicle Speed during RDE Test-Drive

37

Are hybrid-powertrains the right solutions to meet the EU-emission-targets 2030?

6 Comparison between Diesel and PHEV Comparing conventional Diesel-vehicle and PHEV shows significant advantages of the hybrid-drive in the urban section (Figure 10). The battery was fully charged prior to the test and the vehicle was operated in ‘Auto eDrive’ mode, optimizing the powertrain towards efficiency. Even considering the emission factor of the electrical power grid and charging inefficiencies, the PHEV emits 15% less carbon dioxide in the urban section than the diesel vehicle. Focusing only on the emissions of the internal combustion engines, the PHEV even emits 72% less which emphasizes the importance of using renewable electrical energy for electrified vehicles. However, the PHEV loses its benefit while vehicle speed increases since it turned out that the electric drive of the test vehicle operates mainly at speeds below 70 kph. The PHEV uses a gasoline engine which in general has lower overall efficiency compared to diesel engines (25% vs. 33% [19]). Furthermore, the vehicle weight is 160 kg higher than that of the conventional one. This causes higher CO2-emission in the highwaysection. Comparing the efficiency throughout the whole RDE-cycle, both powertrains are on a similar level when considering the emissions caused by the electrical power grid.

Figure 10: Comparison between Diesel and PHEV

38

Are hybrid-powertrains the right solutions to meet the EU-emission-targets 2030?

7 Comparison of States of Charge The comparison of different states of charge (SOC) shows the expected emission deterioration in the urban section as SOC decreases (Figure 11). With zero charge the CO2-emission in all sections is higher than for the diesel vehicle. However, there are significant variations in extra-urban and highway section up to 12% even though there is no impact of state of charge. Furthermore, all tests have been performed by the same driver and same driving style at similar weather conditions. Hence, the variation is mainly caused by the traffic situation. For future test campaigns it is recommended to keep the conditions as constant as possible and to perform at least three tests to create an averaged result.

Figure 11: Impact of State of Charge (SOC)

8 Comparison of Drive Modes There are different drive modes available in the drivers menu of the PHEV to modify the setting towards comfort, sportiness or efficiency. With regards to efficiency there are the options ‘Auto eDrive’ and ‘Max eDrive’ available. The first mode manages the torque-split of electric motor and internal combustion engine in order to increase the overall efficiency. The latter operates as long as possible in fully electric mode, which is assumed to be beneficial in urban sections in order to reduce local emissions. However, the results during the RDE-test show a slightly higher emission of the

39

Are hybrid-powertrains the right solutions to meet the EU-emission-targets 2030? combustion engine in ‘Max eDrive’ mode, even though it did not consume the same amount of electrical energy (Figure 12).

Figure 12: Comparison of Drive Modes

The reason becomes clear in Figure 13, showing the CO2-emissions of the combustion engine in the urban section. During the first 17 kilometers, the ‘Max eDrive’ mode allows full electric driving. However, after state of charge has reached approximately 5%, the vehicle starts-up the combustion engine and is almost not supported by the electric drive. Hence, the powertrain efficiency drops and the cumulated CO2emission rises significantly. After 22 kilometers it even exceeds the cumulated emission of the ‘Auto e-Drive’ mode.

Figure 13: CO2-Emission of Internal Combustion Engine in different Drive Modes

40

Are hybrid-powertrains the right solutions to meet the EU-emission-targets 2030?

9 Recuperation efficiency A main advantage of a PHEV is the capability to recuperate kinetic energy into electrical energy during braking. In order to determine the efficiency of recuperation, a fully electric mountain drive was performed. The vehicle was driven uphill to an altitude of 245 m and same way back in order to measure the energy flow at the battery (Figure 14).

 







Figure 14: Recuperation Mountain Drive

During these tests, a recuperation efficiency of approximately 35% has been measured. This value is limited by several factors. First of all, there are driving resistances that cannot be recuperated since they are converted into heat, such as aerodynamic drag or roll resistance. Furthermore, there are losses in the powertrain such as friction losses of the drivetrain and charge losses in the battery. The charging current at the battery is mainly limited by its size, cooling strategy and the battery management system. Also, the design of the electric motor may limit the maximum possible recuperation. The maximum recuperation efficiency of a PHEV based on these limits is assumed to be 50% [19]. In order to determine the influence of vehicle speed on recuperation, the energy flow into the battery during deceleration has been measured. For this test, the vehicle was accelerated to 90 kph on flat road and slowly decelerated to standstill at 1.5 m/s². A linear correlation between speed and recuperated energy is only observed down to 40 kph (Figure 15). At lower speeds the recuperation efficiency drops and even turns negative below 20 kph. There are two main reasons for that. During deceleration, the braking torque of the electric motor is adding up to the hydraulic braking system. In

41

Are hybrid-powertrains the right solutions to meet the EU-emission-targets 2030? order to have a comfortable and constant braking sensation with decreasing vehicle speed, the electric motor starts to phase out (Figure 16). At speeds below 10 kph, the electric motor significantly drops in efficiency and the braking torque falls to zero.

Figure 15: Cumulated Recuperation Energy during Deceleration

Figure 16: Operation Characteristics of Electric Motor [19]

10 Fuel Economy in WLTP and Optimization Potential RDE-measurements are appropriate to get an indication of the actual fuel economy on the road. However, for the official assessment whether a vehicle meets the European CO2-emission targets, only the WLTP is applied. For conventional powertrains, the WLTC cycle is performed only once. For plug-in hybrid systems it has to be repeated multiple times according to the schematic overview shown in figure 17 [20]. The

42

Are hybrid-powertrains the right solutions to meet the EU-emission-targets 2030? procedure starts with a pre-conditioning cycle with an undefined SOC of the battery. After that, the battery is fully charged and the WLTC cycle is repeated several times until the battery reaches the minimum SOC which is reached when the change of net energy of the battery throughout a cycle is less than 4% of the cycle energy at the wheels. This specific cycle is called transition cycle n where the drive mode changes from charge depletion mode (CD) to charge sustaining mode (CS). Subsequently, a confirmation cycle n+1 is performed and after a 120 min break, the battery is charged to SOC=100% in order to determine the electrical energy EAC. The latter will not be considered in terms of CO2, since the legislation describes the energy from the electrical grid as CO2-neutral.

Figure 17: Schematic Overview of Test Procedure in WLTP [28]

The fuel consumption which is equivalent to the CO2-emission is calculated by:      
  

(1)

Where: C

= weighted fuel consumption in liters per 100 kilometers

C1

= fuel consumption in liters per 100 kilometers in charge depletion mode (CD)

C2

= fuel consumption in liters per 100 kilometer in charge sustaining mode (CS)

UF

= utility factor as a function of the electric range RCDC (Figure 25)

The utility factor has a significant influence on the weighted fuel consumption. The utility factor in accordance to electric range is shown in figure 18. Furthermore, the electrical range which is equivalent to the number of cycles in charge depletion mode, significantly influences the utility factor and hence, the weighted fuel consumption.

43

Are hybrid-powertrains the right solutions to meet the EU-emission-targets 2030?

Figure 18: Utility Factor UF as a Function of Electric Range [20]

In order to determine the CO2-Emissions of the plug-in hybrid test vehicle according to WLTP, a measurement on a roller dyno at company Horiba Europe GmbH in Oberursel, Germany has been performed (Figure 19). Figure 20 shows the results of the pre-conditioning cycle with an SOC of 50%. The CO2-emission in the graph only refers to the internal combustion engine.

Figure 19: Test Set-Up for WLTC-Measurements on Roller Dyno

44

Are hybrid-powertrains the right solutions to meet the EU-emission-targets 2030?

Figure 20: CO2-Emission of an ICE in WLTC pre-conditioning cycle

The results have been incorporated into an inhouse software-tool, called OptiMap. It allows the calculation of CO2-emission, or respectively, fuel consumption in WLTPcycle based on vehicle-data (weight, drag torque etc.), powertrain data (engine torque, speed etc.) and engine map or cycle data from roller dyno. Hence, by variation of input parameters, the benefits of modifications on vehicle and powertrain side can be assessed in this manner. At first, several modifications on the plug-in configuration have been defined for calculation. At first, this trial was done only simulating WLTPcycle as it would be done for conventional powertrains. Table 3: Parameter Variation in OptiMap

45

Are hybrid-powertrains the right solutions to meet the EU-emission-targets 2030? Figure 21 shows the results. The variation of the e-drive mapping in blue towards higher share of the e-drive shows the logical result of reduced emissions by the combustion engine, whereas the emission caused by the electrical grid increases. Same behavior can be observed when increasing the maximum possible vehicle speed in electric mode. However, a larger battery capacity does not generate any benefits. Even an increase of emission can be observed due to the growing vehicle weight while scaling up the battery. This is due to the fact that the WLPC-cycle is still a moderate load profile for the vehicle and the default configuration of the test vehicle will not reach the minimum state of charge.

Figure 21: Results of Parameter Variation, Considering only one WLTC-Cycle

For the analysis according to WLTP-requirements for plug-in Hybrid vehicles, an additional variation of parameters has been done (table 4). A weak point is the engine torque of the electric drive which allows fully electric driving only up to 70 kph and limited acceleration capability. This causes the combustion engine to operate in many conditions such as extra-urban and highway driving. For the parameter variation, the torque capability of the electric drive was increased by roughly 45% from 130 Nm to 190 Nm. The battery size has a significant influence either, since an increasing electrical range causes an increasing utility factor which makes the fuel consumption of the combustion engine less important. It was enlarged by 50% and 100%. The additional vehicle weight due to the enlarged battery has been considered for the calculation with 0.1 kWh/kg.

46

Are hybrid-powertrains the right solutions to meet the EU-emission-targets 2030? Table 4: Parameter Variation in OptiMap  $ % & ' (

    
    
  
!

/'(.   
/(#.
!

/'(.   
/$##.
!

/'(.   
/$##.

!

/'(.
 
 
!%##


  

+ %
  + %
  $& *
  $* '
  $* '
 

!
 $&#
 $+#
 $+#
 $+#
 $+#


 
 %&#(
 %&#(
 %&($
 %&+)
 %$+)


Furthermore, a reduction of vehicle weight is assumed to improve electrical range as well as fuel consumption. In Figure 22, the results of the calculations are shown. The “default configuration” (= series configuration) reaches an emission of 74 g/km which is 57% less than the result in the RDE-study. This can be explained with more moderate vehicle speeds and accelerations in the WLTC-cycle as well as with the artificial calculation method. In this case, the production vehicle would not achieve the target of 60 g/km for 2030. The increase of the electric motor torque by 45% causes an increased CO2-emission by 9.4% which becomes clear when analyzing the amount of driven cycles for the WLTP-calculation (Figure 23). While the default configuration reaches three cycles until the battery reaches the minimum SOC and the confirmation cycle starts, the larger e-drive causes and increased electrical energy consumption and the battery already reaches the minimum SOC after two cycles. Hence, the utility factor in formula 1 decreases due to reduced electrical range and the influence of the ICE-emission in the confirmation cycle grows accordingly. The logical next step is the enlarged battery size by 50% to compensate the increase of electrical energy consumption. The result is an emission of 63 g/km which is close to the future CO2-target. By increasing the battery size by 100%, the CO2-target will be met. Even though an additional weight reduction of 200 kg is assumed to have a significant improvement in fuel economy, the calculation only shows a further improvement by 3.7%.

47

Are hybrid-powertrains the right solutions to meet the EU-emission-targets 2030?

Figure 22: CO2-Emissions in WLTC with Parameter Variation

Figure 23: Required Amount of WLTC-Cycles with Varied Parameters

11 Summary/Conclusions Currently the future emission targets in the European Union are challenging the powertrain and vehicle manufacturers as well as the suppliers. In order to meet the strict emissions targets, most OEMs are focusing on the electrification of their vehicles, mainly in the form of plug-in hybrids.

48

Are hybrid-powertrains the right solutions to meet the EU-emission-targets 2030? In order to verify the performance of these systems and to better understand potential market requirements, a test campaign was performed. It was comparing the CO2emissions of a conventional diesel-powertrain (BMW X5 3.0 TDI) to a plug-in hybrid based on the same vehicle-platform (BMW X5 xDrive40e). The tests have been done on public roads according to RDE-legislation. In addition, a measurement on a roller dyno was used to determine the emission according to WLTP, supported by an inhouse software tool (OptiMap). The results were showing advantages towards the hybrid, in urban section. However, when considering the CO2-impact from the electrical grid, both powertrains are on a similar level. Furthermore, the comparison between WLTP and RDE emissions reveals a strong discrepancy since the WLTP-procedure is based on an artificial calculation, whereas the results of the RDE-cycle are actual values, measured on the road. This is important for the assessment of the actual efficiency of a vehicle since the WLTP is currently used for the official efficiency certification. Based on a simulation, it was shown that moderate technical modifications of the plug-in configuration can easily be used in order to reach the future emission targets, according to WLTP. The test campaign was also revealing some of the downsides of RDE-measurements on the road. Even an experienced driver will face variations in the results of measured emissions due to changing weather conditions and traffic. This impedes the measurement work when focusing on minor parameters. In order to eliminate the impact of environmental conditions, detailed testing on a conditioned test-bench is recommended for future development work. The approach of ElringKlinger Motortechnik will be to support the customers in their development work by operating a flexible powertrain-test bench. It allows the testing of pure powertrains, electrical drives or even full vehicles under stable conditions (Figure 24). It will help to simulate and optimize future complex powertrains, regardless if it is conventional driven vehicle, a full-electric vehicle (BEV) or a hydrogen car.

Figure 24: New Powertrain-Test Bench at ElringKlinger Motortechnik

49

Are hybrid-powertrains the right solutions to meet the EU-emission-targets 2030?

