Gas generator

Abstract

To provide a gas producer which can be so controlled that while a cup body is increased in mechanical strength, a size of rupture of the cup body becomes stable.SOLUTION: A gas producer comprises: a short-sized cylindrical housing in which a gas producing agent is accommodated; an ignitor which includes an ignition part accommodating an ignition charge; and a cup-shaped member which includes an inflammation chamber accommodating a transfer charge thereinside and is formed of a single member in a bottomed cylindrical shape, in which a brittle portion which is partially thin is arranged at a top wall part of the cup-shaped member, and a side wall portion of the cup-shaped member is higher in mechanical strength than the brittle portion. The side wall portion of the cup-shaped member comprises a thin portion provided on the top wall part side and a thick portion extending from the thin portion to the opposite side from the top wall portion along an axial direction, in which the brittle portion has sufficient mechanical strength to rupture the cup-shaped member earlier than the side wall portion as the ignitor operates, and the thin portion has sufficient mechanical strength to rupture, deform, or melt when the brittle portion ruptures up to the thin portion.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a gas generator incorporated in an occupant protection device for protecting an occupant in the event of a vehicle collision, and more particularly to a gas generator incorporated in an airbag device mounted on an automobile or the like. [Background technology]

[0002] Conventionally, airbag devices, which are passenger protection devices, have become widespread from the viewpoint of protecting passengers in automobiles, etc. Airbag devices are installed for the purpose of protecting passengers from impacts that occur when a vehicle or the like crashes, and the airbag instantly inflates and deploys when a vehicle or the like crashes, so that the airbag acts as a cushion to receive the body of the passenger.

[0003] The gas generator is a device incorporated in the airbag device. When a vehicle crashes, the control unit supplies electricity to ignite an igniter, which produces a flame that burns a gas generating agent, instantly generating a large amount of gas, thereby inflating and deploying the airbag.

[0004] Gas generators are available in a variety of structures. A gas generator that is particularly suitable for use in a driver's side airbag device, a passenger's side airbag device, etc. is a short, approximately cylindrical disk-type gas generator with a comparatively large outer diameter.

[0005] A disk-type gas generator has a short, approximately cylindrical housing with both axial ends closed, a plurality of gas outlets provided in the peripheral wall of the housing, a transfer charge contained inside the housing so as to face an igniter attached to the housing, a gas generating agent is filled inside the housing so as to surround the transfer charge, and a filter is contained inside the housing so as to further surround the gas generating agent.

[0006] An example of a document disclosing a specific configuration of this disk-type gas generator is Japanese Patent Application Laid-Open No. 2004-217059 (Patent Document 1).

[0007] Patent Document 1 discloses a gas generator in which a cup body filled with a transfer charge and an igniter collar that holds an igniter main body are crimped and fixed at a bent portion on the lower end side of a crimp case. The cup body is made of a metal such as aluminum and has a weak portion on at least one of the closed end face and the peripheral wall portion, and since the cup body is easily ruptured at the weak portion, the pressure applied to the crimp case is reduced, and as a result, the crimp case is prevented from falling off or being damaged. However, since the cup body is made of a thin aluminum plate, its mechanical strength is low, and there is a problem that the rupture strength of the cup body cannot be increased when the transfer charge is burned. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2004-217059 A Summary of the Invention [Problem to be solved by the invention]

[0009] In order to sufficiently burn the enhancer charge, it is necessary to increase the internal pressure of the cup body to improve the burning speed of the enhancer charge. This is because the gas generating agent inside the gas generator can be burned efficiently in a short time and the gas can be ejected into the airbag. However, generally, when the mechanical strength of the cup body (cup-shaped member) is increased, problems such as restrictions on the rupture (breakage), deformation or melting of the cup body, or the size of the rupture (breakage) of the cup body becoming unstable and the output characteristics of the generated gas being reduced are likely to occur. That is, generally, there is a trade-off between increasing the mechanical strength of the cup body and controlling the size of the rupture (breakage) of the cup body (uniformization of the breakage area).

[0010] Therefore, the present invention has been made to solve the above-mentioned problems, and has an object to provide a gas generator that can control the size of the rupture of the cup body so that it is stable (the rupture area is made uniform) while increasing the mechanical strength of the cup body. [Means for solving the problem]

[0011] (1) A gas generator of the present invention comprises a short cylindrical housing constituted by a cylindrical peripheral wall portion provided with a gas outlet, a top plate portion closing one axial end of the peripheral wall portion, and a bottom plate portion closing the other axial end of the peripheral wall portion, the housing having a combustion chamber therein containing a gas generating agent, an igniter assembled to the bottom plate portion and including an ignition portion housing an ignition charge that is ignited when activated, and a cup-shaped member made of a single cylindrical member with a bottom, the cup-shaped member including a transfer chamber therein housing a transfer charge and disposed so as to protrude toward the combustion chamber such that the internal space of the transfer chamber faces the ignition portion, the cup-shaped member having a top wall portion forming a bottom surface, the top wall portion of the cup-shaped member having at least a thin-walled fragile portion disposed in at least a portion thereof, the cup-shaped member having a side wall portion of the cup-shaped member having a mechanical strength higher than that of the fragile portion that separates the transfer chamber from the combustion chamber, the side wall portion having a thickness greater than that of the top wall portion, the thin-walled portion is disposed opposite the ignition portion and has a mechanical strength such that the cup-shaped member ruptures, deforms, or melts before the side wall portion ruptures in response to activation of the igniter, the thin-walled portion has a mechanical strength such that the cup-shaped member ruptures, deforms, or melts when the rupture, deformation, or melting in the weak portion advances to the thin-walled portion, and the thick-walled portion has a mechanical strength such that the cup-shaped member ruptures, deforms, or melts even when the rupture, deformation, or melting in the weak portion advances to the thin-walled portion and the thin-walled portion ruptures, deforms, or melts, and the connecting portion has a step shape formed on the outside of the side wall portion by utilizing a difference in thickness between the thin-walled portion and the thick-walled portion. The weak portion disposed on the top wall portion of the cup-shaped member is thinner than the side wall portion of the cup-shaped member, and the top wall portion of the cup-shaped member is composed of a weak portion-existing region where rupture, deformation or melting occurs initially from the weak portion due to combustion of the transfer charge accompanying activation of the igniter, and a weak portion-free region where rupture, deformation or melting occurs progressing from the rupture, deformation or melting of the weak portion-existing region a predetermined time after the rupture, deformation or melting of the weak portion-existing region.

[0014] (2 In the gas generator of (1) above, the weakened portion is preferably in the form of slits provided radially from the center in the top wall portion.

[0015] ( 3 In the gas generator of (1) above, the cup-shaped member is preferably made of a metal or an alloy.

[0016] ( 4 ) The gas generator of (1) above preferably further comprises a filter provided circumferentially inside the housing, and a support member having a circular plate-shaped base provided in a direction along the inner bottom surface of the bottom plate, an abutment portion abutting against the inner circumferential surface of the end of the filter on the bottom plate side, and a tubular upright portion upright from the base toward the top plate side, and the support member is held by the cup-shaped member by pressing the upright portion into the thick-walled portion of the cup-shaped member.

[0017] ( 5 ) The gas generator of (1) above further comprises a filter provided circumferentially on the inside of the housing, and the cup-shaped member further has a circular plate-shaped base provided in a direction along the inner bottom surface of the bottom plate, a contact portion contacting the inner circumferential surface of the end portion of the filter on the bottom plate side, and a tubular upright portion upright from the base toward the top plate side, and it is preferable that the upright portion is integrally extended from the side wall portion of the cup-shaped member. Effect of the Invention

[0018] According to the present invention, it is possible to provide a gas generator that can be controlled so that the size of the rupture of the cup body is stable (the rupture area is uniform) while increasing the mechanical strength of the cup body. Furthermore, since the size of the rupture of the cup body is stable (the rupture area is uniform), it is possible to provide a gas generator that can exhibit predetermined performance while reducing the amount of transfer charge. [Brief description of the drawings]

[0019] [Figure 1] 1 is a schematic cross-sectional view of a disk-type gas generator according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a perspective view of a cup-shaped member of the disk-type gas generator of FIG. 1. [Diagram 3] FIG. 2 is a schematic cross-sectional view for illustrating the operation of the disk-type gas generator of FIG. [Figure 4] FIG. 1 is a diagram showing test conditions and test results of a verification test. [Diagram 5] FIG. 2A is a schematic cross-sectional view of the shape of a cup-shaped member used in a verification test, and FIG. 2B is a diagram showing the test conditions and test results of the verification test. [Figure 6] FIG. 2A is a schematic cross-sectional view of the shape of a cup-shaped member used in a verification test, and FIG. 2B is a diagram showing the test conditions and test results of the verification test. [Figure 7] FIG. 11 is a perspective view of a cup-shaped member according to a modified example of the embodiment of the present invention. [Figure 8] FIG. 11 is a schematic cross-sectional view of a gas generator according to a modified example of the embodiment of the present invention. [Figure 9] FIG. 11 is a schematic cross-sectional view of a gas generator according to a modified example of the embodiment of the present invention. [Figure 10] 10A to 10C are perspective views of cup-shaped members according to various modified examples of the embodiment of the present invention. [Figure 11] FIG. 11 is a schematic cross-sectional view of a gas generator according to a modified example of the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the embodiment shown below, the present invention is applied to a disk-type gas generator that is suitably incorporated in an airbag device mounted on the steering wheel of an automobile. In the embodiment shown below, the same or common parts are given the same reference numerals in the drawings, and their description will not be repeated.

