Automatic transmission having torque converter with lockup clutch and method of controlling same lockup clutch

摘要

When a downshift instruction has been detected, the oil pressure of a lookup clutch is controlled, and the state of operation of the automatic transmission is detected. If a starting condition has been met, a slip rotation speed of the lockup clutch is calculated, and if the calculated slip rotation speed is greater than or equal to a reference rotation speed, the calculated slip rotation speed is set as a target slip rotation speed. If a condition for converging the target slip rotation speed has been met, the target slip rotation speed is then converged to a steady target rotation speed.