Igniter and gas generator

Abstract

To obtain an igniter and a gas generator which can adjust the elongation of a cup-shaped member during operation while maintaining sealing and insulation, and which suppresses the ignition hindrance to a transfer charge. A disc-type gas generator 100 has a short-size substantially cylindrical case whose one end and the other end are closed, and in a housing space provided inside the case, a holding portion 30, an igniter 40 having a burst cap 43, a cup-shaped member 50, a transfer charge 59, a gas generating agent 61, a lower-side support member 70, an upper-side support member 80, a buffer member 85, a filter 90, and the like are housed as internal constituent members. In order to make the elongation rate of the burst cap 43 during operation of the igniter 40 greater than 0% and less than 10%, the burst cap 43 is formed by molding a thermosetting resin or a thermoplastic resin containing an elongation rate adjusting material into a cup shape.

Description

Technical Field

[0001] This invention relates to an igniter and a gas generator assembled in an occupant protection device for protecting occupants in the event of a collision in a vehicle or the like, and particularly to an igniter and a gas generator assembled in an airbag device equipped in automobiles or the like. Background Technology

[0002] Previously, airbags were widely used as occupant protection devices to protect occupants in vehicles and other similar structures. Airbags are installed to protect occupants from the impact of a collision. When a collision occurs, the airbag inflates and deploys instantly, acting as a buffer to protect the occupant's body.

[0003] The gas generator is assembled in the airbag device. When a collision occurs, the igniter is ignited by the power supply from the control unit. The flame generated in the igniter causes the gas generator to burn and instantly produce a large amount of gas, thereby causing the airbag to inflate and deploy.

[0004] Gas generators come in various structures, but those that are particularly suitable for use in driver-side airbag systems, passenger-side airbag systems, etc., include disc-shaped gas generators with a relatively large outer diameter and a short, roughly cylindrical shape.

[0005] The disc-shaped gas generator has a short, generally cylindrical housing that is closed at both ends along the axis. Multiple gas outlets are provided on the peripheral wall of the housing, and a ignition propellant is contained inside the housing in a manner facing an igniter assembled on the housing. In addition, a gas generating agent is filled inside the housing in a manner surrounding the ignition propellant, and a filter is contained inside the housing in a manner further surrounding the gas generating agent.

[0006] The following patent document 1 discloses the specific structure of the disc-shaped gas generator.

[0007] In particular, in the following patent document 1 Figure 4 The invention discloses a method of arranging a cup-shaped component on the outer peripheral surface of an igniter, and sealing the igniter and the orifice by pressing the cup-shaped component with an O-ring.

[0008] Existing technical documents:

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 10-310023 Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] In the aforementioned cup-shaped component, it is desirable to maintain the aforementioned sealing and insulation properties without hindering the ignition from the igniter to the propellant. This allows the gas generating agent inside the gas generator to burn effectively within a short time, expelling gas into the gas bag. However, in the aforementioned cup-shaped component, when the igniter is operating, it slightly elongates and breaks following the breakage of other cup-shaped components containing the igniter's propellant. The inventors of this application have discovered that if this elongation is significant, it becomes a major obstacle to the ignition from the igniter to the propellant.

[0013] Therefore, the present invention is proposed to solve the above-mentioned problems, and its purpose is to provide an igniter and a gas generator that, while maintaining sealing and insulation, adjusts the elongation of the cup-shaped component during operation, thereby suppressing the obstruction to the transfer of ignition to the propellant compared to the past.

[0014] Methods for solving problems

[0015] (1) The igniter of the present invention comprises: a first cup-shaped component with a bottomed cylindrical shape containing an ignition powder, and having an opening fitted by a plug having a pair of electrode pins connected to a resistive element; a second cup-shaped component with a bottomed cylindrical shape covering the exterior of the first cup-shaped component; and a retaining portion integrally holding the pair of electrode pins, the plug, the first cup-shaped component, and the second cup-shaped component, characterized in that the second cup-shaped component is made of a thermosetting resin or thermoplastic resin containing an elongation-adjusting material for adjusting the elongation after molding to less than 10%.

[0016] (2) In the igniter of (1) above, it is preferable that the second cup-shaped component and the retaining part are integrally formed, and the retaining part is made of the same material as the second cup-shaped component.

[0017] (3) The present invention is a gas generator having an igniter as described in (1) or (2) above.

[0018] The effects of the invention

[0019] According to the present invention, an igniter and a gas generator can be configured to suppress the obstruction to the ignition charge by adjusting the elongation of the cup-shaped component during operation while maintaining sealing and insulation. Attached Figure Description

[0020] Figure 1 This is a schematic cross-sectional view of a disc-shaped gas generator according to an embodiment of the present invention.

[0021] Figure 2 for Figure 1 A top view of the rupture cover of a disc-shaped gas generator.

[0022] Figure 3 For illustrative purposes Figure 1A schematic partial cross-sectional view of the cracking of the rupture cover of a disc-shaped gas generator.

[0023] Figure 4 for Figure 1 A schematic cross-sectional view of a modified example of a disc-shaped gas generator.

[0024] Figure 5 A graph representing the results of Example 1 in the verification experiment.

