Hydraulic control apparatus for vehicle continuously variable transmission, having means for limiting increase in input shaft speed after the speed rises to predetermined level with vehicle speed

摘要

A hydraulic control apparatus for controlling a speed ratio of a vehicle continuously variable transmission (14), which includes a device (82) for producing an input shaft speed pressure varying with the input shaft speed of the transmission, a device (114) for producing an engine output pressure varying with the currently required output of the vehicle engine, a device (86, 388, 386) for producing a vehicle speed pressure varying with the vehicle speed, such that a rate of increase in the vehicle speed pressure is limited after the vehicle speed pressure reaches a predetermined upper limit which varies with the engine output pressure, and a shift control valve device (330, 460, 490) including a valve spool (350, 472, 492) operated to control the hydraulic actuator for changing the speed ratio so as to shift-down the transmission, in relation to an increase in the engine output pressure and an increase in the vehicle speed pressure, and changing the speed ratio so as to shift-up the transmission, in relation to an increase in the input shaft speed pressure.