Gas generator and method for manufacturing gas generator

Abstract

In the gas generator, the plurality of gas discharge holes include at least one first gas discharge hole and one second gas discharge hole for making the cracking pressure of the blocking member different, and the minimum flow path cross-sectional area of the gas flow path formed by the first gas discharge hole is equal to the minimum flow path cross-sectional area of the gas flow path formed by the second gas discharge hole. The first gas discharge hole and the second gas discharge hole are different from each other in at least one of the shape and the circumference of the opening on the inner surface side of the housing.

Description

Technical Field

[0001] The invention relates to a gas generator and a method for manufacturing the gas generator. Background Art

[0002] Conventionally, a gas generator is widely used in which an igniter and a gas generating agent are arranged in a housing, the igniter is operated to burn the gas generating agent, and the combustion gas is discharged to the outside through a plurality of gas discharge holes formed in the housing.

[0003] The gas generator is configured such that a plurality of gas discharge ports are blocked by a blocking member such as a sealing tape, thereby maintaining the interior of the housing airtight before operation, and when operating, the blocking member is ruptured by the pressure of the combustion gas, thereby opening the gas discharge hole. In this regard, the following technology is known: when the gas generator is operating, in order to reliably rupture the blocking member and stabilize the output performance, the gas discharge hole is drilled in a manner to form a protrusion (flash) around the inner wall surface side of the housing of the gas discharge hole, and the range including the gas discharge hole and the protrusion is covered with a sealing tape (for example, Patent Document 1).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2013-241102 Summary of the invention

[0007] Problems to be solved by the invention

[0008] Furthermore, the output performance of the gas generator uses the emission amount and emission time of the combustion gas as parameters. In order to obtain stable (good reproducibility) output performance, it is important to stably burn the gas generating agent.

[0009] An object of the technology disclosed herein is to provide a gas generator having stable output performance.

[0010] Solutions for solving problems

[0011] In order to solve the above-mentioned problems, the technology disclosed in the present invention adopts the following structure. That is, the technology disclosed in the present invention is a gas generator. The gas generator disclosed in the present invention comprises: an igniter; a gas generating agent that burns by the operation of the igniter to generate combustion gas; a shell in which the igniter and the gas generating agent are contained; a plurality of gas discharge holes that penetrate the inside and outside of the shell; and a blocking member that is assembled on the inner surface of the shell, covers the openings on the inner surface side of the shell of the plurality of gas discharge holes before the operation of the igniter, thereby blocking the plurality of gas discharge holes, and is ruptured by the pressure of the combustion gas generated by the operation of the igniter, thereby opening the plurality of gas discharge holes. Moreover, the plurality of gas discharge holes include at least one first gas discharge hole and one second gas discharge hole that make the rupture pressure of the blocking member different, the minimum flow path cross-sectional area of ​​the gas flow path formed by the first gas discharge hole is equal to the minimum flow path cross-sectional area of ​​the gas flow path formed by the second gas discharge hole, and at least one of the shape and the perimeter of the opening on the inner surface side of the shell is different from each other in the first gas discharge hole and the second gas discharge hole.

[0012] According to the gas generator disclosed in the present invention, the minimum flow path cross-sectional area for controlling the gas discharge amount is set equal in the first gas discharge hole and the second gas discharge hole, so that the gas discharge amount per unit time of the first gas discharge hole and the gas discharge amount per unit time of the second gas discharge hole can be equal. Moreover, at least one of the shape and the circumference of the opening portion on the inner surface side of the shell is made different in the first gas discharge hole and the second gas discharge hole, so that the rupture pressure of the first gas discharge hole and the rupture pressure of the second gas discharge hole can be different. That is, two gas discharge holes with the same internal pressure control function of the shell and different ease of opening can be intentionally set. As a result, the timing of the opening can be made different in the first gas discharge hole and the second gas discharge hole, and the rapid drop in the internal pressure of the shell can be suppressed when the igniter is working. As a result, the combustion performance of the gas generating agent can be maintained and the output performance of the gas generator can be stabilized.

[0013] Furthermore, in the gas generator of the present disclosure, the first gas discharge hole and the second gas discharge hole may be blocked by the blocking members having the same specifications.

[0014] Furthermore, in the gas generator disclosed herein, the first gas discharge hole and the second gas discharge hole may be holes having a circular cross-section, and the hole diameters of the openings on the inner surface side of the shell in the first gas discharge hole and the second gas discharge hole may be different from each other.

[0015] In addition, in the gas generator disclosed in the present invention, it may also be that the first gas exhaust hole and the second gas exhaust hole include: a straight cylindrical portion, whose cross-section is constant in the thickness direction of the shell; and a tapered portion, which is connected to the straight cylindrical portion and whose cross-sectional area increases as it moves away from the straight cylindrical portion in the thickness direction, and in one of the first gas exhaust hole and the second gas exhaust hole, the tapered portion opens on the inner surface side of the shell, and the straight cylindrical portion opens on the outer surface side of the shell, and in the other of the first gas exhaust hole and the second gas exhaust hole, the straight cylindrical portion opens on the inner surface side of the shell, and the tapered portion opens on the outer surface side of the shell.

[0016] Furthermore, in the gas generator of the present disclosure, the straight tube portion may be formed by a shear surface, and the tapered portion may be formed by a fracture surface.

[0017] Furthermore, in the gas generator of the present disclosure, when the thickness of the housing is t1 and the length of the straight tube portion in the thickness direction of the housing is t2, 0.3 <t2 / t1<0.7。

[0018] In addition, in the gas generator disclosed in the present invention, a protrusion protruding toward the inner side of the shell may be formed on at least a portion of the periphery of the opening portion on the inner surface side of only either one of the first gas exhaust hole and the second gas exhaust hole, and the blocking member may be assembled to the inner surface of the shell in a manner covering the protrusion.

[0019] Furthermore, in the gas generator of the present disclosure, a peripheral edge of an opening of only one of the first gas discharge hole and the second gas discharge hole on the inner surface side of the housing may be chamfered.

[0020] Furthermore, the technology disclosed herein may be specified as a method for manufacturing a gas generator. That is, the technology disclosed in the present invention is a method for manufacturing a gas generator, the gas generator comprising: an igniter; a gas generating agent that burns by the operation of the igniter to generate combustion gas; a shell that accommodates the igniter and the gas generating agent in its interior; a plurality of gas discharge holes that penetrate inside and outside the shell; and a blocking member that blocks the plurality of gas discharge holes, the method for manufacturing the gas generator comprising the following steps: forming a plurality of gas discharge holes including at least one first gas discharge hole and one second gas discharge hole in the shell in such a manner that the rupture pressure of the blocking member is different in the first gas discharge hole and the second gas discharge hole; and assembling the blocking member on the inner surface of the shell in such a manner that the openings on the inner surface side of the shell of the plurality of gas discharge holes are covered, in the process of forming the plurality of gas discharge holes in the shell, the minimum flow path cross-sectional area of ​​the gas flow path formed by the first gas discharge hole is made equal to the minimum flow path cross-sectional area of ​​the gas flow path formed by the second gas discharge hole, and in the first gas discharge hole and the second gas discharge hole, at least one of the shape and the circumference of the opening on the inner surface side of the shell is made different from each other.

[0021] In addition, in the manufacturing method of the gas generator disclosed in the present invention, in the step of forming the multiple gas exhaust holes in the shell, a hole is punched from the outer surface side of the shell using a punching process to form one of the first gas exhaust hole and the second gas exhaust hole, and a hole is punched from the inner surface side of the shell using a punching process to form the other of the first gas exhaust hole and the second gas exhaust hole.

[0022] Furthermore, in the method for manufacturing a gas generator disclosed herein, in the step of forming the plurality of gas discharge holes in the shell, the opening portion of only one of the first gas discharge hole and the second gas discharge hole on the inner surface side of the shell may be chamfered.

[0023] Furthermore, in the method for manufacturing a gas generator of the present disclosure, in the step of attaching a blocking member to the inner surface of the housing, the first gas discharge hole and the second gas discharge hole may be blocked by the blocking member having the same specification.

[0024] Beneficial Effects

[0025] According to the technology disclosed in the present invention, a gas generator having stable output performance can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a longitudinal sectional view showing the state of the gas generator according to Embodiment 1 before operation.

[0027] Figure 2 yes Figure 1 AA section view.

[0028] Figure 3 This is an enlarged cross-sectional view for explaining the shape of the first small hole in Embodiment 1.

[0029] Figure 4 It is a diagram showing the shape of the opening portion of the first small hole on the inner surface side of the housing according to the first embodiment.

[0030] Figure 5 This is an enlarged cross-sectional view for explaining the shape of the second small hole in Embodiment 1.

[0031] Figure 6 It is a diagram showing the shape of the opening portion of the second small hole on the inner surface side of the housing according to the first embodiment.

[0032] Figure 7 This is a flowchart of the method for manufacturing the gas generator according to the first embodiment.

[0033] Figure 8 This is a cross-sectional view for explaining the method of forming the first small hole in the first embodiment.

[0034] Fig. 9 This is a cross-sectional view for explaining the method of forming the second small hole in the first embodiment.

