JP2009286218A - Gas generator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas generator capable of easily processing the sealing for preventing moisture absorption of a gas generating agent, remarkably enhancing the workability during the assembly, and suppressing the manufacturing cost to be low, accordingly. <P>SOLUTION: A cylinder type gas generator 1A comprises a long housing 10, an ignition chamber 15, a combustion chamber 16 and a decompression chamber 17 provided in the housing 10. An igniter 30 and a transfer charge 27 are stored in the ignition chamber 15. A cushion material 51, a gas generating agent 52 and a perforated plate 18 are stored in the combustion chamber 16. The cushion material 51, the gas generating agent 52 and the perforated plate 18 are stored in a sealed state in a storage space 73 of a first sealed container 70 arranged in the combustion chamber 16. The transfer charge 27 is stored in a sealed state in a storage space 83 of a second sealed container 80 arranged in the ignition chamber 15. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a gas generator incorporated in an airbag device as an occupant protection device mounted on an automobile or the like, and more particularly to a so-called cylinder type gas generator having a long cylindrical outer shape.

  2. Description of the Related Art Conventionally, airbag devices, which are occupant protection devices, have been widely used from the viewpoint of protecting occupants such as automobiles. An airbag device is installed in a vehicle or the like for the purpose of protecting an occupant from an impact caused by the collision of a vehicle or the like, and is an airbag that is deployed by instantly inflating and deploying the airbag at the time of a vehicle or the like collision. It is intended to catch the passenger's body. The gas generator is a device that is incorporated in the airbag device and inflates and deploys the airbag by instantaneously generating gas when a vehicle or the like collides.

  There are various types of gas generators based on specifications such as installation position and output with respect to a vehicle or the like. One of them is a gas generator having a structure called “cylinder type”. The cylinder type gas generator has a long cylindrical shape, and is suitably incorporated in a side airbag device, an airbag device for a passenger seat, or the like.

  In general, in a cylinder type gas generator, a heat transfer means such as an igniter and a charge transfer agent is disposed at one end portion in the axial direction of a housing, and a combustion chamber in which a gas generating agent is accommodated is provided at a substantially central portion in the axial direction. In addition, a decompression chamber in which the filter is accommodated and a gas outlet are provided at the other end in the axial direction. In the cylinder-type gas generator having the above-described configuration, the flame generated by the operation of the igniter is transmitted to the gas generating agent through the combustion of the transfer agent, whereby the gas generating agent burns and the high temperature and high pressure combustion gas is generated. Occurs. The generated high-temperature and high-pressure combustion gas flows into the decompression chamber from the combustion chamber, is decompressed in the decompression chamber, passes through the filter, and is discharged from the gas outlet to the outside of the housing. The combustion gas discharged from the gas outlet is then used for inflation / deployment of the airbag.

In the cylinder type gas generator, it is necessary that the combustion chamber in which the gas generating agent is accommodated be hermetically sealed. This is because when the outside air enters the combustion chamber from an external space, the gas generating agent may absorb moisture due to moisture contained in the outside air that has entered, and the gas generating agent has absorbed moisture. This is because a desired gas output cannot be obtained. For this reason, in a conventional cylinder type gas generator, a seal portion is formed by interposing an O-ring between members constituting the housing, a gas outlet provided in the housing, or a communication provided in the housing. The airtightness of the combustion chamber has been ensured by closing the holes with a metal seal tape. References disclosing a cylinder type gas generator that has been subjected to a sealing process using such an O-ring or a seal tape include, for example, Japanese Patent Application Laid-Open No. 11-78766 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2005-313812. There exists a gazette (patent document 2) etc.
Japanese Patent Laid-Open No. 11-78766 JP 2005-313812 A

  However, when the configuration as disclosed in Patent Documents 1 and 2 described above is employed, a fragile seal member such as an O-ring or a seal tape is accurately placed at a predetermined position in the assembly process of the cylinder type gas generator. There is a problem that it is necessary to assemble, the handling becomes complicated, and the manufacturing cost increases. In general, in a cylinder type gas generator, a cushioning material for preventing crushing due to vibration of the gas generating agent and a perforated plate for preventing the gas generating agent from entering the decompression chamber are accommodated in the combustion chamber. However, since these members are also relatively fragile members, the handling at the time of assembly is complicated, which causes the manufacturing cost to increase. Furthermore, the work of filling a gas generator in the middle of assembly with a charge transfer agent or a gas generating agent that requires a great deal of care in handling because it reacts sensitively to static electricity or fire involves considerable difficulty.

  Therefore, the present invention has been made to solve the above-mentioned problems, and the sealing process for preventing the gas generating agent from absorbing moisture is facilitated, and the workability during assembly is greatly improved. As a result, an object of the present invention is to provide a gas generator capable of reducing the manufacturing cost.

  The gas generator according to the present invention includes a housing, a combustion chamber, a decompression chamber, and ignition means. The housing includes a gas outlet and is formed of a long cylindrical member that is closed at both axial ends. The combustion chamber is located inside the housing, and combustion gas is generated in the combustion chamber by burning the gas generating agent. The decompression chamber is located inside the housing, and in the decompression chamber, the pressure of the combustion gas that has flowed in is reduced as the combustion gas generated in the combustion chamber flows in. Combusted gas is introduced to the gas outlet. The ignition means is means for burning the gas generating agent. A first sealed container having a sealed housing space is disposed in the combustion chamber, and the gas generating agent is disposed in the housing space of the first sealed container, and the gas generating agent is disposed in the decompression chamber. An intrusion prevention member for preventing entry and a crush prevention member for preventing crushing of the gas generating agent due to vibration are disposed.

  With this configuration, the gas generating agent can be housed and disposed in the combustion chamber in a state in which the gas generating agent is sealed in advance by the first closed container, so that the gas generating agent is particularly hermetically sealed in the housing. Therefore, it is not necessary to perform a sealing process. Therefore, it is not necessary to seal each part of the housing using a fragile member such as an O-ring or a seal tape, so that the sealing process for preventing the gas generating agent from absorbing moisture is greatly facilitated. . In addition, when the gas generating agent is accommodated in the first sealed container, it is also possible to previously accommodate and arrange the intrusion prevention member and the crush prevention member to be disposed in the combustion chamber in the first sealed container together with the gas generating agent. Therefore, these members can be assembled to the housing at a time in a sub-assembled state, and the assembly operation of the gas generator can be greatly facilitated. Therefore, by adopting the above configuration, the sealing process for preventing the gas generating agent from absorbing moisture can be facilitated, and the workability at the time of assembly can be dramatically improved. It can be set as the gas generator which can be suppressed low.

