Gas producer and gas discharge method of gas producer

Abstract

To provide technique which is capable of reducing amount of combustion residue which is discharged to outside of a gas producer.SOLUTION: A gas producer comprises an igniter, a gas generating agent which generates fuel gas by burning by actuation of the igniter, a housing which accommodates the igniter and the gas generating agent inside, a gas discharge hole which penetrates inside and outside of the housing and a seal made of a metal which is formed in sheet-like shape and is attached to internal surface of the housing and blocks the gas discharge hole by covering an opening of inner surface side of the housing in the gas discharge hole before actuation of the igniter and opens the gas discharge hole by cracking by receiving pressure of combustion gas generating by the actuation of the igniter. The gas discharge hole includes chamfering area on which a corner part of the opening of the inner surface side of the housing is removed over whole circumference.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a gas generator and a method for discharging gas in a gas generator. [Background technology]

[0002] Conventionally, a gas generator has been widely used in which an igniter and a gas generating agent are placed inside a housing, the gas generating agent is burned by activating the igniter, and the combustion gas is discharged to the outside from one or more gas exhaust holes formed in the housing.

[0003] The gas generator is configured such that the inside of the housing is kept airtight before activation by blocking the gas exhaust port with a blocking member such as a sealing tape, and upon activation, the blocking member is cleaved by the pressure of the combustion gas to open the gas exhaust hole. In this regard, a technique is known for blocking the gas exhaust hole with a moisture-proof sealing tape that can prevent the gas generating agent from absorbing moisture (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-217899 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, the combustion gas generated in the housing and reaching the gas exhaust hole may contain residues (combustion residues) produced by combustion. In a gas generator, it is desired to prevent the combustion residues from being discharged to the outside of the gas generator as much as possible.

[0006] The technique of the present disclosure aims to reduce the amount of combustion residue discharged to the outside of a gas generator. [Means for solving the problem]

[0007] In order to solve the above problems, the technology of the present disclosure employs the following configuration. That is, the gist of the technology according to the present disclosure is as follows.

[0008] [1] The technology disclosed herein is An igniter, A gas generating agent that generates a combustion gas by burning in response to activation of the igniter; a housing that accommodates the igniter and the gas generating agent therein; a gas exhaust hole penetrating the inside and outside of the housing; a metal seal formed in a sheet shape and attached to the inner surface of the housing, the metal seal covering an opening of the gas discharge hole on the inner surface side of the housing before activation of the igniter to close the gas discharge hole, and cleaving under pressure of the combustion gas generated by activation of the igniter to open the gas discharge hole, The gas exhaust hole has a chamfered area in which a corner of an opening on an inner surface side of the housing is removed over an entire periphery. It is a gas generator. [2] In the gas generator according to [1], The chamfered area is an opening on the inner surface side of the housing in the thickness direction of the housing. The diameter may be tapered away from the portion. [3] In the gas generator according to [1] or [2], The inner wall surface of the chamfered region may be formed in a straight or curved shape in a cross section along the thickness direction of the housing. [4] In the gas generator according to any one of [1] to [3], The gas discharge hole may have a straight region that is continuous with the chamfered region and extends with a constant inner diameter. [5] In the gas generator according to any one of [1] to [4], The seal includes an aluminum base layer and an adhesive layer provided on one surface of the base layer and adhered to an inner surface of the housing, The thickness of the base layer may be 50 μm or more and 200 μm or less. [6] In the gas generator described in [5], the seal may have a tensile strength measured in accordance with JIS Z0237 of 100 [N] / 20 [mm] or more and 200 [N] / 20 [mm] or less. [7] In the gas generator described in [5] or [6], the seal may further include an adhesive layer provided on the other surface of the base material layer and having adhesive properties. [8] In the gas generator according to any one of [1] to [7], The seal may be configured such that at least a portion of the seal remains within the gas exhaust hole when the seal is ruptured. [9] In the gas generator according to any one of [1] to [8], The seal may be configured so that, when the seal is cleaved, a minimum flow path cross-sectional area of ​​a flow path of the combustion gas formed in the gas discharge hole becomes smaller than a minimum cross-sectional area of ​​the gas discharge hole.

[10] The technology disclosed herein is preparing a housing for a gas generator, the housing containing an igniter and a gas generating agent that generates a combustion gas by burning when the igniter is activated, the housing having a gas discharge hole penetrating the inside and outside of the housing, the gas discharge hole having a chamfered region in which a corner of an opening on an inner surface side of the housing is removed over an entire circumference; a step of attaching a sheet-shaped metal seal to an inner surface of the housing to cover an opening of the gas exhaust hole on the inner surface side of the housing, thereby closing the gas exhaust hole; assembling the gas generator; activating the igniter; and pressing the seal against an inner wall surface of the chamfered region by a pressure of the combustion gas generated by activation of the igniter, and tearing an area of ​​the seal that is on the inside of an abutment area that abuts against the inner wall surface of the chamfered region, thereby tearing the seal so that at least a portion of the seal remains in the gas discharge hole. A method for discharging gas from a gas generator.

[11] In the gas discharge method according to

[10] , In the step of preparing the housing, the chamfered region is formed into the gas exhaust region so that the diameter of the chamfered region decreases with increasing distance from the opening on the inner surface side of the housing in a thickness direction of the housing. Formed in the exit hole, The step of tearing the seal may include bending and tearing the seal so that the seal follows an inner wall surface of the chamfered region.

[12] In the gas discharge method according to

[10] or

[11] , In the step of preparing the housing, an inner wall surface of the chamfered region may be formed to be linear or curved in a cross section along a thickness direction of the housing.

[13] In the gas discharge method according to any one of

[10] to

[12] , In the step of preparing the housing, a straight region that opens to an outer surface of the housing and extends with a constant inner diameter is formed in the gas discharge hole; The step of tearing the seal may include bending and tearing the seal so that at least a portion of the seal reaches the straight region.

[14] The gas discharge method according to any one of

[10] to

[13] , In the step of tearing the seal, the seal may be bent and torn so that a minimum flow path cross-sectional area of ​​the combustion gas flow path formed in the gas discharge hole is smaller than a minimum cross-sectional area of ​​the gas discharge hole.

[15] The gas discharge method according to any one of

[10] to

[14] , In the step of blocking the gas exhaust hole, the gas exhaust hole may be blocked by the seal including an aluminum base layer and an adhesive layer provided on one side of the base layer and adhered to the inner surface of the housing.

[16] The gas discharge method according to any one of

[10] to

[15] , The housing is formed with a plurality of the gas exhaust holes, In the step of assembling the gas generator, a cylindrical filter is disposed inside the housing so as to form an annular space between the filter and an inner surface of the housing; In the step of breaking open the seal, pressure may be applied to the seal while the pressure in the annular space is made uniform by introducing the combustion gas generated by activation of the igniter and passing through the filter into the annular space.

