JP2002370597A - Air bag - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air bag with a high unfolding pressure resistance which is light weight and can be accommodated at compact and in which a stress concentration is dispersed at a sewing part of a hanging string to occupant side foundation cloth. SOLUTION: In the air bag formed to a bag-like shape, an air bag body is constituted by a woven fabric of which METSUKE (weight/unit area) is 180 g/m<2> and the hanging string for restricting unfolding popping out length of a bag body by fastening the occupant side and the opposite side thereto is provided on the inside of the air bag body. The hanging string is sewed to the occupant side of the air bag body by a stitch line of curved line comprising a long circle. A major diameter of an ellipse is positioned at a right angle to the longitudinal direction of the hanging string and has length equal to or longer than a width of the hanging string.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an airbag for protecting an occupant in the event of a collision of an automobile.

[0002]

2. Description of the Related Art In recent years, airbag systems have become widespread as safety devices for protecting occupants of automobiles, and the number of mounting parts has increased from driver's seat to passenger seat, side collision protection (side bag), and rear seat. Is coming. In this way, as the number of airbags and the number of airbags mounted on them increase, the demand for lighter and more compact airbag systems has begun.
Each component of the system has been designed to be smaller and lighter. Airbag bags have also been reduced in weight by making them non-coated and reducing the bag folding storage capacity.

[0003] Under such circumstances, with regard to the fabric used for the bag or member of the airbag, it has been studied to reduce the weight of the fabric by reducing the thickness of the constituting yarn.
940 dtex (840 denier) conventionally used
Airbags composed of woven fabric using finer 470 dtex (420 denier) yarns have been put into practical use.
Further, Japanese Patent Application Laid-Open No. 3-137245 discloses that 300 to 4
A non-coated woven fabric for airbags using a raw yarn of 00 dtex (270 to 360 denier) has been proposed. However, when these nonwoven fabrics are used as non-coated bags, high-density fabrics must be used to reduce the air permeability. The characteristics are also reduced, and no remarkable effect is recognized from the viewpoint of reducing the weight of the airbag.

[0004] Therefore, using a finer yarn,
Proposals have been made to create extremely light woven fabrics to further reduce the weight of airbags. For example, USP548
Japanese Patent No. 2317 discloses 50 dtex (45 denier).
An airbag using a woven fabric using nylon 66 of up to 160 dtex (140 denier) is described. The basis weight of these fabrics is half or less than that of conventional airbag fabrics, and exceeds the conventional level in terms of weight reduction.

[0005] On the other hand, a suspending string for regulating the amount of protrusion in the occupant direction when deployed is provided inside a normal airbag. The fixing of the suspension string to the airbag body, particularly to the occupant-side base cloth, is often directly sewn without using a fixing cloth piece in order to reduce the weight. A large impact force generated when the airbag is initially protruded is applied to the sewn portion of the hanging string to the airbag body, and in the case of a woven fabric having a small basis weight as used in the present invention, a sharp tension of the sewing thread is applied. As a result, the seam may be enlarged, and in some cases, the hot gas may erupt from the enlarged seam, causing the base cloth at the seam to melt.

In order to avoid the above-mentioned problem, for example, Japanese Utility Model Laid-Open No. 5-46615 discloses that when the ends of the cords are directly sewn and fixed to the occupant-side fabric, both ends in the width direction of the cords are fixed. Although a method of setting a non-sewn portion having a predetermined width has been proposed, the sewn portion becomes narrower than the width of the cord body, and it is difficult to avoid stress concentration on the sewn portion. Japanese Patent Application Laid-Open No. 3-164349 discloses that the length of a sewn portion formed in a direction orthogonal to the longitudinal direction of the belt is made longer than the width of the belt to reduce stress concentration on the sewn portion. Although the method is described, the belt is sewn to a piece of cloth called a belt catch other than the airbag body base cloth, and in such a method, the lightweight and compact storage that is the object of the present invention is performed. A possible airbag cannot be realized.

