Gas generator

Abstract

To provide a gas generator reduced in size and weight and facilitating assembly work.SOLUTION: A gas generator 1A comprises at least: a housing where an inner space is partitioned into a gas generating agent storage chamber S1 and a filter chamber; a gas generating agent 60 stored in the gas generating agent storage chamber S1; an autoignition agent 61; and a coil spring 70. The coil spring 70 has: a first pressing part 72a located on the side of the gas generating agent 60; a second pressing part 72b located on the side of the autoignition agent 61; and a spring part 71 located between them. The first pressing part 72a and the second pressing part 72b are so constituted as to form a tabular shape as a whole. As viewed along an axial direction, the second pressing part 72b has a larger outer shape than the autoignition agent 61, and the spring part 71 includes a constricted part 73 having a smaller outer shape than the first pressing part 72a and the second pressing part 72b.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a gas generator to be incorporated into an airbag device as an occupant protection device equipped in an automobile or the like, and particularly to a so-called cylinder-type gas generator having an elongated cylindrical outer shape that is suitably incorporated into a side airbag device 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] The gas generator is incorporated into this airbag device. When a vehicle crashes, the control unit energizes the igniter, which then generates a flame that burns the gas generating agent, instantly generating a large amount of gas, which inflates and deploys the airbag.

[0004] There are gas generators of various configurations based on specifications such as the installation position relative to a vehicle, etc., and gas output. One of these is what is called a cylinder-type gas generator. A cylinder-type gas generator has an elongated cylindrical outer shape and is suitably incorporated into a side airbag device, a curtain airbag device, a knee airbag device, a seat cushion airbag device, etc.

[0005] Typically, in a cylinder-type gas generator, an igniter is attached to one axial end of a housing, and a gas generating agent storage chamber containing a plurality of granular gas generating agents is provided on the one end side.

[0006] Furthermore, in recent years, cylinder-type gas generators have become known in which an auto-ignition agent is further accommodated in the gas generating agent storage chamber. The auto-ignition agent ignites automatically without the activation of an igniter, thereby preventing the cylinder-type gas generator from malfunctioning due to external heating in the unlikely event of a fire or other incident occurring in a vehicle or the like equipped with an airbag device incorporating a cylinder-type gas generator.

[0007] An example of a document disclosing a cylinder-shaped gas generator having the above configuration is Japanese Patent Application Laid-Open No. 2022-102514 (Patent Document 1). In the cylinder-shaped gas generator disclosed in Patent Document 1, the autoignition agent and the gas generating agent are elastically biased by a coil spring interposed between them, thereby fixing them inside the gas generating agent storage chamber. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2022-102514 Summary of the Invention [Problem to be solved by the invention]

[0009] Here, in the cylinder-type gas generator in which safety is improved by providing an auto-ignition agent as described above, important issues are making it smaller and lighter and further facilitating the assembly work.

[0010] Therefore, the present invention has been made in consideration of the above-mentioned problems, and has as its object to provide a gas generator that is small, lightweight, and easy to assemble. [Means for solving the problem]

[0011] A gas generator according to the present invention comprises a housing, a partition, a plurality of granular gas generating agents, an igniter for burning the gas generating agents, an auto-ignition agent that automatically ignites without activation of the igniter, and a coil spring. The housing has a cylindrical peripheral wall including a portion that defines a gas generating agent storage chamber and a portion that defines a filter chamber in which a filter is housed. The partition is located inside the housing and divides the interior space of the housing into the gas generating agent storage chamber and the filter chamber in the axial direction of the peripheral wall. The gas generating agent is housed in the gas generating agent storage chamber. The igniter is assembled to one end of the housing on the gas generating agent storage chamber side in the axial direction. The auto-ignition agent is housed in the gas generating agent storage chamber so as to contact a main surface of the partition facing the gas generating agent storage chamber. The coil spring is formed by winding a metal wire and is interposed in a compressed state between the autoignition agent and the gas generating agent. The coil spring has a first pressing portion located on the gas generating agent side, a second pressing portion located on the autoignition agent side, and a spring portion located between the first pressing portion and the second pressing portion. The first pressing portion is formed by routing one end of the metal wire so that the first pressing portion has a plate-like shape as a whole. The second pressing portion is formed by routing the other end of the metal wire so that the second pressing portion has a plate-like shape as a whole. The gas generating agent is fixed inside the gas generating agent storage chamber by being urged toward the igniter side by the spring portion via the first pressing portion. The autoignition agent is fixed inside the gas generating agent storage chamber by being urged toward the filter chamber side by the spring portion via the second pressing portion. When viewed along the axial direction, the second pressing portion has an outer shape larger than that of the autoignition agent. In the gas generator according to the present invention, when viewed along the axial direction, the spring portion includes a constricted portion whose outer shape is smaller than that of both the first pressing portion and the second pressing portion. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a gas generator that is small, lightweight, and easy to assemble. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic view of a cylinder-shaped gas generator according to an embodiment. [Figure 2] FIG. 2 is an enlarged view of the vicinity of the igniter shown in FIG. [Figure 3] FIG. 2 is an enlarged view of region III shown in FIG. [Figure 4] 2 is a schematic diagram of the coil spring shown in FIG. 1 in a state before being assembled to a cylinder-shaped gas generator. FIG. [Figure 5] 2 is a schematic view of the autoignition agent and the coil spring shown in FIG. 1 as viewed from the filter chamber side. FIG. [Figure 6] 10A and 10B are partially enlarged views for explaining examples of the arrangement and orientation of the autoignition agent. [Figure 7] FIG. 10 is a partially enlarged view of a cylinder-shaped gas generator according to a first modified example. [Figure 8] FIG. 10 is a partially enlarged view of a cylinder-shaped gas generator according to a second modified example. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The embodiments shown below exemplify the case where the present invention is applied to a cylinder-type gas generator incorporated in a side airbag device. In the embodiments shown below, the same or common parts are designated by the same reference numerals in the drawings, and their description will not be repeated.

