Hydraulisches Steuerungssystem eines stufenlosen Riemengetriebes mit Riemendruckoptimierung.

摘要

A hydraulic control apparatus for a vehicle continuously variable transmission including a pressure regulating valve (102) having a valve spool (110) which operates depending upon a determined current speed ratio of the transmission and a currently detected required output of the vehicle engine, to generate a controlled belt tensioning pressure (P l 2) for controlling the tension of a transmission belt (44) at a required minimum level. The apparatus further includes a device (346, 500) responsive to an electric signal, for generating a pilot pressure (Psol4, PsolL) to be applied to the valve, and an electronic control device (460) for calculating a basic output pressure of the valve, based on the current speed ratio and the currently required output, according to a stored relationship among these two parameters and the basic output Pressure, to determine the electric signal, based on the basic output pressure and an optimum value of the belt tensioning pressure, for coincidence of the belt tensioning pressure with the optimum value.