JP7758566B2 - Gas generator - Google Patents

Description

The present invention relates to a gas generator incorporated into an occupant protection device that protects occupants in the event of a vehicle collision, and in particular to a gas generator incorporated into an airbag device installed in an automobile or the like.

Airbag systems, which are occupant protection devices, have become widespread in automobiles and other vehicles to protect passengers. Airbag systems are installed to protect passengers from the impact that occurs during a vehicle collision. When a vehicle crashes, the airbag instantly inflates and deploys, acting as a cushion to support the passenger's body.

The gas generator is incorporated into this airbag device. When a vehicle crashes, the control unit energizes the igniter, igniting the igniter. The flame generated in the igniter burns the gas generating agent, instantly generating a large amount of gas, which inflates and deploys the airbag.

Gas generators come in a variety of structures, but a type that is particularly suitable for use in driver-side airbag systems, passenger-side airbag systems, etc. is the disk-type gas generator, which is a short, roughly cylindrical gas generator with a relatively large outer diameter.

A disk-type gas generator has a short, approximately cylindrical housing with both axial ends closed, multiple gas outlets provided in the peripheral wall of the housing, a transfer charge contained inside the housing facing an igniter attached to the housing, a gas generating agent filled inside the housing surrounding the transfer charge, and a filter contained inside the housing to further surround the gas generating agent.

For example, Patent Document 1 discloses a disk-type gas generator equipped with a cushioning material to prevent the gas generating agent from being crushed by vibrations or the like in the combustion chamber provided within the housing. The cushioning material in Patent Document 1 is positioned so as to face the top surface of the cup body filled with a transfer charge.

Japanese Patent Application Laid-Open No. 2003-312434

In the gas generator of Patent Document 1, if the distance between the cushion material and the top surface of the cup body is relatively short, the transfer charge may be adsorbed to the cushion material when the igniter is activated, causing the transfer charge to be deactivated and reducing the amount of transfer charge that can be transferred to the gas generant, resulting in insufficient gas output performance. Possible solutions to this include ensuring a sufficient distance between the cushion material and the top surface of the cup body, or increasing the size of the cup body to increase the amount of transfer charge. However, if a sufficient distance is maintained between the cushion material and the top surface of the cup body, the size of the gas generator increases. Furthermore, even if a certain amount of distance is maintained between the cushion material and the top surface of the cup body, some transfer charge may still be adsorbed to the cushion material, making it impossible to achieve the desired gas output performance. Furthermore, increasing the size of the cup body to increase the amount of transfer charge increases the total weight of the gas generator.

The present invention was made in consideration of these circumstances, and aims to provide a gas generator that can demonstrate sufficient gas output performance even with a relatively small amount of transfer charge.

(1) A gas generator of the present invention comprises a short cylindrical housing constituted by a cylindrical peripheral wall portion provided with a gas outlet, a top plate portion closing one axial end of the peripheral wall portion, and a bottom plate portion closing the other axial end of the peripheral wall portion, the housing having a combustion chamber therein containing a gas generating agent; an igniter assembled to the bottom plate portion and including an ignition portion containing an ignition charge that ignites when activated; a cup-shaped member consisting of a single cylindrical member with a bottom, the cup-shaped member containing a transfer chamber therein containing a transfer charge and arranged to protrude toward the combustion chamber so that the internal space of the transfer chamber faces the ignition portion; and a cushioning material arranged on the bottom plate side and supporting the gas generating agent from the bottom plate side, the cushioning material being characterized in that a substantially disk-shaped upper support member is arranged at the end of the combustion chamber located on the top plate side, and at least a portion of the gas generating agent is arranged between the cup-shaped member and the upper support member so as to contact the upper support member . The cup-shaped member also includes a top wall portion having a thin-walled fragile portion at least in part thereof, and a side wall portion of the cup-shaped member that separates the transfer chamber from the combustion chamber and has a higher mechanical strength than the fragile portion. The side wall portion also includes a thin-walled portion provided on the top wall portion side and a thick-walled portion extending from the thin-walled portion along the axial direction to the opposite side from the top wall portion, the fragile portion being disposed opposite the ignition portion and having a mechanical strength such that the cup-shaped member ruptures, deforms, or melts before the side wall portion does upon activation of the igniter, and the thin-walled portion has a mechanical strength such that the cup-shaped member ruptures, deforms, or melts if the rupture, deformation, or melting in the fragile portion extends to the thin-walled portion.

The present invention makes it possible to provide a gas generator that can demonstrate sufficient gas output performance even with a relatively small amount of transfer charge.

1 is a schematic cross-sectional view of a disk-type gas generator according to an embodiment of the present invention. FIG. 2 is a plan view of a cup-shaped member of the disk-type gas generator of FIG. 1. 2 is a schematic cross-sectional view for explaining the operation of the disk-type gas generator of FIG. 1. FIG. FIG. 10 is a schematic cross-sectional view of a disk-type gas generator according to a modified example of the embodiment of the present invention. FIG. 10 is a schematic cross-sectional view of a disk-type gas generator according to comparative examples 1 and 2 of verification test 1. FIG. 10 is a schematic cross-sectional view of a disk-shaped gas generator according to Comparative Example 3 of Verification Test 1 and Comparative Example 4 of Verification Test 2. FIG. 1 is a diagram showing test conditions and test results of verification test 1. FIG. 10 is a diagram showing test conditions and test results of verification test 2. FIG. 10 is a diagram showing test conditions and test results of verification test 3. FIG. 10 is a schematic cross-sectional view of a disk-type gas generator according to a modified example of the embodiment of the present invention. FIG. 10 is a diagram showing test conditions and test results of verification test 4.

Embodiments of the present invention will now 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 suitable for incorporation into an airbag device mounted on the steering wheel of an automobile, etc. In the embodiments shown below, identical or common parts are designated by the same reference numerals in the drawings, and their description will not be repeated.

Figure 1 is a schematic diagram of a disk-type gas generator 100 according to an embodiment of the present invention. First, the configuration of the disk-type gas generator 100 according to this embodiment will be described with reference to Figure 1.

