GB2346847A

GB2346847A - An air bag arrangement

Info

Publication number: GB2346847A
Application number: GB9903725A
Authority: GB
Inventors: Andrew Leask; Ian Martin Redgrave
Original assignee: MG Rover Group Ltd
Current assignee: MG Rover Group Ltd
Priority date: 1999-02-19
Filing date: 1999-02-19
Publication date: 2000-08-23
Also published as: GB9903725D0

Abstract

An airbag arrangement (21) in which a canister frame (22) combines with a lining member (25) in order to define a canister with a stowage space (24) within which an air bag can be stored and from which an air bag is deployed. The lining member (25) being flexible to allow inward deformation in contact with an occupant but being sufficiently robust to resist outward bulging of a part of the canister constituted by that lining member (25) as the air bag is deployed from the stowage space (24).

Description

AN AIR BAG ARRANGEMENT The present invention relates to an air bag arrangement and in particular to such an arrangement used in a motor vehicle.

It is now common to include a rapidly deployable air bag within a motor vehicle to protect occupants from injury during vehicle collisions. These air bags must be located to enable appropriate deployment towards the occupant. Thus, the air bag is stowed in a canister generally located about that occupant, for example above the occupant's knees.

Unfortunately, air bags generally are stowed within and deployed from an arrangement which includes a relatively robust storage canister. These canisters being located adjacent to an occupant will, despite the best efforts of the deployed air bag, still present a relatively hard surface upon which an occupant may be injured during a vehicle collision and which may foul other occupant safety features.

It is an object of the present invention to provide an air bag arrangement which avoids that arrangement presenting a hard surface upon which a vehicle occupant may become injured or which may interfere with other occupant safety features such as collapsible panels.

In accordance with the present invention there is provided an air bag arrangement for a vehicle, the arrangement including a canister frame and a lining member which combine to form a canister within which an air bag is stowed and from which that air bag is deployed, the lining member providing at least part of a wall of the canister but is flexible to deform under inward impact to the canister whilst sufficiently robust to inhibit outward bulging as the air bag is deployed therefrom.

The lining member may form one side of the canister or constitute an"L"or a "section located within the canister frame. Alternatively, the lining member may comprise a complete tailored pocket to fit within the canister frame.

The canister frame may have a lipped edge to provide appropriate engagement grip with the lining member in order to secure it to the frame and so inhibit outward bulging of that lining member as the air bag is deployed.

Typically, the canister frame will at least include one window section which is covered by the lining member in order form part of the canister wall and so provide the canister for stowage of an air bag.

The canister will generally have a displaceable lid which is displaced upon deployment of the air bag therefrom.

The lining member generally engages at least one top edge of the canister frame in order to provide part of the wall of the canister.

The lining member will typically be reinforced in order to achieve the necessary flexibility to deformation under inward impact, particularly after the air bag has been deployed, whilst being sufficiently robust to inhibit outward bulging as the air bag is deployed from the canister. This reinforcing may be provided through a mesh, which may be integral with the lining or located as a backer layer to a lining sheet so that the whole forms the lining member. This mesh may be tensioned during the air bag deployment episode in order to facilitate robust inhibition of"outward"bulging as the air bag is deployed.

The lining member may engage edge anchors about the canister frame which inhibit outward bulging of the lining member as the air bag is deployed whilst enabling release under inward impact to the canister.

An embodiment 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 front perspective view of a previous air bag arrangement; Figure 2 is a pictorial front perspective view of an air bag arrangement in accordance with the present invention; Figure 3 is a schematic cross-section of the air bag arrangement as depicted in Figure 2; and Figure 4 is a schematic cross-section of an alternate manner for securing a lining member to a canister frame.

Figure 1 illustrates, in pictorial front perspective, a known air bag arrangement. Thus, an air bag arrangement 1 comprises a canister 2 with a displaceable lid 3 within which is defined a storage space 4 for an air bag (not shown). This air bag, in use, will also be associated with appropriate deployment mechanisms which will generally precipitate release of an expansion gas. Thus, the displaceable lid 3 is displaced from its association as depicted in Figure 1 with the canister 2 to enable that air bag to be presented to a vehicle occupant.

It will be noted that the canister 2 essentially comprises at least a U-shaped section formed from a metal or robust plastic material. Thus, such a canister 2, when located within a motor vehicle after deployment of an air bag from the space 4 presents a relatively hard surface which may cause injury to an occupant.

Clearly, when such a canister 2 is located adjacent an occupant of a vehicle which is deformed and crushed as a result of a-vehicle collision, such hard surfaces significantly increase the danger of injury to that occupant.

