Gas generator

Abstract

To provide a gas generator capable of preventing abnormal operation such as breakage of a housing from being induced.SOLUTION: The gas-generator 1A includes a gas-generating-agent-storing chamber S1 and a filter-chamber S2. A partition member 50 for partitioning a space inside the housing into a gas generating agent storage chamber S1 and a filter chamber S2 is arranged in the housing, and the filter 90 divides the filter chamber S2 into an inner space S2A and an outer space S2B and abuts on the partition member 50. The housing has a gas discharge opening in a portion defining the outer space S2B. A first fragile portion 53 that is cleaved by receiving a pressure exceeding a predetermined first pressure value is provided in a portion of the partition member 50 facing the inner space S2A, and a second fragile portion 54 that is cleaved by receiving a pressure exceeding a predetermined second pressure value higher than the first pressure value is provided in a portion of the partition member 50 facing the outer space S2B.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a gas generator to be incorporated in an airbag device as an occupant protection device equipped in an automobile or the like. [Background technology]

[0002] Airbag devices, which are passenger protection devices, have become widespread from the viewpoint of protecting passengers in automobiles, etc. Airbag devices are installed to protect passengers from impacts that occur during a vehicle collision, and the airbag instantly inflates and deploys during a vehicle collision, thereby acting as a cushion to support the passenger's body.

[0003] The gas generator is incorporated into this airbag device. When a vehicle crashes, an igniter is activated by electricity from the control unit. The flame generated in the igniter burns the gas generating agent, instantly generating a large amount of gas, which inflates and deploys the airbag.

[0004] Gas generators have a variety of configurations based on specifications such as the installation position relative to a vehicle or the like and output. One of these is what is called a cylinder-type gas generator. In general, a cylinder-type gas generator has a long, cylindrical outer shape and is suitably incorporated into a side airbag device, a passenger-side airbag device, a curtain airbag device, a knee airbag device, a seat cushion airbag device, or the like. Examples of documents disclosing such a cylinder-type gas generator include Japanese Patent Application Laid-Open No. 2023-87958 (Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2023-87958 Summary of the Invention [Problem to be solved by the invention]

[0006] In a gas generator, it is important to stably burn the gas generating agent when the igniter is activated. Here, in order to stably burn the gas generating agent, it is necessary to burn the gas generating agent in a predetermined high-pressure environment, and therefore the gas generator is designed so that the pressure inside the housing increases to a considerable pressure value when the igniter is activated, for example by narrowing the size of the gas outlet provided in the housing to a predetermined size.

[0007] On the other hand, if a fire breaks out in a vehicle equipped with an airbag system incorporating a gas generator, the gas generator may be heated from the outside, causing the temperature inside the gas generator to rise to several hundred degrees Celsius. In this case, if the temperature of the gas generant or transfer charge reaches its spontaneous ignition temperature, an abnormal operation will occur in which the gas generator activates without the igniter operating.

[0008] If such abnormal operation is induced, the gas generator itself will already be at a high temperature due to external heating, and the combustion of the gas generating agent will cause the pressure inside the housing to rise to a level much higher than the pressure required when the above-mentioned igniter is activated, which could cause the housing to rupture.

[0009] Therefore, the present invention has been made in consideration of the above-mentioned problems, and aims to provide a gas generator that can prevent the induction of abnormal operation that could cause the housing to break. [Means for solving the problem]

[0010] A gas generator according to the present invention comprises a housing, a partition member, and an igniter. The housing has a cylindrical peripheral wall portion, and one and the other axial ends are closed. The housing contains therein a gas generating agent storage chamber containing a gas generating agent, and a filter chamber in which a filter is disposed. The partition member is inserted into the peripheral wall portion so that the gas generating agent storage chamber is located at the one end and the filter chamber is located at the other end, thereby dividing the interior space of the housing in the axial direction of the peripheral wall portion. The igniter is assembled to the one end of the housing. The filter includes a hollow cylindrical portion at least at an end of the filter chamber on the one end side that divides the filter chamber into an inner space and an outer space in the radial direction of the peripheral wall portion. An end of the hollow cylindrical portion on the one end side abuts the partition member. The housing has a gas outlet in a portion that defines the outer space for ejecting gas to the outside. The portion of the partition member facing the inner space is provided with a first weak portion that ruptures when subjected to pressure exceeding a predetermined first pressure value, and the portion of the partition member facing the outer space is provided with a second weak portion that ruptures when subjected to pressure exceeding a predetermined second pressure value that is higher than the first pressure value. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a gas generator that can prevent the induction of abnormal operation that could cause the housing to break. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic view of a disk-type gas generator according to a first embodiment. FIG. [Figure 2] FIG. 2 is an enlarged view of region II shown in FIG. [Figure 3] FIG. 2 is an enlarged view of region III shown in FIG. [Figure 4] FIG. 2 is an enlarged view of region IV shown in FIG. [Figure 5]2 is a view of a partition member provided in the disk-type gas generator shown in FIG. 1, viewed from the filter chamber side. FIG. [Figure 6] FIG. 2 is a schematic diagram showing a gas flow during normal operation of the disk-type gas generator shown in FIG. [Figure 7] FIG. 2 is a diagram showing a gas flow during auto-ignition operation of the disk-type gas generator shown in FIG. [Figure 8] 10A to 10C are diagrams showing the configuration of a partition member according to first to fourth modified examples. [Figure 9] FIG. 10 is a schematic view of a disk-type gas generator according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The embodiments shown below exemplify the case where the present invention is applied to a cylinder-type gas generator incorporated in a side airbag device. In the embodiments shown below, the same or common parts are designated by the same reference numerals in the drawings, and their description will not be repeated.

