JP2009241634A - Gas generator and filter for gas generator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas generator having a simple constitution capable of more surely preventing outflow of combustion gas from a gap between a filter and a housing and more efficiently utilizing the filter. <P>SOLUTION: This gas generator 1A has the short-sized cylindrical housing including an initiator shell 20 and a closure cell 30. In the housing, an igniter 13, a combustion chamber 50 and the filter 60 are provided. In the combustion chamber 50, gas generation agent 51 is stored. The igniter 13 is provided to face the combustion chamber 50. The filter 60 includes a cylindrical part 61 for surrounding the combustion chamber 50 and an extension part 62 extended along a bottom plate part 21 of the housing from an axial direction end part of the filter 60 abutting on the bottom plate part 21 toward the radial direction inside. In this case, the space factor of the filter 60 in the extension part 62 is larger than that in the cylindrical part 61. The extension part 62 does not substantially have air ventilating property. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a gas generator incorporated in an occupant protection device and a gas generator filter used therefor, and more specifically, a gas generator incorporated in an airbag device mounted on a steering wheel of an automobile and the like. The present invention relates to a filter for a gas generator used in the above.

  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. The airbag device is equipped for the purpose of protecting the occupant from the impact caused by the collision of the vehicle or the like. By inflating and deploying the airbag instantaneously at the time of the collision of the vehicle or the like, the airbag functions as a cushion of the occupant. It is to catch the body. The gas generator is incorporated in the airbag device, and igniters (squibs) are ignited by energization from the control unit (actuator) in the event of a vehicle collision, etc., and the gas generating agent is combusted by the flame generated in the igniter. This is a device that instantly generates the combustion gas and inflates and deploys the airbag. Note that the airbag device is mounted on, for example, an automobile steering wheel or an instrument panel.

  There are various types of gas generators, and there is a so-called disk-type gas generator as a gas generator that is suitably used for a driver side airbag device equipped on a steering wheel or the like. . A disk-type gas generator has a short cylindrical housing closed at both ends in the axial direction, a gas outlet is provided on the peripheral wall of the housing, and a gas generating agent, an igniter, and the like are accommodated inside the housing. It will be. In this disk-type gas generator, it is general that a filter is accommodated in the housing so as to surround a combustion chamber in which a gas generating agent is accommodated. The filter functions as a collecting unit that collects a residue (slag) contained in the combustion gas, and also functions as a cooling unit that lowers the temperature of the combustion gas as it passes through the inside.

  In the disk-type gas generator having the above-described configuration, if no measures are taken, a part of the combustion gas flows out from the gap between the filter and the housing during operation and does not pass through the inside of the filter. There is a problem that combustion gas is ejected from the ejection port. Normally, a configuration is adopted in which the housing is pressed against the filter so that such a gap does not occur. However, the internal pressure in the combustion chamber is very high during operation, so in some cases the housing is slightly May cause the above-mentioned gap.

  When the combustion gas flows out from such a gap, not only the desired output characteristics are not obtained, but also the combustion gas is not sufficiently cooled, or the combustion gas is injected into the combustion gas from the gas generator. It may contain a lot of slag. As a result, the airbag may not be intended to be inflated or deployed, or the airbag may be seriously damaged.

  In order to solve such problems, in recent disk-type gas generators, in order to prevent the combustion gas from flowing out from the gap, the inner peripheral surface of the filter defining the combustion chamber, the inner surface of the housing, In general, a configuration is adopted in which a metal outflow prevention member is disposed along the inner surface of the filter, and the outflow prevention member is in pressure contact with the inner peripheral surface of the filter and the inner surface of the housing. As a document disclosing such a configuration, for example, there is Patent Document 1 (Japanese Patent Laid-Open No. 10-287197).

  However, when such a configuration is adopted, it is necessary to dispose the above-described outflow prevention member on each of the top plate portion side and the bottom plate portion side of the housing, and the assembly work accompanying the increase in the number of parts is complicated. This leads to a problem that presses down the manufacturing cost. In addition, since the outflow prevention member is configured to partially cover the inner peripheral surface of the filter, the combustion gas is prevented from flowing into the filter in the portion covered by the outflow prevention member. As a result, the filter There is also a problem that the entire system cannot be used efficiently.