[0015] (Embodiment) FIG. 1 is a schematic diagram of a cylinder-shaped gas generator according to an embodiment. FIG. 2 is an enlarged view of the vicinity of the igniter shown in FIG. 1. FIG. 3 is an enlarged view of region III shown in FIG. 1. FIG. 4(A) is a schematic front view of the coil spring shown in FIG. 1 before it is assembled to the cylinder-shaped gas generator, and FIGS. 4(B) and 4(C) are schematic side views of the coil spring. FIG. 5 is a schematic view of the auto-ignition agent and coil spring shown in FIG. 1, viewed from the filter chamber side. First, the configuration of cylinder-shaped gas generator 1A according to the present embodiment will be described with reference to FIGS. 1 to 5. In FIG. 5, a pattern is added to the auto-ignition agent to facilitate understanding.

[0016] As shown in Figures 1 to 3, cylinder-shaped gas generator 1A has a long, columnar outer shape. Cylinder-shaped gas generator 1A has a long, substantially cylindrical housing whose one and other axial ends are closed. The housing includes housing main body 10, holder 20, closing member 30, and partition member 50. The outer shell of the housing is defined by housing main body 10, holder 20, and closing member 30.

[0017] The housing main body 10, the holder 20, and the closing member 30 accommodate internal components such as an igniter 40, a plurality of granular gas generating agents 60 (hereinafter also referred to simply as "gas generating agents 60"), an auto-ignition agent 61, a coil spring 70, and a filter 80, and in addition, the above-mentioned partition member 50, which is also an internal component, is disposed within the housing. A gas generating agent storage chamber S1 and a filter chamber S2 are located within the housing. The gas generating agent storage chamber S1 accommodates the gas generating agent 60, the auto-ignition agent 61, and the coil spring 70, which are among the above-mentioned internal components. The filter chamber S2 accommodates the filter 80.

[0018] The housing main body 10 constitutes the peripheral wall portion 11 of the housing and is made of a long cylindrical member. The peripheral wall portion 11 has open ends on both axial ends. The peripheral wall portion 11 includes both a portion that defines the gas generating agent storage chamber S1 and a portion that defines the filter chamber S2.

[0019] The housing body 10 may be made of a metal member such as stainless steel, iron steel, aluminum alloy, or stainless alloy, or may be made of a press-formed product formed into a cylindrical shape by pressing a rolled steel plate such as SPCE.The housing body 10 may also be made of an electric resistance welded pipe such as STKM.

[0020] In particular, when the housing body 10 is constructed from a press-formed rolled steel plate or an electric resistance welded pipe, the housing body 10 can be formed more cheaply and easily than when metal components such as stainless steel or steel are used, and the weight can be significantly reduced.

[0021] The holder 20 and the closing member 30 are made of metal members such as stainless steel, iron steel, aluminum alloy, stainless alloy, or the like.

[0022] 1 and 2, holder 20 is made of a substantially cylindrical member having a through-hole 21 extending in a direction parallel to the axial direction of peripheral wall 11, and is assembled to peripheral wall 11 so as to close one of a pair of open ends of peripheral wall 11. In detail, holder 20 is fixed to peripheral wall 11 by joining holder 20 and peripheral wall 11 at or near their contact portions by, for example, welding, with a portion of holder 20 inserted into the open end of peripheral wall 11.

[0023] As a result, a weld 101 extending along the circumferential direction of the housing is provided at the axial end of the housing located on the open end side of the peripheral wall 11. The gap between the peripheral wall 11 and the holder 20 is filled with the weld 101. Therefore, the gap is sealed by the weld 101, making it possible to ensure airtightness in that portion. Note that electron beam welding, laser welding, resistance welding, or the like can be suitably used to weld the peripheral wall 11 and the holder 20 together.

[0024] The assembly structure of the holder 20 to the peripheral wall 11 is not limited to the above-described assembly structure, and other assembly structures may be adopted. In that case, airtightness between the peripheral wall 11 and the holder 20 can be ensured by providing an O-ring or the like at an appropriate position.

[0025] 1, the blocking member 30 is made of a substantially disk-shaped member and is assembled to the peripheral wall portion 11 so as to block the other of a pair of open ends of the peripheral wall portion 11. In detail, the blocking member 30 is inserted into the open end of the peripheral wall portion 11, with one axial end face of the blocking member 30 abutting against the filter 80, and a predetermined position of the peripheral wall portion 11 is reduced in diameter radially inward toward the other axial end face of the blocking member 30, thereby crimping and fixing the blocking member 30 to the peripheral wall portion 11. In this way, the other axial end of the housing is formed by the blocking member 30.

