Device for prevention of slap-back lock of inertia reel

• US 5,794,878 A
• Filed: 05/20/1997
• Issued: 08/18/1998
• Est. Priority Date: 05/20/1997
• Status: Expired due to Term

• Current Assignee: AmSafe, Inc. (Transdigm Group Incorporated)
• Original Assignee: AmSafe, Inc. (Transdigm Group Incorporated)
• Inventors: Hagan, Willard F., Carpenter, Christopher, Freeman, Michael J., Warrick, James C., Zollinger, Lindsay P.
• Primary Examiner(s): DARLING, JOHN PATRICK
• Application Number:
  US08/861,882
• Time in Patent Office: 455 Days
• Field of Search: 242/381, 280/805, 180/268, 297/475
• US Class Current: 242/381
• CPC Class Codes: B60R 2022/3419 with end lock preventing means
• CPC Class Codes: B60R 22/38 responsive only to belt movement

Abstract

A conventional webbing-locking inertia reel is modified by integration of a device for the prevention of slap-back lock of the inertia reel upon excessively rapid retraction of the webbing worn by a seat occupant as a safety belt and/or harness. The device also slows the retraction of the webbing enough to prevent a hard collision of the webbing stop at the inertia reel. This is accomplished by interacting the reel shaft with a specially designed damping disk so that both the shaft and the damping disk rotate counter-clockwise when an external force pulls the webbing from its rotatable spool, while simultaneously the shaft also interacts with a conventional housed return spring, causing it to wind and build up a rewinding force, which, when the external force is removed or ceases, causes rotation of the shaft, spool, and damping disk clockwise and rewinds the webbing on the spool. The damping disk is installed in a damper housing section filled with a special high-viscosity synthetic grease so that damping occurs when the damping disk is rotated, due to the shear of the grease that occurs when the two surfaces, that of the damping disk and the housing wall, move relative to each other.

Claims

1. A seat restraint system used to protect a seat occupant from sudden decelerations, the seat restraint system comprising:

a supporting frame having two opposite walls;

an inertia reel mounted on said supporting frame, said inertia reel having

a cylindrical spool,

a shaft having a first and a second opposite ends, said shaft supporting said spool and said two opposite ends of said shaft being mounted on said two opposite walls of said supporting frame such that said spool and said shaft rotate on a perpendicular axis to said two opposite walls;

a webbing attached to said shaft, said webbing being reeled or unreeled around said spool depending on the direction of the rotation of said spool;

a damping disk attached to said first opposite end of said shaft;

a spring cup having at least one wall, said spring cup being attached to said supporting frame and having a spring having a first end attached to said spring cup and a second end attached to said first opposite end of said shaft proximate said damping disk such that said spring creates rotational force to cause said spool to rotate;

a damping housing having a wall attached to said at least one wall of said spring cup forming a damping chamber between said at least one wall of said spring cup and said wall of said damping housing encasing said damping disk; and

wherein said damping chamber is filled with a high viscosity fluid which causes a fluid damping force against said damping disk when said damping disk is rotated.

2. The seat restraint system of claim 1 further comprising:

a sensing mechanism which prevents the sudden rotation of said spool in one rotation direction.

3. The seat restraint system of claim 1 wherein said damping disk is so shaped as to experience a greater fluid damping force when said damping disk is rotated in one direction than when said damping disk is rotated in the opposite direction.

4. The seat restrain system of claim 3, wherein said damping disk has three hook shaped vanes.

5. The seat restraint system of claim 1 wherein said high viscosity fluid is a synthetic damping grease.

6. The seat restraint system of claim 1 wherein said damper housing is attached to said spring cup by a plurality of integral plastic pins fit through a plurality of holes in said spring cup.

7. The seat restraint system of claim 6 wherein said pins are heat staked to be melted to fill to form a tight head for each of said pins.

8. The seat restraint system of claim 1 wherein said wall of said spring cup has a hole which receives a spindle which attaches said damping disk with said first opposite end of said shaft;

and wherein

said hole has a groove around its rim to accommodate an O-ring aligned in said groove around said hole of said wall of said spring cup to prevent leakage of said high viscosity fluid through said hole into said spring cup.

9. The seat restraint system of claim 1 further comprising an O-ring having a circumference greater than the circumference of said damping disk;

and

wherein said O-ring is placed in a circular groove located on said wall of said damping housing to prevent leakage of grease.

10. The seat restraint system of claim 1 wherein said damping disk and said damping housing are fabricated from an acetal resin homopolymer.

11. A rotationally-damped inertia reel mechanism designed to reduce slap-back action, the rotationally-damped inertia reel mechanism comprising;

a supporting frame having two opposite walls;

a spooling member having first and second opposite ends, said two opposite ends of said spooling member being mounted on said two opposite walls of said supporting frame such that said spooling member is capable of rotating on a perpendicular axis to said two opposite walls;

a flexible winding member attached to said shaft, said flexible winding member capable of being reeled or unreeled around said spooling member depending on the direction of the rotation of said spooling member;

a damping member attached to one of said opposite ends of said spooling member, said damping member being so shaped as to experience a greater fluid damping force when said damping member is rotated in one direction than when said damping member is rotated in the opposite direction;

a spring cup having at least one wall, said spring cup being attached to said supporting frame and having a spring having a first end attached to said spring cup and a second end attached to one of said opposite ends of said spooling member such that said spring creates rotational force to cause said spooling member to rotate; and

a damping housing surrounding said damping member, forming a damping chamber therein;

wherein said damping chamber is filled with fluid causing a fluid damping force against said damping member when said damping member is rotated.