JP7636233B2 - Gas generator - Google Patents

Description

The present invention relates to a gas generator that is incorporated into an airbag device as a passenger protection device installed in an automobile or the like, and more specifically to a so-called cylinder-type gas generator that has a long cylindrical shape.

Gas generators have been known that have a long cylindrical housing and a sealed container that contains a gas generating agent and is in contact with one end of a filter via a thin partition plate (with a hole in the center) (see, for example, Patent Document 1 below).

Patent No. 5455932

In gas generators such as those in Patent Document 1, the rupture strength (burst pressure) of the filter-side end of the sealed container and the size of the flow path in the filter for the generated gas (hereinafter, flow path size) both depend on the inner diameter of the filter or the inner diameter of the hole in the center of the partition plate. In other words, in the past, it was not possible to design the rupture strength of the filter-side end of the sealed container and the flow path size separately. Therefore, in the past, it was not easy to fine-tune the performance of the gas generator, including the collection of residue by the filter.

Therefore, the present invention aims to provide a gas generator that allows the tear strength of the filter-side end of the sealed container and the flow path size to be designed separately, making it easier to fine-tune performance than before.

(1) A gas generator of the present invention comprises: a long housing; an igniter provided at one end of the housing for igniting a gas generating agent; a filter provided on the other end side of the housing; a cylindrical member provided inside the housing between the igniter and the filter and containing the gas generating agent; a first cylindrical portion provided inside the housing between the cylindrical member and the filter and having an opening formed at an end side of the igniter; and an annular abutment portion provided on the filter side of the first cylindrical portion and abutting against an end side of the igniter of the filter. A partition member has the following features : an internal space formed between the cylindrical member and the filter by the first cylindrical portion and the abutment portion , wherein the first cylindrical portion has an inner diameter larger than an inner diameter of the filter, the opening abuts against the end side of the cylindrical member of the filter, and a hole is formed in a central portion of the abutment portion.

(2) In the gas generator of (1) above, it is preferable that the partition member further includes a second cylindrical portion extending from the inner peripheral edge of the hole and having an outer diameter equal to or smaller than the inner diameter of the filter, and that the second cylindrical portion is inserted inside the filter.

(3) From another perspective, in the gas generator of (1) above, the abutment portion may extend from the first cylindrical portion, have a cross section that tapers in diameter from the first cylindrical portion side to the filter side, and at least a portion of the abutment portion may be inserted inside the filter.

According to the present invention, it is possible to provide a gas generator in which the tear strength of the filter-side end of the sealed container and the flow path size can be designed separately, making it easy to adjust the performance.

FIG. 2 is a schematic diagram (partially omitted) showing a cross-sectional view of an internal structure of a gas generator according to an embodiment of the present invention. FIG. 2 is an enlarged schematic view showing the partition member and its surroundings in FIG. 1 . 13 is an enlarged schematic view showing the vicinity of a partition member of a gas generator according to a modified example. FIG. FIG. 11 is a schematic cross-sectional view showing a housing used in a gas generator according to another modified example.

Below, the internal structure of a cylinder-type gas generator according to an embodiment of the present invention will be described with reference to FIG. 1.

(Configuration of gas generator 100)
Gas generator 100 has a long, approximately cylindrical outer shape, and includes a housing 10, a holder 20 attached to one open end of housing 10, a blocking member 12 attached to the other end of housing 10 so as to block the other open end of housing 10, a cylindrical sealed container 34 (cylindrical member) containing gas generating agent 31, a filter 41 that collects residue of the generated gas, and a partition member 36 provided between filter 41 and sealed container 34.

The housing 10 has peripheral walls 10a, 10e and is made of a long cylindrical member with openings at both axial ends. The blocking member 12 has an annular groove portion 13 formed on the peripheral surface of the blocking member 12 so as to extend in the circumferential direction. In addition, a gas outlet 11 is provided in the peripheral wall near the end of the housing 10 on which the blocking 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 gas outlets 11 are provided along the circumferential and axial directions of the housing 10.

