Gas generator

Abstract

To provide a gas generator that makes a joint portion between a housing and a bolt less likely to be damaged when an external force is applied, while achieving a reduction weight.SOLUTION: A gas generator 1 includes: a housing having a cylindrical portion 10; a bolt 2; and a joint portion 6. The bolt 2 has a rod-like portion 3 and is joined to an outer peripheral surface 10a of the cylindrical portion 10. The joining portion 6 joins the cylindrical portion 10 and the bolt 2 to each other by allowing at least one of the outer peripheral surface 10a and an axial end part 4 of the rod-shaped portion 3 to be melted and then solidified. The rod-like portion 3 includes a male screw portion 3a. A plate thickness of the cylindrical portion 10 is less than 1.3 mm. The gas generator 1 satisfies L>(A×S1) / (t×S2×G), wherein L is a peripheral length of an outer edge of a boundary portion between the joining portion 6 and the outer peripheral surface 10a, A is an effective cross-sectional area of the male screw portion 3a, S1 is a bolt strength of the bolt 2, t is the plate thickness of the cylindrical part 10, S2 is a tensile strength of the cylindrical portion 10, and G is a shearing coefficient of the cylindrical portion 10.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a gas generator incorporated in an occupant protection device for protecting an occupant in the event of a vehicle collision, and more particularly to a gas generator incorporated in an airbag device mounted on an automobile or the like. [Background technology]

[0002] Conventionally, airbag devices, which are passenger protection devices, have become widespread from the viewpoint of protecting passengers in automobiles, etc. Airbag devices are installed for the purpose of protecting passengers from impacts that occur when a vehicle or the like crashes, and the airbag instantly inflates and deploys when a vehicle or the like crashes, so that the airbag acts as a cushion to receive the body of the passenger.

[0003] The gas generator is a device incorporated into the airbag device. When a vehicle crashes, the control unit supplies electricity to ignite an igniter, which then produces a flame that burns a gas generating agent, instantly generating a large amount of gas, thereby inflating and deploying the airbag.

[0004] There are gas generators with various configurations based on the specifications such as the installation position relative to the vehicle, output, etc., one of which is called a cylinder-type gas generator. The cylinder-type gas generator has a long cylindrical outer shape and is suitably incorporated into a side airbag device, a curtain airbag device, a knee airbag device, a seat cushion airbag device, etc.

[0005] Stud bolts for mounting to a retainer of an airbag device or the like may be provided on the outer peripheral surface of the housing of a cylindrical gas generator. Japanese Patent Application Laid-Open No. 2005-247289 (Patent Document 1) discloses a technique for welding and mounting a stud bolt to the outer peripheral surface of a flat-machined gas generator housing. Japanese Patent Application Laid-Open No. 2005-313752 (Patent Document 2) discloses a technique for welding and mounting the head of a headed bolt, which is formed with a curved surface, to the curved outer peripheral surface of the gas generator. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2005-247289 A [Patent Document 2] JP 2005-313752 A Summary of the Invention [Problem to be solved by the invention]

[0007] Here, in order to realize safe operation of the gas generator, it is essential to prevent deformation, damage, etc. from occurring at the joint formed by welding the housing and the stud bolt even when some unintended external force is applied to the gas generator or the retainer, etc. This issue becomes particularly prominent when the plate thickness of the housing is reduced to meet the recent need for lighter gas generators.

[0008] Therefore, the present invention has been made to solve the above-mentioned problems, and has an object to provide a gas generator that is lightweight and in which damage is less likely to occur at the joint between the housing and the bolt when some external force is applied. [Means for solving the problem]

[0009] A gas generator according to the present invention ejects gas toward the outside, and includes a housing having a cylindrical portion, a bolt, and a joint portion. The bolt has a rod-shaped portion and is joined to a curved outer circumferential surface of the cylindrical portion. The joint portion joins the cylindrical portion and the bolt to each other by melting at least one of the outer circumferential surface of the cylindrical portion and an axial end portion of the rod-shaped portion on the cylindrical portion side and then solidifying. The rod-shaped portion includes a male thread portion formed by providing a spiral groove on the circumferential surface of the rod-shaped portion. The plate thickness of the cylindrical portion is less than 1.3 mm. In the gas generator according to the present invention, the gas generator satisfies the following formula (1) when the circumferential length of an outer edge of a boundary portion between the joint portion and the outer circumferential surface of the cylindrical portion is L, the effective cross-sectional area of ​​the male thread portion is A, the bolt strength of the bolt is S1, the plate thickness of the cylindrical portion is t, the tensile strength of the cylindrical portion is S2, and the shear coefficient of the cylindrical portion is G. L>(A × S1) / (t × S2 × G) (1) Effect of the Invention

