Torque split control system for a four-wheel drive motor vehicle

Claim 1

In a system for controlling torque split for a four-wheel drive vehicle having a transmission, a central differential for splitting output torque of the transmission at a predetermiend ratio, power trains for transmitting the split torques from output members of the central differential to front and rear wheels of the vehicle, the improvement of the system, which comprises: said central differential comprising an input sun gear operatively conencted with an output shaft of said transmission, a plurality of output sun gears coaxial with said input sun gear, a carrier operatively conencted to a set of driving wheels of said vehicle, a pinion member comprising a plurality of planetary pinions which are different in the number of teeth and integral with each other and rotatably supported on said carrier, each of said planetary pinions being engaged with corresponding ones of said sun gears and an output member operatively conencted to another set of driving wheels; selecting means for selectively connecting one of said output sun gears to said output member; and a control unit for operating said selecting means in accordance with driving conditions of the vehicle so as to select one of said output sun gears.

Claim 7

The system according to claim l,further comprising: means for rendering said central differential operative during a period of time when said selecting means operates to select one of said output sun gears, thereby preventing a decrease of the split torque during the period.