JP7296242B2 - gas generator - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas generator that utilizes pressurized gas and is incorporated in an airbag device as an occupant protection device mounted on an automobile or the like.

Gas generators utilizing pressurized gas are, for example, driver or front passenger airbag systems, side impact airbag systems, curtain airbag systems, knee bolster systems, inflatable seatbelt systems, and pedestrian protection systems. It is used in a restraining device for automobiles, such as a device attached to the exterior of the vehicle, for example, as disclosed in Japanese Unexamined Patent Application Publication No. 2002-200012.

In gas generators that use pressurized gas, gas is sealed inside a cylindrical housing that serves as a pressurized gas chamber. The installation of the rupture disc is important because it is closed by a melting and deforming member), but it is necessary to contain the gas for the service life of the vehicle (eg 15 years).

Patent No. 2009-51236

In a gas generator that uses pressurized gas, as described above, when the gas generator is activated, the rupture disc ruptures, melts, or deforms due to a predetermined impact. Along with the outflow of the pressurized gas, fragments of the rupture disc also flowed into the airbag, possibly causing damage to the airbag.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a gas generator using pressurized gas that does not damage the airbag.

(1) The present invention comprises a cylindrical housing partially filled with pressurized gas, a partition member provided to partition the middle of the housing for enclosing the pressurized gas, and the housing. a holder provided to close the opening on the other end side of the partition member and holding an igniter capable of igniting toward the partition member, wherein the partition member It has a communication hole that communicates with the partitioned housing, and a fixed portion that is fixed so as to close the communication hole, and a part of the fixed portion can be cleaved by receiving a predetermined pressure or heat. Each of the cleavable portion of the rupture disc and the portion other than the cleavable portion of the rupture disc has a projection projecting from the rupture disc. and forming the height of the protrusion from the rupture disc at a site other than the cleavable site of the rupture disc higher than the height from the rupture disc of the protrusion at the cleavable site of the rupture disc. Thus, the thickness of the portion other than the cleavable portion of the rupture disc is formed thicker than the cleavable portion of the rupture disc.

According to the configuration (1) above, it is possible to provide a gas generator that includes a partition member having a rupture disc, a portion of which is cleavable and the other portion of which is fixed. Therefore, the rupture disc according to the gas generator of the present invention can prevent the rupture disc from bursting and scattering fragments. As a result, according to the present invention, it is possible to prevent the airbag from being damaged in the gas generator using pressurized gas.

(2) In the gas generator of (1) above, the rupture disc is preferably fixed to the partition member by general welding such as laser welding, friction welding, or resistance welding. The resistance welding is preferably projection welding or spot welding.

According to the configuration (2) above, the rupture disc can be easily provided on the partition member.

(3) In the gas generator of (1) or (2) above, when there are a plurality of cleavable portions of the rupture disc and a plurality of portions other than the cleavable portion of the rupture disc, the rupture disc and the portion of the rupturable disc other than the cleavable portion are preferably provided substantially symmetrically with respect to the center of the partition member.

According to the configuration (3) above, when it is actuated, the force generated by the outflow of gas can be offset at the rupturable portions of the rupture discs provided substantially symmetrically.

(4) In the gas generators of (1) to (3) above, it is preferable that the rupture disc is arranged on the pressurized gas chamber side of the partition member.

The rupture disc is normally pressurized by the gas in the pressurized gas chamber. Therefore, according to the above configuration (4), even if it is peeled off, it can be prevented from being delivered from the communication hole. Also, if the rupture disc is placed on the side opposite to the pressurized gas chamber side of the partition member, a very strong bond is required to prevent it from coming off while withstanding the pressure of the pressurized gas. In this case, the costs are relatively high. However, according to the above configuration (4), it is sufficient to bond with a predetermined strength or more (for example, a bond with a strength enough to hold the gas in the pressurized gas chamber so as not to leak until the next replacement). Cost can be suppressed compared to the case where the rupture disc is arranged on the side opposite to the pressurized gas chamber side of the partition member.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows the internal structure of the gas generator which concerns on embodiment of this invention which represented one part with the cross section. (a) is a plan view of a partition member in the gas generator of FIG. 1, and (b) is a cross-sectional view taken along line AA of (a). FIG. 2 is a diagram showing a part of the manufacturing process of the gas generator of FIG. 1; FIG. 2 is a diagram showing a part of the manufacturing process of the gas generator of FIG. 1; (a) is a plan view showing Modification 1 of the partition member in the gas generator of FIG. 1, and (b) is a cross-sectional view taken along line BB of (a). (a) is a plan view showing Modification 2 of the partition member in the gas generator of FIG. 1, and (b) is a cross-sectional view taken along line CC of (a).

