The Engineering Resource For Advancing Mobility 400 COMMONWEALTH DRIVE WARRENDALE, PA 15096 Yutaka Taga, Kazumasa Nakamura, and Hiroshi Ifo Chassis and Drive Train Engineering Dept. Toyota Motor Co., Ltd. Takao Taniguchi Product Engineering and Development Dept. Aisin-Warner, Ltd. Passenger Car Meeting Troy, Michigan June 7-10,1982 Downloaded from SAE International by University of Auckland, Saturday, September 29, 2018The appearance of the code at the bottom of the first page of this paper indicates SAE's consent that copies of the paper may be made for personal or internal use, or for the persona! or internal use of specific clients. This consent is given on the con­ dition, however, that the copier pay the stated per article copy fee through the Copyright Clearance Center, Inc., Operations Center, 21 Congress St., Salem, MA 01970 for copying beyond that permitted by Sections 107 or 108 of the U.S. Copyright Law. This consent does not extend to other kinds of copying such as copying for general distribution, for advertising or promotional purposes, for creating new collec­ tive works, or for resale. Papers published prior to 1978 may also be copied at a per paper fee of $2.50 under the above stated conditions. SAE routinely stocks printed papers for a period of three years following date of publication. Direct your orders to SAE Order Department. To obtain quantity reprint rates, permission to reprint a technical paper or per­ mission to use copyrighted SAE publications in other works, contact the SAE Publica­ tions Division. ISSN 0148-7191 Copyright 1982 Society of Automotive Engineers, inc. Downloaded from SAE International by University of Auckland, Saturday, September 29, 2018820740 Yutaka Taga, Kazumasa Nakamura, and Hiroshi Ito Chassis and Drive Train Engineering Dept. Toyota Motor Co., Ltd. Takao Taniguchi Product Engineering and Development Dept. Aisin-Warner, Ltd. ABSTRACT As the computer control concept develops, its application has potential answers to better fuel economy requirements in the automotive industry. Under overall programs to upgrade the total vehicle performance, Toyota has been developing automatic transmissions systemati­ cally. A new automatic transmission employing a microcomputer was introduced for better economy and driveability. The microcomputer controls shift and lock-up clutch operating schedules. The transmission ensures mechanical coupling from the low gear for high efficiency while maintaining superior shift quality with the lock-up clutch control during shift transi­ tion. It also offers shift pattern selection for various driving conditions and driver's preference. FUEL ECONOMY IMPROVEMENT in automobiles is one of the major requirements for effective utili­ zation of the limited source of petroleum. From the viewpoint of vehicle functions, improvements in the performance and passenger comfort are also essential subjects of the automotive engineering. To meet these requirements, Toyota Motor Co., Ltd. has continued the developments in all concerned areas. Particularly in power train, great efforts have been made to design more fuel-efficient automatic transmissions while providing higher level of vehicle performances and passenger comfort under systematic and long term programs for improving the total vehicle performance. In 1977, the four-speed automatic transmission with overdrive (1)* was introduced, reducing fuel consumption and interior noise successfully. Further, in 1980, to achieve higher efficiency and performances, a new ellip­ tic torque converter incorporating a lock-up clutch was developed for the four-speed auto­ matic transmission with overdrive. For further development step, studied was to apply the lock-up clutch from lower vehicle speed for deriving the fuel economy potential of the four-speed automatic transmission with overdrive. The lock-up clutch operation, how­ ever, gives an ad