References 1.
https://unfccc.int/process-and-meetings/the-paris-agreement/the-paris-agreement 2.
https://ec.europa.eu/clima/policies/transport/vehicles/cars_en 3.
https://www.vcd.org/fileadmin/user_upload/Redaktion/Themen/Auto_Umwelt/C2Grenzwert/2017_-_ICCT_-_From_Laboratory_to_Road_FactSheet_German __2_.pdf 4.
Commission Regulation (EU) 2016/646 of 20 April 2016 amending Regulation (EC) No 692/2008 as regards emissions from light passenger and commercial vehicles (Euro 6) 5.
European Regulation #2017/1151/EG 6.
European Regulation #715/2007/EG 7.
https://www.tu-chemnitz.de/hsw/psychologie/professuren/allpsy1/pdf/Franke_etal._2014_URI-methods-AHFE.pdf 8.
https://www.ucsusa.org/clean-vehicles/electric-vehicles/electric-cars-battery-lifematerials-cost 9.
https://www.chevrolet.com/electric/bolt-ev-electric-car 10.
http://magazine.fev.com/en/fev-study-examines-drivetrain-topologies-in-2030-2/ 11.
https://en.wikipedia.org 12.
http://schaeffler-events.com/kolloquium/lecture/h3/index.html 13.
www.porsche.com 14.
Frank-Thomas Wenzel: „Sparsam nur im Prospekt“ Frankfurter Rundschau 2014/07/24 15.
https://theicct.org/news/press-release-new-icct-study-shows-real-world-exhaustemissions-modern-diesel-cars-seven-times 16.
https://docs.house.gov/meetings/IF/IF02/20151008/104046/HHRG-114-IF0220151008-SD002.pdf 17.
https://de.statista.com/infografik/18870/neuzulassungen-umsatz-suvs-indeutschland/ 18.
https://de.statista.com/statistik/daten/studie/38897/umfrage/co2-emissionsfaktorfuer-den-strommix-in-deutschland-seit-1990/

50

Are hybrid-powertrains the right solutions to meet the EU-emission-targets 2030? 19.
Küntscher & Hoffmann – Kraftfahrzeug-Motoren, Vogel Fachbuch (2004) 20.
Peter Hofmann – Hybridfahrzeuge, Springer Verlag (2014) 21.
ICCT Briefing Paper - How to measure fuel consumption and CO2 emissions of plug-in hybrid vehicles, today and in the future (July 2017)

51

A mobility study in commercial and industrial areas of Stuttgart – Experiences and conclusions promoting intermodality of commuters Günter Sabow Wirtschafts- und Industrievereinigung Stuttgart e.V.

This manuscript is not available according to publishing restriction. Thank you for your understanding.

© Springer Fachmedien Wiesbaden GmbH, ein Teil von Springer Nature 2020 M. Bargende et al. (Hrsg.), 20. Internationales Stuttgarter Symposium, Proceedings, https://doi.org/10.1007/978-3-658-29943-9_4

53

MobiLab – The mobility living lab at the University of Stuttgart Prof. Dr.-Ing. Wolfram Ressel University of Stuttgart

This manuscript is not available according to publishing restriction. Thank you for your understanding.

© Springer Fachmedien Wiesbaden GmbH, ein Teil von Springer Nature 2020 M. Bargende et al. (Hrsg.), 20. Internationales Stuttgarter Symposium, Proceedings, https://doi.org/10.1007/978-3-658-29943-9_5

55

Future of multi-modal mobility Dipl.-Ing. Univ. Jürgen Schlaht Siemens Mobility GmbH SMO DT TI TIM

© Springer Fachmedien Wiesbaden GmbH, ein Teil von Springer Nature 2020 M. Bargende et al. (Hrsg.), 20. Internationales Stuttgarter Symposium, Proceedings, https://doi.org/10.1007/978-3-658-29943-9_6

57

Future of multi-modal mobility

Abstract Todays’ travelling is a mess. Overcrowded at any transportation mode: in the air, on the road and on rail tracks. Key requirement of end users for passenger and cargo is easy, convenient and affordable in-time door-to-door transportation. The author is proposing a disruptive way to reach these requirements: Not the passenger or the freight is interchanging but will be interchanged in a personalized transportation box, the pod. The pods are standardized and suitable for all transportation modes, according to the actual needs of the end users and the actual traffic situation in the different modes an optimized routing will be calculated and executed. Advantages for the travelers: Maximum convenience through personalized pods and maximum reliability of the journey bey usage of all available transportation modes. Advantages for the environment and the society: the pods are the most time in movement, all pod carriers are electrified and interconnected for maximum efficiency of the system. Keywords: Future Mobility, multi-modal, podimization

1 Introduction What is Mobility? Here we talk about changing the physical position of people or goods. Mobility of mankind for thousands of years didn’t change very much. There was walking by foot, riding animals, later pulling people or goods with carriages. In the beginning powered by human beings, later by animals. A first breakthrough was invention of the wheel. The radius of human activities was increased dramatically. But this status quo lasted very long. The first real disruptive innovation mobility seems to be the invention of the railway system using steel tracks and steel wheels. Through the minimum resistance big loads could be transported very efficient, safe and very independent from weather conditions. The steel railway was basis for economically and socially exploration of the continents. Since invention of the railway system there have be some bigger improvements: motor powered traction, steam engine locomotives, later replaced by electrical locomotives. Trains with locos and passenger cars have been replaced by multiple unit trains. But, that’s it. The railway system of today shows over the last decades only incremental innovations: less weight, less energy consumption, more capacity. A railway system is just the same railway system as 200 years ago. The same thing with the other transportation modes. Since invention of the car in early 1900 years a car is a car: 4 rubber wheels, two head lights, two tail lights, seats for

58

Future of multi-modal mobility driver and passengers mostly in two rows, steering wheel, windscreen, and so on. Since invention of the first car the innovations in automotive are incrementally. Even electrical propulsion systems had been in use more than hundred years ago. A big step for long-distance mobility of mankind was invention of the airplane in the early 1900 years. Like railways and automotive the main technical principle hadn’t changed. Biggest innovation was implementation of jet engines for more speed and greater distances. So, as a first conclusion it can be said that most of the today’s transportation modes have been invented some hundred years ago and have been developed since then only incrementally, reaching physical limits of further developments within their own infrastructures. The continuously growing demand for transportation is asking for new answers on this challenge!

2 How to create a better multi-modal mobility 2.1 The challenge: Continuously growing transportation demand Mobility is growing year for year and brings all transportation systems to the limit. Overcrowded at any transportation mode: in the air, on the road and on rail tracks. Due to efforts to maximize capacity train units are very big and not flexible according to different and quickly changing travelling demands. The cars are unused most of their lifetime and standing cars are filling all the streets in the cities. Traffic jams are daily business. Air traffic is increasing permanently, using nearly 100% non-regenerative fossil energy sources. All these transportation modes are optimizing themselves with few intermodal interfaces. There is few flexibility in using all transportation modes in a coordinated and optimized way regarding energy consumption, travelling time and ecological footprint. Key requirement of end users for passenger and cargo is easy, convenient and affordable in-time door-to-door transportation. Key requirement of the society is sustainable transport with maximum energy efficiency and minimum emissions using regenerative energy sources. The today’s transportation modes are highly developed and at the same time at their limits, further improvement of the global situation is not possible with this “Silo” approach. The good news is, that there are highly sophisticated innovations and developments of general technologies: Automatization and Digitalization.

59

Future of multi-modal mobility Combining the existing infrastructures with fully automated and digitalized “Mobility as a Service” systems could be the way to fulfil the key requirements of end users and society: Not the passenger or the freight is interchanging but they will be interchanged in a personalized transportation box, the pod. The pods are standardized and suitable for all transportation modes, according to the actual needs of the end users and the actual traffic situation in the different modes an optimized routing will be calculated and executed. Advantages for the travelers: Maximum convenience through personalized pods and maximum reliability of the journey bey usage of all available transportation modes. Advantages for the environment and the society: the pods are the most time in movement, all pod carriers are electrified and interconnected for maximum efficiency of the system.

2.2 First answer: Implement Automated Nano Transport System (ANTSTM) Travelling today by air is a mess. Delays, canceled flights, narrow space for the passengers, safety issues and uncomfortable situations e.g. the security check procedure, boarding and deboarding. For example walking for more than one hour in a queue like sheep for the security check at Brussels airport. On the road you can see each day traffic jams end endless streams of trucks and cars. Too much cars and trucks for the existing roads, but with every new road more cars and trucks are there. New streets lead to new traffic. On the other hand you can see the rail tracks most of the time “empty”, but de facto they are fully loaded most of the time. This is artificially generated by the actual signaling and safety philosophy. See the discrepancy between overcrowded streets und “optically empty” rail tracks. You could “fill the empty tracks” with autonomous rail units with own intelligence and sensors on board, recognizing each other, communicating with the other rail units and the intelligent infrastructure. Small rail units are bringing more individuality in traveling, more door-to-door experience. The autonomous rail units are fully electrified with energy storage systems on board, operating in the same smart grids like autonomous road vehicles. The road vehicles will take the first and last mile of the journey. So the rail and road units have to be synchronized permanently. By dividing a rail (or road) car in two parts, the passenger or cargo unit for transportation of passengers and goods (the pod) and the drive unit for the transportation unit (the pod carrier) you can interchange the pod between road and rail pod carriers and vice versa. The author is proposing rail units of 12m length which is a good compromise between riding comfort, capacity and costs per unit. This pod system is called “Automated Nano

60

Future of multi-modal mobility Transport System (ANTS)”. The interior of the ANTS pods can be designed individually according to the needs and requirements of the end users. Maximum standardized in the outer dimensions, in the interior there is maximum flexibility by usage of prefabricated interior modules for the different use cases. The author initialized examinations of the operating model of autonomous rail units like ANTS in the existing rail infrastructure with experts of the university of Aachen, RWTH. It could be shown that ANTS can communicate with each other and intelligent switches without need of additional signaling infrastructure, like autonomous cars and trucks on the roads. Also ANTS and conventional trains can communicate with each other and there can be a co-existence of autonomous rail units and conventional trains on the same rail tracks, see Fig.1. Following the idea of 12m ANTS pods you can create very individualized and optimized interiors with extraordinary passenger experiences. In the “M-Scenario” you have a perfect environment for long distance travelling, better than Business Class Flight. In the “X-Scenario” you have a perfect environment for working alone or in a team, with high-sophisticated Office equipment. The latest ANTS version is the “Diversity ANT”, which is especially designed to be used by all kind off people, as e.g. people with reduced mobility (PRM). Or, for example, parents with little babies. The environment in a Diversity ANT is guaranteeing maximum comfort and dignity for all passengers and this will lead to a democratization of mobility. With ANTS you can have Mobility for All! Following further the idea of having moving spaces of 12m length and 3m width you can leave the pods stationary and you can arrange some or a lot of them to at least temporary “pod-villages” or “pod-cities”. The combination of the maximum standardizes drive units, the rail-pod-carriers, and the maximum individualized pods you can create an unseen variety of use cases and also new business cases. The author started a design competition with students at the university of Aachen, RWTH, to think about the architectonical fusion of mobile ANTS with non-mobile buildings. By combining mobile devices with buildings you can create added value in various aspects. You can integrate ANTS pods in skyscraper structures so you can use the building each time in another way. For example, you can change at the “restaurant floor” of an “ANT-Tower” the catering each week: Italian, Chinese, whatever you want. Or you want to extend your living space at your destination and you are booking extra rooms with lounge furniture, SPA and so on. Additionally, the students developed architectonic models for Mobility Hubs for interchanging ANTS pods between rail and water and rail and street.

61

Future of multi-modal mobility You can also think about usage of drone modules to carry ANTS pods into the air. But… really? The author is thinking that the ANTS concept is very suitable and optimal for the rail operation as such with some good interfaces to road transportation. But for several applications within a holistic multi-modal mobility the ANTS pods seem to be too BIG. For a real multi-modality transport the pods must be smaller.

Figure 1: Operation of ANTS in today’s rail infrastructure

2.3 What is multi-modal mobility? In Fig.2 you see an overview picture for multi-modal mobility. In this picture is shown the different transportation tasks like Urban / Suburban / Regional / Long distance. They have common infrastructures for communication, energy and operation. For the different transportation modes there are different special transportation devices. E.g. on the street there are cars, buses and trucks. In the air there are planes and helicopters/drones. Multi-modal transportation means usage of usage of more than one transportation mode during the journey. The author gives one example for a real use case. The author is living in city A in Germany and his office is located in city B in Germany. The distance between home and office is 19 km. By car this means 20 to 25 minutes travelling time door-to door. Using public transport this means 71 minutes of travelling time: Walking to the bus station – waiting for the bus – riding by Bus – transfer from bus station to train station – waiting for the train – riding by train – transfer from train station to bus station – waiting for the bus – riding by bus – walking to the office. Now you can think about optimization of this journey: Max 1min waiting times (“On demand” bus and train) and 10% higher speed of bus and trains are leading to 50 minutes travelling time.

62

Future of multi-modal mobility This means that the optimization of classical multi-modality has limits in the own system, there are still the walking times and transfer times for the passenger. An optimized multi-modal journey in this case means still double time compared driving with the car! Another way must be found to make public transportation more attractive and competitive compared with the individual transportation od passengers and goods by cars, buses and trucks. All the existing transportation devices can be replaced by pod/pod-carrier systems. According to this philosophy you have standardized and multi-modal usable pods, which are combined with the corresponding pod-carriers for each transportation mode.So, we need standardized and easily interchangeable multi-modal usable pods. For passengers and freight. For all transportation modes.

Figure 2: Overview multi-modal mobility

2.4 Second answer: Implement multi-modal pods (One4All) There are impressive artistic futuristic views of the proposed multi-modal pod system, for each mode as well as for the system integration in the “Big Picture” according to Fig. 3. On the street you can see pods in different sizes with the corresponding pod-carriers. But there is not only the Siemens-Vision One4All of the idea. Some big OEMs like Daimler and Renault launched already similar concepts. For example the vision of Daimler is showing a very flat pod-carrier with the possibility to put passenger pods or cargo pods on top of it. But you can wonder if the pods of Daimler and Renault can be interchanged between their pod-carriers. For that you would need standardized interfaces for mechanics, electronics and electrical equipment.

63

Future of multi-modal mobility In the air you can see pods in different sizes with the corresponding pod-carriers like drones or ropeway systems. Ropeways for the author have some advantages like less noise and more safety, you can call it “guided air traffic”. Not only the Siemens vision can be seen. For example Airbus and Audi launched already an air-street concept, The “Pop.Up Next” concept. A small pod is either transported by an AUDI pod-carrier for road or by a drone package from Airbus. Will the pod of Airbus/Audi be interchangeable with the pod-carriers from Renault and Daimler? Not without standardized interfaces! A real multi-modal approach for mobility of passengers and goods means a lot of standardization work. Also for the aspect of homologation standardization and crossmodal collaboration is mandatory. On rail tracks you see an ANTS-like concept with the difference of smaller transportation units. Passenger pods and cargo pods are combined and integrated in a common rail-pod carrier. These kind of pod trains will be the backbone of future high-speed long-distance transportation of passengers and goods. Due to the big advantages of a steel-steel railway system regarding energy efficiency and therefore the minimum environmental impact as well as the unreached safety is the transportation on railways the most sustainable and recommendable transportation mode. Mass transit should be on rail and long-distance transportation should be on rail, for passengers and cargo. Connectivity and collaboration between the transportation modes will be ensured by the “One4All” pod. One4All means one transportation device for all transportation modes.