[0035] Fig.10 This is an enlarged cross-sectional view for explaining the shape of the second small hole in Modification 1 of Embodiment 1.

[0036] Fig.11 This is an enlarged cross-sectional view for explaining the shape of the first small hole in the second modification of the first embodiment.

[0037] Fig.12 This is an enlarged cross-sectional view for explaining the shape of the second small hole in the second modification of the first embodiment.

[0038] Fig.13 This is an enlarged cross-sectional view for explaining the shape of the first small hole in the second embodiment.

[0039] Fig.14 This is an enlarged cross-sectional view for explaining the shape of the second small hole in the second embodiment.

[0040] Fig.15 It is a diagram showing an example of the shape of the opening of the small hole on the inner surface side of the housing. DETAILED DESCRIPTION

[0041] Hereinafter, the gas generator of the embodiment of the present disclosure will be described with reference to the accompanying drawings. In the embodiment described below, a scheme of applying the technology of the present disclosure to a gas generator (inflator) for an airbag will be described. However, the use of the technology of the present disclosure is not limited thereto, and for example, it can be applied to a gas generator for a seat belt retractor. Each structure and combination thereof in each embodiment is an example, and the structure can be appropriately added, omitted, replaced, and otherwise changed without departing from the scope of the subject matter of the present invention. The present disclosure is not limited to the embodiment, but only to the claims.

[0042] <Implementation Method 1>

[0043] Embodiment 1 is described below. Embodiment 1 corresponds to a scheme in which the circumference of the opening of the first gas discharge hole on the inner surface side of the shell and the circumference of the opening of the second gas discharge hole on the inner surface side of the shell are different from each other among schemes that the technology disclosed herein can adopt.

[0044] Figure 1 1 is a longitudinal sectional view showing a state of gas generator 100 according to Embodiment 1 before operation. Figure 1 The middle figure shows a cross section along the central axis of the housing 1 indicated by the reference numeral CA1. The gas generator 100 of the first embodiment is configured as a so-called dual-type gas generator having two igniters. However, the technology disclosed in the present invention is not limited thereto. That is, the gas generator disclosed in the present invention may be a so-called single-type gas generator having only one igniter, or may be a gas generator having three or more igniters.

[0045] [Overall composition]

[0046] like Figure 1 As shown, the gas generator 100 includes a first ignition device 4, a first inner cylinder member 5, an explosive 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 shell 1 for accommodating them, a plurality of gas discharge holes H1 penetrating the inside and outside of the shell 1, and a sealing band S1 for blocking the plurality of gas discharge holes H1. The gas generator 100 is configured such that the first gas generating agent 110 is burned by operating the first igniter 41 of the first ignition device 4, and the second gas generating agent 120 is burned by operating the second igniter 71 of the second ignition device 7, and the combustion gas as their combustion products is discharged from the plurality of gas discharge holes H1 formed in the shell 1. Here, the direction along the central axis CA1 of the shell 1 is defined as the up-down direction of the gas generator 100, and the upper shell side (i.e., Figure 1The upper side of the gas generator 100 is set as the upper side of the gas generator 100, and the lower shell side (that is, Figure 1 The lower side in the figure is set as the lower side of the gas generator 100. The following describes the various components of the gas generator 100. It should be noted that in this specification, for convenience, the ignition device operation included in the ignition device is sometimes expressed as "ignition device operation" or "gas generator operation".

[0047] [case]

[0048] In the shell 1, an upper shell 2 and a lower shell 3 made of metal, each formed into a roughly cylindrical shape with a bottom, are joined with their open ends facing each other, thereby forming a short-sized cylindrical shape including a cylindrical peripheral wall portion shown by the figure mark 11 and the axial ends of the peripheral wall portion 11 are blocked. Figure 1 The central axis CA1 is the central axis of the peripheral wall portion 11 .

[0049] The upper housing 2 has a cylindrical upper peripheral wall portion 21 and a top plate portion 22 that blocks 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 housing 3 has a cylindrical lower peripheral wall portion 31 and a bottom plate portion 32 that blocks 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. The bottom plate portion 32 is formed with a first mounting hole 32a for mounting the first ignition device 4 on the bottom plate portion 32 and a second mounting hole 32b for mounting the second ignition device 7 on the bottom plate portion 32.

[0050] The joint portion 23 of the upper shell 2 and the joint portion 33 of the lower shell 3 are joined by laser welding or the like after being superimposed, thereby forming a short cylindrical shell 1 with both ends blocked in the axial direction. 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 shell 1 is configured to include: a cylindrical peripheral wall portion 11; a top plate portion 22, which is provided on one end side of the peripheral wall portion 11; and a bottom plate portion 32, which is provided on the other end side in a manner opposite to the top plate portion 22. The first combustion chamber 10 is defined by these peripheral wall portions 11, the top plate portion 22, the bottom plate portion 32 and the second inner cylinder member 8 described later. The first ignition device 4, the first inner cylinder member 5, the transfer powder 6, the filter 9 and the first gas generating agent 110 are arranged in the first combustion chamber 10.

[0051] [Ignition device]

[0052] like Figure 1As shown, the first ignition device 4 is fixed to the 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 the second mounting hole 32b formed in the bottom plate portion 32 of the lower shell 3. In addition, the second ignition device 7 includes a second igniter 71. The first igniter 41 and the second igniter 71 each contain a primer (not shown) inside, and the first igniter 41 and the second igniter 71 are operated by being supplied with an ignition current, thereby causing the primer to burn and releasing its combustion products to the outside. The first igniter 41 and the second igniter 71 are an example of an "igniter" of 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 at the same time as the first ignition device 4 or at a specified timing after the first ignition device 4 operates. Compared with a so-called single-stage gas generator, the gas generator 100 can release a large amount of combustion gas to the outside with various output profiles by the combustion of the first gas generating agent 110 realized by the operation of the first ignition device 4 and the combustion of the second gas generating agent 120 realized by the operation of the second ignition device 7. It should be noted that the second ignition device 7 does not always work. For example, the gas generator 100 can operate only the first ignition device 4 and not the second ignition device 7 when the impact is weak, and operate the first ignition device 4 and the second ignition device 7 at the same time when the impact is strong, depending on the impact sensed by the sensor (not shown).

[0053] [Inner cylinder member]

[0054] 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 that blocks one end of the surrounding wall portion 51. The first inner cylinder member 5 is assembled to the bottom plate portion 32 by inserting or pressing the first ignition device 4 into the other end of the surrounding wall portion 51. Figure 1 As shown, the first ignition device 4 is surrounded by a surrounding wall portion 51, thereby forming a ignition chamber 53 between the first inner cylinder member 5 and the first ignition device 4. The ignition chamber 53 contains the ignition powder 6 that burns when the first ignition device 4 is operated. In addition, a plurality of communication holes h1 that connect the internal space of the first inner cylinder member 5 (i.e., the ignition chamber 53) with the external space are formed in the surrounding wall portion 51 of the first inner cylinder member 5. Before the first ignition device 4 is operated, the communication holes h1 are blocked by a sealing tape (not shown).

[0055] 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 blocks one end of the surrounding wall portion 81. The second inner cylinder member 8 is assembled to the bottom plate portion 32 by embedding or pressing the second ignition device 7 into the other end of the surrounding wall portion 81. Figure 1 As shown, a second combustion chamber 20 is formed inside the second inner cylinder member 8, and the second combustion chamber 20 is provided with a second ignition device 7 and a second gas generating agent 120 that burns by the operation of the second ignition device 7. In addition, a plurality of communication holes h2 that communicate the internal space of the second inner cylinder member 8 (i.e., the second combustion chamber 20) with the external space (i.e., the first combustion chamber 10) are formed in the surrounding wall portion 81 of the second inner cylinder member 8. Before the second ignition device 7 is operated, the communication holes h2 are blocked by a sealing tape (not shown).

[0056] [Filter]

[0057] like Figure 1 As shown, the filter 9 is formed in a cylindrical shape, and the filter 9 surrounds the first gas generating agent 110, and is arranged in the first combustion chamber 10 in such a manner that the gas discharge hole H1 is located outside the filter 9 in the radial direction of the filter 9. That is, the filter 9 is arranged between the first gas generating agent 110 and the plurality of gas discharge holes H1 in such a manner as to surround the first gas generating agent 110. The upper end surface of the filter 9 abuts against the top plate portion 22 supported by the upper shell 2, and the lower end surface abuts against the bottom plate portion 32 supported by the lower shell 3. When the combustion gas of the first gas generating agent 110 and the second gas generating agent 120 passes through the filter 9, the filter 9 cools the combustion gas by taking away the heat of the combustion gas. In addition, in addition to having a cooling function for the combustion gas, the filter 9 also has a function of filtering the combustion gas by capturing the combustion residue contained in the combustion gas.

[0058] [Gunpowder]

[0059] As the primer 6, in addition to the known black powder, a gas generating agent having good ignition performance and a higher combustion temperature than the first gas generating agent 110 can be used. The combustion temperature of the primer 6 can be set in the range of 1700° C. to 3000° C. As such a primer 6, for example, a known primer containing nitroguanidine (34% by weight) and strontium nitrate (56% by weight) can be used. In addition, the primer 6 can be in various shapes such as granular, pellet, cylindrical, and disc shapes.