Further, Japanese Patent Application Laid-Open No. 2000-255357
Japanese Patent Publication No. has a fineness of 220 dtex (200 denier).
There is disclosed a method of sewing a hanging string which can be applied to an airbag made of a fabric having a basis weight of 150 g / m ² or less using the following yarns. However, in recent years, further improvement in occupant restraint capability has been demanded, and demand for improvement in pressure resistance during deployment of an airbag (hereinafter, also referred to as deployment pressure resistance) has been increased due to an increase in deployment gas output of an inflator. . Accordingly, an airbag that is lightweight and compact and has a higher deployment pressure than before has been desired.

[0008]

SUMMARY OF THE INVENTION The present invention is lighter and more compact than conventional airbags, and has a reduced stress concentration at the sewn portion of the suspension string to the occupant-side fabric.
It is an object of the present invention to provide an airbag having a high deployment pressure.

[0009]

Means for Solving the Problems The inventors of the present invention have studied the deployment pressure resistance of a lightweight and thin woven fabric in order to put it into practical use as an airbag with a high-output type inflator. It was found that a major factor influencing the melt was melt fracture caused by the thin fabric constituent yarns being melted by hot gas jetting at the seams.

Therefore, as a result of further study, by specifying the sewn shape and the sewn conditions of the suspending string, the stress concentration at the sewn portion of the suspending string during the deployment of the airbag is dispersed, and It has been found that the opening of the airbag is suppressed, and an airbag compatible with a high-output inflator can be obtained, and the present invention has been accomplished. That is, the present invention is as follows.

1. An airbag formed in a bag shape, wherein the airbag body is formed of a fabric having a basis weight of 180 g / m ² or less, and the occupant side and the opposite side are connected to the inside of the airbag body to deploy the bag body. A hanging string for regulating the protrusion length is provided, and the hanging string is sewn to the occupant side of the airbag body at a curved stitch line composed of an ellipse, and the major axis of the ellipse is the length of the hanging string. An airbag, wherein the airbag is positioned at right angles to the direction, and the major axis has a length equal to or greater than the width of the hanging string.

2. The major axis a (mm) and minor axis b (m
m) and the width w (mm) of the hanging string are expressed by the following formulas (1) to (1).
(4) The airbag as described in (1) above, which simultaneously satisfies (4). 1 <a / b <15 (1) 20 ≦ b ≦ 200 (2) 100 ≦ a ≦ 700 (3) 20 ≦ w ≦ 150 (4) The above 1 wherein the ellipse is an ellipse composed of a major axis a and a minor axis b.
Or the airbag according to 2.

4. The sewing of the hanging string to the airbag body satisfies the following expressions (5) and (6).
The airbag according to any one of the above items 1 to 3, wherein the airbag is sewn under the conditions of x) and the number of needles S (needle / cm). 200 ≦ T ≦ 1700 (5) 2 ≦ S ≦ 6 (6) Hereinafter, the present invention will be described in detail.

According to the present invention, the air sewn with a specific structure and sewing specifications can withstand an impact when the air bag is deployed, despite the fact that the woven fabric is an extremely thin and flexible fabric having a basis weight of 180 g / m ² or less. The bag is provided. An air bag according to the present invention, a basis weight of 180 g / m ² or less, preferably constructed the bag body fabric is 100 to 160 g / m ^2, of the bag by connecting the occupant side and the opposite side inside the air bag body A suspending string for regulating the protruding length is provided, and the suspending string is sewn to the airbag body on the occupant side of the airbag body and on the opposite side.

In the present invention, a plurality of, for example, two, suspending cords may be separately provided, but preferably, the fixing portion is provided substantially at the center of the suspending cord, and the fixing portion is provided on the airbag body base cloth. The sewing machine is sewn to the center part of the occupant side, and both ends of the pair of hanging straps are sewn to the other side of the opposing airbag body. In this case, it is preferable that both ends extending from the central portion of the suspension string be sewn to the airbag body together with the reinforcing cloth of the opening for inserting the inflator.

In the present invention, it is important that the stitch line shape of the sewn portion of the fixing portion to the airbag body is configured as follows. That is, the hanging string is sewn to the occupant side with a curved stitch line composed of an ellipse, the major axis of the ellipse is located at right angles to the longitudinal direction of the strap, and the major axis is equal to or greater than the width of the strap. Have a length. By forming the stitch line in such a shape, the impact force at the time of inflation of the airbag can be uniformly received over the entire sewn portion. Further, the stress of the entire sewn portion can be reduced, and the stress concentration can be shifted to the hanging string side.

