Gas generator

Abstract

[Problem] To provide a gas generator capable of easily performing leak inspection. [Solution] A disk-type gas generator 100 includes: a housing having therein a combustion chamber 60 in which a gas generating agent 61 for generating gas through combustion and argon gas for leak inspection are housed; and an igniter 40 for igniting and burning the gas generating agent 61. Since the argon gas for leak inspection is housed in the combustion chamber 60, the leak test of the disk type gas generator 100 can be easily performed.

Description

Gas generator

[0001] The present invention relates to a gas generator incorporated in an occupant protection device for protecting an occupant in the event of a vehicle collision, and more particularly to a gas generator incorporated in an airbag device mounted on an automobile or the like.

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

[0003] Gas generators have a variety of structures, but a gas generator that is particularly suitable for use in a driver's side airbag device, a passenger's side airbag device, etc. is a short, approximately cylindrical disk-type gas generator with a relatively large outer diameter.

[0004] A disk-type gas generator has a short, approximately cylindrical housing with both axial ends closed, a plurality of gas outlets provided in the peripheral wall of the housing, a transfer charge contained inside the housing so as to face an igniter assembled to the housing, a gas generating agent filled inside the housing so as to surround the transfer charge, and a filter contained inside the housing so as to further surround the gas generating agent.

[0005] For example, Patent Document 1 discloses a gas generator in which a housing having a gas outlet is separated into a first chamber and a second chamber by a partition, and each of the first chamber and the second chamber is filled with a gas source.

[0006] JP 2018-012418 A

[0007] In the gas generator of Patent Document 1, pressurized gas may be used as the gas source, but the pressurized gas is not a gas for leak testing, which makes it difficult to perform leak testing.

[0008] The present invention has been made in view of the above circumstances, and has an object to provide a gas generator that allows leak testing to be easily carried out.

[0009] (1) A gas generator according to the present invention is characterized by comprising a housing having a combustion chamber therein that contains a gas generating agent that generates gas by combustion and argon gas for leak testing, and an igniter that ignites and burns the gas generating agent.

[0010] (2) In the gas generator of (1) above, the argon gas is preferably at normal pressure.

[0011] According to the present invention, it is possible to provide a gas generator that allows leak testing to be easily carried out.

[0012] FIG. 2 is a schematic cross-sectional view showing a disk-shaped gas generator according to an embodiment of the present invention. FIG. 3 is a schematic cross-sectional view showing a step of attaching a cup-shaped member to a holding portion, among the steps of assembling the disk-shaped gas generator of FIG. 1. FIG. 4 is a schematic cross-sectional view showing a step of filling a housing with gas generating agent, among the steps of assembling the disk-shaped gas generator of FIG. 1. FIG. 5 is a schematic cross-sectional view showing a step of attaching an upper shell to a lower shell, among the steps of assembling the disk-shaped gas generator of FIG. 1. FIG. 6 is a schematic view showing a step of welding the lower shell and the upper shell together, among the steps of assembling the disk-shaped gas generator of FIG. 1.

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the embodiments shown below, the present invention is applied to a disc-type gas generator that is suitably incorporated into an airbag device mounted on the steering wheel of an automobile, etc. In the embodiments shown below, the same or common parts are designated by the same reference numerals in the drawings, and their description will not be repeated.

[0014] Fig. 1 is a schematic cross-sectional view showing a disk-type gas generator 100 according to an embodiment of the present invention. First, with reference to Fig. 1, the configuration of disk-type gas generator 100 according to the present embodiment will be described.

[0015] 1 , disk-shaped gas generator 100 includes a housing, a holding portion 30, igniter 40, cup-shaped member 50, lower support member 70, upper support member 80, cushion material 85, and filter 90. An accommodating space provided inside the housing accommodates internal components such as a part of holding portion 30, igniter 40, cup-shaped member 50, transfer charge 59, gas generating agent 61, lower support member 70, upper support member 80, cushion material 85, and filter 90. A combustion chamber 60 is located in the accommodating space provided inside the housing and mainly accommodates gas generating agent 61, one of the above-mentioned internal components.

[0016] The housing is a short, generally cylindrical body with one axial end and the other axial end closed. The housing includes a lower shell 10 and an upper shell 20. The lower shell 10 and the upper shell 20 are each formed as a press-molded product, for example, by pressing a rolled metal plate-like member. The metal plate-like members constituting the lower shell 10 and the upper shell 20 are made of metal plates made of, for example, stainless steel, iron steel, aluminum alloy, stainless alloy, etc., and preferably so-called high-tensile steel plates that do not break or otherwise damage even when a tensile stress of 440 MPa or more and 780 MPa or less is applied.

[0017] The lower shell 10 and the upper shell 20 are each formed in a generally cylindrical shape with a bottom, and are joined together with their open surfaces facing each other to form a housing. The lower shell 10 has a bottom plate portion 11 and a peripheral wall portion 12, and the upper shell 20 has a top plate portion 21 and a peripheral wall portion 22.

[0018] The upper end of the peripheral wall 12 of the lower shell 10 is inserted into the lower end of the peripheral wall 22 of the upper shell 20 and press-fitted. Furthermore, the peripheral wall 12 of the lower shell 10 and the peripheral wall 22 of the upper shell 20 are joined at or near their contact point, thereby fixing the lower shell 10 and the upper shell 20 together. Here, electron beam welding, laser welding, friction welding, or the like can be suitably used to join the lower shell 10 and the upper shell 20 together.