[0060] [Gas generating agent]

[0061] The first gas generator 110 burns by the operation of the first igniter 41, thereby generating combustion gas. The second gas generator 120 burns by the operation of the second igniter 71, thereby generating combustion gas. For the first gas generator 110 and the second gas generator 120, a gas generator with a lower combustion temperature can be used. The combustion temperature of the first gas generator 110 and the second gas generator 120 can be set in the range of 1000°C to 1700°C. As such a first gas generator 110 and a second gas generator 120, for example, a known gas generator containing guanidine nitrate (41% by weight), basic copper nitrate (49% by weight), and an adhesive and an additive can be used. In addition, for the first gas generator 110 and the second gas generator 120, various shapes such as granular, pelletized, cylindrical, and disc-shaped can be used.

[0062] [Gas exhaust hole]

[0063] like Figure 1 As shown, a plurality of gas discharge holes H1 penetrating the inside and outside of the housing 1 are formed in a circumferential arrangement on the peripheral wall portion 11 of the housing 1. The gas discharge holes H1 penetrate from the inner surface 11a (the inner peripheral surface of the peripheral wall portion 11) to the outer surface 11b (the outer peripheral surface of the peripheral wall portion 11) of the housing 1. The internal space of the housing 1 (the first combustion chamber 10) is communicated with the external space of the housing 1 via the gas discharge holes H1. Thus, the gas discharge holes H1 form a flow path for discharging combustion gas from the inside of the housing 1 to the outside.

[0064] Here, in this specification, the area of ​​the cross section of the gas flow path formed by the gas discharge hole H1 that is orthogonal to the flow direction of the combustion gas is defined as the flow path cross-sectional area. In Embodiment 1, the direction in which the gas discharge hole H1 penetrates the shell 1, that is, the thickness direction of the shell 1 becomes the flow direction of the combustion gas. Moreover, the cross-sectional area that becomes the smallest in the gas flow path is defined as the minimum flow path cross-sectional area. In the gas discharge hole H1, the portion that becomes the minimum flow path cross-sectional area becomes the speed limit (throttling) of the gas discharge. That is, the gas discharge amount per unit time of the gas discharge hole H1 is determined according to the minimum flow path cross-sectional area. Moreover, by adjusting the number of open gas discharge holes and the gas discharge amount per unit time of the gas discharge holes, the internal pressure of the shell 1 can be controlled.

[0065] like Figure 1 As shown, the plurality of gas discharge holes H1 are constituted to include a plurality of large holes 12 and a plurality of small holes 13 having different minimum flow path cross-sectional areas. In the gas generator 100 of the first embodiment, the minimum flow path cross-sectional area of ​​the large hole 12 is larger than the minimum flow path cross-sectional area of ​​the small hole 13. Therefore, the gas discharge amount per unit time of the large hole 12 is larger than the gas discharge amount per unit time of the small hole 13. Figure 1As shown, a plurality of large holes 12 are arranged in the circumferential direction on the peripheral wall portion 11, and a plurality of small holes 13 are arranged in the circumferential direction below the plurality of large holes 12. However, the arrangement of the large holes 12 and the small holes 13 is not limited to this.

[0066] [Sealing tape]

[0067] like Figure 1 As shown, a sealing tape S1 is installed on the inner surface 11a of the shell 1. The sealing tape S1 is an example of a "blocking member" disclosed in the present invention. The sealing tape S1 is, for example, a strip-shaped member in which an adhesive layer is formed on one side of a metal base material layer, and is installed on the inner surface 11a of the shell 1 by bonding the adhesive layer to the inner surface 11a. The base material layer is preferably made of aluminum, and can also be made of stainless steel or copper. The adhesive layer can be a layer made of a known synthetic resin-based adhesive. As the adhesive, silicone-based, rubber-based, epoxy-based adhesives, etc. are preferred from the point of view of heat resistance and adhesion. However, the material of the sealing tape S1 is not limited to the above.

[0068] like Figure 1 As shown, the sealing tape S1 is assembled to the inner surface 11a in a state of covering the opening of the gas discharge hole H1 on the inner surface 11a side of the housing 1, thereby blocking the plurality of gas discharge holes H1. Before the first igniter 41 is operated, the gas discharge hole H1 is blocked by the sealing tape S1, thereby preventing the outside air (moisture) from penetrating into the interior of the housing 1 through the gas discharge hole H1, and maintaining the interior of the housing 1 airtight.

[0069] like Figure 1 As shown, in Embodiment 1, a single sealing tape S1 is used to block the large holes 12 and the small holes 13. One piece of sealing tape S1 is used to block all the large holes 12, and another piece of sealing tape S1 is used to block all the small holes 13. It should be noted that a single sealing tape may be used to block a plurality of gas discharge holes H1, or one piece of sealing tape may be used to block all the gas discharge holes H1.

[0070] When the first igniter 41 is working, the sealing tape S1 is cracked by the pressure of the generated gas, thereby opening a plurality of gas discharge holes H1. Here, in this specification, the pressure required to crack the blocking member (in this case, the sealing tape S1) in each gas discharge hole and open the gas discharge hole is defined as "cracking pressure". When the blocking member cracks, the blocking member subjected to the pressure of the combustion gas is pressed against the periphery of the opening portion on the inner surface side of the shell of the gas discharge hole and is sheared along the periphery. Therefore, the cracking pressure of the blocking member of each gas discharge hole is determined according to the specifications of the blocking member and the properties of the opening portion of the gas discharge hole. The specifications of the blocking member specifically refer to the tensile strength and thickness of the blocking member. The lower the tensile strength of the blocking member or the thinner the blocking member, the lower the cracking pressure. In addition, the properties of the opening portion of the gas discharge hole specifically refer to the shape and perimeter (length of the periphery) of the opening portion on the inner surface side of the shell of the gas discharge hole. The shape of the opening portion includes protrusions and chamfers formed on the periphery of the opening portion in addition to the planar shape presented by the periphery of the opening portion. When a protrusion is formed on the periphery of the opening, the rupture pressure becomes lower, and when the periphery of the opening is chamfered, the rupture pressure becomes higher. In addition, the longer the periphery of the opening, the lower the rupture pressure.

[0071] In the gas generator 100 of the first embodiment, the rupture pressure of the sealing band S1 at the large hole 12 is set to be lower than the rupture pressure of the sealing band S1 at the small hole 13. In setting the rupture pressures of the large hole 12 and the small hole 13, for example, the circumference of the opening of the large hole 12 on the inner surface 11a side of the housing 1 may be made longer than the circumference of the opening of the small hole 13 on the inner surface 11a side, or the sealing band S1 blocking the large hole 12 may be made thinner than the sealing band S1 blocking the small hole 13.

[0072] [First small hole and second small hole]

[0073] Figure 2 yes Figure 1 AA section view. Figure 2 The middle figure shows a cross section perpendicular to the central axis CA1 of the gas generator 100 before operation. Figure 2 In the figure, for the sake of convenience, the first ignition device 4, the second ignition device 7 and the joints 23 and 33 are omitted.

[0074] like Figure 2 As shown, the plurality of small holes 13 include a plurality of first small holes 13a and a plurality of second small holes 13b. The first small holes 13a are an example of the "first gas discharge hole" of the present disclosure, and the second small holes 13b are an example of the "second gas discharge hole" of the present disclosure. On the peripheral wall portion 11 of the housing 1, the first small holes 13a and the second small holes 13b are alternately arranged at equal intervals in the circumferential direction.

[0075] In the gas generator 100 of the first embodiment, the gas discharge amount per unit time of the first small hole 13a and the second small hole 13b is set equal, and the rupture pressure of the sealing band S1 at the first small hole 13a and the rupture pressure of the sealing band S1 at the second small hole 13b are slightly different. The details will be described later, but in the gas generator 100 of the first embodiment, the properties of the opening part on the inner surface 11a side of the small hole 13 are set in such a way that the rupture pressure of the sealing band S1 at the first small hole 13a is lower than the rupture pressure of the sealing band S1 at the second small hole 13b. However, this does not limit the magnitude relationship between the rupture pressure of the first gas discharge hole (first small hole) and the rupture pressure of the second gas discharge hole (second small hole) of the technology disclosed in the present invention. In addition, in the technology disclosed in the present invention, it is not necessary to have a plurality of first gas discharge holes and second gas discharge holes, as long as the plurality of gas discharge holes include at least one first gas discharge hole and one second gas discharge hole each that make the rupture pressure of the blocking member different. In addition, the arrangement of the first gas discharge holes and the second gas discharge holes in the technology disclosed in the present invention is not limited to the above, and for example, a plurality of first gas discharge holes and a plurality of second gas discharge holes may be biased.

