U.S. patent application number 09/728660 was filed with the patent office on 2001-04-26 for airbag cover.
This patent application is currently assigned to TRW Automotive Safety Systems GmbH. Invention is credited to Kreile, Holger.
Application Number | 20010000418 09/728660 |
Document ID | / |
Family ID | 8048572 |
Filed Date | 2001-04-26 |
United States Patent
Application |
20010000418 |
Kind Code |
A1 |
Kreile, Holger |
April 26, 2001 |
Airbag cover
Abstract
An airbag cover for an airbag unit in a motor vehicle is adapted
to be torn open along predetermined lines on sudden inflation of
the airbag to swing open in one or more parts along hinge lines.
The cover is composed of two or more layers. A full-length tear
line intended as a predetermined breaking line is provided only in
the first layer on the side of the airbag.
Inventors: |
Kreile, Holger; (Elsenfeld,
DE) |
Correspondence
Address: |
Tarolli, Sundheim, Covell
Tummino & Szabo LLP
1111 Leader Building
526 Superior Avenue
Cleveland
OH
44114-1400
US
|
Assignee: |
TRW Automotive Safety Systems
GmbH
|
Family ID: |
8048572 |
Appl. No.: |
09/728660 |
Filed: |
December 2, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09728660 |
Dec 2, 2000 |
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09190088 |
Nov 12, 1998 |
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6199897 |
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09728660 |
Dec 2, 2000 |
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09084707 |
May 26, 1998 |
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6170860 |
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Current U.S.
Class: |
280/728.3 |
Current CPC
Class: |
B60R 21/2165
20130101 |
Class at
Publication: |
280/728.3 ;
280 |
International
Class: |
B60R 021/16 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 13, 1997 |
DE |
297 20 138.7 |
Claims
What is claimed is:
1. A cover for an exit opening of an airbag unit in a motor
vehicle, the cover being adapted to be torn open along
predetermined lines on sudden inflation of the airbag to swing open
along hinge lines, the cover comprising at least two layers, and
only a first one of said layers having a full-length tear line
intended as a predetermined breaking line.
2. The cover according to claim 1, wherein a partial tear line
intended as a predetermined breaking line is provided in a second
one of said layers.
3. The cover according to claim 2, wherein the tear line of the
second layer is at least partially coincident with the tear line in
the first layer.
4. The cover according to claim 3, wherein the tear line of the
second layer is at least partially coincident with a portion of the
tear line in the first layer which tears open first.
5. The cover according to claim 4, wherein the first layer consists
of a harder material than the second layer.
6. The cover according to claim 5, wherein the first layer is
located internally adjoining the airbag.
7. The cover according to claim 6, wherein the second layer
consists essentially of the same material as an upper layer of an
installation surrounding of the cover.
8. The cover according to claim 1, wherein a third layer and each
of any further layers have no predetermined breaking line.
9. The cover according to claim 1, wherein a third layer and each
of any further layers have a predetermined breaking line which is
not longer than the predetermined breaking line in the second
layer.
10. The cover according to claim 1, wherein the layers are
interconnected by one of the group of methods consisting of
bonding, mechanical assembling, pressing and injection molding.
Description
1. The present invention relates to an airbag cover which closes an
exit opening of an airbag unit in a motor vehicle.
2. Usually, such covers are visually and haptically adapted to
their installation surrounding. Insofar as a driver airbag is
concerned, the cover has to be matched to the surface structure and
colour of the steering wheel sheating. Front passenger airbags are
arranged below the instrument panel so that the surface of the
cover has to correspond with the surface of the instrument panel as
far as possible. The situation is similar for side airbags and all
other airbags to be installed in motor vehicles.
3. It can easily be understood that adapting the cover to its
installation surrounding often poses great problems, because the
latter possibly consists of materials which are not or only partly
suitable for manufacturing a cover. Typical covers are therefore
configured normally with two or more layers, the internal layer
being provided with the required structural strength, whereas the
outer layer is taylored so as to adapt to the installation
surrounding. In most cases, the cover is a part of a separate
airbag module which is designed for the installation on a steering
wheel, an instrument panel or other internal parts of a car body.
In these cases, the cover is often designated as "cover cap", the
circumferential edge of which is adapted to the size of the
installation opening and the tear area of which, in contrast, is
smaller.
