CA1337207C - Impact absorbing bag and manufacturing method thereof - Google Patents
Impact absorbing bag and manufacturing method thereofInfo
- Publication number
- CA1337207C CA1337207C CA000585682A CA585682A CA1337207C CA 1337207 C CA1337207 C CA 1337207C CA 000585682 A CA000585682 A CA 000585682A CA 585682 A CA585682 A CA 585682A CA 1337207 C CA1337207 C CA 1337207C
- Authority
- CA
- Canada
- Prior art keywords
- tubular
- connecting portion
- weave structure
- woven fabric
- bag
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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- Air Bags (AREA)
Abstract
An impact absorbing bag consisting of a seamless tubular woven fabric constituted with a central zone, having substantially a circular shape and formed by a non-connecting portion B2 of a tubular weave structure B, and a circumferential zone, having a ring-like shape and formed by a connecting portion B1 of the tubular weave structure B or by the connecting portion B1 and a non-tubular weave structure A, wherein the transition between the non-tubular weave A structure and the tubular weave structure B is continuous; at least on portion of a surface of the seamless tubular woven fabric being provided with a polymer covering layer; a gas introducing hole being provided in the non-connecting portion B2 of the tubular weave structure B at one side of the seamless tubular woven fabric. Also, a method for manufacturing an impact absorbing bag, consisting of a step of obtaining a continuous body of a seamless tubular woven fabric by repeating a tubular weave structure B in which a plurality of warp threads are woven with a plurality of weft threads in a manner that the more the weft picking operation is repeated, first, the shorter the length in the widthwise direction of a connecting portion B1 and, then, the longer the length in the widthwise direction of the connecting portion B1, so that a non-connecting portion B2 having a substantially circular shape is formed, or by alternately repeating the tubular weave structure B and a non-tubular weave structure A, a step of forming a polymer layer on at least a portion of a surface of the obtained continuous body or a segment cut from the continuous body in a circular shape to give the above seamless tubular woven fabric, and a step of providing the gas introducing hole, the order of the above steps being arbitrarily selectable.
Description
- l- 1337207 IMPACT ABSORBING BAG AND MANUFACTURING METHOD
THEREOF
BACKGROUND OF THE INVENTION
1. Field of the Invention The present invention relates to an air bag and a method of manufacturing the same. More particularly, the present invention relates to an impact absorbing bag housed in a center portion of a steering wheel which is capable of sensing impact caused when a car collides with some object and instantaneously inflating to ensure the safety of a driver or the like and to a method for manufact-lring the impact absorbing bag.
THEREOF
BACKGROUND OF THE INVENTION
1. Field of the Invention The present invention relates to an air bag and a method of manufacturing the same. More particularly, the present invention relates to an impact absorbing bag housed in a center portion of a steering wheel which is capable of sensing impact caused when a car collides with some object and instantaneously inflating to ensure the safety of a driver or the like and to a method for manufact-lring the impact absorbing bag.
2. Description of the Related Art When a car collides with an oncoming car or another object, the driver may smash his face strongly onto the steering wheel or the front glass. If the impact generated at that time can be reduced, it is possible to prevent death or serious injury to the driver.
In many countries, drivers are obligated by law to use seat belts as one means of safety upon collisions, but the ef~ective reduction of the impact by seat belts is not sufficient when a car collides with an object at a high speed.
Therefore, use of an air bag system, i.e., a system capable of sensing an impact caused when a car collides with an object and instantaneously inflating a bag housed in a center portion of a steering wheel or the like to ensure the safety of the driver or the like is now being considered in many countries as a more reliable safety measure .
One conventional air bag has been manufact~lred by forming a polymer layer on a plain woven fabric, providing a gas introducing hole in one of the woven fabrics, superimposing two woven fabrics with polymer layers in a state with the polymer layer sides facing each other, and sewing together circumferential edges of the two woven fabrics. For example, Japanese Unexamined Patent Publication (Kokai) No. 51-4742, in the portion explaining the conventional air bags, describes that conventional air bags are obtained by cutting two circular pieces of woven fabrics from two regular square pieces of woven fabrics and sewing together the circumferential edges of the two circular pieces.
In air bags, a gas is instantaneously fed into the bag by explosion of a pyrotechnic, so the air bag m~lst have a strength sufficient to endure the impact force caused by the explosion. The above-mentioned method of manufacturing air bags using a sewing process has several problems in this regard. There are many manual working processes involved, so there is a chance of decreased strength of the sewn portions and inspections of the strength of the sewn portions and the air permeability of the woven fabric take much time. The overall reliability of air bags manufactllred by this method is low.
A method of manufacturing air bags using a tubular weaving method has been proposed. Japanese Examined Patent Publication (Kokoku), corresponding to Japanese Unexamined Patent Publication (Kokai) No. 57-58228, discloses an impact absorbing tubular woven fabric having bag portions formed by alternately folding two woven fabrics up and down at a middle portion. In this tubular weave, a bag portion A and a bag portion B having a connecting portion C, which consists of the upper woven fabric and lower woven fabric woven together in a jointed weave, are alternately provided. The bag portion B is smaller than the bag portion A. The fact that this tublllar woven fabric ~ould be coated was mentioned in this patent publication, but a detailed explanation was only given of a continuous body of an air bag.
F~rther, Japanese Examined Patent Publication (Kokoku) No. 54-576, corresponding to Japanese Unexamined Patent Publication (Kokai) No. 50-7232, di~scloses an impact absorbing bag having an upper connecting portion and a lower connecting portion having weft threads with larger shrinkage ratios than their warp threads. In the description of the invention and the drawings of this publication, there was shown an air bag having a square shape in plan view, provided at the outer layer thereof with a covering layer.
