Electro-hydraulic control apparatus for a motor-vehicle transmission with at least five forward gears and one reverse gear

摘要

The control system comprises, in its version intended for a double-clutch transmission with six o seven forward gears and one reverse gear, a first shift fork (12) for engaging the first gear (I) or the third gear (III), respectively, a second shift fork (16) for engaging the reverse gear (R) or the fifth gear (IV), respectively, a first hydraulic actuator (22) arranged to control the displacement of the first shift fork (12), a second hydraulic actuator (26) arranged to control the displacement of the second shift fork (16), a selection slide valve (52) which can be moved into a first operating position in which the first hydraulic actuator (22) is selected and a second operating position in which the second hydraulic actuator (26) is selected, a pilot solenoid valve (62) for controlling the displacement of the slide valve (52) between the first and second operating positions, and first and second gear shift solenoid valves (56, 54) for controlling the supply of fluid to the hydraulic actuator (22, 26) each time selected by the slide valve (52) or the connection of said actuator with a tank. The slide valve (52) is configured in such a manner that the first and second operating positions are end-of-travel positions, wherein the first operating position is a rest position, in which the pilot solenoid valve (62) does not generate any hydraulic pilot control signal and the slide valve (52) is held by resilient means (90) against a first mechanical stop, and wherein the second operating position is a maximum-control position, in which the pilot solenoid valve (62) generates a hydraulic control signal such that the slide valve (52) is brought against a second mechanical stop opposite to the first one.