As shown in FIG. 1, the disk-type gas generator 100 has a short, approximately cylindrical housing with one axial end and the other closed, and the storage space provided inside this housing contains internal components such as a holder 30, an igniter 40, a cup-shaped member 50, a transfer charge 59, a gas generating agent 61, a lower support member 70, an upper support member 80, a cushion material 85, and a filter 90. Also located in the storage space provided inside the housing is a combustion chamber 60 that primarily contains the gas generating agent 61, one of the internal components described above.

The housing includes a lower shell 10 and an upper shell 20. Each of the lower shell 10 and the upper shell 20 is a press-formed product formed, for example, by pressing a rolled metal plate. The metal plate members that make up the lower shell 10 and the upper shell 20 are made of metal plates made of stainless steel, iron steel, aluminum alloy, stainless alloy, etc., and preferably so-called high-tensile steel plates are used, which will not break or otherwise be damaged even when a tensile stress of 440 MPa or more but 780 MPa or less is applied.

The lower shell 10 and 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.

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, thereby forming a press fit. 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 abutment, 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.

As a result, the portion of the housing's peripheral wall closest to the bottom plate 11 is formed by the peripheral wall 12 of the lower shell 10, and the portion of the housing's peripheral wall closest to the top plate 21 is formed by the peripheral wall 22 of the upper shell 20. Furthermore, one axial end and the other axial end 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.

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 the portion where the igniter 40 is fixed via the holding portion 30, and the recessed portion 14 is the portion that provides space for providing the female connector portion 34 in the holding portion 30.

The protruding tube portion 13 is formed in a generally cylindrical shape with a bottom, and its axial end portion located on the top plate portion 21 side has an opening 15 that is asymmetrical in a plan view (e.g., D-shaped, barrel-shaped, oval, etc.). This opening 15 is the portion through which a pair of terminal pins 42 of the igniter 40 are inserted.

The igniter 40 is used to generate a flame and includes an ignition unit 41 and the pair of terminal pins 42 described above. The ignition unit 41 contains 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 connected to the ignition unit 41 to ignite the ignition charge.

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 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.

The resistor typically uses nichrome wire, and the ignition charge typically uses ZPP (zirconium potassium perchlorate), ZWPP (zirconium tungsten potassium perchlorate), lead tricinate, or the like. The squib cup and plug mentioned above are generally made of metal or plastic.

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 produced by the combustion ruptures the squib cup containing the ignition charge. The time it takes for the igniter 40 to activate after current flows through the resistor is generally less than 2 ms when nichrome wire is used for the resistor.

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

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 through an opening 15 provided in the bottom plate portion 11 so that the material extends from part of the inner surface of the bottom plate portion 11 to part of the outer surface, and then solidifying the material.

The raw material for the retaining portion 30 formed by injection molding is preferably a resin material that exhibits excellent heat resistance, durability, and corrosion resistance after hardening. 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 (such as nylon 6 or nylon 66), polypropylene sulfide resin, and polypropylene oxide resin can also be used. When selecting such a thermoplastic resin 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, there is no need to add a filler as described above.

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.

The retaining portion 30 is fixed to the bottom plate portion 11 on the surfaces of the inner covering portion 31, outer covering portion 32, and connecting portion 33 facing 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.

As a result, the opening 15 is completely filled with the terminal pin 42 and the retaining portion 30, ensuring a seal in this area and ensuring airtightness of the space inside the housing. As mentioned above, the opening 15 is formed asymmetrically in a plan view, and therefore, by filling the opening 15 with the connecting portion 33, the opening 15 and connecting portion 33 also function as a rotation prevention mechanism that prevents the retaining portion 30 from rotating relative to the bottom plate portion 11.

A female connector portion 34 is formed on the outer-facing portion of the outer covering portion 32 of the holder 30. This 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.

The lower end of the terminal pin 42 of the igniter 40 is exposed and positioned within this female connector portion 34. A male connector is inserted into the female connector portion 34, thereby establishing electrical continuity between the harness core wire and the terminal pin 42.

The above-described injection molding may also be performed using a lower shell 10 in which an adhesive layer has already been applied at a predetermined position on the surface of the bottom plate 11 in the area that will be covered by the retaining portion 30. The adhesive layer can be formed by applying adhesive to a predetermined position on the bottom plate 11 and then allowing it to harden.

In this way, the hardened adhesive layer is positioned between the bottom plate portion 11 and the retaining portion 30, making it possible to more firmly adhere the retaining portion 30, which is made of a molded resin portion, to the bottom plate portion 11. Therefore, by providing the adhesive layer 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 level of sealing in that area.

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 resin materials mentioned above, adhesives 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.

Note that while the configuration shown here is one in which the igniter 40 can be fixed to the lower shell 10 by injection molding the retaining portion 30, which is made of a resin molded portion, other alternative means can also be used to fix the igniter 40 to the lower shell 10.

A cup-shaped member 50 is attached to the bottom plate 11 so as to cover the protruding tube 13, the holding portion 30, and the igniter 40. The cup-shaped member 50 has a generally cylindrical shape with a bottom and an open end on the bottom plate 11 side, and contains 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, which contains the gas generating agent 61, so that the space provided therein faces the ignition portion 41 of the igniter 40.

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 open end of the side wall portion 52 on the bottom plate portion 11 side.

The side wall portion 52 has a thin portion 52a provided on the top wall portion 51 side and a thick portion 52b extending from the thin portion 52a along the axial direction opposite the top wall portion 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.

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 that follows 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 flange-like tip portion 54 extending radially outward.

The tip 54 of the extension 53 is positioned 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 secure the cup-shaped member 50.

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

The cup-shaped member 50 is preferably made of metals such as stainless steel, steel, aluminum, aluminum alloy, stainless steel, or stainless steel alloy, or resins such as thermosetting resins such as epoxy resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyamide resin (such as nylon 6 or nylon 66), polypropylene sulfide resin, and polypropylene oxide resin. 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.

