GB2302169A

GB2302169A - Rupturing the seal of a bottle of compressed gas

Info

Publication number: GB2302169A
Application number: GB9511946A
Authority: GB
Inventors: Torbjorn Skanberg
Original assignee: Autoliv Development AB
Current assignee: Autoliv Development AB
Priority date: 1995-06-13
Filing date: 1995-06-13
Publication date: 1997-01-08
Anticipated expiration: 2015-06-13
Also published as: DE19681465T1; GB9511946D0; GB2302169B; WO1996041732A1

Abstract

A gas supply comprises a bottle 1 of compressed gas with at least one opening 4, 5 formed in the wall of a bottle sealed with a metallic foil 6, 7 across the opening, an element 10 being provided on the exterior of the bottle in engagement with the foil which in response to a signal moves in such a way as to cause a part 20 of the element to tear or cut the foil, permitting gas to escape to inflate, for example, an air-bag. The element 10 may be in the form of a piston movable within a bore 3 by firing a pyrotechinc charge 15. The foil may be ruptured by a pointed flange 19, or a knife blade (24, Figure 3). Alternatively the foil may be glued or soldered (Figure 4) to the piston so that it is torn by the movement of the piston, or a tab attached to both the piston and foil (Figures 5 and 6) which is pulled when the piston moves.

Description

DESCRIPTION OF INVENTION "IMPROVEMENTS IN OR RELATING TO A GAS SUPPLY" THE PRESENT INVENTION relates to a gas supply and more particularly relates to a gas supply intended for use with an air-bag or other safety device in a motor vehicle An air-bag may be provided in a motor vehicle, adapted to be inflated in response to an accident occurring, to provide protection for the driver of the vehicle or a passenger in the vehicle.

Various types of gas supply have been proposed before for use in an air-bag arrangement and some prior art gas supplies comprise a bottle containing compressed gas.

It has been proposed to seal such a gas bottle with a disc of foil, the foil resting against a piston which is contained within a re-entrant part of the gas bottle, the piston initially supporting the foil so that the foil forms a gas-tight seal for the gas bottle. The piston is moved, however, when an accident occurs, typically as a result of the ignition of a pyrotechnic charge. The piston moves away from the foil, and no longer supports the foil. The pressure of gas within the gas bottle then ruptures the foil, thus permitting the gas to escape from the gas bottle and to inflate the air-bag.

An arrangement of this type is disclosed in GB-A2,277,984.

It has been found, however, that if a very thin foil is used, it may be damaged even before the supporting piston is removed. However, if the foil is made to be thicker, it might not break, even when the supporting piston moves, if there has been any leakage of gas from the bottle of compressed gas.

A further arrangement utilising a flexible foil disc is disclosed in WO 93/21042. However, in the teaching of this Specification, a pin is inserted into the bottle to break the foil disc. This is not desirable because the pressure within the bottle might rise or fragile parts inside the bottle might be damaged.

The present invention seeks to provide an improved gas supply.

According to this invention there is provided a gas supply, said gas supply comprising a bottle containing compressed gas, at least one opening formed in the wall of the bottle, a metal foil extending across the opening, the periphery of the foil being secured to the bottle, the foil sealing the opening in a gas-tight manner, an element being provided on the exterior of the bottle, the element being in engagement with the foil, means being provided to move said element in response to a predetermined signal in such a way that the movement of the element causes part of the element in engagement with the foil to tear or cut the foil, thus permitting gas to escape from the bottle of compressed gas.

The gas supply may be connected to supply gas to a safety device, such as an air-bag, within a motor vehicle.

Preferably the said bottle is a metal bottle and the foil has a thickness of less one-fifth of the thickness of the wall of the bottle.

Conveniently the means to move said element comprise a pyrotechnic charge.

Preferably an electric igniter is provided adapted to ignite the pyrotechnic charge in response to a predetermined signal. The signal may be generated by a crash sensor or the like.

In one embodiment the element is initially located adjacent the aperture, part of the foil being pressed against part of the element by the compressed gas within the bottle.