The internal structure of a gas generator according to an embodiment of the present invention will be described below with reference to FIGS. 1 to 4. FIG.

(Configuration of gas generator 100)
The gas generator 100 has an elongated, substantially cylindrical outer shape, and includes a housing 10, a holder 20 attached to one open end of the housing 10, and a holder 20 that closes the other open end of the housing 10. and a closure member 40 attached to the other end of housing 10 .

The housing 10 is a long cylindrical member having openings at both ends in the axial direction. The closing member 40 is a disk-shaped member having a predetermined thickness, and its peripheral surface is crimped and fixed. In addition, the closing member 40 is provided with a through hole 41 substantially at the center. The through hole 41 is provided so as to communicate with the internal space of a cylindrical member 42 provided on the outer side of the closing member 40, and is closed by a rupture disk 43 before actuation. The rupture disc 43 is welded so as to block the through hole 41, and is designed to rupture or split when a predetermined pressure is applied.

The tubular member 42 has a diameter smaller than that of the housing 10 and has a gas ejection port 44 . The gas ejection port 44 is a hole for ejecting gas generated inside the gas generator 100 to the outside, and is provided in plural along the circumferential direction and the axial direction of the tubular member 42 .

The closing member 40 and the tubular member 42 are made of metal such as stainless steel, iron steel, aluminum alloy, or stainless alloy, and are disk-shaped members having a predetermined thickness. Then, in a state in which the closing member 40 is inserted into one open end of the housing 10, the peripheral wall of the housing 10 at the portion corresponding to the peripheral surface of the closing member 40 is reduced in diameter in the radial direction (crimped). , the closing member 40 is crimped and fixed to the housing 10 . Alternatively, the closing member 40 and the housing 10 are welded and fixed by general welding such as laser welding, friction welding, and resistance welding.

The holder 20 is made of a metal such as stainless steel, iron steel, aluminum alloy, or stainless alloy, and in a state in which a part of the holder 20 is inserted into the other open end of the housing 10, the outer peripheral surface of the holder 20 The holder 20 is crimped and fixed to the housing 10 by reducing (crimping) the corresponding portion of the peripheral wall of the housing 10 radially inward. Alternatively, the closing member 40 and the housing 10 are welded and fixed by general welding such as laser welding, friction welding, and resistance welding.

An igniter 21 as a means for igniting the gas generating agent 30 is arranged in the holder 20 . The igniter 21 and the holder 20 fixing the igniter 21 function as ignition means for generating a flame for burning the granular gas generating agent 30, which will be described later.

The igniter 21 is inserted into the hollow opening of the holder 20 and fixed by the resin molded portion 22 .

More specifically, the igniter 21 includes a base frame through which a pair of terminal pins 23 are inserted and held, and a squib cup 21a attached to the base frame. A resistor (bridge wire) is attached to connect the tips of the pins 23, and an ignition charge is filled in the squib cup 21a so as to surround or contact the resistor. A 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 igniter. The squib cup 21a may be filled with not only the igniter but also a transfer charge. a composition consisting of titanium hydride/potassium perchlorate, or a composition consisting of boron/5-aminotetrazole/potassium nitrate/molybdenum trioxide. Squib cups are generally made of metal or plastic.

When a collision is detected, a predetermined amount of current flows through the resistor via the terminal pin 23 . When a predetermined amount of current flows through the resistor, Joule heat is generated in the resistor, and the igniter starts burning upon receiving this heat. A high-temperature flame generated by the combustion ruptures the squib cup 21a containing the ignition charge. The time from when the current flows through the resistor until the igniter 21 is activated is 2 milliseconds or less when the nichrome wire is used as the resistor.

As shown in FIG. 1, the internal space of the housing 10 is provided with a working gas generation chamber 12 containing a gas generating agent 30 and a pressurized gas chamber 13 containing pressurized gas. . The working gas generation chamber 12 and the pressurized gas chamber 13 are separated by a partition member 11 .

