Air bag retainer with cutting flaps

A cover assembly for an air bag restraint system has a smooth outer skin with a backing layer of foam located between the outer skin cover and a retainer member. The retainer member is located above the outlet of an air bag casing and includes a plurality of flaps therein each having a pointed end located in a hidden position beneath the foam and outer skin cover and at a point generally centrally of the outlet of the casing. Each of the flaps is connected to the retainer member by integral hinge segments in the retainer member. When the air bag is inflated, it will cause the segments to pivot outwardly about the hinge segments to pierce both the foam layer and the outer skin and peel them apart so as to form a multi-sided opening through the cover assembly for deployment of the air bag.

FIELD OF THE INVENTION 
This invention relates to air bag restraint systems for motor vehicles and 
more particularly to air bag restraint systems which are housed by a cover 
assembly for providing an invisible access door for deployment of the air 
bag following inflation thereof. 
BACKGROUND OF THE INVENTION 
Various air bag restraint systems have been proposed in which an access 
door is arranged behind a continuously formed outer skin or cover. In some 
cases the underside of the outer skin is perforated or weakened. In such 
arrangements as shown in U.S. Pat. Nos. 3,622,176 and 4,246,213 the 
weakened sections represent underlying depressions in the outer cover 
which show as an outline of an access door for an underlying air bag 
assembly. Furthermore, such systems require that the outer cover be torn 
apart at the weakened seams. If the seams are irregular in form the 
opening force will vary and at times may tend to impede the release of an 
air bag. 
In other arrangements, the cover assembly includes a separate cutting 
device that will pierce the outer skin. Examples of such separate cutting 
devices are set forth in U.S. Pat. No. 4,097,064 and copending U.S. 
application Ser. No. 601,406 filed Oct. 22, 1990 now U.S. Pat. No. 
5,035,444. 
SUMMARY OF THE INVENTION 
The present invention includes an invisible cover for an air bag restraint 
system which is easily fabricated using standard foam molding apparatus 
and which has a retainer with integral cutting flaps that pivot in 
response to air bag inflation to peel back segments of a foam layer and 
outer skin to form a deployment opening for passage of the air bag into 
the passenger compartment of the vehicle. 
A feature of the present invention is to preform the cutting flaps in a 
retainer member of a foamed interior trim product of the vehicle of the 
type having an outer skin of plastic material, an intermediate foam layer 
for providing a soft feel and a retainer member for supporting the 
interior trim product within the vehicle; the flaps are formed as separate 
segments in the retainer each having a pointed end for piercing the foam 
and outer skin and each having an integral hinge section at one end for 
allowinq pivotal movement of the flaps so as to peel the foam layer and 
outer skin to form an air bag deployment opening. 
Still another feature of the present invention is to provide a cover 
assembly for concealing an air bag restraint assembly including an air 
bag, a housing for the air bag, a gas generator located in the housing for 
supplying gas to the air bag in response to vehicle impact; the cover 
assembly comprising an outer skin which covers the interior trim product 
and including a backing layer of foam behind the outer skin for supporting 
the outer skin; a retainer member underlying the foam backing layer has a 
portion thereof divided into a plurality of flaps formed therein each 
having pointed ends thereon located centrally of the outlet from an air 
bag housing; each of the flaps are integrally connected to the retainer 
member at a weakened section defining a hinge for pivotal movement to 
cause the pointed ends to penetrate both the foam layer and the outer skin 
to pierce and peel back segments of the foam backing layer and outer skin 
to form an opening therethrough for deployment of an air bag into the 
passenger compartment of a vehicle when inflated by the gas generator. 
