tesoutce For 'Obility 400 COMMONWEALTH DRIVE WARRENDALE, PA 15096 840448 Manfred Schwab Robert Bosch GmbH, Stuttgart Reprinted from SP-572- New Developments in Electronic Engine Management International Congress & Exposition Detroit, Michigan February 27-March 2,1984 Downloaded from SAE International by North Carolina State Univ, Tuesday, September 18, 2018ISSN 0148-7191 Copyright 1984 Society of Automotive Engineers, Inc. This paper is subject to revision. Statements and opinions ad­ vanced in papers or discussion are the author's and are his responsibility, not SAE's; however, the paper has been edited by SAE for uniform styling and format. Discussion will be printed with the paper if it is published in SAE Transactions. For permission to publish this paper in full or in part, contact the SAJE Publications Division. Persons wishing to submit papers to be considered for pre­ sentation or publication through SAE should send the manu­ script or a 300 word abstract of a proposed manuscript to: Secretary, Engineering Activity Board, SAE. Printed in U.S.A. Downloaded from SAE International by North Carolina State Univ, Tuesday, September 18, 2018840448 Electronic Control of a 4-Speed Automatic Transmission with Lock-Up Clutch Manfred Schwab Robert Bosch GmbH, Stuttgart ABSTRACT The paper describes the electronic control of an automatic 14-speed transmission with lock-up clutch. As compared to purely hydraulically con­ trolled transmissions, this control offers a clearly improved quality of shifting and the possibility of achieving improvements in fuel consumption thanks to a special economy program. The electronic control unit is a Bosch MOTROKIC which has been expanded to include the functions of transmission control. A special feature is the engine torque control which is implemented by way of retarding the ignition when shifting. This opens up an additional degree of freedom for optimising & .transmission in terms of shift comfort, life of the friction elements and the ■Dover which can be transmitted. Development work on electronic transmission con­ trols has been in progress for several years worldwide. This is because several advantages can be expected over purely hydraulic control: - Implementation of various shift programs, e.g. optimized for fuel economy or performance - Improved shift comfort thanks to sophistica­ ted control strategies - Flexibility in adaption to different vehic­ les and engines by means of memory programming - Implementation of new functions So far shift point controls and lock-up controls have been the main subject of reports /1//2/. This paper presents a complete electronic trans­ mission control which has been developed to the series-production stage by Robert Bosch GmbH in cooperation with Zahnradfabrik Friedrichshafen AG and Bayerische Motorenwerke AG. This trans­ mission control also includes shift quality con­ trol. It is shown that here too electronics of­ fers important new aspects and functional im­ provements j in particular through interaction with other electronics systems. 2i_§ISTBH_DESCRIFTI0N 2.1 Transmission The kHF22 E transmission is a new development by ZF based on the 3 HP 22 model /3/A/. An additio­ nal downline planetary gear train provides a fourth gear with overdrive characteristics. The drive is through hydrodynamic torque converter which can be locked up by means of a clutch. In the hydraulic control the mechanical governor and the load-dependent pressure control via "bow- den cable were replaced by electrohydraulic ac­ tuators for gear selection and pressure control. The only mechanical connection to the transmis­ sion is from the selector lever by means of which three different hydraulic channels are selected in the positions R, H and D, 3, 2, 1. 2.2 Electronic control unit The electronic control unit {Fig. 1) is an ex­ pansion of the Bosch MOTROKIC system /5/ which, in its basic form, combines t