Control device for lockup clutch

摘要

When the change rate d theta TH of an accelerator opening degree exceeds a reference value at a time point t0 as a result of the depression of an accelerator pedal, a predetermined target speed ratio eECONOMY taking preference of a specific fuel consumption up to such time is switched to a during-acceleration target speed ratio ePOWER taking preference of an accelerating performance. For a period from the time point t0 to a time point t2 until the actual speed ratio e reaches a minimum value, a feed-forward control is carried out in order to equalize the actual speed ratio e to the during-acceleration target speed ratio ePOWER. For a period from the time point t2 to a time point t3, a return-time target speed ratio eTRN gradually increased toward the predetermined target speed ratio eECONOMY is set, and a feed-back control is carried out in order to equalize the actual speed ratio e to the return-time target speed ratio eTRN. Thus, it is possible to set the speed ratio of a torque converter at a high value during a normal cruising of a vehicle to enhance the specific fuel consumption, and to reduce the speed ratio during depression of the accelerator pedal to enhance the accelerating performance.