gas generator

Abstract

To provide a gas generator in which stable operation can be realized, and also weight saving and reduction in manufacturing costs are achieved by a structural device.SOLUTION: A gas generator 1 includes: an igniter 40; a partition member 50 for partitioning a space inside a housing into a gas generating agent storage chamber S1 and a filter chamber S2 in an axial direction; and a gas generating agent 60 and a coil spring 70 stored in the gas generating agent storage chamber S1. The coil spring 70 is interposed between the partition member 50 and the gas generating agent 60, and fixes, inside the gas generating agent storage chamber S1, the gas generating agent 60 while separating from the partition member 50. When a volume of the gas generating agent storage chamber S1 is V1, and a volume of a non-filled space S1A as a space where the gas generating agent 60 is not arranged inside the gas generating agent storage chamber S1 because the coil spring 70 is arranged is V2, the V1, V2 satisfy the condition of 0.05≤V2 / V1≤0.32.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 equipped in an automobile or the like, and particularly relates to a so-called cylinder type gas generator having a long cylindrical outer shape that is preferably incorporated in a side airbag device or the like.

Background Art

[0002] Conventionally, from the viewpoint of protecting occupants of automobiles and the like, airbag devices as occupant protection devices have become widespread. The airbag device is equipped for the purpose of protecting the occupant from the impact generated during a vehicle collision or the like, and instantaneously inflates and deploys the airbag during a vehicle collision or the like, so that the airbag serves as a cushion to receive the body of the occupant.

[0003] The gas generator is incorporated in this airbag device, and when the vehicle collides or the like, the igniter is ignited by energization from the control unit, and the gas generating agent is burned by the flame generated in the igniter to instantaneously generate a large amount of gas, thereby inflating and deploying the airbag.

[0004] Gas generators exist in various configurations based on specifications such as the installation position and output with respect to the vehicle or the like. One of them is what is called a cylinder type gas generator. The cylinder type gas generator has a long cylindrical outer shape and is preferably incorporated in a side airbag device, a curtain airbag device, a knee airbag device, a seat cushion airbag device, or the like.

[0005] Normally, in a cylinder type gas generator, an igniter is assembled at one end portion in the axial direction of the housing, and a gas generating agent storage chamber in which the gas generating agent is stored is provided on the one end portion side, a filter chamber in which a filter is arranged is provided on the other end portion side in the axial direction of the housing, and a gas ejection port is provided in the peripheral wall portion of the housing that defines the filter chamber.

[0006] In a cylinder-type gas generator configured in this way, the gas generating agent burns when the igniter is activated, generating gas inside the housing. The generated gas then passes through the filter and is ejected to the outside through the gas outlet.

[0007] Examples of documents disclosing this type of cylinder-type gas generator include Japanese Patent Application Publication No. 2007-314102 (Patent Document 1). [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2007-314102 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] In general, it is important for gas generators to burn the gas generating agent stably and continuously during operation. To burn the gas generating agent stably and continuously, it is necessary to place the gas generating agent under a predetermined high-pressure environment. Therefore, gas generators are designed so that the pressure inside the housing, which is a pressure-resistant container, is raised to a considerable level during operation by narrowing the size of the gas outlet provided in the housing to a desired size.

[0010] On the other hand, in recent years there has been a strong demand for lighter gas generators. To lighten a gas generator, it is effective to reduce the thickness of the housing, and if this can be done, it will lead to a reduction in material costs and, as a result, a reduction in manufacturing costs. However, if the thickness of the housing is simply reduced, there is a risk that the pressure resistance performance of the housing may not be sufficiently ensured.

[0011] Therefore, in order to achieve stable operation of the gas generator while reducing its weight, it is essential to reduce the pressure inside the housing during operation to a considerable extent, within a range that allows the gas generating agent to burn stably and continuously. However, achieving this through structural design of the gas generator is not easy.

[0012] Therefore, the present invention has been made in view of these problems, and aims to provide a gas generator that not only achieves stable operation but also reduces weight and manufacturing costs through structural improvements. [Means for solving the problem]

[0013] A gas generator according to the present invention comprises a housing, a partition member, an igniter, and a coil spring. The housing consists of a long cylindrical member with one end and the other end closed in the axial direction, and includes a gas generating agent chamber containing a gas generating agent and a filter chamber where a filter is located. The partition member partitions the internal space of the housing in the axial direction so that the gas generating agent chamber is formed at the one end of the housing and the filter chamber is formed at the other end of the housing. The igniter is assembled to the one end of the housing to burn the gas generating agent. The coil spring is interposed between the partition member and the gas generating agent and is housed in the gas generating agent chamber, fixing the gas generating agent inside the gas generating agent chamber by biasing it toward the one end of the housing while separating it from the partition member. In the gas generator according to the present invention described above, if the volume of the gas generating agent containment chamber is V1, and the volume of the unfilled space inside the gas generating agent containment chamber where the gas generating agent is not placed due to the placement of the coil spring is V2, 0.164 The condition ≤V2 / V1 ≤ 0.32 is satisfied.

[0014] In the gas generator according to the present invention described above, the igniter may have an ignition section containing an igniter, in which case it is preferable that the ignition section faces the gas generating agent without any other components in between.

[0015] In the gas generator according to the present invention described above, the coil spring may include a cylindrical portion located on the partition member side and a pressing portion located at the end of the cylindrical portion on the gas generating agent side, which presses the gas generating agent toward the one end of the housing.

[0016] In the gas generator according to the present invention described above, the partition member may be a bottomed cylindrical member having a partition wall portion arranged perpendicular to the axial direction of the housing and an annular wall portion erected from the periphery of the partition wall portion toward the one end of the housing. In this case, it is preferable that the axial end of the coil spring located toward the other end of the housing is inserted at least inside the partition member. [Effects of the Invention]

[0017] According to the present invention, not only can stable operation be achieved, but the gas generator can also be made lighter and have reduced manufacturing costs through structural improvements. [Brief explanation of the drawing]

[0018] [Figure 1] This is a schematic diagram of a cylinder-type gas generator according to an embodiment. [Figure 2] Figure 1 is an enlarged cross-sectional view of the vicinity of the igniter in the cylinder-type gas generator. [Figure 3] This is an enlarged cross-sectional view of the vicinity of the partition member of the cylinder-type gas generator shown in Figure 1. [Figure 4] This table summarizes the test conditions and test results of the verification test. [Figure 5] This graph shows the test results of the verification test. [Modes for carrying out the invention]

[0019] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following embodiments illustrate the case where the present invention is applied to a cylinder-type gas generator incorporated in a side airbag device. In the following embodiments, the same or common parts are denoted by the same reference numerals in the drawings, and the description thereof will not be repeated.

