Patent ID: 8202186

Claim:
A hydraulic control apparatus for an automatic transmission that includes a planetary gear set and a plurality of friction elements and establishes a plurality of speeds by changeover of the plurality of friction elements between engagement and release, the plurality of friction elements including a first friction element that is brought into a release state upon first shift, a second friction element that is in a release state upon the first shift but is brought into an engagement state upon second shift, and a third friction element that is brought into a release state upon the second shift, the hydraulic control apparatus comprising: a pressure regulator valve regulating a hydraulic fluid pressure that is supplied to the second friction element; a selector valve that is switchable between a first position where fluid communication between the pressure regulator valve and the second friction element is allowed, and a second position where the fluid communication between the pressure regulator valve and the second friction element is blocked; a switch means for switching the selector valve to the second position when the first friction element is in the engagement state, and switching the selector valve to the first position when the first friction element is in the release state; and a sequential shift control means for performing sequential shift control in a case where it is necessary to execute the second shift during execution of the first shift, the sequential shift control including: starting reduction of hydraulic fluid pressure in the third friction element when a parameter that varies in accordance with a degree of progress of the first shift has reached a predetermined value, and performing piston stroke control that includes outputting a high hydraulic pressure command as a hydraulic fluid pressure to the second friction element when the selector valve is switched from the second position to the first position, and subsequent to completion of outputting of the high hydraulic pressure command, outputting a low hydraulic pressure command that is lower than the high hydraulic pressure command.