gas generator

Abstract

The goal is to obtain a gas generator that allows for easy control of the ignition rate of the gas generating agent using AI in emergencies, while maintaining the same axial length of the housing as conventional models. [Solution] The gas generator 100 has a long, roughly cylindrical outer shape and includes a housing 10, a holder 20 attached to one open end of the housing 10, an igniter 50 held by the holder 20 for igniting the gas generating agent 31, a cup member 32, a filter 41, and a partition member 34 that separates the gas generating agent 31 from the AI ​​agent 33. The partition member 34 includes a coil spring 35 and a locking member 36 that encloses and locks the coil spring 35, which is initially biased or compressed in the axial direction of the housing 10. The locking member 36 is made of a material with a melting point lower than the ignition point of the AI ​​agent 33, and when the locking member 36 melts, it releases the lock of the coil spring 35, pushing the gas generating agent 31 towards the igniter 50.

Description

Technical Field

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

Background Art

[0002] In a cylinder-type gas generator, the long cylindrical housing is generally configured such that one end is closed by a closing member and the other end is closed by a holder having an ignition portion (see, for example, Patent Document 1 below). The gas generator of Patent Document 1 below includes a housing, a gas generating agent loaded in the housing, and an auto-ignition agent (AI agent) provided in the vicinity of the gas generating agent via a partition member in the housing. Since this AI agent auto-ignites at a lower temperature than the gas generating agent, in the event of a fire or the like occurring in a vehicle equipped with an airbag device incorporating the gas generator, it is possible to prevent the induction of abnormal operation of the gas generator due to external heating.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the gas generator represented by the above patent document, in the event of a fire or the like occurring in a vehicle or the like, the control of the ignition amount of the gas generating agent by the AI agent can be achieved by changing the shape or position of the partition member or the like to provide a distance between the gas generating agent and the AI agent. However, due to that distance, it is necessary to lengthen the housing along the axial direction.

[0005] Therefore, the present invention aims to provide a gas generator that allows for easy control of the amount of ignition of the gas generating agent by the AI ​​agent in an emergency, while maintaining the same axial length of the housing as conventional models. [Means for solving the problem]

[0006] (1) The gas generator of the present invention comprises: a long cylindrical housing loaded with a gas generating agent that generates gas by combustion and having a gas outlet formed thereon for ejecting the gas; an igniter capable of igniting and burning the gas generating agent; a holder that holds a part of the igniter and is fixed to one end of the housing in the axial direction; a blocking member fixed to the other end of the housing in the axial direction; an auto-igniter provided inside the housing that ignites at a lower temperature than the gas generating agent; and a partition member that separates the gas generating agent and the auto-igniter, wherein the gas generating agent is provided on the igniter side and the auto-igniter is provided on the blocking member side; the partition member has an elastic body and a locking member that locks the elastic body in an initial state biased or compressed in the axial direction of the housing; the locking member is made of a material whose melting temperature is lower than the ignition temperature of the auto-igniter; and the locking of the elastic body is released when the locking member melts.

[0007] (2) In the gas generator described in (1) above, it is preferable that another elastic body is provided to separate the igniter and the gas generating agent.

[0008] (3) In the gas generator described in (2) above, the locking member is preferably a box-shaped member, a member made of thread or string, or a member with a cross-section that is approximately C-shaped or U-shaped. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a gas generator that allows for easy control of the amount of ignition of the gas generating agent by the AI ​​agent in emergencies, while maintaining the axial length of the housing to be about the same as in conventional models. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram (partially omitted) showing the internal structure of a gas generator according to an embodiment of the present invention, with a portion shown in cross-section. [Figure 2] Figure 1 is a schematic diagram (partially omitted) showing the internal structure of the gas generator during operation. [Figure 3] This figure shows a modified example of the partition member of the gas generator shown in Figure 1. [Modes for carrying out the invention]

[0011] Hereinafter, with reference to Figures 1 and 2, a cylinder-type gas generator according to an embodiment of the present invention and a seat in a vehicle equipped with this gas generator will be described.

[0012] (Configuration of gas generator 100) The gas generator 100 has a long, roughly cylindrical outer shape and includes a housing 10, a holder 20 attached to one open end of the housing 10, and a closing member 12 attached to the other end of the housing 10 to close the other open end of the housing 10.

[0013] The housing 10 consists of a long, cylindrical member having a peripheral wall and openings at both ends in the axial direction.