Figure 3: Big picture One4All pods

64

Future of multi-modal mobility

3 Conclusions Now the message is: Let’s get compatible! The “Big Picture” is showing all transportation modes mixed and all working together in a permanently synchronized and optimized operational modus. Railway will be the sustainable backbone of future multi-modal mobility, for mass transit as well as for highspeed transportation, for passengers and goods. The first and last mile will be executed by pod carriers in the other transportation modes. All automatized, digitalized and electrified transportation. Door-to-door Mobility-AsA-Service. The podimized mobility will the future of multi-modal mobility!

References 1.
ANTS designed by BMW Designworks 2.
Small pods One4All designed by Moodley industrial design 3.
Operational examinations and technical consulting by RWTH Aachen

(All studies financed 100% by Siemens Mobility GmbH)

65

Increasing Mobility Rainer Röck Ingenieurbüro Röck

This manuscript is not available according to publishing restriction. Thank you for your understanding.

© Springer Fachmedien Wiesbaden GmbH, ein Teil von Springer Nature 2020 M. Bargende et al. (Hrsg.), 20. Internationales Stuttgarter Symposium, Proceedings, https://doi.org/10.1007/978-3-658-29943-9_7

67

Concept people mover of tomorrow Felix Jakob, Giovanni Sapio, Nicole Starr AKKA Technologies

© Springer Fachmedien Wiesbaden GmbH, ein Teil von Springer Nature 2020 M. Bargende et al. (Hrsg.), 20. Internationales Stuttgarter Symposium, Proceedings, https://doi.org/10.1007/978-3-658-29943-9_8

69

Concept people mover of tomorrow

1
Abstract AKKA ranks as the European leader in engineering consulting and R&D services in the mobility sector. As an innovation accelerator for its clients, AKKA supports leading industry players throughout the life cycle of their products with cutting edge digital technologies. Their R&D department “AKKA Research” is proudly presenting a new internal project. The automotive industry is currently in a massive transition phase, which perhaps marks the biggest change since the industrial revolution. Our customers are not only faced with new power systems such as electrical power, new technologies such as autonomous driving and digitalization, but they are also in a strategic transition from traditional car manufactures to mobility service providers. In 2010, AKKA Research faced the challenge of autonomous driving by developing a self-driving car called Link&Go. The final prototype was revealed at the Geneva Motor show in 2013, nearly two years earlier than the presentation of the well-known Google car. One year later in 2014, AKKA Research unveiled the Link&Go 2 concept, which is based on a completely integrated electric platform. By rethinking urban mobility and the surrounding environment, the intelligent platform links inhabitants with other system users. The concept vehicle is fully autonomous and is equipped with several sensors such as cameras and LiDAR systems, which were designed for the city of the future. Based on the experience of Link&Go and Link&Go 2, AKKA Research has started working on a concept for an autonomous people mover of the future. Its main aim is to improve urban mobility and propose a new vehicle concept that meets requirements of future megatrends and adds benefits to the automotive industry. Today’s visions of autonomous shuttles are nothing more than an electrical shuttle moving without a driver. While this is remarkable in itself, AKKA Research believes to be able to go a step further. The AKKA People Mover enables a new approach of mobility and combines several other mobility services within an urban environment. The AKKA People Mover demonstrates innovative approaches in respect to user experience, autonomous platform, powertrain, energy storage, data collection, and IoT among others.

70

Concept people mover of tomorrow

2 Context

Figure 1: Individual transportation has become an issue [2, 3]

In today’s mobility ecosystem, issues surrounding the first/last mile problem, traffic jams and increasing CO2 emissions, as shown in Figure 1, are constantly plaguing individuals and cities around the world. The first/last mile problem is driven by the fact that public transportation does not always pick up or drop off individuals directly where they want to go, often resulting in individuals walking, driving or using other modes of transportation to get to their final destination. This issue of the first/last mile problem, coupled with traffic jams and increasing CO2 emissions, will only continue to grow as present-day cities become megacities. When looking at this trend regarding megacities, one thing is clear: cities are expanding with more people living in them than ever before. Such a trend underlines the need for new approaches towards public transportation to satisfy the needs of modern urban commuters. If new approaches to treat the existing issues with public transportation are not developed, more traffic and congestion will continue to fill cities. While a high percentage of people today have a set routine, current public transportation is not optimized for people’s needs and often does not offer additional services, which are in line to what users actually need or want for their daily commute. Moreover, by looking at the large number of cars parked alongside the streets in cities, one can observe that the power units of these vehicles are sitting idle, with estimates suggesting that they are not used 95% of their lifetime [4].

71

Concept people mover of tomorrow By focusing on current mobility shortcomings, the combination of the potential autonomous capability of vehicles, the underutilized powertrains of vehicles, the congestion and traffic flow of cities and the wants and needs of public transportation users, a new mode of transportation could be developed and optimized.

3 AKKA Concept Today, thanks to the introduction of electrical vehicles, which combine a series of advantages in terms of efficiency, cost, and maintenance, we are seeing a disruption in the traditional car industry market. The sharing economy of mobility is also growing and becoming a game-changer for transportation due to the multitude of services that are offered today through different apps and platforms. When combining the technological evolution and its convergence that has taken place in the last decade, with the above-mentioned phenomena, disruption in the transportation sector is happening rapidly. This in turn, is allowing for possible new business models and products.

Figure 2: ICE vs TaaS (Transportation as a Service): Projected trends in annual sales [1]

Helping contribute to the notion that the transportation sector is on track for further disruptions, in 2019 new-car purchases in the US-American market has fallen. Additionally, the number of members registered to a car-sharing service is projected to exceed 23 million globally in 2024, as seen in Figure 2. [1]

72

Concept people mover of tomorrow The combination of those factors will shrink the car market by 80%, meaning [1]: –
Disruption on the automotive domain: this means that we will have fewer vehicles that are owned by private individuals and a higher percentage of Mobility as a Service (MaaS) vehicles. Those MaaS vehicles will promote the best way to drive, not only the shortest route, that means better services onboard and the possibility to “live” the Service, and not only “use” it. –
Disruption on car insurance industry –
Disruption on oil industry –
Fewer parking spaces needed: in the future, fewer parking spaces will be needed, with existing spaces becoming available for public areas such as parks and vegetation. To provide an answer on the demands of tomorrow AKKA Technologies is working on its own concept of a people mover. The AKKA People Mover is a new MaaS oriented concept, developed to improve the quality of traditional transportation services offered to customers and utilize a new, shared autonomous platform, which can drive different sets of vehicles (pod), as seen in Figure 3.

Figure 3: Pods fittings – Pods can be combined with different chassis depending on their use

73

Concept people mover of tomorrow Pod modules, thanks to their flexibility, can be used for a multitude of different purposes. By reimagining the internal and external designs and use cases, the pod has the ability to be transformed and used for various different services and places, such as a people mover, a delivery vehicle, a mobile supermarket, or as a coffee shop, among others, as shown below in Figure 4. The pod is meant to interact and blend in with the architecture of cities, as well as help reduce the amount of congestion on the roads and to ease the current constraints of city layouts and infrastructure. Additionally, as the pod is intended to be available 24 hours a day, the powertrains of the pods will not be underutilized and will be available whenever users need them. This lends to the idea that the AKKA People Mover will be everywhere at the same time, and will provide a service that is currently not offered by traditional forms of mobility or other on-demand mobility services.

Figure 4: Use cases provided by the concept

74

Concept people mover of tomorrow

4 Specifications 4.1 Objectives Styling and Design Today’s public transportation is very standardized, with a state-of-the-art comparison revealing that many competitors are proposing very similar shapes and designs. The market of autonomous driving shuttles is currently full of solutions that do not stand out for their body shape or architecture. The objective of the Styling & Design is to combine a platform with an innovative design making the people mover much more attractive to customers. The final design will be presented at the Stuttgarter Symposium.

Body in White Current bus architecture does not take into account the change in user needs and technologies. The objective of Body in White is to propose a new platform, which can be used not only for public transportation. This explores new concept solutions according to the project specifications (powertrain, functionalities, uses cases, etc.) and will propose a solution that combines the packaging that best realizes the customer and user needs.

Powertrain Within the current market, new alternative powertrain options are frequently emerging and being studied. These new types of powertrain are still not 100% optimized to be used in production vehicles today. One of the objectives will be through innovative solutions to integrate the most efficient powertrain technologies. Energy storage, vehicle architecture and uncertainties related to different technological introductions will be the challenges by the powertrain.

Autonomous Driving Autonomous driving is one of the innovation fields, in which companies are focusing their R&D efforts at the moment. Such innovation affects not only passengers but also civilians based on governmental decisions. Vehicle manufacturers are increasingly trying to demonstrate the capacity of autonomous driving through research and field demonstration. Autonomous driving will also affect future traffic management. In order to integrate todays existing solutions in a smart way, it is important to develop algorithms that are able to manage vehicle fleet traffic.

75

Concept people mover of tomorrow

User Experience Often, time spent on public transportation is considered wasted time since public transportation systems offer a standardized user experience. The objective is to propose, in respect to an interior modularity, multiple usage profiles of the shuttle. By using analytic technologies, the shuttle will provide additional information and services to passengers. The concept plans to satisfy user needs, which are evolving and changing faster than ever before.

4.2 Driving Unit Module

Figure 5: Battery change – The two trailer switch out for best efficiency

The driving unit module is conceived to be a flexible platform, which can carry different categories of pods, ideally for different purposes. To understand how the module drives on the road and understand its capabilities in maneuvering, it will be a selfbalancing two-wheeler, which uses differential speed to steer the vehicle on a given path. The driving unit module, when connected to the pod will take the function of rear axle; meanwhile the front axle will give the direction. The driving unit in the concept vision is an autonomous module, which can drive from the charging station or driving unit parking lot, to the pod that is requiring a battery change or to the pod that needs to be picked up, as shown in Figure 5 and Figure 6.

76

Concept people mover of tomorrow

Figure 6: Catching ride

As the driving unit will ideally run on the road autonomously in between charging stations and pod pick-up locations, without the assistance of a safety driver, it will be equipped with a light system and noise emitters. The driving unit is intended to be lightweight and compact for easy storage, as well as have a battery that can be charged within few minutes. In the current concept vision, the driving unit is planned to carry up to 3.5t. The driving unit will also utilize in-wheel motors to help steer, as in-wheel hub motors deliver greater efficiency, packaging, torque vectoring and regeneration when compared to conventional solutions. The in-wheel hub motors used for the driving unit will be provided by Elaphe, which AKKA has collaborated with previously on projects. With the help of the in-wheel hub motors, the driving unit will be able to change its direction through the principle of different rotational speed per each wheel. This solution will allow the driving unit to reach the pod and connect to the rear section of the vehicle when travelling at a low speed.

4.3 Pod Module The pod module in the vision concept is a container that can be used for different purposes, as mentioned before. All the pods will have the same standardized connection system, so that the same kind of driving unit can pick up different pods.

77

Concept people mover of tomorrow

Figure 7: Use case scenario of People Mover

As previously explained, cityscapes of the future will need to be redesigned. By consequence of redesigning cities, future vehicles will also have to be designed in order to be adapted to the future cities, which will be more technologically advanced and smarter. As private vehicles today are parked on the side of streets and not accessible to other individuals, the goal of the AKKA People Mover is to ensure that the parked pods are usable and accessible for all people. This means that cities will have movable and flexible services located throughout the cityscape, as well as a space for individuals to relax and hang out in addition to parks. When being used as a people mover, the pod is envisioned to comfortably transport up to 12 people at one time. The pod will also include different services that utilize the latest advanced technologies, such as augmented/virtual reality and machine learning based technologies that can help users enjoy their journey. The pod, when connected with the driving unit, will be an autonomous vehicle of Level 4, as defined by SAE. This means that the shuttle can drive itself independently in most environments, but a driver may still need to take over. The long-term vision is SAE Level 5. The planned AKKA People Mover demonstrator (driving unit + pod) will run on a closed circuit under supervision of a safety driver, who is able take over via a Drive by Wire solution in the event of a system malfunction or an emergency.