[0010] According to the present invention, it is possible to provide a gas generator which is lightweight and in which damage is unlikely to occur at the joint between the housing and the bolt when some external force is applied. [Brief description of the drawings]

[0011] [Figure 1] 1 is a schematic diagram of a cylinder-shaped gas generator according to an embodiment. [Diagram 2] 2A to 2C are a perspective view, a side view, and a bottom view of the bolt shown in FIG. 1 before welding. [Diagram 3] 3 is a schematic diagram showing how the bolt shown in FIG. 2 is attached to a housing. FIG. [Figure 4] FIG. 2 is a side view of the cylinder-shaped gas generator shown in FIG. [Diagram 5] FIG. 5 is an enlarged cross-sectional view of a main portion in the vicinity of the joint shown in FIG. [Figure 6] 1 is a graph showing the measurement results of verification test 1. [Figure 7] 13 is a graph showing the measurement results of verification test 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The embodiment shown below illustrates a case where the present invention is applied to a cylinder-type gas generator incorporated in a side airbag device. In the embodiment shown below, the same or common parts are given the same reference numerals in the drawings, and the description thereof will not be repeated.

[0013] (Embodiment) Fig. 1 is a schematic diagram of a cylinder-shaped gas generator according to an embodiment. First, with reference to Fig. 1, the configuration of cylinder-shaped gas generator 1 according to the present embodiment will be described. Note that arrows DR1 and DR2 shown in Fig. 1 indicate the axial direction of housing body 10 and the axial direction of bolt 2 constituting cylinder-shaped gas generator 1, respectively (the same applies to Figs. 2 to 5 described later).

[0014] As shown in FIG. 1, cylinder-shaped gas generator 1 comprises a housing 90 having a long, generally cylindrical outer shape with one axial end and the other end closed, and two bolts 2 joined via joints 6 (see FIG. 5, etc., described later) to curved outer circumferential surface 10a of housing body 10, which serves as a cylindrical portion constituting housing 90.

[0015] A retainer of an airbag device or the like is attached to the bolt 2. For example, a bolt made of cold heading carbon steel (SWCH) or the like is used as the bolt 2. The number of bolts 2 is not particularly limited to two, and may be one, or three or more.

[0016] The housing 90 has a housing main body 10, a holder 20, and a blocking member 30. Inside the housing 90 constituted by the housing main body 10 and the like, an igniter 40, a partition member 50, a storage chamber defining member 60, a gas generating agent 70, a filter 80, and the like are accommodated as internal components. Inside the housing 90, there are positioned a combustion chamber R1 in which the gas generating agent 70, one of the above-mentioned internal components, is mainly arranged, and a filter chamber R2 in which the filter 80 is arranged.

[0017] The housing body 10 constitutes the peripheral wall of the housing 90. The housing body 10 is made of a long, substantially cylindrical member with openings formed at both ends in the axial direction (see arrow DR1). Materials that constitute the housing body 10 include, for example, general structural carbon steel pipes (STK) and mechanical structural carbon steel pipes (STKM). The outer diameter of the housing body 10 is preferably, for example, 15 mm or more and 40 mm or less.

[0018] Furthermore, the plate thickness of housing body 10 is preferably less than 1.3 mm, for example, more preferably less than 1.1 mm, and even more preferably less than 0.9 mm. This enables the weight of cylinder-shaped gas generator 1 to be reduced. Furthermore, the plate thickness of housing body 10 is preferably greater than 0.5 mm, for example.

[0019] The holder 20 is fixed to the housing body 10 so as to close one end of the housing 90 in the axial direction. The closing member 30 is fixed to the housing body 10 so as to close the other end of the housing 90 in the axial direction of the housing body 10.

[0020] The igniter 40 is for burning the gas generating agent 70, and is attached to one end of the housing 90 by being supported by the holder 20. As a result, the igniter 40 is disposed so as to face the internal space of the housing 90.

[0021] A partition member 50 serving as a partition is disposed at a predetermined position in the space inside the housing 90. This divides the space inside the housing 90 in the axial direction of the housing body 10 into a combustion chamber R1 and a filter chamber R2.

[0022] Within the space inside the housing 90, a storage chamber defining member 60 and a gas generating agent 70 are disposed in a space sandwiched between the holder 20 and the partition member 50 (that is, a combustion chamber R1).

