Vehicle occupant restraint belt retractor

Claim 1

In a vehicle occupant restraint belt retractor including a housing adapted to be mounted on a vehicle, a belt reel rotatably supported by the housing, an occupant restraint belt wound and unwound from the reel upon reel rotation in opposite directions, means normally biasing the reel in the belt winding direction of rotation, and an inertia locking mechanism for selectively locking the belt reel against rotation in the belt unwinding direction, a mechanism for selectively preventing the biasing means from rotating the belt reel in the belt winding direction so as to hold the belt in an unwound condition for use, the mechanism comprising: a circular ratchet configuration on the belt reel concentric about the axis of rotation thereof and having locking surfaces spaced circumferentially thereabout so as to face in the belt winding direction of reel rotation; a detent member mounted on the housing for movement between a nonlocking position out of engagement with the circular ratchet configuration so as to permit belt winding reel rotation and a locking position in engagement with the ratchet configuration so as to prevent this belt winding reel rotation; means biasing the detent member to the locking position; the belt reel having an annular surface generated about the axis of reel rotation and rotatable therewith during belt winding and unwinding reel rotation; a control disk rotatable with respect to the reel about the rotational axis thereof and having one side engaged with the annular surface of the reel, the control disk including a control portion that engages the detent member to move this member to the nonlocking position when the control disk rotates in the belt unwinding direction so that the reel is thereby free to rotate in the belt winding direction, a first pair of engageable surfaces on the control disk and the housing for limiting the rotation of the control disk in the belt unwinding direction after the detent member has been moved to the nonlocking position, and a second pair of engageable surfaces on the control disk and the housing for limiting the rotation of the control disk in the belt winding direction of rotation so that the total rotation of the control disk is less than one revolution; a blocking disk rotatable with respect to the reel about the rotational axis thereof and being positioned on the opposite side of the control disk from the annular surface of the reel, the blocking disk having a blocking portion with a notch for holding the detent member in the nonlocking position after the control disk moves the detent member to this non-locking position, the detent member engaging the blocking portion to limit movement of the blocking disk in the belt winding direction, and a pair of engageable surfaces on the housing and the blocking disk for limiting rotation of the blocking disk in the belt unwinding direction so that the total rotation of the blocking disk is less than one reVolution; and a resilient spring means engaging the side of the blocking disk opposite the control disk so as to bias the blocking disk into frictional engagement with the control disk and to in turn bias the control disk into frictional engagement with the annular surface of the reel so that reel rotation rotates the control disk in a clutched manner between the limits of its rotation and rotation of the control disk rotates the blocking disk in a clutched manner between the limits of its rotation, the control disk being rotated by this clutching to its limit of rotation in the belt unwinding direction as the belt in unwound to thereby move the detent member to its nonlocking position, the notch in the blocking portion of the blocking disk engaging the detent member to hold the detent member in the nonlocking position so as to permit the reel to wind the belt and to concomitantly prevent the clutching of the blocking disk to the control disk from rotating the blocking disk in the belt winding direction with the control disk, the blocking disk being subsequently moved in the belt unwinding direction of rotation by the control disk as the belt is unwound so as to disengage the detent member and allow the bias thereof to move the detent member to locked position and to thereby prevent belt winding until the belt is subsequently unwound a sufficient extent to again engage the control portion of the control disk with the detent member so as to again move the detent member to the nonlocking position.