[0019] As a result, the portion of the peripheral wall of the housing closer to the bottom plate 11 is formed by the peripheral wall 12 of the lower shell 10, and the portion of the peripheral wall of the housing closer to the top plate 21 is formed by the peripheral wall 22 of the upper shell 20. One end and the other end in the axial direction of the housing are closed by the bottom plate 11 of the lower shell 10 and the top plate 21 of the upper shell 20, respectively.

[0020] The bottom plate portion 11 of the lower shell 10 has a recessed portion 14 and an opening 15. A protruding cylindrical portion 13 that protrudes toward the top plate portion 21 is provided in the center of the bottom plate portion 11 of the lower shell 10, thereby forming a recessed portion 14 in the center of the bottom plate portion 11 of the lower shell 10. The protruding cylindrical portion 13 is a portion where the igniter 40 is fixed via the holding portion 30, and the recessed portion 14 is a portion that provides space for providing the female connector portion 34 in the holding portion 30. The recessed portion 14 is recessed toward the inside of the housing on the outer surface of the housing. Specifically, the recessed portion 14 is recessed toward the top plate portion 21 on the outer surface of the bottom plate portion 11.

[0021] The protruding tube portion 13 is formed in a generally cylindrical shape with a bottom, and an opening 15 having a point-symmetric shape (e.g., D-shaped, barrel-shaped, elliptical, etc.) in a plan view is provided at its axial end portion located on the top plate portion 21 side. The opening 15 penetrates the bottom plate portion 11 in the axial direction. That is, the opening 15 is formed at the bottom of the recessed portion 14, penetrates the bottom plate portion 11 in the direction in which the recessed portion 14 is recessed, and communicates between the inside and outside of the housing. The opening 15 is a portion through which a pair of terminal pins 42 of the igniter 40 are inserted.

[0022] The igniter 40 is for generating a flame and includes an ignition portion 41 and a pair of terminal pins 42. The igniter 40 ignites and burns the gas generating agent 61. The ignition portion 41 is disposed inside the housing and is ignited by the flow of electric current. The ignition portion 41 includes an ignition charge that ignites and burns to generate a flame when activated, and a resistor for igniting the ignition charge. The pair of terminal pins 42 are a pair of terminal pins for passing electric current through the ignition portion 41. The pair of terminal pins 42 are connected to the ignition portion 41 to ignite the ignition charge. The pair of terminal pins 42 extend to the outside of the housing through the opening 15.

[0023] More specifically, the ignition unit 41 comprises a cup-shaped squib cup and a plug that closes the open end of the squib cup and through which a pair of terminal pins 42 are inserted and held; a resistor (bridge wire) is attached so as to connect the tips of the pair of terminal pins 42 inserted into the squib cup; and an ignition charge is loaded into the squib cup so as to surround or be adjacent to the resistor.

[0024] Here, nichrome wire or the like is generally used as the resistor, and ZPP (zirconium potassium perchlorate), ZWPP (zirconium tungsten potassium perchlorate), lead tricinate, etc. are generally used as the ignition charge. The squib cup and plug are generally made of metal or plastic.

[0025] When a collision is detected, a predetermined amount of current flows through the resistor via the terminal pin 42. This current flow generates Joule heat in the resistor, causing the ignition charge to begin burning. The high-temperature flame generated by the combustion ruptures the squib cup containing the ignition charge. The time from when the current flows through the resistor to when the igniter 40 is activated is generally 2 ms or less when nichrome wire is used for the resistor.

[0026] Igniter 40 is attached to bottom plate 11 in a state where it is inserted from the inside of lower shell 10 so that terminal pin 42 passes through opening 15 provided in protruding cylindrical portion 13. Specifically, holding portion 30 made of a resin molded portion is provided around protruding cylindrical portion 13 provided on bottom plate 11, and igniter 40 is fixed to bottom plate 11 by being held by holding portion 30.

[0027] The retaining portion 30 is formed by injection molding (more specifically, insert molding) using a mold, and is formed by adhering an insulating fluid resin material to the bottom plate portion 11 of the lower shell 10 so that it passes through an opening 15 provided in the bottom plate portion 11 and reaches from a portion of the inner surface of the bottom plate portion 11 to a portion of the outer surface, and then solidifying it.

[0028] As the raw material for the retaining portion 30 formed by injection molding, a resin material that exhibits excellent heat resistance, durability, corrosion resistance, and the like after hardening is preferably selected and used. In this case, it is not limited to thermosetting resins such as epoxy resin, but thermoplastic resins such as polybutylene terephthalate resin, polyethylene terephthalate resin, polyamide resin (e.g., nylon 6, nylon 66, etc.), polypropylene sulfide resin, and polypropylene oxide resin can also be used. When such a thermoplastic resin is selected as the raw material, it is preferable to incorporate glass fiber or the like as a filler into the resin material to ensure the mechanical strength of the retaining portion 30 after molding. However, if sufficient mechanical strength can be ensured with the thermoplastic resin alone, it is not necessary to add a filler as described above.

[0029] The retaining portion 30 has an inner covering portion 31 that covers part of the inner surface of the bottom plate portion 11 of the lower shell 10, an outer covering portion 32 that covers part of the outer surface of the bottom plate portion 11 of the lower shell 10, and a connecting portion 33 that is located within the opening 15 provided in the bottom plate portion 11 of the lower shell 10 and is continuous with the inner covering portion 31 and the outer covering portion 32, respectively.

[0030] The retaining portion 30 is fixed to the bottom plate portion 11 at the surfaces of the inner covering portion 31, the outer covering portion 32, and the connecting portion 33 that face the bottom plate portion 11. The retaining portion 30 is also fixed to the side and bottom surfaces of the ignition portion 41 of the igniter 40 near the lower end, and to the surface of the terminal pin 42 of the igniter 40 near the upper end.

