Patent ID: 6413184
Filing Date: 2002-07-02
Classification: B60K,F16H

Abstract:
A power transmission system for a four-wheel drive vehicle, which has a differential mechanism having a torque sensing type differential limiting function and including an input element and two output elements made rotatable differentially of each other by receiving a power from said input element for establishing a torque limiting a differential rotation in response to an input torque, one of said two output elements being integrated with a front wheel side drive member, and the other output element being coupled to a rear wheel side drive member, comprising:a torque distribution mechanism for transmitting a torque to a front-wheel drive shaft connected to front wheels or a rear-wheel drive shaft connected to rear wheels; a first selective coupling mechanism for coupling said torque distribution mechanism selectively to said front-wheel side drive member or said rear-wheel side drive member; and a second selective coupling mechanism for coupling said input element and one of said output elements, when said first selective coupling mechanism releases the coupling between said torque distributing mechanism and the front-wheel or rear-wheel side drive member, to integrate said differential mechanism as a whole thereby to establish a two-wheel drive state; wherein said differential mechanism includes: two side gears arranged as said output elements on a common axis; and a case member acting as said input element and holding a first pinion gear meshing with one of said side gears and a second pinion gear meshing with said first pinion gear and the other side gear so that they can rotate and revolve in sliding contact, and wherein said second selective coupling mechanism includes coupling means for coupling said case member and one of said side gears selectively to rotate integrally.