GB2339737A - An airbag arrangement - Google Patents

Description

2339737 AN AIRBAG ARRANGEMENT The present invention relates to an airbag

arrangement for use within a motor vehicle.

Use of airbags within a motor vehicle in order to protect occupants of that vehicle during road traffic accidents has become relatively commonplace. Thus, it will be understood that an airbag is generally rapidly inflated in order to present a protective "cushion" about the vehicle occupant in order to absorb collision energy and prevent occupant collisions with relatively hard surfaces within the vehicle cabin.

Such rapid deployment of the airbag necessitates relatively aggressive inflation which can in itself injure the vehicle occupant. Such injury to the vehicle occupant is particularly possible when that occupant is orientated or significantly different from that averaged in order to specify the airbag deployment regime. For example, if the occupant is leaning forward or to one side as the airbag arrangement is deployed then the percussive force due to the rapid inflation of the airbag can jar the occupant creating injuries thereby.

It is an object of the present invention to provide an airbag arrangement in which inflation of the airbag can be more appropriately controlled.

In accordance with the present invention there is provided an airbag arrangement for a vehicle, the arrangement comprising an airbag deployed through inflation via a nozzle arrangement, the nozzle arrangement comprising a first nozzle member and a second nozzle member arranged in juxtaposed relationship about an axis, said first nozzle member including a fundamental aperture and said second nozzle member including a secondary aperture arrangement, said fundamental aperture and said secondary aperture arrangement being notionally aligned about the axis, said first and/or said second nozzle member being coupled to bias means associated with said airbag and arranged therefrom to relatively deform or relatively deflect said fundamental aperture and said secondary aperture arrangement from said notional alignment dependent upon that airbag's deployment condition or status.

Normally, the fundamental aperture will be a single circular orifice.

The secondary aperture arrangement may comprise a plurality of radiating petals or a distribution of holes or slots. It is the positional combination of the fundamental aperture and the secondary aperture arrangement in juxtaposed relationship which adjusts the available overlapping nozzle cross-section therebetween in order to define the nozzle arrangement's operational cross-section and, through their respective peripheral walls in combination, achieve some guiding of the inflation gas jet.

The first nozzle member and the second nozzle member may be formed from a metal or plastics material. Thus, these members may present static fundamental aperture and/or secondary aperture arrangement dimensions. Alternatively, the first and second nozzle members may be formed from elastomeric materials such that the fundamental aperture and/or the secondary aperture arrangement deform under load presented through the bias means.

The bias means may comprise straps or tethers secured both to the first and/or the second nozzle member along with the airbag as it is deployed.

The first nozzle member and the second nozzle member may comprise respective cupped elements. Furthermore, a friction coupling can be provided between the first nozzle member and the second nozzle member in order to facilitate good bias response as the members are relatively deformed or relatively deflected as the airbag deployment progresses.

Alternatively, in accordance with the invention, there is provided an airbag arrangement for a vehicle, the arrangement comprising an airbag deployed through inflation via a nozzle, the nozzle comprising a first nozzle member and a plain nozzle member arranged about a common axis, said first nozzle member including a fundamental aperture and said plain nozzle 20 member being secured to one side of that fundamental aperture, said first and/or plain nozzle member being coupled to bias means associated with said airbag and, dependent upon that airbag's deployment condition or status, said bias means acting upon said first member and/or said plain nozzle member in order to relatively displace these members such that the plain nozzle member effectively reduces the size of, or closes, said fundamental aperture by extending across it.

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

Figure 1 is a pictorial plan view of a first nozzle member; Figure 2 is a pictorial plan view of a second nozzle member; Figure 3 is a pictorial perspective view of the nozzle members depicted in Figures 1 and 2 within a schematic airbag arrangement; Figure 4 is a pictorial front perspective of an airbag arrangement in accordance with a first deployment; Figure 5 is a pictorial front elevation of an airbag in accordance with a second deployment; Figure 6 is a part cross-section of a nozzle arrangement in a first notionally aligned configuration; and Figure 7 is a pictorial part cross-section of a nozzle arrangement in accordance with a displaced configuration consistent with the invention.