[0031] As a result, opening 15 is completely filled with terminal pin 42 and holding portion 30, and the sealing of this portion ensures airtightness of the space inside the housing. Note that, because opening 15 is formed in an asymmetrical shape in a plan view as described above, by filling opening 15 with connecting portion 33, opening 15 and connecting portion 33 also function as an anti-rotation mechanism that prevents holding portion 30 from rotating relative to bottom plate portion 11.

[0032] The outer covering portion 32 of the holding portion 30 is embedded in the recessed portion 14, recessed toward the interior of the housing, and open toward the side opposite the interior of the housing. Specifically, the outer covering portion 32 of the holding portion 30 is recessed toward the top plate portion 21, and open toward the side opposite the top plate portion 21. The holding portion 30 holds the igniter 40 with a pair of terminal pins 42 exposed from the bottom of the outer covering portion 32. The pair of terminal pins 42 protrude from the bottom of the outer covering portion 32.

[0033] A female connector portion 34 is formed on the portion of the outer covering portion 32 of the holding portion 30 facing outward. The female connector portion 34 is a portion for receiving a male connector (not shown) of a harness for connecting the igniter 40 to a control unit (not shown), and is located within a recess 14 provided in the bottom plate portion 11 of the lower shell 10.

[0034] A portion of the terminal pin 42 of the igniter 40 near the lower end is exposed and disposed within the female connector portion 34. A male connector is inserted into the female connector portion 34, thereby establishing electrical continuity between the core wire of the harness and the terminal pin 42.

[0035] The above-described injection molding may also be performed using a lower shell 10 in which an adhesive layer is provided in advance at a predetermined position on the surface of the bottom plate 11 in the portion that will be covered by the holding portion 30. The adhesive layer can be formed by applying adhesive to a predetermined position on the bottom plate 11 in advance and then curing the adhesive.

[0036] In this way, the hardened adhesive layer is positioned between the bottom plate portion 11 and the holding portion 30, so that the holding portion 30, which is made of a resin molded portion, can be more firmly fixed to the bottom plate portion 11. Therefore, if the adhesive layer is provided in a ring shape along the circumferential direction so as to surround the opening 15 provided in the bottom plate portion 11, it is possible to ensure a higher sealing performance in that portion.

[0037] Here, the adhesive to be applied in advance to the bottom plate portion 11 is preferably one that contains as its raw material a resin material that has excellent heat resistance, durability, corrosion resistance, etc. after hardening, and is particularly preferably one that contains as its raw material a cyanoacrylate-based resin or a silicone-based resin. In addition to the above-mentioned resin materials, materials containing raw materials such as phenolic resins, epoxy resins, melamine resins, urea resins, polyester resins, alkyd resins, polyurethane resins, polyimide resins, polyethylene resins, polypropylene resins, polyvinyl chloride resins, polystyrene resins, polyvinyl acetate resins, polytetrafluoroethylene resins, acrylonitrile butadiene styrene resins, acrylonitrile styrene resins, acrylic resins, polyamide resins, polyacetal resins, polycarbonate resins, polyphenylene ether resins, polybutylene terephthalate resins, polyethylene terephthalate resins, polyolefin resins, polyphenylene sulfide resins, polysulfone resins, polyethersulfone resins, polyarylate resins, polyetheretherketone resins, polyamideimide resins, liquid crystal polymers, styrene rubbers, and olefin rubbers can also be used as the above-mentioned adhesives.

[0038] Here, an example of a configuration has been given in which the igniter 40 can be fixed to the lower shell 10 by injection molding the retaining portion 30 made of a resin molded portion, but other alternative means can also be used to fix the igniter 40 to the lower shell 10.

[0039] A cup-shaped member 50 is attached to the bottom plate 11 so as to cover the protruding tube 13, the holder 30, and the igniter 40. The cup-shaped member 50 has a generally cylindrical shape with a bottom that is open at the end on the bottom plate 11 side, and includes a space therein for accommodating a transfer charge 59. The cup-shaped member 50 is positioned so that it protrudes into the combustion chamber 60 that accommodates the gas generating agent 61, with the space provided therein facing the ignition portion 41 of the igniter 40.

[0040] The cup-shaped member 50 has a top wall portion 51, a cylindrical side wall portion 52 extending from the periphery of the top wall portion 51 toward the bottom plate portion 11, and an extension portion 53 extending radially outward from the opening end, which is the end of the side wall portion 52 on the bottom plate portion 11 side.

[0041] The side wall 52 includes a thin portion 52a provided on the top wall 51 side, and a thick portion 52b extending from the thin portion 52a along the axial direction to the opposite side of the top wall 51. The thin portion 52a is thicker than the fragile portion 55 described below but thinner than the thick portion 52b, and has the mechanical strength to rupture (break), deform, or melt in accordance with the rupture (break), deformation, or melting of the fragile portion 55.

[0042] The extension portion 53 is formed to extend along the inner surface of the bottom plate portion 11 of the lower shell 10. Specifically, the extension portion 53 has a curved shape to follow the shape of the inner bottom surface of the bottom plate portion 11 at and near the portion where the protruding tubular portion 13 is provided, and includes a tip portion 54 extending in a flange-like shape at its radially outer portion.

