Control device for continuously variable transmission

A control device for a continuously variable transmission comprising:

• a continuously variable transmission mechanism transmitting power with a belt wound around a primary pulley and a secondary pulley;
• a torque convertor provided between an engine and the continuously variable transmission mechanism, the torque convertor having a pump impeller rotating integrally with the engine, a turbine runner rotating integrally with an input shaft of the continuously variable transmission mechanism and a lock-up clutch connecting the pump impeller and the turbine runner;
• and
• a control unit controlling the lock-up clutch to a predetermined engagement state and controlling the continuously variable transmission mechanism to a predetermined transmission ratio, according to a travelling condition, and
• the control unit being configured to, when shifting the lock-up clutch from a disengagement state to an engagement state, control a transmission ratio of the continuously variable transmission mechanism so that when a rotation speed difference between an engine rotation speed and a turbine rotation speed that is a rotation speed of the turbine runner is a predetermined rotation speed difference or less, the turbine rotation speed approaches the engine rotation speed more closely than a turbine rotation speed in a case where control of a transmission ratio of the continuously variable transmission mechanism, which is set according to the travelling condition during a shift of the lock-up clutch, is continued.