[0021] Fig. 1 is a schematic diagram of a disk-type gas generator 100 in an embodiment of the present invention. First, with reference to Fig. 1, the configuration of disk-type gas generator 100 in the present embodiment will be described.

[0022] As shown in Fig. 1, disk-type gas generator 100 has a short, substantially cylindrical housing with one and the other axial ends closed, and an accommodation space provided inside this housing accommodates internal components such as retainer 30, igniter 40, cup-shaped member 50, transfer charge 59, gas generating agent 61, lower support member 70, upper support member 80, cushion material 85, and filter 90. Also, a combustion chamber 60 is located in the accommodation space provided inside the housing, in which is mainly accommodated gas generating agent 61, one of the above-mentioned internal components.

[0023] The housing includes a lower shell 10 and an upper shell 20. Each of the lower shell 10 and the upper shell 20 is a press-molded product formed by pressing a rolled metal plate-like member, for example. The metal plate-like member constituting the lower shell 10 and the upper shell 20 is made of a metal plate made of, for example, stainless steel, iron steel, aluminum alloy, stainless alloy, etc., and preferably a so-called high-tensile steel plate that does not break or otherwise break even when a tensile stress of 440 MPa or more and 780 MPa or less is applied is used.

[0024] The lower shell 10 and the upper shell 20 are each formed in a generally cylindrical shape with a bottom, and are assembled and joined together with their open faces facing each other to form a housing. The lower shell 10 has a bottom plate portion 11 and a peripheral wall portion 12, and the upper shell 20 has a top plate portion 21 and a peripheral wall portion 22.

[0025] The upper end of the peripheral wall 12 of the lower shell 10 is inserted into the lower end of the peripheral wall 22 of the upper shell 20 and press-fitted. Furthermore, the peripheral wall 12 of the lower shell 10 and the peripheral wall 22 of the upper shell 20 are joined at or near their abutment, thereby fixing the lower shell 10 and the upper shell 20. Here, electron beam welding, laser welding, friction welding, or the like can be suitably used to join the lower shell 10 and the upper shell 20.

[0026] As a result, the portion of the peripheral wall of the housing closer to the bottom plate 11 is formed by the peripheral wall 12 of the lower shell 10, and the portion of the peripheral wall of the housing closer to the top plate 21 is formed by the peripheral wall 22 of the upper shell 20. Moreover, one and the other axial ends of the housing are closed by the bottom plate 11 of the lower shell 10 and the top plate 21 of the upper shell 20, respectively.

[0027] A protruding tubular portion 13 that protrudes toward the top plate portion 21 is provided in the center of the bottom plate portion 11 of the lower shell 10, thereby forming a recessed portion 14 in the center of the bottom plate portion 11 of the lower shell 10. The protruding tubular portion 13 is a portion where the igniter 40 is fixed via the holding portion 30, and the recessed portion 14 is a portion that provides a space for providing the female connector portion 34 in the holding portion 30.

[0028] The protruding tube portion 13 is formed in a generally cylindrical shape with a bottom, and an opening 15 having a point-asymmetric shape (for example, a D-shape, a barrel shape, an ellipse shape, etc.) in a plan view is provided at the axial end portion located on the top plate portion 21 side. The opening 15 is a portion through which a pair of terminal pins 42 of the igniter 40 are inserted.

[0029] The igniter 40 is for generating a flame, and includes an ignition unit 41 and the above-mentioned pair of terminal pins 42. The ignition unit 41 contains therein an ignition charge that ignites and burns to generate a flame when activated, and a resistor for igniting the ignition charge. The pair of terminal pins 42 are connected to the ignition unit 41 for igniting the ignition charge.

[0030] More specifically, the ignition section 41 comprises a squib cup formed in a cup shape, and a plug which closes the open end of the squib cup and through which a pair of terminal pins 42 are inserted and held. A resistor (bridge wire) is attached to connect the tips of the pair of terminal pins 42 inserted into the squib cup, and an ignition charge is loaded into the squib cup so as to surround or be adjacent to the resistor.

[0031] 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 ignition charge. The squib cup and plug mentioned above are generally made of metal or plastic.

[0032] When a collision is detected, a predetermined amount of current flows through the resistor via the terminal pin 42. When a predetermined amount of current flows through the resistor, Joule heat is generated in the resistor, and the ignition charge begins to burn. The high-temperature flame generated by the combustion explodes the squib cup that contains the ignition charge. The time from when the current flows through the resistor to when the igniter 40 is activated is generally 2 ms or less when nichrome wire is used as the resistor.

[0033] The igniter 40 is attached to the bottom plate portion 11 in a state where it is inserted from the inside of the lower shell 10 so that the terminal pin 42 passes through the opening 15 provided in the protruding tubular portion 13. Specifically, a holding portion 30 made of a resin molded portion is provided around the protruding tubular portion 13 provided on the bottom plate portion 11, and the igniter 40 is fixed to the bottom plate portion 11 by being held by the holding portion 30.

[0034] The retaining portion 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 bottom plate portion 11 so that the material reaches from a portion of the inner surface of the bottom plate portion 11 to a portion of the outer surface of the bottom plate portion 11 through an opening 15 provided in the bottom plate portion 11 of the lower shell 10, and then solidifying the material. The squib cup has an ignition charge loaded therein so as to contact the ignition source.

[0035] 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 ignition charge. The squib cup and plug mentioned above are generally made of metal or plastic.

[0036] When a collision is detected, a predetermined amount of current flows through the resistor via the terminal pin 42. When a predetermined amount of current flows through the resistor, Joule heat is generated in the resistor, and the ignition charge begins to burn. The high-temperature flame generated by the combustion explodes the squib cup that contains the ignition charge. The time from when the current flows through the resistor to when the igniter 40 is activated is generally 2 ms or less when nichrome wire is used as the resistor.

[0037] The igniter 40 is attached to the bottom plate portion 11 in a state where it is inserted from the inside of the lower shell 10 so that the terminal pin 42 passes through the opening 15 provided in the protruding tubular portion 13. Specifically, a holding portion 30 made of a resin molded portion is provided around the protruding tubular portion 13 provided on the bottom plate portion 11, and the igniter 40 is fixed to the bottom plate portion 11 by being held by the holding portion 30.

[0038] The retaining portion 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 bottom plate portion 11 so that the material reaches from a portion of the inner surface of the bottom plate portion 11 to a portion of the outer surface of the bottom plate portion 11 through an opening 15 provided in the bottom plate portion 11 of the lower shell 10, and then solidifying the material.

[0039] As the raw material of the holding part 30 formed by injection molding, a resin material having excellent heat resistance, durability, corrosion resistance, etc. after hardening is suitably selected and used. In this case, it is possible to use not only thermosetting resins such as epoxy resins, but also thermoplastic resins such as polybutylene terephthalate resin, polyethylene terephthalate resin, polyamide resin (e.g., nylon 6, nylon 66, etc.), polypropylene sulfide resin, polypropylene oxide resin, etc. When these thermoplastic resins are selected as raw materials, it is preferable to include glass fiber or the like as a filler in these resin materials in order to ensure the mechanical strength of the holding part 30 after molding. However, if sufficient mechanical strength can be ensured with only the thermoplastic resin, it is not necessary to add the above-mentioned filler.

[0040] The retaining portion 30 has an inner covering portion 31 covering part of the inner surface of the bottom plate portion 11 of the lower shell 10, an outer covering portion 32 covering part of the outer surface of the bottom plate portion 11 of the lower shell 10, and a connecting portion 33 located within an opening 15 provided in the bottom plate portion 11 of the lower shell 10 and continuous with the inner covering portion 31 and the outer covering portion 32, respectively.

[0041] The retaining portion 30 is fixed to the bottom plate portion 11 at the surfaces of the inner covering portion 31, the outer covering portion 32, and the connecting portion 33 facing the bottom plate portion 11. The retaining portion 30 is also fixed to the side and bottom surfaces of the portions of the ignition portion 41 of the igniter 40 near the lower end, and to the surface of the portions of the terminal pin 42 of the igniter 40 near the upper end.

