Airbag with reinforced tether fabric seams

Abstract

Provided is an airbag that restricts expansion thickness using a tether that links facing panels, wherein the panels have been made thinner and the airbag has been configured to be light and to have a small storage volume, while also suppressing rupturing in stitching sections between the panels and the tether at the time of airbag deployment. The present invention relates to an airbag having a bag body in which a pair of base fabric panels have been stitched together at the outer edges thereof, and a tether fabric of a prescribed width that has been stitched to the pair of base fabric panels inside the bag body so as to be able to restrict the distance between the pair of base fabric panels at the time of expansion of the bag body, said airbag being characterized in that the base fabric panels and the tether fabric are stitched together along with a reinforcing fabric that has been positioned on the outside of the bag body, and the reinforcing fabric is stitched to the base fabric panels outside of the seam allowance of the tether material, at a stitching strength that is lower than the stitching strength between the reinforcing fabric, the base fabric panels, and the tether fabric. This airbag is preferably a pedestrian airbag.

Description

[Technical Field]

[0001] The present invention relates to an airbag used in an airbag system installed in a vehicle. More specifically, the present invention relates to an airbag in which opposing base fabric panels are sewn together with a tether fabric to maintain a predetermined thickness when inflated, and in which the sewn portion of the tether fabric is reinforced. [Background technology]

[0002] An airbag system installed in a vehicle consists of an airbag module (device), sensors, and an operation control device. The airbag module consists of an airbag container, a gas generator inflator, and an airbag bag (cushion). Here, the airbag bag (cushion) is simply referred to as an airbag. Conventionally, when defining the thickness of an airbag upon completion of inflation, a tether connecting opposing panels is configured to determine the distance between the opposing panels. Patent Document 1 below discloses a pedestrian airbag in which the tether between opposing panels is relatively wide, and the tether supports the inflation and deployment structure of the airbag that broadly covers the car's hood cover (bonnet). However, Patent Document 1 does not describe in detail what kind of suture is used between the panel and the tether, much less the strength of the suture. Furthermore, in the airbag described in Patent Document 1, when the gas inflates, the thickness of the airbag is restricted by the tether, which may cause excessive force to act on the tether suture, potentially leading to rupture near the suture.

[0003] Patent Document 2 below proposes that, in order to reinforce the base fabric 31 near the seam, a reinforcing fabric 33 is placed on the outer side of the base fabric 31, and the reinforcing fabric 33 is sewn to the base fabric 31 with a seam 37 (single stitching), while one end of the connecting fabric 40 is sewn to both the reinforcing fabric 33 and the base fabric 31 with a seam 41 (joint stitching). However, while Patent Document 2 teaches that the stress generated in the joint when the airbag inflates is distributed between the reinforcing fabric and the base fabric, it does not describe the relationship between the seam strength of a single stitch and the seam strength of a joint stitch, which can lead to problems due to the stitching becoming too dense.

[0004] Patent Document 3 below proposes that in order to provide a pedestrian protection airbag in which the tether is less likely to break, when sewing the base fabric 30 and the tether 17B (17) together, the upper end of the tether is folded along the base fabric to form a lateral folded portion 26 and then sewn together. However, Patent Document 3 does not describe sewing a reinforcing fabric together with the tether to the base fabric, sewing the reinforcing fabric to the base fabric separately, or using an adhesive to fix the reinforcing fabric to the base fabric. Furthermore, it does not teach the method of adding a reinforcing fabric to the base fabric to bear the stress of the seam and strengthen the seam. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2019-172170 [Patent Document 2] Japanese Patent Publication No. 2011-148365 [Patent Document 3] Japanese Patent Publication No. 2019-34618 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] For example, pedestrian protection airbags are large airbags that cover the entire width of the vehicle and need to be rapidly deployed and inflated to protect the human body. If the gas is supplied from a single point, the load on the airbag's cushioning bladder during inflation becomes significant, and depending on the shape and design, the bladder may rupture. Furthermore, in order to further improve the energy efficiency of vehicles by making airbags lighter and to reduce storage volume by making the base fabric panel of the airbag thinner, conventional airbag configurations may rupture when inflated. Under these circumstances, the problem that the present invention aims to solve is to provide an airbag that is relatively large, such as a pedestrian protection airbag that covers the entire width of a vehicle, and whose inflation thickness is regulated by a tether connecting opposing panels, by thinning the panels, thereby creating a lightweight and compact airbag, while suppressing damage at the seam between the panel and the tether when the airbag deploys (i.e., reinforcing the seam). [Means for solving the problem]

