gas generator

Abstract

To provide a gas generator that can reliably ensure sealability for a long term, and can also be inexpensively manufactured.SOLUTION: A gas generator 1 comprises: a metallic holder 10; an igniter assembly 2 including an igniter 20 and a resin molding part 30; a cup 40; and a gas-generating agent 50. The cup 40 includes a flange 43, and the igniter assembly 2 is provided with an annular groove for receiving the flange 43. An inner wall surface of the annular groove is defined by an outer peripheral surface of a first covering part 31 of the resin molding part 30. A bottom surface of the annular groove is defined by a first end surface 10a of the holder 10. An outer wall surface of the annular groove is defined by an inner circumferential surface of an annular brim 13 provided on the holder 10. The annular brim 13 is bent inward to thereby assemble the cup 40 to the holder 10 ina state that a boundary between the first end surface 10a of the holder 10 and the outer peripheral surface of the first covering part 31 is covered with a sealing material 60 applied to an inside of the annular groove.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a gas generator, and particularly to a small gas generator configured to generate a relatively small amount of gas during operation.

Background Art

[0002] Conventionally, seat belt devices, which are occupant protection devices, have been widely used from the viewpoint of protecting occupants of automobiles and other vehicles. Seat belt devices are equipped for the purpose of protecting occupants from impacts generated during collisions of vehicles and the like, and restrain an occupant to a seat by wrapping the belt around the occupant's body. This prevents the occupant from being thrown into or out of the vehicle during a collision of the vehicle or the like.

[0003] Among seat belt devices, those equipped with a so-called pretensioner incorporate a small gas generator called a micro gas generator. A pretensioner is a device that instantly takes up slack in a seat belt caused by factors such as the thickness of clothing when a collision of a vehicle or the like is detected. This function is realized by one end of the seat belt being strongly pulled in by the pressure of gas output from the gas generator.

[0004] Generally, in this type of gas generator, manufacturing is performed by fixing a bottomed substantially cylindrical cup loaded with a gas generating agent to an igniter assembly in which an igniter for burning the gas generating agent is pre-assembled to a holder.

[0005] There are various structures for assembling an igniter to a holder. One of them is an assembly structure known in which an igniter is assembled to a holder by injection molding using a resin material as a raw material (more specifically, insert molding). Documents disclosing such an assembly structure include, for example, Japanese Patent Laid-Open No. 2003-161599 (Patent Document 1), Utility Model Registration No. 3134430 (Patent Document 2), Japanese Patent Laid-Open No. 2010-276263 (Patent Document 3), Japanese Patent Laid-Open No. 2019-99022 (Patent Document 4), and the like. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2003-161599 [Patent Document 2] Utility Model Registration No. 3134430 Gazette [Patent Document 3] Japanese Patent Publication No. 2010-276263 [Patent Document 4] Japanese Patent Publication No. 2019-99022 [Overview of the project] [Problems that the invention aims to solve]

[0007] In this case, when the igniter is assembled to the holder by injection molding using resin material as the raw material, it is necessary to ensure reliable sealing over the long term at the interface between the resin molded part formed by injection molding and the holder. In this regard, the above-mentioned Patent Documents 1 to 4 are configured to ensure sealing by providing various irregularities such as vertical walls and grooves on the surface of the holder in the part that will be covered by the resin molded part.

[0008] However, in order to ensure sealing performance by creating various irregularities such as vertical walls and grooves on the surface of the holder, it is necessary to perform extremely high-precision machining on the holder, and this is a major factor that drives up manufacturing costs.

[0009] Therefore, the present invention has been made to solve the above-mentioned problems, and aims to provide a gas generator that can reliably ensure long-term sealing performance at the interface between the resin molded part and the holder, and can be manufactured at low cost. [Means for solving the problem]

[0010] A gas generator according to the present invention comprises a gas generating agent that generates gas when burned, a bottomed, substantially cylindrical cup that houses the gas generating agent and has one end in the axial direction as an open end, and an igniter assembly having a substantially cylindrical outer shape that closes the open end of the cup when the cup is assembled coaxially with the igniter assembly. The igniter assembly includes an igniter having an ignition section loaded with an igniter charge and a terminal pin connected to the ignition section, a substantially cylindrical metal holder having a first end face which is the axial end face on the side facing the cup, a second end face which is the axial end face on the side not facing the cup, and a through portion that reaches the first end face and the second end face and through which at least a part of the igniter is inserted, and a resin molded part that fixes the igniter to the holder by filling the space between the igniter and the holder so that the ignition section faces the gas generating agent. The first end face of the holder is provided with a protruding annular flange that surrounds the through-hole. The resin molded part has a first covering portion that is fixed to and covers the portion of the first end face of the holder located around the through-hole, a second covering portion that is fixed to and covers the portion of the second end face of the holder located around the through-hole, and a connecting portion that connects the first covering portion and the second covering portion by embedding the through-hole. The cup has a flange portion that extends outward from the open end, and the axial end face of the igniter assembly facing the cup is provided with an annular groove portion that receives the flange portion. The inner wall surface of the annular groove portion is defined by the outer circumferential surface of the first covering portion, the bottom surface of the annular groove portion is defined by the first end face of the holder, and the outer wall surface of the annular groove portion is defined by the inner circumferential surface of the annular flange portion. In the gas generator according to the present invention described above, a sealant is applied to the inside of the annular groove and the flange portion is received in the annular groove, and the annular flange portion is bent inward, so that the boundary between the first end face of the holder exposed inside the annular groove and the outer peripheral surface of the first covering portion is covered with the sealant, and the flange portion is sandwiched between the annular flange portion and the bottom surface of the annular groove, thereby assembling the cup to the holder. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a gas generator that can reliably ensure long-term sealing performance at the interface between the resin molded part and the holder, and that can be manufactured at low cost. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic cross-sectional view of a gas generator according to an embodiment. [Figure 2] This is a schematic cross-sectional view along the line II-II shown in Figure 1. [Figure 3] This is a magnified view of region III shown in Figure 1. [Figure 4] Figure 1 is a schematic cross-sectional view of the igniter assembly during the manufacturing process of the gas generator shown. [Figure 5] Figure 1 is a schematic cross-sectional view showing the manufacturing method of the gas generator. [Figure 6] Figure 1 is a schematic cross-sectional view showing the manufacturing method of the gas generator. [Figure 7] Figure 1 is a schematic cross-sectional view showing the manufacturing method of the gas generator. [Figure 8] Figure 1 is a schematic cross-sectional view showing the manufacturing method of the gas generator. [Figure 9] Figure 1 is a schematic cross-sectional view showing the gas generator incorporated into the pretensioner. [Figure 10] Figure 1 is a schematic cross-sectional view showing how to attach a shorting clip to the gas generator. [Modes for carrying out the invention]