As shown in FIG. 3, the gas generating agent 30 is a long cylindrical integrally molded product that is ignited by flame generated by the igniter 21 and combusts to generate gas. Also, the gas generant 30 is generally formed as a molded body containing fuel, oxidant and additive. As the fuel, for example, a triazole derivative, a tetrazole derivative, a guanidine derivative, an azodicarbonamide derivative, a hydrazine derivative, or a combination thereof is used. Specifically, nitroguanidine, guanidine nitrate, cyanoguanidine, 5-aminotetrazole and the like are preferably used. Examples of oxidizing agents include basic metal hydroxides such as basic copper nitrate and basic copper carbonate, perchlorates such as ammonium perchlorate and potassium perchlorate, alkali metals, alkaline earth metals, Nitrates containing cations selected from transition metals and ammonia are used. As nitrates, for example, sodium nitrate, potassium nitrate and the like are preferably used. Additives include binders, slag forming agents, combustion modifiers, and the like. Suitable binders include cellulose derivatives such as hydroxypropylene methyl cellulose, organic binders such as metal salts of carboxymethyl cellulose and stearates, and inorganic binders such as synthetic hydroxytalcite and acid clay. As the slag forming agent, silicon nitride, silica, acid clay, etc. can be suitably used. Also, metal oxides, ferrosilicon, activated carbon, graphite, and the like can be suitably used as combustion modifiers.

The partition member 11 is made of metal such as stainless steel, iron steel, aluminum alloy, or stainless alloy, and as shown in FIGS. It is a thing. The base material 11a has a planar circular shape with a communication hole 11c on one surface side, and a rupture disk 11b is welded and fixed on the other surface side at a welding point 11d by projection welding and spot welding. . The joining of the rupture disc 11b to the base material 11a may be performed only by projection welding or only by spot welding.

As shown in FIGS. 2(a) and 2(b), the rupture disc 11b has projections 11d1 and 11d2 on each half circumference of the circular edge. The positions of the protrusions 11d1 and 11d2 correspond to the welding points 11d. The thickness (height) of the protrusion 11d1 is about 0.7 mm to 1.1 mm, and the thickness (height) of the protrusion 11d2 is about 0.8 mm to 1.2 mm. It is formed thicker than the thickness of 11d1. Therefore, the welded portion of the protrusion 11d1 of the rupture disc 11b is weaker than the welded portion of the protrusion 11d2. It is easier to split (easier to peel) than the welded part.

The pressurized gas chamber 13 is filled with an inert gas such as nitrogen, argon, or helium at a maximum pressure of about 90 MPa. Moreover, the pressurized gas chamber 13 can communicate with the outside through the through hole 41 and the gas ejection port 44 when the rupture disc 43 ruptures during operation.

A female connector (not shown) is attached to the end of the gas generator 100 where the holder 20 is arranged. This female connector is a portion to which a male connector of a harness for transmitting a signal from collision detection means provided separately from the gas generator 100 is connected. A shorting clip (not shown) is attached to the female connector as needed. This shorting clip is attached to prevent the gas generator 100 from malfunctioning due to electrostatic discharge or the like during transportation of the gas generator 100, etc., and is attached to the harness at the stage of assembly to the airbag system. The contact with the terminal pins 23 is released by inserting the male connector into the female connector.

Next, an example of a method for manufacturing the gas generator 100 described above will be described.

First, after the closing member 40 is press-fitted into the opening on the other end side of the housing 10, it is attached using general welding such as laser welding, friction welding, and resistance welding. (Fig. 3(a), (b)). Then, the base material 11a inserted from the opening on one end side of the housing 10 is attached to the portion 10a of the inner wall of the housing 10 (FIGS. 3(a) and 3(b)). In addition, the inner wall of the housing 10 has a smaller diameter than the one end side of the housing 10 at a portion 10a. Therefore, by pushing the base material 11a into the portion 10a, the base material 11a is fixed in a state in which it bites into the inner wall of the housing 10 without any gap (FIG. 3(c)). Here, as a modified example, a step of providing the base material 11a in front of the closing member 40 may be employed.

Next, a resistance welder 50 is used to weld the rupture disc 11b to the base material 11a. Specifically, it is as follows. First, the resistance welder 50 is installed in the opening on one end side of the housing 10 (Fig. 4(a)). Subsequently, resistance welding is performed while pressing the rupture disk 11b temporarily fixed to the tip of the electrode portion 51 against the base material 11a (FIG. 4(b)).