4. An airbag cover may constitute an integral component of an
instrument panel or of another internal part for motor vehicle
bodies, where the adaptation to the installation surrounding
generally poses no problems, but wherein the exact positioning of
the tear line and the dimensioning of the predetermined breaking
lines with respect to their strength can become difficult.
5. Hitherto it is assumed that, in the case of airbag covers
configured in two or more layers, the tear lines intended as
predetermined breaking lines have to be arranged in all layers such
that they have the same length and coincide with each other, so
that a defined resistance to tearing can be reproducibly realized
within narrow limits, because in this respect one cannot accept an
incalculable hindrance on the sudden deployment of the airbag.
This, however, can be achieved in the case of covers configured in
two or more layers only with significant production expenses,
because for producing the individual layers separate operating
steps are required and, mostly, also separate form tools.
6. The present invention provides an airbag cover which can be
produced at a far more favorable price, without posing the need of
accepting incalculable resistances on the sudden inflation of the
airbag along predetermined lines.
7. According to the invention, an airbag cover is provided which
consists of two or more layers, a full-length tear line intended as
a predetermined breaking line being provided only in a first one
layer of these layers.
8. Tests have surprisingly brought the result that there is no need
for a full-length tear line in the second layer and that the second
layer in fact tears open independently of the tear line predefined
in the first layer when the airbag is inflated. The dynamic forces
during the tearing process obviously are of more importance than
the static tensile strength so that any resistances to tearing
hardly play a role when the first layer is torn open under the
influence of the gas pressure wave acting in the airbag. Therefore,
it is sufficient to configure a tear line intended as a
predetermined breaking line in the second layer, which tear line is
shorter than that of the first layer. Furthermore, it has been
found that it is sufficient to configure the tear line of the
second layer so as to be at least partially coincident with the
tear line of the first layer.
9. Further details of the invention are explained more clearly with
reference to the embodiments illustrated in the FIGS. 1 and 2, in
which:
10. FIG. 1 shows a first embodiment of the invention in a plan
view.
11. FIG. 2 shows a second embodiment of the invention and likewise
in a plan view.
12. In FIG. 1 there is illustrated a cut-out 5 of an installation
surrounding of an airbag cover 1, which for example could be part
of an instrument panel. The airbag cover 1 is configured in two
layers, a full-length tear line 2 being configured in the first
layer and completed by bending lines 4. On inflation of the airbag
(not shown), the cover 1 tears open at first along the horizontally
extending part of the tear line 2 and then along the vertically
extending lines adjoining thereto at the right and the left so that
the upper and the lower part of the cover 1 can swing open about
the bending or hinge lines 4. The tear line 3 of the second layer
is configured only along the horizontal extent of the tear line 2
in the first layer and is extended so as to protrude at its ends
beyond the vertical line portions by a specific length. It has been
found that a tear line 3 configured in such a way is absolutely
sufficient for ensuring a perfect tearing process. It can easily be
understood that it is much simpler during production to configure
the tear line 3 in the second layer so as to be coincident with the
horizontally extending part only of tear line 2 in the first layer,
as if during production additionally also the vertically extending
sections had to be adapted to each other with respect to their
dimensions.
13. In FIG. 2 an airbag cap referenced by 6 is a component of an
airbag module which is installed in an installation surrounding,
for example, in the steering wheel or instrument panel of a motor
vehicle. The cover 1 is a part of the airbag cap 6 and has in the
first layer a tear line 2 intended as a predetermined breaking line
which is arranged like in the embodiment according to FIG. 1. The
predetermined breaking line 3 in the second layer is configured so
as to correspond only with the horizontal extent of the tear line 2
of the first layer, and is also configured only along part of its
length. Here, too, the upper and lower parts of the cover 1 swing
open about bending or hinge lines 4. Even such a tear line 3 in the
second layer can be sufficient, because the dynamic forces on the
sudden inflation of the airbag are, as has been proved, sufficient
to cause the further tearing of the second layer along any lines as
predefined by the tear lines in the first layer.
14. It should be noted that the extension of the tear lines 2 and 3
as well as of the bending lines 4 is only schematically depicted in
the FIGS. 1 and 2 and that these lines are not visible or
perceptible, at least at the surface facing the passenger
compartment.
* * * * *