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The embodiments shown below exemplify a case where the present invention is applied to a gas generator (a so-called micro gas generator) suitably incorporated in a seatbelt device provided with a pretensioner. In the embodiments shown below, identical or common portions are denoted by the same reference numerals in the drawings, and description thereof will not be repeated.

[0014] Fig. 1 is a schematic cross-sectional view of a gas generator according to an embodiment, and Fig. 2 is a schematic cross-sectional view taken along the line II-II shown in Fig. 1. Further, Fig. 3 is an enlarged view of region III shown in Fig. 1, and Fig. 4 is a schematic cross-sectional view of an igniter assembly during the manufacture of the gas generator shown in Fig. 1. First, the configuration of the gas generator 1 according to the present embodiment will be described with reference to Figs. 1 to 4.

[0015] As shown in Figs. 1 to 3, the gas generator 1 according to the present embodiment includes an igniter assembly 2 having a substantially cylindrical outer shape composed of a holder 10, an igniter 20 and a resin molded portion 30, a substantially cylindrical cup 40 with a bottom, a gas generating agent 50, and a sealant 60. In the gas generator 1, the cup 40 is disposed coaxially with and assembled to the igniter assembly 2, whereby the holder 10 and the resin molded portion 30 of the igniter assembly 2 and the cup 40 constitute a housing that serves as the outer shell of the gas generator 1.

[0016] The gas generating agent 50 is accommodated in a space defined by the igniter assembly 2 and the cup 40, and the igniter 20 is fixed to the holder 10 via the resin molded portion 30 such that the ignition portion 21 thereof faces the gas generating agent 50. The sealant 60 is provided so as to be interposed between the cup 40 and the igniter assembly 2 at a predetermined position therebetween, and the details thereof will be described later.

[0017] As shown in Figures 1 and 2, the holder 10 is a component for holding the igniter 20 and the cup 40, and has a substantially cylindrical outer shape. In this embodiment, however, the holder 10 is provided with a recess 14 and a through-hole 10c, which will be described later, so the holder 10 has a substantially cylindrical shape.

[0018] More specifically, the holder 10 includes a cylindrical body portion 11 and a substantially disc-shaped partition portion 12 located inside the body portion 11 and at the axial end of the body portion 11 on the cup 40 side. An open through portion 10c is located in the center of the partition portion 12, and a recess 14 is located inside the body portion 11 and at the axial end of the body portion 11 opposite to the cup 40 side. These through portion 10c and recess 14 are connected to each other.

[0019] Here, the holder 10 has a first end face 10a, which is the axial end face on the side facing the cup 40, and this first end face 10a is defined by the axial end face of the body portion 11 on the cup 40 side and the main surface of the partition portion 12 on the cup 40 side. The holder 10 also has a second end face 10b, which is the axial end face on the side not facing the cup, and this second end face 10b is defined by the axial end face of the body portion 11 on the side opposite to the cup 40 side and the main surface of the partition portion 12 on the side opposite to the cup 40 side (more precisely, since the recess 14 described above is provided on this main surface, this main surface corresponds to the surface of the recess 14). The through portion 10c described above reaches both the first end face 10a and the second end face 10b of the holder 10.

[0020] Furthermore, the first end face 10a of the holder 10 is provided with a protruding annular flange portion 13 that surrounds the through portion 10c. This annular flange portion 13 is a part for crimping and fixing the flange portion 43 of the cup 40, which will be described later. When crimping and fixing, the annular flange portion 13 is bent inward, so that the flange portion 43 is sandwiched between it and the first end face 10a, thereby fixing the cup 40 to the holder 10 in a way that prevents it from moving. The annular flange portion 13 is located on the outer edge of the first end face 10a, so the first end face 10a is located between the through portion 10c and the annular flange portion 13.

[0021] As described above, the holder 10 is also a component that forms part of the housing, and is made of a molded product made of a metal material such as aluminum or an aluminum alloy. The holder 10 is formed into the shape shown in Figure 4 by performing forging, punching, and cutting as needed on a plate-shaped metal member or rod-shaped metal member that will be used as the raw material, one or more times in a predetermined order.

[0022] The igniter 20 is for generating a flame and is also called a squib. The igniter 20 has an ignition unit 21 and a pair of terminal pins 22. Inside the ignition unit 21 is an igniter that generates a flame by igniting and burning when in operation, and a resistor (bridge wire) for igniting this igniter. The pair of terminal pins 22 are connected to the ignition unit 21 to ignite the igniter.

[0023] More specifically, the ignition unit 21 includes a cup-shaped squib cup, the aforementioned resistor is attached to connect the tips of a pair of terminal pins 22 inserted into the squib cup, and an igniter is loaded into the squib cup so as to surround or be close to the resistor.

[0024] Here, nichrome wire is generally used as the resistor, and ZPP (zirconium potassium perchlorate), ZWPP (zirconium tungsten potassium perchlorate), lead tricinate, etc. are generally used as the igniter. The squib cup mentioned above is generally made of metal or plastic.

[0025] When a collision is detected, a predetermined amount of current flows through the resistor via terminal pin 22. This current generates Joule heat in the resistor, causing the igniter to begin burning. The high-temperature flame produced by the combustion ruptures the squib cup containing the igniter. The time from when current flows through the resistor until the igniter 20 activates is generally 2ms or less when a nichrome wire is used for the resistor.

