Note: Descriptions are shown in the official language in which they were submitted.
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SPECIFICATION
TITLE OF THE INVENTION
sase cloth for air bag
sAcKGRouND OF THE INVENTION
The present invention relates to an air bag for
protecting the occupantin an vehicle as it is inflated
by reaction gas from an inflator when the vehicle is
collided, and in particular to a base cloth to con-
stitute such air bag.
The air bag unit as provided on a fix`ed portion
of car body in front of a seat in a vehicle plays an
important role to protect the person in the vehicle
from injury when the vehicle is collided as the air
bag is inflated instantaneously by the pressure of
reaction gas released from an inflator fixed on
steering or on dashboard.
For example, as shown in Fig. 4, such air bag
unit 1 comprises an inflator 2, which induces chemical
reaction of gas generating agent by collision signal
from collision detecting sensor when deceleration
of vehicle becomes higher than a certain level and
ejects the reaction gas, and an air bag 3, the base
of which is fixed on the inflator 2 and which is
inflated by the gas ejected from the inflator 2.
This air bag unit 1 is mounted, for example, on
a fixed portion of car body such as the center of
steering wheel 5 with the air bag 3 folded up and
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placed in a pad 4.
As shown in Fig. 5, the gas generating agent in
the inflator 2 reacts when the vehicle is collided,
and the air bag 3 is instantaneously inflated by
the reaction gas thus generated. In so doing, the
air bag 3 receives the occupant M, who is thrown
forward by inertia, and protects the person M from
the collision against car body.
In an air bag 3 of conventional type, the air
bag 3 for air bag unit 1 to be installed on the
driver's seat is formed by sewing a base cloth 3a
facing to the driver M and a base cloth 3b to be
fixed on a fixed portion of car body. The air bag
3 for the air bag unit 1 to be installed on the
other position other than the driver's seat
is formed by sewing the base cloth formed in
various shapes. These base cloths 3a and 3b are
made of woven cloths in most cases.
The air bag 3 must fulfill the function to
inflate instantaneously by high pressure reaction
gas and to receive theoccupant perfectly, and the
following conditions are required for the base
clothes 3a and 3b:
(1) Warp and weft must be set in the same density.
(2) They must be set at far higher density than
normal woven cloth.
~3) The strength must be equal in longitudinal
direction and lateral direction.
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However, when a cloth is woven, crimping gen-
erally occurs, in which the woven cloth is shrinked
in lateral direction. In general, the base cloth
for air bag is woven in high density using thread
of about 400 deniers. In weaving the cloth in such
high density, stress often unavoidably occurs on the
selvege. Accordingly, it has been customary to
weave the cloth by holding the selvege of base cloth
and pulling warp, using a temple. However, when
cloth is woven by holding only the selvege of base
cloth, warp is more extensively pulled as it
approaches toward the center of weaving width.
Thus, warp 103 is unavoidably stretched on the selvege
102 of base cloth 101. As the result, weft 104
is curved in the pulling direction of the warp
103, and the base cloth thus woven has partially
different density, and the elongation also dif
fers partially. When elongation and density
differ partially, the strength of base cloth also
partially differs between the selvege and the center.
Therefore, the strength of air bag differs
between the case where base cloth 101 is cut at
the portion A for air bag and the case where it
is cut ai the portion B.
As described above, in the conventional type
for air bag, the density of warp and weft differs
partially and the strength is not uniform. Thus,
the conditions required for base cloth of air bag
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as described above cannot be satisfied, and the
function of air bag cannot be fulfilled to full
extent.
SUMMARY OF THE INVENTION
The object of the present invention is to offer
a base cloth for air bag, which can fulfill the
functions of air bag satisfactorily and reliably.
To attain such object, the base cloth according
to the present invention is made of woven cloth and
constitutes an air bag, which is inflated by reaction
gas from an inflator, operated in an emergency, and
receives the occupantin vehicle, characterized in
that warp and weft are set in the same high density,
and that the strength in lateral direction is uni-
formly set.
