Gas generator

Abstract

To obtain a gas generator that can suppress deterioration due to moisture absorption of a gas generating agent inside a housing, and that can reduce the number of components and can be easily assembled.SOLUTION: A gas generator 100 includes: a housing 10; a holder 20 attached to one open end of the housing 10; a closing member 12 which is attached to the other end part of the housing 10 so as to close the other open end of the housing 10; and a side cover 51 which covers a part of the holder 20 and a part of an igniter 50. The side cover 51 has an end which is welded and fixed to the housing 10 and the holder 20 in the state pinched between an inner wall of the housing 10 and a side part 22 at a welding fixed part 62. The welding fixed part 62 is annularly formed along a circumferential direction of the housing 10 by performing welding along the circumferential direction of the housing 10 from an exterior of the housing 10 at a position corresponding to the side part 22 covered by the side cover 51.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a gas generator incorporated in an airbag device as an occupant protection device mounted on an automobile or the like, and more particularly to a so-called cylinder-type gas generator having an elongated cylindrical outer shape. [Background technology]

[0002] In a cylinder-type gas generator, the long cylindrical housing is generally configured so that at least one end thereof is closed by a holder having an ignition portion (see, for example, Patent Document 1 below). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 6,149,193 [Patent Document 2] U.S. Patent No. 9,455,519 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned Patent Document 1, there are many paths through which air passes between the internal space in the housing filled with the gas generating agent and the outside of the housing, which raises concerns about deterioration of the gas generating agent in the housing due to moisture absorption. Furthermore, in the above-mentioned Patent Document 2, an O-ring, a sealant, or the like is used to suppress moisture absorption by the gas generating agent in the housing. However, a component such as an O-ring or a sealant often needs to be provided for each of the above-mentioned paths through which air passes, which increases the number of parts. This increase in the number of parts creates the problem of making the gas generator assembly process more complicated.

[0005] Therefore, an object of the present invention is to provide a gas generator that can suppress deterioration of the gas generating agent in the housing due to moisture absorption more than conventional gas generators, can reduce the number of parts, and is easy to assemble. [Means for solving the problem]

[0006] (1) A gas generator of the present invention comprises a long cylindrical housing that includes therein a working gas generation chamber in which working gas is generated by combustion of a gas generating agent, and a filter chamber that houses a filter through which the working gas generated in the working gas generation chamber passes; gas generant ignition means that contains an ignition charge and is arranged at one axial end of the housing and is capable of igniting and burning the gas generant in the working gas generation chamber; a substantially cylindrical first forming portion that has a holding portion that holds the gas generant ignition means on the inner side of the housing; and a holding portion that is integral with the first forming portion on the opposite side to the working gas generation chamber side of the first forming portion and is arranged on the opposite side to the holding position of the gas generant ignition means for applying electricity to the gas generant ignition means. a holder having a substantially cylindrical second forming portion with a fitting portion into which a connector can be fitted, and fixed to one axial end of the housing; and a side cover which is a bottomed cylindrical member having a cylindrical portion and covers at least a portion of the gas generant ignition means on the working gas generation chamber side and at least a part of a side surface of the first forming portion, and is provided so that the cylindrical portion is sandwiched between an inner wall of the housing and the side surface of the first forming portion, and at least a part of a position of the housing corresponding to the side surface of the first forming portion covered by the side cover, a part of the side cover corresponding to said part, and a part of the side surface of the holder corresponding to said part are welded annularly along the circumferential direction of the housing. The holder-side end of the housing and the holder-side end of the side cover are arranged to be aligned in the radial direction, the outer diameter of the first formed portion is smaller than the outer diameter of the second formed portion, a connecting portion that connects the first formed portion and the second formed portion is provided between the first formed portion and the second formed portion, and the welded and fixed portions are at least the holder-side end of the housing, the holder-side end of the side cover, and the connecting portion. It is characterized by:

[0008] ( 2 ) (1) above ofIn the gas generator, it is preferable that the end of the side cover on the working gas generating chamber side is formed with a bottom surface portion and a tapered portion connected to the bottom surface portion and narrowing in diameter toward the other end of the housing in the axial direction.