[0026] The igniter 20 is attached to the holder 10 with a terminal pin 22 inserted through a through-hole 10c provided in the partition wall 12 of the holder 10. Specifically, the resin molded part 30 described above is provided around the holder 10 to fill the space between the holder 10 and the igniter 20, and the igniter 20 is assembled to the holder 10 by being held by the resin molded part 30.

[0027] The resin molded part 30 is formed by injection molding (more specifically, insert molding) using a mold, and is formed by adhering an insulating fluid resin material to the holder 10 so that it reaches from a part of the first end face 10a to a part of the second end face 10b of the holder 10 via a through-hole 10c provided in the partition wall portion 12 of the holder 10, and then solidifying it.

[0028] The igniter 20 is inserted into the holder 10 from the first end face 10a side during the molding of the resin molded part 30, with the terminal pin 22 inserted through the through-hole 10c. In this state, the above-mentioned fluid resin material is poured to fill the space between the igniter 20 and the holder 10, thereby fixing the igniter 20 to the holder 10 via the resin molded part 30.

[0029] Here, the size of the through-hole 10c provided in the holder 10 is smaller than the outer diameter of the ignition part 21, which is the largest outer diameter part of the igniter 20. By configuring it in this way, even if unexpected damage occurs to the resin molded part 30, it is possible to prevent the igniter 20 from passing through the through-hole 10c and flying out of the housing due to the rise in internal pressure of the housing space 44 (i.e., the space in which the gas generating agent 50 is housed), as described later, thereby ensuring the safe operation of the gas generator 1.

[0030] As the raw material for the resin molded part 30 formed by injection molding, a resin material with excellent heat resistance, durability, corrosion resistance, etc. after curing is preferably selected and used. In this case, it is not limited to thermosetting resins such as epoxy resin, but it is also possible to use thermoplastic resins such as polybutylene terephthalate resin, polyethylene terephthalate resin, polyamide resin (for example, nylon 6 or nylon 66), polypropylene sulfide resin, and polypropylene oxide resin. When selecting these thermoplastic resins as raw materials, it is preferable to include glass fibers or the like as fillers in these resin materials in order to ensure the mechanical strength of the resin molded part 30 after molding. However, if sufficient mechanical strength can be ensured with thermoplastic resin alone, it is not necessary to add the fillers as described above.

[0031] The resin molded part 30 has a first covering part 31 that covers a part of the first end face 10a of the holder 10, a second covering part 32 that covers a part of the second end face 10b of the holder 10, and a connecting part 33 that is located within a through part 10c provided in the partition wall part 12 of the holder 10 and connects the first covering part 31 and the second covering part 32.

[0032] The resin molded portion 30 is fixed to the holder 10 on the surface of the first covering portion 31, the second covering portion 32, and the connecting portion 33 on the holder 10 side. The resin molded portion 30 is also fixed to the side and bottom surface of the portion of the ignition portion 21 of the igniter 20 that is near the lower end, and to the surface of the portion of the terminal pin 22 of the igniter 20 that is near the upper end. As a result, the through portion 10c is completely embedded by the terminal pin 22 and the resin molded portion 30, and the airtightness of the space inside the housing is ensured by ensuring a seal in that portion.

[0033] Here, the first covering portion 31 is formed to cover the portion of the first end face 10a of the holder 10 adjacent to the through portion 10c, and its outer edge is located further inward at a distance from the annular flange portion 13 without reaching the annular flange portion 13. Therefore, the outer edge portion of the first end face 10a of the holder 10 is exposed and not covered by the first covering portion 31.

[0034] Furthermore, the first covering portion 31 is provided with a reinforcing portion 31a that protrudes upward along the side surface of the ignition portion 21 of the igniter 20. This reinforcing portion 31a is a part that adjusts the degree to which the squib cup of the igniter 20 opens when the gas generator 1 is in operation (i.e., prevents the squib cup from opening excessively). By providing this reinforcing portion 31a, it becomes possible to give directionality to the heat particles generated when the igniter 20 is in operation, and to efficiently guide these heat particles to the gas generating agent 50.

[0035] On the other hand, the second covering portion 32 is formed to include a first portion 32a that covers the surface of the recess 14 on the second end face 10b of the holder 10, and a second portion 32b that protrudes from the portion of the second end face 10b of the holder 10 where the recess 14 is not provided (i.e., the second end face 10b of the portion defined by the body portion 11) toward the side opposite to the side where the cup 40 is located. Furthermore, the second covering portion 32 is provided with a concave female connector portion 32c that straddles the first portion 32a and the second portion 32b.

[0036] The female connector portion 32c is positioned with the pair of terminal pins 22 of the igniter 20 exposed, and the female connector portion 32c functions as a part for receiving and holding a male connector (not shown) for external connection of the igniter 20 via the pair of terminal pins 22. That is, when the male connector of the harness connected to the control unit (not shown) is inserted into the female connector portion 32c, electrical conductivity is achieved between the core wire of the harness and the terminal pins 22, thereby connecting the igniter 20 and the control unit.

[0037] Furthermore, the portion of the inner surface of the female connector portion 32c defined by the aforementioned second portion 32b (i.e., the portion of the second covering portion 32 that protrudes from the second end face 10b of the holder 10 and does not have the recess 14) is provided with a recessed locking portion 32b1 for holding the shorting clip 80 (see Figure 10).

[0038] In this embodiment of the gas generator 1, a plurality of grooves 14a are provided on the surface of the recess 14, extending from the through portion 10c provided in the partition wall portion 12 of the holder 10 to the second end face 10b of the holder 10 in the portion where the recess 14 is not provided. These grooves 14a are provided so as to be scattered along the circumferential direction of the holder 10, and in this embodiment, as shown in Figure 2, three grooves 14a are provided so as to be evenly spaced along the circumferential direction. All of these grooves 14a are embedded by the second covering portion 32 of the resin molded portion 30.

[0039] This configuration allows the groove 14a and the second covering portion 32 that fills it to interlock, preventing the resin molded portion 30 from rotating relative to the holder 10. Furthermore, this configuration significantly improves the moldability of the resin molded portion 30 during injection molding, a point that will be described in detail later.

