Hydraulic control device for automatic transmission

摘要

PCT No. PCT/JP87/00456 Sec. 371 Date Mar. 1, 1988 Sec. 102(e) Date Mar. 1, 1988 PCT Filed Jun. 30, 1987 PCT Pub. No. WO88/00306 PCT Pub. Date Jan. 14, 1988.A hydraulic control device of an automatic transmission for a vehicle utilizes a shift valve for shifting at a high speed stage to prevent creeping and provide a hill-stop mechanism. The shift valve for shifting at the high speed stage has a port open to a forward clutch hydraulic servo, a port communicating with a brake hydraulic servo, and a port receiving modulator pressure from a modulator valve. A solenoid valve controlling the shift valve is in turn controlled by signals issued when the vehicle stops and begins to travel, and the modulator valve is controlled by a linear solenoid throttle valve. The modulator pressure is applied to the forward clutch hydraulic servo, and line pressure is applied to the brake hydraulic servo when the vehicle stops. Line pressure is applied to the forward clutch hydraulic servo and line pressure to the brake hydraulic servo is drained when the vehicle runs.