[0009] According to the above-mentioned configurations, it is possible to provide a gas generator that can suppress moisture absorption by the gas generating agent in the housing more effectively than ever before and that is easy to assemble. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram showing an internal structure of a gas generator according to an embodiment of the present invention, with a portion shown in cross section. [Figure 2] FIG. 2 is an enlarged cross-sectional view of a portion of FIG. [Figure 3] FIG. 3 is a view showing the state of FIG. 2 before being fixed by welding. [Figure 4] FIG. 2 is a cross-sectional view showing an example of the side cover of FIG. 1. [Figure 5] FIG. 2 is a cross-sectional view showing an example of the side cover of FIG. 1. [Figure 6] FIG. 2 is a cross-sectional view showing an example of the side cover of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, with reference to Figs. 1 to 3, the internal structure of a cylinder-type gas generator according to an embodiment of the present invention will be described.

[0012] (Configuration of gas generator 100) As shown in FIG. 1, gas generator 100 has a long, generally cylindrical outer shape, and includes housing 10, holder 20 attached to one open end of housing 10, closing member 12 attached to the other end of housing 10 so as to close the other open end of housing 10, and side cover 51 covering part of holder 20 and part of igniter 50.

[0013] Housing 10 consists of a long, cylindrical member having openings at both axial ends. Closure member 12 consists of a disk-shaped member having a predetermined thickness, and has a welded fixing portion 60 on its circumferential surface. This welded fixing portion 60 is annularly welded to the outer periphery of one end of housing 10, and is thereby formed in an annular shape along the circumferential direction on the circumferential surface of closing member 12. Also, gas outlets 11 are provided in the peripheral wall of housing 10 near the end on the side where closing member 12 is attached. These gas outlets 11 are holes for ejecting gas generated inside gas generator 100 to the outside, and a plurality of gas outlets 11 are provided along the circumferential and axial directions of housing 10.

[0014] The blocking member 12 is made of a metal such as stainless steel, iron steel, aluminum alloy, or stainless alloy, and is a substantially disk-shaped member having a predetermined thickness.

[0015] 1 and 2, holder 20 has a first forming portion 20a having a holding portion 26 that holds igniter 50 inside housing 10, and a second forming portion 20b having a fitting portion 21 that can be fitted with a connector (not shown) for supplying electricity to igniter 50, on the opposite side to the holding position of igniter 50, and is fixed to one end of housing 10 on the ignition chamber 19 side. Holder 20 is also a substantially cylindrical member made of metal such as stainless steel, iron steel, aluminum alloy, or stainless alloy.

[0016] 3, before welding, the first forming portion 20a has a side surface portion 22 for sandwiching the igniter 50-side end of the side cover 51 together with the inner wall of the housing 10, and a positioning portion 23 used for positioning the igniter 50-side end of the housing 10 and the igniter 50-side end of the side cover 51 before welding. The side surface portion 22 is formed to have an outer diameter smaller than that of the second forming portion 20b. Before welding, the positioning portion 23 is also a portion that forms a staircase shape together with the side surface portion 22 and the side surface portion 24 of the second forming portion 20b. The second forming portion 20b is integrally provided with the first forming portion 20a on the side opposite the working gas generation chamber 17 side of the first forming portion 20a.

[0017] 1 to 3, the side cover 51 includes a bottom 51a, a tapered portion 51b having one end connected and fixed to the bottom 51a, a first cylindrical portion 51c having one end connected and fixed to the other end of the tapered portion 51b, an igniter contact portion 51d having one end connected and fixed to the other end of the first cylindrical portion 51c, and a second cylindrical portion 51e having one end connected and fixed to the other end of the igniter contact portion 51d. This side cover 51 is a directional member in which the bottom 51a breaks upon activation, and the tapered portion 51b concentrates the flame emitted from the tip of the igniter 50 and directs the flame toward the working gas generation chamber 17. The bottom 51a may be formed with a weakened portion (such as a recessed portion provided on the outer surface) to make the bottom 51a more likely to break upon activation.

