Filter and gas generator

Abstract

To prevent a metal wire from being frayed or to prevent the fray of the metal wire from spreading to another part of the metal wire by limiting the fray of the metal wire to a very small part even when the metal wire is disconnected.SOLUTION: A filter 201 includes: a winding body 210A around which a metallic wire 220 is spirally wound in multiple layers; and at least one protective member 231 covering a part of an outer peripheral surface of the winding body to prevent the metallic wire from fraying. The winding body has, in an outer peripheral part including the outermost layer Ln thereof, has a low-number-of-winds portion 211 where the number of winds of the metal wire is smaller than that of an inner peripheral part 213. The protective member is formed of a member different from the metal wire. The protective member is attached to an intermediate part of the winding body in the axial direction thereof and surrounds the winding body at least once. At least a part (contact portion 221) of a first metal wire portion 220(n) constituting the outermost layer of the winding body is in contact with the protective member.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a filter and a gas generator. [Background technology]

[0002] Vehicles such as automobiles are equipped with airbag devices that protect occupants from impacts that occur during a vehicle collision. A gas generator, which instantly inflates and deploys an airbag during a vehicle collision, burns a gas generating agent to instantly generate a large amount of gas, thereby inflating and deploying the airbag. The gas generator has a built-in metal filter to control and cool the emission of high-temperature gas generated by the combustion of the gas generating agent.

[0003] As an example of such a metal filter, Patent Document 1 describes a wire-wound filter in which at least one metal wire is wound in a spiral and in multiple layers. This filter is cylindrical and has fray prevention sections at both axial ends, where the winding pitch of the metal wire is narrowed to increase the winding density of the metal wire. This suppresses fraying near both axial ends and improves the shape retention of the filter. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-319781 A Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, the fray prevention portion is made of metal wire that constitutes the filter. Therefore, if the metal wire breaks in the fray prevention portion or its vicinity, the fray prevention portion will fray and will no longer be able to perform its function. As a result, there is a risk that the filter portion located on the inner diameter side of the fray prevention portion will fray.

[0006] The present invention has been made in consideration of the above circumstances, and aims to prevent the metal wire from fraying even in the unlikely event that the metal wire breaks, or to limit the fraying of the metal wire to a very small portion so that it does not spread to other portions of the metal wire. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides a filter comprising a winding body in which metal wire is wound in a spiral and in multiple layers, and at least one protective member that covers a portion of the outer circumferential surface of the winding body to prevent fraying of the metal wire, wherein the winding body has a low-turn portion in an outer circumferential portion including the outermost layer of the winding body, in which the number of turns of the metal wire is fewer than in an inner circumferential portion, and the protective member is made of a member separate from the metal wire and is attached to the winding body at an appropriate position, and at least a portion of a first metal wire portion constituting the outermost layer of the winding body is in contact with the protective member. [Effects of the Invention]

[0008] According to the present invention, even if the metal wire is broken, the metal wire can be prevented from fraying, or the fraying of the metal wire can be limited to a small part of the metal wire and prevented from spreading to other parts of the metal wire. [Brief explanation of the drawings]

[0009] [Figure 1] 1A and 1B are diagrams illustrating a filter according to a first embodiment of the present invention, in which FIG. 1A is a schematic perspective view of the filter, and FIG. 1B is a schematic perspective view of a winding body that constitutes the filter. [Figure 2] 5A to 5C are schematic diagrams illustrating a method for manufacturing a winding body. [Figure 3] 1 is a schematic diagram of a disk-type gas generator incorporating a filter according to an embodiment of the present invention; [Figure 4] 10(a) and 10(b) are plan views illustrating an example of a method for attaching a protective member that is wound around the circumferential direction. [Figure 5]5(a) and 5(b) are schematic front views illustrating the attachment position of the protection member. [Figure 6] FIG. 10 is a schematic front view illustrating the number of turns of a metal wire belonging to a low-turn portion. [Figure 7] 10(a) and 10(b) are schematic front views showing a modified example of the first embodiment. [Figure 8] FIG. 4 is a schematic front view showing a filter according to a second embodiment of the present invention. [Figure 9] 5(a) and 5(b) are schematic front views illustrating the attachment position of the protection member. [Figure 10] 10(a) and 10(b) are schematic front views showing a modified example of the second embodiment. [Figure 11] 10(a) and 10(b) are photographs showing test specimens used to calculate the relationship between the pressure loss and the outer periphery coverage rate of the winding body by the protective member. [Figure 12] 10(a) and 10(b) are diagrams showing the relationship between the coverage rate of the outer periphery of the winding body by the protective member and pressure loss. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will be described in detail below using the embodiments shown in the drawings. However, unless otherwise specified, the components, types, combinations, shapes, relative positions, etc. described in these embodiments are merely illustrative examples and do not intend to limit the scope of the present invention. Furthermore, the embodiments can be implemented in appropriate combinations as long as they are not inconsistent.

[0011] [Outline of filter configuration] FIG. 1 is a diagram illustrating a filter according to a first embodiment of the present invention, where (a) is a schematic perspective view of the filter, and (b) is a schematic perspective view of a winding body that constitutes the filter.

[0012] A hollow cylindrical filter (hereinafter referred to as the filter) 201A (201, 200) according to an embodiment of the present invention includes a hollow cylindrical winding body 210A (210) in which one or more continuous metal wires 220 are wound in a spiral, multi-layered manner so that adjacent metal wire portions in the inner and outer diameter directions extend in directions that intersect with each other, and at least one protective member 231 (230) that covers a portion of the outer surface of the winding body to prevent fraying of the metal wires. First, the general configuration of the winding body and a manufacturing method thereof, as well as a gas generator, which is an example of a device into which the filter is incorporated, will be described.

[0013] The winding body 210 according to one embodiment of the present invention is formed by winding at least one continuous metal wire 220 in a spiral shape with a constant pitch and in multiple layers, with a constant inclination angle relative to the axial direction (the vertical direction in the drawing). Here, the individual layers in which the metal wire 220 is wound in the same direction are referred to as wire layers L1, L2, L3, etc. The metal wires constituting each of the wire layers L1, L2, L3, etc. extend in the same direction inclined relative to the axial direction (the central axis Ax1) of the hollow cylindrical winding body in a front view, and the metal wires constituting each adjacent wire layer in the inner and outer radial directions extend in directions that intersect with each other (are not parallel to each other).