[0014] (Embodiment 1) Fig. 1 is a schematic diagram of a cylinder-shaped gas generator according to embodiment 1. Figs. 2 to 4 are enlarged views of regions II, III and IV shown in Fig. 1, respectively. Also, Fig. 5 is a view of a partition member provided in the disk-shaped gas generator shown in Fig. 1, viewed from the filter chamber side. First, with reference to Figs. 1 to 5, the configuration of cylinder-shaped gas generator 1A according to the present embodiment will be described.

[0015] 1 to 4, cylinder-shaped gas generator 1A has a long, columnar outer shape, and has a long, substantially cylindrical housing whose one and other axial ends are closed. The housing forms the outer shell of cylinder-shaped gas generator 1A, and includes housing main body 10, holder 20, and closing member 30.

[0016] The housing accommodates internal components such as an igniter 40, a partition member 50, a plurality of granular gas generating agents 60, an auto-ignition agent 61, an isolating member 70, a coil spring 80, and a filter 90. The housing also accommodates a gas generating agent storage chamber S1 that accommodates the gas generating agent 60, the auto-ignition agent 61, the isolating member 70, and the coil spring 80, among the internal components described above, and a filter chamber S2 in which a filter 90 is disposed.

[0017] The housing body 10 constitutes the peripheral wall portion 11 of the housing and is made of a long cylindrical member with openings formed on both axial ends. The holder 20 is made of a tubular member with a through-hole 21 extending in a direction parallel to the axial direction of the housing body 10. The blocking member 30 is made of a substantially disk-shaped member.

[0018] The housing body 10 may be made of a metal member such as stainless steel, iron steel, aluminum alloy, or stainless alloy, or may be made of a press-formed product formed into a cylindrical shape by pressing a rolled steel plate such as SPCE.The housing body 10 may also be made of an electric resistance welded pipe such as STKM.

[0019] In particular, when the housing body 10 is constructed from a press-formed rolled steel plate or an electric resistance welded pipe, the housing body 10 can be formed more cheaply and easily than when metal components such as stainless steel or steel are used, and the weight can be significantly reduced.

[0020] On the other hand, the holder 20 and the closing member 30 are made of metal members such as stainless steel, iron steel, aluminum alloy, stainless alloy, or the like.

[0021] 1 and 2, holder 20 is assembled to housing body 10 so as to close one open end provided in peripheral wall portion 11 of housing body 10. As a result, one axial end of the housing is formed by holder 20. More specifically, holder 20 is fixed to housing body 10 by joining holder 20 and housing body 10 at or near their contact portion with each other, for example, by welding, with a portion of holder 20 inserted into the open end of housing body 10.

[0022] As a result, a weld 101 extending along the circumferential direction of the housing is provided at one axial end of the housing, and this weld 101 fills the gap between the housing main body 10 and the holder 20. Therefore, this weld 101 seals the gap, making it possible to ensure airtightness in that area. For welding the housing main body 10 and the holder 20, for example, electron beam welding, laser welding, resistance welding, etc. can be suitably used.

[0023] The assembly structure of the holder 20 to the housing main body 10 is not limited to the assembly structure described above, and other assembly structures may be adopted. In that case, airtightness between the housing main body 10 and the holder 20 can be ensured by providing an O-ring or the like at an appropriate position.

[0024] 1 and 3, the closing member 30 is assembled to the housing body 10 so as to close the other open end provided in the peripheral wall portion 11 of the housing body 10. As a result, one axial end of the housing is formed by the closing member 30. More specifically, the closing member 30 is fixed to the housing body 10 by joining the closing member 30 and the housing body 10 at or near their contact portion with each other, for example, by welding, with a portion of the closing member 30 inserted into the open end of the housing body 10.

[0025] As a result, a weld 102 extending along the circumferential direction of the housing is provided at the axial end on the other end side of the housing in the axial direction, and this weld 102 fills the gap between the housing main body 10 and the closing member 30. Therefore, this weld 102 seals the gap, making it possible to ensure airtightness in that area. For example, electron beam welding, laser welding, resistance welding, etc. can be suitably used to weld the housing main body 10 and the closing member 30 together.

[0026] The assembly structure of the closing member 30 to the housing main body 10 is not limited to the assembly structure described above, and other assembly structures may be adopted. In such cases, airtightness between the housing main body 10 and the closing member 30 can be ensured by providing an O-ring or the like at an appropriate position. Furthermore, the housing main body 10 and the closing member 30 may not be separate bodies, but may be configured as a single member having a cylindrical shape with a bottom.

[0027] 1 and 2, the igniter 40 is mounted to the one end in the axial direction of the housing by being supported by the holder 20. The igniter 40 is for burning the gas generating agent 60, and is installed so as to face the space inside the housing.

[0028] The igniter 40 has an ignition unit 41 and a pair of terminal pins 42. The ignition unit 41 includes a squib cup, and a resistor (bridge wire) is attached inside the squib cup so as to connect to the pair of terminal pins 42. The squib cup is filled with an ignition charge so as to surround or be in contact with the resistor. A transfer charge may also be loaded inside the squib cup, if necessary.

[0029] Here, the resistor typically uses nichrome wire or resistance wire made of an alloy containing platinum and tungsten, and the ignition charge typically uses ZPP (zirconium-potassium perchlorate), ZWPP (zirconium-tungsten-potassium perchlorate), lead tricinate, etc. Furthermore, the transfer charge typically uses a composition consisting of a metal powder / oxidizer, such as B / KNO3, B / NaNO3, or Sr(NO3)2, a composition consisting of titanium hydride / potassium perchlorate, or a composition consisting of B / 5-aminotetrazole / potassium nitrate / molybdenum trioxide.

[0030] When a collision is detected, a predetermined amount of current flows through the resistor via the terminal pin 42. This current flow generates Joule heat in the resistor, causing the ignition charge to begin burning. The high-temperature particles generated by the combustion split open the squib cup containing the ignition charge. The time from when the current flows through the resistor to when the igniter 40 is activated is generally 2 milliseconds or less when nichrome wire is used for the resistor.

