Patent ID: 7581612

Claim:
A drive force distribution device of a vehicle including a main drive wheel, a sub drive wheel, and a drive force transmission system that transmits a drive force generated by a drive source to the drive wheels, the device comprising: a coupling arranged in the drive force transmission system, wherein the coupling changes a torque transmission rate of a torque transmitted from an input of the coupling to an output of the coupling, thereby varying a drive force distribution ratio of the main drive wheel to the sub drive wheel; a control section that controls operation of the coupling, the control section estimating the temperature of at least one of heat generating portions of the drive force transmission system by accumulating a heat generating energy accumulated in the heat generating portion in correspondence with the load acting on the heat generating portion, wherein, if the estimated temperature exceeds a predetermined temperature, the control section controls the operation of the coupling to reduce the load acting on the heat generating portion, thereby suppressing overheating of the heat generating portion; a memory portion that memorizes the estimated temperature as a memorized temperature before the drive source is stopped; and a timer portion that, upon re-start of the drive source after the drive source is stopped, measures the time since the stopping of the drive source, wherein the control section controls the operation of the coupling in correspondence with the measured time and the memorized temperature immediately after the drive source is re-started.