A torque distribution-controlling apparatus has been conventionally known, the apparatus which actively controls, on the basis of a vehicle driving condition, distribution of torque to right and left axles of a vehicle. For example, according to a torque distribution-controlling apparatus, which is disclosed in an examined patent publication JP07-025267A, a pair of clutches are provided at an input side of this apparatus, in which one of the pair of clutches controls torque transmission to a left axle of a vehicle, while the other one of the pair of clutches controls torque transmission to a right axle of the vehicle. Herein, each clutch can be operated independently. Therefore, it is possible to adjust, on the basis of a vehicle driving condition, a degree of torque, which is to be transmitted to the left axle of the vehicle, and a degree of torque, which is to be transmitted to the right axle of the vehicle.
However, in this torque distribution-controlling apparatus described above, a dual shaft structure is employed at an output side of this apparatus, the structure in which two output shafts are provided for the purpose of obtaining torque which have been transmitted to the pair of clutches at the input side. Therefore, an engagement portion between a gear, which is provided for the output shaft of the one of the pair of clutches, and a gear, which is directly linked to the left axle, is displaced or deviated back and forth from a connecting portion between a gear, which is provided for the output shaft of the other one of the pair of clutches, and a gear, which is directly linked to the right axle. As a result, for example when a vehicle is turning, a vehicle behavior may on occasions become different between the vehicle right and left sides. Moreover, according to this dual shaft structure, a torque transmission control, which is performed by each clutch, may become complicated, wherein it is on occasions difficult to finely adjust a degree of torque, which is transmitted to the right and left axles of the vehicle, in response to a vehicle driving condition.
The present invention has been made in view of the above circumstances, and provides a torque distribution-controlling apparatus, according to which a driving force transmitting system for a right wheel of a vehicle is structured in a symmetric manner to a driving force transmitting system for a left wheel of a vehicle, and it is possible to finely control a distribution ratio of torque, which is distributed to the right and left wheels of a vehicle, in response to a vehicle driving condition.