However, when making separate bags from the impact absorbing tubular woven fabric disclosed in Japanese Examined Patent Publication (Kokoku) No. 57-58228, the above tubular woven fabric should be cut along the widthwise direction in a portion indi~ated as C in Fig. 9 in the publication, so the shape of the cut fabric necessarily be~omes square. An air bag having a square shape has problems such that the air pressure is not applied uniformly over the air bag, the appearance of the air bag is inferior, and it is difficult to neatly house the air bag in the steering wheel. The impact absorbing bag disclosed in Japanese Examined Patent Publication (Kokoku) No. 54-576 also has a square shape, so it has the same problems.
It is possible to make the chamber into whicn air is blown an o~tagon by sewing the four corners of an air bag of a square shape (in this case, the appearance of the air bag is still square), but this sewn air bag has disadvantages of the large cost of the labor to sew the corners, the weaker strength of the sewn portions compared to the other portions, and the la~k of uniformity. Even if this air bag is turned inside out by pulling the inside of "~
..~. .
_ 4 _ 1337207 the air bag through the opening at the center portion of the air bag for the air insertion, only the appearance of the air bag is improved. The other disadvantages, such as the inferior uniformity, are not eliminated.
SUMMARY OF THE INVENTION
A first object of the present invention is to provide an impact absorbing bag having superior uniformity~
appearance, and reliability and having the ability to be easily manufactured.
A second obje~t of the present invention is to provide a preferable method of manufacturing the impact absorbing bag having the above-mentioned characteristics.
An impa~t absorbing air bag in accordance with the present invention consists of a seamless tubular woven fabric constituted with a central zone, having substantially a circular shape and formed by a non-connecting portion B2 of a tubular weave struct~re B, and a ~ircumferential zone, having a ring-like shape and formed by a connecting portion Bl of the tubular weave structure B or by the connecting portion Bl and a non-tubular weave structure A, wherein the transition between the non-tubular weave structure A and the tubular weave structllre B is continuous. Further, at least one portion of the sllrface of the seamless tubular woven fabric is provided with a polymer ~overing layer 2. A gas introducing hole 3 is provided in the non-connecting portion B2 of the tub-llar weave structllre B at one side of the seamless tubular woven fabric 1.
Another type of impat absorbing bag in accordance with the presen~ invention is a bag having an inside-out structure formed by pulling o~t the inside of the above-mentioned impact absorbing bag through the gas introducing hole.
The manufacturing method of the impact absorbing bag in ~ ,, ~,......
_ 5 13~7207 accordance with the present invention consists of the following steps, the order of which can be arbitrarily set:
a step of obtaining a continuo-ls body of a seamless tubular woven fabric by repeating a tubular weave strilcture B in which a plurality of warp threads are woven with a plurality of weft threads in a manner that the more the weft picking operation is repeated, first, the shorter the length in the widthwise direction of the connecting portion Bl and, then, the longer the length in the widthwise direction of the connecting portion Bl, so that a non-connecting portion B2 having a substantially circular shape is formed, or by alternately repeating the above-described tubular weave structure B and a non-tubular weave structure A;
a step of forming a polymer layer on at least a portion of a surface of the obtained continuous body or a segment cut from the said continuous body;
a step of c~ltting the continllous body of the seamless tublllar woven fabric, or a segment cut from the continllolls body, in a circular shape to give a seamless tubular woven fabric constituted with a central zone, having substantially a circular shape and formed by a non-connecting portion B2 of a tubular weave structure B, and a cir~umferential zone, having a ring-like shape and formed by a connecting portion Bl of the tubular weave structure B or by the connecting portion Bl and a non-tublllar weave structure A, the transition between the non-tubular weave structure A and the tubular weave structure B being continuous, and a step of providing a gas introducing hole in the non-connecting portion B2 of the tubular weave structure B at one side of the seamless tubular woven fabric.
Another manufacturing method of the impact absorbing bag in accordance with the present invention further includes a step of turning the impact absorbing bag inside ~,,;~, .. . .
Oilt by pulling out an inner side of the impact absorbing bag throl(3h the gas introducing hole.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a plan view illustrating an example of a continuous body of a seamless tubular woven fabric in accordance with the present invention;
Fig. 2 is a front view illustrating the continuous body illustrated in Fig. 1 and provided with a polymer layer;
Fig. 3 is a plan view illustrating an example of one individual unit of the seamless tublllar woven fabric provided with a gas introducing hole;
Fig. 4 is a cross-sectional view of an example of the impact absorbing bag in accordance with the present invention obtained by turning inside-out an individual unit of the impact absorbing bag illustrated in Fig. 3 through the gas introducing hole;
Fig. 5 is a cross-sectional view of another example of the impact absorbing bag obtained by turning inside-out an individual unit illustrated in Fig. 3 through the gas introducing hole; and Figs. 6 to 8 are plan views illustrating other examples of the continuous bodies of the impact absorbing bag in accordance with the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will now be described in detail with reference to the accompanying drawings illustrating embodiments.
As can be seen from Figs. 1 to 3, an impact absorbing bag in accordance with the present invention uses as a base woven fabric structllre a seamless tubular woven fabric 1 constituted with a central zone, having a substantially circular shape and formed by a non-connecting portion B2 of a tubular weave portion B, and a circumferential zone, A ~
,,,, . ., ~
l~372n7 having a ring-like shape and formed by a connecting portion Bl of the tubular weave structure B or by the connecting portion Bl and a non-tubular weave structllre, in which the transition between the non-tubular weave structure A and the tubular weave structure B is continuous.
The seamless tubular woven fabric as described herebefore can be obtained by preparing a contin-lo-ls body of the seamless tubular woven fabric manufactured by repeating at least one tubular weave structure B in which a plurality of warp threads~are woven with a plurality of weft threads in a manner that the more the weft picking operation is repeated, first, the shorter the length in the widthwise direction of the connecting portion B and then the longer the length in the widthwide direction of the connecting portion Bl, thus forming a non-connecting portion B2 having substantially a tubular shape, or by alternately repeating the above-described t~lbular weave structure and a non-tubular weave structure A, and then cutting the continuo-ls body of the seamless tubular woven fabric or a segment cut from the continuo~ls body in a substantially circ-llar shape.
