gas generator

Abstract

To provide a technology relating to a filter unit for a gas generator suitable for manufacturing the gas generator.SOLUTION: A filter unit for a gas generator includes a filter and a filter housing that coaxially positions and fixes the filter in a filter housing space, and the filter housing includes a first restricting end portion that is disposed at one end of the filter housing as a closed surface and restricts one axial end surface of the filter, a second restricting end portion that is disposed at the other end of the filter housing so as to surround a periphery of a gas inflow port and restricts the other axial end surface of the filter, and a peripheral wall portion that connects the first restricting end portion and the second restricting end portion and has a gas discharge port. The circumferential wall includes a restraining circumferential wall that restrains a circumferential surface of the filter, and a non-restraining circumferential wall in which the gas discharge port is disposed and which is disposed apart from the circumferential surface of the filter such that an annular gap is formed between the non-restraining circumferential wall and the circumferential surface.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a filter unit for a gas generator, a gas generator, and a method for manufacturing a gas generator. [Background technology]

[0002] Conventionally, a long cylindrical gas generator has been known that includes a combustion chamber housing unit that accommodates a gas generating agent therein, and a filter housing that accommodates a filter therein and is attached to one end of the combustion chamber housing unit (see, for example, Patent Document 1). The combustion chamber housing unit has, for example, a long cylindrical metal combustion chamber housing, within which a combustion chamber that accommodates the gas generating agent is formed. In addition, for example, an igniter is attached to the other end of the combustion chamber housing for igniting the gas generating agent accommodated in the combustion chamber.

[0003] Typically, the filter housing is formed with a gas outlet for discharging combustion gas generated by combustion of the gas generating agent to the outside. The combustion gas generated in the combustion chamber housing unit passes through the filter before being discharged to the outside from the gas outlet, whereby it is cooled and slag (residue) contained in the combustion gas is collected by the filter. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 6,908,104 Summary of the Invention [Problem to be solved by the invention]

[0005] In the gas generator disclosed in Figure 1 and other figures of Patent Document 1, filter housing 51 that houses filter 37 is assembled to container 41 that houses gas generating agent 52. However, in conventional filter units for gas generators, filter 37 housed within filter housing 51 is not positioned until filter housing 51 is assembled to container 41. Therefore, before filter housing 51 is assembled to container 41, filter 37 is not fixed within filter housing 51 and is not unitized. As a result, filter 37 is prone to falling off filter housing 51 during the manufacturing process of the gas generator, making handling difficult.

[0006] The technique of the present disclosure has been made in view of the above-described circumstances, and has an object to provide a technique relating to a filter unit for a gas generator that is suitable for manufacturing a gas generator. [Means for solving the problem]

[0007] A filter unit for a gas generator according to the present disclosure for solving the above-mentioned problems comprises a filter having a columnar outer shape, and a filter housing that houses the filter in a filter housing space formed inside, in a state where the filter is positioned and fixed coaxially, the filter housing having a first constraining end portion that is arranged as a closed surface at one end of the filter housing and that constrains one axial end face of the filter, a second constraining end portion that is arranged at the other end of the filter housing so as to surround the periphery of a gas inlet and that constrains the other axial end face of the filter, and a peripheral wall portion that connects between the first constraining end portion and the second constraining end portion and that has a gas discharge port, the first constraining end portion, the second constraining end portion and the peripheral wall portion being integrally formed, the peripheral wall portion having a constraining peripheral wall portion that constrains the peripheral surface of the filter, and the gas discharge port is arranged at a distance from the peripheral surface of the filter so as to form an annular gap between the peripheral wall portion and the peripheral surface of the filter, and a non-constraining peripheral wall portion.

[0008] Here, the second restraining end portion may be formed by an annular flange in which an end portion of the peripheral wall portion is folded toward the filter accommodating space.

[0009] Furthermore, the peripheral wall portion may include a small diameter portion and a large diameter portion having an outer diameter larger than that of the small diameter portion, and the constrained peripheral wall portion may be formed by the small diameter portion, and the non-constrained peripheral wall portion may be formed by the large diameter portion.

[0010] The constraining peripheral wall portions may be formed on both one end side and the other end side of the peripheral wall portion in the axial direction, and the non-constraining peripheral wall portion may be formed between the pair of constraining peripheral wall portions.

[0011] The filter may have a cylindrical shape with a hollow portion formed along the axial direction, and the second restraining end portion may cover the entire end face of the filter.

[0012] The filter may have a cylindrical shape with a hollow portion formed along the axial direction, and the diameter of the gas inlet may be equal to or smaller than the inner diameter of the filter.

[0013] Furthermore, a plurality of the gas exhaust ports may be formed in the peripheral wall portion, and the total opening area of ​​the plurality of gas exhaust ports may be larger than the opening area of ​​the gas inlet.

[0014] The technology according to the present disclosure can also be specified as a gas generator. That is, the gas generator according to the present disclosure comprises a combustion chamber housing unit having a cylindrical combustion chamber housing in which a combustion chamber that accommodates a gas generating agent is formed and an igniter attached to the combustion chamber housing, and any of the above-mentioned filter units for a gas generator that is assembled to one end of the combustion chamber housing, with the gas inlet of the filter housing being arranged to face the combustion chamber.