[17] The gas discharge method according to any one of

[10] to

[16] , In the step of splitting the seal, the seal may be stretched by pressure of the combustion gas, and the seal may be bent and split in a state where at least a portion of the seal remains within the gas discharge hole. Effect of the Invention

[0009] According to the technique of the present disclosure, it is possible to reduce the amount of combustion residue discharged to the outside of the gas generator. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a vertical cross-sectional view showing a state before activation of the gas generator according to the embodiment. [Diagram 2] 2 is an enlarged cross-sectional view of the vicinity of a gas discharge hole of the gas generator according to the embodiment. FIG. [Diagram 3] 5 is a cross-sectional view for explaining a structure of a seal tape of the gas generator according to the embodiment. FIG. [Figure 4] 4 is a flowchart of a gas discharge method for the gas generator according to the embodiment. [Diagram 5] FIG. 1 is a cross-sectional view (1) for explaining a preparation step of a housing according to an embodiment. [Figure 6] FIG. 11 is a cross-sectional view (2) illustrating the preparation step of the housing according to the embodiment. [Figure 7] FIG. 2 is a cross-sectional view (1) for explaining a seal cleaving process according to the embodiment. [Figure 8] FIG. 11 is a cross-sectional view (2) for explaining the seal cleaving process according to the embodiment. [Figure 9] 10 is an enlarged cross-sectional view of the vicinity of a gas discharge hole of a gas generator according to a first modified example of the embodiment. FIG. [Figure 10] FIG. 11 is a cross-sectional view illustrating a structure of a seal tape of a gas generator according to a second modified example of the embodiment. [Figure 11] 1 is a table showing the results of a combustion residue amount measurement test. [Figure 12] 1 is a table showing the results of a chamfer ratio evaluation test. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] A gas generator according to an embodiment of the present disclosure will be described below with reference to the drawings. In the embodiment described below, a mode in which the technology according to the present disclosure is applied to a gas generator (inflator) for an airbag will be described. However, the use of the technology according to the present disclosure is not limited thereto, and the technology may be applied to a gas generator for a seat belt retractor, for example. Each configuration and combination thereof in each embodiment is an example, and addition, omission, substitution, and other modifications of the configuration are possible as appropriate within the scope of the present invention. The present disclosure is not limited by the embodiments, but is limited only by the claims. In this specification, "chamfering" refers to removing a corner of a member, and includes C-chamfering and R-chamfering.

[0012] Fig. 1 is a vertical cross-sectional view showing a state before activation of a gas generator 100 according to an embodiment. Fig. 1 shows a cross section along the central axis of a housing 1 indicated by the symbol CA1. The gas generator 100 according to the present embodiment is configured as a so-called dual-type gas generator having two igniters. However, the technology according to the present disclosure is not limited thereto. In other words, the gas generator according to the present disclosure only needs to be provided with one or more igniters, and may be a so-called single-type gas generator having only one igniter, or may be a gas generator having three or more igniters.

[0013] [Overall configuration] 1, the gas generator 100 includes a first ignition device 4, a first inner cylinder member 5, an enhancer charge 6, a second ignition device 7, a second inner cylinder member 8, a filter 9, a first gas generating agent 110, a second gas generating agent 120, a housing 1 accommodating these, a plurality of gas discharge holes 13 penetrating the inside and outside of the housing 1, and a seal tape S1 closing the plurality of gas discharge holes 13. The gas generator 100 is configured to combust the first gas generating agent 110 by activating a first igniter 41 included in the first ignition device 4, combust the second gas generating agent 120 by activating a second igniter 71 included in the second ignition device 7, and release the combustion gas, which is a combustion product thereof, from the plurality of gas discharge holes 13 formed in the housing 1. Here, the direction along the central axis CA1 of the housing 1 is defined as the up-down direction of the gas generator 100, the upper shell side indicated by reference numeral 2 (i.e., the upper side in FIG. 1) is the upper side of the gas generator 100, and the lower shell side indicated by reference numeral 3 (i.e., the lower side in FIG. 1) is the lower side of the gas generator 100. Each component of the gas generator 100 will be described below. Note that in this specification, the operation of an igniter included in an ignition device may be expressed as "the ignition device operates" or "the gas generator operates" for convenience.

[0014] [housing] The housing 1 is formed into a short cylinder shape including a cylindrical peripheral wall portion indicated by reference numeral 11, with both axial ends of the peripheral wall portion 11 closed, by joining an upper shell 2 and a lower shell 3, each of which is made of metal and formed into a substantially cylindrical shape with a bottom, with their open ends facing each other. The central axis CA1 in FIG. 1 is the central axis of the peripheral wall portion 11.

[0015] The upper shell 2 has a cylindrical upper peripheral wall portion 21 and a top plate portion 22 closing the upper end of the upper peripheral wall portion 21. A joint portion 23 extending radially outward is connected to the lower end of the upper peripheral wall portion 21. The lower shell 3 has a cylindrical lower peripheral wall portion 31 and a bottom plate portion 32 closing the lower end of the lower peripheral wall portion 31. A joint portion 33 extending radially outward is connected to the upper end of the lower peripheral wall portion 31. A first mounting hole 32a for mounting the first ignition device 4 to the bottom plate portion 32 and a second mounting hole 32b for mounting the second ignition device 7 to the bottom plate portion 32 are formed in the bottom plate portion 32.

[0016] The joint portion 23 of the upper shell 2 and the joint portion 33 of the lower shell 3 are overlapped and joined by laser welding or the like to form a short cylindrical housing 1 with both axial ends closed. The upper peripheral wall portion 21 of the upper shell 2 and the lower peripheral wall portion 31 of the lower shell 3 form a cylindrical peripheral wall portion 11 connecting the top plate portion 22 and the bottom plate portion 32. That is, the housing 1 is configured to include the cylindrical peripheral wall portion 11, the top plate portion 22 provided on one end side of the peripheral wall portion 11, and the bottom plate portion 32 provided on the other end side so as to face the top plate portion 22. The peripheral wall portion 11, the top plate portion 22, the bottom plate portion 32, and the second inner cylinder member 8 described later define a first combustion chamber 10. In the first combustion chamber 10, a first ignition device 4, a first inner cylinder member 5, an enhancer charge 6, a filter 9, and a first gas generating agent 110 are arranged.

[0017] [Ignition device] As shown in FIG. 1, the first ignition device 4 is fixed to a first mounting hole 32a formed in the bottom plate portion 32 of the lower shell 3. The first ignition device 4 includes a first igniter 41. The second ignition device 7 is fixed to a second mounting hole 32b formed in the bottom plate portion 32 of the lower shell 3. The second ignition device 7 includes a second igniter 71. The first igniter 41 and the second igniter 71 each contain an ignition charge therein, and are actuated by the supply of an ignition current to burn the ignition charge and release the combustion product to the outside. The first igniter 41 and the second igniter 71 are examples of the "igniter" according to the present disclosure. The first ignition device 4 and the second ignition device 7 operate independently of each other. When the second ignition device 7 operates, the second ignition device 7 operates simultaneously with the actuation of the first ignition device 4 or at a predetermined timing after the actuation of the first ignition device 4. The gas generator 100 can emit a large amount of combustion gas to the outside with various output profiles by the combustion of the first gas generating agent 110 by the activation of the first ignition device 4 and the combustion of the second gas generating agent 120 by the activation of the second ignition device 7, as compared with a so-called single-type gas generator. Note that the second ignition device 7 does not always operate, and for example, the gas generator 100 may operate only the first ignition device 4 without activating the second ignition device 7 in response to an impact detected by a sensor when the impact is weak. Also, for example, when the impact is strong, the first ignition device 4 and the second ignition device 7 can be activated simultaneously.

[0018] [Inner cylinder material] The first inner cylinder member 5 is a bottomed cylindrical member extending from the bottom plate portion 32 toward the top plate portion 22, and includes a cylindrical surrounding wall portion 51 and a cover wall portion 52 closing one end of the surrounding wall portion 51. The first ignition device 4 is fitted or pressed into the other end of the surrounding wall portion 51, so that the first inner cylinder member 5 is attached to the bottom plate portion 32. As shown in FIG. 1, the first ignition device 4 is surrounded by the surrounding wall portion 51, so that a transfer chamber 53 is formed between the first inner cylinder member 5 and the first ignition device 4. The transfer chamber 53 contains a transfer charge 6 that is burned by the operation of the first ignition device 4. In addition, the surrounding wall portion 51 of the first inner cylinder member 5 has a plurality of communication holes h1 that communicate between its internal space (i.e., the transfer chamber 53) and the external space. The communication hole h1 may be closed by a sealing tape before the first ignition device 4 is activated.