First, an elliptical stitch line is a curve in all parts of the line and has no singular point. That is, since there is no portion having a double tangent and the inclination of the tangent always changes smoothly, the stress distribution is good. In a line such as a joint between a straight line and a curved line or a joint between a curved line and a curved line, a tangent line is doubled at the joint point and becomes a stress concentration point. Next, by arranging the major axis at right angles to the longitudinal direction of the suspending string in a circular stitch line consisting of an oblong, a gentle line having the minor axis end of the oblong, that is, the maximum tangent radius, at the width center of the suspending string. Are orthogonal, and the stress can be assumed as a whole. Further, both wings of the stitch line receiving the stress release the stress because the tangents of the two wings are parallel to the longitudinal direction of the suspension string at the long diameter end of the ellipse. On the other hand, when the stitch lines are perpendicular to each other at the center of the suspension string, stress concentration occurs at both ends of the straight line segment. In addition, when a true circle stitch line or a long-diameter end of an ellipse is perpendicular to the center of the hanging string, stress concentration at the perpendicular point is large. Preferred oval shapes are a major axis a (mm) and a minor axis b
(Mm).

Further, in the present invention, the major axis a (mm) of the stitch line has a length equal to or larger than the width w (mm) of the hanging string. This is because the stress applied to the entire width of the suspension string during deployment of the airbag is received by a longer sewing portion to distribute the stress. The width w of the hanging string referred to here is the smallest width among the string widths taken at right angles to the longitudinal direction of the hanging string. FIG. 7 shows an example of the shape of the stitch line in the hanging string.

The shape of the elliptical stitch line has a major axis a
(Mm), minor diameter b (mm), and width w (mm) of the hanging string
However, it is preferable that the following formulas (1) to (4) are simultaneously satisfied. 1 <a / b <15 (1) 20 ≦ b ≦ 200 (2) 100 ≦ a ≦ 700 (3) 20 ≦ w ≦ 150 (4) The ratio a / b of the major axis to the minor axis is 1 It is preferably in the range of <a / b <15, more preferably 2 <a / b ≦ 10, and still more preferably 3 <a / b ≦ 10. a /
The stress distribution at the center of the hanging string width becomes possible in an ellipse where b exceeds 1, and the larger the value is, the more the sewn part of the hanging string receives the stress with a curve having a large tangent radius. Has good stress dispersion. On the other hand, if the value of a / b is too large, there is a tendency for stress concentration to occur at the long diameter end.

The minor diameter b (mm) is preferably from 20 to 200 mm, and more preferably from 20 to 150 mm. Since the smaller the minor diameter b (mm), the better the stress dispersion, the smaller the minor diameter b (mm), the smaller the diameter is, preferably 200 mm or less. Preferably, there is.

The major diameter a (mm) is preferably from 100 to 700 mm, more preferably from 100 to 650 m.
m. The larger the major diameter a (mm) is, the better the stress dispersion is. However, if the length is within the above range, it is preferable in terms of stress dispersion, and distortion as the deployed shape of the entire airbag is acceptable. The width w (mm) of the hanging string is preferably in the range of 20 ≦ w ≦ 150, more preferably 30 to 100 mm
It is. Since the width of the hanging string is more effective for dispersing stress in an expanded shape when the airbag is deployed,
mm or less is preferable. On the other hand, the width of the suspending string is determined according to the mechanical properties of the base fabric used for the suspending string due to the demand for mechanical strength enough to support the impact force during deployment. 20 mm or more is preferable from the point of view.

The shape of the suspending string is preferably a fan-like shape in which the sewn portion expands in accordance with the shape of the stitch line as compared with the width of the string, and the width of the string increases toward the stitch line. In the present invention, depending on the type, specifications, etc. of the airbag, the number of the hanging strings, the material, etc. may be appropriately selected, for example, even if the fabric is the same as the airbag body, another thick body is used. Denier yarn, for example,
A woven fabric made using 235 to 940 dtex (210 to 840 denier) yarn, a belt-like woven fabric made by a special loom for narrow width fabric, a knitted fabric by warp knitting, or the like may be used. When cutting a suspending string from a wide woven or knitted fabric, the cutting direction may be a direction parallel to the warp or the weft of the woven fabric, or a direction intersecting with the warp or the weft, for example, a bias direction of 45 °. May be appropriately selected according to the characteristics of the hanging string to be suspended.

