JP2005186873A - Filter for inflator of airbag device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily manufacture a filter built in an inflator for an airbag without impairing the performance. <P>SOLUTION: The filter for the inflator of the airbag device is constituted by forming a spirally bent intermediate work 14 formed of a wire 13 formed of stainless steel or the like, obtaining a cylindrical intermediate body 16 by winding the intermediate work 14 by several turns around a core 15, placing the cylindrical intermediate body 16 in a female mold 17 and pressing it in the axial direction, and entangling the overlapping intermediate works 14 in a non-separable manner to maintain the cylindrical shape. The filter 7 having adequate porosity is efficiently and easily manufactured, and the filter is easily adaptable to the difference in the kind (the difference in size or shape) by changing the winding manner of the intermediate work 14 or the diameter of the core 15. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a filter used for an inflator (gas generator) in an airbag device mounted on a vehicle such as a vehicle or an aircraft.

  An airbag device used for mitigating an impact on an occupant at the time of a collision of a vehicle or the like includes an inflator that is operated by the impact of the collision and ejects a gas, and a bag that is inflated by the gas. The inflator is configured such that a gas generating agent is disposed inside a sealed case, and the gas generating agent is burned (exploded) with an igniter to eject gas to the outside of the case.

  A filter for collecting harmful substances such as a fuel residue of the gas generating agent is disposed inside the case of the inflator. Many inflator filters (coolant filters) are cylindrical, and many structures have been proposed.

For example, Japanese Patent Laid-Open No. 7-285413 (Patent Document 1) discloses a wire formed in a cylindrical shape by a knitted mesh, and Japanese Patent Laid-Open No. 11-348712 (Patent Document 2) discloses a wire. What is formed by weaving is disclosed, and Japanese Patent Laid-Open No. 2001-315611 (Patent Document 3) discloses a structure obtained by laminating and sintering a wire mesh, and further, Japanese Patent Laid-Open No. 2001-171472. (Patent Document 4) discloses a flat yarn-like metal belt-like material that is rolled and sintered in a cylindrical shape while being laminated in a cylindrical shape.
JP-A-7-285413 JP 11-348712 A JP 2001-315611 A JP 2001-171472 A

  In an air bag device, the bag must be inflated instantaneously by the impact of a collision. Therefore, the inflator filter is required to have a function of collecting residues while ensuring gas permeability. Moreover, since a high pressure is applied by combustion of a gas generating agent, strength is also required.

  Conventional filters have also been developed to meet such demands. However, in the case of forming a cylindrical filter by knitting or weaving a wire as in Patent Document 1 and Patent Document 2, the porosity (bulk) Although there is an advantage that a filter with a uniform density) can be obtained, it is inferior in production efficiency and takes a lot of work to process, and it also has poor compatibility with differences in diameter and length (difference in type) There's a problem. In addition, although the processing costs of the configurations of Patent Document 3 and Patent Document 4 can be reduced as compared with Patent Documents 1 and 2, the problem of the processing cost still remains because a wire net or a special belt-shaped material must be prepared. It can be said.

  This invention makes it a subject to improve such a present condition.

  The inventors of the present application have paid attention to the point that the wire rods are tightly coupled when intertwined, and have completed the present invention.

  In other words, the inflator filter according to the first aspect of the present invention has a cylindrical shape or the like in which metal wires bent in a spiral or zigzag form are overlapped in layers, and the overlapping wire groups are pressed and entangled with each other. Is held. In addition, it is preferable that the raw material wire is bent in the tertiary direction like a spiral.

  In addition, the inflator filter according to the invention of claim 2 has a cylindrical shape. In this invention, a core material is prepared for manufacturing, and a metal wire bent in a spiral shape or a zigzag shape is used as the core material. A cylindrical intermediate body made of a wire with a high porosity is manufactured by winding the core material so as to be laminated in the axial direction and the radial direction, and then the intermediate body is pressed in the axial direction, the radial direction, or both directions. By reducing the density, the overlapping wires are entangled with each other so that they cannot be separated from each other, and a cylindrical shape is maintained.

  According to the present invention, the wires constituting the filter are bent and entangled with each other, so that the strength as a filter can be secured, and the degree of bending or pressurizing when the wire is bent in advance is formed into a predetermined shape. By controlling the pressure strength at the time, a filter with a porosity that has both gas permeability and residue trapping properties could be obtained.