[0031] Igniter 40 is fixed to holder 20 by crimping portion 22 provided on holder 20. More specifically, holder 20 has crimping portion 22 for crimping and fixing igniter 40 at an axial end portion facing the interior space of the housing, and igniter 40 is inserted into through portion 21 and held against the wall portion of the portion of holder 20 that defines through portion 21, and thereby igniter 40 is clamped and fixed within holder 20 by crimping the above-mentioned crimping portion 22.

[0032] As a result, igniter 40 is mounted to holder 20 so that ignition portion 41 protrudes toward the interior of the housing. Therefore, when igniter 40 is activated, the ignition charge is ignited, causing the squib cup to split, and the squib cup opens as a result of this splitting.

[0033] Here, a seal member 43 made of an O-ring or the like is interposed between holder 20 and igniter 40, and the gap between holder 20 and igniter 40 is thereby filled with seal member 43, thereby sealing the gap. Therefore, with this configuration, it is possible to ensure airtightness in that portion. Note that the assembly structure of igniter 40 is not limited to the assembly structure using crimped portion 22 described above, and other assembly structures may be adopted.

[0034] A recess 23 is provided at the axial end portion exposed to the outside of holder 20, continuing from the above-mentioned through-hole 21. Recess 23 forms a female connector portion that receives a male connector (not shown) of a harness for connecting igniter 40 to a control unit (not shown), and terminal pin 42 of igniter 40 is exposed and positioned within recess 23. A male connector is inserted into recess 23 as the female connector portion, thereby achieving electrical continuity between the core wire of the harness and terminal pin 42.

[0035] 1 and 4, a partition member 50 is disposed at a predetermined position in the space inside the housing. The partition member 50 is a member for dividing the space inside the housing in the axial direction of the housing into a gas generating agent storage chamber S1 and a filter chamber S2.

[0036] The partition member 50 has a cylindrical shape with a bottom, and is made of a metal member such as stainless steel, iron steel, aluminum alloy, or stainless alloy. The partition member 50 has a flat partition wall portion 51 arranged perpendicular to the axial direction of the housing main body 10, and a cylindrical plate-like annular wall portion 52 standing from the periphery of the partition wall portion 51 toward the gas generating agent storage chamber S1. The partition member 50 is arranged so that the outer main surface of the partition wall portion 51 (i.e., the main surface on the filter chamber S2 side) abuts against the filter 90, and the outer peripheral surface of the annular wall portion 52 abuts against the inner circumferential surface of the housing main body 10.

[0037] The partition member 50 is assembled by being inserted into the housing body 10 and then joined to the housing body 10. More specifically, the partition member 50 is press-fitted into the housing body 10, and is fixed to the housing body 10 by joining the annular wall portion 52 of the partition member 50 to the housing body 10 at or near the contact portion between them, such as by welding.

[0038] As a result, a weld 103 extending along the circumferential direction of the housing is provided in the part of the housing corresponding to the part into which the partition member 50 is inserted, and this weld 103 fills the gap between the housing main body 10 and the partition member 50. Therefore, this gap is sealed by the weld 103, making it possible to ensure airtightness in this part. For welding the housing main body 10 and the partition member 50 together, for example, electron beam welding, laser welding, resistance welding, etc. can be suitably used.

[0039] The assembly structure of the partition member 50 to the housing main body 10 is not limited to the assembly structure using press-fitting and welding described above, and other assembly structures may be adopted. In that case, airtightness between the housing main body 10 and the partition member 50 can be ensured by providing an O-ring or the like at an appropriate position.

[0040] 4 and 5, a part of the partition wall 51 is configured as a thin-walled part, thereby providing a first weak part 53 and a second weak part 54. Of these, the first weak part 53 is provided in a part of the partition wall 51 of the partition member 50 that faces an inner space S2A, which will be described later, and the second weak part 54 is provided in a part of the partition wall 51 of the partition member 50 that faces an inner space S2A, which will be described later.

[0041] These first fragile portion 53 and second fragile portion 54 are configured so that when the internal pressure of the gas generating agent storage chamber S1 increases due to combustion of the gas generating agent 60, the partition portion 51 at the portion where the first fragile portion 53 and the second fragile portion 54 are provided will be torn open, and details of this will be described later.

[0042] As shown in Figures 1, 2 and 4, within the space inside the housing, a gas generating agent 60, an autoignition agent 61, an isolation member 70 and a coil spring 80 are arranged in the space sandwiched between the holder 20 and the partition member 50 (i.e., the gas generating agent storage chamber S1).

[0043] Of these, the autoignition agent 61 and the isolating member 70 are arranged on the side where the partition member 50 is located (i.e., the other end side of the gas generating agent storage chamber S1 in the axial direction of the housing), and the coil spring 80 is arranged on the side where the holder 20 is located (i.e., the one end side of the gas generating agent storage chamber S1 in the axial direction of the housing). The gas generating agent 60 is arranged between the isolating member 70 and the coil spring 80.

[0044] The gas generating agent 60 is an agent that generates gas by being ignited and burning by thermal particles generated by the activation of the igniter 40. A non-azide gas generating agent is preferably used as the gas generating agent 60, and the gas generating agent 60 is generally configured as a molded body containing fuel, an oxidizer, and an additive.

[0045] The fuel may be, for example, a triazole derivative, a tetrazole derivative, a guanidine derivative, an azodicarbonamide derivative, a hydrazine derivative, or a combination thereof. Specifically, nitroguanidine, guanidine nitrate, cyanoguanidine, 5-aminotetrazole, or the like is preferably used.

[0046] Examples of oxidizing agents include basic metal salts such as basic copper nitrate and basic copper carbonate, perchlorates such as ammonium perchlorate and potassium perchlorate, and nitrates containing cations selected from alkali metals, alkaline earth metals, transition metals, and ammonia. Suitable nitrates include sodium nitrate and potassium nitrate.

