400 Commonwealth Drive, Warrendale, PA 15096-0001 U.S.A. Tel: (724) 776-4841 Fax: (724) 776-0790 Web: www.sae.org SAE TECHNICAL PAPER SERIES 2007-01-0272 Two-Mode Urban Transit Hybrid Bus In-Use Fuel Economy Results from 20 Million Fleet Miles Peter K. Chiang General Motors Powertrain Reprinted From: Advanced Hybr id Vehicle Powertrains, 2007 (SP-2101) 2007 World Congress Detroit, Michigan April 16-19, 2007 Downloaded from SAE International by Univ of California Berkeley, Sunday, August 05, 2018By mandate of the Engin eering Meetings Board, th is paper has been approved for SAE publication upon completion of a peer review process by a minimum of three (3) industry experts under the supervision of the session organizer. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise,without the prior written permission of SAE. For permission and licensing requests contact: SAE Permissions 400 Commonwealth DriveWarrendale, PA 15096-0001-USAEmail: [email protected]: 724-776-3036Tel: 724-772-4028 For multiple print copies contact: SAE Customer ServiceTel: 877-606-7323 (inside USA and Canada)Tel: 724-776-4970 (outside USA)Fax: 724-776-0790Email: Customer [email protected] ISSN 0148-7191Copyright © 2007 SAE InternationalPositions and opinions advanced in this paper are those of the author(s) and not necessarily those of SAE.The author is solely responsible for the content of the paper. A process is available by which discussions will be printed with the pap er if it is publishe d in SAE Transactions. Persons wishing to submit papers to be considered for presentation or publication by SAE should send themanuscript or a 300 word abstract of a proposed manuscript to: Secretary, Engineering Meetings Board, SAE. Printed in USADownloaded from SAE International by Univ of California Berkeley, Sunday, August 05, 2018AB STRACT The General Motors Allison Two-Mode compound split parallel hybrid EP system for transit buses has been in production for over three years, accumulating over 20 million fleet miles. During this period of operation, extensive fuel economy analysis has been performed over multiple use cycles in multiple locations. This paper describes the in-use fuel economy results, as well as the hybrid system mode operations, the component utilization, and thecontrols improvements to maximize the hybrid fuel economy. Actual in-use data will be presented from individual vehicles, as well as the fleet averages encompassing a broad range of duty cycles. A chassis dynamometer testing results are discussed as an alternative evaluation method. INTRODUCTION The GM Allison Hybrid EP40 SystemTM and EP50 SystemTM have been a major technological advance for the bus transit industry. The EP40 and EP50 Systems give the transit industry the ability to provide higher ride quality with less noise, diminished environmental impact, and reduced fuel consumption. The objective of this paper is to summarize and illustrate how the GM Allison Hybrid E P40/50 system acts to achieve these benefits. Prior to production, the development team was given several production design objectives: improve fuel economy, reduce gaseous emissions, and provide superior ride and drive performance. City transit bus fleets are major fuel consumers and emission producers, and the stop-and-go nature of transit driving cycles plays to the strength of hybrid powertrains. The Allison business team strategically chose to release the GM Hybrid E P40 and EP50 SystemTM into the transit bus fleets, where the hybrid system can produce the greatest payback for metropolitan city customers from environmental and economic standpoints. Since the start of production, more than 600 E P40 SystemTM and EP50 SystemTMhave been sold and installed into transit buses, such as 60’ articulated buses, 40’ transit buses, and 45’ coaches