Gas generator

Abstract

To provide a gas generator capable of utilizing a space inside a mounting device more efficiently than conventional techniques.SOLUTION: A gas generator 100 is a short, substantially cylindrical disk-type gas generator and includes a housing, a holding portion, an igniter, a cup-shaped member, a lower support member, an upper support member, a gas generating agent, a cushion material, and a filter. The housing is a short, substantially semi-cylindrical shape with one end and the other end in the axial direction closed. The housing includes a lower shell and an upper shell 20. The lower shell and the upper shell 20 are each formed in a bottomed substantially semi-cylindrical shape, and the housing is configured by assembling and joining these shells such that their opening surfaces face each other. By disposing two gas generators 100 such that flat portions 22b face each other, it is possible to utilize a space inside the mounting target device efficiently.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a gas generator incorporated in an occupant protection device for protecting an occupant in the event of a collision of a vehicle or the like. [Background technology]

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

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

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

[0005] For example, Patent Document 1 discloses an airbag device in which a plurality of disk-shaped gas generators are arranged in parallel. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-132293 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in an airbag device incorporating a plurality of disk-shaped gas generators as in Patent Document 1, the space within the airbag device cannot be used efficiently, and there is a problem that the device becomes relatively large.

[0008] The present invention has been made in view of the above circumstances, and has an object to provide a gas generator that can utilize the space within the device to which it is to be assembled more efficiently than conventional gas generators. [Means for solving the problem]

[0009] (1) A gas generator of the present invention comprises a cylindrical housing, a gas generating agent contained in the housing and burning to generate gas, an igniter capable of igniting and burning the gas generating agent, and a filter provided around the circumference of the housing to surround the gas generating agent, wherein at least a portion of a side surface of the housing is formed into a shape that conforms to the shape of the interior of a target device when the gas generator is assembled to the target device.

[0010] (2) In the gas generator of (1) above, the portion having a shape that conforms to the shape of the interior of the device to be assembled is preferably a flat surface, a curved surface, or a surface having a wavy, stepped, or zigzag cross section.

[0011] (3) In the gas generator of (1) above, it is preferable that no gas outlet is provided in the portion having a shape that conforms to the shape of the interior of the device to be assembled.

[0012] (4) In the gas generator of (1) above, it is preferable that a flange portion used when assembling the gas generator to the target device is not provided on the portion shaped to conform to the shape inside the target device. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a gas generator that can utilize the space in the device to which it is assembled more efficiently than ever before. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a plan view showing a gas generator according to a first embodiment of the present invention. [Figure 2] 2A and 2B are side views of the gas generator of FIG. 1, where (a) is a view seen from one side, and (b) is a view seen from the opposite side to (a). [Figure 3] 2 is a cross-sectional view taken along the line AA of the gas generator of FIG. 1. [Figure 4] FIG. 4 is a plan view showing a gas generator according to a modified example of the first embodiment of the present invention. [Figure 5] FIG. 4 is a plan view showing a gas generator according to a second embodiment of the present invention. [Figure 6] FIG. 10 is a plan view showing a gas generator according to a third embodiment of the present invention. [Figure 7] FIG. 11 is a plan view showing a gas generator according to a modified example of the third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] First Embodiment A gas generator 100 according to a first embodiment of the present invention will now be described with reference to Figures 1 to 3. Note that Figure 1 shows a state in which two gas generators 100 are arranged adjacent to each other.

[0016] 1 to 3, gas generator 100 is a short, substantially cylindrical, disk-shaped gas generator, and includes a housing, a holding portion 30, igniter 40, cup-shaped member 50, lower support member 70, upper support member 80, cushion material 85, and filter 90. An accommodating space provided inside the housing accommodates internal components such as a part of holding portion 30, igniter 40, cup-shaped member 50, transfer charge 59, gas generating agent 61, lower support member 70, upper support member 80, cushion material 85, and filter 90. A combustion chamber 60, which mainly accommodates gas generating agent 61 out of the above-mentioned internal components, is located in the accommodating space provided inside the housing.

[0017] The housing is a short, approximately semi-cylindrical body with one axial end and the other axial end closed. The housing includes a lower shell 10 and an upper shell 20. The lower shell 10 and the upper shell 20 are each formed as a press-molded product, for example, by pressing a rolled metal plate-like member. The metal plate-like members constituting the lower shell 10 and the upper shell 20 are made of metal plates made of stainless steel, iron steel, aluminum alloy, stainless alloy, etc., and preferably so-called high-tensile steel plates that will not break or otherwise be damaged even when a tensile stress of 440 MPa or more but 780 MPa or less is applied.

