gas generator

Abstract

The goal is to obtain a gas generator that, even with a relatively small-diameter, elongated housing, has sufficient strength at the ignition end while using relatively inexpensive materials and achieving a lighter weight than conventional designs. [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, a closing member 12 attached to the other end of the housing 10 to close the other open end of the housing 10, an annular portion 60 provided at the other end of the holder 20, and a pocket portion 70 provided inside the annular portion 60. The annular portion 60 and the pocket portion 70 are formed separately, with an opening 61 formed in the annular portion 60, and the same number of locking portions 72 as the opening 61 formed on the outer circumference of the pocket portion 70, and the pocket portion 70 is provided inside the annular portion 60 with the locking portions 72 locked into the opening 61.

Description

Technical Field

[0004] , , ,

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

Background Art

[0002] In a gas generator for being incorporated in a seat seat or the like, in order to make it easy to attach, a gas generator having a housing with a relatively small diameter and an elongated shape is desired. Examples of such a gas generator include those listed in Patent Document 1 below. In a gas generator such as Patent Document 1 below, it is natural that the thickness of the wall portion of the housing is sufficient and the strength is sufficient. In particular, at the end portion on the igniter side of the gas generator (in Patent Document 1 below, the end portion of the housing), at the portion where the airbag contacts during deployment, it is necessary to have a strength that is not destroyed. In addition, when the end portion on the igniter side of the above-described gas generator is destroyed, there is a possibility that the female connector or retainer connected to the end portion on the igniter side of the above-described gas generator may also be destroyed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In gas generators like the one described in Patent Document 1, the igniter-side end of the gas generator and the rest of the gas generator are integrally formed housings. While this allows for a relatively small-diameter housing, the thickness of the housing walls must be matched to the thickness of the igniter-side end of the gas generator, which requires strength. This increases the overall weight of the housing, making weight reduction difficult. Alternatively, instead of increasing the thickness of the housing walls, the entire housing could be made of a stronger material, but this tends to increase material costs.

[0005] Therefore, the present invention aims to provide a gas generator that, even with a relatively small-diameter, elongated housing, can achieve sufficient strength at the igniter end without increasing the thickness of the housing walls, while also being able to use relatively inexpensive materials and be lighter than conventional models. [Means for solving the problem]

[0006] (1) The gas generator of the present invention is characterized by comprising: a long cylindrical housing into which a gas generating agent that generates gas by combustion is loaded and into which a gas outlet for ejecting the gas is formed; 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 closing member fixed to the other end of the housing in the axial direction; an annular portion, one end of which is connected to the other end of the holder and made of a material with higher strength than the material forming the housing; and a pocket portion formed radially inward of the other end of the annular portion and into which at least a part of an external connector can be connected.

[0007] (2) In the gas generator described in (1) above, the annular portion and the pocket portion are formed separately, and it is preferable that at least one opening is formed in the annular portion, the same number of locking portions as the opening are formed on the outer circumference of the pocket portion which are locked into the opening, and the pocket portion is provided inside the annular portion with the locking portions locked into the opening.

[0008] (3) From another perspective, in the gas generator described in (1) above, the annular portion and the pocket portion may be integrally formed. [Effects of the Invention]

[0009] According to the present invention, even with a relatively small-diameter, elongated housing, it is possible to obtain a gas generator that has sufficient strength at the igniter end without increasing the thickness of the housing walls, while keeping material costs relatively low and being lighter than conventional designs. [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] This is a magnified view of the area around the holder of the gas generator shown in Figure 1. [Figure 3] (a) is a plan view of the annular section of Figure 1, and (b) is a plan view of the pocket section of Figure 1. [Figure 4] This is a cross-sectional view showing a modified example of a component of a gas generator according to an embodiment of the present invention. [Modes for carrying out the invention]

[0011] A cylinder-type gas generator according to an embodiment of the present invention will be described below with reference to Figures 1 to 3.

[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, a closing member 12 attached to the other end of the housing 10 to close the other open end of the housing 10, an annular portion 60 provided at the other end of the holder 20, and a pocket portion 70 provided radially inward of the annular portion 60.

