Electronic system for controlling an automatic transmission in response

Abstract

An electronic system for controlling an automatic transmission having an hydraulic control circuit comprises a large scale integrated semiconductor logic unit, a semiconductor read-only memory, a semiconductor read-write memory and input and output ports as required. The read-only memory fixedly stores standard data indicating the upper and the lower limit value of vehicle speed which correspond to the individual throttle openings of the engine for each shift lever position of a vehicle on which the automatic transmission, the hydraulic control circuit and the electronic system are mounted; slope detecting reference data indicating the vehicle speeds on slopes which correspond to the throttle opening in each shift lever position; slope detecting program data which is utilized to detect a slope as a result of the comparison between the reference data on one hand and the current shift lever position, the current throttle opening and the current vehicle speed; additional program data which is utilized to modify at least part of the standard data in response to a slope detected to produce shift reference data which corresponds to the slope; shift determining program data which determines a speed range to be established in response to the comparison of the current speed range, the current throttle opening and the current vehicle speed against the shift reference data; and shift controlling program data responsive to the determined speed range to control the energization of the solenoid valves.