[0014] The sealing member 12 consists of a disc-shaped member having a predetermined thickness. In addition, a gas outlet 11 is provided on the peripheral wall near the end of the housing 10 on the side to which the sealing member 12 is attached. This gas outlet 11 is a hole for ejecting gas generated inside the gas generator 100 to the outside, and multiple outlets are provided along the circumferential and axial directions of the housing 10.

[0015] Furthermore, the closing member 12 is made of metal such as stainless steel, iron or steel, aluminum alloy, or stainless steel alloy. As shown in Figure 1, the closing member 12 is fixed to the housing 10 by forming an annular welded portion 13 by laser welding or the like, with a portion of the closing member 12 inserted into one of the open ends of the housing 10.

[0016] The holder 20 is made of a metal such as stainless steel, iron or steel, aluminum alloy, or stainless alloy, and has a tapered fitting portion 23 into which the igniter 50 is fitted, an annular welded portion 22 formed by laser welding or the like, and a fitting portion 21 on the opposite side of the holding position of the igniter 50 into which a female connector (not shown) for supplying power to the igniter 50 can be fitted.

[0017] As mentioned above, a female connector is formed on the mating portion 21 of the holder 20. This female connector is the part to which the male connector of a harness that transmits signals from a collision detection means, which is provided separately from the gas generator 100, is connected. A retainer 60 is attached to the female connector. This retainer 60 is attached to prevent the cylinder-type gas generator 100 from malfunctioning due to electrostatic discharge or the like during transport of the gas generator 100, and when the male connector of the harness is inserted into the female connector during the assembly stage to the airbag system, contact with its terminal pins (not shown) is released.

[0018] As shown in Figure 1, an igniter 50, which serves as an ignition means for the gas generating agent 31, is positioned at one end of the housing 10 in the axial direction (i.e., the part closer to the holder 20). The igniter 50 and the holder 20 that fixes the igniter 50 function as ignition means that generate a flame for burning the granular gas generating agent 31, which will be described later.

[0019] As shown in FIG. 1, the igniter 50 is held by the holder 20 while being inserted into the fitting portion 23 of the holder 20. More specifically, the igniter 50 includes a base frame that inserts and holds a pair of terminal pins (not shown), and a squib cup 51 (cup-shaped member) attached to the base frame. A resistor (bridge wire) is attached to connect the tips of the terminal pins (not shown) inserted into the squib cup 51, and the squib cup 51 is filled with an ignition charge so as to surround this resistor or to contact this resistor. Generally, nichrome wire or the like is used as the resistor, and generally ZPP (zirconium·potassium perchlorate), ZWPP (zirconium·tungsten·potassium perchlorate), lead trinitrate or the like is used as the ignition charge. Note that the squib cup 51 may be filled with not only the ignition charge but also a transfer charge. As the transfer charge that can be arranged simultaneously with the ignition charge, a composition composed of a metal / oxidant typified by boron / potassium nitrate or the like, a composition composed of titanium hydride / potassium perchlorate, or a composition composed of boron / 5-aminotetrazole / potassium nitrate / molybdenum trioxide or the like is used.

[0020] When a collision is detected, a predetermined amount of current flows through the resistor via the terminal pins (not shown). When a predetermined amount of current flows through the resistor, Joule heat is generated in the resistor, and upon receiving this heat, the ignition charge starts to burn. The high-temperature flame generated by the combustion ruptures the squib cup 51 that houses the ignition charge. The time from when the current starts to flow through the resistor until the igniter 50 operates is 2 milliseconds or less when a nichrome wire is used as the resistor.

[0021] Also, the squib cup 51 is generally made of metal or resin. Note that a substantially cylindrical member (not shown) that covers other than the vicinity of the tip portion of the peripheral wall portion of the squib cup 51 may be caulked and fixed to the holder 20 by the caulking portion 24 together with the igniter 50. Here, the substantially cylindrical member is a directional member that directs the direction of the flame generated in the igniter 50 toward the cup member 32 side during operation.

[0022] As shown in FIG. 1, in the internal space of the housing 10, a space 10A in which a gas generating agent 31 or the like is sealed and a filter 41 are provided in parallel in the axial direction of the housing 10.