[0076] Figure 3 FIG. 1 is an enlarged cross-sectional view for explaining the shape of the first small hole 13a in Embodiment 1. Figure 3 The figure shows Figure 2 BB profile. Figure 3 Reference numeral 13a1 indicates an opening of the first small hole 13a on the inner surface 11a side of the housing 1, and reference numeral 13a2 indicates an opening of the first small hole 13a on the outer surface 11b side of the housing 1. The first small hole 13a of Embodiment 1 is formed as a hole having a circular (perfect circle) cross section perpendicular to the thickness direction (gas flow direction) of the housing 1. The opening 13a1 of the first small hole 13a is covered by a sealing tape S1.

[0077] like Figure 3As shown, the first small hole 13a includes a straight tube portion 131 and a tapered portion 132. The straight tube portion 131 is formed so that the cross section (cross-sectional shape and cross-sectional area) is constant in the thickness direction of the shell 1. The inner wall surface 131a forming the straight tube portion 131 has a cylindrical shape with a constant diameter in the thickness direction of the shell 1. The tapered portion 132 is formed to be connected to the straight tube portion 131 and the cross-sectional area increases as it moves away from the straight tube portion 131 in the thickness direction of the shell 1. The inner wall surface 132a forming the tapered portion 132 has a cylindrical shape that expands in diameter as it moves away from the straight tube portion 131 in the thickness direction of the shell 1. In the first small hole 13a of embodiment 1, the tapered portion 132 opens on the inner surface 11a side of the shell 1, and the straight tube portion 131 opens on the outer surface 11b side of the shell 1. The tapered portion 132 of the first small hole 13a forms an opening portion 13a1 by opening on the inner surface 11a. The straight tube portion 131 of the first small hole 13a is opened on the outer surface 11b to form an opening portion 13a2. The details will be described later, but the first small hole 13a of the first embodiment is formed by punching from the outer surface 11b side of the housing 1 by punching. The inner wall surface 131a of the straight tube portion 131 is formed as a shear surface achieved by punching. The inner wall surface 132a of the tapered portion 132 is formed as a fracture surface achieved by punching. The shear surface is formed as a relatively smooth surface with a metallic luster, and the fracture surface is formed as a relatively rough surface without a metallic luster.

[0078] like Figure 3 As shown, the cross-sectional area of ​​the gas flow path formed by the first small hole 13a is the smallest in the straight tube portion 131. That is, in the first small hole 13a, the straight tube portion 131 is a restriction for gas discharge. The minimum flow path cross-sectional area of ​​the first small hole 13a is set as A1. Figure 3 The cross-sectional view C1 shows a cross section of the straight tube portion 131 perpendicular to the thickness direction of the housing 1. As shown in the cross-sectional view C1, in the first small hole 13a of the first embodiment, the cross-sectional area of ​​the straight tube portion 131 is the minimum flow path cross-sectional area A1.

[0079] Figure 4 1 is a diagram showing the shape of the opening 13a1 of the first small hole 13a on the inner surface 11a side of the housing 1 according to the first embodiment. Figure 4 As shown, the planar shape of the periphery of the opening 13a1 of the first small hole 13a is circular. The diameter of the opening 13a1 is D1, and the perimeter of the opening 13a1 (the length of the periphery of the opening 13a1) is P1.

[0080] Figure 5 FIG. 1 is an enlarged cross-sectional view for explaining the shape of the second small hole 13b in Embodiment 1. Figure 5 The figure shows Figure 2 CC profile. Figure 5Reference numeral 13b1 indicates an opening of the second small hole 13b on the inner surface 11a side of the housing 1, and reference numeral 13b2 indicates an opening of the second small hole 13b on the outer surface 11b side of the housing 1. The second small hole 13b of Embodiment 1 is formed as a hole having a circular cross section perpendicular to the thickness direction (gas flow direction) of the housing 1, similarly to the first small hole 13a. The opening 13b1 of the second small hole 13b is covered by a sealing tape S1.

[0081] The second small hole 13b is the same as the first small hole 13a, and includes a straight tube portion 131 formed by a shear surface and a tapered portion 132 formed by a fracture surface. The diameter of the straight tube portion 131 of the second small hole 13b is equal to the diameter of the straight tube portion 131 of the first small hole 13a. In the second small hole 13b of embodiment 1, contrary to the first small hole 13a, the straight tube portion 131 opens on the inner surface 11a side of the shell 1, and the tapered portion 132 opens on the outer surface 11b side of the shell 1. The straight tube portion 131 of the second small hole 13b is opened on the inner surface 11a to form an opening portion 13b1. The tapered portion 132 of the second small hole 13b is opened on the outer surface 11b to form an opening portion 13b2. The details will be described later, but the second small hole 13b of embodiment 1 is formed by punching from the inner surface 11a side of the shell 1 by punching processing, contrary to the first small hole 13a.

[0082] like Figure 5 As shown, the cross-sectional area of ​​the gas flow path formed by the second small hole 13b is the same as that of the first small hole 13a, and is the smallest in the straight tube portion 131. That is, in the second small hole 13b, the straight tube portion 131 also throttles the gas discharge. The minimum flow path cross-sectional area of ​​the second small hole 13b is set to A2. Figure 5 The cross-sectional view C2 shows a cross section of the straight tube portion 131 perpendicular to the thickness direction of the housing 1. As shown in the cross-sectional view C2, in the second small hole 13b of the first embodiment, the cross-sectional area of ​​the straight tube portion 131 is the minimum flow path cross-sectional area A2.

[0083] Figure 6 1 is a diagram showing the shape of the opening 13b1 on the inner surface 11a side of the housing 1 of the second small hole 13b according to the first embodiment. Figure 4 As shown, the planar shape of the periphery of the opening 13b1 of the second small hole 13b is the same as that of the opening 13a1 of the first small hole 13a, which is a circle. The diameter of the opening 13b1 is set to D2, and the perimeter of the opening 13b1 (the length of the periphery of the opening 13b1) is set to P2.

[0084] Here, in the first orifice 13a and the second orifice 13b, the minimum flow path cross-sectional area and the properties of the opening on the inner surface 11a side of the shell 1 are compared. As described above, the flow path cross-sectional area of ​​the first orifice 13a and the second orifice 13b is the smallest in the straight tube portion 131 of the same diameter. Therefore, the minimum flow path cross-sectional area A1 of the first orifice 13a is equal to the minimum flow path cross-sectional area A2 of the second orifice 13b. That is, A1=A2. Therefore, the gas discharge amount per unit time of the first orifice 13a and the second orifice 13b is equal. In addition, as Figure 4 and Figure 6 As shown, the shapes of the opening 13a1 of the first small hole 13a and the opening 13b1 of the second small hole 13b are both circular and identical. Here, the opening 13a1 of the first small hole 13a is formed by the tapered portion 132, while the opening 13b1 of the second small hole 13b is formed by the straight tube portion 131, so the opening 13a1 of the first small hole 13a and the opening 13b1 of the second small hole 13b have different apertures. Specifically, the diameter D1 of the opening 13a1 is larger than the diameter D2 of the opening 13b1. D1>D2, so the circumference P1 of the opening 13a1 of the first small hole 13a is longer than the circumference P2 of the opening 13b1 of the second small hole 13b. That is, P1>P2. Therefore, the rupture pressure of the sealing band S1 at the first small hole 13a is lower than the rupture pressure of the sealing band S1 at the second small hole 13b. As a result, the first small hole 13a is easier to open than the second small hole 13b.

[0085] [Method for manufacturing gas generator]

[0086] Next, a description will be given of a method for assembling the gas generator according to Embodiment 1. However, the method for manufacturing the gas generator disclosed in the present application is not limited to the following method. Figure 7 1 is a flow chart of a method for manufacturing a gas generator according to Embodiment 1. Figure 7 As shown, the gas generator assembly method of Embodiment 1 includes a preparation step of step S101 , a gas discharge hole forming step of step S102 , a blocking member mounting step of step S103 , and an assembly step of step S104 .

[0087] First, in the preparation process of step S101, the first ignition device 4, the first inner cylinder member 5, the explosive 6, the second ignition device 7, the second inner cylinder member 8, the filter 9, the upper shell 2, the lower shell 3, the first gas generating agent 110, the second gas generating agent 120 and the sealing tape S1 are prepared.

[0088] Next, in the gas discharge hole forming process of step S102, a plurality of gas discharge holes H1 are formed in the housing 1 in such a manner that the rupture pressure of the sealing tape S1 is different in the first small hole 13a and the second small hole 13b. Specifically, a plurality of large holes 12 and a plurality of small holes 13 are formed by punching the upper peripheral wall portion 21 of the upper housing 2 by punching. In the punching process of the large hole 12, a punch having a larger diameter than the punch used for the punching process of the small hole 13 is used. Thus, the minimum flow path cross-sectional area of ​​the large hole 12 is larger than the minimum flow path cross-sectional area of ​​the small hole 13. As a result, the gas discharge amount per unit time of the large hole 12 is greater than the gas discharge amount per unit time of the small hole 13.