[0014] In Figure 1, the extension direction (longitudinal direction of metal wire portion 220(n-2)) of metal wire portion 220(n-2) (thickness not shown) constituting wire layer Ln-2 is the direction indicated by the solid arrow, and the extension direction (longitudinal direction of metal wire portion 220(n-3)) of metal wire portion 220(n-3) constituting wire layer Ln-3 immediately inside it is the direction indicated by the dashed arrow. That is, the winding body 210 has one wire layer (for example, wire layer L1) formed by spirally winding the metal wire 220 at a certain inclination angle with respect to the axial direction, and another wire layer (for example, wire layer L2) formed by spirally winding a metal wire at an inclination angle different from that of the metal wire constituting the one wire layer L1, superimposed on the outer circumferential side of the one wire layer L1. The metal wires constituting the one wire layer L1 and the adjacent other wire layer L2 are configured to be non-parallel to the axial direction and to intersect with each other. The inclination angle of the metal wires constituting the wire layer with respect to the axial direction may be varied within one wire layer. Also, like the wire layers Ln and Ln-1, the inclination angles of the metal wires 220(n) and 220(n-1) relative to the axial direction may be configured to vary within one winding body 210.

[0015] The filter 200 including this winding body 210 is used to remove unwanted substances from various fluids, such as liquids and gases, and, depending on the application, to simultaneously cool the fluid passing through the filter. This filter is configured to form a flow path through which the fluid passes in the direction in which the wire layers overlap, i.e., in the radial direction of the filter. The fluid may pass from the inner diameter side to the outer diameter side of the filter, or from the outer diameter side to the inner diameter side. Here, the radial direction does not mean the diametric direction (radial direction) in the strict sense, but rather roughly in the radial direction as opposed to the axial or circumferential directions. The size of the filter (inner diameter, outer diameter, axial dimensions, etc.) is determined appropriately depending on the structure and size of the device in which the filter is to be incorporated. The types of metals that can be used to make the winding include iron, mild steel, stainless steel, nickel alloys, copper alloys, etc., and among these, austenitic stainless steel (SUS304) is preferred.

[0016] Furthermore, the thickness and cross-sectional shape (cross-sectional shape in a direction perpendicular to the longitudinal direction of the metal wire) of the metal wire used for the winding are determined appropriately depending on the size of the filter, the substances removed by the filter, pressure loss, etc. For example, the cross-sectional area of ​​the metal wire used for the gas generator filter is about 0.03 to 0.8 mm^2 (the wire diameter is about 0.2 to 1 mm when a round wire with a perfectly circular cross-sectional shape is used as the standard). The winding body uses a metal wire material obtained by rolling a metal wire having a perfectly circular cross section into a predetermined shape. The metal wire material may be a rectangular wire rolled to have a flattened rectangular cross section, or a deformed wire rolled to have a roughly V-shaped cross section. In the winding body 210, the metal wire material 220 is wound so as not to be twisted.

[0017] [Manufacturing method of winding body] FIG. 2 is a schematic diagram illustrating a method for manufacturing the winding body. To produce the winding body 210, first, one end (starting end, winding start) of the metal wire 220 is fastened at an appropriate position on the mandrel 131 constituting the winding device 130. With a predetermined tension applied to the metal wire 220, the mandrel 131 is rotated at a predetermined speed in a fixed direction about the central axis Ax2, and a guide member 132 that supplies the metal wire 220 is moved back and forth at a predetermined speed along the central axis Ax2 of the mandrel 131. By this operation, the metal wire 220 is wound spirally and in multiple layers around the outer periphery of the mandrel 131. Furthermore, the metal wires constituting adjacent wire layers cross each other to form a mesh.

[0018] For example, in the first metal wire layer wound directly around the outer periphery of the mandrel 131, if each metal wire 220 is inclined clockwise by a predetermined angle θ with respect to the axial direction of the mandrel 131, the metal wire 220 constituting the second metal wire layer wound around the outer periphery of the first metal wire layer will be inclined counterclockwise by a predetermined angle θ with respect to the axial direction of the mandrel 131. The starting end of the metal wire 220, held at one axial end of the mandrel 131 (right side in the figure), is folded back toward the other axial end of the mandrel 131 (left side in the figure) when the metal wire 220 has been wound around the mandrel 131 in two or more layers. The metal wire 220 is further wound around the folded back starting end, thereby sandwiching and fixing the starting end between the adjacent wire layers. After that, the metal wire 220 is wound a predetermined number of times (a predetermined number of layers), and then the other end (terminal end, winding end side) of the metal wire 220 is joined and fixed to an appropriate position of the wound metal wire 220 by resistance spot welding. The welding machine 150 that resistance spot welds the metal wire 220 includes an electrode 151 that applies a current required for joining. The electrode 151 is configured to be movable forward and backward relative to the mandrel 131, and can press the metal wire 220 with a predetermined pressure and can also pass a current for joining while pressed. After joining the ends of the metal wire 220, the metal wire 220 is cut by an appropriate method and removed from the mandrel 131, thereby obtaining a hollow cylindrical body.

[0019] The angle (winding angle) of the metal wire 220 relative to the axial direction of the mandrel 131 and the spacing (pitch) between adjacent metal wires 220 in the axial direction can be changed by appropriately adjusting the ratio between the rotation speed of the mandrel 131 and the movement speed of the guide member 132. By appropriately changing the thickness, winding angle, pitch, and number of windings of the metal wire, the pressure loss of the fluid passing through the filter (winding body) can be controlled to an appropriate value. The mandrel 131 is generally columnar or cylindrical, and is generally made of metal such as stainless steel, copper alloy, aluminum alloy, etc. The inner diameter of the winding body 210 corresponds to the outer diameter of the mandrel 131, and the outer diameter of the winding body 210 is adjusted appropriately depending on the size (thickness) of the metal wire 220 and the number of windings.