[0007] In other words, the initial understanding is as follows: [1] An airbag comprising a bag body formed by sewing a pair of base fabric panels together at their outer edges, and a tether fabric of a predetermined width sewn to the pair of base fabric panels inside the bag body so as to restrict the distance between the pair of base fabric panels when the bag body is inflated, An airbag characterized in that the base fabric panel and the tether fabric are sewn together with a reinforcing fabric positioned on the outside of the bag, and the reinforcing fabric is sewn to the base fabric panel with a lower stitching strength than the stitching strength that sews the reinforcing fabric, the base fabric panel, and the tether fabric together. [2] The airbag according to [1], characterized in that the suture strength of the reinforcing fabric and the base fabric panel is lower than that of the reinforcing fabric, the base fabric panel and the tether fabric, and that the strength of the suture thread, the fineness of the suture thread, or the number of stitches in the suture is lower or a combination thereof. [3] The airbag according to [1] or [2], wherein both the reinforcing fabric and the base fabric panel are plain weave fabrics, and the reinforcing fabric is biased and fixed to the base fabric panel with respect to the warp and weft directions. [4] The airbag according to any one of [1] to [3] above, wherein the woven fineness of the reinforcing fabric {the value obtained by multiplying the fineness (dtex) by the weave density (threads / 2.54cm) and summing them in the warp and weft directions} is 1.1 times or more and 1.6 times or less the woven fineness of the base fabric panel. [5] The airbag according to any one of [1] to [4], wherein the base fabric panel and the tether fabric are sewn together with a reinforcing fabric fixed to the base fabric panel with adhesive on the outside of the bag body. [6] The airbag according to [5], wherein the adhesive is an adhesive resin, a hot melt resin, or a curable resin. [7] The airbag according to [6], wherein the adhesive is in the form of dots or stripes. [8] An airbag according to any one of [1] to [7], wherein there is no adhesive at the seam where the reinforcing fabric, the base fabric panel, and the tether fabric are sewn together. [9] The airbag according to any one of [1] to [8] above, wherein the woven fineness of the tether fabric {the value obtained by multiplying the fineness (dtex) by the weave density (threads / 2.54cm) and summing them in the warp and weft directions} is 1.1 times or more and 1.6 times or less the woven fineness of the base fabric panel.

[10] The airbag according to any one of [1] to [9], wherein the base fabric panel and the tether fabric are sewn together with a reinforcing fabric disposed on the outside of the bag body, as well as a tether reinforcing fabric disposed on the inside of the bag body on the outside of the seam allowance of the tether fabric.

[11] The airbag according to

[10] , wherein the seam allowance of the tether fabric and the tether reinforcement fabric are fixed together with an adhesive.

[12] An airbag according to any one of [1] to

[10] , wherein the seam allowance of the tether fabric is folded over and sewn.

[13] The airbag according to any one of [1] to

[12] , wherein the fineness of the yarn constituting the base fabric panel is 200 dtex or more and 400 dtex or less.

[14] The airbag is a pedestrian airbag, as described in any of [1] to

[13] above. [Effects of the Invention]

[0008] According to the airbag of the present invention, for example, in an airbag that is relatively large and covers the entire vehicle width, such as an airbag for pedestrians, and restricts the inflation thickness with a tether that connects opposing panels, the panel is made thinner, and while the airbag is lightweight and can be stored in a small volume, an airbag that suppresses breakage (reinforces the sewing) at the stitching portion between the panel and the tether can be provided.

Brief Description of the Drawings

[0009] [Figure 1] It is a cross-sectional view of Embodiment 1 of the present invention. [Figure 2] It is a cross-sectional view of Embodiment 2 of the present invention. Note that the checked pattern of reference numeral 3 indicates that it is biased. [Figure 3] It is a cross-sectional view of Embodiment 3 of the present invention. [Figure 4] It is a cross-sectional view of Embodiment 4 of the present invention. [Figure 5] It is a cross-sectional view of Embodiment 5 of the present invention. [Figure 6] It is a cross-sectional view of Embodiment 6 of the present invention. [Figure 7] It is a cross-sectional view of Embodiment 7 of the present invention. [Figure 8] It is a cross-sectional view of Embodiment 8 of the present invention. [Figure 9] It is an explanatory view showing an overview of the sample shape (before sewing) in Examples and Comparative Examples. [Figure 10] It is an explanatory view showing an overview of the sample shape (after sewing) in Examples and Comparative Examples. [Figure 11] It is an explanatory view showing an overview of the measurement method of sewing strength in Examples and Comparative Examples. [Figure 12] It is an explanatory view showing an overview of the sample shape (after sewing) in Comparative Example 4.

Modes for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described in detail. One embodiment of the present invention is an airbag having a bag in which a pair of base fabric panels are sewn together at the outer edge of an inflatable air chamber in the bag, and a tether fabric of a predetermined width sewn to the pair of base fabric panels inside the bag so as to regulate the distance between the pair of base fabric panels when the bag is inflated, wherein the base fabric panels and the tether fabric are sewn together with a reinforcing fabric disposed on the outside of the bag, and the reinforcing fabric is sewn to the base fabric panels on the outside of the seam allowance of the tether fabric with a sewing strength lower than the sewing strength between the reinforcing fabric, the base fabric panels and the tether fabric.

