Monolithic gas generant grains

• US 7,758,709 B2
• Filed: 06/21/2006
• Issued: 07/20/2010
• Est. Priority Date: 06/21/2006
• Status: Expired due to Fees

• Current Assignee: Autoliv ASP Incorporated (Autoliv Incorporated)
• Original Assignee: Autoliv ASP Incorporated (Autoliv Incorporated)
• Inventors: Bradford, Roger, Mendenhall, Ivan, Hussey, Brett
• Primary Examiner(s): Lorengo; Jerry
• Assistant Examiner(s): McDonough; James E
• Application Number:
  US11/472,260
• Publication Number:
  US 20070296190A1
• Time in Patent Office: 1,490 Days
• Field of Search: 149/23, 149/2, 149/45, 149/109.4
• US Class Current: 149/23
• CPC Class Codes: B60R 21/2644 using only solid reacting substances, e.g. pellets, powder
• CPC Class Codes: C06B 45/00 Compositions or products which are defined by structure or arrangement of component of product explosive charges of particular form or shape F42B1/00, F42B3/00
• CPC Class Codes: C06D 5/06 by reaction of two or more solids

Abstract

A gas generant for an inflatable restraint device (for example, an airbag system for a vehicle) is a monolithic compressed solid that has a linear burn rate of greater than or equal to about 1.6 inches per second at a pressure of about 3,000 pounds per square inch. The gas generant can be in the form of an annular disk having a plurality of apertures. The gas generant may be substantially free of binder and may have a low initial surface area which progressively increases during burning. The gas generant provides a gas generation profile that improves restraint of vehicle occupants, including those occupants that are out-of-position. Additionally, the shaped gas generant decreases occupant exposure to toxic effluent combustion products and solid respirable particulates.

Claims

1. A pressed monolithic gas generant for an inflatable restraint device comprising an annular disk having a plurality of apertures, a first aperture of said plurality of apertures having a first diameter and a second aperture of said plurality of apertures having a second diameter, wherein said first diameter is greater than said second diameter, an initial surface area of the disk is less than about 13,000 mm², wherein a linear burn rate of the gas generant is greater than or equal to about 1.6 inches per second at a pressure of about 3,000 pounds per square inch, a product of a mass density and a gas yield of the gas generant is greater than or equal to about 5.0 moles/100 cm³, and wherein the gas generant is substantially free of polymeric binder and is azide free.

2. The gas generant of claim 1, wherein the gas generant has a mass density of greater than or equal to about 1.9 g/cm³.

3. The gas generant of claim 1, wherein the gas generant has a gas yield of greater than about 2.4 moles per 100 g of gas generant.

4. The gas generant of claim 1, wherein the gas generant in a final pressed form has an actual density of greater than or equal to about 95% of the maximum theoretical mass density of the gas generant.

5. The gas generant of claim 1, wherein the gas generant has a flame temperature of less than or equal to about 2300 Kelvin.

6. The gas generant of claim 1, wherein the gas generant is substantially free of perchlorate-containing oxidizing agents.

7. The gas generant of claim 1, wherein the generant is a pressed monolithic grain in the form of an annular disk comprising said plurality of apertures, wherein an initial surface area of the disk is less than about 12,000 mm².

8. The gas generant of claim 7, wherein the one or more of the plurality of apertures have a ratio of length to diameter of less than about 7.5.

9. The gas generant of claim 1, wherein the gas generant in a final pressed form has an actual density of greater than or equal to about 97% of the maximum theoretical mass density of the gas generant.

10. The gas generant of claim 1, wherein said linear burn rate of the gas generant is greater than or equal to about 1.8 inches per second at a pressure of about 3,000 pounds per square inch.

11. The gas generant of claim 10, wherein said linear burn rate of the gas generant is less than or equal to about 2.3 inches per second at a pressure of about 3,000 pounds per square inch.

12. The gas generant of claim 1, wherein said product of a mass density and a gas yield of the gas generant is greater than or equal to about 5.2 moles/100 cm³.

13. The gas generant of claim 1, comprising a substituted basic metal nitrate, wherein the substituted basic metal nitrate includes a reaction product of an acidic organic compound and a basic metal nitrate.

14. The gas generant of claim 13, wherein said substituted basic metal nitrate comprises 5-amino tetrazole substituted basic copper nitrate.

19. The gas generant of claim 1, wherein the first aperture having said first diameter greater than said second diameter defines a central aperture of said annular disk.

20. The gas generant of claim 1, wherein said plurality of apertures further comprises a plurality of said second apertures.

21. The gas generant of claim 1, wherein said first diameter is at least three times greater than said second diameter.

15. A pressed monolithic gas generant for an inflatable restraint device comprising an annular disk having a plurality of apertures, comprising a first aperture of said plurality of apertures having a first diameter and a second aperture of said plurality of apertures having a second diameter, wherein said first diameter is greater than said second diameter, and said second aperture has a ratio of length to diameter of about 3.5 to about 8, an initial surface area of the disk is less than about 13,000 mm², wherein a linear burn rate of the gas generant is greater than or equal to about 1.8 inches per second at a pressure of about 3,000 pounds per square inch and less than or equal to about 2.3 inches per second at a pressure of about 3,000 pounds per square inch, a product of a mass density and a gas yield of the gas generant is greater than or equal to about 5.0 moles/100 cm³, and wherein the gas generant is substantially free of polymeric binder and is azide free.

16. The gas generant of claim 15, comprising a substituted basic metal nitrate, wherein the substituted basic metal nitrate includes a reaction product of an acidic organic compound and a basic metal nitrate.

22. The gas generant of claim 15, wherein the first aperture having said first diameter greater than said second diameter defines a central aperture of said annular disk.

23. The gas generant of claim 15, wherein said plurality of apertures further comprises a plurality of said second apertures.

24. The gas generant of claim 15, wherein said first diameter is at least three times greater than said second diameter.

17. A pressed monolithic gas generant for an inflatable restraint device comprising an annular disk having a plurality of apertures, comprising a first aperture of said plurality of apertures having a first diameter and a second aperture of said plurality of apertures having a second diameter, wherein said first diameter is greater than said second diameter, and said second aperture has a ratio of length to diameter of about 3.5 to about 8, an initial surface area of the disk is less than about 13,000 mm², wherein a linear burn rate of the gas generant is greater than or equal to about 1.6 inches per second at a pressure of about 3,000 pounds per square inch, a product of a mass density and a gas yield of the gas generant is greater than or equal to about 5.0 moles/100 cm³, and wherein the gas generant is substantially free of polymeric binder and perchlorate-containing oxidizers and is azide free.

18. The gas generant of claim 17, comprising a substituted basic metal nitrate, wherein the substituted basic metal nitrate includes a reaction product of an acidic organic compound and a basic metal nitrate.

25. The gas generant of claim 17, wherein the first aperture having said first diameter greater than said second diameter defines a central aperture of said annular disk.

26. The gas generant of claim 17, wherein said plurality of apertures further comprises a plurality of said second apertures.

27. The gas generant of claim 17, wherein said first diameter is at least three times greater than said second diameter.