Patent ID: 7195581

Claim:
A power transmission device which transmits power of an engine to a drive wheel, the power transmission device comprising: an automatic transmission; a torque converter comprising a lockup clutch, the torque converter being disposed between the engine and the automatic transmission; a switching mechanism which switches an engaging state of the lockup clutch; and a controller which performs open loop control of the engaging state of the lockup clutch through the switching mechanism, when the torque converter transitions from a first state in which the lockup clutch is disengaged to a second state in which the lockup clutch is at least partially engaged, wherein the controller: estimates a torque of the engine at a time when the open loop control ends; estimates a necessary lockup capacity required for the converter at the time when the open loop control ends, based on the estimated torque of the engine; and controls the engaging state of the lockup clutch through the switching mechanism to make a lockup capacity, at the time when the open loop control ends, become the necessary lockup capacity.