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 SERIES2005-01-3890 Flash Temperature in Clutches T. M. Cameron Kettering University T. McCombs, S. Tersigni and T.-C. Jao Afton Chemical Corporation Powertrain & Fluid Systems Conference and Exhibition San Antonio, Texas USA October 24-27, 2005Downloaded from SAE International by University of Michigan, Sunday, July 29, 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: 724-776-1615Email: Customer [email protected] ISSN 0148-7191Copyright © 2005 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 University of Michigan, Sunday, July 29, 20182005-01-3890 Flash Temperature in Clutches T. M. Cameron Kettering University T. McCombs, S. Tersigni and T.-C. Jao Afton Chemical Corporation Copyright © 2005 SAE International ABSTRACT Sliding contact between friction surfaces occurs in nu- merous torque transfer elements: torque converter clutches, shifting clutches, launch or starting clutches, limited slip differential clutches, and in the meshing of gear teeth under load. The total temperature in a friction interface is the sum of the equilibrium temperature with no sliding and a transient temperature rise, the flash temperature , caused by the work done while sliding. In a wet shifting clutch the equilibrium temperature is typically the bulk oil temperature and the flash temperature is the temperature rise during clutch engagement. The flash temperature is an important factor in the performance and durability of a clutch since it affects such things as the reactivity of the sliding surfaces and lubricant con-stituents (e.g., oxidation) and thermal stress in the com-ponents. Knowing how high the flash temperature be-comes is valuable for the formulation of ATF, gear oil, engine oil and other lubricants. This paper presents two models for approximating flash temperature in clutch interfaces for: (1) a large thermal mass with a good conduction path to an equilibrium tem-perature boundary, and (2) a small thermal mass without a good conduction path to a constant temperature boundary. The explicit expressions given for flash tem-perature in terms of material and friction properties are useful for applications such as estimating thermal effects on the lubricant and changes in the friction properties and clutch torque. Friction heating expressions for differ-ent slipping conditions are given and are used in the models to predict surface flash temperatures for specific cases: (a) plate #1 (front steel plate) in SAE #2 rig tests such as the MERCON ® V and DEXRON® III H friction tests, (b) plate #3 (interior steel plate) in SAE #2 tests, and (c) the steel plate in an LVF