  And in this invention, since it can manufacture only by pressing this after laminating in a multilayer form, such as winding a wire rod around a core material as a raw material, processing cost is lower than that using weaving or knitting or using a wire mesh. Can be reduced. Also, for example, in the case of a cylindrical shape, the outer shape can be freely controlled by changing the diameter of the core material, so that it is highly compatible with differences in size and shape.

  Next, an embodiment of the present invention will be described with reference to the drawings.

(1). First embodiment (FIGS. 1 to 3)
1 to 3 show the first embodiment. FIG. 1 is a cross-sectional view of an inflator 1 for an airbag device for a driver's seat. The inflator 1 is a metal plate made of a hollow circular main body case (housing) 2 and a cylindrical inner case disposed inside the main body case 2. 3 is provided. The inner case 3 is disposed concentrically with the main body case 2 and is welded to the main body case 2.

  In the inner case 3, an igniter 4 that is operated by an impact and a transfer charge 5 that is burned by the operation of the igniter 4 are disposed. The inner case 3 has a flame transfer hole 6 through which the flame of the charge transfer agent 5 is ejected.

  Further, a cylindrical filter 7 is disposed concentrically inside the inner case 3, and is surrounded by the filter 7 and the inner case 3, and a donut-shaped combustion chamber 8 is mainly composed of, for example, sodium azide. The gas generating agent 9 is filled. A support member 10 that contacts and positions the inner peripheral surface of the filter 7 is fixed to the inner top surface and the inner bottom surface of the inner case 3 by welding.

  In addition, an annular space 11 having a slight gap is formed between the inner peripheral surface of the inner case 3 and the outer peripheral surface of the filter 7, and a plurality of exhaust holes 12 are formed in the outer peripheral portion of the inner case 3. . When the igniter 5 is activated by a collision of a vehicle or the like, the explosive combustion of the transfer charge 5 causes the gas generating agent 9 to instantaneously burn and generate high-pressure gas. The gas passes through the filter 7 and passes through the exhaust hole 12 to the bag. The bag fills up (not shown) and the bag expands.

  The filter 7 is made of a metal wire such as stainless steel. By winding one or more wires as a material, the wire group is laminated in the thickness direction and the axial direction, and the overlapping wires are entangled. ing. For this reason, as schematically shown in FIG. 2, it has an appearance as if countless spiral forms are continuous.

  The manufacturing method of the filter 7 is shown in FIG. In this manufacturing method, by using a metal wire 12 such as stainless steel as shown in (A) as a material and winding it around a round bar, the intermediate material 13 bent in a spiral shape as shown in (B) and (C) is obtained. ((B) is a front view, (C) is a CC view of (B)), and then the intermediate material 14 is wound around the metal core material 15 several times to obtain a large number. A cylindrical intermediate body 16 in which the intermediate material 14 is overlapped in the longitudinal direction and the thickness direction (radial direction) is formed.

  The cylindrical intermediate body 16 is held in a cylindrical shape by the intermediate material 14 meshing with each other, but at this stage, the porosity is very high in a fluffy state. In the present embodiment, the cylindrical intermediate body 16 is formed by a plurality of intermediate materials 13, but the cylindrical intermediate body 16 may be formed by a single intermediate material 14. Alternatively, a plurality of intermediate materials 14 may be twisted and entangled together and wound around a core material 15 having a round bar shape or a cylindrical shape.

  Next, the cylindrical intermediate body 16 wound around the core material 15 is fitted into the female mold 17, and the cylindrical intermediate body 16 is pressed and bent in the axial direction so that the overlapping intermediate materials 14 are entangled with each other. . Thereby, the cylindrical filter 7 in which the overlapped intermediate materials 14 are held inseparable is obtained. In the present embodiment, the flange 15 a is provided integrally with the core material 15, and the cylindrical intermediate body 16 is pressed by fitting the core material 15 into the female mold 17, but the pressing member slides on the core material 15. It may be provided freely. It is also possible to pressurize the cylindrical intermediate body 16 by pressing the cylindrical intermediate body 16 in the radial direction using a split female or male mold.

  The filter 7 obtained in this way is excellent in strength because the intermediate material 14 is complicatedly overlapped in the radial direction and the axial direction and is entangled with each other. Further, since the wire is bent in a complicated manner, a uniform gap equivalent to the knitted filter 7 can be secured. Since the processing of the intermediate material 14, the processing of the cylindrical intermediate body 16, and the processing from the cylindrical intermediate body 16 to the filter 7 are also easy, the high-quality filter 7 can be easily and efficiently manufactured. .

