HYDRAULIC CONTROL SYSTEM FOR AUTOMATIC TRANSMISSION

摘要

A hydraulic control system comprises a distributor valve including a valve body formed with a first port communicating with a pressure regulator and a second inlet port. The valve body is also formed with a plurality of outlet ports communicating with corresponding frictional elements, respectively. A solenoid operated relief valve is fluidly disposed between the pressure regulator and the second inlet port of the valve body. The distributor valve includes a rotary valve element operatively connected with a stepping motor. The rotary valve element is rotatably disposed within a bore of the valve body and has a plurality of angular positions for connecting the outlet ports to the first inlet port, second inlet port and drainage, selectively. The solenoid of the relief valve is of the proportioning type and is controlled by a control unit. The stepping motor is also controlled by the control unit.