Of particular concern with regard to the present invention is where the canister 2 is located about and above an occupant's knee area. In such circumstances, it will be appreciated that as the vehicle deforms under impact, the occupant's knees will be brought into relatively severe impact abutment with the lower part of the canister 2. Regrettably, as the air bag is deployed from the space 4, it will be understood that it is generally necessary to ensure that the canister 2 remains relatively robust and dimensionally stable. If the canister 2 was made flexible, then as the air bag expands from the canister 2, the lower surface of that canister 2 would, in any event, be propelled towards an occupant precipitating injury.

An air bag arrangement in accordance with the present invention is depicted in Figure 2. In this arrangement 21, an air bag canister is provided by combination of a canister frame 22 and a lining member 25. Thus, the canister constituted by the frame 2 and the lining member 25 defines an air bag stowage space 24 from which an air bag can be deployed by displacement of a lid 23. In such circumstances, air bag deployment in accordance with the present invention is similar to that with regard to a conventional arrangement and as depicted in Figure 1. However, a window section 26 defined in the canister frame 22 is closed only by the lining member 25.

The lining member 25 is formed from a flexible sheet. Typically, this flexible sheet will be a cloth or reinforced plastics material. In such circumstances, the lining member 25 is flexible but has a relatively high resistance to extension such that as the air bag is deployed from the space 24, there is a resistance to outward bulging through the window section 26. It will be understood, that as the lining 25 is relatively inextensible, the desire to bulge as a result of air bag deployment is resisted and, in any event, as the lining 25 is flexible, any abutment contact may be susceptible to distortion in contact with the occupant with less potential for injury to the occupant.

In order to ensure outward bulging of the lining member 25 is limited, it is necessary to provide appropriate fixing to secure the lining 25 to the canister frame 22. Thus, where the lining 25 assumes a U-shaped cross-section as show in figure 1, the top edges 27,28 of the frame 22 will be configured to allow the lining member 25 to fold over and robustly engage these edges 27,28. The edges 27,28 may have lips to grip the lining member 25. The lining member 25 may be secured to these edges 27,28 using a beading strip (not shown) with mechanical fastening means passing through the edges 27,28 and the lining member 25 along with the beading strip. Alternatively, the lining member 25 may be secured to the canister frame 22 using an adhesive or other appropriate means.

In principle, the lining member 25 and the canister frame 22 need to combine to define the storage space 24. Thus, as depicted in Figures 2 and 3, it is most convenient if the lining member 25 is in the form of a U-shaped section. Such a Ushaped cross-section maximises the containment effect against the air bag as it is deployed under inflation from the space 24. However, it will also be understood that, in order to provide the space 24 in essence all that the lining member of the present invention must do is close a window section in the canister frame 22. In such circumstances, it will be appreciated that the lining member 25 can take the form of a single flat sheet of material or an L-shape or a complete tailored pocket lining for the canister frame 22. In any event, the lining member 25 must be appropriately secured to the canister frame 22 in order to prevent or inhibit bulging of the lining member 25 under air bag deployment inflation.

Once an air bag is deployed from the space 24 in accordance with the present invention, it will be appreciated that the lining 25 through the window section 26 is all that a vehicle occupant will substantially contact under abutment. Thus, as the lining member 25 is flexible, there is little danger of hard impact injury as a result of that abutment. Clearly, prior to air bag deployment from the space 24, the lining member 25 will at least be held on or supported by any air bag stowed within the space 24. In such circumstances, the inward deformation of the lining 25 may be limited by engagement with the air bag stowed within the space 24.

However, as this will be during normal driving conditions when the danger of injury from abutment impact is limited there is no detrimental effect upon the utility of the present air bag arrangement. Furthermore, it will be understood that the lining member 25 itself or a separate easily detachable or displaceable cover may be located over the window 26 to ensure aesthetic consistency with motor vehicle interior surfaces or structures.

In order to render the lining member 25 flexible to prevent impact abutment injury with an occupant whilst adequately robust to prevent bulging deformation as an air bag is deployed, it will be appreciated that the lining member 25 will typically comprise a reinforced sheet of material. This reinforced sheet of material may incorporate a cloth, woven or non-woven, to provide reinforcement to a plastic impregnant or extrusion. However, as it is not imperative that the lining member 25 should be gas-tight, a simple cloth sheet may be acceptable provided it has adequate strength. In such circumstances, the lining member 25 could be made from a wide range of sheet materials including chain mail formed from metal links or a sheet of extruded plastics material. It is the requirement for resistance to extensivity whilst being flexible which is the paramount determinant upon the acceptability of a material sheet for the lining member 25. It will also be understood that the thickness of the material necessary to provide an adequate lining member 25 will also be a consideration in view of the desire to make the overall dimensions of the air bag arrangement as small as possible for easier accommodation within the relative confined spaces of motor vehicle interiors.