  In the gas generator according to the present invention, the combustion chamber and the decompression chamber are preferably provided side by side in the axial direction of the housing inside the housing, and the ignition means is the combustion chamber. It is preferable that the chamber is provided at a position opposite to the decompression chamber. In that case, it is preferable that the first sealed container is press-fitted and fixed inside the housing, and the entry preventing member is an end portion on the decompression chamber side in the accommodation space of the first sealed container. It is preferable that the intrusion preventing member is disposed, and the crushing preventing member is preferably disposed in an end portion on the ignition means side in the accommodating space of the first sealed container.

  By comprising in this way, these gas generants, an entry prevention member, and the 1st airtight container in which the gas generant, the entry prevention member, and the crushing prevention member were accommodated in the housing are press-fitted and fixed. Since the crush preventing member can be fixed to the housing at a time, further assembly work can be facilitated.

  In the gas generator according to the present invention, it is preferable that the gas generator further includes an ignition chamber located inside the housing and containing the ignition means. In that case, the ignition means However, it is preferable to include an igniter including an igniter that generates a flame by burning, and a transfer agent that transmits the flame generated in the igniter to the gas generating agent. The ignition chamber is preferably provided with a second sealed container having a sealed storage space. In that case, the transfer charge is disposed in the storage space of the second sealed container. It is preferable.

  By configuring in this way, the transfer charge can be accommodated and disposed in the ignition chamber together with the closed container in a state where the transfer charge is sealed in advance by the second closed container, so that the transfer charge is particularly hermetically sealed in the housing. There is no need to perform the sealing process. Therefore, it is not necessary to seal each part of the housing using a fragile member such as an O-ring or a seal tape, so that the seal process for preventing the transfer of moisture from the transfer charge is greatly facilitated. Therefore, by adopting the above-described configuration, it is possible to facilitate the sealing process for preventing the transfer of moisture from the transfer charge, and it is possible to dramatically improve the workability at the time of assembly and to reduce the manufacturing cost. It can be set as the gas generator which can be suppressed.

  In the gas generator according to the present invention, it is preferable that the entry preventing member is constituted by a plate-like member including a plurality of openings having a size smaller than the outer shape of the gas generating agent. Moreover, in the gas generator based on the said invention, it is preferable that the said crushing prevention member is comprised by the member which can be elastically deformed.

  In the gas generator according to the present invention, the gas generator is located inside the housing and partitions a space inside the housing, and a filter disposed in the decompression chamber; Is preferably further provided. In that case, the partition member is arranged coaxially with the housing, thereby separating the decompression chamber into an inner decompression chamber and an outer decompression chamber in the radial direction, and one of the tubular portions. It is preferable to include an extending portion that divides the space inside the housing into the combustion chamber and the decompression chamber by being continuously extended from the axial end toward the radially outer side. Further, it is preferable that a first communication hole that communicates the combustion chamber and the inner decompression chamber is provided at an axial end located on the side where the extending portion of the cylindrical portion is provided, It is preferable that a second communication hole for communicating the inner decompression chamber and the outer decompression chamber is provided in the cylindrical portion. The gas outlet is preferably provided only on the peripheral wall of the housing at a portion defining the outer decompression chamber, and at least one of the opening surfaces of the second communication hole is covered by the filter. It is preferable. The extending portion serves as a pressure partition that creates a pressure difference between the combustion chamber and the outer decompression chamber in a state where the gas generating agent is combusted, and the cylindrical portion is configured to burn the gas generating agent. In this state, it is preferable to be a pressure partition that creates a pressure difference between the inner decompression chamber and the outer decompression chamber.

  With this configuration, the combustion gas generated in the combustion chamber by the combustion of the gas generating agent is depressurized in two stages in the order of the inner decompression chamber and the outer decompression chamber, and from the gas outlet to the outside of the housing. And will be released. Therefore, it is possible to sufficiently cool and depressurize the combustion gas discharged from the gas outlet, and it becomes easy to obtain desired output characteristics. Further, since the inner decompression chamber and the outer decompression chamber described above can be configured with a very simple configuration in which the partition member having the extending portion is disposed inside the housing, there is a problem that the assembly structure is complicated. Does not occur. Further, since the inner decompression chamber and the outer decompression chamber are partitioned in the radial direction, the gas generator itself does not increase in size. Therefore, it is possible to provide a gas generator that can be configured in a relatively simple and compact configuration for obtaining desired combustion characteristics.

  In the gas generator according to the present invention, the filter preferably has a hollow cylindrical shape, in which case the hollow cylindrical filter is disposed in the outer decompression chamber. It is preferable.

  With this configuration, the combustion gas that has been decompressed and cooled in the inner decompression chamber is blown onto the filter, so that the risk of the filter being damaged is reduced and the required volume of the filter Will be small.

  In the gas generator based on the said invention, it is preferable that the said filter is comprised with the metal wire wound around the said cylindrical part.

  In this way, by configuring the filter by winding the metal wire around the cylindrical portion of the partition member, the deformation of the filter toward the radially outer side is suppressed, so that the filter is deformed and the gas It is possible to prevent the occurrence of problems such as clogging of the jet nozzle. In addition, since the filter can be assembled to the partition member in advance before fixing the partition member to the housing, the assembly work can be greatly facilitated and a gas generator can be manufactured at low cost. become.

  In the gas generator according to the present invention, the filter preferably has a hollow cylindrical shape, in which case the hollow cylindrical filter is disposed in the inner decompression chamber. Also good.

  Even in such a configuration, a gas generator that can be configured relatively simply and compactly to obtain desired combustion characteristics can be obtained.

  In the gas generator according to the present invention, it is preferable that a plurality of the second communication holes are equally provided in the cylindrical portion of the portion covered with the filter.

  By configuring in this way, it becomes possible to prevent the combustion gas from flowing locally in the filter, so that the flow of the combustion gas passing through the filter can be made more uniform in the filter. Thus, the filter can be used efficiently.

  According to the present invention, the gas generation that can facilitate the sealing process for preventing the gas generating agent from absorbing moisture and dramatically improve the workability during the assembly, thereby reducing the manufacturing cost. Can be a container.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the embodiment described below, a cylinder type gas generator suitably incorporated in the side airbag device will be described as an example.

