Lockup control device of a fluid transmission

Abstract

According to the lockup device of a fluid transmission under the present invention, at the decelerating running when the change rate of engine load exceeds a set value, a lockup control pattern is changed so that the area where the lockup device is controlled to perfect friction or to the specified friction force. By this change, at the decelerating running large engine brake force can be worked and a good feeling of deceleration can be given to a driver. In the case where fuel supply to the engine is suspended at the decelerating running of the engine, transmission of large engine brake force as mentioned above results in comparatively longer time of maintaining high engine speed and longer time of fuel supply cutting off, with consequent saving of fuel consumption. Moreover, by changing the target slip quantity to the increasing side at the accelerating running, torque increasing action at the accelerating running is displayed effectively and accelerability can be improved. At the normal running, lowering of specific fuel consumption due to slip of the torque converter can be checked by setting a target slip quantity small. Thus, coexistence of improvement of accelerability and improvement of specific fuel consumption can be planned.