Preferably the element has a further part, located initially adjacent the part against which the foil is pressed, the said further part being brought into contact with the foil on movement of said element. The further part may comprise a point of projection or a projecting knife blade.

Alternatively the said part of the element against which the foil is pressed is provided with a recess, part of the foil being pressed into the recess, the arrangement being such that upon movement of the element, the part of the foil within the recess is torn.

Alternatively the part of the foil that is initially pressed against part of the element by the compressed gas within the bottle is soldered or adhered to the said part of the element.

Preferably the element comprises a piston movable within a cylindrical recess defined by a re-entrant portion of the bottle, the said aperture being formed in the side wall of the re-entrant portion.

In an alternative embodiment the said part of the element comprises a tab adhered or soldered to part of the foil, means being provided connecting the tab to a piston located within a cylinder containing a pyrotechnic charge, means being provided to ignite the pyrotechnic charge in response to a predetermined signal. The predetermined signal may be generated by a crash sensor or the like.

In one embodiment the said cylinder is secured to the exterior of the bottle, the piston moving in a direction parallel to the exterior of the bottle.

In an alternative embodiment the cylinder is located to extend perpendicularly to the wall of the bottle, the piston moving away from the bottle, the tab being connected to the piston by means of a wire extending from the tab, to the piston.

Preferably the wire extends beyond the piston to a free end portion thereof which is secured to the wall of the gas bottle.

In order that the invention may be more readily understood, and so that further features thereof may be appreciated, the invention will now be described, by way of example, with reference to the accompanying drawings in which FIGURE 1 is a diagrammatic sectional view of parts of one embodiment of the invention, FIGURE 2 is a view illustrating part of an arrangement, similar to that of Figure 1, but of a modified embodiment of the invention, FIGURE 3 is a view corresponding to Figure 2 illustrating another modified form of the invention, FIGURE 4 is a view corresponding to Figure 2 illustrating yet another modified form of the invention, FIGURE 5 is a sectional view of part of yet another embodiment of the invention, FIGURE 6 is a perspective view of part of yet another embodiment of the invention, and Referring initially to Figure 1 of the accompanying drawings, a metal bottle 1 containing compressed gas is provided with a re-entrant portion 2 which defines an inwardly directed cylindrical bore 3. Two diametrically opposed apertures 4,5 are formed in the wall of the reentrant portion 2 defining the bore 3. Each of the apertures 4,5 is sealed with a sheet of foil 6,7, the periphery of each sheet being secured to the inner wall of the gas bottle by means of solder or adhesive 8. The sheets of foil may have a thickness which is less than onefifth of the thickness of the bottle wall.

A piston 10 is provided which is slidable within the bore 3. The piston 10 can thus move along the wall that defines the apertures 4,5, moving in a direction parallel to the wall. One end 11 of the piston is comprised of a disc 11, that end being directed towards the closed end of the bore 3. The other end of the piston is provided with a bore 12 which extends into the piston and which receives one end of a tube 13, the other end of which is secured to a mounting plate 14 which is spaced from the bottle 1. A pyrotechnic charge 15 is received within the tube 13 and an electric igniter 16 is provided within the pyrotechnic charge.

The piston has a side wall 17 which defines an external peripheral annular recess 18 which entirely surrounds the piston. The sheets of foil 6 and 7 are pressed into engagement with the base of the annular recess 18 by the pressure of gas within the bottle. The sheets of foil they extend out of the interior of the gas bottle 1, through the apertures 4,5, to the exterior of the gas bottle 1.

At the end of the piston closest to the support plate 14, a radially outwardly extending flange 19 is provided. The outer periphery of the flange 19 has a greater axial thickness than the inner part of the flange 19, and consequently, the part of the flange 19 which is adjacent the foil 6 and 7 is pointed 20.

In operation of the device illustrated in Figure 1, in the event that an accident occurs, an electric current flows through the electric igniter 16, igniting the pyrotechnic charge 15. Hot gas under pressure is thus supplied to the interior of the tube 13, consequently moving the piston 10 towards the left as shown in Figure 1.

