400 Commonwealth Drive, Warrendale, PA 15096-0001 U.S.A. Tel: (724) 776-4841 Fax: (724) 776-5760 Web: www.sae.org SAE TECHNICAL PAPER SERIES 2006-01-0149 Development of a Super-Flat Torque Converter for the New Toyota FWD 6-Speed Automatic Transaxle Toru Ochi, Hiroaki Takeuchi, Hiromi chi Kimura and Kazuyuki Watanabe Toyota Motor Corp. Reprinted From: Tran smission and Driveline 2006 (SP-2001) 2006 SAE World Congress Detroit, Michigan April 3-6, 2006 Downloaded from SAE International by Brought to you by the University of Texas Libraries, Sunday, August 05, 2018The Engineering Meetings Board has approved this paper for publication. It has successfully completed SAE's peer review process under th e supervision of the session organi zer. This process requires a minimum of three (3) reviews by industry experts. 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]: 724-772-4028 Fax: 724-776-3036 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: [email protected] ISSN 0148-7191 Copyright © 2006 SAE International Positions 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 th e 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 publicat ion by SAE should send the manuscript or a 300 word abstract to Secretary, Engineering Meetings Board, SAE. Printed in USADownloaded from SAE International by Brought to you by the University of Texas Libraries, Sunday, August 05, 2018ABSTRACT Toyota Motor Corporation has developed a new super- flat torque converter for the Flex Start System. It is installed in a new six-speed automatic transaxle (U660E) for front engine, front wheel drive vehicles. The Flex Start System is the first technology in the world that can start smoothly and reduce torque converter slipping loss by using a lock-up clutch at start. The newly developed super-flat torus achieves a high torque capacity and a maximum efficiency of 90%. Fuel economy is increased further by adding an efficient damper for low-speed lock-up in the free space provided by utilizing the super-flat torus. Toyota also developed a simple and super-flat s tructure at the one-way clutch (O.W.C.) area. This paper describes the structure, features, and performance of this new torque converter and the Flex Start System. INTRODUCTION The torque converter is the main device as the starting clutch of the automatic transmission, because it provides smooth driving performance at a low cost. On the other hand, shortening of the shaft length is required in order to improve the installation in engine compartment. Its efficiency must also increase in order to improve fuel economy and reduce CO2 emissions. However, a tradeoff is required, because the miniaturization of the torque converter causes a decrease the transmission efficiency in general, and leads to fuel consumption increase. Therefore a small torque converter with high efficiency is demanded. Lock up is an effective means to reduce slipping loss of a converter. çImproving the Lock up clutch damper’s performance makes it possible to expand the area of Lock up clutch operation. Furthermore, due to the advancement of the power performance by increasing shift stages and the precise and highly responsive lock- up control system, it was possible to aim at improving acceleration perform