[0089] In forming the plurality of small holes 13, punching is performed so that the rupture pressure of the sealing tape S1 at the first small hole 13a and the rupture pressure of the sealing tape S1 at the second small hole 13b are different from each other. Figure 8 1 is a cross-sectional view for explaining a method of forming the first small hole 13a of Embodiment 1. Fig. 9 This is a cross-sectional view for explaining a method of forming the second small hole 13b in Embodiment 1. The first small hole 13a and the second small hole 13b are formed by punching using punches having the same diameter. Figure 8 and Fig. 9 The reference numeral 200 indicates a punch used for processing. Figure 8 As shown in FIG. 1 , the first small hole 13a is formed by punching from the outer surface 11b side of the housing 1 by punching. As a result, in the first small hole 13a, a straight tube portion 131 formed by a shear surface is formed on the outer surface 11b side of the housing 1, and a tapered portion 132 formed by a fracture surface is formed on the inner surface 11a side of the housing 1. Fig. 9 As shown, the second small hole 13b is formed by punching from the inner surface 11a side of the housing 1. Thus, in the second small hole 13b, a straight portion 131 is formed on the inner surface 11a side of the housing 1, and a tapered portion 132 is formed on the outer surface 11b side of the housing 1.

[0090] In the process of forming the gas discharge hole, the punch 200 having the same diameter is used in the first small hole 13a and the second small hole 13b, so that the straight tube portion 131 having the same diameter is formed in the first small hole 13a and the second small hole 13b, respectively. As a result, the minimum flow path cross-sectional area A1 of the first small hole 13a is equal to the minimum flow path cross-sectional area A2 of the second small hole 13b. In addition, in the process of forming the gas discharge hole, the punching directions in the first small hole 13a and the second small hole 13b are opposite to each other, so that the positional relationship between the straight tube portion 131 and the tapered portion 132 in the first small hole 13a and the second small hole 13b is opposite to each other. As a result, the circumferences of the opening portion 13a1 of the first small hole 13a and the opening portion 13b1 of the second small hole 13b are different from each other. In this example, the circumference P1 of the opening portion 13a1 of the first small hole 13a is longer than the circumference P2 of the opening portion 13b1 of the second small hole 13b.

[0091] Next, in the assembly process of the blocking member in step S103, the sealing tape S1 is assembled on the inner surface 11a of the housing 1 in such a manner as to cover the openings on the inner surface 11a side of the housing 1 of the plurality of gas discharge holes H1. Thus, the plurality of gas discharge holes H1 are blocked. In this example, all the large holes 12 are blocked collectively by one piece of sealing tape S1, and all the small holes 13 are blocked collectively by another piece of sealing tape S1. Therefore, the first small hole 13a and the second small hole 13b are blocked by the sealing tape S1 of the same specification.

[0092] Next, in the assembly process of step S104, the first ignition device 4 and the second ignition device 7 are assembled on the lower housing 3, the first inner cylinder member 5 filled with the ignition powder 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. After that, the filter 9 is arranged on the lower housing 3, and the first gas generating agent 110 is filled inside the filter 9. Finally, the upper housing 2 is covered on the lower housing 3, and the joint portion 23 of the upper housing 2 and the joint portion 33 of the lower housing 3 are overlapped and joined by laser welding or the like, thereby forming the housing 1. As described above, the gas generator 100 is assembled.

[0093] [action]

[0094] Below, refer to Figure 1 , the basic operation of the gas generator 100 according to Embodiment 1 will be described. In this example, the case where the second ignition device 7 is operated later than the first ignition device 4 (that is, after the first ignition device 4 is operated) will be described.

[0095] When the sensor (not shown) senses the impact, the ignition current is supplied to the first igniter 41 of the first ignition device 4, and the first igniter 41 operates. Then, the detonator contained in the first igniter 41 burns, and the flame, high-temperature gas, etc. as the combustion products are discharged into the ignition chamber 53. As a result, the ignition powder 6 contained in the ignition chamber 53 burns, and combustion gas is generated in the ignition chamber 53. When the sealing tape that blocks the communication hole h1 of the surrounding wall portion 51 of the first inner cylinder member 5 is ruptured due to the pressure of the combustion gas of the ignition powder 6, the combustion gas is discharged to the outside of the ignition chamber 53 through the communication hole h1. Then, the combustion gas of the ignition powder 6 contacts the first gas generating agent 110 arranged around the surrounding wall portion 51, and the first gas generating agent 110 is ignited. The first gas generating agent 110 burns, thereby generating high-temperature / high-pressure combustion gas in the first combustion chamber 10. The sealing tape S1 is ruptured by the pressure of the combustion gas, thereby opening a plurality of gas discharge holes H1. The combustion gas is cooled and combustion residues are collected by passing through the filter 9. The combustion gas of the first gas generating agent 110 cooled and filtered by the filter 9 is discharged to the outside of the housing 1 through the plurality of gas discharge holes H1.

[0096] Next, when the second igniter 71 of the second ignition device 7 is operated, the second gas generating agent 120 contained in the second combustion chamber 20 is burned, and combustion gas is generated in the second combustion chamber 20. When the sealing tape that blocks the communication hole h2 of the surrounding wall portion 81 of the second inner cylinder member 8 is ruptured by the pressure of the combustion gas of the second gas generating agent 120, the combustion gas is discharged to the first combustion chamber 10 through the communication hole h2. The combustion gas of the second gas generating agent 120 is cooled and filtered by the filter 9, and then discharged to the outside of the housing 1 through the plurality of gas discharge holes H1.

[0097] 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. The airbag expands to form a buffer between the occupant and a hard structure, thereby protecting the occupant from impact.

[0098] [About the opening timing]

[0099] Furthermore, generally, the combustion performance of the gas generator tends to improve as the temperature or pressure around the gas generator increases. That is, the combustion of the gas generator is not active in a low temperature / low pressure environment. Therefore, in order to reduce the output performance difference of the gas generator when operating at high temperature (high temperature operation) and when operating at low temperature (low temperature operation) and stabilize the output performance, it is necessary to maintain the internal pressure of the shell during low temperature operation, especially in the initial stage when the gas generator starts to burn.

[0100] As described above, in the gas generator 100 of the first embodiment, the rupture pressure of the sealing band S1 at the large hole 12 is set to be lower than the rupture pressure of the sealing band S1 at the small hole 13. For example, it is assumed that the first igniter 41 and the second igniter 71 are operated simultaneously during low-temperature operation, and the first gas generating agent 110 and the second gas generating agent 120 are all burned. In this case, in the initial stage, only the large hole 12 among the plurality of gas discharge holes H1 opens as the internal pressure of the housing 1 rises. As a result, a part of the combustion gas is discharged, and the internal pressure of the housing 1 is reduced, but the small hole 13 is blocked, so the combustion performance of the gas generating agent is maintained. Then, when the internal pressure of the housing 1 further increases as the gas generating agent burns, the small hole 13 opens later than the large hole 12. However, at this time, when all the small holes 13 (all the first small holes 13a and all the second small holes 13b) are opened at once, the internal pressure of the housing 1 drops sharply, and the combustion performance of the gas generating agent may be reduced. In contrast, in the gas generator 100 of the first embodiment, the rupture pressure of the sealing tape S1 is slightly different between the first small hole 13a and the second small hole 13b, thereby making the opening ease different between the first small hole 13a and the second small hole 13b. Therefore, the first small hole 13a having a relatively low rupture pressure opens earlier, and the second small hole 13b having a relatively high rupture pressure opens later. By making the opening timing different between the first small hole 13a and the second small hole 13b so that all the small holes 13 are not opened at once, the internal pressure of the housing 1 is suppressed from dropping sharply, and the combustion performance of the gas generating agent is maintained.

[0101] [Function / Effect]

[0102] As described above, the gas generator 100 of the first embodiment includes: a housing 1 in which the first igniter 41 and the first gas generating agent 110 are accommodated; a plurality of gas discharge holes H1 penetrating the inside and outside of the housing 1; and a sealing tape S1 mounted on the inner surface 11a of the housing 1. The sealing tape S1 covers the openings of the plurality of gas discharge holes H1 on the inner surface 11a side of the housing 1 before the operation of the gas generator 100, thereby blocking the plurality of gas discharge holes H1, and is ruptured by the pressure of the combustion gas generated in the housing 1 by the operation of the gas generator 100, thereby opening the plurality of gas discharge holes H1. The plurality of gas discharge holes H1 include at least one first small hole 13a and one second small hole 13b, each of which has different rupture pressures of the sealing tape S1. Moreover, the minimum cross-sectional area A1 of the gas flow path formed by the first small hole 13a is equal to the minimum cross-sectional area A2 of the gas flow path formed by the second small hole 13b. In the first small hole 13a and the second small hole 13b, the circumferences of the openings on the inner surface 11a side of the shell 1 are different so that their rupture pressures are different.

[0103] According to the gas generator 100 configured as described above, the minimum flow path cross-sectional area for controlling the gas discharge amount is made equal in the first small hole 13a and the second small hole 13b, so that the gas discharge amount per unit time of the first small hole 13a and the gas discharge amount per unit time of the second small hole 13b can be made equal. In addition, the circumference of the opening portion on the inner surface 11a side of the housing 1 is made different in the first small hole 13a and the second small hole 13b, so that the rupture pressure of the first small hole 13a and the rupture pressure of the second small hole 13b can be made different. That is, two types of gas discharge holes having the same internal pressure control function of the housing 1 and different opening easiness can be intentionally set. As a result, the timing of opening can be made different in the first small hole 13a and the second small hole 13b, and a sharp drop in the internal pressure of the housing 1 can be suppressed at the initial stage of operation of the gas generator 100. As a result, the combustion performance of the gas generating agent can be maintained, and the output performance of the gas generator 100 can be stabilized.