78

Concept people mover of tomorrow

5 Bibliography 1.
J. Arbib, T. Seba, “Rethinking Transportation 2020-2030 – The Disruption of Transportation and the Collapse of the Internal-Combustion Vehicle and Oil Industries”, 2017 2.
P. Gosselin, „Carbon Diocide And The Ocean: Temperatures Is Driving CO2 And Not Vice Versa”, 2013 3.
International Sustainable Solutions i-SUSTAIN, OnRequest Images, “The Commuter Toolkit”, 2010 4.
D. Shoup, “The High Cost of Free Parking, Updated Edition,” 2011

79

Downtown delivery last mile with E-van and box body with integral batteries Jürgen Erhardt Erhardt GmbH Fahrzeug + Teile

© Springer Fachmedien Wiesbaden GmbH, ein Teil von Springer Nature 2020 M. Bargende et al. (Hrsg.), 20. Internationales Stuttgarter Symposium, Proceedings, https://doi.org/10.1007/978-3-658-29943-9_9

81

Downtown delivery last mile with E-van and box body with integral batteries Lightweight construction as a guaranteed reduction in emissions less weight = less energy = less emission The topic is inner city delivery also called last mile, implemented in the logistics by purely electric vans, which are equipped with individual bodies for the goods to be transported and have the required battery as part of the body. First of all to our company, we are body manufacturers for commercial vehicle bodies and have specialized in vehicle bodies used in distribution traffic for the past 20 years. As early as the 1990s, we developed and built lightweight superstructures on commercial vehicles, at that time increasing the payload under the background. We took sustainability into account and also implemented it by using aluminum, but it was not accepted in the market, as this resulted in a considerable additional price. Then as now, our motto is lighter and more stable, a very elementary principle in the construction of grooved vehicles. The beginnings were very difficult, the opinion was that lighter means more unstable and that paying more for a higher payload was also not possible in the market. Only in recent years has the importance of lightweight design development been accepted more and more by the market. The legal requirements for the chassis made the chassis increasingly heavy, exhaust systems, collision protection requirements are just a few examples that led to increased empty weights of the chassis. The shift in inner-city deliveries to smaller vehicles, from total weights 7.5 t to 12 t to vehicles with 3.5 t, leads to payload problems. Since the transport volume is increasing and the payload is decreasing, but also the loading volume, this means more vehicles have to drive into the cities to ensure delivery. A shift to 3.5 t GG vehicles also requires the EG driver’s license classification. Since the introduction of driving license classes B and C in 1999, young people with driving license B have only been allowed to drive vehicles up to 3.5 t, previously class 3 was the basic driving license, valid for vehicles up to 7.5 t GG, and it was even allowed Central axle trailers with 10.5 t can be driven. However, the use of 3.5 t vehicles has a far more decisive reason, that is the legal provisions. Regulations such as electronic tachograph, speed limit to 80 km / h and travel time regulations are no longer applicable to vehicles up to 3.5 t GG, and there is also no Sunday driving ban. That is why the 3.5 t GG vehicle will become the most important in the future for inner city deliveries. Our experience with customers shows that a payload of 1 t is required in this vehicle class. It is already available with current combustion engines and box bodies with electro-hydraulic tail lifts only with ultra-lightweight bodies, currently not achievable when using purely electric vehicles. Although there is

82

Downtown delivery last mile with E-van and box body with integral batteries an exceptional permit that the total weight can be increased by 700 kg when using electric transporters and the legal regulations as with the 3.5 t GG are retained, a payload target of 1 t is also problematic here. Since the inner city delivery requires a very wide logistics, e.g. parcel or KEP vehicles, fresh food and frozen products, drinks, non-food in general, but also waste disposal up to public transport, a variety of body variants are also required. This gives further problems in terms of payload and range. We are generally of the opinion that delivery to the city center, last mile, is the most sensible way to use pure electric vehicles, given the whole discussion about drive types, whether purely electric, fuel cell, e-fuels, hybrid, etc., since the infrastructure has to be set up in a shorter time. Internal fleets, which have clearly defined unloading points, draw up defined route plans, can therefore calculate planned daily kilometers and determine their own infrastructure (loading points) are suitable for implementing e-mobility immediately. Against this background, several years ago we dealt with the development of a complete system for a vehicle with a total weight (GG) up to 3.5 t with electric drive, batteries and body. The aim was to ensure a safe range, a time-defined charging time, a payload optimization and no restrictions on the dimensions of the cargo. The result is the E-City Truck, a patent-pending body with integral batteries in an ISO housing. Integral batteries in an ISO housing Assured range = less space and weight The project is in collaboration developed with Dr. Jobst Kerspe, TEB, and Michael Fischer, GVI, and essentially means that the batteries are not installed in several housings with heavy brackets on the left, right and between the chassis frame, but in a GVI housing (supported vacuum insulation) as the subassembly or subframe take over the floor of the respective superstructure. A holistic concept which can be technically adapted to any chassis through an interface and can therefore also be used across brands. Before we go into this concept in more detail, a few funding projects that we are currently developing and that also have an impact on our E City Truck project in details. We want to present 3 projects that are funded by the state of Baden-Württemberg, the ECB project, the TexEx project and a very large U shift project. In the ECB project, Elektro City Body, we are developing the possibility of replacing the substructure, which is usually made of steel or aluminum, with wood in cooperation with the DLR. This construction is integrated in an insulated drawer system, which accommodates the battery packages. As a result, we can guarantee the insulation of the

83

Downtown delivery last mile with E-van and box body with integral batteries batteries, have a modular structure with which we can define ranges for specific use and have the option of quickly replacing the battery units with the drawer solution, exchanging charged batteries for further ranges or replace. Thermal developments are tested so that battery operation is always guaranteed in the thermal window, in which the optimum performance, durability and efficiency are available. Through permanent monitoring of temperature and capacity, all informations were transmitted to the driver and fleet management. The test also determines and simulates the form in which the battery housing needs to be air-conditioned, since by charging the batteries and operating the batteries, heat is achieved that is used for the thermal window. In summary, we are testing both the optimization of the battery performance, thereby extending the range and guaranteeing the range, and the possibility of using hybrid materials to use renewable materials. The TexEx project concerns the construction of commercial vehicles, in this project we develop the use of smart textiles in commercial vehicles as the inner and outer skin of a box body. The U shift project is a complete system, which includes an autonomously driving drive board with swap bodies for all logistics requirements for inner city deliveries. We are developing the body for freight transport, a project for both lightweight construction and e-mobility with an autonomous carrier unit. In this project we also want to introduce the integral battery solution, we will present this concept below. The idea arose from the experience of being on the road for more than 4 years and to optimize the subject of superstructures even further without affecting the loading mass. After the 1st winter it was clear that the big enemy of the batteries is the temperature, especially in the low temperature window, and the air resistance. Since we are active in the commercial vehicle, it was also clear that the payload would become a problem with the additional battery weights for vehicles delivering to the city center. From this came the idea together with H. Michael Fischer and Dr. Jobst Kerspe was born to integrate the batteries in the body and to isolate them with an optimized insulating housing. This is to ensure that the batteries are kept in the optimal temperature window during the operating period. At the same time, we have subframes for commercial vehicles that connect the chassis to the body. Here, assembly guidelines must be met with regard to resistance moments, types of attachment such as shear-resistant, torsionally soft or torsionally stiff, etc. and dimensional components such as free-wheeling with deflection above the rear axle. Based on these specifications, we developed the concept to produce a load-bearing insulating housing that accommodates itself and ensures the technical requirements for the construction and the chassis assembly.

84

Downtown delivery last mile with E-van and box body with integral batteries GVI technology is a technical solution for this, i.e. With the help of vacuum insulation, we achieve an isofactor of 10 mm, a much higher isofactor, k-value, than with 25 mm PU foam. Now are the Housing the Technical Requirement of the subframe and is Base of the floor of the body. This design saves the subframe, which means a weight saving of approx. 150 kg depending on the body length. In addition, the brackets for the battery case, as currently installed on e-trucks, are no longer required. The batteries are currently installed by the chassis manufacturers or retrofitters in individual metal housings with a rung on the chassis frame below the body. Our solution approach saves weight because no brackets are required. In contrast to the existing solutions, access to the battery packs is simplified, for example in the event of a repair, the packs lie flat on one level. The retrofit includes, for example, 5 battery cases, which are fully packed with cells have a difficult accessibility. The positioning is on the left and right outside the chassis frames and between the frame long beams. Replacing the rechargeable batteries is also simplified, since the flat arrangement and lateral access to each individual cell is possible. The crash behavior is safer because the batteries are installed at a height where no cars crashes. By the current converted chassis, the battery packs are located directly in the impact area of a car. Even in the event of a crash with a truck, only the outer would be damaged, since the packages are built up in one layer. Depending on the width and configuration of the cells, there is also a safety zone of 10 to 20 cm from the outside of the body in there are no cells implemented. The monitoring of the batteries will be in the driver display. Therefore the driver is already informed about all conditions of the batteries. The basic development in this project lies in the modular design and the guaranteed range, regardless of weather and external influences. We were able to fulfill a large number of, mostly positive, components in the conception, the only topic at the moment is the interface to the chassis manufacturers. Just as there is no vehicle on the German market without a combustion engine, no chassis without batteries can be ordered, only with an E drive motor. The interface is technically not a problem, but is currently not preferred by the OEMs. The advantages of the integral battery concept clearly lie in the secure range and optimized payload. In addition, the range can be adapted to the logistical requirements thanks to the modular design, and it is also planned that subsequent extensions will be possible. The design is suitable for accommodating alternative body types, e.g. dry freight cases, tippers, flatbeds, insulated cases and much more. With a payload calculation, we were able to achieve a higher remaining payload when the GG was increased to 4.2 t than with a vehicle with a combustion engine.

85

Emission-free driving Gunnar-Marcel Klein MANN+HUMMEL International GmbH & Co. KG

This manuscript is not available according to publishing restriction. Thank you for your understanding.

© Springer Fachmedien Wiesbaden GmbH, ein Teil von Springer Nature 2020 M. Bargende et al. (Hrsg.), 20. Internationales Stuttgarter Symposium, Proceedings, https://doi.org/10.1007/978-3-658-29943-9_10

87

Pathways to a CO2-free mobility system in Germany from a technological point of view Michael Kühn, Peter Burghardt, Hans-Georg Hummel E@motion GmbH

© Springer Fachmedien Wiesbaden GmbH, ein Teil von Springer Nature 2020 M. Bargende et al. (Hrsg.), 20. Internationales Stuttgarter Symposium, Proceedings, https://doi.org/10.1007/978-3-658-29943-9_11

89

Pathways to a CO2-free mobility system in Germany from a technological point of …

1
Introduction Mankind in 21st century is successfully striving for prosperity and better living conditions. In parallel, we recognize unusual climatic phenomena in everyday life. A climate change can be detected by everybody even without special instruments. Due to the high change velocity, the consequences affect mankind within one generation. The population reacts to this change with an increasing energy demand and more migration activities. This leads to a significant unbalance of our living space and fossil energy consumption on our planet. The CO2 emissions on Earth are negatively influenced by unrestrained combustion and obstruction of photosynthesis as well as climate-damaging emissions by humans. Our Earth reacts with an increase of the mean temperature. Hence, the sea level rises considerably, weather phenomena like heat periods, floods and storms etc. increase dramatically. The Global Carbon Project /1/ investigated the global relationships between the supply and absorption of CO2. Accordingly, our planets carbon footprint is increasingly out of balance, or rather, out of hand as shown in Figure 1.

Figure 1: Disruption of the global carbon cycle due to anthropogenic activities (5% annually) /1/

CO2 emissions are released through fossil sources and land use, and on the other hand are stored through the biosphere, the seas and the atmosphere. The atmosphere is overloaded with CO2 and has to absorb an additional 2 Gt of the approx. 40 Gt of CO2

90

Pathways to a CO2-free mobility system in Germany from a technological point of … emitted per year. This increased concentration of CO2 on the Globus leads to global warming due to the reduction of infrared radiation into space. In various scenarios, depicted in Figure 2, relations between the global CO2 emissions and a related global temperature increase was calculated. To comply with the results of the 21st United Nations Framework Convention on Climate Change in Paris from 2015 (COP21), a stabilization of the global warming between 1,5 and 1,8 ° C compared to the preindustrial age has to be reached. For this purpose, an overall budget of 580 Gt was calculated with medium confidence /2/.The scenarios, marked in violet and blue, will reverse the climate change according to the COP21 target. The other CO2-scenarios create a high level of CO2 concentration in the atmosphere thus rising temperatures with exacerbating climate problems on our planet.

Figure 2: Target corridor for compliance with a global warming limit of 1.5- 2,0 ° C by reducing CO2 /1;2/

2 Transfer of the guidelines by the climate targets to the transport sector In the further course we want to concentrate on the contribution of traffic and in particular on the share of car traffic in CO2 emissions as well as possible and necessary measures.

91

Pathways to a CO2-free mobility system in Germany from a technological point of … The transport sector in Germany is responsible for approx. 162 million tons of CO2 out of a total of 866 million tons in 2018 which is 19% of the total share. The biggest part of this is caused by car traffic with 61%. Commercial vehicle traffic accounts for 35% and all other modes of transport for the remaining 4% of CO2 emissions. National air transport plays a subordinate role. In contrast to international aviation, which was deliberately excluded from the transport sector, but is limited in the EU by CO2 certificates. The CO2 emissions contributions calculated internally on the basis of the UBA and the Federal Statistical Office are significantly higher in international aviation /3; 4/.

Figure 3: Share of the individual modes of transport in the CO2 emissions of the transport sector /3; 4/

This paper encompasses the simulation results of the CO2-emission of the German car traffic. In addition, the modeling enables the calculation of other modes of transport. As stated at the beginning, the limitation of global warming to 1.5-2 ° C requires a restriction of the total global CO2 emissions to 580 gigantic tons in the period from 2017 to 2050. The percentage CO2 reduction required for this was transferred to the CO2 emissions generated by German car traffic starting from 2017, hence, a CO2 emission budget for car traffic of 1,76 megatons in the period 2017-2050 could be calculated.

92

Pathways to a CO2-free mobility system in Germany from a technological point of … Figure 4 describes the percentage of reduction and the resulting CO2 emission budget for the car traffic in Germany. This shows that the annual passenger car CO2 emissions must be reduced to below 50% by 2030, based on the starting value in 2017.

1,70 Mega-t !!!

Figure 4: CO2 target emissions for passenger car traffic to limit global warming to 1.5-2.0 °C

3 Measures to reduce CO2 emissions in the car traffic sector in Germany 3.1 Examined scenarios and premises for the simulation The EU emissions legislation for passenger cars currently requires a maximum fleet consumption of 95 g CO2 / km from 2020 /5/. This motivates the vehicle manufacturers to introduce electric vehicles and plug-in hybrids, as otherwise no series-compatible technology is available for a target-oriented reduction in CO2 emissions. Against this background, several states, vehicle OEMs and political parties have communicated a replacement scenario for the internal combustion engine cars currently used. The table below shows the current decision situation. Only a few OEMs have published a clear position regarding an exit of the internal combustion engine (ICE) as a car powertrain. In summary, the automotive industry hopes to sell combustion engines by around 2040, followed by the market exit around 2050.