[0020] (Embodiment) FIG. 1 is a schematic view of a cylinder-type gas generator according to an embodiment. FIGS. 2 and 3 are enlarged cross-sectional views of the vicinity of the igniter and the vicinity of the partition member of the cylinder-type gas generator shown in FIG. 1, respectively. First, referring to FIGS. 1 to 3, the configuration of the cylinder-type gas generator 1 according to the present embodiment will be described.

[0021] As shown in FIG. 1, the cylinder-type gas generator 1 has an elongated columnar outer shape and has an elongated cylindrical housing with one end and the other end located in the axial direction closed. The housing includes a housing body 10, a holder assembly 20, and a closing member 30.

[0022] Inside the housing composed of the housing body 10, the holder assembly 20, and the closing member 30, an igniter 40, a partition member 50, a gas generating agent 60, a coil spring 70, a filter 80, etc. are accommodated as internal components. Also, inside the housing, a gas generating agent accommodation chamber S1 in which the gas generating agent 60 and the coil spring 70 among the above-described internal components are accommodated, and a filter chamber S2 in which the filter 80 is disposed are located.

[0023] Here, in the following description, among the internal spaces of the cylinder-type gas generator 1, the space corresponding to the above-described gas generating agent accommodation chamber S1 and the space corresponding to the hollow portion 81 of the filter 80 described later in the above-described filter chamber S2 are included and will be referred to as a combustion chamber.

[0024] The housing body 10 constitutes the peripheral wall of the housing and consists of a long cylindrical member with openings formed at both ends in the axial direction. The holder assembly 20 consists of a cylindrical member having a through-hole-shaped hollow opening that extends in a direction parallel to the axial direction of the housing body 10, and has a holder portion 20A and a connector portion 20B, which will be described later. The closing member 30 consists of a substantially disc-shaped member.

[0025] The housing body 10 may be made of a metal component such as stainless steel, iron, aluminum alloy, or stainless alloy, or it may be made of a press-formed product formed into a cylindrical shape by press-working rolled steel sheet, such as SPCE. Alternatively, the housing body 10 may be made of electric resistance welded pipe, such as STKM.

[0026] In particular, when the housing body 10 is constructed from a press-formed rolled steel sheet or electric resistance welded pipe, it is possible to form the housing body 10 at a lower cost and more easily compared to using metal components such as stainless steel or iron, and to significantly reduce its weight.

[0027] On the other hand, the holder portion 20A and the closing member 30 of the holder assembly 20 are made of metal components such as stainless steel, iron, aluminum alloy, or stainless alloy.

[0028] The holder assembly 20 is fixed to the housing body 10 so as to close one of the axial open ends of the housing body 10. Specifically, with the holder assembly 20 inserted into the aforementioned open end of the housing body 10, a predetermined position of the housing body 10 is reduced in diameter radially inward toward the holder assembly 20, and another predetermined position of the housing body 10 is reduced in diameter radially inward toward the vicinity of the holder assembly 20, thereby crimping and fixing the holder assembly 20 to the housing body 10. As a result, one axial end of the housing is formed by the holder assembly 20. Details of this crimping and fixing will be explained later.

[0029] The closing member 30 is fixed to the housing body 10 so as to close the other open end of the housing body 10 in the axial direction. Specifically, with the closing member 30 inserted into the other open end of the housing body 10, the closing member 30 is crimped and fixed to the housing body 10 by reducing the diameter of a predetermined position of the housing body 10 radially inward toward the vicinity of the closing member 30. As a result, the other end of the housing in the axial direction is formed by the closing member 30. Details of this crimping and fixing will be explained later.

[0030] These crimping fixations are of a type called eight-way crimping, which reduces the diameter of the housing body 10 almost uniformly toward the radially inward direction. By performing this eight-way crimping, crimped portions 12 to 14 are provided on the housing body 10. As a result, the housing body 10, the holder assembly 20, and the closing member 30 come into direct contact with each other, preventing any gaps from forming between them.

[0031] Furthermore, the assembly structure of the holder assembly 20 and the closing member 30 to the housing body 10 is not limited to the assembly structure described above (details of which will be described later), and other assembly structures may be adopted. Also, the housing body 10 and the closing member 30 may not be separate components, but rather formed from a single component having a bottomed cylindrical shape.

[0032] As shown in Figures 1 and 2, the igniter 40 is mounted to the aforementioned axial end of the housing by being supported by the holder assembly 20. The igniter 40 is for burning the gas generating agent 60 and is installed facing the internal space of the housing.

[0033] The igniter 40 is for generating a flame and is also called a squib. The igniter 40 includes a base 41, an ignition part 42, and a pair of terminal pins 43. The base 41 is the part that holds the ignition part 42 and the pair of terminal pins 43, and is also the part that is fixed to the holder assembly 20. The base 41 holds the pair of terminal pins 43 by inserting them through it.

[0034] The ignition unit 42 contains, inside, an igniter that generates a flame when ignited and burned during operation, and a resistor (bridge wire) for igniting the igniter. A pair of terminal pins 43 are connected to the ignition unit 42 to ignite the igniter.

[0035] More specifically, the ignition unit 42 includes a cup-shaped squib cup, and the aforementioned resistor is attached to connect the tips of a pair of terminal pins 43 inserted into the squib cup. The ignition charge is loaded into the squib cup so as to surround or be close to the resistor. In addition, a propellant charge may be loaded into the ignition unit 42 as needed.

