GB2404634A

GB2404634A - Airbag comprising an outer and an inner bag

Info

Publication number: GB2404634A
Application number: GB0318433A
Authority: GB
Inventors: Gilles Garret; Anders Astrom; David Stow
Original assignee: Autoliv Development AB
Current assignee: Autoliv Development AB
Priority date: 2003-08-06
Filing date: 2003-08-06
Publication date: 2005-02-09
Anticipated expiration: 2023-08-06
Also published as: GB0318433D0; GB2404634B

Abstract

A side air-bag (5) is to be used as a safety device in a motor vehicle to provide protection to seat occupants in the event of a crash situation. The side air-bag (5) comprises an outer bag (7) and an inner bag (12), the inner bag (12) being located within the outer bag (7). A gas generator (10) is provided in order to supply gas to the inner bag (12), and there is at least one gas flow path (16) extending from the inner bag (12) to the outer bag (6).

Description

DESCRIPTION OF INVENTION

"IMPROVEMENTS IN OR RELATING TO AN AIR-BAG" THE PRESENT INVENTION relates to an air-bag, and more particularly relates to a side air-bag. It has been proposed to mount a side air-bag in a vehicle to provide protection for an occupant of the vehicle in the event that an accident, particularly a side impact, should occur. Such a side air-bag is typically mounted in position either within a side part of the back-rest of the seat or in part of the vehicle adjacent the seat, and is configured so that, when inflated, the air-bag is located between the occupant of the seat and the side of the vehicle. In a side impact situation it is important that the air-bag is inflated, at least to a sufficient degree to provide effective protection for the seat occupant, within an extremely brief period of time. Various types of side air-bag have been proposed previously, but the present invention seeks to provide an improved side air-bag. According to this invention there is provided a side air-bag, the side airbag comprising an outer bag, and an inner bag located within the outer air-bag, there being a gas generator to supply gas to the inner bag, there being a gas flow path extending from the inner bag to the outer bag. Preferably the inner bag is a coated bag. Advantageously the outer bag is an un-coated bag. Conveniently the inner bag has a substantial horizontal extent at its lower end, and a lesser horizontal extent at an intermediate position located above its lower end. Preferably the diameter of the inner bag is, on average, between 100 and 200 millimetres. Advantageously the diameter of the inner bag, on average, is substantially 120 millimetres. Conveniently on inflation, the working pressure within the inner bag is in the range of 1 to 3 bars, and the working pressure in the outer bag is substantially in the range of 0.4 to 0.7 bars. Preferably the volume of the inner bag is between one-third and twothirds of the volume of the outer bag. Advantageously, the volume of the inner bag is between one-half and two-thirds of the volume of the outer bag. In one embodiment the inner bag is of substantially frusto-conical form. Conveniently a gas generator of elongate form is mounted within the inner bag, the leading edge of the inner bag, when inflated, making an angle a with the axis of the gas generator, the angle a being between 0 and 30[deg]. In another embodiment the outer bag is divided into a plurality of chambers. Preferably the outer bag is divided into three chambers. Conveniently the outer air-bag is divided into chambers by at least one seam extension which extends across parts of the outer bag and which contacts, when inflated, the inner bag, the inner bag having gas flow apertures which communicate with each of the chambers. Advantageously the inner bag is of substantially cylindrical or frustoconical form. In a further embodiment the inner air-bag is of substantially "C"-shaped form having upper and lower extensions which extend into the upper-most and lower-most chambers. In another embodiment the air-bag is divided into two chambers by a single horizontal extension of a peripheral seam, the inner air-bag being substantially "L"-shaped, with part of the inner air-bag of substantial horizontal extent being maintained within a lower-most chamber, and an upper part of the inner air-bag of lesser horizontal extent being contained within an upper chamber. Conveniently each chamber, when the air-bag is inflated, has a different respective pressure. In a further embodiment the inner bag is of "donut", torroidal or annular form. Preferably the outer bag is provided with a seam located within a central part of the inner bag. 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 side-view of a vehicle seat showing an airbag in accordance with the invention in the inflated state, FIGURE 1A is a sectional view taken on the line AA of Figure 1, FIGURE 2 is a diagrammatic view of an alternative form of air-bag, FIGURE 3 is a diagrammatic view of yet further alternative form of airbag, FIGURE 3A is a plan view of a fabric element used to form part of the air-bag shown in Figure 3, FIGURE 4 is a diagrammatic view of another form of air-bag, FIGURE 4A is a plan view of a fabric element used to form part of the air-bag of Figure 4, and FIGURE 5 is a diagrammatic view of another form of air-bag. Referring initially to Figure 1 of the accompanying drawings, a vehicle seat 1 is illustrated, the seat having a squab 2, a back-rest 3 and a head-rest 4. A side air-bag 5 is illustrated, the side air-bag being mounted in position at a side part of the back-rest 3 so that, when the side air-bag is inflated (the condition shown in Figure 1) the air-bag 5 is located adjacent the side of the occupant of the seat, between the seat occupant and the side of the vehicle. The air-bag 5 has an outer bag 6. The outer bag 6 is formed from two super-imposed layers of fabric 7, 8, the edges of the layers of fabric being interconnected by means of a peripheral seam 9. Contained within the outer air-bag 6 is