[0019] The second inner cylinder member 8 is a bottomed cylindrical member extending from the bottom plate portion 32 toward the top plate portion 22, and includes a cylindrical surrounding wall portion 81 and a cover wall portion 82 that closes one end of the surrounding wall portion 81. The second ignition device 7 is fitted or press-fitted into the other end of the surrounding wall portion 81, so that the second inner cylinder member 8 is fitted into the bottom plate portion 1, the second inner cylinder member 8 is provided with a second combustion chamber 20 in which a second ignition device 7 and a second gas generating agent 120 that is combusted by the activation of the second ignition device 7 are disposed. The second inner cylinder member 8 is provided with a plurality of communication holes h2 in the surrounding wall portion 81 of the second inner cylinder member 8, which communicate the internal space (i.e., the second combustion chamber 20) with the external space (i.e., the first combustion chamber 10). The communication holes h2 are closed by a sealing tape before the second ignition device 7 is activated.

[0020] [filter] As shown in FIG. 1, the filter 9 is formed in a cylindrical shape and is disposed in the first combustion chamber 10 so as to surround the first gas generating agent 110 and to have the gas discharge holes 13 located outside the first gas generating agent 110 in the radial direction. That is, the filter 9 is disposed between the first gas generating agent 110 and the plurality of gas discharge holes 13 so as to surround the first gas generating agent 110. As a result, as shown in FIG. 1, an annular space 12 is formed between the outer peripheral surface of the filter 9 and the inner surface 11a (the inner peripheral surface of the peripheral wall portion 11) of the housing 1. The filter 9 is supported by abutting its upper end surface against the top plate portion 22 of the upper shell 2, and is supported by abutting its lower end surface against the bottom plate portion 32 of the lower shell 3. The filter 9 can be formed, for example, by forming a metallic wire or a porous plate into a cylindrical shape. When the combustion gas of the first gas generating agent 110 or the second gas generating agent 120 passes through the filter 9, the filter 9 removes heat from the combustion gas to cool the combustion gas. In addition to cooling the combustion gas, the filter 9 also has a function of filtering the combustion gas by collecting combustion residues contained in the combustion gas. Note that the "filter" according to the present disclosure may have at least one of the functions of cooling the combustion gas and collecting combustion residues.

[0021] [Explosive powder] As the enhancer charge 6, in addition to known black powder, a gas generating agent having good ignition properties and a higher combustion temperature than the first gas generating agent 110 can be used. The combustion temperature of the enhancer charge 6 can be set in the range of 1700 to 3000°C. As such an enhancer charge 6, for example, a known material containing nitroguanidine (34% by weight) or strontium nitrate (56% by weight) can be used. In addition, the enhancer charge 6 can be in various shapes, such as granular, pellet, cylindrical, or disk-like.

[0022] [Gas generator] The first gas generating agent 110 generates a combustion gas by burning in response to the activation of the first igniter 41. The second gas generating agent 120 generates a combustion gas by burning in response to the activation of the second igniter 71. A gas generating agent having a relatively low combustion temperature can be used for the first gas generating agent 110 and the second gas generating agent 120. The combustion temperature of the first gas generating agent 110 and the second gas generating agent 120 can be set in the range of 1000 to 1700°C. As such a first gas generating agent 110 and the second gas generating agent 120, for example, a known agent containing guanidine nitrate (41% by weight), basic copper nitrate (49% by weight), a binder, and an additive can be used. In addition, the first gas generating agent 110 and the second gas generating agent 120 can be in various shapes, such as granular, pellet, cylindrical, and disk shapes.

[0023] [Gas exhaust hole] As shown in FIG. 1, a plurality of gas exhaust holes 13 penetrating the inside and outside of the housing 1 are formed in the peripheral wall portion 11 of the housing 1, lined up in the circumferential direction. The gas exhaust holes 13 penetrate from the inner surface 11a (the inner peripheral surface of the peripheral wall portion 11) of the housing 1 to the outer surface 11b (the outer peripheral surface of the peripheral wall portion 11). The internal space of the housing 1 (first combustion chamber 10) and the external space of the housing 1 are connected via the gas exhaust holes 13. As a result, the gas exhaust holes 13 form a flow path for discharging combustion gas from the inside of the housing 1 to the outside. Note that in the technology according to the present disclosure, the number of gas exhaust holes does not need to be multiple, and the housing may have one or more gas exhaust holes. It is sufficient if it is formed.

[0024] FIG. 2 is an enlarged cross-sectional view of the vicinity of the gas discharge hole 13 of the gas generator 100 according to the embodiment. In FIG. 2, a cross section along the central axis CA1 of the housing 1 is illustrated. The cross section illustrated in FIG. 2 is also a cross section along the thickness direction of the housing 1. Reference numeral 13a1 in FIG. 2 indicates an opening of the gas discharge hole 13 on the inner surface 11a side of the housing 1, and reference numeral 13a2 indicates an opening of the gas discharge hole 13 on the outer surface 11b side of the housing 1. The gas discharge hole 13 according to the present embodiment is formed as a hole in which the cross section and the opening perpendicular to the thickness direction (gas flow direction) of the housing 1 are circular (perfect circle). However, the cross-sectional shape and the opening shape of the gas discharge hole according to the present disclosure are not limited to a circle, and various shapes such as an ellipse, an oval, a polygon, etc. can be adopted. The opening 13a of the gas discharge hole 13 is covered by a seal tape S1.

[0025] As shown in FIG. 2, the gas exhaust hole 13 has a chamfered region 131 in which the corners of the opening on the inner surface 11a side of the housing 1 are removed over the entire circumference, and a straight region 132 that is connected to the chamfered region 131 and extends with a constant inner diameter along the thickness direction of the housing 1. In the gas exhaust hole 13, the chamfered region 131 opens on the inner surface 11a side of the housing 1, and the straight region 132 opens on the outer surface 11b side of the housing 1. The chamfered region 131 of the gas exhaust hole 13 opens on the inner surface 11a to form the opening 13a. The straight region 132 of the gas exhaust hole 13 opens on the outer surface 11b to form the opening 13b. Reference numeral 13a1 denotes the periphery of the opening 13a, and reference numeral 13b1 denotes the periphery of the opening 13b. Moreover, reference numeral 13c1 denotes a boundary between an inner wall surface 1311 forming the chamfered region 131 and an inner wall surface 1321 forming the straight region 132.

[0026] The chamfered region 131 is tapered so that the diameter decreases with increasing distance from the opening 13a on the inner surface 11a side of the housing 1 in the thickness direction of the housing. Therefore, the cross-sectional area of ​​the chamfered region 131 decreases with increasing distance from the opening 13a on the inner surface 11a side of the housing 1 in the thickness direction of the housing. Therefore, among the inner wall surfaces of the gas discharge hole 13, the inner wall surface 1311 forming the chamfered region 131 has a cylindrical shape that decreases in diameter with increasing distance from the opening 13a on the inner surface 11a side of the housing 1 in the thickness direction of the housing, and is formed in a straight line inclined with respect to the thickness direction in a cross section along the thickness direction of the housing 1. As a result, the inner wall surface 1311 faces the inside of the housing 1.

