Rupture device and gas generator

Abstract

The purpose of the present disclosure is to provide a technique capable of easily rupturing a burst plate. This rupture device includes: a burst plate that has a first surface and a second surface on the opposite side from the first surface, and closes the opening of a container filled with pressurized gas, the burst plate having a fragile part on at least one surface of the first surface and the second surface of the burst plate, the fragile part having a start point and an end point that are located at different positions and having an extension region between the start point and the end point, the extension region having an annular shape including a curved part or a straight line part or a curved part and a straight line part; and an igniter that includes an ignition part on the tip side, the ignition part facing a rupture starting point region that is a part of the extension region of the fragile part excluding the start point and the end point so that rupture starts from the rupture starting point region and the distance from the extension region becomes indefinite over the outer peripheral part of the ignition part.

Description

Cleavage devices and gas generators

[0001] The present invention relates to a cleaving device and a gas generator.

[0002] BACKGROUND ART Conventionally, there has been known a gas generator that stores pressurized gas in a container and supplies the pressurized gas to an air bag or the like by rupturing a rupture disk that closes an opening of the container (see, for example, Patent Document 1).

[0003] U.S. Patent No. 6,361,070

[0004] If the rupture disc that closes the opening of the container cannot be reliably ruptured, a sufficient volume of pressurized gas cannot be supplied to the outside.

[0005] An object of the technology of the present disclosure is to provide a technology that allows a rupture disc to be easily ruptured.

[0006] (Aspect 1) A rupture device comprising: a rupture disc having a first surface and a second surface opposite to the first surface, the rupture disc closing an opening of a container filled with pressurized gas; a fragile portion formed on at least one of the first surface and the second surface of the rupture disc, the fragile portion having a start point and an end point disposed at different positions, and an extended region between the start point and the end point formed in an annular shape including a curved portion, a straight portion, or both a curved portion and a straight portion; and an ignition portion including an ignition portion on a tip side, the ignition portion facing a rupture initiation region that is a part of the extended region excluding the start point and the end point of the fragile portion, and an igniter disposed such that a distance from the extended region is variable along the outer periphery of the ignition portion so that rupture starts from the rupture initiation region. (Aspect 2) In the rupture device according to Aspect 1, the rupture disc may be ruptured by a load being applied to the rupture initiation region by combustion products generated by activation of the igniter, and the rupture may progress along the extension region toward the start point and the end point. (Aspect 3) In the rupture device according to Aspect 1 or 2, the igniter may be disposed in a position where the center of the ignition part does not overlap with the center of the extension region of the fragile part when viewed from the axial direction of the ignition part. (Aspect 4) In the rupture device according to any of Aspects 1 to 3, when viewed from the axial direction of the ignition part, a part of the outer periphery of the ignition part may be outside the extension region of the fragile part. (Aspect 5) The rupturing device according to any one of Aspects 1 to 4, wherein the igniter is disposed so that a center of the ignition part and a center of the extension region of the weakened part overlap when viewed from the axial direction of the ignition part, and the extension region may extend in a concave shape toward the center of the rupture disc when viewed from the axial direction of the ignition part. (Aspect 6) The rupturing device according to any one of Aspects 1 to 5, wherein stress dispersion points are formed at the start point and the end point of the weakened part and stop rupture that has progressed from the rupture initiation region. (Aspect 7) The rupturing device according to Aspect 6, wherein the stress dispersion points may be deflection parts of the weakened part that extend outward from the center of the extension region of the weakened part.(Aspect 8) The rupturing device according to any one of Aspects 1 to 7, wherein the rupture disc is provided in a region overlapping with the ignition part when viewed from the axial direction of the ignition part, and has an inclined portion that is inclined when viewed from a direction perpendicular to the axial direction of the ignition part, and the rupture initiation region may be located on the inclined portion. (Aspect 9) The rupturing device according to any one of Aspects 1 to 8, wherein in the fragile part, the rupture initiation region may be located closer to the ignition part than the start point and the end point. (Aspect 10) The rupturing device according to any one of Aspects 1 to 9, wherein the rupture initiation region may be located at a position where the linear distance from the center of the ignition part to the extension region is shortest when viewed from the axial direction of the ignition part. (Aspect 11) The rupturing device may be a gas generator including the rupture device according to any one of Aspects 1 to 7.

[0007] The contents described in the means for solving the problems can be combined as much as possible within the scope of the problems and technical ideas of this disclosure.

