GB2339738A - Airbag with initially uneven surface - Google Patents

Description

2339738 AN AIRBAG The present invention relates to an airbag and more

particularly to an airbag for use within a motor vehicle.

Over recent years, use of airbags in motor vehicles has become relatively commonplace in order to protect vehicle occupants during vehicle collisions. Typically, airbags are specified taking an average occupant and a normal occupant position in the vehicle in order to assess the necessary airbag dimensions and inflation force to achieve sufficiently rapid deployment for appropriate protection. It will be appreciated that rapid deployment is necessary in order to provide an adequate level of protection for a vehicle occupant during the relatively short time period of a vehicle accident.

Unfortunately, provision of an adequately rapid deployment of an airbag, as indicated previously, requires averaging both of the occupant dimensions and that occupant's position. However, occupants move within a vehicle seat and actual occupant seat position may be adjusted in accordance with their preference. In any event, all occupants are not of average dimensions. In such circumstances, appropriately rapid deployment of the airbag itself may be too aggressive for the circumstances and therefore cause occupant injury.

It is an object of the present invention to provide an airbag which is more progressive in terms of engagement with an occupant and therefore less aggressive particularly with regard to occupants significantly different to the average in terms of their position.

In accordance with the present invention there is provided an airbag for a motor vehicle wherein the airbag is inflated upon detection of an accident, the airbag including a structured wall section arranged in use to abut an occupant of the vehicle on inflation, the structured wall section unevenly developing through inflation to initially deploy tentacle elements therefrom with lines of weakness therebetween in order to develop therefrom, under further inflation of the airbag, wall bubbles which connect these tentacle elements and such that airbag flats between these wall bubbles, under further inflation of the airbag, expand or deform in order to develop said wall section into a substantially even structured wall surface across the -45 airbag finallypresented to the occupant.

Further in accordance with the present invention, there is provided an airbag for a motor vehicle wherein the airbag includes at least one transient uneven abutment surface in a structured wall section to engage a vehicle occupant in a progressively less compliant manner until that structured wall section is a substantially even surface across the airbag finally presented to the occupant.

Preferably, the structured wall section has a regular or irregular configuration as required by a particular installation within a motor vehicle.

Lines of weakness within the airbag can be created through weaving or stitching or other means as appropriate.

The degree of unevenness within the structured wall section of the airbag will generally be in the order of at least 50 mm.

An mbodiment of the present invention will now be described by way of example with reference to the accompanying drawings, in which:

Figure 1 is a pictorial plan view of an airbag; Figure 2 is a pictorial front perspective view of the airbag depicted in Figure 1 at a first stage of deployment with only selected inflation for illustration purposes only; Figure 3 is a front perspective of the airbag depicted in Figure 2 at a second stage of deployment; Figure 4 is a front perspective of the airbag depicted in Figures 2 and 3 at a third stage of deployment; and Figure 5 is a front perspective view of the airbag depicted in Figures 2 to 4 upon full deployment.

As indicated previously, airbags must be rapidly deployed in order to be effective within a motor vehicle. Traditionally, a blanket flat linear surface is initially deployed and presented to a motor vehicle occupant. Unfortunately, if the occupant is too close to the airbag or mis-aligned, such a flat monolithic engagement can be a significant and sudden percussive force to the occupant with at least a potential for airbag deployment induced occupant injury- The present invention reduces such initial percussive engagement with the vehicle occupant upon airbag deployment. In effect, the initial airbag engagement surface rather than being even and linear is presented as an uneven undulating surface which it will be appreciated is more compliant in engagement with the occupant.

The degree of unevenness within the engagement surface initially presented to the occupant is gradually diminished until an even and linear surface, in order to maximise engagement with the occupant, is fanally presented. Thus, in the engagement or abutment surface of the airbag from initial engagement with the occupant progressively becomes less compliant and so more resilient in order'to absorb energy and protect the vehicle occupant.

In the embodiment depicted in the drawings, an airbag I is illustrated in which an engagement or abutment surface 2 is deployed towards an occupant in use. This engagement surface 2 includes at least one structured wall section 3.