[0023] The gas generating agent 31 is a composition that is ignited by the flame generated by being ignited by an igniter 50 and generates gas by burning. Also, the gas generating agent 31 is generally formed as a molded body containing a fuel, an oxidizing agent, and an additive. As the fuel, for example, triazole derivatives, tetrazole derivatives, guanidine derivatives, azodicarbonamide derivatives, hydrazine derivatives, etc. or combinations thereof are used. Specifically, for example, nitroguanidine, guanidine nitrate, cyanoguanidine, 5-aminotetrazole, etc. are preferably used. Also, as the oxidizing agent, for example, basic metal nitrates such as basic copper nitrate and basic copper carbonate, perchlorates such as ammonium perchlorate or potassium perchlorate, nitrates containing cations selected from alkali metals, alkaline earth metals, transition metals, and ammonia are used. As the nitrate, for example, sodium nitrate, potassium nitrate, etc. are preferably used. Also, as the additive, a binder, a slag former, a combustion regulator, etc. are mentioned. As the binder, for example, cellulose derivatives such as hydroxypropylmethylcellulose, metal salts of carboxymethylcellulose, organic binders such as stearates, inorganic binders such as synthetic hydrotalcite and acid clay can be preferably used. As the slag former, silicon nitride, silica, acid clay, etc. can be preferably used. Also, as the combustion regulator, metal oxides, ferrosilicon, activated carbon, graphite, etc. can be preferably used.

[0024] In the housing 10, the space in which the gas generating agent 31 is loaded and the space in which the AI agent (auto-igniting agent) 33 is provided are partitioned by a partition member 34.

[0025] Since the AI ​​agent 33 automatically ignites at a lower temperature than the gas generating agent 31, in the event of a fire or other incident in a vehicle equipped with an airbag system or the like that incorporates the gas generator 100, it is possible to prevent the gas generator 100 from malfunctioning due to external heating. Furthermore, the AI ​​agent 33 is held inside the bottom surface 32b of the cup member 32 by adhesive or the like. In addition, the AI ​​agent 33 is protected by the partition member 34 so as not to come into contact with the gas generating agent 31. As a result, no parts are needed to hold the AI ​​agent 33.

[0026] The partition member 34 includes a coil spring 35 (an example of an elastic body) and a locking member 36 that encloses and locks the coil spring 35, which is initially biased or compressed in the axial direction of the housing 10.

[0027] The coil spring 35 is formed by winding a spiral so that its overall appearance resembles a cylindrical shape. Furthermore, one end of the coil spring 35, which is formed in a spiral shape, abuts against the bottom portion 34A formed on the gas generating agent 31 side of the locking member 36, and the other end, which is also formed in a spiral shape, abuts against the top portion 34B formed on the AI ​​agent 33 side of the locking member 36, and is disposed inside the locking member 36 in its initial state with an elastic force biased along the axial direction of the housing 10.

[0028] The locking member 36 can be any material whose melting point is lower than the ignition point of the AI ​​agent 33. Examples include resins or rubbers with a melting point lower than the ignition point of the AI ​​agent 33, such as polyethylene, polypropylene, polyacetal, polyamide 6, polyvinyl chloride, polystyrene, cellophane tape, polyethylene terephthalate (PET), and ABS resin.

[0029] The coil spring 37 is formed by winding a spiral so that its overall appearance resembles a cylindrical shape. One end of the coil spring 37 surrounds the squib cup 51 and abuts against the crimping portion 24, while the other end, which is formed in a spiral shape, abuts against the gas generating agent 31, thereby biasing the gas generating agent 31 with elastic force. Due to this biasing force, the gas generating agent 31 is fixed within the housing 10 by being sandwiched between the coil spring 37 and the partition member 34. Furthermore, since the coil spring 37 as a whole has a cylindrical shape that follows the shape of the squib cup 51 from the igniter 50 side to the gas generating agent 31 side, it is possible to easily direct the direction of the flame emitted from the igniter 50 towards the gas generating agent 31.

[0030] The cup member 32 is a short, bottomed cylindrical member that closes the end of the filter 41 on the gas generating agent 31 side, and comprises a cylindrical portion 32a and a bottom surface portion 32b that closes the end of the cylindrical portion 32a on the AI ​​agent 33 side. Preferably, the cup member 32 is fixed to the inner wall of the housing 10 so that the position of the filter 41 can be positioned at a predetermined position (for example, a position facing the gas outlet 11 as shown in Figure 1). The bottom surface portion 32b is designed to melt or break due to the gas generated during operation. The cup member 32 is made of a resin member or a composite reinforced member containing resin. Examples of this resin member or composite reinforced member containing resin include, for example, glass fiber-reinforced PA6 (polyamide 6), POM (polyacetal, polyoxymethylene), etc. As one modification, the cup member 32 may be made of, for example, a metal such as stainless steel or iron, or an alloy such as an aluminum alloy or stainless steel alloy.

