Perforator and gas discharge device

Abstract

This perforator comprises: a piston rod that has, on the distal-end side thereof, a blade edge part that is disposed so as to face a sealing plate in a state in which the perforator is attached to a gas bottle; and a drive unit that causes the piston rod to be fired toward the sealing plate during operation and causes the blade edge part to pierce the sealing plate. The blade edge part has a plurality of ridge lines and three or more piston blade surfaces that are separated from each other by the ridge lines.

Description

Perforators and gas extractors

[0001] The present invention relates to a perforator and gas evacuation device for venting gas from a gas bottle.

[0002] A perforator is known that is used by attaching a gas bottle that stores gas inside, and that discharges gas from the gas bottle by opening (unsealing) a sealing plate that seals the gas outlet of the gas bottle (see, for example, Patent Document 1).

[0003] This type of perforator has a piston with a cutting edge at its tip that faces the sealing plate when attached to the gas bottle, and a drive unit that propels the piston toward the sealing plate when activated.

[0004] For example, Patent Document 1 discloses a perforator equipped with a piston rod having a cutting edge on the tip side that is V-shaped and pointed in a side view.

[0005] Patent No. 6283252

[0006] However, with conventional perforators, when the cutting edge of the piston rod is used to perforate the sealing plate, there is a risk that the cutting edge may tear the sealing plate.

[0007] The technology of the present disclosure has been made in consideration of the above-mentioned circumstances, and aims to provide a technology that prevents a sealing plate from being torn off when the sealing plate is perforated by the cutting edge of a piston rod in a perforator for discharging gas from a gas bottle.

[0008] The present disclosure solves the above problems in the following manner: That is, the technology according to the present disclosure provides a perforator that is used with a gas bottle attached and that, when activated, opens a sealing plate that seals a gas outlet of the gas bottle, thereby discharging gas from the gas bottle, the perforator comprising: a piston rod having a cutting edge portion at its tip end that faces the sealing plate when the perforator is attached to the gas bottle; and a drive unit that, when activated, propels the piston rod toward the sealing plate, causing the cutting edge portion to perforate the sealing plate, wherein the cutting edge portion has a plurality of ridges and three or more piston blade faces that are separated from each other by the ridges.

[0009] The cutting edge may include a tip ridge that forms the tip of the cutting edge, and the projected length of the tip ridge along the axial direction of the piston rod may be smaller than the diameter of the piston rod.

[0010] Furthermore, one end of another ridge line may be connected to both ends of the tip ridge line.

[0011] The other end of the other ridge line may extend to a side surface of the piston rod.

[0012] Furthermore, a plurality of the other ridges may be connected to at least one end of the tip ridge.

[0013] Furthermore, one ends of the plurality of ridgelines may meet at an apex formed at the tip of the cutting edge portion, and the other ends of the ridgelines may extend to a side surface of the piston rod.

[0014] The technology of the present disclosure may also be a gas discharge device including any one of the perforators described above and a gas bottle that can be attached to the perforator.

[0015] According to the present disclosure, it is possible to provide a technique for preventing a sealing plate from being torn off when the sealing plate is perforated by the cutting edge of a piston rod in a perforator for discharging gas from a gas bottle.

[0016] FIG. 1 is a diagram illustrating an example of the configuration of a perforator according to an embodiment. FIG. 2 is a diagram illustrating an example of the configuration of a gas bottle according to an embodiment. FIG. 3 is a diagram illustrating the operation of the perforator according to an embodiment. FIG. 4 is a diagram illustrating the detailed structure of a second piston according to an embodiment. FIG. 5 is a diagram illustrating the axial projection length of a tip ridge. FIG. 6 is a diagram illustrating a piston rod according to Comparative Example 1. FIG. 7 is a diagram illustrating an example of a state in which a sealing plate of a gas bottle is perforated by the cutting edge of a piston rod according to an embodiment. FIG. 8 is a diagram comparing the perforation states of the sealing plate in the embodiment and the comparative example. FIG. 9 is a diagram illustrating a piston rod according to Comparative Example 2. FIG. 10 is a diagram illustrating a piston rod according to Comparative Example 3. FIG. 11 is a diagram illustrating the cutting edge of a piston rod according to Modification Example 1. FIG. 12 is a diagram illustrating the cutting edge of a piston rod according to Modification Example 2.