[0043] The tip 54 of the extension 53 is disposed between the bottom plate 11 and the lower support member 70 along the axial direction of the housing, and is thereby sandwiched between the bottom plate 11 and the lower support member 70 along the axial direction of the housing. As a result, the tip 54 of the extension 53 of the cup-shaped member 50 is pressed toward the bottom plate 11 by the lower support member 70, and the cup-shaped member 50 is fixed to the bottom plate 11. This prevents the cup-shaped member 50 from falling off the bottom plate 11 without using crimping or press-fitting to fix the cup-shaped member 50.

[0044] The cup-shaped member 50 has no openings in either the side wall portion 52 or the top wall portion 51, and surrounds an internal space. When the igniter 40 is activated and the transfer charge 59 in the transfer chamber 57 is ignited, the cup-shaped member 50 bursts, deforms, or melts due to an increase in pressure in the internal space and the conduction of the generated heat.

[0045] Suitable materials for the cup-shaped member 50 include metal members such as stainless steel, steel, aluminum, aluminum alloy, stainless steel, stainless steel alloy, etc., and resin members such as thermosetting resins typified by epoxy resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyamide resin (e.g., nylon 6, nylon 66, etc.), polypropylene sulfide resin, polypropylene oxide resin, etc. In particular, aluminum alloys or iron-based metal materials such as stainless steel and steel, which have relatively higher mechanical strength than aluminum, are preferred.

[0046] The method for fixing the cup-shaped member 50 is not limited to the above-described fixing method using the lower support member 70, and other fixing methods may be used.

[0047] At least a portion of the top wall 51 of the cup-shaped member 50 is provided with a weakened portion 55 that is thinner than the side wall 52. The weakened portion 55 is provided by a radially extending slit, and is configured to have lower mechanical strength than the side wall 52 of the cup-shaped member 50. The weakened portion 55 is disposed so as to face the ignition portion 41 of the igniter 40. In addition, the portion of the top wall 51 other than the radially extending weakened portion 55 is provided with a non-weakened portion 56 that is thicker than the weakened portion 55 and has a thickness approximately the same as that of the thick portion 52b.

[0048] As a result, in the space inside the cup-shaped member 50, the weak portion 55 is ruptured (broken), deformed, or melted by the thrust generated by the combustion of the transfer charge 59, and then the thin-walled portion 52a is ruptured (broken), deformed, or melted in accordance with the rupture (rupture), deformation, or melting of the weak portion 55, and the mechanical strength of the weak portion 55 and the thin-walled portion 52a is relatively low. On the other hand, the non-weak portion 56 and the thick-walled portion 52b are formed thicker than the weak portion 55, and are therefore configured to remain even after the transfer charge 59 is burned when the igniter 40 is activated.

[0049] The thicknesses of the fragile portion 55 and thin portion 52a and the non-fragile portion 56 and thick portion 52b are adjusted as appropriate based on the type and filling amount of the transfer charge 59 used, and an example is shown below. For example, when the cup-shaped member is made of iron, stainless steel, or an aluminum alloy, the thicknesses of the fragile portion 55 and thin portion 52a are set to 0.6 mm or less, preferably 0.5 mm or less. On the other hand, when the cup-shaped member is made of iron, stainless steel, or an aluminum alloy, the thicknesses of the non-fragile portion 56 and thick portion 52b are set to 0.6 mm or more and 1.5 mm or less, preferably 0.6 mm or more and 1.2 mm or less, provided that they are greater than the thicknesses of the fragile portion 55 and thin portion 52a.

[0050] The above-described fragile portion 55 may be made up of any number of slits as long as the slits constituting the fragile portion 55 are arranged radially. For example, the slits may be arranged in a cross or asterisk shape in a plan view.

[0051] The transfer charge 59 filled in the transfer chamber 57 is ignited by the flame generated by the activation of the igniter 40, and generates thermal particles as it burns. The transfer charge 59 needs to be capable of reliably starting the combustion of the gas generant 61, and generally, a composition made of a metal powder / oxidizer, such as B / KNO3, B / NaNO3, or Sr(NO3)2, a composition made of titanium hydride / potassium perchlorate, or a composition made of B / 5-aminotetrazole / potassium nitrate / molybdenum trioxide, is used.

[0052] The enhancer charge 59 may be in a powder form, or formed into a predetermined shape with a binder, etc. The shape of the enhancer charge 59 formed with a binder may be, for example, granular, cylindrical, sheet, spherical, single-hole cylinder, multi-hole cylinder, tablet, or the like.

[0053] Within the space within the housing, the space surrounding the portion in which the cup-shaped member 50 is disposed defines a combustion chamber 60 containing gas generating agent 61. Specifically, as described above, the cup-shaped member 50 is disposed so as to protrude into the combustion chamber 60 formed within the housing, and the space provided in the portion facing the outer surface of the top wall portion 51 of the cup-shaped member 50 and the space provided in the portion facing the outer surface of the side wall portion 52 form the combustion chamber 60. As a result, the gas generating agent 61 is disposed adjacent to the outer surface of the cup-shaped member 50.

[0054] A filter 90 is disposed along the inner periphery of the housing in a space that radially surrounds the combustion chamber 60 containing the gas generating agent 61. The filter 90 has a cylindrical shape and is disposed so that its central axis substantially coincides with the axial direction of the housing.

[0055] The gas generating agent 61 is an agent that is ignited by thermal particles generated by the transfer charge 59 when the igniter 40 is activated, and burns to generate gas. A non-azide gas generating agent is preferably used as the gas generating agent 61, and the gas generating agent 61 is generally formed as a molded body containing a fuel, an oxidizer, and an additive.

