Hydraulic pressure control system for belt-type continuously variable transmission

摘要

A hydraulic pressure control system for a belt-type continuously variable transmission including a speed ratio control mechanism composed of two variable pulleys each having a belt groove with a width that can be changed according to a hydraulic pressure, and a belt member passed over the variable pulleys in engagement with the belt grooves of the variable pulleys so as to transmit a power therebetween. The hydraulic pressure control system includes a line pressure control means for controlling a line pressure supplied to one of the variable pulleys; and a speed ratio control pressure control means for controlling the line pressure as a speed ratio change pressure supplied to the other of the variable pulley according to a desired speed ratio. The line pressure control means includes a detecting means for detecting whether or not an actual speed ratio has reached the desired speed ratio, and operable to lower the line pressure if the first detecting means detects that the actual speed ratio has reached the desired speed ratio.