Patent ID: 8666628

Claim:
A torque distribution control apparatus for a four-wheel drive vehicle, comprising: a vehicle-speed detector configured to detect a vehicle speed of the four-wheel drive vehicle which includes: right and left main driving wheels to which a driving torque output from a driving source is directly transmitted; and right and left sub-driving wheels to which the driving torque is transmitted via right and left torque distribution clutches; a wheel-speed detector configured to detect wheel speeds of the main driving wheels and the sub-driving wheels; a sub-driving-wheel distribution-torque calculator configured to calculate a sub-driving-wheel distribution torque in accordance with a rotation speed difference between the main driving wheels and the sub-driving wheels calculated based on an output from the wheel-speed detector; a torque limiter configured to limit an upper limit of the sub-driving-wheel distribution torque when the sub-driving-wheel distribution torque calculated by the sub-driving-wheel distribution-torque calculator is higher than or equal to a first predetermined value, when both a rotation speed difference of the left torque distribution clutch and a rotation speed difference of the right torque distribution clutch are larger than or equal to a second predetermined value, and when the vehicle speed detected by the vehicle-speed detector is lower than or equal to a third predetermined value; and a controller configured to control, by changing engaging forces of the right and left torque distribution clutches in accordance with a driving state of the four-wheel drive vehicle, the sub-driving-wheel distribution torque to be transmitted to the right and left sub-driving wheels.