[0017]

[0023] Hereinafter, a protection device according to an embodiment of the present disclosure will be described 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 the configuration 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 claims.

[0018] The perforator according to this embodiment is used with a gas bottle attached, and when activated, opens a sealing plate that seals the gas outlet of the gas bottle, thereby discharging gas from the gas bottle, and comprises: a piston having a cutting edge portion at its tip that is positioned opposite the sealing plate when the perforator is attached to the gas bottle; and a drive unit that when activated, launches the piston toward the sealing plate, causing the cutting edge portion to perforate the sealing plate, and the cutting edge portion has a plurality of ridges and three or more piston blade faces that are separated from each other by the ridges.

[0019] <Embodiment> Fig. 1 is a diagram showing an example of the configuration of a perforation device 1 according to an embodiment. The perforation device 1 is used with a cartridge-type gas bottle 2 (see Fig. 2) attached thereto, and is a perforation device that, when activated, discharges gas from the gas bottle by opening a sealing plate that seals a gas outlet in the gas bottle 2. A gas discharge device is formed by combining the perforation device 1 with the gas bottle 2 attached to the perforation device 1. Fig. 1 shows the perforation device 1 in a state before activation. Fig. 2 is a diagram showing an example of the configuration of the gas bottle 2 according to an embodiment.

[0020] The gas bottle 2 is, for example, an iron cartridge container filled with gas at high pressure. The gas bottle 2 is formed with a gas outlet 21 for discharging the gas. Furthermore, before use, the gas outlet 21 of the gas bottle 2 is sealed (blocked) by a sealing plate 22, thereby hermetically sealing the interior of the gas bottle 2. The sealing plate 22 is, for example, an iron circular plate that blocks the opening related to the gas outlet 21. Of course, the shape of the sealing plate 22 can be changed as appropriate to match the shape of the opening of the gas outlet 21.

[0021] The bottle-side attachment part 23 formed on the gas outlet 21 side of the gas bottle 2 can be connected to the main body-side attachment part 16 formed on the perforator 1 side, thereby allowing the gas bottle 2 to be detachably attached to the gas bottle 2. The main body-side attachment part 16 of the perforator 1 has, for example, a recessed shape that can receive the bottle-side attachment part 23 of the gas bottle 2. Furthermore, the connection method between the bottle-side attachment part 23 and the main body-side attachment part 16 is not particularly limited, but examples include a screw connection method.

[0022] The perforator 1 has a cylindrical first housing 10 and a cylindrical second housing 40. In Fig. 1, the central axis extending in the axial direction of the first housing 10 and the second housing 40 is indicated by the symbol C1. In this embodiment, the first housing 10 and the second housing 40 are arranged, for example, coaxially.

[0023] The first housing 10 has an open first end 11 located at one end in the axial direction, to which a connection cap member 13 is attached. The main body side attachment portion 16 is formed by a recess formed inside the connection cap member 13. The second end 12 located at the other end in the axial direction of the first housing 10 is also open, to which a cylindrical second housing 40 is connected and fixed.

[0024] A first end 41 located on one axial end side of the second housing 40 is fitted into the second end 12 of the first housing 10, and the two components are integrated to prevent them from falling off. A cylindrical piston guide 18 is disposed inside the first housing 10. The piston guide 18 is fixed to the inner wall surface of the first housing 10.

[0025] An opening 14 is formed at the axially intermediate position of the first housing 10, and a cylindrical gas discharge member 15 is connected and fixed to this opening 14. The gas discharge member 15 may be, for example, a threaded pipe joint called a nipple. Reference symbol C2 in FIG. 1 indicates the central axis of the gas discharge member 15. For example, the central axis C2 of the gas discharge member 15 extends in a direction perpendicular to the central axis C1 of the first housing 10. A first end 15A of the gas discharge member 15 is connected to the opening 14 of the first housing 10. A second end 15B of the gas discharge member 15, located on the opposite side of the first end 15A in the axial direction, is connected to a gas pipe or the like leading to a gas supply target (e.g., an airbag) to which the gas discharge device (perforator 1) supplies gas. A hollow gas flow path 17 is formed inside the gas discharge member 15, penetrating the gas discharge member 15 along the axial direction, and the gas discharged from the gas outlet 21 of the gas bottle 2 is supplied to a gas supply target through the gas flow path 17 of the gas discharge member 15. Note that the airbag described above is an example of a gas supply target, and the gas supply target is not particularly limited.