[0018] The lower shell 10 and the upper shell 20 are each formed in a generally semi-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 11 and a peripheral wall 12, and the upper shell 20 has a top plate 21 and a peripheral wall 22. The peripheral wall 12 has a curved portion 12a with a semi-circular cross section and a flat portion 12b formed opposite the curved portion 12a, and extends from the outer periphery of the bottom plate 11 toward the upper shell 20. The peripheral wall 22 has a curved portion 22a with a semi-circular cross section, a flat portion 22b formed opposite the curved portion 22a, and a flange 25 formed at the lower end of the curved portion 22a, and extends from the outer periphery of the top plate 21 toward the lower shell 10. The flange portion 25 is formed with a plurality of through holes 25a that are used when attaching the flange portion 25 to a device (such as an airbag device) to be assembled.

[0019] The upper end of the peripheral wall 12 of the lower shell 10 is inserted into the lower end of the peripheral wall 22 of the upper shell 20 and press-fitted. Furthermore, the peripheral wall 12 of the lower shell 10 and the peripheral wall 22 of the upper shell 20 are joined at or near their 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 together.

[0020] As a result, the portion of the peripheral wall of the housing closer to the bottom plate 11 is formed by the peripheral wall 12 of the lower shell 10, and the portion of the peripheral wall of the housing closer to the top plate 21 is formed by the peripheral wall 22 of the upper shell 20. One end and the other end in the axial direction of the housing are closed by the bottom plate 11 of the lower shell 10 and the top plate 21 of the upper shell 20, respectively.

[0021] The igniter 40 is for generating a flame and includes an ignition portion 41 and a pair of terminal pins 42. The igniter 40 ignites and burns the gas generating agent 61. The ignition portion 41 is disposed inside the housing and is ignited by the flow of electric current. The ignition portion 41 includes an ignition charge that ignites and burns to generate a flame when activated, and a resistor for igniting the ignition charge. The pair of terminal pins 42 are a pair of terminal pins for passing electric current through the ignition portion 41. The pair of terminal pins 42 are connected to the ignition portion 41 to ignite the ignition charge. The pair of terminal pins 42 extend to the outside of the housing through the opening 15.

[0022] 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 close to the resistor.

[0023] Here, nichrome wire is generally used as the resistor, and ZPP (zirconium potassium perchlorate), ZWPP (zirconium tungsten potassium perchlorate), lead tricinate, etc. are generally used as the ignition charge. The squib cup and plug mentioned above are generally made of metal or plastic.

[0024] When a collision is detected, a predetermined amount of current flows through the resistor via the terminal pin 42. This current flow generates Joule heat in the resistor, causing the ignition charge to begin burning. The high-temperature flame generated by the combustion ruptures the squib cup containing the ignition charge. The time from when the current flows through the resistor to when the igniter 40 is activated is generally 2 ms or less when nichrome wire is used for the resistor.

[0025] Igniter 40 is attached to bottom plate 11 in a state where it is inserted from the inside of lower shell 10 so that terminal pin 42 passes through opening 15 provided in protruding cylindrical portion 13. Specifically, holding portion 30 made of a resin molded portion is provided around protruding cylindrical portion 13 provided on bottom plate 11, and igniter 40 is fixed to bottom plate 11 by being held by holding portion 30.

[0026] The gas generating agent 61 is an agent that is ignited by thermal particles generated by the transfer charge 59 when the igniter 40 is activated, and burns to generate gas. A non-azide gas generating agent is preferably used as the gas generating agent 61, and the gas generating agent 61 is generally formed as a molded body containing a fuel, an oxidizer, and an additive.

[0027] The fuel may be, for example, a triazole derivative, a tetrazole derivative, a guanidine derivative, an azodicarbonamide derivative, a hydrazine derivative, or a combination thereof. Specifically, nitroguanidine, guanidine nitrate, cyanoguanidine, 5-aminotetrazole, or the like is preferably used.

[0028] Examples of oxidizing agents that can be used include basic metal nitrates such as basic copper nitrate, basic metal carbonates such as basic copper carbonate, perchlorates such as ammonium perchlorate and potassium perchlorate, and nitrates containing cations selected from alkali metals, alkaline earth metals, transition metals, and ammonia. Suitable nitrates include sodium nitrate and potassium nitrate.

