GB2421223A

GB2421223A - Air-bag inflator assembly with gas deflector

Info

Publication number: GB2421223A
Application number: GB0427850A
Authority: GB
Inventors: Jorg Knoblich; Rainer Bichler
Original assignee: Autoliv Development AB
Current assignee: Autoliv Development AB
Priority date: 2004-12-20
Filing date: 2004-12-20
Publication date: 2006-06-21
Also published as: GB0427850D0

Abstract

A safety device for a motor vehicle which incorporates a housing (1) which is of a plastics material. The housing (1) defines a plate (2) that has a central aperture (3). An inflator (5) is mounted to the plate (2), so that part of the inflator (5) extends through the aperture (3). The throat (11) of an air-bag (10) is also mounted to the plate (2), so that the throat (11) is fixed to the plate (2) around the central aperture (3). As the housing (1) is of plastic, the plate (2) is relatively thick compared to a conventional metal housing which means that when the inflator (5) is mounted to the plate (2) outlet apertures (9) of the inflator (5) are positioned adjacent the part of the throat (11) of the air-bag (10) which is attached to the plate (2). A deflector (16) is formed integrally with the plate (2), and the deflector (16) provides an upstanding wall which immediately surrounds the aperture (3) in the plate (2). The deflector (16) deflects gas passing out from the outlet apertures (9) away from the part of the throat (11) of the air-bag 10 which is attached to the plate (2).

Description

DESCRIPTION OF INVENTION

"IMPROVEMENTS IN OR RELATING TO A SAFETY DEVICE" THE PRESENT INVENTION relates to a safety device, and more particularly relates to a safety device to protect the driver of a motor vehicle. Previously proposed safety devices for protecting the driver of a vehicle comprise an inflator, which is configured to be actuated in the event that a crash situation occurs, and an air-bag to be inflated by the inflator. The inflator and the air-bag are usually mounted in a housing, with the housing being located in a central part of the vehicle steering wheel. The air-bag, when inflated, is immediately in front of the driver. Inflators which are commonly used in safety devices of this type incorporate a pyrotechnic material which, when ignited, burns to produce a volume of gas to inflate the air-bag. The gas is usually at a high temperature and is expelled rapidly from the inflator as a hot jet. This hot jet of gas is aggressive and potentially very destructive. It is important that this aggressive jet of gas is not directed immediately onto the material of an air-bag, in such a way as to damage the air-bag. In Figure 1 of the accompanying drawings, a prior proposed safety device has a housing 1 which is of metal. The housing 1 has an internal plate 2. A central aperture 3 is formed in the plate 2 and a plurality of mounting holes 4 surround the central aperture 3. An inflator 5 is provided to be mounted on the housing 1. The inflator 5 is of a conventional design and has a main cylindrical body 6, with a flange 7 that extends radially outwardly from the side wall of the cylindrical body 6. The flange 7 has mounting apertures 8 corresponding to the mounting holes 4. Gas outlet apertures 9 are formed in the side wall of the cylindrical body 6 of the inflator 5 at a position above the flange 7, to allow gas to escape from within the inflator 5. The inflator 5 is mounted to the plate 2 by inserting part of the main cylindrical body 6 through the central aperture 3, and engaging the upper side of the flange 7 with the lower side of the plate 2, with the mounting apertures 8 in the flange 7 aligned with the mounting holes 4 in the plate 2. An air-bag 10 is provisioned which has a throat 11. The throat 11 is located above the plate 2, so that the throat 11 engages the upper side of the plate 2 and surrounds the central aperture 3. The throat 11 of the air-bag 10 incorporates a plurality of securing apertures 12 which, when the throat 11 is located above the plate 2, are aligned with the mounting holes 4 in the plate 2. A retainer ring 13 is situated within the interior of the air-bag 10, and the retainer ring 13 is located above the part of the throat 11 which engages the plate 2. The retainer ring has a plurality of mounting apertures 14 which, when the retainer ring 13 is located above the throat 11, are aligned with the securing apertures 12 in the throat 11. A plurality of pegs 15 are inserted through the mounting apertures 8 in the flange 7, the mounting holes 4 in the plate 2, the securing apertures 12 in the throat 11 and the mounting apertures 14 in the retainer ring 13 which are all co-aligned. The pegs 15 have an enlarged head at each end, and hold the retainer ring 13 and the flange 7 tightly against the plate 2. The throat 11 of the air-bag 10 is trapped between the retainer ring 13 and the plate 2, and a substantially gas-tight seal is formed between the throat 11 and the plate 2. As the plate 2 of the housing 1 is made of metal, which is a strong material, the plate 2 may be thin. This means that, when the inflator 5 is mounted to the housing 1, the outlet apertures 9 of the inflator 5 are positioned above the position where the throat 11 of the air-bag 10 is trapped between the retainer ring 13 and the plate 2. Therefore, hot gas which is produced by the inflator 5 is directed into the air-bag 10 at a position above the throat 11, and not directed immediately onto the part of the throat 11 of the air-bag 10 which is trapped between the retainer ring 13 and the plate 2.