As indicated previously, airbags within motor vehicles are generally deployed using a gas inflation mechanism through which normally hot pyrotechnically generated gas is jetted into the airbag through a nozzle arrangement. Clearly, to inflate with sufficient rapidity an airbag, gas flow through that nozzle arrangement must be rapid. Unfortunately, sufficiently powerful and rapid gas jets can be dangerous in terms of potential injury to an occupant.

In accordance with one embodiment of the present invention, the nozzle arrangement though which the inflation gas is input to the airbag comprises two members in a juxtaposed position. These nozzle members are depicted respectively in Figures 1 and 2.

In Figure 1 a first nozzle member 1 is depicted in pictorial plan view. This first nozzle member 1 essentially comprises a fundamental aperture 2 through which inflation gas is presented. Thus, the first nozzle member 1 is configured to allow this member 1 to be secured to an airbag deployment mechanism such that that airbag deployment mechanism's inflation gas can be presented through the fundamental aperture 2.

In Figure 2 a second nozzle member 3 is illustrated in pictorial plan view. This member 3 functionally includes a secondary aperture arrangement 4. As depicted, this comprises a central aperture surrounded by a plurality of further petal apertures. However, it will be appreciated that a wide range of secondary aperture arrangements could be used dependent upon the necessary nozzle arrangement configuration necessary to achieve the desired response in accordance with the present invention.

Thus, the arrangement 4 could take the form of radiating petals or slots or a grid or any other distribution of apertures desired for appropriate response.

Figure 3 illustrates combination of the first nozzle member 1 and the second nozzle member 3 within a schematic illustration of an airbag arrangement. Thus, the members 1, 3 are arranged in a juxtaposed relationship as a nozzle arrangement 5 between an airbag housing 6 and an airbag deployment mechanism 7. It will be appreciated that the housing 6 accommodates a stowed airbag prior to deployment whilst the mechanism 7 includes an appropriate inflation means to achieve rapid gas evacuation through the nozzle arrangement 5 into that airbag upon deployment.

Tho members 1, 3 are arranged in a juxtaposed position such that respective central regions of the fundamental aperture 2 and the aperture arrangement 4 are notionally aligned and overlap. However, lateral movement between the members 1, 3 relative to each other is achievable.

Thus, the respective coincident or overlap between the fundamental aperture 2 and the secondary aperture arrangement 4 can be varied in order to adjust the available nozzle jet cross-section through which inflation gas can be presented to the airbag for deployment.

I Such relative lateral movement can be achieved whilst retaining 10 integration of the airbag arrangement through configuring the respective members 1, 3 as friction plates with radial slide members therebetween. Furthermore, association between the respective members 1, 3 can be achieved through appropriate guide surfaces either side;vhich retain the members 1, 3 in a juxtaposed relationship.

The members 1, 3 will normally be of a cupped configuration, one within the other. Such configuration further facilitates juxtaposed positioning between the members 1,3 without fixings therebetween.

In accordance with the present invention, it is displacement between the nozzle members 1, 3 which achieves the variation in nozzle arrangement cross-section available for inflation gas passage to deploy the airbag. It will be appreciated that the available cross-section of the nozzle arrangement 5 is highly determinant in the rate of gas flow therethrough and so, in the present case, deployment of the airbag. Thus, in accordance with the present invention, either the first nozzle member 1 or the second nozzle member 3 or both members 1, 3 are coupled to tethers or straps secured to the airbag. Thus, through these tethers or straps, the relative positions of the members 1, 3 to each other are biased one way or the other dependent upon the current airbag deployment condition or status.

I In Figures 4 and 5, two airbag deployment scenarios are illustrated in 10 pictorial perspective for illustrative purposes only. In Figure 4, an airbag 41 deployment is depicted with substantially even inflation whilst in Figure 5 an airbag 51 deployment is illustrated with uneven inflation due to engagement with an obstacle, such as an occupant 52, on only one side of the airbag 51.