  1A and 1B are views showing an external structure of a cylinder type gas generator according to an embodiment of the present invention. FIG. 1A is a front view and FIG. 1B is a right side view. FIG. 2 is a diagram showing the internal structure of the cylinder type gas generator in the present embodiment, and is a schematic cross-sectional view along the line II-II shown in FIGS. 1 (A) and 1 (B). 3A is a schematic cross-sectional view showing a state before the first sealed container shown in FIG. 2 is assembled to the housing, and FIG. 3B is a diagram of the second sealed container shown in FIG. It is a schematic cross section which shows the state before the assembly | attachment to a housing. First, with reference to these FIG. 1 thru | or FIG. 3, the structure of the cylinder type gas generator in this Embodiment is demonstrated.

  As shown in FIGS. 1 and 2, the cylinder type gas generator 1 </ b> A in the present embodiment has a long and substantially cylindrical outer shape, and has a housing 10 as an outer shell member. The housing 10 includes a cylindrical member 11, a closing member 14 and a holder 20. The cylindrical member 11 is a long cylindrical member having openings at both ends in the axial direction. The closing member 14 is made of a disk-shaped member having a predetermined thickness, and closes one opening in the axial direction of the cylindrical member 11. The closing member 14 is provided with a recess 14b for fixing a partition member 40 described later. Further, the closing member 14 has a groove 14a for caulking and fixing, which will be described later, on its peripheral surface. The caulking fixing groove 14 a is formed in an annular shape on the peripheral surface of the closing member 14 so as to extend along the circumferential direction. The holder 20 is formed of a cylindrical member having a hollow portion 22 extending along the same direction as the axial direction of the cylindrical member 11, and closes the other opening in the axial direction of the cylindrical member 11. The holder 20 has a groove 21 for caulking and fixing described later at a predetermined position on the outer peripheral surface thereof. The caulking fixing groove 21 is formed in an annular shape on the outer peripheral surface of the holder 20 so as to extend along the circumferential direction.

  The cylindrical member 11, the closing member 14, and the holder 20 are all made of a metal member such as stainless steel, steel, aluminum alloy, stainless alloy, and are connected and fixed by caulking. Specifically, in a state where a part of the closing member 14 is inserted into one opening end of the cylindrical member 11, a portion of the cylindrical member 11 corresponding to the groove 14 a provided on the peripheral surface of the closing member 14. The closure member 14 is caulked and fixed to the cylindrical member 11 by reducing the diameter of the peripheral wall inward in the radial direction and engaging with the groove 14a. In a state where the portion is inserted, the peripheral wall of the cylindrical member 11 corresponding to the groove 21 provided on the outer peripheral surface of the holder 20 is contracted radially inward and engaged with the groove 21. The holder 20 is caulked and fixed to the cylindrical member 11.

  These caulking fixings are caulking fixings called eight-side caulking that uniformly reduce the diameter of the peripheral wall of the cylindrical member 11 radially inward. By performing this caulking, the caulking portions 13 a and 13 b are provided on the peripheral wall of the cylindrical member 11. By using the above-mentioned eight-way caulking, airtightness can be sufficiently ensured without interposing a seal member between two members to be caulked and fixed.

  As shown in FIG. 2, an ignition chamber 15, a combustion chamber 16, and a decompression chamber 17 are provided in a space inside the cylinder type gas generator 1 </ b> A defined by the cylindrical member 11, the closing member 14 and the holder 20. Yes. The ignition chamber 15, the combustion chamber 16, and the decompression chamber 17 are formed by partitioning the space inside the housing 10 by a cup-shaped member 25 and a partition member 40 which will be described later.

  The ignition chamber 15 is mainly defined by the holder 20 and the cup-shaped member 25, and is provided in a portion of the housing 10 near the holder 20 (right portion in the drawing). An igniter (squib) 30 is disposed in the hollow portion 22 of the holder 20, and the resin molding portion 24 is located between the holder 20 and the igniter 30. The cup-shaped member 25 is formed of a bottomed cylindrical member having a space inside, and is arranged in contact with the holder 20 so that the space inside faces the ignition part 31 of the igniter 30.

  The above-mentioned resin molding part 24 is formed by, for example, insert molding, and the raw material thereof is a thermosetting resin typified by an epoxy resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyamide resin (for example, nylon 6 or nylon). 66), thermoplastic resins represented by polypropylene sulfide resin, polypropylene oxide resin and the like can be used.

  The igniter 30 is an ignition device for generating a flame, and includes an ignition unit 31 and a terminal pin 32. The ignition unit 31 includes an igniting agent that ignites during operation and a resistor for burning the igniting agent. The terminal pin 32 is connected to the ignition unit 31 in order to ignite the igniting agent. More specifically, the igniter 30 includes a base portion through which the pair of terminal pins 32 are inserted and held, and a squib cup attached to the base portion, and the tip of the terminal pin 32 inserted into the squib cup. A resistor (bridge wire) is attached so as to connect the squib cups, and an igniting agent is filled in the squib cup so as to surround the resistor or in contact with the resistor. Nichrome wire or the like is generally used as the resistor, and ZPP (zirconium / potassium perchlorate), ZWPP (zirconium / tungsten / potassium perchlorate), lead tricinate, or the like is generally used as the igniting agent. The squib cup is generally made of metal or plastic.

  When a collision is detected, a predetermined amount of current flows through the resistor via the terminal pin 32. When a predetermined amount of current flows through the resistor, Joule heat is generated in the resistor, and the ignition powder starts to burn upon receiving this heat. The high temperature flame generated by the combustion ruptures the squib cup containing the igniting agent. The time from when the current flows through the resistor until the igniter 30 is activated is 3 milliseconds or less when a nichrome wire is used as the resistor.

  As shown in FIG. 2, in the space defined by the cup-shaped member 25, the holder 20, the igniter 30 and the like in the ignition chamber 15 (that is, the space inside the cup-shaped member 25), the second sealed container 80 is placed. Contained. As shown in FIG. 3B, the second sealed container 80 includes a bottomed cylindrical cup portion 81 and a cap portion 82 that closes the opening of the cup portion 81. And the cap portion 82 are combined and joined, so that the accommodation space 83 formed therein is hermetically sealed from the outside of the second hermetic container 80. As the cup part 81 and the cap part 82, a metal thin plate (foil) such as copper, aluminum, copper alloy, or aluminum alloy formed by press working or the like is used. In addition, brazing, bonding, or the like is preferably used for joining the cup portion 81 and the cap portion 82.