Therefore, as a structure that can prevent the outflow of gas from the above-described gap without increasing the number of parts and that enables efficient use of the filter, it is disclosed in Patent Document 2 (Japanese Patent Laid-Open No. 2003-40074). A gas generator having the structure as described above has been proposed. In the gas generator disclosed in Patent Document 2, the axial end of the cylindrical portion of the filter is extended inward, and the extended portion is arranged along the inner surface of the housing. Trying to prevent the occurrence of problems.
JP-A-10-287197 Japanese Patent Laid-Open No. 2003-40074

  However, even when the structure of the gas generator as disclosed in Patent Document 2 is adopted, if the thickness of the extending portion of the filter is not sufficiently increased, the outflow of combustion gas from the gap is also prevented. I can't do it. This is because when the extended portion of the filter is made thin, the slag collecting function and the cooling function are secured to some extent as compared with the case where the extended portion is not provided, but the extended portion has passed. This is because a part of the combustion gas may wrap around the gap without flowing into the cylindrical portion of the filter. Therefore, in order to completely prevent the combustion gas from flowing out from the above-mentioned gap, it is inevitably necessary to make the extending portion of the filter as thick as the cylindrical portion, and such a configuration is adopted. In this case, a problem such as an increase in the size of the apparatus and a problem of an increase in weight are caused.

  Therefore, the present invention has been made to solve the above-described problems, and can more reliably prevent the outflow of combustion gas from the gap between the filter and the housing, and the filter can be made more efficient. An object of the present invention is to provide a gas generator having a simple configuration that can be used for the above and a filter for the gas generator used in the gas generator.

  A gas generator according to the present invention includes a housing, ignition means, and a filter. The housing is composed of a short cylindrical member composed of a top plate portion and a bottom plate portion that close both ends in the axial direction, and a peripheral wall portion provided with a gas ejection port, and a combustion chamber in which a gas generating agent is accommodated. Is included inside. The ignition means is attached to the bottom plate so as to face the combustion chamber, and the filter is disposed in the housing. The filter includes a cylindrical portion that surrounds the combustion chamber in the radial direction of the housing, an axial end portion that contacts the top plate portion of the filter, and an axial end portion that contacts the bottom plate portion of the filter. And an extending portion extending along the top plate portion or the bottom plate portion from the at least one of them toward the inside in the radial direction. Here, the space factor of the filter in the extended portion is larger than the space factor of the filter in the tubular portion. The filter space factor is a value indicating the ratio of the volume occupied by the filter material per unit volume of the space where the filter is located.

  By configuring in this way, combustion gas may flow between the axial end of the filter and the housing during operation due to the presence of the relatively high space extending portion provided in the filter. It can be surely prevented. Further, it is not necessary to separately provide an outflow prevention member for closing the gap between the axial end of the filter and the housing at the portion where the extending portion is disposed. Furthermore, it is possible to reduce the thickness of the extended portion, and the apparatus does not increase in size. Therefore, it is possible to provide a gas generator having a simple configuration that can more reliably prevent the combustion gas from flowing out from the gap between the filter and the housing and that can more efficiently use the filter. it can.

  In the gas generator according to the present invention, it is preferable that the extended portion has substantially no air permeability. By comprising in this way, it can be set as the gas generator by which the outflow of the combustion gas from the said clearance gap was prevented reliably.

  In the gas generator based on the said invention, it is preferable that the said filter is comprised with the cylindrical member formed by winding a metal wire. Patent Document 2 described above describes forming a filter by embossing an aggregate of metal wires. However, when a filter is manufactured by such a method, the space factor of the filter is made different between the tubular portion and the extending portion of the filter, or the air permeability is changed between these portions. It is not easy to do. On the other hand, by using the filter formed by winding the metal wire as described above, the deformation of the filter toward the radially outer side can be suppressed, and the space factor of the filter can be reduced. Differentiating each part can be performed relatively easily, and the air permeability of each part of the filter can be changed. Therefore, it can be set as a high-performance gas generator at low cost. When the filter is formed by winding a metal wire in this way, either the winding pattern of the metal wire or the winding tension of the metal wire is changed between the cylindrical portion and the extending portion in the manufacturing process. By making them different, it becomes possible to cause a difference between the space factor of the cylindrical portion and the space factor of the extended portion as described above.

  The gas generator filter according to the present invention has a short cylindrical shape including a cylindrical portion and an extending portion. The cylindrical portion is formed in a hollow shape, and the extending portion extends radially inward from at least one of the axial ends of the gas generator filter. Here, the space factor in the extension part is larger than the space factor in the cylindrical part.