[0026] Next, the internal structure of the housings (first housing 10, second housing 40) of the perforator 1 will be described in detail. Hereinafter, the first end 41 side of the second housing 40 in the axial direction will be referred to as the front end side, and the second end 42 side located on the opposite side will be referred to as the rear end side. An initiator 50 serving as a drive unit is fixed to the second end 42 side (rear end side) of the second housing 40. The initiator 50 is, for example, an electric igniter. The initiator 50 has an ignition unit 51 arranged so as to face an accommodation space formed in the second housing 40. The ignition unit 51 is, for example, configured as a cup container that accommodates an ignition charge therein. For example, the ignition charge is accommodated in the cup container of the ignition unit 51 while in contact with a bridge wire (resistor) that is strung so as to connect the base ends of a pair of conductive pins. As the ignition charge, for example, ZPP (zirconium potassium perchlorate), ZWPP (zirconium tungsten potassium perchlorate), THPP (titanium hydride potassium perchlorate), lead tricinate, etc. may be used.

[0027] Reference numeral 52 denotes a lead wire, through which an operating current for operating the initiator 50 is supplied from a power source. When an operating current is supplied to the initiator 50, the bridge wire in the ignition unit 51 heats up, causing the ignition charge in the cup container to ignite and burn, generating combustion gas. Then, as the ignition charge in the cup container burns, the pressure inside the cup container increases, causing the cup container cleavage surface 51A to cleave, releasing the combustion gas into the storage space formed in the second housing 40.

[0028] A first piston 60 and a second piston 70 are arranged in an accommodation space formed within the housings (first housing 10, second housing 40) of the perforator 1, starting from a position closest to the initiator 50. The first piston 60 is arranged to be movable within a first piston movement space S1 formed inside the second housing 40 along the axial direction of the first piston movement space S1 (i.e., along the central axis C1). For example, the first piston 60 is a roughly cylindrical piston member, and its outer diameter is equal to the inner diameter of a first guide surface 43 formed by the inner circumferential surface of the second housing 40. In addition, a recess 61 is provided at the rear end of the first piston 60, where the rear end surface is recessed.

[0029] The second piston 70 has a piston head 71 and a piston rod 72 extending forward from the piston head 71. The piston head 71 and piston rod 72 of the second piston 70 are cylindrical, and the piston rod 72 has a smaller diameter than the piston head 71. The piston rod 72 is coaxial with and integrally connected to the piston head 71. The first piston 60 has a larger diameter than the piston head 71 of the second piston 70. The piston rod 72 of the second piston 70 has a cutting edge 73 on the tip side.

[0030] A second piston movement space S2 is formed inside the piston guide 18, allowing the second piston 70 to move. The second piston 70 is movable along the axial direction of the second piston movement space S2 (i.e., along the central axis C1). The piston guide 18 has a small-diameter inner circumferential surface 181 with a relatively small inner diameter and a large-diameter inner circumferential surface 182 with a larger inner diameter than the small-diameter inner circumferential surface 181. The small-diameter inner circumferential surface 181 is located on the front end side of the piston guide 18, and the large-diameter inner circumferential surface 182 is located rearward of the small-diameter inner circumferential surface 181. The inner diameter of the large-diameter inner circumferential surface 182 is equal to the diameter of the piston head 71 of the second piston 70. The inner diameter of the small-diameter inner circumferential surface 181 is equal to the diameter of the piston rod 72 of the second piston 70. The second piston 70 is accommodated in the first piston movement space S1 such that the piston rod 72 is accommodated in the second piston movement space S2 and the piston head 71 faces the front end surface 62 of the first piston 60.

[0031] The front end surface of the piston guide 18 is formed as a first stopper wall 183 that prevents the first piston 60 from slipping out forward when the perforator 1 is operated. The wall surface that forms a step between the small-diameter inner circumferential surface 181 and the large-diameter inner circumferential surface 182 is configured as a second stopper wall 184 that prevents the piston head 71 of the second piston 70 from slipping out forward when the perforator 1 is operated.

[0032] The perforator 1 configured as described above is used with the bottle-side attachment portion 23 of the gas bottle 2 attached to the main body-side attachment portion 16. The materials of the components constituting the perforator 1 are not particularly limited, but for example, the first housing 10 and the second housing 40 may be made of metal such as aluminum or iron. The first piston 60 may be made of heat-resistant resin. The second piston 70 may be made of metal such as stainless steel or iron. The connection cap member 13 and the piston guide 18 may be made of resin. Of course, these materials are merely examples.

