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

摘要

A device for changing the speeds of the front (10) and rear wheels (14) in a four-wheel-drive vehicle (1) including a continuously variable speed-changing mechanism for the front wheels (10), which changes the input rotational speed and outputs it to the front wheel drive shafts (9), and a continuously variable speed-changing mechanism for the rear wheels (14), which changes the input rotational speed and outputs it to the rear wheel drive shafts (13). The device for changing the speeds of the front wheels (10) and the rear wheels (14) comprises a detector means for detecting the operation conditions of the vehicle (1), a steering angle sensor (18) for detecting the steering angle zeta of the vehicle (1), and a controller (30) for variably controlling the speeds of the continuously variable speed-changing mechanisms (6a, 6b) based on the operation conditions of the vehicle (1). The controller (30) sets a target speed-changing ratio obtained from the vehicle (1) operating conditions to be a target speed-changing ratio for the rear wheels (14) in the continuously variable speed-changing mechanism (6b) for the rear wheels (14), and sets a speed-changing ratio obtained from the target speed-changing ratio and from a steering angle zeta detected by the steering angle sensor (18) to be a target speed-changing ratio for the front wheels (10) in the continuously variable speed-changing mechanism (6a) for the front wheels (10).