Note that the method for fixing the cup-shaped member 50 is not limited to the method using the lower support member 70 described above, and other fixing methods may also be used.

At least a portion of the top wall 51 of the cup-shaped member 50 is provided with a weak portion 55 that is thinner than the side wall 52. As shown in FIG. 2, the weak portion 55 is formed 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 weak portion 55 is positioned so that it faces the ignition portion 41 of the igniter 40. In addition, the portion of the top wall 51 other than the radially extending weak portion 55 is provided with a non-weak portion 56 that is thicker than the weak portion 55 and has a thickness similar to that of the thick portion 52b.

As a result, the space inside the cup-shaped member 50 is such that the weak portion 55 ruptures (breaks), deforms, or melts due to the thrust generated by the combustion of the transfer charge 59, and then the thin-walled portion 52a ruptures (breaks), deforms, or melts in accordance with the rupture (breaks), deformation, or melting of the weak portion 55, resulting in a relatively low mechanical strength of the weak portion 55 and the thin-walled portion 52a. On the other hand, the non-weak portion 56 and the thick-walled portion 52b are thicker than the weak portion 55, and are therefore configured to remain even after the transfer charge 59 burns when the igniter 40 is activated.

The thicknesses of the above-mentioned 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 transfer charge 59 used, and the following is an example. For example, if the cup-shaped member is made of iron, stainless steel, or an aluminum alloy, the thickness of the above-mentioned fragile portion 55 and thin portion 52a is 0.6 mm or less, and preferably 0.5 mm or less. On the other hand, if the cup-shaped member is made of iron, stainless steel, or an aluminum alloy, the thickness of the non-fragile portion 56 and thick portion 52b is 0.6 mm to 1.5 mm, preferably 0.6 mm to 1.2 mm, provided that it is greater than the thickness of the fragile portion 55 and thin portion 52a.

The above-mentioned fragile portion 55 is not limited to the one shown in Figure 2, and may consist 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 when viewed from above.

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/KNO ₃ , B/NaNO ₃ , or Sr(NO ₃ ) ₂ , a composition made of titanium hydride/potassium perchlorate, or a composition made of B/5-aminotetrazole/potassium nitrate/molybdenum trioxide, is used.

The enhancer charge 59 may be in powder form or formed into a specific shape using a binder. Enhancer charge 59 formed using a binder can take a variety of shapes, including granules, cylinders, sheets, spheres, single-hole cylinders, multi-hole cylinders, and tablets.

A combustion chamber 60 containing gas generating agent 61 is located in the space within the housing, surrounding the portion in which the cup-shaped member 50 is disposed. 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.

In addition, a filter 90 is arranged along the inner periphery of the housing in the space radially surrounding the combustion chamber 60 containing the gas generating agent 61. The filter 90 has a cylindrical shape and is arranged so that its central axis substantially coincides with the axial direction of the housing.

The gas generant 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. It is preferable to use a non-azide gas generant as the gas generant 61, and the gas generant 61 is generally formed as a molded body containing fuel, an oxidizer, and an additive.

The fuel may be, for example, a triazole derivative, a tetrazole derivative, a guanidine derivative, an azodicarbonamide derivative, a hydrazine derivative, or a combination of these. Specifically, nitroguanidine, guanidine nitrate, cyanoguanidine, or 5-aminotetrazole is preferably used.

Examples of oxidizing agents 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.

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.

The molded body of the gas generating agent 61 may take a variety of shapes, including granular, pellet-like, cylindrical, and other granular shapes, as well as disk-like shapes. Cylindrical molded bodies may also be used that have perforations inside (such as single-hole or multi-hole cylindrical shapes). These shapes are preferably selected appropriately depending on the specifications of the airbag device into which the disk-type gas generator 100 is incorporated. It is preferable to select the optimal shape for the specifications, such as a shape that changes the gas generation rate over time when the gas generating agent 61 burns. In addition to the shape of the gas generating agent 61, it is also preferable to select the size and filling amount of the molded body appropriately, taking into consideration the burning rate and pressure exponent of the gas generating agent 61, etc.

The filter 90 can be made of, for example, metal wire such as stainless steel or steel that has been wound and sintered, or a mesh of woven metal wire that has been pressed together. Specific examples of mesh materials that can be used include stockinette knit wire mesh, plain woven wire mesh, and a collection of crimped metal wires.

The filter 90 can also be made of a wound perforated metal plate. Examples of perforated metal plates include expanded metal, which is made by cutting staggered slits into a metal plate and expanding the slits to form holes and create a mesh-like structure, and hook metal, which is made by drilling holes into a metal plate and flattening the edges of the holes by crushing any burrs that may form around them. The size and shape of the holes can be modified as needed, and holes of different sizes and shapes may be included on the same metal plate. Suitable metal plates include mild steel and stainless steel, as well as non-ferrous metals such as aluminum, copper, titanium, nickel, and alloys of these.

The filter 90 functions as a cooling device that cools the gas generated in the combustion chamber 60 by removing the high-temperature heat contained in the gas as it passes through the filter 90, and also functions as a removal device that removes residue (slag) and other contaminants 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 positioned away from the peripheral wall portions 12 and 22 of the lower shell 10 and upper shell 20, which constitute the peripheral wall portions of the housing, so that a predetermined gap 28 is formed between the filter 90 and the peripheral wall portions 12 and 22.

The peripheral wall portion 22 of the upper shell 20 facing the filter 90 is provided with multiple gas outlets 23. These multiple gas outlets 23 are used to guide gas that has passed through the filter 90 to the outside of the housing.

In addition, metal sealing tape 24 is attached to the inner surface of the peripheral wall portion 22 of the upper shell 20 as a sealing member to close the multiple gas outlets 23. Aluminum foil with an adhesive applied to one side can be suitably used as this sealing tape 24, and the sealing tape 24 ensures the airtightness of the combustion chamber 60.

A lower support member 70 is disposed near the end of the combustion chamber 60 that faces the bottom plate 11. The lower support member 70 has an annular shape and is disposed substantially between the filter 90 and the bottom plate 11, covering the boundary between them. 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.