[0015] Furthermore, a gas generator according to the present disclosure may comprise a combustion chamber housing unit having a cylindrical combustion chamber housing in which a combustion chamber for accommodating a gas generating agent is formed and an igniter attached to the combustion chamber housing, and a gas generator filter unit assembled to one end of the combustion chamber housing, wherein the filter housing has an annular step portion between the small diameter portion and the large diameter portion, and the small diameter portion of the filter housing is inserted into the one end of the combustion chamber housing so that the gas inlet faces the combustion chamber, and the annular step portion abuts against an open end face at the one end side of the combustion chamber housing.

[0016] The technology according to the present disclosure can also be specified as a method for manufacturing a gas generator. A method of manufacturing a gas generator according to the present disclosure comprises the steps of: preparing a filter unit for a gas generator, the filter comprising a filter having a columnar outer shape, and a filter housing that accommodates the filter in a filter accommodating space formed therein while positioning and fixing the filter coaxially; preparing a combustion chamber housing unit that has a cylindrical combustion chamber housing in which a combustion chamber that accommodates a gas generating agent is formed, and an igniter attached to the combustion chamber housing; and assembling the filter unit for a gas generator to one end of the combustion chamber housing, wherein the filter housing has, integrally formed, a first constrained end portion, a second constrained end portion, and a peripheral wall portion that connects the first constrained end portion and the second constrained end portion, and the peripheral wall portion has a non-constrained peripheral wall portion in which a gas outlet is arranged, and a constrained peripheral wall portion that constrains a peripheral surface of the filter, and when preparing the filter unit for a gas generator, the first constrained end portion is arranged at one end of the filter housing as a closing surface to constrain one axial end surface of the filter, and the second constrained end portion is arranged at the other end of the filter housing so as to surround the periphery of a gas inlet By doing so, the other axial end face of the filter is constrained, the non-constrained peripheral wall portion is positioned away from the peripheral surface of the filter so as to form an annular gap between the non-constrained peripheral wall portion and the peripheral surface of the filter, and the constrained peripheral wall portion constrains the peripheral surface of the filter. [Effects of the Invention]

[0017] According to the present disclosure, a technique can be provided relating to a filter unit for a gas generator that is suitable for manufacturing a gas generator. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic axial cross-sectional view showing an example of a gas generator according to a first embodiment. [Figure 2] FIG. 2 is a diagram illustrating the detailed structure of the filter unit. [Figure 3] FIG. 3 is a flowchart illustrating the steps of the method for manufacturing a gas generator. [Figure 4] FIG. 4 is a diagram illustrating the filter unit preparation step. [Figure 5] FIG. 5 is a diagram illustrating the state of the assembly process. [Figure 6] FIG. 6 is a diagram illustrating an example of the placement of a sealing member and a porous member that are placed at the second restraining end of the filter housing. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that each configuration and combination thereof in the embodiments is merely an example, and addition, omission, substitution, and other modifications of the configuration are possible as appropriate within the scope of the gist of the present disclosure. The present disclosure is not limited by the embodiments, but is limited only by the claims.

[0020] <Embodiment 1> Fig. 1 is a schematic axial cross-sectional view showing an example of a gas generator according to embodiment 1. Gas generator 1 can be used, for example, as a gas generating device for inflating an airbag. Gas generator 1 in Fig. 1 includes a combustion chamber housing unit 10 and a filter unit 4 (gas generator filter unit) assembled integrally with combustion chamber housing unit 10.

[0021] The combustion chamber housing unit 10 has a cylindrical combustion chamber housing 2, and the filter unit 4 is attached to one axial end of the combustion chamber housing 2. The igniter 3 is attached to the other axial end of the combustion chamber housing 2. Hereinafter, the end of the combustion chamber housing 2 to which the filter unit 4 is attached will be referred to as the first end 2A, and the end to which the igniter 3 is attached will be referred to as the second end 2B. The first end 2A and the second end 2B of the combustion chamber housing 2 are open ends, and are closed by the filter unit 4 and the igniter 3. The combustion chamber housing 2 may be made of metal. The reference symbol 2C denotes the open end surface of the first end 2A of the combustion chamber housing 2.

[0022] The igniter 3 is, for example, an electric ignition type igniter, and it is possible to adopt an igniter that is used in known gas generators. For example, the igniter 3 has a metal cup body 31 that houses and seals an ignition charge, and a pair of conductive pins 32, 32 for receiving a current supply from the outside, which are fixed to a metal igniter holder 33 via a resin member 34. The igniter holder 33 of the igniter 3 may be welded to an opening on the other axial end side of the combustion chamber housing 2, for example. In this case, the igniter holder 33 may be joined to the opening of the combustion chamber housing 2 by full-circumference welding, which allows for airtight welding.

[0023] Inside the combustion chamber housing 2, a cup-shaped separator is placed at a predetermined distance from the igniter 3. A partition wall (retainer) 5 is disposed in the combustion chamber housing 2 at a position closer to the second end 2B, as shown in FIG.