The accommodation space 83 of the second hermetic container 80 is filled with the explosive charge 27. The explosive charge 27 is ignited by a flame generated by the operation of the igniter 30 and burns to generate hot particles. The charge transfer agent 27 is required to be able to reliably start combustion of a gas generating agent 52 described later. Generally, from the metal powder / oxidant represented by B / KNO ₃ or the like. The composition etc. which become are used. As the charge transfer agent 27, a powdery one, a one molded into a predetermined shape by a binder, or the like is used. Examples of the shape of the transfer charge molded by the binder include various shapes such as a granular shape, a columnar shape, a sheet shape, a spherical shape, a single-hole cylindrical shape, a porous cylindrical shape, and a tablet shape. In the present embodiment, the charge transfer agent 27 and the above-described igniter 30 function as ignition means for burning a gas generating agent 52 described later.

  A plurality of openings 25 a are provided on the bottom wall of the cup-shaped member 25, and the openings 25 a communicate the ignition chamber 15 and the combustion chamber 16. Moreover, the flange part is formed in the opening end by the side of the holder 20 of the cup-shaped member 25 toward the outer side. The flange portion is sandwiched between the axial end surface of the holder 20 and the caulking portion 13 d provided on the cylindrical member 11, whereby the cup-shaped member 25 is fixed to the housing 10. Note that the above-mentioned eight-side caulking is used for caulking for fixing the cup-shaped member 25 to the housing 10.

  As shown in FIG. 2, the combustion chamber 16 is defined by the cylindrical member 11, a flange portion 42 of a partition member 40 to be described later, and a cup-shaped member 25, and is provided at a substantially central portion of the housing 10. A first sealed container 70 is accommodated in the combustion chamber 16. As shown in FIG. 3A, the first sealed container 70 includes a bottomed cylindrical cup portion 71 and a cap portion 72 that closes the opening of the cup portion 71. By combining and joining the cap portion 72 and the cap portion 72, the accommodation space 73 formed therein is hermetically sealed from the outside of the first hermetic container 70. As the cup part 71 and the cap part 72, a metal thin plate (foil) such as copper, aluminum, copper alloy, aluminum alloy or the like formed by press working or the like is used. In addition, brazing, bonding, or the like is suitably used for joining the cup portion 71 and the cap portion 72.

  The gas generating agent 52, the porous plate 18, and the cushion material 51 are accommodated in the accommodation space 73 of the first sealed container 70. More specifically, the perforated plate 18 is disposed at the end portion on the decompression chamber 17 side of the accommodation space 73 of the first sealed container 70, and of the accommodation space 73 of the first sealed container 70. A cushion material 51 is disposed at an end portion on the ignition chamber 15 side. And the gas generating agent 52 is filled and located in the accommodation space 73 of the 1st airtight container 70 so that it may be located between these perforated plates 18 and the cushion material 51.

  The gas generating agent 52 is ignited by the heat particles generated by the combustion of the charge transfer agent 27 ignited by the igniter 30, and generates gas by burning. The gas generating agent 52 is generally formed as a molded body containing a fuel, an oxidant, and an additive. As the fuel, for example, a triazole derivative, a tetrazole derivative, a guanidine derivative, an azodicarbonamide derivative, a hydrazine derivative, or a combination thereof is used. Specifically, for example, nitroguanidine, guanidine nitrate, cyanoguanidine, 5-aminotetrazole and the like are preferably used. In addition, as the oxidizing agent, for example, nitrate containing a cation selected from alkali metals, alkaline earth metals, transition metals, and ammonia is used. As the nitrate, for example, sodium nitrate, potassium nitrate and the like are preferably used. In addition, examples of the additive include a binder, a slag forming agent, and a combustion adjusting agent. As the binder, for example, organic binders such as metal salts of carboxymethyl cellulose and stearates, and inorganic binders such as synthetic hydroxytalcite and acid clay can be suitably used. As the slag forming agent, silicon nitride, silica, acid clay, etc. can be suitably used. Moreover, as a combustion regulator, a metal oxide, ferrosilicon, activated carbon, graphite, etc. can be used suitably.

  The shape of the molded body of the gas generating agent 52 includes various shapes such as a granular shape, a pellet shape, a cylindrical shape, and a disk shape. In addition, a porous (for example, a single-hole cylindrical shape or a porous cylindrical shape) having a hole inside the molded body is also used. These shapes are preferably appropriately selected according to the specifications of the airbag apparatus in which the cylinder type gas generator 1A is incorporated. For example, the shape in which the gas generation rate changes with time when the gas generating agent 52 is burned. It is preferable to select an optimal shape according to the specification, such as selecting. In addition to the shape of the gas generating agent 52, it is preferable to appropriately select the size and filling amount of the molded body in consideration of the linear combustion rate, the pressure index, etc. of the gas generating agent 52.

  The cushion material 51 corresponds to a crushing prevention member for preventing the gas generating agent 52 made of a molded body from being crushed by vibration or the like, and a ceramic fiber molded body, foamed silicon, or the like is preferably used. The cushion material 51 is opened or divided by combustion of the charge transfer agent 27 during operation, and in some cases burns down.

  The perforated plate 18 is made of a plate-like member provided with a plurality of communication holes 18a, and is curved so that the central portion protrudes toward the holder 20 side. The communication holes 18 a provided in the porous plate 18 are all formed smaller than the outer shape of the gas generating agent 52. The perforated plate 18 corresponds to an entry preventing member for preventing the gas generating agent 52 from entering the decompression chamber 17, and preferably a metal member such as stainless steel, steel, an aluminum alloy, or a stainless alloy is used. It is done. The perforated plate 18 also has a function of rectifying the flow of combustion gas passing through the perforated plate 18 during operation.

  A partition member 40 is accommodated in the decompression chamber 17. The partition member 40 is continuously extended radially outward from the cylindrical portion 41 disposed coaxially with the cylindrical member 11 and the axial end of the cylindrical portion 41 on the combustion chamber 16 side. And a flange portion 42 as an extending portion. The decompression chamber 17 is defined by the cylindrical member 11, the closing member 14, and the flange portion 42 of the partition member 40, and is provided in a portion of the housing 10 near the closing member 14 (the left portion in the drawing).