[0104] In the gas generator 100 of the first embodiment, the first small hole 13a and the second small hole 13b are blocked by the sealing tape S1 of the same specification. That is, the difference in the rupture pressure is generated by the difference in the properties (perimeter) of the opening 13a1 of the first small hole 13a and the opening 13b1 of the second small hole 13b, rather than by the difference in the specification of the sealing tape S1. Therefore, it is not necessary to make the specifications of the sealing tape S1 different in the first small hole 13a and the second small hole 13b, so that all the small holes 13 can be blocked with a common (one piece) sealing tape S1. However, the technology disclosed in the present invention can also make the specifications of the blocking member different in the first gas discharge hole and the second gas discharge hole.

[0105] It should be noted that, in the gas generator 100 of the first embodiment, the cracking pressure of the first small hole 13a is configured to be lower than the cracking pressure of the second small hole 13b, but in the technology disclosed in the present invention, the magnitude relationship between the cracking pressure of the first gas discharge hole and the cracking pressure of the second gas discharge hole is not limited to the above. The cracking pressure of the first gas discharge hole may be higher than the cracking pressure of the second gas discharge hole. In addition, in the gas generator 100 of the first embodiment, the large hole 12 and the small hole 13 having different minimum flow path cross-sectional areas are included in the plurality of gas discharge holes H1, but in the technology disclosed in the present invention, it is not necessary to have a plurality of gas discharge holes having different minimum flow path cross-sectional areas.

[0106] Furthermore, in the technology disclosed herein, the plurality of gas discharge holes may include, in addition to the first gas discharge hole and the second gas discharge hole, gas discharge holes having the same minimum flow path cross-sectional area and a plugging member having a rupture pressure different from that of the first gas discharge hole and the second gas discharge hole. That is, there may be three or more gas discharge holes having the same minimum flow path cross-sectional area and a plugging member having a different rupture pressure.

[0107] In the gas generator 100 of the first embodiment, the first small hole 13a and the second small hole 13b are formed as holes with a circular cross section, and the apertures (D1, D2) of the openings (13a1, 13b1) on the inner surface 11a side of the housing 1 in the first small hole 13a and the second small hole 13b are different from each other. Thus, the perimeters (P1, P2) of the openings on the inner surface 11a side of the housing 1 can be made different from each other in the first small hole 13a and the second small hole 13b. It should be noted that in the technology disclosed in the present invention, the cross-sectional shape of the first gas discharge hole and the second gas discharge hole, and the shape of the openings of the first gas discharge hole and the second gas discharge hole are not limited to a circle, and various shapes such as an ellipse, an oblong, a polygon, etc. may also be used as described later.

[0108] In addition, the first small hole 13a and the second small hole 13b of the first embodiment include: a straight tube portion 131 whose cross section is constant in the thickness direction of the housing 1; and a tapered portion 132, which is connected to the straight tube portion 131 and whose cross-sectional area increases as it moves away from the straight tube portion 131 in the thickness direction. In one of the first small hole 13a and the second small hole 13b (the first small hole 13a), the tapered portion 132 opens on the inner surface 11a side of the housing 1, and the straight tube portion 131 opens on the outer surface 11b side of the housing 1. In addition, in the other side (the second small hole 13b), the straight tube portion 131 opens on the inner surface 11a side of the housing 1, and the tapered portion 132 opens on the outer surface 11b side of the housing 1. In this way, the positional relationship between the straight tube portion 131 and the tapered portion 132 is configured to be opposite to each other in the first small hole 13a and the second small hole 13b, so that the minimum flow path cross-sectional area in the first small hole 13a and the second small hole 13b can be equal, and the rupture pressure of the sealing band S1 can be different. It should be noted that in the technology disclosed in the present invention, the tapered portion of the second gas discharge hole (second small hole 13b) can be opened on the inner surface side of the shell and the straight tube portion can be opened on the outer surface side of the shell, and the straight tube portion of the first gas discharge hole (first small hole 13a) can be opened on the inner surface side of the shell and the tapered portion can be opened on the outer surface side of the shell.

[0109] In the gas generator 100 of the first embodiment, the straight tube portion 131 is formed by a shear surface, and the tapered portion 132 is formed by a fracture surface. Such a gas discharge hole H1 having the straight tube portion 131 and the tapered portion 132 can be appropriately formed by punching. However, in the technology disclosed herein, the method of forming the first gas discharge hole and the second gas discharge hole in the housing is not limited to punching. For example, the first gas discharge hole and the second gas discharge hole may also be drilled by a drill.

[0110] Here, if Figure 3 and Figure 5As shown, the thickness of the housing 1 is set to t1, and the length of the straight tube portion 131 of the small hole 13 in the thickness direction of the housing 1 is set to t2. At this time, it can be set that 0.3 < t2 / t1 < 0.7. Such a gas discharge hole H1 can be appropriately formed by punching. However, in the technology of the present disclosure, the relationship between the thickness of the housing and the length of the straight tube portion is not limited to the above.

[0111] In addition, the manufacturing method of the gas generator 100 according to the first embodiment includes the following steps: forming a plurality of gas discharge holes H1 including at least one first small hole 13a and one second small hole 13b in the housing 1; and assembling a sealing tape S1 on the inner surface 11a of the housing 1 so as to cover the opening on the inner surface 11a side of the housing 1 where the plurality of gas discharge holes H1 are located. In the step of forming a plurality of gas discharge holes H1 in the housing 1, the minimum flow path cross-sectional area A1 of the gas flow path formed by the first small hole 13a is made equal to the minimum flow path cross-sectional area A2 of the gas flow path formed by the second small hole 13b, and the circumferences of the openings on the inner surface 11a side of the housing 1 in the first small hole 13a and the second small hole 13b are made different from each other. In this way, in the manufacturing method of the gas generator 100, a plurality of gas discharge holes H1 are formed in the housing 1 in such a manner that the cracking pressure of the sealing tape S1 is different in the first small hole 13a and the second small hole 13b. By this manufacturing method, the opening timing can be made different in the first small hole 13a and the second small hole 13b, and a sharp drop in the internal pressure of the housing 1 can be suppressed. That is, a gas generator 100 with stable output performance can be manufactured.

[0112] In addition, in the manufacturing method of the gas generator 100 according to the first embodiment, in the step of forming a plurality of gas discharge holes H1 in the housing 1, the first small hole 13a is formed by punching through from the outer surface 11b side of the housing 1, and the second small hole 13b is formed by punching through from the inner surface 11a side of the housing 1. That is, the punching directions in the first small hole 13a and the second small hole 13b are opposite to each other. Thereby, the circumferences of the openings on the inner surface 11a side of the housing 1 in the first small hole 13a and the second small hole 13b can be made different from each other. It should be noted that the difference in the circumferences of the openings of the gas discharge holes on the inner surface 11a side of the housing 1 can also be applied to the large hole 12 in addition to the first small hole 13a and the second small hole 13b.

[0113] [Modification Example 1 of the First Embodiment]

[0114] Hereinafter, the gas generator 100 of the modification example of the first embodiment will be described. In the description of the modification example, the description will be centered on the differences from the Figures 1 to 9 scheme described above, and for the same points, detailed description will be omitted.

[0115] [Modification Example 1 of the First Embodiment]

[0116] Fig.10 FIG. 1 is an enlarged cross-sectional view for explaining the shape of the second small hole 13 b of the first modification of the first embodiment. Fig.10 The figure shows the equivalent of Figure 5 In addition, Fig.10 The cross-sectional view C3 shows a cross section of the second small hole 13 b which is perpendicular to the thickness direction of the housing 1 .

[0117] The second small hole 13b of the modification example 1 is formed as a hole having a circular cross section. Figure 5 The difference of the second small hole 13b shown in the figure is that the cross section is constant from the opening 13b1 on the inner surface 11a side of the housing 1 to the opening 13b2 on the outer surface 11b side. That is, the second small hole 13b of the modification example 1 does not have the same cross section as the second small hole 13b shown in the modification example 1. Figure 5 The tapered portion 132 is shown. Therefore, the cross-sectional area of ​​the gas flow path formed by the second small hole 13b of the modification 1 is constant in the thickness direction of the housing 1 at the minimum flow path cross-sectional area A2.

[0118] In the first modification, the minimum flow path cross-sectional areas (A1, A2) are combined in such a way that they are equal. Figure 3 The first small hole 13a and Fig.10 As a result, the diameter D1 of the opening 13a1 on the inner surface 11a side of the first small hole 13a is larger than the diameter D2 of the opening 13b1 on the inner surface 11a side of the second small hole 13b. As a result, the circumference P1 of the opening 13a1 of the first small hole 13a is longer than the circumference P2 of the opening 13b1 of the second small hole 13b, so the rupture pressure of the first small hole 13a is lower than the rupture pressure of the second small hole 13b. As described above, in the gas generator 100 of the modified example 1, the minimum flow path cross-sectional area is equal in the first small hole 13a and the second small hole 13b, and the rupture pressures of the blocking members are different from each other.