Figures 2 to 4 only illustrate one wall section 3 to improve clarity. The airbag 1 is deployed in a conventional manner through a gas inflation mechanism typically including a pyrotechnic gas generation apparatus which rapidly inflates the airbag I in order to present it to a vehicle occupant in use.

The wall sections 3 are formed through appropriate manufacturing techniques. Thus, the wall sections 3 in the engagement surface 2 can be achieved through appropriate weaving of the material from which the surface 2 is formed or stitching or introduction of lines of weakness or folding or adhesive or any other technique in order to create localised structures necessary to create the walled section 3.

It will be appreciated that naturally there is a desire within a closed volume to equalise gas pressure. Thus, within an airbag 1 upon inflation -6, from an appropriate airbag deployment mechanism, there is a natural desire to equalise gas pressure throughout the volume of the airbag 1. In such circumstances the wall sections 3 are deployed. Due to their limited volume, these sections may, at least transiently, be relatively rigid but being located upon a more voluminous base volume 4 can be deformed or deflected into compliance with an engaged occupant profile.

Normally, the airbag 1 when stowed may have a generally conventional configuration. However, as illustrated in Figure 2, upon initial deployment of the airbag 1, the base volume 4 of the airbag 1 is inflated. This inflation of the base volume 4 will typically force the airbag 1 beyond the natural canning or housing within which the bag 1 is stowed but not bring the airbag 1 into engagement with an occupant of a vehicle. Thus, at a certain level of inflation of the airbag 1, the wall sections 3 are inflated. This first stage of airbag deployment is illustrated in Figure 2.

The wall section 3 depicted in Figure 2 generally takes the form of a plurality of tentacles which are projected away from the airbag 1 and thus towards a vehicle occupant. These tentacles are localised upon the base volume 4 and thus are relatively compliant, i.e. deformable and deflectable upon the base volume 4 on engagement with a vehicle occupant. In such circumstances, there is a degree of low level engagement with the occupant but of a relatively soft or passive nature with a relatively low percussive shock. However, this engagement will generally be sufficient to push or urge the occupant to the desired orientation for better protective engagement in a vehicle accident.

The tentacles of the wall section 3 can be created through stitching or 5 adhesion of specific tentacle fingers into orifices of the engagement surface 2. However, it is preferred that these tentacles of the wall section 3 are created through reduced material thickness or weaving such that the tentacles of the wall section 3 due to equahsation of gas pressure within the volume of the airbag 1 are projected as depicted and described.

It will be appreciated if the tentacles for wall section 3 are relatively weaker than the material of the surface 2 in particular then, in accordance with equalisation of inflation gas pressure, that weaker material will be ballooned into the tentacle deployment depicted.

Clearly, the tentacles of the wall section 3 alone are insufficient to engage a vehicle occupant appropriately for injury prevention in a traffic accident. However, sudden transfer from tentacle engagement to full even and linear surface engagement with an occupant would stiE precipitate significant percussive shock and therefore may induce injury itself upon that vehicle occupant. Thus, in accordance with the present invention, it is preferred that additional stages are included to the even and linear surface presentation to an occupant as depicted in Figure 5. These additional stages are illustrated in Figures 3 and 4 of the drawings.

As depicted in Figure 2, between the tentacles of the wall section 3, sections 5 of relative weakness in the engagement surface 2 are located.

Thus, upon further inflation of the airbag 1, and thus increase in gas pressure, these weak sections 5 rupture or expand to allow ballooning between the tentacles of the wall section 3 and so create wall bubbles 6 as depicted in Figure 3.

1 Due to their larger dimensions and broader actual base to the surface 2, it will be appreciated that these wall bubbles 6 are significantly less compliant than the tentacles illustrated in Figure 2 and thus, present a noticeably more resilient surface to a vehicle occupant for appropriate engagement.

In Figure 4, it will be noted that these wall bubbles 6 in a next stage of airbag deployment extend laterally with the line of the weak sections 5 in order to create airbag mounds 7 with airbag flats 8 therebetween.