[0008] According to the present disclosure, the rupture disc can be easily ruptured.

[0009]

[0033] Fig. 1 is a cross-sectional view in the axial direction of a gas generator according to the first embodiment. Fig. 2 is a plan view of a rupture disc, as seen from above in the axial direction of the gas generator. Fig. 3 is a plan view of a rupture disc of a gas generator according to a comparative example, as seen from above in the axial direction of the gas generator. Fig. 4 is a diagram showing stress distribution in the rupture disc of the gas generator according to the first embodiment. Fig. 5 is a diagram showing stress distribution in the rupture disc of the gas generator according to the comparative example. Fig. 6 is a plan view of the rupture disc, as seen from above in the axial direction of the gas generator. Fig. 7 is a diagram showing stress distribution in the rupture disc of a gas generator according to a modified example. Fig. 8 is a plan view of a rupture disc of a gas generator according to the second embodiment, as seen from above in the axial direction of the gas generator. Fig. 9 is a plan view of a rupture disc of a gas generator according to the third embodiment, as seen from above in the axial direction of the gas generator. Fig. 10 is a cross-sectional view in the axial direction of a gas generator according to the fourth embodiment. Fig. 11 is a plan view of a rupture disc of a gas generator according to the fourth embodiment, as seen from above in the axial direction of the gas generator.

[0010] <Embodiment 1> A gas generator according to Embodiment 1 of the present disclosure will be described below with reference to the drawings. Note that each configuration and combination thereof in the embodiment is merely an example, and addition, omission, substitution, and other modifications of configurations are possible as appropriate within the scope of the gist of the present disclosure. The present disclosure is not limited by the embodiment, but is limited only by the scope of the claims.

[0011] In this embodiment, a gas generator equipped with a rupture device for rupturing a rupture disc will be described as an example. The gas generator is used to supply gas to airbags and seat belt retractors used in vehicles and various safety devices, shock absorbers and protective devices, or to fluid discharge devices or devices that utilize gas expansion.

[0012] FIG. 1 is an axial cross-sectional view of a gas generator 1 according to this embodiment. In FIG. 1 , a central axis C1 of gas generator 1 is shown by a dashed-dotted line. Gas generator 1 includes a metal container 2 having a cylindrical external shape. The container 2 is hollow, and a gas-filled chamber 3 that is filled with pressurized gas is formed within container 2. Container 2 serves as a housing for forming gas-filled chamber 3 therein. One axial end of container 2 is closed, and a circular opening 4 is formed in the center of that end. Pressurized gas is filled into gas-filled chamber 3 through opening 4. After the pressurized gas has been filled, opening 4 is closed by a seal pin 5. Seal pin 5 is made of the same metal as container 2, and is fixed to container 2 by welding or the like. This enables seal pin 5 to close opening 4. The pressurized gas filled into gas-filled chamber 3 may be a known gas such as argon or helium, or a mixture thereof. In the following description, one end of the container 2 is referred to as the upper side of the gas generator 1 , and the other end of the container 2 is referred to as the lower side of the gas generator 1 .

[0013] An opening 6 that is entirely open is formed on the other end side of the container 2, and a metal igniter housing 7 is inserted through the opening 6 of the container 2. The igniter housing 7 is welded to the container 2 around the entire circumference to close the opening 6 so that the pressurized gas does not leak from the gas filling chamber 3. The igniter housing 7 is a housing for accommodating an igniter 9 therein. The igniter housing 7 has a rupture disc portion 7A (an example of a "rupture disc" in the present disclosure) disposed opposite one end side of the container 2, a peripheral wall portion 7B extending from the periphery of the rupture disc portion 7A to the lower side of the gas generator 1, and an expanded-diameter peripheral wall portion 7C that has a larger diameter than the peripheral wall portion 7B and extends to the lower side of the gas generator 1. The rupture disc portion 7A, the peripheral wall portion 7B, and the expanded-diameter peripheral wall portion 7C are integrally formed. The rupture disk 7A has a plate-like shape with a first surface 70A facing the gas-filled chamber 3 and a second surface 70B opposite the first surface 70A, and closes the opening 6. The peripheral wall 7B is formed with a plurality of gas discharge ports 8. The gas discharge ports 8 are through-holes that communicate between the inside and outside of the igniter housing 7.