[0013] The housing 10 is made of a metal such as steel, and consists of a long cylindrical member having a circumferential 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 flange portion 21 formed on the outer circumference of the holder 20, annular welded portions 22 and 25 formed by laser welding or the like, and a fitting portion 26 on the opposite side of the holding position of the igniter 50 into which the tip to part of a female connector (not shown) for supplying power to the igniter 50 can be fitted. The welded portion 22 is the part where the end of the housing 10 on the igniter 50 side and the surface of the flange portion 21 on the housing 10 side are welded together. The welded portion 25 is the part where the end of the annular portion 60 on the housing 10 side and the surface of the flange portion 21 on the annular portion 60 side are welded together.

[0017] As shown in FIGS. 1, 2, and 3(a), the annular portion 60 has a pair of openings 61 formed at opposing positions. Further, the annular portion 60 is made of a material that is stronger than the housing 10 and has a tensile strength of 850 MPa or more that can withstand contact with the airbag during deployment, and it can be any material as long as it can be welded to the holder 20. For example, as the material (material) used for the annular portion 60, STKM-13C, which is a carbon steel pipe for machine structures, or a carbon steel pipe for machine structures (STKM-14C, STKM-15C, STKM-16C, STKM-17C, etc.) with a higher tensile strength than STKM-13C can be mentioned.

[0018] The pocket portion 70 is made of resin, and as shown in FIGS. 1, 2, and 3(b), it has an annular fitting portion 71 that can be fitted from the middle of a female connector (not shown) for energizing the igniter 50 to the vicinity of the wiring-side end, and a pair of locking portions 72 provided on the outer periphery of the pocket portion 70 and arranged at opposing positions. The locking portion 72 is a portion where the pocket portion 70 can be locked to the annular portion 60 by fitting the pocket portion 70 into the inside of the annular portion 60 and inserting it into the opening 61.

[0019] As long as the same number of openings 61 and locking portions 72 are provided, any number of one or more can be formed. However, it is preferable that a plurality of openings 61 and locking portions 72 are provided.

[0020] The female connector is formed by the fitting portion 26 of the holder 20 and the fitting portion 71 of the pocket portion. This female connector is a portion where the male connector of a harness that transmits a signal from a collision detection means provided separately from the gas generator 100 is connected. A retainer (not shown) can be attached to the female connector. This retainer is attached to prevent the cylinder-type gas generator 100 from malfunctioning due to electrostatic discharge or the like during the transportation of the gas generator 100, etc., and the contact to the terminal pin 52 is released when the male connector of the harness is inserted into the female connector at the stage of assembling the airbag device.

[0021] As shown in FIGS. 1 and 2, an igniter 50 as an ignition means for the gas generating agent 31 is disposed at one axial end of the housing 10 (that is, the portion closer to the holder 20). Note that the igniter 50 and the holder 20 for fixing the igniter 50 have a function as an ignition means for generating a flame for burning the granular gas generating agent 31 described later.

[0022] As shown in FIGS. 1 and 2, the igniter 50 is held by the holder 20 in a state of 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 52, and a squib cup 51 (cup-shaped member) attached to the base frame. A resistor (bridge wire) is attached so as to connect the tips of the terminal pins 52 inserted into the squib cup 51, and the squib cup 51 is filled with an ignition charge so as to surround or contact this resistor. Generally, a 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, a composition composed of titanium hydride / potassium perchlorate, or a composition composed of boron / 5-aminotetrazole / potassium nitrate / molybdenum trioxide is used.

[0023] When a collision is detected, a predetermined amount of current flows through the resistor via the terminal pins 52. 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 flows through the resistor until the igniter 50 operates is 2 milliseconds or less when a nichrome wire is used as the resistor.

[0024] Furthermore, the squib cup 51 is generally made of metal or resin. A substantially cylindrical member (not shown) that covers the peripheral wall of the squib cup 51 except for the area near the tip may be crimped and fixed to the holder 20 together with the igniter 50 by a crimping portion 24. Here, the substantially cylindrical member is a directional member that directs the flame generated in the igniter 50 when in operation toward the cup-shaped member 32 (bottomed cylindrical member).

