JPH07285413A - Filter for inflator in air bag system - Google Patents

Abstract

PURPOSE:To improve the filtering effect for catching the fine particle such as the powder dust of the exploded propellant, eliminate the danger of the breakage of a filter which is applied with the gas pressure, and further facilitate the handling. CONSTITUTION:On the outer periphery of a protecting inner cylinder 1 having a number of small through holes on a cylinder wall, a ceramics sheet layer 2 which is formed by winding the ceramics sheet which is formed by skimming the ceramics fibers is formed, and a metal screen buffering body 3 is laminated on the outer periphery, and a protecting outer cylinder 4 having a number of small through holes is laminated on the outer periphery. The particularly preferable buffering body is a compressively shaped metal screen buffering body which is formed by compressing a cylindrical multiple folded metal screen which is formed by repetitively folding the end part in the lengthwise direction of the cylindrical metal screen in hosiery knitting in the lengthwise direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter used in an inflator (gas generator) of an air bag system for alleviating an impact on an occupant in the event of an automobile collision to improve the safety of the occupant.

[0002]

2. Description of the Related Art In a vehicle collision accident, a propellant (explosive) in an inflator is ignited to explode gas,
An air bag system that opens the bag by this gas, cushions the shock of the driver and other occupants and protects the occupant's safety has already been put into practical use, and its use is expanding.

Gas explosively generated from the propellant in the gas generating chamber of the inflator passes through the cylindrical filter from the inside to the outside after coming into contact with the cooling mesh, and is provided outside the filter along the cylindrical wall. The gas flows from the inflator into the bag through the plurality of gas passage holes to deploy the bag. The filter captures high temperature particles such as dust of explosive propellant contained in the gas so as not to flow into the bag. Since high heat resistance is required for this filter, conventionally, a metal mesh (usually stainless steel wire) plain-woven wire mesh is cut into strips of appropriate size, and this is wound in multiple layers in a cylinder. I am using.

[0004]

The above-mentioned conventional filter is composed of multiple layers of plain weave wire mesh in which the vertical strands and the horizontal strands intersect at a right angle while being straight, so that the void structure of the filter is simple. Therefore, the effect of the filter on the fine particles such as dust generated by the explosion of the propellant is not sufficient. In order to enhance the filter effect in the above conventional filter, it is necessary to reduce the wire diameter of the metal wire forming the wire mesh and to use multiple wire meshes in which the mesh is finely knitted, so that the filter is costly. In addition, there is a drawback that the pressure loss of gas permeation also increases.

Further, the above-mentioned conventional filter has a small shape retention strength, and it has a drawback that it spreads when receiving a gas pressure and easily enters the gas passage hole of the inflator and is damaged. If the filter is not effective enough, or if the filter is damaged, the hot dust of explosive propellant leaks into the bag and damages the bag, impairing the function of the bag or injuring passengers. There is a risk of Also, the conventional filter has a low shape retention strength and is easily deformed, which is inconvenient in handling.

The present invention eliminates the above-mentioned drawbacks of the conventional inflator filter for an air bag system, improves the filter action for capturing high temperature fine particles such as dust of explosive propellant, and reduces gas pressure. It is an object of the present invention to eliminate the risk of the filter being damaged when it is received, impairing the filter function, and to provide a filter that is easy to handle.

[0007]

In an inflator filter for an airbag system of the present invention that achieves the above object, a ceramic fiber is paper-shaped on the outer periphery of a cylindrical protective inner cylinder having a large number of through small holes in a cylindrical wall. A ceramic sheet layer obtained by winding a paper-made ceramic sheet into a cylinder is provided,
The wire mesh cushioning body is laminated in a cylindrical shape on the outer periphery thereof, and a cylindrical protective outer cylinder having a large number of through small holes on the cylinder wall is further laminated on the outer periphery thereof. As the above-mentioned wire mesh cushioning body, a cylindrical multi-fold wire mesh in which a longitudinal end of the knitted wire mesh is folded back onto the outer circumferential surface of the metal mesh is repeated a plurality of times. A cylindrical compression-molded wire mesh cushion formed by compression in the depth direction is particularly preferable.

