How to create a folding model of an airbag

Abstract

This invention provides a method for creating a folding model of an airbag that can avoid penetration of the base fabric in computer simulations. [Solution] A model of the folded shape is created by setting the layer thickness of multiple base fabrics 21a, 21b that are overlapped in the region including the node S of the folded part of the airbag to be less than or equal to a predetermined value. This makes it possible to create an accurate folded model that corresponds to the actual airbag.

Description

Technical Field

[0001] The present invention relates to a method for creating a folding model of an airbag.

Background Art

[0002] Conventionally, an airbag mounted in a vehicle is stored inside a steering wheel or inside a dashboard in a folded state, and when the vehicle collides (for example, during a frontal collision), it is inflated by gas ejected from an inflater and deployed to protect the occupant.

[0003] And, for the purpose of storing this airbag compactly, etc., the folding method is designed using computer simulation (folding calculation is performed during the process of creating a model for computer simulation). For example, in Patent Document 1, based on the shape of the airbag, the folding form of the airbag is input using a keyboard and a mouse of a personal computer on an input screen, and the inflated airbag shape and the folded airbag shape are created as an airbag model of initial conditions by a three-dimensional shape creating device.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, as shown in Figure 3(a), an actual airbag a is constructed by overlapping multiple base fabrics b and sewing them together to form a bag, and is stored in a folded state with multiple nodes c (see the areas enclosed by dashed lines in the figure). In an actual airbag a, the overlapping of each base fabric b is maintained by wrinkles forming in the overlapping base fabrics b, but in computer simulations, since the circumference of the outer base fabric b and the circumference of the inner base fabric b theoretically match at the folded part, a large load is applied from the inner base fabric b to the outer base fabric b at this folded part, and in some cases a part of the inner base fabric b may pierce through the outer base fabric b.

[0006] As an example, Figure 3(b) shows a model of the folded portion (the part that is folded in half) of an airbag a (for example, an airbag that deploys when gas is supplied between base fabric b1 and base fabric b2) made by overlapping three base fabrics b1, b2, and b3. In this way, since base fabric b1 is located inside base fabrics b2 and b3 (inside the folded portion), there is an excess in the perimeter length, and in computer simulations, a part of the inner base fabric b1 (part of the excess perimeter length) appears to penetrate the outer base fabrics b2 and b3.

[0007] In the actual airbag a, such penetration of the base fabrics b1, b2, and b3 does not occur (as mentioned above, the difference in circumference is absorbed by wrinkles in the base fabric b1, so a large load is not applied). Therefore, in reality, it was not possible to create an accurate folding model for this folding part that corresponds to the actual airbag a.

[0008] The present invention has been made in view of the above, and its objective is to provide a method for creating a folding model of an airbag that can avoid penetration of the base fabric in computer simulations. [Means for solving the problem]

[0009] The present invention provides a solution for achieving the above objective, which is based on a method for creating a folded model of an airbag, in which multiple base fabrics are layered and sewn together to form a bag. This method for creating a folded model of an airbag is characterized by setting the layer thickness of the multiple base fabrics that are layered on top of each other in a region including at least the nodes of the folded portion of the airbag to be less than or equal to a predetermined value, and then creating a model of the folded shape using base fabrics of the set layer thickness.

[0010] This specific detail helps to prevent excess material from being added to the circumference of the inner base fabric at the folding point, thus avoiding the situation in computer simulations where a portion of the inner base fabric protrudes through the outer base fabric, and enabling the creation of an accurate folding model that corresponds to the actual airbag. [Effects of the Invention]

[0011] In this invention, a model of the folded shape is created by setting the layer thickness of multiple base fabrics that overlap each other in a region including at least the nodes of the folded portion of the airbag to be less than or equal to a predetermined value. Therefore, it is possible to create an accurate folded model that corresponds to the actual airbag. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1(a) is a perspective view of an airbag device according to an embodiment, showing the airbag in its retracted state, and Figure 1(b) shows the airbag in its deployed state. [Figure 2] Figure 2(a) is a model diagram of the overlapping portion of two base fabrics in an airbag, Figure 2(b) is an image diagram showing the overlapping portion of two base fabrics in a folding model according to an embodiment, and Figure 2(c) is an image diagram showing the overlapping portion of two base fabrics in a folding model according to the prior art. [Figure 3]The prior art is shown, with Figure 3(a) illustrating the folding portion of the airbag, and Figure 3(b) showing a model of the folding portion of the airbag made by layering three base fabrics. [Modes for carrying out the invention]

[0013] Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, the base fabric constituting the airbag, whose folding model is created by computer simulation, is one that has relatively low bending rigidity.