[0011] In the prior art, a reinforcing fabric for panel reinforcement is sewn onto the (base fabric) panel, and a tether is sewn together with the reinforced area (see Figure 2 of Patent Document 2). In contrast, in this embodiment, a reinforcing fabric for reinforcement is placed on the outside of the base fabric panel, and a tether (fabric) is sewn together with the reinforced area. Furthermore, the reinforcing fabric is sewn to the base fabric panel on the outside of the tether fabric's seam allowance with a seam strength lower than the seam strength between the reinforcing fabric, the base fabric panel, and the tether fabric (see Figure 1). By placing the reinforcing fabric for reinforcing the base fabric panel on the outside of the bag body and finishing it by sewing a tether together with the reinforced area, it becomes easier to fold and store, the sewn part is flexible and easy to fold, there is no obstruction to unfolding by a rough and stiff sewn part, and the reinforcement effect is sufficient.

[0012] For example, in the case of a pedestrian protection airbag, tension is applied to the base fabric panel and tether fabric by gas pressure during inflation and deployment. During the process of the airbag expanding from its folded state, rupturing the airbag case cover, and deploying to a state where it can protect pedestrians in an organized form, bag rupture may occur. The rupture site is the stitching where the tether fabric is attached, and in particular, when the fabric of the panel is made thinner to reduce weight, the tether fabric attachment point may become the starting point of rupture, potentially causing damage to the base fabric panel. In this embodiment, when sewing the tether fabric to the base fabric panel, the reinforcing fabric is placed on the outside of the base fabric panel and then sewn together. Therefore, even if the fabric of the base fabric panel is made thinner to reduce weight, the stress concentration at the seam is absorbed by the reinforced section consisting of the base fabric panel and the reinforcing fabric, thus preventing the airbag from bursting. As a whole, the airbag can be made lighter while avoiding gas rupture and maintaining the target pressure. Furthermore, if the reinforcing fabric is sewn to the base fabric panel on the outside of the seam allowance of the tether fabric with a lower stitching strength than the stitching strength of the reinforcing fabric, the base fabric panel, and the tether fabric together, then folding and storage is improved, folding workability is enhanced, there is no obstruction to deployment by the stitching, and the reinforcing effect is sufficient due to the integration of the base fabric panel and the reinforcing fabric. The reinforcing fabric should be placed on the opposite side of where the tether fabric is sewn to the base fabric panel. In other words, having the reinforcing fabric on the outermost part of the airbag allows it to better support the stress concentration at the seams caused by gas pressure.

[0013] As mentioned above, by pre-positioning reinforcing fabric on the base fabric panel and finishing by sewing tethers to the reinforced areas, the workability of the process of adding the reinforcing fabric is improved, it becomes easier to fold and store, there is no obstruction to unfolding by rough, stiff seams, and the reinforcing effect is sufficient. Pre-positioning reinforcing fabric on such a base fabric panel can be done with the minimum amount of stitching (see Figure 1). Alternatively, the reinforcing fabric may be temporarily fixed to the base fabric panel, then the outer edge of the reinforcing fabric may be sewn in place by a chain stitch or the like, and then a tether may be finished by sewing it together with the reinforcing area. This is because the sewing process can be stabilized if the reinforcing fabric is sewn to the panel mostly at its outer edge. Unlike the joint stitching that sews the reinforcing fabric and the tether fabric together, sewing the reinforcing fabric to the base fabric panel at the outer edge requires a lower sewing strength. This lower sewing strength at the outer edge, compared to the joint stitching between the reinforcing fabric, the base fabric panel, and the tether fabric, can be achieved by using a strong suture, a fine suture, or a combination of these methods. When sewing the reinforcing fabric to the base fabric panel, the strength of the suture thread used for the outer edge stitching of the reinforcing fabric should be lower than the strength of the suture thread used for the joint stitching between the reinforcing fabric, the base fabric panel, and the tether fabric, and may be as low as 10% of the strength, but more preferably in the range of 30% to 90%. The fineness of the suture thread used for the outer edge stitching of the reinforcing fabric should be lower than the fineness of the suture thread used for the joint stitching, and may be as low as 10% of the fineness, but more preferably in the range of 30% to 90%. The number of stitches used for the outer edge stitching of the reinforcing fabric should be lower than the number of stitches used for the joint stitching, and may be as low as 10% of the number of stitches, but more preferably in the range of 30% to 90%. Sewing the reinforcing fabric to the base fabric panel at the outer edge in this way allows for energy absorption by preventing the joint stitching from becoming the starting point of airbag failure when force is applied during deployment and inflation. Sewing the reinforcing fabric to the base fabric panel at roughly the outer edge makes the sewing process easier to stabilize. The stitching between the reinforcing fabric and the base fabric panel at the outer edge is performed with a weaker stitch than the stitching between the reinforcing fabric, the base fabric panel, and the tether fabric. This allows the former to break first, preventing the airbag from rupturing from the latter. This also prevents interference with folding and storage, and reduces the obstruction of deployment by rough stitching. When stitching the outer edge of the reinforcing fabric to the base fabric panel, it is preferable to avoid the tether's stitching allowance and position the stitching line outside the allowance.

