THE PRESENT INVENTION relates to a cover for an air-bag.

Many motor vehicles are now provided with one or more air-bags adapted to be inflated in the event that an accident should arise, to provide some protection for the driver (and possibly front-seat passenger) in the vehicle. Such air-bags are typically mounted within the hub of the steering-wheel, or within the dash-board, in a recess provided for that purpose. An exterior cover for the recess is provided, which forms the central part of the steering-wheel or part of the dash-board. The cover typically comprises a panel having split or break lines which define one or more flaps or doors within the cover. These flaps or doors are intended to open when the bag is inflated, thus permitting the bag to escape from the recess and be in an appropriate position to protect the driver or passenger in the vehicle when an accident arises. If the cover comprises a laminate of several layers, as is conventional, such as a carrier layer, a foam layer and an outer skin, all these layers have to be split along the edges of the flaps or doors, along split lines, and such split lines will usually be visible from the exterior of the panel. This is undesirable.

EP-A-0,358,230 discloses one attempt to solve this problem in which the whole cover opens in the manner of a hinged lid, rather than the cover being provided with

separate flaps or doors defined by split or break lines. One side of the cover is mounted on an inwardly directed flange adapted to be connected to a housing that initially contains the air-bag, the upper part of the flange forming a hinge to allow hinged opening of the cover. The other side of the cover is initially held in position by a plurality of spaced apart fingers. The spaced apart fingers are each connected to the underside of the cover by areas of significantly reduced thickness. The free ends of the fingers are inter-connected by a panel adapted to be connected to the housing. The intention is that these areas of significantly reduced thickness will break or snap when the air-bag is inflated, thus allowing the cover panel to hinge open in the manner of a lid.

Two disadvantages arise from the arrangement disclosed in EP-A-358,230. The first disadvantage is that relatively complex tooling has to be used to mould the structure described in that prior publication. It is not possible to use a simple two-part mould, but instead a complex multi-part mould has to be used. It is, in any event, difficult to mould the areas of the fingers of reduced thickness with any real accuracy. A further disadvantage is that the separate tongues and the areas of reduced thickness do not provide rigid support for the part of the cover panel that they engage. Thus, this part of the cover panel may, in use of the motor vehicle, vibrate or "wobble". This is clearly undesirable.

The present invention seeks to provide an improved cover for an air-bag.

According to this invention there is provided a cover for an air-bag, the cover including a carrier comprising a main part having a flange formed integrally

therewith at or adjacent one edge thereof, which flange extends substantially perpendicularly from the lower face thereof, the flange being provided with means to connect the flange to a housing or the like containing an air-bag to keep the cover in a closed position until the air-bag is actuated, the upper face of the main part of the carrier being provided with a plurality of recesses substantially aligned with the flange.

The recesses, being substantially aligned with the flange, serve, at the very least, to reduce the thickness of the material connecting the flange to the main part of the cover at least in the region of the recesses. It is therefore envisaged that, when an air-bag provided with a cover as described above is actuated, the material joining the flange to the rest of the main part of the carrier will fracture, permitting the cover to open. It is envisaged, however, that the flange will extend over substantially the entire width of the carrier, thus providing significant support for the cover. It is also envisaged that the carrier may be moulded using relatively simple moulding tools.

Preferably the recesses are distributed along the entire length of the flange. The recesses may be evenly distributed or may be un-evenly distributed. If the recesses are distributed along the entire length of the flange there will no tendency for one part of a flange to be more securely connected to the main part of the cover than any other part of the flange.

Preferably the depth of each recess is less than the thickness of the main part of the carrier, but alternatively the depth of each recess may be at least equal to the thickness of the main part of the carrier.

Each recess may be of any desired shape, but preferably each recess is of circular or substantially circular form, the diameter of each such circular recess being greater than the width of the flange.

Preferably the flange is spaced from the said edge of the main part of the carrier and is substantially parallel to the said edge of the main part of the carrier. Alternatively, however, the flange may be substantially aligned with the said edge of the main part of the carrier.

Conveniently, the cover is designed so that, in operation of the air-bag, the flange separates from the main part of the carrier, but the main part of the carrier, on both sides of the flange, retains its integrity.

Preferably the cover comprises a foam layer with an exterior skin layer, the foam layer and the skin layer being mounted on the carrier.

The cover may be provided with means defining a hinge extending along the edge of the cover opposed to the flange.

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 sectional view taken on line A-A of Figure 2 of part of carrier for a cover for an air-bag,

FIGURE 2 is a top view of part of the carrier of Figure 2,

FIGURE 3 is a sectional view illustrating the carrier, in the form of Figure 1, as part of a complete cover for an air-bag,

FIGURE 4 is a sectional view, corresponding to Figure l, of a carrier intended to form part of an alternative embodiment of the invention taken on line B-B of Figure 5, and

FIGURE 5 is a top plan view of part of the carrier of Figure 4.

Referring initially to Figures 1 and 2 of the drawings, a carrier 1 which is to form part of a cover for an air-bag is moulded from a substantially rigid plastics material. The carrier 1 comprises a main part in the form of an upper substantially planar portion 2, having a free edge 3. At the side opposed to the free edge 3 this planar portion 2 is adapted to be mounted in position so that the planar portion 2 may hinge in the manner of a lid, with the free edge 3 of the planar portion moving generally as indicated by the arrow 4. This may be accomplished by providing a depending flange with a region of reduced thickness adjacent the point where the flange is connected to the planar portion 2. Alternatively, the flange may be of uniform thickness, with that thickness being selected so that the flange can bend to provide a hinge effect.