A still further feature of the present invention is to provide a cover 
assembly for concealing an air bag restraint assembly including an air 
bag, a housing for the air bag, a gas generator located in the housing for 
supplying gas to the air bag in response to vehicle impact the cover 
assembly comprising: an outer skin covering an interior trim product and 
including a backing layer of foam behind the outer skin for defining a 
surface configuration on the outer skin; a retainer member underlying the 
foam backing layer has a portion thereof divided into a plurality of 
separate triangular flaps having their apexes located centrally of the 
outlet from an air bag housing; each of the triangular flaps has its base 
integrally connected to the retainer at a weakened section hinge line that 
allows pivotal movement of the flaps to cause the apexes to penetrate both 
the foam layer and the outer skin to pierce and peel back segments of the 
layer and outer skin to form an opening therethrough for deployment of an 
air bag into the passenger compartment of a vehicle when inflated by the 
gas generator. 
In the construction of soft foam insert doors a preformed outer skin or 
shell member formed by casting vinyl particles on a heated mold surface is 
seated in a female cavity of a foam mold as setforth in U.S. Pat. Nos. 
4,784,366 and 4,873,032, which are commonly assigned to the assignee in 
the present application, and are incorporated herein by reference. These 
patents disclose how a first retainer member is supported at construction 
holes on the lid of the mold which closes to form a mold space between the 
retainer and the preload vinyl skin. The retainer on the lid can also 
include a port through which foam precursors are directed into the mold 
space for reaction therein to form a cellular foam material that is soft 
to the feel. The resultant structure is removed from the foam mold and 
includes a vinyl skin which can be colored and grained to match the 
aesthetic appearance of the outer vinyl surface of an interior trim 
product such as an instrument panel having a upper opening therein for the 
deployment of an air bag. In the past, the retainer member has been 
weakened at a door segment but has required separate cutters. In the 
present invention, the cutters are formed integral of the retainer. 
Moreover, the integral flaps forming the cutters are hidden from view and 
do not pierce the frame until pivoted in a direction to perform a 
"peeling" of the backing foam and outer cover.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION 
Referring now to FIG. 1, a door assembly for an opening through which an 
inflatable restraint safety device is deployed into a passenger 
compartment is shown at 10. In this embodiment of the invention the door 
assembly 10 is shown in a top mount position and forming a hidden opening 
12 in the surface 14 of a dashboard or instrument panel 16. The door 
assembly 10 is in an underlying relationship to a sloped front windshield 
18. While shown in the upper surface of the instrument panel, the opening 
could also be formed in the front surface 16a of the instrument panel 16 
in what is known as a mid-mount position. The top mount or mid-mount of 
the door assembly 10 depends upon the location of an underlying air bag 
restraint system 20. In the illustrated embodiment of FIG. 1, the air bag 
restraint system 20 includes a gas generator or canister 22 located in a 
canister housing or casing 24 mounted on a suitable vehicle component not 
shown. The gas generator has a plurality of openings 22a through which a 
suitable inflatant gas flows when an impact sensor 26 is actuated upon 
vehicle impact to condition a controller 28 to initiate gas generation all 
as is well known to those skilled in the art. The inflatant is directed 
into the interior of an inflatable air bag 30 connected at one end 30a to 
the casing 24 and having convolutions 30b which expand as the air bag is 
inflated to impact against the underside of the door assembly 10 to cause 
it to peel apart for deployment of the air bag 30 through the opening 12. 
In accordance with the invention, the door assembly includes a vinyl outer 
skin or cover 32 which can be formed from cast vinyl material by processes 
such as those set forth in U.S. Pat. Nos. 4,664,864 and 4,784,911, all 
commonly assigned to the same assignee as in the present application. Such 
outer covers 32 have colors and grain appearances that are accurately 
matched to the appearance of the surface of an associated interior trim 
product such as the illustrated instrument panel. The vinyl outer skin or 
cover 32 has edge portions 32a thereon bent over the peripheral edge of an 
instrument panel retainer 34 of the type which is mounted on a lid of a 
foam mold apparatus such as illustrated and described in U.S. Pat. No. 
4,806,094, commonly assigned to the same assignee as the present invention 
and incorporated herein by reference. 