[0033] Next, the operation of the perforator 1 will be described. FIG. 3 is a diagram illustrating the operation of the perforator 1 according to the embodiment. Reference numeral 3 in the figure denotes a gas discharge device including the perforator 1 and the gas bottle 2 attached to the perforator 1. In the initial state before the perforator 1 is activated, the relative positions of the first piston 60 and the second piston 70 are as shown in FIG. 1. That is, the first piston 60 is disposed in the first piston movement space S1 formed in the second housing 40, with the recessed portion 61 facing the ignition portion 51 of the initiator 50. The second piston 70 is disposed in the second piston movement space S2, with the piston head 71 facing the front end surface 62 of the first piston 60 and the cutting edge portion 73 formed on the tip side facing the sealing plate 22 of the gas bottle 2. The piston head 71 of the second piston 70 is disposed, for example, in contact with the front end surface 62 of the first piston 60.

[0034] 3A shows the state at the moment when the initiator 50 is activated. When the initiator 50 is activated, the ignition charge in the cup container at the ignition unit 51 ignites and burns, causing the cleavage surface 51A of the cup container to cleave, and combustion gas is forcefully released into the first piston movement space S1. The first piston 60, which receives the pressure of this combustion gas in the recess 61, is launched axially forward within the first piston movement space S1. Then, as the first piston 60 is launched axially forward (moves at high speed) (the first piston 60 collides with the piston head 71 of the second piston 70), the second piston 70 is also launched coaxially with the first piston 60 within the second piston movement space S2.

[0035] 3(b) shows the state in which the first piston 60 and the second piston 70 have been launched. The first piston 60, launched as described above, stops when it collides with the first stopper wall 183. The second piston 70 stops when the piston head 71 collides with the second stopper wall 184. When the second piston 70 is launched, during the launch process, the cutting edge 73 formed on the tip side of the piston rod 72 of the second piston 70 collides with the sealing plate 22 of the gas bottle 2, and the cutting edge 73 perforates the sealing plate 22.

[0036] When the cutting edge 73 of the piston rod 72 of the second piston 70 perforates the sealing plate 22 sealing the gas outlet 21 of the gas bottle 2, the gas (indicated by the diagonally hatched arrow in the figure) that has been filled in the bottle at high pressure flows out from the gas outlet 21. (c) in Figure 3 shows a state in which gas is being discharged from the gas outlet 21 of the gas bottle 2. The second piston 70 is pushed back from inside the gas outlet 21 by the pressure of the gas flowing out from the gas outlet 21 of the gas bottle 2. The gas that has flowed out from the gas outlet 21 of the gas bottle 2 then flows into the gas flow path 17 formed in the gas discharge member 15 through the space S3 formed between the main body-side mounting part 16 of the perforator 1 and the piston guide 18, and is supplied to a target for gas supply, such as an airbag.

[0037] Next, details of the second piston 70 in the perforator 1 will be described, focusing on the structure of the cutting edge portion 73. FIG. 4 is a diagram illustrating the detailed structure of the second piston 70 according to the embodiment. (a) shows a first side surface of the second piston 70. (b) shows a second side surface of the second piston 70. The symbol C3 shown in (a) is a central axis extending in the axial direction of the second piston 70 (piston rod 72). (b) shows a side surface when the second piston 70 is rotated 90° around the central axis C3 based on the first side surface shown in (a). (c) shows the front surface (anterior surface) of the second piston 70. (d) is a perspective view of the second piston 70.

[0038] In this embodiment, the cutting edge portion 73 formed on the tip side of the second piston 70 has a plurality of ridge lines EL and three or more piston cutting surfaces separated from one another by the ridge lines EL. In the example shown in Figure 4, the cutting edge portion 73 is configured to include six piston cutting surfaces PL1 to PL6 separated from one another by seven ridge lines (EL0, EL11 to EL16). When the piston cutting surfaces PL1 to PL6 are not to be distinguished from one another, they may be referred to as "piston cutting surfaces PL."