For example, first, the non-tubular weave structure A
is formed by repeating a non-tubular weave until the predetermined length is obtained and then the tubular weave structure B having the connecting portion Bl and the non-connecting portion B2 of a substantially ring-like shape is manufactured by performing a tubular weave operation, i.e., a warp and weft double weaving weave in which a front layer and a back layer are connected to each other at both edge portions, in su~h a manner that the more the weft picking operation is repeated, first, the shorter the length in the widthwise direction of the conne~ting portion Bl and then the longer the length in the widthwise direction of the connecting portion Bl. After that, a continuous body in ,.
Af which a plurality of the seamless tub-llar woven fabrics are aligned in a row, as illustrated in Fig. 1, can be obtained by repeating th~non-tubular weaving operation and the tubular weaving operation gradually changing the length in the widthwise direction of the connecting portion Bl at both edge portions.
In this case, when a conne~ting portion Bl having some width is further arranged on a middle portion in the widthwise direction of the continuous body, a continuous body can be obtained in which a plurality of the seamless tubular woven fabrics are arranged in two rows as illustrated in Fig. 6. A continuous body in which a plurality of seamless tubular woven fabrics are arranged in rows of three or more can be easily obtained in the same manner as that of the previous case. Further, a continuolls body in which a plurality of sea~less tubular woven fabrics are arranged in a zigzag state as illustrated in Fig. 7 can be obtained by repeating a required number of times only the tublllar weaving operation in which the length in the widthwise direction of the connecting portion Bl at both edge portions is gradually changed and not applying the non-tubular weaving operation.
The weaving of the seamless tubular woven fabri~ can be performed by using a dobby loom, a jacquard loom, or the like.
The shape of the non-connecting portion B2 in the tubular weave stru~ture B is generally circular or nearly circular, but it is possible to make a deformed circle as illustrated in Fig. 8. The impact absorbing bag including the non-conne~ting portion B2 of the deformed circle can be usefully used as an air bag in the front passenger seat or the rear passenger seats.
A plain weave, twill weave, satin weave, or the like ~4 ~
~.,~
can be used as the weave in the non-~onnecting portion and the connecting portion.
As the weft thread and the warp thread used for manufacturing the seamless tubular woven fabric, a thread produced from a polyester fiber, polyamide fiber, including aramide fibers, acrylic fiber, polyvinyl alcohol fiber, polyvinylidene chloride fiber, polyolefin fiber, polyurethane fiber, fluoroplasti¢ fiber, semisynthetic fiber, regenerated fiber, natural fiber, ~arbon fiber, glass fiber, ceramic fiber, metal fiber, or the like can be used.
Further, a thread having a suitable elasticity can be llsed.
A polymer layer 2 is provided on at least one portion of a surface of the seamless tub~lar woven fabric 1 to prevent permeation of gases through the woven fabric 1.
Generally, the polymer layer 2 is provided on the entire surface of both sides of the seamless tubular woven fabric, but the polymer layer may also be provided on just the surface of the side facing the driver when the air bag is mounted in a steering wheel.
As examples of the polymer layer, mention may be made of film produced from a polyurethane resin, polyester resin, polyamide resin, polyvinylidene chloride resin, polyvinyl chloride resin, polyolefin resin, fluorine resin, sili~one resin, polystyrene resin, cellulose polymer, natural rubber, synthetic rubber, or the like. A polymer capable of forming an elastic film is useful. A poly~rethane elastomer, a polyester elastomer, a polyamide elastomer, a polyolefin elastomer, or the like can be used as typical elasti~
polymers. A polyurethane elastomer is particularly preferable. Here, "polyurethane elastomer" denotes a rubber-like elastic polymer having a urethane radical in its molecular structure and includes an adipate ester type, a polyether type, a caprola~tone type, and a polycarbonate ,~
type.
The polymer is generally applied in a film state, liquid state, solution state, dispersion state, or a molten state on the outer surface of both sides o~ the seamless tubular woven fabric and then is made into a laminate or covering by heating, drying, cooling, irradiation by activation energy, or the like.
Further, if necessary, it is possible to use a method in which the warp thread and/or weft thread is previously coated with the polymer, a fabric is made by the above warp threads and weft threads, and the woven fabric is heated to increase the flowability of the polymer on the surface of the thread so that gaps in the woven fabric structure are filled with the polymer.
The polymer layer 2 may be formed on the seamless tubular woven fabric 1 for individual units of the fabric 1.
However, it is more efficient to form the polymer layer on a continuous body of the seamless tubular woven fabrics. It is possible to apply the polymer layer to a segment cut from a continuous body, for example, a segment incl~ding two seamless tubular woven fabrics, a segment including three seamless tubular woven fabrics, or a segment having the shape of a square.
A gas introducing hole 3 is arranged on the tublllar weave structure B of the side of the seamless tubular woven fabric with the polymer layer. The gas introducing holes may be made in the continuolls body, the segments, or the individual units.
To obtain the individual units of the seamless tubular woven fabric from the contin-lous body, the connecting portion Bl of the tubular weave structllre B or the connecting portion Bl and the non-t~lbular weave structure A
may be cut in a circular shape along a position slightly ~ .~
. ~
ll- 1337207 apart from the circumferential edge of the non-connecting portion B2 having a substantially circular shape in the tubular weave structure B. It is advantageous to use melting rather than mechanical cutting as a cutting method. Thus, individual units including the non-connecting portion B2 having the circular shape of the tubular weave structure B
and a ring-like portion arranged circumferentially on the non-connecting portion B2 and cornprising the connecting portion Bl or the ~onnecting portion Bl and the non-tubular weave structure A is obtained.
The polymer layer 2 is generally formed on the seamless tubular woven fabric 1 from the outside of the fabric 1.
