Patent ID: 6846266
Filing Date: 2005-01-25
Classification: F16H,Y10T

Abstract:
1. 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 power therebetween; wherein said hydraulic pressure control system comprises 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 pulleys according to a desired speed ratio; said line pressure control means comprising a first detecting means for detecting whether or not an actual speed ratio has reached the desired speed ratio, and operable to lower the line pressure with a predetermined drop marain, if the first detecting means detects that the actual speed ratio has reached the desired speed ratio, wherein said detection of whether or not an actual speed ratio has reached the desired speed ratio and said lowering of the line pressure are performed as a routine, said routine being repeated until said actual speed ratio becomes short of said desired speed ratio.