[0040] Furthermore, in the gas generator 1 according to this embodiment, as shown in Figure 1, if the protruding length of the second portion 32b of the second covering portion 32 is A, and the axial length of the holder 10 after the cup 40 is assembled to the holder 10 is B (i.e., the axial distance of the holder 10 from the upper end of the annular flange portion 13 after bending to the second end face 10b of the holder 10 in the portion where the recess 14 is not provided), then the protruding length A and the axial length B satisfy the condition B < 1.8 × A (hereinafter referred to as the "first condition").

[0041] In addition, in the gas generator 1 according to this embodiment, as shown in Figure 1, when the depth of the female connector portion 32c is C, the protruding length A and the depth C satisfy the condition C < 1.8 × A (hereinafter referred to as the "second condition").

[0042] By satisfying at least one of these first and second conditions, it becomes possible to significantly increase the protruding length A of the second portion 32b of the second covering portion 32. This has the effect of facilitating the insertion of the male connector after the gas generator 1 is assembled to the pretensioner, as described later, and also allows for an increase in the amount of gas generating agent 50 filled without increasing the size of the cup 40. These points will be described in detail later.

[0043] The igniter assembly 2, consisting of the holder 10, igniter 20, and resin molded part 30 as described above, is manufactured as a single integrated part by pre-assembling these parts together during the manufacturing of the gas generator 1. Subsequently, the remaining parts, the cup 40, gas generating agent 50, and sealant 60, are assembled to this single part, the igniter assembly 2, thereby manufacturing the gas generator 1.

[0044] Therefore, as shown in Figure 4, at the time the igniter assembly 2 is manufactured, the annular flange portion 13 provided on the first end face 10a of the holder 10 has not yet been bent inward and is standing upright along the axial direction of the holder 10. In this state, the annular groove portion 2a for receiving the flange portion 43 of the cup 40 is located on the axial end face of the igniter assembly 2 on the side to which the cup 40 is assembled, with the groove portion 2a open to the outside. The inner wall surface of the annular groove portion 2a (i.e., the side surface located radially inward) is defined by the outer circumferential surface of the first covering portion 31 of the resin molded portion 30, the bottom surface of the annular groove portion 2a is defined by the first end face 10a of the exposed portion of the holder 10, and the outer wall surface of the annular groove portion (i.e., the side surface located radially outward) is defined by the inner circumferential surface of the annular flange portion 13 provided on the holder 10.

[0045] As shown in Figures 1 and 3, the cup 40 is made of a bottomed, substantially cylindrical member with one axial end being an open end 41a, and has a side wall portion 41, a bottom wall portion 42, and a flange portion 43. The gas generating agent 50 is contained in the housing space 44 of the cup 40 defined by the side wall portion 41 and the bottom wall portion 42.

[0046] The open end 41a described above is formed at the end of the pair of axial ends of the side wall portion 41 that is opposite to the side where the bottom wall portion 42 is located. The flange portion 43 is positioned to extend outward from this open end 41a. The flange portion 43 is the part for fixing the cup 40 to the holder 10.

[0047] The bottom wall portion 42 of the cup 40 is provided with a score 42a by forming groove-shaped cuts on its surface. This score 42a is provided to create a weaker area at a predetermined position on the bottom wall portion 42 compared to other positions, and by providing this score 42a, the cup 40 can be configured to open starting from that part when the gas generator 1 is in operation.

[0048] The cup 40 is also a component that makes up part of the housing, and is made of a molded product made of a metal material such as aluminum, aluminum alloy, or iron-based material including stainless steel. Generally, press working using a mold is used to form the cup 40.

[0049] As described above, the cup 40 is assembled to the holder 10 by crimping and fixing its flange portion 43 to the holder 10 by the annular flange portion 13 provided on the holder 10. Specifically, with the flange portion 43 of the cup 40 inserted into the annular groove portion 2a provided on the igniter assembly 2, the annular flange portion 13 is bent inward, thereby fixing the cup 40 to the igniter assembly 2.

[0050] The gas generating agent 50 generates a large amount of gas when ignited and burned by the igniter 20. As the gas generating agent 50, molded bodies of smokeless powder (nitrocellulose) or molded bodies of non-azide compositions consisting of organic nitrogen compounds and oxidizing agents are used. Recently, however, there has been growing interest in using non-nitrocellulose gas generating agents as the gas generating agent 50, as these produce extremely low levels of harmful substances such as carbon monoxide.

[0051] The molded body of the gas generating agent 50 can be in various shapes, such as granules, pellets, cylinders, or discs. Perforated forms with through holes (e.g., macaroni or lotus root shapes) can also be used as molded bodies for the gas generating agent 50. The optimal shape is selected according to the specifications of the pretensioner to which the gas generator 1 is assembled. In addition to the shape, the size of the molded body of the gas generating agent 50 is selected considering factors such as linear combustion rate and pressure index. The amount of gas generating agent 50 to be filled can be appropriately changed according to the specifications of the pretensioner to which it is assembled, but when smokeless powder is used, it is generally around 0.1g to 2.0g.

[0052] As shown in Figures 1 and 3, when the cup 40 is assembled to the igniter assembly 2, as described above, the flange portion 43 of the cup 40 is housed in the annular groove portion 2a of the igniter assembly 2, and the flange portion 43 is sandwiched between the annular flange portion 13 and the bottom surface of the annular groove portion 2a. Here, a sealant 60 is interposed between the annular flange portion 13 and the annular groove portion 2a.

[0053] The sealant 60 is intended to airtightly seal the containment space 44 containing the gas generating agent 50 from the outside space, and specifically to prevent the flow of gas through the interface between the holder 10 and the cup 40 and the interface between the holder 10 and the resin molded part 30.