[0024] In the example shown in FIG. 1 , the partition wall 5 has an overall stepped cylindrical shape with a bottom. The side of the partition wall 5 includes a large-diameter portion 51 having a relatively large diameter and a small-diameter portion 52 having a small diameter, and a bottom 53 is connected to the small-diameter portion 52. For example, the outer diameter of the large-diameter portion 51 of the partition wall 5 is approximately the same as the inner diameter of the combustion chamber housing 2, and the large-diameter portion 51 is fixed to the inner circumferential surface of the combustion chamber housing 2. The large-diameter portion 51 of the partition wall 5 may be welded to the inner circumferential surface of the combustion chamber housing 2, or may be fixed by another method. At least one communication hole 54 of any shape is formed in the bottom 53 of the partition wall 5 so as to penetrate the bottom 53.

[0025] The partition wall 5 arranged as described above divides the interior of the combustion chamber housing 2 into a transfer chamber (enhancer chamber) 21 and a combustion chamber 22. Inside the combustion chamber housing 2, the transfer chamber 21 is formed between the igniter 3 and the partition wall 5, and the combustion chamber 22 is formed between the partition wall 5 and the filter unit 4. As shown in FIG. 1 , the cup body 31 of the igniter 3 is arranged facing the inside of the transfer chamber 21.

[0026] A transfer charge (enhancer agent) 61 is accommodated in the transfer charge chamber 21 formed inside the combustion chamber housing 2. A gas generant 62 is accommodated in the combustion chamber 22. The transfer charge 61 and the gas generant 62 are not particularly limited, and various materials applicable to known gas generators can be used. The transfer charge 61 and the gas generant 62 include known compositions, such as guanidine nitrate (41% by weight), basic copper nitrate (49% by weight), binders, and additives. The individual shapes of the transfer charge 61 and the gas generant 62 can be, for example, pellets, disks, columns, or single-hole cylinders with through holes. The transfer charge 61 and the gas generant 62 may be gas generants of the same type, shape, and size, or may be gas generants of different types, shapes, and sizes. The transfer charge 61 may not be loaded in the transfer charge chamber 21, and the gas generant 62 in the combustion chamber 22 may be directly ignited using the igniter 3. Furthermore, the partition wall 5 does not have to be installed inside the combustion chamber housing 2.

[0027] A connector (not shown) is connected to the pair of conductive pins 32, 32 of the igniter 3 when the gas generator 1 is mounted in, for example, an airbag device of a vehicle, enabling power to be supplied from the connector to the igniter 3. The structure of the filter unit 4 will be described later; for example, when a sensor (not shown) in the airbag device detects an impact accompanying a collision of a vehicle or the like, an ignition current is supplied to the pair of conductive pins 32, 32, and the igniter 3 is activated. Then, an ignition charge housed in a cup body 31 of the igniter 3 burns, generating a flame, high-temperature gas, and the like as combustion products. Then, as the ignition charge burns, the internal pressure of the cup body 31 increases, causing the cup body to split, and the flame, high-temperature gas, and the like are released from the split point of the cup body into the transferor chamber 21. As a result, the transfer charge 61 housed in the transferor chamber 21 ignites, and combustion of the transfer charge 61 generates combustion gas as a combustion product.

[0028] As described above, the bottom 53 of the partition 5 is formed with the communication hole 54. Therefore, the combustion gas of the enhancer charge 61 flows into the combustion chamber 22 through the communication hole 54 of the partition 5. As a result, the gas generating agent 62 accommodated in the combustion chamber 22 is ignited, and the gas generating agent 62 burns, generating combustion gas. The combustion gas generated by the combustion of the gas generating agent 62 passes through the filter 7 of the filter unit 4 attached to the first end 2A of the combustion chamber housing 2, and is then discharged to the outside from the gas discharge port 46. The filter 7 cools the combustion gas of the gas generating agent 62 and collects slag (residue) and the like contained in the combustion gas.

[0029] The filter unit 4 will be described in detail below. FIG. 2 shows the filter unit 4 in detail. 1 is a diagram illustrating a thin structure. The filter unit 4 includes a filter 7 having a columnar outer shape and a filter housing 40 that houses the filter 7. The filter housing 40 is a cylindrical (cup-shaped) member with a bottom that is attached to close the opening (open end) of the first end 2A of the combustion chamber housing 2, and a filter housing space that houses the filter 7 is formed inside (inside) the filter housing 40. The filter 7 is housed inside (in the filter housing space) in a state where it is positioned and fixed coaxially.

[0030] 2, the filter 7 has a cylindrical shape and is formed with a hollow portion 71 penetrating along the axial direction. However, the filter 7 does not have to have a cylindrical shape and may have other shapes. Furthermore, the filter 7 does not have to have a hollow portion 71 and may be a solid filter member.

[0031] In the drawing, reference numeral 72 denotes a first end face (one axial end face) located at one axial end of the filter 7. Reference numeral 73 denotes a second end face (the other axial end face) located at the other axial end of the filter 7. Reference numeral 74 denotes the outer peripheral surface of the filter 7. The filter 7 may be formed from a metal wire. For example, the filter 7 may be produced by placing a flat-braided metal wire in a mold and compressing it into a cylindrical shape. The filter 7 may also be formed by winding a metal wire multiple times around a rod-shaped core material and then pulling out the core material to form a cylindrical shape. Of course, these are merely examples of the filter 7, and the filter 7 is not limited to these.

