Land vehicles – Wheeled – Attachment
Reexamination Certificate
2002-04-30
2003-11-25
English, Peter C. (Department: 3616)
Land vehicles
Wheeled
Attachment
C280S732000
Reexamination Certificate
active
06651998
ABSTRACT:
The invention relates to a safety covering for an airbag.
Airbag coverings on interior trim panels of motor vehicles in which the lining comprises a dimensionally stable supporting part and a decorative layer, which are interconnected by a foam layer, are frequently designed in prior art as “invisible” coverings. Here through a rear-side cross-sectional weakening of the supporting part and generally also of the decorative layer, a single- or double-bladed “flap” is produced which is burst open by the opening (inflated) gas bag of the airbag system. Of the many publications which go deeper into this prior art, let DE 196 46 548 be mentioned, from which a comprehensive overview of this prior art can be taken. In this process, the burst- open flaps point towards the interior of the vehicle; they therefore contain an injury risk in the case of impact with a person. In DE 196 46 548, it is proposed, in order to reduce the risk of injury, that the aperture through which the gas bag passes should be designed not in the shape of a flap, but in a “pointed oval” shape, similar to a fish's mouth. Since however the tearing edges of the supporting part also arch towards the passenger compartment, the injury risk in relation to the flap disintegration is admittedly reduced, but not completely eliminated.
Another attempt at solving the problem is quoted in EP 867 346 A1. A component set in motion, which is a constituent part of the airbag device and is brought into motion before the expansion of the gas bag, actuates the airbag covering in such a way that the flaps of the covering move substantially within the outer contour of the airbag device. The examples listed in this publication show an actuating mechanism which has positive guiding of the flaps with the aid of traction cams and link guides. Such a solution renders considerably more difficult the one-piece production of a trim panel through the previously standard foaming together of the supporting part and the decorative layer, since it is not possible to foam in the traction cams and the link guides. The attachment of covering devices and the airbag device also requires difficult assembly work since the propulsion channel of the gas bag and the covering predetermine an enclosed space which is difficult to access from outside. Finally forces of inertia affect the traction and guide cams of the covering in addition, since the opening movement has to take place before the inflation of the airbag device, and this in a matter of milliseconds. The solution proposed by EP 0 867 346 A1 also requires special airbag devices having an integrated drive device; the previously used devices cannot be employed.
The object of the present invention is to provide an “invisible” airbag covering in interior trim panels of vehicles,
which renders possible simple and reliable production by foaming together the supporting part and decorative layer,
which ensures that no material portions of the supporting part reach the passenger compartment and represent an injury risk there,
which makes it possible to use airbag devices of conventional design, and
which also continues to function reliably at high component accelerations and the acceleration forces resulting therefrom.
This object is accomplished by providing the safety covering with a capture chamber for the tear-off region of the supporting part, and for the separated material of the foam layer, which capture chamber has a guide edge configured as a roller for a traction strip. Because, in the region of the safety covering delimited by cross-sectional weakening and/or material separation in the supporting part, the material of the supporting part and at least parts of the foam layer can, before the gas bag unfolds, be removed from its effective area and be brought behind the interior trim panel. On the one hand the occupants are reliably protected against damaging edges, and secondly the “Propulsion channel” of the gas bag can be kept free of components such as guide lugs, clams or flap edges, components which harm the inflating gas bag or at least impair its functioning.
When the material portions of the supporting layer and at least parts of the foam layer have been removed from the effective area of the gas bag, the decorative area still covers the gas bag aperture. Under the term “decorative layer” are to be understood all the materials which are standard in prior art, such as pre-moulded thermosetting foils and sintered slush skins. These decorative foils can be easily penetrated by the gas bag, particularly if they have cross-sectional weakenings in the penetration region. Such cross-sectional weakenings can be mechanically produced scorings of the rear side of the decorative layer, but to an increasing extent are also micro-perforations which are introduced with the aid of laser beams. Since the cross-sectional weakening can be of any predetermined type, the tearing characteristics of the decorative layer can be influenced and thus also the unfolding characteristics of the gas bag. The decorative layer has firstly a lower mass, secondly it consists of a soft, yielding material, such that under standard operating conditions it represents no danger of injury for the occupants and no risk of damage to the gas bag.
Removing the supporting part material from the effective area of the unfolding gas bag can advantageously come about in that this region of the supporting part is securely connected, approximately over its entire width, on the rear side to a correspondingly wide traction strip, which engages parallel to a cross-sectional weakness predetermining the tear-off region, and specifically with a tractive force directed approximately perpendicular to the supporting part, which force is applied by a traction device which can be released by a driving situation sensor. The flat attachment of the tear-off region has the advantage of optimum introduction of force with simultaneous minimisation of the masses to be moved, by which means the ability of the arrangement to function remains guaranteed even in the case of high accelerations. The traction strip can be guided in a simple manner in such a way that it engages approximately perpendicular to the supporting part surface (in the direction of the surface normal), by which means reliable tearing along the cross-sectional weakening can be achieved, at least the traction strip can introduce much higher forces than for example cam followers maintain in a link guide. The traction strip is preferably glued flat and connected to the corresponding region of the supporting part. In the area of introduction of force, the peeling tensions occurring during adhesion can be absorbed by additional measures, for example by a row of rivets.
If no additional constructional measures are provided, the separation of the supporting part tear-off portion from the decorative layer takes place in the foam layer which has the lowest material strength in the system composed of supporting part/foam/decorative layer. A portion of the foam will, since the tearing of the foam layer takes place in an uncontrolled manner, remain on the decorative layer and can reach the passenger compartment with the gas bag. This can be counteracted by the decorative layer being provided on the side remote from the visible side in the airbag region at least partially with an adhesion-lessening coating, which makes it easier to detach the foam layer from the decorative layer. A further possibility consists in extending the traction strip into the foam layer; a design which causes for example no constructional difficulties if a material separation delimits one side of the tear-off region. The region of the traction strip extending into the foam here expediently runs. closely below the decorative layer. Two modes of operation are possible:
1. The traction strip area in the foam defines a tear zone in the foam (weak point function).
2. The traction strip region in the foam is securely connected to the rear side of the decorative layer (function as a tearing aid for the decorative layer).
In the sec
Jahn Thomas
Mayer Wolfgang
Skowronnek Jürgen
English Peter C.
SAI Automotive SAL GmbH
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