[0014] When both the reinforcing fabric and the base fabric panel are plain weave fabrics, the reinforcing fabric can be positioned biased relative to the base fabric panel in the warp and weft directions (see Figure 2). Bias means that the warp threads of the reinforcing fabric and the warp or weft threads of the base fabric panel are not parallel, but are angled at approximately 45 degrees. By doing so, the forces applied to the seams when the airbag deploys and inflates are absorbed by the reinforcing fabric and the base fabric panel, thereby increasing the strength of the jointed seams.

[0015] The reinforcing fabric is intended to compensate for any deficiencies in the mechanical properties of the base fabric panel (woven fabric), and preferably compensates for the thickness of the base fabric (see Figure 3). The weave fineness (dtex / 2.54cm) of the reinforcing fabric is preferably 0.65 to 1.6 times, more preferably 0.9 to 1.6 times, and even more preferably 1.1 to 1.6 times, compared to the weave fineness of the base fabric panel. If the weave fineness (dtex / 2.54cm) of the reinforcing fabric is 1.6 times or less compared to the weave fineness of the base fabric panel, storage and weight reduction will not be compromised. Here, weave fineness is the value obtained by multiplying the fineness (dtex) by the weave density (threads / 2.54cm) in the woven fabric that makes up the base fabric panel and tether fabric, and adding the results in the warp and weft directions. A higher weave fineness results in a thicker fabric and a heavier weight per unit area. By making the weave density of the reinforcing fabric greater than that of the base fabric panel (by 1.1 times or more), it is possible to prevent the base fabric panel from breaking at the seams. When the base fabric panel is gas-inflated, the thickness of the airbag is restricted by the tether fabric, so a large force acts on the seams of the tether fabric. However, when the force acts on the base fabric panel through the sewing thread, the reinforcing fabric intervenes and can withstand that force.

[0016] In particular, when the base fabric panel is made thinner by reducing the fineness of the constituent yarns, the part that receives the force when the airbag inflates and deploys becomes mainly the reinforcing fabric rather than the base fabric panel, thus making it resistant to damage at the seams. From the viewpoint of mechanical properties and storability, the fineness of the constituent yarns of the thinned base fabric panel is preferably 200 dtex to 400 dtex, and more preferably 200 dtex to 300 dtex.

[0017] The tensile breaking strength (N / cm) of the reinforcing fabric is preferably 1.1 times or more than the tensile breaking strength of the panel, and more preferably 1.2 times or more. If it is 1.5 times or less, it is readily available as a woven fabric (not shown).

[0018] As illustrated in Figure 4, the base fabric panel and the tether fabric may be sewn together with a reinforcing fabric that is fixed to the base fabric panel with adhesive on the outside of the bag. There are no particular restrictions on the adhesive used to attach and fix the reinforcing fabric to the base fabric panel, but various adhesive resins and tack resins (adhesives) can be used. When assembling the airbag, applying adhesive resin or tack resin to the reinforcing fabric and bonding and fixing the panel and the reinforcing fabric together makes the assembly process easier. Using an adhesive resin makes bonding the base fabric panel and the reinforcing fabric simple, requiring only placing and pressing. Adhesive resins are those that exhibit adhesive properties at room temperature (around 20°C), and examples include acrylic adhesives, urethane adhesives, and silicone adhesives. The main raw material for acrylic adhesives is butyl acrylate, but ethyl acrylate and 2-hexyl acrylate are also included.

[0019] Adhesive resins include hot-melt resins, which are solid at room temperature (around 20°C) and have thermal melting properties, as well as curable resins that can be cured by heat or ultraviolet light. As hot-melt resins, thermoplastic resins with a melting point of 80 to 200°C can be used. Examples of hot-melt resins include polyamides, polyurethanes, polyesters, polypropylenes, polyethylenes, and modified ethylene vinyl acetate copolymers. Examples of heat-crosslinkable resins among curable resins include those obtained by adding an epoxy-based crosslinking agent to acrylic or polyurethane, and those containing N-methylolacrylamide are particularly preferred.