[0042] As a result, the opening 15 is completely filled with the terminal pin 42 and the holding portion 30, and the sealing performance of this portion is ensured, thereby ensuring airtightness of the space inside the housing. Since the opening 15 is formed in an asymmetrical shape in a plan view as described above, by filling the opening 15 with the connecting portion 33, the opening 15 and the connecting portion 33 also function as a rotation prevention mechanism that prevents the holding portion 30 from rotating with respect to the bottom plate portion 11.

[0043] A female connector portion 34 is formed on a portion of the outer covering portion 32 of the holding portion 30 facing the outside. This female connector portion 34 is a portion for receiving a male connector (not shown) of a harness for connecting the igniter 40 to a control unit (not shown), and is located within a recess portion 14 provided in the bottom plate portion 11 of the lower shell 10.

[0044] A portion of the terminal pin 42 of the igniter 40 near the lower end is exposed and disposed within the female connector portion 34. A male connector is inserted into the female connector portion 34, thereby achieving electrical continuity between the core wire of the harness and the terminal pin 42.

[0045] The above-mentioned injection molding may also be performed using the lower shell 10 in which an adhesive layer is provided in advance at a predetermined position on the surface of the bottom plate portion 11 in the portion that will be covered by the holding portion 30. The adhesive layer can be formed by applying an adhesive to a predetermined position on the bottom plate portion 11 in advance and curing the adhesive, for example.

[0046] In this way, the hardened adhesive layer is positioned between the bottom plate portion 11 and the holding portion 30, so that the holding portion 30 made of a resin molded portion can be more firmly fixed to the bottom plate portion 11. Therefore, if the adhesive layer is provided in a ring shape along the circumferential direction so as to surround the opening 15 provided in the bottom plate portion 11, it is possible to ensure higher sealing performance in that portion.

[0047] Here, as the adhesive to be applied in advance to the bottom plate portion 11, an adhesive containing as a raw material a resin material that has excellent heat resistance, durability, corrosion resistance, etc. after hardening is preferably used, and for example, an adhesive containing as a raw material a cyanoacrylate-based resin or a silicone-based resin is particularly preferably used. In addition to the above-mentioned resin materials, phenol-based resins, epoxy-based resins, melamine-based resins, urea-based resins, polyester-based resins, alkyd-based resins, polyurethane-based resins, polyimide-based resins, polyethylene-based resins, polypropylene-based resins, polyvinyl chloride-based resins, polystyrene-based resins, polyvinyl acetate-based resins, polytetrafluoroethylene-based resins, acrylonitrile butadiene styrene-based resins, acrylonitrile styrene-based resins, acrylic resins, polyamide-based resins, polyacetal-based resins, polycarbonate-based resins, polyphenylene ether-based resins, polybutylene terephthalate-based resins, polyethylene terephthalate-based resins, polyolefin-based resins, polyphenylene sulfide-based resins, polysulfone-based resins, polyethersulfone-based resins, polyarylate-based resins, polyether ether ketone-based resins, polyamide imide-based resins, liquid crystal polymers, styrene-based rubbers, olefin-based rubbers, and the like can be used as the above-mentioned adhesives.

[0048] Note that, although an example configuration has been given here in which the igniter 40 can be fixed to the lower shell 10 by injection molding the retaining portion 30 made of a resin molded portion, it is also possible to use other alternative means for fixing the igniter 40 to the lower shell 10.

[0049] A cup-shaped member 50 is attached to the bottom plate portion 11 so as to cover the protruding tube portion 13, the holding portion 30 and the igniter 40. The cup-shaped member 50 has a generally cylindrical shape with a bottom that is open at the end on the bottom plate portion 11 side, and includes a space therein for accommodating an enhancer charge 59. The cup-shaped member 50 is disposed so as to protrude into the combustion chamber 60 in which the gas generating agent 61 is accommodated, so that the space provided therein faces the ignition portion 41 of the igniter 40.

[0050] The cup-shaped member 50 has a top wall portion 51, a cylindrical side wall portion 52 extending from the periphery of the top wall portion 51 toward the bottom plate portion 11, and a flange portion 62 extending radially outward from the opening end, which is the end portion of the side wall portion 52 on the bottom plate portion 11 side.

[0051] Side wall 52 includes thin portion 52a provided on the top wall 51 side, and thick portion 52b extending from thin portion 52a along the axial direction to the opposite side to top wall 51. Thin portion 52a is thicker than fragile portion 55 and thinner than thick portion 52b, and has the mechanical strength to rupture (break), deform, or melt in accordance with rupture (break), deformation, or melting of fragile portion 55.

[0052] The flange portion 62 has a shape that is bent radially outward in parallel with the annular portion of the protruding cylindrical portion 13. Therefore, a part of the cup-shaped member 50 is not sandwiched between the lower support member 70 and the bottom plate portion 11 of the lower shell 10.

[0053] The cup-shaped member 50 has no openings in either the side wall portion 52 or the top wall portion 51, and surrounds a space provided therein. When the igniter 40 is activated and the transfer charge 59 inside the transfer chamber is ignited, the cup-shaped member 50 bursts, deforms, or melts due to a pressure increase in the internal space and the conduction of the generated heat.

[0054] The cup-shaped member 50 is preferably made of a metal member such as stainless steel, steel, aluminum, aluminum alloy, stainless steel, stainless steel alloy, or a resin member such as a thermosetting resin represented by epoxy resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyamide resin (e.g., nylon 6, nylon 66, etc.), polypropylene sulfide resin, polypropylene oxide resin, etc. In particular, an aluminum alloy or an iron-based metal material such as stainless steel or steel, which has a relatively higher mechanical strength than aluminum, is preferable.

[0055] The method for fixing the cup-shaped member 50 is not limited to the above-mentioned fixing method using the lower support member 70, and other fixing methods may be used.

[0056] At least a part of the top wall 51 of the cup-shaped member 50 is provided with a weak portion 55 which is thinner than the side wall 52. The weak portion 55 is provided by a radially extending slit, and is configured to have lower mechanical strength than the side wall 52 of the cup-shaped member 50. Here, the weak portion 55 is disposed so as to face the ignition portion 41 of the igniter 40. In addition, the part of the top wall 51 other than the weak portion 55 which extends radially is provided with a non-weak portion 56 which is thicker than the weak portion 55 and has a thickness approximately equal to that of the thick portion 52b.

[0057] As a result, in the space inside the cup-shaped member 50, the weak portion 55 ruptures (breaks), deforms, or melts due to the thrust generated by the combustion of the transfer charge 59, and then the thin-walled portion 52a ruptures (breaks), deforms, or melts in accordance with the rupture (breaks), deformation, or melting of the weak portion 55, and the mechanical strength of the weak portion 55 and the thin-walled portion 52a is relatively low. On the other hand, the non-weak portion 56 and the thick portion 52b are formed to be thicker than the weak portion 55, and are configured to remain even after the transfer charge 59 burns when the igniter 40 is activated.

[0058] The thicknesses of the fragile portion 55 and the thin portion 52a and the non-fragile portion 56 and the thick portion 52b are appropriately adjusted based on the type and amount of the transfer charge 59 used, and an example is shown below. For example, the thicknesses of the fragile portion 55 and the thin portion 52a are set to 0.6 mm or less, preferably 0.3 mm or less, when the cup-shaped member 50 is made of iron, stainless steel, or aluminum alloy. On the other hand, the thicknesses of the non-fragile portion 56 and the thick portion 52b are set to 0.3 mm or more and 0.9 mm or less, preferably 0.4 mm or more and 0.6 mm or less, provided that they are greater than the thicknesses of the fragile portion 55 and the thin portion 52a, when the cup-shaped member 50 is made of iron, stainless steel, or aluminum alloy.

[0059] The transfer charge 59 filled in the transfer chamber is ignited by the flame generated by the operation of the igniter 40, and generates heat particles by burning. The transfer charge 59 must be capable of reliably starting the combustion of the gas generating agent 61, and generally, a composition made of a metal powder / oxidizer such as B / KNO3, B / NaNO3, Sr(NO3)2, etc., a composition made of titanium hydride / potassium perchlorate, a composition made of B / 5-aminotetrazole / potassium nitrate / molybdenum trioxide, etc., is used.

[0060] The enhancer charge 59 may be in a powder form, a form formed into a predetermined shape by a binder, etc. The shape of the enhancer charge 59 formed by a binder may be, for example, granular, cylindrical, sheet, spherical, single-hole cylinder, multi-hole cylinder, tablet, or the like.

[0061] In the space inside the housing, the space surrounding the portion in which the cup-shaped member 50 is disposed is located a combustion chamber 60 in which a gas generating agent 61 is accommodated. Specifically, as described above, the cup-shaped member 50 is disposed so as to protrude into the combustion chamber 60 formed inside the housing, and the space provided in the portion facing the outer surface of the top wall portion 51 of the cup-shaped member 50 and the space provided in the portion facing the outer surface of the side wall portion 52 form the combustion chamber 60. As a result, the gas generating agent 61 is disposed adjacent to the outer surface of the cup-shaped member 50.