[0027] The straight region 132 is formed so that its cross section (cross-sectional shape and cross-sectional area) is constant in the thickness direction of the housing 1. Of the inner wall surfaces of the gas discharge hole 13, an inner wall surface 1321 that forms the straight region 132 has a cylindrical shape with a constant diameter in the thickness direction of the housing 1, and is formed so that in a cross section along the thickness direction of the housing 1, it has a straight line extending along the thickness direction.

[0028] Although the details will be described later, the gas exhaust hole 13 is formed by drilling a through hole in the housing 1 by drilling or punching, and removing the corners at the opening on the inner surface 11a side of the housing 1 by chamfering. The chamfered area 131 according to this embodiment is formed in a tapered shape by so-called C chamfering, and the chamfer angle θ with respect to the inner surface 11a of the housing 1 is 45°. However, the value of the chamfer angle θ (angle of θ in FIG. 2) is not limited to this, and may be θ<90°. For example, the width dimension of the chamfered area 131 is the chamfer width W [mm], and the depth dimension is the chamfer depth D [mm]. In this example, the chamfered area 131 is formed by C chamfering with a chamfer angle θ=45°, so the chamfer width W and the chamfer depth D are equal. The values ​​of W and D in this C chamfering are the chamfer amount X (distance from the tip of the material to be chamfered: mm). In the technology according to the present disclosure, it is not essential that the chamfer width and the chamfer depth are equal to each other, and they may be different from each other.

[0029] The diameter of the straight region 132 is defined as a hole diameter φ1 [mm], and the diameter of the opening 13a of the gas discharge hole 13 on the inner surface 11a side of the housing 1 is defined as an opening diameter φ [mm]. In this case, the opening diameter φ is expressed by the following formula (1). φ=φ1+X×2 Equation (1) Furthermore, when the chamfer angle θ is 45°, the ratio of the chamfer amount X to the opening diameter φ of the gas exhaust hole 13 is defined as a chamfer ratio P [%]. The chamfer ratio P is expressed by the following formula (2). P=X / φ×100 Formula (2) The chamfer ratio P is preferably 2.9[%]≦P≦100[%], more preferably 2.9[%]≦P≦50[%], even more preferably 2.9[%]≦P≦30[%], and even more preferably 2.9[%]≦P≦10[%].

[0030] Here, the minor angle formed between the inner surface 11a of the housing 1 and the inner wall surface 1311 of the chamfered region 131 in a cross section along the thickness direction of the housing 1 is defined as θ1. At this time, θ1>90[°] (in this example, θ1=135[°]). Similarly, the minor angle formed between the inner wall surface 1311 of the chamfered region 131 and the inner wall surface 1321 of the straight region 132 in a cross section along the thickness direction of the housing 1 is defined as θ2. At this time, θ2>90[°] (in this example, θ2=135[°]). In other words, θ1 and θ2 are both obtuse angles.

[0031] 2, the area of ​​a cross section of gas discharge hole 13 perpendicular to the thickness direction of housing 1 is smallest in straight region 132. The smallest cross-sectional area of ​​gas discharge hole 13 in a cross section perpendicular to the thickness direction of housing 1 is defined as A1. Cross-sectional view CS1 in FIG. 2 shows a cross section perpendicular to the thickness direction of housing 1 in straight region 132. As shown in cross-sectional view CS1, gas discharge hole 13 according to this embodiment has smallest cross-sectional area A1 in straight region 132.

[0032] [Sealing tape] As shown in Fig. 1, a sealing tape S1 is attached to the inner surface 11a of the housing 1. The sealing tape S1 is an example of a "seal" according to the present disclosure. The sealing tape S1 is formed in a sheet shape (strip shape in this example) and is a metallic member that closes the gas discharge hole 13 before the igniter is activated and opens the gas discharge hole 13 by rupturing when the igniter is activated. Since the sealing tape S1 is made of metal, it has a certain degree of flexibility and ductility at least against the pressure of the combustion gas.

[0033] FIG. 3 is a cross-sectional view for explaining the structure of the seal tape S1 of the gas generator 100 according to the embodiment. FIG. 3 illustrates a state in which the seal tape S1 is attached to the inner surface 11a of the housing 1. The seal tape S1 is a strip-shaped member in which an adhesive layer is formed on one side of a base layer made of, for example, a metal. As shown in FIG. 3, the seal tape S1 includes an aluminum base layer S11 and an adhesive layer S12 provided on one side of the base layer S11, and the adhesive layer S12 adheres to the inner surface 11a of the housing 1, thereby attaching the seal tape S1 to the inner surface 11a. The base layer S11 is preferably made of aluminum, but is not limited thereto, and may be made of stainless steel or copper. The adhesive layer S12 can be a layer made of a known synthetic resin-based adhesive. As the adhesive, a silicone-based, rubber-based, or epoxy-based adhesive is preferable in terms of heat resistance and adhesiveness. However, the material of the seal tape S1 is not limited to the above. As shown in FIG. 3, the thickness of the base layer S11 is denoted by t1, the thickness of the adhesive layer is denoted by t2, and the thickness of the seal tape S1 is denoted by t3.

[0034] As shown in FIG. 2, the sealing tape S1 is attached to the inner surface 11a of the housing 1 while covering the openings of the gas exhaust holes 13 on the inner surface 11a side, thereby closing the multiple gas exhaust holes 13. Therefore, the chamfered areas 131 of all the gas exhaust holes 13 are covered by the sealing tape S1. The gas discharge hole 13 is covered with sealing tape S1. Before the igniter (first igniter 41) is activated, the gas discharge hole 13 is blocked by sealing tape S1, thereby preventing outside air (moisture) from entering the inside of the housing 1 through the gas discharge hole 13, and the inside of the housing 1 is kept airtight. When the first igniter 41 is activated, the sealing tape S1 is ruptured by the pressure of the generated gas, thereby opening the multiple gas discharge holes 13.

[0035] Here, in this specification, the pressure required to rupture the seal (seal tape S1 in this example) at each gas discharge hole to open the gas discharge hole is defined as the "rupture pressure." When the seal ruptures, the seal, subjected to the pressure of the combustion gas, is pressed against the periphery of the opening of the gas discharge hole on the inner surface side of the housing. Therefore, the rupture pressure of the seal at each gas discharge hole is determined according to the specifications of the seal and the shape of the opening of the gas discharge hole. Specifically, the specifications of the seal are the tensile strength and thickness of the seal. The lower the tensile strength of the seal or the thinner the seal, the lower the rupture pressure.

[0036] In addition, in this specification, the cross-sectional area of ​​the combustion gas flow path (gas flow path) formed in the gas exhaust hole 13 by the sealing tape S1 being torn is defined as the flow path cross-sectional area, which is perpendicular to the flow direction of the combustion gas. In this embodiment, the direction in which the gas exhaust hole 13 penetrates the housing 1, that is, the thickness direction of the housing 1, is the flow direction of the combustion gas. The minimum cross-sectional area in the gas flow path is defined as the minimum flow path cross-sectional area. In the gas flow path, the location where the minimum flow path cross-sectional area is the rate-limiting (throttling) of gas exhaust. The effective cross-sectional area through which gas can actually flow in the gas flow path is a size corresponding to the minimum flow path cross-sectional area. In other words, the amount of gas exhausted per unit time from the gas exhaust hole 13 is determined according to the minimum flow path cross-sectional area of ​​the gas flow path formed in the gas exhaust hole 13. The internal pressure of the housing 1 can be controlled by adjusting the number of opened gas exhaust holes and the amount of gas exhausted per unit time from the gas exhaust holes.