In the present invention, it is also preferable that the yarn axis of the fabric forming the occupant-side base fabric of the airbag body is in the bias direction with respect to the length direction of the suspension cord. By doing so, the seam of the sewn portion is always generated at a different weave portion with respect to the yarn constituting the woven fabric, so that the stress applied to the seam can be borne by many yarns. This is effective in reducing stitch misalignment.

Further, in the present invention, when sewing the suspension string to the occupant-side base fabric and / or the side opposite thereto, the thread count and the number of stitches satisfy the following formulas (5) and (6). It is preferable to set T (dtex) and the number of hand movements S (needle / cm). 200 ≦ T ≦ 1700 (5) 2 ≦ S ≦ 6 (6) In the present invention, when sewing a very flexible woven fabric having a basis weight of 180 g / m ² or less, a base fabric is sewn by a sewing method similar to the conventional one. May be damaged. In particular, 3
The single yarn constituting the raw yarn of 50 dtex (315 denier) or more has a single yarn fineness of 6.7 dtex (6 denier) or more, and one yarn is relatively thick. As in the present invention, in order to meet the requirement of the flexibility of the airbag, the single yarn fineness of the original yarn is 3.3 dtex.
(3 denier) Because the following thin thread is used, if sewing is performed using a thick sewing thread count and a corresponding thick sewing needle, the single thread may be damaged by the tip of the sewing needle or the thick thread count may penetrate. There is a tendency for large seam holes to be forcibly formed in the fabric. As a result, the thread damaged by the sewing machine needle or a large stitch hole will be the starting point, and the surrounding woven fabric to which the hanging string is sewn will be opened by the impact force when the airbag is deployed, and in some cases, Could be damaged.

In the present invention, the suture fineness T (dtex) of the suture used for the sewn fixing portion between the suspension cord and the airbag body, particularly, the occupant-side base fabric, is set to be in a range of 200 ≦ T ≦ 1700. Is more preferable, and it is more preferable to set the range of 400 ≦ T ≦ 1000. By setting it in this range, a sufficient reinforcing effect of the stitched portion can be obtained without forming a large stitch hole in the woven fabric.

In the present invention, an optimum stitch strength can be obtained by using an appropriate number of stitches S (needle / cm) for the thread count T. That is, the number of hand movements S is 2 ≦ S ≦
6, more preferably 3 ≦ S ≦ 5
It is. When the number of stitches S is within the above range, sufficient stitch strength can be ensured, and the stitches can be expanded even if the distance between stitches is moderate and a sudden impact is received. There is no. Therefore, there is no possibility that hot gas is blown out from the seam to melt the base cloth between the adjacent seams or that the seam continues to form a large damaged portion.

In the present invention, the sewing machine needle used for sewing is a needle number 2 used for sewing a conventional airbag.
A sewing needle that is thinner than a thicker needle of zero or more, for example, 18
It is preferable to use a count, a count, or the like. Further, it is more effective to use a ball point type sewing machine needle having a rounded tip portion. The seam specifications may be selected according to the fabric to be used, the specifications of the airbag, the required strength of the sewn portion, and the like. For example, lockstitch, double chain stitch, staggered stitch, flat stitch, etc. Can be used,
These combinations may be used. The stitches may be in a single row or in multiple rows, depending on the required characteristics. Preferably,
Two-row stitching with a gap of 5 mm or more is preferred for lockstitching.

In the present invention, the sewing thread used is an upper thread,
When the thread count is different for the lower thread and the like, it is desirable that all the sewing threads satisfy the relationship of the above-described formula (5), but only one of the upper thread and the lower thread satisfies the relationship of the formula (5). do it. The sewing thread used in the present invention may be appropriately selected from those generally called synthetic fiber sewing threads and those used as industrial sewing threads. For example, nylon 6, nylon 66, nylon 46, polyester, vinylon,
Examples include yarns of aramid, fluorine-based polymer, carbon, glass, and the like, and may be any of spun yarn, filament plied yarn, and filament resin impregnated yarn.

