Device for changing the speeds of the front and rear wheels in a four-wheel-drive vehicle

A device for changing the speeds of the front and rear wheels in a four-wheel-drive vehicle including a continuously variable speed-changing mechanism for the front wheels, which changes the input rotational speed and outputs it to the front wheel drive shafts, and a continuously variable speed-changing mechanism for the rear wheels, which changes the input rotational speed and outputs it to the rear wheel drive shafts, so that the front wheels and the rear wheels can be driven at continuously variable speeds independently of each other due to the continuously variable speed-changing mechanisms, said device for changing the speeds of the front and rear wheels comprising:

• a detector means for detecting the operation conditions of the vehicle;
• a steering angle sensor for detecting the steering angle of the vehicle;
• and
• a controller for variably controlling the speeds of said continuously variable speed-changing mechanism for the front wheels and said continuously variable speed-changing mechanism for the rear wheels based on the operation conditions of the vehicle detected by said detector means;
• said controller setting a target speed-changing ratio obtained from the vehicle operating conditions to be a target speed-changing ratio for the rear wheels in the continuously variable speed-changing mechanism for the rear wheels, and setting a speed-changing ratio obtained from said target speed-changing ratio and from a steering angle detected by said steering angle sensor to be a target speed-changing ratio for the front wheels in the continuously variable speed-changing mechanism for the front wheels.