  By setting it as the filter of such a structure, it can be set as the filter for gas generators which can prevent more reliably that combustion gas flows between the axial direction edge part of a filter and a housing at the time of an action | operation.

  ADVANTAGE OF THE INVENTION According to this invention, the gas generator of the simple structure which can prevent the outflow of the combustion gas from the clearance gap between a filter and a housing more reliably, and can utilize a filter more efficiently. And it can be set as the filter for gas generators used for this.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the embodiment described below, the present invention is applied to a so-called disk-type gas generator incorporated in an airbag device mounted on a steering wheel or the like of an automobile.

(Embodiment 1)
FIG. 1 is a schematic cross-sectional view of a gas generator according to Embodiment 1 of the present invention. First, with reference to FIG. 1, the structure of the gas generator in this Embodiment is demonstrated.

  As shown in FIG. 1, the gas generator 1A according to the present embodiment has a short cylindrical housing closed at both ends in the axial direction, and various components are accommodated inside the housing. Yes. The short cylindrical housing is formed by combining an initiator shell 20 and a closure shell 30 each formed in a bottomed cylindrical shape. More specifically, the initiator shell 20 includes a bottom plate portion 21 and a peripheral wall portion 22, and the closure shell 30 includes a top plate portion 31 and a peripheral wall portion 32. By being combined so that the open ends of the shell 30 face each other, a space for accommodating various components is formed therein.

  Each of the initiator shell 20 and the closure shell 30 is made of a metal member such as stainless steel, steel, an aluminum alloy, or a stainless alloy. More specifically, the initiator shell 20 and the closure shell 30 are each made of forging, drawing, pressing, or the like using a die or the like from one plate-shaped or one-piece block-shaped metal member, or a combination thereof. Formed by. For joining the initiator shell 20 and the closure shell 30, electron beam welding, laser welding, friction welding, or the like is preferably used.

  An opening 23 is provided substantially at the center of the bottom plate portion 21 of the initiator shell 20, and the igniter assembly 10 is fixed to the bottom plate portion 21 of the initiator shell 20 so as to close the opening 23. More specifically, the igniter assembly 10 is inserted from the inside into an opening 23 provided in the bottom plate portion 21 of the initiator shell 20, and a predetermined portion of the inserted igniter assembly 10 is joined to the initiator shell 20. As a result, the igniter assembly 10 is fixed to the housing. For joining the igniter assembly 10 and the initiator shell 20, electron beam welding, laser welding, friction welding, resistance welding, or the like is preferably used.

  As shown in FIG. 1, the igniter assembly 10 includes a holder 11, an igniter 12, and a resin molding portion 13. The holder 11 has a substantially cylindrical shape having a hollow opening extending in the axial direction, and an igniter 12 disposed in the hollow opening fills a space between the holder 11 and the igniter 12. The igniter assembly 10 is configured by being fixed to the holder 11 by the resin molding portion 13 provided to do so. In addition, as the holder 11, metal members, such as stainless steel, steel, an aluminum alloy, and a stainless alloy, are used.

  The igniter 12 is an ignition device for generating a flame, and includes an ignition part 12a and a terminal pin 12b. The ignition unit 12a includes therein an igniting agent that ignites during operation and a resistor for burning the igniting agent. The terminal pin 12b is connected to the ignition part 12a in order to ignite the igniting agent. More specifically, the igniter 12a includes a base for inserting and holding the pair of terminal pins 12b, and a squib cup attached on the base, and the tip of the terminal pin 12b inserted into the squib cup is used as the igniter 12a. A resistor (bridge wire) is attached so as to be connected, and an igniting agent is filled in the squib cup so as to surround or be 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. A connector (not shown) of a harness for connecting the igniter 12 and the control unit is connected to the terminal pin 12b.

  When a collision is detected, a predetermined amount of current flows through the resistor via the terminal pin 12b. When a predetermined amount of current flows through the resistor, Joule heat is generated in the resistor, and the ignition agent starts burning. 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 12 is activated is generally 3 milliseconds or less when a nichrome wire is used as the resistor.

  As described above, the resin molding portion 13 is positioned so as to fill the space between the igniter 12 and the holder 11 disposed in the hollow opening of the holder 11. The resin molded portion 13 is formed by, for example, insert molding, and as a raw material, a thermosetting resin typified by an epoxy resin or the like, a polybutylene terephthalate resin, a polyethylene terephthalate resin, a polyamide resin (for example, nylon 6, nylon 66, etc.) ), Thermoplastic resins represented by polypropylene sulfide resin, polypropylene oxide resin and the like can be used.