[0029] Examples of additives include binders, slag formers, and combustion modifiers. Suitable binders include organic binders such as polyvinyl alcohol, metal salts of carboxymethyl cellulose, and stearates, as well as inorganic binders such as synthetic hydrotalcite and acid clay. Other suitable binders include polysaccharide derivatives such as hydroxyethyl cellulose, hydroxypropyl methyl cellulose, cellulose acetate, cellulose propionate, cellulose acetate butyrate, nitrocellulose, microcrystalline cellulose, guar gum, polyvinylpyrrolidone, polyacrylamide, and starch, as well as inorganic binders such as molybdenum disulfide, talc, bentonite, diatomaceous earth, kaolin, and alumina. Suitable slag formers include silicon nitride, silica, and acid clay. Suitable combustion modifiers include metal oxides, ferrosilicon, activated carbon, and graphite.

[0030] The shape of the molded body of the gas generating agent 61 may be in various shapes, such as granular, pellet-like, cylindrical or other particulate shapes, or disk-like shapes. Furthermore, for cylindrical molded bodies, perforated molded bodies having through holes inside the molded body (for example, a single-hole cylindrical shape or a multi-hole cylindrical shape) are also used. These shapes are preferably selected as appropriate depending on the specifications of the airbag device in which the gas generator 100 is incorporated, and it is preferable to select an optimum shape depending on the specifications, such as selecting a shape in which the gas generation rate changes over time when the gas generating agent 61 is burned. Furthermore, in addition to the shape of the gas generating agent 61, it is preferable to select the size and filling amount of the molded body as appropriate, taking into consideration the burning rate, pressure exponent, etc. of the gas generating agent 61.

[0031] The filter 90 functions as a cooling means for cooling the gas generated in the combustion chamber 60 by removing the high-temperature heat of the gas as the gas passes through the filter 90, and also functions as a removal means for removing residue (slag) and the like contained in the gas. Therefore, in order to sufficiently cool the gas and prevent the residue from being released to the outside, it is necessary to ensure that the gas generated in the combustion chamber 60 passes through the filter 90. The filter 90 is disposed at a distance from the peripheral wall portion 22 of the upper shell 20 that constitutes a part of the peripheral wall portion of the housing so that a gap 28 of a predetermined size is formed between the filter 90 and the peripheral wall portion 22. The filter 90 may be, for example, a cylindrical filter formed in a shape similar to the cross-sectional shape of the peripheral wall portion 22, or may be of any shape as long as it is formed in a cylindrical shape so as to surround the gas generating agent 61.

[0032] A plurality of gas outlets 23 are provided in the curved surface portion 22a of the peripheral wall portion 22 of the upper shell 20 facing the filter 90. These gas outlets 23 are for directing gas that has passed through the filter 90 to the outside of the housing. Note that no gas outlets or flanges are formed in the flat surface portion 22b.

[0033] Additionally, a metal sealing tape 24 is attached to the inner peripheral surface of the peripheral wall portion 22 of the upper shell 20 as a sealing member to close the plurality of gas ejection ports 23. As this sealing tape 24, an aluminum foil with an adhesive member applied to one side can be suitably used, and the sealing tape 24 ensures the airtightness of the combustion chamber 60.

[0034] As explained above, gas generator 100 in the first embodiment of the present invention described above comprises a short, approximately semi-cylindrical housing including lower shell 10 having curved portion 12a with a semicircular cross section and flat portion 12b formed opposite curved portion 12a, and upper shell 20 having curved portion 22a with a semicircular cross section and flat portion 22b formed opposite curved portion 22a.

[0035] As shown in Fig. 1, a compact dual inflator can be configured by arranging two gas generators 100 adjacent to each other so that flat surfaces 12b, 22b face each other. That is to say, when gas generator 100 is assembled into a device (for example, an airbag device) that requires two gas generators 100, the effect is that the space within the device can be used more efficiently than before. As a result, it is possible to contribute not only to the miniaturization of gas generator 100 itself, but also to the miniaturization of the device into which it is assembled, which in turn can contribute to a reduction in the transportation costs of each product.

[0036] Furthermore, the configuration of the two gas generators 100 shown in FIG. 1 is simpler in structure and easier to assemble than the configuration of a conventional dual inflator.