[0020] The winding body 210 manufactured by the above method has a protective member 230 attached to its outer circumferential surface to complete the filter 200. The filter is not entirely sintered.

[0021] [Gas generator incorporating a filter] FIG. 3 is a schematic diagram of a disk-type gas generator incorporating a filter according to one embodiment of the present invention. Disk-type gas generator 1 includes a substantially cylindrical housing whose both axial end faces (top and bottom ends in the figure) are closed. An accommodating space formed inside the housing accommodates internal components such as retaining section 30, igniter 40, cup-shaped member 50, transfer charge 59, gas generating agent 61, lower support member 70, upper support member 80, cushion material 85, and filter 200. Also, a combustion chamber 60 is located in the accommodating space provided inside the housing, and this combustion chamber 60 mainly accommodates gas generating agent 61, one of the above-mentioned internal components.

[0022] The housing includes a lower shell 10 having a generally cylindrical shape with a bottom and an open upper end face (having an upper opening), and an upper shell 20 having a generally cylindrical shape with a bottom and an open lower end face (having a lower opening). The lower shell 10 and the upper shell 20 are formed by pressing metal plates made of stainless steel, iron steel, aluminum alloy, stainless alloy, or the like. With the top opening and bottom opening facing each other, the top end of the lower shell 10 is press-fitted into the bottom end of the upper shell 20, and the abutting portion of the two or the vicinity thereof is joined by electron beam welding, laser welding, friction welding, or the like, thereby integrating the two. Upper shell 20 is provided with a flange portion 25 that protrudes radially outward from the lower edge thereof. Flange portion 25 is a portion for fixing disc-shaped gas generator 1 to an external member (for example, a retainer provided in an airbag device).

[0023] A protruding cylindrical portion 13 protrudes from the center of the bottom plate portion 11 of the lower shell 10 toward the top plate portion 21 of the upper shell 20. This forms a recessed portion 14 on the exterior side of the housing, i.e., on the opposite side of the protruding cylindrical portion 13. An opening 15 that connects the inside and outside of the housing is formed in the end face of the protruding cylindrical portion 13 on the top plate portion 21 side. A holding portion 30 for fixing the igniter 40 is provided on the protruding cylindrical portion 13 side and the recessed portion 14 side through the opening 15. The holding portion 30 is made of insulating resin and is formed by insert molding.

[0024] Igniter 40 is a means for generating a flame and includes ignition unit 41, which includes an ignition charge and a resistor that ignites the ignition charge, and a pair of terminal pins 42 that supply power to the resistor. The resistor generates Joule heat to ignite the ignition charge. Recess 14 is a portion that provides space for providing female connector 34, which is electrically connected to terminal pin 42, in holding unit 30.

[0025] A cup-shaped member 50 is attached to the bottom plate portion 11 so as to cover the protruding tube portion 13, the holding portion 30, and the igniter 40. A transfer charge 59 is accommodated in the hollow portion of the cup-shaped member 50. When the igniter 40 is activated and the transfer charge 59 is ignited, the cup-shaped member 50 bursts, deforms, or melts due to an increase in pressure in the internal space and conduction of the generated heat. Of the internal space of the housing, the space surrounding the portion where the cup-shaped member 50 is disposed is a combustion chamber 60 in which a gas generating agent 61 is accommodated. The gas generating agent 61 is disposed adjacent to the outer surface of the cup-shaped member 50. A filter 200 according to an embodiment of the present invention is arranged along the inner periphery of the housing in a space that radially surrounds the combustion chamber 60 that accommodates the gas generating agent 61. The filter 200 has a cylindrical shape and is arranged so that its central axis Ax1 substantially coincides with the axial direction of the housing.

[0026] The filter 200 functions as a cooling means for cooling the gas generated in the combustion chamber 60 by removing the high temperature heat of the gas as the gas passes through the filter 200, and also functions as a removal means for removing residue (slag) and the like contained in the gas. The filter 200 is disposed at a distance from the peripheral wall portions 12, 22 of the lower shell 10 and the upper shell 20, which constitute the peripheral wall portions of the housing, so that a gap 28 of a predetermined size is formed between the peripheral wall portions 12, 22. A plurality of gas outlets 23 are provided in the peripheral wall 22 of the upper shell 20 in a portion facing the filter 200. These gas outlets 23 are for directing gas that has passed through the filter 200 to the outside of the housing. Sealing tape 24 is attached to the gas outlets 23. The sealing tape 24 ensures that the combustion chamber 60 is airtight.

[0027] An annular lower support member 70 is disposed on the bottom plate 11 side of the combustion chamber 60, which secures the filter 200 to the housing and prevents the generated gas from leaking out from the gap between the bottom plate 11 and the lower axial end of the filter 200. Furthermore, a disk-shaped upper support member 80 is disposed on the top plate 21 side of the combustion chamber 60, which secures the filter 200 to the housing and prevents the generated gas from leaking out from the gap between the top plate 21 and the upper axial end of the filter 200. The lower support member 70 and the upper support member 80 are formed by pressing steel plates such as ordinary steel or special steel. A disk-shaped cushion material 85 is disposed between the upper support member 80 and the gas generating agent 61 to press the gas generating agent 61 toward the bottom plate portion 11. The cushion material 85 is made of rock wool, foamed resin, or the like, and prevents the gas generating agent 61 from being crushed due to vibration, etc.

[0028] The gas generator 1 operates as follows. First, when the vehicle collides, the igniter 40 is activated by current from the control unit. The activation of the igniter 40 causes the transfer charge 59 to start burning. The cup-shaped member 50 ruptures, causing the gas generating agent 61 to burn and generate a large amount of gas. The gas passes through the inside of the filter 200 and flows into the gap 28. As the internal pressure inside the housing increases, the sealing tape 24 that has been closing the gas outlet 23 ruptures, and gas is ejected outside the housing through the gas outlet 23. The ejected gas inflates and deploys the airbag.