[0025] Figure 6 A graph representing the results of Example 2 in the verification experiment. Detailed Implementation

[0026] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the embodiments shown below, the present invention is applicable to disc-shaped gas generators suitable for assembly in airbag devices mounted on automobile steering wheels, etc. Furthermore, in the embodiments shown below, the same or common parts are given the same reference numerals in the figures and will not be described again.

[0027] Figure 1 This is a schematic diagram of a disc-shaped gas generator 100 according to an embodiment of the present invention. First, refer to this... Figure 1 The structure of the disc-shaped gas generator 100 in this embodiment will be described.

[0028] like Figure 1 As shown, the disc-shaped gas generator 100 has a short, generally cylindrical housing that is closed at one and the other ends along the axial direction. Within the housing's internal space are housed internal components such as a retainer 30, an igniter 40, a cup-shaped component 50, a propellant 59, a gas generating agent 61, a lower support component 70, an upper support component 80, a cushioning material 85, and a filter 90. Furthermore, a combustion chamber 60, primarily housing the gas generating agent 61 from the aforementioned internal components, is located within the housing's internal space.

[0029] The housing includes a lower side housing 10 and an upper side housing 20. The lower side housing 10 and the upper side housing 20 are each made of stamped parts, for example, formed by stamping rolled metal sheet parts. As the metal sheet parts constituting the lower side housing 10 and the upper side housing 20, metal sheets made of stainless steel, steel, aluminum alloy, stainless steel alloy, etc. are used, and so-called high-tensile steel sheets that will not break or suffer damage even when subjected to tensile stress of 440 [MPa] to 780 [MPa] are used.

[0030] The lower side shell 10 and the upper side shell 20 are each formed into a bottomed, generally cylindrical shape, and are assembled by joining them together with their openings facing each other. The lower side shell 10 has a bottom plate portion 11 and a peripheral wall portion 12, and the upper side shell 20 has a top plate portion 21 and a peripheral wall portion 22.

[0031] The upper end of the peripheral wall portion 12 of the lower side housing 10 is pressed in by inserting it into the lower end of the peripheral wall portion 22 of the upper side housing 20. Furthermore, the peripheral wall portion 12 of the lower side housing 10 and the peripheral wall portion 22 of the upper side housing 20 are joined at or near their abutment, thereby fixing the lower side housing 10 and the upper side housing 20. Here, electron beam welding, laser welding, friction pressing, etc., can be used appropriately for joining the lower side housing 10 and the upper side housing 20.

[0032] Therefore, the portion of the peripheral wall of the housing near the bottom plate 11 is formed by the peripheral wall portion 12 of the lower side housing 10, and the portion of the peripheral wall of the housing near the top plate 21 is formed by the peripheral wall portion 22 of the upper side housing 20. In addition, one end and the other end of the housing in the axial direction are respectively closed by the bottom plate portion 11 of the lower side housing 10 and the top plate portion 21 of the upper side housing 20.

[0033] A protruding cylindrical portion 13 protruding toward the top plate portion 21 is provided at the center of the bottom plate portion 11 of the lower side housing 10, thereby forming a recessed portion 14 at the center of the bottom plate portion 11 of the lower side housing 10. The protruding cylindrical portion 13 is the part for fixing the igniter 40 via the retaining portion 30, and the recessed portion 14 is the part for providing space for the female connector portion 34 in the retaining portion 30.

[0034] The protruding cylindrical portion 13 is formed into a generally cylindrical shape with a base, and at its axial end located on the side of the top plate portion 21, there is an opening 15 with a non-point-symmetric shape (e.g., D-shaped, barrel-shaped, oblong shape, etc.) in a top view. This opening 15 is the part where a pair of terminal pins 42 of the igniter 40 are inserted.

[0035] The igniter 40 is used to generate a flame and has an ignition part 41, a pair of terminal pins 42, and a burst cap 43 (a second cup-shaped component). The ignition part 41 contains an ignition powder that generates a flame by combustion during operation and a resistor for igniting the ignition powder. The pair of terminal pins 42 are connected to the ignition part 41 to ignite the ignition powder. The burst cap 43 is provided for sealing and insulating the igniter 40, such as... Figure 2 As shown, a slit-shaped vulnerable portion 43a and a non-vulnerable portion 43b are provided at the top. Compared with the non-vulnerable portion 43b, the vulnerable portion 43a is more prone to cracking or melting when the igniter 40 is in operation.

[0036] Furthermore, in order to adjust the elongation of the burst cap 43 to be greater than 0% and less than 10% (preferably greater than 0% and less than 5%, more preferably greater than 0% and less than 3%) when the igniter 40 is working, the burst cap 43 is formed by molding a thermosetting resin or thermoplastic resin containing an elongation-adjusting material into a cup shape. In addition, after testing according to the method specified in JIS K7161-2 (2014), the elongation is calculated using the following formula.

[0037] Elongation [%] = (Maximum length of the test piece before fracture - Length of the test piece in its initial state) × 100 / Length of the test piece in its initial state

[0038] Examples of thermosetting resins include phenolic resins, urea resins, melamine resins, unsaturated polyester resins, epoxy resins, and polyimide resins. Examples of thermoplastic resins include polypropylene, polymethyl methacrylate, polystyrene resins, ABS resins, vinyl chloride, nylon 6, nylon 66, polyamide-imide, polyether-imide, polycarbonate, polyacetal, polyphenylene ether, and polyphenylene sulfide. Examples of elongation-regulating materials include cast iron (FCV), die-cast aluminum and other cast iron products, alumina, glass, silicon carbide, silicon nitride and other ceramics. However, any material capable of altering the elongation of a thermosetting or thermoplastic resin can be used.