a gas generator 10. The gas generator 10 is of cylindrical form and has an inclined axis 11. The inclination of the axis 11 is equivalent to the inclination of the front face of the back-rest 3 of the vehicle seat. Contained within the outer bag 6, and surrounding the gas generator 10 is an inner bag 12. The inner bag 12 may be formed from a single sheet of fabric, which is rolled to have a generally tubular form, and which is sealed with a single seam 13. The upper-most part of the inner bag 12 may be trapped within a part 14 of the peripheral seam 9 of the outer bag 6 and similarly the lower part of the inner bag 12 may be trapped within part 15 of the peripheral seam 9 of the outer bag 6 so that the upper and lower ends of the inner bag are retained firmly in position relative to the outer bag 6. The inner bag is not of uniform section along its length, but has a greater diameter, and thus a greater horizontal extent, at its lower end than in a central region, and has even a lesser diameter, and thus a lesser horizontal extent in its upper-most region. The inner bag 12 is thus of an almost frusto-conical form. The inner bag 12 has three gas flow apertures 16, 17, 18 which provide a gas flow path from the inner bag 12 to the outer bag 6. The inner bag has a volume between one-third and two-thirds, and most advantageously between one-third and two-thirds of the volume of the outer bag. The inner bag 12 may be formed of coated fabric, whilst the outer bag 6 may be formed of un-coated fabric. Coated fabric is better able to withstand an aggressive hot gas flow, such as the gas flow from the gas generator 10. The gas from the gas generator will flow through the apertures 16, 17 and 18 into the outer bag 6, and at that stage the flow of gas will be much less aggressive and the temperature of the gas will have reduced, meaning that it is unnecessary to coat the outer air-bag 6. The fact that the outer bag 6 is un-coated means that some gas will permeate through the fabric of the bag, thus providing a desirable "venting" function to enable the outer bag to yield appropriately when force is applied to the bag by a seat occupant. The leading edge of the inner bag 12 makes an angle a the axis 11 of the gas generator 10. The angle a is preferably between 0[deg] and 30[deg]. The average diameter of the inner bag is preferably in the range of 100 to 200 millimetres, most preferably being around 120 millimetres. This enables the air-bag to be inflated in such a way that a working pressure in the range of 1 to 3 bars is achieved within the inner bag 12, whilst a working pressure in the range of 0.4 to 0.7 bars is achieved within the outer bag 6. When the air-bag 5 is deployed, initially gas from the gas generator fills the inner bag 12. Because the inner bag 12 has a substantial horizontal extent in its lower region, the inflated inner bag will occupy a space adjacent the hips or pelvis of a seat occupant, and will also occupy space adjacent the thorax of a seat occupant. Because the inner bag 12 has a relatively small volume it will become inflated relatively quickly, meaning that, in an extremely "fast" accident situation, the inner bag 12 at least will be in a position to provide some protection for a seat occupant as swiftly as possible after the accident has been sensed. Subsequently the outer bag 6 becomes inflated, to provide a greater degree of protection. Due to the relatively small volume of the inner air-bag 12, and the relatively high working pressure within it, the inner air-bag 12 deploys very swiftly and becomes very stiff after inflated so that it becomes stabilised in its inflated position. Within the stated ranges of dimensions and working pressure, the side air-bag arrangement can be adjusted to the required conditions for each vehicle in which it is to be installed. Figure 2 illustrates an air-bag 20 which forms a second embodiment of the invention. The air-bag 20 has an outer un-coated bag 21, again formed of two super-imposed layers of fabric 22, 23 having their edges interconnected by a peripheral seam 24. The seam 24 is provided with two generally horizontally extending extensions 25, 26 which, as will become clear from the following description, serves to divide part of the air-bag into three chambers, namely a pelvic chamber 27, a thorax chamber 28 and a shoulder-and-head chamber 29. A gas generator 30 of elongate form is provided within the air-bag 20 and, surrounding the gas generator 30 is a generally cylindrical inner bag 31. The inner bag 31 is formed in a manner equivalent to that of the inner airbag 12 of the embodiment described with reference to Figures 1 and 1A. The inner bag 31 has one aperture 32 which communicates with the pelvic chamber 27, two apertures 33, 34 which communicate with the thorax chamber 28 and one aperture 35 which communicates with the shoulder chamber 29. The apertures form gas flow paths. It is to be understood that the upper and lower ends of the inner bag 31 are retained by parts of the peripheral seam 24 in a manner equivalent to that described above with reference to the embodiment of Figures 1 and 1A. When the inner bag 31 is inflated on deployment of the air-bag 20, the inner bag contacts the inner-most ends of the extensions 25, 26 thus effectively sealing the pelvic chamber 27, the thorax chamber 28 and the shoulder chamber 29. Because the three chambers are sealed the chambers only receive gas through the apertures 32 to 35 which communicate with each respective chamber and there is no inter-flow of gas between the chambers. On deployment of the air-bag 20 shown in Figure 2 initially the inner bag 31 will become inflated, thus being in position to provide a degree of protection to a seat occupant. Once the inner bag is inflated the three chambers 27, 28, 29 will become inflated and because the chambers are effectively isolated from each other, the chambers may each become inflated to a different pressure. Thus, for example, the pressure in the