| 摘要 |
PURPOSE: A hydraulic control system for a continuously variable transmission of a vehicle is provided to protect a frictional member, and to prevent shift shock by preventing hydraulic pressure from being supplied to the frictional member suddenly in converting into the reverse range during traveling forward. CONSTITUTION: A hydraulic control system of a continuously variable transmission in a vehicle is composed of a pressure control unit having a primary line pressure regulating valve(4), a first solenoid valve, a second pressure regulating valve(6) and a solenoid supply valve(8); a transmission control unit having a transmission gear ratio control valve(10), and a second solenoid valve(S2); a forward and backward movement control unit having a pressure control valve(14), a third solenoid valve(S3), a manual valve(16), and first and second frictional members(C,B); a torque converter control unit having a torque converter feed valve receiving hydraulic pressure from the pressure control unit, and a lockup clutch valve and a fourth solenoid valve(S4); and a safety unit controlled by operational pressure in the backward pressure pipe connecting the manual valve to the second frictional members. The frictional member is protected, and shift shock is reduced with preventing hydraulic pressure from being supplied suddenly in shifting to the reverse range suddenly.
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