[0018] Furthermore, the diameter of bottom portion 51a and the angle of tapered portion 51b with respect to the axial direction of first cylindrical portion 51c can be appropriately changed in consideration of the output or size of igniter 50, the material used for side cover 51 (stainless steel, iron steel, aluminum alloy, stainless steel alloy, etc.), etc., so that bottom portion 51a breaks upon activation. For example, examples of the diameter of bottom portion 51a and the angle of tapered portion 51b with respect to the axial direction of first cylindrical portion 51c are shown in Figures 4 to 6. Below, Figures 4 to 6 will be described, but since reference numerals with the same last two digits are similar, their description may be omitted. Furthermore, since parts not particularly described are similar to those in this embodiment, their description may be omitted.

[0019] 4, the angle of tapered portion 151b with respect to the axial direction of first cylindrical portion 151c is 25°, and the diameter (ΦD) of bottom portion 151a can be determined based on various factors such as the angle of tapered portion 151b with respect to the axial direction of first cylindrical portion 151c, the diameter of first cylindrical portion 151c, the distance from first cylindrical portion 151c to bottom portion 151a, the output or size of the igniter, and the material used for side cover 151. For example, the diameter (ΦD) of bottom portion 151a may be formed to be any size between 4 mm and 5 mm.

[0020] 5, the angle of tapered portion 251b with respect to the axial direction of first cylindrical portion 251c is 45°, and in Fig. 6, the angle of tapered portion 351b with respect to the axial direction of first cylindrical portion 351c is 60°. As in the case of side cover 151 shown in Fig. 4, the diameters of bottoms 251a, 351a of side covers 251, 351 shown in Figs. 5 and 6 can be determined based on various factors, such as the angle of the tapered portion with respect to the axial direction of the first cylindrical portion, the diameter of the first cylindrical portion, the distance from the first cylindrical portion to the bottom, the output or size of the igniter, and the material used for the side cover.

[0021] 4 to 6, the diameter of bottom portion 51a may be kept constant, and the angle of tapered portion 51b relative to the axial direction of first cylindrical portion 51c may be changed as appropriate depending on various factors, such as the output of igniter 50 and the material used for side cover 51.

[0022] The tapered portion 51b is a portion formed so as to decrease in diameter from the working gas generation chamber 17 side toward the filter chamber 18 side (the other end side in the axial direction of the housing 10).

[0023] The first cylindrical portion 51c is a directional portion that can direct the flame toward the working gas generation chamber 17, and is a cylindrical portion having an inner diameter that is the same as or approximately the same as the outer diameter of the squib cup 50a of the igniter 50.

[0024] As shown in FIGS. 1 and 2, the igniter contact portion 51d is a portion that comes into contact with the igniter 50 and sandwiches and fixes the igniter 50 together with the holder 20.

[0025] As shown in FIGS. 1 and 2, the second cylindrical portion 51e is a cylindrical portion sandwiched between the inner wall and the side surface portion 22 of the housing 10, and its end is welded to the housing 10 and the holder 20 at a welded-fixing portion 62. This welded-fixing portion 62 is formed in an annular shape along the circumferential direction of the housing 10, as shown in FIG. 2, by welding a portion 62A along the circumferential direction of the housing 10 from the state shown in FIG. 3 at a position corresponding to the side surface portion 22 covered by the side cover 51 (in this embodiment, the end of the side surface portion 22 on the holder 20 side). This welded-fixing portion 62 restricts the air passage between the inside and outside of the working gas generation chamber 17 more than in the past. Note that, as shown in FIG. 3, the end of the second cylindrical portion 51e is the portion that abuts against the positioning portion 23 before being welded.

[0026] 1, the igniter 50 serving as means for igniting the gas generating agent 30 is disposed at one axial end of the housing 10 (i.e., the portion closer to the holder 20). The igniter 50 and the holder 20 for fixing the igniter 50 function as ignition means for generating a flame for burning the granular gas generating agent 30, which will be described later.