[0008]

In the inflator filter of the airbag system of the present invention having the above-described structure, the gas explosively generated by the ignition of the propellant is transferred from the protective inner cylinder side to the protective outer cylinder (or compression molded wire mesh buffer) side. Pass through the cylinder wall. At this time, fine particles such as dust of the expelled propellant contained in the gas are captured by the filter action of the ceramic sheet wound in a cylindrical shape around the outer circumference of the protective inner cylinder.

The ceramic sheet is made of paper made by adding a small amount of a binder to a ceramic fiber such as alumina and has high heat resistance and appropriate air permeability,
It has a significantly higher ability to capture fine particles than a conventional wire mesh filter. Therefore, the high temperature particles such as dust of the propellant that explodes are captured by the ceramic sheet layer wound around the outer periphery of the protective inner cylinder, and the high temperature particles flow into the air bag to damage the air bag. There is no risk of injuring the driver or other passengers.

The ceramic sheet layer is strongly pressed to the outside when receiving the pressure of explosively generated gas. A wire mesh buffer is provided on the outer periphery of the ceramic sheet layer, and the wire mesh buffer is fine. Since the mesh contacts the ceramic sheet layer and supports it in a buffered manner, the ceramic sheet layer is not damaged by gas pressure.
Further, in the filter of the present invention, the protective inner cylinder and the protective outer cylinder having a large number of small through holes in the cylinder wall are integrally laminated inside the ceramic sheet layer and outside the wire mesh cushioning body. Therefore, the ceramic sheet layer and the wire mesh cushioning body can be well protected, the strength against deformation is large, and it is advantageous in handling.

In particular, when a compression-molded wire mesh buffer is laminated as a wire mesh buffer laminated on the outer periphery of the ceramic paper winding layer, the distribution of contact points (support points) in contact with the ceramic sheet layer is made finer. In addition, the cushioning action can be further improved. That is, the knitted wire mesh is
As shown in FIG. 7, the strand 31 of the metal wire is bent in zigzag, and the upper and lower stages are entangled with each other to form a loop P. Since the loop P has a shape that is easily elastically deformed,
Knitted wire mesh is superior in elasticity, stretchability and flexibility compared to plain weave wire mesh.

In the compression-molded wire mesh cushioning body according to the present invention, the end portion 33 in the longitudinal direction of the cylindrical knitted wire mesh is folded back onto the cylindrical outer circumferential surface 32 of the wire mesh many times as shown in FIG. (Normally 4 to 6 times) This is obtained by repeatedly forming a cylindrical multi-fold wire mesh and then compressing this in the length direction of the cylinder. This compression-molded wire mesh cushioning body is not only excellent as a cushioning body as described above, but also has a large shape retention strength because it is folded and compressed in multiple layers. Therefore, the compression-molded wire mesh cushioning body functions not only as a cushioning body but also as a protective cylinder, and when this compression molding wire mesh cushioning body is used as a wire mesh cushioning body, the external protection cylinder can be omitted.
Alternatively, instead of the internal protective cylinder, a compression-molded wire mesh cushioning body can be used as a buffering internal protective cylinder. Further, the compression-molded wire netting cushion having the above-mentioned structure functions as a filter because the void structure is complicated and fine, and when the ceramic sheet is damaged, it is possible to supplement the filter action of the ceramic sheet.

[0013]

EXAMPLES Details of the present invention will be described below based on examples. 1 is an explanatory view (perspective view) of the first embodiment of the present invention, and FIG. 2 is a sectional view taken along line II-II of FIG. 3 is an explanatory view (perspective view) of the second embodiment of the present invention, and FIG. 4 is a sectional view taken along line IV-IV of FIG. 5 is an explanatory view (perspective view) of the third embodiment of the present invention, and FIG. 6 is a sectional view taken along line VI-VI of FIG. The same reference numerals indicate the same parts.