[0039] The ignition part 41 has a cup-shaped blasting cup (first cup-shaped component) and a plug that closes the opening end of the blasting cup and holds it by inserting a pair of terminal pins 42. A resistor (bridge wire) is installed in such a way as to connect to the front end of the pair of terminal pins 42 inserted into the blasting cup. It also has a structure that fills the blasting cup with igniting powder in such a way as to surround or approach the resistor.

[0040] Here, nickel-chromium alloy wire is typically used as the resistive element, while ZPP (zirconium-potassium perchlorate), ZWPP (zirconium-tungsten-potassium perchlorate), and lead trioctanoate are commonly used as the ignition propellant. Furthermore, the aforementioned blasting cup and plug are generally made of metal or plastic.

[0041] Upon detection of a collision, a specified amount of current flows through terminal pin 42 into the resistive element. The flow of this specified amount of current generates Joule heat within the resistive element, initiating combustion of the ignition charge. The high-temperature flame produced by combustion causes the blasting cup containing the ignition charge to rupture. The time from the current flowing through the resistive element to the activation of the igniter 40 is typically less than 2 ms, in the case where the resistive element utilizes a nichrome wire.

[0042] The igniter 40 is installed on the base plate 11 in a state of insertion from the inside of the lower side housing 10, such that the terminal pin 42 is inserted into the opening 15 provided in the protruding cylindrical portion 13. Specifically, a retaining portion 30 made of resin molding is provided around the inner periphery of the protruding cylindrical portion 13 provided in the base plate 11, and the igniter 40 is fixed to the base plate 11 by being held by the retaining portion 30.

[0043] The retaining part 30 is formed by injection molding (more specifically, insert molding) using a mold. It is formed by attaching an insulating, fluid resin material to the base plate 11 and curing it by means of extending from a part of the inner surface of the base plate 11 to a part of the outer surface via an opening 15 provided in the base plate 11 of the lower side housing 10.

[0044] As the raw material for the retaining part 30 formed by injection molding, resin materials with excellent heat resistance, durability, and corrosion resistance after curing are suitable. In this case, it is not limited to thermosetting resins such as epoxy resins, but thermoplastic resins such as polybutylene terephthalate resin, polyethylene terephthalate resin, polyamide resins (e.g., nylon 6 or nylon 66), polypropylene vulcanizate resin, and polypropylene oxide resin can also be used. When these thermoplastic resins are selected as raw materials, in order to ensure the mechanical strength of the molded retaining part 30, these resin materials preferably contain fillers such as glass fibers. However, if sufficient mechanical strength can be ensured using only thermoplastic resins, it is not necessary to add fillers as described above.

[0045] The retaining part 30 includes an inner covering part 31 that covers a portion of the inner surface of the bottom plate part 11 of the lower side housing 10, an outer covering part 32 that covers a portion of the outer surface of the bottom plate part 11 of the lower side housing 10, and a connecting part 33 located in the opening 15 provided in the bottom plate part 11 of the lower side housing 10 and connected to the inner covering part 31 and the outer covering part 32 respectively.

[0046] In addition, the retaining part 30 is fixed to the base plate 11 on the surface of the inner cover part 31, the outer cover part 32 and the connecting part 33 respectively. Furthermore, the retaining part 30 is fixed to the side and bottom of the portion of the igniter 40 near the lower end of the ignition part 41, and to the surface of the portion of the igniter 40 near the upper end of the terminal pin 42.

[0047] Thus, the opening 15 is completely embedded by the terminal pin 42 and the retaining part 30, ensuring the airtightness of the space inside the housing by ensuring the sealing of this part. In addition, although not shown, since the opening 15 is formed into a non-point-symmetrical shape when viewed from above, by embedding the opening 15 with the connecting part 33, these openings 15 and the connecting part 33 also serve as an anti-rotation mechanism to prevent the retaining part 30 from rotating relative to the base plate part 11.

[0048] A female connector portion 34 is formed on the outer side cover portion 32 of the retaining portion 30 facing outward. This female connector portion 34 is a portion for receiving a male connector (not shown) for connecting the wiring harness of the igniter 40 and the control unit (not shown), and is located in the recess 14 of the bottom plate portion 11 of the lower side housing 10.

[0049] Within the female connector section 34, the portion of the igniter 40 near the lower end of the terminal pin 42 is exposed. A male connector is inserted into the female connector section 34, thereby achieving electrical connection between the core wire of the wiring harness and the terminal pin 42.

[0050] Alternatively, the lower side shell 10, which has an adhesive layer pre-applied at a predetermined position on the surface of the base plate portion 11 covered by the holding portion 30, can also be injection molded as described above. This adhesive layer can be formed by pre-applying adhesive at a predetermined position on the base plate portion 11 and allowing it to cure.

[0051] In this way, since the cured adhesive layer is located between the base plate portion 11 and the retaining portion 30, the retaining portion 30, which is made of resin molding portion, can be more firmly fixed to the base plate portion 11. Therefore, if the adhesive layer is provided in a circumferential ring around the opening 15 provided in the base plate portion 11, a higher sealing performance can be ensured in this part.