[0056] The fuel may be, for example, a triazole derivative, a tetrazole derivative, a guanidine derivative, an azodicarbonamide derivative, a hydrazine derivative, or a combination thereof. Specifically, nitroguanidine, guanidine nitrate, cyanoguanidine, 5-aminotetrazole, or the like is preferably used.

[0057] Examples of oxidizing agents that can be used include basic metal nitrates such as basic copper nitrate, basic metal carbonates such as basic copper carbonate, perchlorates such as ammonium perchlorate and potassium perchlorate, and nitrates containing cations selected from alkali metals, alkaline earth metals, transition metals, and ammonia. Suitable nitrates include sodium nitrate and potassium nitrate.

[0058] Examples of additives include binders, slag formers, and combustion modifiers. Suitable binders include organic binders such as polyvinyl alcohol, metal salts of carboxymethyl cellulose, and stearates, as well as inorganic binders such as synthetic hydrotalcite and acid clay. Other suitable binders include polysaccharide derivatives such as hydroxyethyl cellulose, hydroxypropyl methyl cellulose, cellulose acetate, cellulose propionate, cellulose acetate butyrate, nitrocellulose, microcrystalline cellulose, guar gum, polyvinylpyrrolidone, polyacrylamide, and starch, as well as inorganic binders such as molybdenum disulfide, talc, bentonite, diatomaceous earth, kaolin, and alumina. Suitable slag formers include silicon nitride, silica, and acid clay. Suitable combustion modifiers include metal oxides, ferrosilicon, activated carbon, and graphite.

[0059] The shape of the molded body of gas generating agent 61 may be various, including granular, pellet-like, cylindrical, or other particulate shapes, and disk-like shapes. Furthermore, among cylindrical molded bodies, perforated molded bodies having through holes inside the molded body (for example, a single-hole cylindrical shape or a multi-hole cylindrical shape) are also used. These shapes are preferably selected as appropriate depending on the specifications of the airbag device into which disk-type gas generator 100 is incorporated, and it is preferable to select an optimal shape depending on the specifications, such as a shape in which the rate of gas generation changes over time during combustion of gas generating agent 61. Furthermore, in addition to the shape of gas generating agent 61, it is preferable to select the size and filling amount of the molded body as appropriate, taking into consideration the burning rate, pressure exponent, etc. of gas generating agent 61.

[0060] The filter 90 can be made of, for example, metal wire such as stainless steel or steel wound and sintered, or a mesh of woven metal wires pressed together by pressing. Specific examples of mesh materials that can be used include knitted wire mesh, plain woven wire mesh, and an aggregate of crimped metal wires.

[0061] Alternatively, a perforated metal sheet wound around the filter 90 may be used. Examples of perforated metal sheets include expanded metal, which is a metal sheet with staggered cuts and then expanded to form holes and form a mesh, and hook metal, which is a metal sheet with holes drilled and flattened by crushing any burrs that may form around the holes. The size and shape of the holes can be varied as needed, and holes of different sizes and shapes may be included in the same metal sheet. Suitable metal sheets include mild steel and stainless steel, as well as non-ferrous metal sheets such as aluminum, copper, titanium, nickel, and alloys thereof.

[0062] The filter 90 functions as a cooling means for cooling the gas generated in the combustion chamber 60 by removing the high-temperature heat of the gas as the gas passes through the filter 90, and also functions as a removal means for removing residue (slag) and the like contained in the gas. Therefore, in order to sufficiently cool the gas and prevent the residue from being released to the outside, it is necessary to ensure that the gas generated in the combustion chamber 60 passes through the filter 90. The filter 90 is disposed at a distance from the peripheral wall portions 12, 22 of the lower shell 10 and the peripheral wall portion 22 of the upper shell 20 that constitute the peripheral wall portions of the housing so that a gap 28 of a predetermined size is formed between the filter 90 and the peripheral wall portions 12, 22.

[0063] A plurality of gas outlets 23 are provided in the peripheral wall 22 of the upper shell 20 in a portion facing the filter 90. The gas outlets 23 are used to guide the gas that has passed through the filter 90 to the outside of the housing.

[0064] Additionally, a metal sealing tape 24 is attached to the inner peripheral surface of the peripheral wall portion 22 of the upper shell 20 as a sealing member to close the plurality of gas ejection ports 23. This sealing tape 24 can be suitably made of aluminum foil with an adhesive applied to one side, or the like, and the sealing tape 24 ensures that the combustion chamber 60 is airtight.

[0065] A lower support member 70 is disposed near the end of the combustion chamber 60 that is located on the bottom plate 11 side. The lower support member 70 has an annular shape and is disposed substantially between the filter 90 and the bottom plate 11 so as to cover the boundary between the filter 90 and the bottom plate 11. As a result, the lower support member 70 is positioned between the bottom plate 11 and the cushion material 85 near the end of the combustion chamber 60.

[0066] The lower support member 70 has an annular base portion 71 that is fitted to the bottom plate portion 11 so as to fit along the inner bottom surface of the bottom plate portion 11, an abutting portion 72 that abuts against the inner peripheral surface of the filter 90 closer to the bottom plate portion 11, and a tubular upright portion 73 that stands from the base portion 71 toward the top plate portion 21. The abutting portion 72 extends from the outer edge of the base portion 71, and the upright portion 73 extends from the inner edge of the base portion 71. The upright portion 73 covers the outer peripheral surface of the protruding tubular portion 13 of the lower shell 10 and the outer peripheral surface of the inner covering portion 31 of the holding portion 30 via the extension portion 53 of the cup-shaped member 50.

