Patent ID: 7282009

Claim:
A lock-up clutch control device which controls a lock-up clutch installed in a torque converter interposed between an engine and a transmission used with a vehicle, comprising: a differential pressure generating device which engages or disengages the lock-up clutch by adjusting a differential pressure supplied to the lock-up clutch, a sensor which detects a vehicle speed, and a controller programmed to: determine whether or not the vehicle speed is equal to or larger than a first threshold value (V 1 ) corresponding to a lock-up ON vehicle speed; command the differential pressure generating device to engage the lock-up clutch, when the vehicle speed is equal to or larger than the first threshold value (V 1 ); determine whether or not the vehicle speed has reached a second threshold value (V 2 ) larger than the first threshold value (V 1 ); set a lock-up OFF threshold value (V 3 /V 4 ) which depends on whether the vehicle speed has reached the second threshold value (V 2 ); and command the differential pressure generating device to disengage the lock-up clutch, when the vehicle speed is equal to or less than the lock-up OFF threshold value.