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 abutment portion 72 that abuts against the inner peripheral surface of the filter 90 near the bottom plate portion 11, and a tubular upright portion 73 that stands upright from the base portion 71 toward the top plate portion 21. The abutment 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.

The lower support member 70 not only secures the filter 90 to the housing, but also functions as an outflow prevention device that prevents 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 interior of the filter 90. For this reason, the lower support member 70 is formed, for example, by pressing a metal plate-shaped member, and is preferably made of a steel plate such as ordinary steel or special steel (for example, a cold-rolled steel plate or a stainless steel plate).

A circular disk-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 to prevent the molded gas generating agent 61 from being crushed by vibration or the like, and is preferably made of a ceramic fiber molded body, rock wool, foamed resin (such as foamed silicone, foamed polypropylene, foamed polyethylene, foamed urethane, etc.), rubber such as chloroprene and EPDM, etc.

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

In addition, the cushion material 85 is located at a predetermined distance from the top wall portion 51 of the cup-shaped member 50. Therefore, when the igniter 40 is activated, the transfer charge 59 is able to reach the gas generant 61 and transfer the flame without being adsorbed to the cushion material 85, allowing the gas generant 61 to burn efficiently and achieving the desired gas output performance of the gas generator 100.

Furthermore, because the cushion material 85 is provided on the bottom plate 11 side of the combustion chamber 60, more gas generating agent 61 can be placed between the top wall 51 and the top plate 21 of the cup-shaped member 50 than if the cushion material 85 were 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. Note that the amount of gas generated is adjusted appropriately based on the amount of gas generating agent 61 placed between the top wall 51 and the top plate 21 of the cup-shaped member 50, and an example is shown below. For example, it is preferable that 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 placed above the top wall 51 be 5 mm or more and 20 mm or less.

An upper support member 80 is disposed at the end of the combustion chamber 60 facing the top plate 21. The upper support member 80 has a generally disc-like shape and is positioned between the filter 90 and the top plate 21, covering the boundary between them. 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.

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

The upper support member 80 not only secures the filter 90 to the housing, but also functions as an outflow prevention device that prevents gas generated in the combustion chamber 60 from escaping through the gap between the upper end of the filter 90 and the top plate 21 without passing through the interior of the filter 90 when the igniter 40 is activated. For this reason, the upper support member 80 is formed, for example, by pressing a metal plate-shaped member, and is preferably made of a steel plate such as ordinary steel or special steel (for example, a cold-rolled steel plate or a stainless steel plate).

Next, with reference to Figure 1, the assembly procedure for the disk-type gas generator 100 in this embodiment will be described.

First, the igniter 40 is fixed to the lower shell 10 by injection molding the retaining portion 30, which is made of a resin molded portion. The side wall portion 52 of the cup-shaped member 50, which contains the transfer charge 59, is then press-fitted into the retaining portion 30 of the lower shell 10 to secure it in place. Next, the lower support member 70 is placed on the tip portion 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, cushion material 85 is placed on the upper surface of the base 71 of the lower support member 70, gas generating agent 61 is filled inside the filter 90, and the upper support member 80 is inserted into the upper end portion of the filter 90. After this, the upper shell 20, whose gas outlets 23 have been sealed with sealing tape 24, is placed over the lower shell 10, and the lower shell 10 and upper shell 20 are welded together. This completes the assembly of the disk-type gas generator 100 having the structure shown in Figure 1.

In the disk-shaped gas generator 100 of this embodiment, the cup-shaped member 50 does not have an opening, which makes it extremely easy to fill the transfer charge 59 into the transfer chamber 57 provided inside the cup-shaped member 50. This is because the cup-shaped member 50 itself is constructed of a fragile material with low mechanical strength, so that a portion of the cup-shaped member may rupture, deform, or melt when the disk-shaped gas generator 100 is activated. In other words, the work of closing the opening provided in the cup-shaped member to fill the transfer charge 59, such as with aluminum tape or a closing plate, which was necessary when using a cup-shaped member with an opening, is no longer necessary, which greatly simplifies the manufacturing process.

Figure 3 is a schematic cross-sectional view for explaining the operation of the disk-type gas generator 100 in this embodiment. Next, with reference to Figure 3 and the aforementioned Figure 1, the operation of the disk-type gas generator 100 in this embodiment will be explained.

Referring to FIG. 1, when a vehicle equipped with a disk-type gas generator 100 collides, the collision is detected by collision detection means separately provided in the vehicle, and based on this, the igniter 40 is activated by current supplied from a control unit separately provided in the vehicle. The transfer charge 59 contained in the transfer chamber 57 is ignited by the flame generated by the activation of the igniter 40, and begins to burn.

As shown in Figure 3, immediately after the igniter 40 is activated, the ignition charge loaded in the ignition section 41 rapidly burns, 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.

As shown in FIG. 3, 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. Note that 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, and the internal pressure rises until the top wall 51 ruptures, deforms, or melts. Here, 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. As shown in Figure 2, the fragile portion 55 is provided as a slit, and ruptures, deforms, or melts from the top wall portion 51 of the cup-shaped member 50 first, then splits open to the thin portion 52a of the side wall portion 52. In accordance with the rupture (break), deformation, or melting of the fragile portion 55, the thin portion 52a ruptures (breaks), deforms, or melts, and splits open all the way to the connection with the thick portion 52b. Here, the thick portion 52b does not rupture (break), deform, or melt.

As a result, even the transfer charge 59 located farther from the igniter 40 is ignited by the thermal particles and begins to burn in a shorter time, resulting in a significant increase in pressure and temperature within 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 then come into contact with the gas generant 61 without being affected by the cushion material 85 provided in the lower shell 10 or being deactivated.

In this way, the transfer charge 59 and the large amount of thermal particles generated by it flow into the combustion chamber 60, igniting and burning the gas generating agent 61 contained in the combustion chamber 60 and generating a large amount of gas. The gas generated in the combustion chamber 60 passes through the inside of the filter 90, during which time heat is removed by the filter 90 and cooled, and slag contained in the gas is removed by the filter 90 and flows into the gap 28.

