Patent ID: 7033297

Claim:
A shift control apparatus for controlling shifting actions of an automatic transmission including a hydraulically operated frictional coupling device having a hydraulic cylinder which is supplied with a working fluid when the frictional coupling device is engaged, said shift control apparatus comprising: a transient-hydraulic-pressure control device operable to control a transient value of a hydraulic pressure in the hydraulic cylinder of the frictional coupling device according to an electric signal, upon releasing of the frictional coupling device; an accumulator having a back-pressure chamber a back pressure of which is controllable, and an accumulator chamber connected to the hydraulic cylinder of the frictional coupling device and operable to control a transient value of the hydraulic pressure in the hydraulic cylinder, when the frictional coupling device is engaged with the working fluid being supplied to the hydraulic cylinder; and a back-pressure increasing portion operable to increase the back pressure in the back-pressure chamber of the accumulator for rapidly discharging the working fluid from the accumulator chamber, when the hydraulically operated frictional coupling device is released to effect one of said shifting actions of the automatic transmission.