[0062] Further, a filter 90 is disposed along the inner circumference of the housing in the space radially surrounding the combustion chamber 60 in which the gas generating agent 61 is accommodated. The filter 90 has a cylindrical shape and is disposed so that its central axis substantially coincides with the axial direction of the housing.

[0063] The gas generating agent 61 is an agent that generates gas by being ignited by thermal particles generated by the operation of the igniter 40 and burning. As the gas generating agent 61, it is preferable to use a non-azide gas generating agent, and the gas generating agent 61 is generally formed as a molded body containing a fuel, an oxidizer, and an additive.

[0064] The fuel may be, for example, a triazole derivative, a tetrazole derivative, a guanidine derivative, an azodicarbonamide derivative, a hydrazine derivative, or a combination of these. Specifically, for example, nitroguanidine, guanidine nitrate, cyanoguanidine, 5-aminotetrazole, or the like is preferably used.

[0065] Examples of the oxidizing agent include basic metal hydroxides such as basic copper nitrate and basic copper carbonate, perchlorates such as ammonium perchlorate and potassium perchlorate, and nitrates containing a cation selected from alkali metals, alkaline earth metals, transition metals, and ammonia. Examples of the nitrates that are preferably used include sodium nitrate and potassium nitrate.

[0066] Examples of additives include binders, slag formers, and combustion control agents. Examples of binders that can be suitably used include organic binders such as polyvinyl alcohol, metal salts of carboxymethylcellulose, and stearates, and inorganic binders such as synthetic hydrotalcite and acid clay. Examples of binders that can be suitably used include polysaccharide derivatives such as hydroxyethyl cellulose, hydroxypropyl methyl cellulose, cellulose acetate, cellulose propionate, cellulose acetate butyrate, nitrocellulose, microcrystalline cellulose, guar gum, polyvinylpyrrolidone, polyacrylamide, and starch, and inorganic binders such as molybdenum disulfide, talc, bentonite, diatomaceous earth, kaolin, and alumina. Examples of slag formers that can be suitably used include silicon nitride, silica, and acid clay. Examples of combustion control agents that can be suitably used include metal oxides, ferrosilicon, activated carbon, and graphite.

[0067] The shape of the molded body of the gas generating agent 61 may be various, such as granular, pellet-like, cylindrical, or other granular shapes, or disk-like shapes. In addition, for cylindrical molded bodies, perforated molded bodies having through holes inside the molded body (for example, a single-hole cylindrical shape or a multi-hole cylindrical shape) are also used. These shapes are preferably selected appropriately according to the specifications of the airbag device in which the disk-type gas generator 100 is incorporated, and it is preferable to select an optimal shape according to the specifications, such as a shape in which the gas generation rate changes over time when the gas generating agent 61 is burned. In addition to the shape of the gas generating agent 61, it is preferable to appropriately select the size and filling amount of the molded body taking into consideration the linear burning rate and pressure exponent of the gas generating agent 61, etc.

[0068] The filter 90 can be made of, for example, metal wire such as stainless steel or steel wound and sintered, or a mesh material woven with metal wires and pressed into a compact shape. Specific examples of the mesh material that can be used include knitted wire mesh, plain woven wire mesh, and an assembly of crimped metal wires.

[0069] Also, a perforated metal plate wound around the filter 90 can be used. In this case, the perforated metal plate can be, for example, an expanded metal plate in which staggered cuts are made in a metal plate and the cuts are expanded to form holes and processed into a mesh-like shape, or a hook metal plate in which holes are made in a metal plate and burrs formed around the holes are crushed and flattened. In this case, the size and shape of the holes can be appropriately changed as necessary, and holes of different sizes and shapes can be included in the same metal plate. In addition, as the metal plate, for example, a steel plate (mild steel) or a stainless steel plate can be suitably used, and a non-ferrous metal plate such as aluminum, copper, titanium, nickel, or an alloy thereof can also be used.

[0070] The filter 90 functions as a cooling means for cooling the gas generated in the combustion chamber 60 by removing the high temperature heat of the gas when the gas passes through the filter 90, and also functions as a removal means for removing residues (slag) and the like contained in the gas. Therefore, in order to sufficiently cool the gas and prevent the residues from being released to the outside, it is necessary to ensure that the gas generated in the combustion chamber 60 passes through the filter 90. The filter 90 is disposed away from the peripheral wall portions 12, 22 so that a gap 28 of a predetermined size is formed between the peripheral wall portion 12 of the lower shell 10 and the peripheral wall portion 22 of the upper shell 20 that constitute the peripheral wall portion of the housing.

[0071] A plurality of gas outlets 23 are provided in the peripheral wall 22 of the upper shell 20 in a portion facing the filter 90. The plurality of gas outlets 23 are for directing the gas that has passed through the filter 90 to the outside of the housing.

[0072] Moreover, a metal sealing tape 24 is attached as a sealing member to the inner peripheral surface of the peripheral wall portion 22 of the upper shell 20 so as to close the plurality of gas ejection ports 23. As this sealing tape 24, an aluminum foil with an adhesive material applied to one side can be suitably used, and the sealing tape 24 ensures the airtightness of the combustion chamber 60.

[0073] A lower support member 70 is disposed in the vicinity of the end portion of the combustion chamber 60 located on the bottom plate portion 11 side. The lower support member 70 has an annular shape, and is disposed substantially between the filter 90 and the bottom plate portion 11 so as to cover the boundary portion between the filter 90 and the bottom plate portion 11. As a result, the lower support member 70 is positioned between the bottom plate portion 11 and the gas generating agent 61 in the vicinity of the end portion of the combustion chamber 60.

[0074] The lower support member 70 has an annular base portion 71 that is fitted to the bottom plate portion 11 so as to fit along the inner bottom surface of the bottom plate portion 11, an abutting portion 72 that abuts against the inner peripheral surface of the filter 90 closer to the bottom plate portion 11, and a cylindrical erected portion 73 that erects from the base portion 71 toward the top plate portion 21. The abutting portion 72 extends from the outer edge of the base portion 71, and the erected portion 73 extends from the inner edge of the base portion 71. The erected portion 73 covers the outer peripheral surface of the protruding cylindrical portion 13 of the lower shell 10 and the outer peripheral surface of the inner covering portion 31 of the holding portion 30.

[0075] The lower support member 70 is a member for fixing the filter 90 to the housing, and also functions as an outflow prevention means for preventing gas generated in the combustion chamber 60 from outflowing from the gap between the lower end of the filter 90 and the bottom plate portion 11 during operation without passing through the inside of the filter 90. For this reason, the lower support member 70 is formed, for example, by pressing a metal plate-like member, and is preferably composed of a member made of a steel plate such as ordinary steel or special steel (for example, a cold-rolled steel plate or a stainless steel plate).

[0076] An upper support member 80 is disposed at the end of the combustion chamber 60 located on the top plate portion 21 side. The upper support member 80 has a substantially disk-like shape, and is disposed between the filter 90 and the top plate portion 21 so as to cover the boundary between the filter 90 and the top plate portion 21. As a result, the upper support member 80 is positioned between the top plate portion 21 and the gas generating agent 61 in the vicinity of the end of the combustion chamber 60.

[0077] The upper support member 80 has a base portion 81 that abuts against the top plate portion 21, and an abutment portion 82 that stands upright from the periphery of the base portion 81. The abutment portion 82 abuts against the inner peripheral surface of the axial end portion of the filter 90 that is located on the top plate portion 21 side.

[0078] The upper support member 80 is a member for fixing the filter 90 to the housing, and also functions as an outflow prevention means for preventing gas generated in the combustion chamber 60 from outflowing from the gap between the upper end of the filter 90 and the top plate portion 21 during operation without passing through the inside of the filter 90. For this reason, the upper support member 80 is formed, for example, by pressing a metal plate-like member, and is preferably composed of a member made of a steel plate such as ordinary steel or special steel (for example, a cold-rolled steel plate or a stainless steel plate).

[0079] A disk-shaped cushion material 85 is disposed inside the upper support member 80 so as to come into contact with the gas generating agent 61 contained in the combustion chamber 60. As a result, the cushion material 85 is positioned between the top plate portion 21 and the gas generating agent 61 in the portion of the combustion chamber 60 on the top plate portion 21 side, and presses the gas generating agent 61 toward the bottom plate portion 11 side.

[0080] The cushioning material 85 is provided for the purpose of preventing the gas generating agent 61, which is made of a molded body, from being crushed by vibration or the like, and is preferably made of a material such as a ceramic fiber molded body, rock wool, foamed resin (e.g., foamed silicone, foamed polypropylene, foamed polyethylene, foamed urethane, etc.), or rubber such as chloroprene and EPDM.

[0081] Next, with reference to FIG. 1, a procedure for assembling disk-shaped gas generator 100 in the present embodiment will be described.

[0082] First, the igniter 40 is fixed to the lower shell 10 by injection molding as the holding portion 30 made of a resin molded portion. Then, the side wall portion 52 of the cup-shaped member 50, inside which the transfer charge 59 is accommodated, is press-fitted into the holding portion 30 of the lower shell 10 to be fixed thereto.

