Lock-up control system for automatic transmission

摘要

A lock-up control system for an automatic transmission including a torque converter (10) and a lock-up clutch (10a). The lock-up control system comprises an accelerator pedal depression amount sensor (4) for detecting a depression amount of an accelerator pedal, and a controller. The controller includes an accelerator pedal movement speed calculating section for calculating a movement speed of the accelerator pedal. The controller includes a lock-up control section adapted to disengage the lock-up clutch in a condition in which a driving point of the vehicle is within a lock-up condition releasing region in a set lock-up schedule, and to engage the lock-up clutch in a condition in which the driving point is within a lock-up condition applying region. The lock-up control section includes a first lock-up releasing control section adapted to gradually disengage the lock-up clutch from an engaging state and put the lock-up clutch into a disengaging state when the accelerator pedal movement speed is not lower than a set speed and an initial accelerator pedal depression amount in the accelerator pedal depression amount is not smaller than a set accelerator pedal depression amount to establish a driving condition of the vehicle under the engaging state of the lock-up clutch.