  As shown in FIG. 1, a bottomed cylindrical cup member 40 is attached to the igniter assembly 10 fixed to the bottom plate portion 21 of the initiator shell 20 so as to cover the igniter 12. The cup member 40 has a top wall portion 40a, a side wall portion 40b, and a flange portion 40c, and includes a heat transfer chamber 43 in which a charge transfer agent 44 is accommodated. The cup member 40 is fixed to the holder 11 so that the heat transfer chamber 43 provided therein faces the ignition part 12a of the igniter 12. More specifically, the cup member 40 is fixed to the holder 11 by caulking the flange portion 40 c of the cup member 40 by the caulking portion 11 a provided on the holder 11.

  The cup member 40 has an opening 41 in the side wall 40b. A seal member 42 is affixed to the side wall portion 40 b of the cup member 40 so as to close the opening 41. The seal member 42 is a member for preventing the transfer charge 44 from entering a combustion chamber 50, which will be described later, during non-operation. Preferably, an aluminum foil or the like having an adhesive member applied on one side is used.

The transfer charge 44 filled in the transfer chamber 43 is ignited by a flame generated by the operation of the igniter 12 and burns to generate hot particles. The charge transfer agent 44 must be capable of reliably starting the combustion of a gas generating agent 51, which will be described later, and is generally a metal powder / oxidant represented by B / KNO ₃ or the like. A composition or the like is used. As the charge transfer agent 44, 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.

  As shown in FIG. 1, a combustion chamber in which a gas generating agent 51 is accommodated in a space surrounding a portion where the above-described cup member 40 is disposed in the space inside the housing formed of the initiator shell 20 and the closure shell 30. 50 is located. More specifically, the above-described cup member 40 is disposed so as to protrude into a combustion chamber 50 formed inside the housing, and a portion and a side wall facing the outer surface of the top wall portion 40a of the cup member 40. A space provided in a portion facing the outer surface of the portion 40 b is configured as a combustion chamber 50. Further, a filter 60 is disposed along the inner periphery of the housing in a space surrounding the combustion chamber 50 in which the gas generating agent 51 is accommodated. The filter 60 has a substantially cylindrical shape, and the central axis thereof is disposed so as to substantially coincide with the axial direction of the housing. A predetermined space is formed between the outer peripheral surface of the filter 60 and the inner peripheral surfaces of the peripheral wall portions 22 and 32 of the housing (outer peripheral edge portion of the housing).

  The gas generating agent 51 is ignited by hot particles generated by burning the charge transfer agent 44 ignited by the igniter 12, and generates gas by burning. The gas generating agent 51 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 51 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 selected as appropriate according to the specifications of the airbag apparatus in which the gas generator 1A is incorporated. For example, the shape in which the gas generation rate changes with time during the combustion of the gas generating agent 51 is selected. It is preferable to select an optimal shape according to the specifications. In addition to the shape of the gas generating agent 51, it is preferable to appropriately select the size and filling amount of the molded body in consideration of the linear combustion rate of the gas generating agent 51, the pressure index, and the like.

  The filter 60 includes a cylindrical portion 61 that surrounds the combustion chamber 50 in the radial direction of the housing, and an extending portion 62 that extends radially inward along the bottom plate portion 21 of the initiator shell 20. The extending portion 62 is provided at the end of the cylindrical portion 61 on the bottom plate portion 21 side, and has an outer shape that is annular, and its lower surface is in pressure contact with the bottom plate portion 21 of the initiator shell 20. ing. Preferably, the inner peripheral end of the extending portion 62 is in contact with the caulking portion 11a of the holder 11 described above. The filter 60 is manufactured by, for example, winding a metal wire such as stainless steel or steel, and the cylindrical portion 61 and the extending portion 62 described above are configured as a continuous and integral member.

  Here, the cylindrical part 61 of the filter 60 has sufficient air permeability. The cylindrical portion 61 functions as a cooling means for cooling the combustion gas by taking the high-temperature heat of the combustion gas when the combustion gas generated in the combustion chamber 50 passes through the cylindrical portion 61. Also, it functions as a collecting means for collecting slag contained in the combustion gas. That is, the cylindrical part 61 of the filter 60 corresponds to a filter function part that exhibits a function as a filter. On the other hand, the extending part 62 of the filter 60 has substantially no air permeability. The extending portion 62 prevents the flow of combustion gas flowing out between the axial end portion of the cylindrical portion 61 that is a filter function portion and the bottom plate portion 21 of the initiator shell 20. It functions as a combustion gas outflow prevention means. That is, the extended portion 62 of the filter 60 does not exhibit a function as a filter, and corresponds to an outflow prevention function portion that functions as a combustion gas outflow prevention means.