Therefore, the bag obtained ~y this method has a slightly inferior feeling. Further, since the connecting portion Bl of the tublllar weave structure B or the connecting portion Bl and the non-tubular weave structure A are present in a circumferential portion of the bag, the appearance of the bag is not always good. If the bag is turned inside-out by pulling out the inside of the air bag through the gas introducing hole 3, the feeling and the appearance of the obtained air bag are remarkably improved. Therefore, it is advantageous to use an inside-out air bag in terms of the merchandiseability.
It is possible to provide one orrnore strands or strips ~5 4 inside the impact absorbing bag in accordance with the present invention for limiting the inflation of the bag between the front of the bag, as seen from the driver's position, and the opposite side of the bag, as illustrated clearly in Figs. 4 and 5.
The impact absorbing bag in accordance with the present invention is housed in the central portion of the steering wheel with the gas introducing hole 3 connected to a gas generator. When an impact of a predetermined value or more, A ~
~ se ~
for example, an impact generated when a car having a speed of 16 km/hr or 25 km/hr collides head on with an object, is sensed by a mechanical sensor or an electrical sensor, gas generated by a pyrotechnic is suddenly fed into the bag, and the bag is simultaneously inflated. For example, the bag is inflated in 0.08 second after sensing of the impact. It is also possible to feed a gas having a high pressure from a gas cylinder. When the air bag is used for the front passenger seat or rear passenger seats, portions capable of housing the impact absorbing bags may be suitably arranged inside the car.
The impact absorbing bag according to the present invention uses as a base woven struct~re a seamless tubular woven fabric constituted with a central zone, having substantially a circular shape and formed by a non-connecting portion B2 of a tubular weave structure B, and a circumferential zone, having a ring-like ~hape and formed by a connectinq portion Bl of the tubular weave structilre B or by the conne~ting portion Bl and a non-tubular weave struct~lre A, wherein the transition between the non-tubular weave structure A and the t~lbular weave structure B is continuous. Due to this, it is superior in terms of uniformity, strength, and adjustment of the air-permeability compared with the conventional method of forming a bag by cutting out circular pieces of fabric from two square pieces of fabric and sewing together the circumferences of the same. Therefore, a high degree of reliability can be ensured as an impact absorbing bag. Further the manufactllring steps are streamlined and inspection time can be reduced, so it is advantageous in terms of productivity as well.
Even compared with a sq~are shaped air bag, seen in plan view, prepared from a tubular weave, the impact absorbing bag of the present invention is far superior in A
terms of the overall uniformity of application of the air pressure, the external appearane, and the capability of housing in a steering wheel.
The impact absorbing bag of the present invention, housed in the center portion of the steering wheel, is useful for the object of instantaneously inflation when sensing an impact of collision of the car and ensuring driver safety. It may be used not only for the object of ensuring driver safety, but also for the object of ensuring the safety of the passengers in the front passenger seat and rear passenger seats.
The present invention will now be explained in further detail by examples, which do not, however, limit the invention in any way.
Example 1 Figures 1 to 4 show an example of the steps for manufactilring an impact absorbing bag according to the present invention.
Use was made of polyester multifilament yarn as the warp and weft and weaving was performed using a jacquard loom. First, non-tubular weaving was performed until a predetermined width to form a non-tubular weave structure A, then tubular weaving wherein the upper and lower layers are joined only at the two edge portions was performed so that the more the weft picking operation was repeated, first, the shorter the length in the widthwise direction of a connecting portion Bl and, then, the longer the length in the widthwise direction of the connecting portion Bl, so that a tubular weave struct~re B was formed. This non-tubular weaving step to the tubular weaving step wherein thelength of the connecting portion Bl at the two edges was changed was repeated.
By this, a continuous body of a single row of a ,eamless tubular woven fabric 1 having a non-connecting portion B2 of a tubular weave structllre B which is substantially circular in shape is obtained. (See Fig. 1.) From the two sides of the continllolls body of the seamless tubular woven fabric 1 was coated a polyether type polyurethane elastomer. This was heated to dry and further cured to form a polymer covering layer 2. (See Fig. 2.) Next, separate circular pieces were cut by melting at the connecting portion Bl of the tubular weave structure B
and the non-tubular weave stru~ture A so as to give a diameter somewhat larger than the circular non-connecting portion B2.
There was thus obtained a seamless tubular woven fabric 1 having a polymer covering layer 2 with a central zone, having a circular shape, formed by a non-connecting portion B2 o~ a tublllar weave structure B and a circumferential zone, having a ring-like shape, formed by a connecting portion Bl of the tubular weave structure B. (See Fig. 3.) Next, a hole was made in the center portion of the non-connecting portion B2 on one side, along with the polymerlayer 2, to form the gas introducing hole 3 and thus give an impact absorbing bag. (See Fig. 3.) F~lrther, this individual unit was turned inside out from the gas introducing hole 3 to prepare the desired impact absorbing bag. (See Fig. 4.) Note that (4) in Fig. 4 is a strip for limiting the inflation of the bag, which is provided according to need.
It is attached inside the bag between the top surface and bottom surface. This inflation limiting strip 4, as shown in Fig. 5, may be attached inside the bag between the top surface and bottom surface by tearing a portion of the top surface and bottom surface of the bag, adhering the two ends of the strip 4 so that they stick outside, then adhering a A
. ., . ~
reinforcement piece 5 over the attached portion.
Example 2 Use was made of nylon multifilament yarn as the warp and weft and weaving was performed using a dobby loom.
Except for this, the same procedure was followed as in Example l so as to prepare a continuous body of a seamless tubular woven fabric l.
Next, a film of an adipate ester type polyurethane elastomer was laid over the two surfa~es of a continuolls body of the seamless tublllar woven fabric l. The ~omposite was passed between heating rollers for lamination, thereby forming a polymer covering layer 2. A hole was made in the center portion of the non-connecting portion B2 of the tubular weave structure B on one side, along witA the polymer layer 2, to form the gas introducing hole 3.
Finally, this individual unit was turned inside O~lt from the gas introducing hole 3 to prepare the desired impact absorbing bag.
Example 3 Figures 6 to 8 are plan views showing other examples of the continuous body of the impact absorbing bag of the present invention.