[0020] The adhesive (bonding resin) may be applied in a thin layer to the base fabric panel and / or reinforcing fabric, but it is preferable to apply it in a dot pattern (point pattern) or stripe pattern (not shown). For example, the diameter of the dots can be, for example, 100 μm or more and 1500 μm or less. The number of dots can be, for example, 9 dots / (25.4 × 25.4 mm 2 )) or more 2500(pcs / (25.4×25.4mm) 2 The following is possible: If the adhesive is arranged in a dot pattern, the bonded area is less likely to become rough and hard, and the foldability of the airbag will not be hindered. The bonding resin may also be provided in a line (linear) pattern. In particular, if the adhesive is placed away from the areas where the tether fabric, base fabric panel, and reinforcing fabric are sewn together, deterioration of workability due to needle contamination during the sewing process can be avoided (not shown). When the bonding resin is arranged in a dot pattern, the resin coating area is 3% to 90% of the area of ​​the reinforcing fabric, preferably 5% to 60%. The amount of resin in the bonding resin is 5 g / m². 2 ) or more 35 (g / m 2 ) or less, preferably 10 (g / m³) 2 ) or more 30(g / m 2 ) are as follows: Gravure coating or screen coating can be used as methods for applying the bonding resin to the base fabric panel and / or reinforcing fabric. The bonding resin can also be transferred using release paper. When reinforcing fabric is attached to the base fabric panel in a dot or stripe pattern, the folding process is improved. Furthermore, by using a thermoplastic material for attachment and fixing it to the panel at a relatively low temperature before sewing, the airbag sewing can be completed without damaging the physical properties of the panel. Moreover, by using an intermittent adhesive pattern such as dots for attachment, the folding of the integrated portion of the panel and reinforcing fabric remains flexible, without compromising foldability. If the attachment points avoid the sewing lines, the adhesive will not contaminate the sewing machine needle, and there will be no fluctuation in sewing machine needle resistance, resulting in a stable sewing process. Obstructions to folding and storage are avoided, and obstacles to deployment caused by rough, stiff seams are also reduced.

[0021] When bonding a base fabric panel and a reinforcing fabric, both the base fabric panel and the reinforcing fabric can be single-sided coated fabrics, but it is preferable to bond them with uncoated surfaces facing each other in order to ensure flexibility and adhesive strength at the bonding site (not shown).

[0022] As illustrated in Figure 5, the woven fiber density (dtex / 2.54cm) of the tether fabric is preferably greater than that of the base fabric panel, preferably 1.1 times or more, more preferably 1.2 times or more, and even more preferably 1.4 times or more. If it is 1.6 times or less, storage and weight reduction will not be compromised.

[0023] As illustrated in Figure 6, it is also preferable to sew a tether reinforcement fabric along with the tether fabric when sewing it to the panel. The woven fiber density (dtex / 2.54cm) of the tether reinforcement fabric is preferably higher than that of the base fabric panel. Furthermore, it is preferable to attach the tether reinforcement fabric so as to cover the seam allowance of the tether fabric from above. In this case, as illustrated in Figure 7, the space between the tether fabric and the tether reinforcement fabric can also be fixed with adhesive, similar to the space between the reinforcement fabric and the base fabric panel described above.

[0024] As shown in Figure 8, it is also preferable that the tether fabric be folded and sewn to the base fabric panel.

[0025] This embodiment is an airbag constructed using a tether to regulate the thickness of a base fabric panel, and an embodiment for a pedestrian airbag is particularly preferred. [Examples]

[0026] The present invention will be specifically described below with reference to examples and comparative examples. First, we will explain the materials used in the examples and comparative examples, the methods for measuring their physical properties, etc.

[0027] [Base fabric panel] A plain weave fabric woven using nylon 66 multifilament fibers as warp and weft and coated with a silicone resin was used. The total fineness of the base fabric used was 235 dtex, the number of filaments was 72, the weaving density was 72 threads / inch, the weaving fineness was 33,840 (dtex / 2.54 cm), and the silicone resin coating amount was 17 g / m 2 It was.

[0028] [Tether fabric] A plain weave fabric woven using nylon 66 multifilament fibers as warp and weft and coated with a silicone resin was used. The total fineness of the base fabric used was 470 dtex, the number of filaments was 136, the weaving density was 49 threads / inch, the weaving fineness was 46,060 (dtex / 2.54 cm), and the silicone resin coating amount was 25 g / m 2 It was.

[0029] [Reinforcement fabric] A plain weave fabric woven using nylon 66 multifilament fibers as warp and weft and coated with a silicone resin was used. The total fineness of the base fabric used was 235 dtex, the number of filaments was 72, the weaving density was 72 threads / inch, the weaving fineness was 33,840 (dtex / 2.54 cm), and the silicone resin coating amount was 17 g / m 2 It was.