[0067] The lower support member 70 is a member for fixing the filter 90 to the housing, and also functions as an outflow prevention means for preventing gas generated in the combustion chamber 60 from escaping through the gap between the lower end of the filter 90 and the bottom plate portion 11 when the igniter 40 is activated, without passing through the inside of the filter 90. For this reason, the lower support member 70 is formed, for example, by pressing a metal plate-like member, and is preferably made of a member made of steel plate such as ordinary steel or special steel (for example, cold-rolled steel plate or stainless steel plate).

[0068] A circular plate-shaped cushion material 85 is disposed on the upper surface of the base 71 of the lower support member 70 so as to come into contact with the gas generating agent 61 contained in the combustion chamber 60. The cushion material 85 is provided for the purpose of preventing the gas generating agent 61 made of a molded body from being crushed by vibration or the like, and is preferably made of a member such as a ceramic fiber molded body, rock wool, foamed resin (for example, foamed silicone, foamed polypropylene, foamed polyethylene, foamed urethane, etc.), or rubber typified by chloroprene and EPDM.

[0069] Here, the cushion material 85 is positioned between the bottom plate portion 11 and the gas generating agent 61 in the portion of the combustion chamber 60 on the bottom plate portion 11 side. Therefore, the cushion material 85 presses the gas generating agent 61 toward the top plate portion 21 side.

[0070] Furthermore, cushion material 85 is provided at a position spaced a predetermined distance from top wall portion 51 of cup-shaped member 50. Therefore, when igniter 40 is activated, transfer charge 59 is able to reach gas generating agent 61 and transfer flame without being adsorbed to cushion material 85, so gas generating agent 61 can be burned efficiently and the gas output performance of gas generator 100 can be made as desired.

[0071] Furthermore, because the cushion material 85 is provided on the bottom plate 11 side of the combustion chamber 60, a larger amount of gas generating agent 61 can be disposed between the top wall 51 and the top plate 21 of the cup-shaped member 50 than when the cushion material 85 is provided on the top plate 21 side of the combustion chamber 60. As a result, a larger amount of gas can be generated when the igniter 40 is activated. The amount of gas generated is adjusted appropriately based on the amount of gas generating agent 61 disposed between the top wall 51 and the top plate 21 of the cup-shaped member 50, and an example is shown below. For example, the height (distance from the top plate 21 or the upper support member 80) of the charge surface (the uppermost position of the gas generating agent 61) of the gas generating agent 61 disposed on the top wall 51 is preferably 5 mm or more and 20 mm or less.

[0072] An upper support member 80 is disposed at the end of the combustion chamber 60 that is located on the top plate 21 side. The upper support member 80 has a generally disk-like shape and is disposed between the filter 90 and the top plate 21 so as to cover the boundary between the filter 90 and the top plate 21. As a result, the upper support member 80 is positioned near the end of the combustion chamber 60, between the top plate 21 and the gas generating agent 61.

[0073] The upper support member 80 has a base 81 that abuts against the top plate 21, and an abutment portion 82 that stands upright from the periphery of the base 81. The abutment portion 82 abuts against the inner peripheral surface of the axial end portion of the filter 90 that is located on the top plate 21 side.

[0074] The upper support member 80 is a member for fixing the filter 90 to the housing, and also functions as an outflow prevention means for preventing gas generated in the combustion chamber 60 from escaping through the gap between the upper end of the filter 90 and the top plate portion 21 when the igniter 40 is activated, without passing through the inside of the filter 90. For this reason, the upper support member 80 is formed, for example, by pressing a metal plate-like member, and is preferably made of a member made of a steel plate such as ordinary steel or special steel (for example, a cold-rolled steel plate or a stainless steel plate).

[0075] Argon gas for leak testing is stored in the combustion chamber 60. The leak test is a test to determine whether the argon gas stored inside the housing is leaking to the outside of the housing. The argon gas for leak testing may leak to the outside of the housing through a gap between the lower shell 10 and the retaining portion 30, a gap between the retaining portion 30 and the igniter 40, or a gap between the gas outlet 23 and the sealing tape 24. Alternatively, the argon gas for leak testing may be stored in the transfer chamber 57, for example.

[0076] The argon gas used for leak testing is at normal pressure. The argon gas used for leak testing is at normal temperature. The concentration of the argon gas used for testing in the gas inside the housing is 20 mol% or less. Here, as a variant, the argon gas used for leak testing may be at a pressure higher than normal pressure or lower than normal pressure. The argon gas used for leak testing may be at a temperature higher than normal temperature or lower than normal temperature. The concentration of the argon gas used for testing may be higher than 20 mol%. The concentration of the argon gas used for testing may be 5 mol% or more and 10 mol% or less, for example. The argon gas used for testing may be odorized.

[0077] Fig. 2 is a schematic cross-sectional view showing a step of attaching cup-shaped member 50 to holding portion 30, among the steps of assembling disc-type gas generator 100 of Fig. 1. Fig. 3 is a schematic cross-sectional view showing a step of filling gas generating agent 61 into the interior of the housing, among the steps of assembling disc-type gas generator 100 of Fig. 1. Fig. 4 is a schematic cross-sectional view showing a step of attaching upper shell 20 to lower shell 10, among the steps of assembling disc-type gas generator 100 of Fig. 1. Fig. 5 is a schematic view showing a step of welding lower shell 10 and upper shell 20 together, among the steps of assembling disc-type gas generator 100 of Fig. 1. Next, with reference to Figs. 2 to 5, the procedure for assembling disc-type gas generator 100 in this embodiment will be described.