In accordance with the present invention, the retainer is carried on mold 
apparatus lids and is located thereon so as to form a sealed connection 
with respect to the periphery of the outer skin or cover 32 so as to 
define a space 37 into which foam precursors are directed in a known 
manner for reaction to form a soft feel foam layer 38 behind the cover 32 
The foam layer 38 forms a backing to support the outer cover 32 to produce 
a finished appearance that matches the styling and appearance of other 
associated interior trim components. 
In accordance with one feature of the present invention, the retainer 34 
has diagonally arranged cross openings 34a-34d therein forming the sides 
of four flaps 36, 38, 40 and 42 located in the plane of the remainder of 
the retainer 34. The retainer 34 is connected to vehicle frame members for 
supporting the instrument panel 16 within the vehicle. It is located such 
that the diagonally crossed openings 34a-34d intersect centrally of the 
outlet opening from the casing 24 for the air bag. The flaps 36-42, in 
this embodiment, have a triangular shape and the apexes of each of the 
flaps have integral pointed cutting portions at 36a-42a to pierce a foam 
layer 38 located intermediate the retainer member 34 and the outer skin or 
cover 32 when the flaps 36-42 are pivoted outwardly as shown in FIG. 3. 
The bases of the triangular flaps 36-42 are connected at integrally 
weakened sections 36b-42b to the remainder of the retainer 34 to form 
hinges for upward and outward pivotal movement of each of the flaps as 
shown in FIG. 3. The cutting portions or members 36a-42a provide initial 
piercing of the foam layer 38 and outer skin 32. As shown in FIG. 4, 
openings 34a-34d have opposite upper edges 34e located in the plane of an 
outer surface 35 of the retainer. Surface 35 is parallel to outer skin 32. 
While triangular flaps are illustrated, other forms of flaps may be formed 
in the retainer at a point above the outlet of the casing so long as the 
flaps are integral to the retainer and have a cutting end and a hinged 
end. For example, the flaps may have a truncated cone shape as shown at 50 
in FIG. 6 with a weakened hinge segment 52. Flat end portions 54 have 
cutting edge 56 which severs a generally square segment from the foam and 
outer cover as the foam and outer skin are peeled apart to form an opening 
for deployment of the bag. FIG. 7 shows an H-pattern opening wherein the 
flaps 60 are rectangular with pointed integral cutting portions 62 with 
cutting edges 64. 
Openings 66a-66c form the H-pattern. Weakened integral hinges 68 join each 
flap to the retainer. FIG. 8 shows a scalloped pattern opening wherein the 
flaps 70 are curvilinear with pointed integral cutting portions 72 having 
cutting edges 74. Openings 76, 78 form the flaps 70. Integral weakened 
hinges 79 join the flaps 70 to the retainer. 
In all cases, deployment of an air bag causes it to impact the inside 
surface of the retainer 34 to force the flaps upwardly and outwardly so as 
to produce a peeling type opening until the overlying cover material is 
fully peeled back to define an opening more or less congruent with the 
outline of the weakened segments in the retainer. 
The door assembly of the subject invention thereby provides a soft skin 
door that is easily matched to adjacent interior trim products having 
foamed in place material and wherein the door assembly can be formed by 
standard foam molding apparatus without requiring special modifications to 
retainer components without modification of the lid for carrying such 
retainers and wherein the retainer has integral cutting flaps therein that 
are invisible from the exterior of an interior trim product so that a 
passenger is unaware of the underlying air bag restraint system. While the 
invention is shown in association with a dashboard or instrument panel, it 
is equally suitable for use with other interior trim products such as 
driver side steering wheel housings. The arrangement is manufactured not 
only with standard equipment practicing standard steps, it enables the 
door to be made by less steps and with less components and in a more cost 
effective manner than cutter assemblies of the prior art. 
The invention has been described in an illustrative manner, and it is to be 
understood that the terminology which has been used is intended to be in 
the nature of words of description rather than of limitation. 
Obviously, many modifications and variations of the present invention in 
light of the above teachings may be made. It is therefore, to be 
understood that within the scope of the appended claims, the invention may 
be practiced otherwise than as specifically described.