Continuously variable transmission with control of switching between a high mode and a low mode

摘要

A continuously variable transmission system includes a belt type continuously variable transmission unit (CVT) wherein the direction of torque transmission is switched by torque circulation between a low mode and a high mode accompanied by a change in the axial forces on the pulleys of the CVT. In the Low mode of the D range, a comparatively high hydraulic pressure from a regulator valve is supplied to a Low clutch hydraulic servo via a low-high shifting valve and to a secondary hydraulic servo. In addition, a comparatively low hydraulic pressure from a ratio control valve is supplied to a primary hydraulic servo. These oil pressure feeds are reversed by the switching of the low-high shifting valve.