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

Furthermore, when the cup-shaped member 50 is made of iron or stainless steel, its strength is higher than when it is made of aluminum. Therefore, the cup-shaped member 50 does not rupture, deform, or melt during 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. 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, and increasing the mechanical strength, the combustion of the transfer charge 59 can be sufficiently promoted 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 its 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.

The mechanism by which the transfer charge 59 can be suitably controlled to transfer flame energy in the disk-shaped gas generator 100 of this embodiment will be described below with reference to Figure 1.

In the disk-shaped gas generator 100 configured as described above, activation of the igniter 40 ignites the transfer charge 59 inside the transfer chamber 57, causing the fragile portion 55 of the cup-shaped member 50 to rupture, deform, or melt first. Because the cup-shaped member 50 ruptures, deforms, or melts from the point of origin, there is no risk of rupture, deformation, or melting from the side wall portion 52, where the fragile portion 55 is not present. The transfer charge 59 burns sufficiently before the top wall portion 51 ruptures, deforms, or melts. The top wall portion 51 then begins to split open along the fragile portion 55, starting from the ruptured, deformed, or melted fragile portion 55. After the top wall portion 51 splits open, the split reaches the thin-walled portion 52a of the side wall portion 52, splitting the thin-walled portion 52a of the side wall portion 52. The splitting then stops at the connection between the thin-walled portion 52a and the thick-walled portion 52b.

In this way, the fragile portion 55 splits along its length, resulting in a petal-like split all the way to the connection between the thin portion 52a and the thick portion 52b. Therefore, the cup-shaped member 50 splits partway and then stops, expanding over time toward the top plate 21. Since the size of the rupture in the cup-shaped member 50 remains stable, the thermal particles generated by the combustion of the transfer charge 59 flow more directional toward the top plate 21. In other words, the flame flowing into the combustion chamber 60 is constricted between the cup-shaped member 50 and the top plate 21. Therefore, in the first stage of cleavage, when the weak portion 55 ruptures, deforms, or melts, and the non-weak portion of the top wall portion 51 cleaves starting from the weak portion 55, all of the gas generating agents 61 adjacent to the cup-shaped member 50 will no longer be ignited simultaneously, and the spread of the flames of the gas generating agents 61 will progress mainly between the transfer chamber 57 and the top plate portion 21.

As the rupture, deformation, or melting of the top wall 51 of the cup-shaped member 50 progresses, the second stage begins, in which the thin-walled portion 52a of the side wall 52 begins to split. The splitting of the side wall 52 proceeds along the longitudinal direction of the weakened portions 55 radially arranged on the top wall 51. The thin-walled portion 52a splits downward in the axial direction of the side wall 52, but after splitting partway, the splitting stops. Therefore, thermal particles generated by the combustion of the transfer charge 59 flow into the combustion chamber 60 from the split portion. As a result, the fire spreads to the gas generant 61 between the thin-walled portion 52a and the filter 90, and then to the gas generant 61 between the thick-walled portion 52b and the filter 90.

Therefore, by providing the cup-shaped member 50 with the fragile portion 55, non-fragile portion 56, thin portion 52a, and thick portion 52b and appropriately adjusting the positions and sizes of these fragile portion 55, non-fragile portion 56, thin portion 52a, and thick portion 52b, it is possible to prevent the gas generant 61 from burning too quickly and intentionally slow the progression of combustion, making it very easy to optimize gas output adjustments according to specifications, such as maintaining gas output for a predetermined period of time. Furthermore, in the early stages of rupture, deformation, or melting of the cup-shaped member 50, thermal particles generated by the combustion of the transfer charge 59 flow toward the top plate portion 21, thereby mitigating the impact on the filter 90 and preventing damage.

Furthermore, because the cushioning material 85 is positioned on the bottom plate 11 side, combustion of the gas generating agent 61 between the top wall 51 and the top plate 21 proceeds smoothly immediately after the top wall 51 of the cup-shaped member 50 ruptures, deforms, or melts. This prevents delays in gas output, quickly increases the internal pressure inside the gas generator, and prevents variations in gas output characteristics.

Whether the weak portion 55 and thin-walled portion 52a of the cup-shaped member 50 will rupture, deform, or melt when the thrust generated by the activation of the igniter 40 propagates depends on the mechanical strength (thickness, material, shape, etc.) of the cup-shaped member 50, the output of the igniter 40, the distance between the ignition portion 41 and the weak portion 55 of the cup-shaped member 50, the density of the transfer charge 59 filled in the transfer chamber 57, etc.

Furthermore, it is preferable that the fragile portion 55 of the cup-shaped member 50 has a lower mechanical strength than the side wall portion 52 of the cup-shaped member 50. Possible methods for making the fragile portion 55 of the cup-shaped member 50 weaker than the side wall portion 52 of the cup-shaped member 50 include adjusting their thickness, using different materials for them, or devising their shapes.

By configuring it in this manner, it is relatively easy to cause the fragile portion 55 to rupture, deform, or melt before the thin-walled portion 52a of the cup-shaped member 50 ruptures, deforms, or melts. However, if the fragile portion 55 can be caused to rupture, deform, or melt before the thin-walled portion 52a of the cup-shaped member 50 ruptures, deforms, or melts, the fragile portion 55 and the thin-walled portion 52a of the side wall portion 52 of the cup-shaped member 50 may have approximately the same mechanical strength.

As explained above, according to the disk-type gas generator 100 in the above-described embodiment of the present invention, after the top wall portion 51 of the cup-shaped member 50 ruptures, deforms, or melts, combustion of the gas generant 61 between the top wall portion 51 and the top plate portion 21 proceeds smoothly, thereby making it possible to promote combustion of the gas generant 61 in the combustion chamber 60. As a result, the time from the moment the igniter 40 is activated to the moment gas begins to be ejected to the outside through the gas outlet 23 can be shortened compared to conventional methods. Furthermore, the size of the rupture of the cup-shaped member 50 is stabilized (the rupture area is uniform), and the transfer charge 59 transfers flame to the gas generant 61 without being affected by the cushion material 85. This allows the disk-type gas generator 100 to achieve the desired gas output performance while reducing the amount of transfer charge 59 charged.

