Accumulator control device for hydraulic control device for automatic transmission for vehicle with engine load dependent backup control.

摘要

A hydraulic control device for generating a hydraulic pressure for a back pressure chamber of an accumulator (82) in a speed stage shifting device of an automatic transmission for a vehicle such as an automobile is adapted to generate a hydraulic pressure to be supplied to the back pressure chamber (88) of the accumulator by modulating the so-called line hydraulic pressure according to a balance between the modulated pressure itself and the line hydraulic pressure or more desirably an engine power simulation pressure modulated from the line hydraulic pressure to be lower than the line hydraulic pressure in low engine output operation under an influence of a signal hydraulic pressure controlled by an electromagnetic valve (130), wherein the accumulator control valve (110) has a spool element (113) having a first pressure receiving area exposed to the modulated hydraulic pressure to generate a positive feedback effect of decreasing the modulated hydraulic pressure along with increase thereof and a second pressure receiving area exposed to the line hydraulic pressure or the engine power simulation pressure to generate an effect of increasing the modulated pressure, the first pressure receiving area having an effective pressure responsive sectional area substantially equal in the magnitude and opposite in the orientation to that of the second pressure receiving area.