[0036] Here, the resistor is generally made of nichrome wire or an alloy containing platinum and tungsten, and the igniter is generally made of ZPP (zirconium-potassium perchlorate), ZWPP (zirconium-tungsten-potassium perchlorate), lead tricinate, etc. The propellant is made of a composition consisting of metal powder / oxidant, such as B / KNO3, B / NaNO3, Sr(NO3)2, a composition consisting of titanium hydride / potassium perchlorate, or a composition consisting of B / 5-aminotetrazole / potassium nitrate / molybdenum trioxide, etc.

[0037] When a collision is detected, a predetermined amount of current flows through the resistor via terminal pin 43. This current generates Joule heat in the resistor, causing the igniter to begin burning. The high-temperature thermal particles produced by the combustion cause the squib cup containing the igniter to rupture. The time from when current flows through the resistor until the igniter 40 activates is generally 2 milliseconds or less when a nichrome wire is used for the resistor.

[0038] The igniter 40 is fixed to the holder assembly 20 with its ignition section 42 protruding toward the inside of the housing, and a portion of it positioned inside the aforementioned hollow opening of the holder assembly 20. As a result, the igniter 40 has its ignition section 42 facing the gas generating agent containment chamber S1, while its terminal pin 43 is facing the opposite side from the gas generating agent containment chamber S1.

[0039] As shown in Figure 2, the holder assembly 20 has a metal holder portion 20A located on the gas generating agent containment chamber S1 side and a resin connector portion 20B located on the opposite side from the gas generating agent containment chamber S1 side. The holder assembly 20 is formed as an integrated part by pre-assembling the holder portion 20A and the connector portion 20B together, and this is attached to one of the opening ends of the housing body 10 as described above.

[0040] The holder portion 20A is composed of a flat, substantially disc-shaped member having a through portion extending axially in its central part, and includes a cylindrical first body portion 21 and an annular projection 22 that protrudes outward from the outer circumferential surface of the first body portion 21.

[0041] The holder portion 20A is inserted into the housing body 10 such that its axial direction is parallel to the axial direction of the housing body 10. As a result, the through portion provided in the holder portion 20A defines a part of the hollow opening of the holder assembly 20, and the annular projection 22 protrudes from the first body portion 21 along the radial direction of the housing body 10. The annular projection 22 is provided at the end of the first body portion 21 on the gas generating agent containment chamber S1 side.

[0042] The holder portion 20A is a member for receiving and holding the igniter 40, and has a concave-shaped receiving portion 23a at its axial end on the gas generating agent containment chamber S1 side for receiving the igniter 40. This receiving portion 23a is connected to a through portion provided in the holder portion 20A. In addition, a crimping portion 23b is provided at the end of the holder portion 20A on the gas generating agent containment chamber S1 side so as to surround the receiving portion 23a. The crimping portion 23b is a part for crimping and fixing the igniter 40 to the holder portion 20A.

[0043] The igniter 40 is fixed to the holder portion 20A with its base 41 housed in the housing portion 23a of the holder portion 20A. Specifically, the base 41 is inserted into the housing portion 23a of the holder portion 20A, and the base 41 is pressed against the bottom surface of the housing portion 23a. In this state, the crimping portion 23b provided on the holder portion 20A is bent, thereby fixing the igniter 40 to the holder portion 20A. As a result, the igniter 40 is held by the holder portion 20A.

[0044] Here, a sealing member 27, such as an O-ring, is interposed between the holder portion 20A and the igniter 40. This seals the gap between the holder portion 20A and the igniter 40 by filling it with the sealing member 27. Therefore, this configuration ensures airtightness in that portion. Note that the method of fixing the igniter 40 is not limited to the fixing method using the crimped portion 23b described above, and other fixing methods may be used.

[0045] The connector portion 20B is composed of a substantially cylindrical member having a through portion extending axially in its central part, and includes a cylindrical second body portion 24 and a cylindrical portion 25 extending axially from one end of the second body portion 24.

[0046] The connector portion 20B is inserted into the housing body 10 such that its axial direction is parallel to the axial direction of the housing body 10. As a result, the through portion provided in the connector portion 20B defines a part of the hollow opening of the holder assembly 20 as described above, and the cylindrical portion 25 extends from the second body portion 24 toward the gas generating agent containment chamber S1.

[0047] Here, the holder portion 20A described above is fixed by being press-fitted into the connector portion 20B. More specifically, the first body portion 21 of the holder portion 20A is press-fitted into the cylindrical portion 25 of the connector portion 20B, and the first body portion 21 and the cylindrical portion 25 are in pressure contact, thereby fixing the holder portion 20A and the connector portion 20B so that they do not easily detach.

[0048] The connector section 20B is for receiving a connection connector that connects to the terminal pins 43 of the igniter 40. The terminal pins 43 of the igniter 40 are located inside this connector section 20B. The through-hole provided in the connector section 20B described above constitutes the part for receiving this connection connector.

[0049] More specifically, in the cylinder-type gas generator 1, the igniter 40 needs to be electrically connected to a control unit (not shown) of a vehicle or the like, which is located externally. A harness is typically used for this electrical connection. A male connector is attached to the end of this harness, and a female connector that can be connected to this male connector needs to be provided in the connector section 20B. The through-hole provided in the connector section 20B constitutes this female connector.

[0050] Furthermore, when the male connector of the harness is inserted into the aforementioned through-hole which functions as a female connector, electrical conductivity is achieved between the core wire of the harness and the terminal pin 43, thereby connecting the ignition device 40 to the control unit of the vehicle or the like.

[0051] Furthermore, the connector portion 20B also functions as a component that ensures airtightness between the housing body 10 and the holder portion 20A. This airtightness between the housing body 10 and the holder portion 20A is primarily achieved by the cylindrical portion 25 of the connector portion 20B.

[0052] Specifically, the cylindrical portion 25 is inserted into the open end of the housing body 10 and externally fitted onto the first body portion 21 of the holder portion 20A. As a result, in the portion of the housing body 10 where the cylindrical portion 25 is located in the axial direction, these parts are arranged in the order of the first body portion 21 of the holder portion 20A, the cylindrical portion 25 of the connector portion 20B, and the housing body 10, from the radially inner to the radially outer side of the housing body 10. That is, the first body portion 21 is surrounded by the cylindrical portion 25, and the cylindrical portion 25 is surrounded by the housing body 10.