[0054] Specifically, the sealant 60 is positioned to fill the space defined by the bottom surface of the annular groove 2a defined by the first end face 10a of the holder 10, the lower part of the outer wall surface of the annular groove 2a defined by the inner circumferential surface of the annular flange 13 of the holder 10, the lower part of the inner wall surface of the annular groove 2a defined by the outer circumferential surface of the first covering portion 31 of the resin molded portion 30, and the lower surface of the flange portion 43 of the cup 40. As a result, it is interposed between the holder 10 and the cup 40 and covers the boundary 2b between the first end face 10a of the holder 10 and the outer circumferential surface of the first covering portion 31 that is exposed inside the annular groove 2a.

[0055] Here, any sealant 60 that exhibits sealing properties after curing can be used, but it is preferable that it has appropriate elasticity after curing. For example, sealants containing silicone resins or polyolefin resins as raw materials are suitably used.

[0056] The sealant 60 is applied in liquid form to the inside of the annular groove 2a prior to the crimping and fixing of the flange portion 43 by the annular flange portion 13 described above. In this state, the flange portion 43 is inserted into the annular groove 2a and the flange portion 43 is crimped and fixed by the annular flange portion 13, thereby forming the sealant to be interposed between the holder 10, the resin molded portion 30, and the cup 40 in the manner described above. The curing of the sealant 60 applied in liquid form may be performed before or after crimping and fixing, but it is preferable to perform the curing after crimping and fixing in order to more reliably ensure the sealing performance by the sealant 60.

[0057] Figures 5 to 8 are schematic cross-sectional views showing the manufacturing method of the gas generator according to this embodiment. Next, the manufacturing method of the gas generator 1 according to this embodiment will be described with reference to Figures 5 to 8.

[0058] In manufacturing the gas generator 1 according to this embodiment, first, the holder 10 is prepared. As described above, the holder 10 is manufactured by performing forging, punching, and, if necessary, cutting processes on a plate-shaped or rod-shaped metal member, which is the raw material, once or multiple times in a predetermined order. Here, the holder 10 provided in the gas generator 1 according to this embodiment does not have any complexly shaped parts on the surface of the part that will later be covered by the resin molded part 30, so high-precision cutting, which would be a factor in increasing costs, is not required.

[0059] Next, as shown in Figure 5(A), the holder 10 and igniter 20 are set in the injection molding die 200, which consists of an upper mold 201, a lower inner mold 202A, and a lower outer mold 202B. Specifically, of the lower inner mold 202A and lower outer mold 202B, which are pre-assembled, the holder 10 is set in the lower outer mold 202B, and in this state, the igniter 20 is set in the lower inner mold 202A so that the pair of terminal pins 22 of the igniter 20 pass through the through-hole 10c of the holder 10. Furthermore, the upper mold 201 is then assembled to the lower inner mold 202A and lower outer mold 202B so as to cover the holder 10 and igniter 20, thereby forming a cavity 203 with a shape corresponding to the resin molded part 30 around the holder 10 and igniter 20 located inside the mold 200.

[0060] Next, as shown in Figure 5(B), the resin molded part 30 is formed by injection molding. Specifically, an insulating fluid resin material is injected from the gate 201a provided in the upper mold 201 toward the cavity 203, thereby filling the cavity 203 with the fluid resin material. Subsequently, as the fluid resin material filled in the cavity 203 solidifies, it adheres to the surfaces of the holder 10 and the igniter 20, thereby forming the resin molded part 30 that fixes the holder 10 and the igniter 20 to each other.

[0061] Here, from the viewpoint of improving the moldability of the resin molding section 30, it is important that the fluid resin material injected into the cavity 203 flows into every corner of the cavity 203. In particular, if no measures are taken, due to the structure of the resin molding section 30, the flow of the fluid resin material may be obstructed at the position corresponding to the part of the resin molding section 30 that covers the second end face 10b of the holder 10 (i.e., the aforementioned first part 32a of the second covering section 32), which is the part where the cross-sectional area of ​​the cavity 203 is smallest in the direction perpendicular to the flow direction of the fluid resin material.

[0062] In this regard, in the gas generator 1 according to this embodiment, as described above, a plurality of grooves 14a are provided on the surface of the recess 14 of the holder 10, extending from the through-hole 10c provided in the partition wall 12 to the second end face 10b of the portion where the recess 14 is not provided. As a result, the cross-sectional area of ​​the cavity 203 in the region facing the portion where the plurality of grooves 14a are provided is larger than the cross-sectional area of ​​the cavity 203 in the region facing the portion where the plurality of grooves 14a are not provided. That is, the cavity 203 in the region facing the portion where the plurality of grooves 14a are not provided is configured as a narrow passage 203a through which the fluid resin material flows, while the cavity 203 in the region facing the portion where the plurality of grooves 14a are provided is configured as a wide passage 203b through which the fluid resin material flows.

[0063] Therefore, by providing a wide channel 203b through which the fluid resin material flows in a portion of the cavity 203 where the cross-sectional area is smallest in a direction perpendicular to the flow direction of the fluid resin material, the circulation of the fluid resin material within the cavity 203 is improved, and the fluid resin material reaches every corner of the cavity 203, dramatically improving the moldability of the resin molding section 30.

[0064] In addition, as described above, in the gas generator 1 according to this embodiment, the protruding length A of the second portion 32b of the second covering portion 32, the axial length B of the holder 10 after the cup 40 is assembled to the holder 10, and the depth C of the female connector portion 32c (all of which are shown in Figure 1) satisfy the first condition (i.e., the condition B < 1.8 × A) and / or the second condition (i.e., the condition C < 1.8 × A) described above, resulting in a significantly long protruding length A of the second portion 32b of the second covering portion 32.

[0065] Therefore, as the protruding length A of the second portion 32b of the second covering portion 32 is longer, the length of the narrow passage 203a described above is naturally shortened. In this respect as well, the circulation of the fluid resin material within the cavity 203 is improved, and the moldability of the resin molding portion 30 is dramatically improved.