[0014] An igniter 9 is disposed inside the igniter housing 7. The igniter 9 has an ignition portion 9A disposed at the tip end thereof and containing an ignition charge, a holding portion 9B that holds the ignition portion 9A, and a conductive pin 9C that applies current to the ignition portion 9A. The igniter 9 is of an electric ignition type that burns the ignition charge in the ignition portion 9A by an ignition current supplied from the conductive pin 9C. The ignition portion 9A has a cup shape and is disposed so that its bottom faces the rupture disc portion 7A. An ignition charge is accommodated inside the ignition portion 9A.

[0015] The retaining portion 9B is made of resin and covers the lower periphery of the ignition portion 9A to hold the ignition portion 9A. The retaining portion 9B is formed by injection molding a resin material during the manufacturing process of the igniter 9. A resin material that has excellent heat resistance, durability, corrosion resistance, etc. after hardening can be suitably used as the resin material for the retaining portion 9B. Examples of such resin materials include thermoplastic resins such as polybutylene terephthalate resin, polyethylene terephthalate resin, polyamide resin, polypropylene sulfide resin, and polypropylene oxide resin, as well as thermosetting resins such as epoxy resin.

[0016] The pair of conductive pins 9C are electrically insulated from each other, and a bridge wire is connected to the pair of conductive pins 9C inside the ignition unit 9A. An ignition charge contained inside the ignition unit 9A is in contact with the bridge wire connected to the pair of conductive pins 9C. The ignition charge is ignited and burns by the heat generated by the bridge wire, thereby generating combustion products. In this way, the igniter 9 burns the ignition charge and releases the combustion products.

[0017] The igniter 9 is fixed by a metal igniter collar 10. The igniter collar 10 is formed of metal and surrounds and fixes the retaining portion 8B. The upper side of the igniter collar 10 is crimped to the retaining portion 8B, thereby fixing the igniter collar 10 to the retaining portion 9B. The lower side of the igniter collar 10 extends to the inner wall of the igniter housing 7, and the igniter collar 10 is fixed to the igniter housing 7 by welding its lower end to the igniter housing 7. In this manner, the igniter 9 is fixed to the igniter housing 7 via the metal igniter collar 10. The igniter 9 is fixed within the igniter housing 7 so that the central axis of the ignition portion 9A coincides with the central axis of the gas generator 1. The igniter collar 10 is integrated with a resin support portion 11. The resin used for the support portion 11 may be the same as the resin used for the retaining portion 9B of the igniter 9. Furthermore, a resin different from that used for holding portion 9B can be used for support portion 11. Igniter collar 10 may be an integrally formed product embedded in support portion 11. Furthermore, by using metal for support portion 11 and forming igniter collar 10 and holding portion 9B from an integral resin, support portion 11 and igniter 9 may be integrally molded with injected resin.

[0018] A transfer charge may be accommodated in the space 13 surrounding the ignition unit 9A. A known transfer charge containing, for example, nitroguanidine (34% by weight) or strontium nitrate (56% by weight) may be used as the transfer charge. Alternatively, known black powder (boron saltpeter) may be used as the transfer charge. The transfer charge is filled in a container and may be disposed adjacent to the ignition unit 9A, or may be disposed integrally with the ignition unit 9A in a layered configuration.

[0019] A filter 12 is also disposed so as to surround the space 13. The filter 12 has a cylindrical shape and is disposed between the space 13 and the gas outlet 8. The filter 12 is formed into a cylindrical shape using a laminated wire mesh or the like. The filter 12 is disposed to collect combustion residues of the ignition charge and transfer charge and to cool the combustion gas. The outer peripheral surface of the filter 12 is disposed opposite the inner wall of the igniter housing 7, and a gap 14 serving as a gas flow path is formed between the outer peripheral surface of the filter 12 and the inner wall of the igniter housing 7. The formation of the gap 14 makes it easier for the entire surface of the filter 12 to be used for cooling and residue collection.

[0020] In gas generator 1 according to the present embodiment configured as described above, when igniter 9 is activated, the ignition charge contained in ignition portion 9A ignites and burns, and the resulting flame ruptures rupture disk 7A disposed opposite ignition portion 9A. This causes the pressurized gas filled in gas-filled chamber 3 to pass from space 13 through filter 12 and be released to the outside through gas outlet 8. In this way, gas generator 1 can supply pressurized gas to the outside.

[0021] In the gas generator 1 according to the present embodiment, a rupture device is configured by the rupture disc portion 7A and the igniter 9. The rupture device is filled with pressurized gas, and supplies the pressurized gas to the outside by rupturing the rupture disc portion 7A when the gas generator 1 is activated.

