Lock-up control apparatus in automatic transmission

摘要

In an automatic transmission having a torque converter interposed between an engine and a transmission mechanism, the torque converter includes a lock-up clutch capable of directly coupling an output shaft of the engine and an input shaft of the transmission mechanism. A speed difference detector is provided for detecting a difference between engine rotational speed and input shaft rotational speed. An engine speed controller means is also provided for controlling the engine speed to cause the speed difference to converge within a predetermined range. By detecting the speed difference, it is possible to precisely detect the actual vehicle state, and to reliably and smoothly engage the lock-up clutch without generating shift shock in any vehicle state. With this structure, the lock-up clutch can be reliably engaged and the engine brake can be secured.