  As shown in FIG. 1, a plurality of gas outlets 33 are provided on the peripheral wall portion 32 of the closure shell 30 that faces the filter 60. The gas ejection port 33 is a hole for leading the combustion gas that has passed through the filter 60 to the outside of the housing. A seal member 34 is attached to the inner peripheral surface of the closure shell 30 so as to close the gas ejection port 33. The seal member 34 is a member for ensuring the airtightness of the combustion chamber 50 when not in operation, and preferably an aluminum foil or the like having an adhesive member applied on one side is used.

  An outflow prevention member for preventing combustion gas from flowing out from the gap between the tubular portion 61 of the filter 60 and the closure shell 30 at the end of the combustion chamber 50 on the top plate portion 31 side of the closure shell 30. 54 is arranged. The outflow prevention member 54 is formed by pressing a plate-like member made of metal such as stainless steel or steel, and is in contact with the inner peripheral surface of the upper end portion of the tubular portion 61 of the filter 60. And an annular member having a portion that contacts the top plate portion 31 of the closure shell 30. Here, since the outflow prevention member 54 is formed by bending a metal plate-like member, the outflow prevention member 54 has appropriate elasticity, and the outflow prevention member 54 has an inner peripheral surface of the filter 60. In addition, each of the top plate portions 31 of the closure shell 30 is in appropriate pressure contact.

  Inside the outflow prevention member 54, a cushion material 52 is arranged so as to contact the gas generating agent 51 accommodated in the combustion chamber 50. The cushion material 52 is provided for the purpose of preventing the gas generating agent 51 made of a molded body from being pulverized by vibration or the like, and a ceramic fiber molded body, foamed silicon, or the like is preferably used.

  Next, an example of the procedure for assembling the gas generator 1A shown in FIG. 1 will be described with reference to FIG. The description of the manufacturing procedure of the igniter 12 is omitted.

  First, the igniter assembly 10 is manufactured by fixing the igniter 12 to the holder 11 by insert molding or the like. Subsequently, the inside of the cup member 40 whose opening 41 has been previously closed by the seal member 42 is filled with the transfer charge 44, and the cup member 40 filled with the transfer charge 44 is caulked to the holder 11 of the igniter assembly 10. Fix it. Next, the igniter assembly 10 to which the cup member 40 is attached is inserted into the opening 23 of the initiator shell 20, and the igniter assembly 10 and the initiator shell 20 are fixed by welding or the like.

  Next, the filter 60 is inserted into the initiator shell 20 so that the end of the filter 60 on the side where the extended portion 62 is provided contacts the bottom plate portion 21 of the initiator shell 20. At this time, the filter 60 is centered by the inner peripheral end of the extending portion 62 of the filter 60 and the outer peripheral end of the holder 11. Subsequently, the gas generating agent 51 is filled inside the filter 60, and the outflow prevention member 54 interposed with the cushion material 52 is inserted into the upper end portion of the filter 60.

  Thereafter, the closure shell 30 whose gas outlet 33 is closed by the sealing member 34 is placed on the initiator shell 20, and the top plate portion 31 of the closure shell 30 is brought into pressure contact with the upper surface of the filter 60 while maintaining the state. The closure shell 30 and the initiator shell 20 are fixed by welding or the like. Thus, the assembly of the gas generator 1A having the configuration shown in FIG. 1 is completed.

  Next, operation | movement of 1 A of gas generators in this Embodiment is demonstrated with reference to the same figure. When a vehicle on which the gas generator 1A according to the present embodiment is mounted collides, the collision is detected by a collision detection unit provided separately in the vehicle, and the igniter 12 is activated based on this. The transfer charge 44 accommodated in the transfer chamber 43 is ignited and burned by the flame generated by the operation of the igniter 12, and generates a large amount of heat particles. When the pressure in the cup member 40 increases due to the combustion of the transfer powder 44, the sealing by the sealing member 42 that has closed the opening 41 is broken, and the above-described hot particles are transferred to the combustion chamber 50 through the opening 41. Flow into.