[0022] Fig. 2 is a plan view of the rupture disc 7A as seen from above in the axial direction of the gas generator 1. The rupture disc 7A has a circular planar shape when seen from above in the axial direction of the gas generator 1. In Fig. 2, the outer periphery of an ignition portion 9A disposed below the rupture disc 7A is shown by a dotted line. In this embodiment, a fragile portion 71 is formed on a first surface 70A of the rupture disc 7A. The fragile portion 71 is a portion where the rupture disc 7A actually ruptures, and has a start point 72, an end point 73, an extension region 74, and rupture initiation regions 75 and 76. The extension region 74 includes the rupture initiation regions 75 and 76. The fragile portion 71 is a portion that is thinner than other portions, and specifically, is a groove formed in the rupture disc 7A. The fragile portion 71 has a start point 72 and an end point 73 located at different positions, and an extension region 74 is formed in an annular shape between the start point 72 and the end point 73. The extension region 74 extends in an annular shape from the start point 72 to the end point 73, including both curved and straight portions. The center of the annular extension region 74 coincides with the central axis C1. That is, the igniter 9 is arranged such that the center of the ignition portion 9A and the center of the extension region 74 overlap when viewed from the axial direction of the ignition portion 9A. The extension region 74 may be formed in an annular shape including curved portions, straight portions, or both curved and straight portions. Crack initiation regions 75 and 76 are formed in the middle of the extension region 74. The crack initiation regions 75 and 76 are regions that serve as the initiation points for cleavage and are the regions of the extension region 74 that are closest to the ignition portion 9A. When viewed from the axial direction of the ignition portion 9A of the extension region 74, the portions extending in a concave shape toward the center of the rupture disc portion 7A are rupture initiation regions 75 and 76.

[0023] The ignition portion 9A is disposed opposite the rupture disc portion 7A so that rupture starts from rupture initiation regions 75, 76. Here, the igniter 9 is disposed so that the distance between the ignition portion 9A and the extension region 74 of the fragile portion 71 is variable over the outer periphery of the ignition portion 9A. The distance between the ignition portion 9A and the extension region 74 is not constant from the start point 72 to the end point 73, and is closest at the rupture initiation regions 75, 76. The rupture initiation regions 75, 76 are disposed at positions where the linear distance from the center of the ignition portion 9A to the extension region 74 is shortest when viewed from the axial direction of the ignition portion 9A. The center of the ignition portion 9A coincides with the central axis C1 of the gas generator 1. Therefore, the rupture initiation regions 75, 76 may be formed so as to overlap with the dotted line indicating the outer periphery of the ignition portion 9A in FIG. 2 , or may extend beyond the dotted line and at least a portion thereof may extend inward.

[0024] When the gas generator 1 equipped with such a cleavage device is activated, the igniter 9 is activated, and combustion products generated therefrom apply loads to the cleavage initiation regions 75, 76, causing cleavage to occur along the extension region 74. At this time, cleavage progresses between the cleavage initiation regions 75 and 76, from the cleavage initiation region 75 toward the start point 72, and from the cleavage initiation region 76 toward the end point 73. As a result, the pressurized gas filled in the gas-filled chamber 3 is discharged from the gas discharge port 8.

[0025] 3 is a plan view of a rupture disc portion 700A of a gas generator according to a comparative example, viewed from above in the axial direction of the gas generator. The gas generator according to the comparative example has the same configuration and structure as the gas generator 1 according to the present embodiment, except that it is not provided with rupture origin regions 75, 76.

[0026] The rupture disc 700A has a circular planar shape when viewed from above in the axial direction of the gas generator. In FIG. 3 , the outer periphery of the ignition portion 9A disposed below the rupture disc 700A is indicated by a dotted line. In the comparative example, a fragile portion 710 is formed on a first surface 7000A of the rupture disc 700A. The fragile portion 710 is a portion where the rupture disc 700A actually ruptures, and has a start point 720, an end point 730, and an extension region 740. The fragile portion 710 is a portion thinner than other portions, and more specifically, is a groove formed in the rupture disc 700A. The start point 720 and the end point 730 of the fragile portion 710 are disposed at different positions, and an annular extension region 740 is formed between the start point 720 and the end point 730. The center of the annular extension region 740 coincides with the central axis C1. In the comparative example shown in Figure 3, the fragile portion 710 does not have the cleavage initiation regions 75, 76, and the igniter 9 is positioned so that the distance between the ignition portion 9A and the extension region 740 of the fragile portion 710 is constant around the outer periphery of the ignition portion 9A.