The present invention seeks to provide an improved safety device. According to the present invention, there is provided a safety device comprising a housing which incorporates a plate with an aperture; an air-bag, at least part of the air-bag being attached to the plate; and an inflator, the inflator being mounted to the plate with at least part of the inflator extending through the aperture, the inflator having at least one gas outlet which is adjacent the part of the air-bag which is attached to the plate, the safety device further comprising a deflector which is carried by the plate, at least part of the deflector being positioned between the at least one outlet aperture of the inflator and the part of the air-bag which is attached to the plate, to deflect gas passing out from the at least one outlet aperture away from the part of the air-bag which is attached to the plate. In one embodiment the housing is of plastic. In an alternative embodiment the deflector is formed integrally with the said plate. Preferably the deflector is a separate component mounted to the said plate. Conveniently the deflector is at least partly of a different material to the material of the plate. Advantageously the deflector defines an upstanding wall which surrounds the aperture in the plate. Preferably said wall has an inner face which diverges away from the aperture. Conveniently the inflator incorporates a flange and the flange is attached to one side of the plate. Advantageously the housing incorporates mounting hooks, so that the housing may be mounted to part of a motor vehicle. 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 part of a prior proposed safety device, which has a metal housing, FIGURE 2 is a diagrammatic sectional view of part of a safety device in accordance with a preferred embodiment of the invention, which has a plastic housing, FIGURE 3 is a diagrammatic perspective view from above of the housing of Figure 2, which has an integrally formed deflector, FIGURE 4 is a view corresponding to Figure 3, with an inflator being mounted to the housing and retained in position by a retainer ring, and FIGURE 5 is a diagrammatic sectional view of part of a safety device in accordance with an alternative embodiment of the invention,which has a deflector which is a separate component to the housing. Referring now to Figures 2 to 4, a safety device in accordance with a preferred embodiment of the invention incorporates many of the same parts as the prior proposed safety device seen in Figure 1. Therefore, the same reference numerals will be used in the following description for parts of the preferred embodiment of the invention which correspond to parts of the prior proposed safety device of Figure 1, and these parts will not be re-described. A safety device in accordance with the preferred embodiment of the invention has a housing 1 which is of a plastics material. It is desirable to make the housing 1 of a plastics material, as plastic is often cheaper and easier to work than metal. A housing of a plastics material may also be lighter in weight than a housing of metal. Therefore, in the preferred embodiment of the invention the plate 2 is of a plastics material. Safety devices of this type usually have to be able to withstand certain forces which may be exerted on their housing. If the housing 1 is of a plastics material, the walls of the housing and the plate 2 need to be thicker than the walls and plate 2 of a housing 1 which is of metal, in order to make the plastic housing as strong as the metal housing. Therefore, the plate 2 of the preferred embodiment of the invention which is of plastic is considerably thicker than the metal plate 2 of the prior proposed safety device of Figure 1. It is desirable to incorporate the same inflator 5 in the safety device of the preferred embodiment of the invention as previously used with the metal housing. Thus a single stock of inflators may be used, regardless of whether the housings are of metal or of plastics. For some vehicles it may be essential to use a metal housing. However, if the inflator 5 as used in the prior art arrangement is simply mounted to the relatively thick plastic plate 2, in the conventional way, as described above, the outlet apertures 9 of the inflator 5 become aligned with the part of the throat 11 of the air-bag 10 which is trapped between the retainer ring 13 and the plate 2. This would mean that gas which passes out from the outlet apertures 9 is automatically directed towards the edge of the throat 11 of the air-bag 10. Consequently the housing 1, of a safety device of the described embodiment of the invention has a deflector 16 which is carried by the plate 2. In the preferred embodiment the deflector 16 is formed integrally with the plate 2, and is formed from the same plastics material which forms the plate 2. The deflector will protect the throat region 11 of the air-bag 10. The deflector 16 is an upstanding wall which immediately surrounds the central