[0032] 2, the filter housing 40 includes a peripheral wall portion 41, a first constraining end portion 42 disposed on one end of the peripheral wall portion 41, and a second constraining end portion 43 disposed on the other end of the peripheral wall portion 41. In the axial direction of the filter housing 40, the end portion where the first constraining end portion 42 is formed is referred to as the first end 40A, and the end portion where the second constraining end portion 43 is formed is referred to as the second end 40B. The peripheral wall portion 41, the first constraining end portion 42, and the second constraining end portion 43 of the filter housing 40 are integrally formed.

[0033] Here, the first constraining end 42 disposed on one end side (first end 40A side) of the peripheral wall portion 41 of the filter housing 40 is formed as a closed surface. On the other hand, the second constraining end 43 disposed on the other end side (second end 40B side) of the peripheral wall portion 41 is formed as an annular flange disposed so as to surround the periphery of the gas inlet 44. The gas inlet 44 is an opening for allowing the combustion gas of the gas generating agent 62 generated in the combustion chamber housing unit 10 to flow into the filter housing 40 (filter accommodating space). In this embodiment, the gas inlet 44 has a circular cross section and is provided in the form of a single hole whose center is disposed coaxially with the central axis of the filter housing 40.

[0034] The peripheral wall portion 41 is configured to include small diameter portions 411, 412 formed on both one end side and the other end side in the axial direction, and a large diameter portion 413 formed between the small diameter portions 411, 412. More specifically, annular step portions 414, 415 are formed between the small diameter portions 411, 412 and the large diameter portion 413 to connect them.

[0035] The small diameter portions 411, 412 have a relatively smaller outer diameter than the large diameter portion 413, and the large diameter portion 413 has an outer diameter one size larger than the small diameter portions 411, 412. The filter housing 40 is fixed to the combustion chamber housing 2 in this state, with the small diameter portion 412 located on the second end 40B side inserted into the first end 2A (one end) of the combustion chamber housing 2 so that the gas inlet 44 faces the combustion chamber 22. In this manner, by fixing the filter housing 40 (filter unit 4) to the combustion chamber housing 2 with the small diameter portion 412 inserted into the first end 2A of the combustion chamber housing 2, the insertion amount of the small diameter portion 412 into the first end 2A of the combustion chamber housing 2 can be adjusted according to the amount of gas generating agent 62 accommodated in the combustion chamber 22 of the combustion chamber housing unit 10. This makes it possible to adjust the volume of the combustion chamber 22 to an appropriate size according to the amount of gas generating agent 62. Therefore, even when the gas generator 1 is subjected to vibrations or the like after being mounted in an airbag device or the like, the gas generating agent 62 will not move around excessively within the combustion chamber 22, and the generation of abnormal noise caused by this can be suppressed.

[0036] The method for fixing the filter housing 40 to the combustion chamber housing 2 is not particularly limited. For example, the first end 2A of the combustion chamber housing 2 may be welded (e.g., circumferentially welded) to an appropriate position of the filter housing 40 with the small diameter portion 412 inserted into the first end 2A of the combustion chamber housing 2. In this case, the outer diameter of the small diameter portion 412 of the filter housing 40 may be designed to be equal to or slightly smaller than the inner diameter of the first end 2A of the combustion chamber housing 2. Alternatively, the outer diameter of the small diameter portion 412 of the filter housing 40 may be designed slightly larger than the inner diameter of the first end 2A of the combustion chamber housing 2, and the small diameter portion 412 may be press-fitted into the first end 2A via a seal member to fix the filter housing 40 to the combustion chamber housing 2.

[0037] Furthermore, in the filter unit 4 according to the present embodiment, with the small diameter portion 412 of the filter housing 40 inserted into the first end 2A of the combustion chamber housing 2, the annular step portion 415 connecting the small diameter portion 412 and the large diameter portion 413 may abut against the open end surface 2C of the first end 2A of the combustion chamber housing 2. In this aspect, when assembling the filter unit 4 to the combustion chamber housing unit 10, the small diameter portion 412 of the filter housing 40 is inserted into the first end 2A of the combustion chamber housing 2, and the insertion process is completed when the annular step portion 415 abuts against the open end surface 2C. This makes it possible to keep the insertion amount of the small diameter portion 412 of the filter housing 40 into the combustion chamber housing 2 constant when assembling the filter unit 4. As a result, when assembling gas generators of the same specifications, variation in the volume of the combustion chamber 22 from product to product can be suppressed.

[0038] Furthermore, in the filter unit 4 of this embodiment, when the filter 7 is housed in the filter housing 40 (filter housing space), the small diameter portions 411, 412 of the peripheral wall portion 41 abut against the outer peripheral surface 74 of the filter 7. As a result, the small diameter portions 411, 412 of the peripheral wall portion 41 function as a "constraining peripheral wall portion" that restrains the outer peripheral surface 74 of the filter 7 in the cross-sectional direction (radial direction) within the filter housing 40 (filter housing space). This makes it possible to suppress rattling of the filter 7 within the filter housing 40 (filter housing space). For example, the inner diameters of the small diameter portions 411, 412 may be slightly smaller than the outer diameter of the filter 7 (in its original shape) before the filter 7 is housed in the filter housing 40 (filter housing space). By doing so, the filter 7 can be accommodated within the filter housing 40 (filter accommodating space) while being compressed in the cross-sectional direction (radial direction) by the small diameter portions 411, 412, thereby more effectively suppressing rattling of the filter 7.