[0026] The crimping method is called eight-way crimping, which reduces the diameter of the peripheral wall 11 uniformly inward in the radial direction. This crimping method brings the peripheral wall 11 and the blocking member 30 into direct contact with each other, preventing gaps from forming between them.

[0027] The assembly structure of the closing member 30 to the peripheral wall portion 11 is not limited to the assembly structure described above, and other assembly structures may be adopted. Furthermore, the peripheral wall portion 11 and the closing member 30 may not be separate bodies, but may be configured as a single member having a cylindrical shape with a bottom.

[0028] 1 and 2, the igniter 40 is mounted to the housing by being supported by the holder 20. As a result, the igniter 40 is located on one axial end side of the peripheral wall portion 11 when viewed from the gas generating agent storage chamber S1. The igniter 40 is used to combust the gas generating agent 60, and is arranged so as to face the internal space of the housing.

[0029] The igniter 40 has an ignition section 41 and a pair of terminal pins 42. The ignition section 41 includes a squib cup. A resistor (bridge wire) is attached inside the squib cup so as to connect to the pair of terminal pins 42. The squib cup is filled with an ignition charge so as to surround or be in contact with the resistor. A transfer charge may be loaded inside the squib cup as needed.

[0030] Resistors typically include nichrome wire or alloys containing platinum and tungsten. Ignition charges typically include ZPP (zirconium-potassium perchlorate), ZWPP (zirconium-tungsten-potassium perchlorate), and lead tricinate. Transfer charges include metal powder / oxidizer compositions such as B / KNO3, B / NaNO3, and Sr(NO3)2, titanium hydride / potassium perchlorate, and B / 5-aminotetrazole / potassium nitrate / molybdenum trioxide.

[0031] When a collision is detected, a predetermined amount of current flows through the resistor via the terminal pin 42. This generates Joule heat in the resistor, causing the ignition charge to start burning. The high-temperature particles generated by the combustion split open 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 less than 2 milliseconds if the resistor uses nichrome wire.

[0032] Igniter 40 is fixed to holder 20 by crimping portion 22 provided on holder 20. More specifically, holder 20 has crimping portion 22 for crimping and fixing igniter 40 at an axial end portion facing the interior space of the housing. Igniter 40 is inserted into through portion 21 and is fixed against the wall portion that defines through portion 21, and then crimping portion 22 is crimped, whereby igniter 40 is clamped and fixed within holder 20.

[0033] As a result, igniter 40 is assembled to holder 20 so that ignition portion 41 is positioned to protrude toward the inside of the housing. Therefore, when igniter 40 is activated, the ignition charge is ignited, causing the squib cup to split, and the squib cup opens as a result of this splitting.

[0034] A seal member 43 made of an O-ring or the like is interposed between holder 20 and igniter 40. The gap between holder 20 and igniter 40 is filled with seal member 43, thereby sealing the gap. This configuration makes it possible to ensure airtightness in that portion. Note that the assembly structure of igniter 40 is not limited to the assembly structure using crimped portion 22 described above, and other assembly structures may be adopted.

[0035] A recess 23 is provided at the axial end of holder 20 that is exposed to the outside, continuing from the above-mentioned through-hole 21. Recess 23 forms a female connector portion that receives a male connector (not shown) of a harness for connecting igniter 40 to a control unit (not shown). Terminal pin 42 of igniter 40 is positioned exposed within recess 23. The male connector is inserted into recess 23, which serves as the female connector portion. This establishes electrical continuity between the core wire of the harness and terminal pin 42.

[0036] 1 and 3, a partition member 50, which constitutes part of the housing as described above, is disposed at a predetermined position in the space inside the housing. The partition member 50 is a member for dividing the space inside the housing into a gas generating agent storage chamber S1 and a filter chamber S2 in the axial direction of the peripheral wall portion 11. As a result, the partition member 50 is located on the other end side of the peripheral wall portion 11 in the axial direction when viewed from the gas generating agent storage chamber S1.

[0037] The partition member 50 has a cylindrical shape with a bottom, and is made of a metal member such as stainless steel, iron steel, aluminum alloy, or stainless alloy. The partition member 50 has a flat plate-like partition portion 51 that is arranged perpendicular to the axial direction of the peripheral wall portion 11 to partition the space inside the housing as described above, and a cylindrical plate-like annular wall portion 52 that stands from the periphery of the partition portion 51 toward the gas generating agent storage chamber S1. In this embodiment, the annular wall portion 52 has a circular ring shape when viewed along the axial direction.

[0038] The partition member 50 is arranged so that a first main surface 51a of the pair of main surfaces of the partition portion 51, which faces the filter chamber S2, abuts against the filter 80. The outer peripheral surface of the annular wall portion 52 abuts against the inner peripheral surface of the peripheral wall portion 11.

[0039] Scores 51a1 are provided on the first main surface 51a of the partitioning portion 51. The scores 51a1 are intended to allow the partitioning portion 51 to break and form an opening in response to an increase in the internal pressure of the gas generating agent storage chamber S1 due to combustion of the gas generating agent 60, and are, for example, composed of a plurality of grooves provided radially so as to intersect with one another. The scores 51a1 are provided in a portion of the filter 80 facing the hollow portion 81.