[0029] First Embodiment The configuration of the filter will be described in detail with reference to FIG. As shown in FIG. 1(b), the winding body 210A (210) has a low-turn portion 211 at its outer periphery, which includes the wire layer (outermost layer) Ln located at the outermost side of the winding body among the plurality of wire layers L formed by the metal wire 220, in which the number of turns p of the metal wire 220 in each wire layer L is smaller than the number of turns of the metal wire in each wire layer in the inner periphery portion 213 located inside the outer periphery. 1(a), the protective member 231 (230) is formed as a separate member from the metal wire 220. The protective member 231 is attached to an appropriate position of the winding 210A, and at least a portion (contact portion 221) of the metal wire portion 220(n) (first metal wire portion) constituting the outermost layer Ln of the winding is in contact with the protective member 231.

[0030] <Winding body> In this example, the wire layers Ln and Ln-1 form a low-turn portion 211, and the wire layers Ln-2 to L1 form an inner circumferential portion 213. In the low-turn portion 211, the number of turns (number of windings) of the metal wire 220 in each wire layer L is smaller than that in the inner circumference portion 213. That is, the low-turn portion 211 includes a portion where the winding pitch is wider than the winding pitch of each wire layer located in the inner circumference portion 213. Here, the winding pitch refers to the axial spacing of the metal wire 220 in each wire layer L.

[0031] The low turn portion 211 includes at least the outermost layer Ln. As shown in Fig. 1, the low turn portion 211 preferably includes the outermost layer Ln and a wire layer Ln-1 adjacent to the outermost layer. The low turn portion 211 may include three or more wire layers. Increasing the number of wire layers constituting the low-turn portion 211 increases the external size of the winding body 210A. Therefore, the number of wire layers constituting the low-turn portion 211 is set to an optimum number of layers in consideration of the strength and size required of the winding body 210A. For example, the number of wire layers constituting the low-turn portion 211 is set to approximately 1 to 10 layers. The number of turns of the metal wire 220 in each wire layer constituting the low-turn portion 211 will be described later.

[0032] <Protective materials> In the unlikely event that the metal wire portion 220(n) breaks, the protective member 231 serves to prevent fraying of the metal wire 220 or minimize the adverse effects of fraying of the metal wire 220. Here, "fraying" refers to a disturbance in the winding state of the metal wire, such as the metal wire floating up or the winding of the metal wire becoming loose. The metal wire portion located on the inner periphery is pressed down by the metal wire portion located further outward. Therefore, the metal wire portion located in the inner periphery 213 (inside the outer periphery including the outermost layer) will not fray even if the metal wire portion 220(n) breaks. However, if the metal wire portion 220(n) breaks, it will fray in the radially outward direction. The protective member 231 prevents such fraying of the metal wire portion 220(n).

[0033] The protective member 231 extends in a direction intersecting with the metal wire portions 220(n) and 220(n-1). The protective member 231 in this example is a strip-shaped or linear member extending in the circumferential direction. The protective member 231 is disposed in the axial middle of the winding body 210A and wraps around the winding body at least once.

[0034] Protective member 231 is attached so that the entire portion facing winding body 210A is along (or attached to) the surface of the winding body. Protective member 231 intersects metal wire portion 220(n) at one point, and the intersecting portion is contact portion 221 that comes into contact with metal wire portion 220(n).

[0035] The protective member 231 is configured so as not to separate from the winding body 210A, not to float up, and not to break when subjected to a force from the broken metal wire portion 220(n) that tends to fray or a force that tends to snap in the outer diameter direction (or tends to come off in the outer diameter direction).

[0036] The protective member 231 may be made of the same material as the metal wire 220, or may be made of a different material. It is desirable that the protective member 231 has higher strength and rigidity than the metal wire 220.

[0037] Protective member 231 is attached to winding body 210A in a manner that can prevent fraying. For example, at least a portion of protective member 231 can be firmly fixed (joined) to winding body 210A. Alternatively, protective member 231 may be fixedly attached to winding body 210A using frictional force. Protective member 231 is attached to winding body 210A by a method appropriate for the material that constitutes it.

[0038] Increasing the number of joints of protective member 231 to winding body 210A is advantageous in that it enhances the protective function of the protective member for the winding. The strength and rigidity of protective member 231 itself and the number of joints of the protective member to winding body 210A are set in accordance with the relationship between the two so that the protective member can exert the necessary protective function (protective effect). If the protective member 231 does not come off the winding body 210A, the protective member and the metal wire portion 220(n) need only be in contact with each other, and the two do not necessarily need to be joined together.

[0039] The area (covered area) of the outer circumferential surface of winding 210A covered by the non-void portion of protective member 231 is preferably 30% or less of the outer circumferential surface of the winding. The reason for setting the area to 30% or less will be described later.

[0040] <<Material Examples>> <<<Metal materials>>> Protective member 231 may be made of a metal material. If made of a metal material, protective member 231 may be made of any of the materials that can be used for winding body 210, such as iron, mild steel, stainless steel, nickel alloy, and copper alloy.

[0041] The protective member 231 can take a variety of shapes. The protective member may be a steel plate without holes. The protective member may also have a large number of holes. In this case, the protective member may be an expanded metal or a punched metal. The protective member may also be a metal mesh such as a woven fabric, knitted fabric, or nonwoven fabric made of a metal material. The protective member 231 may be a wire. When the wire-shaped protective member 231 is made of the same metal material as the metal wire 220, the cross-sectional area of ​​the protective member is made larger than that of the metal wire 220, for example, to ensure the strength and rigidity required for the protective member.

[0042] Protective member 231 made of a metallic material can be joined (fixed) to winding body 210A by welding or adhesive. Protective member 231 can also be joined to winding body 210A using a resin adhesive or pressure-sensitive adhesive, or by brazing or soldering. When protective member 231 is a linear metal member, it is also possible to attach the protective member to winding body 210A by winding the protective member around winding body 210A and then twisting and fixing both ends of the protective member in the longitudinal direction.

[0043] <<<Resin materials>>> The protective member may be made of a resin material such as a silicon-based material, an acrylic-based material, etc. The protective member made of a resin material is adhered to the winding body using, for example, an adhesive or a pressure-sensitive adhesive.