93

Pathways to a CO2-free mobility system in Germany from a technological point of … Table 1: Decision status for the exit of passenger cars with combustion engines /6; 7/ New development Vehicle manufacturers Daimler VW, Audi Volvo

Sales until

2020

Market exit

2039 2026

2040 2040

2050

Political parties B.90/Grüne

2030

Countries Norway China Denmark India Iceland Israel California Netherlands Sweden France Great Brit. Canada 

Taiwan Germany

2025 2030 2030 2030 2030 2030 2030 2030 2030

2040

2040 2040 2040

2050 2045 2045 2050

A summary of the announcements from the political environment of the countries listed in Table 2 regarding the exit of the internal combustion engine (ICE) will lead to an end of sales by 2030 and a market exit by 2040. Against this background, the following scenarios were chosen.They are encompassing the following criteria: Political and industrial announcements, the possibility of the visualization of important core parameters of the transition to electric powertrains. Table 2: Key data for simulation scenarios    


  


   







  !  #


 

  "   "

The actual course of future market development depends on many social and marketspecific parameters at the beginning of a disruptive change process /8/ and can therefore only be simulated with restrictions. However, to demonstrate and investigate the core

94

Pathways to a CO2-free mobility system in Germany from a technological point of … parameters of this transformation, the following premises and constants were used for all simulation calculations. Table 3: Premises for simulation scenarios   


 

 
  
 





 


 
 
 


  



 




&















  ()!%
 %(
 &$!(
 "%$$ %*%
" %'!($$
"

The emission of CO2 by electric cars essentially depends on the proportion of electricity generated from renewable sources. Based on the forecasts of the network operators /9/ with a regenerative share of 56% in 2030, 62% in 2035 and 71% in 2040, a maximum value of 80% in 2050 was extrapolated for the calculation of the scenarios. (See also figure 8)

3.2 Analysis of the simulation results To calculate the scenarios, the period defined by the Global Carbon Project from 20172050 was considered. Figure 5 shows a comparison of the stocks of cars with ICE and electric drivetrains for the scenarios described using the assumptions made above. The different introduction speeds of electric cars and the respective market exits of ICE cars are clearly visible. The necessary new registrations of electric cars in Figure 6 show strong to considerable fluctuations, especially in the scenarios Extreme and Politics. The reason for this undesirable behavior from a production perspective is shown as an example for the Scenario Extreme in Figure 7. As a result of the rapid market launch, high numbers of new car registrations are achieved in the area of market growth, which will be driven by a pull effect from a funding program and the fascination for the new drivetrain technology. If the car stock approaches saturation, the new registration drops sharply.

95

Pathways to a CO2-free mobility system in Germany from a technological point of …

Figure 5: Comparison of car stocks in the extreme, politics and industry scenarios

Figure 6: Comparison of new vehicle registrations (industrial, political and extreme scenarios)

After 2038, the car stock only consists of E.-cars with low replacements needs. This is due to the high introductions speed and cars live span of 14 years. The high introduction numbers at around 2032 are then causing a strong demand growth of car replacements in 2047. This analysis demonstrates the problems which will occur with an accelerated introduction of electric cars. The concerns of the car manufacturers to provide a feasible fluctuation of the vehicle production can therefore be understood. A mitigation of this problem is expected by linking several vehicle markets.

96

Pathways to a CO2-free mobility system in Germany from a technological point of …

Figure 7: Comparison of the E.car registrations, vehicle stock and retirement (extreme scenario)

More effects of the introduction of electric cars, especially on CO2 emissions and electricity requirements are presented and analyzed for the scenario Politics. Figure 8 shows the course of the electricity demand for the electric cars together with the amount of

Figure 8: Gross electricity demand for electric vehicles scenario Politics

97

Pathways to a CO2-free mobility system in Germany from a technological point of … electricity required for all other consumers in Germany. The total requirement increases due to the transition to E.-cars from approx. 600 to 710 TWh annually. This is less than 25% of the total electricity demand in 2050. Furthermore, the previously mentioned introduction scenario of regenerative energy sources is depicted in Figure 8. The simulation result for the CO2 emissions to cover the electricity demand is shown in Figure 9. The steady reduction in CO2 emissions mainly results from the increase in electricity generated from renewable sources. It can also be seen that the increase in CO2 emissions from the operation of electric cars contributes by 20% to the CO2 emissions calculated for 2050 to cover the electricity demand.

Figure 9: Overall CO2 emissions to generate the gross electricity demand (political scenario)

Figure 10: Comparison of CO2 emissions scenario Politics with the CO2 target value

98

Pathways to a CO2-free mobility system in Germany from a technological point of … Figure 10 shows the CO2 emissions of the scenario Politics for the entire car fleet, consisting of E.cars and ICE cars, compared to the CO2 target budget determined in Chapter 1. The evaluation of the integral under the envelope of both, ICE & E.cars, shows a significant deviation compared to the integral under the target curve. With the solitary introduction of electric cars and the defined increase in the share of renewable electricity, the goal of limiting global warming of 25kWh). Using the traction battery of an electric vehicle for bi-directional charging is an attractive option during longer parking phases either at home or at work place (s. figure 1).

2 Expansion of power grids Several projects had been set-up to determine the feasibility and the necessary investment for power grid expansion to integration electric vehicles. Major objectives are satisfaction of the user, avoidance of overloading the grids and affordable investment for power grid expansion. Two examples for projects with important results are 1
PlanGridEV: „Distribution grid planning and operational principles for electric vehicle mass roll out while enabling integration of renewable distributed energy resources“, EU founded project 2016 2
Agora Verkehrswende „Verteilnetzausbau für die Energiewende – Elektromobilität im Fokus“, August 2019 Based on a set of scenarios and use cases (for more or less grid-friendly charging) some calculations have been performed that prove that there are major benefits with the smart grid approach. Depending on the setup, the peak load could be reduced by half compared to an uncontrolled charging scenario. Furthermore the usage of renewable energy could be increased without interfering with transportation needs. This clearly shows that in an all-electric world the smart grid approach will play a major role.

2.1 Need of energy for charging electric vehicles In Germany the average electrical power consumption in 2019 had been approximately 500 TWh. The share to charge electric vehicles is small today. Further assumptions: ●
Average driving distance of an electric vehicle per day: 50 km ●
Average consumption of an electric vehicle per day:

12 kWh

●
Average consumption per vehicle and year (365 days):

4,38 MWh

560

Energy and automotive In the following table the additional energy demand had been determined related to the estimated amount of passenger cars with electric engines: # passenger cars (in millions) 6 15 30 45

Energy in TWh/year 26,28 77,7 131,4 197,1

% increase (based von 500 TWh) 5,3 13,1 26,3 39,4

Energy creation can be provided respectively, power at the grid connection points is the major challenge.

2.2 Grid expansion – investments According to [4] NPE estimates in 2025 between 2 and 3 million electric vehicles in Germany. In the study of Agora Verkehrswende [2] several scenarios had been analyzed to determine the necessary investments. It is distinguished between market ramp up until 2030 and two further scenarios for 2050: ●
6 million cars until 2030 (market ramp up scenario 1) ●
15 million cars until 2030 (market ramp up scenario 2) ●
45 million cars until 2050 -> all passengers cars in Germany are electric vehicles (scenario 3) ●
30 million cars until 2050 / mobility change -> the number of passenger cars had been decreased, public traffic increased. The necessary grid extensions for public traffic had been considered in the calculations. The analysis had been performed with various charging options: ●
Uncontrolled charging: charging is immediately performed after connecting to the charging station ●
Controlled charging: the charging process can be controlled within the parking time of the vehicles ●
Optimized controlled charging: energy transfer in the vehicles controlled over several park and usage phases.

561

Energy and automotive For every scenario the quality of the service for the users and required investment for grid expansion had been analyzed. The huge potential for intelligent load management is given by the fact, that many users do not want to continue immediately driving. For the analysis therefore the simultaneity factor for charging processes is essential.

Figure 2: Simultaneity factor

The analysis of scenario 1 and scenario 2 showed that the investments for grid expansion can be reduced by 50% if controlled charging is performed [2]:

In case of optimized controlled charging further reduction of 50% for investments is feasible.

562

Energy and automotive In absolute values depending on the scenario investment is between 1,5 and 2,4 billion Euros per year. Actually expenses for grid extension in Germany is about 3 billion Euro per year (s. figure 3).

Figure 3: Investment per year for grid expansion [2]

If all passenger cars will be electrified grid expansion will be feasible using controlled charging options. Controlled charging is accepted by users without perceptible constraints. Controllable charging will pay off quickly.

3 Implementation of intelligent load management 3.1 Load Management Load management functions are performed to balance the available energy and the demand of energy by the users (smart grid). Charging requirements by the users are classified into three groups: ●
Charging on demand (stochastic: the user expects to receive energy immediately) ●
Controlled charging: the user expects fully charged battery at desired time (driven by financial reward)

563

Energy and automotive ●
Dynamic load management: use of electric vehicles as electricity storage system. This option includes grid feedback facilities.

Requirement for load management – example: Several vehicles intend to charge at the same time on 3-phase 63 A, with 43.5 kW. The local grid provides not more than 680 kVA. The grid is overloaded from as few as 16 electric vehicles. To avoid overloading the grid by means of intelligent control (load management) it is required to provide communication protocol stacks at all system interfaces (figure 4). ISO 15118 is one of the standards which specifies the appropriate control commands for charging communication between electric vehicle and charging station.

3.2 Optimizing charging strategies Charging strategies are adapted on local conditions, dependencies on the time or user requirements: environment (home, public parking, far distance traffic), type of vehicle (private, commercial, public traffic), needs of the user, grid infrastructure. Controlled charging needs therefore also the possibility to adapt controlling parameters to the actual situation. Potential load management strategies have to consider many aspects, i.e. ●
Available performance of the power connection at a certain location ●
Limitations in maximum power or energy ●
Number of users who want to charge ●
Optimizing costs or investments ●
Priority of users ●
Preferred usage of green energy ●
Avoid grid distortion: low harmonics, balanced phases General strategy concepts could be:

564

1


First come first serve: this strategy is performed during high power charging at motorways. The user does not have time and wants to continue the drive quickly.

2


Balanced: If in a row of charging stations only one vehicle is connected, this vehicle is charged receiving 100% of the performacne. If further vehicles are

Energy and automotive connected during the charging process of the first one, the available power is distributed equally between all connected vehicles. 3


Optimized solutions: controlled charging is performed using parameters, i.e. departure time, prioritization, balance of energy demand and available energy, sales tariffs, value added services. User demands are balanced with available resources.

3.3 E-Mobility System Concept

Figure 4: E-Mobility System concept [IAV]

Figure 4 shows the system concept for e-mobility public charging. Roles in the system are electric vehicle, electric vehicle supply equipment (= charging station), charge point operator, e-mobility service provider, distribution system operator and clearing house. The interfaces between the roles are specified. At each interface at least one communication protocol is standardized. Between electric vehicle (EV) and charging station (EVSE) the communication protocol is defined in ISO 15118. Further examples for communication protocols on the other interfaces are: OCPP, IEEE 2030.5, IEC 63110, IEC 63119. A respective concept including specified protocols exist also for home energy management systems (HEMS). Standardized protocols for HEMS are SPINE, SEP 2.0 and Echonet Lite.

3.4 Smart Charging data Important parameter for powerful smart charging functions which are transferred using the communication protocols are available power and energy depending on the time of

565

Energy and automotive the day. All communication protocols (chapter 3.3.) contain complex data structures, which can be used to transmit a large number of different charging offers from e-mobility service providers to the user / driver. The e-mobility service provider receives conditions and ranges by the distribution service operator, i.e. maximal available power, available energy depending on time of the day. The e-mobility provider combines the power profile with tariffs. Tariffs and scheduling for charging is dependend on time of the day, consumption, maximal power or any combination of these pararmeters (s. figure 5). In addition further parameters, i.e. CO2 neutral current may be offered. The driver or an appropriate algorithm chooses a fitting offer and communicates the desired demand. Then the charging process is scheduled. Changes until start of charging process can be performed at any time. A change of scheduling may be triggered by new offers from the e-mobility service provider of by initiative from the driver.

Figure 5: Example for setting of parameters – power profile (source: EEBus Spine Resource Specification [3])

4 Conclusion Several projects show that there is a large potential for controlled charging systems. Compared to uncontrolled solutions controlled charging systems have 50-75% lower investment costs. Therefore it is essential to support the market ramp up until 2030 with intelligent load management applications. Data necessary for the implementation of system-wide applications are transmitted via interfaces using standardized communication protocols. Various standards are available for communication protocols that would enable the integration of vehicles into the grid (e.g. the ISO 15118 charging standard, EEBus for home-energy management systems

566

Energy and automotive and IEC 61113 for backend communication). The components needed for the grid integration of electric vehicles are also available. We now need to develop high-capacity, smart-grid applications and introduce these to the market, applications that efficiently link demand for energy to the available sources of energy. Working together with enterprises in various sectors, the automotive industry is in a position to make a significant contribution to our transition to a clean-energy economy, with systems that also propel digitization. In doing so, we can effectively support our climate objectives at a national and international level. These system applications also offer great potential in the new business sectors of digitization.

Bibliography 1.
PlanGridEV: „Distribution grid planning and operational principles for electric vehicle mass roll out while enabling integration of renewable distributed energy resources“, EU founded project 2016 2.
Agora Verkehrswende „Verteilnetzausbau für die Energiewende – Elektromobilität im Fokus“, August 2019 3.
EEBus SPINE Technical Report – Resource Specification, Version 1.1.1, 2019, http://www.eebus.org/download-standard/ 4.
Fortschrittsbericht 2018 – Markthochlauf, NPE Berlin Mai 2018

567

Digitalization of flow measurement systems, in particular of fuel consumption measurement Dr. Heribert Kammerstetter, Josef Moik, Michael Sammer, Manuel Berglez, Daniel Leitner AVL List GmbH, Hans List Platz 1, 8020 Graz

© Springer Fachmedien Wiesbaden GmbH, ein Teil von Springer Nature 2020 M. Bargende et al. (Hrsg.), 20. Internationales Stuttgarter Symposium, Proceedings, https://doi.org/10.1007/978-3-658-29943-9_43

569

Digitalization of flow measurement systems, in particular of fuel consumption …

1 Abstract Based on a Plugin Hybrid Electric Vehicle (PHEV) a new concept for measuring fuel consumption in a real drive situation is presented. The concept uses flow, density, temperature and pressure sensors which contribute to a physical model working in the flow sensor to correct the dominant systematic measurement deviations. The PHEV vehicle is the ideal platform for the demonstration and validation of such model based approach. The challenging operating modes are caused by the internal combustion (IC) engine permanently starting and stopping during the measurement.

2 Introduction In state of the art fuel consumption measurement systems the influence of factors contributing to the measurement uncertainty budget is kept low by controlling the main contribution factors. These factors are mainly temperature and pressure. Both factors are acting on the fluid volume proportionally. “Controlling” means to keep these influencing factors constant during the measurement. But what, if “controlling” is not possible? What if the vehicle system controls the influencing factors, not a measurement system like we are used in engine test cells? In this case a solution is to deal with these factors as inputs and use them for systematic correction.

3 System Description The Test Platform consists of a standard series production Plugin Hybrid Electric Vehicle [1] which is instrumented with AVL X-ion data acquisition system [2].