[0040] The partition member 50 is assembled by being inserted into the peripheral wall portion 11 and then joined to the peripheral wall portion 11. More specifically, the partition member 50 is press-fitted into the interior of the peripheral wall portion 11, and is fixed to the peripheral wall portion 11 by joining the annular wall portion 52 of the partition member 50 to the peripheral wall portion 11 at or near the contact portion between them, for example, by welding.

[0041] As a result, a weld 90 extending along the circumferential direction of the housing is provided in the portion of the housing corresponding to the portion into which the partition member 50 is inserted. The gap between the peripheral wall 11 and the partition member 50 is filled with the weld 90. As a result, the gap is sealed by the weld 90, making it possible to ensure airtightness in that portion. Note that electron beam welding, laser welding, resistance welding, or the like can be suitably used to weld the peripheral wall 11 and the partition member 50 together.

[0042] The assembly structure of the partition member 50 to the peripheral wall portion 11 is not limited to the assembly structure using press-fitting and welding described above, and other assembly structures may be adopted. In that case, airtightness between the peripheral wall portion 11 and the partition member 50 can be ensured by providing an O-ring or the like at an appropriate position.

[0043] Within the space inside the housing, a plurality of granular gas generating agents 60, an autoignition agent 61, and a coil spring 70 are arranged in the space sandwiched between the holder 20 and the partition member 50 (i.e., the gas generating agent storage chamber S1).

[0044] The coil spring 70 is disposed on the side of the gas generating agent storage chamber S1 where the partition member 50 is located. A plurality of granular gas generating agents 60 are disposed between the holder 20 and the coil spring 70. The autoignition agent 61 is disposed between the partition portion 51 and the coil spring 70 so as to abut against the second main surface 51b of the partition portion 51 on the side facing the gas generating agent storage chamber S1.

[0045] The gas generating agent 60 is an agent that generates gas by being ignited by hot particles generated by the activation of the igniter 40 and burning. A non-azide gas generating agent is preferably used as the gas generating agent 60. The gas generating agent 60 is generally configured as a molded body containing fuel, an oxidizer, and an additive.

[0046] 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. In particular, nitroguanidine, guanidine nitrate, cyanoguanidine, 5-aminotetrazole, or the like is preferably used.

[0047] Examples of oxidizing agents include basic metal salts 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. Suitable nitrates include sodium nitrate and potassium nitrate.

[0048] Examples of additives include binders, slag formers, and combustion adjusters. Suitable binders include organic binders such as metal salts of carboxymethyl cellulose and stearates, and inorganic binders such as synthetic hydrotalcite and acid clay. Suitable slag formers include silicon nitride, silica, and acid clay. Suitable combustion adjusters include metal oxides, ferrosilicon, activated carbon, and graphite.

[0049] The shape of the molded body of the gas generating agent 60 may be various, including granular, pellet-like, cylindrical, or other granular shapes, as well as disk-like shapes. 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 appropriately depending on the specifications of the airbag device into which the cylindrical gas generator 1A is to be incorporated, and it is preferable to select the optimal shape depending on the specifications, such as a shape in which the rate of gas generation changes over time when the gas generating agent 60 is burned. In addition to the shape of the gas generating agent 60, it is preferable to select the size and filling amount of the molded body appropriately taking into consideration the linear burning velocity, pressure exponent, etc. of the gas generating agent 60.

[0050] The autoignition agent 61 is made of pellets formed into a flat, generally cylindrical shape. The autoignition agent 61 is disposed on the opposite side of the coil spring 70 from the side on which the gas generating agent 60 is located (i.e., on the filter 80 side). The autoignition agent 61 is disposed on the radial center side of the peripheral wall portion 11 with its axial end face in contact with a second pressing portion 72b of the coil spring 70, which will be described later. The shape of the autoignition agent 61 is not particularly limited to a flat, generally cylindrical shape, and can be modified in various ways.

[0051] The autoignition agent 61 is held by being sandwiched between the partition portion 51 of the partition member 50 and the coil spring 70. As a result, the autoignition agent 61 is separated from the gas generating agent 60 by the coil spring 70.

[0052] Auto-ignition agent 61 is an agent that ignites automatically without the operation of igniter 40. More specifically, auto-ignition agent 61 spontaneously ignites at a lower temperature than gas generating agent 60, and is intended to prevent abnormal operation of cylinder-shaped gas generator 1A even if cylinder-shaped gas generator 1A is heated from the outside in the unlikely event of a fire or the like occurring in a vehicle or the like equipped with an airbag device incorporating cylinder-shaped gas generator 1A.

[0053] 1 and 3 to 5, the coil spring 70 is provided for the purpose of preventing the gas generating agent 60, which is a compact, from being crushed by vibration or the like, and is made by winding a metal wire. The coil spring 70 has a first pressing portion 72a located on the gas generating agent 60 side, a second pressing portion 72b located on the auto-ignition agent 61 side, and a spring portion 71 located between them.

[0054] The spring portion 71 is made of a portion where a metal wire is wound in a spiral shape. The first pressing portion 72a is provided at the end of the spring portion 71 on the gas generating agent 60 side. The second pressing portion 72b is provided at the end of the spring portion 71 on the autoignition agent 61 side. The first pressing portion 72a is in contact with the gas generating agent 60. The second pressing portion 72b is in contact with the autoignition agent 61.

