Control system for a continuously variable transmission for vehicles

A control system for a continuously variable transmission for vehicles having a V-belt type continuousy variable transmission and a planetary gear set for changing forward and reverse drives, said control system comprising

• an electric control circuit which comprises means for receiving input signals, said input signals comprising shift lever setting position, revolution speed of input pulley, vehicle speed, and carburetor throttle opening, detection and processing circuits for converting said input signals into output voltage signals, an output interface, and a solenoid output driver for converting output of said output interface into operating output for solenoids,
• a shift control mechanism which comprises a manual valve geared with a shift lever, a throttle valve supplying throttle pressure depending on a throttle opening, a regulator valve for receiving throttle pressure and regulating hydraulic fluid pressure supplied from an oil reservoir, which provides regulated pressure as line pressure, a torque ratio valve means for exhausting feedback fluid pressure generated by the throttle valve when a displacement amount of a movable flange of an outupt pulley of the V-belt type continuously variable transmission is less than a first selecting value, a torque ratio control device controlled by said electric control circuit and regulating hydraulic pressure supplied to a hydraulic servo system of an input pulley of the V-belt type continuously variable transmission and changing the torque ratio between the input and output shafts of the V-belt type continuously variable transmission, a solenoid valve controlling a hydraulic servo system associated with friction engaging elements connected to the planetary gear set for changing forward and reverse drives, and a valve means controlling hydraulic pressure to said hydraulic servo system by output signals from said electric control circuit, wherein a rise of hydraulic fluid pressure to said hydraulic servo system associated with friction engaging elements is controlled in its working upon said solenoid valve and delayed when forward and reverse drives are changed by said shift lever.

A control system for a continuously variable transmission for vehicles having a V-belt type continuously variable transmission and a planetary gear set for changing forward and reverse drives, said control system comprising

• an electric control circuit which comprises means for receiving input signals, said input signals comprising shift lever setting positions, revolution speed of input pulley, vehicle speed, and carburetor throttle opening, detection and processing circuits for converting said input signals into output voltage signals, an output interface, and a solenoid output driver for converting output of said output interface into operating output for solenoids,
• a shift control mechanism which comprises a manual valve geared with a shift lever, a detent valve and throttle valve supplying respectively the detent and throttle pressure dpending on a throttle opening, a regulator valve receiving said detent and throttle pressure and regulating hydraulic pressure supplied from an oil reservoir and providing the regulated pressure as line pressure, a torque ratio valve means for exhausting feedback fluid pressure generated by the throttle valve when a displacement amount of a movable flange of an output pulley of the V-belt type continuously variable transmission is less than a first selecting value, and supplying the line pressure to the detent valve when said displacement amount is less than a second selecting value, a torque ratio control device controlled by said electric control circuit and regulating a hydraulic pressure supplied to a hydraulic servo system of an input pulley of the V-belt type continuously variable transmission and changing the torque ratio between an input and output shafts of the V-belt type continuously variable transmission, a solenoid valve controlling a hydraulic servo system associated with friction engaging elements connected to the planetary gear set for changing forward and reverse drives, and a valve means controlling hydraulic pressure to said hydraulic servo system, by output signals from said electric control circuit, wherein a rise of hydraulic fluid pressure to said hydraulic servo system associated with friction engaging elements is controlled in its working upon said solenoid valve and delayed when forward and reverse drives are changed by said shift lever.