In Examples l and 2, a single row of continuous bodies of a seamless tubular woven fabric l was obtained and the impact absorbing bag prepared from the same, but by providing a connecting portion B1 at not only the two edges, but also the width at the intermediate portion with the two edges in the tubular weaving step, it is possible to obtain two rows of continuolls bodies as shown in Fig. 6. It is also possible to prepare impact absorbing bags similarly from su~h two rows of continuous bodies.
The two rows of continuolls bodies in Fig. 7 are prepared by just repeating a necessary number of times just ... . ..
the step of tubular weaving wherein the length in the widtnw1se direction of the connecting portion Bl at the two edges is change.
The continuo-ls body of Fig. 8 was prepared by making the non-~onne~ting portion Bl of the tub-llar weave structure B a deformed circle in shape.
~ '7-
In many countries, drivers are obligated by law to use seat belts as one means of safety upon collisions, but the ef~ective reduction of the impact by seat belts is not sufficient when a car collides with an object at a high speed.
Therefore, use of an air bag system, i.e., a system capable of sensing an impact caused when a car collides with an object and instantaneously inflating a bag housed in a center portion of a steering wheel or the like to ensure the safety of the driver or the like is now being considered in many countries as a more reliable safety measure .
One conventional air bag has been manufact~lred by forming a polymer layer on a plain woven fabric, providing a gas introducing hole in one of the woven fabrics, superimposing two woven fabrics with polymer layers in a state with the polymer layer sides facing each other, and sewing together circumferential edges of the two woven fabrics. For example, Japanese Unexamined Patent Publication (Kokai) No. 51-4742, in the portion explaining the conventional air bags, describes that conventional air bags are obtained by cutting two circular pieces of woven fabrics from two regular square pieces of woven fabrics and sewing together the circumferential edges of the two circular pieces.
In air bags, a gas is instantaneously fed into the bag by explosion of a pyrotechnic, so the air bag m~lst have a strength sufficient to endure the impact force caused by the explosion. The above-mentioned method of manufacturing air bags using a sewing process has several problems in this regard. There are many manual working processes involved, so there is a chance of decreased strength of the sewn portions and inspections of the strength of the sewn portions and the air permeability of the woven fabric take much time. The overall reliability of air bags manufactllred by this method is low.
A method of manufacturing air bags using a tubular weaving method has been proposed. Japanese Examined Patent Publication (Kokoku), corresponding to Japanese Unexamined Patent Publication (Kokai) No. 57-58228, discloses an impact absorbing tubular woven fabric having bag portions formed by alternately folding two woven fabrics up and down at a middle portion. In this tubular weave, a bag portion A and a bag portion B having a connecting portion C, which consists of the upper woven fabric and lower woven fabric woven together in a jointed weave, are alternately provided. The bag portion B is smaller than the bag portion A. The fact that this tublllar woven fabric ~ould be coated was mentioned in this patent publication, but a detailed explanation was only given of a continuous body of an air bag.
F~rther, Japanese Examined Patent Publication (Kokoku) No. 54-576, corresponding to Japanese Unexamined Patent Publication (Kokai) No. 50-7232, di~scloses an impact absorbing bag having an upper connecting portion and a lower connecting portion having weft threads with larger shrinkage ratios than their warp threads. In the description of the invention and the drawings of this publication, there was shown an air bag having a square shape in plan view, provided at the outer layer thereof with a covering layer.
However, when making separate bags from the impact absorbing tubular woven fabric disclosed in Japanese Examined Patent Publication (Kokoku) No. 57-58228, the above tubular woven fabric should be cut along the widthwise direction in a portion indi~ated as C in Fig. 9 in the publication, so the shape of the cut fabric necessarily be~omes square. An air bag having a square shape has problems such that the air pressure is not applied uniformly over the air bag, the appearance of the air bag is inferior, and it is difficult to neatly house the air bag in the steering wheel. The impact absorbing bag disclosed in Japanese Examined Patent Publication (Kokoku) No. 54-576 also has a square shape, so it has the same problems.
It is possible to make the chamber into whicn air is blown an o~tagon by sewing the four corners of an air bag of a square shape (in this case, the appearance of the air bag is still square), but this sewn air bag has disadvantages of the large cost of the labor to sew the corners, the weaker strength of the sewn portions compared to the other portions, and the la~k of uniformity. Even if this air bag is turned inside out by pulling the inside of "~
..~. .
_ 4 _ 1337207 the air bag through the opening at the center portion of the air bag for the air insertion, only the appearance of the air bag is improved. The other disadvantages, such as the inferior uniformity, are not eliminated.
SUMMARY OF THE INVENTION
A first object of the present invention is to provide an impact absorbing bag having superior uniformity~
appearance, and reliability and having the ability to be easily manufactured.
A second obje~t of the present invention is to provide a preferable method of manufacturing the impact absorbing bag having the above-mentioned characteristics.
An impa~t absorbing air bag in accordance with the present invention consists of a seamless tubular woven fabric constituted with a central zone, having substantially a circular shape and formed by a non-connecting portion B2 of a tubular weave struct~re B, and a ~ircumferential zone, having a ring-like shape and formed by a connecting portion Bl of the tubular weave structure B or by the connecting portion Bl and a non-tubular weave structure A, wherein the transition between the non-tubular weave structure A and the tubular weave structllre B is continuous. Further, at least one portion of the sllrface of the seamless tubular woven fabric is provided with a polymer ~overing layer 2. A gas introducing hole 3 is provided in the non-connecting portion B2 of the tub-llar weave structllre B at one side of the seamless tubular woven fabric 1.
Another type of impat absorbing bag in accordance with the presen~ invention is a bag having an inside-out structure formed by pulling o~t the inside of the above-mentioned impact absorbing bag through the gas introducing hole.
The manufacturing method of the impact absorbing bag in ~ ,, ~,......
