Patent ID: 6935452

Claim:
A two-wheel/four-wheel drive switching device for a vehicle comprising: a switching unit provided in either a power transmitting mechanism interposed between an engine and front wheels or a power transmitting mechanism interposed between said engine and rear wheels for switching between the continuation and interruption of power transmission in said power transmitting mechanism; and a control unit for controlling said switching unit, said control unit detecting a drive current supplied to said switching unit and performing variable duty control to maintain said drive current at a given value; wherein the switching unit includes: a drive shaft connected to an engine of the vehicle; a driven shaft engaged with the drive shaft with an annular space defined therebetween; a plurality of engaging members located in this annular space between the drive shaft and the driven shaft so as to disengageably engage the opposed surfaces of the drive shaft and the driven shaft; a switching mechanism for selectively moving the engaging members between a position where the drive shaft and the driven shaft are connected with each other and a position where the drive shaft and the driven shaft are disconnected from each other; a casing; a cylindrical outer ring rotatably mounted in the casing so as to axially project from the casing toward the engine, the outer ring being axially divided into a first outer ring and a second outer ring, the second outer ring having one end connected via a spline and integrally rotatable to the first outer ring, and another end connected via another spline to the drive shaft; and a cylindrical inner ring provided inside the outer ring, an inner circumferential surface of the inner ring being formed with a spline for connecting the driven shaft to the inner ring.