[0039] In the drawings, the symbol EL0 denotes a leading edge line forming the tip of the cutting edge portion 73. In the example shown in FIG. 4 , the leading edge line EL0 extends in a direction perpendicular to the central axis C3 of the piston rod 72 (cutting edge portion 73) (direction perpendicular to the axial line). However, the leading edge line EL0 may also extend in a direction oblique to the central axis C3 of the piston rod 72 (cutting edge portion 73). The leading edge line EL0 has a projected length L0 (hereinafter referred to as the "axial projected length") when projected along the central axis C3 direction (axial direction) of the piston rod 72, which is set to be shorter than the diameter of the piston rod 72. FIG. 5 is a diagram illustrating the axial projected length L0 of the leading edge line EL0. In the embodiment described in FIG. 4 , the leading edge line EL0 extends in a direction perpendicular to the axial line of the piston rod 72, so the actual length L1 of the leading edge line EL0 and the axial projected length L0 are equal (see FIG. 5A). In contrast, when the tip edge line EL0 extends obliquely relative to the central axis C3 of the piston rod 72 (FIG. 5B), the axial projection length L0 of the tip edge line EL0 is smaller than the actual length L1.

[0040] In the configuration example of the cutting edge portion 73 shown in FIG. 4 , one end of each of the other ridgelines is connected to both ends of the leading edge EL0. The other ridgelines here refer to ridgelines other than the leading edge EL0. In this case, multiple other ridgelines (hereinafter referred to as "diagonal ridgelines") may be connected to at least one end of the leading edge EL0. In the example shown in FIG. 4 , one end of each of the diagonal ridgelines EL11, EL13, and EL15 is connected to the first end e1 of the leading edge EL0. Furthermore, one end of each of the diagonal ridgelines EL12, EL14, and EL16 is connected to the second end e2 of the leading edge EL0. Furthermore, the other end of each of the diagonal ridgelines EL11 to EL16, which is connected to one of the ends e1 and e2 of the leading edge EL0, extends to the side surface 721 of the piston rod 72. The oblique ridgelines EL11 to EL16 can also be said to be ridgelines that gradually increase the diameter of the cutting edge 73 from the tip side (the side of the tip ridgeline EL0) toward the base side (the opposite side to the tip ridgeline EL0) in the axial direction of the cutting edge 73. Note that the symbol θ1 shown in Figure 4(a) is the inclination angle of the oblique ridgeline (EL12 in the illustrated example) with respect to the tip ridgeline EL0.

[0041] The cutting edge 73 of the piston rod 72 configured as described above is configured as a knife edge including a leading edge ridge EL0 located at the leading edge. In this embodiment, the cutting edge 73 has three or more piston cutting surfaces PL that are mutually separated by ridges (EL0, EL11 to EL16).

[0042] 6A and 6B are diagrams illustrating a piston rod R1 having a cutting edge portion EP1 according to Comparative Example 1. The piston rod R1 according to Comparative Example 1 shown in FIG. 6A has a so-called two-sided cutting edge portion EP1, and two piston blade surfaces PL'1 and PL'2 are separated by a leading edge line EL0' located at the tip. In Comparative Example 1, when the leading edge line EL0' separating the two piston blade surfaces PL' is projected in the axial direction of the piston rod R1, the axial projected length L0' is equal to the diameter of the piston rod R1. In Comparative Example 1, in which the axial projected length L0' is equal to the diameter of the piston rod R1, the dimension of the axial projected length L0' (diameter of the piston rod R1) needs to be equal to or smaller than the diameter of the sealing plate to be drilled. Therefore, in Comparative Example 1, stroke management when the piston rod R1 is launched during operation of the perforator 1 becomes strict, and if the piston rod R1 is inserted too deeply into the gas outlet 21 of the gas bottle 2, there is a risk that the sealing plate perforated by the cutting edge EP1 will be torn off. Figure 6(b) schematically shows the state after the cutting edge EP1 of the piston rod R1 of Comparative Example 1 has perforated the sealing plate 22 that sealed the gas outlet 21 of the gas bottle 2. Symbol OE denotes the edge of the gas outlet 21. (b) shows the state after the sealing plate 22 that blocked the opening formed inside the edge OE has been perforated. Symbol 22'P1 denotes a remaining piece remaining after perforating the sealing plate 22. Symbol 22'P2 denotes a separated piece that has been torn off from the remaining piece 22'P1 of the sealing plate 22. If the separation piece 22'P2 is torn off when the sealing plate 22 is perforated, the separation piece 22'P2 may be transported through the gas flow path 17 in the gas exhaust member 15 to, for example, an airbag as the target for gas supply, which may cause problems such as damaging the airbag.

