Patent ID: 8548704

Claim:
A lock-up clutch control device for an automatic transmission comprising: a lock-up clutch in a torque converter between an engine of a vehicle and an automatic transmission and configured to engage an engine side and an automatic transmission side of the torque converter; a lock-up clutch control unit which controls a slip amount of the lock-up clutch to a target slip amount when the lock-up clutch engages the engine side and the automatic transmission side, wherein the slip amount comprises a rotation speed difference between the engine side and the automatic transmission side; a required load variation rate calculation unit which calculates a variation rate of a required load of the engine, wherein the variation rate comprises one of a variation in a throttle opening per unit time and a variation in an accelerator pedal operation amount; a target slip amount increasing unit which increases the target slip amount at a predetermined increase rate to an upper limit target slip amount when the variation rate is equal to or greater than a predetermined variation rate; and a target slip amount reducing unit which reduces the target slip amount, after the target slip amount is increased to the upper limit target slip amount, from the upper limit target slip amount at a predetermined reduction rate to a base target slip amount, wherein the predetermined reduction rate is set to decrease as at least one of (i) a vehicle speed, when the variation rate reaches or exceeds the predetermined variation rate, increases and (ii) a speed ratio, when the variation rate reaches or exceeds the predetermined variation rate, decreases.