[0014] -Airbag system configuration- Figure 1 is a perspective view of the airbag device 1 according to this embodiment, where Figure 1(a) shows the retracted state of the airbag 2 and Figure 1(b) shows the deployed state of the airbag 2. The airbag device 1 includes an airbag 2 that deploys (inflates and deploys) when gas is supplied, and an inflator 3 for supplying gas to the inside of the airbag 2. When a vehicle collision occurs, the inflator 3 is activated, and the gas ejected from the inflator 3 is supplied to the inside of the airbag 2, causing the airbag 2 to deploy.

[0015] -Airbag configuration- Airbag 2 is manufactured by overlapping and sewing together multiple base fabrics 21 to form a bag. In the following description, when describing the base fabrics without identifying each one, the base fabric will be labeled 21, and when describing the base fabrics while identifying each one, the base fabric will be labeled 21a, 21b, etc.

[0016] FIG. 2(a) is a model diagram of the overlapping portion of the two base fabrics 21a and 21b in the airbag 2. In this FIG. 2(a), the upper base fabric 21a (e.g., the front side of the airbag 2) is shown by a solid line, and the lower base fabric 21b (e.g., the back side of the airbag 2) is shown by a dashed line. Each base fabric 21a and 21b is formed by cutting out a material such as nylon or polyester, and the airbag 2 is formed into a bag shape by sewing these base fabrics 21a and 21b together. Normally, it is folded and stored in an airbag case not shown.

[0017] And the airbag 2 protects the occupant by being supplied with gas ejected from the inflator 3 at the time of a vehicle collision (e.g., frontal collision) and deploying.

[0018] Incidentally, as the airbag 2, a configuration in which the fabric materials formed by overlapping these base fabrics 21a and 21b are sewn together in a bag shape (a configuration in which gas is supplied to the space between the fabric materials (the fabric material formed by overlapping the base fabrics 21a and 21b into one piece) when the inflator 3 operates and the airbag 2 is deployed) may be adopted, or a configuration in which these base fabrics 21a and 21b are sewn together in a bag shape (a configuration in which gas is supplied to the space between the base fabrics 21a and 21b when the inflator 3 operates and the airbag 2 is deployed) may be adopted. As the configuration of the airbag 2, the number of overlapping sheets of the base fabrics 21a and 21b is not limited to two, and may be three or more.

[0019] In this embodiment, when determining the folding shape of the airbag 2, the folding method is designed using computer simulation.

[0020] -Problems of the prior art- In the prior art, as described with reference to FIG. 3(b), in computer simulation, since the circumferences of the inner base fabric b1 and the outer base fabrics b2 and b3 theoretically match at the folding portion, a large load acts from the inner base fabric b1 toward the outer base fabrics b2 and b3 at this folding portion, and there is a case where a part of the inner base fabric b1 penetrates through the outer base fabrics b2 and b3.

[0021] In the actual airbag a, such penetration of the base fabrics b1, b2, and b3 does not occur (since the difference in circumference is absorbed by wrinkles in the base fabric b1 or the like, a state where a large load acts does not occur). Therefore, in this folding portion, the actual situation was that an accurate folding model corresponding to the actual airbag a could not be created.

[0022] The reason is that, as shown in FIG. 2(c) (this FIG. 2(c) is an image diagram showing the overlapping portion of two base fabrics 21a and 21b in the folding model according to the prior art, the solid lines in each of the base fabrics 21a and 21b indicate the centers in the thickness direction of each of the base fabrics 21a and 21b in computer simulation, and the virtual lines indicate the thicknesses of each of the base fabrics 21a and 21b in computer simulation), in the prior art, individual thickness dimensions were given (offset) to each of the base fabrics 21a and 21b, and they were processed in computer simulation as being overlapped with each other.

