Lockup control apparatus and method for automatic transmission

摘要

A lockup control apparatus and method of an automatic transmission engages a lockup clutch smoothly by gradually varying an electrical signal and holds a lockup pressure at a level corresponding to the engine load when the lockup clutch is engaged. The engagement of the lockup clutch is detected by comparing an engine rotational speed with a turbine rotational speed. The lockup pressure is determined at a minimal value enabling the lockup clutch to be engaged with a sufficient margin. Advantages of the lockup control apparatus are that shocks occured when the lockup clutch is engaged or disengaged can be attenuated and the life of the lockup clutch is substantially prolonged.