The pointed part 20 of the flange 19 thus engages the parts of the sheets of foil 6 and 7 initially engaging the annular recesses 18, thus penetrating and tearing the sheets of foil and permitting gas to flow out of the bottle 1 through a flow passage 21 provided for that purpose between the bottle 1 and the support 14. The flow passage 21 leads to the interior of an air-bag 22 that is to be inflated.

Figure 2 illustrates a slightly modified embodiment of the invention where the outer side wall 17 of the piston 10 is provided with an annular recess 23 which has a smaller width than the width of the part of the sheet of foil 7 that projects outwardly through the aperture 4.

Part of the sheet of foil in engagement with the piston 10 thus extends into the recess 23 by virtue of the pressure of the compressed gas within the bottle 1. The rest of the sheet of foil engages the outer side wall 17 of the piston 10. When the piston 10 moves, the parts of the piston 10 that define the recess 22 engage and tear the part of the foil that is present within the recess 23, thus permitting gas to escape from the bottle 1.

Figure 3 illustrates a further modified embodiment of the invention where the side wall 17 of the piston carries a projecting knife blade 24 at a position initially adjacent the sheet of foil 7. Part of the side wall 17 of the piston initially engages the foil. When the piston 10 moves the knife blade 24 will move from its position adjacent the foil and will engage the foil 7 thus cutting or tearing the foil.

Figure 4 illustrates a further modified embodiment of the invention in which the sheet of foil 7 which engages the piston 10 is actually secured by means of glue or solder 25 to the outer surface of the wall 17 of the piston 10. When the piston moves, as a result of the activation of a pyrotechnic charge, the foil 7 is torn, the part of the foil adhered to the piston being torn away from the rest of the foil, thus permitting gas to escape from the bottle.

Figure 5 illustrates a modified embodiment of the invention. A metal gas bottle 30 has an aperture 31 in the side wall which is sealed by a metal foil 32 which has a thickness less than one-fifth of the thickness of the wall of the bottle. A part 33 of the metal foil extends through the aperture to the exterior of the bottle 30. The periphery of the metal foil is secured by solder or adhesive to the interior of the bottle. A tab 34 which is soldered or adhered to the part 33 of the sheet of foil 32 projecting through the aperture 31. The tab 34 is connected by means of a wire 35 to a piston 36. The piston 36 is contained within a cylinder 37, the cylinder 37 also containing a pyrotechnic charge 38. The axis of the cylinder 37 is parallel with the wall of the bottle 30. The cylinder 37 is secured to the wall of the bottle 30.The arrangement is such that on ignition of the pyrotechnic charge 43, in response to an accident occurring, the piston 36 moves away from the foil in a direction parallel to the wall of the bottle, consequently applying a force to the tab 34 which is sufficient to tear the foil 32. The pyrotechnic charge 38 may be ignited by an appropriate electric igniter similar to the igniter 16.

Figure 6 illustrates a further modified embodiment of the invention which is similar to that of Figure 5. The common components will not be re-described. The wire 35 engages a piston 39, but has a free end secured 40 to the exterior of the gas bottle 30. The piston 39 is contained within a cylinder 41 which also contains a pyrotechnic charge 42. The cylinder 41 has its axis perpendicular to the wall of the bottle 30, and is secured to the wall of the bottle 30. On ignition of the pyrotechnic charge 42, the piston 39 tends to move away from the gas bottle 30, thus applying a tension to the wire 35 which causes the tab 39 to tear the sheet of foil 32.

In the described embodiments of the invention, the sheet of foil may have a thickness which is less than onefifth of the thickness of the bottle wall. When the sheet of foil is torn, cut or ripped, thee compressed gas within the bottle may flow out of the bottle to inflate an airbag.

The foil may, especially in the embodiments of Figures 5 and 6 be sufficiently thick to withstand the pressure of gas within the bottle without external support.