[0027] In this embodiment, assuming that the igniter 9 is activated, a simulation was performed when a load is applied to the rupture disc 7A, and the stress distribution acting on the rupture disc 7A was calculated. The stress distribution was calculated for the rupture disc 7A of this embodiment shown in FIG. 2 and the rupture disc 700A of the comparative example shown in FIG. 3. The simulation conditions were as follows. First, the igniter 9 and the rupture discs 7A and 700A were arranged so that the axial center of the ignition portion 9A of the igniter 9 coincided with the centers of the fragile portions 71 and 710. Next, the diameters of the rupture discs 7A and 700A were set to 12 mm, and the diameters of the fragile portions 71 and 710 were set to 10 mm. The diameter of the fragile portion 71 was set to the diameter of a virtual circle overlapping the annular extension region 74, ignoring the rupture initiation regions 75 and 76. The thickness of the fragile portions 71 and 710 was set to 0.3 mm. The diameter of an imaginary circle contacting the inside of the rupture initiation regions 75, 76 was 8 mm. When viewed from the axial direction of the gas generator, the rupture initiation regions 75, 76 are regions recessed by a maximum of 1 mm on one side inside the extension region 74. In both this embodiment and the comparative example, an ignition charge containing zirconium and potassium perchlorate was used as the ignition charge included in the ignition portion 9A. The amount of the ignition charge was 190 mg, the diameter of the ignition portion 9A was 6 mm, the distance between the ignition portion 9A and the rupture disc portions 7A, 700A was set to 2.0 mm on one side, the gas filling pressure in the gas-filled chamber 3 was 7 MPa, and the temperature of the environment in which the gas generator was installed was set to 23°C.

[0028] FIG. 4 is a diagram showing the stress distribution of the rupture disc 7A in the gas generator 1 according to the present embodiment. FIG. 5 is a diagram showing the stress distribution of the rupture disc 700A in a gas generator according to a comparative example. In FIG. 4, the rupture initiation regions 75, 76 are surrounded by solid lines. In this simulation, the maximum shear stress applied to the middle surface in the thickness direction of the rupture discs 7A, 700A was calculated. As shown in FIGS. 4 and 5, a relatively larger shear stress acts on the fragile portions 71, 710 than on other portions, but a larger shear stress acts on the rupture initiation regions 75, 76 provided in this embodiment ( FIG. 4 ). For this reason, when the igniter 9 is activated, the rupture initiation regions 75, 76 become the rupture initiation points of the fragile portion 71, causing it to rupture. As a result, the gas generator 1 according to the present embodiment can easily rupture the rupture disc 7A with a small amount of ignition charge.

[0029] Furthermore, in the present embodiment, since the start point 72 and the end point 73 of the fragile portion 71 are located at different positions, the rupture site can be maintained in a connected state to the rupture disc portion 7A even after the fragile portion 71 is ruptured. If the rupture site were to be torn off from the rupture disc portion 7A, fragments of the rupture site could block the flow path of the pressurized gas and interfere with the supply of the pressurized gas to the outside. However, the gas generator 1 according to the present embodiment can prevent the rupture site from being torn off from the rupture disc portion 7A, and therefore can prevent the rupture site from interfering with the supply of the pressurized gas to the outside.

[0030] Furthermore, in the gas generator disclosed in Patent Document 1, the rupture disk that closes the opening of the pressurized container does not have a fragile portion formed therein, and is configured to rupture from a location ruptured by arc discharge. With the rupture disk disclosed in Patent Document 1, the location of rupture cannot be controlled, and if the rupture location is too narrow, it becomes impossible to quickly supply the pressurized gas to the outside. On the other hand, in the gas generator according to the present embodiment, since the fragile portion 71 ruptures, the rupture location can be set in advance by designing the extension region 74 of the fragile portion 71, and therefore the pressurized gas can be quickly supplied to the outside.

[0031] For example, the gas generator 1 according to the present embodiment can be used as a gas supply source for a wearable airbag device. Such an airbag device is a device for preventing injury to the wearer when the wearer falls, etc. The gas generator 1 according to the present embodiment can be made lighter because the rupture plate portion 7A can be ruptured with a small amount of ignition charge.