[0052] Here, as an adhesive pre-applied to the base plate 11, it is preferable to use an adhesive that contains a resin material with excellent heat resistance, durability, and corrosion resistance after curing. In particular, it is preferable to use an adhesive containing, for example, cyanoacrylate resin or silicone resin as a raw material. In addition to the resin materials mentioned above, adhesives containing 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, polyamide-imide resins, liquid crystal polymers, styrene rubbers, and olefin rubbers as raw materials can also be used as the aforementioned adhesives.

[0053] Furthermore, although this example illustrates a structure in which the igniter 40 can be fixed relative to the lower side housing 10 by injection molding the retaining part 30, which is made of resin molding part, other alternative solutions can also be used to fix the igniter 40 relative to the lower side housing 10.

[0054] A cup-shaped component 50 is assembled on the base plate 11 to cover the protruding cylindrical part 13, the retaining part 30 and the igniter 40.

[0055] The cup-shaped component 50 is provided to cover the retaining part 30 and the igniter 40. The cup-shaped component 50 has a bottomed, generally cylindrical shape with an opening at one end on the side of the base plate 11, and contains a ignition chamber 57 that houses the ignition propellant 59. The cup-shaped component 50 is disposed in the combustion chamber 60 with its ignition chamber 57 facing the blast cap 43 and the ignition part 41. In addition, the cup-shaped component 50 has a flange-like front end 54 on the open end side, which is fixed by being clamped into the base plate 11 and the lower support member 70. When the igniter 40 is activated and the ignition propellant 59 inside the ignition chamber is ignited, the cup-shaped component 50 may rupture, deform, or melt due to the increase in pressure in its internal space or the conduction of the generated heat.

[0056] The cup-shaped component 50 is preferably made of metals such as stainless steel, iron, aluminum, aluminum alloys, stainless steel, and stainless steel alloys, or of resins such as thermosetting resins (e.g., epoxy resin), thermoplastic resins (e.g., polybutylene terephthalate resin, polyethylene terephthalate resin, polyamide resin (e.g., nylon 6 or nylon 66), polypropylene vulcanizate resin, and polypropylene oxide resin). Aluminum alloys or ferrous metals such as stainless steel and iron, which have higher mechanical strength than aluminum, are particularly preferred.

[0057] Furthermore, the method of fixing the cup-shaped component 50 is not limited to the method of fixing the lower support component 70 described above; other methods of fixing may also be used.

[0058] The ignition charge 59, filled in the ignition chamber, is ignited by the flame generated by the igniter 40, producing hot particles through combustion. As the ignition charge 59, it must be able to reliably initiate the combustion of the gas generator 61. Generally, compositions composed of metal powders / oxidants, such as B / KNO3, B / NaNO3, and Sr(NO3)2, or compositions composed of titanium hydride / potassium perchlorate, or compositions composed of B / 5-aminotetrazole / potassium nitrate / molybdenum trioxide, etc., can be used.

[0059] The ignition source 59 can be in powder form or formed into a predetermined shape by an adhesive. The shape of the ignition source 59 formed by the adhesive can be various, such as granular, cylindrical, flake, spherical, single-hole cylindrical, multi-hole cylindrical, or flat.

[0060] Within the space inside the housing, in the space surrounding the portion where the cup-shaped member 50 is disposed, a combustion chamber 60 containing the gas generating agent 61 is disposed. Specifically, as described above, the cup-shaped member 50 is protrudingly disposed within the combustion chamber 60 formed inside the housing, and the space provided on the outer surface of the top wall portion facing the cup-shaped member 50 and the space provided on the outer surface of the side wall portion constitute the combustion chamber 60. Thus, the gas generating agent 61 is disposed adjacent to the outer surface of the cup-shaped member 50.

[0061] Furthermore, a filter 90 is arranged along the inner circumference of the housing in the space surrounding the combustion chamber 60 containing the gas generating agent 61 radially. The filter 90 has a cylindrical shape, and its central axis is substantially aligned with the axial direction of the housing.

[0062] The gas generator 61 is a reagent that generates gas by ignition and combustion of thermal particles produced by the operation of the igniter 40. As the gas generator 61, a non-azide gas generator is preferred, and the gas generator 61 is usually formed into a molded body containing fuel, oxidant and additives.

[0063] As a fuel, triazole derivatives, tetraazole derivatives, guanidine derivatives, azodicarbonamide derivatives, hydrazine derivatives, or combinations thereof can be used. Specifically, nitroguanidine, guanidine nitrate, cyanoguanidine, 5-aminotetrazole, etc., are preferred, for example.

[0064] As oxidizing agents, alkaline metal hydroxides such as basic copper nitrate or 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 ammonium can be used. As nitrates, sodium nitrate and potassium nitrate are preferred, for example.

[0065] Examples of additives include binders, slag-forming agents, and combustion regulators. For binders, preferred choices include organic binders such as polyvinyl alcohol, metal salts of carboxymethyl cellulose, and stearates, and inorganic binders such as synthetic hydrotalcite and acid clay. Additionally, preferred 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, or inorganic binders such as molybdenum disulfide, talc, bentonite, diatomaceous earth, kaolin, and alumina. For slag-forming agents, preferred choices include silicon nitride, silica, and acid clay. For combustion regulators, preferred choices include metal oxides, ferrosilicon, activated carbon, and graphite.