[0044] <<<The bonding agent itself>>> The protective member may be the adhesive itself that is bonded to the winding body 210A. For example, the protective member 231 may be a resin adhesive applied to the winding body 210A, a brazing material brazed to the winding body 210A, or solder soldered to the winding body 210A. Alternatively, the protective member may be an adhesive itself that can adhere to the winding body 210A. For example, a silicone-based or acrylic-based adhesive having a predetermined thickness can be used as the adhesive.

[0045] <<Installation method>> 4(a) and 4(b) are plan views illustrating an example of a method for attaching a protective member wound in the circumferential direction. The direction perpendicular to the paper surface in the figure is the axial direction of the winding body 210A. FIG. 4 shows an example in which the linear or band-like protective member shown in FIG. 1(a) is wound around the winding body. The following description will be given using an example in which the protective member is made of metal.

[0046] For example, as shown in FIG. 4(a), one longitudinal end 231a of the protective member 231 is fixed to an appropriate position in the circumferential direction of the winding body 210A by spot welding. Then, the protective member 231 is wound around the winding body 210A in the circumferential direction. As shown in FIG. 4(b), the other longitudinal end 231b of the protective member 231 is overlapped with one longitudinal end of the protective member 231. Both longitudinal ends of the protective member 231 are joined together by spot welding. The positions of the two spot welds are adjusted so that they do not overlap in the radial direction.

[0047] The other longitudinal end 231b of the protective member 231 does not have to overlap with the protective member 231 in the radial direction. For example, the other longitudinal end 231b of the protective member 231 may be joined to the winding 210A. In this case, each end 231a, 231b of the protective member 231 is joined to a metal wire portion of the third or subsequent layer (wire layer Ln-2, ​​Ln-3, ...) from the outer periphery of the winding 210A. Even in this case, the protective member 231 has a portion where one longitudinal portion and another longitudinal portion are circumferentially positioned to overlap in the axial direction. In other words, the protective member 231 is wound around the winding 210A at least once.

[0048] Protective member 231 may be fixed at a middle portion in the longitudinal direction to winding body 210A, or at multiple points in the longitudinal direction to winding body 210A.

[0049] <<Installation location>> 5(a) and 5(b) are schematic front views illustrating the attachment position of the protective member. The drawings show only the metal wire portion 220(n) (first metal wire portion) of the outermost layer Ln and the metal wire portion 220(n-1) (second metal wire portion) of the wire layer Ln-1, which is the adjacent layer adjacent to the outermost layer, as the metal wire belonging to the low-turn portion 211 (see FIG. 5). The metal wire portions 220(n) and 220(n-1) are wound approximately evenly at a constant pitch in the axial direction of the winding body 210A.

[0050] The protective member 231 is preferably disposed so as to overlap the intersection 222 between the metal wire portion 220(n) and the metal wire portion 220(n-1). In this case, the metal wire portion 220(n) comes into contact with the protective member 231 at the intersection 222.

[0051] When filter 201 includes one protective member 231, it is desirable that the number of turns of metal wire 220 belonging to the low-turn section be one or less. In particular, it is desirable that metal wire portion 220(n) and metal wire portion 220(n-1) are wound so as to intersect at or around the axial center of winding body 210A. In this case, protective member 231 is disposed at or around the axial center of winding body 210A, and overlaps with intersection 222 of metal wire portion 220(n) and metal wire portion 220(n-1).

[0052] In this way, the length of the metal wire 220 that can be unwound becomes equal when the metal wire portion 220(n) is broken at one end side of the protective member 231 (intersection 222) in the axial direction and when it is broken at the other end side. This means that the length of the unwound metal wire 220 can be minimized. In other words, in this example, this means that the length of the unwound metal wire 220 can be made equal to or less than the length of one revolution.

[0053] For example, as shown in Figure 5(b), suppose that a break 223 occurs in metal wire portion 220(n) in portion 210a of the winding body that is closer to one axial end than protective member 231. In this case, unraveled portion 220a of the metal wire remains within portion 210a of the winding body and does not spread to portion 210b of the winding body that is closer to the other axial end than protective member 231. The length of the unraveled metal wire 220 is one full turn or less. The same applies if a break occurs in portion 210b of the winding body.

[0054] FIG. 6 is a schematic front view illustrating the number of turns of the metal wire rod belonging to the low-turn-number portion. Here, the reason why the number of turns of the metal wire 220 belonging to the low-turn portion 211 is "one turn or less" is as follows. Specifically, the terminal end 224 of the metal wire 220 is generally fixed to an appropriate position on the winding body 210A by spot welding. The spot welding location is selected from any position on the already wound metal wire 220. Therefore, even if the metal wire portion 220(n) is wound at a pitch and angle that allows it to make one turn, the metal wire portion 220(n) does not actually make one turn. For example, if the metal wire portion 220(n) is welded to the axial center of the winding body 210A, the length of the metal wire portion 220(n) is 0.5 turns. For this reason, the number of turns of the metal wire 220 belonging to the low-turn portion 211 is specified as "one turn or less."

[0055] <Modification> 7(a) and 7(b) are schematic front views showing a modified example of the first embodiment. In Fig. 7(a) and 7(b), the explanation will be given on the assumption that the number of turns of the metal wire portion 220(n-1) (not shown) is the same as that of the metal wire portion 220(n).

[0056] 1 and 7, the number of protective members 231 is set to satisfy the following condition. That is, when the number of turns of the metal wire portion 220(n) of the outermost layer Ln is p (where p is a positive number) and the number of protective members is q (where q is a natural number), the number is set to satisfy p≦q. In the filter 201, the number of contact portions 221 is r=q. As shown in filters 201B and 201C, filter 201 may include a plurality of protective members 231 (231A to 231C).

[0057] 7(a) shows an example in which the number of turns of the metal wire portion 220(n) is p=1 and the number of protective members 231 is q=3. It is desirable that at least one protective member 231B overlaps the intersection 222 of the metal wire portion 220(n) and the metal wire portion 220(n-1) (not shown). However, if the number of protective members q is greater than the number of turns q rounded up to the nearest whole number, the length of the metal wire 220 that can be unwound can be made equal to or less than the length of one turn, even if the protective members are not overlapped at the intersection 222.