[0047] Examples of additives include binders, slag formers, and combustion adjusters. Suitable binders include organic binders such as metal salts of carboxymethyl cellulose and stearates, and inorganic binders such as synthetic hydrotalcite and acid clay. Suitable slag formers include silicon nitride, silica, and acid clay. Suitable combustion adjusters include metal oxides, ferrosilicon, activated carbon, and graphite.

[0048] The shape of the molded body of the gas generating agent 60 may be various, including granular, pellet-like, cylindrical, or other granular shapes, as well as disk-like shapes. Furthermore, for cylindrical molded bodies, perforated molded bodies having through holes inside the molded body (for example, single-hole cylindrical shapes or multi-hole cylindrical shapes) are also used. These shapes are preferably selected appropriately depending on the specifications of the airbag device into which the cylindrical gas generator 1A is to be incorporated, and it is preferable to select an optimal shape depending on the specifications, such as a shape in which the rate of gas generation changes over time during combustion of the gas generating agent 60. Furthermore, in addition to the shape of the gas generating agent 60, it is preferable to select the size and filling amount of the molded body appropriately taking into consideration the linear burning velocity, pressure exponent, etc. of the gas generating agent 60.

[0049] Auto-ignition agent 61 is an agent that ignites automatically without the operation of igniter 40, and in this embodiment is made up of pellets formed into a flat, generally cylindrical shape. Auto-ignition agent 61 ignites spontaneously at a lower temperature than gas generating agent 60, and is intended to induce auto-ignition operation by heating cylinder-shaped gas generator 1A from the outside in the unlikely event of a fire or the like occurring in a vehicle or the like equipped with an airbag device in which cylinder-shaped gas generator 1A is incorporated.

[0050] The isolating member 70 is a member for isolating the gas generating agent 60 and the auto-ignition agent 61 so that they do not come into direct contact with each other. The isolating member 70 has a recess 71 for positioning the auto-ignition agent 61 in a portion facing the partition member 50 in the axial direction of the housing body 10. In addition, a through-hole 72 is provided in the bottom of the recess 71 of the isolating member 70 to communicate between the space containing the gas generating agent 60 and the space containing the auto-ignition agent 61.

[0051] Here, the isolation member 70 is preferably made of a metal press-molded product, and is preferably made of a brass member that will not break or melt even when the gas generating agent 60 is burned. However, the isolation member 70 does not necessarily have to be made of brass, and the isolation member 70 may also be made of stainless steel, steel, iron, aluminum, an aluminum alloy, or the like.

[0052] A portion of the above-mentioned autoignition agent 61 is accommodated in the recess 71 provided in the isolating member 70. As a result, the autoignition agent 61 is sandwiched between the bottom of the recess 71 of the isolating member 70 and the partition wall portion 51 of the partition member 50, and is thereby in contact with the partition member 50.

[0053] With this configuration, the auto-ignition agent 61 comes into thermal contact with the housing main body 10 via the partition member 50, which is a metal member, via a substantially shortest path. Therefore, in the event of a fire or the like occurring in a vehicle or the like, the timing of the occurrence of auto-ignition operation, which is initiated by the automatic ignition of the auto-ignition agent 61, is accelerated, and as a result, the temperature of the gas generating agent 60 when the auto-ignition operation occurs can be kept relatively low. Therefore, it is possible to effectively suppress an increase in the internal pressure of the housing when the auto-ignition operation occurs.

[0054] The coil spring 80 is provided for the purpose of preventing the gas generating agent 60, which is a molded body, from being crushed by vibration or the like, and has a spring portion 81 and a pressing portion 82 formed by bending a metal wire. One end of the spring portion 81 is disposed so as to abut against the holder 20, and the pressing portion 82 is formed at the other end. The pressing portion 82 is formed, for example, by arranging a metal wire in a spiral shape at a predetermined interval, and abuts against the gas generating agent 60.

[0055] As a result, the coil spring 80 is sandwiched between the holder 20 and the gas generating agent 60, and as the coil spring 80 undergoes compressive deformation, the gas generating agent 60 is elastically urged toward the partition member 50 by the coil spring 80. Therefore, the gas generating agent 60 accommodated in the gas generating agent accommodating chamber S1 is fixed by being elastically urged toward the partition member 50, and as a result, the gas generating agent 60 can be prevented from moving inside the housing.

[0056] Furthermore, when assembling the coil spring 80, the coil spring 80 is sandwiched between the holder 20 and the gas generating agent 60 and compressed, which allows the coil spring 80 to absorb dimensional variations in the various components housed inside the housing.

[0057] 1, 3, and 4, a filter 90 is disposed in the space within the housing, which is sandwiched between the closing member 30 and the partition member 50 (i.e., the filter chamber S2). The filter 90 has a hollow cylindrical shape with a hollow portion 91 extending in a direction parallel to the axial direction of the housing body 10. One end face in the axial direction of the filter 90 abuts against the bulkhead portion 51 of the partition member 50, and the other end face in the axial direction abuts against the closing member 30.

[0058] The filter 90 functions as a cooling means for cooling the gas by removing the high temperature heat of the gas generated by the combustion of the gas generating agent 60 as the gas passes through the filter 90, and also functions as a removal means for removing slag (residue) and the like contained in the gas. As described above, by using the filter 90 made of a cylindrical member, the flow resistance to the gas flowing through the filter chamber S2 during operation is kept low, making it possible to achieve an efficient gas flow.

[0059] The filter 90 can be preferably made of an assembly of metal wire or metal mesh material made of stainless steel, iron, etc. Specifically, it can be made of a knitted wire mesh, a plain woven wire mesh, an assembly of crimped woven metal wire, or any of these compressed by a press.