_ 5 13~7207 accordance with the present invention consists of the following steps, the order of which can be arbitrarily set:
a step of obtaining a continuo-ls body of a seamless tubular woven fabric by repeating a tubular weave strilcture B in which a plurality of warp threads are woven with a plurality of weft threads in a manner that the more the weft picking operation is repeated, first, the shorter the length in the widthwise direction of the connecting portion Bl and, then, the longer the length in the widthwise direction of the connecting portion Bl, so that a non-connecting portion B2 having a substantially circular shape is formed, or by alternately repeating the above-described tubular weave structure B and a non-tubular weave structure A;
a step of forming a polymer layer on at least a portion of a surface of the obtained continuous body or a segment cut from the said continuous body;
a step of c~ltting the continllous body of the seamless tublllar woven fabric, or a segment cut from the continllolls body, in a circular shape to give a seamless tubular woven fabric constituted with a central zone, having substantially a circular shape and formed by a non-connecting portion B2 of a tubular weave structure B, and a cir~umferential zone, having a ring-like shape and formed by a connecting portion Bl of the tubular weave structure B or by the connecting portion Bl and a non-tublllar weave structure A, the transition between the non-tubular weave structure A and the tubular weave structure B being continuous, and a step of providing a gas introducing hole in the non-connecting portion B2 of the tubular weave structure B at one side of the seamless tubular woven fabric.
Another manufacturing method of the impact absorbing bag in accordance with the present invention further includes a step of turning the impact absorbing bag inside ~,,;~, .. . .
Oilt by pulling out an inner side of the impact absorbing bag throl(3h the gas introducing hole.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a plan view illustrating an example of a continuous body of a seamless tubular woven fabric in accordance with the present invention;
Fig. 2 is a front view illustrating the continuous body illustrated in Fig. 1 and provided with a polymer layer;
Fig. 3 is a plan view illustrating an example of one individual unit of the seamless tublllar woven fabric provided with a gas introducing hole;
Fig. 4 is a cross-sectional view of an example of the impact absorbing bag in accordance with the present invention obtained by turning inside-out an individual unit of the impact absorbing bag illustrated in Fig. 3 through the gas introducing hole;
Fig. 5 is a cross-sectional view of another example of the impact absorbing bag obtained by turning inside-out an individual unit illustrated in Fig. 3 through the gas introducing hole; and Figs. 6 to 8 are plan views illustrating other examples of the continuous bodies of the impact absorbing bag in accordance with the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will now be described in detail with reference to the accompanying drawings illustrating embodiments.
As can be seen from Figs. 1 to 3, an impact absorbing bag in accordance with the present invention uses as a base woven fabric structllre a seamless tubular woven fabric 1 constituted with a central zone, having a substantially circular shape and formed by a non-connecting portion B2 of a tubular weave portion B, and a circumferential zone, A ~
,,,, . ., ~
l~372n7 having a ring-like shape and formed by a connecting portion Bl of the tubular weave structure B or by the connecting portion Bl and a non-tubular weave structllre, in which the transition between the non-tubular weave structure A and the tubular weave structure B is continuous.
The seamless tubular woven fabric as described herebefore can be obtained by preparing a contin-lo-ls body of the seamless tubular woven fabric manufactured by repeating at least one tubular weave structure B in which a plurality of warp threads~are woven with a plurality of weft threads in a manner that the more the weft picking operation is repeated, first, the shorter the length in the widthwise direction of the connecting portion B and then the longer the length in the widthwide direction of the connecting portion Bl, thus forming a non-connecting portion B2 having substantially a tubular shape, or by alternately repeating the above-described t~lbular weave structure and a non-tubular weave structure A, and then cutting the continuo-ls body of the seamless tubular woven fabric or a segment cut from the continuo~ls body in a substantially circ-llar shape.
For example, first, the non-tubular weave structure A
is formed by repeating a non-tubular weave until the predetermined length is obtained and then the tubular weave structure B having the connecting portion Bl and the non-connecting portion B2 of a substantially ring-like shape is manufactured by performing a tubular weave operation, i.e., a warp and weft double weaving weave in which a front layer and a back layer are connected to each other at both edge portions, in su~h a manner that the more the weft picking operation is repeated, first, the shorter the length in the widthwise direction of the conne~ting portion Bl and then the longer the length in the widthwise direction of the connecting portion Bl. After that, a continuous body in ,.
Af which a plurality of the seamless tub-llar woven fabrics are aligned in a row, as illustrated in Fig. 1, can be obtained by repeating th~non-tubular weaving operation and the tubular weaving operation gradually changing the length in the widthwise direction of the connecting portion Bl at both edge portions.
In this case, when a conne~ting portion Bl having some width is further arranged on a middle portion in the widthwise direction of the continuous body, a continuous body can be obtained in which a plurality of the seamless tubular woven fabrics are arranged in two rows as illustrated in Fig. 6. A continuous body in which a plurality of seamless tubular woven fabrics are arranged in rows of three or more can be easily obtained in the same manner as that of the previous case. Further, a continuolls body in which a plurality of sea~less tubular woven fabrics are arranged in a zigzag state as illustrated in Fig. 7 can be obtained by repeating a required number of times only the tublllar weaving operation in which the length in the widthwise direction of the connecting portion Bl at both edge portions is gradually changed and not applying the non-tubular weaving operation.
The weaving of the seamless tubular woven fabri~ can be performed by using a dobby loom, a jacquard loom, or the like.
The shape of the non-connecting portion B2 in the tubular weave stru~ture B is generally circular or nearly circular, but it is possible to make a deformed circle as illustrated in Fig. 8. The impact absorbing bag including the non-conne~ting portion B2 of the deformed circle can be usefully used as an air bag in the front passenger seat or the rear passenger seats.
A plain weave, twill weave, satin weave, or the like ~4 ~
~.,~
can be used as the weave in the non-~onnecting portion and the connecting portion.