[0027] 1 and 2, igniter 50 is inserted into holding portion 26 of first forming portion 20a and fixed to holder 20 by side cover 51. More specifically, as described above, the ends of side cover 51 are welded and fixed to housing 10 and holder 20, so that igniter 50 is sandwiched and fixed between igniter abutment portion 51d of side cover 51 and holder 20 (particularly holding portion 26).

[0028] More specifically, the igniter 50 comprises a base frame for inserting and holding a pair of terminal pins 52, and a squib cup 50a attached to the base frame, with a resistor (bridge wire) attached to connect the tips of the terminal pins 52 inserted into the squib cup 50a, and an ignition charge filled in the squib cup 50a so as to surround or come into contact with the resistor. Nichrome wire or the like is generally used as the resistor, and ZPP (zirconium-potassium perchlorate), ZWPP (zirconium-tungsten-potassium perchlorate), lead tricinate, or the like is generally used as the ignition charge. The squib cup 50a may be filled with not only the ignition charge but also a transfer charge, and examples of transfer charges that can be placed together with the ignition charge include a composition made of a metal / oxidizer, such as boron / potassium nitrate, a composition made of titanium hydride / potassium perchlorate, or a composition made of boron / 5-aminotetrazole / potassium nitrate / molybdenum trioxide. The squib cup is generally made of metal or resin.

[0029] When a collision is detected, a predetermined amount of current flows through the resistor via the terminal pin 52. This current flow through the resistor generates Joule heat, which causes the ignition charge to begin burning. The high-temperature flame generated by the combustion ruptures the squib cup 50a containing the ignition charge. If nichrome wire is used for the resistor, the time from when the current flows through the resistor to when the igniter 50 is activated is less than 2 milliseconds.

[0030] 1, the internal space of the housing 10 is provided with a working gas generation chamber 17 in which a gas generating agent 30 is loaded, a filter chamber 18 in which a filter 40 is housed, and an ignition chamber 19 in which a coil spring 35 is housed. The working gas generation chamber 17 and the filter chamber 18 are separated by a partition member 31.

[0031] On the working gas generating chamber 17 side of the partition member 31 described later, an AI agent 32 having an auto-ignition (AI) function that automatically ignites without the activation of an igniter 50, and a gas generating agent 30 are disposed.

[0032] As shown in FIG. 1 , the gas generant 30 is disposed between the coil spring 35 and the cover member 33. The gas generant 30 is an integrally molded product that is ignited by a flame generated by ignition using an igniter 50 and burns to generate gas. The gas generant 30 is generally formed as a molded product containing a fuel, an oxidizer, and an additive. Examples of fuels that can be used include triazole derivatives, tetrazole derivatives, guanidine derivatives, azodicarbonamide derivatives, hydrazine derivatives, and combinations thereof. Specifically, nitroguanidine, guanidine nitrate, cyanoguanidine, and 5-aminotetrazole are preferred. Examples of oxidizers that can be used include basic metal hydroxides such as basic copper nitrate and 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. Examples of nitrates that can be used include sodium nitrate and potassium nitrate. Examples of additives include binders, slag formers, and combustion modifiers. Suitable binders include organic binders such as cellulose derivatives (e.g., hydroxypropylene methyl cellulose), metal salts of carboxymethyl cellulose, and stearates, as well as inorganic binders (e.g., synthetic hydroxytalcite and acid clay). Suitable slag formers include silicon nitride, silica, and acid clay. Suitable combustion modifiers include metal oxides, ferrosilicon, activated carbon, and graphite.

[0033] 1, the coil spring 35 is formed in the ignition chamber 19 by being wound in a spiral shape along the inner wall of the housing 10 that faces the outer periphery of the side cover 51 so as to resemble a cylindrical shape overall in appearance. One end of the coil spring 35 abuts against the outer surface of the side cover 51, and the other end abuts against the gas generating agent 30, so as to apply an elastic force to the gas generating agent 30. Due to this bias, the gas generating agent 30 is fixed in place within the housing 10 by being sandwiched between the coil spring 35 and the cover member 33.