[0037] Furthermore, in the case of a dual inflator using two gas generators 100 with different outputs, if gas generators 100 with three different outputs are prepared in advance, then it is possible to easily configure dual inflators with nine different combinations.

[0038] In addition, since it can be used as a single gas generator 100, it can be used not only as a dual inflator but also as a simple single inflator, and can be used appropriately according to the design of the device to which it is assembled.

[0039] Conventionally, it has been technically difficult to provide three or more gas generators, but based on the technical concept of the present invention, it is possible to combine three or more gas generators. This makes it possible to achieve ideal output characteristics of the airbag device. The same applies to the following modifications and embodiments.

[0040] <Modification of the first embodiment> Hereinafter, a gas generator 200 according to a modified example of the first embodiment of the present invention will be described with reference to Fig. 4. Note that in this embodiment, explanations of parts having the same reference numerals as the first embodiment down to the last two digits may be omitted if they are similar to the parts in the first embodiment. Furthermore, explanations and illustrations of parts not particularly explained in this embodiment may also be omitted if they are similar to the first embodiment.

[0041] Gas generator 200 differs from gas generator 100 mainly in that it is provided with a semicircular flange portion 125 that follows the shape of side wall portion 122. Although not shown, a plurality of gas outlets are provided in curved surface portion 122a, and no gas outlets are provided in flat surface portion 122b. In addition, no flange portion is provided on flat surface portion 122b.

[0042] As shown in Fig. 4, a compact dual inflator can be configured by arranging two gas generators 200 adjacent to each other so that the flat surface portions 22b face each other. That is, according to the gas generator 200, the same effects as those of the first embodiment can be achieved.

[0043] Second Embodiment A gas generator 300 according to a second embodiment of the present invention will now be described with reference to Fig. 5. Note that in this embodiment, explanations of parts having the same reference numerals as those in the first embodiment down to the last two digits may be omitted if they are similar to parts in the first embodiment. Furthermore, explanations and illustrations of parts not particularly explained in this embodiment may also be omitted if they are similar to those in the first embodiment.

[0044] Gas generator 300 differs from gas generator 100 mainly in that the shape of the housing is a substantially rectangular parallelepiped.

[0045] Gas generator 300 comprises a rectangular tubular upper shell 220 having a rectangular top plate portion 221, rectangular flat plate portions 222a, 222b, 222c, and 222d, and a pair of flange portions 225 extending from each of 222b and 222c, and a rectangular tubular lower shell having a rectangular bottom plate portion (not shown) and four rectangular side portions (not shown). Although not shown, a plurality of gas outlets are provided in flat plate portions 222a, 222b, and 222c, but no gas outlet is provided in flat plate portion 222d. Furthermore, no flange portions are provided on flat plate portion 222a or flat plate portion 222d.

[0046] As shown in Fig. 5, it is possible to configure a compact dual inflator by arranging two gas generators 300 adjacent to each other so that the flat surface portions 222d of the gas generators 300 face each other. That is, according to the gas generator 300, it is possible to achieve the same effects as those of the first embodiment.

[0047] Here, as a modified example of the gas generator 300, the housing may be formed into a substantially cubic shape instead of a substantially rectangular parallelepiped shape.

[0048] Third Embodiment Hereinafter, a gas generator 400 according to a third embodiment of the present invention will be described with reference to Fig. 6. Note that in this embodiment, explanations of parts having the same reference numerals as those in the first embodiment down to the last two digits may be omitted if they are similar to parts in the first embodiment. Furthermore, explanations and illustrations of parts not particularly described in this embodiment may also be omitted if they are similar to those in the first embodiment.

[0049] Gas generator 400 differs from gas generator 100 mainly in that the shape of the housing is a hollow, approximately triangular prism, and that flange portion 325 is formed in a generally L-shape.

[0050] Gas generator 400 comprises a triangular tubular upper shell 220 having a triangular top plate portion 321, quadrangular flat plate portions 322a, 322b, and 322c, and a substantially L-shaped flange portion 325 extending from 322a and 322b, and a triangular tubular lower shell (not shown) having a triangular bottom plate portion (not shown) and three quadrangular side portions (not shown). Although not shown, a plurality of gas outlets are provided in flat plate portions 322a and 322b, and no gas outlet is provided in flat plate portion 322c. Furthermore, no flange portion is provided on 322c.

