Hydraulisches Steuersystem für automatische Getriebe.

摘要

An automatic transmission hydraulic controller having a multiplicity of hydraulic servos for respectively controlling a multiplicity of frictional engagement elements. A hydraulic pressure to be supplied to the hydraulic servos is applied to accumulator chambers of a multiplicity of accumulators (21-24). A line pressure to be supplied to the hydraulic servos is produced by a primary regulator valve (3) and an engine output pressure control valve (5) is controlled by an electrical signal from a control section (8) to produce a hydraulic pressure corresponding to the engine output. Each of at least two particular ones of the multiplicity of accumulators has a back pressure chamber (71-74) formed at the rear of a piston. The pressure receiving area of this back pressure chamber and that of the corresponding accumulator chamber (91-94) are substantially equal to each other. Only one of the frictional engagement elements operated by the hydraulic servos communicating with the particular accumulators is changed over from a released state to an engaged state while the other frictional engagement elements are not changed over from a released state to an engaged state, when the transmission is shifted to a predetermined speed. There is no substantial influence of a change in the line pressure upon the operating state of the other frictional engagement elements.