As the weft thread and the warp thread used for manufacturing the seamless tubular woven fabric, a thread produced from a polyester fiber, polyamide fiber, including aramide fibers, acrylic fiber, polyvinyl alcohol fiber, polyvinylidene chloride fiber, polyolefin fiber, polyurethane fiber, fluoroplasti¢ fiber, semisynthetic fiber, regenerated fiber, natural fiber, ~arbon fiber, glass fiber, ceramic fiber, metal fiber, or the like can be used.
Further, a thread having a suitable elasticity can be llsed.
A polymer layer 2 is provided on at least one portion of a surface of the seamless tub~lar woven fabric 1 to prevent permeation of gases through the woven fabric 1.
Generally, the polymer layer 2 is provided on the entire surface of both sides of the seamless tubular woven fabric, but the polymer layer may also be provided on just the surface of the side facing the driver when the air bag is mounted in a steering wheel.
As examples of the polymer layer, mention may be made of film produced from a polyurethane resin, polyester resin, polyamide resin, polyvinylidene chloride resin, polyvinyl chloride resin, polyolefin resin, fluorine resin, sili~one resin, polystyrene resin, cellulose polymer, natural rubber, synthetic rubber, or the like. A polymer capable of forming an elastic film is useful. A poly~rethane elastomer, a polyester elastomer, a polyamide elastomer, a polyolefin elastomer, or the like can be used as typical elasti~
polymers. A polyurethane elastomer is particularly preferable. Here, "polyurethane elastomer" denotes a rubber-like elastic polymer having a urethane radical in its molecular structure and includes an adipate ester type, a polyether type, a caprola~tone type, and a polycarbonate ,~
type.
The polymer is generally applied in a film state, liquid state, solution state, dispersion state, or a molten state on the outer surface of both sides o~ the seamless tubular woven fabric and then is made into a laminate or covering by heating, drying, cooling, irradiation by activation energy, or the like.
Further, if necessary, it is possible to use a method in which the warp thread and/or weft thread is previously coated with the polymer, a fabric is made by the above warp threads and weft threads, and the woven fabric is heated to increase the flowability of the polymer on the surface of the thread so that gaps in the woven fabric structure are filled with the polymer.
The polymer layer 2 may be formed on the seamless tubular woven fabric 1 for individual units of the fabric 1.
However, it is more efficient to form the polymer layer on a continuous body of the seamless tubular woven fabrics. It is possible to apply the polymer layer to a segment cut from a continuous body, for example, a segment incl~ding two seamless tubular woven fabrics, a segment including three seamless tubular woven fabrics, or a segment having the shape of a square.
A gas introducing hole 3 is arranged on the tublllar weave structure B of the side of the seamless tubular woven fabric with the polymer layer. The gas introducing holes may be made in the continuolls body, the segments, or the individual units.
To obtain the individual units of the seamless tubular woven fabric from the contin-lous body, the connecting portion Bl of the tubular weave structllre B or the connecting portion Bl and the non-t~lbular weave structure A
may be cut in a circular shape along a position slightly ~ .~
. ~
ll- 1337207 apart from the circumferential edge of the non-connecting portion B2 having a substantially circular shape in the tubular weave structure B. It is advantageous to use melting rather than mechanical cutting as a cutting method. Thus, individual units including the non-connecting portion B2 having the circular shape of the tubular weave structure B
and a ring-like portion arranged circumferentially on the non-connecting portion B2 and cornprising the connecting portion Bl or the ~onnecting portion Bl and the non-tubular weave structure A is obtained.
The polymer layer 2 is generally formed on the seamless tubular woven fabric 1 from the outside of the fabric 1.
Therefore, the bag obtained ~y this method has a slightly inferior feeling. Further, since the connecting portion Bl of the tublllar weave structure B or the connecting portion Bl and the non-tubular weave structure A are present in a circumferential portion of the bag, the appearance of the bag is not always good. If the bag is turned inside-out by pulling out the inside of the air bag through the gas introducing hole 3, the feeling and the appearance of the obtained air bag are remarkably improved. Therefore, it is advantageous to use an inside-out air bag in terms of the merchandiseability.
It is possible to provide one orrnore strands or strips ~5 4 inside the impact absorbing bag in accordance with the present invention for limiting the inflation of the bag between the front of the bag, as seen from the driver's position, and the opposite side of the bag, as illustrated clearly in Figs. 4 and 5.
The impact absorbing bag in accordance with the present invention is housed in the central portion of the steering wheel with the gas introducing hole 3 connected to a gas generator. When an impact of a predetermined value or more, A ~
~ se ~
for example, an impact generated when a car having a speed of 16 km/hr or 25 km/hr collides head on with an object, is sensed by a mechanical sensor or an electrical sensor, gas generated by a pyrotechnic is suddenly fed into the bag, and the bag is simultaneously inflated. For example, the bag is inflated in 0.08 second after sensing of the impact. It is also possible to feed a gas having a high pressure from a gas cylinder. When the air bag is used for the front passenger seat or rear passenger seats, portions capable of housing the impact absorbing bags may be suitably arranged inside the car.
The impact absorbing bag according to the present invention uses as a base woven struct~re a seamless tubular woven fabric constituted with a central zone, having substantially a circular shape and formed by a non-connecting portion B2 of a tubular weave structure B, and a circumferential zone, having a ring-like ~hape and formed by a connectinq portion Bl of the tubular weave structilre B or by the conne~ting portion Bl and a non-tubular weave struct~lre A, wherein the transition between the non-tubular weave structure A and the t~lbular weave structure B is continuous. Due to this, it is superior in terms of uniformity, strength, and adjustment of the air-permeability compared with the conventional method of forming a bag by cutting out circular pieces of fabric from two square pieces of fabric and sewing together the circumferences of the same. Therefore, a high degree of reliability can be ensured as an impact absorbing bag. Further the manufactllring steps are streamlined and inspection time can be reduced, so it is advantageous in terms of productivity as well.
Even compared with a sq~are shaped air bag, seen in plan view, prepared from a tubular weave, the impact absorbing bag of the present invention is far superior in A
terms of the overall uniformity of application of the air pressure, the external appearane, and the capability of housing in a steering wheel.
