Patent ID: 6865470

Claim:
A four-wheel drive vehicle, comprising: a source of traction; a main path which serves to transfer traction; an auxiliary path branched from the main path, the auxiliary path serving to transfer traction; main driving wheels which receive traction from the source through the main path; driven wheels which receive traction through the auxiliary path; a clutch arranged in the auxiliary path, the clutch changing traction to be transferred to the driven wheels through a change in engaging force; a device which detects a speed of a vehicle body; a device which detects speeds of the respective wheels; and an ECU which provides to the clutch a control signal for carrying out the change in engaging force, the ECU being se programmed so as to: calculate a control threshold value in accordance with the detected vehicle-body speed, carry out a traction distribution control to increase distribution of traction to the driven wheels when a difference in detected wheel speeds between the main driving wheels and the driven wheels exceeds the control threshold value, detect a constant-speed run of the vehicle, and carry out a correction control to correct the control threshold value in accordance with the detected vehicle-body speed and the difference in detected wheel speeds when the constant-speed run is detected.