[0025] As shown in Figure 1, the internal space of the housing 10 contains a sealed space 10A containing a gas generating agent 31 and a filter 41, which are arranged in parallel in the axial direction of the housing 10.

[0026] The gas generating agent 31 is a composition that generates gas by being ignited by a flame produced by an igniter 50 and then burning. The gas generating agent 31 is generally formed as a molded body containing a fuel, an oxidizer, and additives. 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. As oxidizers, 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, etc. As nitrates, for example, sodium nitrate and potassium nitrate, etc., are preferably used. As additives, examples include binders, slag-forming agents, or combustion modifiers. Suitable binders include, for example, cellulose derivatives such as hydroxypropylene methylcellulose, metal salts of carboxymethylcellulose, organic binders such as stearate, and inorganic binders such as synthetic hydroxytalcite 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.

[0027] Furthermore, within the housing 10, the space where the gas generating agent 31 is loaded and the space where the AI ​​agent (auto-ignition agent) 33 is provided are separated by a partition member 34.

[0028] 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 32b of the cup-shaped member 32 by being sandwiched between the partition member 34 and the cup-shaped member 32. In this way, since the AI ​​agent 33 is held by the cup-shaped member 32 and the partition member 34, no special parts are required to hold the AI ​​agent 33. In addition, the partition member 34 prevents the AI ​​agent 33 from coming into contact with the gas generating agent 31.

[0029] The partition member 34 is a bottomed cylindrical member shorter than the cup-shaped member 32, comprising a cylindrical portion 34a having an opening at the end on the gas generating agent 31 side, and a bottom portion 34b provided to close the end of the cylindrical portion on the filter 41 side. The partition member 34 is press-fitted and fixed to the first cylindrical portion 32a of the cup-shaped member 32. As one modification, the partition member 34 may be inserted into the first cylindrical portion 32a of the cup-shaped member 32 and fixed to the first cylindrical portion 32a by adhesive. Alternatively, the partition member 34 may be a plate member (with an outer circumference shape that conforms to the inner wall of the housing 10).

[0030] Furthermore, the partition member 34 is provided with one or more holes (not shown). The size of each hole is predetermined (for example, set by diameter) in order to adjust the amount of flame when the AI ​​agent 33 ignites.

[0031] 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.

[0032] The cup-shaped 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 first cylindrical portion 32a, a bottom portion 32b that closes the end of the first cylindrical portion 32a on the filter 41 side, a second cylindrical portion 32c with a larger diameter than the first cylindrical portion 32a, and an annular connecting portion 32d that connects the first cylindrical portion 32a and the second cylindrical portion 32c. The first cylindrical portion 32a, the connecting portion 32d, and the second cylindrical portion 32c form a stepped shape in cross-section. The bottom portion 32b is melted or damaged by the gas generated during operation. The cup-shaped member 32 is made of, for example, a metal such as stainless steel or iron, or an alloy such as an aluminum alloy or stainless steel alloy. Furthermore, the cup-shaped member 32 is fixed to the housing 10 by forming an annular welded portion 35 from the outside of the housing 10 by laser welding (through welding) or the like, so that the filter 41 can be positioned at a predetermined position (for example, a position facing the gas outlet 11 as shown in Figure 1). Here, the first cylindrical portion 32a may be relatively thick (for example, thicker than the cylindrical portion 34a). This prevents deformation of the first cylindrical portion 32a even when the partition member 34 is press-fitted into the first cylindrical portion 32a.

[0033] As described above, by welding the cup-shaped member 32 to the housing 10, the generated gas can be bypassed between the inner wall of the housing 10 and the outer circumference of the filter 41 and prevented from leaking out to the gas outlet 11, while also ensuring a seal. In other words, the cup-shaped 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 at the bottom 32b (a portion corresponding to one end of the hollow portion 41a).

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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 towards the cup-shaped member 32 inside the housing 10.

[0038] 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 passes through the holes provided in the partition member 34, melting or damaging the portion of the cup-shaped member 32 corresponding to the hollow portion 41a at the bottom 32b, 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.