[0055] As shown in Figures 4 and 5, the first pressing portion 72a is configured to have a generally disk-like shape as a whole, with one end of the metal wire being spirally arranged with a predetermined gap D (see Figure 4(C)) when viewed along the axial direction. The second pressing portion 72b is configured to have a generally disk-like shape as a whole, with the other end of the metal wire being spirally arranged with a predetermined gap D (see Figure 4(B)) when viewed along the axial direction. By arranging the metal wire in a spiral shape in this way, the generally disk-like first pressing portion 72a and second pressing portion 72b can be manufactured relatively easily.

[0056] Here, from the viewpoint of obtaining a desired gas output in cylinder-shaped gas generator 1A, it is important that the distance D between the metal wires constituting first pressing portion 72a and second pressing portion 72b is considerably large. This is because, if distance D is small, when gas generated in gas generating agent storage chamber S1 passes through first pressing portion 72a and second pressing portion 72b, high flow resistance is generated in these portions, resulting in large pressure loss. On the other hand, from the viewpoint of reliably fixing gas generating agent 60 and autoignition agent 61 inside gas generating agent storage chamber S1 using first pressing portion 72a and second pressing portion 72b, it is important that distance D is considerably small. This is because, if distance D is large, first pressing portion 72a will not have a surface that can come into contact with gas generating agent 60, and similarly, second pressing portion 72b will not have a surface that can come into contact with autoignition agent 61. From these viewpoints, in the present embodiment, distance D is configured to be 1.0 mm or more and 1.4 mm or less.

[0057] When viewed along the axial direction, the outer shape (more specifically, the outer diameter) of the second pressing portion 72b is configured to be larger than the outer shape of the autoignition agent 61 (see FIG. 5 in particular). In this embodiment, the outer shape of the second pressing portion 72b when viewed along the axial direction is substantially the same as the inner diameter of the annular wall portion 52 of the partition member 50. Furthermore, in this embodiment, the size of the outer shape of the first pressing portion 72a when viewed along the axial direction is the same as the size of the outer shape of the second pressing portion 72b when viewed along the axial direction.

[0058] Here, the coil spring 70 is placed in a compressed state by being interposed between the autoignition agent 61 and the gas generating agent 60. Therefore, the gas generating agent 60 is elastically biased toward the igniter 40 side while being separated from the autoignition agent 61 by the spring portion 71 via the first pressing portion 72a. As a result, the gas generating agent 60 is fixed inside the gas generating agent storage chamber S1. Therefore, with this configuration, it is possible to prevent the gas generating agent 60 made of a molded body from being crushed by vibration or the like.

[0059] The autoignition agent 61 is elastically biased toward the partition portion 51 by the spring portion 71 via the second pressing portion 72b while being spaced apart from the gas generating agent 60. As a result, the autoignition agent 61 is fixed inside the gas generating agent storage chamber S1 so as to contact the second main surface 51b of the partition portion 51.

[0060] Furthermore, when assembling the coil spring 70, the coil spring 70 is sandwiched and compressed between the auto-ignition agent 61 and the gas generating agent 60, which allows the coil spring 70 to absorb dimensional variations in the various components housed inside the housing.

[0061] 1, 3 and 4, in cylinder-shaped gas generator 1A according to the present embodiment, spring portion 71 of coil spring 70 includes constricted portion 73 configured to have a smaller outer shape than both first pressing portion 72a and second pressing portion 72b when viewed along the axial direction of peripheral wall portion 11. By configuring in this manner, cylinder-shaped gas generator 1A is made smaller and lighter, the details of which will be described later.

[0062] 1, a filter 80 is disposed in the space within the housing, which is sandwiched between the closing member 30 and the partition member 50 (i.e., the filter chamber S2). The filter 80 is a cylindrical member having a hollow portion 81 extending in a direction parallel to the axial direction of the housing body 10. One axial end face of the filter 80 abuts against the closing member 30, and the other axial end face of the filter 80 abuts against the partition member 50.

[0063] The filter 80 functions as a cooling means for cooling the gas by removing the high temperature heat of the gas generated by the combustion of the gas generating agent 60 as the gas passes through the filter 80, and also functions as a removal means for removing slag (residue) and the like contained in the gas. As described above, by using the filter 80 made of a cylindrical member, the flow resistance to the gas flowing through the filter chamber S2 during operation is kept low, making it possible to achieve an efficient gas flow.

[0064] The filter 80 can be preferably made of an assembly of metal wire or metal mesh material made of stainless steel, iron, etc. In particular, a knitted wire mesh, a plain woven wire mesh, an assembly of crimped woven metal wire, or a combination of these compressed by a press can be used.

[0065] A wound perforated metal plate or the like can also be used as the filter 80. In this case, examples of the perforated metal plate that can be used include expanded metal, which is made by cutting staggered slits in a metal plate and expanding the slits to form holes and process it into a mesh-like shape, and hook metal, which is made by drilling holes in a metal plate and flattening the burrs that form around the holes by crushing them.

[0066] A plurality of gas outlets 12 are provided along the circumferential and axial directions on the peripheral wall 11 of the portion defining the filter chamber S2. These gas outlets 12 are for directing the gas that has passed through the filter 80 to the outside of the housing.

[0067] Next, with reference to FIG. 1, an operation during operation of cylinder-shaped gas generator 1A according to the present embodiment will be described.

