Central differential for a four-wheel drive motor vehicle

Claim 1

In a central differential, comprising a planetary gear device, for a four wheel drive motor vehicle for distributing torque at a predetermined ratio, comprising an input member operatively connected to a power source for inputting input torque, a front torque transmitting member for transmitting a distributed torque to front wheels of the vehicle, and a rear torque transmitting member for transmitting another distributed torque to rear wheels of the vehicle, the improvement in the differential wherein the planetary gear device comprises: a first sun gear; a second sun gear disposed coaxially with an axis of said first sun gear; a carrier disposed coaxially with said axis; a first planetary pinion meshed with said first sun gear; a second planetary pinion meshed with said second sun gear; the number of teeth of said first planetary pinion being equal to the number of teeth of said second planetary pinion, and both said pinions being different in module; a plurality of pinion sets, each comprising said first planetary pinion and said second planetary pinion formed integrally with each other in same phase, and equiangularly disposed around said axis and rotatably supported on said carrier; the difference between the number of teeth of said first sun gear and the number of teeth of said second sun gear integrally multiplied by the number of said pinion sets is an integer; said carrier operatively connected to one of said torque transmitting members; one of said sun gears being coaxially connected to another of said torque transmitting members; and the other of said sun gears being coaxially connected to the input member so as to improve assembling and workability of the planetary gear device.