  The partition member 40 has an axial end of the cylindrical portion 41 on the side where the flange portion 42 is not provided is inserted into a recess 14 b provided in the closing member 14 and is press-fitted and fixed. The end portion is fixed to the housing 10 by being press-fitted and fixed to the cylindrical member 11. Of the peripheral wall of the cylindrical member 11 adjacent to the flange portion 42, a caulking portion 13c is provided on the portion on the decompression chamber 17 side by reducing the diameter of the portion toward the radially inner side. In the caulking portion 13c, the above-described eight-side caulking is used, and the contact portion between the flange portion 42 of the partition member 40 and the cylindrical member 11 is thereby hermetically sealed.

  The decompression chamber 17 is partitioned into two chambers in the radial direction by the cylindrical portion 41 of the partition member 40. Specifically, the decompression chamber 17 is partitioned into an inner decompression chamber 17 a located inside the cylindrical portion 41 and an outer decompression chamber 17 b located outside the tubular portion 41. In addition, a first communication hole 43 that communicates the combustion chamber 16 and the inner decompression chamber 17a is provided at the axial end of the cylindrical portion 41 on the side where the flange portion 42 is provided. The tubular portion 41 is provided with a second communication hole 44 that communicates the inner decompression chamber 17a and the outer decompression chamber 17b. Among these, a plurality of second communication holes 44 are provided along the circumferential direction and the axial direction of the tubular portion 41. The tubular portion 41 and the flange portion 42 described above each function as a pressure partition that causes a pressure difference between the chambers during operation, and have a predetermined proof stress (mechanical strength). It is composed of. Specifically, the partition member 40 is made of a metal member such as stainless steel, steel, an aluminum alloy, or a stainless alloy.

  A filter 60 is accommodated in the outer decompression chamber 17b. The filter 60 is formed of a cylindrical member having a hollow opening extending in the same direction as the axial direction of the cylindrical member 11, and is provided so as to cover the second communication hole 44 provided in the cylindrical portion 41 described above. Yes. As the filter 60, for example, a wire or net made of a metal such as stainless steel or steel is wound in the circumferential direction, or pressed by pressing, or the like is used. When the filter 60 is made of a mesh material, a knitted wire mesh, a plain weave wire mesh, an assembly of crimped metal wires, or the like can be used. When the gas generated in the combustion chamber 16 passes through the filter 60, the filter 60 functions as a cooling means that cools the gas by taking away the high-temperature heat of the gas, and the slag contained in the gas. It also functions as a filtering means for removing water.

  The outer peripheral surface of the filter 60 accommodated and disposed in the outer decompression chamber 17b is disposed at a predetermined distance from the inner peripheral surface of the peripheral wall of the cylindrical member 11 facing the outer peripheral surface. Further, the axial end surface of the filter 60 on the combustion chamber 16 side is disposed at a predetermined distance from the surface of the flange portion 42 of the partition member 40 facing the axial end surface. Furthermore, the axial end surface of the filter 60 on the closing member 14 side is disposed with a predetermined distance from the surface on the inner surface side of the closing member 14 facing the axial end surface. Thus, the outer peripheral surface and the axial end surface of the filter 60 are not in contact with the housing 10 and the flange portion 42 of the partition member 40, and a space is formed between them.

  A gas outlet 12 is provided on the peripheral wall of the cylindrical member 11 that defines the outer decompression chamber 17b. The gas outlet 12 is a hole for releasing the gas generated inside the cylinder type gas generator 1 </ b> A to the outside, and a plurality of gas outlets 12 are provided along the circumferential direction and the axial direction of the cylindrical member 11.

  A female connector (not shown) is attached to the end of the cylinder type gas generator 1A where the holder 20 is disposed. This female connector is a part to which a male connector of a harness that transmits a signal from a collision detection sensor provided separately from the cylinder type gas generator 1A is connected. A shorting clip (not shown) is attached to the female connector as necessary. The shorting clip is attached to prevent the cylinder type gas generator 1A from malfunctioning due to electrostatic discharge or the like during the transportation of the cylinder type gas generator 1A. In the stage, the male connector of the harness is inserted into the female connector, so that the contact with the terminal pin 32 is released.

  Next, the operation | movement at the time of the action | operation of the cylinder type gas generator 1A demonstrated above is demonstrated. When a vehicle equipped with an airbag device incorporating the cylinder-type gas generator 1A according to the present embodiment collides, the collision is detected by a collision detection means provided separately in the vehicle, and ignition is performed based on this. The device 30 is activated. When the igniter 30 is activated, the pressure in the igniter 31 increases due to combustion of the igniting agent, whereby the igniter 31 is ruptured and the flame flows out of the igniter 31.

  After the ignition unit 31 is ruptured, the temperature and pressure in the ignition chamber 15 are increased, and the second sealed container 80 is melted or ruptured. As a result, the explosive charge 27 accommodated in the second sealed container 80 is ignited and burned by the flame generated by the operation of the igniter 30 and generates a large amount of heat particles. The large amount of generated heat particles reaches the combustion chamber 16 via the opening 25 a provided in the cup-shaped member 25.

  The hot particles that reach the combustion chamber 16 melt or rupture the first sealed container 70, burn the cushion material 51, open or divide it, and reach the gas generating agent 52. Thereby, the gas generating agent 52 is ignited and burned, and a large amount of combustion gas is generated. The generated combustion gas passes through the communication hole 18a provided in the porous plate 18, ruptures the first hermetic container 70 located at the tip thereof, and is a space (porous) in which the gas generating agent 52 in the combustion chamber 16 is not accommodated. A portion of the combustion chamber sandwiched between the plate 18 and the decompression chamber 17). Then, the combustion gas flows into the inner decompression chamber 17a via the first communication hole 43 provided at the axial end of the cylindrical portion 41 of the partition member 40 on the combustion chamber 16 side, and enters the inner decompression chamber 17a. Flow in the axial direction. At that time, the combustion gas is depressurized more than the pressure in the combustion chamber 16, and the temperature is also lowered with the depressurization.