[0037] [Operation] Hereinafter, a basic operation of the gas generator 100 according to this embodiment will be described with reference to Fig. 1. In this example, a case will be described in which the second ignition device 7 operates with a delay after the first ignition device 4 (i.e., after the first ignition device 4 is activated).

[0038] When a sensor (not shown) detects an impact, an ignition current is supplied to the first igniter 41 of the first ignition device 4, and the first igniter 41 is activated. Then, the ignition charge housed in the first igniter 41 burns, and the combustion products such as flame and high-temperature gas are released into the transfer chamber 53. As a result, the transfer charge 6 housed in the transfer chamber 53 burns, and combustion gas is generated in the transfer chamber 53. When the seal tape blocking the communication hole h1 of the surrounding wall portion 51 of the first inner cylinder member 5 is torn by the pressure of the combustion gas of the transfer charge 6, the combustion gas is discharged to the outside of the transfer chamber 53 through the communication hole h1. Then, the combustion gas of the transfer charge 6 comes into contact with the first gas generating agent 110 arranged around the surrounding wall portion 51, and the first gas generating agent 110 is ignited. When the first gas generating agent 110 burns, high-temperature and high-pressure combustion gas is generated in the first combustion chamber 10. The sealing tape S1 is ruptured by the pressure of the combustion gas, thereby opening the multiple gas discharge holes 13. The combustion gas passes through the filter 9, whereby the combustion gas is cooled and combustion residue is collected. The combustion gas of the first gas generating agent 110 that has been cooled and filtered by the filter 9 is introduced into the annular space 12 and is discharged to the outside of the housing 1 through the multiple gas discharge holes 13.

[0039] Next, when the second igniter 71 of the second ignition device 7 is activated, the second gas generating agent 120 accommodated in the second combustion chamber 20 is combusted, generating combustion gas within the second combustion chamber 20. When the sealing tape blocking the communication hole h2 of the surrounding wall portion 81 of the second inner cylindrical member 8 is torn by the pressure of the combustion gas of the second gas generating agent 120, the combustion gas is discharged through the communication hole h2 to the first combustion chamber 10. The combustion gas of the second gas generating agent 120 is cooled and filtered by the filter 9, and then introduced into the annular space 12 and discharged to the outside of the housing 1 through the multiple gas discharge holes 13. It is served.

[0040] The combustion gas of the first gas generating agent 110 and the second gas generating agent 120 flows into an airbag (not shown) after being discharged to the outside of the housing 1. When the airbag inflates, a cushion is formed between the occupant and a hard structure, protecting the occupant from an impact.

[0041] [How to exhaust gas from a gas generator] Next, a method for discharging gas in the gas generator according to the present embodiment (gas discharge method) will be described. However, the gas discharge method for the gas generator according to the present disclosure is not limited to the following method. FIG. 4 is a flowchart of the gas discharge method for the gas generator according to the embodiment. As shown in FIG. 4, the gas discharge method for the gas generator according to the present embodiment includes a housing preparation step in step S101, a blocking step of a gas discharge hole in step S102, an assembly step of a gas generator in step S103, an igniter activation step in step S104, and a seal cleavage step in step S105.

[0042] First, in the housing preparation step of step S101, the housing 1 having the gas exhaust hole 13 formed therein is prepared. Figures 5 and 6 are cross-sectional views for explaining the housing preparation step according to the embodiment. In Figures 5 and 6, a cross section along the thickness direction of the housing 1 is illustrated. In the housing preparation step, the gas exhaust hole 13 is formed in the housing 1.

[0043] In forming the gas exhaust hole 13, first, as shown in FIG. 5, a through hole 14 extending with a constant inner diameter along the thickness direction of the housing 1 is formed in the housing 1. The through hole 14 is drilled at a position where the gas exhaust hole 13 is to be formed in the housing 1 by, for example, drilling or punching. Here, reference symbol AC1 in FIG. 5 indicates a corner of the opening of the through hole 14 on the inner surface 11a side of the housing 1. Next, as shown in FIG. 6, the corner AC1 is removed over the entire circumference by C-chamfering to form a chamfered region 131 and a straight region 132. The region of the through hole 14 that is removed by chamfering forms the chamfered region 131, and the region that remains without being removed forms the straight region 132. The chamfered region 131 is formed so as to decrease in diameter as it moves away from the opening 13a on the inner surface 11a side of the housing 1 in the thickness direction of the housing. An inner wall surface 1311 of the chamfered region 131 is formed so as to be linearly inclined with respect to the thickness direction in a cross section along the thickness direction of the housing 1. The straight region 132 is formed so as to open to the outer surface of the housing from the boundary portion 13c1 as a starting point and extend with a constant inner diameter. An inner wall surface 1321 of the straight region 132 is formed so as to be linearly extending along the thickness direction in a cross section along the thickness direction of the housing 1. In this manner, the gas exhaust hole 13 having the chamfered region 131 and the straight region 132 is formed in the housing 1.

[0044] Next, in the gas discharge hole closing process of step S102, a seal tape S1 is attached to the inner surface 11a of the housing 1 so as to cover the openings 13a of the multiple gas discharge holes 13 on the inner surface 11a side of the housing 1. This closes all of the multiple gas discharge holes 13.

[0045] Next, in the gas generator assembly process of step S103, the first ignition device 4 and the second ignition device 7 are attached to the lower shell 3, the first inner cylinder member 5 filled with the transfer charge 6 is fixed to the first ignition device 4, and the second inner cylinder member 8 filled with the second gas generating agent 120 is fixed to the second ignition device 7. Thereafter, a filter 9 is placed in the lower shell 3, and the inside of the filter 9 is filled with the first gas generating agent 110. Finally, the upper shell 2 is placed over the lower shell 3, and the joint portion 23 of the upper shell 2 and the joint portion 33 of the lower shell 3 are overlapped and joined by laser welding or the like to form the housing 1. In this manner, the gas generator 100 is assembled.

[0046] Next, in an igniter activation process of step S104, the igniter of the gas generator 100 is activated. Note that, in the case where the gas generator 100 activates the second igniter 71 after activation of the first igniter 41, the process proceeds to the next step (step S105) after activation of the first igniter 41 and before activation of the second igniter 71.

[0047] Next, in the seal cleaving process of step S105, the seal tape S1 is cleaved by the pressure of the combustion gas generated by the activation of the igniter. Figures 7 and 8 are cross-sectional views for explaining the seal cleaving process according to the embodiment. Figures 7 and 8 show cross sections along the thickness direction of the housing 1.

[0048] As described above, before the igniter is activated, the sealing tape S1 covers the chamfered region 131, and the inner wall surface 1311 of the chamfered region 131 faces the inside of the housing 1. Therefore, when the igniter is activated, as shown in FIG. 7, the sealing tape S1 is stretched and deformed toward the outside of the housing 1 due to the pressure of the combustion gas, and is pressed against the inner wall surface 1311 of the chamfered region 131. At this time, the sealing tape S1 is folded at the opening edge 13a1 and extends so as to follow the inner wall surface 1311 of the chamfered region 131. Here, the region of the sealing tape S1 attached to the inner surface 11a of the housing 1 is defined as the attachment region S1a, the annular region abutting against the inner wall surface 1311 of the chamfered region 131 is defined as the abutment region S1b, and the region inside the abutment region S1b is defined as the inner region S1c.

[0049] Furthermore, the sealing tape S1 is stretched and deformed by the pressure of the combustion gas, so that the inner region S1c reaches the straight region 132 of the gas discharge hole 13 as shown in FIG.