[0068] Referring to FIG. 1, when a vehicle equipped with cylinder-shaped gas generator 1A according to this embodiment collides, the collision is detected by collision detection means provided separately in the vehicle, and based on this, igniter 40 is activated by current supplied from a control unit provided separately in the vehicle.

[0069] When the igniter 40 is activated, the ignition charge and / or the transfer charge combusts, causing the pressure inside the ignition section 41 to rise, which causes the squib cup of the ignition section 41 to split, and thermal particles generated by the combustion of the ignition charge and / or the transfer charge flow out of the ignition section 41. The thermal particles that reach the gas generating agent 60 combust the gas generating agent 60. This generates a large amount of gas inside the gas generating agent storage chamber S1.

[0070] As a result, the pressure in the gas generating agent storage chamber S1 increases, and when the internal pressure of the gas generating agent storage chamber S1 reaches a predetermined pressure, a rupture occurs in the portion of the partition member 50 where the score 51a1 is provided. As a result, an opening is formed in the partition member 50 in the portion facing the hollow portion 81 of the filter 80, and the gas generating agent storage chamber S1 and the filter chamber S2 come into communication with each other via the opening.

[0071] As a result, the gas generated in the gas generating agent storage chamber S1 flows into the filter chamber S2 through the opening formed in the partition member 50. The gas that has flowed into the filter chamber S2 flows axially through the hollow portion 81 of the filter 80, then changes direction in the radial direction, and flows through the interior of the filter 80. During this process, the filter 80 removes heat to cool the gas, and the filter 80 removes slag contained in the gas.

[0072] The gas that has passed through filter 80 is then ejected to the outside of the housing through gas ejection port 12 provided in peripheral wall portion 11. The ejected gas is introduced into the interior of an airbag provided adjacent to cylinder-shaped gas generator 1A, and inflates and deploys the airbag. Note that autoignition agent 61 burns together with gas generating agent 60 when it is burned.

[0073] Here, in cylinder-shaped gas generator 1A according to the present embodiment, spring portion 71 of coil spring 70 includes constricted portion 73, as described above.

[0074] When coil spring 70 including constricted portion 73 is interposed between autoignition agent 61 and gas generating agent 60 in this manner, a repulsive force generated by torsional deformation of coil spring 70 is applied to autoignition agent 61 and gas generating agent 60 in addition to a repulsive force generated by compressive deformation of coil spring 70. In other words, coil spring 70 including constricted portion 73 can apply a larger compressive load to autoignition agent 61 and gas generating agent 60 by the amount of the repulsive force associated with torsional deformation, compared to a coil spring having the same axial length but not including a constricted portion (for example, a coil spring having a substantially cylindrical outer shape).

[0075] In this way, by providing cylinder-shaped gas generator 1A with coil spring 70 that can apply a larger pressing load, it becomes possible to fill gas generating agent storage chamber S1 with gas generating agent 60 at a higher density. As a result, the axial length of cylinder-shaped gas generator 1A can be shortened, and ultimately cylinder-shaped gas generator 1A can be made smaller and lighter.

[0076] Here, possible methods for increasing the compressive load on the gas generating agent include increasing the wire diameter of the coil spring or changing the material. However, these methods have the risk of inviting an increase in the manufacturing cost of the cylinder-shaped gas generator. In this regard, in cylinder-shaped gas generator 1A according to the present embodiment, the compressive load of the coil spring can be increased by providing constricted portion 73 without relying on these methods, and as a result, it is also possible to reduce the manufacturing cost of cylinder-shaped gas generator 1A.

[0077] Furthermore, by using cylinder-shaped gas generator 1A according to the present embodiment, assembly work can be facilitated.

[0078] In other words, if it is necessary to position the autoignition agent 61 at a predetermined radial position on the peripheral wall portion 11 and to position the autoignition agent 61 in a predetermined position when positioning it in order to securely sandwich the autoignition agent 61 between the coil spring 70 and the partition portion 51, then great care will be required in fixing the autoignition agent 61 inside the gas generating agent storage chamber S1, which will result in complicated assembly work.

[0079] In this regard, in cylinder-shaped gas generator 1A according to the present embodiment, as described above, second pressing portion 72b is configured to have an outer shape larger than the outer shape of autoignition agent 61 when viewed along the axial direction of peripheral wall portion 11. By configuring in this manner, it is possible to increase the degree of freedom in the arrangement and orientation of autoignition agent 61 in the radial direction of peripheral wall portion 11. This point will be described in more detail below using FIG. 6 and the aforementioned FIG. 3.

[0080] 6A and 6B are partial enlarged views illustrating examples of the arrangement and orientation of the autoignition agent. In Fig. 6A, a flat, generally cylindrical autoignition agent 61 is arranged radially outward from the peripheral wall 11 with its axial end face in contact with the second pressing portion 72b. In Fig. 6B, the autoignition agent 61 is arranged radially toward the center with its peripheral surface in contact with the second pressing portion 72b. In Fig. 6C, the autoignition agent 61 is arranged radially outward with its peripheral surface in contact with the second pressing portion 72b.