[0053] Furthermore, the housing body 10 in the portion corresponding to the cylindrical portion 25 (i.e., the portion covering the cylindrical portion 25) is provided with a crimping portion 12 that is tapered radially inward. With this crimping portion 12, the cylindrical portion 25 of the connector portion 20B, made of resin, is sandwiched between the crimping portion 12 of the housing body 10, made of metal, and the first body portion 21 of the holder portion 20A, also made of metal. This seals the gap between the housing body 10 and the first body portion 21 with the cylindrical portion 25.

[0054] Here, when the crimping portion 12 is provided on the housing body 10, the cylindrical portion 25 is sandwiched between the housing body 10 and the first body portion 21, and as a result of the load, compressive deformation occurs in the cylindrical portion 25. As a result, the cylindrical portion 25 and the housing body 10 come into close contact, and the cylindrical portion 25 and the first body portion 21 come into close contact.

[0055] Therefore, the cylindrical portion 25 is interposed between the housing body 10 and the first body portion 21 in close contact with each of them, thereby achieving the sealing of the gap described above. Consequently, this configuration makes it possible to ensure airtightness in that portion.

[0056] The material of the connector portion 20B is not particularly limited, but suitable materials include nylon-based resins such as nylon 6, nylon 66, and those filled with glass filler, polyacetal (POM) resin, polycarbonate (PC) resin, polyphenylene sulfide (PPS) resin, and polybutylene terephthalate (PBT) resin.

[0057] Furthermore, in the holder portion 20A, an annular projection 22 is provided at a position closer to the gas generating agent containment chamber S1 than the first body portion 21. Therefore, the annular projection 22 also functions as a stopper to prevent the holder assembly 20 from falling out of the housing body 10. This stopper function of the annular projection 22 is exhibited not only during the manufacturing and non-operational stages of the cylinder-type gas generator 1, but also when subjected to pressure due to the rise in internal pressure of the gas generating agent containment chamber S1 during operation.

[0058] In this embodiment, the cylindrical gas generator 1 has an inner diameter greater than the inner diameter of the second body portion 24, and the connector portion 20B is provided with an annular stepped surface 26 that connects the inner circumferential surface of the second body portion 24 and the inner circumferential surface of the cylindrical portion 25. As a result, the first body portion 21 of the holder portion 20A is inserted into one axial end of the connector portion 20B on which the annular stepped surface 26 is provided, and consequently, the axial end face of the first body portion 21, which is located on the opposite side from the gas generating agent containment chamber S1, is in contact with the annular stepped surface 26.

[0059] With this configuration, the holder portion 20A and the connector portion 20B can be fixed together by press-fitting the holder portion 20A into the connector portion 20B, as described above, and the positioning of the holder portion 20A and the connector portion 20B along the axial direction of the housing body 10 can be performed with high precision.

[0060] When this configuration is adopted, the female connector described above will be defined by the axial end face of the first body portion 21 and the inner circumferential surface of the second body portion 24, which are located on the opposite side from the gas generating agent containment chamber S1.

[0061] As shown in Figures 1 and 3, partition members 50 are positioned at predetermined locations within the internal space of the housing. The partition members 50 are components that divide the internal space of the housing into a gas generating agent containment chamber S1 and a filter chamber S2 in the axial direction.

[0062] The partition member 50 has a bottomed cylindrical shape and is made of a metal material such as stainless steel, iron ore, aluminum alloy, or stainless alloy. The partition member 50 has a flat plate-shaped partition wall portion 51 arranged perpendicular to the axial direction of the housing body 10, and a cylindrical plate-shaped annular wall portion 52 erected from the periphery of the partition wall portion 51 toward the gas generating agent containment chamber S1. The partition member 50 is positioned so that the outer main surface of the partition wall portion 51 abuts against the filter 80, and the outer circumferential surface of the annular wall portion 52 abuts against the inner circumferential surface of the housing body 10.

[0063] A score 51a is provided on the main surface of the partition wall 51 that abuts the filter 80. The score 51a is intended to cause the partition wall 51 to rupture and form an opening as the internal pressure of the gas generating agent containment chamber S1 increases due to the combustion of the gas generating agent 60, and is composed of, for example, a plurality of grooves arranged radially and intersecting each other. The score 51a is provided on the part of the filter 80 that faces the hollow portion 81.

[0064] The partition member 50 is fixed by being joined to the housing body 10 while it is inserted inside the housing body 10. More specifically, the partition member 50 is press-fitted into the housing body 10 and fixed by welding the annular wall portion 52 of the partition member 50 to the housing body 10 at or near the contact point between them.

[0065] As a result, a welded portion 90 extending along the circumferential direction of the housing body 10 is formed on the housing body 10 and the partition member 50 corresponding to the portion in which the partition member 50 is inserted. Electron beam welding, laser welding, resistance welding, etc., can be suitably used for welding the partition member 50 to the housing body 10.

[0066] When the partition members 50 are fixed to the housing body 10 by welding in this manner, the gap between these partition members 50 and the housing body 10 is filled by the welded portion 90, thereby sealing the gap. Therefore, this configuration makes it possible to ensure airtightness in that portion.

[0067] Furthermore, the method of fixing the partition member 50 to the housing body 10 is not limited to the pressing and welding methods described above, but other fixing methods may be used. In that case, airtightness between the partition member 50 and the housing body 10 can be ensured by providing O-rings, sealing tape, etc., at appropriate positions.

[0068] As shown in Figures 1 to 3, the gas generating agent 60, the coil spring 70, and the combustion control member 45 are arranged in the space between the holder assembly 20 and the partition member 50 within the housing (i.e., the gas generating agent storage chamber S1).

[0069] Of these, the combustion control member 45 is located on the side where the holder assembly 20 is located (i.e., on the side of the housing in the axial direction as described above within the gas generating agent containment chamber S1), and the coil spring 70 is located on the side where the partition member 50 is located (i.e., on the side of the housing in the axial direction as described above within the gas generating agent containment chamber S1, on the other end). The gas generating agent 60 is located between these combustion control member 45 and coil spring 70.

