Land vehicles – Wheeled – Attachment
Reexamination Certificate
2000-12-06
2002-11-19
Dickson, Paul N. (Department: 3619)
Land vehicles
Wheeled
Attachment
C280S732000, C280S736000
Reexamination Certificate
active
06481742
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a structure for preventing gas leakage during inflator's operation in an air bag system in which an inflatable air bag for use in a car is inflated by gas generated from an inflator so as to protect a crew.
The present application is based on Japanese Patent Applications No. Hei. 11-346238 and 11-347769, which are incorporated herein by reference.
2. Description of the Related Art
Generally, an air bag system has such a configuration that an inflatable air bag and an inflator for generating gas for inflating the air bag are received in a casing, and an air bag side opening portion of the casing is closed by a cover portion which has a hinge portion and a rupture presumptive portion.
Sheet metal is used for casings in most air bag systems. In some air bag systems, however, in order to take measures for environmental problems such as regulations of exhaust gas of, for example, carbon dioxide or the like, and in order to reduce the weight of a car as a whole, casing material has been changed from sheet metal to resin material. Then, the aforementioned inflator is received in an inflator receiving casing. The inflator is fixedly fastened in a predetermined position inside the casing by a bolt projected from a forward end portion of the inflator, and a nut to be screwed down to the bolt. As a structure for attaching such an inflator, there has been a proposal as shown in FIG.
18
.
In this structure, fitting holes
16
d
and
16
e
in which an inflator
31
can be inserted from its front side or its rear side are provided in opposite, front and rear side walls of an inflator receiving casing
16
b.
Then, a lock flange portion
31
a
formed in the base end portion of the inflator
31
is locked at the outer circumferential edge of one fitting hole
16
d
while a bolt
33
formed in the forward end portion of the inflator
31
is attached to the other fitting hole
16
e
through a spacer
32
. That is, a fitting flange portion
32
a
of the spacer
32
is engaged with the fitting hole
16
e
, and the bolt
33
of the inflator
31
is made to project outside through a bolt insertion hole
32
b
of the spacer
32
. A nut
34
is screwed down to the bolt
33
so as to fixedly fasten the inflator
31
in a predetermined position.
In the aforementioned structure for attaching the inflator
31
, however, when there occurs a car collision such that the inflator
31
operates to inflate the air bag
21
with gas, the reaction of the gas causes high-pressure gas to pass into a bottom portion of the inflator receiving casing
16
b
. As a result, the inflator
31
receives force so as to be pushed up. That is, because the inflator receiving casing
16
b
is formed of synthetic resin material and the spacer
32
is made of metal material, the inflator receiving casing
16
b
is lower in rigidity than the spacer
32
. Accordingly, there occurs a phenomenon that the fitting flange portion
32
a
slides up while elastically deforming the circumferential edge of the fitting hole
16
e
. As a result, the fitting flange portion
32
a
of the spacer
32
is detached from the fitting hole
16
e
of the casing
16
as shown by the chain line in FIG.
9
. Thus, there is a fear that gas leaks from a gap-between the inflator receiving casing
16
b
and the spacer
32
so that the inflation of the air bag
21
becomes imperfect.
On the other hand, the casing
16
made of resin material has a weld portion which is peculiar to a resin molding. That is, the weld portion is formed by branches of a resin solution which pass in a plurality of directions in a cavity so as to be brought into contact with and bonded with each other when the casing
16
is molded. Therefore, also in an air bag system in which no spacer
32
is used in an inflator receiving casing
16
b
with fitting holes
16
d
and
16
e
having different diameters, there is a problem that the weld portion may be broken to cause gas leakage when the inflator
31
is operated.
Further, a case of another air bag system is shown in FIG.
19
.
That is, the air bag system case has a cover
101
formed integrally with an instrument panel body (hereinafter referred to as “instrument panel” simply)
100
, a housing
110
fitted to the cover
101
, and so on. A door portion.
101
c
is formed in the cover
101
. The door portion
101
c
is defined by a rupture presumptive portion
101
b
and a hinge portion
101
a
. An air bag
120
folded up and an inflator
121
for unfolding the air bag
120
are received in a space formed by the cover
101
and the housing
110
. The air bag
120
is unfolded by gas generated by the inflator
121
in response to a signal from a sensor attached to a vehicle body or the like. By the unfolding of the air bag
120
, the door portion
101
c
is opened and the unfolded air bag
120
is released to protect a crew.
In this configuration, a through hole
102
is provided in a side wall
101
d
of the cover
101
, while a lock portion
111
is provided like a bridge on a side wall
110
a
of the housing
110
so as to be located in a position corresponding to the through hole
102
. Then, the housing
110
is fitted to the cover
101
, and the lock portion
111
of the housing
110
is engaged with the through hole
102
of the cover
101
. Thus, the cover
101
and the housing
110
are locked with each other. Further, a plate
130
having an insertion portion
130
a
which can be partially inserted into the lock portion
111
of the housing
110
is used to hold the side wall
101
d
of the cover
101
between the plate
130
and the side wall
110
a
of the housing
110
. Then, the plate
130
is fixed on the housing
110
by studs
131
and nuts
132
.
When the air bag system is configured thus the movement of the cover
101
to leave the housing
110
is restricted because the insertion portion
130
a
of the plate
130
is inserted into the air bag system. Thus, there is no fear that the cover
101
is unexpectedly released from the locking between the through hole
102
of the cover
101
and the lock portion
111
of the housing
110
.
However, there is a problem that the lock portion
111
of the housing
110
is disengaged from the through hole
102
of the cover
101
when the air bag
120
is unfolded.
That is, when the air bag
120
is unfolded suddenly, force in the direction shown by the arrows A
1
in
FIG. 19
acts on the side wall
101
d
of the cover
101
. Thus, the side wall
101
d
of the cover
101
bulges apart from the side wall
110
a
of the housing
110
, so that there arises a fear that the plate
130
is deformed as shown by the dotted lines in FIG.
19
. When the plate
130
is deformed conspicuously like this, the restriction of the insertion portion
130
a
of the plate
130
on the movement of the side wall
101
d
of the cover
101
becomes so insufficient that there is a fear that the through hole
102
of the cover
101
is apart from the lock portion
111
of the housing
110
. As a result, there is a fear that the gas generated by the inflator
121
leaks to the outside of the air bag system. In addition, there is a fear that such gas leakage results in an unfolded state of the air bag
120
different from an aimed state.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a structure for preventing gas leakage during inflator's operation in an air bag system that can solve a new problem of gas leakage during inflator's operation which is common to the aforementioned background art.
In order to achieve the above object, according to the present invention, there is provided a structure for preventing gas leakage during inflator's operation in an air bag system comprising: an inflatable air bag for use in a car; an inflator for generating gas for inflating the airbag, the inflator having a flange portion and a bolt provided at a base end portion thereof and at a forward end portion thereof, respectively; a casing for receiving the air bag and the inflator; and a cover
Ichimaru Kazumi
Ichino Rie
Usami Hironori
Dickson Paul N.
Ilan Ruth
Pillsbury & Winthrop LLP
Toyoda Gosei Co,., Ltd.
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