Adjacent the free edge 3 of the planar portion 2, there is a depending integral flange 5 which extends in a substantially unbroken form substantially across the entire width of the planar portion 2, parallel with the free edge 3. The flange 5 extends substantially perpendicularly from the lower face of the planar portion 2. Towards its lower edge the flange 5 is provided with a plurality of

through-bores 6 adapted to receive rivets or the like to secure the flange in position on a housing defining a recess which contains an air-bag.

A plurality of recesses 7 are formed in the upper surface 8 of the planar portion 2. The recesses 7 are each of circular form. The diameter of each recess is greater than the thickness of the depending flange 5. The centres of the recesses are aligned with the centre of the depending flange 5 so that each recess 7 is located directly above the depending flange 5, with parts of the recess extending beyond either side of the depending flange 5.

The recesses 7 are uniformly spaced apart, there being regions 9 of the planar portion 2 located between adjacent recesses 7.

The depth of each recess 7 is slightly less than the thickness of the planar portion 2.

As can be seen from Figure 1 there are thus relatively thin regions of plastic material 10 extending from the top of each depending flange 5 to the rest of the planar portion 2 in the region of each recess 7.

The carrier 1 is intended to form part of a cover for an air-bag as is shown more clearly in Figure 3. A foamed material 11 is moulded in position to engage the upper surface 8 and the free edge 3 of the carrier 1, the foamed material being provided with an exterior protective layer or "skin" 12. Since the recesses 7 do not fully penetrate the planar portion 2, no foam can pass through the recesses during the moulding of the foamed material 11.

The cover illustrated in Figure 3 is intended to be mounted in position on a housing defining a recess containing an air-bag. When the air-bag is inflated, the flange 5 becomes separated from the rest of the carrier 1, thus permitting the cover to hinge upwardly in the manner of a lid, as indicated generally by the arrow 4 in Figure 3. The relatively thin areas of plastic 10 between the top of the flange 5 and the rest of the planar element 2 will snap, and also the portion of the flange 5 secured to the under-surface of the planar element 2 in the regions 9 between the adjacent apertures 7 will also snap. It may be appropriate for the apertures 7 to be quite close together. It is to be appreciated that the design is such that the flange 5 becomes separated from the main part of the carrier, constituted by the planar portion 2. The planar portion 2 retains its integrity, the region defining the free edge 3 remaining connected to the rest of the planar portion 2 by virtue of the regions 9 between the recesses 7.

It is to be understood that the flange 5 is an integral flange which extends over substantially the entire width of the cover. Whilst the flange may be provided with one or more vertically extending slits, the intention is that the flange should extend under substantially the whole of the width of the carrier element 1 is a substantially unbroken form, thus providing substantially rigid support for the cover.

Figure 4 illustrates a carrier 1' comprising a modified embodiment of the invention. The same reference numerals are used in Figure 4 for those parts which are common with the embodiment of Figure 1 and these parts will not be re-described in detail.

In the embodiment of Figure 4 there are two major differences as compared with the embodiment of Figure 1. Firstly, it is to be observed that the depending flange 5 has been located so that the outward face 13 thereof is substantially flush with the free edge 3 of the planar portion 2 of the carrier 1• . The recesses 7' are still of substantially circular form and are still aligned with the flange 5, meaning that the recesses are thus only part circular, as can be seen from Figure 5, since the side wall of each recess intersects the free edge 3 of the planar portion 2.

The second major difference is that the depth of each recess 7 ¹ is at least equal to the thickness of the planar portion 2, and indeed may slightly exceed the thickness of the planar portion 2. Thus each recess 7' may be considered as an aperture through the planar portion 2. Thus, in the region 14, which is equivalent to where the plastics of reduced thickness 10 was provided in the embodiment of Figure 1, between the top of the flange 5 and the rest of the planar element 2 in the region where a recess 7 is provided, in the embodiment of Figure 4 there is no plastic material at all.

Thus, in the embodiment of Figure 4, the flange 5 is not connected at all to the planar element 2 in the region of the recesses 7* , but is only connected to the planar element 2 in the regions 9 located between adjacent recesses 7• .

Because the flange 5 extends substantially over the entire width of the cover, this flange still provides very significant strength and rigidity to the carrier element 1■ . On actuation of the air-bag the flange 5 will

break away from the planar portion 2, the plastic material present in the regions 9 snapping.

It is to be appreciated that the carrier element 1' of Figures 4 and 5 will be provided with a foam layer and outer skin corresponding to the foam layer 11 and outer skin 12 of Figure 3. The apertures effectively defined in the regions 14 will have to be blocked by appropriate means during the moulding of the foamed material.

It is to be appreciated that both of the carriers described above may be moulded using a relatively simple two-part mould, that two-part mould carrying pins adapted to project into the mould to form the apertures 6 present in the flange 5. The mould used to form the carrier of invention may thus be much simpler than the mould used to form the carrier of the prior art discussed above.