[0083] Then, gas generating agent 61 is filled inside filter 90, and upper support member 80 with cushioning material 85 interposed therebetween is inserted into the upper end portion of filter 90. Thereafter, upper shell 20, whose gas outlet 23 is closed with sealing tape 24, is placed over lower shell 10, and lower shell 10 and upper shell 20 are welded together. This completes the assembly of gas generator 100 having the structure shown in FIG.

[0084] Here, in disk-shaped gas generator 100 in the present embodiment, since no opening is provided in cup-shaped member 50, the step of filling transfer charge 59 in transfer charge chamber 57 provided inside cup-shaped member 50 can be carried out very easily. This is because cup-shaped member 50 itself is configured of a fragile member with low mechanical strength so that a part of the cup-shaped member will burst, deform or melt when disk-shaped gas generator 100 is activated. In other words, the work of closing the opening provided in the cup-shaped member to fill transfer charge 59, for example, by using aluminum tape or a closing plate, which was necessary when a cup-shaped member having an opening was used, becomes unnecessary, and the manufacturing process can be significantly simplified.

[0085] Fig. 3 is a schematic cross-sectional view for illustrating the operation of the disk-type gas generator in the present embodiment. Next, the operation of disk-type gas generator 100 in the present embodiment will be described with reference to Fig. 3 and the above-mentioned Fig. 1.

[0086] 1, when a vehicle equipped with disk-type gas generator 100 collides, the collision is detected by collision detection means separately provided in the vehicle, and based on this, igniter 40 is activated by current from a control unit separately provided in the vehicle. Transfer charge 59 accommodated in transfer chamber 57 is ignited by a flame generated by the activation of igniter 40 and begins combustion.

[0087] At that time, as shown in FIG. 3, immediately after the igniter 40 is activated, the ignition charge loaded in the ignition section 41 rapidly burns, causing the squib cup of the ignition section 41 to burst, and the thrust generated by the rapid combustion of the ignition charge is transmitted to the transfer charge 59 filled in the transfer chamber 57.

[0088] As shown in FIG. 3, when the thrust reaches the top wall 51 of the cup-shaped member 50, the fragile part 55 of the cup-shaped member 50, which is made of a fragile material, is ruptured, deformed, or melted. The rupture, deformation, or melting of the fragile part 55 of the cup-shaped member 50 occurs later than the ignition of the transfer charge 59 by the heat particles generated by the combustion of the ignition charge. Since the fragile part 55 does not exist in the side wall 52 but exists in the top wall 51, the fragile part 55 of the top wall 51 ruptures, deforms, or melts, and the internal pressure rises until the top wall 51 ruptures, deforms, or melts. Here, the transfer charge 59 of the cup-shaped member 50 is scattered and dispersed inside the cup-shaped member 50 by the thrust generated by the combustion of the ignition charge. 2, the fragile portion 55 is provided as a slit, and ruptures, deforms or melts first from the top wall portion 51 of the cup-shaped member 50, and then tears open toward the thin-walled portion 52a of the side wall portion 52. The thin-walled portion 52a ruptures (breaks), deforms or melts in accordance with the rupture (breaks), deformation or melting of the fragile portion 55, and tears open up to the connection portion with the thick-walled portion 52b. Here, the thick-walled portion 52b does not rupture (breaks), deform or melt.

[0089] As a result, the transfer charge 59 located farther from the igniter 40 is also ignited by the thermal particles in a shorter period of time and begins to burn, resulting in a significant increase in pressure and temperature in the space inside the cup-shaped member 50. As a result, the fragile portion 55 and the thin-walled portion 52a of the cup-shaped member 50 will burst, deform or melt in turn in a shorter period of time, and a large amount of heat particles generated by the combustion of the transfer charge 59 will flow into the combustion chamber 60 earlier.

[0090] In particular, in FIG. 1, the cup-shaped member 50 is made of iron or stainless steel, which has a higher strength than aluminum, and therefore does not burst, deform, or melt in the initial stage of combustion of the enhancer charge 59. At this time, the internal pressure of the cup-shaped member 50 rises until a predetermined time has elapsed at which the fragile portion 55 of the cup-shaped member bursts, deforms, or melts. Then, after the internal pressure reaches a certain level, the fragile portion 55 and the thin portion 52a of the cup-shaped member 50 burst, deform, or melt in sequence. Therefore, by using an iron-based metal material with high mechanical strength such as iron or stainless steel for the cup-shaped member 50 to increase the mechanical strength, the combustion of the enhancer charge 59 can be sufficiently promoted when the cup-shaped member 50 is split, and the cup-shaped member 50 can be split in a state in which the combustion of the gas generating agent 61 is promoted. Such an improvement in the mechanical strength of the cup-shaped member 50 can be achieved by increasing the thickness, even when a metal with low strength such as aluminum is used. In this case, the thickness is preferably 0.4 mm or more and 1.5 mm or less, and more preferably 0.6 mm or more and 1.2 mm or less.

[0091] In this way, a large amount of thermal particles flow into the combustion chamber 60, whereby the gas generating agent 61 contained in the combustion chamber 60 is ignited and combusted, generating a large amount of gas. The gas generated in the combustion chamber 60 passes through the inside of the filter 90, during which time the heat is removed by the filter 90 and the gas is cooled, and the slag contained in the gas is removed by the filter 90 and flows into the gap 28.

[0092] Hereinafter, with reference to FIG. 1, a mechanism by which the transmission of flame energy by transfer charge 59 can be suitably controlled in the case of disk-shaped gas generator 100 in the embodiment of the present invention will be described.

[0093] 2, in disk-type gas generator 100 of the embodiment of the present invention, top wall portion 51 of cup-shaped member 50 has a radially thinner thickness at top wall portion 51 than other portions to form weak portion 55, and the remaining portion of top wall portion 51 of cup-shaped member 50 has a thicker thickness than weak portion 55 to form non-weak portion 56. Thin portion 52a of side wall portion 52 of cup-shaped member 50 is configured to be thicker than weak portion 55 and thinner than thick portion 52b, and thick portion 52b of side wall portion 52 of cup-shaped member 50 is configured to be thicker than weak portion 55 and thin portion 52a, and to be approximately the same thickness as non-weak portion 56.

[0094] With this configuration, the fragile portion 55 ruptures, deforms, or melts first. Here, since the cup-shaped member 50 ruptures, deforms, or melts from the portion that is the starting point, there is no risk of rupture, deformation, or melting from the side wall portion 52 where the fragile portion 55 does not exist, and the top wall portion 51 ruptures, deforms, or melts after the transfer charge 59 has sufficiently burned. Then, starting from the fragile portion 55 that has ruptured, deformed, or melted, the top wall portion 51 ruptures along the fragile portion 55. After the top wall portion 51 ruptures, the rupture reaches the thin portion 52a of the side wall portion 52, and ruptures the thin portion 52a of the side wall portion 52 as it is. Then, the rupture stops at the connection portion between the thin portion 52a and the thick portion 52b. Thus, the fragile portion 55 ruptures in the longitudinal direction, so that the fragile portion 55 ruptures in a petal shape up to the connection portion between the thin portion 52a and the thick portion 52b. Therefore, since the cup-shaped member 50 breaks open only halfway (at the connection between the thin-walled portion 52a and the thick-walled portion 52b) and then stops, it expands over time toward the top plate portion 21, and the size of the break in the cup-shaped member 50 is opened in a stable state, so that the heat particles generated by the combustion of the transfer charge 59 flow more directionally toward the top plate portion 21.

[0095] Specifically, in the first stage of cleavage in which the weak portion 55 ruptures, deforms or melts and the non-weak portion of the top wall portion 51 cleaves starting from the weak portion 55, the top wall portion 51 of the cup-shaped member 50 ruptures, deforms or melts while the side wall portion 52 remains, so that the heat particles generated by the combustion of the transfer charge 59 flow toward the top plate portion 21, and the flame flowing into the combustion chamber 60 is constricted between the cup-shaped member 50 and the top plate portion 21. As a result, all of the gas generating agents 61 adjacent to the cup-shaped member 50 are not ignited at the same time, and the flame spread of the gas generating agents 61 progresses mainly between the transfer chamber 57 and the top plate portion 21.

[0096] When the rupture, deformation or melting of the top wall 51 of the cup-shaped member 50 progresses, the thin wall portion 52a is then torn open as the second stage. Here, the side wall portion 52 is torn open along the longitudinal direction in which the weak portions 55 radially provided on the top wall 51 were provided, and the thin wall portion 52a is torn open downward in the axial direction of the side wall portion 52, but after it is torn halfway (to the connection portion between the thin wall portion 52a and the thick wall portion 52b), the torn open stops. Therefore, heat particles generated by the combustion of the transfer charge 59 flow into the combustion chamber 60 from the torn portion. As a result, the fire spreads to the gas generating agent 61 between the thin wall portion 52a and the filter 90, and then the fire spreads to the gas generating agent 61 between the thick wall portion 52b and the filter 90.

