Method for controlling the burning pressure in apreinflator, preinflator per se and hybrid gas generator incorporating such a preinflator

• US 20050250059A1
• Filed: 12/17/2001
• Published: 11/10/2005
• Est. Priority Date: 01/19/2001
• Status: Active Grant

• Current Assignee: Autoliv AB (Autoliv Incorporated)
• Original Assignee: Autoliv AB (Autoliv Incorporated)
• Inventors: Ostin, Thorbjorn
• Granted Patent: US 7,156,025 B2
• Time in Patent Office: Days
• US Class Current: 431/2
• CPC Class Codes: B60R 2021/26094 characterised by fluid flow controlling valves
• CPC Class Codes: B60R 21/2644 using only solid reacting substances, e.g. pellets, powder

Abstract

The present invention relates to a method and a device for making the combustion of a pyrotechnic compostion independent of the ambient temperature when combusting a pyrotechnic composition in a preinflator or combustion chamber (2) incorporating outlets but being otherwise enclosed. As claimed in the present invention this is enabled by controlling the burning pressure of the pyrotechnic composition so that it does not exceed a predetermined value. The characteristic feature of the present invention is that the preinflator (2), in which combustion of the pyrotechnic composition takes place, incorporates a plurality of gas discharge perforations (6-9) or outlets, each of which is initially sealed by a bursting disc or foil seal (10) that is designed to rupture when the said burning pressure in the combustion chamber (2) is exceeded.

Claims

1. A method which, when burning a pyrotechnic composition in a preinflator or combustion chamber (2) with outlets but otherwise enclosed, makes combustion of the pyrotechnic composition independent of the ambient temperature by controlling the burning pressure so that it does not exceed a predetermined value wherein the said preinflator (2) in which combustion of the pyrotechnic composition takes place incorporates a plurality of gas discharge perforations (6-9) or outlets, each of which is initially sealed by a bursting disc or foil seal (10) designed to rupture when the said burning pressure in the combustion chamber (2) is exceeded.

2. A method as claimed in claim 1 wherein the said seals are dimensioned with small variations so that one specific seal always ruptures before another.

3. A method as claimed in claim 1 wherein the gases generated by combustion of the pyrotechnic composition in the preinflator (2) flow via gas discharge perforations into a gas filled pressure vessel (1).

4. A preinflator with a burning rate that is independent of the ambient temperature, which burning rate is controlled by the method claimed in claim 1 wherein the said preinflator embodies a plurality of gas discharge perforations (6-9), each of which is initially sealed by a foil seal (10) or bursting disc with an inherent strength that is predetermined in relation to the desired burning pressure in the preinflator (2).

5. A pyrotechnic composition driven hybrid gas generator which, in accordance with the method claimed in claim 1, has been made functionally independent of the ambient temperature and which is of the type that comprises a combustion chamber or preinflator (2) filled with pyrotechnic composition such that the said preinflator, via a dedicated connection that is initially sealed, can be linked to a pressure vessel (1) filled with gas at overpressure and incorporating a gas discharge outlet (12) that is similarly sealed initially and that is connected to a gas consumer wherein the connection between the preinflator (2) and the pressure vessel (1) comprises a plurality of gas discharge perforations (6-9) that are sealed in initial mode and whose seals are arranged to rupture only when a predetermined overpressure in the preinflator (2) is exceeded, and whereby the sealing of outlet (12) in pressure vessel (1) is also designed to rupture when a predetermined overpressure exceeding the initial pressure in the said pressure vessel is exceeded.

6. A pyrotechnic composition driven hybrid gas generator as claimed in claim 5 wherein the preinflator (2) and the pressure vessel (1) are separated from each other by a dividing wall arranged between them incorporating a plurality of gas discharge perforations (6-9) that are initially sealed by one and the same foil seal (10), the strength of which is calculated to rupture at a predetermined load to expose each perforation.