[0050] In this state, the pressure of the combustion gas acts further on the inner region S1c, and the tensile load in the inner region S1c exceeds the tensile strength of the sealing tape S1, so that the inner region S1c is torn apart by ductile fracture (breakage) as shown in FIG. 8. That is, the sealing tape S1 bursts by film destruction from the center of the inner region S1c. The combustion gas is discharged through the gas discharge hole 13. In addition, the inner region S1c is torn apart in the gas discharge hole 13 while at least a part of the mounting region S1a of the sealing tape S1 remains on the inner surface 11a of the housing 1, so that a torn piece F1 of the sealing tape S1 is formed in the gas discharge hole 13. The torn piece F1 is formed by a part of the torn inner region S1c, but may include a part of the abutment region S1b. The torn piece F1 is connected to the mounting region S1a, and can bend by the pressure of the combustion gas with the mounting region S1a as the base end. Therefore, the discharge of the combustion gas is not affected by the torn piece F1.

[0051] If the chamfered region 131 is not formed in the gas discharge hole 13 and the corner AC1 (see FIG. 5) of the opening on the inner surface 11a side of the housing 1 is not removed, the pressure of the combustion gas presses the sealing tape S1 against the corner AC1, and a shear force acts on the sealing tape S1. As a result, the sealing tape S1 is punched out and cleaved together along the opening edge of the gas discharge hole 13 due to shear fracture. For this reason, it is difficult for the sealing tape S1 to remain in the gas discharge hole 13. Furthermore, there is a possibility that pieces of the punched out sealing tape S1 will be discharged to the outside of the housing 1 (outside the gas generator 100) by the pressure of the combustion gas.

[0052] In contrast, in the present embodiment, a chamfered region 131 is formed in the gas discharge hole 13, and the seal tape S1 is received on the inner wall surface 1311 of the chamfered region 131, so that after the seal tape S1 is cleaved, a cleaved piece F1, which is a part of the seal tape S1, remains in the gas discharge hole 13. Therefore, when combustion gas passes through the gas discharge hole 13, at least a part of the combustion residue contained in the combustion gas collides with the cleaved piece F1, thereby suppressing the combustion residue from passing through the gas discharge hole 13 and being discharged to the outside of the gas generator 100. As a result, the discharge amount of the combustion residue is reduced. Also, since at least a part of the seal tape S1 remains in the gas discharge hole 13 as the cleaved piece F1, the amount of fragments of the seal tape S1 discharged to the outside of the gas generator 100 by the pressure of the combustion gas can also be reduced. By having at least a part of the seal tape S1 remain in the gas discharge hole 13 as the cleaved piece F1, the amount of fragments of the seal tape S1 discharged to the outside of the gas generator 100 by the pressure of the combustion gas can also be reduced.

[0053] Here, when the seal tape S1 is cleaved, the minimum flow path cross-sectional area of the gas flow path FP1 formed in the gas discharge hole 13 is defined as A2. The cross-sectional view CS2 in FIG. 8 shows a cross-section orthogonal to the thickness direction of the housing 1 in the straight region 132. As shown in the cross-sectional view CS2, the gas flow path FP1 has the minimum flow path cross-sectional area A2 in the straight region 132.

[0054] If the cleaved seal tape S1 has not reached the straight region 132, the minimum flow path cross-sectional area A2 is equal to the minimum cross-sectional area A1 of the gas discharge hole 13. However, in the present embodiment, since the seal tape S1 has reached the straight region 132, the gas flow path FP1 is narrowed in the straight region 132. Therefore, the minimum flow path cross-sectional area A2 (effective cross-sectional area) of the gas flow path FP1 is smaller than the minimum cross-sectional area A1 of the gas discharge hole 13. That is, A2 < A1. As a result, the effective cross-sectional area through which gas can actually flow in the gas flow path FP1 becomes smaller compared to the case where the seal tape S1 has not reached the straight region 132. This also reduces the discharge amount of the combustion residue.

[0055] Furthermore, in this embodiment, the combustion gas generated by activation of the igniter and passing through the filter 9 is introduced into the annular space 12, whereby the pressure of the combustion gas is made uniform in the space 12. By making the pressure in the annular space uniform, it is possible to make the pressure act uniformly on the seal tape S1 in the multiple gas discharge holes 13. This makes it possible to uniformly cleave the seal tape S1 in the multiple gas discharge holes 13. Note that in the gas generator 100 according to this embodiment, a chamfered region 131 is provided in each of the multiple gas discharge holes 13 so that cleaved pieces F1 are generated, but it is not necessary that a portion of the seal tape S1 remains in all of the gas discharge holes 13 after activation of the igniter.

[0056] [Actions and Effects] As described above, the gas generator 100 according to this embodiment includes the gas discharge hole 13 penetrating the inside and outside of the housing 1 that accommodates an igniter and a gas generating agent therein, and the metal seal tape S1 formed in a sheet shape. The seal tape S1 is attached to the inner surface of the housing 1, and closes the gas discharge hole 13 by covering the opening 13a on the inner surface 11a side of the housing 1 in the gas discharge hole 13 before the igniter is activated, and opens the gas discharge hole 13 by being torn by the pressure of the combustion gas generated by the activation of the igniter. The gas discharge hole 13 has a chamfered region 131 in which the corners of the opening 13a on the inner surface 11a side of the housing 1 are removed over the entire circumference. With this, the seal tape S1 that receives the pressure of the combustion gas when the igniter is activated is received by the inner wall surface 1311 of the chamfered region 131, thereby suppressing shear fracture of the seal tape S1 and making it easier to break by pulling. This allows at least a part of the seal tape S1, that is, a cleaved piece F1, to remain in the gas discharge hole 13 after the seal tape S1 is cleaved. This prevents the combustion residue contained in the combustion gas from passing through the gas discharge hole 13 and being discharged to the outside of the gas generator 100 by the cleaved piece F1. As a result, the amount of the combustion residue discharged from the gas generator 100 can be reduced.

[0057] Furthermore, the gas generator 100 according to this embodiment is configured so that the minimum flow path cross-sectional area A2 of the gas flow path FP1 formed in the gas discharge hole 13 by the sealing tape S1 cleaving is smaller than the minimum cross-sectional area A1 of the gas discharge hole 13. This makes it possible to reduce the effective cross-sectional area of ​​the gas flow path FP1 and further reduce the amount of combustion residue discharged. Note that in this embodiment, the effective cross-sectional area of ​​the gas flow path FP1 is reduced by a portion of the sealing tape S1 that has reached the straight region 132, but the manner in which the effective cross-sectional area is reduced is not limited to this. Furthermore, in the technology according to the present disclosure, it is not essential that the gas discharge hole has a straight region. For example, the gas discharge hole may extend from the chamfered region to the outside of the housing in the thickness direction of the housing. The hole may be an hourglass-shaped hole having a tapered region that increases in diameter as it moves away from the side as a region connected to the chamfered region.

[0058] Here, in the sealing tape S1 including the above-mentioned aluminum base layer S11 and the adhesive layer S12 provided on one side of the base layer S11 and adhered to the inner surface of the housing 1, the thickness t1 of the base layer S11 is preferably 50 [μm] or more and 200 [μm] or less. This can suppress shear fracture of the sealing tape S1 subjected to the pressure of the combustion gas after the igniter is activated, and make it easier to break by pulling. In addition, from the viewpoint of suppressing shear fracture, it is more preferable that the tensile strength of the sealing tape S1 measured in accordance with JIS Z0237 is 100 [N] / 20 [mm] or more and 200 [N] / 20 [mm] or less. However, the thickness of the base layer of the seal according to the present disclosure and the tensile strength of the seal are not limited to the above.