In the present invention, the fineness of the yarn used for the woven fabric of the airbag bag is preferably 250 dtex or less, more preferably 100 to 250 dte.
x, more preferably 150 to 200 dtex.
In addition, the texture of the fabric used for the bag and the hanging string is plain weave,
It may be any of scribble weave (basket weave), twill weave, lattice weave (rip-stop weave), or a composite structure of them. In some cases, various irregularities are obtained by using a dobby device or jacquard device with a loom. It may be an organization. In order to manufacture these woven fabrics, it may be appropriately selected from various looms used for weaving ordinary industrial woven fabrics,
For example, shuttle looms, water jet looms (WJ
L), an air jet loom (AJL), a rapier loom, a projectile loom, a multi-phase loom, or the like can be used.

The cut shape of the bag of the airbag may be any of a circular shape, an oval shape, an elliptical shape, a rectangular shape, a polygonal shape, or a combination thereof, and may be any shape that satisfies the desired deployed shape. Depending on the performance of the inflator, the capacity of the airbag, the use site, etc., the fabric constituting the airbag of the present invention may be provided with a heat-resistant elastomer and may be impermeable, or may be completely impermeable. A non-coated fabric that is not applied may be used. In the case of a non-coated fabric, scouring, drying, heat setting, etc. may be performed, and conditions such as heat setting temperature may be selected in consideration of air permeability, mechanical characteristics, and the like. Further, a fabric obtained by adding a heat-resistant elastomer to a part of an airbag made of a non-coated fabric may be used in combination.

When a heat-resistant elastomer is applied to a woven fabric, the method of applying the heat-resistant elastomer is as follows: 1) coating method (knife, kiss, reverse, etc.), 2) dipping method,
3) Processing methods such as printing (screen, roll, rotary, etc.) can be used.
Any of a solvent system, an emulsion system, an aqueous solution system, and a fine powder system may be used. The amount of adhesion may be smaller than that of a conventional coating cloth, for example, 10 g / m ² or less.

The heat-resistant elastomer may be interposed on at least one surface of the woven fabric, a gap between the woven fabrics, or a part or all of the gap between the fiber yarns. The heat-resistant elastomer may be any material to which the above-mentioned processing method can be applied, and examples thereof include silicone-based, fluorine-based, chlorine-based, polyurethane-based, epoxy-based, polyester-based, polyamide-based, polyimide-based, chlorsulfone-based, and phenol-based elastomers. , Acrylic or the like, or a mixture of two or more of these, or copolymers may be appropriately selected, but from the viewpoint of improving the mechanical properties of the woven fabric, heat resistance, etc., silicone-based, fluorine-based, and polyurethane-based are preferred. Particularly preferred.

Further, in order to improve the adhesion to the fabric, various pretreatment agents and adhesion improvers may be added to the heat-resistant elastomer, or the surface of the fabric may be subjected to a pretreatment such as a primer treatment in advance. You may. Further, a processing agent for imparting further heat resistance, anti-aging property, oxidation resistance and the like to the elastomer may be added. In order to improve the physical properties of the elastomer, after applying the elastomer to the fabric, drying, crosslinking, vulcanization, etc., hot air treatment, contact heat treatment, high energy treatment (high frequency, electron beam, ultraviolet treatment)
And so on.

In the present invention, the fiber yarn constituting the woven fabric is not particularly limited.
Nylon 66, Nylon 46, Nylon 610, Nylon 612 or the like alone, or polyamide fiber, polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polybutylene terephthalate, polyethylene naphthalate or the like obtained by copolymerization or mixing thereof;
Or an aramid fiber, a wholly aromatic polyester fiber, a vinylon fiber, an ultra-high molecular weight polyethylene represented by a polyester fiber obtained by copolymerization and mixing thereof, paraphenylene terephthalamide, and a copolymer thereof with an aromatic ether, and the like. Such as polyolefin fibers, vinyl chloride and vinylidene chloride fibers, fluorine fibers including polytetrafluoroethylene, polysulfone (PSf) fibers, polyphenylene sulfide (PP)
S) Fiber, polyetheretherketone (PEEK)
Fiber, polyimide fiber, polyetherimide fiber, cellulosic fiber including high-strength rayon, acrylic fiber,
Carbon fiber, glass fiber, silicone carbide (Si
C) It may be appropriately selected from fibers, alumina fibers, and the like. In some cases, inorganic fibers such as metal fibers represented by steel may be included.

