| 摘要 |
PURPOSE: An oil pressure control system for a continuously variable transmission of a vehicle is provided to change speed precisely by controlling a fluid with the oil pressure to be supplied from a primary pulley. CONSTITUTION: An oil pressure control system for a continuously variable transmission of a vehicle comprises a primary line pressure adjusting valve(4), a secondary line pressure adjusting valve(6), a secondary pulley(8), a first solenoid valve(S1), a second solenoid valve(S2), a third solenoid valve(S3), a fourth solenoid valve(S4), a pressure control valve(18), a transmission gear ratio control valve(14), a forward friction member(C), and a reverse friction member(B). The primary line pressure adjusting valve adjusts the oil pressure from an oil pump(2). The oil pressure is supplied to the secondary line pressure adjusting valve and the secondary pulley. The adjusted oil pressure of the secondary line pressure adjusting valve is supplied to the first and the second solenoid valves and the pressure control valve. The first and the second solenoid valves control a reducing valve(10), a damper clutch control valve(12), primary line pressure adjusting valve and the transmission gear ratio control valve. The transmission gear ratio control valve controls the fluid to be supplied to the primary pulley according to a duty of the second solenoid valve. The decompressed fluid by the reducing valve is supplied to the third and the fourth solenoid valve. The third solenoid valve controls the pressure control valve. The fourth solenoid valve controls the damper clutch control valve. The oil pressure from the pressure control valve is supplied to the forward and the reverse friction members according to a switching of a passage of a manual valve(20). The oil pressure from the primary pulley also controls the transmission gear ratio control valve. Thereby, fuel efficiency and driving feeling are improved and cost of production is reduced.
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