Furthermore, by adding the fragile portion 55 and thin-walled portion 52a to the cup-shaped member 50, although the amount of part processing required increases, the amount of transfer charge 59 required can be significantly reduced, thereby reducing the time from when the igniter 40 is activated until gas begins to be ejected to the outside through the gas outlet 23 at low cost.

In addition, by reducing the amount of transfer charge 59 filled, the volume of the cup-shaped member 50 can be made smaller than before, making it possible to optimize the volume of the disk-type gas generator 100 and thereby reduce its weight.

In addition, since the gas temperature drops as the amount of transfer charge 59 decreases, the cooling capacity of the filter 90 can be reduced accordingly. As a result, the weight of the filter 90 can also be reduced.

The above describes embodiments of the present invention, but these are merely illustrative examples and do not limit the present invention in any way. Specific configurations and other aspects can be modified as appropriate. Furthermore, the actions and effects described in the embodiments of the invention are merely a list of the most favorable 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.

In the above embodiment, the cushion material 85 is disposed on the bottom plate portion 11 side, but this is not limiting. The cushion material 85 only needs to be located a predetermined distance from the cup-shaped member 50, and it only needs to be located at a distance that does not cause the transfer charge 59 to be deactivated before the transfer of ignition to the gas generant 61 is complete when the igniter 40 is activated. For example, the cushion material 85 may be located at a position where the transfer charge 59 does not become adsorbed onto the cushion material 85 before the transfer of ignition to the gas generant 61 is complete, or at a position far from the cup-shaped member 50 where the transfer charge 59 is the last to reach the cushion material 85 within the combustion chamber 60.

In the above embodiment, the side wall portion 52 of the cup-shaped member 50 is described as having a thin portion 52a and a thick portion 52b, but this is not limited to this. The side wall portion 52 of the cup-shaped member 50 only needs to be configured to have a higher mechanical strength than the fragile portion 55 of the cup-shaped member 50. For example, the thickness of the side wall portion 52 may be constant by making the material of the side wall portion 52 and the material of the fragile portion 55 different.

A modified version of the above embodiment will be described below with reference to Figure 4. Note that a disk-shaped gas generator 200 according to the modified version of the above embodiment differs from disk-shaped gas generator 100 according to the above embodiment only in the configuration of the cup-shaped member. Note that components in this modified version whose last two digits are the same as those in the above embodiment are the same components unless otherwise specified, and therefore their description will be omitted.

As shown in FIG. 4 , in the disk-type gas generator 200, the cup-shaped member 250 has a top wall portion 251, a cylindrical side wall portion 252 extending from the periphery of the top wall portion 251 toward the bottom plate portion 211, and an extension portion 253 extending radially outward from the open end of the side wall portion 252, which is the end portion on the bottom plate portion 211 side. The extension portion 253 has a curved shape to follow the shape of the inner bottom surface of the bottom plate portion 211 at and near the portion where the protruding cylindrical portion 213 is provided, and includes a flange-like extending tip portion 254 at its radially outer portion. The thicknesses of the top wall portion 251, side wall portion 252, extension portion 253, and tip portion 254 of the cup-shaped member 250 are constant. The cup-shaped member 250 has sufficient mechanical strength to cause at least a portion of the cup-shaped member 250 to burst, deform, or melt when the igniter 240 is activated.

The cup-shaped member 250 is preferably made of a metal such as stainless steel, steel, aluminum, aluminum alloy, stainless steel, or stainless steel alloy, or a resin such as a thermosetting resin such as epoxy resin, or a thermoplastic resin such as polybutylene terephthalate resin, polyethylene terephthalate resin, polyamide resin (such as nylon 6 or nylon 66), polypropylene sulfide resin, or polypropylene oxide resin. In particular, aluminum alloys or iron-based metal materials such as stainless steel or steel are preferred, as they have relatively higher mechanical strength than aluminum.

In the disk-shaped gas generator 200 configured in this manner, the transfer charge 259 burns when the igniter 240 is activated, and as a result of the thrust generated by this combustion, at least a portion of the top wall 251 or side wall 252 of the cup-shaped member 250 ruptures, deforms, or melts. The transfer charge 259 and a large amount of thermal particles generated by the transfer charge 259 then flow into the combustion chamber 260, reach the gas generant 261 without being adsorbed by the cushion material 285, and transfer the flame. In other words, since the cushion material 285 is located on the bottom plate 211 side, combustion of the gas generant 261 between the top wall 251 and the top plate 221 proceeds smoothly, preventing delays in gas output, rapidly increasing the internal pressure within the gas generator, and preventing variations in gas output characteristics. Therefore, the disk-type gas generator 200 can promote combustion of the gas generating agent 261 in the combustion chamber 260, enabling the desired gas output performance to be achieved.

(Verification Test 1)
As Example 1 and Example 2, disk-shaped gas generators having the same configuration as disk-shaped gas generator 200 were manufactured and subjected to a 60 L tank test described below. Furthermore, as Example 3, a disk-shaped gas generator having the same configuration as disk-shaped gas generator 100 was manufactured and subjected to a similar 60 L tank test. Note that in the disk-shaped gas generators according to Examples 1 to 3, the cushioning material is arranged on the bottom plate side of the combustion chamber (arranged below). Furthermore, in the disk-shaped gas generators according to Examples 1 to 3, the material of the cup-shaped member was made of an aluminum alloy.

As Comparative Example 1, a disk-shaped gas generator was manufactured that differed from the disk-shaped gas generator of Example 1 only in that the cushioning material was positioned on the top plate side of the combustion chamber (upper position), and a 60L tank test was conducted. Similarly, as Comparative Example 2, a disk-shaped gas generator was manufactured that differed from the disk-shaped gas generator of Example 2 only in the positioning of the cushioning material, and a 60L tank test was conducted. Note that Figure 5 is a schematic cross-sectional view of a disk-shaped gas generator 300 with the same configuration as Comparative Examples 1 and 2. Furthermore, the cup-shaped member in Comparative Examples 1 and 2 was made of an aluminum alloy.