In Figure 4 the airbag 41 is anchored upon an airbag housing 46 and is inflated through a nozzle arrangement 45 from an airbag deployment mechanism 47. The nozzle arrangement 45 comprises a first nozzle member 40 and a second nozzle member 43. These members 40, 43 as indicated previously with regard to members 1, 3 are in a juxtaposed relationship and allow lateral movement therebetween. Thus, a respective fundamental aperture (not shown) in the first member 40 is notionally aligned about a common axis, i.e. prior to airbag deployment, with a central portion of a secondary aperture arrangement in the second nozzle member 43.

Upon initial deployment of the airbag 41 through activation of the mechanism 47, the nozzle arrangement 45, as indicated previously, has the fundamental aperture and the secondary aperture arrangement in respective members 40, 43 in notional alignment. Thus, upon initial deployment the overlap and therefor available cross-sectional area of the nozzle arrangement for inflation gas flow is substantially maximised or as desired for initial airbag deployment. However, as depicted in Figure 4, the second nozzle member 43 is coupled to bias straps or tethers 48 which are also secured to the airbag 41. Thus, as the airbag 41 inflates, it will be appreciated that these tethers 48 can act upon the second nozzle member 43 in order to bias its orientation in accordance with the airbag 41 status and condition. In such circumstances, the nozzle arrangement cross-section can be varied as desired through an airbag deployment episode by relative displacement or distortion between the fundamental aperture and the secondary aperture arrangement as a result of airbag bias action through the tethers 48.

Clearly, the tethers 48 upon opposite sides, or as desired, can be configured of different lengths or resistance to elongation in order to produce the required variations in available nozzle arrangement crosssection during the deployment episode by altering the relative bias between the members 40, 43.

It will be appreciated that the straps or tethers 48 can be incorporated into the airbag structure or skirt portions thereof Furthermore, these tethers or straps 48 are preferably substantially symmetrical in order to ensure appropriate displacement in the nozzle arrangement 45.

Typically, four, eight or twelve straps or tethers 48 will be located about an airbag 41 and these straps or tethers 48 may be of differing lengths in order to vary the sequence of engagement and so bias with the airbag 41 through airbag deployment inflation.

The tethers 48 may be of fixed length or elastic. With tethers 48 of a fixed length, it will be appreciated that action upon the member 43 is only effective once the airbag 41 has developed to a sufficient extent in order to tighten these tethers 48. With regard to elastic tethers 48, it will be appreciated that the level of action upon the member 43 may be adjusted, and alter over the airbag deployment episode, dependent upon the rate of airbag 41 deployment and extent along with Young's modulus and coefficients of elasticity, stress and strain variation with extension length for the tethers 48.

Normally, the tethers 48 will be arranged in substantially opposed pairs in order to balance the effect upon the member 43. Furthermore, the tethers 43 could be deployed from a reel and this reel could act to limit the rate of tether 48 release through inertia engagement or other mechanical 5 control.

Generally, the tethers 48 will act by relative displacement between the first member 40 and the second member 43 or more particularly between the respective fundamental aperture and the secondary aperture arrangement incorporated into these members 40, 43. However, it will be appreciated that, the tethers 48 could act upon a member 43 which is distortable under load from the tethers 48 such that the shape of the secondary aperture arrangement incorporated therein is also distorted to vary the nozzle cross-section area through which inflation gas is deployed from the mechanism 47 to the air bag 41. Alternatively, the fundamental aperture could be distorted and the secondary aperture arrangement of fixed dimension or, both the fundamental aperture and the secondary aperture arrangement could distort under load through the tethers 48.

It will be appreciated, the purpose of relative displacement between the members 43, 40 is in order to alter the nozzle aperture cross-section available through which inflation gases can be presented to the airbag 41. The tethers 48 adjust this nozzle cross-section as the airbag 41 develops through inflation. Thus, the tethers 48 in association with the nozzle arrangement 45 allow control of the rate of airbag 41 deployment to that acceptable for good engagement with an occupant.