  The combustion gas introduced into the inner decompression chamber 17a and decompressed flows into the outer decompression chamber 17b through the second communication hole 44 provided in the tubular portion 41 of the partition member 40. At that time, the combustion gas is cooled by the filter 60 disposed so as to cover the second communication hole 44, and the slag contained in the combustion gas is removed. Further, at that time, the combustion gas is depressurized more than the pressure in the inner decompression chamber 17a, and the temperature further decreases with the depressurization. Thereafter, the combustion gas reduced to a predetermined pressure and cooled to a predetermined temperature is discharged from the gas outlet 12 to the outside of the housing 10. The gas released from the gas outlet 12 is guided into the airbag to inflate and deploy the airbag.

  Next, the assembly procedure of the cylinder type gas generator 1A in the present embodiment will be described. First, as shown in FIG. 3A, a first sealed container 70 composed of a cup part 71 and a cap part 72 is prepared, and the porous plate 18 and the gas generating agent 52 are placed in the cup part 71 of the first sealed container 70. These are accommodated in the order of the cushion material 51. Then, the opening of the cup portion 71 is closed by the cap portion 72, and the cap portion 72 is joined to the cup portion 71. Next, as shown in FIG. 3 (B), a second sealed container 80 composed of a cup part 81 and a cap part 82 is prepared, and the transfer charge 27 is accommodated in the cup part 81 of the second sealed container 80. . Then, the opening of the cup part 81 is closed by the cap part 82, and the cap part 82 is joined to the cup part 81.

  Next, referring to FIG. 2, the closing member 14 is inserted into one end of the cylindrical member 11 in the axial direction and fixed by caulking, and the partition member 40 to which the filter 60 is assembled is inserted and fixed. . At that time, a caulking portion 13c is formed in advance at a predetermined position of the cylindrical member 11, and the flange portion 42 of the partition member 40 is brought into contact with the caulking portion 13c. The partition member 40 is fixed to the housing 10 by press-fitting the end of the tubular member 41 on the side where the flange portion 42 is not provided into the recess 14 b of the closing member 14.

  Next, the first sealed container 70 in which the gas generating agent 52 and the like described above are accommodated is inserted and fixed to the housing 10 in which the partition member 40 is assembled. At this time, the first sealed container 70 is press-fitted and fixed to the peripheral wall of the cylindrical member 11. Further, the end surface of the first sealed container 70 is stopped against the flange portion 42 of the partition member 40.

  Subsequently, with respect to the housing 10, these components are inserted into the housing in the order of the cup-shaped member 25, the second sealed container 80 in which the above-described transfer charge 27 is accommodated, and the holder 20 in which the igniter 30 is assembled. . Then, the holder 20 is caulked and fixed to the cylindrical member 11, and then the predetermined position of the cylindrical member 10 is caulked so that the cup-shaped member 25 is sandwiched between the cylindrical member 11 and the holder 20. Thus, the assembly of the cylinder type gas generator 1A configured as shown in FIGS. 1 and 2 is completed.

  In the cylinder type gas generator 1A in the present embodiment described above, the gas generating agent 52 is disposed in the combustion chamber 16 in a state of being sealed and accommodated by the first sealed container 70, and the transfer charge 27 is the second. The ignition chamber 15 is disposed in a state of being sealed and accommodated by the sealed container 80. Therefore, it is not necessary to perform a sealing process for hermetically sealing the gas generating agent 52 and the transfer agent 27 in the housing 10, and as a result, each part of the housing 10 is used by using a fragile member such as an O-ring or a sealing tape. It becomes unnecessary to perform the sealing process, and the sealing process for preventing the gas generating agent 52 and the transfer agent 27 from absorbing moisture is greatly facilitated. Therefore, by adopting the above-described configuration, it is possible to dramatically improve the workability at the time of assembly, and it is possible to provide a cylinder type gas generator that can suppress the manufacturing cost.

  Further, in the cylinder type gas generator 1A in the present embodiment, when the gas generating agent 52 is accommodated in the first sealed container 70, the perforated plate 18 and the cushion material 51 to be disposed in the combustion chamber 16 are gasified. Since it is configured to be previously accommodated and arranged in the first closed container 70 together with the generating agent 52, these members can be assembled to the housing 10 at a time in a sub-assembled state. Therefore, by adopting the above configuration, the assembly work can be further facilitated, and a cylinder-type gas generator that can further suppress the manufacturing cost can be obtained.

  Further, by using the above-described cylinder type gas generator 1A in the present embodiment, the combustion gas generated in the combustion chamber 16 by the combustion of the gas generating agent 52 is caused in the inner decompression chamber 17a and the outer decompression chamber 17b. The pressure is reduced in two stages in order, and the gas is discharged from the gas outlet 12 to the outside of the housing 10. Therefore, it is possible to sufficiently cool and depressurize the combustion gas discharged from the gas outlet 12, and it becomes easy to obtain desired output characteristics. Moreover, since the inner decompression chamber 17a and the outer decompression chamber 17b described above can be configured with a very simple configuration in which the partition member 40 having the flange portion 42 is disposed inside the housing 10, an assembly structure is provided. There is no problem of complication. Further, since the inner decompression chamber 17a and the outer decompression chamber 17b are partitioned in the radial direction, the gas generator itself does not increase in size. Therefore, it is possible to provide a gas generator that can be configured in a relatively simple and compact configuration for obtaining desired combustion characteristics.

  In addition, by using the cylinder type gas generator 1A in the present embodiment, the combustion gas that has been decompressed and cooled in the inner decompression chamber 17a is blown to the filter 60, and therefore the filter 60 is damaged. The risk is reduced, and the required volume of the filter 60 can be reduced. Moreover, since the flow of the combustion gas passing through the filter 60 can be made more uniform in the filter 60, the filter 60 can be used efficiently. Further, since the combustion gas after passing through the filter 60 is discharged from the gas outlet 12 through the space of the outer decompression chamber 17b where the filter 60 is not located, the gas injection can be performed more uniformly and stably. Combustion gas is released from the outlet 12. Therefore, the filter 60 can be prevented from being damaged, and the filter 60 can be efficiently used. Therefore, the filter 60 can be reduced in size, and a high performance, small and light gas generator can be obtained.

  Further, if the filter 60 has a configuration in which a metal wire is wound around the tubular portion 41 of the partition member 40, the deformation of the filter 60 toward the radially outer side is suppressed. Generation | occurrence | production of the malfunction that the filter 60 deform | transforms and the gas jet nozzle 12 causes clogging can be prevented now. In addition, by adopting the above configuration, the filter 60 can be assembled to the partition member 40 in advance before fixing the partition member 40 to the housing 10, so that the assembly work is greatly facilitated. A gas generator can be manufactured at low cost.