[0058] 7(b) shows an example in which the number of turns of the metal wire portion 220(n) is p=3 and the number of protective members 231 is q=3. If the number of turns q, rounded up to the nearest whole number, is made the same as the number of protective members q, and if the protective members are overlapped at the intersections 222, the length of the metal wire 220 that can be unwound can be made equal to or shorter than the length of one turn.

[0059] When the filter 201 includes a plurality of protective members 231, the axial intervals between the protective members are set so that the length of the metal wire 220 that can be unwound is equal to or less than a desired length (for example, equal to or less than one revolution).

[0060] Second Embodiment FIG. 8 is a schematic front view showing a filter according to a second embodiment of the present invention. Filter 202A (202, 200) includes winding body 210B (210) and protective member 232 (230). Winding body 210B shown in the figure differs from that of the first embodiment in that it does not include low-turn portion 211 (FIG. 1). Note that the winding body included in the filter according to this embodiment may be winding body 210A shown in FIG. 1.

[0061] As in the first embodiment, the protective member 232 is configured as a member separate from the metal wire 220. Moreover, it is desirable that the protective member 232 has higher strength and rigidity than the metal wire 220, and the materials that can be used for the protective member 232 are the same as those in the first embodiment. The protection member 232 differs from the first embodiment in that it is not wound around the winding body 210B.

[0062] In this example as well, it is desirable that the area (covered area) of the outer circumferential surface of winding 210B covered by the non-void portion of protective member 232 be 30% or less of the outer circumferential surface of the winding. The reason for setting it to 30% or less will be described later.

[0063] Hereinafter, the same components as those in the first embodiment will be denoted by the same reference numerals, and the description will be omitted as appropriate. The differences from the first embodiment will be mainly described.

[0064] <Protective materials> In filter 202A, protective member 232 is disposed at a position in the circumferential direction of winding body 210B and fixed in place on winding body 210B. The protective member 232 extends in a direction intersecting with the metal wire portion 220(n). The protective member 232 according to this example is a strip-shaped member extending in the axial direction and intersecting with the metal wire 220. The protective member 232 covers a portion of the winding body 210B in the circumferential direction.

[0065] When filter 202A includes a single protective member 232, the length of protective member 232 is set so as to span the portion (contact portion 221A) located closest to one end in the axial direction and the portion (contact portion 221C) located closest to the other end of metal wire portion 220(n) that may overlap with protective member 232. For example, protective member 232 can extend over the entire axial length of winding body 210B.

[0066] <<Installation location>> 9(a) and 9(b) are schematic front views illustrating the attachment position of the protective member. Of the metal wire parts, only metal wire part 220(n) is shown in FIG. 9(a), and only metal wire parts 220(n) and 220(n-1) are shown in FIG.

[0067] The filter 202A is configured to satisfy p≦r, where p (where p is a positive number) is the number of turns of the metal wire portion 220(n) constituting the outermost layer Ln of the winding body 210B, and r (where r is a natural number) is the number of contact portions 221 where the metal wire portion 220(n) and the protective member 232 come into contact with each other. In this example, the number of turns of the metal wire portion 220(n) is p=3, and the metal wire portion 220(n) has a plurality of contact portions 221 (221A to 221C), the number of which is r=3. By doing so, even if the metal wire portion 220(n) breaks at any point, as shown in FIG. 9(b), the length of the metal wire 220 that can be unwound can be kept to the length of one turn or less.

[0068] 9(b) shows a case where disconnection 223A occurs closer to one end in the axial direction than contact portion 221A, and disconnection 223B occurs between contact portions 221B and 221C. In both cases, only the metal wire 220 between contact portions 221, 221 is unraveled, and the length of unraveled portions 220a, 220b of the metal wire is one revolution or less.

[0069] In this example, protective member 232 is strip-shaped and extends axially, and its longitudinal length is approximately equal to the axial length of winding body 210B. Therefore, each contact portion 221 is located at the same position in the circumferential direction and is spaced apart in the axial direction. Furthermore, all contact portions 221A to 221C are located on a single protective member 232.

[0070] 9(b), similarly to the first embodiment, in this example, it is desirable that the protective member 232 is disposed so as to come into contact with the metal wire portion 220(n) at the intersection 222. In this way, it is possible to control so that there is not a large difference in the length of the metal wire that is unwound when the metal wire portion 220(n) is broken at one end side of the intersection 222 in the axial direction and when it is broken at the other end side.

[0071] <<Installation method>> The protective member 232 is fixed to the winding body 210B by a method suitable for the shape of the protective member 232 among the methods described in the first embodiment. The protective member 232 is fixed to the winding body 210B so that, if the metal wire portion 220(n) breaks, the protective member 232 will not come off from the winding body 210B together with the metal wire portions 220(n), 220(n-1).

[0072] The illustrated filter 202A includes three joints 233A to 233C as joints 233 where protective member 232 and winding body 210B are joined. The joints 233 are, for example, spot-welded locations. The two joints 233A and 233C are located at both longitudinal ends of protective member 232. Joint 233B is located at an appropriate position between joints 233A and 233C.

[0073] In order to perform the necessary functions, protective member 232 is fixed to winding body 210B so that no large gap is formed between the winding body and the outer peripheral surface of the winding body. For this reason, when the longitudinal length of protective member 232 is relatively long, such as when protective member 232 extends over the entire axial length of winding body 210B, it is desirable to provide at least one joint 233 at each longitudinal end of protective member 232. In this case, a required number of joints 233 are provided in the longitudinal middle portion according to the longitudinal length of protective member 232 (or the axial length of winding body 210B).

[0074] <Modification> 10(a) and 10(b) are schematic front views showing a modified example of the second embodiment. The filter 202 (202B, 202C) may include a plurality of protective members 232 (232A to 232C). The protective members 232 may be shorter than the entire axial length of the winding body 210B.

[0075] 10(a) shows an example in which the number of turns of the metal wire portion 220(n) is p=3 and the number of protective members 232 is q=3. Each of the protective members 232A to 232C has one contact portion 221 (221A to 221C). The total number of contact portions 221 included in the filter 202B is r=3, which satisfies p≦r.