[0066] The gas generator 61 can be molded into various shapes, including granular, micro-pellet, cylindrical, and disc-shaped forms. Additionally, cylindrical forms can also be perforated (e.g., single-hole or multi-hole cylinder shapes) with through-holes inside. These shapes are preferably selected appropriately based on the specifications of the gasbag assembly of the disc-shaped gas generator 100, with the optimal shape corresponding to the specifications being preferred, such as a shape that reflects the change in gas generation rate over time during combustion of the gas generator 61. Furthermore, in addition to the shape of the gas generator 61, the size and filling amount of the molded form are preferably selected appropriately, taking into account the linear combustion rate and pressure index of the gas generator 61.

[0067] Filter 90 can be, for example, a filter made by winding and sintering metal wires such as stainless steel or steel, or a filter made by pressing and compacting a mesh woven with metal wires. As a mesh material, specifically, it can be a wire mesh woven from knitted fabric or a wire mesh made of plain weave fabric, or an assembly of metal wires made of curled fabric, etc.

[0068] Alternatively, a filter with a perforated metal plate wound around it can be used as filter 90. In this case, the perforated metal plate can be, for example, a steel mesh formed by pushing open the metal plate with serrated cuts and processing it into a mesh shape, or a hook metal plate that is flattened by perforating the metal plate and flattening the burrs generated around the holes. In this case, the size and shape of the formed holes can be changed as needed, and different sizes and shapes of holes can be contained in the same metal plate. In addition, steel plates (mild steel) or stainless steel plates are preferred as metal plates, and non-ferrous metal plates such as aluminum, copper, titanium, nickel or their alloys can also be used.

[0069] When the gas generated in the combustion chamber 60 passes through the filter 90, the filter 90 functions as a cooling mechanism to cool the gas by removing the high temperature of the gas, and also as a removal mechanism to remove residues (slag) contained in the gas. Therefore, in order to adequately cool the gas and prevent the release of residues to the outside, it is necessary to ensure that the gas generated in the combustion chamber 60 passes through the filter 90. In addition, the filter 90 is disposed separately from the peripheral walls 12 and 22, such that a gap 28 of a predetermined size is formed between the peripheral wall 12 of the lower side housing 10 and the peripheral wall 22 of the upper side housing 20, which constitute the peripheral wall of the housing.

[0070] A plurality of gas outlets 23 are provided on the peripheral wall 22 of the upper side housing 20 facing the filter 90. These plurality of gas outlets 23 are used to exhaust the gas passing through the filter 90 to the outside of the housing.

[0071] Furthermore, a metal sealing strip 24, serving as a sealing component, is affixed to the inner circumferential surface of the peripheral wall portion 22 of the upper side housing 20 to seal the aforementioned plurality of gas outlets 23. This sealing strip 24 can preferably be made of aluminum foil or similar material coated on one side with an adhesive component, and its sealing strip 24 ensures the airtightness of the combustion chamber 60.

[0072] A lower support member 70 is disposed near the end of the combustion chamber 60 on the side of the bottom plate portion 11. The lower support member 70 has an annular shape and is disposed substantially close to the filter 90 and the bottom plate portion 11 in order to cover the junction of the filter 90 and the bottom plate portion 11. Thus, the lower support member 70 is located between the bottom plate portion 11 and the gas generating agent 61 near the aforementioned end of the combustion chamber 60.

[0073] The lower support member 70 has an annular plate-shaped base 71 that is close to the inner bottom surface of the base plate 11, an abutting portion 72 that abuts against the inner peripheral surface of the base plate 11 near the filter 90, and a cylindrical erecting portion 73 that is erected vertically from the base 71 toward the top plate 21. The abutting portion 72 extends from the outer edge of the base 71, and the erecting portion 73 extends from the inner edge of the base 71. The erecting portion 73 covers the outer peripheral surface of the protruding cylindrical portion 13 of the lower side housing 10 and the outer peripheral surface of the inner cover portion 31 of the retaining portion 30.

[0074] The lower support member 70 is used to fix the filter 90 to the housing, and also functions as an outflow prevention mechanism to prevent gas generated in the combustion chamber 60 during operation from flowing out through the gap between the lower end of the filter 90 and the base plate 11 without passing through the interior of the filter 90. Therefore, the lower support member 70 is formed, for example, by stamping a metal plate, and is preferably made of steel plate such as ordinary steel or special steel (e.g., cold-rolled steel plate or stainless steel plate).

[0075] An upper support member 80 is disposed at the end of the combustion chamber 60 located on the side of the top plate portion 21. The upper support member 80 has a generally disc-shaped shape and is disposed close to the filter 90 and the top plate portion 21 to cover the junction of the filter 90 and the top plate portion 21. Thus, the upper support member 80 is located between the top plate portion 21 and the gas generating agent 61 near the aforementioned end of the combustion chamber 60.

[0076] The upper support member 80 has a base 81 that abuts against the top plate portion 21 and an abutment portion 82 that is erected vertically from the periphery of the base 81. The abutment portion 82 abuts against the inner circumferential surface of the axial end located on the top plate portion 21 side of the filter 90.