[0119] [Variation 2 of Implementation Example 1]

[0120] Fig.11 FIG. 2 is an enlarged cross-sectional view for explaining the shape of the first small hole 13a of the second modification of the first embodiment. Fig.11 The figure shows the equivalent of Figure 3 In addition, Fig.11 The end view E1 shows the opening portion 13a2 of the first small hole 13a on the outer surface 11b side of the housing 1. Fig.12 FIG. 2 is an enlarged cross-sectional view for explaining the shape of the second small hole 13 b of the second modification example of the first embodiment. Fig.12 The figure shows the equivalent of Figure 5 In addition, Fig.12The end view E2 shows the opening portion 13b1 of the second small hole 13b on the inner surface 11a side of the shell 1. The first small hole 13a and the second small hole 13b of the modification example 2 are formed as holes with a circular cross-section. The first small hole 13a of the modification example 2 is formed so that the cross-sectional area increases from the opening portion 13a2 on the outer surface 11b side of the shell 1 toward the opening portion 13a1 on the inner surface 11a side. On the other hand, the second small hole 13b of the modification example 2 is formed so that the cross-sectional area increases from the opening portion 13b1 on the inner surface 11a side of the shell 1 toward the opening portion 13b2 on the outer surface 11b side. That is, the first small hole 13a and the second small hole 13b of the modification example 2 do not have the same cross-sectional area as shown in FIG. Figure 3 , Figure 5 The straight tube portions 131 are shown with the tapers facing in opposite directions.

[0121] like Fig.11 As shown in FIG. 1 , the first small hole 13a of the second modification has the smallest flow path cross-sectional area at the opening 13a2 on the outer surface 11b side of the housing 1. Fig.12 As shown, in the second small hole 13 b of the second modification example, the flow path cross-sectional area is smallest at the opening 13 b 1 on the inner surface 11 a side of the housing 1 .

[0122] In variant example 2, the minimum flow path cross-sectional area A1 of the first small hole 13a is equal to the minimum flow path cross-sectional area A2 of the second small hole 13b. Therefore, the diameter D1 of the opening portion 13a1 on the inner surface 11a side of the first small hole 13a is larger than the diameter D2 of the opening portion 13b1 on the inner surface 11a side of the second small hole 13b. As a result, the circumference P1 of the opening portion 13a1 of the first small hole 13a is longer than the circumference P2 of the opening portion 13b1 of the second small hole 13b, so that the rupture pressure of the first small hole 13a can be lower than the rupture pressure of the second small hole 13b. As described above, in the gas generator 100 of variant example 2, the minimum flow path cross-sectional areas are equal in the first small hole 13a and the second small hole 13b and the rupture pressures of the blocking components are different. In addition, it is also possible to Figure 10 to Figure 12 The solution is applied to the large hole 12, and two large holes 12 with the same minimum flow path cross-sectional area but slightly different bursting pressures are set.

[0123] <Implementation Method 2>

[0124] The following describes a gas generator 100 according to Embodiment 2. Embodiment 2 corresponds to a solution that can be adopted by the technology disclosed in the present invention, in which the shape of the opening of the first gas discharge hole on the inner surface side of the shell is different from the shape of the opening of the second gas discharge hole on the inner surface side of the shell. Figures 1 to 12 The description will focus on the differences from the scheme of embodiment 1 described in , and detailed description of the same points will be omitted.

[0125] Fig.13 FIG. 1 is an enlarged cross-sectional view for explaining the shape of the first small hole 13a in Embodiment 2. Fig.13 The figure shows the equivalent of Figure 3 In addition, Fig.13 The cross-sectional view C4 shows a cross section of the first small hole 13 a that is perpendicular to the thickness direction of the housing 1 . Fig.14 FIG. 2 is an enlarged cross-sectional view for explaining the shape of the second small hole 13 b of the second modification example of the first embodiment. Fig.12 The figure shows the equivalent of Figure 5 In addition, Fig.14 The cross-sectional view C5 shows a cross section of the second small hole 13b perpendicular to the thickness direction of the housing 1. The first small hole 13a and the second small hole 13b of the second embodiment are formed as holes with a circular cross section, and the cross section is constant from the opening on the inner surface 11a side to the opening on the outer surface 11b side of the housing 1. In the second embodiment, the minimum flow path cross-sectional area A1 of the first small hole 13a is equal to the minimum flow path cross-sectional area A2 of the second small hole 13b.

[0126] like Fig.12 As shown, the first small hole 13a of the second embodiment has a protrusion 133 protruding toward the inside of the shell 1 formed around the opening 13a1 on the inner surface 11a side of the shell 1. The protrusion 133 is, for example, a burr generated when the first small hole 13a is processed. For example, in the process of forming a plurality of gas exhaust holes H1 in the shell 1, the first small hole 13a can be drilled from the outer surface 11b side of the shell 1 by punching or drilling, and the burr generated in the opening 13a1 on the inner surface 11a side of the shell 1 is not removed and remains, thereby forming the protrusion 133. Fig.13 As shown, the sealing tape S1 is mounted on the inner surface 11a of the housing 1 in a manner covering the protrusion 133. When the gas generating agent 110, 120 burns during the operation of the gas generator 100, the sealing tape S1 is pressed against the periphery of the opening 13a1 of the first small hole 13a by the pressure of the combustion gas. At this time, the protrusion 133 presses the sealing tape S1 in a manner of piercing the sealing tape S1, so that the sealing tape S1 is more likely to crack than when the protrusion 133 is not formed. That is, by forming the protrusion 133, the cracking pressure of the sealing tape S1 at the first small hole 13a is reduced.

[0127] like Fig.14As shown, in the second embodiment, the chamfered portion 134 is formed by C chamfering at the periphery of the opening 13b1 on the inner surface 11a side of the shell 1 of the second small hole 13b. For example, in the process of forming a plurality of gas discharge holes H1 in the shell 1, the second small hole 13b can be drilled from the outer surface 11b side of the shell 1 by punching or drilling, and the opening 13b1 on the inner surface 11a side of the shell 1 is chamfered to form the chamfered portion 134. The chamfered portion 134 is not limited to C chamfering, and may also be other shapes such as R chamfering. Fig.13 As shown in FIG. 1 , the sealing tape S1 is mounted on the inner surface 11a of the housing 1 in a manner covering the chamfered portion 134. When the gas generating agents 110 and 120 burn, the sealing tape S1 is pressed against the periphery of the opening 13b1 of the second small hole 13b by the pressure of the combustion gas, but the chamfered portion 134 removes the corner of the periphery, so that the shear force is less likely to act on the sealing tape S1 than when the chamfered portion 134 is not formed, and the sealing tape S1 is less likely to rupture. That is, by forming the chamfered portion 134, the rupture pressure of the sealing tape S1 at the second small hole 13b is increased.

[0128] As described above, in the gas generator 100 of the second embodiment, in the process of forming the plurality of gas discharge holes H1 in the housing 1, the shapes of the openings on the inner surface 11a side of the housing 1 are made different in the first small hole 13a and the second small hole 13b. Therefore, in the gas generator 100 of the second embodiment, the minimum flow path cross-sectional areas are equal in the first small hole 13a and the second small hole 13b, and the rupture pressures of the sealing band S1 are different. As a result, the output performance of the gas generator 100 can be stabilized.

[0129] It should be noted that, in Embodiment 2, a protrusion 133 is formed on the first small hole 13a and a chamfer 134 is formed on the second small hole 13b, but the technology disclosed in the present invention is not limited thereto. A protrusion is formed on at least a portion of the periphery of the opening portion on the inner surface side of the shell of only one of the first gas discharge hole (first small hole 13a) and the second gas discharge hole (second small hole 13b), so that the cracking pressures in the first gas discharge hole and the second gas discharge hole can be different from each other. For example, one of the first gas discharge hole and the second gas discharge hole is drilled out from the outer surface side of the shell by punching or drilling, and the other is drilled out from the inner surface side of the shell by punching, thereby forming a protrusion on at least a portion of the opening portion on the inner surface side of only one of the shells. In addition, the periphery of the opening portion on the inner surface side of the shell of only one of the first gas discharge hole and the second gas discharge hole is chamfered, so that the cracking pressures in the first gas discharge hole and the second gas discharge hole can be different from each other. Moreover, it is also possible to Fig.13 , Fig.14The shape shown is applied to the large holes 12, and two types of large holes 12 having the same minimum flow path cross-sectional area but slightly different bursting pressures are provided.

[0130] [Variation of Embodiment 2]

[0131] In the second embodiment, the planar shape of the periphery of the opening portion on the inner surface 11 a side of the housing 1 may be different between the first small hole 13 a and the second small hole 13 b . Fig.15 1 and 10 are diagrams showing an example of the shape of the opening of the small hole 13 on the inner surface 11 a side of the housing 1 . Fig.15 (A) indicates a circular opening. Fig.15 (B) indicates that the opening is an ellipse. Fig.15 (C) indicates the case where the opening is a rectangle (rectangle), Fig.15 (D) represents the case where the opening is a square. It should be noted that Fig.15 The shapes shown are only examples. Fig.15 In addition to the shapes shown as examples, various shapes such as an oval, a polygon other than a quadrilateral, etc. can be adopted.