3.1 Vehicle

Figure 1: Test vehicle Mitsubishi Outlander

570

Figure 2: Vehicle in chassis dyno for WLTP cycle

Digitalization of flow measurement systems, in particular of fuel consumption The test vehicle is the Mitsubishi MY18 Outlander PHEV. This vehicle was chosen by AVL due to its availability and technology. The test vehicle is operated as is, without modification, except the instrumentation of the powertrain. The purpose of the vehicle is purely to serve as a test platform for AVL measurement equipment. There is no intention of AVL to investigate and/or rate or optimize the performance of this vehicle. It is used as is. The powertrain of this car consists of two 60 kW electric drive motors, and one 89 kW internal combustion engine. One electric motor acts on the front and one on the rear axle. The internal combustion engine is coupled either to a generator, which also acts as starter motor for the IC-engine, or directly to the front axle via a 1 gear transaxle. The electric motors are fed by a drive battery of 12 kWh capacity with a nominal voltage of 296 V (80 cells in series). The battery has a closed air cooling system and a mass of 180 kg. The total vehicle mass is 1820 kg. The MY18 model used is rated with a fuel consumption of 1.7 l/100 km (NEDC) or 41 g/km CO2 emissions (compared to the actual MY19 model with a fuel consumption of 2.0 l/100 km (WLTP) or 46 g/km CO2). The test vehicle can be operated in 3 basic drive modes selected by the vehicle depending on load conditions 1.
Pure electric mode 2.
Series Hybrid mode 3.
Parallel Hybrid mode In addition to the 3 load-selected drive modes the driver can select between 3 “overruling” operating modes: ●
Pure electric mode ●
Save mode (battery not used) ●
Charge mode (battery charged by IC-engine) In addition to these driving modes, the vehicle allows to select various engine braking and power regeneration modes.

3.2 Vehicle Instrumentation The purpose of the test vehicle instrumentation is to integrate all instrumentation for the acquisition of the energy flows between the sub-systems in the vehicle. The result is a synchronized access to all signal- and data-sources like

571

Digitalization of flow measurement systems, in particular of fuel consumption … –
IC-Engine indication (AVL ZI45 spark plug sensors) –
IC-Engine fuel flow –
Optic access to combustion via spark plug sensors –
Infrared based catalyst temperature measurement –
Generator/starter motor electric power flow (3-phase current and voltage) –
Front electric motor power flow (3-phase current and voltage) –
Rear electric motor power flow (3-phase current and voltage) –
Drive battery voltage, front connector current, rear connector current –
Charge port current All data sources are connected to the AVL X-ion™ Mobile (684) data acquisition system. The user-frontend is a laptop with AVL IndiCom™ data acquisition and processing software.

Figure 3: PHEV Measurement System: E-Power

572

Digitalization of flow measurement systems, in particular of fuel consumption

Figure 4: PHEV Measurement System: ICE-Power

Data acquisition integrates CAN-bus vehicle data well synchronized to the rest of the sensor signals.

3.2.1 Fuel Flow Measurement

Figure 5: Fuel Flow sensor integration in test vehicle

573

Digitalization of flow measurement systems, in particular of fuel consumption … Main focus in this presentation is on the fuel flow measurement. As the sensor of choice the AVL PLUtron™ ADVANCED flow meter is used. This sensor provides volume flow, mass flow, density, temperature and fuel pressure with a data rate of 100 Hz via a high speed CAN interface to the X-ion™ Mobile data acquisition system. Fuel Flow measurement in vehicles is a challenge, because of the unpredictable environment compared to a test cell. The main contributing factors are temperature and pressure. Temperature is influenced by the natural heat sources in the vicinity of the measurement system. Pressure is controlled by the vehicle control-unit according to operating mode and load. For both factors, the fuel volume contained in the measurement circuit between the flow meter and the Injector, acts as a multiplier for the uncertainty contribution. Because of the “Close-To-Engine” application in the vehicle, the volume is minimized as a byproduct of the application. Test measurements show, that the change in temperature expressed as a gradient °C/time is small, even though the temperature change in an engine compartment may be significant in the range of several 10 °C. In comparison to a typical test cell system the “circuit volumes” are much larger, but temperature stability in this case is in the range of 0.02 °C.

4 Measurement Uncertainty Budget The Measurement Uncertainty budget for the mass flow measurement is made according to JCGM 100:2008 [3], also known as the GUM (Guide to the expression of Uncertainty in Measurement) issued from the BIPM (Bureau International Poids et Mesures).

Figure 6: Ichikawa diagram of the factors contributing to the measurement uncertainty of a mass flow measurement

574

Digitalization of flow measurement systems, in particular of fuel consumption For the Uncertainty Budget for the flow measurement the main contributing factors are collected in Figure 6. In a test bed environment the Circuit Volume is the dominant contributor to uncertainty. To minimize the effect of Temperature and pressure acting on the Circuit volume, test bed systems use a highly sophisticated control for both, temperature and pressure. In a vehicle the Circuit Volume is not present at all, in particular in a return less gasoline application. The fuel system volume in test bed systems is same compared to a vehicle. Regardless if the application is in a test bed or in a vehicle, the Fuel System Volume is not controlled by means of a temperature control. The main difference between test beds and vehicles is, that in a vehicle, the environment is much more demanding, because the fuel system is positioned in the vicinity of all the heat dissipating powertrain components. The engine compartment is small and cooling is depending on vehicle speed.

Figure 7: Comparison of typical measurement uncertainties of conventional test bed fuel consumption measurement (Fuel Exact), Close To Engine application of a flow sensor in a test bed and Close To Engine application in a vehicle environment

When comparing conventional fuel consumption measurement like the AVL Fuel Exact to a Close To Engine application in a test-bed, the elimination of the “Circuit Volume” is the reason for the significant improvement in measurement uncertainty in the range

575

Digitalization of flow measurement systems, in particular of fuel consumption … of 30% to 50%, at least in the lower measurement range. But this improvement is not possible to be transferred to the vehicle, because of the challenging environmental boundaries in the engine compartment. But in case of a favorable fuel system design, like in the case of a return-less gasoline fuel system, the measurement uncertainty in the vehicle is comparable to a standard fuel consumption system in a well-designed test cell. Figure 7 does not take into account events like engine start and –stops during the measurement. These events draw special attention regarding the specific system variations during these events.

5 Dominant Systematic Effect Compensation

Figure 8: Typical sequence controlled by the vehicle directly after powering up: The IC-engine starts for about 50 seconds, activates the generator and charges the battery for 20 seconds with a power of approx. 7 kW. After this the IC-engine is shut down again

Measurement cycles in a hybrid car contain IC-Engine start and stop sequences during the cycle.

576

Digitalization of flow measurement systems, in particular of fuel consumption

Figure 9: Engine Stop right after end of charging cycle. After Engine stop the flow meter detects pressure induced flow

Figure 10: Systematic correction of the pressure induced flow results in a plausible flow reading

Start as well as stop of the engine causes the fuel pressure to change by about 200 mbar. This pressure change causes fuel flow readings in the magnitude of +- 3 kg/h during periods when the engine speed is already zero and no injections are made (Figure 9). An approach to treat the fuel as a compressible fluid and compensate for the accumulated volume caused by the pressure changes, eliminates the non-plausible flow readings completely (Figure 10). In recent applications, this type of compensation was only done in high pressure applications, like Diesel Common Rail fuel injection systems. Now it seems that in modern fuel systems, for the sake of energy efficient systems, the low pressure fuel pumps only work as much as necessary and are switched off during engine stand still. This causes the fuel pressure to change between Engine active and not active, and causes the flow readings accordingly. Fact is, that these flow readings are true flows, because any change in pressure is only possible, if fluid flows into the control volume or out of the control volume. This behavior must not be mixed with temperature changes. Temperature is to be treated separately, but for simplicity, in the data presented in this paper temperature can be treated to be constant during measurements. Figure 10 shows that the un-plausible flow readings disappear when applying a compensation model which is based on compressible fluid. What should be mentioned here is, that although the pressure compensation model works nearly perfect, the compressibility which was used for this compensation model is very different from what was expected by the fluid properties. Gasoline has a bulk modulus of approx. 1300 MPa. In the pressure compensation used in Figure 10, a bulk modulus a magnitude smaller in the range of 100 MPa had to be used for the compensation to work properly. An explanation to the small bulk modulus to be used is, that the compensation approach is able to compensate for any linear elastic phenomenon in the system. As long as the

577

Digitalization of flow measurement systems, in particular of fuel consumption … effects are linear, all elasticities in the system that act on the fluid pressure can be superimposed and result in an overall elasticity. The elasticity of the fluid is still 1300 MPa, but if this fluid is enclosed in a hose that is very flexible, the elasticity of the system fluid + hose get combined, comparable to springs which act one on top of another one. Another effect which may contribute to the small bulk modulus are air bubbles in the fluid.

6 Conclusion Fuel consumption measurements in Hybrid vehicles are challenged by low flow rates combined with engine start and stop during the driving cycles. The vehicle decides depending on the load demand if the IC-Engine is used, for either charging the battery or assisting the powertrain directly by supplying torque to the wheels. Engine start and stop is associated with pressure changes in the measurement circuit which cause nonplausible flow readings in periods when no fuel is consumed by the IC-Engine. Because the PLUtron ADVANCED flow sensor has the option to measure fuel pressure as well, a flow compensation based on the compressibility of the fuel can be used to eliminate all pressure induced flow readings which do not contribute to the engine fuel consumption.

Bibliography 1.
https://www.mitsubishi-motors-pr.eu/MY19/Files/Documents/EN/newMY19OutlanderPHEV.pdf 2.
https://www.avl.com/x-ion 3.
JCGM 100:2008, Evaluation of measurement data – Guide to the expression of uncertainty in measurement, First Edition September 2008, JCGM

578

Solution of trade-offs in the development of powertrains by use of online measurement technologies P. Berlet, A. Jäger IAVF Antriebstechnik GmbH, Karlsruhe

© Springer Fachmedien Wiesbaden GmbH, ein Teil von Springer Nature 2020 M. Bargende et al. (Hrsg.), 20. Internationales Stuttgarter Symposium, Proceedings, https://doi.org/10.1007/978-3-658-29943-9_44

579

Solution of trade-offs in the development of powertrains by use of online …

1 Introduction In modern vehicle power trains for passenger cars combustion engines will be supplemented more and more by electric engines. However NOx- and particle emissions as well as CO2-emissions by fuel consumption are still in focus. Further progress may be realised by friction reduction as well as by improved mixture preparation and combustion of the fuel. Due to the increasing complexity the strategy of IAVF in the development of powertrains results in selective online measurements of relevant properties during the whole development and testing process. In this way characteristics of the power train may be quantified exactly, their trends observed and those extrapolated for lifetime predictions.

Fig. 1: Strategy in power train development using the whole chain of options for testing by online measurements

Depending on task and stage of development of a project different testing tools from tribometer up to chassis dynamometer may be implemented. According to experience an early analysis by the use of cost-efficient tools may help to avoid problems at an advanced stage of a project.

580

Solution of trade-offs in the development of powertrains by use of online …

2 Objectives and trade-offs in the development of a robust powertrain 2.1 Accelerated oil aging and high performance of the lubricant The trend in automotive industry to low viscosity engine oils is ongoing driven by the needs to reduced fuel consumption. Entrance of fuel, water and soot lead to clearly changed tribological and rheological properties of the lubricant. Mechanical stress and oxidation processes accelerate the oil aging additionally. In engine operation the various oil aging parameters change in a very complex interaction and this fact makes it difficult to explain their influence on oil performance. Therefore oil aging in laboratory and a tribological characterisation using a micro tribometer were conducted [1].

Fig. 2: Influence of fuel dilution, shear and soot entrance in engine oil on high temperature / high shear viscosity and IAVF-wear index

Oil aging by fuel dilution was simulated by Diesel fuel of commercial quality with 7% fatty acid methyl ester (FAME). The samples were homogenised by shaking and the fuel content was measured by GC-analysis (DIN 51380). To analyse the effect of soot in oil on the tribological behaviour the sooty oil was produced by burning Diesel fuel in the IAVF soot generator. Its functional principle bases on the controlled combustion of Diesel fuel. Sooty exhaust gas will be blown into the engine oil. Oil aging by shear stress was carried out by test method CEC L45-99: Temperature was fixed at

581

Solution of trade-offs in the development of powertrains by use of online … 60 °C to avoid an additional oxidation of the oil. Oxidation of the lubricant was made on the basis of established oxidation tests. Wear index was developed to characterise performance of used passenger car engine oils at the end of their oil changing interval in relation to a reference. The IAVF inhouse method works with a commercially available micro tribometer, Fig. 2.

Fig. 3: Wear index of engine oils aged by fuel dilution, oxidation, shearing and soot entrance versus high temperature / high shear viscosity

The effects of the different oil aging parameters on wear index and high temperature / high shear viscosity are shown in Fig.3. Initiated by these investigations on a micro tribometer for the most important oil aging parameters fuel dilution and soot entrance online measurement devices are meanwhile also available for engine test benches. But low viscosity oils do not only influence the wear of components. It also changes oil pressure built-up and heat dissipation, for instance in turbo chargers and may have an effect on their robustness [2].

2.2 High pressure and low wear of components For further reductions of fuel consumption and emissions of future passenger cars by improved mixture preparation and combustion a high pressure gasoline direct injection with 500 bars and more was identified just in the special research field 606 of the Deutsche Forschungsgemeinschaft DFG until 2012. However because of the limited

582

Solution of trade-offs in the development of powertrains by use of online … lubricity of the fluid with regards to an application in a series engine there are enhanced requirements on wear resistance of the gasoline pump.

Fig. 4: High pressure gasoline injection pump and pump drive on component test rig

To realise gasoline injection up to 600 bars in a demonstrator engine a new injection pump was developed [3, 4]. The hardness of the piston guide material was decreased to improve its elasticity. In order to investigate the wear behaviour of the piston guide a component test rig was built-up, Fig. 4. An online wear measurement device using Radionuclide Techniques (RNT) was installed in the fuel circuit.

Fig. 5: Wear of different piston guides, speed and rail pressure set point of a gasoline injection pump on component test bench during running-in

583

Solution of trade-offs in the development of powertrains by use of online … During the first half of a predetermined running-in program and injection pressure up to 350 bars wear of both piston guides is situated nearly on zero level. Remarkable wear just occurs when a high pump speed is reached for the first time, Fig. 5.