[0097] Therefore, by providing the cup-shaped member 50 with a weak portion 55, a non-weak portion 56, a thin portion 52a, and a thick portion 52b, and appropriately adjusting the positions and sizes of the weak portion 55, the non-weak portion 56, the thin portion 52a, and the thick portion 52b, it is possible to prevent the gas generating agent 61 from burning rapidly and intentionally slow down the progress of the burning, and it becomes very easy to optimize the adjustment of the gas output according to specifications, such as maintaining the gas output for a predetermined period of time.

[0098] Furthermore, if the entire side wall portion 52 of the cup-shaped member 50 is made thin-walled, there is a risk that the filter 90 will be subjected to the impact when the cup-shaped member 50 bursts, deforms or melts due to the combustion of the transfer charge 59, and the filter 90 will be damaged. However, by making a portion (thick portion 52b) of the side wall portion 52 of the cup-shaped member 50 thick and providing a fragile portion 55 in the top wall portion 51 as in the disk-type gas generator 100 in an embodiment of the present invention, heat particles will be directed toward the top plate portion 21 in the early stages of the bursting, deformation or melting of the cup-shaped member 50, so that the impact applied to the filter 90 is mitigated and damage to the filter 90 is prevented.

[0099] Furthermore, by adopting the above-mentioned configuration, top wall portion 51 instantly bursts, deforms or melts upon ignition, and the combustion of gas generating agent 61 between top wall portion 51 and top plate portion 21 proceeds immediately, so there is no delay in gas output, the internal pressure inside the gas generator increases quickly, and further, variations in output characteristics can be prevented in advance.

[0100] As the pressure in the space inside the housing increases due to the combustion of gas generating agent 61, sealing tape 24 closing gas outlet 23 provided in upper shell 20 breaks, and gas is ejected to the outside of the housing through gas outlet 23. The ejected gas is introduced into an airbag provided adjacent to disk-type gas generator 100, and inflates and deploys the airbag.

[0101] Here, whether the weak portion 55 and thin portion 52a of the cup-shaped member 50 will burst, deform or melt in sequence due to the propagation of the thrust generated by the activation of the igniter 40 depends on the mechanical strength (thickness, material, shape, etc.) of the cup-shaped member, the output of the igniter 40, the distance between the ignition portion 41, the cup-shaped member and the weak portion 55, the density of the transfer charge 59 filled in the transfer chamber, etc.

[0102] In this way, in order to sequentially rupture, deform or melt the weak portion 55 and thin portion 52a of the cup-shaped member 50 by utilizing the increase in pressure and temperature in the transfer chamber due to the combustion of the transfer charge 59, various adjustments can be made to the mechanical strength (thickness, material, shape, etc.) of the cup-shaped member 50 described above, the output of the igniter 40, the distance between the ignition portion 41 and the weak portion 55 of the cup-shaped member 50, the density of the transfer charge 59 filled in the transfer chamber, etc., but this can be achieved relatively easily by constructing the cup-shaped member 50 from an iron-based metallic material such as iron or stainless steel, as described above.

[0103] In either case, it is preferable that the fragile portion 55 of the cup-shaped member 50 has a lower mechanical strength than the side wall portion 52 of the cup-shaped member 50. Methods for making the fragile portion 55 of the cup-shaped member 50 weaker than the side wall portion 52 of the cup-shaped member 50 include adjusting their thickness, using different materials for them, and devising their shapes.

[0104] With this configuration, it is relatively easy to cause the fragile portion 55 to rupture, deform or melt before the thin-walled portion 52a of the cup-shaped member 50 ruptures, deforms or melts. However, when the fragile portion 55 can be caused to rupture, deform or melt before the thin-walled portion 52a of the cup-shaped member 50 ruptures, deforms or melts, the fragile portion 55 and the thin-walled portion 52a of the side wall portion 52 of the cup-shaped member 50 may have approximately the same mechanical strength.

[0105] As described above, according to the above-described embodiment of the present invention, it is possible to provide disc-type gas generator 100 that is controllable so that the magnitude of rupture (breakage) in cup-shaped member 50 is stable while increasing the mechanical strength of cup-shaped member 50. Furthermore, since the magnitude of rupture of cup-shaped member 50 is stabilized (the breakage area becomes uniform), it is possible to provide disc-type gas generator 100 that can exhibit predetermined performance while reducing the amount of transfer charge 59.

[0106] Furthermore, since the promotion of combustion of the transfer charge 59 makes it possible to start the combustion of the gas generating agent 61 earlier, it is possible to shorten the time from when the igniter is activated until when the gas starts to be ejected to the outside through the gas outlet 23, as compared to the conventional case. Furthermore, by adding the weak portion 55 and the thin portion 52a of the cup-shaped member 50, it is possible to make the fracture area uniform, and although the amount of part processing increases, the amount of charge of the transfer charge 59 can be significantly reduced, and it is possible to shorten the time from when the igniter is activated until when the gas starts to be ejected to the outside through the gas outlet 23 at low cost.

[0107] Furthermore, by reducing the amount of transfer charge 59 filled, the volume of cup-shaped member 50 can be made smaller than before, so that the volume of disk-type gas generator 100 can be optimized to reduce its weight.

[0108] In addition, since the gas temperature is lowered by reducing the amount of transfer charge 59, the cooling capacity of the filter 90 may be reduced accordingly. As a result, the weight of the filter 90 can be reduced.

[0109] (Verification test) Next, a disk-type gas generator having the same configuration as the disk-type gas generator 100 was created, and a verification test was performed to see what kind of changes would occur in a 60L tank test by changing the shape and dimensions of the cup-shaped member. The 60L tank test here is a test in which a disk-type gas generator (specifically, see Examples 1 to 3 below) having a cup-shaped member is individually placed in a sealed tank of 60L volume after being temperature-controlled in an environment of -40°C ± 2°C for 4 hours or more, and then operated to measure the increase in tank internal pressure over time. In this verification test, the gas pressure was measured over time from the time the igniter was activated until 100 ms. In addition, the number of moles of gas generated by the gas generating agent of each disk-type gas generator was 2 mol, and the amount of transfer charge filled in the cup-shaped member was 1.2 g. In addition, the material of each cup-shaped member in this verification test was an aluminum alloy.

[0110] Example 1 The above verification test was performed twice for each of a disk-type gas generator (hereinafter, the conventional gas generator) equipped with a conventional cup-shaped member (specification name: no step) with a constant thickness (thickness 1 mm) and a disk-type gas generator (hereinafter, the gas generator of the present invention) having the same configuration as disk-type gas generator 100 equipped with a cup-shaped member (specification name: with step) with a thin-walled part having a thickness of 0.5 mm, an axial length of the thin-walled part of 5 mm, a thickness of 1 mm, and an axial length of the thick-walled part of 15 mm. The fragile part in each cup-shaped member is the same as fragile part 55 in the above embodiment, with a slit depth of 0.6 mm (residual thickness 0.4 mm) and a width of 3 mm. The axial length of the cup-shaped member in each gas generator was the same. Other conditions were the same for the conventional gas generator and the gas generator of the present invention.

[0111] Figure 4 shows the results of a verification test on a conventional gas generator and the gas generator of the present invention. Note that t1 is the time until gas output is detected, and Pmax is the maximum pressure inside the tank.

[0112] In the gas generator of the present invention, as shown in (1) and (2) in Fig. 4, in both of the two verification tests, not only was a high gas output obtained at a relatively early stage from the time the igniter was activated, but it was also found to undergo a similar pressure change. In other words, it was found that the cup-shaped member can stably exhibit preferable gas output performance in the gas generator of the present invention.

[0113] In contrast, in the conventional gas generator, in the verification test for the case shown in Fig. 4(3), gas output performance similar to that of the gas generator of the present invention was exhibited, but in the verification test for the case shown in Fig. 4(4), the time until gas output was detected was delayed compared to the verification tests for Fig. 4(1) to (3), and the gas output process as shown in Fig. 4(1) to (3) could not be followed. In other words, it was found that with the configuration of the conventional gas generator, there are cases in which the gas output process varies from one gas generator to another.

[0114] Therefore, it was found that the gas generator of the present invention can stably exhibit favorable gas output performance compared to conventional gas generators.

[0115] Example 2 In a gas generator of the present invention similar to that of Example 1, a verification test was conducted to determine the gas output when a cup-shaped member (see FIG. 5(a)) having an axial height of 20 mm, a thin-walled portion thickness of 0.5 mm, a slit depth of 0.6 mm (remaining thickness 0.4 mm) and width of 3 mm at the weak portion, and a thickness of 1 mm at other portions was used, without changing the internal volume, and the axial length Pmm of the thin-walled portion was changed to (1) 5 mm, (2) 8 mm, or (3) 11 mm, respectively, and a 60 L tank test similar to that of Example 1 was conducted. The other conditions of each gas generator were the same. The results of this verification test are shown in FIG. 5(b).