[0030] [Sewing thread] Sewing thread 1: As a normal sewing thread, a sewing thread for airbags made by Gunze (total fineness 1880 dtex, 2 - ply twist of nylon 66 multifilament fibers 940 dtex) was used as the upper and lower threads. Sewing thread 2: As a sewing thread with a smaller fineness than sewing thread 1 (tear seam), a sewing thread for airbags made by Gunze (total fineness 940 dtex, 2 - ply twist of nylon 66 multifilament fibers 470 dtex) was used as the upper and lower threads. Sewing thread 3: As a sewing thread with a lower strength than sewing thread 2 (tear seam), a sewing thread for low - strength airbags (total fineness 940 dtex, 1 - ply twist of nylon 66 multifilament fibers 940 dtex) was used as the upper and lower threads. The strength of sewing thread 3 was 93.3% of the strength of sewing thread 2. Suture 4: As a suture with a finer fineness than suture 2 (teaream), Gunze's airbag sewing machine thread (total fineness 235 dtex, nylon 66 multifilament fiber 235 dtex single strand) was used for both the upper and lower threads. Suture 5: As a suture (teaream) with lower strength than suture 1, low-strength airbag sewing thread (total fineness 940 dtex, nylon 66 multifilament fiber 470 dtex 2-ply) was used for both the upper and lower threads. The strength of suture 5 was 93.3% of the strength of suture 1.

[0031] [sewing machine] A JUKI LU-2210W-7 sewing machine was used to sew the tether fabric and base fabric panels together.

[0032] [Preparation of test specimens] As shown in the <Sample Shape> in Figure 9, the tether base fabric and the base fabric panel were cut into strips along the grain of the base fabric to be 320 mm long x 500 mm long. The reinforcing fabric (also called a patch) was cut along the grain of the base fabric to be 300 mm long x 30 mm long. First, the reinforcing fabric was placed on top of the base fabric panel with the uncoated side facing each other, and bonded or sewn within the area of ​​the fixing point (4b). Then, as shown in the <Sample Shape (After Tether Sewing)> in Figure 9, the three layers in the order of tether fabric → panel base fabric → reinforcing fabric were sewn together. For the joint stitching, the tether fabric was stitched in a straight line using the aforementioned sewing machine with 50 stitches / 10cm, within a 270mm area in the center of the width direction, with a 15mm stitch allowance (4a: tether stitching). Three backstitches were made at the beginning and end of the stitching. Subsequently, as shown in Figure 10 <Sample Shape (After Sewing of Tether Overlap)>, in order to evaluate the mechanical characteristics of the stitched area, the ends of the base fabric panels in the length direction were overlapped so that the strip shape formed a loop, and the overlap was stitched in a straight line in the warp direction of the base fabric with 35 stitches / 10cm (7a: Sewing of Base Fabric Panel Overlap). The length of the loop was 320mm around. The tether fabric was folded back at the end furthest from the straight seam (4a), and the tether fabrics were sewn together at the midpoint between the straight seam (4a) and the folded section using three rows of straight stitches (7b: sewing the overlapping section of the tether fabric) in the warp direction of the base fabric at a stitch rate of 35 stitches / 10cm. The length from the folded section to the straight seam (4a) was set to 200mm. Finally, it was confirmed that the overlapping sections of the base fabric panels and the tether fabrics were not tilted, and that the straight seams (4a) and the sewing of the overlapping sections (7a, 7b) were aligned with the warp direction of the base fabric. It was also confirmed that these were not misaligned to prevent uneven stress on the sewing sections during measurement and thus avoid measurement errors.

[0033] (1) Measurement of sewing strength (N / cm) As shown in Figure 11, the <Jig Shape>, a jig that holds the test specimen by passing it through the loops of the base fabric panel and tether fabric was attached to the Tensilon universal material testing machine manufactured by A&D Co., Ltd. As shown in Figure 11, the <Sample Mounting State>, when the test specimen was mounted on the testing machine, it was adjusted so that the tether fabric was perpendicular to the base fabric panel (forming a T shape) when viewed from the side (the direction in which the thickness of the test specimen can be confirmed). At this time, the stroke was adjusted so that the tether fabric was stretched parallel to the tensile direction, and the stroke (distance from the straight stitch (4a: tether stitch) to the fixing point (folded part) of the lower part of the tether fabric to the jig) was 200 to 400 mm. Measurements were taken at a tensile speed of 300 mm / min, and the maximum strength at the time of fracture was determined as the sewing strength (N), and the value divided by the length of the straight stitch was calculated as the sewing strength (N / cm).

[0034] (2) Measurement of the thickness (mm) of the tether section when folded into quarters As described above, the test specimens were prepared, and the base fabric panel and tether fabric were cut to match the size of the protective cloth to create 300mm x 30mm sample pieces. The cut sample pieces were folded in half perpendicular to the straight stitch (4a), and then folded in half again perpendicular to the fold to create a four-fold sample. The folded portion of the sample was placed under a 150mm x 15mm plate, and a load was applied for 30 seconds so that the total load including the plate was 1kg. After that, the sample thickness at the four corners of the plate was measured with calipers, and the average of the measurements taken at the four locations was taken as the bending thickness of the stitched section. This value represents the bending thickness.

