Seat belt retractor

• US 4,635,874 A
• Filed: 12/12/1985
• Issued: 01/13/1987
• Est. Priority Date: 12/12/1985
• Status: Expired due to Fees

• Current Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Original Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Swindlehurst, James A.
• Primary Examiner(s): Levy, Stuart S.
• Assistant Examiner(s): Matecki, Katherine A.
• Application Number:
  US06/808,082
• Time in Patent Office: 397 Days
• Field of Search: 242/107.4 B, 242/107.4 D, 242/107.4 A
• US Class Current: 242/383.1
• CPC Class Codes: B60R 22/38 responsive only to belt movement
• CPC Class Codes: B60R 22/41 with additional means for preventing locking during unwinding under predetermined conditions

Abstract

A seat belt retractor includes a reel rotatably mounted on the frame side walls and having toothed plates disposed adjacent to the side walls and a belt wound on the reel to a diameter greater than the toothed plates. A lock bar extending between the side walls is movable from a rest position spaced away from the toothed plates to a locking position engaging one of the sprocket teeth subsequent to the unwinding of sufficient belt from the reel to decrease the belt diameter to a diameter less than the diameter of the sprocket teeth. A sensor pawl eccentrically mounted on the reel flies out into engagement with inside clutch teeth of an annular clutch member, an annular split clutch ring encircles the outer surface of the annular clutch member and has an actuating arm which actuates the lock bar. The split clutch ring has fingers which seat into teeth provided on the outer surface annular clutch member. These teeth on the inner and outer surfaces are equal in number with the sprocket teeth and angularly related therewith to assure full engagement of the lock bar with the sprocket teeth. If an occupant unwinds the belt from the retractor at a high rate of speed which would initiate retractor lockup before the belt has been sufficiently unwound to expose the toothed plates for engagement by the lock bar, the clutch spring will provide a measured incremental slippage of the locking mechanism to permit continued belt unwinding while still maintaining the desired timing relationship between the sensor mechanism and the lock bar.

Claims

1. A seat belt retractor comprising:

a frame having spaced apart side walls;

a reel rotatably mounted on the side walls and having toothed plates disposed adjacent the side walls and having a belt wound thereon to a diameter greater than the diameter of teeth of the toothed plates;

a lock bar extending between the side walls and having a normal rest position spaced away from the toothed plates and being movable to a locking position engaging one of the teeth subsequent to the unwinding of sufficient belt from the reel to decrease the belt diameter to a diameter less than the diameter of the teeth;

a first clutch member mounted for rotary movement relative the reel and having a normal rest position, said first clutch member having means acting to move the lock bar into the engaged position upon said first clutch member rotation from the rest position in the belt unwinding direction of rotation;

a second clutch member having a plurality of circumferentially spaced inner teeth on the inner periphery thereof and an equal number of circumferentially spaced teeth on the outer periphery thereof;

pawl means carried by the reel and movable to selectively couple the reel with the second clutch member in response to a sensed rate of belt unwinding reel rotation so that the pawl rotates the second clutch member in the unwinding direction of rotation; and

said first clutch member being a split clutch ring encircling the outer periphery of the second clutch member and having spring fingers engaging the outer teeth thereof to friction drive couple the split clutch ring with the second clutch member, said split clutch ring further having an actuating arm extending into actuating proximity with the lock bar whereby the lock bar is moved into engagement with the reel teeth to lock the reel against any further belt unwinding belt reel rotation in the event of occurrence of the sensed rate of belt unwinding reel rotation subsequent to the unwinding of sufficient belt from the reel to decrease the belt diameter to a diameter less than the diameter of the teeth of the toothed plates and the split clutch ring slips on the rotating second clutch member in incremental steps defined by the spacing of the outer teeth of the second clutch member in the event that occurrence of the sensed rate of belt unwinding occurs prior to the unwinding of sufficient belt from the reel to expose the teeth of the toothed plates for engagement by the lock bar.