[0078] First, as shown in Fig. 2, the holding portion 30 made of a resin molded portion is injection molded into the recess 14 of the lower shell 10, thereby fixing the igniter 40. Then, the side wall 52 of the cup-shaped member 50, which contains the transfer charge 59, is press-fitted into the holding portion 30 of the lower shell 10 to fix it. Specifically, the cup-shaped member 50 is held by a jig 200, and a jig 201 holding the lower shell 10 is moved toward the cup-shaped member 50, thereby press-fitting the inner covering portion 31 of the holding portion 30 of the lower shell 10 into the side wall 52 of the cup-shaped member 50.

[0079] 3, the lower support member 70 is placed on the tip end 54 of the extension portion 53 of the cup-shaped member 50, and the filter 90 is inserted toward the inner bottom surface of the lower shell 10. Then, a cushion material 85 is placed on the upper surface of the base portion 71 of the lower support member 70, and the gas generating agent 61 is filled inside the filter 90. Specifically, the lower shell 10 is placed on a jig 202, and a predetermined amount of gas generating agent 61 measured by an electronic balance or the like is placed inside the filter 90 using a jig 203.

[0080] Next, the combustion chamber 60 is filled with argon gas for inspection, and the upper support member 80 is inserted into the upper end portion of the filter 90. Note that the upper support member 80 may be inserted into the upper end portion of the filter 90 under an argon gas atmosphere. Thereafter, the upper shell 20, whose gas outlets 23 are closed with sealing tape 24, is placed over the lower shell 10. Specifically, as shown in FIG. 4 , the lower shell 10 is held by a jig 204, and the upper shell 20 is held by a jig 205. Then, the jig 205 is moved toward the lower shell 10 along the inner peripheral wall of the jig 204A, thereby placing the upper shell 20 over the lower shell 10.

[0081] 5 , lower shell 10 and upper shell 20 are then welded together. Specifically, upper shell 20 is fixed by jig 206, and while jig 206 is rotated to rotate disc-shaped gas generator 100, lower shell 10 and upper shell 20 are welded together by YAG (Yttrium Aluminum Garnet) welding machine 207 so as to close the gap between them.

[0082] This completes the assembly of disk-type gas generator 100 having the structure shown in FIG.

[0083] Here, in disk-shaped gas generator 100 of the present embodiment, no opening is provided in cup-shaped member 50, and therefore the step of filling transfer charge 59 into transfer chamber 57 provided inside cup-shaped member 50 can be carried out very easily. This is because cup-shaped member 50 itself is configured from a fragile member with low mechanical strength so that a part of the cup-shaped member will rupture, deform or melt when disk-shaped gas generator 100 is activated. In other words, the work of closing the opening provided in the cup-shaped member in order to fill transfer charge 59, such as with aluminum tape or a closing plate, which was necessary when a cup-shaped member having an opening was used, is no longer necessary, and the manufacturing process can be greatly simplified.

[0084] Fig. 6 is a schematic diagram showing the steps of conducting a leak test on disk-type gas generator 100 of Fig. 1. Next, the procedure for conducting a leak test on disk-type gas generator 100 will be described with reference to Fig. 6.

[0085] 6, the disk-shaped gas generator 100 is placed in a chamber 208, and the chamber 208 is evacuated. Specifically, the leak machine 209 has a vacuum pump (not shown), and the chamber 208 is evacuated by the vacuum pump.

[0086] When argon gas leaks from disk-shaped gas generator 100, leak detector 209 detects the argon gas leaked from disk-shaped gas generator 100. Specifically, when argon gas leaks from disk-shaped gas generator 100, the argon gas enters leak detector 209, causing leak detector 209 to detect the argon gas.

[0087] In this manner, a leak test of the disk-type gas generator 100 can be performed.

[0088] Next, with reference to FIG. 1, the operation of disk-type gas generator 100 in this embodiment will be described.

[0089] When a vehicle equipped with disk-shaped gas generator 100 collides, the collision is detected by collision detection means separately provided in the vehicle, and based on this, a control unit separately provided in the vehicle supplies current to activate igniter 40. Transfer charge 59 accommodated in transfer chamber 57 is ignited by a flame generated by the activation of igniter 40, and begins combustion.

[0090] At this time, immediately after the igniter 40 is activated, the ignition charge loaded in the ignition section 41 burns rapidly, causing the squib cup of the ignition section 41 to burst, and the heat generated by the rapid combustion of the ignition charge is transmitted to the transfer charge 59 filled in the transfer chamber 57.

[0091] When the thrust reaches the top wall 51 of the cup-shaped member 50, the fragile portion 55 of the cup-shaped member 50, which is made of a fragile material, ruptures, deforms, or melts. This rupture, deformation, or melting of the fragile portion 55 of the cup-shaped member 50 occurs later than the ignition of the transfer charge 59 by thermal particles generated by the combustion of the ignition charge. Since the fragile portion 55 is not present in the side wall 52 but is present in the top wall 51, the fragile portion 55 of the top wall 51 ruptures, deforms, or melts first, and the internal pressure increases until the transfer charge 59 ruptures, deforms, or melts. The transfer charge 59 of the cup-shaped member 50 is subjected to the thrust generated by the combustion of the ignition charge and is scattered and dispersed within the cup-shaped member 50. The fragile portion 55 is provided as a slit as described above, and ruptures, deforms, or melts first from the top wall 51 of the cup-shaped member 50, and then splits open toward the thin-walled portion 52a of the side wall 52. The thin portion 52a ruptures (breaks), deforms, or melts in accordance with the rupture (break), deformation, or melting of the fragile portion 55, and continues to split open to the connection with the thick portion 52b. Here, the thick portion 52b does not rupture (break), deform, or melt.