[0035] (3) Folding (folding) work time The folding time was recorded as the time taken from the preparation of the cut sample piece to folding the sample piece and placing the plate on top, as part of the process of measuring the thickness of the tether section when folded into four. The time required for three workers to perform this process for 10 sample pieces was measured. The average of the obtained results was expressed as the folding time, with Comparative Example 3 set as the baseline of 100.

[0036] [Examples 1-6, Comparative Examples 1-5] Test specimens were prepared with the reinforcing fabric and its fixing method / location shown in Table 1 below. Note that the fixing locations listed in Table 1 below indicate the sewing positions within the area of ​​fixing location (4b) in Figure 9 for each example or comparative example. Solid lines indicate the outer edge of the reinforcing fabric, and dashed lines indicate the sewing positions. In Example 1, when the reinforcing fabric was placed on the base fabric panel with a 100 mm offset in the weft direction and the uncoated sides facing each other, the base fabric panel and the reinforcing fabric were secured by sewing using the sewing thread 2 and the sewing machine at a rate of 30 stitches / 10 cm, so that the seam allowance was 10 mm along the outer edge of the reinforcing fabric. Then, the base fabric panel with the reinforcing fabric attached was placed on top of the tether fabric with a 100 mm offset in the weft direction, and the ends of the tether fabric and the ends of the reinforcing fabric were positioned to coincide, creating a three-layer structure in the order of tether fabric → base fabric panel → reinforcing fabric, and the two layers were sewn together using sewing thread 1. In Example 2, the sewing method for fixing the base fabric panel and the reinforcing fabric was the same as in Example 1, except that the sewing thread 3 was used. In Example 3, the sewing method for fixing the base fabric panel and the reinforcing fabric was the same as in Example 1, except that the sewing thread 4 was used. In Example 4, the sewing to fix the base fabric panel and the reinforcing fabric was performed using the sewing thread 1 at a rate of 20 stitches / 10 cm, except that it was the same as in Example 1. In Example 5, the sewing to fix the base fabric panel and the reinforcing fabric was performed using the sewing thread 1 at a rate of 5 stitches per 10 cm, except that it was the same as in Example 1. In Example 6, the sewing to fix the base fabric panel and the reinforcing fabric was performed using the sewing thread 5 at a rate of 50 stitches per 10 cm, except that it was the same as in Example 1. In Comparative Example 1, no reinforcing fabric was used, and two layers were used in the order of tether fabric → base fabric panel, and they were sewn together using sewing thread 1. In Comparative Example 2, instead of sewing along the outer edge of the reinforcing fabric, three layers were used in the order of tether fabric → base fabric panel → reinforcing fabric, and they were sewn together using sewing thread 1. In Comparative Example 3, the procedure was the same as in Example 1, except that when the reinforcing fabric was overlapped on the base fabric panel with the non-coated sides facing each other, offsetting it by 100 mm in the weft direction, the sewing to fix the base fabric panel and the reinforcing fabric was performed using sewing thread 1 and the aforementioned sewing machine at a stitch rate of 50 stitches / 10 cm. In Comparative Example 4, instead of overlapping the base fabric panel with the reinforcing fabric with the uncoated side facing it and fixing the base fabric panel and the reinforcing fabric together, the uncoated side of the reinforcing fabric was placed against the coated side of the base fabric panel and sewn together in the same places as shown in Example 1. Then, as shown in Figure 12, the process was the same as in Example 1, except that the tether fabric → reinforcing fabric → panel base fabric were layered in that order and sewn together. In Comparative Example 5, when the reinforcing fabric was overlapped on the base fabric panel with the non-coated sides facing each other, offsetting it 100 mm in the weft direction, the base fabric panel and the reinforcing fabric were secured by sewing using sewing thread 1 with the aforementioned sewing machine at a stitch rate of 50 stitches / 10 cm. Then, a joint stitch was performed with two rows of straight stitching (double lockstitch) at a stitch rate of 50 stitches / 10 cm. The spacing between the two rows of stitching was 3 mm, and the distance from the straight stitching on the side furthest from the edge of the tether fabric to the edge of the tether fabric (seam allowance for the tether fabric) was 15 mm.

[0037] The aforementioned sewing strength (N / cm), tether section four-fold thickness (mm), and reinforcing fabric utilization rate (N / cm) 2 The length of the device and the time required for folding were measured and evaluated. The results are shown in Table 1 below.