[0070] The gas generating agent 60 is an agent that generates gas by being ignited and burned by the thermal particles produced when the igniter 40 is activated. It is preferable to use a non-azide gas generating agent 60, and the gas generating agent 60 is generally composed of a molded body containing fuel, an oxidizer, and an additive.

[0071] As fuels, for example, triazole derivatives, tetrazole derivatives, guanidine derivatives, azodicarbonamide derivatives, hydrazine derivatives, etc., or combinations thereof can be used. Specifically, for example, nitroguanidine, guanidine nitrate, cyanoguanidine, 5-aminotetrazole, etc., are preferably used.

[0072] Suitable 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.

[0073] Examples of additives include binders, slag-forming agents, and combustion modifiers. Suitable binders include organic binders such as metal salts of carboxymethylcellulose and stearates, and inorganic binders such as synthetic hydrotalcite and acid clay. Suitable slag-forming agents include silicon nitride, silica, and acid clay. Suitable combustion modifiers include metal oxides, ferrosilicon, activated carbon, and graphite.

[0074] The molded body of the gas generating agent 60 can take various shapes, including granular, pelletized, cylindrical, and disc-shaped forms. In the case of cylindrical forms, perforated molded bodies with through holes inside (e.g., single-hole cylindrical or multi-hole cylindrical shapes) are also used. These shapes are preferably selected appropriately according to the specifications of the airbag device into which the cylinder-type gas generator 1 is incorporated. For example, it is preferable to select a shape in which the gas generation rate changes over time during the combustion of the gas generating agent 60, or to select the optimal shape according to the specifications. Furthermore, in addition to the shape of the gas generating agent 60, it is preferable to appropriately select the size and filling amount of the molded body, taking into consideration the linear combustion rate and pressure index of the gas generating agent 60.

[0075] The coil spring 70 is provided to prevent the gas generating agent 60, which is made of a molded body, from being crushed by vibration or the like, and has a cylindrical portion 71 and a pressing portion 72 formed by bending a metal wire.

[0076] The cylindrical portion 71 consists of a spring-like section in which a metal wire is wound in a spiral shape, with one end positioned to abut against the partition wall portion 51 of the partition member 50. On the other hand, the pressing portion 72 is provided at the other end of the cylindrical portion 71 and is configured to have a substantially disc-like shape overall, for example, by arranging the metal wires substantially parallel at predetermined intervals, or by arranging the metal wires in a spiral shape at predetermined intervals. This pressing portion 72 is in contact with the gas generating agent 60.

[0077] Here, the coil spring 70 is compressed by being sandwiched between the partition member 50 and the gas generating agent 60. As a result, the gas generating agent 60 is elastically biased by the coil spring 70 toward the holder assembly 20 side (i.e., toward the aforementioned end side of the housing), thereby preventing the gas generating agent 60 from moving within the gas generating agent containment chamber S1. Therefore, this configuration prevents the molded gas generating agent 60 from being crushed by vibration or the like.

[0078] Furthermore, when the coil spring 70 is assembled, it is compressed by being sandwiched between the partition member 50 and the gas generating agent 60, which allows the coil spring 70 to absorb dimensional variations in the various components housed inside the housing.

[0079] The combustion control member 45 is designed to efficiently guide the heat particles generated by the igniter 40 to the gas generating agent 60 when the cylinder-type gas generator 1 is in operation. The combustion control member 45 has a substantially cylindrical shape and is fitted onto the ignition unit 42 so as to surround the ignition unit 42 by covering its circumferential surface.

[0080] In this way, because the ignition unit 42 is surrounded by the combustion control member 45, when the squib cup defining the outer surface of the ignition unit 42 ruptures, an opening is mainly formed at the tip of the squib cup located on the gas generating agent 60 side, and as a result the direction of travel of the heat particles generated in the ignition unit 42 is narrowed in the axial direction of the housing.

[0081] In other words, by positioning the combustion control member 45 to fill the gap between the housing body 10 and the ignition unit 42, the combustion control member 45 is located radially outward of the ignition unit 42. As a result, the combustion control member 45 obstructs the radial outward movement of the heat particles generated in the ignition unit 42, and consequently, the direction of movement of the heat particles is narrowed in the axial direction.

[0082] Therefore, by configuring it in this way, when the cylinder-type gas generator 1 is in operation, it becomes possible to direct the direction of travel of the heat particles generated at the ignition section 42 of the igniter 40, and to efficiently guide the heat particles to the gas generating agent 60.

[0083] Furthermore, as shown in Figure 2, the outer circumferential surface of the combustion control member 45 is provided with an annular recess 45a extending in the circumferential direction. This annular recess 45a is a portion for fixing the combustion control member 45 to the housing body 10. Specifically, with the combustion control member 45 inserted into the housing body 10, the portion of the housing body 10 corresponding to the annular recess 45a is reduced in diameter radially inward and engages with the annular recess 45a, thereby crimping and fixing the combustion control member 45 to the housing body 10. As a result, a crimped portion 13 is provided on the portion of the housing body 10 corresponding to the annular recess 45a.

[0084] Here, by providing the crimping portions 12 and 13 described above at predetermined positions on the housing body 10, the holder assembly 20 is also fixed to the housing body 10. In other words, by providing a pair of crimping portions 12 and 13 so as to sandwich the annular projection 22 provided on the holder portion 20A of the holder assembly 20, the movement of the holder portion 20A along the axial direction of the housing body 10 is restricted, thereby firmly fixing the holder assembly 20 to the housing body 10.

[0085] As shown in Figure 1, a filter 80 is placed in the space within the housing that is sandwiched between the closing member 30 and the partition member 50 (i.e., the filter chamber S2). The filter 80 is made of a cylindrical member having a hollow portion 81 that extends in a direction parallel to the axial direction of the housing body 10, with one end face in the axial direction in contact with the closing member 30 and the other end face in the axial direction in contact with the partition wall portion 51 of the partition member 50.

[0086] The filter 80 functions as a cooling means that cools the gas generated by the combustion of the gas generating agent 60 by removing the high-temperature heat from the gas as it passes through the filter 80, and also functions as a removal means that removes slag (residue) and other substances contained in the gas. As described above, by using a filter 80 made of a cylindrical member, the flow resistance to the gas flowing through the filter chamber S2 during operation is kept low, enabling efficient gas flow.