[0023] In what is shown in FIG. 2(c), a thickness dimension T is given to each of the upper base fabric 21a and the lower base fabric 21b, and the layer thickness of the two-layered base fabrics 21a and 21b is treated as "T×2". When folding at the node marked with the symbol S in the figure, due to the large layer thickness of the two-layered base fabrics 21a and 21b, the above-described penetration occurred due to the difference in circumference (see FIG. 3(b)). An example of this thickness dimension T is 0.3 mm. In this case, the layer thickness of the two-layered base fabrics 21a and 21b is treated as 0.6 mm. This dimension is not limited to this.

[0024] -Folding model- This embodiment takes this point into consideration and sets the layer thickness of multiple base fabrics 21a, 21b that are overlapped in at least the region including the nodes of the folded portion of the airbag 2 to be less than or equal to a predetermined value, and creates a model of the folded shape using base fabrics 21a, 21b with the set layer thickness.

[0025] Specifically, as shown in Figure 2(b) (Figure 2(b) is also an illustrative diagram showing the overlapping area of ​​the two base fabrics 21a and 21b in the folding model), instead of assigning individual thickness dimensions to each of the base fabrics 21a and 21b, the base fabrics 21a and 21b are overlapped (without offset), and a thickness dimension T is assigned to each of these overlapped base fabrics 21a and 21b, which is then processed in the computer simulation.

[0026] As a result, the layer thickness of the two layers of base fabric 21a and 21b is treated as T, and in computer simulations, the inner base fabric (e.g., base fabric 21b) will conform to the outer base fabric (e.g., base fabric 21a) at the folded portion (there will be no difference in the perimeter length of the two layers of base fabric 21a and 21b). This will prevent a large load from acting from the inner base fabric 21b toward the outer base fabric 21a at this folded portion, and will not cause a situation in which a part of the inner base fabric 21b penetrates the outer base fabric 21a.

[0027] In this case, the overall rigidity of the base fabrics 21a and 21b in the computer simulation will be treated as a rigidity equivalent to a thickness of "T × 2", while the overall thickness dimension of the base fabrics 21a and 21b will be treated as "T". This makes it possible to create a folding model that has the rigidity corresponding to the actual airbag 2, while preventing a situation where a part of the inner base fabric 21b penetrates the outer base fabric 21a.

[0028] -Effects of the embodiment- As described above, in this embodiment, the layer thickness of the multiple base fabrics 21a and 21b that overlap each other in the region including at least the nodal point S of the folded portion of the airbag 2 is set to be less than or equal to a predetermined value to create a model of the folded shape. Therefore, the layer thickness of the base fabrics 21a and 21b can be reduced (smaller than that of the conventional technology) without changing the bending rigidity of the base fabrics 21a and 21b, and an accurate folded model corresponding to the actual airbag 2 can be created.

[0029] -Other Embodiments- Furthermore, the present invention is not limited to the embodiments described above, and all modifications and applications are possible within the scope of the claims and equivalents thereof.

[0030] For example, in the embodiment described above, the base fabrics 21a and 21b were completely overlapped (overlapped without any misalignment). The present invention is not limited to this, and it is also within the scope of the technical idea to slightly offset the base fabrics 21a and 21b from each other, as long as it does not cause a situation in which a part of the inner base fabric 21b penetrates the outer base fabric 21a.

[0031] Furthermore, in the embodiment described above, the base fabrics 21a and 21b were overlapped (not offset) over their entire length. The present invention is not limited to this, and if the folding portions are known in advance, only the portions around the nodes S of those folding portions may be overlapped (not offset). In this case, specifically, since the airbag 2 is folded at multiple locations and stored in the airbag case, only the portions around the nodes S at each of these folding portions will be overlapped (not offset).

[0032] Furthermore, this invention can be applied not only to calculations for folding or bending a model that starts in a flat state, but also to creating a model from CAD data of a folded or bent shape. [Industrial applicability]

[0033] The present invention is applicable to a method for creating folding models that design the folding mechanism of airbags installed in vehicles using computer simulations. [Explanation of Symbols]

[0034] 2 airbags 21,21a,21b Base fabric S node T Thickness dimensions of the base fabric

Claims

[Claim 1] A method for creating a folding model of an airbag, which is made by overlapping and sewing together multiple base fabrics to form a bag, A method for creating a folding model of an airbag, characterized in that the layer thickness of the plurality of base fabrics that are overlapped in a region including at least the nodes of the folding portion of the airbag is set to be less than or equal to a predetermined value, and a model of the folding shape is created using base fabrics of the set layer thickness.

Images