Patent ID: 7235036

Claim:
A lockup control method for a vehicular torque converter, comprising: controlling a differential-pressure to a lockup clutch during a steady-state traveling state, in such a manner that the torque converter is under a steady-state lockup state where input and output elements of the torque converter are directly connected with each other by the lockup clutch under a steady-state lockup differential-pressure level; controlling the differential-pressure during a coasting state where an accelerator opening is completely closed, in such a manner that the torque converter is under a coast lockup state where the differential-pressure is lower than the steady-state lockup differential-pressure level; controlling the differential-pressure when an engine speed becomes equal to or lower than a lockup release rotational speed, in such a manner that a lockup state is released; calculating an actual lockup release time which is a time period between a time point at which a lockup release command for releasing the lockup state is outputted and a time point at which the lockup clutch actually becomes released in response to the lockup release command; and setting the lockup release rotational speed on the basis of the calculated actual lockup release time.