Patent ID: 9709165
Date: 2017-07-18
CPC Classifications: F16H

Claim:
1. An apparatus for controlling an automatic transmission that is connected to a prime mover mounted on a vehicle and changes a speed of rotation of the prime mover to transmit the speed of rotation to driven wheels, the apparatus comprising: a torque converter interposed between the prime mover and the automatic transmission and equipped with a lock-up clutch; a hydraulic supply circuit that supplies hydraulic pressure to the lock-up clutch; the automatic transmission; clutches provided on the automatic transmission and connecting the prime mover and the driven wheels; a controller that controls operation of the lock-up clutch and the automatic transmission through the hydraulic supply circuit; and a rotational speed ratio calculator that calculates a ratio of an input rotational speed of the automatic transmission relative to an output rotational speed of the prime mover; wherein the controller forms a lock-up clutch engaging circuit through the hydraulic supply circuit when the automatic transmission is gear-shifted to a predetermined gear at deceleration of the vehicle and it is determined that predetermined operating conditions of the vehicle are satisfied, determines whether an engage-position sticking malfunction of the lock-up clutch has occurred based on the calculated ratio when the lock-up clutch engaging circuit has been formed, and disengages the clutches when it is determined that the engage-position sticking malfunction of the lock-up clutch has occurred.