Fig. 6: Wear rates of different piston guides of a gasoline injection pump at 350 bar injection pressure and 100 % delivery rate versus speed

Fig. 7: Wear rates of different piston guides of a gasoline injection pump at 3000 rpm injection pressure and 100 % delivery rate versus injection pressure

584

Solution of trade-offs in the development of powertrains by use of online … In operation after running-in the wear rates of the piston guide which is made of the material with reduced hardness are very low, as shown in Fig. 6. It is also notable that there is not any strong influence of the injection pressure on pump wear, Fig. 7.

2.3 Low fuel consumption and minimised engine emissions

Fig. 8: HD-BE-demonstrator engine on engine test bench

To investigate the potential of high pressure gasoline direct injection with regard to fuel consumption and emissions it was necessary to build a demonstrator engine. However it was well-known from component test rig that the high fuel pressure requires an enhanced driving power. Therefore it was decided to change the position of the fuel pump from outlet camshaft to chain drive. As a consequence a new chain drive layout as well as a separate control unit for the injection system had to be developed. After the high pressure gasoline injection pump and its drive train (CAM-Box) whad been tested successfully on a component test rig it was installed in the demonstrator engine on an engine test bench, Fig. 8. With regard to emissions especially particles could be reduced substantially especially when injection pressure rises up to 600 bars. In addition the improved mixture preparation and combustion overcompensated the enhanced driving power of the injection pump and friction mean effective pressure re-

585

Solution of trade-offs in the development of powertrains by use of online … spectively. Nevertheless with regard to engine efficiency there seemed to be an optimum at 500 bars as Fig. 9 shows.

Fig. 9: Fuel consumption, friction mean effective pressure and emissions of the HD-BEdemonstrator engine at 2000 rpm / 8.6 bar pmi versus injection pressure

Advantages of the high pressure direct injection with regard to exhaust emissions were also measured during dynamic accelerations of the demonstrator engine on test bench.

3 Summary and outlook Future requirements to reduce fuel consumption as well as emissions lead to a tightening of trade-off between friction reduction and modern combustion processes on one side and the need for a high robustness over engine lifetime on the other side. The actual requirement for In Service Conformity (ISC) until 100.000 km as well as the accelerating trend to downsizing and hybridisation of power trains makes matters worse for combustions engines. By means of examples it was demonstrated, how the above-mentioned trade-off might be solved and which possibilities are offered by the use of online measurement methods like wear analysis using Radionuclide Techniques.

586

Solution of trade-offs in the development of powertrains by use of online … In addition to the presented methods top down strategies like Road to Rig and the use of previously on chassis dynamometer applied CVS emission measurement technology in combination with virtual car software provide new opportunities, Fig. 10.

Fig. 10: Test bench with Carmaker® for test bench control and Constant Volume Sampler (CVS)

Fig. 11: Principle of Road to Rig measurements and simulations using virtual car

587

Solution of trade-offs in the development of powertrains by use of online … In consideration of the fact that the stress of lubricants and components is further increasing the comprehensive quantification of their robustness-relevant properties like wear and oil consumption by online measurement techniques seems to be essential to ensure the endurance of power train, exhaust after treatment system etc. under varied car configurations and stress collectives in daily operation. For this purpose stationary maps and dynamic operational profiles are measured and numerous versions like different car models are simulated by the use of virtual car software, Fig. 11. In this way improved lifetime models for relevant power train properties may help to ensure the robustness of new cars before start of production comprehensively.

Bibliography 1.
Berlet, P., Müller, G. Pöhlmann, K., Stern, D.: Praxisnahe Alterung von Motorölen und Auswirkungen auf tribologisch relevante Eigenschaften, Annual Meeting of the German Tribological Society, Göttingen, 2013. 2.
Jäger, A., Kirsten, K.: How to improve TC performance and durability, when oil specification and duty cycles are changing?, International Conference on Turbochargers and Turbocharging, Singapore, 2019. 3.
Berlet, P., Köhler, L., Kronstedt, M., Phan, B., Schmitz, N., Wittemann, N., Veit, V., Züfle, M.: Entwicklung und Erprobung einer neuen Kraftstoffpumpe für Hochdruck-Benzindirekteinspritzung, Annual Meeting of the German Tribological Society, Göttingen, 2019. 4.
BMWi-project HD-BE Hochdruck-Benzindirekteinspritzung, Final Report, 2019.

588

Study to assess the suitability of C/C-SiC as material for piston rings Alex Heron-Himmel12, Fiona Kessel12*, Dr. Yuan Shi1* German Aerospace Center (DLR), Institute of Vehicle Concepts *

Institute of Structures and Design

1

The authors contributed equally in research and data analysis. Fiona Kessel and Alex Heron-Himmel contributed equally to writing the paper and share first authorship.

2

© Springer Fachmedien Wiesbaden GmbH, ein Teil von Springer Nature 2020 M. Bargende et al. (Hrsg.), 20. Internationales Stuttgarter Symposium, Proceedings, https://doi.org/10.1007/978-3-658-29943-9_45

589

Study to assess the suitability of C/C-SiC as material for piston rings

1
Abstract The potential of ceramic matrix composites in a diversity of applications is being researched. High load brake disks have proven to be a successful adaptation of the materials properties for an automotive system. The paper summarizes the first steps towards the possibility of piston rings made from a ceramic matrix composite. After a brief description of the selected ceramic matrix composite the basic requirements for piston rings during assembly and operation as well as possibilities to assess the suitability are discussed. To achieve an overview of how the fibre orientation influences the material properties a selection of carbon fibre preforms are selected and processed into ceramic matrix composite piston rings before being tested. The results prove that one part C/C-SiC piston rings are possible as the basic strain during instalment on pistons is the first challenge to be assessed. Furthermore an insight towards the dependencies between fibre orientation and properties of the filigree piston rings is given. While the planed friction results are not available the manufacturing experience is discussed next to the strain test to form an initial assessment of the suitability. The results prove that C/C-SiC has potential as piston ring material and the tensile strength for assembly is demonstrated. Further research regarding the optimization of the preform or other manufacturing steps could prove to generate properties tailored to piston ring requirements.

2
Introduction Piston rings are an elementary part of an internal combustion engine. The multitude of partially conflicting tasks leads to a very high level of specialized research and development. The optimization of the geometric profile, the selection of coatings, the combination with lubrication and the cylinder liner material and its coatings are some of the fields in which piston rings have become very highly developed over the past decades [1],[2]. The next possible development in the field of piston rings could be achieved through solutions which allow a reduction of the number of piston rings from the usual three to two. As pistons with only two rings could be built slightly shorter, achieving an advantage in engine size, weight and vibrations. The DLR has looked into the adaptation of ceramic matrix composites into automotive technologies, specifically C/C-SiC brakes, in the past [3]. In follow-up discussions the question evolved whether a similar material could be used for piston rings. As the possibilities of modern manufacturing keep growing the limitations for the application of ceramic matrix composites are reduced. Therefore the DLR Institute of Structures and

590

Study to assess the suitability of C/C-SiC as material for piston rings Design joined the Institute of Vehicle Concepts in a small project to assess the basic suitability.

2.1 C/C-SiC a Ceramic Matrix Composite In the past development of ceramic matrix composites (CMC) the focus was on having a higher heat resistance than alloys and optimizing to maximal strain resistance so the material could be used in aerospace application [4]. With the growing amount of adaption in the aerospace industry the production price of CMC has been reduced. Thus other industries started to show interest and research is more actively looking into further adaptations. The DLR Institute of Structures and Design has acquired an intense knowledgebase regarding ceramic matrix composites for a variety of applications. One of the versatile material combinations is a carbon fibre/carbon – silicon carbide (C/C-SiC). The choice of the material is based upon following expectation. The carbon fibres will set the baseline for the flexibility of the product while the unbound carbon can serve as a solid lubricant to support the oil lubrication. The silicon carbide is the strong and hard counterpart material, which should ensure the durability and minimal wear of the piston ring.

Figure 1: LSI process for C/C-SiC [5]

591

Study to assess the suitability of C/C-SiC as material for piston rings In the past decades of research regarding C/C-SiC the DLR utilises the cost efficient liquid silicon infiltration (LSI) manufacturing process [6]. Figure 1 shows the basic steps, a carbon fibre reinforced polymer (CFRP) is shaped, then strongly heated in an oven in an oxygen free atmosphere to reduce the non-carbon elements and creating miniature gaps for the infiltration with silicon to commence the reaction to silicon carbide in and around the gaps. Nearly every step in the manufacturing process of ceramic matrix composites allows for an adaptation of the properties of the material [7]. For example different kinds of carbon fibre reinforced preforms will create C/C-SiC materials with divergent properties. A selection of preform techniques is described in section 4, they are used to produce multiple C/C-SiC piston ring samples allowing a comparison of the properties during this study.

2.2 Piston Ring Basic Properties A large amount of properties expected from piston ring materials are issued along the premise, that the material is an alloy and possibly has a non-metal coating. Likewise standard piston and cylinder liner materials are implied. This makes it difficult to evaluate a material that may offer larger changes to the lubrication system [8]. However some basic properties can be identified. Although it is possible to create multi segment piston rings, such a solution would outweigh most benefits in a mass production scale. Therefore the first basic property is that the piston ring is one part and can be mounted using existing methods, for example with piston ring pliers [9]. Figure 2 illustrates the steps during assembly, next to the opening of the piston ring gap, the necessity to withstand the compression to fit into the cylinder on the piston is evidentially the second part of this requirement.

Figure 2: Piston ring flexibility during assembly

592

Study to assess the suitability of C/C-SiC as material for piston rings As the friction of the piston ring will always stay a decisive factor, a baseline assessment of the frictional coefficient belongs to the basic properties. A statement regarding the possibility of the use of less viscous oil is complicated to prove but should be mentioned as a potential, which can be looked into in future. Basic loads on a piston ring in operation accumulate from the movement of the piston, the gas pressure and friction. More complicated effects such as ring twist, crowning, fluidity or ring flutter need a more detailed ring design which will only take place once the basic loads are be endured by simple C/C-SiC piston ring samples.

3 Simulation and Test Setup To assess the basic requirements calculations and simulations regarding strain and stress are carried out and key elements are tested in experiment. To create a simple and comparable piston ring sample the following simplified piston ring dimensions are selected to model an 82.5 mm piston ring. The sample is circular with an inside diameter of 80 mm and thickness and width of 3 mm. The initial gap in the simulation models is 16 mm and needs to open up to 25 mm while closing to about 2 mm.

3.1 Simulation of Basic Piston Ring Requirements In an early step to evaluate the feasibility of installing one part C/C-SiC rings onto a piston the strain was simulated in Ansys. The two steps of fitting a ring onto a piston, figure 2, are the initial two simulations. In all simulations C/C-SiC material data is set with a young’s modulus of 44.5 GPa and a Poisson’s rate of 0.15, not taking fibre orientation into account. The results of the opening of the ring are to be compared with the test rig results. The dynamic strain during piston motion is harder to recreate on a simple test ring, therefore it is only simulated. Thereby the piston ring was firmly set into the bottom side of the groove, to keep the simulation simple.

3.2 Test of Piston Ring Stress-Strain Curve There is no standard test for CMC rings, therefore a standard for a strength test of ceramic C-Rings (ASTM C1323 – 16) was adapted for the C/C-SiC test setup, figure 3. As the test additionally aimed to prove a far enough opening of the gap to allow the fitting of the ring over a piston, the gap opening was additionally measured with a goal of 30 mm to ensure fault tolerance.

593

Study to assess the suitability of C/C-SiC as material for piston rings

Figure 3: Stress-strain trial test with metal ring

Figure 4: Cylinder liner simulator [10]

3.3 Run-in Behaviour and Friction A further critical requirement for piston rings is the friction coefficient. A variation of coefficients is expected to be noted; depending on the carbon fibre orientation on the surface layer of the ring which is dependent of the preform creation method. The friction coefficient is measured on a cylinder-liner simulation test rig, figure 4. The ring segments are approximately 30 mm long and are moved with 50Hz and a stroke of 3mm. In combination with a nominal force of up to 250N this represents the motion around the top dead centre. During running-in of the ring segments only 150N will be applied. The measurements will consist of the frictional coefficient during running-in and a selection of operation points. Furthermore the surface of the ring segments and cylinder liner will be analysed optically.

4 C/C-SiC Preform Variation The transferability of the known C/C-SiC properties to a thin ring structure is very unsure. Depending on the carbon fibre preform and the resulting fibre orientation in the piston rings variations from the expected properties may accrue. Therefore a selection C/C-SiC ring samples with different preform variations is produced. Before the test results are presented the differences and difficulties during the production of the ring samples are described.

594

Study to assess the suitability of C/C-SiC as material for piston rings

4.1 Carbon Fibre Woven Plate One of the simplest preforms is created from a carbon fibre woven plate. From a large sheet with the right thickness the rings can be cut out directly. In the resulting rings the fibres have the same 90° orientation to each other, yet are not in a constant orientation towards the sliding surface, figure 5. A disadvantage is that this preform method creates a lot of waste material.

Figure 5: Schematic fibre orientation in rings from woven plate [11]

4.2 Carbon Fibre Woven Tube The next simplest preform is created from a standard carbon fibre fabric tube. From a tube with the right diameter and thickness the rings can be cut off. In the resulting rings the fibres are either oriented in circular or in the direction of ring motion. Either way tangential to the sliding surface, figure 6.

Figure 6: Schematic fibre orientation in rings from woven tube [10]

595

Study to assess the suitability of C/C-SiC as material for piston rings

4.3 Filament Winding Tube In filament winding, rovings are winded on a cylindrical core to give the textile structure. The angle of the roving placement is set to an 89° angel of the core axis, to make the highest use of the fibre length for the piston ring. Several winded layers are applied to the core to reach the sufficient component thickness, figure 7.

Figure 7: Schematic fibre orientation in rings from filament winding tube [10]

4.4 Tailored Fibre Placement (TFP) TFP is embroidery of the preform, which gives higher variability of fibre orientation in the piston ring, e.g. figure 8. At the time this method is too expensive for a mass production of piston rings, however it could allow significant insight into how the fibre orientation changes the material behaviour in piston ring geometry.