[0034] The AI ​​agent 32 having AI functionality automatically ignites at a lower temperature than the gas generating agent 30, and therefore, in the event of a fire or the like occurring in a vehicle or the like equipped with an airbag system or the like incorporating the gas generator 100, it is possible to prevent the gas generator 100 from malfunctioning due to external heating. This makes it possible to further prevent the gas generating agent 30 from burning before the AI ​​agent 32 automatically ignites in the event of a fire or the like occurring in a vehicle or the like equipped with an airbag system or the like incorporating the gas generator 100. The cover member 33 is a disc-shaped member made of a metal or alloy, and may be of any type as long as it separates the AI ​​agent 32 from the gas generating agent 30 to prevent them from coming into contact with each other, and may, for example, have a plurality of holes or no holes.

[0035] 1 and 2, the partition member 31 is generally bowl-shaped, and although not shown, a score line (not shown) is provided near the center of the bottom so that it can easily break when a predetermined pressure is applied. The side surface of the partition member 31 is welded to the housing 10 in a circular shape in the circumferential direction at a welded fixing portion 61.

[0036] As shown in FIG. 1 , the filter chamber 18 communicates with the outside through a gas outlet 11 provided on the peripheral wall of the housing 10. The filter chamber 18 also houses a filter 40, which is a cylindrical member with a substantially cylindrical space 40a at its center. The use of such a cylindrical filter 40 reduces the flow resistance of the working gas flowing through the filter chamber 18 during operation, enabling efficient gas flow. The filter 40 may be made of wire material, such as stainless steel or steel, or a mesh material wound or pressed. Specifically, a knitted wire mesh, a plain-woven wire mesh, or a crimped-woven metal wire assembly may be used. The filter 40 functions as a cooling means for cooling the gas generated in the working gas generation chamber 17 by removing the high-temperature heat of the gas as it passes through the filter 40, and also functions as a removal means for removing slag and other contaminants contained in the gas. Here, as a modified example of the filter 40, a filter having a labyrinth flow path formed by combining roughly cylindrical or cone-shaped metal parts may be used. This allows the path of the working gas to be changed in various directions, thereby enabling cooling of the gas and removal of slag.

[0037] A female connector (not shown) is attached to second forming portion 20b. This female connector is a portion to which a male connector of a harness that transmits a signal from collision detection means that is provided separately from gas generator 100 is connected. A retainer (not shown) is attached to the female connector. This retainer is attached to prevent malfunction of cylindrical gas generator 100 due to electrostatic discharge or the like when gas generator 100 is transported, and at the stage of assembly into an airbag device, the male connector of the harness is inserted into the female connector, thereby releasing the male connector from contact with terminal pin 52.

[0038] Next, an operation during activation of gas generator 100 described above will be described. When a vehicle equipped with an airbag device incorporating gas generator 100 in the present embodiment collides, the collision is detected by collision detection means separately provided in the vehicle, and igniter 50 is activated based on this detection. When igniter 50 is activated, the pressure inside igniter 50 increases due to combustion of the ignition charge, causing the tip of squib cup 50a of igniter 50 to rupture, and flames flow from the tip of squib cup 50a of igniter 50 into the interior of side cover 51.

[0039] The flames flowing in in this manner are concentrated by the tapered portion 51b of the side cover 51, causing the bottom portion 51a of the side cover 51 to split, and the gas generating agent 30 in the container 34 to ignite and burn, generating a large amount of gas. At this time, because the flames are concentrated, they are more likely to eject toward the back side of the working gas generation chamber 17 (toward the filter chamber 18). This combustion of the gas generating agent 30 increases the pressure within the working gas generation chamber 17, causing the partition member 31 to split, and the gas flows into the filter chamber 18. The folded portion of the approximately bowl-shaped partition member 31 prevents gas from flowing between the filter 40 and the inner wall of the housing 10, preventing the gas from being released to the outside without passing through the filter 40. In this way, the gas flowing into the filter chamber 18 is cooled to a predetermined temperature via the filter 40. A large amount of the cooled gas is ejected from the gas ejection port 11 to the outside of the gas generator 100. The gas ejected from the gas ejection port 11 is guided into the inside of the airbag to inflate and deploy the airbag.