[0132] For example, the opening 13a1 of the first small hole 13a and the opening 13b1 of the second small hole 13b can be respectively Fig.15 Different shapes can be selected from (A) to (D). In this way, the rupture pressure of the sealing band S1 can be different in the first small hole 13a and the second small hole 13b. For example, the first small hole 13a can be set as an elliptical hole with a constant cross-section, and the second small hole 13b can be set as a circular hole with a constant cross-section and a flow path cross-sectional area equal to that of the first small hole 13a. When compared with equal areas, the perimeter of the ellipse is longer than the perimeter of the circle. In addition, for example, the first small hole 13a can be set as a rectangular hole with a constant cross-section, and the second small hole 13b can be set as a square hole with a constant cross-section and a flow path cross-sectional area equal to that of the first small hole 13a. When compared with equal areas, the perimeter of the rectangle is longer than the perimeter of the square. In any of the above examples, the perimeter P1 of the opening 13a1 of the first small hole 13a is longer than the perimeter P2 of the opening 13b1 of the second small hole 13b. That is, in the first small hole 13a and the second small hole 13b, not only the shape of the opening on the inner surface 11a side of the housing 1 can be made different, but also the circumference of the opening can be made different, so that the rupture pressure can be appropriately made different. It should be noted that such a difference in shape can also be applied to the large hole 12, and two types of large holes 12 with the same minimum flow path cross-sectional area but slightly different rupture pressures can be provided.

[0133] <Others>

[0134] The preferred embodiments of the present disclosure are described above, but the various schemes disclosed in this specification may also be combined with any other features disclosed in this specification. It should be noted that in Embodiment 1, a scheme in which the perimeters of the openings on the inner surface side of the shell in the first gas discharge hole and the second gas discharge hole are different from each other is described, and in Embodiment 2, a scheme in which the shapes of the openings are different from each other is described, but the shapes and perimeters of the openings may be different from each other in the first gas discharge hole and the second gas discharge hole. That is, the technology of the present disclosure only needs at least one of the shapes and perimeters of the openings on the inner surface side of the shell in the first gas discharge hole and the second gas discharge hole to be different from each other. It should be noted that even in the case where there are multiple gas discharge holes with different shapes and perimeters of the openings on the inner surface side of the shell, the case in which the difference in shape and perimeter is considered to be within the range of the processing tolerance of the gas discharge hole is excluded from the technology of the present disclosure. In addition, in the above-mentioned embodiment, an example of a so-called two-stage gas generator with two igniters is shown, but even in a case in which only one, such as Japanese Patent Publication No. 2019-156107, is provided, the gas generator is not included in the present invention. Figure 1 The so-called single-stage gas generator of the igniter shown can also obtain the same effect as the above-mentioned embodiment when the technology of the present disclosure is applied. For example, it is assumed that at least two gas discharge holes (first gas discharge hole and second gas discharge hole) with equal gas discharge amount per unit time (internal pressure control function of the shell) and different cracking pressure (opening ease) of the blocking member are provided in the single-stage gas generator. Even in this case, when the gas generator is working, the opening timing of the first gas discharge hole is different from the opening timing of the second gas discharge hole, that is, the gas discharge hole is opened in multiple stages, so that, for example, when working at low temperature, the internal pressure can be suppressed from dropping sharply, and the combustion performance at normal temperature or close to high temperature can be exhibited. It should be noted that the purpose of the technology of the present disclosure is to control the internal pressure of the shell when the gas generator is working. If the method of use can adjust the timing of the opening of the first gas discharge hole and the second gas discharge hole, it is not limited to the application only in the case where the ambient temperature during operation is different as in the above-mentioned embodiment.

[0135] Description of Reference Numerals

[0136] 100: Gas generator;

[0137] 1: Shell;

[0138] 41: first igniter (an example of an igniter);

[0139] 110: a first gas generating agent (an example of a gas generating agent);

[0140] H1: gas discharge hole;

[0141] 13a: a first small hole (an example of a first gas discharge hole);

[0142] 13b: a second small hole (an example of a second gas discharge hole);

[0143] S1: Sealing tape (an example of a blocking member).

Claims

1. A gas generator comprising: Igniter; a gas generating agent that burns through the operation of the igniter to generate combustion gas; a housing, accommodating the igniter and the gas generating agent therein; A plurality of gas exhaust holes extending through the inside and outside of the shell; and a blocking member, which is mounted on the inner surface of the housing and covers the openings of the inner surface of the housing of the plurality of gas discharge holes before the igniter is operated, thereby blocking the plurality of gas discharge holes, and is ruptured by the pressure of the combustion gas generated by the operation of the igniter, thereby opening the plurality of gas discharge holes. The plurality of gas discharge holes include at least one first gas discharge hole and one second gas discharge hole that have different rupture pressures of the blocking member. The minimum cross-sectional area of ​​the gas flow path formed by the first gas discharge hole is equal to the minimum cross-sectional area of ​​the gas flow path formed by the second gas discharge hole. The first gas discharge hole and the second gas discharge hole are different from each other in at least one of the shape and the perimeter of the opening on the inner surface side of the housing.

2. The gas generator according to claim 1, wherein: The first gas discharge hole and the second gas discharge hole are blocked by the blocking members having the same specifications.

3. The gas generator according to claim 1 or 2, wherein: The first gas exhaust hole and the second gas exhaust hole are holes with circular cross-sections. The first gas discharge hole and the second gas discharge hole have openings on the inner surface side of the housing that have different hole diameters.

4. The gas generator according to claim 1 or 2, wherein: The first gas discharge hole and the second gas discharge hole include: a straight tube portion whose cross section is constant in the thickness direction of the shell; and a tapered portion connected to the straight tube portion and having a cross-sectional area increasing as it moves away from the straight tube portion in the thickness direction, In one of the first gas discharge hole and the second gas discharge hole, the tapered portion opens on the inner surface side of the housing, and the straight portion opens on the outer surface side of the housing. In the other of the first gas discharge hole and the second gas discharge hole, the straight tube portion opens on the inner surface side of the housing, and the tapered portion opens on the outer surface side of the housing.

5. The gas generator according to claim 4, wherein: The straight tube portion is formed by a shear surface, The tapered portion is formed by a fracture surface.

6. The gas generator according to claim 4, wherein: When the thickness of the shell is t1 and the length of the straight tube portion in the thickness direction of the shell is t2, 0.3 <t2 / t1<0.7。 7. The gas generator according to claim 1 or 2, wherein: A protrusion protruding toward the inside of the housing is formed on at least a portion of the periphery of the opening of only one of the first gas discharge hole and the second gas discharge hole on the inner surface side of the housing, The blocking member is mounted on the inner surface of the housing so as to cover the protrusion.

8. The gas generator according to claim 1 or 2, wherein: The peripheral edge of the opening of only one of the first gas discharge hole and the second gas discharge hole on the inner surface side of the housing is chamfered.

9. A method for manufacturing a gas generator, the gas generator comprising: an igniter; a gas generating agent that burns when the igniter is operated to generate combustion gas; a housing that accommodates the igniter and the gas generating agent; and a plurality of gas discharge holes that penetrate inside and outside of the housing; and a blocking member for blocking the plurality of gas discharge holes, the manufacturing method of the gas generator comprising the following steps: forming a plurality of gas discharge holes including at least one first gas discharge hole and one second gas discharge hole in the housing in such a manner that the rupture pressure of the blocking member is different between the first gas discharge hole and the second gas discharge hole; as well as The blocking member is mounted on the inner surface of the housing so as to cover the openings of the plurality of gas discharge holes on the inner surface side of the housing. In the process of forming the multiple gas exhaust holes in the shell, the minimum cross-sectional area of ​​the gas flow path formed by the first gas exhaust holes is made equal to the minimum cross-sectional area of ​​the gas flow path formed by the second gas exhaust holes, and in the first gas exhaust holes and the second gas exhaust holes, at least one of the shape and the circumference of the opening on the inner surface side of the shell is different from each other.

10. The method for manufacturing a gas generator according to claim 9, wherein: In the step of forming the plurality of gas discharge holes in the housing, punching a hole from the outer surface of the housing to form one of the first gas discharge hole and the second gas discharge hole, The other of the first gas discharge hole and the second gas discharge hole is formed by punching from the inner surface side of the housing.

11. The method for manufacturing a gas generator according to claim 9, wherein: In the step of forming the plurality of gas discharge holes in the housing, An opening portion of only one of the first gas discharge hole and the second gas discharge hole on the inner surface side of the housing is chamfered.

12. The method for manufacturing a gas generator according to any one of claims 9 to 11, wherein: In the step of attaching a blocking member to the inner surface of the housing, the first gas discharge hole and the second gas discharge hole are blocked by the blocking member having the same specification.

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