The blocking member 12 is made of a metal such as stainless steel, iron steel, aluminum alloy, or stainless alloy. As shown in FIG. 1, with a portion of the blocking member 12 inserted into one open end of the housing 10, the peripheral wall 10a of the housing 10 at a portion corresponding to the annular groove 13 on the peripheral surface of the blocking member 12 is narrowed radially inward (crimped) to engage with the annular groove 13, thereby crimping and fixing the blocking member 12 to the housing 10.

The holder 20 is made of a metal such as stainless steel, iron steel, aluminum alloy, or stainless alloy, and has a tapered fitting portion 23 into which the igniter 50 fits, an annular groove portion 22 formed on the outer peripheral surface extending in the circumferential direction for crimping and fixing, and a fitting portion 21 on the opposite side to the holding position of the igniter 50 into which a female connector (not shown) for supplying electricity to the igniter 50 can be fitted. The holder 20 is crimped and fixed to the housing 10 by reducing (crimping) the diameter of the peripheral wall 10e of the housing 10 in the portion corresponding to the annular groove portion 22 provided on the outer peripheral surface of the holder 20 radially inward to engage with the annular groove portion 22.

As described above, a female connector is formed in the fitting portion 21 of the holder 20. This female connector is a portion to which a 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) is attached to the female connector. This retainer is attached to prevent malfunction of the cylindrical gas generator 100 due to electrostatic discharge or the like during transportation of the gas generator 100, and contact with the terminal pin 52 is released when the male connector of the harness is inserted into the female connector at the stage of assembly to the airbag device.

As shown in FIG. 1, an igniter 50 is disposed at one axial end of the housing 10 (i.e., the portion closer to the holder 20) as a means for igniting the gas generating agent 31. The igniter 50 and the holder 20 to which the igniter 50 is fixed function as an ignition means for generating a flame for burning the granular gas generating agent 31, which will be described later.

As shown in FIG. 1, the igniter 50 is inserted into the fitting portion 23 of the holder 20 and held together with a substantially cylindrical member 53, which will be described later. More specifically, the igniter 50 includes a base frame through which a pair of terminal pins 52 are inserted and held, 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 52 inserted into the squib cup 51, and an ignition charge is filled in the squib cup 51 so as to surround or contact the resistor. Nichrome wire or the like is generally used as the resistor, and ZPP (zirconium potassium perchlorate), ZWPP (zirconium tungsten potassium perchlorate), lead tricinate, or the like is generally used as the ignition charge. In addition to the ignition charge, a transfer charge may be filled in the squib cup 51. Examples of transfer charges that can be placed at the same time as the ignition charge include a composition made of a metal/oxidizer, such as boron/potassium nitrate, a composition made of titanium hydride/potassium perchlorate, or a composition made of boron/5-aminotetrazole/potassium nitrate/molybdenum trioxide.

When a collision is detected, a predetermined amount of current flows through the resistor via the terminal pin 52. When a predetermined amount of current flows through the resistor, Joule heat is generated in the resistor, and the ignition charge begins to burn in response to this heat. The high-temperature flame generated by the combustion ruptures the squib cup 51 that contains the ignition charge. When nichrome wire is used for the resistor, the time from when the current flows through the resistor to when the igniter 50 is activated is less than 2 milliseconds.

The squib cup 51 is generally made of metal or resin. An approximately cylindrical member 53, which covers the peripheral wall of the squib cup 51 except for the vicinity of the tip, is fixed to the holder 20 by crimping together with the igniter 50 by crimping the crimping portion 24. The approximately cylindrical member 53 is a directional member that directs the direction of the flame generated in the igniter 50 toward the sealed container 34 when activated. A coil spring 54 is provided around the squib cup 51 and the approximately cylindrical member 53 along the inner wall of the housing 10. One end of this coil spring 54 abuts against the end of the lid portion 34b of the sealed container 34 described below, and the other end abuts against the end on the inside side of the holder 20.

