PURPOSE: To prevent the lowering of torque and the generation of any torque shock by outputting a lock-up control signal for lowering clutch engaging force in case that the natural frequency changing signal of an intake system is input in a lock-up state.
CONSTITUTION: A control unit 17 conducts the opening/closing control for an opening/closing valve 14 via an actuator 16 according to signals from respective sensor to change the natural frequency of an intake system. In case that a present operating state is in a predetermined engine speed area, a lock-up control releasing signal is output to release a lock-up control. Accompanied with the lock-up releasing motion, a torque ratio is changed to a rising side as compared with the case of continuity of the lock-up control. Accordingly, the torque of the output side of a transmission is increased as compared with the case that the lock up is not released and also generally smooth characteristics having a small quantity of torque change can be obtained.
KAMIMURA HIDEYUKI
NOSE HIROSHI