Whether the nozzle cross-section constituted by the degree of alignment between the fundamental aperture and the secondary aperture arrangement is all through relative displacement or through aperture distortion or a combination is substantially irrelevant provided the control of the tethers 48 on the aperture arrangement 45 is consistent with airbag 41 deployment status or condition.

In Figure 4, inflation of the airbag 41 is substantially even and balanced. However, it will be appreciated that, if the airbag 41 were to encounter an obstacle, such as a vehicle occupant, then inflation of the airbag would be distorted and so it may be desirable to adjust the rate of airbag inflation accordingly.

In Figure 5 an airbag 51 upon deployment inflation encounters a vehicle occupant 52. Thus, the airbag 51 is distorted in one comer.

The airbag 51 is inflated, as indicated previously, and normally through a deployment mechanism 57 secured to a nozzle arrangement 55 such that the airbag 51 extends from the housing 56.

It will be appreciated that an airbag 51 being an enclosed volume wishes to equalise gas pressure along with adopt as low a surface area for volume as possible, i.e. a sphere. Thus, in the embodiment depicted in Figure 5, it will be appreciated that the distortion causes to the airbag 51 during deployment will create a substantially repulsive force in the direction of arrow head R upon the occupant 52. This repulsive force R may push the occupant 52 into engagement with relatively hard surfaces and so precipitate injury to that occupant 52.

1 In the above circumstances, it would be desirable to reduce the rate of 10 airbag 51 inflation and so reduce the magnitude of the force R. Alternatively, it may be desirable to increase the inflation rate in other circumstances to magnify the effect of the airbag 51 due to the reduced engagement with the occupant 52. Inherently, it is the actual specific installation and deployment scenario which dictates whether increased or 15 reduced airbag 51 inflation rate is desired.

Irrespective of whether the rate of airbag 51 deployment should be increased or decreased, the nozzle arrangement 55 in accordance with the present invention allows such adjustment through alteration in the nozzle cross-section available for gas input to the airbag 51.

The nozzle arrangement 55 as previously comprises a first nozzle member 50 and a second nozzle member 53. These members 50, 53 are in a juxtaposed relationship and are allowed to move laterally relative to each other in order to vary the alignment between a fundamental aperture in the first nozzle member 50 and a secondary aperture arrangement in the second nozzle member 53. By appropriate choice of the dimensions of the respective fundamental aperture and secondary aperture arrangement, it will be appreciated that dependent upon the degree of relative displacement between the first member 50 and the second member 53, the nozzle crosssection available for gas jet input to the airbag 51 can be adjusted.

Relative displacement between the first nozzle member 50 and the second nozzle member 53 is in a similar manner to that depicted with regard to Figure 4. Thus, tethers or straps 58 are secured both to the airbag.51 and to the second nozzle member 53. The length of respective tethers 58 either side of the airbag 51 is determined by the inflation status or condition of that airbag 1. Thus, in the circumstances depicted in Figure 5, it win be appreciated that tether 58a is pulled further than tether 58b due to the distorting effect of engagement with the occupant 52. Thus, additional stretching load upon the tether 58a pulls the second nozzle member 52 and so precipitates relative displacement between that member 53 and the first member 50 in order to alter the alignment between the respective fundamental aperture and the secondary aperture arrangement. Such 15- alteration in the alignment between the fundamental aperture and the secondary aperture arrangement will alter the nozzle cross-section available for gas injection to the airbag 51 and therefore the rate of inflation of that airbag 51.

As previously rather than actual relative displacement between the first nozzle member 50 and the second nozzle member 53, it will be appreciated that the fundamental aperture or the secondary aperture arrangement could be distorted through the loads presented by the tethers 58 in order to alter the resultant overlap nozzle cross-section available for gas injection to the airbag 51.

Figures 6 and 7 illustrate, in part cross-section, a nozzle arrangement comprising a first nozzle member 61 and a second nozzle member 62.