[0060] A wound perforated metal plate or the like can also be used as the filter 90. In this case, examples of the perforated metal plate that can be used include expanded metal, which is a metal plate with staggered cuts that are then expanded to form holes and processed into a mesh-like structure, and hook metal, which is a metal plate with holes drilled in it and burrs that form around the holes are flattened by crushing them.

[0061] In the filter chamber S2, the filter 90 is disposed at a distance from the peripheral wall 11 so that a gap 13 of a predetermined size is formed between the outer peripheral surface of the hollow cylindrical filter 90 and the inner peripheral surface of the peripheral wall 11 of the housing body 10. As a result, the filter chamber S2 is divided by the filter 90 in the radial direction of the peripheral wall 11 into an inner space S2A and an outer space S2B, of which the inner space S2A is defined by the hollow portion 91 of the filter 90, and the outer space S2B is defined by the gap 13 described above.

[0062] Furthermore, a plurality of gas outlets 12 are provided along the circumferential and axial directions in the portion of the peripheral wall 11 of the housing body 10 that defines the filter chamber S2 (i.e., the portion of the peripheral wall 11 that defines the outer space S2B described above). These gas outlets 12 are for directing the gas that has passed through the filter 90 to the outside of the housing.

[0063] In this way, by providing a gap 13 between the filter 90 and the peripheral wall portion 11 of the housing main body 10, the gas generated by the combustion of the gas generating agent 60 passes through almost the entire area of ​​the filter 90, thereby improving the utilization efficiency of the filter 90.

[0064] As described above and as shown in FIG. 4, in cylinder-shaped gas generator 1A according to the present embodiment, of first weak portion 53 and second weak portion 54 consisting of thin-walled portions provided in partition wall portion 51 of partition member 50 described above, first weak portion 53 is positioned so as to face inner space S2A of filter chamber S2 described above, and second weak portion 54 is positioned so as to face outer space S2B of filter chamber S2 described above.

[0065] That is, as shown in Figures 4 and 5, the first fragile portion 53 is provided in the center of the partition portion 51 and in a position close to the radial center of the partition portion 51 so as to face the hollow portion 91 of the filter 90 that forms the inner space S2A, and the second fragile portion 54 is provided in a position close to the outer peripheral edge of the partition portion 51 so as to face the above-mentioned gap portion 13 that forms the outer space S2B.

[0066] 5, for ease of understanding, the contact area of ​​the filter 90 with the partition wall portion 51 of the partition member 50 is indicated by a colored region marked with the symbol R (the same applies to FIGS. 8(A) to 8(D) described below). The above-mentioned first fragile portion 53 is provided in a portion of the partition wall portion 51 located inside this contact area R, and the above-mentioned second fragile portion 54 is provided in a portion of the partition wall portion 51 located outside this contact area R.

[0067] There are no particular limitations on the shapes of first weak portion 53 and second weak portion 54, but in cylinder-shaped gas generator 1A according to the present embodiment, as shown in Fig. 5, first weak portion 53 is configured as a thin-walled portion formed by providing, in partition portion 51, a plurality of linear grooves that extend radially by intersecting each other, and second weak portion 54 is configured as a thin-walled portion formed by providing, in partition portion 51, a plurality of recesses that are positioned in a dotted row along the circumferential direction of partition member 50. The plurality of grooves that form first weak portion 53 and the plurality of recesses that form second weak portion 54 are both provided in the main surface of a pair of main surfaces of partition portion 51 that faces filter chamber S2.

[0068] Furthermore, a notch 92 extending along the outer edge of the end of the hollow cylindrical filter 90 facing the partition member 50 is provided, and the notch 92 constitutes part of the outer space S2B. Providing such a notch 92 in the filter 90 makes it possible to increase the area of ​​the partition wall 51 of the partition member 50 facing the outer space S2B without significantly reducing the volume of the filter 90, and to increase the area of ​​the partition wall 51 where the above-mentioned second fragile portion 54 is provided.

[0069] First weak portion 53 is configured so that, when subjected to a pressure exceeding a predetermined first pressure value, rupture occurs in partition portion 51, starting from first weak portion 53. Here, the predetermined first pressure value is the rupture pressure of partition portion 51 required to achieve an internal pressure of the housing that enables gas generating agent 60 to stably burn during normal operation of cylinder-shaped gas generator 1A.

[0070] On the other hand, second weak portion 54 is configured so that, when subjected to a pressure exceeding a predetermined second pressure value that is higher than the first pressure value, rupture occurs in partition portion 51, starting from second weak portion 54. Here, the predetermined second pressure value is the rupture pressure of partition portion 51 that is required to appropriately reduce the internal pressure of the housing so that rupture does not occur in the housing during abnormal operation of cylinder-shaped gas generator 1A.

[0071] The rupture pressures of the first and second fragile portions 53 and 54 (i.e., the above-mentioned first and second pressure values) can be adjusted by the shape, size, depth, etc. of the grooves and recesses provided in the partition portion 51 to form the first and second fragile portions 53 and 54. In other words, the rupture pressures of the first and second fragile portions 53 and 54 are determined by the shape, size, thickness, etc. of the first fragile portions 53.

[0072] Here, the specific rupture pressures of first fragile portion 53 and second fragile portion 54 are set appropriately based on the specifications of cylinder-shaped gas generator 1A, but the rupture pressure of first fragile portion 53 is expected to be, for example, 10 MPa or more and 30 MPa or less, and the rupture pressure of second fragile portion 54 is expected to be, for example, 90 MPa or more and 110 MPa or less. Note that the rupture pressure of second fragile portion 54 needs to be higher than the maximum value of the internal pressure of gas generating agent storage chamber S1 during normal operation, and from this perspective, the rupture pressure of second fragile portion 54 is preferably set to at least 70 MPa or more.