It will again be appreciated due to the greater engagement volume and dimensions of these mounds 7 that the resilience of the surface 2 presented by the tops of these mounds 7 to an occupant in use is significantly greater than that during earlier airbag deployment stages depicted in Figures 2 and 3. Furthermore, as the airbag 1 deployment proceeds through further gas inflation, the isolation of these flats 8 diminishes until, as depicted in Figure 5, a substantially flat, even and linear surface 9 can be presented to 5 a vehicle occupant upon full airbag 1 deployment.

It will be appreciated, although Figure 5 illustrates the eventual final airbag surface 9 as substantially planar that more normally due to the gas injection nature of airbag 1 inflation, typically this surface 9 win be domed at least transiently during airbag deployment. Such doming is one of the inherent problems with airbag 1 deployment in that the central region of the surface 9 is in direct line with the gas inflation jet and thus presents a significant percussive shock to a vehicle occupant. The present invention regulates such percussive shock to an occupant by ensuring through weaknesses or other means within the engagement surface 2 of the airbag 1, that at least the central regions of an airbag must pass through the tentacle, bubble wall 6 and mound 7 stages before -presenting an even and linear surface engagement with a vehicle occupant. These stages allow a more sympathetic engagement with a vehicle occupant by providing a compliant engagement depth for the airbag during early or initial stages of engagement with the occupant. Clearly, the extent of the compliant engagement depth is a design choice limited by the capability of incorporating lines of weakness in the surface 2 which can expand to the required extent for the tentacles, airbag bubbles (6) and airbag mounds (7).

It will be appreciated that through the inflation of walled sections 3 that a vehicle occupant is more gently pushed away from the bulk of the airbag if they are relatively close to that airbag 1. Typically, the tentacles along with bubbles 6 and mounds 7 will have a height at least in the order of 50 mm above the surface 2. However, it will be appreciated that the degree of unevenness or compliance depth between the surface 2 and the tops of the wall section 3 at the various stages of deployment will depend upon expected operational conditions and actual airbag installation within a vehicle.

As indicated previously, typically a plurality of wall sections 3 will be included within the engagement surface 2 of the airbag 1. As depicted the lines of the wall section 3 may be jagged or straight in order to achieve the best transient engagement with an occupant upon deployment. Furthermore, the tentacles or other initial structures used to engage the vehicle occupant can be regularly located within the airbag 1 or irregularly distributed or alternatively configured for best presentation, i.e. a different tentacle distribution within the central region of the airbag 1 in comparison with peripheral regions due to the inherent nature of central jet inflation of the airbag 1 upon deployment presenting an uneven blast of inflation gas.

It will also be understood that the tentacles, airbag wall bubbles (6) and airbag mounds (7) may have different heights above the surface 2 during the successive deployment stages and across the surface 2 for best engagement with an occupant.

Claims (9)

-12CLAIMS

1. An airbag for a motor vehicle, the airbag including a structured wall section arranged in use to initially abut, in use, an occupant of a vehicle upon inflation, the structured wall section being configured for uneven development through inflation to deploy tentacle elements with lines of weakness therebetween in order to develop, under further inflation, wall bubbles which connect with these tentacle elements and such that airbag flats between these wall bubbles, under further inflation, expand or deform in order to develop said wall section into a substantially even surface across the airbag for final presentation to an occupant.

2. An airbag for a motor vehicle, the airbag including at least one transient structured wall section to form an uneven engagement surface, in use, to a vehicle occupant which is progressively less compliant under inflation until that structured wall section is an even and linear surface across the airbag as finally presented, in use, to that occupant.

3. An airbag as claimed in Claim 1 or Claim 2, wherein the structured wall section is regular across the airbag.

4. An airbag as claimed in Claim 2, wherein the structured wall section is irregular across the airbag.

5. An airbag as claimed in Claim 1 or Claim 2, wherein the airbag includes respective structured wall sections of different configuration in different areas of the airbag.

6. An airbag as claimed in any preceding claim, wherein each structured wall section is formed through weaving or stitching or adhesion or introduction of lines of weakness within the airbag structure.

7. An airbag as claimed in any preceding claim, wherein the structured I wall section has a depth in the order of 50 mm.

8. An airbag substantially as hereinbefore described with reference to the accompanying drawings.

9. A motor vehicle including an airbag as claimed in any preceding claim.