Land vehicles – Wheeled – Attachment
Patent
1996-10-23
1998-06-30
Dickson, Paul N.
Land vehicles
Wheeled
Attachment
280732, B60R 2116
Patent
active
057722404
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to an air-bag arrangement.
BACKGROUND OF THE INVENTION
It has been proposed to provide an air-bag in a motor vehicle, means being provided to inflate the air-bag in the event that an accident should arise, the inflated air-bag providing protection for the driver of the vehicle or a passenger in the vehicle.
The air-bag is, prior to use, usually concealed behind a cover. The cover may form the central part of a steering wheel, if the air-bag is intended to provide protection for the driver of the vehicle, or the cover may form part of the dash-board of the vehicle, if the air-bag is to provide protection for a passenger within the vehicle.
Typically, an air-bag cover is made of a laminate of two layers of plastics material. The inner layer is relatively stiff and hard and provides the cover with the desired degree of strength, and the outer layer is softer, sometimes being made of a foam with an outer "skin".
The inner layer is such that the entire cover forms an integral part of the central part of the steering wheel or forms an integral part of a dashboard. The outer layer is to provide the usual degree of comfort that is found in a motor vehicle.
It is necessary to provide the cover with a line of mechanical weakness, so that, when the air-bag is inflated one or more parts of the cover form "doors" which hinge outwardly when subjected to a predetermined pressure to permit the air-bag to be inflated in the desired manner. This is usually achieved by providing a line of mechanical weakness or a "splitline".
FIG. 1 in the accompanying drawings comprises a sectional view through part of a typical present-day air-bag cover. The inner layer 1 comprises a relatively hard plastic material such as a thermoplastic elastomer and has a region 2 where the thickness of the layer is substantially less than in the remaining parts of the layer. The region 2 thus comprises a line of mechanical weakness. The region 2 is also deformed upwardly.
The layer 1 of thermoplastic elastomer supports an upper outer relatively thick layer 3 which may also be formed of thermoplastic elastomer, although the elastomer may be relatively soft, and it can be seen that, because of the deformed configuration of the inner layer 1, in the region 4 the layer of polyurethane foam 3 also has a reduced thickness. The region 2 is aligned with or overlies the region 4 and this combined region thus comprises a "splitline". A portion of the cover to one side of the splitline (or portions on both sides of the splitline) may open in the manner of a "door" when subjected to a predetermined pressure as the air-bag is inflated.
It has been found that when a cover of this particular type is manufactured, even though the outer surface of the outer layer is substantially smooth, nevertheless the precise location of the "splitline" constituted by the regions 2 and 4 of reduced thickness, is clearly visible. This can be unsightly.
It has been proposed to avoid the unsightliness by providing, as shown in FIG. 2, a depressed "style line" 5 in the outer surface of the outer layer 3 of the cover. However, this does mean that the pattern of the "style" lines 5 has to coincide with the pattern defined by the lines of mechanical weakness, and such a pattern may not be aesthetically pleasing and, especially where the air-bag cover forms part of the dashboard, may look very much "out of place".
SUMMARY OF THE INVENTION
The present invention seeks to provide an improved air-bag arrangement.
According to this invention there is provided a cover for an air-bag, the cover comprising a laminate consisting an inner layer of polymer material and an outer layer of polymer material, each layer being provided with a line of mechanical weakness, the line of mechanical weakness in the outer layer being displaced at least 2 millimeters relative to the line of mechanical weakness in the inner layer, these splitlines together defining a door in the cover adapted to open when a predetermined pressure is provided from the insid
REFERENCES:
patent: 4903986 (1990-02-01), Cok et al.
patent: 4989895 (1991-02-01), Pearson et al.
patent: 5082310 (1992-01-01), Bauer
patent: 5110647 (1992-05-01), Sawada et al.
patent: 5143401 (1992-09-01), Zushi
patent: 5172931 (1992-12-01), Baba et al.
Autoliv Development AB
Dickson Paul N.
LandOfFree
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