[0092] Therefore, the transfer charge 59 located farther from the igniter 40 is also ignited by the thermal particles in a shorter time and begins to burn, which results in a significant increase in pressure and temperature in the space inside the cup-shaped member 50. As a result, the fragile portion 55 of the cup-shaped member 50 ruptures, deforms, or melts in a shorter time, and a large amount of thermal particles generated by the combustion of the transfer charge 59 flows into the combustion chamber 60 quickly. These thermal particles are not affected by the cushion material 85 provided in the lower shell 10 and come into contact with the gas generating agent 61 without being deactivated.

[0093] In this way, the transfer charge 59 and a large amount of thermal particles generated by the transfer charge 59 flow into the combustion chamber 60, igniting and burning the gas generating agent 61 contained in the combustion chamber 60, generating a large amount of gas. Note that the argon gas in the combustion chamber 60 is an inert gas and does not affect the combustion of the gas generating agent 61. The gas generated in the combustion chamber 60 passes through the inside of the filter 90, and in this process, heat is removed by the filter 90 and the gas is cooled, and slag contained in the gas is removed by the filter 90 and flows into the gap 28.

[0094] Then, as the pressure in the space inside the housing increases due to the combustion of gas generating agent 61, sealing tape 24 that has been closing gas outlet 23 provided in upper shell 20 ruptures, and gas is ejected to the outside of the housing through gas outlet 23. The ejected gas is introduced into the inside of an airbag provided adjacent to disk-shaped gas generator 100, and inflates and deploys the airbag.

[0095] Note that when the cup-shaped member 50 is made of iron or stainless steel, the strength is higher than when the cup-shaped member 50 is made of aluminum, and therefore the cup-shaped member 50 does not rupture, deform, or melt in the initial stage of combustion of the transfer charge 59. At this time, the internal pressure of the cup-shaped member 50 increases until a predetermined time has elapsed at which the fragile portion 55 of the cup-shaped member 50 ruptures, deforms, or melts. Then, once the internal pressure reaches a certain level, the fragile portion 55 and the thin-walled portion 52a of the cup-shaped member 50 rupture, deform, or melt in sequence. Therefore, by using an iron-based metal material with high mechanical strength, such as iron or stainless steel, for the cup-shaped member 50, the mechanical strength can be increased to sufficiently promote the combustion of the transfer charge 59 when the cup-shaped member 50 is split, thereby splitting the cup-shaped member 50. Such an improvement in the mechanical strength of the cup-shaped member 50 can be achieved by increasing the thickness, even when a metal with low strength, such as aluminum, is used. In this case, the thickness is preferably 0.4 mm or more and 1.5 mm or less, and more preferably 0.6 mm or more and 1.2 mm or less.

[0096] As explained above, disk-shaped gas generator 100 in an embodiment of the present invention comprises a housing having combustion chamber 60 therein that contains gas generating agent 61 that generates gas by combustion and argon gas for leak testing, and igniter 40 that ignites and burns gas generating agent 61.

[0097] According to this, since argon gas for leak testing is contained in combustion chamber 60, a leak test of disk-shaped gas generator 100 can be easily carried out.

[0098] In addition, in disk-type gas generator 100 according to the embodiment of the present invention, the argon gas used for inspection is at normal pressure.

[0099] According to this, since there is no need to pressurize the argon gas, the leak test of the disk-shaped gas generator 100 can be performed more easily.

[0100] Although the embodiments of the present invention have been described above, they are merely illustrative examples and do not limit the present invention, and the specific configurations and the like can be appropriately modified in design. Furthermore, the actions and effects described in the embodiments of the invention are merely a list of the most preferable actions and effects resulting from the present invention, and the actions and effects of the present invention are not limited to those described in the embodiments of the present invention.

[0101] In the above-described embodiment, the present invention has been described as being applied to a disk-type gas generator, but is not limited to this. For example, the present invention can also be applied to a so-called cylinder-type gas generator having an elongated cylindrical outer shape.

[0102] REFERENCE SIGNS LIST 10 Lower shell 11 Bottom plate portion 12 Peripheral wall portion 13 Projecting tube portion 14 Recessed portion 15 Opening 20 Upper shell 21 Top plate portion 22 Peripheral wall portion 23 Gas outlet 24 Sealing tape 28 Gap portion 30 Holding portion 31 Inner covering portion 32 Outer covering portion 33 Connecting portion 34 Female connector portion 40 Igniter 41 Igniter portion 42 Terminal pin 50 Cup-shaped member 51 Top wall portion 52 Side wall portion 52a Thin portion 52b Thick portion 53 Extension portion 54 Tip portion 55 Fragile portion 56 Non-fragile portion 57 Transfer chamber 59 Transfer charge 60 Combustion chamber 61 Gas generating agent 70 Lower support member 71 Base portion 72 Contact portion 73 Standing portion 80 Upper support member 81 Base portion 82 Contact portion 85 Cushion material 90 Filter 100 Disk-type gas generator 200, 201, 202, 203, 204, 204A, 205, 206 Jig 207 YAG welding machine 208 Chamber 209 Leak machine

Claims

1. A gas generator comprising: a housing having an internal combustion chamber that contains a gas generating agent that generates gas when burned and argon gas for leak testing; and an igniter that ignites and burns the gas generating agent.

2. The gas generator according to claim 1, wherein the argon gas is at atmospheric pressure.

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