[0032] <Modification> Next, a gas generator according to a modification of the first embodiment will be described. Fig. 6 is a plan view of the rupture disc portion 7A as seen from above in the axial direction of the gas generator. The gas generator according to the modification has the same configuration and structure as gas generator 1 according to the first embodiment, except that a cracking initiation region 77 is provided instead of cracking initiation regions 75, 76.

[0033] In this modification, only one rupture initiation region 77 is provided in the middle of the extension region 74. The rupture initiation region 77 is located on the opposite side of the start point 72 and the end point 73. When viewed from the axial direction of the ignition part 9A of the extension region 74, the rupture initiation region 77 is a portion that extends and is recessed toward the center of the rupture disc part 7A. When viewed from the axial direction of the ignition part 9A, the rupture initiation region 77 is located at a position where the linear distance from the center of the ignition part 9A (the same position as C1) to the extension region 74 is the shortest. In this way, only one rupture initiation region 77 may be provided.

[0034] FIG. 7 is a diagram showing the stress distribution in the rupture disc portion 7A in the gas generator according to the modified example. In FIG. 7, the rupture origin region 77 is surrounded by a solid line. In this modified example, a simulation was also performed under the same conditions as in the first embodiment, and the stress acting on the rupture disc portion 7A was calculated. As shown in FIG. 7, a larger shear stress acts on the rupture origin region 77. Therefore, when the igniter 9 is activated, the rupture origin region 77 becomes the rupture origin of the fragile portion 71 and ruptures. The rupture occurs along the extension region 74 from the rupture origin region 77 toward the start point 72 and the end point 73, respectively. As a result, the gas generator according to this modified example can easily rupture the rupture disc portion 7A with a small amount of ignition charge.

[0035] In addition, in the modified example, since the start point 72 and the end point 73 of the rupture initiation region 77 are arranged on the opposite sides, rupture starts from the rupture initiation region 77, and the state in which the rupture site is connected to the rupture disc portion 7A can be more effectively maintained. Therefore, the gas generator according to this modified example can prevent the rupture site from being torn off from the rupture disc portion 7A.

[0036] <Embodiment 2> Next, a gas generator according to embodiment 2 will be described. Fig. 8 is a plan view of the rupture disc 7A as seen from above in the axial direction of the gas generator 1. In Fig. 8, the outer periphery of the ignition part 9A arranged below the rupture disc 7A is shown by a dotted line. In Fig. 8, components that are substantially the same as those in embodiment 1 described above are given the same reference numerals, and descriptions thereof will be omitted. The gas generator according to embodiment 2 has the same configuration and structure as the gas generator 1 according to embodiment 1, except for the positional relationship between the rupture disc 7A, the rupture disc 7A, and the ignition part 9A.

[0037] In the present embodiment, when viewed from the axial direction of the ignition part 9A, the ignition part 9A is disposed in a positional relationship such that the center C2 thereof does not overlap with the center C3 of the extension region 74 of the fragile part 71. In the present embodiment, the ignition part 9A is disposed away from the central axis C1 of the gas generator, and the fragile part 71 is formed so that the center C3 of the annular extension region 74 coincides with the central axis C1 of the gas generator. More specifically, in the present embodiment, when viewed from the axial direction of the ignition part 9A, a part of the outer periphery of the ignition part 9A deviates from the extension region 74. With this configuration, it is possible to make the extension region 74 at a portion overlapping with the ignition part 9A the crack initiation region 78 without providing an extending region recessed inward like the above-mentioned crack initiation regions 75 and 76 in the extension region 74. The crack initiation region 78 overlapping with the ignition part 9A is a region to which a larger shear stress acts than other regions, and cracking can be initiated from the crack initiation region 78. In the gas generator according to this embodiment, the rupture plate portion 7A can be easily ruptured with a small amount of ignition charge.

[0038] Furthermore, in this embodiment, even if a part of the outer periphery of the ignition part 9A overlaps with the extension region 74 when viewed in the axial direction of the ignition part 9A, it is sufficient that the center C2 of the ignition part 9A is positioned so as not to overlap with the center C3 of the extension region 74 of the fragile part 71. This positional relationship makes the distance between the ignition part 9A and the extension region 74 inconstant along the outer periphery of the ignition part 9A, and the area close to the ignition part 9A can be set as the rupture initiation region.