The yarn is not particularly limited, such as filaments of long fibers, spun yarns of short fibers, and composite yarns thereof. In some cases, processing such as twisting, bulking, crimping, and winding may be performed. These fiber yarns, spinnability and processability, various additives commonly used to improve the durability of the material, for example, heat stabilizers, antioxidants, light stabilizers, antiaging agents, One or more of a lubricant, a smoothing agent, a pigment, a water repellent, an oil repellent, a hiding agent such as titanium oxide, a gloss imparting agent, a flame retardant, a plasticizer, and the like may be used.

The airbag according to the present invention includes a driver seat, a passenger seat,
The present invention can be applied to any of commonly used airbag application sites such as a side (including an inflatable curtain) and a rear seat.

[0037]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In addition, the performance evaluation of the airbag was performed by the following method. (Deployment test) Driver inflator (non-azide type,
Maximum tank pressure of 60 liters; 185kPa, 200k
Pa, 215 kPa).

Using a fixing bracket and a resin cover, the bag was folded and assembled into a module. After being preheated at 100 ° C. for 4 hours, a deployment test was conducted. The state of damage was observed and evaluated according to the following criteria. Pass: No breakage, and no change in the stitch line (seam) of the occupant-side base fabric of the hanging string, such as a clear opening.

Misalignment: No bag breakage, but a stitch line (seam) of 1 mm or more is recognized on the stitch line (seam) of the occupant-side base fabric of the hanging string. Broken bag: A bag that has been broken during deployment. [Examples 1 to 6, Comparative Example 1] Nylon 66 fiber 155d
Using tex / 84f (original yarn strength of 7.7 cN / dtex), the density of the woven fabric is 91, and the weft is 91 / 2.54 cm.
Was woven. The woven fabric was scoured and heat-set to obtain a non-coated woven fabric N having a woven density of 91.5 yarns / 2.54 cm in both wefts. The fabric weight was 121 g / m ² .

From the obtained non-coated fabric, two circular cloths (1, 2) having an outer diameter of φ720 mm as shown in FIGS. 1 and 2 were cut, and an opening of φ70 mm was formed at the center of the circular cloth 1 as an inflator mounting port. And φ3 as exhaust hole
Two 5 mm circular holes were provided. On the other hand, 470 dt of nylon 66 fiber was
ex / 70f, weaving plain fabrics A and B, scouring,
Heat set. The obtained plain woven fabric A was used as a non-coated woven fabric having a woven fabric density of 53 / 2.54 cm for both wefts, and a plain woven fabric B of 46 woven fabrics / 2.54 cm for both woven fabric density and weft, 40 g / m ^{2 of} silicone rubber was applied to use as a coated fabric. From plain fabrics A and B,
The outer diameter φ220 mm and the inner diameter φ70 m shown in (1) and (2) of FIG.
m of the donut-shaped cloth was cut.

In the center of the circular cloth 1, a reinforcing cloth piece A of a non-coated cloth cut from the plain cloth A ((1) and (2) in FIG. 3)
As shown on the right side of FIG. 4, the circular cloth and the reinforcing cloth are overlapped with each other in the direction of the respective yarn axes, and the stitch diameter is 195 m.
m (outer layer) and 135 mm (middle layer). As the sewing thread, a 30th thread (470 dtex) of nylon 66 was used for both the upper thread and the lower thread, and the main thread having a stitch number of 6 stitches / cm was sewn with a 16th sewing machine needle.