[0087] The filter 80 can preferably be made of an assembly of metal wires or metal mesh materials made of stainless steel or iron. Specifically, it can be made of knitted wire mesh, plain woven wire mesh, an assembly of crimped metal wires, or these materials compressed by pressing.

[0088] Alternatively, a perforated metal plate wound around a metal sheet can be used as the filter 80. In this case, examples of perforated metal plates that can be used include expanded metal, which is made by cutting a metal plate in a staggered pattern and then expanding the cuts to form holes and create a mesh-like structure, and hook metal, which is made by drilling holes in a metal plate and then flattening the burrs that form around the edges of the holes.

[0089] The housing body 10 that defines the filter chamber S2 is provided with multiple gas outlets 11 along the circumferential and axial directions. These multiple gas outlets 11 are for guiding the gas that has passed through the filter 80 to the outside of the housing.

[0090] The closing member 30 is fixed to the housing body 10 by a crimping portion 14 provided at a predetermined position on the housing body 10. Specifically, the housing body 10 is provided with a crimping portion 14 that is reduced in diameter radially inward on the side of the housing body 10 opposite to the side where the filter chamber S2 is located, as viewed from the closing member 30, and adjacent to the closing member 30. The closing member 30 is sandwiched between this crimping portion 14 and the filter 80. As a result, the movement of the closing member 30 along the axial direction of the housing body 10 is restricted, and the closing member 30 is firmly fixed to the housing body 10.

[0091] Next, with reference to Figure 1, the operation of the cylinder-type gas generator 1 according to this embodiment will be described.

[0092] Referring to Figure 1, if a vehicle equipped with the cylinder-type gas generator 1 according to this embodiment is involved in a collision, the collision is detected by a collision detection means separately provided in the vehicle, and based on this, the igniter 40 is activated by power supplied from a control unit separately provided in the vehicle.

[0093] When the igniter 40 is activated, the ignition charge, or the ignition booster in addition to it, burns, increasing the pressure inside the ignition unit 42. This causes the squib cup of the ignition unit 42 to rupture, and the heat particles generated by the burning of the ignition charge, or the ignition booster in addition to it, flow out of the ignition unit 42. The heat particles that reach the gas generating agent 60 burn the gas generating agent 60, thereby generating a large amount of gas inside the gas generating agent containment chamber S1.

[0094] Consequently, the pressure in the gas generating agent chamber S1 increases, and when the internal pressure of the gas generating agent chamber S1 reaches a predetermined pressure, a rupture occurs in the part of the partition member 50 where the score 51a is provided. As a result, an opening is formed in the partition member 50 in the part facing the hollow portion 81 of the filter 80, and the gas generating agent chamber S1 and the filter chamber S2 become connected through this opening.

[0095] Consequently, the gas generated in the gas generating agent containment chamber S1 flows into the filter chamber S2 through the opening formed in the partition member 50. The gas that flows into the filter chamber S2 flows axially through the hollow section 81 of the filter 80, then changes direction radially and flows through the inside of the filter 80. At this time, heat is removed from the gas by the filter 80, cooling it, and slag contained in the gas is removed by the filter 80.

[0096] The gas that has passed through the filter 80 is then ejected to the outside of the housing through a gas outlet 11 provided in the housing body 10. The ejected gas is introduced into the airbag located adjacent to the cylinder-type gas generator 1, causing the airbag to inflate and deploy.

[0097] In this embodiment, the cylinder-type gas generator 1 not only achieves stable operation, but also reduces weight and manufacturing costs through structural improvements. This point will be explained in detail below.

[0098] As shown in Figures 1 to 3, in the cylinder-type gas generator 1 according to this embodiment, as described above, the coil spring 70 is arranged in the gas generating agent storage chamber S1 so as to be interposed between the partition member 50 and the gas generating agent 60. As a result, the gas generating agent 60 is positioned at a distance from the partition member 50, and the gas generating agent storage chamber S1 includes an unfilled space S1A, which is the space where the gas generating agent 60 is not placed due to the placement of the coil spring 70, and a filled space S1B, which is the space where the gas generating agent 60 is placed.

[0099] In this embodiment, the cylinder-type gas generator 1 includes a combustion control member 45 in addition to the gas generating agent 60 and coil spring 70 in the gas generating agent containment chamber S1. However, since the combustion control member 45 essentially functions as a pressure partition, the space in which the combustion control member 45 is located is not included in the gas generating agent containment chamber S1.

[0100] In the cylinder-type gas generator 1 according to this embodiment, if the volume of the gas generating agent containment chamber S1 (i.e., the sum of the volume of the unfilled space S1A and the volume of the filled space S1B) is V1, and the volume of the unfilled space S1A is V2, then the volume ratio V2 / V1, which is the ratio of V1 and V2, satisfies the condition 0.05 ≤ V2 / V1 ≤ 0.32.

[0101] By satisfying this condition, the cylinder-type gas generator 1 according to this embodiment can reduce the pressure inside the housing (i.e., the internal pressure of the combustion chamber) to a considerable extent during operation, within a range that allows the gas generating agent 60 to burn stably and continuously. This condition was derived based on the results of verification tests described later.

[0102] In other words, when the volume ratio V2 / V1 described above satisfies the condition 0.05 ≤ V2 / V1, a cavity of a predetermined volume is created in the portion of the gas generating agent containment chamber S1 on the partition member 50 side. This prevents unburned gas generating agent 60 from accumulating in that portion when the cylinder-type gas generator 1 is operating. As a result, the opening formed in the partition member 50 when the partition wall 51 breaks will not be blocked by unburned gas generating agent 60, thus reducing the gas flow resistance in that portion. Consequently, the gas generated in the gas generating agent containment chamber S1 flows more smoothly into the filter chamber S2, effectively suppressing the rise in internal pressure of the combustion chamber.