[0059] [Modifications of the embodiment] A gas generator according to a modified example of the embodiment will be described below. In the description of the modified example, differences from the aspect described in Fig. 1 to Fig. 8 will be mainly described, and a detailed description of similarities will be omitted.

[0060] [Variation 1] Fig. 9 is an enlarged cross-sectional view of the vicinity of gas discharge hole 13A of gas generator 100A according to Modification 1. Fig. 9 corresponds to Fig. 2, and shows a cross section along the thickness direction of housing 1.

[0061] Gas exhaust hole 13A according to Modification 1 is formed as a hole having a circular (perfect circle) opening and a cross section perpendicular to the thickness direction of housing 1. As shown in Fig. 9, gas exhaust hole 13A has a chamfered region 131A in which the corners of the opening on the inner surface 11a side of housing 1 are removed (rounded) all around, and a straight region 132 that is continuous with chamfered region 131A and extends with a constant inner diameter along the thickness direction of housing 1.

[0062] The chamfered region 131A according to the first modification is formed so that its diameter decreases with increasing distance from the opening 13a on the inner surface 11a side of the housing 1 in the thickness direction of the housing. Therefore, the inner wall surface 1311A forming the chamfered region 131A has a cylindrical shape that decreases in diameter with increasing distance from the opening 13a on the inner surface 11a side of the housing 1 in the thickness direction of the housing, and is formed in a curved arc shape that is convex toward the inside of the housing 1 in a cross section along the thickness direction of the housing 1. As a result, the inner wall surface 1311A faces the inside of the housing 1.

[0063] The gas discharge hole 13A is formed in step S101 (housing preparation step) of the gas discharge method described above by drilling or punching a through hole in the housing 1 and rounding the corner of the opening on the inner surface 11a side of the housing 1 by so-called R chamfering. By the R chamfering, the inner wall surface 1311A of the chamfered region 131 is formed to have a curved shape (an arc shape in this example) in a cross section along the thickness direction of the housing 1. If the curvature radius of the R chamfer is R [mm], then W = D = R. Note that the inner wall surface 1311A of the chamfered region 131A may have a curved shape other than an arc in a cross section along the thickness direction of the housing 1, and the chamfer width W and the chamfer depth D may not be equal.

[0064] In gas generator 100A according to modified example 1, the same action and effect as in gas generator 100 described above is achieved. That is, after sealing tape S1 is torn, a torn piece F1 that is at least a part of sealing tape S1 can be left in gas discharge hole 13A. As a result, the amount of combustion residue discharged from gas generator 100 can be reduced. Also in gas generator 100A, the amount of combustion residue formed in gas discharge hole 13A due to the sealing tape S1 being torn can be reduced. The minimum cross-sectional area of ​​the gas flow passage is smaller than the minimum cross-sectional area of ​​the gas exhaust hole 13 A. This reduces the effective cross-sectional area of ​​the gas flow passage, and further reduces the amount of combustion residue discharged.

[0065] [Variation 2] FIG. 10 is a cross-sectional view for explaining the structure of a seal tape S1B of a gas generator 100B according to Modification 2. FIG. 10 illustrates a state in which the seal tape S1B is attached to the inner surface 11a of the housing 1. As shown in FIG. 10, the seal tape S1B includes an aluminum base layer S11, an adhesive layer S12 provided on one surface of the base layer S11 and adhering to the inner surface 11a of the housing 1, and an adhesive layer S13 provided on the other surface of the base layer S11 and having adhesiveness. As shown in FIG. 10, the adhesive layer S13 faces the inner side of the housing 1. As with the adhesive layer S12, the adhesive layer S13 can be a layer made of a known synthetic resin-based adhesive.

[0066] In gas generator 100B according to modification 2 as well, the same operational effects as those of gas generator 100 described above are achieved. Furthermore, in gas generator 100B according to modification 2, since adhesive layer S13 is provided on sealing tape S1 facing the inside of housing 1, after sealing tape S1B is cleaved, combustion residue can be attached to and collected on adhesive layer S13 of a part (cleaved piece F1) of sealing tape S1B remaining in gas discharge hole 13. As a result, the amount of combustion residue discharged can be further reduced.

[0067] [Combustion residue amount measurement test] A test was conducted to measure the amount of combustion residue discharged from a gas generator according to an embodiment of the present disclosure (a combustion residue amount measurement test). The present disclosure will be specifically described below with reference to the embodiment. However, the present disclosure is not limited to the aspects of the following embodiment.

[0068] In the test, the gas generators according to the examples and comparative examples described below were operated, and the amount of combustion residue discharged from the gas discharge hole to the outside of the housing was measured. The examples correspond to the gas generator 100 according to the embodiment described in Figs. 1 to 4 and 6 to 8. The comparative example differs from the examples in that the gas discharge hole does not have a chamfered region. That is, the entire region of the gas discharge hole of the comparative example corresponds to the straight region. In the examples and comparative examples, two types of gas discharge holes with different hole diameters φ1 of the straight region were provided in the housing. Of the two types of gas discharge holes, the one with the larger hole diameter φ1 is called the "large hole" and the one with the smaller hole diameter is called the "small hole". The gas discharge hole of the examples was formed by chamfering a through hole made by drilling, and the gas discharge hole of the comparative example was formed by punching (punching by a press) and was not chamfered. The transfer charge and gas generating agent of the same specifications were used in the same amounts in the examples and comparative examples. The sealing tape used had a base layer thickness t1 = 100 [μm], an adhesive layer thickness t2 = 50 [μm], and a tensile strength measured in accordance with JIS Z0237 of 119 [N] / 20 [mm].

[0069] For each of the examples and comparative examples, the amount of combustion residue discharged was measured when the first and second igniters were activated simultaneously and when the second igniter was activated 100 [msec] after the first igniter was activated. Three examples and three comparative examples were prepared, the amount of combustion residue discharged was measured, and the average amount of combustion residue discharged was calculated for each of the examples and comparative examples.

[0070] Figure 11 is a table showing the results of the combustion residue amount measurement test. In the table in Figure 11, the value listed in the "φ1 [mm]" column for "large hole" is the hole diameter φ1 [mm] of the straight region of the large hole. The value listed in the "quantity [pieces]" column for "large hole" is the number of large holes. Similarly, the value listed in the "φ1 [mm]" column for "small hole" is the hole diameter φ1 [mm] of the straight region of the small hole. The number in the "Quantity [pieces]" column for "Small holes" is the number of small holes.

[0071] In the table in Figure 11, the value listed in the "Simultaneous ignition" column of "Amount of combustion residue [mg]" is the average amount [mg] of combustion residue emitted when the first and second igniters are activated simultaneously, and the value listed in the "Delayed ignition" column is the average amount [mg] of combustion residue emitted when the second igniter is activated 100 [msec] after the activation of the first igniter.

[0072] As shown in Fig. 11, in both the cases of simultaneous ignition and delayed ignition, the amount of combustion residue discharged was smaller in the examples than in the comparative examples. From the above test results, it was confirmed that the amount of combustion residue discharged can be reduced by the examples of the present disclosure.

[0073] [Chamfering ratio evaluation test] A test (chamfering ratio evaluation test) was conducted to evaluate the relationship between the chamfering ratio P [%], which is the ratio of the chamfering amount X to the opening diameter φ on the inner surface of the housing at the gas exhaust hole, and the tearing state of the sealing tape.