[0066] Next, the igniter assembly 2, consisting of the holder 10, the igniter 20, and the resin molded part 30, is removed from the mold 200, and then, as shown in Figure 6, a sealant 60 is applied. Specifically, the liquid sealant 60 is applied to the annular groove 2a of the igniter assembly 2, which is defined by the outer circumferential surface of the first covering portion 31 of the resin molded part 30, the first end face 10a of the holder 10, and the inner circumferential surface of the annular flange portion 13 of the holder 10, using, for example, a dispenser 210. At that time, a sufficient amount of liquid sealant 60 is applied to cover the boundary 2b between the first end face 10a of the holder 10 and the outer circumferential surface of the first covering portion 31, which will be exposed inside the annular groove 2a after curing.

[0067] Next, as shown in Figures 7 and 8, the cup 40 is assembled to the igniter assembly 2. Specifically, as shown in Figure 7, first, the flange portion 43 of the cup 40, which contains a predetermined amount of gas generating agent 50, is inserted into the annular groove 2a of the igniter assembly 2, which has a liquid sealant 60 applied to the inside of the annular groove 2a. Subsequently, as shown in Figure 8, while maintaining the state in which the flange portion 43 is received in the annular groove 2a, the annular flange portion 13 provided on the holder 10 is bent inward (i.e., in the direction of arrow D shown in the figure), thereby crimping and fixing the flange portion 43 with the annular flange portion 13.

[0068] As a result, the flange portion 43 is sandwiched between the annular flange portion 13 and the bottom surface of the annular groove portion 2a, with the boundary 2b (see Figure 3) between the first end face 10a of the holder 10 exposed inside the annular groove portion 2a and the outer peripheral surface of the first covering portion 31 of the resin molded portion 30 being covered by the sealant 60, thereby allowing the cup 40 to be assembled to the ignition unit 2.

[0069] As described above, the hardening of the sealant 60 is performed before or after the crimping and fixing of the flange portion 43 by the annular flange portion 13, thereby completing the manufacture of the gas generator 1 as shown in Figure 1. In addition, since the sealant 60 not only covers the boundary 2b described above but is also interposed between the holder 10 and the cup 40, the sealant 60 makes it possible to ensure airtightness in both the portion between the holder 10 and the cup 40 and the portion between the holder 10 and the resin molded portion 30.

[0070] As described above, by using the gas generator 1 according to this embodiment, it becomes possible to ensure reliable sealing performance over the long term at the interface between the resin molded part 30 and the holder 10 by the sealant 60, and it also becomes possible to create a gas generator that can be manufactured inexpensively without requiring high-precision cutting.

[0071] Figures 9(A) and 9(B) are schematic cross-sectional views showing one example and another example of the gas generator according to this embodiment being incorporated into a pretensioner. Next, the assembly structure of the gas generator 1 according to this embodiment to the pretensioner will be described with reference to Figures 9(A) and 9(B).

[0072] As shown in Figure 9(A), when the gas generator 1 is incorporated into the pretensioner 100A of the seat belt device, the gas generator 1 is assembled into the substantially cylindrical casing 110 of the pretensioner 100A.

[0073] More specifically, the gas generator 1 is first inserted into the casing 110 from its axial end on the side where its cup 40 is located. At this time, the upper end of the annular flange 13 provided on the holder 10 of the gas generator 1 abuts against the stepped portion 111 provided on the inner circumferential surface of the casing 110, thereby positioning the gas generator 1 relative to the casing 110. In this positioned state, the second portion 32b of the second covering portion 32 of the resin molded portion 30 of the gas generator 1 and the tip portion of the casing 110 face each other in the radial direction of the casing 110.

[0074] Next, in this state, the tip portion of the casing 110 is bent inward (i.e., toward the second portion 32b of the second covering portion 32 of the gas generator 1), so that the body portion 11 of the holder 10 of the gas generator 1 is sandwiched between the crimped portion 112 of the bent portion of the casing 110 and the stepped portion 111 described above, thereby crimping and fixing the gas generator 1 to the casing 110.

[0075] As a result, the gas generator 1 is assembled to the pretensioner 100A. When the gas generator 1 is assembled to the pretensioner 100A, the second portion 32b of the second covering portion 32 of the gas generator 1 protrudes beyond the tip of the casing 110. Therefore, the second portion 32b of the second covering portion 32 acts as a guide, making it easier to insert the male connector into the female connector portion 32c provided on the second covering portion 32.

[0076] On the other hand, in the pretensioner 100B shown in Figure 9(B), the thickness of the casing 110 is greater than that of the pretensioner 100A described above, in order to improve its pressure resistance performance. In this case, as the thickness of the casing 110 increases, the thickness of the crimping portion 112 for crimping and fixing the gas generator 1 also increases. If the protrusion amount of the second portion 32b of the second covering portion 32 of the gas generator 1 described above is not sufficiently large, the second portion 32b of the second covering portion 32 of the gas generator 1 described above will not protrude beyond the tip of the casing 110, and the guide function described above will not be performed.

[0077] In this regard, in the gas generator 1 according to this embodiment, as described above, the protruding length A of the second portion 32b of the second covering portion 32, the axial length B of the holder 10 after the cup 40 is assembled to the holder 10, and the depth C of the female connector portion 32c (all of which are shown in Figure 1) satisfy the first condition (i.e., the condition B < 1.8 × A) and / or the second condition (i.e., the condition C < 1.8 × A) described above, so that the protruding length A of the second portion 32b of the second covering portion 32 is configured to be remarkably long.

[0078] Therefore, the amount of protrusion of the second portion 32b of the second covering portion 32 is sufficiently secured, and even when the thickness of the casing 110 increases, the guiding function of the second portion 32b of the second covering portion 32 is not lost and is performed, resulting in the effect of facilitating the insertion of the male connector.

[0079] In addition, referring to Figures 9(A) and 9(B), if a higher gas output is required, it is effective to increase the axial length of the cup 40 in order to increase the amount of gas generating agent 50 filled in the gas generator 1. However, if configured in this way, the amount of gas generator 1 inserted into the casing 110 will inevitably increase, and in order to secure the internal volume of the casing 110 in the portion where the gas generator 1 is not inserted, the casing 110 will also need to be made longer by that amount, which leads to the problem of increasing the size of the pretensioners 100A and 100B.