[0039] <Embodiment 3> Next, a gas generator according to embodiment 3 will be described. Fig. 9 is a plan view of rupture disc 7A as seen from above in the axial direction of gas generator 1. In Fig. 9, the outer periphery of ignition section 9A arranged below rupture disc 7A is shown by a dotted line. In Fig. 9, components that are substantially the same as those in embodiment 1 and embodiment 2 described above are denoted by the same reference numerals, and descriptions thereof will be omitted. Note that the gas generator according to embodiment 3 has the same configuration and structure as gas generator 1 according to embodiment 2, except that it is provided with stress dispersing portions 80, 81.

[0040] The gas generator according to this embodiment includes stress distribution points 80, 81 formed at the start point 72 and end point 73 of the fragile portion 71, and stopping the cleavage that has progressed from the cleavage initiation region 78. The stress distribution points 80, 81 are portions that prevent the cleavage from progressing further, and distribute the stress required for the cleavage that has progressed along the extension region 74. The stress distribution points 80, 81 extend outward from the center of the extension region 74, and change the direction of cleavage progression outward. The stress distribution points 80, 81 are deflection parts of the fragile portion that exhibit the function of changing the direction of cleavage progression. Therefore, at the stress distribution points 80, 81, it is possible to branch the fragile portion from the start point 72 and end point 73, or to form fragile portions in a direction different from the extension direction of the extension region 74.

[0041] In this embodiment, the stress dispersing portions 80, 81 are formed in an M-shape. By providing the stress dispersing portions 80, 81, the rupture can be stopped at the stress dispersing portions 80, 81, and the rupture portion can be prevented from being torn off from the rupture disc portion 7A. The shape of the stress dispersing portions 80, 81 can be the same as that of the stress dispersing portion disclosed in Japanese Patent Application Laid-Open No. 2005-238948.

[0042] <Fourth Embodiment> Next, a gas generator according to a fourth embodiment will be described. Fig. 10 is an axial cross-sectional view of gas generator 1 according to this embodiment. Fig. 11 is a plan view of rupture disc 7A as seen from above in the axial direction of gas generator 1. In Figs. 10 and 11, configurations that are substantially the same as those in the first to third embodiments described above are designated by the same reference numerals, and descriptions thereof will be omitted.

[0043] The rupture disc 7A has an inclined portion 91 formed at a position facing the ignition portion 9A, and annular inclined portions 90 and 92 surrounding the inclined portion 91. The annular inclined portion 90 and inclined portion 92 are connected in the circumferential direction and do not substantially face the ignition portion 9A. A rupture initiation region 79 is provided in the inclined portion 91. In the fragile portion 71, the rupture initiation region 79 is located closer to the ignition portion 9A than the start point 72 and the end point 73. The inclined portions 90 and 92 are provided to form the central inclined portion 91, and the inclined portion 91 is inclined downward from the inclined portion 90 side toward the inclined portion 92. The rupture initiation region 79 of the fragile portion is located at the point closest to the ignition portion 9A, and is located in the inclined portion 91. In this way, the rupture starting region 79 can also be provided by providing the inclined portion 91 in the rupture disc portion 7A and making the distance between the fragile portion and the outer periphery of the ignition portion 9A indefinite when viewed from a direction perpendicular to the axial direction of the gas generator 1. The inclined portion 91 may have a circular shape when viewed from the direction of the central axis C1.

[0044] According to the gas generator 1 according to the present embodiment, the rupture initiation region 79 is a region where a larger shear stress acts than other regions, and rupture can be initiated from the rupture initiation region 79. The gas generator 1 according to the present embodiment can easily rupture the rupture disk portion 7A with a small amount of ignition charge. Note that, as in the present embodiment, the fragile portion may of course be formed in a U-shape.

[0045] <Other Embodiments> Although the embodiments of the present disclosure have been described above, the various embodiments described above can be combined as much as possible. In the above embodiments, a stored-type gas generator using pressurized gas as the main inflation source has been exemplified, but the technology of the present disclosure can also be applied to a hybrid-type gas generator that supplies pressurized gas and combustion gas to the outside. Furthermore, in the above embodiments, the fragile portion 71 is provided on the first surface 70A side of the rupture disc portion 7A, but the fragile portion 71 may be provided on the second surface 70B side, or the fragile portion 71 may be provided in the same portion on both the first surface 70A side and the second surface 70B side.

[0046] The cleaving device of the present disclosure is also widely applicable to gas generators, such as gas generators for vehicle airbags, gas generators for airbags worn on the human body, gas generators for drone airbags, and gas generators for inflating floats such as life jackets.