[0073] Figure 6 is a schematic diagram showing the flow of gas during normal operation of the disk-shaped gas generator shown in Figure 1. Next, with reference to Figure 6 and the above-mentioned Figure 1, operation of cylinder-shaped gas generator 1A according to the present embodiment during normal operation will be described.

[0074] Referring to FIG. 1, when a vehicle equipped with cylinder-shaped gas generator 1A according to this embodiment collides, the collision is detected by collision detection means provided separately in the vehicle, and based on this, igniter 40 is activated by current supplied from a control unit provided separately in the vehicle.

[0075] When the igniter 40 is activated, the pressure inside the ignition part 41 increases due to the combustion of the ignition charge and / or the transfer charge in addition to the ignition charge, which causes the squib cup of the ignition part 41 to split open, and thermal particles generated by the combustion of the ignition charge and / or the transfer charge in addition to the ignition charge flow out to the outside of the ignition part 41. The thermal particles that reach the gas generating agent 60 combust the gas generating agent 60, thereby generating a large amount of gas inside the gas generating agent storage chamber S1.

[0076] As a result, the pressure in the gas generating agent storage chamber S1 increases, and when the internal pressure of the gas generating agent storage chamber S1 reaches the above-mentioned predetermined first pressure value, a rupture occurs in the portion of the partition wall portion 51 of the partition member 50 where the first weak portion 53 is provided, as shown in Fig. 6. As a result, an opening is formed in the portion of the partition member 50 that faces the internal space S2A of the filter chamber S2, and the gas generating agent storage chamber S1 and the internal space S2A of the filter chamber S2 communicate with each other via the opening.

[0077] 6, the gas generated in the gas generating agent storage chamber S1 flows into the internal space S2A through the opening formed in the partition member 50. At this time, no rupture occurs in the portion of the partition wall portion 51 of the partition member 50 where the second fragile portion 54 is provided. This is because the pressure in the gas generating agent storage chamber S1 is appropriately reduced by the rupture of the first fragile portion 53, and as a result, the internal pressure of the gas generating agent storage chamber S1 does not reach the above-mentioned predetermined second pressure value.

[0078] 1, the gas that has flowed into the inner space S2A flows through the hollow portion 91 of the filter 90 in the axial direction, then changes direction in the radial direction, and flows through the interior of the filter 90. During this process, the filter 90 removes heat to cool the gas, and the filter 90 also removes slag contained in the gas.

[0079] The gas that has passed through filter 90 then flows into outer space S2B of filter chamber S2, and is then ejected to the outside of the housing via gas outlet 12 provided in peripheral wall portion 11 of housing main body 10. The gas ejected to the outside from gas outlet 12 is introduced into the interior of an airbag provided adjacent to cylinder-shaped gas generator 1A, and inflates and deploys the airbag. During normal operation of cylinder-shaped gas generator 1A, auto-ignition agent 61 burns together with gas generating agent 60 when it burns.

[0080] Fig. 7 is a schematic diagram showing the flow of gas during auto-ignition operation of the disk-shaped gas generator shown in Fig. 1. Next, with reference to Fig. 7 and the above-mentioned Fig. 1, operation during auto-ignition operation of cylinder-shaped gas generator 1A according to the present embodiment will be described.

[0081] 1, in the event of a fire or the like occurring in a vehicle equipped with cylinder-shaped gas generator 1A according to the present embodiment, cylinder-shaped gas generator 1A will be heated from the outside. This heating not only heats the housing of cylinder-shaped gas generator 1A but also gas generating agent 60, auto-ignition agent 61, etc., and they reach a high temperature, but auto-ignition agent 61, which is configured to automatically ignite at a temperature lower than that of gas generating agent 60, begins to burn when it reaches its spontaneous ignition temperature, thereby triggering auto-ignition operation independent of the operation of igniter 40.

[0082] When the auto-ignition operation is initiated, gas generating agent 60 immediately begins to burn in conjunction with the combustion of auto-ignition agent 61. At this time, since cylinder-shaped gas generator 1A has already reached a high temperature as a whole due to being heated from the outside, the pressure in gas generating agent storage chamber S1 rises rapidly, and accordingly the internal pressure of gas generating agent storage chamber S1 quickly reaches the above-mentioned predetermined first pressure value. Accordingly, as shown in FIG. 7 , a rupture occurs in the portion of partition wall portion 51 of partition member 50 where first weak portion 53 is provided.

[0083] As a result, an opening is formed in a portion of the partition member 50 facing the inner space S2A of the filter chamber S2, and the gas generating agent storage chamber S1 and the inner space S2A of the filter chamber S2 are in communication with each other via the opening. Accordingly, gas generated in the gas generating agent storage chamber S1 flows into the inner space S2A via the opening formed in the partition member 50, as shown by arrow A in FIG.

[0084] However, as mentioned above, during auto-ignition operation, unlike during normal operation as described above, the entire cylinder-shaped gas generator 1A is already at a high temperature, so the rate at which the internal pressure of the gas generating agent storage chamber S1 is increased by the combustion of the gas generating agent 60 exceeds the rate at which the internal pressure of the gas generating agent storage chamber S1 is reduced by the rupture of the first weak part 53, and the pressure in the gas generating agent storage chamber S1 does not decrease, and the pressure in the gas generating agent storage chamber S1 continues to rise.

[0085] Then, when the internal pressure of the gas generating agent storage chamber S1 reaches the above-mentioned predetermined second pressure value, a rupture occurs in the portion of the partition wall portion 51 of the partition member 50 where the second weak portion 54 is provided, as shown in Fig. 7. As a result, an opening is formed in the portion of the partition member 50 facing the outer space S2B of the filter chamber S2, and the gas generating agent storage chamber S1 and the outer space S2B of the filter chamber S2 communicate with each other via the opening.