[0038] [Table 1] [Industrial applicability]

[0039] According to the present invention, in an airbag that is relatively large, such as a pedestrian airbag that covers the entire width of a vehicle, and whose inflation thickness is regulated by a tether connecting opposing panels, it is possible to provide an airbag that is lightweight and has a small storage volume by making the panels thinner, while suppressing damage at the seam between the panel and the tether when the airbag is deployed. Therefore, the airbag according to the present invention can be widely used in airbag systems for vehicles, including aircraft, ships, and automobiles. [Explanation of Symbols]

[0040] 1. Base fabric panel 2 Tether cloth 3. Reinforcement fabric 4. Adhesive (between the reinforcing fabric and the base fabric panel) 5. Suture (same stitch) 5' Suture (auxiliary stitching, between the reinforcing fabric and the base fabric panel) 6. Tether reinforcement fabric 7. Adhesive (between the tether reinforcement fabric and the base fabric panel) 4a Tethered stitching 4b Fixing points between the base fabric panel and the reinforcing fabric 7a Sewing of overlapping sections of base fabric panels 7b Sewing the overlapping section of the tether fabric 8 strokes

Claims

1. An airbag comprising a bag body in which a pair of base fabric panels are sewn together at their outer edges, and a tether fabric of a predetermined width sewn to the pair of base fabric panels inside the bag body so as to regulate the distance between the pair of base fabric panels when the bag body is inflated, The base fabric panel and the tether fabric are sewn together with a reinforcing fabric positioned on the outside of the bag, and the reinforcing fabric is sewn to the base fabric panel with a lower stitching strength than the stitching strength that sews the reinforcing fabric, the base fabric panel, and the tether fabric together. An airbag in which the woven fineness of the reinforcing fabric {the value obtained by multiplying the fineness (dtex) by the weaving density (threads / 2.54 cm) and summing them in the warp and weft directions} is 1.1 times or more and 1.6 times or less the woven fineness of the base fabric panel.

2. An airbag comprising a bag body in which a pair of base fabric panels are sewn together at their outer edges, and a tether fabric of a predetermined width sewn to the pair of base fabric panels inside the bag body so as to regulate the distance between the pair of base fabric panels when the bag body is inflated, The base fabric panel and the tether fabric are sewn together with a reinforcing fabric positioned on the outside of the bag, and the reinforcing fabric is sewn to the base fabric panel with a lower stitching strength than the stitching strength that sews the reinforcing fabric, the base fabric panel, and the tether fabric together. An airbag in which the woven fineness of the tether fabric {value obtained by multiplying the fineness (dtex) by the weave density (threads / 2.54 cm) and summing them in the warp and weft directions} is 1.1 times or more and 1.6 times or less the woven fineness of the base fabric panel.

3. The airbag according to claim 1 or 2, characterized in that the suture strength of the stitching between the reinforcing fabric and the base fabric panel is lower than that of the stitching between the reinforcing fabric, the base fabric panel and the tether fabric, and that any or more of the strength of the suture thread, the fineness of the suture thread, or the number of stitches in the stitching are lower.

4. The airbag according to claim 1 or 2, wherein both the reinforcing fabric and the base fabric panel are plain weave fabrics, and the reinforcing fabric is biased and fixed to the base fabric panel with respect to the warp and weft directions.

5. The airbag according to claim 1 or 2, wherein the base fabric panel and the tether fabric are sewn together with a reinforcing fabric fixed to the base fabric panel with adhesive on the outside of the bag body.

6. The airbag according to claim 5, wherein the adhesive is an adhesive resin, a hot melt resin, or a curable resin.

7. The airbag according to claim 6, wherein the adhesive is in the shape of dots or stripes.

8. The airbag according to claim 1 or 2, wherein there is no adhesive at the seam where the reinforcing fabric, the base fabric panel, and the tether fabric are sewn together.

9. The airbag according to claim 1, wherein the woven fineness of the tether fabric {the value obtained by multiplying the fineness (dtex) by the weave density (threads / 2.54 cm) and summing them in the warp and weft directions} is 1.1 times or more and 1.6 times or less the woven fineness of the base fabric panel.

10. The airbag according to claim 1 or 2, wherein the base fabric panel and the tether fabric are sewn together with a reinforcing fabric disposed on the outside of the bag body, as well as a tether reinforcing fabric disposed on the inside of the bag body on the outside of the seam allowance of the tether fabric.

11. The airbag according to claim 10, wherein the seam allowance of the tether fabric and the tether reinforcement fabric are fixed together with an adhesive.

12. The airbag according to claim 1 or 2, wherein the seam allowance of the tether fabric is folded over and sewn.

13. The airbag according to claim 1 or 2, wherein the fineness of the yarn constituting the base fabric panel is 200 dtex or more and 400 dtex or less.

14. The airbag according to claim 1 or 2, wherein the airbag is a pedestrian airbag.

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