Patent ID: 6634978
Filing Date: 2003-10-21
Classification: B60K,F16H

Abstract:
A differential device for 4WD vehicles comprising:a differential case which receives a driving force from a driving shaft to rotate the differential case; first and second side gears accommodated in the differential case to deliver the driving force transmitted to the differential case at a ratio to first and second wheels; a rotation member rotatable together with the first wheel; a sole actuator; a switching mechanism operatively driven along a wheel-axis by the sole actuator to selectively establish one of: 1) a 2WD state in which the rotation member is out of connection with the first side gear; 2) a differential-free 4WD state in which a connection is established only between the rotation member and the first side gear; and 3) a differential-locked 4WD state in which the first side gear is connected to both the differential case and the rotation member; the switching mechanism comprising: a movable first member continually connected to the rotation member, the first member being connected to the first side gear when the first member is moved in one direction along the wheel-axis relative to the rotation member, the first member being disconnected from the first side gear when the first member is moved in an opposite direction relative to the rotation member; a movable second member continually connected to the first member, the second member being connected to the differential case when the second member is moved in one direction along the wheel-axis relative to the first member, the second member being disconnected from the differential case when the second member is moved in an opposite direction along the wheel-axis relative to the first member; the second member being positionable in a first position corresponding to the 2WD state, a second position corresponding to the differential-free 4WD state, and a third position corresponding to the differential-locked 4WD state; a relative movement inhibiting mechanism which on demand inhibits movement of the first member relative to the rotation member, and which on demand inhibits movement of the second member relative to the first member; the relative movement inhibiting mechanism being constructed so that: while the second member is positioned within a range from the first position to the second position, the relative movement inhibiting mechanism inhibits the movement of the second member relative to the first member while the first member and the second member are concurrently moved relative to the rotation member; while the second member is positioned within a range from the second position to the third position, the relative movement inhibiting mechanism inhibits the movement of only the first member relative to the rotation member, while the second member is brought into movement relative to the first member under an immovable condition of the first member along the wheel-axis.