Electro-hydraulic control system for a motor-vehicle transmission

摘要

The clcctro-hydraulic control system comprises a gear shift control device (10) and a hydraulic control circuit (12). The gear shift control device (10) includes four shift forks (14, 16, 18, 20), operatively associated each to a respective engagement sleeve (112, 114, 116, 118) of the transmission to cause this latter to move between first and second engagement positions, and an operating unit (22) comprising four double-acting hydraulic actuators (24, 26, 28, 30) arranged to control each the displacement of a respective shift fork (14, 16, 18, 20). The hydraulic control circuit (12) comprises a supply unit (50), a distributor valve (52) adapted to select every time one of the four hydraulic actuators (24, 26, 28, 30) and two solenoid valves (54, 56) adapted to control the hydraulic actuator selected by the distributor valve (52). The distributor valve (52) has four operating positions, each of which corresponds to the selection of a respective hydraulic actuator (24, 26, 28, 30). The two solenoid valves (54, 56) are arranged to be connected each to a respective pressure chamber (42, 44) of the hydraulic actuator (24, 26, 28, 30) selected by the distributor valve (52).