As Comparative Example 3, a disk-shaped gas generator was manufactured that differed from the disk-shaped gas generator of Example 3 only in that the cushioning material was positioned on the top plate side of the combustion chamber (upper position), and a 60L tank test was conducted. Figure 6 is a schematic cross-sectional view of disk-shaped gas generator 400 with the same configuration as Comparative Example 3. Furthermore, the material of the cup-shaped member of Comparative Example 3 was an aluminum alloy.

In Verification Test 1, the 60L tank test involved individually placing the disk-type gas generators according to Examples 1 to 3 and Comparative Examples 1 to 3 in a sealed tank with a volume of 60L, operating them at room temperature (RT), and measuring the increase in tank internal pressure over time from the time the igniter was activated up to 100 ms.

Figure 7 shows the results of Verification Test 1. In Figure 7, t1 is the time until gas output is detected, Pt20 is the tank internal pressure 20 ms after the igniter is activated, Pt40 is the tank internal pressure 40 ms after the igniter is activated, and Pmax is the maximum tank internal pressure. The same applies to Figures 8 and 9 below.

From the results in Figure 7, it was found that the disk-shaped gas generator according to Example 1 had a similar t1 compared to the disk-shaped gas generator according to Comparative Example 1, but Pt20, Pt40, and Pmax were all larger, enabling it to exhibit high gas output performance. Furthermore, it was found that the disk-shaped gas generator according to Example 2, in which the amount of transfer charge was reduced compared to Example 1 (weight reduction) could exhibit high gas output performance at a relatively early stage from the time the igniter was activated, compared to the disk-shaped gas generator according to Comparative Example 2. Furthermore, it was found that the disk-shaped gas generator according to Example 3, which was also designed to be lighter, could exhibit high gas output performance at a relatively early stage from the time the igniter was activated, compared to the disk-shaped gas generator according to Comparative Example 3. Therefore, it was found that the disk-shaped gas generators according to Examples 1 to 3, in which the cushioning material was arranged lower, had improved gas output performance when compared in order with Comparative Examples 1 to 3, in which the cushioning material was arranged upper.

Furthermore, in the disk-type gas generator according to Example 3, t1 is shorter and both Pt20 and Pt40 are larger than in the disk-type gas generator according to Example 2, and it was found that desirable gas output performance can be stably exhibited while reducing the amount of transfer charge. Therefore, it was confirmed that a disk-type gas generator having the same configuration as the above-mentioned disk-type gas generator 100 of the present invention can be made lighter in weight and can stably exhibit excellent gas output performance.

(Verification Test 2)
Next, a disk-shaped gas generator having the same configuration as disk-shaped gas generator 400 shown in FIG. 6 was manufactured, and verification test 2 was conducted to determine what changes would occur in a 60 L tank test, which will be described later, depending on whether or not a cushioning material was provided.

Here, the disk-shaped gas generator according to Comparative Example 4 has a cushioning material arranged on the top plate side of the combustion chamber (upper arrangement). The disk-shaped gas generator according to Comparative Example 5 does not have a cushioning material. The cup-shaped member according to Comparative Examples 4 and 5 is made of an aluminum alloy. All other conditions, except for the presence or absence of a cushioning material, were the same for each disk-shaped gas generator.

In Verification Test 2, the 60L tank test involved individually placing the disk-type gas generators according to Comparative Examples 4 and 5 in a sealed tank with a volume of 60L, operating them at -40°C (LT), and measuring the increase in tank internal pressure over time from the time the igniter was activated until 100 ms. Figure 8 shows the results of Verification Test 2.

The results in Figure 8 show that, in the disk-shaped gas generator according to Comparative Example 4, t1 is longer and Pt20, Pt40, and Pmax are all smaller than in the disk-shaped gas generator according to Comparative Example 5. Therefore, it was confirmed that, in the disk-shaped gas generator according to Comparative Example 4, in which the cushion material is arranged on top, gas output performance is reduced due to the influence of the cushion material compared to the disk-shaped gas generator according to Comparative Example 5.

(Verification Test 3)
Next, a disk-shaped gas generator having the same configuration as disk-shaped gas generator 100 shown in Figure 1 was manufactured, and verification test 3 was conducted to determine what changes would occur in the 60 L tank test described below by changing the height (distance from the upper support member) of the charge surface of the gas generating agent placed above the cup-shaped member (the topmost position of the gas generating agent).

Here, the disk-shaped gas generator according to Example 4 had a charge surface height of 3 mm for the gas generating agent. Furthermore, the disk-shaped gas generator according to Example 5 had a charge surface height of 5 mm for the gas generating agent. Furthermore, the disk-shaped gas generator according to Example 6 had a charge surface height of 7 mm for the gas generating agent. Note that the higher the charge surface height of the gas generating agent, the greater the amount of gas generating agent disposed between the top wall and ceiling plate of the cup-shaped member. Furthermore, the cup-shaped member according to Examples 4 to 6 was made of an aluminum alloy. Note that all other conditions, except for the charge surface height of the gas generating agent, were the same for each disk-shaped gas generator.

In Verification Test 3, the 60L tank test involved individually placing the disk-type gas generators according to Examples 4 to 6 in a sealed tank with a volume of 60L, operating them at -40°C (LT), and measuring the increase in tank internal pressure over time from the time the igniter was activated until 100 ms. Figure 9 shows the results of Verification Test 3.

The results in Figure 9 show that the disk-type gas generators of Examples 5 and 6 achieve higher gas output performance at a relatively early stage from the time the igniter is activated than the disk-type gas generator of Example 4. Therefore, it was found that in a disk-type gas generator having the same configuration as the above-mentioned disk-type gas generator 100 of the present invention, desirable gas output performance can be stably achieved if the height of the gas generating agent surface is 5 mm or more.