  In addition, the difference in diameter can be easily dealt with by preparing the core material 15 and the female mold 17 with different diameters. It can be handled very easily by changing. Therefore, even if the type of the filter 7 is different, it can be easily handled. A core material for producing the cylindrical intermediate body 16 and a core material for pressurization may be used separately.

  Note that when the intermediate material 14 is wound around the core material 15, the intermediate material 14 which is overlapped in the radial direction may be wound so as to intersect each other, as schematically shown by a one-dot chain line in FIG. According to the above, it is expected that the entanglement between the intermediate materials 14 is promoted and is more excellent in strength. It is also possible to manufacture a pressurized intermediate body that is many times longer than a single filter 7 and cut it into a ring shape to form a single filter 7. Furthermore, it is also possible to integrate a wire by adding a sintering process according to a user's request.

(2). Second embodiment (FIGS. 4 to 5)
In the second embodiment shown in FIGS. 4 to 5, a spacer portion 7 a that hits the inner peripheral surface of the main body case 2 is formed at the outer peripheral end of the filter 7. If formed in this way, the filter 7 can be held without being displaced while securing the annular space 11 inside the main body case 2, so there is a possibility that the support member 16 need not be provided inside the main body case 2.

  And the spacer part 7a can be easily formed by using the female type | mold 17 which formed the step part 17a in the inner surface. In addition, it is preferable to wind the intermediate material 14 thickly around a portion corresponding to the spacer portion 7a at the stage of manufacturing the cylindrical intermediate body 16. The spacer portion 7 a can be provided at both ends of the filter 7.

(3). Third to fourth embodiments (FIGS. 6 to 7)
In 3rd Embodiment shown in FIG. 6, the filter 7 is formed in the bottomed cylinder shape (cross-sectional U-shape) provided with the top-plate part 7b, and in 4th Embodiment shown in FIG. It is formed in a dome shape. If formed in this manner, the permeation area of the combustion gas is widened, and it is considered that the gas permeability and the residual collecting ability can be improved. In the present invention, by winding the intermediate material 14 around the outer peripheral surface and the top surface of the core, the bottomed cylindrical or dome-shaped form and the filter 7 can be easily manufactured. This is one of the features of the present invention.

(4). Others The present invention can be embodied in various ways other than the above embodiment. For example, the form of the filter 7 can be set freely according to the structure of the inflator, such as a donut shape as described in JP-A-10-297418, or a disk shape.

  In the case of a flat type filter, it can also be produced by stacking a number of layers while folding the wire and pressing it in the thickness direction. Moreover, the material of a wire can use a copper wire or a plated steel wire. Furthermore, the wire may have a square cross section such as a triangle or a square.

  The inflator filter also plays a role of absorbing heat generated by the combustion of the gas generating agent. Therefore, a filter with high thermal conductivity is desirable, but strength must be ensured. In this regard, surface treatment with a material having high thermal conductivity such as copper plating, gold plating, or silver plating may be performed while securing strength by making the wire rod made of stainless steel or iron.

It is a figure which shows 1st Embodiment. It is a partially broken front view which shows the external appearance of a filter typically. It is a figure which shows the manufacturing process of a filter. It is a figure which shows 2nd Embodiment. It is a figure which shows a part of manufacturing process of the filter of 2nd Embodiment. It is a figure which shows 3rd Embodiment. It is a figure which shows 4th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inflator 2 Main body case 4 Igniter 7 Filter 9 Gas generating agent 13 Material wire 14 Intermediate material 15 Core 16 Cylindrical intermediate body 17 Female type

Claims (2)

Metal wires bent in a spiral or zigzag shape are stacked in layers, and the shape of a cylinder or the like is maintained by pressurizing the overlapping wire group and intertwining each other.
Inflator filter for airbag devices. A cylindrical intermediate body made of a wire with a high porosity by preparing a core material and winding a metal wire that is bent in a spiral or zigzag shape around the core material so as to be laminated in the axial direction and the radial direction of the core material Then, by pressing the intermediate body in the axial direction or radial direction or both directions to reduce the density, the overlapping wires are intertwined in an inseparable manner to maintain a cylindrical shape.
The inflator filter for an airbag apparatus according to claim 1.

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