[0103] However, experiments have confirmed that if the aforementioned cavity is made too large, not only does the housing become larger, but it also leads to a significant increase in the internal pressure of the combustion chamber during operation. This is thought to be because, in the initial stages of operation of a cylinder-type gas generator, a large amount of unburned decomposition gas is generated as the gas generating agent burns. However, if the aforementioned cavity is made too large, this unburned decomposition gas does not remain inside the gas generating agent chamber, but flows into the filter chamber through an opening formed in the partition member when the partition wall breaks, and accumulates in the filter chamber. Subsequently, this unburned decomposition gas is ignited by thermal particles that enter the filter chamber later, causing it to burn explosively.

[0104] In this regard, by ensuring that the volume ratio V2 / V1 satisfies the condition V2 / V1 ≤ 0.32, the mechanism for such an increase in internal pressure can be suppressed, thereby effectively suppressing the increase in internal pressure of the combustion chamber.

[0105] Therefore, as with the cylinder-type gas generator 1 according to this embodiment, by satisfying the condition that the volume ratio V2 / V1 is 0.05 ≤ V2 / V1 ≤ 0.32, stable operation can be achieved, and the rise in internal pressure of the combustion chamber during operation can be effectively suppressed, making it possible to reduce the thickness of the housing accordingly. As a result, the structural ingenuity described above makes it possible to reduce the weight of the cylinder-type gas generator 1 and lower the manufacturing cost.

[0106] In this embodiment, the cylinder-type gas generator 1 is configured such that the ignition unit 42 of the igniter 40 directly faces the gas generating agent 60 without the need for any other components. This configuration allows the gas generating agent 60 to start burning earlier when the igniter 40 is activated, thereby improving ignition performance immediately after the igniter 40 is activated and increasing the flame generated at that time.

[0107] Therefore, by adopting this configuration, many gas generating agents can start burning at once, and an opening will be formed in the partition member 50 earlier. As a result, the gas generated in the gas generating agent containment chamber S1 will flow more smoothly into the filter chamber S2, making it possible to suppress the rise in internal pressure of the combustion chamber even more effectively.

[0108] Furthermore, in order to more effectively suppress the rise in internal pressure of the combustion chamber, it is preferable to increase the diameter of the hollow portion 81 of the filter 80 (for example, to make the diameter 11 mm or more). By configuring it in this way, it becomes possible to increase the area of ​​the opening formed in the partition member 50 during operation, so that the gas generated in the gas generating agent containment chamber S1 flows more smoothly into the filter chamber S2, and it becomes possible to more effectively suppress the rise in internal pressure of the combustion chamber.

[0109] Furthermore, in the cylinder-type gas generator 1 according to this embodiment, as described above, the axial end of the coil spring 70 located on the filter chamber S2 side is configured to be inserted into the partition member 50. This makes it possible to attach the entire partition member 50 to the housing body 10 with the coil spring 70 already assembled to the partition member 50 during the manufacturing of the cylinder-type gas generator 1, thereby simplifying its manufacturing process.

[0110] Furthermore, Patent Document 1, mentioned above, discloses a cylinder-type gas generator in which a coil spring is interposed between a partition member and a gas generating agent inside the gas generating agent containment chamber, similar to the cylinder-type gas generator 1 according to this embodiment. However, the coil spring disclosed in Patent Document 1 is provided to prevent unburned gas generating agent from flowing into the filter chamber, and therefore its function is completely different from the coil spring 70 provided in the cylinder-type gas generator 1 according to this embodiment. In fact, Patent Document 1 not only makes no mention of the volume ratio mentioned above, but also does not describe how the coil spring helps to suppress the rise in internal pressure during operation.

[0111] (Verification test) Figure 4 is a table summarizing the test conditions and test results of the verification test, and Figure 5 is a graph showing the test results of the said verification test. The verification test conducted by the inventor will now be described with reference to Figures 4 and 5, as well as the aforementioned Figure 1.

[0112] In the verification tests, as Verification Examples 1 to 6, cylinder-type gas generators with various volume ratios V2 / V1 as described above were actually manufactured, and the maximum internal pressure of the combustion chamber during operation was measured by operating these generators.

[0113] The cylinder-type gas generators in Verification Examples 1 to 6 all conform to the configuration of the cylinder-type gas generator 1 in the above-described embodiment, and the only difference in configuration between these cylinder-type gas generators in Verification Examples 1 to 6 is basically the axial length L2 of the coil spring 70 shown in Figure 1. Here, the reason why the axial length L1 of the gas generating agent containment chamber S1 (more precisely, the axial length of the part of the gas generating agent containment chamber S1 excluding the part in which the combustion control member 45 is located) differs in the cylinder-type gas generators in Verification Examples 1 to 6 is because the axial length L2 of the coil spring 70 described above is different, while the axial length of the part of the gas generating agent containment chamber S1 in which the gas generating agent 60 is contained is basically the same.

[0114] The gas generating agent 60 used in the cylinder-type gas generators in Verification Examples 1 to 6 all consisted mainly of GN (guanidine nitrate) and BCN (basic copper nitrate), with a molar count of 0.45 mol in each case. Furthermore, the inner diameter R of the housing body 10 used in the cylinder-type gas generators in Verification Examples 1 to 6 was 17.4 mm in each case, and the outer and inner diameters of the coil springs 70 used in the cylinder-type gas generators in Verification Examples 1 to 6 were 16.2 mm and 14.6 mm, respectively.

[0115] Furthermore, the measurement point for the maximum internal pressure during operation of the cylinder-type gas generator in verification examples 1 to 6 was set to approximately the center of the closing member 30 facing the filter chamber S2 (see point P shown in Figure 1).

[0116] Here, for the cylinder-type gas generators related to Verification Examples 1, 3, and 4, two samples of each were prepared, while for the cylinder-type gas generators related to Verification Examples 2, 5, and 6, only one sample of each was prepared. For the cylinder-type gas generators related to Verification Examples 1, 3, and 4, for which two samples were prepared, the average value of the maximum internal pressure of each combustion chamber is plotted on a graph in Figure 5.