7. A device as claimed in claim 6 wherein all gas discharge perforations of the preinflator are sealed by one and the same foil seal (10) arranged on one side of the dividing wall separating the preinflator (2) from the pressure vessel (1), and which foil is welded around each gas discharge perforation (6-9) at a distance from the edge of each said perforation that is determined by the area of foil that it is desirable shall be subjected to the internal pressure from the preinflator side and from the pressure vessel side respectively.

8. A pyrotechnic composition driven hybrid gas generator as claimed in claim 5 wherein the said foil seal (10) is welded around the inner edge of the dividing wall (5) as well as along diagonal dividing lines between the gas discharge perforations.

9. A pyrotechnic composition driven hybrid gas generator as claimed in claim 5 wherein the foil (10) is welded at different distances from the edges of the various gas discharge perforations.

10. A method as claimed in claim 2 wherein the gases generated by combustion of the pyrotechnic composition in the preinflator (2) flow via gas discharge perforations into a gas filled pressure vessel (1).

11. A preinflator with a burning rate that is independent of the ambient temperature, which burning rate is controlled by the method claimed in claim 2 wherein the said preinflator embodies a plurality of gas discharge perforations (6-9), each of which is initially sealed by a foil seal (10) or bursting disc with an inherent strength that is predetermined in relation to the desired burning pressure in the preinflator (2).

12. A pyrotechnic composition driven hybrid gas generator which, in accordance with the method claimed in claim 2, has been made functionally independent of the ambient temperature and which is of the type that comprises a combustion chamber or preinflator (2) filled with pyrotechnic composition such that the said preinflator, via a dedicated connection that is initially sealed, can be linked to a pressure vessel (1) filled with gas at overpressure and incorporating a gas discharge outlet (12) that is similarly sealed initially and that is connected to a gas consumer wherein the connection between the preinflator (2) and the pressure vessel (1) comprises a plurality of gas discharge perforations (6-9) that are sealed in initial mode and whose seals are arranged to rupture only when a predetermined overpressure in the preinflator (2) is exceeded, and whereby the sealing of outlet (12) in pressure vessel (1) is also designed to rupture when a predetermined overpressure exceeding the initial pressure in the said pressure vessel is exceeded.

13. A pyrotechnic composition driven hybrid gas generator which, in accordance with the method claimed in claim 3, has been made functionally independent of the ambient temperature and which is of the type that comprises a combustion chamber or preinflator (2) filled with pyrotechnic composition such that the said preinflator, via a dedicated connection that is initially sealed, can be linked to a pressure vessel (1) filled with gas at overpressure and incorporating a gas discharge outlet (12) that is similarly sealed initially and that is connected to a gas consumer wherein the connection between the preinflator (2) and the pressure vessel (1) comprises a plurality of gas discharge perforations (6-9) that are sealed in initial mode and whose seals are arranged to rupture only when a predetermined overpressure in the preinflator (2) is exceeded, and whereby the sealing of outlet (12) in pressure vessel (1) is also designed to rupture when a predetermined overpressure exceeding the initial pressure in the said pressure vessel is exceeded.

14. A pyrotechnic composition driven hybrid gas generator as claimed in claim 6 wherein the said foil seal (10) is welded around the inner edge of the dividing wall (5) as well as along diagonal dividing lines between the gas discharge perforations.

15. A pyrotechnic composition driven hybrid gas generator as claimed in claim 7 wherein the said foil seal (10) is welded around the inner edge of the dividing wall (5) as well as along diagonal dividing lines between the gas discharge perforations.

16. A pyrotechnic composition driven hybrid gas generator as claimed in claim 6 wherein the foil (10) is welded at different distances from the edges of the various gas discharge perforations.

17. A pyrotechnic composition driven hybrid gas generator as claimed in claim 7 wherein the foil (10) is welded at different distances from the edges of the various gas discharge perforations.

18. A pyrotechnic composition driven hybrid gas generator as claimed in claim 8 wherein the foil (10) is welded at different distances from the edges of the various gas discharge perforations.