The first embodiment shown in FIGS. 1 and 2 is a ceramic sheet in which one or more layers of a ceramic sheet are wound around the outer circumference of a cylindrical protective inner cylinder 1 having a large number of through small holes 11 in the cylinder wall. A layer 2 is provided, a wire mesh cushioning body 3 is laminated on the outer circumference thereof, and a protective outer cylinder 4 having a small through hole 41 on the cylinder wall is further laminated on the outer circumference thereof. The inner protective cylinder 1 and the outer protective cylinder 4 are, for example, stainless steel plates having a large number of through holes each having a hole diameter of 1.0 mm and arranged in a zigzag pattern at a hole interval of 2.0 mm. It is formed by welding.

The ceramic sheet layer 2 is a ceramic sheet made by adding a small amount of an organic binder to a ceramic fiber such as alumina to form a paper sheet, for example, a 0.06 inch (1.524 mm) thick FIBERFRAX paper (Toshiba Monoflux). It is formed by winding one layer of the product name of a corporation). The ceramic sheet layer needs to have appropriate air permeability, and it is desirable that the pressure loss measured by the gas removal filter performance test method defined in JIS B9901 be in the range of 3.5 to 6 mmAq (water column height). .

The wire mesh cushioning body 3 is a cylindrical wire mesh molded body having elasticity and flexibility capable of elastically supporting the ceramic sheet 2, and has a contact point (support point) in contact with the ceramic sheet layer 2. It is desirable that the stitches are fine so that they are finely distributed. For example, a strip-shaped plain weave wire mesh or a knitted wire mesh is multiply wound and laminated, or a cylindrical knitted wire mesh is folded as described above is used as a wire mesh buffer. However, the above-mentioned compression-molded wire mesh cushioning body obtained by further compressing the multi-folded wire mesh in the longitudinal direction of the cylinder is particularly preferable from the viewpoint of its cushioning property and the fineness of distribution of contact points in contact with the ceramic sheet layer. .

The compression-molded wire mesh cushioning body preferable as the cushioning body 3 in the present invention preferably has an outer diameter of 0.08 mm.
A metal wire such as a stainless steel wire having a range of 0.3 mm or a galvanized anticorrosion iron wire is used as an element wire, and the loop P shown in FIG.
Under the condition that the entanglement with each other, for example, a knitted wire mesh in a cylindrical shape with an inner diameter of 90 mm is formed into an appropriate length (usually 240 mm).
mm-280 mm) For example, cut into a length of 260 mm,
The end portion is folded back on the outer peripheral surface of the cylinder of the wire mesh by folding back the length L shown in FIG. 8 to, for example, 65 mm, and the wire mesh is folded, and the folding is repeated to make multiple folding (usually 4 to 6 layers). (Folding) A cylindrical multi-fold wire mesh is further put in a mold and compression-molded in the length direction thereof, for example, to a length of 20 mm.

In the second embodiment of the present invention shown in FIGS. 3 and 4, a ceramic sheet layer 2 formed by winding a ceramic sheet in a tubular shape is provided on the outer circumference of a protective inner cylinder 1, and the above-mentioned wire mesh buffer is provided on the outer circumference thereof. The cylindrical compression-molded wire mesh cushioning body 3'of FIG. In this embodiment, the protective outer cylinder is omitted because the compression-molded wire mesh cushioning body has high strength.

In the third embodiment of the present invention shown in FIGS. 5 and 6, the above-mentioned cylindrical compression-molded wire mesh cushioning body 3'is used as a protective inner cylinder, and a ceramic sheet is wound into a cylindrical shape on the outer periphery thereof. The ceramic sheet layer 2 is provided, and the above compression-molded wire mesh cushioning body 3'is further laminated on the outer periphery thereof. That is, the third embodiment is the protection inner cylinder 1 in the second embodiment.
Instead of the above, a compression-molded wire netting buffer 3'is used, and the ceramic sheet layer 2 is sandwiched between the inside and outside by the compression-molded wire netting buffer 3 '. Also in the above-mentioned first embodiment, the compression molded wire mesh cushioning body 3 ′ can be used instead of the inner cylinder 1.

