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 2007-01-0273 Defining the General Motors 2-Mode Hybrid Transmission Tim M. Grewe, Brendan M. Conlon and Alan G. Holmes General Motors Reprinted From: Advanced Hybr id Vehicle Powertrains, 2007 (SP-2101) 2007 World Congress Detroit, Michigan April 16-19, 2007 By 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 ofthe 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 Service Tel: 877-606-7323 (inside USA and Canada)Tel: 724-776-4970 (outside USA)Fax: 724-776-0790Email: Customer [email protected] ISSN 0148-7191 Copyright © 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 the manuscript or a 300 word abstract of a proposed manuscript to: Secretary, Engineering Meetings Board, SAE. Printed in USADefining the General Motors 2-Mode Hybrid Transmission Tim M. Grewe, Brendan M. Conlon and Alan G. Holmes General Motors Copyright © 2007 SAE International ABSTRACT The new General Motors 2-Mode Hybrid transmission for full-size, full-utility SUVs integrates two electro-mechanical power-split operating modes with four fixed gear ratios and provides fuel savings from electric assist, regenerative braking and low-speed electric vehicle operation. A combination of two power-split modes reduces the amount of mechanical power that must be converted to electricity for continuously variable transmission operation. Four fixed gear ratios further improve power transmission capacity and efficiency for especially demanding maneuvers such as full acceleration, hill climbing, and towing. This paper explains the basics of electro-mechanical power-split transmissions, input-split and compound-split modes, and the addition of fixed gear ratios to these modes to create the 2-Mode Hybrid transmission for SUVs. INTRODUCTION The 2-Mode Hybrid transmission for SUVs is an electrically variable transmission, which uses electric motors to operate at nearly any speed ratio through the transmission. The electric motors in the transmission also allow hybrid functions: electric vehicle operation, electric boost, and regenerative braking, as well as engine starting. The 2-Mode Hybrid transmission is also an automatic transmission, without a torque converter but with conventional hydraulically-applied wet-plate clutches to allow automatic shifting among two continuously variable modes and four fixed gears, a total of six mechanical configurations: EVT mode 1, EVT mode 2, and fixed gears 1 through 4. This combination is fully integrated into a package very much like a conventional automatic transmission, with added wires leading to electronic controls and a high-voltage battery. DEVELOPMENT OF THE 2-MODE HYBRID An electrically variable transmission or EVT uses electric motors to control its speed ratio, giving it a continuous choice of ratios. The input, output, and electric motors are connected to planetary gearing. In a set of planetary gears, the speed of a p