[0081] As described above, there are various arrangements and orientations of auto-ignition agent 61, but in cylinder-shaped gas generator 1A according to the present embodiment, because second pressing portion 72b is configured so that its outer shape is larger than that of auto-ignition agent 61 as described above, auto-ignition agent 61 can be fixed inside gas generating agent storage chamber S1 not only in the arrangement and orientation shown in Fig. 3 above (i.e., an orientation in which the axial end face is in contact with second pressing portion 72b, and an arrangement in which auto-ignition agent 61 is positioned toward the center in the radial direction), but also in arrangements and orientations such as those shown in Figs. 6(A) to (C), for example. Therefore, the degree of freedom in the arrangement and orientation of auto-ignition agent 61 can be increased, and as a result, the assembly work of cylinder-shaped gas generator 1A is facilitated.

[0082] Therefore, by configuring as described above, it is possible to provide a gas generator that is small, lightweight, and easy to assemble.

[0083] Furthermore, in the present embodiment, the external dimensions of first pressing portion 72a and second pressing portion 72b are the same when viewed along the axial direction of peripheral wall portion 11, and as a result, coil spring 70 has a structure that is plane-symmetrical with respect to a plane that is located at the center of coil spring 70 in the axial direction. With this configuration, it is not necessary to distinguish between the front and back of coil spring 70 when assembling coil spring 70. This also facilitates the assembly work of cylinder-shaped gas generator 1A.

[0084] In the above-described embodiment, an example has been given in which the first pressing portion 72a and the second pressing portion 72b of the coil spring 70 are configured such that, when viewed along the axial direction of the peripheral wall portion 11, the metal wire is arranged in a spiral shape at a predetermined interval, so that the overall shape is approximately disk-like, including a surface perpendicular to the axial direction. However, the first pressing portion 72a and the second pressing portion 72b may also be configured, for example, such that the metal wire is arranged approximately parallel at a predetermined interval, so that the overall shape is approximately disk-like.

[0085] Furthermore, in the present embodiment described above, the case has been exemplified where the diameter of the second pressing portion 72b when viewed along the axial direction of the peripheral wall portion 11 is approximately the same as the inner diameter of the annular wall portion 52 of the partition member 50, but the diameter of the second pressing portion 72b may be different from the inner diameter of the annular wall portion 52. Furthermore, in the present embodiment, the case has been exemplified where the outer sizes of the first pressing portion 72a and the second pressing portion 72b when viewed along the axial direction are the same, but the outer sizes of these portions may be different from each other.

[0086] (First and second modified examples) Figures 7 and 8 are partial enlarged views of cylinder-shaped gas generators according to first and second modified examples, respectively. Cylinder-shaped gas generators 1A1, 1A2 according to first and second modified examples based on the above-described embodiment will now be described with reference to Figures 7 and 8. Note that Figures 7 and 8 show cylinder-shaped gas generators 1A1, 1A2 at positions corresponding to the partial enlarged view shown in Figure 3, respectively.

[0087] As shown in Figures 7 and 8, cylinder-shaped gas generators 1A1, 1A2 according to the first and second modified examples differ from cylinder-shaped gas generator 1A according to the embodiment described above only in the configuration of the coil spring.

[0088] More specifically, in cylinder-shaped gas generator 1A1 according to the first modification, the number of turns of spring portion 71A1 of coil spring 70A1 is configured to be fewer than the number of turns of spring portion 71 of coil spring 70 in cylinder-shaped gas generator 1A. More specifically, the number of turns of spring portion 71A1 is one turn less than the number of turns of spring portion 71.

[0089] In cylinder-shaped gas generator 1A2 according to the second modification, the number of constricted portions 73A2 formed in spring portion 71A2 of coil spring 70A2 is configured to be greater than the number of constricted portions 73 formed in spring portion 71 of coil spring 70 in cylinder-shaped gas generator 1A. More specifically, spring portion 71 has a single constricted portion 73 formed therein, whereas spring portion 71A2 has a plurality of (more specifically, two) constricted portions 73A2 formed therein.

[0090] Even when configured in this manner, effects similar to those described in the above-mentioned embodiment can be obtained, and a gas generator can be made smaller and lighter and easier to assemble.

[0091] (Addendum) The characteristic configurations of the gas generators disclosed in the above-described embodiment and the modified examples thereof can be summarized as follows.

[0092] [Appendix 1] a housing having a cylindrical peripheral wall portion including a portion defining a gas generating agent storage chamber and a portion defining a filter chamber in which a filter is stored; a partition portion located inside the housing and partitioning the interior space of the housing into the gas generating agent storage chamber and the filter chamber in the axial direction of the peripheral wall portion; a plurality of granular gas generating agents contained in the gas generating agent storage chamber; an igniter that is mounted to one end of the housing on the gas generating agent storage chamber side in the axial direction and that burns the gas generating agent; an auto-ignition agent that is accommodated in the gas generating agent accommodation chamber so as to be in contact with a main surface of the partition portion on a side facing the gas generating agent accommodation chamber, and that automatically ignites without depending on activation of the igniter; a coil spring formed by winding a metal wire and interposed in a compressed state between the autoignition agent and the gas generating agent; the coil spring has a first pressing portion located on the gas generating agent side, a second pressing portion located on the autoignition agent side, and a spring portion located between the first pressing portion and the second pressing portion, the first pressing portion is configured by arranging one end of the metal wire so that the first pressing portion has a plate-like shape as a whole, the second pressing portion is configured by arranging the other end of the metal wire so that the second pressing portion has a plate-like shape as a whole, the gas generating agent is fixed inside the gas generating agent storage chamber by being urged toward the igniter by the spring portion via the first pressing portion, the autoignition agent is fixed inside the gas generating agent storage chamber by being urged toward the filter chamber by the spring portion via the second pressing portion, When viewed along the axial direction, the outer shape of the second pressing portion is larger than the outer shape of the autoignition agent, the spring portion includes a constricted portion having an outer shape smaller than both the first pressing portion and the second pressing portion when viewed along the axial direction.

