Land vehicles – Wheeled – Attachment
Reexamination Certificate
2000-09-20
2002-10-08
Culbreth, Eric (Department: 3616)
Land vehicles
Wheeled
Attachment
C280S732000
Reexamination Certificate
active
06460875
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to air bags and, more particularly, to an instrument panel to operatively overlie an air bag and through which the air bag can be extended as the air bag is changed by inflation thereof from an undeployed state into a deployed state.
2. Background Art
In
FIG. 6
, an instrument panel is shown at
10
to be operatively placed over an air bag
12
. The instrument panel
10
is constructed so that the air bag
12
, upon being deployed by inflation, can extend through the instrument panel
10
in a direction indicated by the arrow
14
.
The instrument panel
10
consists of a skin layer
16
having an exposed front surface
18
and an oppositely facing rear surface
20
. A foamed resin layer
22
is laminated to the rear surface
20
of the skin layer
16
. A core layer
24
is adhered to the rear surface
26
of the foamed resin layer
22
and has an opening
28
formed therethrough. A door
30
is adhered to the rear surface
26
of the foamed resin layer
22
and has a joint portion
32
which abuts to a joint portion
34
on the core layer
24
.
The skin layer
16
has a weakening break portion
36
. The break portion
36
consists of a region
38
in the skin layer
16
having at thickness T that is less than the thickness T
1
of the remainder of the skin layer
16
. The skin layer
16
may be, for example, an olefinic thermoplastic elastomer (TPO). Deployment of the air bag
12
, by inflation thereof, causes the door
30
to advance in the direction of the arrow
14
and to thereby rupture the foamed resin layer
22
and the skin layer
16
in the vicinity of the break portion
36
.
With this construction, it is difficult to select the adhesive force between the skin layer
16
and the foamed resin layer
22
and the desired load on the skin layer
16
that produce elongation and breakage of the skin layer
16
to provide the desired operating characteristics for the instrument panel
10
. Trial and error may thus be required to arrive at the desired operating characteristics.
Another form of conventional instrument panel is shown at
40
in
FIGS. 7-9
. In the instrument panel
40
, a foamed resin layer
42
is laminated to the rear surface
44
of a skin layer
46
. A core layer
48
is laminated to the rear surface
50
of the foamed resin layer
42
. The core layer
48
has an opening
52
therethrough to allow an air bag
54
to extend therethrough as the air bag
54
is changed from an undeployed state, as shown in
FIG. 7
, by deflation, to a deployed state. A door
56
laminated to the rear surface
50
of the foamed resin layer
42
covers the opening
52
. The door
56
has a joint portion
58
which abuts a joint portion
60
on the core layer
48
.
The instrument panel
40
has a break portion
62
. The break portion
62
consists of a groove
64
. The groove
64
has a U shape defined by spaced sides
66
,
68
between which a base
70
is defined. The skin layer
46
may be made, for example, from an olefinic thermoplastic elastomer (TPO).
Upon deployment of the air bag
54
, the pressure applied to the door
56
causes the foamed resin layer
42
and skin layer
46
to rupture adjacent to the break portion
62
. In this construction, the door
56
spans the opening
52
slightly behind the base
70
and extends outwardly past the groove
64
so that a peripheral edge
72
resides slightly beyond the groove side
68
. As a result, as shown in
FIG. 9
, fracture may occur not precisely at the break portion
62
, but rather spaced to the side thereof at the location of the edge
72
. As this occurs, the edge
72
of the door
56
raises the foamed resin layer
42
and skin layer
46
to cause delamination both in the region at
74
between the skin layer
46
and foamed resin layer
42
and in the region at
76
between the foamed resin layer
42
and the core layer
48
.
Another problem with the instrument panel
40
in
FIG. 7
is that passage of the resin layer, in its liquid state, between the joint portions
58
,
60
is prevented only by facing and abutting surfaces
78
,
80
thereon. As a result, leakage of the foamed resin liquid may occur as the foamed resin liquid is cast during formation of the instrument panel
40
.
To address this resin leakage problem, various solutions have been proposed, for example, in Japanese Patent Laid-Open No. 52826/1998, Japanese Patent Laid-Open No. 211625/1998, Japanese Patent Laid-Open No. 235661/1998, and Japanese Patent Laid-Open No. 188747/1999. In each of these disclosures, the problem of resin leakage between the core material and the skin is addressed. None of the above disclosures discloses a solution for preventing leakage of resin between abutting materials which are relatively hard.
One proposed solution to the leakage problem is shown in
FIG. 10
on an instrument panel
82
, which has the same construction as the instrument panel
40
with the exception of one addition. In the instrument panel
82
, a sealing tape
84
is interposed between the surfaces
78
,
80
on the joint portions
58
,
60
. The sealing tape
84
may not effectively solve the leakage problem in the event that there is poor dimensional accuracy of the surfaces
78
,
80
on the joint portions
58
,
60
. Further, if the sealing tape
84
does not effectively bond, leakage may occur whereupon burrs of solidified foamed resin may be formed. These burrs may be undesirable for cosmetic reasons, which may necessitate removal thereof.
Another problem with the instrument panel
40
in
FIG. 7
is that by reason of the over/underlying relationship of the core layer
48
and door
56
, the foamed resin layer
42
has a thickness T
3
between the skin layer
46
and the door
56
that is less than the thickness T
4
between the skin layer
46
and the core layer
48
. As a result, there may be residual strain in the foamed resin layer
42
, resulting in the appearance of a step in the vicinity of the edge
72
which is visible to the naked eye at the front of the instrument panel
40
.
SUMMARY OF THE INVENTION
In one form, the invention is directed to the combination of an air bag having an undeployed state and a deployed state, and an instrument panel. The instrument panel overlies the air bag with the air bag in the undeployed state. The instrument panel has a skin layer with oppositely facing front and rear surfaces, a foamed resin layer on the rear surface of the skin layer and having a thickness, a core layer having an opening bounded by an edge through which the air bag extends with the air bag in the deployed state, and a door at the opening. The door has a peripheral edge and is repositionable from a closed position into an open position as an incident of the air bag changing from the undeployed state into the deployed state. The skin layer has a break portion defined by a groove at which the skin layer ruptures as the air bag changes from the undeployed state into the deployed state. The groove has first and second spaced sides and a base between the first and second sides. The groove produces a localized reduction in the thickness of the foamed resin layer and has at least a portion that is spaced outwardly from the edge bounding the opening in the core layer. At least a portion of the peripheral edge of the door extends outwardly from the edge bounding the core layer opening toward the groove but not past the groove.
In one form, the door has a generally flat first surface and an offset surface portion adjacent to the peripheral edge of the door that makes an angle with the first flat surface.
In one form, the door has a generally flat front surface and a corner at the juncture of the front of the door and the peripheral edge. An angle defined between a line extending from the corner to the groove base and the flat front surface of the door is in the range of 30° to 90°.
In one form, an extension of the offset surface portion intersects the groove.
In one form, the core layer has a joint portion and the door has a joint portion and the joint portions are in
Kurimoto Takuya
Teranishi Sadao
Culbreth Eric
Mitsuboshi Belting Ltd.
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