As shown in FIG. 1, a cylindrical sealed container 34 in which a gas generating agent 31 and the like are sealed, and a filter 41 are loaded in parallel in the axial direction of the housing 10 into the internal space of the housing 10. The sealed container 34 is preferably made of a metal such as aluminum.

The sealed container 34 has a bottomed cylindrical portion 34a and a lid portion 34b, and the gas generating agent 31, the coil spring 35, the AI agent 32, the cover member 33, and the partition member 36 are arranged inside. The bottomed cylindrical portion 34a has an end portion 34c that forms the bottom. The lid portion 34b and the tip of the igniter 50 are arranged at a predetermined distance from each other. This makes it easier for the squib cup 51 to split open when the igniter 50 is activated. The thickness and/or material of the end portion 34c can also be changed to adjust it so that it either bursts or splits open when activated.

The gas generating agent 31 is an integrally molded product that is ignited by a flame generated by ignition by the igniter 50 and burns to generate gas. The gas generating agent 31 is generally formed as a molded product containing a fuel, an oxidizer, and an additive. As the fuel, for example, a triazole derivative, a tetrazole derivative, a guanidine derivative, an azodicarbonamide derivative, a hydrazine derivative, or a combination of these is used. Specifically, for example, nitroguanidine, guanidine nitrate, cyanoguanidine, 5-aminotetrazole, etc. are preferably used. As the oxidizer, for example, a basic metal hydroxide such as basic copper nitrate or basic copper carbonate, a perchlorate such as ammonium perchlorate or potassium perchlorate, an alkali metal, an alkaline earth metal, a transition metal, a nitrate containing a cation selected from ammonia, etc. are used. As the nitrate, for example, sodium nitrate, potassium nitrate, etc. are preferably used. As the additive, a binder, a slag forming agent, a combustion adjusting agent, etc. are used. As the binder, for example, cellulose derivatives such as hydroxypropylene methylcellulose, metal salts of carboxymethylcellulose, organic binders such as stearates, and inorganic binders such as synthetic hydroxytalcite and acid clay can be suitably used. As the slag former, silicon nitride, silica, acid clay, etc. can be suitably used. As the combustion regulator, metal oxides, ferrosilicon, activated carbon, graphite, etc. can be suitably used.

As shown in FIG. 1, the coil spring 35 is formed by winding in a spiral shape so that the overall appearance resembles a truncated cone shape. The coil spring 35 is provided so that one end abuts against the lid portion 34b and the other end formed in a spiral shape abuts against the gas generating agent 31 to apply an elastic force to the gas generating agent 31. Due to this bias, the gas generating agent 31 is fixed in the sealed container 34 by being sandwiched between the coil spring 35, the end of the filter 41 on the coil spring 35 side, and the bottom of the bottomed cylindrical portion 34a. The coil spring 35 is generally formed in a truncated cone shape from the igniter 50 side to the gas generating agent 31 side, which makes it easier to direct the direction of the flame emitted from the igniter 50 toward the gas generating agent 31 side.

The AI agent 32 has an auto-ignition (AI) function that automatically ignites without the operation of the igniter 50. In more detail, the AI agent 32 automatically ignites at a lower temperature than the gas generating agent 31, so that in the unlikely event of a fire or the like occurring in a vehicle or the like equipped with an airbag device or the like incorporating the gas generator 100, it is possible to prevent the induction of abnormal operation of the gas generator 100 due to external heating. In addition, a cover member 33 that holds the AI agent 32 is hermetically housed in the bottom of the sealed container 34 on the side of the blocking member 12. The cover member 33 has a plurality of holes.