[0039] As described above, the inner diameter of the large diameter portion 413 of the peripheral wall portion 41 of the filter housing 40 is larger than the outer diameter of the filter 7. Therefore, as shown in Fig. 2, when the filter 7 is housed inside the filter housing 40 (the filter housing space), the inner circumferential surface of the large diameter portion 413 is spaced apart from the outer circumferential surface 74 of the filter 7. Furthermore, as a result, an annular gap 45 is formed between the outer circumferential surface 74 of the filter 7 and the inner circumferential surface of the large diameter portion 413. The central axis of this annular gap 45 is coaxial with the central axis of the filter housing 40, for example.

[0040] Further, the large diameter portion 413 of the peripheral wall portion 41 is provided with a gas outlet 46 for discharging the combustion gas of the gas generating agent 62 to the outside of the filter housing 40. The filter unit 4 in this embodiment receives the combustion gas of the gas generating agent 62 generated in the combustion chamber 22 of the combustion chamber housing unit 10 from a gas inlet 44 arranged facing the combustion chamber 22. The combustion gas is introduced into the hollow portion 71 of the filter 7 housed in the filter housing 40 (filter housing space). The combustion gas introduced into the hollow portion 71 of the filter 7 passes through the filter 7 and the annular gap 45 in that order, and is discharged to the outside from a gas discharge port 46 formed in the large diameter portion 413 of the peripheral wall portion 41. In this embodiment, the gas discharge port 46 is disposed in the large diameter portion 413 that surrounds the periphery of the annular gap 45. This allows the gas discharge port 46 to be directly connected to the annular gap 45, and allows the combustion gas to be smoothly discharged from the gas discharge port 46.

[0041] The large diameter portion 413 of the peripheral wall 41, which is disposed opposite to and spaced apart from the outer peripheral surface 74 of the filter 7, functions as a "non-constraining peripheral wall portion" that does not radially constrain the filter 7. The number, position, size, shape, arrangement pattern, and other aspects of the gas discharge ports 46 provided in the large diameter portion 413 of the peripheral wall 41 are not particularly limited, but in this embodiment, a plurality of gas discharge ports 46 are arranged at predetermined intervals along the circumferential direction of the large diameter portion 413.

[0042] Next, the axial restraint of the filter 7 accommodated in the filter housing 40 will be described. The second restraint end 43 of the filter housing 40 is formed by an annular flange formed by folding an end of the peripheral wall portion 41 toward the filter accommodating space. The inner surface 42A of the first restraint end 42, which is formed as a closed surface, and the inner surface 43A of the second restraint end 43, which is formed as an annular flange, are disposed opposite each other across the filter accommodating space. When the filter 7 is accommodated in the filter housing 40 (filter accommodating space), the inner surface 42A of the first restraint end 42 abuts against a first end face (one axial end face) 72 of the filter 7, and the inner surface 43A of the second restraint end 43 abuts against a second end face (the other axial end face) 73 of the filter 7. In other words, the first restraint end 42 and the second restraint end 43 sandwich the filter 7 from both axial sides of the filter housing 40, thereby restraining the filter 7 in the axial direction.

[0043] As a result, it is possible to suppress axial movement of the filter 7 within the filter housing 40 (filter accommodating space), thereby suppressing rattle of the filter 7. Furthermore, by doing so, it is possible to suitably suppress the occurrence of a phenomenon known as short pass, in which combustion gas that has flowed into the hollow portion 71 of the filter 7 through the gas inlet 44 of the filter housing 40 passes between the first end face 72 and the first constraining end 42 of the filter 7, or between the second end face 73 and the second constraining end 43 of the filter 7, and is discharged from the gas outlet 46 (without passing through the filter 7).

[0044] Here, the distance between the inner surface 42A of the first constraining end 42 and the inner surface 43A of the second constraining end 43 may be slightly smaller than the axial length of the filter 7 before being accommodated in the filter housing 40 (filter accommodation space). This allows the filter 7 to be accommodated in the filter housing 40 (filter accommodation space) while being axially compressed by the first constraining end 42 and the second constraining end 43. As a result, rattle of the filter 7 or the short-passing of the combustion gas described above can be more effectively suppressed. The inner surface 42A of the first constraining end 42 and the first end face (one axial end face) 72 of the filter 7 in the filter housing 40 may be indirectly abutted by a sealant such as a gasket being interposed therebetween. The inner surface 43A of the second constraining end 43 and the second end face (the other axial end face) 73 of the filter 7 may be indirectly abutted by a sealant such as a gasket being interposed therebetween.

[0045] In the filter unit 4 of this embodiment, the diameter of the gas inlet 44 is equal to or smaller than the inner diameter of the filter 7. Here, the inner diameter of the filter 7 refers to the diameter of the hollow portion 71 formed in the filter 7. As a result, as shown in FIG. 2, the second restraint end portion 43, which is an annular flange surrounding the periphery of the gas inlet 44, is positioned so as to be in contact with the filter 7. The second end surface 73 of the filter 7 (the end surface facing the second constraining end portion 43) is entirely covered by the second constraining end portion 43. By entirely covering the second end surface 73 of the filter 7 in this manner, the high-temperature combustion gas with a high flow rate is prevented from directly colliding with the second end surface 73 of the filter 7. This makes it possible to suitably prevent damage to the second end surface 73 of the filter 7.

