Patent ID: 7892141

Claim:
A speed ratio change control device for a continuously variable transmission comprising: a continuously variable speed ratio change mechanism in which a belt is wrapped around a primary pulley and a secondary pulley and a speed ratio is varied by controlling a pressure supplied to each pulley to displace a movable sheave of each pulley; a speed ratio change control valve which controls a primary pressure that serves as a pressure supplied to the primary pulley, using a line pressure supplied by a hydraulic pump as a source pressure; and a link mechanism which moves the speed ratio change control valve to a position in which the primary pressure varies when a speed ratio change actuator moves to a position corresponding to a target speed ratio of the continuously variable speed ratio change mechanism, and returns the speed ratio change control valve to a position in which the primary pressure is maintained by varying the primary pressure such that the movable sheave of the primary pulley displaces, the device comprising a controller which: calculates a maximum thrust that can be generated by the primary pulley on the basis of an upper limit value of the line pressure; calculates an upper limit value of a shift speed of the continuously variable speed ratio change mechanism on the basis of the maximum thrust that can be generated by the primary pulley; and sets the target speed ratio of the continuously variable speed ratio change mechanism on the basis of the upper limit value of the shift speed.