4 is a schematic cross-sectional view taken along the line IV-IV shown in FIG. 2, and FIG. 5 is a schematic cross-sectional view taken along the line V-V shown in FIG. As shown in FIG. 4, in the cylinder type gas generator 1 </ b> A according to the present embodiment, the first communication hole 43 is configured by a single hole, and the opening area S <b> 1 is the first communication hole 43. the diameter when the phi _1, represented by _{S1 = π × (φ 1/} 2) 2. Further, as shown in FIG. 5, in the cylinder type gas generator 1A according to the present embodiment, the second communication hole 44 is constituted by a plurality of holes, and the sum S2 of the opening areas is the second diameter per one of the communication hole 44 and phi _2, when the number is n, is represented by S2 = n × π × (φ 2/2) 2. Further, as shown in FIG. 2 (C), in the cylinder type gas generator 1A in the present embodiment, the gas outlet 12 is constituted by a plurality of holes, and the sum S3 of the opening areas is diameter per one gas injection port 12 and phi _3, when the number is m, is represented by S3 = m × π × (φ 3/2) 2.

  Here, when these S1, S2, and S3 satisfy the relationship of S1 <S2 and S1 <S3, the flange portion 42 of the partition member 40 mainly has an aperture stop plate for reducing the pressure of the combustion gas (that is, It will function as a pressure partition). In that case, S1 / S2 and S1 / S3 are preferably adjusted to be in the range of 0.25 to 1, respectively. When configured in this manner, the cylindrical member 11 at the portion defining the outer decompression chamber 17b and the cylindrical portion 41 of the partition member 40 can be thinned to some extent. Further, when these S1, S2, and S3 are configured to satisfy the relationship of S1 <S2 <S3, both the flange portion 42 and the cylindrical portion 41 of the partition member 40 are for reducing the combustion gas. It functions as an aperture diaphragm (ie, a pressure partition), and the pressure applied to the housing and the partition member 40 can be dispersed.

  On the other hand, when these S1, S2, and S3 satisfy the relationship of S2 <S1 and S2 <S3, the cylindrical portion 41 of the partition member 40 mainly has an aperture stop plate for reducing the pressure of the combustion gas (that is, It will function as a pressure partition). In that case, S2 / S1 and S2 / S3 are preferably adjusted to be in the range of 0.25 to 1, respectively. When configured in this manner, the cylindrical member 11 at the portion defining the outer decompression chamber 17b and the flange portion 42 of the partition member 40 can be thinned to some extent.

  6 to 10 are enlarged cross-sectional views of the main part showing the internal structure of the cylinder type gas generator according to the first to fifth modifications of the present embodiment. Next, the structure of the cylinder type gas generator according to the first to fifth modifications of the present embodiment will be described with reference to FIGS.

  In the cylinder type gas generator 1B according to the first modification shown in FIG. 6, the axial end surfaces of the hollow cylindrical filter 60 accommodated in the outer decompression chamber 17b are respectively flange portions 42 of the partition members 40. And the inner surface of the closing member 14 are in contact with each other. And the 2nd communicating hole 44 is provided in alignment over the substantially whole area of the axial direction of the cylindrical part 41 of the division member 40. As shown in FIG. Even when configured in this manner, the same effect as that obtained when the cylinder-type gas generator 1A according to the present embodiment is used can be obtained.

  In the cylinder type gas generator 1C according to the second modified example shown in FIG. 7, the bent portion 42a is continuously extended from the outer peripheral end portion of the flange portion 42 of the partition member 40, and the cylindrical member 11 is provided. When the partition member 40 is assembled and fixed, the outer peripheral surface of the bent portion 42a is configured to be in pressure contact with the inner peripheral surface of the cylindrical member 11. When configured in this manner, the same effect as that obtained in the case of the cylinder type gas generator 1A in the present embodiment described above can be obtained, and elasticity toward the outside of the bent portion 42a can be obtained. Since the pressure member makes the pressure contact between the partition member 40 and the cylindrical member 11, the cylindrical member 11 and the partition member by caulking performed in the cylinder type gas generator 1 </ b> A in the above-described embodiment. Fixing with the 40 flange portions is unnecessary, and further assembly work can be facilitated.

  In the cylinder type gas generator 1D according to the third modification shown in FIG. 8, the extending portion that extends continuously from the axial end surface on the combustion chamber 16 side of the cylindrical portion 41 of the partition member 40 is provided. The tapered portion 45 extends from the tubular portion 41 in an inclined manner toward the radially outer side. In such a configuration, the combustion chamber 16 reaches the inside of the tapered portion 45 of the partition member 40, and also in this case, the combustion chamber 16 and the outer decompression chamber 17 b are extended from the partition member 40. It is divided by the taper part 45 as a part. Here, the tapered portion 45 of the partition member 40 is press-fitted and fixed to the cylindrical member 11. When configured in this way, the same effect as that obtained when the cylinder type gas generator 1A in the present embodiment described above can be obtained, and an elastic biasing force toward the outside of the tapered portion 45 can be obtained. Since the pressure contact between the partition member 40 and the cylindrical member 11 is realized by the above, the cylindrical member 11 and the partition member 40 are crimped by the caulking performed in the cylinder type gas generator 1A in the above-described embodiment. Fixing to the flange portion is unnecessary, and further assembly work can be facilitated.

  In the cylinder type gas generator 1E according to the fourth modification shown in FIG. 9, a hollow cylindrical filter 60 is disposed in the inner decompression chamber 17a. Specifically, by adopting a configuration in which the filter 60 is press-fitted into the tubular portion 41 of the partition member 40, the second communication hole 44 provided in the tubular portion 41 is covered by the press-fitted filter 60. It is configured. Even when configured in this manner, the same effect as that obtained when the cylinder-type gas generator 1A according to the present embodiment is used can be obtained.

  In the cylinder type gas generator 1F according to the fifth modification shown in FIG. 10, a bottomed cylindrical member having a bottom portion 11a is used as the cylindrical member 11 and a bottomed tube having a bottom portion 46 as the partition member 40 is used. A shaped member is used. Then, the assembly of the partition member 40 to the cylindrical member 11 is realized by the contact between the bottom portion 11 a of the cylindrical member 11 and the bottom portion 46 of the partition member 40. Even when configured in this manner, the same effect as that obtained when the cylinder-type gas generator 1A according to the present embodiment is used can be obtained.

