JP4884002B2 - Airbag - Google Patents

Description

  The present invention relates to an airbag for protecting an occupant in the event of a vehicle collision, and more particularly to an airbag that is provided with a membrane member so that the inside air of the airbag can be exhausted when a predetermined internal pressure is reached.

Airbag systems have become widespread as safety devices for protecting passengers in vehicles, and there are an increasing number of mounting parts for driver seats, passenger seats, side impact protection, and rear seats, and the protection function for passengers is increasing. In order to improve the cushioning of the airbag deployed at the time of a collision as such an airbag and to prevent the airbag from being damaged when the impact of the occupant is eased, the airbag breaks and opens when the pressure in the airbag reaches a predetermined level. Thus, there has been proposed an airbag provided with a sealing member that enables exhaust (Patent Document 1).
Special table 2000-515090

However, since a rubber film such as silicone rubber is used as a conventional sealing member for forming such an exhaust opening, even if a pre-breaking portion is provided in advance, the internal pressure is reduced due to the rubber elasticity. As it rises, it swells like a shochu liquor and then breaks, so the break start point is not constant, and the break progress direction and break length are not constant from the break start point. When the rupture is started, the internal pressure is drastically lowered and the driving force for the progress of the rupture is reduced. For this reason, the breaking length may end short. The opening area is not constant depending on the state of the sealing member portion that remains uncut, and as a result, the exhaust characteristics vary. Such a tendency is also a concern in the case where a score is processed in advance in the planned fracture portion described in Patent Document 1.
The present invention does not require processing to form a weak portion in the film material that forms the planned opening portion, the way of breaking the film material is constant, and the planned opening portion is substantially fully opened by the breakage. Thus, an object of the present invention is to provide an airbag exhibiting stable exhaust characteristics.

  As a result of earnest study, the present inventor has found that when the planned opening portion is a quadrangle, stress concentration occurs at the diagonal portion of the pair of opposite corner portions when the airbag is deployed, and further, the diagonal line is defined as an airbag base fabric. By crossing the warp yarn and the weft yarn in the direction intersecting with the yarn axis direction, the diagonal portion breaks into a cross shape and the entire opening portion is turned over so that the opening can be stably performed. The present inventors have found that exhaust characteristics can be realized, and have further studied based on this knowledge to complete the present invention.

That is, the present invention
[1] A membrane member constituting an exhaust opening planned portion that breaks when an airbag reaches a predetermined internal pressure during the airbag deployment process is attached to a woven base fabric of a bag-like airbag In the airbag, the membrane member is not formed with a weak portion in advance, the planned opening portion has a polygonal shape, and the membrane member has an easily cut portion at a part of the circumference of the planned opening portion. The easily cut portion is a pair of opposing corner portions of the polygon and is broken at a diagonal portion connecting the opposing pair of corner portions along a direction intersecting the warp and weft yarn axis directions of the base fabric. An airbag, characterized in that
[2] The airbag according to [1], wherein the polygon is a quadrangle.
[3] The airbag according to claim 1 or 2, wherein the exhaust opening scheduled portion breaks into approximately a cross shape.
About.

  According to the present invention, the exhaust opening scheduled portion is broken as designed and the opening area is stabilized when the internal pressure of the airbag reaches a predetermined pressure with a simple configuration without forming the weak portion in advance. Therefore, the exhaust can be performed as designed, and the increase of the cushioning effect when the airbag is deployed and the possibility of damage to the airbag due to the impact with the occupant can be eliminated.

In the present invention, the configuration of the exhaust opening planned portion of the airbag is important, and the other portions are not particularly limited.
The air bag of the present invention is not particularly limited except for the positional relationship between the shape of the exhaust opening planned portion and the yarn axis of the base fabric, and a conventional film material such as silicone rubber is used. can do. As the polygon in the present invention, a quadrilateral is most preferable because a cruciform tension is applied to two pairs of corners intersecting each other and breaks quickly, but a polygon having opposing corners constituting a diagonal line is preferred. I need it.
FIG. 4A is an explanatory diagram for explaining the vicinity of a planned exhaust opening portion made of a conventional film material. The membrane material is composed of a thin opening planned portion and a surrounding thick portion. FIG. 4B is a cross-sectional explanatory diagram illustrating an example of the layer configuration of FIG. As shown in FIG. 4 (b), the membrane material is bonded and fixed to the front and back with a base cloth, leaving a portion of the planned opening and a part of the thick wall around it.

Example 1
FIG. 1 is an explanatory view of the vicinity of a planned opening portion of the present invention. In FIG. 1, the central portion shows a planned opening portion made of a square film material having a thickness of 0.25 mm and a side of 20 to 40 mm (in FIG. 1, the white portion in the center square), The periphery is made of a 0.7 mm thick membrane material, and the thick portion is left 20 mm wide (in FIG. 1, a square black portion). The outer peripheral portion of the 90 mm diameter membrane material is fixed on the front and back with a base fabric Yes. Moreover, the opposing corner | angular part used as an easy cut part is arrange | positioned so that the warp of this base fabric and the thread-axis direction (base fabric direction) of a weft may cross | intersect.
With this configuration, when the internal pressure of the airbag rises to a predetermined pressure (15 to 50 kPa), stress concentrates on the diagonal line portion (the portion indicated by the alternate long and short dash line in FIG. 1) of the planned opening portion shown in FIG. And since this diagonal part exists in the direction which cross | intersects a base cloth direction, it can fracture | rupture in a substantially cross shape in this diagonal part. Therefore, the fracture opening can be stably performed as the assumed opening planned portion.

Example 2
FIG. 2 shows that the whole film material in FIG. 1 is made into a square, and the entire outer peripheral part in addition to the planned opening part is also made into a square. With such a configuration, stress is easily applied to the diagonal line portion of the planned opening portion, and stress distribution to other portions is difficult to occur, so that the opening can be opened very quickly.
Comparative Example FIGS. 3a) to 3d) are explanatory diagrams when deployed using an airbag in which the shape of the exhaust opening planned portion is a circular shape. In this case, stress concentration occurs. Since there is no part to be cut, the direction in which the film is cut is not stable, the broken state is broken, the original circular shape is also distorted circular shape, and the opening area is not constant, indicating that the exhaust characteristics are not stable. .

Explanatory drawing of the Example of the opening opening part for exhaust_gas | exhaustion of this invention. Explanatory drawing of another Example same as the above. Explanatory drawing which shows that the fracture | rupture state is not stabilized when the opening part for exhaust is made circular shape. a is explanatory drawing of the conventional opening part for exhaust_gas | exhaustion, b is explanatory drawing of the layer structure.

Claims (3)

An airbag in which a membrane member that constitutes an exhaust opening planned portion that breaks when an airbag reaches a predetermined internal pressure during the airbag deployment process is attached to a woven base fabric of a bag-like airbag The membrane member is not formed with a weak portion in advance, the planned opening portion has a polygonal shape, the membrane member has an easily cut portion around a portion of the circumference of the planned opening portion, The easily cut portions are a pair of opposing corner portions of the polygon, and the break occurs at the diagonal portion connecting the opposing corner portions along the direction intersecting the warp axis direction of the warp and the weft of the base fabric. An airbag characterized by that. The airbag according to claim 1, wherein the polygon is a quadrangle. The airbag according to claim 1 or 2, wherein the exhaust opening scheduled portion is broken into approximately ten characters.

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