Reinforcing of the material from which the lining member 25 is made will typically take the form of a mesh or fabric as described above. This mesh or fabric may be integral within a thickness of the lining material 25 or comprise a backing layer to a sheet material used to form the lining member 25. In any event, the reinforcing mesh or fabric within the lining member 25 may be static or active under air bag deployment. In a static embodiment, the mesh used to reinforce the lining member 25 would simply resist extension deformation and depend upon the appropriate secure anchoring of the lining member 25 to the canister frame 22 to inhibit outward bulging as the air bag is deployed. In an active embodiment, the mesh used to reinforce the lining member 25 will be tensioned as the air bag is deployed from the stowage space 24 in order to counter-act the bulging pressures precipitated by that air bag deployment expansion. This tensioning of the mesh would be initiated as the air bag is deployed from the space 24 but released after full air bag deployment in order to allow the lining member 25 to return to its flexibility necessary to avoid impact injuries with a vehicle occupant.

The present air bag arrangement, in short, allows inward deformation under impact with an occupant, eg. their knees whilst presenting a sufficiently robust arrangement to inhibit outward bulging as the air bag is deployed in order to prevent any progressive bulging itself precipitating injury to that occupant. As indicated above, in such circumstances it is necessary to differentiate between outward and inward displacement of the lining member 25.

An approach to achieving the above described opposing requirements is as illustrated in Figure 4. Thus, a canister frame 32 defines a window section 36 which will normally be that wall portion of the canister towards a vehicle occupant. This window section 36 is closed by a lining member 35 such that a stowage space 34 therebehind is available in which an air bag can be stowed and from which that air bag can be deployed as required. In order to anchor the lining member 35 about the window section 36, the canister frame 32 includes anchor pegs 33. These anchor pegs 33 enter and engage apertures in the lining member 35. In such circumstances, an outward bulging load presented in the direction of arrow head A is resisted by this engagement between the anchor pegs 33 and the lining member 35 whilst an abutment impact with an occupant in the direction of arrow heads B will lift the lining member 55 from the anchor pegs 33 and so allow inward deformation and flexibility avoiding injury.

Those skilled in the art will appreciate there are a wide range of techniques and manners for appropriate securing of the lining to the canister frame. Thus, an appropriate adhesive or gripper members could be used.

Although the present invention has been described with regard to a single window section in canister frame, it will be understood that a window section could be provided in each wall surface of a canister frame such that the lining member constitutes at least part of that wall in order to define a stowage space therebeneath for an air bag.

Although the present invention has been described with regard to actual occupant contact with the air bag arrangement, it will be appreciated that the present air bag arrangement could be used where it is predicted that other deforming or displacing panels or components within a vehicle may foul or abut the air bag arrangement such that this interaction between the air bag arrangement and those other vehicle panels or components does not precipitate dangerous impact seizure. It will be understood that, generally speaking, some motor vehicle panels and components will include in their design the ability to deform over a predicted deformation depth or length in order to gradually rather than abruptly absorb impact energy and so reduce the prospects of traumatic arrest injury to an occupant. Any fouling between components, as these deformations take place, will thus reduce the energy absorbing capabilities of the occupant safety features of the vehicle.

Claims

CLAIMS 1. An air bag arrangement for a vehicle, the arrangement including a canister frame and a lining member which combine to form a canister within which an air bag is stowed and from which that air bag is deployed, the lining member forming at least part of a wall of the canister and being flexible to deform under inward impact to the canister but sufficiently robust to inhibit outward bulging as the air bag is deployed therefrom.
2. An arrangement as claimed in Claim 1, wherein the lining member is a flat sheet panel or has a U-shaped cross-section or has an L-shaped cross-section or is a tailored pocket to fit the canister frame and so forms at least part of a wall of the canister defined by that canister frame.
3. An arrangement as claimed in Claim 1 or Claim 2, wherein the canister frame includes at least one window section closed by the lining member in order to form at least part of a wall of the canister formed by combination of the canister frame and the lining member.
4. An arrangement as claimed in Claim 1,2 or 3, wherein the canister frame has upper edges which are lipped in order to facilitate securing of the lining member thereto.
5. An arrangement as claimed in any preceding claim, wherein the arrangement includes a displaceable lid secured across the canister and displaceable upon deployment of the air bag therefrom.
6. An arrangement as claimed in any preceding claim, wherein the lining member includes reinforcing means in order to facilitate robust inhibition of outward bulging as the air bag is deployed from the canister.
7. An arrangement as claimed in Claim 6, wherein the reinforcing means may be tensioned as, or just prior, to deployment of the air bag from the canister in order to further inhibit outward bulging as that air bag is deployed therefrom.
8. An arrangement as claimed in any preceding claim, wherein edge anchors are located about the canister frame in order to engage and secure the lining member against outward bulging of that part of the wall constituted by the lining member as the air bag is deployed from the canister.
9. An air bag arrangement substantially as hereinbefore described with reference to Figures 2 to 4.