Multiple level load limiter for primary and secondary collisions

• US 5,626,306 A
• Filed: 08/11/1995
• Issued: 05/06/1997
• Est. Priority Date: 08/11/1995
• Status: Expired due to Fees

• Current Assignee: Key Safety Systems, Inc. (Ningbo Junsheng Investment Group Co., Ltd.)
• Original Assignee: Alliedsignal Inc. (Honeywell International Inc.)
• Inventors: Dybro, Niels, Miller, Harold J. III
• Primary Examiner(s): Jillions, John M.
• Application Number:
  US08/514,287
• Time in Patent Office: 634 Days
• Field of Search: 242/379.1, 280/805, 280/806, 297/470, 297/471, 297/472, 297/476, 297/477, 297/478
• US Class Current: 242/379.1
• CPC Class Codes: B60R 22/4676 comprising energy-absorbing means operating between belt reel and retractor frame

Abstract

An energy absorbing seat belt retractor comprising: a frame (22); a spool (24) rotatably mounted relative to the spool including a lock wheel (71) having a plurality of lock teeth associated therewith and adapted to receive a seat belt thereabout; a lock pawl (77) for engaging the spool upon sensing a one of a vehicle deceleration and seat belt extraction above certain determinable levels; and movable nut (90) located in the spool and for prohibiting relative movement between the lock wheel and spool below a threshold input force level generated in part by occupant load on the seat belt and for generating a controlled energy dissipating reaction force on the seat belt after the input force exceeds the threshold level to permit a controlled rotation of the spool and the controlled pay-out of the seat belt from the spool during a first and subsequent accidents.

Claims

1. A seat belt retractor (20) for protecting an occupant during a vehicle impact comprising:

a rotating spool or reel (24),

seat belt webbing (31) wound about the spool and adapted to extend about the occupant;

first locking means (71) operatively connected to the spool for initially preventing the rotation of the spool during a first impact,

first means (90,

     100) associated with the spool, for enabling the spool to rotate after a predetermined load, in excess of a first level, has been applied to the webbing, and for generating a generally constant reaction force of a first level on the webbing opposing occupant motion, including a deformable bushing and a displaceable member which compresses the bushing, wherein the bushing deforms outwardly as it is compressed;

second means, active after belt forces reach the predetermined load on the seat belt webbing, for increasing the reaction force as a function of further protraction of the seat belt webbing from the spool and to generate a higher reaction force of a second level on the webbing, including wherein the spool includes a bore disposed about the bushing and wherein after a predetermined amount of motion of the displaceable member the bushing is deformed sufficiently outwardly to abut an inner wall of the bore thereby effectively increasing the stiffness of the bushing, whereupon any further outward expansion of the bushing is prohibited and further motion of the displaceable member is resisted thereby generating the reaction force at the second level.

2. The device as defined in claim 1 wherein a washer is disposed between the bushing and displaceable member.

3. A seat belt retractor (20) for protecting an occupant during a vehicle impact comprising:

a rotating spool or reel (24),

seat belt webbing (31) wound about the spool and adapted to extend about the occupant;

first locking means (71) operatively connected to the spool for initially preventing the rotation of the spool during a first impact,

first means (90,

     100) associated with the spool, for enabling the spool to rotate after a predetermined load, in excess of a first level, has been applied to the webbing, and for generating a generally constant reaction force at a first level on the webbing opposing occupant motion, including a deformable bushing having a first thin portion which is outwardly expandable into a washer-like shape and a displaceable member which compresses the thin first bushing portion to the washer-like shape thereby generating the first level reaction force;

second means, active after belt forces reach the predetermined load on the seat belt webbing for increasing the reaction force as a function of further protraction of the seat belt webbing from the spool and to generate a higher reaction force at a second level on the webbing, including a second bushing portion, adjacent the first bushing portion and opposite the displaceable member, the second bushing portion being more resistive to the compressive motion of the displaceable member than is the first bushing portion to thereby generate the second level reaction force.

4. A seat belt retractor (20) for protecting an occupant during a vehicle impact comprising:

a rotating spool or reel (24),

seat belt webbing (31) wound about the spool and adapted to extend about the occupant;

first locking means (71) operatively connected to the spool for initially preventing the rotation of the spool during a first impact,

first means (90,

     100) associated with the spool, for enabling the spool to rotate after a predetermined load, in excess of a first level, has been applied to the webbing, and for generating a generally constant reaction force of a first level on the webbing opposing occupant motion and thereafter for generating a reaction force of a higher second level, including an annular carrier (222) having a center member (224) and a first bushing (228) positioned adjacent one side of the center member and a second bushing (230) positioned adjacent an opposite side of the center member, wherein the yield strength of the first and second bushings are dissimilar, whereby the first level reaction force is generated as the displaceable member deforms the first bushing and the second level reaction force is generated as the second bushing is deformed.

5. The device as defined in claim 4 wherein a washer is disposed between the thin bushing portion and displaceable member.