A ring-shaped protrusion (not shown) is provided on the circumference of the rupture disc 11b on the substrate 11a side. In addition, this protrusion is divided into a higher protrusion and a lower protrusion in each semicircular portion. During welding, heat is concentrated on the protrusions, thereby softening and crimping progress, and the lower protrusions are formed as protrusions 11d1, and the higher protrusions are formed as protrusions 11d2 (see FIG. 2). be.

Next, after loading the gas generating agent 30 from the opening on the one end side of the housing 10 (FIG. 4(c)), the holder 20 to which the igniter 21 is attached is crimped to the opening on the one end side of the housing 10. fixed. Through these series of steps, the gas generator 100 shown in FIG. 1 is completed.

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 according to the present embodiment collides, the collision is detected by collision detection means separately provided in the vehicle, and the igniter 21 works. When the igniter 21 is activated, the pressure inside the igniter 21 increases due to the combustion of the igniter, which causes the tip of the squib cup 21a of the igniter 21 to rupture, and the flame spreads from the tip of the squib cup 21a of the igniter 21 to the outside (activation It flows out to the gas generation chamber 12).

The flame that flows in this way ignites and burns the gas generating agent 30 to generate a large amount of gas. Combustion of the gas generating agent 30 increases the pressure in the working gas generating chamber 12, and the generated gas causes the rupture plate 11b provided in the partition member 11 to split the welded portion 11d on the protruding portion 11d1 side. . Here, the welded portion 11d of the rupture disc 11b on the protruding portion 11d2 side is not split and remains fixed.

The generated gas flows into the pressurized gas chamber 13 from the cleaved portion of the rupture disc 11b through the communication hole 11c. At this time, slag contained in the gas is removed by the rupture disc 11b. The gas that has flowed into the pressurized gas chamber 13 further pressurizes the pressurized gas in the pressurized gas chamber 13 to burst the rupture disc 43 . The gas generated in the working gas generation chamber 12 and the pressurized gas in the pressurized gas chamber 13 are jetted out of the gas generator 100 from the gas jetting port 44 through the through hole 41 . The gas ejected from the gas ejection port 44 in this manner is guided into the interior of the airbag to inflate and deploy the airbag.

(Main features of gas generator 100)
According to this embodiment, it is possible to provide gas generator 100 having partition member 11 having rupturable disc 11b, a part of which can be cleaved and the other part of which remains fixed. Therefore, the rupture disc 11b of the gas generator 100 can be prevented from being ruptured to generate fragments. As a result, according to the gas generator 100, the airbag is not damaged during operation.

Further, according to the present embodiment, the rupture disc 11b can be easily provided on the base material 11a.

Further, according to the present embodiment, it is possible to provide a hybrid gas generator 100 that utilizes not only the pressurized gas but also the gas generating agent. When the gas generating agent 30 is burned by the igniter 21 during operation of the gas generator 100, slag (residue) is generated. Slag (residue) collides with the plate and becomes trapped. Therefore, according to the gas generator of the present invention, slag (residue) can be collected.

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

For example, when there are multiple cleavable sites of the rupture disc and multiple sites other than the cleavable site of the rupture disc, the cleavable site of the rupture disc and other sites other than the cleavable site of the rupture disc may be provided substantially symmetrically with respect to the center of the partition member. Specific examples include those shown in FIG. 5 or FIG. 6, and each will be specifically described below. 5 and 6, the description of the same parts as the partition member 11 of the above-described embodiment will be omitted unless otherwise specified.

In the partition member 111 shown in FIG. 5, two protrusions 111d1 facing each other and two protrusions 111d2 facing each other are formed with respect to the center, and the protrusions 111d1 and 111d2 are arranged alternately on the circumference, which is different from the above embodiment. When the gas generator using the partition member 111 is operated, when the cleavable portions (welded portions of the two protrusions 111d1) provided substantially symmetrically on the rupture disc are cleaved, the force generated by the outflow of gas ( force generated by gas ejection) can be offset.