[0086] 7, the gas generated in the gas generating agent storage chamber S1 flows into the outer space S2B through the opening formed in the partition member 50. As a result, after the portion of the partition wall 51 where the second fragile portion 54 is provided is ruptured, the gas generated in the gas generating agent storage chamber S1 moves toward the filter chamber S2 through the portion of the partition wall 51 that is ruptured starting from the first fragile portion 53 and also through the portion of the partition wall 51 that is ruptured starting from the second fragile portion 54, and is then discharged to the outside through the gas outlet 12 provided in the peripheral wall 11 of the housing.

[0087] Here, unlike the inner space S2A of the filter chamber S2, the outer space S2B of the filter chamber S2 communicates with the gas outlet 12 provided in the peripheral wall portion 11 of the housing without passing through the filter 90. Therefore, the flow resistance to gas flowing from the gas generating agent storage chamber S1 directly into the outer space S2B of the filter chamber S2 and through the path to the gas outlet 12 is significantly smaller than the flow resistance to gas flowing through the path from the gas generating agent storage chamber S1 to the gas outlet 12 via the inner space of the filter chamber S2.

[0088] Therefore, after the portion of the partition portion 51 where the second weak portion 54 is provided is ruptured, the gas can be discharged to the outside more efficiently, and the rate at which the internal pressure of the gas generating agent storage chamber S1 is reduced due to the rupture of not only the first weak portion 53 but also the second weak portion 54 becomes faster than the rate at which the internal pressure of the gas generating agent storage chamber S1 is increased due to the combustion of the gas generating agent 60, and the pressure in the gas generating agent storage chamber S1 is appropriately reduced.

[0089] Therefore, the pressure in gas generating agent storage chamber S1 will not rise any further, and it is possible to prevent a pressure rise in gas generating agent storage chamber S1 that would result in rupture of the housing by appropriately setting the rupture pressure of second fragile portion 54. For this reason, by configuring cylinder-shaped gas generator 1A according to the present embodiment, it is possible to prevent the induction of abnormal operation that would result in rupture of the housing, and it is possible to provide a cylinder-shaped gas generator with improved safety compared to conventional ones.

[0090] (Variation) Figures 8(A) to 8(D) are views showing the configuration of partition members according to first to fourth modified examples. Partition members 50A to 50D according to first to fourth modified examples will now be described with reference to Figures 8(A) to 8(D). Note that partition members 50A to 50D according to first to fourth modified examples are provided in cylinder-shaped gas generator 1A in place of partition member 50 provided in cylinder-shaped gas generator 1A according to embodiment 1 described above.

[0091] 8(A), similarly to the partition member 50 according to the first embodiment, a plurality of recesses are provided in a dotted row along the circumferential direction of the partition member 50A at positions close to the outer peripheral edge of the partition wall portion 51, thereby providing second fragile portions 54. Here, the plurality of recesses are configured as grooves extending radially outwardly of the partition member 50A, and in this respect, the configuration of the partition member 50A differs from that of the partition member 50 according to the first embodiment.

[0092] 8(B) , in a partition member 50B according to a second modified example, the second fragile portions 54 are configured as a plurality of grooves provided near the outer peripheral edge of the partition wall portion 51. These grooves are arranged in a line along the circumferential direction of the partition member 50B, each having a predetermined length, and in this modified example, a total of six grooves are arranged. That is, in this modified example, the second fragile portions 54 are provided intermittently along the circumferential direction of the partition member 50B.

[0093] 8(C) , the second fragile portions 54 are formed of a plurality of grooves disposed near the outer peripheral edge of the partition wall portion 51, similar to the partition member 50B of the second modified example described above. Similar to the partition member 50B of the second modified example described above, these grooves are also configured to be aligned along the circumferential direction of the partition member 50C, each having a predetermined length. In this modified example, a total of four grooves are disposed. In other words, in this modified example, the second fragile portions 54 are also disposed intermittently along the circumferential direction of the partition member 50C.

[0094] 8(D) shows a partition member 50D according to a fourth modified example, in which the second fragile portion 54 is configured as a single groove portion provided near the outer peripheral edge of the partition wall portion 51. This single groove portion is positioned so as to go around the circumferential direction of the partition member 50B. That is, in this modified example, the second fragile portion 54 is provided continuously along the circumferential direction of the partition member 50D.

[0095] When a cylinder-shaped gas generator is provided with any of partition members 50A to 50D according to the first to fourth modifications, the same effects as those described in the above-mentioned embodiment 1 can be obtained. In this way, the number, shape, size, arrangement position, etc. of second fragile portions 54 provided in partition member 50 can be modified in various ways. Note that the number, shape, size, arrangement position, etc. of first fragile portions 53 can also be modified in various ways.

[0096] (Embodiment 2) Fig. 9 is a schematic diagram of a disk-shaped gas generator according to Embodiment 2. Hereinafter, with reference to Fig. 9, a disk-shaped gas generator 1B according to the present embodiment will be described.

[0097] As shown in Figure 9, disk-shaped gas generator 1B according to the present embodiment differs from cylinder-shaped gas generator 1A according to the first embodiment described above only in the configuration of filter 90. Specifically, in disk-shaped gas generator 1B, notch 92 (see Figure 4) is not provided at the end of filter 90 on the partition member 50 side, and filter 90 has a hollow cylindrical outer shape with the same inner and outer diameters at any position in the axial direction.

[0098] In the disk-shaped gas generator 1B configured in this manner, the first weak portion 53 provided in the partition wall portion 51 of the partition member 50 faces the inner space S2A of the filter chamber S2, and the second weak portion 54 provided in the partition wall portion 51 of the partition member 50 faces the outer space S2B of the filter chamber S2, thereby achieving the same effects as those described in the first embodiment above.

[0099] (Summary of the Disclosure of the Embodiments and Modifications) The characteristic configurations disclosed in the above-described embodiment and modifications can be summarized as follows.