[0051] 6, it is possible to configure a compact dual inflator by arranging two gas generators 400 adjacent to each other so that the flat surface portions 322c of the two gas generators 400 face each other. That is, according to the gas generator 400, it is possible to achieve the same effects as those of the first embodiment.

[0052] <Modification of the third embodiment> Hereinafter, with reference to Fig. 7, a gas generator 500 according to a modified example of the third embodiment of the present invention will be described. Note that in this embodiment, explanations of parts having the same reference numerals as the first embodiment down to the last two digits may be omitted if they are similar to the parts in the first embodiment. Furthermore, explanations and illustrations of parts that are not particularly explained in this embodiment may also be omitted if they are similar to the first embodiment.

[0053] Gas generator 500 differs from gas generator 400 of the third embodiment in that two flange portions 425 are formed so as to protrude from flat portions 422a, 422b, respectively, and in that the position at which through hole 425a is formed is different.

[0054] 6, it is possible to configure a compact dual inflator by arranging two gas generators 500 adjacent to each other so that the flat surface portions 422c of the two gas generators 500 face each other. That is, according to the gas generator 500, it is possible to achieve the same effects as those of the third embodiment.

[0055] Although the embodiments of the present invention have been described above, they are merely illustrative examples and do not limit the present invention, and the specific configurations and the like can be appropriately modified in design. Furthermore, the actions and effects described in the embodiments of the invention are merely a list of the most preferable actions and effects resulting from the present invention, and the actions and effects of the present invention are not limited to those described in the embodiments of the present invention.

[0056] In the above-described embodiment and the like, a configuration has been shown in which the side surface of the housing is flat so as to have a shape that follows the shape of the housing of an adjacent gas generator, but this is not limited to this. For example, at least a portion of the side surface of the housing may be formed so as to have a shape that follows the shape of the interior of a target device that is adjacent to at least a portion of the side surface of the housing (for example, the external shape of another gas generator assembled within the target device, the internal shape of the target device, etc.). In other words, at least a portion of the housing may be formed not only to have a flat shape, but also to have a shape that follows the shape of a device outside the housing, such as a curved surface, a surface with a wave-shaped, stepped, or zigzag (approximately Z-shaped) cross section, or a complex, intricate shape.

[0057] Furthermore, when two or more gas generators according to the present invention are assembled into a target device, etc., they do not necessarily need to be arranged symmetrically or adjacent to each other. Furthermore, when assembling a gas generator according to the present invention into a target device, etc., there is no need to use two or more of the same gas generators, and gas generators having different housing shapes may be used in appropriate combination. [Explanation of symbols]

[0058] 10 Lower side shell 11 Bottom plate part 12, 22, 122, 222, 322, 422 Peripheral wall section 12a, 22a, 122a curved section 12b, 22b, 122b, 222a, 222b, 222c, 222d, 322a, 322b, 322c, 422a, 422b, 422c Plane section 13 Projected cylinder part 15 Opening 20, 120, 220, 320, 420 Upper side shell 21, 121, 221, 321, 421 Top plate 23 Gas outlet 24 Sealing tape 25, 125, 225, 325, 425 flange 25a, 125a, 225a, 325a, 425a through hole 28 Gap 30 Holding part 40 Igniter 41 Ignition part 42 terminal pins 50 Cup-shaped member 59 Transfer Charge 60 Combustion chamber 61 Gas Generator 70 Lower support member 80 Upper support member 85 Cushioning material 90 filters 100, 200, 300, 400, 500 Gas Generator

Claims

1. A cylindrical housing; a gas generating agent contained in the housing and configured to generate gas by combustion; an igniter capable of igniting and burning the gas generating agent; a filter provided around the housing in a circumferential direction so as to surround the gas generating agent, A gas generator characterized in that at least a part of a side surface of the housing is formed into a shape that follows the shape of the interior of a target device when the gas generator is assembled into the target device.

2. 2. The gas generator according to claim 1, wherein the portion having a shape that conforms to the shape of the device to be assembled is a flat surface or a surface having a wave-shaped, stepped or zigzag cross section.

3. 2. The gas generator according to claim 1, wherein no gas outlet is provided in the portion having a shape that conforms to the shape of the interior of the device to be assembled.

4. 2. The gas generator according to claim 1, wherein a flange portion used when assembling the gas generator into the apparatus to be assembled is not provided in the portion having a shape that conforms to the shape inside the apparatus to be assembled.

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