  In the above-described embodiment and its modifications, the case where the present invention is applied to a cylinder-type gas generator incorporated in a side airbag device has been described as an example. However, the present invention is not limited to a cylinder-type gas generator incorporated in a passenger-side airbag device, or a so-called T-shaped gas generator having a long output portion in the same manner as the cylinder-type gas generator. Applicable.

  As described above, the above-described embodiment and its modified examples disclosed herein are illustrative and non-restrictive in every respect. The technical scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is the front view and right view which show the external appearance structure of the cylinder type gas generator in one embodiment of this invention. It is a schematic cross section which shows the internal structure of the cylinder type gas generator in one embodiment of this invention. It is a schematic cross section which shows the state before the assembly | attachment to the housing of the 1st airtight container and the 2nd airtight container shown in FIG. It is a schematic cross section along the IV-IV line shown in FIG. It is a schematic cross section along the VV line shown in FIG. It is a principal part expanded sectional view which shows the internal structure of the cylinder type gas generator which concerns on the 1st modification of one embodiment of this invention. It is a principal part expanded sectional view which shows the internal structure of the cylinder type gas generator which concerns on the 2nd modification of one embodiment of this invention. It is a principal part expanded sectional view which shows the internal structure of the cylinder type gas generator which concerns on the 3rd modification of one embodiment of this invention. It is a principal part expanded sectional view which shows the internal structure of the cylinder type gas generator which concerns on the 4th modification of one embodiment of this invention. It is a principal part expanded sectional view which shows the internal structure of the cylinder type gas generator which concerns on the 5th modification of one embodiment of this invention.

Explanation of symbols

  1A to 1F Cylinder type gas generator, 10 housing, 11 cylindrical member, 11a bottom, 12 gas outlet, 13a to 13d, caulking portion, 14 closing member, 14a groove, 14b recess, 15 ignition chamber, 16 combustion chamber, 17 Decompression chamber, 17a inner decompression chamber, 17b outer decompression chamber, 18 perforated plate, 18a communication hole, 20 holder, 21 groove, 22 hollow portion, 24 resin molded portion, 25 cup-shaped member, 25a opening, 27 explosive charge, 30 Igniter, 31 ignition part, 32 terminal pin, 40 partition member, 41 cylindrical part, 42 flange part, 42a bent part, 43 first communication hole, 44 second communication hole, 45 taper part, 46 bottom part, 51 cushion material , 52 Gas generating agent, 60 filter, 70 1st airtight container, 71 Cup part, 72 Cap part, 73 Storage space, 80 2 closed container, 81 cup portion 82 cap portion 83 accommodating space.

Claims (12)

A long cylindrical housing that includes a gas outlet and is closed at both axial ends;
A combustion chamber that is located inside the housing and in which combustion gas is generated by burning the gas generating agent;
A decompression chamber that is located inside the housing and depressurizes the pressure of the combustion gas that flows in by the combustion gas generated in the combustion chamber flowing in, and that guides the decompressed combustion gas to the gas outlet;
Ignition means for burning the gas generating agent,
A first sealed container having a sealed storage space is disposed in the combustion chamber,
In order to prevent crushing of the gas generating agent due to vibration, the gas generating agent, an intrusion preventing member for preventing the gas generating agent from entering the decompression chamber, and the accommodating space of the first sealed container. A gas generator in which an anti-crushing member is arranged. The combustion chamber and the decompression chamber are provided side by side in the axial direction of the housing inside the housing,
The gas generator according to claim 1, wherein the first closed container is disposed in the combustion chamber by being press-fitted and fixed inside the housing.   The gas generator according to claim 2, wherein the entry preventing member is disposed at an end portion on the decompression chamber side in the accommodating space of the first sealed container. The ignition means is provided at a position opposite to the decompression chamber of the combustion chamber,
The gas generator according to claim 2 or 3, wherein the anti-crushing member is disposed at an end portion on the ignition means side in the accommodating space of the first sealed container. An ignition chamber located inside the housing and containing the ignition means;
The ignition means includes an igniter including an igniter that generates a flame by combustion, and a transfer agent that transmits the flame generated in the igniter to the gas generating agent.
In the ignition chamber, a second sealed container having a sealed storage space is disposed,
The gas generator according to any one of claims 1 to 4, wherein the transfer charge is disposed in the accommodation space of the second sealed container.   6. The gas generator according to claim 1, wherein the intrusion prevention member is a plate-like member including a plurality of openings having a size smaller than an outer shape of the gas generating agent.   The gas generator according to claim 1, wherein the anti-crushing member is made of an elastically deformable member. A partition member located inside the housing and defining a space inside the housing;
A filter disposed in the decompression chamber,
The partition member is disposed coaxially with the housing to thereby divide the decompression chamber into an inner decompression chamber and an outer decompression chamber in the radial direction, and one axial end of the tubular portion An extended portion that divides the space inside the housing into the combustion chamber and the decompression chamber by being continuously extended radially outward from the combustion chamber,
A first communication hole that communicates the combustion chamber and the inner decompression chamber is provided at an axial end located on the side where the extending portion of the cylindrical portion is provided,
The cylindrical portion is provided with a second communication hole that communicates the inner decompression chamber and the outer decompression chamber,
The gas ejection port is provided only on the peripheral wall of the housing in a portion defining the outer decompression chamber,
The second communication hole has at least one opening surface thereof covered by the filter,
The extending portion serves as a pressure partition that creates a pressure difference between the combustion chamber and the outer decompression chamber in a state where the gas generating agent is burned,
The gas according to any one of claims 1 to 7, wherein the cylindrical portion serves as a pressure partition wall that generates a pressure difference between the inner decompression chamber and the outer decompression chamber in a state where the gas generating agent is combusted. Generator.   The gas generator according to claim 8, wherein the filter has a hollow cylindrical shape and is disposed in the outer decompression chamber.   The gas generator according to claim 9, wherein the filter is made of a metal wire wound around the cylindrical portion.   The gas generator according to claim 8, wherein the filter has a hollow cylindrical shape and is disposed in the inner decompression chamber.   The gas generator according to any one of claims 8 to 11, wherein a plurality of the second communication holes are equally provided in the cylindrical portion of the portion covered with the filter.

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