In the partition member 211 shown in FIG. 6, a plurality of pairs of protrusions 211d1 and a pair of protrusions 211d2 are formed to face each other with respect to the center, and the plurality of protrusions This embodiment differs from the above-described embodiment in that the portion 211d1 and the plurality of protrusions 211d2 are alternately arranged in parallel on the circumference. When the gas generator using the partition member 211 is operated, when the cleavable portions (welded portions of a plurality of pairs of protrusions 211d1) provided substantially symmetrically on the rupture disc are cleaved, gas is generated by outflow Forces (forces generated by gas eruptions) can be offset.

Moreover, in the above embodiment, the gas generating agent is used, but the present invention is not limited to this. For example, the heat and pressure of the flame generated by the operation of the igniter may be used to split the rupturable portion of the rupture disc (so-called stored method), or the igniter may be used to burn the gas generating agent. It is also possible to use gas pressure to operate a piston or the like, and to physically cleave the rupturable portion of the rupture disc with the operated piston (so-called reverse flow method).

Further, instead of the rupture disc 43 in the above embodiment, a rupture disc 11b may be applied.

Further, although the peripheral shape of the rupture disc 11b in the above embodiment is circular, it is not limited to this, and may be, for example, an elliptical shape, a triangular shape, a polygonal shape such as a quadrangle, or the like.

Moreover, although the rupture disc 11b in the above embodiment was welded to the base material 11a on the working gas generation chamber 12 side, it may alternatively be welded to the pressurized gas chamber 13 side of the base material 11a. As a result, even if the rupture disc 11b is peeled off during normal operation, it can be prevented from being delivered from the communication hole 11c. Also, if the rupture disc 11b is arranged on the side opposite to the pressurized gas chamber side of the base material 11a (the side of the working gas generation chamber 12), it will not come off while withstanding the pressure of the pressurized gas. A very strong bond is required, but in this case the costs are relatively high. However, if the rupture disc 11b is provided on the pressurized gas chamber side of the base material 11a, bonding with a predetermined strength or more (for example, holding so that the gas in the pressurized gas chamber 13 does not leak until the next replacement) The cost can be reduced compared to the case where the rupture disc 11b is arranged on the side opposite to the pressurized gas chamber 13 side (working gas generation chamber 12 side) of the base material 11a. can be done.

Further, the rupture disc 11b in the above embodiment was welded to the base material 11a and provided in the housing 10, but instead of this, it is welded directly to the inner wall of the housing 10 without using the base material 11a. may be provided.

10 Housing 11, 111, 211 Partition member 11a Base material 11b Rupture disc 11c Communication hole 11d Welding points 11d1, 11d2, 111d1, 111d2, 211d1, 211d2 Protrusion 12 Working gas generation chamber 13 Pressurized gas chamber 20 Holder 21 Ignitor 21a Squib cup 22 Resin molded portion 23 Terminal pin 30 Gas generating agent 40 Closing member 41 Through hole 42 Cylindrical member 43 Rupture plate 44 Gas ejection port 50 Projection welder 51 Electrode unit 100 Gas generator

Claims (4)

A cylindrical housing partly filled with a pressurized gas, a partition member provided to partition the middle of the housing for enclosing the pressurized gas, and an opening on the other end side of the housing a holder provided to close the part and holding an igniter capable of igniting toward the partition member,
The partition member has a communication hole communicating with the partitioned housing and a fixed portion fixed to close the communication hole. It has a rupture disc, a part of which is a cleavable site,
Each of the cleavable portion of the rupture disc and the portion other than the cleavable portion of the rupture disc has a protrusion projecting from the rupture disc,
forming the height of the protrusion from the rupture disc at a site other than the cleavable site of the rupture disc higher than the height from the rupture disc of the protrusion at the cleavable site of the rupture disc A gas generator characterized in that the thickness of the portion of the rupture disc other than the cleavable portion is formed to be thicker than the cleavable portion of the rupture disc. 2. The gas generator according to claim 1, wherein the rupture disc is fixed to the partition member by laser welding, friction welding, or resistance welding. When there are a plurality of cleavable sites of the rupture disc and a plurality of sites other than the cleavable site of the rupture disc,
2. The cleavable portion of the rupture disc and the portion other than the cleavable portion of the rupture disc are provided substantially symmetrically with respect to the center of the partition member. 2. The gas generator according to 2. The gas generator according to any one of claims 1 to 3, wherein the rupture disc is arranged on the pressurized gas chamber side of the partition member.

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