[0116] In the gas generator of this embodiment, as shown in FIG. 5(b), it was found that even if the axial length P mm of the thin-walled portion of the cup-shaped member in FIG. 5(a) was changed to (1) 5 mm, (2) 8 mm, or (3) 11 mm, favorable gas output performance could be exhibited in each case, almost similar to Example 1.

[0117] Example 3 In a gas generator of the present invention similar to that of Example 1, a verification test was conducted to determine the gas output when a cup-shaped member (see FIG. 6(a)) having an axial height of 20 mm, an axial length of the thin-walled portion of 5 mm, a slit depth of 0.6 mm (remaining thickness 0.4 mm) and width of 3 mm in the weak portion, and a thickness of 1 mm in other portions was used, while keeping the internal volume unchanged, and changing the thickness Qmm of the thin-walled portion to (1) 0.4 mm, (2) 0.5 mm, (3) 0.6 mm, or (4) 0.7 mm, and conducting a 60 L tank test similar to that of Example 1. The other conditions of each gas generator were the same. The results of this verification test are shown in FIG. 6(b).

[0118] In the gas generator of this embodiment, as shown in FIG. 6(b), it was found that even if the thickness Qmm of the thin-walled portion of the cup-shaped member in FIG. 6(a) was changed to (1) 0.4 mm, (2) 0.5 mm, (3) 0.6 mm, or (4) 0.7 mm, favorable gas output performance could be exhibited almost similarly to Examples 1 and 2.

[0119] (Variations, etc.) In the following, modified examples of the embodiment of the present invention will be described, and unless otherwise specified, the same names will be used for parts having similar functions. Furthermore, in each modified example, parts similar to those in the above embodiment will be indicated by the same reference numerals with the last two digits, and descriptions thereof may be omitted, unless otherwise specified.

[0120] The cup-shaped member 50 in the embodiment of the present invention can be applied to a disk-type gas generator provided with two igniters called a dual inflator, for example, in the same manner as the disk-type gas generator 100 of the present embodiment, and can also be applied to other gas generators.

[0121] Furthermore, the fragile portion 55 of the cup-shaped member 50 is not limited to that shown in Fig. 2. For example, any number of slits may be included in the fragile portion 55 as long as the slits are arranged radially. For example, the fragile portion may have slits arranged in a cross or asterisk shape in plan view.

[0122] The uneven shape of the fragile portion 55 is not limited to the above-mentioned shape, and may be any shape. For example, a ring-shaped convex portion may be provided by making a part of the non-fragile portion 56 bulge toward the top wall portion 51, or the entire fragile portion 55 may be curved to form a concave portion. In addition, a plurality of convex portions or concave portions may be provided in the fragile portion 55 in a dotted or matrix pattern. Furthermore, the top wall portion 51 may be provided with the fragile portion 55 in a circular or annular shape.

[0123] The slits of the weakened portion 55 may be continuously extended onto the surface (outer wall) of the thin portion 52a of the side wall portion 52.

[0124] Depending on the purpose, the cup-shaped member 50 may be replaced with the cup-shaped member 150 shown in FIG. 7. The cup-shaped member 150 is different from the cup-shaped member 50 in that the cup-shaped member 50 has a slit (weakened portion) formed along the entire circumference, whereas the cup-shaped member 150 does not have a slit (weakened portion) formed along the entire circumference. A detailed description will be given below. Note that the same parts as those in the above embodiment are designated by reference numerals with the same last two digits, and description thereof may be omitted.

[0125] The weak parts 155 are arranged offset from one another by being provided at specific angles as viewed from the circumferential direction. Here, a region where weak parts are provided at an angle of less than half a circumference (angle of 180°) as viewed from above in the axial direction is called a weak part-existing region, and a region where no weak parts are provided at an angle of more than half a circumference (angle of 180°) as viewed from above in the axial direction is called a weak part-non-existing region. In Fig. 7, due to the presence of the weak part-existing region 151a and the weak part-non-existing region 151b, the rupture, deformation or melting of the cup-shaped member occurs in the weak part-existing region 151a before the weak part-non-existing region 151b, so that heat particles generated by the combustion of the transfer charge flow into the combustion chamber with directionality.

[0126] In this case, not only can the effects described in the above-mentioned embodiment be obtained, but also the weak portion 155 and the thin portion 152a can be more reliably ruptured, deformed, or melted when the igniter is activated, and the effect of reliably promoting the combustion of the transfer charge can be obtained. Furthermore, since the weak portion 155 unevenly distributed over half the circumference of the thin portion 152a ruptures, deforms, or melts, the combustion gas of the transfer charge can be made to flow in a direction toward the combustion chamber. The present invention can also be applied to the disk-type gas generator provided with two igniters, called the dual inflator described above.

[0127] In Fig. 7, the slits in the weak portion are provided radially from the center at three positions at an angle of 60°, but this is not limited to this. For example, the slits in the weak portion may be provided in a roughly V-shape with two slits provided at an angle of 60°, or the slits in the weak portion may be provided radially from the center at four or more positions at an angle of 30°.

[0128] In the above-described embodiment and its modified examples of the present invention, the upper shell and the lower shell are formed as press-formed products formed by pressing a metal member, but this is not necessarily limited to this, and it is also possible to use upper shells and lower shells formed by a combination of press processing and other processes (forging, drawing, cutting, etc.), or to use upper shells and lower shells formed only by the above-mentioned other processes.

[0129] Furthermore, in the above-described embodiment of the present invention and its modified examples, a case has been exemplified in which a protruding cylindrical portion is provided on the lower shell, but it is of course also possible to apply the present invention to a gas generator configured in such a way that the protruding cylindrical portion is not provided.

[0130] Furthermore, in the above-mentioned embodiment of the present invention and its modified examples, the cup-shaped member is one that bursts, deforms, or melts due to a pressure rise in the internal space and conduction of the generated heat when the transfer charge is ignited by the operation of the igniter, but cup-shaped members of other configurations may be used. Specifically, the cup-shaped member may be one in which an opening is provided in advance in a member having high mechanical strength such as a stainless steel alloy, and the opening is blocked with a sealing tape so that the blocking of the sealing tape is broken when the member is activated.

[0131] Moreover, examples of modified examples of the above embodiment include gas generators and cup-shaped members shown in Fig. 8 to Fig. 11. Hereinafter, the gas generators and cup-shaped members according to each modified example will be described, focusing on the points that differ from the above embodiment.

[0132] 8(a) differs from the above embodiment in that the upper end of the erected portion 273 of the lower support member 270 is press-fitted into the thick-walled portion 252b of the cup-shaped member 250, that an upper support member 280 with the base portion 281 facing the lower side is used, and that no cushioning material is used. Note that the side wall portion 282 of the upper support member 280 does not have to abut against the inner wall of the filter 290, or may abut against it.

[0133] Here, one step (before the upper shell 220 is press-fitted into the lower shell 210) of the manufacturing process of the gas generator in Fig. 8(a) is shown in Fig. 8(b). Note that before the upper shell 220 is press-fitted into the lower shell 210 (before the upper end of the standing portion 273 of the lower support member 270 is press-fitted into the thick-walled portion 252b of the cup-shaped member 250), the relationship is: outer diameter of the thin-walled portion 252a ≦ inner diameter of the upper end of the standing portion 273 of the lower support member 270 < outer diameter of the thick-walled portion 252b. Therefore, Fig. 8(b) shows a state in which the upper end of the standing portion 273 of the lower support member 270 is fitted into the thin-walled portion 252a of the cup-shaped member 250, but is stopped by the upper end of the thick-walled portion 252b and does not naturally move from the upper end of the thick-walled portion 252b to the lower side. This makes it possible to prevent the lower support member 270 from being installed at an angle or from moving radially during the manufacturing process, thereby facilitating the filling of the gas generator 200 with the gas generating agent 261.

[0134] 8(b), when the gas generator 200 is filled with the gas generating agent 261 and the upper shell 220 is press-fitted into the lower shell 210, the upper end of the erected portion 273 of the lower support member 270 is press-fitted and fixed into the thick portion 252b of the cup-shaped member 250 via the gas generating agent 261 pressed by the upper support member 280. As a result, the gas generating agent 261 is fixed within the space surrounded by the lower support member 270, the upper support member 280, and the filter 290. Furthermore, since the lower support member 270 is press-fitted and fixed into the thick portion 252b of the cup-shaped member 250, it does not move inside the gas generator 200 even if the gas generator 200 vibrates.

[0135] Therefore, according to this modification, not only can the same effects as those of the above embodiment be obtained, but also, compared to the above embodiment, it is not necessary to use a cushioning material, and the number of parts can be reduced. Also, since it is not necessary to fix the lower support member 270 in advance, and the above-mentioned press-fitting and fixing is performed when the upper shell 220 is press-fitted into the lower shell 210, it is possible to reduce costs by simplifying the manufacturing process.