[0023] The storage chamber defining member 60 is a member that defines the gas generating agent storage chamber R1A in which the gas generating agent 70 is stored. The storage chamber defining member 60 is made of a relatively fragile member so that it will burst or melt as the gas generating agent 70 burns.

[0024] The gas generating agent 70 is an agent that generates gas by being ignited by thermal particles generated by the activation of the igniter 40 and burning. As the gas generating agent 70, it is preferable to use a non-azide gas generating agent, and the gas generating agent 70 is generally formed as a molded body containing a fuel, an oxidizer, and an additive.

[0025] Of the spaces inside the housing 90, a filter 80 is disposed in a space (i.e., a filter chamber R2) sandwiched between the blocking member 30 and the partition member 50. The filter 80 functions as a cooling means for cooling the gas by removing high-temperature heat contained in the gas generated by the combustion of the gas generating agent 70 when the gas passes through the filter 80, and also functions as a removal means for removing residue (slag) and the like contained in the gas.

[0026] A plurality of gas outlets 31 are provided in the portion of the housing body 10 that defines the filter chamber R2 along the circumferential and axial directions of the housing body 10. These gas outlets 31 are for directing the gas that has passed through the filter 80 to the outside of the housing 90.

[0027] Figures 2(A), 2(B) and 2(C) are respectively a perspective view, a side view and a bottom view showing the state before welding of the bolt shown in Figure 1. Next, with reference to Figure 2, the configuration of bolt 2 in this embodiment in the state before welding will be described.

[0028] As shown in Fig. 2(A), Fig. 2(B) and Fig. 2(C), in a state before welding, the bolt 2 has a solid, substantially cylindrical rod-shaped portion 3 extending along its axial direction (see arrow DR2) and a flange portion 4 as an axial end portion provided at one end of the rod-shaped portion 3 in the axial direction of the bolt 2. When viewed along the axial direction of the bolt 2, the flange portion 4 has a track shape. Here, the track shape means that the outer edge of the flange portion 4 is a rounded rectangular shape consisting of two straight line portions located parallel to each other and two curved portions located parallel to each other. The shape of the flange portion 4 is not particularly limited to the track shape, and may be a substantially circular shape, a substantially elliptical shape, a substantially rectangular shape, or the like.

[0029] The rod-shaped portion 3 includes a male thread portion 3a formed by providing a helical groove 3a1 (see FIG. 5 described later) on its circumferential surface. The flange portion 4 has an opposing surface 8. The opposing surface 8 is a surface that faces the outer circumferential surface 10a of the housing body 10 when the bolt 2 is welded to the outer circumferential surface 10a.

[0030] FIG. 3 is a schematic diagram showing how the bolt shown in FIG. 2 is attached to the housing. FIG. 4 is a side view of the cylinder-shaped gas generator as viewed from the direction of arrow IV in FIG. 1. FIG. 5 is an enlarged cross-sectional view of a main part in the vicinity of the joint shown in FIG. 4. FIG. 5(A) is an enlarged cross-sectional view of a main part in the vicinity of the joint taken along line VA-VA shown in FIG. 4, and FIG. 5(B) is an enlarged cross-sectional view of a main part in the vicinity of the joint taken along line VB-VB shown in FIG. 4. Next, with reference to these FIGS. 3 to 5, a method of attaching bolt 2 to housing body 10 in this embodiment and a configuration in the vicinity of joint 6 in cylinder-shaped gas generator 1 according to this embodiment will be described. Note that in FIG. 3, housing body 10 is illustrated in cross section. Also, in order to facilitate understanding, a pattern is added to joint 6 in FIG. 4.

[0031] When attaching the bolt 2 to the curved outer peripheral surface 10a of the housing body 10, first, a voltage is applied to the bolt 2 and the housing body 10, which are arranged facing each other at a distance, as shown in Fig. 3. Next, while maintaining the state in which the voltage is applied to the bolt 2 and the housing body 10, the bolt 2 is moved in the direction of the arrow AR1 in Fig. 3, whereby the flange portion 4 of the bolt 2 is pressed against the outer peripheral surface 10a of the housing body 10.

[0032] At that time, discharge occurs between the flange portion 4 and the outer peripheral surface 10a, causing these portions to be locally heated. This heating causes a part of the flange portion 4 and a part of the outer peripheral surface 10a of the housing body 10 to melt and begin to melt. Hereinafter, the melted portion of the flange portion 4 and the outer peripheral surface 10a of the housing body 10 will be collectively referred to as the molten portion.