[0043] In contrast, in the piston rod 72 according to this embodiment, the cutting edge 73 includes multiple ridgelines EL and three or more piston blade surfaces PL separated from one another by the ridgelines EL. In this embodiment, the axial projection length L0 of the leading ridgeline EL0 at the tip of the cutting edge 73 is smaller than the diameter of the piston rod 72 (the maximum outer diameter of the cutting edge 73). This allows the diameter of the piston rod 72 (the maximum outer diameter of the cutting edge 73) to be set larger than the inner diameter of the edge portion OE at the gas outlet 21 of the gas bottle 2, i.e., the diameter of the sealing plate 22. Therefore, the sealing plate 22 can be pierced by inserting only a portion of the cutting edge 73 into the gas outlet 21 (see FIG. 7 ). In other words, the axial projection length L0 of the leading ridgeline EL0 at the cutting edge 73 can be set smaller than the diameter of the sealing plate 22, and the diameter of the piston rod 72 (the maximum outer diameter of the cutting edge 73) can be set larger than the diameter of the sealing plate 22.

[0044] FIG. 7 illustrates an example of a state in which the cutting edge 73 of the piston rod 72 according to this embodiment has perforated the sealing plate 22 of the gas bottle 2. The symbol L2 denotes the insertion depth (hereinafter referred to as the "cutting edge insertion depth (length)") of the cutting edge 73 when the piston rod 72, projected during operation of the perforator 1, perforates the sealing plate 22 with the cutting edge 73. The depth L2 is the depth of the cutting edge 73 that is inserted further back (inward of the gas bottle 2) than the position of the sealing plate 22. For example, in the example shown in FIG. 7, during operation of the perforator 1, the movement of the piston rod 72 projected toward the gas outlet 21 is stopped when the diagonal ridges EL11 and EL12 of the cutting edge 73 collide with the edge OE of the gas outlet 21. In this embodiment, the cutting edge insertion depth L2 can be easily adjusted by adjusting the length of the leading edge EL0 and the inclination angles of the diagonal ridges EL11 to EL16.

[0045] 8 is a diagram comparing the perforation conditions of the sealing plate in the embodiment and Comparative Example 1. The upper diagram shows Comparative Example 1, and the lower diagram shows the embodiment. Also, the symbol BL in the figure indicates the boundary position between the sealing plate 22 and the edge portion OE, i.e., the outer periphery position of the sealing plate 22.

[0046] (a) shows the state at the time when the cracking of the sealing plate 22 starts. (d) shows the state when the perforation of the sealing plate 22 is completed. (b) and (c) show each state between (a) and (d), that is, each state in the process of the perforation of the sealing plate 22 gradually progressing. Note that the hatched areas in each figure are schematic representations of the openings formed in the sealing plate 22.

[0047] Here, the basic performance required of the perforator 1 is the cross-sectional area of ​​the opening formed when the sealing plate 22 is perforated ("required cross-sectional area of ​​the opening"). The appropriate value of this required cross-sectional area of ​​the opening can be calculated, for example, from the pressure (MPa / s) of the gas flowing out from the gas outlet 21 of the gas bottle 2 when the sealing plate 22 is perforated. For example, the required value set for the gas pressure at the beginning of perforation is 4.5 (MPa / s), and the required value set for the required cross-sectional area of ​​the opening to satisfy this condition is 10 (mm ２ ) is an example. Of course, these required values ​​are merely examples. Both the embodiment and Comparative Example 1 are similar in that it is necessary to ensure the required opening cross-sectional area when drilling the sealing plate 22.

[0048] In FIG. 8A, the tearing length of the sealing plate 22 when it tears corresponds to the length of the leading edge line EL0' (axial projection length L0') in Comparative Example 1, and corresponds to the length of the leading edge line EL0 (axial projection length L0) in the embodiment. In Comparative Example 1, the tearing of the sealing plate 22 progresses by the two piston blade surfaces PL'1 and PL'2 formed on both sides of the leading edge line EL0' during the transition process from (b) to (c) to (d). Therefore, the tearing of the sealing plate 22 progresses in a direction perpendicular to the extension direction of the leading edge line EL0' (direction perpendicular to the leading edge line), gradually increasing the tear width and finally reaching the completed perforation state of (d). The dashed line in the figure indicates the fold line FL of the fold-in piece along which the torn sealing plate 22 is folded into the interior of the gas bottle 2. 8, in Comparative Example 1, the length of the fold line FL gradually decreases as the perforation process of the sealing plate 22 progresses from (b) to (c) to (d). Therefore, as described in FIG. 6, there is a risk that a part of the sealing plate 22 may be torn off as a separation piece 22'P2 during the perforation process of the sealing plate 22.