aperture 3 in the plate 2. The inner face of the wall diverges upwardly away from the central aperture 3 to form a deflecting face which will deflect a horizontal flow of gas upwardly. Part of the deflector 16 is positioned between the outlet apertures 9 of the inflator 5 and the part of the throat 11 of the air-bag 10 which is trapped between the retainer ring 13 and the plate 2, and thus the deflector 16 protects the throat region 11 of the air-bag 10 from a direct flow of gas from the inflator 5. In the event that the vehicle is involved in an accident, the safety device is triggered, and the inflator 5 is actuated to generate gas to inflate the air-bag 10. The gas passing out from the outlet apertures 9 is directed immediately onto the diverging inner face of the deflector 16, and the deflector 16 deflects the gas away from the part of the throat 11 which is trapped between the retainer ring 13 and the pate 2. After the gas has been deflected by the deflector 16 the gas flow is less aggressive and may pass upwardly into the interior of the air-bag 10. In embodiments of the invention, the housing 1 incorporates plastic hooks which are formed integrally with the body of the housing 1. The hooks form part of a mounting arrangement for mounting the housing 1 onto part of the vehicle. In other embodiments the hooks may be separate elements to the housing 1, and simply mounted on the housing 1 to enable the housing 1 to be mounted to the vehicle. Although, in the preferred embodiment of the invention, the deflector 16 is formed integrally with the plate 2 of the housing 1, in an alternative embodiment the deflector 16 is a separate element to the housing 1, as seen in Figure 5. In this alternative embodiment, the deflector 16 is a hollow cylindrical open-ended member which provides an inner face that diverges away from the central aperture 3 when the member is within the central aperture 3. In this alternative embodiment the member has a screw thread on its outer wall, which engages a screw thread on the plate 2 on the inner face of the central aperture 3. The member is thus screwed into the central aperture 3 to form the deflector 16. Although in this alternative embodiment the deflector is mounted to the plate 2 by a screw-fit, the deflector 16 may be mounted by a friction fit or alternatively a snap-in arrangement. In this alternative embodiment the member which forms the deflector 16 is of the same material as the material of plate 2, but in other embodiments, the member which forms the deflector 16 may be of a different material to that of the plate 2. In such other embodiments, the deflector 16 may be of a plastics material which has a higher melting point than the plastics material forming the plate 2. Thus, the deflector 16 may be more resistant to being damaged by the hot jet of gas passing out from the outlet apertures 9 in the inflator 5 than the material of the plate 2. 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 safety device comprising a housing which incorporates a plate with an aperture; an air-bag, at least part of the air-bag being attached to the plate; and an inflator, the inflator being mounted to the plate with at least part of the inflator extending through the aperture, the inflator having at least one gas outlet which is adjacent the part of the air-bag which is attached to the plate, the safety device further comprising a deflector which is carried by the plate, at least part of the deflector being positioned between the at least one outlet aperture of the inflator and the part of the air-bag which is attached to the plate, to deflect gas passing out from the at least one outlet aperture away from the part of the air-bag which is attached to the plate.

2. A safety device according to Claim 1, wherein the housing is of plastic.

3. A safety device according to Claim 1 or Claim 2, wherein the deflector is formed integrally with the said plate.

4. A safety device according to Claim 1 or Claim 2, wherein the deflector is a separate component mounted to the said plate.

5. A safety device according to Claim 4, wherein the deflector is at least partly of a different material to the material of the plate.

6. A safety device according to any one of the preceding Claims, wherein the deflector defines an upstanding wall which surrounds the aperture in the plate.

7. A safety device according to Claim 6, wherein said wall has an inner face which diverges away from the aperture.

8. A safety device according to any one of the preceding Claims, wherein the inflator incorporates a flange and the flange is attached to one side of the plate.

9. A safety device according to any one of the preceding Claims, wherein the housing incorporates mounting hooks, so that the housing may be mounted to part of a motor vehicle.

10. A safety device substantially as herein described with reference to and as shown in Figures 2 to 5 of the accompanying drawings.

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