As shown in FIG. 2, the partition member 36 includes a first cylindrical portion 36a, an abutment portion 36b, and a second cylindrical portion 36c. The first cylindrical portion 36a has an inner diameter larger than the inner diameter of the filter 41, and an opening is formed at the end portion on the igniter 50 side. In addition, the end portion on the igniter 50 side of the first cylindrical portion 36a abuts against the end portion 34c of the sealed container 34 so that the opening portion of the first cylindrical portion 36a faces the end portion 34c. The abutment portion 36b is provided on the filter 41 side of the first cylindrical portion 36a and is annular in shape abutting against the end portion on the igniter 50 side of the filter 41. In addition, the abutment portion 36b has a curved portion 36b1 continuously provided in the circumferential direction to form a hole portion in the center portion. The first cylindrical portion 36a and the abutment portion 36b ensure a sufficient operating space between the filter 41 and the sealed container 34 when the end 34c of the sealed container 34 ruptures or splits open during operation of the gas generator 100. Furthermore, during operation of the gas generator 100, the end 34c of the sealed container 34 ruptures or splits open with stress concentrated at position 34c1. Therefore, the end 34c of the sealed container 34 can be smoothly ruptured or split open during operation of the gas generator 100.

The second cylindrical portion 36c extends from the curved portion 36b1 of the abutment portion 36b so as to be inserted into the filter 41. The outer diameter of the second cylindrical portion 36c is equal to or smaller than the inner diameter of the filter 41. This makes it easy to fit the second cylindrical portion 36c into the filter 41, facilitating positioning of the partition member 36 during manufacture of the gas generator 100. This makes it possible to provide a gas generator 100 that is relatively easy to manufacture. Furthermore, the second cylindrical portion 36c can protect the end of the filter 41 from breakage and/or rupture of the end 34c of the sealed container 34 during operation.

The outer peripheral wall of the first cylindrical portion 36a of the partition member 36 is disposed so as to abut against the inner wall of the housing 10, and the abutting portion 36b is disposed so as to cover the end of the filter 41. This prevents the generated gas from bypassing between the inner wall of the housing 10 and the outer peripheral portion of the filter 41 and leaking out to the gas outlet 11. In other words, the partition member 36 allows the gas generated on the sealed container 34 side to flow into the filter 41 side via the second cylindrical portion 36c.

The filter 41 is made of a cylindrical member having a substantially cylindrical hollow portion 41a in the center. By using the filter 41 made of the above-mentioned cylindrical member, the flow resistance of the working gas flowing during operation is kept low, and efficient gas flow is possible. The filter 41 is made of, for example, wire material made of metal such as stainless steel or steel, or a mesh material wound or pressed. Specifically, a knitted wire mesh, a plain woven wire mesh, or an assembly of crimped woven metal wires is used. The filter 41 functions as a cooling means for cooling the gas by removing the high temperature heat of the gas when the gas generated in the sealed container 34 passes through the filter 41, and also functions as a removal means for removing slag and the like contained in the gas. Here, as a modified example of the filter 41, a filter having a labyrinth-shaped flow path formed by combining substantially cylindrical or mortar-shaped parts made of metal may be used. This allows the working gas to be redirected in various directions, allowing the gas to be cooled and slag to be removed.

In the above-mentioned embodiment of the present invention, a filter made of a so-called knitted wire mesh is used as an example, but it is also possible to use a filter made by winding punched metal or an expanded metal instead. Here, punched metal refers to a metal plate in which only openings are provided in a plate-shaped metal member (i.e., no protrusions are provided around the openings), and expanded metal refers to a metal plate in which openings are provided in the plate-shaped metal member by, for example, making staggered cuts and expanding the cuts to form a mesh-like structure. Even when such punched metal or expanded metal is used instead of the knitted wire mesh described above, the same effects as those described in the above-mentioned embodiment of the present invention can be obtained.

In addition, in the above-mentioned punched metal and expanded metal, the filter is formed of a laminate by winding a single metal plate-like member, but the configuration of the filter is not limited to this configuration. In other words, the filter may be formed of a laminate by combining different metal plate-like members in each layer, or the filter may be formed of a laminate by winding some of the layers by winding a single metal plate-like member and combining the remaining layers by winding another single metal plate-like member.