[0049] On the other hand, as shown in the lower part of Figure 8, the cutting edge portion 73 of the piston rod 72 according to the embodiment has a tip edge line EL0 at its tip, which is shorter than the diameter of the piston rod 72 (the maximum outer diameter of the cutting edge portion 73). From the ends e1 and e2 of the tip edge line EL0, diagonal ridge lines EL11 to EL16 extend radially toward the side surface 721 of the piston rod 72. The piston blade surfaces PL1 to PL6 defined by these diagonal ridge lines EL11 to EL16 gradually expand the cross-sectional area of ​​the cutting edge portion 73 from the tip side to the base side. As shown in the lower part of Figure 8, the perforation area gradually expands as the perforation process of the sealing plate 22 progresses from (b) to (c) to (d). However, the length of the fold line FL gradually increases, unlike in Comparative Example 1. This is a technical feature unique to the cutting edge portion 73 according to the embodiment, which has three or more piston blade surfaces PL, and cannot be achieved in Comparative Example 1, which has only two piston blade surfaces PL. As a result, in this embodiment, the sealing plate 22 can be effectively prevented from being torn off until the perforation is completed as shown in (d). Therefore, the separated pieces 22'P2 of the sealing plate 22 can be effectively prevented from being transported to, for example, a gas supply target (airbag) through the gas flow path 17 in the gas discharge member 15.

[0050] In particular, according to the cutting edge portion 73 of the piston rod 72 in the embodiment, one end of multiple diagonal ridges gathers at each end e1, e2 of the tip ridge line EL0, and the other end of each diagonal ridge is connected to the side surface 721 of the piston rod 72, making it easy to form a multi-faceted cutting edge portion 73 having multiple piston blade surfaces PL.

[0051] Furthermore, the cutting edge portion 73 of the piston rod 72 in this embodiment has three or more piston blade surfaces PL, and therefore, compared to Comparative Example 1, which has only two piston blade surfaces PL', the perforating force when perforating the sealing plate 22 during operation of the perforator 1 can be increased. Furthermore, according to this embodiment, the length of the tip edge line EL0 can be made shorter than the diameter of the piston rod 72, and therefore, the collision energy required to split the sealing plate 22 can be made smaller than that of Comparative Example 1. In other words, according to this embodiment, even if the firing energy when firing the piston rod 72 during operation of the perforator 1 is small, it is possible to suitably perforate the sealing plate 22.

[0052] As Comparative Example 2, a piston rod R2 having a cutting edge portion EP2 including a single piston cutting surface PL' as shown in Fig. 9 is also possible. In the cutting edge portion EP2 of a single cut type as in Comparative Example 2, a portion of the sealing plate 22 is likely to tear off during the process of drilling the sealing plate 22, similar to the cutting edge portion EP1 of a two-cut type as in Comparative Example 1. Furthermore, as shown in the lower part of Fig. 9, the cutting edge portion EP2 of Comparative Example 2 pushes through the sealing plate 22 by shearing, which may result in blocking of the opening (gas flow path) formed by the sheared sealing plate 22.

[0053] 10 , a comparative example 3 is also possible, in which the cutting edge EP3 has a so-called conical shape, as in the piston rod R3. While this comparative example 3 has the advantage of making it easier to adjust the cutting edge insertion depth L2 of the cutting edge EP3 when the perforator 1 is operated, the lack of a ridge on the cutting edge makes it difficult to ensure sufficient perforation force on the sealing plate 22 when the perforator 1 is operated. Therefore, even if perforation of the sealing plate 22 is initiated starting from the vertex VP of the cutting edge EP3 when the perforator 1 is operated, the piston rod R3 may be pushed back by the pressure of the gas flowing out from the inside of the gas bottle 2, potentially preventing the formation of an opening having the required cross-sectional area. However, the piston rod 72 according to this embodiment can avoid the inconvenience of the comparative example 3.