[0039] 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 inside of the gas generator 100 reaches a predetermined high temperature, the AI ​​agent 33 ignites, igniting and burning the gas generating agent 31 to generate gas. Due to the gas pressure inside the housing 10, the generated gas melts or damages the portion of the cup-shaped member 32 corresponding to the hollow portion 41a at the bottom 32b, causing it to rupture and flow into the hollow portion 41a. Subsequently, the generated gas is ejected from the gas outlet 11 to the outside of the gas generator 100 via the filter 41. 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.

[0040] (Main features of the gas generator 100) According to this embodiment, the housing 10 can be made of a relatively inexpensive material that has sufficient strength to withstand the gas pressure generated during operation. Furthermore, a material with higher strength than the housing 10, which tends to be relatively expensive, can be used only for the annular portion 60, where higher strength than the housing 10 is required. Therefore, even with a relatively small-diameter, elongated housing 10, the strength of the annular portion 60 at the end on the igniter 50 side can be sufficient without increasing the thickness of the walls of the housing 10, while keeping the overall material cost relatively low and providing a gas generator 100 that is lighter than conventional models.

[0041] Furthermore, since the annular portion 60 is made of a material with higher strength than the housing 10, it can withstand contact with the airbag when it is deployed, thus preventing damage to the retainer or female connector.

[0042] Furthermore, since the annular portion 60 and the pocket portion 70 are separate parts, the pocket portion 70 can be appropriately modified by simply changing it to a pocket portion having a mating portion that matches the shape of a retainer or female connector.

[0043] Furthermore, conventional holders required machining of the mating portion to match the complex shape of the retainer or female connector's outer shape, which tended to result in relatively high manufacturing costs. In contrast, the shape of the holder 20 in the above embodiment requires simpler machining than conventional holders, and since the pocket portion 70 is made of resin, it can be manufactured relatively inexpensively by injection molding or the like. Therefore, according to the above embodiment, component costs can be reduced compared to conventional holders.

[0044] 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 description of the embodiments above, and further includes all modifications within the meaning and scope of equivalence to the claims. For example, instead of the annular portion 60 and pocket portion 70 of the above embodiments, an annular portion 160, which is integrally formed with the annular portion and pocket portion of the above embodiments as shown in Figure 4, may be used. Note that the annular portion 160 does not have an opening or a locking portion. Furthermore, it is preferable that the annular portion 160 is made of the same material as the annular portion 60.

[0045] Furthermore, for example, the coil spring 37 in the above embodiment does not necessarily have to be provided. Also, the coil spring can be any elastic material. For example, it could be a leaf spring or a rubber material with relatively high heat resistance.

[0046] Furthermore, the filter 41 in the above embodiment is not necessarily provided, but may be provided as needed. [Explanation of Symbols]

[0047] 10 Housing 10A space 11 Gas nozzles 12. Closure member 13, 22, 25, 35 Welds 20 holders 21 Flange section 23, 26, 71, 171 Fitting parts 24 Crimping part 31 Gas generating agent 32 Cup-shaped member 32a First cylindrical part 32b, 34b bottom 32c Second cylindrical part 32d Connection part 33 AI agent 34 Partition Members 34a Cylindrical part 37 Coil springs 41 Filters 41a Hollow part 50 igniter 51 Squib Cup 60, 160 Ring section 61 Opening 70 Pocket section 72 Locking part 100 Gas Generator

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 annular portion, one end of which is connected to the other end of the holder, is made of a material with higher strength than the material forming the housing, A pocket portion is formed radially inward at the other end of the annular portion, and to which at least a part of an external connector can be connected, A gas generator characterized by having the following features.

2. The annular portion and the pocket portion are formed separately. At least one opening is formed in the annular portion, The gas generator according to claim 1, characterized in that the outer circumference of the pocket portion is formed with the same number of locking portions as the opening, which are locked into the opening, and the pocket portion is provided inside the annular portion with the locking portions locked into the opening.

3. The gas generator according to claim 1, characterized in that the annular portion and the pocket portion are integrally formed.

Images