Next, the operation of the gas generator 100 described above during operation will be described. When a vehicle equipped with an airbag device incorporating the gas generator 100 of this embodiment collides, the collision is detected by a collision detection means separately provided in the vehicle, and the igniter 50 is activated based on this detection. When the igniter 50 is activated, the pressure inside the igniter 50 increases due to the combustion of the ignition charge, causing the tip of the squib cup 51 of the igniter 50 to rupture, and the flame flows from the tip of the squib cup 51 of the igniter 50 to the sealed container 34 side inside the housing 10.

The flame thus flowing in ruptures the lid 34b of the sealed container 34, and further ignites and burns the gas generating agent 31 in the sealed container 34, generating a large amount of gas. This combustion of the gas generating agent 31 increases the pressure in the sealed container 34, and the generated gas causes stress to be concentrated at the position 34c1. When the pressure in the sealed container 34 reaches a predetermined level or higher, the gas generated in the sealed container 34 ruptures or breaks the end 34c of the sealed container 34 on the blocking member 12 side, and flows into the hollow portion 41a through the inside of the partition member 36. 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, but since 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 inside of the airbag to inflate and deploy the airbag.

(Main features of the gas generator 100)
According to the present embodiment, the formation of the internal space by the first cylindrical portion 36a of the partition member 36 and the inner diameter of the filter 41 can be designed separately, and therefore the rupture strength of the end portion 34c on the filter side of the sealed container 34 and the flow path size (the inner diameter of the filter 41) can be designed separately. That is, the portion of the end portion 34c of the sealed container 34 where stress is concentrated can be easily adjusted by the thickness and the size of the inner diameter of the first cylindrical portion 36a of the partition member 36, and the size of the inner diameter of the filter 41 can be easily adjusted separately. Also, by appropriately changing the thickness of the end portion 34c of the sealed container 34, the design of the rupture strength of the end portion 34c can be adjusted more easily than in the past. Therefore, it is possible to provide a gas generator 100 in which fine adjustment of performance is easier than in the past. That is, for example, the internal pressure in the sealed container 34 during operation can be adjusted more easily than in the past (for example, reduced more easily than in the past). Furthermore, the inner diameter of filter 41 can be made smaller than before without changing the length of housing 10 (the radial thickness of filter 41 can be made thicker than before), so that a gas generator 100 can be provided that can improve the residue collection ability of filter 41 compared to before while maintaining the same size as before.

In addition, by changing the thickness and/or material of the end 34c, it is possible to adjust it so that it either bursts or splits when activated.

In addition, since the second cylindrical portion 36c can be easily fitted into the inside of the filter 41, the partition member 36 can be easily positioned during the manufacture of the gas generator 100. Therefore, a gas generator 100 that is relatively easy to manufacture can be provided.

The partition member 36 also protects the end of the filter 41 from breakage and/or rupture of the end 34c of the sealed container 34 during operation.

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

For example, a modified example of the above embodiment may be a gas generator having the configuration shown in Figure 3. A detailed description will be given below, but parts that are the same as those in the above embodiment will be given the same reference numerals with the last two digits and explanations may be omitted. Also, parts in this modified example that are not specifically described are the same as those in the above embodiment.

The gas generator of this modified example differs in that it uses a partition member 136 and a filter 141 instead of the partition member 36 and filter 41 of the above embodiment.

As shown in FIG. 3, the partition member 136 includes a first cylindrical portion 136a, an abutment portion 136b, and a second cylindrical portion 136c. The first cylindrical portion 136a has an inner diameter larger than the inner diameter of the filter 141, and an opening is formed at the end on the igniter side. In addition, the end on the igniter side of the first cylindrical portion 136a abuts against the end 134c of the sealed container 134 so that the opening of the first cylindrical portion 136a faces the end 134c. The abutment portion 136b is provided on the filter 141 side of the first cylindrical portion 136a and abuts against the end on the igniter side of the filter 141. The abutment portion 136b has a tapered shape (annular) in cross section that narrows from the first cylindrical portion 136a side to the filter 141 side. The first cylindrical portion 136a and the abutment portion 136b ensure sufficient operating space between the filter 141 and the sealed container 134 when the end 134c of the sealed container 134 ruptures or splits open during operation of the gas generator of this modified example. Furthermore, during operation of the gas generator of this modified example, the end 134c of the sealed container 134 ruptures or splits open with stress concentrated at the position 134c1. Therefore, the end 134c of the sealed container 134 can be smoothly ruptured or split open during operation of the gas generator of this modified example.