[0080] In this regard, in the gas generator 1 according to this embodiment, since the first and / or second conditions described above are met, the protruding length A of the second portion 32b of the second covering portion 32 is significantly long, so that the female connector portion 32c can be positioned retracted in the direction away from the cup 40 along the axial direction of the gas generator 1, and consequently, the resin molded portion 30, the partition wall portion 12 of the holder 10 and the igniter 20 can also be positioned retracted in the direction away from the cup 40.

[0081] Therefore, even without increasing the axial length of the cup 40, the volume of the housing space 44 increases by the amount that the resin molded part 30, the partition wall part 12 of the holder 10, and the igniter 20 are moved back, and the amount of gas generating agent 50 that can be filled can be increased accordingly. Thus, by adopting this configuration, it becomes possible to achieve higher gas output when required without increasing the size of the pretensioners 100A and 100B.

[0082] Figure 10 is a schematic cross-sectional view showing how to attach a shorting clip to the gas generator according to this embodiment. Next, a method for attaching a shorting clip 80 to the gas generator 1 according to this embodiment will be described with reference to Figure 10.

[0083] In the gas generator 1 according to this embodiment, it is necessary to prevent malfunctions from occurring due to, for example, electrostatic discharge before installation in a vehicle. As shown in Figure 10, the shorting clip 80 is attached to the female connector portion 32c of the gas generator 1 in order to prevent such malfunctions. When the shorting clip 80 is attached to the female connector portion 32c, the pair of terminal pins 22 of the igniter are intentionally short-circuited by the conductive leaf spring portion (not shown) of the shorting clip 80.

[0084] When attaching the shorting clip 80 to the gas generator 1, the shorting clip 80 is inserted into the female connector portion 32c of the gas generator 1. At this time, multiple locking portions 81 provided on the circumferential surface of the shorting clip 80 are locked by locking portions 32b1 provided on the inner surface of the female connector portion 32c. The locking of the locking portions 81 by these locking portions 32b1 fixes the shorting clip 80 to the female connector portion 32c.

[0085] Furthermore, the shorting clip 80 is provided with a hollow portion (not shown) that receives a pair of terminal pins 22 of the igniter 20, and the aforementioned leaf spring portion is arranged in this hollow portion. This leaf spring portion is configured to be able to contact both of the pair of terminal pins 22 in an elastically biased state when the shorting clip 80 is fixed to the female connector portion 32c, thereby maintaining a short-circuited state between the pair of terminal pins 22.

[0086] In this embodiment, since the first and / or second conditions described above are met, the protruding length A (see Figure 1) of the second portion 32b of the second covering portion 32 is significantly long. Therefore, the locking portion 32b1 provided on the gas generator 1 is provided on the portion of the inner surface of the female connector portion 32c that is defined by the second portion 32b described above.

[0087] Next, referring to Figure 1 mentioned above, the operation of the gas generator 1 according to this embodiment will be described.

[0088] Referring to Figure 1, if a vehicle equipped with the gas generator 1 according to this embodiment collides, the collision is detected by a collision detection means separately provided on the vehicle, and based on this, the igniter 20 is activated by the power supplied from the control unit. When the igniter 20 is activated, the igniter contained in the ignition unit 21 is ignited and burns, causing the squib cup to rupture.

[0089] The flame generated by the combustion of the igniter is ejected into the containment space 44 where the gas generating agent 50 is contained as the squib cup ruptures. This flame ignites and burns the gas generating agent 50, generating a large amount of gas in the containment space 44. The combustion of the gas generating agent 50 causes the internal pressure of the containment space 44 to rise rapidly, which causes the bottom wall 42 of the cup 40 to open starting from the score 42a, and the large amount of gas generated is released to the outside of the gas generator 1.

[0090] Subsequently, the large amount of gas discharged from the gas generator 1 is guided into the operating space of the pretensioner into which the gas generator 1 is incorporated (i.e., the space inside the casing 110 as described above (see Figures 9(A) and 9(B), etc.)). This drives the pretensioner, causing one end of the seat belt attached to the seat belt device to be strongly pulled in.

[0091] The characteristic configuration of the gas generator disclosed in the above-described embodiment can be summarized as follows:

[0092] [Note 1] A gas generating agent that produces gas when burned, A bottomed, substantially cylindrical cup containing the above-mentioned gas generating agent, with one end in the axial direction being an open end, The igniter assembly comprises a substantially cylindrical outer shape that closes the open end of the cup when the cup is mounted coaxially, The above ignition assembly is An igniter having an ignition section loaded with igniter powder and terminal pins connected to the ignition section, A substantially cylindrical metal holder having a first end face which is the axial end face on the side facing the cup, a second end face which is the axial end face on the side not facing the cup, and a through portion that reaches the first end face and the second end face and through which at least a part of the igniter is inserted, The igniter includes a resin molded part that fills the space between the igniter and the holder, thereby fixing the igniter to the holder so that the ignition part faces the gas generating agent. The first end face of the holder is provided with a protruding annular flange that surrounds the through portion. The resin molded part has a first covering portion that is fixed to and covers the portion of the first end face of the holder located around the through portion, a second covering portion that is fixed to and covers the portion of the second end face of the holder located around the through portion, and a connecting portion that connects the first covering portion and the second covering portion by embedding the through portion. The cup described above has a flange portion extending outward from the open end, The axial end face of the igniter assembly facing the cup is provided with an annular groove for receiving the flange portion. The inner wall surface of the annular groove is defined by the outer circumferential surface of the first covering portion. The bottom surface of the annular groove is defined by the first end surface of the holder. The outer wall surface of the annular groove is defined by the inner circumferential surface of the annular flange. A gas generator in which a sealant is applied to the inside of the annular groove and the flange is received in the annular groove, and the annular flange is bent inward, so that the boundary between the first end face of the holder exposed inside the annular groove and the outer surface of the first covering is covered with the sealant, and the flange is sandwiched between the annular flange and the bottom surface of the annular groove, thereby assembling the cup to the holder.

