Speed change controller for infinite speed ratio transmission

A speed change controller for an infinite speed ratio transmission for a vehicle, the infinite speed ratio transmission comprising an input shaft, a continuously variable transmission which comprises a first output shaft and transmits a rotation of the input shaft at an arbitrary speed ratio to the first output shaft, a fixed speed ratio transmission which comprises a second output shaft and transmits the rotation of the input shaft at a fixed speed ratio to the second output shaft, a planetary gear set comprising a first rotation element joined to the first output shaft, a second rotation element joined to the second output shaft, and a third rotation element which varies a rotation direction and a rotation speed according to a difference between a rotation speed of the first rotation element and a rotation speed of the second rotation element, the vehicle running according to the rotation of the third rotation element, and a selector lever which selects an operating range of the infinite speed ratio transmission, the operating range comprising a forward motion range and a reverse motion range, the controller comprising:

• an actuator which varies an amount of torque transmitted between the input shaft and the first output shaft;
• a sensor which detects the operating range selected by the selector lever;
• and
• a controller which controls the actuator according to the operating range so that a rotation torque in an opposite direction to a vehicle travel direction represented by the operating range is not transmitted between the input shaft and the first output shaft.