| 摘要 |
PURPOSE: A hydraulic control system of an automatic transmission for a vehicle is provided to improve transmission responsiveness and shift feeling and to enlarge a transmission control range by independently controlling respective friction elements and controlling the release hydraulic pressure of a kick-down servo. CONSTITUTION: A hydraulic control system of an automatic transmission for a vehicle comprises a pressure control unit to control the hydraulic pressure generated by an oil pump(4), a damper clutch control unit to operate a damper clutch of a torque converter(2), a transmission control unit to form a transmission mode, a hydraulic control unit to smoothly form a transmission mode by controlling shift feeling and responsiveness, and a hydraulic distribution unit to distribute hydraulic pressure to first, second, third and fourth friction elements(C1,C2,C3,C4) acting as input and reaction force elements. The transmission control unit consists of a manual valve(26) for changing a path depending on the manipulation of a selector lever. The hydraulic control unit consists of first, second, third and fourth pressure control valves(16,18,20,22) for independently controlling first, second, third and fourth valves and solenoid valves(S1,S2,S3,S4). The hydraulic distribution unit consists of a control switch valve(28) to supply hydraulic pressure to an operation chamber of the second friction element and to the pressure control unit, a low control valve(30) to supply hydraulic pressure to the third and fourth friction elements, and a fail safe valve(32) to hold a third speed when breakage occurs.
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