[0077] The upper support member 80 is used to fix the filter 90 to the housing, and also functions as an outflow prevention mechanism to prevent gas generated in the combustion chamber 60 during operation from flowing out through the gap between the lower end of the filter 90 and the top plate portion 21 without passing through the interior of the filter 90. Therefore, the upper support member 80 is formed, for example, by stamping a metal plate, and is preferably made of steel plate such as ordinary steel or special steel (e.g., cold-rolled steel plate or stainless steel plate).

[0078] Inside the upper support member 80, a disc-shaped buffer material 85 is disposed in contact with the gas generating agent 61 contained in the combustion chamber 60. Thus, the portion of the buffer material 85 on the top plate portion 21 side of the combustion chamber 60 is located between the top plate portion 21 and the gas generating agent 61, pressing the gas generating agent 61 toward the bottom plate portion 11.

[0079] The cushioning material 85 is provided to prevent the gas generator 61, which is composed of a molded body, from being crushed due to vibration or the like. It is preferably composed of a molded body of ceramic fiber or a component made of rock wool, foamed resin (such as foamed silicone, foamed polypropylene, foamed polyethylene, foamed polyurethane, etc.), or rubber such as chloroprene and EPDM.

[0080] Next, refer to Figure 1 The assembly procedure for the disc-shaped gas generator 100 of this embodiment will be explained.

[0081] First, the igniter 40 is fixed in the lower side housing 10 by injection molding a retaining part 30 made of resin molding part. Then, it is fixed by pressing the side wall of the cup-shaped member 50, which contains the propellant 59, into the retaining part 30 of the lower side housing 10.

[0082] Next, gas generator 61 is filled inside the filter 90, and the upper support member 80, which contains cushioning material 85, is inserted into the upper part of the filter 90. Then, the upper side housing 20, which has the gas outlet 23 sealed by the sealing strip 24, is covered relative to the lower side housing 10, and the lower side housing 10 and the upper side housing 20 are welded together. This completes the process. Figure 1 Assembly of the gas generator 100 with the structure shown.

[0083] In this embodiment of the disc-shaped gas generator 100, since no opening is provided on the cup-shaped member 50, the process of filling the ignition chamber 57 provided inside the cup-shaped member 50 with the ignition propellant 59 can be performed very easily. This is because, when the disc-shaped gas generator 100 is operating, the cup-shaped member 50 itself is made of a fragile component with low mechanical strength, which can cause a portion of the cup-shaped member to crack, deform, or melt. That is, the operation of closing the opening provided on the cup-shaped member for filling the ignition propellant 59, which is required when using a cup-shaped member with an opening, is not necessary. For example, aluminum strips or sealing plates are not required, thus greatly simplifying the manufacturing process.

[0084] Figure 3 This is a schematic cross-sectional view used to illustrate the operation of the disc gas generator in this embodiment. Next, refer to this... Figure 3 and the above Figure 1 The operation of the disc gas generator 100 in this embodiment will be explained. Additionally, Figure 3 This is a schematic cross-sectional view. For ease of explanation, only a portion of the components surrounding the igniter 40 are shown; other components are omitted.

[0085] Reference Figure 1In the event of a collision involving a vehicle equipped with a disc-shaped gas generator 100, a collision is detected by a collision detection mechanism separately installed on the vehicle. Based on this, the igniter 40 is activated by energizing a control unit separately installed on the vehicle. The ignition propellant 59 housed in the space S1, which serves as the ignition chamber, is ignited by the flame generated by the igniter 40 and begins to burn.

[0086] At this moment, immediately after the igniter 40 is activated, the ignition propellant in the ignition section 41 burns rapidly, causing the rupture cup of the ignition section 41 to rupture, the rupture cap 43 to crack, and the thrust generated by the rapid combustion of the ignition propellant propagates to the ignition propellant 59 filled in the ignition chamber 57. Here, using... Figure 3 Specifically, describe the cracking of the explosion cover 43.

[0087] When the igniter 40 is working, firstly, from Figure 1 The initial state change is Figure 3 The state shown in (a). Specifically, the top of the burst cap 43 expands, the non-fragile portion 43b bulges, and the fragile portion 43a becomes elongated. Then, as shown in (a). Figure 3 As shown in (b), the vulnerable part 43a is damaged and becomes several pieces. That is, the top of the blast cap 43 is cracked.

[0088] Next, the thrust reaches the interior of the cup-shaped component 50, causing it to crack, deform, or melt within the cup-shaped component 50, which is composed of relatively fragile parts. This cracking, deformation, or melting of the cup-shaped component 50 occurs later than the ignition of the propellant 59 caused by the hot particles generated by the combustion of the igniter. Here, the propellant 59 in the cup-shaped component 50 is dispersed within the cup-shaped component 50 due to the thrust generated by the combustion of the igniter, becoming a dispersed state.

[0089] Therefore, within a shorter time, the propellant 59, which is farther from the igniter 40, is also ignited by the hot particles and begins to burn. As a result, the pressure and temperature inside the cup-shaped component 50 increase significantly. Consequently, the cup-shaped component 50 cracks, deforms, or melts within a shorter time, and a large number of hot particles generated by the combustion of the propellant 59 flow into the combustion chamber 60 prematurely.