The base cloth for air bag according to this
invention with such arrangement can fulfill the
functions of air bag perfectly when it receives
the occupant when it is inflated instantaneously
by high pressure reaction gas because warp and
weft are set in the same high density and because
the strength in lateral direction is uniformly
set. Above all, the air bag forOccllpant on the
seat other than the driver's seat effectively
functions because even the selvege of base cloth
is used.
Still other ob]ects and advantages of the
invention will in part be obvious and will in
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part be apparent from the specification.
The invention accordingly comprises the
features of construction, combinations of ele-
ments, and arrangement of parts which will be
exemplified in the construction hereinafter
set forth, and the scope of the invention will
be indicated in the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 shows an example of an air bag of an
embodiment of the base cloth for air bag according
to the present invention, (A) being a plan view,
and (B) a cross-sectional view along the line
IB-IB in (A);
Fig. 2 is a drawing showing a part of woven
cloth to be used as base cloth of this embodiment;
Fig. 3 represents an example of a weaving
machine to weave the above woven cloth;
Fig. 4 is a schematical cross-sectional view
of typical case where the air bag unit is installed
on steering wheel;
Fig. 5 shows the conditlon when the air bag is
inflated; and
Fig. 6 shows the base cloth of conventional
type for air bag when it is woven up.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
As shown in Figs. 1 (A) and (B), the air bag
comprises a base cloth 3a installed face-to-face to
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the occupantM in the vehicle and a base cloth 3b to
be fixed on a fixed portion of car body, and it is
formed by sewing up the marginal portions of the
base cloths 3a and 3b. In the example shown in the
figure, the base cloths 3a and 3b are sewn up in
such manner that the thread directions intersect
each other by an angle of about 45 degrees between
these cloths. of course, the direction of these
threads may be in the same direction or the intersect-
ing angle may be an angle other than 45 degrees.
As shown in Fig. 2, these base cloths 3a and
3b are woven with the same density for both warp
6 and weft 7 and in the higher density than the
density of normal woven cloth. Also, the base
cloths are made of woven cloth, in which the strength
in lateral direction is uniformly set.
Such woven cloth is woven, for example, by a
weaving machine 8 using bar temple as shown in Fig.
3. Specifically, a cover 11 is mounted on a guide
bar 10 of main body 9 of the weaving machine 3,
and bar temple 13 is disposed in a space 12 formed
between them. The woven cloth 14 is inserted into
this space 12. After it is wound on the bar temple
13, it is sent toward the breast beam 15 and is
finally wound up on a winder (not shown).
When the woven cloth 14 is woven, weft 7 is
passed through between the warps 6, which are
positioned up and down and on which a certain
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tension is applied. Then, the weft 7 is hit by the
guide bar 10 toward the weaving end of the woven
cloth 4 to increase the density of the weft 7. In
this case, when the guide bar 10 moves back from
the weaving end, the bar temple 13 ls pulled up
by the tension of the woven cloth 14, and the woven
cloth 14 is held between main body 9 and bar temple
13 as well as between bar temple 13 and cover 11.
As the result, total width of the woven cloth 14
is tightened, and the weaving end does not move.
When guide bar 10 hits the weaving end, the woven
cloth 14 is loosened. Because bar temple 13 is
separated from main body 9 and cover 11, the woven
cloth 14 is wound up on the winder.
The woven cloth 14 thus woven up has the warp
and the weft in the same density, and the density
is higher than that of normal woven cloth. More-
over, no sag occurs on the selvege of the woven cloth
14, and the woven cloth 14 has uniform tensile
strength over the entire width.
Therefore, by cutting such woven cloth 14 to
the base cloth in a proper shape for air bag 3
according to the place to be installed and by
sewing these base cloths, the air bag 3 can re-
liably receive the occupant in the vehicle when
it is inflated instantaneously by high pressure
reaction gas.
As it is evident from the above description,
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warp and weft have the same high density in the
base cloths for air bag according to this invention,
and the strength in lateral direction is uni~ormly
set. Accordingly, the air bag can be inflated
instantaneously by high pressure reaction gas and
receive the occupant in reliable manner. Above all,
in the air bag for the occupant on the seats other
than the driver's seat, the base cloth according
to this invention can effectively fulfill its
function because even the selvege of the base cloth
is used in many cases.