[0020]

As described above, the inflator filter of the airbag system of the present invention having the above-described structure is provided with the ceramic sheet layer 2 in which a ceramic sheet made of paper-made ceramic fibers is wound into a tubular shape. When the gas explosively generated by the ignition of the propellant passes through the cylindrical filter of the present invention from the inside to the outside, high-temperature fine particles such as dust of the expelled propellant contained in the gas are It is effectively captured by the ceramic sheet layer. Therefore, there is no danger that high-temperature fine particles in the gas will flow into the air bag to damage the air bag or injure an occupant such as a driver.

The ceramic sheet layer has high heat resistance,
It is protected by a protective inner cylinder laminated inside it or a compression-molded wire mesh buffer, and is supported by a wire mesh buffer on the outside as a buffer, so when it receives the pressure of an explosively generated gas. Will not be damaged even in. In particular, when the ceramic sheet layer is buffer-supported by the compression-molded wire mesh cushioning body, the cushioning property is excellent, and the contact points (support points) in contact with the ceramic sheet layer can be finely distributed. Furthermore, even if the ceramic sheet layer is damaged for some reason, or even if it is damaged, the filter function can be supplemented by the excellent filter action of the compression molded wire mesh cushioning body. There are advantages. Furthermore, since the filter of the present invention is integrally laminated with the protective inner cylinder, the protective outer cylinder, and the compression-molded wire mesh cushioning body having high strength, there is no deformation and it is advantageous in handling.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is an explanatory diagram of a second embodiment of the present invention.

4 is a sectional view taken along line IV-IV of FIG.

FIG. 5 is an explanatory diagram of a third embodiment of the present invention.

6 is a sectional view taken along line VI-VI in FIG.

FIG. 7 is an explanatory diagram of a knitted wire mesh.

FIG. 8 is an explanatory view of folding back an end portion of a cylindrical wire mesh to an outer peripheral surface of the cylinder.

[Explanation of symbols]

 1 Protective Inner Cylinder 2 Ceramic Sheet Layer 3 Wire Mesh Cushion 3'Compression Molded Wire Mesh Cushion 4 Protective Cylinder

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shu Maeda 1-5-2 Fukaminishi Yamato-shi, Kanagawa Nihon Linets Co., Ltd. Within Sensor Technology Co., Ltd.

Claims (5)

[Claims] 1. A ceramic sheet layer in which a ceramic sheet made of paper-shaped ceramic fibers is wound in a cylindrical shape is provided on the outer circumference of a cylindrical protective inner cylinder having a large number of through small holes in the cylindrical wall, and the outer circumference thereof is provided. A filter for an inflator of an airbag system, wherein a wire mesh cushioning body is laminated in a cylindrical shape, and a cylindrical protective outer cylinder having a large number of through small holes in a cylindrical wall is further laminated on the outer periphery thereof. 2. A ceramic sheet layer in which a ceramic sheet made of paper-shaped ceramic fibers is wound into a cylindrical shape is provided on the outer circumference of a cylindrical protective inner cylinder having a large number of through small holes in the cylindrical wall, and the outer circumference thereof is provided. A cylindrical multi-folded wire mesh is formed by repeatedly folding a cylindrical knitted wire mesh whose end in the lengthwise direction is folded back onto the outer circumferential surface of the metal mesh a plurality of times and further compressed in the lengthwise direction. A filter for an inflator of an air bag system, which is obtained by stacking the above-mentioned tubular compression-molded wire mesh cushioning bodies. 3. A filter for an inflator of an air bag system according to claim 2, wherein a cylindrical protective outer cylinder having a large number of through small holes in the cylindrical wall is further laminated on the outer periphery of the compression molded wire mesh cushioning body. . 4. The inflator filter for an airbag system according to claim 2 or 3, wherein a tubular compression molded wire mesh cushion is laminated instead of the protective inner cylinder. filter. 5. The ceramic sheet layer has a thickness of 3.5 to 6 mm.
Pressure loss in the range of Aq (water column height) (however, JISB9
The filter for an inflator of an air bag system according to any one of claims 1 to 4, further comprising a gas removal filter performance test method (901).