[0033] As the bolt 2 is further pressed against the housing body 10, the molten portion is sandwiched between the unmelted portion of the flange portion 4 and the unmelted portion of the outer peripheral surface 10a of the housing body 10. As a result, the molten portion is stretched along the curved outer peripheral surface 10a of the housing body 10.

[0034] Thereafter, the molten portion solidifies, forming a joint portion 6 between the bolt 2 and the housing body 10, as shown in Figures 4, 5(A) and 5(B). As a result, the bolt 2 is joined to the outer peripheral surface 10a of the housing body 10 via the joint portion 6.

[0035] Here, cylinder-shaped gas generator 1 according to the present embodiment is configured to satisfy formula (1) described below in order to make joint portion 6 between housing body 10 and bolt 2 less susceptible to damage when some kind of external force is applied to gas generator 1, etc. This point will be described in detail below.

[0036] When assembling the cylinder-type gas generator to a retainer or the like, or when a vehicle equipped with the cylinder-type gas generator collides, an unintended external force may be applied to the cylinder-type gas generator. If no measures are taken against this, there is a concern that the external force may be applied to the joint between the bolt and the housing body, causing deformation or damage to the joint. If this deformation or damage occurs to the joint, there is a risk that the planned operation will not be achieved during operation of the cylinder-type gas generator, resulting in malfunction.

[0037] Therefore, if bolt 2 can be caused to break before an excessive external force is applied to joint 6, it can prevent damage or deformation from occurring in joint 6, in the unlikely event that such damage occurs. As a result, safe operation of cylinder-type gas generator 1 can be achieved.

[0038] There are three possible fracture modes of the joint 6: fracture in the tensile direction, fracture in the shear direction, and fracture in the torque direction. Of these, it is unrealistic for fracture in the torque direction to occur. Also, generally, the tensile strength tends to be greater than the shear strength. Therefore, if fracture in the tensile direction of the joint 6 is suppressed, fracture in the shear direction will also be suppressed accordingly. Therefore, in the cylinder-shaped gas generator 1, it is important to prevent fracture in the tensile direction of the joint 6.

[0039] In other words, in cylinder-shaped gas generator 1 , the weld strength at joint 6 is required to be greater than the tensile strength of bolt 2 .

[0040] Here, assuming that the effective cross-sectional area of ​​the male thread portion 3a is A, the bolt strength of the bolt 2 is S1, the circumferential length of the outer edge 6a (see Figs. 4 and 5) of the boundary between the joint portion 6 and the outer circumferential surface 10a of the housing body 10 is L, the plate thickness of the housing body 10 is t, the tensile strength of the housing body 10 is S2, and the shear coefficient of the housing body 10 is G, the tensile strength T1 of the bolt 2 is expressed by the following formula (11), and the weld strength T2 at the joint portion 6 is expressed by the following formula (12). The validity of formulas (11) and (12) has been confirmed by verification tests 1 and 2 described below. T1 = A × S1 (11) T2 = L × t × S2 × G (12)

[0041] The effective cross-sectional area A of the male thread portion 3a is expressed by the following formula (13). Note that d2 indicates the effective diameter of the male thread portion 3a, and d3 indicates the root diameter of the male thread portion 3a. As shown in FIG. 5(A), the effective diameter d2 is the diameter of an imaginary cylinder in which the width dimension of the helical groove 3a1 and the width dimension of the thread of the male thread portion 3a that is provided to be paired with the helical groove 3a1 are both P / 2, when the pitch of the male thread portion 3a is dimension P. Also, the root diameter d3 is the diameter of an imaginary cylinder that is in contact with the root of the helical groove 3a1. A = (π / 4) × ((d2 + d3) / 2) 2 (13)

[0042] Cylinder-shaped gas generator 1 according to the present embodiment satisfies the following equation (1), which is obtained by establishing the inequality T2>T1 between the tensile strength T1 of bolt 2 expressed by the above equation (11) and the weld strength T2 at joint 6 expressed by the above equation (12). L>(A × S1) / (t × S2 × G) (1)

[0043] That is, in the cylinder-shaped gas generator 1 of this embodiment, the circumferential length L of the outer edge 6a of the boundary between the joint 6 and the outer peripheral surface 10a of the housing body 10 is configured so as to satisfy the above formula (1).