However, the external support provided by the piston of the embodiments of Figures 1 to 3 may prevent an un-intentional rupturing of the foil caused by long term stress. A gas supply as described may be provided in a motor vehicle, and may not be activated for a long period of time, typically in excess of ten years, but should be ready to be activated at any instant during that period. A relatively thin foil may be stressed and may deteriorate if it is unsupported but subjected to a high pressure for a prolonged period of time.

Claims

CLAIMS:

1. A gas supply, said gas supply comprising a bottle containing compressed gas, at least one opening formed in the wall of the bottle, a metal foil extending across the opening, the periphery of the foil being secured to the bottle, the foil sealing the opening in a gas-tight manner, an element being provided on the exterior of the bottle, the element being in engagement with the foil, means being provided to move said element in response to a predetermined signal in such a way that the movement of the element causes part of the element in engagement with the foil to tear or cut the foil, thus permitting gas to escape from the bottle of compressed gas.

2. A gas supply according to Claim 1 wherein the gas supply is connected to supply gas to a safety device within a motor vehicle.

3. A gas supply according to Claim 2 wherein the gas supply is adapted to supply gas to an air-bag within the motor vehicle.

4. A gas supply according to any one of the preceding Claims wherein the said bottle is a metal bottle and the foil has a thickness of less one-fifth of the thickness of the wall of the bottle.

5. A gas supply according to any one of the preceding Claims wherein the means to move said element comprise a pyrotechnic charge.

6. A gas supply according to Claim 5 wherein an electric igniter is provided adapted to ignite the pyrotechnic charge in response to a predetermined signal.

7. A gas supply according to any one of the preceding Claims wherein the element is initially located adjacent the aperture, part of the foil being pressed against part of the element by the compressed gas within the bottle.

8. A gas supply according to Claim 7 wherein the element has a further part, located initially adjacent the part against which the foil is pressed, the said further part being brought into contact with the foil on movement of said element.

9. A gas supply according to Claim 8 wherein the further part comprises a pointed projection.

10. A gas supply according to Claim 8 wherein the further part comprises a projecting knife blade.

11. A gas supply according to Claim 7 wherein the said part of the element against which the foil is pressed is provided with a recess, part of the foil being pressed into the recess, the arrangement being such that upon movement of the element, the part of the foil within the recess is torn.

12. A gas supply according to Claim 7 wherein the part of the foil that is initially pressed against part of the element by the compressed gas within the bottle is soldered or adhered to the said part of the element.

13. A gas supply according to any one of Claims 1 to 12 wherein the element comprises a piston movable within a cylindrical recess defined by a re-entrant portion of the bottle, the said aperture being formed in the side wall of the re-entrant portion.

14. A gas supply according to any one of Claims 1 to 4 wherein the said part of the element comprises a tab adhered or soldered to part of the foil, means being provided connecting the tab to a piston located within a cylinder containing a pyrotechnic charge, means being provided to ignite the pyrotechnic charge in response to a predetermined signal.

15. A gas supply according to Claim 14 wherein the said cylinder is secured to the exterior of the bottle, the piston moving in a direction parallel to the exterior of the bottle.

16. A gas supply according to Claim 16 wherein the cylinder is located to extend perpendicularly to the wall of the bottle, the piston moving away from the bottle, the tab being connected to the piston by means of a wire extending from the tab, to the piston.

17. A gas supply according to Claim wherein the wire extends beyond the piston to a free end portion thereof which is secured to the wall of the gas bottle.

18. A gas supply substantially as herein described with reference to and as shown in Figure 1 of the accompanying drawings.

19. A gas supply substantially as herein described with reference to and as shown in Figure 2 of the accompanying drawings.

20. A gas supply substantially as herein described with reference to and as shown in Figure 3 of the accompanying drawings.

21. A gas supply substantially as herein described with reference to and as shown in Figure 4 of the accompanying drawings.

22. A gas supply substantially as herein described with reference to and as shown in Figure 5 of the accompanying drawings.

23. A gas supply substantially as herein described with reference to and as shown in Figure 6 of the accompanying drawings.