(Verification Test 4)
Next, a disk-shaped gas generator (Example 7) having the same configuration as gas generator 500 shown in Fig. 10 was manufactured, and verification test 4 was conducted to examine what changes would occur in the above-mentioned 60 L tank test depending on the presence or absence of a lower support member and the position of the cushioning material. The results of verification test 4 are shown in Fig. 11. Fig. 11 also shows the results of comparative example 3 and example 3 above.

Here, the gas generator 500 shown in FIG. 10 is a disk-shaped gas generator according to a modification of the above embodiment, and differs from the above embodiment in the following points: (1) it does not have a lower support member; and (2) on the lower shell 510 side, a disk-ring-shaped cushion material 585 is disposed within the housing 510 so that the inside of the cushion material 585 abuts against the outer wall and tip 554 of the lower part of the cup-shaped member 550, and the outside of the cushion material 585 abuts against the inner wall of the lower part of the filter 590. Note that components in this modification whose last two digits match those in the above embodiment are the same components unless otherwise specified, and therefore their description will be omitted. This gas generator 500 can achieve the same effects as the above embodiment. Furthermore, the cushion material 585 allows the filter 590 to be positioned when assembling the gas generator 500. Furthermore, by using the cushion material 585 to hold down the tip 554 (the part forming the flange) of the cup-shaped member 550, it is possible to prevent the cup-shaped member 550 from coming out of the inner covering part 531 before the cup-shaped member 550 is torn open. In addition, because the cushion material 585 remains unburned during operation, it is possible to prevent combustion residue from leaking out from between the lower end of the filter 590 and the inner wall of the lower shell 510.

The results of Figure 11 show that the disk-shaped gas generator according to Example 7 is able to demonstrate high gas output performance at a relatively early stage from the time the igniter is activated, compared to the disk-shaped gas generator according to Comparative Example 3. The results of Figure 11 also show that although the disk-shaped gas generator according to Example 7 does not have a lower support member, it is able to demonstrate gas output performance similar to that of the disk-shaped gas generator according to Example 3, which does have such a lower support member. In other words, the results of this verification test show that the disk-shaped gas generator according to Example 7 achieves the same effects as Example 3, while allowing for a reduction in the number of parts and weight compared to the disk-shaped gas generator according to Example 3.

10, 210, 310, 410, 510 Lower shell 11, 211, 311, 411, 511 Bottom plate portion 12, 212, 312, 412, 512 Peripheral wall portion 13, 213, 313, 413, 513 Protruding cylindrical portion 14, 214, 314, 414, 514 Recessed portion 15, 215, 315, 415, 515 Opening 20, 220, 320, 420, 520 Upper shell 21, 221, 321, 421, 521 Top plate portion 22, 222, 322, 422, 522 Peripheral wall portion 23, 223, 323, 423, 523 Gas outlet 24, 224, 324, 424, 524 Sealing tape 28, 228, 328, 428, 528 Gap portion 30, 230, 330, 430, 530 Holding portion 31, 231, 331, 431, 531 Inner covering portion 32, 232, 332, 432, 532 Outer covering portion 33, 233, 333, 433, 533 Connecting portion 34, 234, 334, 434, 534 Female connector portion 40, 240, 340, 440, 540 Igniter 41, 241, 341, 441, 541 Ignition portion 42, 242, 342, 442, 542 Terminal pin 50, 250, 350, 450, 550 Cup-shaped member 51, 251, 351, 451, 551 Top wall portion 52, 252, 352, 452, 552 Side wall portion 52a, 452a, 552a Thin portion 52b, 452b, 552b Thick portion 53, 253, 353, 453, 553 Extension portion 54, 254, 354, 454, 554 Tip portion 55, 455, 555 Weak portion 56, 456, 556 Non-weak portion 57, 257, 357, 457, 557 Transfer chamber 59, 259, 359, 459, 559 Transfer charge 60, 260, 360, 460, 560 Combustion chamber 61, 261, 361, 461, 561 Gas generant 70, 270, 370, 470 Lower support member 71, 81, 271, 281, 371, 381, 471, 481, 581 Base portion 72, 82, 272, 282, 372, 382, 472, 482, 582 Abutment portion 73, 273, 373, 473 Standing portion 80, 280, 380, 480, 580 Upper support member 85, 285, 385, 485, 585 Cushion material 90, 290, 390, 490, 590 Filter 100, 200, 300, 400, 500 Disk-type gas generator

Claims (1)

a short cylindrical housing having a combustion chamber therein and containing a gas generating agent, the housing being composed of a cylindrical peripheral wall portion provided with a gas ejection port, a top plate portion closing one axial end of the peripheral wall portion, and a bottom plate portion closing the other axial end of the peripheral wall portion; and an igniter including an ignition portion assembled to the bottom plate portion and containing an ignition charge that ignites when activated;
A cup-shaped member made of a single cylindrical member with a bottom, which includes a transfer chamber containing a transfer charge therein and is arranged to protrude toward the combustion chamber so that the internal space of the transfer chamber faces the ignition portion;
a cushioning material disposed on the bottom plate portion side and supporting the gas generating agent from the bottom plate portion side;
Equipped with
An approximately disk-shaped upper support member is disposed at an end of the combustion chamber that is located on the top plate side,
the gas generating agent disposed on the top plate portion side is disposed between the cup-shaped member and the upper support member so as to be in contact with the upper support member,
The cup-shaped member includes a top wall portion having a thin-walled weak portion at least in a portion thereof, and a side wall portion of the cup-shaped member that separates the transfer chamber and the combustion chamber and has a mechanical strength higher than that of the weak portion,
the side wall portion includes a thin portion provided on the top wall portion side and a thick portion extending from the thin portion along the axial direction to a side opposite the top wall portion,
the fragile portion is disposed opposite the ignition portion and has a mechanical strength that causes the cup-shaped member to rupture, deform, or melt before the side wall portion does upon activation of the igniter,
the thin-walled portion has a mechanical strength such that it will rupture, deform, or melt when rupture, deformation, or melting in the fragile portion progresses to the thin-walled portion;
Gas generator.