[0076] Each protective member 232 is arranged to have at least one contact portion 221 around each circumference of the metal wire portion 220(n). That is, each protective member 232 is arranged so that the distance between two adjacent contact portions 221, 221 is within one circumference. Furthermore, each protective member 232 is arranged so that the contact portions 221 are spaced apart in the axial direction.

[0077] 10(b) shows an example in which the number of turns of the metal wire portion 220(n) is p=3 and the number of protective members 232 is q=2. Each of the protective members 232A and 232B has two contact portions 221. The total number of contact portions 221 (221A to 221D) included in the filter 202C is r=4, which satisfies p≦r.

[0078] Each protective member 232 is arranged so that the interval between two adjacent contact portions 221, 221 is within one circumference. For example, each protective member 232A, 232B is arranged so that the interval between two adjacent contact portions 221B, 221C is within one circumference. Furthermore, each protective member 232A, 232B is arranged so that the contact portions 221 are spaced apart in the axial direction.

[0079] 10(a) and 10(b), each protective member 232 has two joints 233, but the number of joints per protective member is not limited to this. For example, the protective member 232 shown in FIG. 10(a) is short in itself, so it is sufficient to have only one joint 233 on the metal wire portion 220(n).

[0080] [Basis of coverage rate] 11(a) and 11(b) are photographs of the test specimen used to calculate the relationship between the pressure loss and the coverage rate of the outer periphery of the winding body by the protective member. Specimen 240 (240A, 240B) was obtained by covering the outer surface of winding body 210B with aluminum-based tape 241 (241A, 241B). Tape 241 did not have any holes passing through its surface (holes connecting the inner diameter side facing winding body 210B with the outer diameter side), and had a porosity of 0%.

[0081] 11(a) shows a test piece 240A in which a tape 241A is wound around the axial center of a winding body 210B. The tape 241A covers the entire circumference of the winding body 210B. 11(b) shows a test piece 240B in which tape 241B is attached to appropriate positions in the circumferential direction of the winding body 210B. The tape 241B extends in the axial direction of the winding body 210B and covers the entire winding body 210B in the axial direction.

[0082] When the width of tape 241 was increased, the coverage area expanded in the axial direction (height direction) in test piece 240A, and in the circumferential direction in test piece 240B. The pressure loss was measured for each tape width (coverage rate) in each test piece 240, and the relationship between the coverage rate (blockage rate) of the outer surface of winding body 210B and the pressure loss was determined.

[0083] Figures 12(a) and 12(b) show the relationship between the outer periphery coverage rate of the winding body by the protective member and pressure loss. Figure 12(a) corresponds to test piece 240A, and Figure 12(b) corresponds to test piece 240B. Each figure shows the original data and the graph. The dashed lines shown are approximate straight lines when the coverage rate is 0 to 30%.

[0084] The winding body 210B constituting each test piece 240 has an outer diameter (diameter) of 53 mm, a height (axial length) of 49 mm, and an outer peripheral area of ​​8159 mm^2. The pressure loss of the winding body when the coverage rate is 0% is 0.42 kPa. The "pressure loss increase rate" in the table is "{pressure loss at coverage rate x% - pressure loss at coverage rate (x-10%)} / pressure loss at coverage rate (x-10%)."

[0085] As shown in FIG. 12, the relationship between the coverage and the pressure loss is roughly the same for both test specimens 240A and 240B. As shown in the graphs in Figures 12(a) and 12(b), the pressure loss increases almost linearly up to a coverage of 30%. Once the coverage exceeds 30%, the graph becomes nonlinear and the rate of increase in pressure loss increases sharply.

[0086] From the above results, in the present invention, it is desirable to set the coverage of winding 210 (210A, 210B) to 30% or less in order to prevent a sudden increase in pressure loss. The coverage of the winding by the protective member takes into consideration the porosity of the protective member (or the pressure loss of the protective member). In other words, it is desirable to set the coverage of the winding by the non-void portion of the protective member to 30% or less of the outer circumferential area of ​​the winding. By determining the coverage of the winding by the protective member based on the pressure loss of the filter, it is possible to suppress power loss of the explosive when a filter equipped with a protective member is used in a gas generator.

[0087] [Summary of Examples of Embodiments, Actions, and Effects of the Present Invention] <First embodiment> The filter 201 according to this embodiment includes a winding body 210A in which a metal wire 220 is wound spirally and in multiple layers, and at least one protective member 231 that covers a portion of the outer circumferential surface of the winding body to prevent fraying of the metal wire. The winding has a low-turn portion 211 at its outer periphery, including the outermost layer Ln, where the number of turns of the metal wire is fewer than that of the inner periphery 213. The protective member is made of a separate member from the metal wire and is attached to the winding in an appropriate position. The filter is characterized in that at least a portion (contact portion 221) of the first metal wire portion 220(n) constituting the outermost layer of the winding is in contact with the protective member.

[0088] According to this aspect, a protective member made of a component independent of the metal wire is attached to the outermost layer of the winding body, so that even if the metal wire breaks, the metal wire will not fray, or the fraying of the metal wire will be limited to a small part of the wire and will not spread to other parts of the wire. Furthermore, since the number of turns of the metal wire is reduced in the outer periphery, even if the metal wire breaks in the low-turn portion, the length of the frayed metal wire can be kept to a minimum.

[0089] <Second embodiment> In filter 201 according to this embodiment, protective member 231 is disposed in the axial middle of winding body 210A and wraps around the winding body at least once. The protective member may be a member extending in the circumferential direction of the winding body.

[0090] <Third embodiment> The filter 201 according to this embodiment is characterized in that, when the number of turns of the first metal wire portion 220(n) is p (where p is a positive number) and the number of protective members 231 is q (where q is a natural number), p≦q is satisfied. According to this aspect, the length of the metal wire that frays can be kept to one circumference or less.

[0091] <Fourth embodiment> The filter 201 according to this embodiment is characterized in that the number of turns of the metal wire 220 in the outermost layer Ln and its adjacent layer Ln-1 is one or less. According to this aspect, the length of the metal wire that frays can be kept to one circumference or less.

