Automatic power transmission control system

Claim 1

An electronic control system for an automatic power transmission for a motor vehicle driven by an engine having a carburetor throttle valve controlled by an accelerator pedal comprising, in combination; gear ratio changing means, first sensing means for generating first voltage proportional in magnitude to vehicle speed; second sensing means for generating second voltage of opposite polarity to the first voltage and proportional in magnitude to effective open area of said carburetor throttle valve; circuit means connected with said gear ratio changing means for effecting the operation thereof including inputs connected to said first and second sensing means to receive said first and second voltages therefrom, and further including means for comparing the first and second voltages and producing a first set of shifting signals to cause said gear ratio changing means to effect shift into different gear ratios in accordance with a predetermined shift schedule in dependence on said first and second voltages; and control means including a constant voltage power supply means connected to said inputs of said circuit means to supply a third voltage of opposite polarity to said first voltage thereto and switching means connected between said constant voltage power supply means and said inputs of said circuit means, said switching means cooperating with said accelerator pedal for transmitting said third voltage to said inputs of said circuit means when said carburetor throttle valve is closed, and said comparing means producing a second set of shifting signals to cause said gear ratio changing means to effect shift into different gear ratios in accordance with another predetermined shift schedule in dependence on said first, second and third voltages, whereby downshift will take place at a higher vehicle speed level than normal when said throttle valve is closed.