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 2007-01-3976 Development of Next-Generation Automatic Transmission Fluid Technology Sung Choon Yoo and Sang Yeob Cha Hyundai Motor Company and Kia Motor Corporation Masahiko Ikeda and Isao Nakagawa Lubrizol International Laboratory for Asia Pacific Hyun-Soo Hong The Lubrizol Corporation Powertrain & Fluid Systems Conference & Exhibition Rosemont, Illinois October 29-November 1, 2007Downloaded from SAE International by University of Liverpool, Monday, September 10, 2018The Engineering Meetings Board has approved this paper for publication. It has successfully completed SAE's peer review process under the supervision of the session organizer. 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 © 2007 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 the paper. A process is available by which discussions will be printed with the paper if it is published 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 to Secretary, Engineering Meetings Board, SAE. Printed in USADownloaded from SAE International by University of Liverpool, Monday, September 10, 20181ABSTRACT Global o riginal equipment manufacturers (OEMs) have requested lower viscosity automatic transmission fluid (ATF) for use in conventional and 6-speed automatic transmissions (AT) to meet growing demands for improved fuel economy. While lower-viscosity ATF may provide better fuel economy by reducing churning losses, other key performance attributes must be considered when formulating lower viscosity ATF (1,2). Gear and bearing performance can be key concerns with lower-viscosity ATFs due to reduced film thickness at the surfaces. Long-term anti-shudder performance is also needed to enable the aggressive use of controlled slip torque converter clutches that permit better fuel economy. And, friction characteristics need to be improved for higher clutch holding capacity and good clutch engagement performance. This paper covers the development of next-generation, low-viscosity ATF technology, which provides optimum fuel economy along with wear and friction durability. Low Velocity Friction Apparatus (LVFA), SAE #2, and FZG pitting tester were used to develop the technology. Also a test using current transmission was developed to measure the fuel economy of test fluids. The technology developed provides excellent fuel economy, measured by actual transmissions, while providing superior gear and bearing protection, optimized friction characteristics and excellent shear stability. INTRODUCTION Demand for better fuel economy to meet strict government legislation on carbon dioxide (CO 2) emissions and ever-increasing crude oil costs accelerated the development of new fuel efficient transmissions over the past 20 years. New transmissions such as the continuously variable transmission (CVT), traction drives or infinitely variable transmission (IVT), and dual clutch transmission (DCT) have been introduced in the market to provide b