[0040] (Main features of the gas generator 100) According to the present embodiment, the formation of welded fixing portion 62, which is easy to work with, limits the air passage path between the inside of working gas generation chamber 17 and the outside more than ever before. Therefore, it is possible to provide gas generator 100 that is easier to assemble and that can suppress deterioration of gas generating agent 30 in the housing due to moisture absorption more than ever before.

[0041] Furthermore, since components such as O-rings or sealing materials are not required, the number of parts can be reduced compared to conventional systems.

[0042] Although the embodiments of the present invention have been described above with reference to the drawings, it should be understood that the specific configurations are not limited to these embodiments. The scope of the present invention is defined by the claims rather than the description of the above embodiments, and further includes all modifications within the meaning and scope of the claims.

[0043] In the above embodiment, the vicinity of the end of side cover 51 is welded to form welded fixing portion 62, but this is not limiting. For example, an intermediate portion of second cylindrical portion 51e of side cover 51 may be welded to side surface portion 22 of housing 10 and holder 20.

[0044] Furthermore, second cylindrical portion 51e of side cover 51 does not have to be long enough to come into contact with positioning portion 23. In this case, however, it is necessary that the end or middle portion of second cylindrical portion 51e of side cover 51 is reliably welded and fixed to housing 10 and side portion 22 of holder 20. [Explanation of symbols]

[0045] 10. Housing 11 Gas outlet 12 Closure member 17 Working gas generation chamber 18 Filter chamber 19 Ignition chamber 20 Holder 20a 1st forming part 20b Second forming part 21 Fitting part 22 Side part 23 Positioning part 24 Side part 26 Holding part 30 Gas Generator 31 Partition member 32 AI agents 33 Cover member 34 container 35 coil spring 40 filters 40a space 50 igniter 50a squib cup 51, 151, 251, 351 Side cover 51a, 151a, 251a, 351a bottom 51b, 151b, 251b, 351b tapered section 51c, 151c, 251c, 351c First cylindrical portion 51d, 151d, 251d, 351d Ignition contact part 51e, 151e, 251e, 351e Second cylindrical portion 52 terminal pins 60, 61, 62 Welded fixing parts 100 Gas Generator

Claims

1. a long cylindrical housing that includes therein a working gas generation chamber in which a working gas is generated by combustion of a gas generating agent, and a filter chamber that houses a filter through which the working gas generated in the working gas generation chamber passes; a gas generating agent ignition means containing an ignition charge, disposed at one end of the housing in the axial direction, and capable of igniting and burning the gas generating agent in the working gas generation chamber; a holder fixed to one axial end of the housing, the holder comprising: a substantially cylindrical first forming portion having a holding portion that holds the gas generant ignition means inside the housing; and a substantially cylindrical second forming portion that is integrally formed with the first forming portion on the side opposite to the working gas generation chamber side of the first forming portion, the second forming portion having a fitting portion into which a connector for energizing the gas generant ignition means can be fitted, on the side opposite to the holding position of the gas generant ignition means; a side cover, which is a bottomed cylindrical member having a cylindrical portion, covering at least a portion of the gas generant ignition means on the working gas generation chamber side and at least a part of a side surface of the first forming portion, and is provided so that the cylindrical portion is sandwiched between an inner wall of the housing and the side surface of the first forming portion; Equipped with at least a portion of the housing at a position corresponding to a side surface of the first forming portion covered by the side cover, a portion of the side cover corresponding to the portion, and a portion of the side surface of the holder corresponding to the portion are welded and fixed in an annular shape along the circumferential direction of the housing, an end of the housing on the holder side and an end of the side cover on the holder side are arranged to be aligned in a radial direction, an outer diameter of the first forming portion is smaller than an outer diameter of the second forming portion, and a connecting portion that connects the first forming portion and the second forming portion is provided between the first forming portion and the second forming portion, A gas generator characterized in that the welded and fixed portions are at least the end of the housing on the holder side, the end of the side cover on the holder side, and the connecting portion.

2. The end of the side cover on the working gas generation chamber side is provided with: A bottom portion; a tapered portion connected to the bottom surface portion and tapering toward the other end of the housing in the axial direction; 2. The gas generator according to claim 1, wherein:

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