Further, a reinforcing cloth B (left side in FIG. 4) of a coated cloth having the same shape and structure as that shown in FIG. In the same manner as described above, the yarns were overlapped in the direction of the thread axis, and sewed together at a seam diameter of 76 mm (inner layer). As the sewing thread, a fifth thread (1400 dtex) of nylon 66 was used for both the upper thread and the lower thread, and the main thread was stitched at 4.5 stitches / cm and the sewing machine was sewn with a 23rd-number sewing machine needle.

Further, as a reinforcing cloth piece of the exhaust hole, a plain woven fabric A
Cut two pieces of donut-shaped cloth with an outer diameter of 65 mm and an inner diameter of 35 mm from each other, superimposed one by one on the exhaust hole of the circular cloth 1 and sewed them together with a seam diameter of 50 mm. No. 30 yarn of 66 yarn (470 dt
ex), the stitches were sewn together with a 16th sewing machine needle in a lockstitch having a stitch number of 4 stitches / cm.

Next, the circular cloth 1 in which the reinforcing cloth pieces are sewn together.
A bolt hole for mounting an inflator having a hole diameter of φ55 mm was formed in the center of. The opening position was in the yarn axis direction of the reinforcing cloth as shown in FIG. Also, from the bias direction of the plain fabric N, as a hanging string (refer to FIG. 6 for the hanging string), a strip having a minimum width wmm (the value of w is shown in Table 1) and a length of 600 mm, and an elliptical shape in the center. A piece of cloth (see FIG. 7) having an oval bulge for providing a sewn portion was cut. As shown in FIG. 7, the center part of the hanging string is superimposed on the center of the circular cloth 2 and the 20th thread (700 dtex) of nylon 66 thread is used and the main stitching is performed at 4.5 stitches / cm. Sewing was performed in two rows of shapes (major axis a, minor axis b; values of a and b are shown in Table 1).

Next, the circular cloth 1 (FIG. 1) and the circular cloth 2 (FIG. 2) were overlapped at a position where their respective yarn axes were shifted by 45 °, and sewn 20 mm inside from the outer diameter. As for the sewing thread, the upper thread is nylon 66 thread No. 8 (940 dte
x), No. 30 thread of nylon 66 thread (470 dte)
Using x), sewing was performed with a 18th-number sewing machine needle by double chain stitching (two rows) having a stitch number of 5 stitches / cm.

Finally, both ends of the hanging string are superimposed on the extended ears of the reinforcing cloth ((2) in FIG. 3) sewn on the circular cloth 1, and the nylon 66 thread 8th (940 dtex) is laid. Using the lock stitch, the number of needles was sewn at 3.5 stitches / cm and fixed. The obtained airbag was inverted from the mounting port and subjected to a deployment test. Table 1 shows the test conditions and results.

[Comparative Example 2] The procedure was performed in the same manner as in Example 1 except that the occupant-side sewn portion of the suspension string was a circular outer circumferential stitch line having a diameter of 170 mm (Fig. 10). Table 1 shows the test conditions and results. [Comparative Example 3] The occupant-side sewn portion of the hanging string was 150 mm on a side.
The procedure was performed in the same manner as in Example 1 except that the square outer stitch line (FIG. 8) was used. Table 1 shows the test conditions and results.

[Comparative Example 4] The sewn portion on the occupant side of the suspension string was connected to the outer peripheral stitch line described in Example 1 of JP-A-2000-255357 (FIG. 9; a 90 mm straight portion and a diameter 127).
Example 1 except that a semicircular part of mm was joined).
Was performed in the same manner as described above. Table 1 shows the test conditions and results.

[0049]

[Table 1]

From the above results, the following has been found. In the first embodiment, the inflator output is 185 kP
a, 200 kPa, in each case, there was no bag breakage or opening, and it passed. Examples 2 and 3 are examples where a / b is relatively low.
It passes when the inflator output is 185 kPa. 20
At 0 kPa, although there was an aperture near the tip of the minor axis b and the stress dispersion was somewhat insufficient, it withstood without breaking the bag.

Example 4 was an example in which a / b was 5, and the width w of the hanging string was slightly narrow at 40 mm, but the result was almost the same as that of Example 1. In Examples 5 and 6, a / b is 5 and minor axis b is 4
0 mm or the case where the major axis a was 600 mm, and it passed and passed the case where the inflator output was 215 kPa.

