SA E TECHNICAL PAPER SERIES An Advanced Electronic Control and Diagnostic System for Automatic Transmission Bernhard Wust and Manfred Bek J. M. Voith GmbH The Engineering Society =For Advancing Mobi\ity and sea ~ir and ~mce- International Truck & Bus Meeting & Exposition Seattle, Washington L1-s-nher 7-Q 1 QQd I.UVCIl.--. . ,, . ,, , 400 Commonwealth Drive, Warrendale, PA 15096-0001 U.S.A. Tel: (41 2)776-4841 Fax:(412)776-5760 Downloaded from SAE International by North Carolina State Univ, Saturday, September 15, 2018Theappearance ofthe ISSN code atthe bottom of thii page indicates SAE'sconsent that copies of the paper may be made for personal or internal use of speclfc clients. Thisconsent is given on the wnditimn, however.thattiw mpierpay a$!i.OOperartjcle co~v fee throuah the Co~vrioht Clearance Center. Inc. Ooerations Center. 222 .. .. ~dskood D&. Danvers. MA 01 923forwpying be;ondtha&mnMted by ~ekons 107 or 1M) of the U.S. Copyright Law. This consent does not extend to other Wnds of copying such as copying for general distributimn. for adverlising or promotional pum, for creating new collective works, or for &. SAE rouf~nely stocks printed papers for a period of three years following date of publication. Direct your orders to SAE Customer Sales and Satisfaction Department Quantity reprint rates can be obtained fmm the Customer Sales and Satisfaction Department To request permission to reprint a technical paper or permission to us$ copyrighted SAE publications in other works, contact the SAE Publications Gmup. All SAE pspers, &dads, and WeztW bwlrsamsbrbeclodandin&mdintb Globel Wlny Datsbese. No part of this publication may by reproduced in any form, in an electronic retrieval system or otherwise, without the prior written permission of the publisher. ISSN 0146-7191 CopyrigM 1994 Society of Automotive Engineers, Inc. Positions and opinions advaracsd in this paper are those of the author(6) and not necessarily those of SAE. The author is solely responsibie for the content of the paper. A process is available by which discussions will be printed with the paper M it is published in SAE transadions. For permission to publish this paper in full or in part, contact the SAE Publications Group. Persons wishing to submit papers to be considered for presentation or puMitbn through SAE should send the manuscrip1 or a 300 word abstract of a proposed manuscript to: Secretaly, Engineering Activity Board, SAE. Plinted in USA m.1- Downloaded from SAE International by North Carolina State Univ, Saturday, September 15, 2018An Advanced Electronic Control and Diagnostic System for Automatic Transmission Bernhard Wust and Manfred Bsk J. M. Voith GmbH ABSTRACT The functions, design and mode of operation of a new electronic control system for automatic transmissions for ciw buses are described. Apart from the dual-channel computer structure for safety functions used here for the fim time for electronic transmission control, the principal features of the control unit are its capability of communication, its high level of self-diagnosis, and its modular structure. Furthermore, a new type of actuator has been developed in the form of pressure control solenoid valves. Gearshift programs depending on driving resistance reduce fuel consumption while ensuring optimum drivabiiity. The control pressure required for maintaining a given target slip time is computed in advance with the aid of a simulation model of the transmission memorized in the electronic control unit. Deviations due to tolerances or aging are compensated by adaptive correction of the control pressure. The automatic adaptation to changing conditions leads to a constantly high level of comfort in respect of gearshifts over the entire lifetime. 1. INTRODUCTION The demands made on environmental compatibility, economy, driving comfort, reliability and safety of city buses are continually increasing. A vital role is p