[0031] The cup member 32 prevents the generated gas from leaking out to the gas outlet 11 by bypassing it between the inner wall of the housing 10 and the outer circumference of the filter 41, while also ensuring a seal. In other words, the cup member 32 allows the gas generated on the igniter 50 side inside the housing 10 to flow into the filter 41 side through a portion that has been opened by melting or damage to the bottom portion 32b (a portion corresponding to one end of the hollow portion 41a).

[0032] The filter 41 consists of a cylindrical member having a columnar (for example, roughly cylindrical, roughly rectangular, etc.) hollow portion 41a in the center. By using a filter 41 made of a cylindrical member, the flow resistance of the working gas flowing during operation is kept low, enabling efficient gas flow. The filter 41 can be made of, for example, wire rods made of metal such as stainless steel or iron, or mesh material that has been wound or compressed by pressing. Specifically, knitted wire mesh, plain woven wire mesh, or an assembly of crimped metal wire rods can be used. The filter 41 functions as a cooling means to cool the gas by removing the high temperature heat contained in the gas as it passes through the filter 41 generated in the housing 10, and also functions as a removal means to remove slag and other substances contained in the gas. As one modification of the filter 41, a filter having a labyrinthine flow path formed by combining roughly cylindrical or mortar-shaped parts made of metal may be used. This allows the path of the working gas to be changed in various directions, making it possible to cool the gas and remove slag.

[0033] Furthermore, in the embodiments of the present invention described above, an example was given in which a filter made of so-called knitted wire mesh was used. However, it is also possible to use a filter made by winding perforated metal or expanded metal instead. Here, perforated metal refers to a metal plate in which only openings are provided (i.e., no protrusions are provided around the periphery of the openings), and expanded metal refers to a metal plate in which openings are provided in a mesh-like structure by, for example, making staggered cuts in a plate-shaped metal member and then expanding it. Even when such perforated metal or expanded metal is used in place of the knitted wire mesh described above, the same effects as those described in the embodiments of the present invention described above can be obtained.

[0034] Furthermore, in the perforated metal and expanded metal described above, a filter consisting of a laminate is constructed by winding a single metal plate-shaped member, but the structure of the filter is not limited to this structure. That is, each layer may be made of a separate metal plate-shaped member and these may be combined to form a laminate filter, or some of the layers may be formed by winding a single metal plate-shaped member, and the remaining layers may be formed by winding another single metal plate-shaped member, and these may be combined to form a laminate filter.

[0035] Next, the operation of the gas generator 100 during normal operation, as described above, will be explained. When a vehicle equipped with an airbag system incorporating the gas generator 100 in this embodiment is involved in a collision, the collision is detected by a collision detection means separately provided in the vehicle, and the igniter 50 is activated based on this. When the igniter 50 is activated, the pressure inside the igniter 50 increases due to the combustion of the igniter, causing the tip of the squib cup 51 of the igniter 50 to rupture, and the flame flows out from the tip of the squib cup 51 of the igniter 50 to the cup member 32 inside the housing 10.

[0036] The flames that flow in in this way ignite and burn the gas generating agent 31 inside the housing 10, generating a large amount of gas. The combustion of this gas generating agent 31 increases the pressure inside the space 10A in the housing 10, and the generated gas melts or damages the portion of the bottom surface 32b of the cup member 32 corresponding to the hollow portion 41a, causing it to rupture and flow into the hollow portion 41a. The generated gas is then ejected from the gas outlet 11 to the outside of the gas generator 100 via the filter 41, but because it passes through the filter 41, the generated gas is cooled to a predetermined temperature. The gas ejected from the gas outlet 11 is then guided into the airbag, causing it to inflate and deploy.

[0037] Next, the operation of the gas generator 100 during emergency activation, as described above, will be explained. In the event of a fire or other incident in a vehicle equipped with an airbag system incorporating the gas generator 100 in this embodiment, and the temperature inside the gas generator 100 reaches the melting temperature of the locking member 36, the coil spring 35 is automatically released from its initial locked state due to the melting or peeling of the locking member 36 and the elastic force of the coil spring 35. Depending on the selected material, for example, if the locking member 36 is made of resin, the melted locking member 36 may extend along the axial direction of the housing 10, as shown in Figure 2, and at least one of the bottom portion 34A and the top portion 34B may be melted or peeled off. Then, the coil spring 35, released from its locked state, pushes the gas generating agent 31 towards the igniter 50, and the coil spring 37 contracts. That is, a space with a predetermined distance is formed between the gas generating agent 31 and the AI ​​agent 33. Subsequently, when the inside of the gas generator 100 reaches a predetermined high temperature, the AI ​​agent 33 ignites, igniting and burning the gas generating agent 31 at the planned ignition rate to generate gas. The gas pressure inside the housing 10 causes the generated gas to melt or break the portion of the bottom surface 32b of the cup member 32 corresponding to the hollow portion 41a, causing it to rupture and flow into the hollow portion 41a. The generated gas then passes through the filter 41 and is ejected from the gas outlet 11 to the outside of the gas generator 100. As it passes through the filter 41, the generated gas is cooled to a predetermined temperature. The gas ejected from the gas outlet 11 is then guided into the airbag, causing it to inflate and deploy.

