Transmission control apparatus, having means for determining the completion of a shifting action of a coupling device with pressure adjusting accumulator

Claim 1

A hydraulic control apparatus for controlling a hydraulically operated automatic transmission of a motor vehicle having a frictionally coupling device, an accumulator which communicates with the frictionally coupling device, and a rotary member whose rotating speed changes due to a shifting action of the coupling device, said apparatus including an electronic control device for controlling a back pressure of said accumulator during a shifting action of the frictionally coupling device for minimizing a shifting shock of the transmission, said apparatus comprising: first determining means for effecting a first determination that the transmission should be shifted with said shifting action of said frictionally coupling device; means for generating a shifting command to initiate said shifting action after said first determination; speed detecting means for detecting a rotating speed of said rotary member; second determining means for effecting a second determination, based on the rotating speed detected by said speed detecting means, that said shifting action of said frictionally coupling device is completed; time measuring means for measuring a time which has passed after one of a moment when said first determination is effected and a moment of generation of said shifting command; and third determining means for effecting a third determination that said shifting action is completed, irrespective of the detected rotating speed of said rotary member, when the time measured by said time measuring means exceeds a predetermined time interval.