Kick down control system

Claim 1

A kick down control system for an automatic transmission mounted on a motor vehicle having an internal combustion engine, and throttle valve provided on the engine for controlling a mixture of fuel and air induced in the engine, the system comprising a throttle position sensor for repeatedly detecting opening degree of the throttle valve and for producing an opening degree signal representing the opening degree, memory means for storing a value as a maximum value and for producing a maximum value signal representing the maximum value, maximum value learning means responsive to the opening degree signal for rewriting the stored maximum value in the memory means with a new value larger than the stored value when the opening degree is larger than the stored value, kick down solenoid means for down-shifting the transmission ratio of the automatic transmission to increase acceleration efficiency, and kick down deciding means responsive to the opening degree signal and the maximum value signal for determining a kick down condition when the opening degree represented by the opening degree signal at least equals a predetermined value relative to the maximum value to accurately actuate the kick down solenoid means, so as to provide the down-shifting of the automatic transmission without receiving influences of variation in accuracy of the throttle position sensor.