pelvic chamber 27 may be much greater than the pressure provided in the thorax chamber 28. Figure 3 illustrates yet another embodiment of the invention in which an outer bag 40 which is formed from two layers of fabric 41, 42 having their edges interconnected by means of a peripheral seam 43, the seam having a horizontal extending internal extension 44, contains a cylindrical gas generator 45. The cylindrical gas generator 45 is contained within a generally "L"-shaped inner bag 46. The inner bag 46 is formed from a single element of fabric 47, the element of fabric being substantially symmetrical about a notional fold-line 48, the part of the fabric to each side of the fold-line being substantially "L"-shape. The inner bag is provided with mounting apertures 49 to accommodate mounting studs provided on the gas generator 45.The inner bag 46 thus presents a lower portion 50 of substantial horizontal extent which, when the air-bag is inflated, extends to substantially fill the lower-most part of the outer air-bag 41 located beneath the horizontal extension 44 of the peripheral seam 43. The inner bag 46 also presents an upwardly extending region which fills part of the outer bag 40 located above the extension 44 of the peripheral seam 43. This upwardly extending part 51 of the air-bag is provided with a single gas flow aperture 52. Again the inner bag 46 may be coated whilst the outer bag 41 is uncoated. On deployment of the air-bag shown in Figure 3 and 3A, initially the inner bag 46 will become inflated, with the lower-most portion 50 extending forwardly to lie adjacent the hips or pelvis of a seat occupant, and the upwardly extending portion 51 lying adjacent the thorax of the seat occupant. Subsequently gas will flow from the single aperture 52 into the part of the outer bag 41 lying above the horizontal projection 44 formed on the peripheral seal 43. The air-bag will thus become fully deployed. It should also be noted that in this embodiment, gas is allowed to travel between the upper and lower portions of the outer air-bag 40, past the internal extension 44. Figure 4 illustrates another embodiment of the invention in which an outer bag 60 which is formed from super-imposed fabric layers 61, 62 having their edges interconnected by a peripheral seam 63. The seam 63 has two spaced-apart inwardly extending extensions 64, 65. The air-bag contains a generally cylindrical gas generator 66. The gas generator is located within an inner bag 67 which is of generally "C"-shape. The inner bag 67 is formed from a single element 68 of fabric. The element 68 is symmetrical about a foldline 69 and is folded about the fold-line with the edges of two symmetrical parts being interconnected by a seam to form the inner bag. The inner bag is provided with apertures 70, 71 to accommodate mounting brackets provided on the gas generator 66. The inner bag 67 is so configured that when the inner bag is inflated, a first part 72 of the inner bag which has a substantial horizontal extent substantially fills the chamber defined beneath the lower-most horizontal extension 64 of the peripheral seam 63, that chamber being a hip or pelvic chamber. A generally cylindrical intermediate part 73 of the inner air-bag extends across an intermediate or thorax chamber defined between the two horizontal extensions 64 and 65 of the peripheral seam, and again an enlarged upper region 74 of the inner air-bag substantially fills an upper-most chamber defined above the horizontal extension 65 of the peripheral seam. The inner bag 67 is provided with one gas flow aperture 75 communicating with the lower-most chamber defined beneath the horizontal extension 64, two gas flow apertures 76, 77 communicating with the intermediate chamber defined between the two horizontal extensions 64, 65 and a single gas flow aperture 78 communicating with the upper-most chamber above the horizontal extension 65. In this embodiment when the air-bag is deployed, again the inner bag becomes fully inflated initially, and subsequently gas flows through the apertures into the separate chambers, inflating the separate chambers to a desired pressure. As can be seen from Figure 4 the inner-most ends of the horizontal extensions 64, 65 effect contact with the intermediate part 73 of the inner bag, thus effectively sealing the three chambers from each other, allowing the three chambers to be inflated at different pressures. Turning finally to Figure 5 of the accompanying drawings, an outer airbag 80 is provided formed from two super-imposed layers of fabric 81, 82 interconnected by means of a peripheral seam 83, and also connected by means of a substantially centrally located horizontally extending "I" form seam 84. Contained within the air-bag is a gas generator 85. The gas generator 85 is contained within an inner bag 86, the inner bag being of "donut" or torroidal or annular form. The inner bag 86 is provided with two gas flow apertures 87, 88, the aperture 87 being directed towards a space located beneath the horizontal I seam 85 and the aperture 88 being directed to a space located above the horizontal I seam 84. In this embodiment the lower-most part of the inner air-bag has a substantial horizontal extent, whereas an intermediate part of the inner air-bag has a much lesser horizontal extent. The inner bag, when initially inflated, will have parts thereof lying adjacent the hips of the seat occupant and parts lying adjacent the thorax of the seat occupant, and will thus be in a position, very shortly after an accident has been sensed, to provide a degree of protection to a seat occupant. In all of the embodiments the relative volumes of the bags, and the pressures on inflation are as described with reference to Figure 1. In the present Specification "comprises" means "includes or consists of' and "comprising" means "including or consisting of'. The features disclosed in the foregoing description, or the following Claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