The second cylindrical portion 136c is formed continuously and integrally with the abutment portion 136b and is positioned inside the hollow portion 141a of the filter 141.

The gas generator of this modified example can achieve the same effects as the above embodiment.

As another modification, the partition member 36 in the above embodiment may have only the first cylindrical portion 36a and the abutment portion 36b, without the second cylindrical portion 36c.

As another modification, instead of the housing in the above embodiment or modification, the housing 210 shown in FIG. 4 (the housing precursor before the holder or the like is crimped and fixed) may be used. This housing 210 has two types of gas outlets 211a and 211b with different diameters, and is provided in a position facing a filter (not shown) as in the above embodiment or modification. The housing 210 also has an area A where multiple gas outlets 211a are provided, and an area B where multiple gas outlets 211b are provided. Also, by making the gas outlet 211b on the igniter side (lower side of the paper in FIG. 4) smaller in diameter than the gas outlet 211a, it is possible to make full use of the filter (not shown) similar to the above embodiment or modification provided inside the gas outlets 211a and 211b.

In addition, in the above embodiment and modified examples, the method of reducing the diameter of the housing is described using crimping as an example, but any processing method that can reduce the diameter of the housing may be used.

10, 110, 210 Housing 10a Peripheral wall 10e Peripheral wall 11, 211a, 211b Gas outlet 12 Closure member 13 Annular groove portion 20 Holder 21 Fitting portion 22 Annular groove portion 23 Fitting portion 24 Crimping portion 31, 131 Gas generating agent 32, 132 AI agent 33, 133 Cover member 34, 134 Sealed container 34a, 134a Bottomed cylindrical portion 34b Lid portion 34c, 134c End portion 35 Helical spring 36, 136 Partition member 36a, 136a First cylindrical portion 36b, 136b Abutment portion 36b1 Curved portion 36c, 136c Second cylindrical portion 41, 141 Filter 41a, 141a Hollow portion 50 Igniter 51 Squib cup 52 Terminal pin 53 Cylindrical member 54 Helical spring 100 Gas generator

Claims (3)

An elongated housing;
an igniter provided at one end of the housing for igniting the gas generating agent;
a filter provided on the other end side of the housing;
a cylindrical member provided inside the housing between the igniter and the filter, the cylindrical member containing the gas generating agent;
a partition member including: a first cylindrical portion provided inside the housing between the cylindrical member and the filter, the first cylindrical portion having an opening formed at an end portion on the igniter side; an annular abutment portion provided on the filter side of the first cylindrical portion and abutting against the end portion of the filter on the igniter side; and an internal space formed between the cylindrical member and the filter by the first cylindrical portion and the abutment portion ;
Equipped with
the first cylindrical portion has an inner diameter larger than an inner diameter of the filter, and the opening portion abuts against an end portion of the cylindrical member on the filter side;
A gas generator characterized in that a hole is formed in the center of the abutment portion. The partition member further includes a second cylindrical portion extending from an inner peripheral edge of the hole and having an outer diameter equal to or smaller than an inner diameter of the filter.
2. The gas generator according to claim 1, wherein the second cylindrical portion is inserted inside the filter. 2. The gas generator according to claim 1, characterized in that the abutment portion extends from the first cylindrical portion, has a cross section that is tapered so that its diameter decreases from the first cylindrical portion side to the filter side, and at least a portion of the abutment portion is inserted inside the filter.

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