  The gas generating agent 51 accommodated in the combustion chamber 50 is ignited and burned by the flowing heat particles, and a large amount of combustion gas is generated. The combustion gas generated in the combustion chamber 50 passes through the cylindrical portion 61 of the filter 60, and at that time, heat is taken away and cooled by the filter 60, and the slag contained in the combustion gas is the cylindrical shape of the filter 60. It is removed by the portion 61 and flows into the outer peripheral edge of the housing. As the internal pressure of the housing increases, the sealing by the sealing member 34 that has closed the gas outlet 33 of the closure shell 30 is broken, and combustion gas is jetted out of the housing through the gas outlet 33. The jetted gas is introduced into an airbag provided adjacent to the gas generator 1A, and the airbag is inflated and deployed.

  As described above, in the gas generator 1A in the present embodiment, the filter 60 is configured by the cylindrical portion 61 as the filter function portion and the extending portion 62 as the combustion gas outflow prevention function portion. Yes. Here, the cylindrical part 61 as the filter function part is formed to have sufficient air permeability, and the extending part 62 as the outflow prevention function part has substantially no air permeability. Is formed. The presence or absence of this air permeability is determined by adjusting the space factor in the tubular portion 61 of the filter 60 and the space factor in the extending portion 62 of the filter 60. Here, the space factor is a value indicating the ratio of the volume occupied by the filter material per unit volume of the space where the filter is located, and the larger the ratio, the larger the volume occupied by the material, and the air permeability is Will be reduced. That is, a large space factor means that the filter material is relatively densely arranged, and a small space factor means that the filter material is relatively sparsely arranged. Means that

  In the gas generator 1A according to the present embodiment, the space factor in the extending portion 62 of the filter 60 is larger than the space factor of the tubular portion 61 of the filter 60. For example, when a band-shaped metal wire having a rectangular cross-sectional shape is used as the material of the filter 60, the space factor in the extending portion 62 of the filter 60 is approximately 55% or more (as an example, 60% ± 5 %), And the space factor in the cylindrical portion 61 of the filter 60 is approximately 45% or less (for example, approximately 40% ± 5%). By setting it as such a space factor, it becomes possible to make the air permeability of the extension part 62 as an outflow prevention function part lower than the air permeability of the cylindrical part 61 as a filter function part, and substantially. Adjustment is possible to the extent that there is no air permeability.

  Note that the adjustment of the space factor described above can be performed by changing the winding pattern of the metal wire wound in the manufacturing process of the filter 60 between the extending portion 62 and the cylindrical portion 61, or in the manufacturing process. The winding tension applied to the metal wire during winding can be adjusted by changing between the extending portion 62 and the tubular portion 61.

  As will be described above, the extending portion 62 configured so as to have a relatively high space factor and substantially no air permeability, like the gas generator 1A in the present embodiment, has an axial end of the filter 60. By providing the extended portion 62 along the housing, it is possible to reliably prevent combustion gas from flowing into the gap between the axial end of the filter 60 and the housing during operation. Become. Therefore, by adopting this configuration, it is possible to provide a gas generator that can stably control the inflation and deployment of the airbag without damaging the airbag.

  In addition, by adopting the above-described configuration, it is possible to reduce the number of parts for preventing combustion gas outflow, which is one for each of the upper end and the lower end of the combustion chamber in the conventional gas generator, and to reduce the number of parts. Can be reduced, and the assembly work can be facilitated. In addition, since the thickness of the extending portion 62 of the filter 60 can be formed thinner than the thickness of the cylindrical portion 61 of the filter 60, the axial shape of the gas generator does not increase in size. . Therefore, a high-performance gas generator can be manufactured at a low cost with a simple configuration.

  As described above, by using the gas generator 1A according to the present embodiment and the gas generator filter 60 used therefor, the outflow of combustion gas from the gap between the filter 60 and the housing can be more reliably prevented. It is possible to provide a gas generator having a simple configuration that can be used and the filter 60 can be used more efficiently, and a filter for the gas generator used in the gas generator.

  FIG. 2 is a schematic cross-sectional view of a gas generator according to a modification of the present embodiment. In addition, about the part similar to 1 A of gas generators in the above-mentioned this Embodiment, the same code | symbol is attached | subjected in a figure, and the description is not repeated here.

