Patent ID: 7287631

Claim:
A lock-up clutch control device which controls a lock-up clutch provided in a torque converter which is mounted between an engine and a transmission provided in a vehicle, the lock-up clutch control device switching between a converter state and a lock-up state of the torque converter by controlling a differential pressure supplied to the lock-up clutch, the lock-up clutch control device comprising: a sensor which detects a vehicle speed; a differential pressure generator which generates the differential pressure supplied to the lock-up clutch in response to an operational differential pressure command value; and a controller programmed to: calculate a first differential pressure command value which decreases at a predetermined rate of change, after the detected vehicle speed becomes a first predetermined vehicle speed; calculate a second differential pressure command value which is smaller than the first differential pressure command value; set the operational differential pressure command value for the differential pressure generator to the second differential pressure command value, before the detected vehicle speed becomes a second predetermined vehicle speed which is lower than the first predetermined vehicle speed; and set the operational differential pressure command value for the differential pressure generator to a value at which the lock-up clutch is immediately released, when the detected vehicle speed becomes the second predetermined vehicle speed.