Land vehicles – Wheeled – Attachment
Reexamination Certificate
2003-05-30
2004-06-01
Dickson, Paul N. (Department: 3616)
Land vehicles
Wheeled
Attachment
C280S732000
Reexamination Certificate
active
06742804
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a tear structure of an air bag door and more particularly to a tear structure comprising two sheets of door panels which are formed integrally with the base of the upholstery member of a vehicle and open to both sides when an air bag system is actuated and two sheets of movable reinforcing panels which are fitted to a bracket disposed on the back side of the base in such a manner as being openable to both sides and fixed correspondingly to the door panels, wherein when an air bag starting to expand simultaneously with the operation of the air bag system presses the movable reinforcing panels from the inside, there occurs the rupture of tear seams formed along the center line where the two sheets of adjoining door panels meet and along the outer edge lines thereof to timely open the door panels toward a passenger's chamber.
2. Description of the Related Art
In recent years, almost all passenger cars are normally equipped with air bag systems for car drivers' and front passengers' seats in order to protect on-board persons from impacts due to collisions and the like. The air bag system for the car driver's seat is usually installed in a horn pad portion in the center of a steering wheel. However, as shown in FIGS.
10
and
11
, for example, the airbag system for the front passenger's seat is installed in such a way that it is housed inside an instrument panel
10
as a vehicle upholstery member that is located in front of the passenger's seat and incorporated in the forepart of a passenger's chamber
45
. Therefore, an air bag door
12
to be opened and displaced toward the passenger's chamber
45
is separately mounted or integrally formed in a region corresponding to the air bag system
20
for the passenger's seat in the panel base
11
of the instrument panel
10
. When the door
12
is released from the panel base
11
, an open partition toward the passenger's chamber
45
is formed. More specifically, when the air bag system
20
operates on sensing an impact due to a collision, an inflated air bag
21
forces the air bag door
12
to open from the inside and develops into the passenger's chamber
45
via the open partition.
Heretofore, it has been a common practice that the air bag door
12
is separately formed from the panel base
11
of the instrument panel
10
and mounted therein. In recent years, however, the number of airbag doors
12
integrally formed with the respective panel bases
11
is on the increase. In other words, the air bag door
12
usually forms a design surface as part of the panel base
11
as shown in
FIGS. 10 and 11
and when the air bag door
12
receives the pressing force from the inflating air bag
21
after the air bag system
20
operates, rupture occurs along tear seams
15
and
16
that are provided in the panel base
11
beforehand, so that the tear seams
15
and
16
are separated from the panel base
11
and allowed to open. With respect to the form of the air bag door
12
, there are, for example, a one-side opening type having one door panel portion, a both-side opening type (as shown in the drawings) having two sheets of door panels and so forth. In any one of the types, however, an important matter is not to hinder the smooth development of the air bag
21
expected to take approximately {fraction (1/100)} second from beginning to completion of its inflation.
As the panel base
11
integrally forming the air bag door
12
is generally a synthetic resin molded material of polypropylene or the like, the panel base
11
itself including the air bag door
12
may be damaged by an impact resulting from receiving strong pressing force from the air bag
21
particularly at low temperatures (below zero) and there is immanent possibility of developing problems in view of its strength and safety. Consequently, measures to increase the strength by fitting a metal reinforcing member
25
, for example, by caulking to the periphery of the air bag door
12
on the back side of the panel base
11
in order to prevent the air bag door
12
from being damaged and scattered off.
On condition that the both-side opening type air bag door
12
having the two sheets of door panels
13
and
14
is employed, the metal reinforcing member
25
includes, as shown in
FIGS. 11
,
12
and
13
A, a rectangular frame-like fixing bracket
26
fixed in such a manner as to surround the edged tear seam
16
formed along the outer edge lines of the door panels
13
and
14
formed on the panel base
11
, and movable brackets
27
and
27
mounted face-to-face on the inner side of the opening of the fixing bracket
26
. The fixing bracket
26
includes a tubular portion
28
for retaining and holding the air bag system
20
, and a retaining plate portion
29
that is integrally molded to the tubular portion
28
and fitted by caulking to the back side of panel base
11
. Further, the movable brackets
27
and
27
correspond to the respective door panels
13
and
14
of the air bag door
12
, each of the movable brackets
27
and
27
including fixing support panels
30
fitted by welding or machine screws to the tubular portion
28
of the fixing bracket
26
, and movable reinforcing panels
31
that are pivotally joined to the respective fixing support panels
30
and also joined by caulking to the undersides of the corresponding door panels
13
and
14
. With the panel base
11
for mounting the metal reinforcing member
25
, the door panels
13
and
14
and the outer peripheral portions of the air bag door
12
are reinforced thereby so that the panel base
11
may become strong enough to sufficiently resist the strong pressing force generated by the inflation of the air bag
21
.
Incidentally, the conventional idea about the air bag door
12
was to attempt to increase the strength of the air bag door
12
itself by means of the metal reinforcing member
25
, and the chief aim of this was to avoid the damage caused by the strong pressing force of the air bag
21
. Therefore, the movable reinforcing panel
31
of the movable bracket
27
fixed to the underside of each of the door panels
13
and
14
has I-, L- or T-shaped reinforcing recessed portions
33
in proper places as shown in
FIG. 12
whereby to prevent the deformation of each of the door panels
13
and
14
of the air bag door
12
by increasing the strength of the movable reinforcing panel
31
itself against bending, deflection and twisting as shown in FIG.
12
. In this case, as the air bag
21
to be inflated through the operation of the air bag system
20
inflates in a spherical shape with the center of its upper face being inflated as shown in
FIG. 10
, the strongest pressing force is applied to the vicinity of the center (substantially central region of the central tear seam
15
) between the opposed edge portions of the movable reinforcing panels
31
and
31
fixed to the underside of the air bag door
12
. However, because the movable reinforcing panels
31
and
31
are almost free from deformation against the pressing force of the air bag
21
, substantially equal push-up force is applied to the whole surface of the corresponding door panels
13
and
14
.
When the air bag
21
starts inflating at the initial pressing stage, both the door panels
13
and
14
of the air bag door
12
are pushed up substantially without being bent-deformed, and the central tear seam
15
formed along the center line between the adjoining door panels
13
and
14
and the edged tear seam
16
formed along the outer edge lines are totally and simultaneously ruptured (sheared), so that partial rupture hardly occurs. As is well known, however, the force needed to rupture the tear seams
15
and
16
totally and simultaneously is far greater than what is needed to partially rupture part of the tear seams
15
and
16
first and then to make the rupture extend to the whole. Therefore, because no rupture of the tear seams
15
and
16
occurs unless the internal pr
Funato Toshiyasu
Hisadome Tomokazu
Murakami Akihiko
Suzuki Hiroaki
Dickson Paul N.
Inoac Corporation
To Toan C
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