Steuereinrichtung für hydraulisch betätbares Fahrzeuggetriebe

摘要

Apparatus for controlling at least three shift valves operating four hydraulic clutches in a hydraulically operated vehicular transmission. The shift valves are serially located and alternately switched to establish successive first through fourth-speed transmission trains. Each shift valve is urged to one position by a respective spring and has an oil chamber at its opposite for oil pressure to urge it to its other position. Additionally, the first shift valve has another oil chamber at its spring end. A first electromagnetic open-air pressure dump valve is connected to a first oil passage through which oil is inputted to the first oil chamber of the first shift valves and the oil chamber of the second shift valve. A second electromagnetic open-air pressure dump valve is connected to a second oil passage through which oil is inputted to the other oil chamber of the first shift valve and the oil chamber of the third shift valve. An electronic microcomputer controls the first and second electromagnetic valves to operate the shift valves by permitting or dumping oil pressure to the oil chambers.