[0046] Furthermore, when the gas generator 1 is activated, the output of the combustion gas discharged from the gas outlet 46 of the filter unit 4 is limited by the smaller of the total opening area of ​​the gas outlets 46 and the opening area of ​​the gas inlet 44. The total opening area of ​​the gas outlets 46 is the sum of the opening areas of the gas outlets 46 when a plurality of gas outlets 46 are arranged in the large diameter portion 413 of the peripheral wall portion 41 of the filter housing 40. Here, when a plurality of gas outlets 46 are arranged in the large diameter portion 413 of the peripheral wall portion 41, it is thought that, assuming the same processing tolerance per gas outlet 46, the total processing tolerance increases as the number of gas outlets 46 increases. Therefore, when a plurality of gas outlets 46 are arranged in the large diameter portion 413 of the peripheral wall portion 41, it is easier to adjust the output of the gas generator 1 by limiting the rate of the output of the gas generator 1 (i.e., the amount of gas supplied to the airbag device) by the opening area of ​​the gas inlet 44. Therefore, when multiple gas discharge ports 46 are arranged in large diameter portion 413 of peripheral wall portion 41 of filter housing 40, it is preferable to make the total opening area of ​​multiple gas discharge ports 46 larger than the opening area of ​​gas inlet 44. Doing so is advantageous for the stability of the output of gas generator 1, and makes it possible to suppress output variation.

[0047] Next, a description will be given of a method for manufacturing gas generator 1 including the above-described combustion chamber housing unit 10 and filter unit 4. Fig. 3 is a flow chart illustrating the steps of the method for manufacturing gas generator 1. First, in step S01, the above-described filter unit 4 is prepared (filter unit preparation step).

[0048] Fig. 4 is a diagram illustrating the filter unit preparation process. In the filter unit preparation process, a filter housing intermediate 400 is prepared, with one end being an open end 401, as shown in the upper part of Fig. 4, for example. Filter housing intermediate 400 is similar to filter housing 40 described in Fig. 2, except that second constraining end 43 is not folded toward the filter accommodating space. In other words, filter housing intermediate 400 corresponds to filter housing 40 before second constraining end 43 is folded.

[0049] Next, in the filter unit preparation step, the filter 7 is inserted into the filter accommodating space formed inside the filter housing intermediate 400 from the open end 401 side (middle row in FIG. 4 ). For example, the inner diameter of each of the small diameter portions 411, 412 of the peripheral wall 41 of the filter housing intermediate 400 is set to a dimension slightly smaller than the outer diameter of the filter 7 before being accommodated in the filter accommodating space. In this case, when the filter 7 is inserted into the filter accommodating space of the filter housing intermediate 400, the filter 7 is press-fitted into each of the small diameter portions 411, 412 of the peripheral wall 41. As a result, the filter 7 is compressed in the radial direction by the small diameter portions 411, 412 (constraining peripheral wall portions) of the peripheral wall 41, and the radial positioning of the filter 7 is completed. In this state, the filter 7 is coaxially fixed to the filter housing intermediate 400. Furthermore, the large diameter portion 413 (non-constraining peripheral wall portion) of the peripheral wall portion 41 is disposed spaced apart from the outer peripheral surface 74 of the filter 7 so that an annular gap 45 is formed between the outer peripheral surface 74 and the large diameter portion 413 (non-constraining peripheral wall portion).

[0050] Next, the peripheral wall of the filter housing intermediate 400 is folded inward at a specified position P1 near the open end 401. As a result, as shown in the lower part of FIG. 4, the second constraining end 43 is formed as an annular flange, and a gas inlet 44 is formed inside the edge of the second constraining end 43. Here, the folding position (P1) at which the filter housing intermediate 400 is folded inward is set so that the inner surface 42A of the first constraining end 42 and the inner surface 43A of the second constraining end 43 are in contact with the filter 7. The first and second restraining ends 42, 43 are set to abut against the first end surface 72 and the second end surface 73, respectively. This allows the filter 7 to be positioned in the axial direction by the first restraining end portion 42 and the second restraining end portion 43. For example, the dimension from the folding position (P1) of the filter housing intermediate 400 to the first restraining end portion 42 may be set to a dimension slightly smaller than the axial length of the filter 7. This allows the filter 7 to be compressed in the axial direction by the first and second restraining end portions 42, 43.

[0051] In this manner, preparation of the filter unit 4 is completed. In the filter unit preparation process, the first constraining end portion 42 is disposed as a blocking surface at one end of the filter housing 40 to constrain a first end face (one axial end face) 72 of the filter 7, and the second constraining end portion 43 is disposed at the other end of the filter housing 40 so as to surround the periphery of the gas inlet 44 to constrain a second end face (the other axial end face) 73 of the filter 7. In addition, the large diameter portion 413 (non-constraining peripheral wall portion) of the peripheral wall portion 41 of the filter housing 40 is disposed spaced apart from the outer peripheral surface 74 of the filter 7 so as to form an annular gap 45 between the large diameter portion 413 and the outer peripheral surface 74 of the filter 7, and the outer peripheral surface 74 of the filter 7 is constrained by the small diameter portions 411, 412 (constraining peripheral wall portions). When preparing the filter housing intermediate 400 in step S01, it is also possible to prepare a filter housing intermediate 400 that does not have a small diameter portion 412 on the open end 401 side, and then form the small diameter portion 412 after inserting the filter 7 into the filter accommodating space, and then form the second restraining end 43.

