Patent ID: 7651422

Claim:
A shift control system for a V-belt type continuously variable transmission of a vehicle in which a V-belt is wound between a primary pulley of an input side connected to an engine and a secondary pulley of an output side, a primary pulley pressure acting on the primary pulley and a secondary pulley pressure acting on the secondary pulley are generated respectively with a line pressure as an original pressure, and a shift actuator operable to an operating position corresponding to a target gear ratio, wherein a differential pressure is generated between the primary pulley pressure and the secondary pulley pressure to change widths of V-shaped grooves of the primary pulley and the secondary pulley so that an actual gear ratio that is obtained from speed ratio of the primary pulley and the secondary pulley becomes equal to the target gear ratio, the shift control system comprising: a transmission controller configured to control the shift actuator and configured to detect a downshift of the continuously variable transmission; a speed detecting device configured to detect a speed of the vehicle; and an idle state detecting device configured to detect an idle state of the engine, wherein the transmission controller is configured to limit an operating speed of the shift actuator to prevent slippage of the V-belt when: the speed detected by the speed detecting device is less than a first predetermined speed, the transmission controller detects the downshift, and the idle state detecting device does not detect the idle state of the engine.