The first nozzle member 61 includes a fundamental aperture 63 whilst the second nozzle member 62 includes a secondary aperture arrangement comprising a central aperture 64 and respective radial apertures 65, 66. In use, the fundamental aperture 63 will be coupled to airbag inflation means (not shown) such that inflation gas passes through this aperture 63.

Figure 6 illustrates the nozzle arrangement 60 generally prior to airbag deployment such that the fundamental aperture 63 is notionally aligned with the central aperture 64 of the secondary aperture arrangement. Thus, upon initial inflation of an airbag coupled subsequently to the second nozzle member 62, it will be appreciated that inflation.;;.-as passes through the fundamental aperture 63 and then through the secondary aperture arrangement via the central aperture 64 to that airbag. In such circumstances, the nozzle cross-section available to the inflation gases is substantially dictated by the central aperture 64 and this will significantly determine airbag inflation rate.

As indicated previously, the respective members 61, 62 are allowed through appropriate means to achieve relative lateral displacement. Thus, as depicted in Figure 7, the second nozzle member 62 has moved relative to the first nozzle member 61 with the result that the fundamental aperture 63 is no longer in alignment with the central aperture 64 but is now overlapping with a radial aperture 65. Thus, the nozzle cross-section through which inflation gas can pass is determined by the degree of overlap between the fundamental aperture 63 and this radial aperture 65. This degree of overlap varies with the relative displacement between the first member 61 and the second member 62.

As indicated previously, either the first nozzle member 61 or the second nozzle member 62 is coupled to tethers or straps 68 secured to the airbag such that these straps or tethers 68 apply load to the member 61 as the airbag develops, in order to precipitate the relative displacement described and thus variation in alignment between the fundamental aperture 63 and the secondary aperture arrangement 64-66.

Even load application through the straps or tethers 68 applied to members 61, 62 will leave aperture alignment substantially as indicated in Figure 6. However, uneven load applied through tethers or straps 68 will result in the relative displacement depicted in Figure 7 and therefore alteration in the aperture alignment and so nozzle cross-sectional area available for inflation gas transmission to an airbag. Such an uneven load distribution applied via the straps or tethers 68 may be the result of uneven 10 inflation of the airbag resulting from angular or uneven inflation of the airbag due to engagement with an obstacle or vehicle occupant. In such circumstances, it will be appreciated that generally the strap or tethers 68 will be in opposed pairs in order to achieve the desired uneven loading and so displacement between the members 61, 62.

As indicated previously, generally an airbag must be deployed rapidly and thus the rate of gas influx to the airbag must be high. Such high rate gas injecting to the airbag can itself precipitate problems when that jet is directed towards an occupant.

It will be appreciated in accordance with the present invention by 20 appropriate choice and distribution of the fundamental aperture 63 and the secondary aperture arrangement 64-66 that a degree of jet direction or guiding variation can be achieved through the respective aperture peripheral walls coinciding to provide a varying guide path for the injection gas flow. Such jet direction variation may be utilised to achieve more appropriate airbag deployment through alteration in the location of that inflation jet engagement with the surface to which the object or the vehicle occupant is in contact with the airbag. It will be understood that cupped configurations for the respective nozzle members will facilitate such variations in jet angle for the same degree of relative displacement in comparison with juxtaposed flat jet members.

It will be appreciated that the relative sizes and distribution of apertures in the nozzle members can be tailored to specific requirements for appropriate airbag deployment. Thus, as depicted the radial aperture 65 could be larger than the central aperture 64 or vice versa depending upon requirements. Larger radial apertures 65 will tend to increase the rate of gas transmission whilst smaller radial apertures 65 will reduce the rate of inflation gas transmission with reciprocal alteration in the airbag deployment rate and aggressiveness.

Further in accordance with the present invention, it will be appreciated that appropriate relative displacement and/or distortion of a first nozzle member or a second nozzle member could precipitate a total misalignment 19- between the fundamental aperture and the secondary aperture arrangement and so cut off inflation gas to the airbag. In such circumstances, a single tether or strap will be secured to the airbag and have a fixed length such that when the airbag is deployed to the extent of 5 that strap or tether length, the nozzle arrangement would be distorted or there would be relative displacement between the first nozzle member and the second nozzle member to provide total aperture misalignment and therefore inflation gas cut off to stop further inflation of the airbag. Prior to the effect of this single tether the aperture arrangement may have been 10 controlled by other straps or tethers operated as described previously. Clearly, with the nozzles completely out of alignment there will be a necessity to provide some form of venting for any further inflation gas flows.