[0092] <Fifth and ninth embodiments> In the filter 200 according to this embodiment, the area of ​​the winding 210 covered by the non-void portion of the protective member 230 is 30% or less of the outer peripheral area of ​​the winding. According to this aspect, it is possible to avoid a sudden increase in pressure loss due to the provision of a protective member.

[0093] <Sixth embodiment> The filter 202 according to this embodiment includes a winding body 210B in which a metal wire 220 is wound spirally and in multiple layers, and at least one protective member 232 that covers a portion of the outer circumferential surface of the winding body to prevent fraying of the metal wire. The protective member is made of a separate member from the metal wire, and is disposed at a circumferential position of the winding body and fixed to an appropriate position on the winding body. The filter is characterized in that, when the number of turns of the first metal wire portion 220(n) constituting the outermost layer Ln of the winding body is p (where p is a positive number), and the number of contact portions 221 where the first metal wire portion and the protective member come into contact is r (where r is a natural number), p≦r is satisfied.

[0094] According to this aspect, a protective member made of a component independent of the metal wire is attached to the outermost layer of the winding body, so that even if the metal wire breaks, the metal wire will not fray, or the fraying of the metal wire will be limited to a small part of the wire and will not spread to other parts of the wire. Furthermore, the length of the metal wire that frays can be kept to one circumference or less.

[0095] <Seventh embodiment> In the filter 202 according to this embodiment, the first metal wire portion 220(n) is characterized in that it has a plurality of contact portions 221, and the contact portions are spaced apart from each other in the axial direction. According to this aspect, the length of the metal wire that frays can be limited to one circumference or less. Note that the multiple contact portions may be formed between the first metal wire portion and a single protective member, or may be formed between the first metal wire portion and multiple protective members.

[0096] <Eighth embodiment> In the filter 202 according to this embodiment, the protective member 232 extends in a direction intersecting with the first metal wire portion 220(n) and is characterized by including a plurality of contact portions 221. According to this aspect, the number of protective members can be reduced, which makes it easier to manufacture the filter.

[0097] <Tenth embodiment> This aspect is characterized by a gas generator 1 incorporating the filter 200 of each of the above-described embodiments. The gas generator according to this aspect enjoys the effects achieved by the filters of the above-described embodiments. [Explanation of symbols]

[0098] L, L1, L2...Ln...wire layer, Ln...outermost layer, Ax1...(filter) central axis, Ax2...(mandrel) central axis, 1...(disk-shaped) gas generator, 10...lower shell, 11...bottom plate portion, 12...circumferential wall portion, 13...projecting cylindrical portion, 14...recessed portion, 15...opening, 20...upper shell, 21...top plate portion, 22...circumferential wall portion, 23...gas outlet, 24...sealing tape, 25 ...flange portion, 28...gap portion, 30...holding portion, 34...female connector portion, 40...igniter, 41...ignition portion, 42...terminal pin, 50...cup-shaped member, 59...transfer charge, 60...combustion chamber, 61...gas generating agent, 70...lower support member, 80...upper support member, 85...cushion material, 130...winding device, 131...mandrel, 132...guide member, 150...welding machine, 151...electrode, 2 00...filter, 201, 201A-C...filter, 202, 202A-C...filter, 210, 210A, 210B...winding body, 210a, 210b...winding body portion, 211...low turn number portion, 213...inner peripheral portion, 220...metal wire, 220(n)...(first) metal wire portion, 220(n-1)...(second) metal wire portion, 220a, 220b...unwound portion, 221, 221A to 221C...contact portion, 222...intersection portion, 223, 223A, 223B...disconnection, 224...termination portion, 230...protective member, 231, 231A to C...protective member, 231a...one end portion, 231b...other end portion, 232, 232A, 232B...protective member, 233, 233A to C...joint portion, 240, 240A, 240B...test specimen, 241, 241A, 241B...tape

Claims

1. A filter comprising a winding body in which a metal wire is wound in a spiral and in multiple layers, and at least one protective member that covers a part of an outer circumferential surface of the winding body to prevent fraying of the metal wire, the winding body includes a low-turn portion in an outer periphery including an outermost layer of the winding body, in which the number of turns of the metal wire is smaller than that of an inner periphery portion, the protective member is formed as a separate member from the metal wire and is attached to the winding body in an appropriate position; A filter characterized in that at least a portion of the first metal wire portion constituting the outermost layer of the winding body is in contact with the protective member.

2. 2. The filter according to claim 1, wherein the protective member is disposed at an axially intermediate portion of the winding body and extends around the winding body at least once.

3. The filter according to claim 1, characterized in that, when the number of turns of the first metal wire portion is p (where p is a positive number) and the number of protective members is q (where q is a natural number), p≦q is satisfied.

4. 2. The filter according to claim 1, wherein the number of turns of the metal wire in the outermost layer and the adjacent layer is one or less.

5. 2. The filter according to claim 1, wherein the area of ​​the winding covered by the non-void portion of the protective member is 30% or less of the outer circumferential area of ​​the winding.

6. A filter comprising a winding body in which a metal wire is wound in a spiral and in multiple layers, and at least one protective member that covers a part of an outer circumferential surface of the winding body to prevent fraying of the metal wire, the protective member is formed as a separate member from the metal wire, and is disposed at a portion of the winding body in the circumferential direction and fixed to an appropriate position on the winding body; a filter characterized in that, when the number of turns of the first metal wire portion constituting the outermost layer of the winding body is p (where p is a positive number), and the number of contact portions where the first metal wire portion and the protective member are in contact is r (where r is a natural number), p≦r is satisfied.

7. 7. The filter of claim 6, wherein the first metal wire portion comprises a plurality of the contact portions, each of the contact portions being spaced apart in the axial direction.

8. 7. The filter according to claim 6, wherein the protection member extends in a direction intersecting the first metal wire portion and includes a plurality of the contact portions.

9. 7. The filter according to claim 6, wherein the area of ​​the winding covered by the non-void portion of the protective member is 30% or less of the outer circumferential area of ​​the winding.

10. A gas generator incorporating a filter according to any one of claims 1 to 9.

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