[0044] In this way, by configuring the circumferential length L to be considerably long so as to satisfy the above formula (1), when a tensile load is applied to the bolt 2 and the joint 6, the bolt 2 breaks before an excessive external force is applied to the joint 6. Therefore, even in the unlikely event that damage or deformation occurs to the joint 6, this can be prevented in advance.

[0045] Therefore, by making the cylinder-shaped gas generator 1 according to the present embodiment, it is possible to achieve a gas generator that is lightweight and is less susceptible to damage at the joint between the housing and the bolt when some external force is applied.

[0046] Furthermore, in cylinder-shaped gas generator 1 of this embodiment, the orientation of bolt 2 is adjusted so that when bolt 2 is joined to outer peripheral surface 10a of housing body 10, the longitudinal direction of flange portion 4 coincides with the axial direction of housing body 10.

[0047] More specifically, as shown in FIG. 4, when viewed along the axial direction of the rod-shaped portion 3, the bolt 2 is joined to the outer peripheral surface 10a of the housing body 10 so that the outer dimension of the flange portion 4 in a direction parallel to the axial direction of the housing body 10 (see arrow DR1) is larger than the outer dimension of the flange portion 4 in a direction perpendicular to the axial direction.

[0048] With this configuration, even if the flange portion 4 is made flat without being given a special shape, it is possible to ensure a long circumferential length L while reducing the gap between the outer circumferential surface 10a of the housing body 10 and the flange portion 4. Therefore, with this configuration, it is possible to prevent the joint portion 6 from being damaged or deformed.

[0049] (Verification test 1) In the verification test 1, the validity of the formula (11) was confirmed by comparing the actual measured tensile strength of the bolt sample prepared for the verification test 1 with the theoretical value calculated by the formula (11) representing the tensile strength T1 of the bolt described above.

[0050] In this verification test, ten bolts each of Sample 1, which is a bolt with a bolt strength of 667 MPa, and Sample 2, which is a bolt with a bolt strength of 776.25 MPa, were prepared. The material of both Sample 1 and Sample 2 was cold heading carbon steel (SWCH18A), and the effective cross-sectional area of ​​both Sample 1 and Sample 2 was 20.1 cm 2 It is.

[0051] In the verification, first, each sample was attached to the housing body. The attachment method was the same as that described in the above embodiment. The material of the housing body used here was carbon steel pipe for machine construction (STKM13C).

[0052] Next, a tensile test was carried out on the sample and the housing body joined together via the joint, and the tensile strength of the sample was measured when the sample broke.

[0053] Fig. 6 is a graph showing the measurement results of Verification Test 1. The horizontal axis indicates bolt strength (MPa), and the vertical axis indicates bolt tensile strength T1 (kN). In Fig. 6, the theoretical value calculated by formula (11) is indicated by a dashed line. The standard deviation of the measured values ​​of the ten samples 1 was 0.049 kN, and the standard deviation of the measured values ​​of the ten samples 2 was 0.154 kN.

[0054] From the graph of this verification test shown in Figure 6, it was confirmed that the difference between the theoretical values ​​and the measured values ​​was considerably small. From the above, it was confirmed that the formula (11) showing the tensile strength T1 of the bolt is valid.

[0055] (Verification test 2) In verification test 2, the validity of formula (12) was confirmed by comparing the actual measured value of the weld strength at the joint for attaching the bolt to the housing body with the theoretical value calculated by formula (12) which represents the weld strength T2 at the above-mentioned joint.

[0056] In this verification test, in order to break the joint in the tensile direction, a bolt with a high bolt strength that would not cause the bolt to break before the joint was prepared and attached to the housing body. The material of the housing body used here is carbon steel pipe for machine construction (STKM13C), and the plate thickness of the housing body is 1.0 mm.

[0057] Next, the circumference of the joint (more specifically, the circumference of the outer edge of the boundary between the joint and the outer periphery of the housing body) was measured. Next, a tensile test was conducted on the bolt and the housing body joined together via the joint, and the weld strength of the joint was measured when fracture occurred. This verification test was conducted a total of three times by changing the circumference of the joint.

[0058] 7 is a graph showing the measurement results of verification test 2. The horizontal axis indicates the circumference (mm) of the joint, and the vertical axis indicates the weld strength T2 (kN) of the joint.

[0059] From the graph of this verification test shown in Figure 7, it was confirmed that the difference between the theoretical values ​​and the measured values ​​was considerably small. From the above, it was confirmed that the formula (12) expressing the weld strength T2 at the joint is valid.

[0060] (Additional Note) The characteristic configurations of the gas generators disclosed in the above-described embodiments can be summarized as follows.