Figure 8: Schematic possible fibre orientation of rings with tailored fibre placement

596

Study to assess the suitability of C/C-SiC as material for piston rings

5 Results and Discussion 5.1 Simulation As describe above the first challenge is to prove a C/C-SiC ring can withstand the strain during assembly onto a piston. The basic Ansys Simulation delivered the results in table 1 proving that the ring should be able to be opened far enough. Table 1: Simulation results of spreading a C/C-SiC piston ring sample Force (each side) 1N 3N 5N 7N 9N 11 N 13 N

Maximum Stress 9, 3 MPa 27,8 MPa 46,6 MPa 65,3 MPa 83,9 MPa 102,6 MPa 121,2 MPa

Gap Opening 16mm + 2 x 0,4 mm = 16,8 mm 16mm + 2 x 1,3 mm = 17,6 mm 16mm + 2 x 2,2 mm = 20,4 mm 16mm + 2 x 3 mm = 22 mm 16mm + 2 x 3,9 mm = 23,8 mm 16mm + 2 x 4,8 mm = 26, 6 mm 16mm + 2 x 5,7 mm = 27,4 mm

The simulation of the equivalent stress of a compressed piston ring, figure 9 results in similar stress as the opening. As described above the ring sample geometry does not represent a ring which would close to a perfect circle and create an ideal radial pressure distribution. Furthermore no optimization of the gap size in regards to the short strain during fitting and the ongoing strain of the compressed ring took place.

Figure 9: Simulation of a compressed C/C-SiC piston ring sample

597

Study to assess the suitability of C/C-SiC as material for piston rings In the simulation the basic loads on a piston ring in running conditions do not create any critical conditions. Special effects that may arise will need to be accounted for in future work e.g. due to different inertial of the piston rings. The simulation in this work is basic, proving assembly is possible. Trying to analyse the different preform solutions solely in simulation would have proven difficult. The material properties of a composite material such as of C/C-SiC can be very dependant of the geometry. Attempts at more detailed simulations will need further input. Detailed material models for the most promising preforms could be adapted with the results of the experimental strength test. However future work cannot purely rely on simulation results. Creating real samples and experimental test rigs is necessary to verify statements established upon simulation results.

5.2 Piston Ring Strength The tensile testing in accordance to ASTM C1323 – 16 is performed as the simulation does not account for fibre orientation in the C/C-SiC structure. Especially in order to compare the different preforming methods, pure simulation is not sufficient. Therefore multiple piston ring samples of each preform are tested. The aim for the gap opening during tensile testing is determined as opening up the 16 mm initial gap to an opening of 30 mm for assemble. Using (01) the resulting strain for this requirement is 87.5 %.         


 

(01)

Structure strain



Initial gap opening




Difference in gap opening and initial gap opening

So the aim for the C/C-SiC piston rings is surpassing this mark. Initially four different preform types run through the manufacturing process. However the TFP based piston rings didn’t retain their shape during pyrolysis and thus cannot be tested. The three other types (woven plate, woven tube, filament winding) are successfully processed and the results are shown in figure 10. The woven plate samples are the only to reach the targeted structure strain of 87.5 %. The woven based tube did not endure the structure strain and failed at roughly 55 %. Also the winded tube did not reach the necessary structure strain, however it has an impressively high tensile strength before collapsing.

598

Study to assess the suitability of C/C-SiC as material for piston rings

Figure 10: Stress in regards to structure strain of the preform sample rings

Since the material composition (C-, Si- and SiC- phases) of the tested C/C-SiC piston ring varieties is very similar, the authors come to the conclusion that the fibre orientation created the mayor impact to the structure strain results. The simplest fibre reinforcement is created by the filament winding. The winding layers are parallel to the rotation axis while the filaments inside the layers are winded at 89° degree to the rotation axis. Thus very high tensile strength and a stiff structure are the result. This stiffness made the structure unable to achieve the required gap opening. For the woven tube the layer arrangement is similar (layers parallel to rotation axis). Regarding fibre orientation inside the layers the degree distribution was 1:1 0° and 90° to the rotation axis. This leads to a reduced tensile strength and a reduced stiffness. While the reduced stiffness is favourable, the remaining tensile strength is too low to meet the demand in structure strain. For the woven plate the layer arrangement is orthogonal to the rotation axis and the fibres inside the layers are oriented in 90° and 0°. Regarding the piston ring geometry this leads to an anisotropic fibre orientation which seems to be key for the high structure strain, as the fibres give a balanced damage tolerance to the ceramic martial, without stiffening the structure.

599

Study to assess the suitability of C/C-SiC as material for piston rings Indeed the result demonstrates that both woven structures fail at a comparable stress level while the structure strain is completely different. This shows that stiffness could be adjusted to a favourable amount such that the component will not be deformed in the application while being so low that the structure strain allows uncritical mounting. The results show that mountable C/C-SiC piston rings are possible. However the preform with sufficient properties has a disadvantage in manufacturing since a huge amount of material waste is produced while cutting rings from woven plates. Yet it is expected that tubular semi-finished products as given with filament winding could be developed with the properties necessary for piston rings. This would be a considerably more economical approach to manufacturing piston rings. Furthermore with additional resources the complications in pyrolysis of TFP rings could be solved, allowing for even more selective material properties.

5.3 Friction Measurements Problems with the test bench resulted in a delay of over six months for our friction coefficient measurements. Therefore no detailed assessment is possible at this moment. Next to the frictional coefficient test, pin-on-disc tribometer experiments may follow in future to gain a more understanding of the detailed surface behaviour in a fashion seen e.g. in diamond like carbon coating research [12].

6 Summary and Outlook Most research in regard to piston rings further the state of the art by creating or optimising coatings and the friction partners. In contrast this work looks at the possibility of a new material for piston rings. To assess C/C-SiC initial calculations and simulations tool place. With the first positive results supporting the estimates test rig experiments are considered to prove baseline suitability. The production of the C/C-SiC piston ring samples takes place with preforms from woven plates, woven tube, filament winded tubes and tailored fibre placement. In stress-strain experiments the samples prove C/C-SiC is capable of the flexibility necessary to serve as one-piece piston ring. In the results the strong influence of the differences in carbon fibre orientation of the preforms is also observed. As not all viable preform options have been regarded in this study further research is necessary to determine a preform optimised regarding assembly strain, friction behaviour and economic manufacturing methods. Furthermore research regarding the optimization of the ring geometry taking the fibre orientation and the preform process into regards is essential for future research. To generate the maximum benefit during these

600

Study to assess the suitability of C/C-SiC as material for piston rings next steps collaboration with knowledgeable partners in CMC manufacturing, piston rings and piston engine is desired.

Bibliography 1.
Senatore, A., and Aleksendric, D. (2013). Advances in piston rings modelling and design. Recent Patents on Engineering, 7(1), 51-67. doi:10.2174/ 1872212111307010005 2.
Cha, S. C., and Erdemir, A. (2015). Coating technology for vehicle applications. Book; doi:10.1007/978-3-319-14771-0 3.
Koch, D. and Heidenreich, B. and Shi, Y. and Klopsch, L. and Kessel, F. (2019) Carbon fiber based ceramic brake materials - concepts and applications. 10th International Conference on High Temperature Ceramic Matrix Composites (HTCMC 10), 20.-22. Sept.2019, Bordeaux, Frankreich. 4.
Heidenreich, B. and Zuber, C. and Toro, S. and Nardi, M. (2013) C/C
SiC friction pads for an aircraft propeller brake. In: (DGM) DGfMeV, editor. DGM 19 Symposium Verbundwerkstoffe und Werkstoffverbunde; 03.
05.07.2013 Karlsruhe, Germany. 5.
Krenkel, W. (2003), C/C-SiC composites for hot structures and advanced friction systems, presented at the 27th Cocoa Beach Conference & Exposition. 6.
Gern, F. H. and Kochendörfer, R. (1997) Liquid silicon infiltration: description of infiltration dynamics and silicon carbide formation, Composites Part A: Applied Science and Manufacturing, vol. 28, no. 4, pp. 355-364, 1997/01/01. 7.
Heidenreich, B. and Jain, N. and Postler, K. and Koch, D. and Schneck, T. K. and Hermanutz, F. and Clauß, B. and Buchmeiser, M. R. and Brück, B. and Schulz, M. and Müller, W. and Horn, S. R. (2019) C/C-SiC Materials Based on High Performance C Fibres with Tailored Fibre-Matrix Bonding. 10th International Conference on High Temperature Ceramic Matrix Composites (HTCMC 10), 20.-22. Sept. 2019, Bordeaux, Frankreich. 8.
Hannemann F. (2018) Gesamtheitlicher Ansatz zur Optimierung der Reibpartner Kolbenring / Zylinderlaufbahn mithilfe von Einzylinder-Versuchen. In: Roß T., Heine A. (eds) Der Verbrennungsmotor - ein Antrieb mit Vergangenheit und Zukunft. Springer Vieweg, Wiesbaden 9.
MS Motorservice International GmbH, (2018), Kolbenringe für Verbrennungsmotoren, Neuenstadt, MS Motorservice International GmbH

601

Study to assess the suitability of C/C-SiC as material for piston rings 10.
Fraunhofer IWM, Tribologie auf Komponentenebene - Fraunhofer IWM, (2019), https://www.iwm.fraunhofer.de 11.
Virsik, R. and Koch, D. (2017), DE Patent No. 102017113433, Deutsches Patentund Markenamt 12.
Rübig, B. and Heim, D. and Forsich, C. et al., (2017), Tribological behavior of thick DLC coatings under lubricated conditions, Surface and Coatings Technology, Volume 314, Pages 13-17, ISSN 0257-8972

602

Experimental and numerical investigations of NO2 and HCHO formation in lean gas engines D. Notheis, U. Wagner, A. Velji, T. Koch*1 F. Poschen, M. Olzmann*2 *1 Institut für Kolbenmaschinen, Karlsruher Institut für Technologie *2 Institut für Physikalische Chemie, Abteilung für Molekulare Physikalische Chemie, Karlsruher Institut für Technologie

This manuscript is not available according to publishing restriction. Thank you for your understanding.

© Springer Fachmedien Wiesbaden GmbH, ein Teil von Springer Nature 2020 M. Bargende et al. (Hrsg.), 20. Internationales Stuttgarter Symposium, Proceedings, https://doi.org/10.1007/978-3-658-29943-9_46

603

Investigations of interactions between fuels and fuels leading components of plug-inhybrid electrical vehicles

Dr. Wilfried Plum, Sebastian Feldhoff OWI gGmbH Prof. Markus Jakob, Jens Staufenbiel Hochschule Coburg

© Springer Fachmedien Wiesbaden GmbH, ein Teil von Springer Nature 2020 M. Bargende et al. (Hrsg.), 20. Internationales Stuttgarter Symposium, Proceedings, https://doi.org/10.1007/978-3-658-29943-9_47

605

Investigations of interactions between fuels and fuels leading components of …

1 Motivation The new European emission standard defines that the fleet-average CO2 emission of cars and vans shall not exceed 61.75 g CO2 / km from 2030 onwards [1]. From current point of view, these CO2 emission limits cannot be achieved by vehicle fleets, which are driven by conventional combustion engines only. As a result, hybridized powertrain systems such as plug-in hybrid electric vehicles (PHEVs) are promising technologies, since periods of fully electric driving are considered with 0 g CO2 emission in a tank-to-wheel balance. On the contrary side, a long-term use of the electric powertrain only due to short-distance trips [2] can lead to changing of fuel properties. However, the interaction of fuel and components over time could also result in malfunctions of these components. As a result, the investigations are an important topic for future power train developments. The researches of this project are focused on fuel storage effects and the interactions with components, which could result from an isolated long-term use of a PHEV vehicle in electric drive. Moreover, the investigations are planned in wide-screening approach with many fuels and hardware components, since the long-term storage effects are hardly described in literature by now. Figure 1 shows an extract of the complete screening matrix with investigated fuels listed on the left and investigated components listed on the right. It can be seen that this research projects includes gasoline and diesel related fuels. Both fuel types have been considered although most PHEV fuels are using spark-ignition engines, so that the investigation on gasoline and related components are of most interest. Nevertheless, the component investigations include gasoline and diesel related hoses, filters, pumps and injectors to consider a wide range of fuel guiding components within these investigations, too.

Figure 1: Extract of the screening matrix, which was investigated in the context of this project

606

Investigations of interactions between fuels and fuels leading components of … In order to apply a systematic approach, the project was separated into three steps. The first step of the project was focused on fuel aging investigations themselves. Here, defined fuel samples were stored and aged for up to 9 months in chemical laboratory facilities under accelerated conditions to investigated the effects of long-term fuel storage without the cross-effects of the hardware components. The second project step included fuel sample interaction with corresponding hardware components. This means that the filters, hoses, injectors and pumps were checked for proper operation and then filled with the fresh fuel samples before being stored in laboratory facilities for up to 9 months under accelerated conditions. The final tests of project part number checked the functionality of these components after the corresponding period. The third project part focused on the chemical analysis of the fuel samples that could be extracted from the stored hardware components. These fuel samples were used to checked if significant hardware changes could be related to fuel changing effects or vice versa. The following paper is focused on the investigations of two exemplary gasoline fuels and three exemplary diesel fuels from the context of this project. Moreover, the hardware investigations, which are shown in this paper, are limited to the injector investigation only results for brevity purposes. The chapter of technical results is separated into the two parts of chemical analysis and hardware analysis. The complete investigation results will of course be given in the final report.

2 Technical
results 2.1 Chemical fuel investigations As described earlier, a long-term use of PHEV vehicles in electric mode only can result in fuel changing effects, which can significantly impair the fuel properties themselves. As a result, the first part of this research project is focused on the investigation of long-term storage effects on gasoline and diesel related fuels themselves. In order to provide a structured description, this chapter is separated into the results gasoline and diesel related results before describing the corresponding hardware results in chapter 2.2.

2.1.1 Chemical fuel investigations of gasoline related fuels The gasoline fuel investigations are based on the initial identification of a representative fuel reference to ensure that the laboratory gasoline investigation generates a realistic result. The corresponding reference was given by a fuel sample of a vintage car, which was stored and not refilled for 4 consecutive years. As a result, this vintage-car fuel sample represents a worst-case of fuel changing tendencies.

607

Investigations of interactions between fuels and fuels leading components of …

Figure 2: Vapor pressure of E0, E20 (stored in closed bottles and in bottles equipped with purge valves at 50°C in a climate chamber) and of a vintage car fuel

Figure 3: Volatile fraction (