Wrapped gas generant cartridge

• US 5,763,820 A
• Filed: 05/12/1997
• Issued: 06/09/1998
• Est. Priority Date: 01/16/1996
• Status: Expired due to Term

• Current Assignee: Autoliv ASP Incorporated (Autoliv Incorporated)
• Original Assignee: Autoliv ASP Incorporated (Autoliv Incorporated)
• Inventors: Philpot, Paul T., Jackson, Scott A., Lindsey, David W.
• Primary Examiner(s): TUDOR, HAROLD JAY
• Application Number:
  US08/854,599
• Time in Patent Office: 393 Days
• Field of Search: 102/200, 102/202, 102/282, 102/285, 102/288, 102/289, 102/290, 102/322, 102/331, 102/430, 102/431, 102/433, 102/434, 102/443, 102/464-466, 102/530, 102/531, 102/700, 280/741
• US Class Current: 102/531
• CPC Class Codes: B60R 21/2644 using only solid reacting substances, e.g. pellets, powder
• CPC Class Codes: F42B 3/04 for producing gas under pressure generators of inflation fluid especially adapted for vehicle air bags B60R21/26
• CPC Class Codes: F42B 5/16 characterised by composition or physical dimensions or form of propellant charge, with or without projectile, or powder chemical composition C06B; F42B5/24 takes precedence

Abstract

A wrapped gas generant cartridge is incorporated in an inflator of a vehicle occupant restraint system. The gas generant cartridge includes a stacked, aligned plurality of substantially flat annular wafers of gas generant material having a central opening therethrough. A wrap of sheet material surrounds the plurality of wafers and has marginal end panels folded along the end surfaces of the plurality of wafers, leaving at least one end opening exposed for receiving an ignition tube of the inflator. The wrap of sheet material is selected from metal foil, expanded metal, cellulose, thermoplastics, including polyolefin shrink wrap, with tape, adhesive or adhesive laminates holding the wrap in position. The gas generant cartridge is received in a filter and screen pack within the inflator.

Claims

1. A wrapped gas generant cartridge for handling and transporting thereof for installation at a later time in inflators for vehicle occupant restraint systems, the wrapped gas generant cartridge comprising:

A) a stacked aligned plurality of substantially flat annular wafers of gas generant material, each wafer having a center opening, wherein the, stacked aligned plurality of wafers has;

1) a cylindrical outer surface,

2) a central opening, and

3) annular end faces extending between the ends of the cylindrical outer surface and the ends of the central opening,

B) a pyrotechnic-free wrap of sheet material surrounding the cylindrical outer surface of the stacked, aligned plurality of wafers, the sheet material holding the wafers in alignment; and

C) the wrap of sheet material having marginal end panels respectively extending inwardly from the ends of the cylindrical surface along only a portion of the annular end faces of the plurality of wafers, the marginal end panels holding the wafers in a stack so that the central opening is exposed in at least one end of the wrap for accepting an ignition system at the later time when the wrapped gas generant cartridge is assembled into the inflator.

2. A gas generant cartridge as defined in claim 1 wherein the wrap of sheet material is a metal foil surrounding the cylindrical outer surface of the stacked, aligned plurality of wafers and overlapping itself and defining an overlapping portion secured to itself for holding the wafers in alignment.

3. A gas generant cartridge as defined in claim 2 and further comprising at least one strip of tape securing the overlapping portion of the wrap of sheet material in position surrounding the cylindrical outer surface of the stacked, aligned plurality of wafers.

4. A gas generant cartridge as defined in claim 3 and further comprising a strip of tape securing a portion of the wrap of sheet material to the plurality of wafers.

5. A gas generant cartridge as defined in claim 2 wherein the marginal end panels of the metal foil are folded into overlapping pleats along the annular end faces of the plurality of wafers.

6. A gas generant cartridge as defined in claim 5 wherein the folded marginal end panels extend approximately halfway along the annular end faces of the plurality of wafers.

7. A gas generant cartridge as defined in claim 6 wherein the metal foil is aluminum.

8. A gas generant cartridge as defined in claim 2 and further comprising adhesive applied to the overlapping portion and marginal end panels of the metal foil wrap of sheet material for securing the sheet in wrapped condition with annular bands along the annular end faces of the plurality of wafers.

9. A gas generant cartridge as defined in claim 2 and further comprising adhesive applied over the surface of the metal foil wrap of sheet material surrounding the cylindrical outer surface of the plurality of wafers and folded inwardly into bands extending along the end faces of the plurality of wafers.

10. A gas generant cartridge as defined in claim 1 wherein the wrap of sheet material is thermoplastic.

11. A gas generant cartridge as defined in claim 10 wherein the thermoplastic is a polyolefin shrink wrap.

12. A gas generant cartridge as defined in claim 10 wherein the wrap of sheet material is a thermoplastic surrounding the cylindrical outer surface of the stacked, aligned plurality of wafers and overlapping itself and secured to itself for holding the wafers in alignment, with adhesive applied to the overlapping portion and marginal end panels, and having its marginal end panels folded inwardly along the annular end faces of the plurality of wafers for holding the wafers in a stack.

13. A gas generant cartridge as defined in claim 10 and further comprising adhesive applied over the surface of the thermoplastic wrap of sheet material surrounding the cylindrical outer surface of the plurality of wafers and folded inwardly along the end faces of the plurality of wafers.

14. A gas generant cartridge as defined in claim 10 wherein the wrap of sheet material is polyethylene.

15. A gas generant cartridge as defined in claim 10 wherein the wrap of sheet material is polyester.

16. A gas generant cartridge as defined in claim 1 wherein the wrapped sheet material is cellulose surrounding the cylindrical outer surface of the stacked, aligned plurality of wafers and overlapping itself and secured to itself for holding the wafers in alignment, and having its marginal end panels folded inwardly along the annular end faces of the plurality of wafers for holding the wafers in a stack.

17. An inflator for a vehicle occupant restraint system, the inflator comprising;

A) a housing defining an outlet opening for delivery of inflation gas;

B) a wrapped gas generant cartridge having a stacked aligned plurality of substantially flat, annular wafers of gas generant material, each wafer, having a center opening, wherein the stacked aligned plurality of wafers has;

1) a cylindrical outer surface,

2) a central opening, and

3) annular end faces extending between the ends of the cylindrical outer surface and the ends of the central opening;

C) a pyrotechnic-free wrap of non-perforated foil, film, paper or coated paper sheet material surrounding the cylindrical outer surface of the stacked, aligned plurality of wafers, the sheet material holding the wafers in alignment;

D) the wrap of sheet material having marginal end portions respectively extending inwardly from the ends of the cylindrical surface along only a portion of the annular end faces of the plurality of wafers, the marginal end portions holding the wafers in a stack so that the central opening is exposed in at least one end of the wrap;

E) means receiving and supporting the wrapped gas generant cartridge within the housing; and

F) ignition means positioned in the inflator by means of the open end of the central opening of the wrapped generant cartridge for igniting the gas generant wafers in the central opening thereof.

18. An inflator as defined in claim 17 wherein the means receiving and supporting the wrapped gas generant cartridge in the housing is a tubular filter and screen park.

19. An inflator as defined in claim 17 wherein the ignition means is an ignition tube extending substantially through the central opening of the wrapped gas generant cartridge.

20. A gas generant cartridge as defined in claim 17 wherein the wrap of sheet material is a metal foil surrounding the cylindrical outer surface of the stacked, aligned plurality of wafers and overlapping itself and secured to itself for holding the wafers in alignment.