[0038] (Main features of the gas generator 100) According to this embodiment, while maintaining the axial length of the housing 10 to be about the same as conventional designs, it is possible to create a gas generator 100 that allows for easy control of the amount of ignition of the gas generating agent 31 by the AI ​​agent 33 in emergencies. Furthermore, compared to gas generators in which the AI ​​agent and the gas generating agent are positioned far apart, it is possible to shorten the axial length of the housing, thus enabling a more compact and lightweight design.

[0039] Although embodiments of the present invention have been described above with reference to the drawings, it should be understood that the specific configuration is not limited to these embodiments. The scope of the present invention is indicated by the claims rather than the above description of embodiments, and further includes all modifications within the meaning and scope equivalent to the claims.

[0040] For example, the coil spring 37 in the above embodiment does not necessarily have to be provided. Also, the coil springs 35 and 37 can be any elastic material. For example, they can be leaf springs or rubber materials with relatively high heat resistance.

[0041] Furthermore, the locking member may be a box-shaped member, such as a cylindrical or polygonal prism-shaped member, or a conical or frustoconical-shaped member. The elastic body in this case should be appropriately selected in terms of material, shape, and size to match the internal shape of the locking member. The locking member may or may not have a hole in at least one of its bottom or top. For example, as shown in Figure 3(a), there may be a cylindrical locking member 136 with a hole 136a formed in the bottom, or as shown in Figure 3(b), there may be a cylindrical locking member 236 with holes 236a and 236b formed in the bottom and top. The locking member may also be a thread or string made of resin such as nylon thread (e.g., fishing line) or elastic rubber. In the case of a thread or string made of rubber, it may be annular (so-called rubber band, rubber ring, or rubber band). These threads or strings can be used as locking members to bind and lock an elastic body, such as a coil spring, in a biased or compressed state in its initial configuration.

[0042] Furthermore, instead of the locking member 36 in the above embodiment, a locking member 336 having an opening on some of its surfaces and a substantially C-shaped cross-section (see Figure 3(c) showing an example of a locking member viewed from the side) or a locking member 436 having an opening on some of its surfaces and a substantially U-shaped cross-section (see Figure 3(d) showing an example of a locking member viewed from the side) may be used. [Explanation of Symbols]

[0043] 10 Housing 10A space 11 Gas nozzles 12. Closure member 13, 22 Welds 20 holders 21, 23 Fitting part 24 Crimping part 31 Gas generating agent 32 Cup components 32a Cylindrical part 32b Bottom part 33 AI agent 34 Partition Members 34A bottom 34B Heaven 35, 37 Coil springs 36, 136, 236, 336, 436 Locking member 41 Filters 41a Hollow part 50 igniter 51 Squib Cup 60 retainers 100 Gas Generator 136a, 236a, 236b holes

Claims

1. A long, cylindrical housing is fitted with a gas generating agent that generates gas when burned, and has a gas nozzle formed therein for ejecting the gas, An igniter capable of igniting and burning the aforementioned gas generating agent, A holder that holds a portion of the igniter and is fixed to one end of the housing in the axial direction, A closing member fixed to the other end of the housing in the axial direction, An automatic ignition agent provided within the housing, which ignites at a lower temperature than the gas generating agent, A partition member that separates the gas generating agent and the auto-ignition agent, Equipped with, The gas generating agent is provided on the igniter side, and the automatic ignition agent is provided on the blocking member side. The partition member comprises an elastic body and a locking member that locks the elastic body in an initial state where it is biased or compressed in the axial direction of the housing. The gas generator is characterized in that the locking member is made of a material with a melting point lower than the ignition temperature of the automatic ignition agent, and the locking of the elastic body is released when the locking member melts.

2. The gas generator according to claim 1, characterized in that another elastic body is provided to partition the igniter and the gas generating agent.

3. The gas generator according to claim 1, characterized in that the locking member is a box-shaped member, a member made of thread or string, or a member having a cross-section that is substantially C-shaped or substantially U-shaped.

Images