[0090] In particular, Figure 1In this design, the cup-shaped component 50 is made of iron or stainless steel, which has higher strength than aluminum. Therefore, during the initial stage of combustion of the propellant 59, the cup-shaped component 50 will not crack, deform, or melt. At this time, the internal pressure of the cup-shaped component 50 rises until a predetermined time is reached during which the cup-shaped component 50 cracks, deforms, or melts. Moreover, when the internal pressure reaches a certain level, the cup-shaped component 50 cracks, deforms, or melts. Therefore, by using a ferrous metal material with high mechanical strength, such as iron or stainless steel, the mechanical strength of the cup-shaped component 50 is improved, thereby sufficiently promoting the combustion of the propellant 59 when the cup-shaped component 50 cracks, and enabling the cup-shaped component 50 to crack under conditions that promote the combustion of the gas generator 61. This improvement in the mechanical strength of the cup-shaped component 50 can be achieved even when using a metal with low strength, such as aluminum, by increasing its thickness. The thickness is preferably 0.4 mm to 1.5 mm, more preferably 0.6 mm to 1.2 mm.

[0091] In this way, a large number of hot particles flow into the combustion chamber 60, and the gas generating agent 61 contained in the combustion chamber 60 is ignited and burned, producing a large amount of gas. The gas generated in the combustion chamber 60 passes through the interior of the filter 90, where it is cooled by the heat removed by the filter 90, and the slag contained in the gas is removed by the filter 90 and flows into the gap 28.

[0092] As the pressure inside the casing rises due to the combustion of the gas generator 61, the sealing strip 24 that closes the gas outlet 23 on the upper side casing 20 cracks, and gas is ejected out of the casing through the gas outlet 23. The ejected gas is introduced into the interior of the airbag adjacent to the disc-shaped gas generator 100, causing the airbag to inflate and deploy.

[0093] As described above, according to the embodiments of the present invention, while maintaining sealing and insulation in the initial state, the smooth breaking of the top of the rupture cap 43 after operation allows for smooth ignition to the propellant 59, thus enabling earlier initiation of combustion of the gas generator 61. As a result, the time from the moment the igniter 40 operates to the moment gas begins to be ejected externally via the gas outlet 23 can be shortened compared to the past. Furthermore, even when the time from the moment the igniter 40 operates to the moment gas begins to be ejected externally via the gas outlet 23 is set to be the same as in the past, by changing the material of the rupture cap 43 of the present invention, the amount of propellant 59 can be reduced by a certain amount compared to the past. This reduces costs.

[0094] Furthermore, by making the vulnerable part 43a into a slit-shaped groove, the amount of resin used can be reduced, thus reducing costs compared to the case where the vulnerable part 43a is not formed.

[0095] Hereinafter, variations of embodiments of the present invention will be described. Unless otherwise specified, parts with the same function will be given the same name, and the following two digits will be given the same symbol. In addition, the description of parts that are the same as those in the above embodiments may sometimes be omitted.

[0096] For example, such as Figure 4 As shown, the gas generator 200 can also be a gas generator 140 that integrates the rupture cap and the retaining part. According to this modification, not only can the same effects as the above-described embodiment be obtained, but the sealing performance can be further improved and the number of parts can be reduced. In addition, since there is no step of installing the rupture cap, the cost can be reduced accordingly.

[0097] Similar to the disc gas generator 100 of this embodiment, the igniter in the embodiments and variations of the present invention can also be applied to disc gas generators equipped with two igniters, referred to as dual inflators. Furthermore, it can also be applied to the igniter of a so-called cylindrical gas generator having an elongated cylindrical shape, or to the igniter of a small gas generator included in a seatbelt pretensioner.

[0098] In addition, the blast cap 43 is not limited to Figure 1 As shown. For example, the slits constituting the vulnerable part 43a can be arranged radially, or they can be composed of several slits. For example, the vulnerable part can also be provided with slits in a cross or asterisk shape when viewed from above. In addition, the top of the blast cap 43 can also be composed of a flat surface where the vulnerable part 43a is not formed.

[0099] Furthermore, the shape of the convex and concave portion 43a is not limited to the shape described above and can be any shape. For example, a portion of the non-fragile portion 43b may be made to bulge to one side to form the fragile portion 43a, or the entire fragile portion 43a may be bent in a way that creates a concave portion. Alternatively, multiple protrusions or concave portions may be provided in the fragile portion 43a in a dotted or rowed pattern.

[0100] Furthermore, in the above-described embodiments and variations of the present invention, a case in which a protruding cylindrical portion is provided on the lower side housing is illustrated, but of course, the present invention can also be applied to a gas generator with a structure that does not have such a protruding cylindrical portion.

[0101] Furthermore, the characteristic structures shown in the above-described embodiments and variations of the present invention can of course be combined with each other within the scope permitted by reference to the spirit of the present invention.

[0102] In summary, the embodiments and variations disclosed herein are illustrative in all respects and are not restrictive. The scope of the present invention is defined by the scope of the claims and includes all modifications within the meaning and scope equivalent to the description in the claims.

