Monolithic gas generant grains

• US 20070296190A1
• Filed: 06/21/2006
• Published: 12/27/2007
• Est. Priority Date: 06/21/2006
• Status: Active Grant

• Current Assignee: Autoliv ASP Incorporated (Autoliv Incorporated)
• Original Assignee: Autoliv ASP Incorporated (Autoliv Incorporated)
• Inventors: Hussey, Brett, Mendenhall, Ivan, Bradford, Roger
• Granted Patent: US 7,758,709 B2
• Time in Patent Office: Days
• US Class Current: 280/741
• 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, wherein the plurality of apertures have 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.

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 one or more apertures, wherein an initial surface area of the disk is less than about 13,000 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. An inflatable restraint device comprising:

an airbag for restraining motion of a vehicle occupant; and

at least one gas generant for inflating the airbag in the form of a monolithic annular disk having a plurality of apertures and further having 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, wherein the gas generant is substantially free of polymeric binder.

10. The device of claim 9, wherein one or more of the plurality of apertures have a ratio of length to diameter of about 3.5 to about 8 and an initial surface area of the disk is less than about 13,000 mm².

11. The device of claim 10, wherein the gas generant is a pressed monolithic grain in the form of an annular disk comprising one or more apertures, wherein an initial surface area of the disk is less than about 13,000 mm², and the gas generant grain produces an effluent for inflating the airbag that is substantially free of chloride containing species.

12. The device of claim 9, wherein a 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 device of claim 9, wherein a combustion pressure in the inflatable device is less than or equal to about 3,500 pounds per square inch and greater than about 2,000 pounds per square inch for at least 25 milliseconds.

14. A gas generant for an inflatable restraint device comprising an annular disk having a plurality of apertures, 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, wherein 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 oxidizing agents.

15. The gas generant of claim 14, wherein the plurality of apertures have a ratio of length to diameter of about 3.5 to about 8 and an initial surface area of the disk is less than about 13,000 mm².

16. The gas generant of claim 14, wherein the gas generant produces an effluent during burning that is substantially free of chloride containing species.

17. The gas generant of claim 14, wherein the gas generant has a mass density of greater than or equal to about 1.9 g/cm³.

18. The gas generant of claim 14, wherein the gas generant has a gas yield of greater than about 2.4 moles per 100 g of gas generant.

19. The gas generant of claim 14, wherein the gas generant is in a final pressed form that has an actual density of greater than or equal to about 95% of the maximum theoretical mass density of the gas generant.

20. The gas generant of claim 14, wherein the gas generant has a loading density of about 62% to about 63%.