The impact absorbing bag of the present invention, housed in the center portion of the steering wheel, is useful for the object of instantaneously inflation when sensing an impact of collision of the car and ensuring driver safety. It may be used not only for the object of ensuring driver safety, but also for the object of ensuring the safety of the passengers in the front passenger seat and rear passenger seats.
The present invention will now be explained in further detail by examples, which do not, however, limit the invention in any way.
Example 1 Figures 1 to 4 show an example of the steps for manufactilring an impact absorbing bag according to the present invention.
Use was made of polyester multifilament yarn as the warp and weft and weaving was performed using a jacquard loom. First, non-tubular weaving was performed until a predetermined width to form a non-tubular weave structure A, then tubular weaving wherein the upper and lower layers are joined only at the two edge portions was performed so that the more the weft picking operation was repeated, first, the shorter the length in the widthwise direction of a connecting portion Bl and, then, the longer the length in the widthwise direction of the connecting portion Bl, so that a tubular weave struct~re B was formed. This non-tubular weaving step to the tubular weaving step wherein thelength of the connecting portion Bl at the two edges was changed was repeated.
By this, a continuous body of a single row of a ,eamless tubular woven fabric 1 having a non-connecting portion B2 of a tubular weave structllre B which is substantially circular in shape is obtained. (See Fig. 1.) From the two sides of the continllolls body of the seamless tubular woven fabric 1 was coated a polyether type polyurethane elastomer. This was heated to dry and further cured to form a polymer covering layer 2. (See Fig. 2.) Next, separate circular pieces were cut by melting at the connecting portion Bl of the tubular weave structure B
and the non-tubular weave stru~ture A so as to give a diameter somewhat larger than the circular non-connecting portion B2.
There was thus obtained a seamless tubular woven fabric 1 having a polymer covering layer 2 with a central zone, having a circular shape, formed by a non-connecting portion B2 o~ a tublllar weave structure B and a circumferential zone, having a ring-like shape, formed by a connecting portion Bl of the tubular weave structure B. (See Fig. 3.) Next, a hole was made in the center portion of the non-connecting portion B2 on one side, along with the polymerlayer 2, to form the gas introducing hole 3 and thus give an impact absorbing bag. (See Fig. 3.) F~lrther, this individual unit was turned inside out from the gas introducing hole 3 to prepare the desired impact absorbing bag. (See Fig. 4.) Note that (4) in Fig. 4 is a strip for limiting the inflation of the bag, which is provided according to need.
It is attached inside the bag between the top surface and bottom surface. This inflation limiting strip 4, as shown in Fig. 5, may be attached inside the bag between the top surface and bottom surface by tearing a portion of the top surface and bottom surface of the bag, adhering the two ends of the strip 4 so that they stick outside, then adhering a A
. ., . ~
reinforcement piece 5 over the attached portion.
Example 2 Use was made of nylon multifilament yarn as the warp and weft and weaving was performed using a dobby loom.
Except for this, the same procedure was followed as in Example l so as to prepare a continuous body of a seamless tubular woven fabric l.
Next, a film of an adipate ester type polyurethane elastomer was laid over the two surfa~es of a continuolls body of the seamless tublllar woven fabric l. The ~omposite was passed between heating rollers for lamination, thereby forming a polymer covering layer 2. A hole was made in the center portion of the non-connecting portion B2 of the tubular weave structure B on one side, along witA the polymer layer 2, to form the gas introducing hole 3.
Finally, this individual unit was turned inside O~lt from the gas introducing hole 3 to prepare the desired impact absorbing bag.
Example 3 Figures 6 to 8 are plan views showing other examples of the continuous body of the impact absorbing bag of the present invention.
In Examples l and 2, a single row of continuous bodies of a seamless tubular woven fabric l was obtained and the impact absorbing bag prepared from the same, but by providing a connecting portion B1 at not only the two edges, but also the width at the intermediate portion with the two edges in the tubular weaving step, it is possible to obtain two rows of continuolls bodies as shown in Fig. 6. It is also possible to prepare impact absorbing bags similarly from su~h two rows of continuous bodies.
The two rows of continuolls bodies in Fig. 7 are prepared by just repeating a necessary number of times just ... . ..
the step of tubular weaving wherein the length in the widtnw1se direction of the connecting portion Bl at the two edges is change.
The continuo-ls body of Fig. 8 was prepared by making the non-~onne~ting portion Bl of the tub-llar weave structure B a deformed circle in shape.
~ '7-
Claims
1. A seamless woven fabric used for manufacturing an impact-absorbing bag comprising a tubular weave structure and a non-tubular weave structure; said tubular weave structure having a connecting portion and a non-connecting portion; said connecting portion defining a circumferential zone, having a ring-like shape; said non-connecting portion constituting a central zone of the bag, having substantially a circular shape; said tubular weave structure having opposite sides; said non-tubular weave structure is contiguous with said tubular weave structure; said bag including a gas introducing hole provided in said non-connecting portion of said tubular weave structure at one of said opposite side.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000616920A CA1337944C (en) | 1987-12-11 | 1994-08-25 | Impact absorbing bag and manufacturing method thereof |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31493487 | 1987-12-11 | ||
| JP62-314934 | 1987-12-11 | ||
| JP31240488A JPH0692218B2 (en) | 1987-12-11 | 1988-12-09 | Shock absorbing bag and manufacturing method thereof |
| JP63-312404 | 1988-12-09 |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000616920A Division CA1337944C (en) | 1987-12-11 | 1994-08-25 | Impact absorbing bag and manufacturing method thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1337207C true CA1337207C (en) | 1995-10-03 |
Family
ID=26567158
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000585682A Expired - Fee Related CA1337207C (en) | 1987-12-11 | 1988-12-12 | Impact absorbing bag and manufacturing method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1337207C (en) |
-
1988
- 1988-12-12 CA CA000585682A patent/CA1337207C/en not_active Expired - Fee Related
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| MKLA | Lapsed |