Title: Development of a four-speed automatic transmission with overdrive

Authors: A. Numazawa, S. Kubot, Y. Shindo, S. Moroto

Addresses: Toyota Motor Co. Ltd., Japan. ' Toyota Motor Co. Ltd. Japan. ' Toyota Motor Co. Ltd. Japan. ' Aisin Warner Ltd., Anjo, Japan

Abstract: A new four-speed automatic transmission with overdrive has been developed and put into production for the purpose of improvement of fuel economy and the reduction of engine noise. The transmission has the following characteristics: gear train arrangement with overdrive unit; lower overdrive gear ratio; shift feel controls for clutch-to-clutch shifting; optimum shift points on fuel economy, driveability and exhaust emissions; lockout system of overdrive gear. For optimum gear ratios, shift points, and smooth shift feel controls, computer simulations were used to provide design direction. This paper describes the design features and the confirmation testings of the transmission, and also refers to effects on fuel economy and noise reduction of the transmission in the vehicle.

Keywords: transmission design; 4-speed automatic transmission; gear train; powertrain; powertrain efficiency; overdrive gear; torque convertor; clutch; hydraulic controls; control system; planetary gear set; final drive; gear ratio; shift points; shift feel controls; shift positions; shift performance; lockout system; interchangeability; durability tests; driveability; reliability; safe driving; weight reduction; emission control; fuel economy; noise reduction; optimisation.

DOI: 10.1504/IJVD.1980.061359

International Journal of Vehicle Design, 1980 Vol.1 No.2, pp.151 - 164

Available online: 25 May 2014 *

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