[0061] [Appendix 1] A gas generator that ejects gas to the outside, a housing having a cylindrical portion; A bolt having a rod-shaped portion and joined to the curved outer peripheral surface of the cylindrical portion; a joint portion that joins the cylindrical portion and the bolt to each other by melting and then solidifying at least one of the outer circumferential surface of the cylindrical portion and the axial end portion of the rod-shaped portion on the cylindrical portion side, The rod-shaped portion includes a male screw portion formed by providing a spiral groove on a circumferential surface of the rod-shaped portion, The cylindrical portion has a thickness of less than 1.3 mm; A gas generator which satisfies the following formula (1), where L is the circumference of the outer edge of the boundary between the joint and the outer circumferential surface of the cylindrical portion, A is the effective cross-sectional area of ​​the male thread portion, S1 is the bolt strength of the bolt, S2 is the tensile strength of the cylindrical portion, t is the plate thickness of the cylindrical portion, and G is the shear coefficient of the cylindrical portion. L>(A × S1) / (t × S2 × G) (1)

[0062] [Appendix 2] 2. The gas generator described in appendix 1, wherein, when viewed along the axial direction of the rod-shaped portion, an outer dimension of the axial end portion in a direction parallel to the axial direction of the cylindrical portion is larger than an outer dimension of the axial end portion in a direction perpendicular to the axial direction of the cylindrical portion.

[0063] [Appendix 3] 3. The gas generator according to claim 2, wherein the axial end portion is constituted by a flange portion.

[0064] [Appendix 4] 4. The gas generator according to claim 3, wherein the flange portion has a track shape when viewed along the axial direction of the rod-shaped portion.

[0065] [Appendix 5] 5. A gas generator according to any one of claims 1 to 4, wherein the plate thickness of the cylindrical portion is less than 1.1 mm.

[0066] (Other forms, etc.) The shape, configuration, size, number, material, and the like of each part shown in the above-mentioned embodiment of the present invention can be modified in various ways without departing from the spirit of the present invention.

[0067] Furthermore, the characteristic configurations shown in the above-mentioned embodiments of the present invention can naturally be combined with each other without departing from the spirit of the present invention.

[0068] As such, the above-described embodiments disclosed herein are illustrative in all respects and are not restrictive. The technical scope of the present invention is defined by the claims, and includes all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0069] 1 cylinder-type gas generator, 2 bolt, 3 rod-shaped portion, 3a male thread portion, 3a1 spiral groove, 4 flange portion, 6 joint portion, 6a outer edge, 8 opposing surface, 10 housing body, 10a outer peripheral surface, 20 holder, 30 blocking member, 31 gas outlet, 40 igniter, 50 partition member, 60 storage chamber defining member, 70 gas generating agent, 80 filter, 90 housing, R1 combustion chamber, R1A gas generating agent storage chamber, R2 filter chamber.

Claims

1. A gas generator that ejects gas to the outside, a housing having a cylindrical portion; A bolt having a rod-shaped portion and joined to the curved outer peripheral surface of the cylindrical portion; a joint portion that joins the cylindrical portion and the bolt to each other by melting and then solidifying at least one of the outer circumferential surface of the cylindrical portion and the axial end portion of the rod-shaped portion on the cylindrical portion side, The rod-shaped portion includes a male screw portion formed by providing a spiral groove on a circumferential surface of the rod-shaped portion, The cylindrical portion has a plate thickness of less than 1.3 mm; a circumferential length of an outer edge of a boundary between the joint portion and the outer circumferential surface of the cylindrical portion is L, an effective cross-sectional area of ​​the male thread portion is A, a bolt strength of the bolt is S1, a tensile strength of the cylindrical portion is S2, the plate thickness of the cylindrical portion is t, and a shear coefficient of the cylindrical portion is G, which satisfies the following formula (1): L>(A×S1) / (t×S2×G)...(1)

2. 2. The gas generator according to claim 1, wherein, when viewed along the axial direction of the rod-shaped portion, an outer dimension of the axial end portion in a direction parallel to the axial direction of the cylindrical portion is larger than an outer dimension of the axial end portion in a direction perpendicular to the axial direction of the cylindrical portion.

3. 3. The gas generator according to claim 2, wherein the axial end portion is constituted by a flange portion.

4. 4. The gas generator according to claim 3, wherein the flange portion has a track shape when viewed along the axial direction of the rod-shaped portion.

5. 2. The gas generator according to claim 1, wherein the wall thickness of the cylindrical portion is less than 1.1 mm.

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