Alternatively, a plain nozzle member, to replace one of the nozzle members, could be associated with a nozzle arrangement and this plain 15 nozzle member pulled across the fundamental aperture and/or the secondary aperture arrangement by a bias strap or tether secured to the airbag upon achievement of the desired degree of airbag deployment. In such circumstances, any excess inflation gas would need to be vented in an appropriate manner away from the vehicle interior and in particular 20 occupants of the vehicle. Such a plain nozzle member could replace the second nozzle member with a fundamental aperture alone regulating inflation gas as appropriate until the plain member was biased across that fundamental aperture through the tether or strap secured to the airbag as it deploys.

It will be understood that, particularly for large airbags, a plurality of nozzles could be provided in the arrangement in order to achieve the desired deployment inflation rate and response. Thus, more nozzle cross-section will be available for gas injection and by orientating nozzles appropriately, the directionality of such flows can be set or adjusted. Furthermore, operation or opening or closure of these nozzles may be successive, consecutive, sequential or at the same time.

Claims (13)

-21CLAIMS

1. An airbag arrangement for a vehicle, the arrangement comprising an airbag deployed through inflation via a nozzle, the nozzle comprising a first nozzle member and a second nozzle member arranged in juxtaposed relationship, said first nozzle member including a fundamental aperture and said second nozzle member including a secondary aperture arrangement, said first and/or said second nozzle member being coupled to bias means associated with said airbag and arr4nged therefrom to deform or deflect said fundamental aperture and said secondary aperture arrangement from relative alignment dependent upon airbag deployment condition or status and so alter the nozzle in terms of its nozzle cross-sectional area available for passage of an inflation gas for inflation of the airbag through the nozzle.

2. An arrangement as claimed in Claim 1, wherein the fundamental aperture is a circular orifice in the first nozzle member.

3. An arrangement as claimed in Claim 1 or Claim 2, wherein the secondary nozzle arrangement comprises a central aperture with radial apertures thereabout or comprises radial petals extending from a central position for notional alignment about a common axis with the fundamental aperture.

4. An arrangement as claimed in Claim 1, 2 or 3, wherein a plurality of nozzles are provided.

5. An arrangement as claimed in Claim 1, 2 or 3, wherein the first nozzle member and/or the second nozzle member is formed from a material which is deformable under a load from the bias means such that the respective fundamental aperture and/or said secondary aperture arrangement is deformed to alter the nozzle cross-sectional area.

6. An arrangement as claimed in any preceding claim, wherein the bias means comprises straps or tethers secured to the airbag and to the first nozzle member or the second nozzle member.

7. An arrangement as claimed in Claim 5, wherein the straps or tethers have a fixed length.

8. An airbag as claimed in any of Claims 1 to 5, wherein the straps or tethers have an elastic extension response to load.

9. An airbag arrangement as claimed in any preceding claim, wherein the first nozzle member and the second nozzle member have a cupped configuration, one within the other.

10. An arrangement as claimed in any preceding claim, wherein the bias means is configured to allow total misalignment between said fundamental aperture and said secondary aperture arrangement.

11. An airbag arrangement for a vehicle, the arrangement comprising an airbag deployed for inflation via a nozzle, the nozzle comprising a first nozzle member and a plain nozzle member arranged about a common axis, said first nozzle member including a fundamental aperture and said plain nozzle member being secured to one side of that fundamental aperture, said first and/or plain nozzle member being coupled to bias means associated with said airbag and dependent upon that airbag's deployment condition or status, said bias means acting upon said first nozzle member and/or plain nozzle in order to relatively displace these members such that the plain nozzle member effectively closes said fundamental aperture by extending across it.

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

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