[0054] <Modifications> Next, modifications of the piston rod 72 according to this embodiment will be described. FIG. 11 is a diagram illustrating the cutting edge 73A of the piston rod 72A according to Modification 1. FIG. 11A is a perspective view of the cutting edge 73A side of the piston rod 72A, and FIG. 11B is a front view thereof. Unlike the cutting edge 73 described in FIG. 4, the cutting edge 73A according to Modification 1 does not have a tip ridge EL0 formed on the tip side, and has a pointed cone shape with a vertex VP formed at the tip. The cutting edge 73A has multiple ridges extending from the vertex VP. Specifically, one end of each of the multiple ridges converges at the vertex VP, and the other end of each ridge extends to the side surface 721 of the piston rod 72A. The cutting edge 73A according to Modification 1 shown in FIG. 11 has a quadrangular pyramid shape with a square base, and four oblique ridges EL21 to EL24 extend from the vertex VP. The four piston blade surfaces PL1 to PL4 are separated by the ridge lines EL21 to EL24.

[0055] Figure 12 is a diagram illustrating a cutting edge portion 73B of a piston rod 72B according to Modification 2. As with Modification 1, the cutting edge portion 73B according to Modification 2 has multiple ridges, one end of which converges at a vertex VP, and the other end of each ridge extends to a side surface 721 of the piston rod 72A. The cutting edge portion 73B according to Modification 2 shown in Figure 12 has a triangular pyramid shape with a triangular base, and three oblique ridgelines EL31 to EL33 extend from the vertex VP. The ridgelines EL31 to EL33 then divide the cutting edge portion 73B into three piston cutting surfaces PL1 to PL3.

[0056] The piston rods 72A, 72B having the cutting edges 73A, 73B according to Modifications 1 and 2 also achieve the same technical effects as the piston rod 72 having the cutting edge 73 described above. That is, the cutting edges 73A, 73B according to Modifications 1 and 2 have a conical shape, which allows for easy adjustment of the cutting edge insertion depth L2 during operation of the perforator 1. Furthermore, like the cutting edge 73 described above, the cutting edges 73A, 73B include multiple ridges and three or more piston blade surfaces PL separated by the ridges. Therefore, the length of the fold line FL along which the sealing plate 22 is folded toward the rear during the perforation process of the sealing plate 22 is not shortened. As a result, tearing of the sealing plate 22 during perforation can be effectively prevented. Furthermore, unlike Comparative Example 3 described above, ridges are formed at the boundaries between the piston blade surfaces, resulting in excellent perforation (splitting) force when the perforator 1 is operated to perforate (split) the sealing plate 22.

[0057] Although the embodiments 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.

[0058] REFERENCE SIGNS LIST 1... Perforator 2... Gas bottle 3... Gas discharge device 10... First housing 21... Gas outlet 22... Sealing plate 40... Second housing 50... Initiator 60... First piston 70... Second piston 71... Piston head 72... Piston rod 73... Cutting edge

Claims

1. A perforator which is used with a gas bottle attached and which, when activated, discharges gas from a gas bottle by opening a sealing plate that seals a gas outlet of the gas bottle, comprising: a piston rod having a cutting edge portion at its tip which is positioned opposite the sealing plate when the perforator is attached to the gas bottle; and a drive unit which, when activated, launches the piston rod toward the sealing plate and causes the cutting edge portion to perforate the sealing plate, wherein the cutting edge portion has a plurality of ridges and three or more piston blade faces which are separated from one another by the ridges.

2. The perforator according to claim 1, wherein the cutting edge includes a tip ridge that forms the tip of the cutting edge, and the projected length of the tip ridge along the axial direction of the piston rod is smaller than the diameter of the piston rod.

3. The perforator according to claim 2, wherein one end of another ridge is connected to both ends of said tip ridge.

4. The perforator according to claim 2, wherein the other end of said other ridge extends to a side surface of said piston rod.

5. The perforator according to claim 3, wherein a plurality of said other ridges are connected to at least one end of said tip ridge.

6. A perforator as set forth in claim 5, wherein one end of each of said ridges meets at an apex formed at the tip of said cutting edge portion, and the other end of each ridge extends to a side surface of said piston rod.

7. A gas discharge device comprising: a perforator according to any one of claims 1 to 6; and a gas bottle attachable to the perforator.

Images