[0047] Although an example in which a rupture device composed of a rupture disc and an igniter is applied to a gas generator has been described as an embodiment, the rupture device of the present disclosure can be applied to devices other than gas generators. For example, the rupture device of the present disclosure can be applied to the drive source of the marker substance release device disclosed in Japanese Patent Application Laid-Open No. 2006-059000. The rupture device of the present disclosure can also be applied to the gas generator of the fire extinguisher disclosed in Japanese Patent Application Laid-Open No. 2016-168410 and the fire extinguishing gas release device disclosed in Japanese Patent Application Laid-Open No. 2015-84820. The rupture device of the present disclosure can also be applied to the needleless injection system disclosed in Japanese Patent Application Laid-Open No. 2010-279706 and the means for releasing pressurized gas in the needleless injection device disclosed in Japanese Patent Application Laid-Open No. 2008-500876.

[0048] Although the embodiments of the gas generator according to the present disclosure have been described above, each aspect disclosed in this specification can be combined with any other feature disclosed in this specification.

[0049] DESCRIPTION OF SYMBOLS 1: Gas generator 2: Container 3: Gas filling chamber 4: Opening 5: Seal pin 6: Opening 7: Igniter housing 7A: Rupture disc portion 7B: Peripheral wall portion 7C: Expanded diameter peripheral wall portion 8: Gas discharge port 9: Igniter 9A: Ignition portion 9B: Holding portion 9C: Conductive pin 10: Igniter collar 11: Support portion 12: Filter 13: Space 14: Gap 70A: First surface 70B: Second surface 71: Weak portion 72: Starting point 73: Ending point 74: Extension region 75, 76, 77, 78, 79: Crack initiation region 80, 81: Stress dispersion portion 90, 91, 92: Inclined portion

Claims

1. A rupture device comprising: a rupture disc having a first surface and a second surface opposite to the first surface, the rupture disc closing an opening of a container filled with pressurized gas; a weakened portion formed on at least one of the first and second surfaces of the rupture disc, the weakened portion having a start point and an end point located at different positions, and an extended region between the start point and the end point formed in an annular shape including a curved portion, a straight portion, or both a curved portion and a straight portion; and an ignition portion including an ignition portion on a tip side, the ignition portion facing a rupture initiation region, which is a part of the extended region excluding the start point and the end point of the weakened portion, and an igniter disposed so that the distance from the extended region to the ignition portion is variable along the outer periphery of the ignition portion so that rupture starts from the rupture initiation region.

2. The rupture device according to claim 1, wherein the rupture disc is ruptured by a load being applied to the rupture initiation region by combustion products generated by activation of the igniter, and the rupture progresses along the extension region toward the start point and the end point.

3. The cleaving device according to claim 1, wherein the igniter is positioned such that the center of the ignition part does not overlap the center of the extension region of the weakened part when viewed in the axial direction of the ignition part.

4. The cleaving device according to claim 3, wherein when viewed in the axial direction of the ignition part, a part of the outer periphery of the ignition part is outside the extension region of the weakened part.

5. The rupture device according to claim 1, wherein the igniter is disposed such that the center of the ignition part and the center of the extending region of the fragile part overlap when viewed in the axial direction of the ignition part, and the extending region extends in a concave shape toward the center of the rupture disc when viewed in the axial direction of the ignition part.

6. The cleaving device according to claim 1, further comprising stress dispersion points formed at the start and end points of the weakened portion, which stop cleavage that has progressed from the cleavage initiation region.

7. The cleaving device according to claim 6, wherein the stress dispersion point is a deflection portion of the weakened portion that extends from the center of the extension region of the weakened portion toward the outside.

8. The rupture device according to any one of claims 1 to 7, wherein the rupture disc is provided in a region overlapping with the ignition part when viewed from the axial direction of the ignition part, and has an inclined part that is inclined when viewed from a direction perpendicular to the axial direction of the ignition part, and the rupture initiation region is located on the inclined part.

9. The cleaving device according to claim 8, wherein the cleavage initiation region is located closer to the ignition portion than the start point and the end point in the weakened portion.

10. A cleavage device according to any one of claims 1 to 7, wherein the cleavage initiation region is located at a point where the linear distance from the center of the ignition part to the extension region is shortest when viewed in the axial direction of the ignition part.

11. A gas generator comprising a cleaving device according to any one of claims 1 to 7.

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