CLAIMS:

1. A side air-bag, the side air-bag comprising an outer bag, and an inner bag located within the outer air-bag, there being a gas generator to supply gas to the inner bag, there being a gas flow path extending from the inner bag to the outer bag.

2. An air-bag according to Claim 1 wherein the inner bag is a coated bag.

3. An air-bag according to Claim 1 or Claim 2 wherein the outer bag is an un-coated bag.

4. An air-bag according to any one of the preceding Claims wherein the inner bag has a substantial horizontal extent at its lower end, and a lesser horizontal extent at an intermediate position located above its lower end.

5. An air-bag according to any one of the preceding Claims wherein the diameter of the inner bag is, on average, between 100 and 200 millimetres.

6. An air-bag according to Claim 5 wherein the diameter of the inner bag, on average, is substantially 120 millimetres.

7. An air-bag according to any one of the preceding Claims wherein, on inflation, the working pressure within the inner bag is in the range of 1 to 3 bars, and the working pressure in the outer bag is substantially in the range of 0.4 to 0.7 bars.

8. An air-bag according to any one of the preceding Claims wherein the volume of the inner bag is between one-third and two-thirds of the volume of the outer bag.

9. An air-bag according to any one of the preceding claims wherein the volume of the inner bag is between one-half and two-thirds of the volume of the outer bag.

10. An air-bag according to any one of the preceding Claims wherein the inner bag is of substantially frusto-conical form.

11. An air-bag according to Claim 10 wherein a gas generator of elongate form is mounted within the inner bag, the leading edge of the inner bag, when inflated, making an angle a with the axis of the gas generator, the angle a being between 0 and 30[deg].

12. An air-bag according to any one of Claims 1 to 9 wherein the outer bag is divided into a plurality of chambers.

13. An air-bag according to Claim 12 wherein the outer bag is divided into three chambers.

14. An air-bag according to Claim 12 or 13 wherein the outer air-bag is divided into chambers by at least one seam extension which extends across parts of the outer bag and which contacts, when inflated, the inner bag, the inner bag having gas flow apertures which communicate with each of the chambers.

15. An air-bag according to Claim 14 wherein the inner bag is of substantially cylindrical or frusto-conical form.

16. An air-bag according to Claim 14 wherein the inner air-bag is of substantially "C"-shaped form having upper and lower extensions which extend into the upper-most and lower-most chambers.

17. An air-bag according to Claim 14 wherein the air-bag is divided into two chambers by a single horizontal extension of a peripheral seam, the inner airbag being substantially "L"-shaped, with part of the inner air-bag of substantial horizontal extent being maintained within a lower-most chamber, and an upper part of the inner air-bag of lesser horizontal extent being contained within an upper chamber.

18. An air-bag according to any one of Claims 12 to 17 wherein each chamber, when the air-bag is inflated, has a different respective pressure.

19. An air-bag according to any one of Claims 1 to 9 wherein the inner bag is of "donut", torroidal or annular form.

20. An air-bag according to Claim 19 wherein the outer bag is provided with a seam located within a central part of the inner bag.

21. An air-bag substantially as herein described with reference to and as shown in Figures 1 and 1A of the accompanying drawings.

22. An air-bag substantially as herein described with reference to and as shown in Figure 2 of the accompanying drawings.

23. An air-bag substantially as herein described with reference to and as shown in Figures 3 and 3A of the accompanying drawings.

24. An air-bag substantially as herein described with reference to and as shown in Figures 4 and 4A of the accompanying drawings.

25. An air-bag substantially as herein described with reference to and as shown in Figure 5 of the accompanying drawings.

26. Any novel feature or combination of features disclosed herein.