[0052] 3, a cylindrical combustion chamber housing unit is prepared in which the combustion chamber 22 for accommodating the gas generating agent 62 is formed (combustion chamber housing unit preparation step). The combustion chamber housing unit referred to here may be, for example, the combustion chamber housing unit 10 before the igniter 3 is attached. Of course, the procedure shown in FIG. 3 is one example, and the order of the filter unit preparation step and the combustion chamber housing unit preparation step is not particularly important, and these orders may be reversed as appropriate.

[0053] Next, in step S03, filter unit 4 is assembled to first end 2A (one end) of combustion chamber housing 2 (assembly step). FIG. 5 is a diagram illustrating the state of the assembly step. In the assembly step, small diameter portion 412 of filter housing 40 in filter unit 4 is inserted into first end 2A of combustion chamber housing 2 until annular step portion 415 of filter housing 40 abuts against open end face 2C of combustion chamber housing 2, and in this state filter housing 40 is fixed to combustion chamber housing 2. Fixing of filter housing 40 to combustion chamber housing 2 may be achieved by welding as described above, or by press-fitting small diameter portion 412 into first end 2A via a seal member. After the assembly step is complete, for example, igniter 3 is assembled to second end 2B of combustion chamber housing 2, thereby completing gas generator 1 described with reference to FIGS. 1 and 2 . The above-described method for manufacturing gas generator 1 is an example, and the steps may be interchanged or other steps may be added as necessary. For example, in the above example, in the combustion chamber housing unit preparation step, a combustion chamber housing unit before the igniter 3 is installed is prepared, the filter unit 4 is assembled to the combustion chamber housing unit, and then the igniter 3 is installed in a subsequent step, but this is not limited to this. In some cases, a combustion chamber housing unit 10 with the igniter 3 already installed may be prepared, and the filter unit 4 may be assembled to the combustion chamber housing unit 10 in the assembly step.

[0054] As described above, the filter unit 4 according to this embodiment is configured as a unit structure in which the filter 7 is accommodated in the filter housing 40 while being positioned and fixed coaxially. The filter unit 4 allows the filter 7 to be fixed to the filter housing 40 while being constrained in both the axial direction and the cross-sectional direction (radial direction). This allows the filter 7 to be secured to the filter housing 40 within the filter housing 40 (filter accommodation space). It can be positioned and fixed without rattle. By uniting filter 7 and filter housing 40 in this way, filter 7 and filter housing 40 will not separate even if subjected to external impact, making handling easier. Therefore, during the manufacturing process of gas generator 1, filter 7 will not fall off filter housing 40, making it easy to handle as a part. It is therefore possible to provide a filter unit 4 that is suitable for manufacturing gas generator 1. Furthermore, because filter 7 can be fixed inside filter housing 40 without rattle, it is possible to suppress the generation of abnormal noise caused by external vibrations.

[0055] Furthermore, in the filter unit 4 according to this embodiment, small diameter portions 411, 412 are arranged as constraining circumferential wall portions on both the first end 40A side and the second end 40B side of the circumferential wall portion 41 of the filter housing 40. This allows the outer peripheral surface 74 of the filter 7 to be positioned and fixed more stably in the cross-sectional direction (radial direction). However, the arrangement of the constraining circumferential wall portions in the filter housing 40 is not limited to this. For example, the small diameter portion 411 (412) may be arranged on only one of the first end 40A side and the second end 40B side of the circumferential wall portion 41, and the other portion of the circumferential wall portion 41 may be the large diameter portion 413.

[0056] In addition, in order to prevent external moisture from entering the combustion chamber 22 when the filter unit 4 of this embodiment is assembled to the combustion chamber housing unit 10, it is preferable that the gas exhaust port 46 or the gas inlet port 44 be hermetically sealed with a sealing member such as sealing tape.

[0057] When closing the gas exhaust port 46 with a sealing member such as sealing tape, if multiple gas exhaust ports 46 are provided in the peripheral wall portion 41, each gas exhaust port 46 must be closed with a sealing member. On the other hand, closing the gas inlet 44 with a sealing member is advantageous in that it is sufficient to close only a single gas inlet 44. Furthermore, when multiple gas exhaust ports 46 are closed with sealing members, differences in the rupture pressure at which the sealing members rupture during operation of the gas generator 1 may occur due to processing tolerances for each gas exhaust port 46, potentially resulting in some gas exhaust ports 46 being open to the outside and others remaining closed. Furthermore, when the gas exhaust port 46 is closed from the outside with a sealing member, there is a risk that the sealing member may be damaged if it comes into contact with something. Considering these points, closing the gas inlet 44 of the filter unit 4 with a sealing member is preferable to closing the gas exhaust port 46 with a sealing member.