[0093] [Note 2] The second end face of the holder is provided with a recess that leads to the through portion. The second covering portion is provided to include a first portion which covers the recess and a second portion which protrudes from the second end face of the holder in the portion where the recess is not provided toward the side opposite to the side where the cup is located. The gas generator as described in Appendix 1, wherein the above-mentioned terminal pins are arranged, and a recessed female connector portion for receiving and holding a male connector for external connection of the igniter via the terminal pins is provided spanning the first portion and the second portion of the second covering portion.

[0094] [Note 3] The gas generator described in Appendix 2 satisfies the condition B < 1.8 × A, where A is the protruding length of the second part described above, and B is the axial length of the holder after the cup has been assembled to the holder.

[0095] [Note 4] The gas generator described in Appendix 2 satisfies the condition C < 1.8 × A, where A is the protruding length of the second part and C is the depth of the female connector part.

[0096] [Note 5] The gas generator according to any one of the appendices 2 to 4, wherein a recessed locking portion for holding a shorting clip is provided on the inner surface of the female connector portion as defined by the second portion.

[0097] [Note 6] A groove is provided on the surface of the recess, extending from the through portion to the second end face of the holder in the portion where the recess is not provided. The gas generator according to any one of the appendices 2 to 5, wherein the groove portion described above is embedded by the second covering portion described above.

[0098] In the embodiments described above, the example given was a case in which a gas generator is manufactured by applying a sealant to the inside of the annular groove before crimping the annular flange. However, the sealant may be applied only to the flange portion of the cup beforehand without applying it to the inside of the annular groove before crimping the annular flange, or the sealant may be applied to both the inside of the annular groove and the flange portion before crimping the annular flange.

[0099] Furthermore, the shape, configuration, size, number, material, etc., of each part shown in the above-described embodiment can be modified as appropriate, as long as they do not deviate from the spirit of the present invention.

[0100] Thus, the embodiments disclosed herein are illustrative in all respects and not restrictive. The technical scope of the present invention is defined by the claims and includes all modifications within the meaning and scope of equivalents to the claims. [Explanation of symbols]

[0101] 1 Gas generator, 2 Ignition assembly, 2a Annular groove, 2b Boundary, 10 Holder, 10a First end face, 10b Second end face, 10c Through section, 11 Body section, 12 Partition section, 13 Annular flange section, 14 Recess, 14a Groove section, 20 Ignition, 21 Ignition section, 22 Terminal pin, 30 Resin molded section, 31 First covering section, 31a Reinforcement section, 32 Second covering section, 32a First part, 32b Second part, 32b1 Locking section, 32c Female connector section, 33 Connection section, 40 Cup, 41 Side wall section, 41a Open end, 42 Bottom wall section, 42a Score, 43 Flange section, 44 Housing space, 50 Gas generating agent, 60 Sealant, 80 Shorting clip, 81 Locking part, 100A, 100B Pretensioner, 110 Casing, 111 Stepped part, 112 Crimping part, 200 Mold, 201 Upper mold, 201a Gate, 202A Lower inner mold, 202B Lower outer mold, 203 Cavity, 203a Narrow passage, 203b Wide passage, 210 Dispenser.

Claims

1. A gas generating agent that produces gas when burned, A bottomed, substantially cylindrical cup containing the gas generating agent, with one end in the axial direction being an open end, The igniter assembly comprises a substantially cylindrical outer shape that closes the open end of the cup when the cup is mounted coaxially, The igniter assembly is An igniter having an ignition section loaded with igniter powder and terminal pins connected to the ignition section, A substantially cylindrical metal holder having a first end face which is the axial end face on the side facing the cup, a second end face which is the axial end face on the side not facing the cup, and a through portion that reaches the first end face and the second end face and through which at least a part of the igniter is inserted, The igniter includes a resin molded part that fills the space between the igniter and the holder, thereby fixing the igniter to the holder such that the ignition part faces the gas generating agent. The first end face of the holder is provided with a protruding annular flange that surrounds the through portion. The resin molded portion has a first covering portion fixed to and covering the portion of the first end face of the holder located around the through portion, a second covering portion fixed to and covering the portion of the second end face of the holder located around the through portion, and a connecting portion that connects the first covering portion and the second covering portion by embedding the through portion. The cup has a flange portion extending outward from the open end, The axial end face of the igniter assembly facing the cup is provided with an annular groove for receiving the flange portion. The inner wall surface of the annular groove is defined by the outer circumferential surface of the first covering portion. The bottom surface of the annular groove is defined by the first end surface of the holder, The outer wall surface of the annular groove is defined by the inner circumferential surface of the annular flange, A gas generator in which a sealant is applied to the inside of the annular groove and the flange portion is received in the annular groove, and the annular flange portion is bent inward, so that the boundary between the first end face of the holder and the outer peripheral surface of the first covering portion, which is exposed inside the annular groove, is covered by the sealant, and the flange portion is sandwiched between the annular flange portion and the bottom surface of the annular groove, thereby assembling the cup to the holder.

2. The second end face of the holder is provided with a recess that leads to the through portion. The second covering portion is provided to include a first portion which covers the recess and a second portion which protrudes from the second end face of the holder in the portion where the recess is not provided toward the side opposite to the side where the cup is located. The gas generator according to claim 1, wherein the terminal pins are arranged and a concave female connector portion for receiving and holding a male connector for external connection of the igniter via the terminal pins is provided spanning the first portion and the second portion of the second covering portion.

3. The gas generator according to claim 2, wherein the protruding length of the second portion is A, and the axial length of the holder after the cup is assembled to the holder is B, and the condition B < 1.8 × A is satisfied.

4. The gas generator according to claim 2, wherein the protruding length of the second portion is A and the depth of the female connector portion is C, and the condition C < 1.8 × A is satisfied.

5. The gas generator according to any one of claims 2 to 4, wherein a recessed locking portion for holding a shorting clip is provided on the inner surface of the female connector portion as defined by the second portion.

6. A groove is provided on the surface of the recess, extending from the through portion to the second end face of the holder in the portion where the recess is not provided. The gas generator according to any one of claims 2 to 4, wherein the groove is embedded by the second covering portion.

Images