In Comparative Example 1, the width of the hanging string (w = 120 mm)
When the major axis (a = 100 mm) was shorter than that, the inflator output could not withstand 185 kPa, and the bag was broken.
Comparative Example 2 is an example of a circular stitch line, in which the bag was broken from the center line in the longitudinal direction of the sewn portion (the circled portion in FIG. 10). Comparative Example 3 is an example of a square stitch line,
Bag breakage was observed from the stitch line angle of the sewn portion (FIG. 8).

Comparative Example 4 is an example in which a straight line located at a right angle to the longitudinal direction of the hanging string and a circular stitch line (FIG. 9) in which semicircles connecting these straight lines on both sides of the hanging string are connected, and the inflator output is 185 kPa. 200k
At Pa, the bag was broken. At this time, the bag was broken from the joint between the straight line and the semicircle.

[0054]

According to the airbag of the present invention, the suspension string is sewn to the occupant side of the airbag body with a specific specification.
Despite being lightweight and compact, it can sufficiently withstand the impact force when the airbag is deployed even in the case of high inflator output, and is a highly safe and reliable airbag.

[Brief description of the drawings]

FIG. 1 is a view showing an example of a circular cloth provided with an inflator mounting port which forms a part of a bag body of an airbag.

FIG. 2 is a view showing an example of another circular cloth sewn together with the circular cloth shown in FIG. 1;

FIG. 3 is a diagram illustrating an example of a reinforcing cloth around an inflator mounting opening of a bag body of an airbag.

FIG. 4 is a diagram illustrating an example of a case in which reinforcing cloths A and B are sewn and fixed around an inflator mounting opening of a circular cloth;

FIG. 5 is a diagram showing an example of a positional relationship between a thread axis of a reinforcing cloth and a bolt hole for fixing to a inflator.

FIG. 6 is a diagram illustrating an example of an airbag.

FIG. 7 is a view showing a specification in which a suspension string is sewn to the occupant side of the airbag body in the embodiment of the present invention.

FIG. 8 is a view showing a stitch line for sewing a suspension string to an occupant side of an airbag body in Comparative Example 3 of the present invention.

FIG. 9 is a view showing a stitch line for sewing a suspension string to an occupant side of an airbag body in Comparative Example 4 of the present invention.

FIG. 10 is a diagram showing a stitch line for sewing a suspension string to an occupant side of an airbag body in Comparative Example 2 of the present invention.

FIG. 11 is a view showing a specification of sewing a suspension string to an occupant side of an airbag body in a conventional airbag.

[Explanation of symbols]

 1: Circular cloth 2: Circular cloth A: Plain weave B: Plain weave a: Long diameter b: Short diameter w: Width of hanging strap

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Claims (4)

[Claims] 1. An airbag formed in a bag shape, wherein the airbag body is formed of a fabric having a basis weight of 180 g / m ² or less, and connects an occupant side and an opposite side to the inside of the airbag body. A suspending string is provided to regulate the length of the bag body when it is deployed, and the suspending string is sewn to the occupant side of the airbag body at a curved stitch line consisting of an ellipse, and the major axis of the oblong is An airbag, wherein the airbag is located at a right angle to the longitudinal direction of the suspending string, and the major axis has a length equal to or greater than the width of the suspending string. 2. The major axis a (mm) and the minor axis b (mm) of an ellipse
2. The airbag according to claim 1, wherein the width w (mm) of the hanging string satisfies the following expressions (1) to (4) at the same time. 1 <a / b <15 (1) 20 ≦ b ≦ 200 (2) 100 ≦ a ≦ 700 (3) 20 ≦ w ≦ 150 (4) 3. The airbag according to claim 1, wherein the ellipse is an ellipse having a major axis a and a minor axis b. 4. The sewing thread fineness T (dte) satisfying the following equations (5) and (6) when the suspension string is sewn to the airbag body.
The airbag according to any one of claims 1 to 3, wherein the airbag is sewn under the conditions of x) and the number of needles S (needle / cm). 200 ≦ T ≦ 1700 (5) 2 ≦ S ≦ 6 (6)