  As shown in FIG. 2, the gas generator 1 </ b> B according to this modification is different from the gas generator 1 </ b> A according to the present embodiment described above in the configuration of the filter 60. The filter 60 of the gas generator 1 </ b> B according to this modification includes a tubular portion 61 that surrounds the combustion chamber 50 in the radial direction of the housing, and an extension extending radially inward along the bottom plate portion 21 of the initiator shell 20. Further, the cylindrical portion 61 has a spacer portion 61 a extending from the axial end on the side in contact with the extending portion 62 toward the radially inner side. The spacer part 61 a is a part of the cylindrical part 61, and the space factor in the spacer part 61 a is the same as that of the cylindrical part 61.

  The spacer portion 61 a functions as a filter function portion together with the cylindrical portion 61, and also functions as a portion that adjusts the volume of the combustion chamber 50. That is, by adjusting the size of the spacer portion 61a, the volume of the combustion chamber 50 formed inside the filter 60 can be easily changed without changing the size of the housing. Therefore, by adopting a configuration like the gas generator 1B according to this modification, gas generators having various output characteristics are individually manufactured only by changing the size and shape of the spacer portion 61a of the filter 60. This makes it possible to make design changes and the like more easily.

(Embodiment 2)
FIG. 3 is a schematic cross-sectional view of a gas generator according to Embodiment 2 of the present invention. In addition, the same code | symbol is attached | subjected in the figure about the part similar to 1 A of gas generators in above-mentioned Embodiment 1, and the description is not repeated here.

  In the gas generator 1A according to the first embodiment described above, the extending portion 62 provided in the filter 60 is provided at the end portion in the axial direction of the initiator shell 20 on the bottom plate portion 21 side. As shown in FIG. 3, the gas generator 1 </ b> C in FIG. 3 has an extending portion 63 provided in the filter 60 provided at an axial end portion on the top plate portion 31 side of the closure shell 30. Accordingly, the internal structure of the housing is also slightly different.

  As shown in FIG. 3, in the gas generator 1 </ b> C according to the present embodiment, the filter 60 extends along the cylindrical portion 61 that surrounds the combustion chamber 50 in the radial direction of the housing and the top plate portion 31 of the closure shell 30. And an extending portion 63 extending radially inward. The extending portion 63 is provided at the end of the cylindrical portion 61 on the top plate portion 31 side, and has an outer shape that is annular, and its upper surface is pressed against the top plate portion 31 of the closure shell 30. In contact. Here, the extending portion 63 is substantially air-permeable by adjusting its space factor, similarly to the extending portion 62 provided in the filter 60 of the gas generator 1A in the first embodiment. It is configured not to have. Thereby, the extending part 63 does not exhibit a function as a filter, but functions as an outflow prevention function part that exhibits a function as a combustion gas outflow prevention means.

  A cushion material 52 is disposed in a portion of the internal space of the filter 60 on the extending portion 63 side so as to contact the gas generating agent 51 accommodated in the combustion chamber 50. The cushion material 52 is provided for the purpose of preventing the gas generating agent 51 made of a molded body from being pulverized by vibration or the like, and a ceramic fiber molded body, foamed silicon, or the like is preferably used.

  On the other hand, at the end of the combustion chamber 50 on the bottom plate portion 21 side of the initiator shell 20, the outflow prevention for preventing the combustion gas from flowing out from the gap between the tubular portion 61 of the filter 60 and the initiator shell 20. A member 55 is disposed. The outflow prevention member 55 is formed by pressing a metal plate-like member such as stainless steel or steel, and is in contact with the inner peripheral surface of the lower end portion of the tubular portion 61 of the filter 60. And an annular member having a portion that contacts the bottom plate portion 21 of the initiator shell 20 and a portion that contacts the outer peripheral end of the caulking portion 11 a of the holder 11. Here, since the outflow prevention member 55 is formed by bending a metal plate-like member or the like, the outflow prevention member 55 has appropriate elasticity, and the outflow prevention member 55 has an inner peripheral surface of the filter 60. The bottom plate portion 21 of the initiator shell 20 and the outer peripheral end of the caulking portion 11a of the holder 11 are in appropriate pressure contact.

  Even when the configuration is similar to that of the gas generator 1C in the present embodiment, the same effects as those described in the gas generator 1A in the first embodiment can be obtained. That is, the extending portion 63 configured to relatively increase the space factor and substantially not to be air permeable is provided at the axial end portion of the filter 60, and the extending portion 63 is disposed along the housing. By doing so, it becomes possible to reliably prevent the combustion gas from flowing into the gap between the axial end of the filter 60 and the housing during operation, and in the conventional gas generator, the upper and lower ends of the combustion chamber In addition, the number of combustion gas outflow prevention members, which is required one by one, can be reduced to one. Therefore, by using the gas generator 1C according to the present embodiment and the gas generator filter 60 used therefor, it is possible to more reliably prevent the outflow of combustion gas from the gap between the filter 60 and the housing. And it can be set as the gas generator of the simple structure which can utilize the filter 60 more efficiently, and the filter for gas generators used for this.