[0103] (Verification Experiment)

[0104] Next, disc-shaped gas generators with the same structure as the disc-shaped gas generators 100 and 200 described above (hereinafter referred to as the gas generator of Example 1 and the gas generator of Example 2, respectively) were fabricated. By changing the material of the rupture cap and integrating the rupture cap and the retaining part, verification tests were conducted to observe changes in a 60L chamber. The 60L chamber test here refers to a test in which the disc-shaped gas generators with the same structure as the disc-shaped gas generators 100 and 200 were conditioned at -40℃±2℃ for at least 4 hours, placed in a 60L sealed chamber, and operated, with the pressure rise measured over time. In addition, in this verification test, the gas pressure was measured over time from the moment the igniter started operating until 100ms. Furthermore, the number of moles of gas generated by the gas generating agent in each disc-shaped gas generator was 2 mol, and the amount of propellant filled into the cup-shaped component was 1.2g. Furthermore, in this verification test, the burst cap of the gas generator in Example 1 was made of a material containing 30% by weight of glass fiber in nylon 66, and the integrated material of the burst cap and retaining part of the gas generator in Example 2 was also made of a material containing 30% by weight of glass fiber in nylon 66. Additionally, the burst cap of the existing product gas generator in Example 1 (which has the same structure as the gas generator in Example 1 except for the material of the burst cap) was made of nylon 66, and the integrated material of the burst cap and retaining part of the existing product in Example 2 (which has the same structure as the gas generator in Example 2 except for the material of the integrated material of the burst cap and retaining part) was also made of nylon 66. Furthermore, the elongation of the nylon 66 used in the existing product of the burst cap is 10%. Moreover, the elongation of the material containing 30% by weight of glass fiber in nylon 66 used in the burst caps (material variations) of Examples 1 and 2 of the present invention is 3%.

[0105] (Results of Example 1)

[0106] Figure 5 The results of Example 1 are shown. Here, HT was tested at 90°C, and RT was tested at room temperature. Additionally, Figure 5 The "SQ cap" in this context is an abbreviation for burst cap. The same applies in Example 2. Additionally, from... Figure 5 As can be seen from the chart, for the gas generator of Example 1, the time t1 from the moment the igniter starts to work to the moment the gas pressure begins to rise is faster than that of the gas generator of the existing product.

[0107] (Results of Example 2)

[0108] Figure 6This represents the results of Example 2. From Figure 6 As can be seen from the chart, for the gas generator of Example 2, the time t1 from the moment the igniter starts to work to the moment the gas pressure begins to rise is faster than that of the gas generator of the existing product.

[0109] Based on the results of Examples 1 and 2, it is evident that when the burst cap of the present invention is used in the gas generator of an igniter, by making the elongation of the material constituting the burst cap lower than that of existing products, the time t1 from the moment the igniter begins to operate until the gas pressure begins to rise can be shortened. That is, it is evident that the output performance of the gas generator using the burst cap of the present invention in an igniter is better than that of existing products.

[0110] Explanation of reference numerals in the attached figures

[0111] 10, 110 lower side shell

[0112] 11, 111 Base Plate

[0113] 12, 112 circumferential wall sections

[0114] 13, 113 Protruding cylindrical portion

[0115] 14, 114 Recesses

[0116] 15, 115 openings

[0117] 20, 120 Upper side shell

[0118] 21, 121 Top plate section

[0119] 22, 122 circumferential wall portion

[0120] 23, 123 Gas ejection outlets

[0121] 24, 124 sealing tape

[0122] 28, 128 gap

[0123] 30, 130 holding section

[0124] 31, 131 Inner Cover Section

[0125] 32, 132 Outer Covering

[0126] 33, 133 Connecting parts

[0127] 34, 134 Female connector section

[0128] 40 and 140 igniters

[0129] 41, 141 Ignition Section

[0130] 42, 142 terminal pins

[0131] 43, 143 Explosive Cap

[0132] Vulnerable parts 43a and 143a

[0133] 43b, 143b Non-vulnerable parts

[0134] 50, 150 cup-shaped parts

[0135] 54, 154 Front end

[0136] 57, 157 Fire Transfer Room

[0137] 59, 159 ignition source

[0138] 60, 160 Combustion Chamber

[0139] 61, 161 gas generator

[0140] 70, 170 Lower support components

[0141] 71, 171 base

[0142] 72, 172 Contact part

[0143] 73, 173 Establishment Department

[0144] 80, 180 Upper support components

[0145] 81, 181 base

[0146] 82, 182 Contact part

[0147] 85, 185 cushioning material

[0148] 90, 190 filters

[0149] 100, 200 gas generators

[0150] S1 and S2 spaces

Claims

1. An igniter comprising: a first cup-shaped member which is a bottomed cylinder containing an ignition powder and which is fitted to an opening portion by a plug having a pair of electrode pins to which a resistance body is attached; a second cup-shaped member which is a bottomed cylinder covering the outside of the first cup-shaped member; and a holding portion which integrally holds the pair of electrode pins, the plug, the first cup-shaped member, and the second cup-shaped member, wherein the second cup-shaped member is composed of a thermosetting resin or a thermoplastic resin containing an elongation adjusting material for adjusting the elongation after molding to less than 10%.

2. The igniter according to claim 1, wherein the second cup-shaped member and the holding portion are integrally molded, and the second cup-shaped member is composed of the same material as the holding portion.

3. A gas generator having the igniter according to claim 1 or 2. ​ characterized in that ​ ​ ​ ​ ​

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