Load Limiting Seat Belt Retractor With Spiral Turn Limiter

• US 20150251627A1
• Filed: 03/06/2014
• Published: 09/10/2015
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: Autoliv ASP Incorporated (Autoliv Incorporated)
• Original Assignee: Autoliv ASP Incorporated (Autoliv Incorporated)
• Inventors: Kohlndorfer, Kenneth, Schulz, Kurt
• Granted Patent: US 9,469,272 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B60R 2022/286 using deformation of material
• CPC Class Codes: B60R 22/3413 operating between belt reel and retractor frame B60R22/4676 takes precedence

Abstract

A motor vehicle seat belt retractor having load limiting features for controlling seat belt restraint loads for a retractor having a spool for storing belt webbing and rotatable with respect to a retractor frame, and a locking mechanism for locking the spool to provide vehicle occupant restraint. A load limiting element coupled with the spool limits restraint loading of the seat belt webbing upon locking of the spool. A rotational displacement limiting mechanism limits the displacement of the load limiting element, the limiting mechanism having a cam forming a spiral flight rotatable with the load limiting element and a cam follower engaging the spiral flight. The cam and the cam follower interengage to reach an end position preventing further relative angular displacement beyond a predetermined angular displacement of the load limiting element. Embodiments provide various configurations for the cam and cam follower elements.

Claims

1. A motor vehicle seat belt retractor having load limiting features for controlling restraint load acting on seat belt webbing stored on the retractor, the retractor of a type having a spool rotatable with respect to a retractor frame, the spool storing the seat belt webbing wrapped thereon, and a locking mechanism for selectively locking the spool to provide vehicle occupant restraint, the retractor comprising:

a load limiting element coupled with the spool, the load limiting element limiting restraint loading of the seat belt webbing upon locking of the locking mechanism, and

a rotational displacement limiting mechanism for limiting the displacement of the load limiting element, the limiting mechanism having a cam forming a spiral flight rotatable with a portion of the load limiting element and having a cam follower engaging the spiral flight, the cam and the cam follower interengaging to reach an end position of the spiral flight preventing further relative angular displacement of the load limiting element beyond a predetermined maximum angular displacement.

2. A motor vehicle seat belt retractor in accordance with claim 1 further comprising the cam follower further engaging a track coupled with the retractor.

3. A motor vehicle seat belt retractor in accordance with claim 1 further comprising the load limiting element is in the form of a torsion bar.

4. A motor vehicle seat belt retractor in accordance with claim 1 further comprising the spiral flight comprising two or more interlaced grooves.

5. A motor vehicle seat belt retractor in accordance with claim 1 further comprising the cam is a tubular load coupler forming the spiral flight in the form of a helical profile on a surface of the tubular load coupler.

6. A motor vehicle seat belt retractor in accordance with claim 5 further comprising the helical profile is formed on an outside surface of the tubular load coupler.

7. A motor vehicle seat belt retractor in accordance with claim 5 further comprising the tubular load coupler is positioned inside a cylindrical cavity formed by the spool.

8. A motor vehicle seat belt retractor in accordance with claim 5 further comprising the tubular load coupler is positioned on an end of the spool and extending therefrom.

9. A motor vehicle seat belt retractor in accordance with claim 7 further comprising the cam follower in the form of a ball, and the spool forming a guide groove defining a channel for movement of the ball along the inside cylindrical cavity of the spool as the spiral flight rotates relative to the spool.

10. A motor vehicle seat belt retractor in accordance with claim 9 further comprising the guide groove having a deformable element disposed therein which resists axial movement of the ball.

11. A motor vehicle seat belt retractor in accordance with claim 9 further comprising, wherein the ball element is restricted from further movement upon reaching an end of the spiral flight thereby locking the coupler to the retractor frame.

12. A motor vehicle seat belt retractor in accordance with claim 1 further comprising, the cam in the form of a first plate having the spiral flight disposed thereon, and the cam follower in the form of a ball element which moves along the spiral flight and radially within a groove formed by a second plate upon angular displacement of the load limiting element.

13. A motor vehicle seat belt retractor in accordance with claim 12 further comprising, a deformable sheet disposed between the first plate and the second plate, the deformable sheet being deformed by the ball element as the ball element moves along the spiral flight and the groove.

14. A motor vehicle seat belt retractor having load limiting features for controlling restraint load acting on seat belt webbing stored on the retractor, the retractor of a type having a spool rotatable with respect to a retractor frame, the spool storing the seat belt webbing wrapped thereon, the retractor comprising:

a load limiting element having a first and a second engagement sections, the first engagement section coupled with the spool to rotate with the spool and the second engagement section selectively coupled with the retractor frame via a locking mechanism, the load limiting element undergoing plastic torsional deformation thereby limiting restraint loading of the seat belt webbing upon locking of the locking mechanism, and

a rotational displacement limiting mechanism for limiting the maximum torsional deformation of the load limiting element, the limiting mechanism having a cam forming a spiral flight rotatable with the load limiting element second engagement section and having a cam follower engaging the spiral flight, the cam and the cam follower interengaging to reach an end position of the spiral flight preventing further relative angular displacement beyond a predetermined maximum angular displacement between the load limiting element first and second engagement sections.

15. A motor vehicle seat belt retractor in accordance with claim 14 further comprising the cam follower further engaging a track coupled with the retractor.

16. A motor vehicle seat belt retractor in accordance with claim 14 further comprising the load limiting element is a torsion bar.

17. A motor vehicle seat belt retractor in accordance with claim 16 further comprising the torsion bar is positioned inside a cylindrical cavity formed by the spool.

18. A motor vehicle seat belt retractor in accordance with claim 14 further comprising the spiral flight comprising two or more interlaced grooves.

19. A motor vehicle seat belt retractor in accordance with claim 14 further comprising the cam is a tubular load coupler forming the spiral flight in the form of a helical profile on a surface of the tubular load coupler.

20. A motor vehicle seat belt retractor in accordance with claim 14 further comprising the helical profile is formed on an outside surface of the tubular load coupler.

21. A motor vehicle seat belt retractor in accordance with claim 14 further comprising the cam is positioned inside a cylindrical cavity formed by the spool.

22. A motor vehicle seat belt retractor in accordance with claim 21 further comprising the cam follower in the form of a ball, and the spool forming a guide groove defining a channel for movement of the ball along the inside cylindrical cavity of the spool as the spiral flight rotates relative to the spool.

23. A motor vehicle seat belt retractor in accordance with claim 22 further comprising the guide groove having a deformable element disposed therein which resist axial movement of the ball.

24. A motor vehicle seat belt retractor in accordance with claim 19 further comprising the load coupler is positioned on an end of the spool and extending therefrom.

25. A motor vehicle seat belt retractor in accordance with claim 14 further comprising, wherein the cam follower is in the form of a ball element which is restricted from further movement upon reaching an end of the spiral flight thereby locking the cam to the retractor frame.

26. A motor vehicle seat belt retractor in accordance with claim 14 further comprising, the cam in the form of a first plate having the spiral flight disposed thereon, and the cam follower in the form of a ball element which moves radially within a groove formed by a second plate upon angular displacement of the load limiting element.

27. A motor vehicle seat belt retractor in accordance with claim 26 further comprising, a deformable sheet disposed between the first plate and the second plate, the deformable sheet being deformed by the ball element as the ball element moves along the spiral flight and the groove.