  The characteristic configurations of the embodiments described above and the modifications thereof can be combined with each other. For example, a pair of extending portions having substantially no air permeability may be provided on both sides of the end portion in the axial direction of the filter, and the above-described embodiment may be applied to the filter of the gas generator according to the above-described second embodiment. It is good also as a structure which provides the spacer part provided in the filter of the gas generator in 1 modification.

  Moreover, in each above-mentioned embodiment and its modification, although demonstrated by exemplifying what was formed in the cylinder shape by winding a metal wire as a filter, it consists of metals, such as stainless steel and steel You may utilize what pressed and pressed the wire and the net | network material. More specifically, the filter can be formed of a press-worked product such as a knit metal mesh, a plain weave wire mesh, or an assembly of clamp-woven metal wires. However, even in that case, it is necessary to adjust so that the space factor of the extended portion functioning as the combustion gas outflow prevention function portion is larger than the space factor of the cylindrical portion functioning as the filter function portion. is there.

  Further, in each of the above-described embodiments and modifications thereof, the case where the extending portion is configured to have an annular shape has been described as an example, but the embodiment is not necessarily limited to such a shape. Alternatively, the extending portion may be formed in a disk shape. Further, the boundary position between the extending portion having a relatively large space factor and the cylindrical portion having a relatively small space factor is not necessarily the position as shown in FIGS. It is not necessary to be changed, and the position can be changed as appropriate.

  As described above, the above-described embodiments and modifications thereof disclosed herein are illustrative in all respects and are not restrictive. 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 a schematic cross section of the gas generator in Embodiment 1 of the present invention. It is a schematic cross section of the gas generator which concerns on the modification of Embodiment 1 of this invention. It is a schematic cross section of the gas generator in Embodiment 2 of the present invention.

Explanation of symbols

  1A to 1C Gas generator, 10 igniter assembly, 11 holder, 11a caulking part, 12 igniter, 12a ignition part, 12b terminal pin, 13 resin molding part, 20 initiator shell, 21 bottom plate part, 22 peripheral wall part, 23 Opening portion, 30 closure shell, 31 top plate portion, 32 peripheral wall portion, 33 gas outlet, 34 sealing member, 40 cup member, 40a top wall portion, 40b side wall portion, 40c flange portion, 41 opening portion, 42 sealing member, 43 Fire transfer chamber, 44 Transfer charge, 50 Combustion chamber, 51 Gas generating agent, 52 Cushion material, 54, 55 Outflow prevention member, 60 Filter, 61 Cylindrical part, 61a Spacer part, 62, 63 Extension part.

Claims (6)

A short cylindrical housing that includes a combustion chamber in which a gas generating agent is housed, and includes a top plate portion and a bottom plate portion that close both ends in the axial direction, and a peripheral wall portion provided with a gas ejection port;
Ignition means attached to the bottom plate so as to face the combustion chamber;
A filter disposed in the housing,
The filter includes at least a cylindrical portion that surrounds the combustion chamber in the radial direction of the housing, an axial end portion that contacts the top plate portion of the filter, and an axial end portion that contacts the bottom plate portion of the filter. An extension part extending along the top plate part or the bottom plate part from either one toward the radially inner side,
A gas generator in which a space factor of the filter in the extending portion is larger than a space factor of the filter in the cylindrical portion.   2. The gas generation according to claim 1, wherein the extending portion is a portion that prevents combustion gas generated by burning the gas generating agent from reaching the gas ejection port without passing through the inside of the filter. vessel.   The gas generator according to claim 1 or 2, wherein the extending portion has substantially no air permeability.   The gas generator according to any one of claims 1 to 3, wherein the filter is formed of a cylindrical member formed by winding a metal wire.   By changing either the winding pattern of the metal wire or the winding tension of the metal wire, there is a difference between the space factor of the tubular portion and the space factor of the extended portion, Item 5. The gas generator according to Item 4. A gas filter for a short cylinder including a hollow cylindrical portion,
Including an extended portion extending radially inward from at least one of the axial ends of the gas generator filter,
The filter for gas generators in which the space factor in the extension part is larger than the space factor in the cylindrical part.

Images