[0100] [Appendix 1] a housing having a cylindrical peripheral wall portion, one end and the other end in an axial direction being closed, and including therein a gas generating agent storage chamber in which a gas generating agent is stored and a filter chamber in which a filter is disposed; a partition member that is inserted into the peripheral wall portion so that the gas generating agent storage chamber is located on the one end side and the filter chamber is located on the other end side, thereby dividing the internal space of the housing in the axial direction of the peripheral wall portion; an igniter assembled to the one end of the housing, the filter includes a hollow cylindrical portion at least at an end portion of the filter chamber on the one end side, the hollow cylindrical portion dividing the filter chamber into an inner space and an outer space in a radial direction of the peripheral wall portion, an end portion of the hollow cylindrical portion on the one end side abuts against the partition member, the housing has a gas outlet for ejecting gas to the outside in a portion defining the outer space, a first weak portion that ruptures when subjected to pressure exceeding a predetermined first pressure value is provided in a portion of the partition member that faces the inner space; A gas generator, wherein a second weak part that ruptures when subjected to pressure exceeding a predetermined second pressure value that is higher than the first pressure value is provided in a part of the partition member that faces the outer space.

[0101] [Appendix 2] 2. The gas generator according to claim 1, wherein the first weak portion and the second weak portion are configured by thin-walled portions provided in the partition member.

[0102] [Appendix 3] 3. The gas generator according to claim 1, wherein the second weak portion is positioned continuously or intermittently along the circumferential direction of the partition member.

[0103] [Appendix 4] 4. The gas generator according to any one of claims 1 to 3, wherein the filter has a notch extending along an outer edge of an end portion on the one end side of the hollow cylindrical portion.

[0104] [Appendix 5] 5. A gas generator according to any one of appendixes 1 to 4, wherein the filter has a hollow cylindrical shape overall and is held by being sandwiched between the other end of the housing and the partition member.

[0105] (Other forms, etc.) In the above-described embodiment and modified example, an example has been given in which the first and second fragile portions are formed by providing a recess or groove of a predetermined shape in one of the pair of main surfaces of the partition wall portion of the partition member that faces the filter chamber. However, the first and second fragile portions may also be formed by providing a recess or groove of a predetermined shape in one of the pair of main surfaces of the partition wall portion of the partition member that faces the gas generating agent storage chamber, or the first and second fragile portions may be formed by providing a recess or groove of a predetermined shape in both of the pair of main surfaces.

[0106] Furthermore, in the above-described embodiment and modified examples, an example has been described in which the present invention is applied to a cylinder-shaped gas generator equipped with an auto-ignition agent, but the application of the present invention is not necessarily limited to this, and it is naturally possible to apply the present invention to a cylinder-shaped gas generator that does not have an auto-ignition agent.

[0107] Furthermore, the shape, configuration, size, number, material, etc. of each part shown in the above-described embodiment and modified examples can be modified in various ways without departing from the spirit of the present invention.

[0108] Furthermore, the characteristic configurations shown in the above-described embodiments and modifications can be combined with each other without departing from the spirit of the present invention.

[0109] As such, the above-described embodiments and modifications disclosed herein are illustrative in all respects and are not restrictive. The technical scope of the present invention is defined by the claims, and includes all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0110] 1A, 1B Cylindrical gas generator, 10 Housing body, 11 Peripheral wall portion, 12 Gas outlet, 13 Gap portion, 20 Holder, 21 Penetration portion, 22 Crimping portion, 23 Recessed portion, 30 Closure member, 40 Igniter, 41 Ignition portion, 42 Terminal pin, 43 Sealing member, 50 Partition member, 51 Bulkhead portion, 52 Annular wall portion, 53 First weak portion, 54 Second weak portion, 60 Gas generating agent, 61 Auto-ignition agent, 70 Isolation member, 71 Recessed portion, 72 Through hole, 80 Coil spring, 81 Spring portion, 82 Pressing portion, 90 Filter, 91 Hollow portion, 92 Notch portion, 101-103 Welded portions, S1 Gas generating agent storage chamber, S2 Filter chamber, S2A Inner space, S2B Outer space.

Claims

1. a housing having a cylindrical peripheral wall portion, one end and the other end in an axial direction being closed, and including therein a gas generating agent storage chamber in which a gas generating agent is stored and a filter chamber in which a filter is disposed; a partition member that is inserted into the peripheral wall portion so that the gas generating agent storage chamber is located on the one end side and the filter chamber is located on the other end side, thereby dividing the interior space of the housing in the axial direction of the peripheral wall portion; an igniter assembled to the one end of the housing, the filter includes a hollow cylindrical portion at least at an end portion of the filter chamber on the one end side, the hollow cylindrical portion dividing the filter chamber into an inner space and an outer space in a radial direction of the peripheral wall portion, an end portion of the hollow cylindrical portion on the one end side abuts against the partition member, the housing has a gas outlet for ejecting gas to the outside in a portion defining the outer space, a first weakened portion that ruptures when subjected to pressure exceeding a predetermined first pressure value is provided in a portion of the partition member that faces the inner space; a second weak part that ruptures when subjected to pressure exceeding a predetermined second pressure value that is higher than the first pressure value, is provided in a part of the partition member that faces the outer space.

2. 2. The gas generator according to claim 1, wherein the first weak portion and the second weak portion are configured by thin-walled portions provided in the partition member.

3. The gas generator according to claim 1 , wherein the second weakened portions are positioned continuously or intermittently along the circumferential direction of the partition member.

4. 2. The gas generator according to claim 1, wherein said filter has a notch extending along an outer edge of said one end side of said hollow cylindrical portion.

5. 2. The gas generator according to claim 1, wherein the filter has a hollow cylindrical shape as a whole, and is held by being sandwiched between the other end of the housing and the partition member.

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