Patent ID: 7553257

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 between the main drive wheel and the sub drive wheel; and a control section that controls operation of the coupling, the control section estimating a temperature of at least one of heat generating portions of the drive force transmission system by calculating a value related to the heat energy accumulated in the at least one of the heat generating portions during torque transmission through the heat generating portion in correspondence with a rotational speed of the at least one of the heat generating portions and the torque transmission rate in the at least one of the heat generating portions, and correcting the calculated value by a correction value related to an outside temperature, wherein, if the estimated temperature exceeds a predetermined temperature, the control section controls the operation of the coupling to suppress overheating of the heat generating portion.