[0117] Referring to Figures 4 and 5, the results of the verification tests showed that the cylinder-type gas generators in Verification Examples 2-5, where the volume ratios V2 / V1 were 0.093, 0.164, 0.231, and 0.291 respectively, exhibited a significantly greater reduction in the maximum internal pressure of the combustion chamber compared to the cylinder-type gas generators in Verification Examples 1 and 6, where the volume ratios V2 / V1 were 0.014 and 0.329 respectively. Specifically, while the maximum internal pressure of the combustion chambers of the cylinder-type gas generators in Verification Examples 1 and 6 all exceeded 100 MPa, the maximum internal pressure of the combustion chambers of the cylinder-type gas generators in Verification Examples 2-5 were all suppressed to less than 80 MPa. In the table shown in Figure 4, a maximum internal pressure of the combustion chamber suppressed to less than 100 MPa is evaluated as "good," and a maximum internal pressure of the combustion chamber exceeding 100 MPa is evaluated as "unacceptable."

[0118] Based on these results, it is understood that by satisfying the above-mentioned volume ratio V2 / V1 condition of 0.05 ≤ V2 / V1 ≤ 0.32, the maximum internal pressure of the combustion chamber can be suppressed to at least 100 MPa or less. Furthermore, in order to further ensure this effect, it is preferable that the above-mentioned volume ratio V2 / V1 condition of 0.08 ≤ V2 / V1 ≤ 0.31 is satisfied in order to suppress the maximum internal pressure of the combustion chamber to about 80 MPa or less, and furthermore, in order to further ensure this effect, it is preferable that the above-mentioned volume ratio V2 / V1 condition of 0.09 ≤ V2 / V1 ≤ 0.30 is satisfied in order to suppress the maximum internal pressure of the combustion chamber to about 70 MPa or less.

[0119] Furthermore, in the cylinder-type gas generator manufactured in this verification test, the axial length of the coil spring 70 that actually satisfies the above-mentioned volume ratio V2 / V1 of 0.05 ≤ V2 / V1 ≤ 0.32 is L2 They are generally between 5mm and 25mm in size.

[0120] Based on the results of the verification tests described above, it can be said that by using the cylinder-type gas generator 1 according to the above embodiment, not only can stable operation be achieved, but the gas generator can also be made lighter and have reduced manufacturing costs through structural improvements.

[0121] (Other forms) In the embodiments of the present invention described above, a cylinder-type gas generator was explained using as an example, in which one axial end of the housing is composed of a holder assembly consisting of a metal holder portion and a resin connector portion. However, instead, one axial end of the housing may be composed of only a metal holder.

[0122] Furthermore, in the embodiments of the present invention described above, a cylinder-type gas generator without an auto-ignition agent that ignites automatically without the operation of an igniter was used as an example for explanation, but the cylinder-type gas generator may be configured to include such an agent. The auto-ignition agent ignites spontaneously at a lower temperature than the gas generating agent, and is intended to prevent abnormal operation from being induced by external heating of the cylinder-type gas generator in the event of a fire or the like in a vehicle equipped with an airbag system incorporating the cylinder-type gas generator. When providing this auto-ignition agent in a cylinder-type gas generator, for example, the auto-ignition agent can be placed in the space within the combustion chamber and in contact with a partition member. In that case, one example is the auto-ignition Agent However, it can be fixed in place by being sandwiched between a coil spring and a partition member.

[0123] Furthermore, in the embodiments of the present invention described above, the application of the present invention to a cylindrical gas generator incorporated into a side airbag system was used as an example. However, the application of the present invention is not limited to this, and it can also be applied to cylindrical gas generators incorporated into curtain airbag systems, knee airbag systems, seat cushion airbag systems, etc., as well as so-called T-shaped gas generators that have an elongated external shape similar to that of a cylindrical gas generator.

[0124] Thus, the embodiments disclosed herein are illustrative in all respects and not restrictive. The technical scope of the present invention is defined by the claims and includes all modifications within the meaning and scope of equivalents to the claims. [Explanation of Symbols]

[0125] 1 Cylinder-type gas generator, 10 Housing body, 11 Gas outlet, 12-14 Crimped parts, 20 Holder assembly, 20A Holder part, 20B Connector part, 21 First body, 22 Annular projection, 23a Housing part, 23b Crimped part, 24 Second body, 25 Cylindrical part, 26 Annular stepped surface, 27 Seal member, 30 Closure member, 40 Ignition device, 41 Base, 42 Ignition part, 43 Terminal pin, 45 Combustion control member, 45a Annular recess, 50 Partition member, 51 Partition wall, 51a Score, 52 Annular wall, 60 Gas generating agent, 70 Coil spring, 71 Cylindrical part, 72 Pressing part, 80 Filter, 81 Hollow part, 90 Welded part, S1 Gas generating agent housing chamber, S1A Unfilled space, S1B filled space, S2 filter chamber.

Claims

1. A long, cylindrical housing containing a gas generating agent chamber and a filter chamber, with one end and the other end closed in the axial direction, A partition member divides the internal space of the housing in the axial direction such that the gas generating agent containment chamber is formed at one end of the housing and the filter chamber is formed at the other end of the housing, An igniter assembled to one end of the housing for burning the gas generating agent, The system includes a coil spring interposed between the partition member and the gas generating agent, which houses the gas generating agent in the gas generating agent containment chamber, and which fixes the gas generating agent inside the gas generating agent containment chamber by biasing the gas generating agent toward the one end of the housing while separating it from the partition member, A gas generator that satisfies the condition 0.164 ≤ V2 / V1 ≤ 0.32, where V1 is the volume of the gas generating agent containment chamber, and V2 is the volume of the unfilled space inside the gas generating agent containment chamber where the gas generating agent is not placed due to the placement of the coil spring.

2. The igniter has an ignition section containing an igniter, The gas generator according to claim 1, wherein the ignition unit faces the gas generating agent without the need for any other components.

3. The gas generator according to claim 1 or 2, wherein the coil spring includes a cylindrical portion located on the partition member side and a pressing portion located at the end of the cylindrical portion on the gas generating agent side, which presses the gas generating agent toward the one end of the housing.

4. The partition member consists of a bottomed cylindrical member having a partition wall portion arranged perpendicular to the axial direction of the housing and an annular wall portion erected from the periphery of the partition wall portion toward the one end of the housing. The gas generator according to any one of claims 1 to 3, wherein the axial end of the coil spring located on the other end side of the housing is inserted into at least the interior of the partition member.

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