[0058] Furthermore, when the gas generating agent 62 accommodated in the combustion chamber 22 of the combustion chamber housing unit 10 is in a solid form such as a pellet shape and the size of each particle is smaller than the opening area of ​​the gas inlet 44, it is preferable to install a movement suppression member at the second restraining end 43 of the filter housing 40 to suppress movement of the gas generating agent 62 from the combustion chamber 22 side into the filter housing 40 (filter accommodating space). An example of such a movement suppression member is a porous member having a large number of holes.

[0059] Here, when both a sealing member (e.g., sealing tape) for closing the gas inlet 44 of the filter unit 4 and a porous member for suppressing the intrusion of the gas generating agent 62 into the filter housing 40 (filter accommodating space) from the combustion chamber 22 side are attached to the second restraining end 43, if the porous member comes into contact with the sealing member, this may affect the rupture pressure of the sealing member. Therefore, in such a case, it is preferable to arrange the sealing member and the porous member apart from each other.

[0060] 6 is a diagram illustrating an example of the installation of a sealing member and a porous member installed at the second restraining end 43 of the filter housing 40. In the installation example shown in the upper part of FIG. 6, a sealing tape 8 as a sealing member is attached to the outer surface 43B of the second restraining end 43 inside the filter housing 40. In addition, an annular spacer 9A, for example, is attached to the outer surface 43B of the second restraining end 43, and a porous member 9B is attached to the spacer 9A. In this installation example, by interposing the spacer 9A between the outer surface 43B of the second restraining end 43 and the porous member 9B, the porous member 9B and the sealing tape 8 are spaced apart from each other, preventing them from coming into contact with each other.

[0061] 6, a shallow cup-shaped porous member 9C is attached to the outer surface 43B of the second restraining end 43. The porous member 9C has a spacer portion 9D, and by attaching the spacer portion 9D to the outer surface 43B of the second restraining end 43, the porous member 9C and the sealing tape 8 are spaced apart from each other.

[0062] Although the embodiments of the present disclosure have been described above, each aspect disclosed in this specification can be combined with any other feature disclosed in this specification. [Explanation of symbols]

[0063] 1: Gas generator 2: Combustion chamber housing 3:Igniter 5: Bulkhead 6: Gas generator 7: Filter 10: Combustion chamber housing unit 40: Filter housing 41: Peripheral wall part 42: 1st restraint end 43:Second restraint end 44: Gas inlet 45: Gap 46: Gas outlet

Claims

1. A cylindrical combustion chamber housing having an open end and a combustion chamber formed inside which a gas generating agent is contained, A filter unit is assembled to one end of the combustion chamber housing so as to close the opening at that end, Equipped with, The aforementioned filter unit is A filter having a columnar shape, A filter housing that houses the filter in a filter housing space formed on the inside, with the filter positioned and fixed coaxially, Equipped with, The filter housing has two restraining ends that restrain one axial end face and the other axial end face of the filter, respectively, and a peripheral wall portion that connects the two restraining ends and has a gas outlet. The peripheral wall portion includes a small-diameter portion that is connected to one of the two restraining ends and restrains the circumferential surface of the filter, and a large-diameter portion that has a larger outer diameter than the small-diameter portion and where the gas outlet is located. The small-diameter portion is inserted into one end of the combustion chamber housing so as to be adjustable in its insertion amount. Gas generator.

2. The small-diameter portion of the filter housing is inserted into the combustion chamber housing at an adjustable depth relative to one end of the combustion chamber housing, depending on the amount of gas generating agent contained in the combustion chamber. The gas generator according to claim 1.

3. The filter housing has an annular stepped portion formed between the small diameter portion and the large diameter portion, The annular stepped portion is in contact with the open end surface of one end of the combustion chamber housing. A gas generator according to claim 1 or 2.

4. The two restraining ends are a first restraining end which is positioned as a closing surface at one end of the filter housing and restrains one axial end surface of the filter, and the other end of the filter housing This is a second restraining end that is positioned at the end to surround the gas inlet and restrains the other end face of the filter in the axial direction. The second restraining end is formed as an annular flange surrounding the gas inlet from the combustion chamber housing to the filter housing, and is positioned so that the gas inlet faces the combustion chamber. A gas generator according to any one of claims 1 to 3.

5. The small diameter portion is formed on both one end and the other end of the peripheral wall portion in the axial direction, and the large diameter portion is formed between the pair of small diameter portions. The filter is housed in the filter housing space in a state in which the filter is compressed radially by a pair of small-diameter portions that abut the circumferential surface of the filter. A gas generator according to any one of claims 1 to 4.

6. The inner surface of the first restraining end and the inner surface of the second restraining end are arranged opposite each other with the filter housing space in between, The first and second restraining ends sandwich the axial end face of the filter from both sides, thereby restraining the filter in a state of axial compression. The gas generator according to claim 4.

7. The filter has a cylindrical shape in which a hollow portion is formed along the axial direction, The second restraining end covers the entire end face of the filter. The gas generator according to claim 4 or 6.

8. The diameter of the gas inlet is equal to the inner diameter of the filter, or smaller than the inner diameter of the filter. The gas generator according to claim 7.

9. The gas outlets are formed in a plurality in the peripheral wall, and the total opening area of ​​the plurality of gas outlets is larger than the opening area of ​​the gas inlet. The gas generator according to claim 4.

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