[0093] [Appendix 2] 2. The gas generator according to claim 1, wherein the external size of the first pressing portion when viewed along the axial direction is the same as the external size of the second pressing portion when viewed along the axial direction.

[0094] [Appendix 3] 3. The gas generator according to claim 1, wherein the first pressing portion and the second pressing portion are configured by arranging the metal wire in a spiral shape at predetermined intervals when viewed along the axial direction.

[0095] [Appendix 4] The second pressing portion is configured to have a disk-like shape as a whole, The partition section is provided with an annular wall section that is erected from a peripheral edge of the partition section toward the gas generating agent storage chamber, 4. The gas generator according to any one of claims 1 to 3, wherein an outer diameter of the second pressing portion and an inner diameter of the annular wall portion are substantially the same.

[0096] (Other forms, etc.) The characteristic configurations shown in the above-described embodiments of the present invention and their modifications can naturally be combined with one another within the scope of the gist of the present invention.

[0097] Furthermore, in the above-described embodiment of the present invention and its modified examples, the present invention has been described by way of example only as being applied to a cylinder-type gas generator incorporated in a side airbag device, but the application of the present invention is not limited to this, and the present invention can also be applied to cylinder-type gas generators incorporated in curtain airbag devices, knee airbag devices, seat cushion airbag devices, etc., and so-called T-shaped gas generators which have an elongated outer shape similar to a cylinder-type gas generator.

[0098] As such, the above-described embodiments and their modifications disclosed herein are illustrative in all respects and are not limiting. The technical scope of the present invention is defined by the claims, and includes all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0099] 1A, 1A1, 1A2 Cylinder-type gas generator, 10 Housing body, 11 Peripheral wall portion, 12 Gas outlet, 20 Holder, 21 Penetration portion, 22 Crimping portion, 23 Recess, 30 Closure member, 40 Igniter, 41 Igniter portion, 42 Terminal pin, 43 Sealing member, 50 Partition member, 51 Partition portion, 51a First main surface, 51a1 Score, 51b Second main surface, 52 Annular wall portion, 60 Gas generating agent, 61 Auto-ignition agent, 70, 70A1, 70A2 Coil spring, 71, 71A1, 71A2 Spring portion, 72a First pressing portion, 72b Second pressing portion, 73, 73A2 Neck portion, 80 Filter, 81 Hollow portion, 90, 101 Welded portion, S1 Gas generant storage chamber, S2 filter chamber.

Claims

1. a housing having a cylindrical peripheral wall portion including a portion defining a gas generating agent storage chamber and a portion defining a filter chamber in which a filter is stored; a partition portion located inside the housing and partitioning the interior space of the housing into the gas generating agent storage chamber and the filter chamber in the axial direction of the peripheral wall portion; a plurality of granular gas generating agents contained in the gas generating agent storage chamber; an igniter that is mounted to one end of the housing on the gas generating agent storage chamber side in the axial direction and that burns the gas generating agent; an auto-ignition agent that is accommodated in the gas generating agent accommodation chamber so as to be in contact with a main surface of the partition portion on a side facing the gas generating agent accommodation chamber, and that automatically ignites without depending on activation of the igniter; a coil spring formed by winding a metal wire and interposed in a compressed state between the auto-ignition agent and the gas generating agent; the coil spring has a first pressing portion located on the gas generating agent side, a second pressing portion located on the auto-ignition agent side, and a spring portion located between the first pressing portion and the second pressing portion, the first pressing portion is configured by arranging one end of the metal wire so that the first pressing portion has a plate-like shape as a whole, the second pressing portion is configured by routing the other end of the metal wire so that the second pressing portion has a plate-like shape as a whole, the gas generating agent is fixed inside the gas generating agent storage chamber by being biased toward the igniter by the spring portion via the first pressing portion, the autoignition agent is fixed inside the gas generating agent storage chamber by being biased toward the filter chamber by the spring portion via the second pressing portion, When viewed along the axial direction, the second pressing portion has an outer shape larger than an outer shape of the autoignition agent, a gas generator, wherein the spring portion includes a constricted portion having an outer shape smaller than both the first pressing portion and the second pressing portion when viewed along the axial direction;

2. 2. The gas generator according to claim 1, wherein an outer size of the first pressing portion when viewed along the axial direction and an outer size of the second pressing portion when viewed along the axial direction are identical.

3. 2. The gas generator according to claim 1, wherein the first pressing portion and the second pressing portion are configured by the metal wire being arranged in a spiral shape with a predetermined interval between them when viewed along the axial direction.

4. The second pressing portion is configured to have a disk-like shape as a whole, The partition section is provided with an annular wall section that is erected from a peripheral edge of the partition section toward the gas generating agent storage chamber, 4. The gas generator according to claim 1, wherein an outer diameter of the second pressing portion and an inner diameter of the annular wall portion are substantially the same.

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