[0074] FIG. 12 is a table showing the results of the chamfering ratio evaluation test. In the test, gas exhaust holes Nos. 1 to 14 shown in FIG. 12 were formed in a housing with a thickness T1 = 1.4 [mm], and were blocked from the inner surface side of the housing with a seal tape with a thickness t3 = 100 [μm]. Then, the seal tape was cleaved by applying the pressure of combustion gas to the seal tape from the inner surface side of the housing, and the cleavage state was evaluated. The gas exhaust holes Nos. 1 to 12 were chamfered with a chamfering angle θ = 45 [°] to form a chamfered area. The gas exhaust holes Nos. 13 and 14 did not form a chamfered area (i.e., the chamfering amount X = 0 [mm]). The gas exhaust holes Nos. 1 to 13 were formed by drilling, and the gas exhaust hole No. 14 was formed by punching (punching with a press). In the table of FIG. 12, the numerical value in the "φ [mm]" column is the opening diameter φ [mm] of the gas exhaust hole on the inner surface side of the housing. The value in the "X [mm]" column is the chamfering amount X [mm] of the opening of the gas exhaust hole on the inner surface of the housing. The value in the "P [%]" column is the chamfering ratio P [%].

[0075] In the table of Figure 12, the column "Cracked state" indicates the state when the sealing tape was cleaved. When the sealing tape was punched out in one piece along the opening edge of the gas exhaust hole due to shear fracture, "shear" was indicated in the column "Cracked state". When the sealing tape ruptured (membrane rupture) due to ductile fracture (fracture), "fracture" was indicated in the column "Cracked state".

[0076] As shown in Fig. 12, when 2.9[%]≦P, the sealing tape was destroyed. From the above evaluation results, it was confirmed that 2.9[%]≦P is preferable.

[0077] <Other> As described above, the gist of this embodiment is to make the tearing mode of the seal tape ductile fracture by forming a chamfered area of ​​the gas exhaust hole on the side of the housing where the seal tape is attached. As long as the minimum cross-sectional area A1 is ensured, there is no impediment to forming a chamfered area of ​​the gas exhaust hole on the outer side of the housing. Although the preferred embodiments of the present disclosure have been described, each aspect disclosed in this specification can be combined with any other feature disclosed in this specification. [Explanation of symbols]

[0078] 100 Gas Generator 1. Housing 13 Gas exhaust hole 131 Chamfer Area 132 Straight Area S1 Sealing Tape

Claims

1. An igniter, A gas generating agent that generates a combustion gas by burning in response to activation of the igniter; a housing that accommodates the igniter and the gas generating agent therein; a gas exhaust hole penetrating the inside and outside of the housing; a metal seal formed in a sheet shape and attached to the inner surface of the housing, the metal seal covering an opening of the gas discharge hole on the inner surface side of the housing before activation of the igniter to close the gas discharge hole, and cleaving under pressure of the combustion gas generated by activation of the igniter to open the gas discharge hole, The gas exhaust hole has a chamfered area in which a corner of an opening on an inner surface side of the housing is removed over an entire periphery. Gas generator.

2. The chamfered region is formed so as to decrease in diameter as it moves away from the opening on the inner surface side of the housing in the thickness direction of the housing.

2. The gas generator according to claim 1.

3. The inner wall surface of the chamfered region is formed in a straight or curved shape in a cross section along the thickness direction of the housing.

3. The gas generator according to claim 2.

4. The gas discharge hole has a straight region that is continuous with the chamfered region and extends with a constant inner diameter.

2. The gas generator according to claim 1.

5. The seal includes an aluminum base layer and an adhesive layer provided on one surface of the base layer and adhered to an inner surface of the housing, The thickness of the base layer is 50 [μm] or more and 200 [μm] or less. A gas generator according to any one of claims 1 to 4.

6. The seal has a tensile strength measured in accordance with JIS Z0237 of 100 [N] / 20 [mm] or more and 200 [N] / 20 [mm] or less.

6. The gas generator according to claim 5.

7. The seal is provided on the other surface of the base material layer and further includes an adhesive layer having adhesiveness.

6. The gas generator according to claim 5.

8. The seal is configured such that at least a portion of the seal remains within the gas exhaust hole when the seal is torn. A gas generator according to any one of claims 1 to 4.

9. The seal is configured so that a minimum flow path cross-sectional area of ​​a flow path of the combustion gas formed in the gas exhaust hole becomes smaller than a minimum cross-sectional area of ​​the gas exhaust hole when the seal is cleaved.

9. The gas generator according to claim 8.

10. preparing a housing for a gas generator, the housing containing an igniter and a gas generating agent that generates a combustion gas by burning when the igniter is activated, the housing having a gas discharge hole penetrating the inside and outside of the housing, the gas discharge hole having a chamfered region in which a corner of an opening on an inner surface side of the housing is removed over an entire circumference; a step of attaching a sheet-shaped metal seal to an inner surface of the housing to cover an opening of the gas exhaust hole on the inner surface side of the housing, thereby closing the gas exhaust hole; assembling the gas generator; activating the igniter; and pressing the seal against an inner wall surface of the chamfered region by a pressure of the combustion gas generated by activation of the igniter, and tearing an area of ​​the seal that is on the inside of an abutment area that abuts against the inner wall surface of the chamfered region, thereby tearing the seal so that at least a portion of the seal remains in the gas discharge hole. A method for discharging gas from a gas generator.

11. In the step of preparing the housing, the chamfered region is formed in the gas discharge hole so that the diameter of the chamfered region decreases with increasing distance from the opening on the inner surface side of the housing in a thickness direction of the housing; In the step of tearing the seal, the seal is folded and torn so that the seal is aligned along an inner wall surface of the chamfered region. The method for discharging gas from a gas generator according to claim 10.

12. In the step of preparing the housing, an inner wall surface of the chamfered region is formed so as to be linear or curved in a cross section along a thickness direction of the housing. The method for discharging gas from a gas generator according to claim 11.

13. In the step of preparing the housing, a straight region that opens to an outer surface of the housing and extends with a constant inner diameter is formed in the gas discharge hole; In the step of tearing the seal, the seal is bent and torn so that at least a portion of the seal reaches the straight region. A method for discharging gas from a gas generator according to any one of claims 10 to 12.

14. In the step of tearing the seal, the seal is bent and torn so that a minimum flow path cross-sectional area of ​​a flow path of the combustion gas formed in the gas discharge hole becomes smaller than a minimum cross-sectional area of ​​the gas discharge hole. A method for discharging gas from a gas generator according to any one of claims 10 to 12.

15. In the step of closing the gas exhaust hole, the gas exhaust hole is closed by the seal including an aluminum base layer and an adhesive layer provided on one surface of the base layer and adhered to an inner surface of the housing. A method for discharging gas from a gas generator according to any one of claims 10 to 12.

16. The housing is formed with a plurality of the gas exhaust holes, In the step of assembling the gas generator, a cylindrical filter is disposed inside the housing so as to form an annular space between the filter and an inner surface of the housing; In the step of breaking the seal, the combustion gas generated by the activation of the igniter and passing through the filter is introduced into the annular space to make the pressure in the annular space uniform, and then pressure is applied to the seal. A method for discharging gas from a gas generator according to any one of claims 10 to 12.

17. In the step of splitting the seal, the seal is expanded by the pressure of the combustion gas, and the seal is bent and split in a state where at least a portion of the seal remains within the gas discharge hole. A method for discharging gas from a gas generator according to any one of claims 10 to 12.

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