[0136] Next, the gas generator shown in Fig. 9 will be described. Gas generator 300 differs from the above-described embodiment in that a cup-shaped member 350 is used instead of cup-shaped member 50 and lower support member 70. Here, a perspective view of cup-shaped member 350 is shown in Fig. 10(a).

[0137] The cup-shaped member 350 has the functions of both the cup-shaped member 50 and the lower support member 70 of the above embodiment, and is formed by integrally extending an erected portion 373, a base portion 371, and an abutment portion 372, which correspond to the lower support member 70 of the above embodiment, from a flange portion 362 of the cup-shaped member 350. The cup-shaped member 350 is fixed to the inner covering portion 331 and the gas generating agent 361 filled in the filter 390. As a result, as shown in FIG. 9(b), in the cup-shaped member 350, the fragile portion 355 and the thin portion 352a burst, deform, or melt in that order during operation, as in the above embodiment, and a large amount of heat particles generated by the combustion of the transfer charge 359 flows into the combustion chamber 360 early.

[0138] According to this modification, not only can the same effects as those of the above embodiment be obtained, but compared to the above embodiment, before operation, cup-shaped member 350 can be fixed together with inner covering portion 331 by gas generating agent 361, and after operation, movement of cup-shaped member 350 in the housing axial direction of gas generator 300 (up and down on the page in FIG. 9) can be more effectively prevented by abutment portion 372 together with inner covering portion 331. Furthermore, according to this modification, cup-shaped member 350 is such that cup-shaped member 50 and lower support member 70 of the above embodiment are integrated, so that the number of parts can be reduced compared to the above embodiment.

[0139] Next, the gas generator shown in Fig. 11 will be described. Gas generator 400 includes the cup-shaped member shown in Fig. 10(b), and differs from the above-described embodiment in that cup-shaped member 450 is used instead of cup-shaped member 50 and lower support member 70. Here, a perspective view of cup-shaped member 450 is shown in Fig. 10(b).

[0140] The cup-shaped member 450 has a top wall 451 instead of the top wall 351 of the cup-shaped member 350 of the above-mentioned modified example. The top wall 451 has a generally circular fragile portion 455 that is thinner than the surrounding area. The cup-shaped member 450 is fixed to the inner covering portion 431 and the gas generating agent 361 filled in the filter 490. As a result, as shown in FIG. 11(b), the fragile portion 455 (and the thin portion 452a depending on the type of transfer charge 459, the amount of transfer charge, and / or the thickness of the thin portion 452a) of the cup-shaped member 450 bursts, deforms, or melts during operation, and a large amount of heat particles generated by the combustion of the transfer charge 459 flows into the combustion chamber 460 early.

[0141] According to this modification, not only can the same effects as those of the above embodiment be obtained, but compared to the above embodiment, before operation, cup-shaped member 450 can be fixed together with inner covering portion 431 by gas generating agent 461, and after operation, movement of cup-shaped member 450 in the housing axial direction of gas generator 400 (up and down on the page in FIG. 11) can be more effectively prevented by abutting portion 372 together with inner covering portion 331. Also, according to this modification, cup-shaped member 450 is such that cup-shaped member 50 and lower support member 70 of the above embodiment are integrated, so that the number of parts can be reduced compared to the above embodiment.

[0142] Instead of the cup-shaped member 450 in the gas generator of FIG. 11, a cup-shaped member 550 (see FIG. 10(c)) in which the portion corresponding to the thin-wall portion 452a is not present in the side wall portion 552 may be used.

[0143] In addition, the characteristic configurations shown in the above-mentioned embodiment of the present invention and its modified examples can naturally be combined with each other within the scope permitted in light of the spirit of the present invention.

[0144] As such, the above-mentioned embodiment and its modified examples disclosed herein are illustrative in all respects and are not restrictive. The technical scope of the present invention is defined by the claims, and includes all modifications within the meaning and scope equivalent to the description of the claims. [Explanation of symbols]

[0145] 10, 210, 310, 410 Lower shell 11, 211, 311, 411 Bottom plate part 12, 212, 312, 412 Peripheral wall part 13, 213, 313, 413 Projected tube part 14, 214, 314, 414 recess 15, 215, 315, 415 opening 20, 220, 320, 420 Upper shell 21, 221, 321, 421 Top plate 22, 222, 322, 422 Peripheral wall part 23, 223, 323, 423 Gas outlet 24, 224, 324, 424 Sealing tape 28, 228, 328, 428 Gap 30, 230, 330, 430 Holding part 31, 231, 331, 431 Inner coating 32, 232, 332, 432 Outer covering part 33, 232, 332, 432 connection part 34, 234, 334, 434 Female connector part 40, 240, 340, 440 igniter 41, 241, 341, 441 Ignition section 42, 242, 342, 442 terminal pins 50, 150, 250, 350, 450, 550 Cup-shaped member 51, 151, 251, 351, 451, 551 Top wall 52, 152, 252, 282, 352, 452, 552 Side wall 52a, 152a, 252a, 352a, 452a Thin wall part 52b, 152b, 252b, 352b, 452b Thick wall part 55, 155, 255, 355, 455, 555 Weakened parts 56, 156, 256, 356 Non-weakened parts 57, 257, 357, 457 Fire transmission room 59, 259, 359, 459 Transfer Charge 60, 260, 360, 460 Combustion chamber 61, 261, 361, 461 Gas Generator 62, 162, 262, 362, 462, 562 Flange 70, 270 Lower support member 71, 81, 271, 371, 471, 281, 381, 481, 571 base 72, 82, 272, 372, 472, 382, ​​482, 572 Contact part 73, 273, 373, 473, 573 Standing section 80, 280, 380, 480 Upper support member 85, 385, 485 Cushioning material 90, 290, 390, 490 Filters 100, 200, 300, 400 Disc type gas generator 151a Area of ​​weakness 151b Area without weak parts

Claims

1. a short cylindrical housing having a combustion chamber therein and containing a gas generating agent, the housing being composed of a cylindrical peripheral wall portion provided with a gas outlet, a top plate portion closing one axial end of the peripheral wall portion, and a bottom plate portion closing the other axial end of the peripheral wall portion; and an igniter including an ignition portion attached to the bottom plate portion and containing an ignition charge that is ignited when actuated; A cup-shaped member including a transfer chamber containing a transfer charge therein and a bottomed cylindrical single member arranged to protrude toward the combustion chamber so that the internal space of the transfer chamber faces the ignition portion; Equipped with The cup-shaped member has a top wall portion that serves as a bottom surface, The top wall portion of the cup-shaped member has at least a thin-walled weak portion disposed in a part thereof, and the cup-shaped member has a side wall portion that divides the transfer chamber and the combustion chamber and has a mechanical strength higher than that of the weak portion, the side wall portion includes a thin portion provided on the top wall portion side, a thick portion extending from the thin portion along the axial direction to a side opposite the top wall portion, and a connection portion connecting the thin portion and the thick portion, the fragile portion is disposed opposite the ignition portion and has a mechanical strength that causes the cup-shaped member to rupture, deform, or melt prior to the side wall portion upon activation of the igniter, the thin-walled portion has a mechanical strength such that it ruptures, deforms, or melts when rupture, deformation, or melting in the fragile portion progresses to the thin-walled portion; the thick-walled portion has a mechanical strength such that it does not rupture, deform, or melt even if rupture, deformation, or melting in the fragile portion progresses to the thin-walled portion and the thin-walled portion ruptures, deforms, or melts; the connecting portion has a stepped shape formed on an outer side of the side wall portion by utilizing a difference in thickness between the thin portion and the thick portion, the fragile portion disposed on the top wall portion of the cup-shaped member is thinner than the side wall portion of the cup-shaped member, The top wall portion of the cup-shaped member is composed of a weak portion existing region where rupture, deformation or melting occurs initially starting from the weak portion due to the combustion of the transfer charge accompanying the activation of the igniter, and a weak portion non-existing region where rupture, deformation or melting occurs progressing from the rupture, deformation or melting of the weak portion existing region after a predetermined time has elapsed since the rupture, deformation or melting of the weak portion existing region. Gas generator.

2. 2. The gas generator according to claim 1, wherein the weakened portion has a slit shape provided radially from a center in the top wall portion.

3. 3. The gas generator according to claim 1, wherein the cup-shaped member is made of a metal or an alloy.

4. a filter provided around the inside of the housing in a circumferential direction; a support member having a base portion in the shape of an annular plate provided in a direction along the inner bottom surface of the bottom plate portion, a contact portion that contacts the inner peripheral surface of the end portion of the filter on the side of the bottom plate portion, and a cylindrical erected portion that is erected from the base portion toward the top plate portion; Further equipped with 4. The gas generator according to claim 1, wherein the support member is held by the cup-shaped member by press-fitting the standing portion into the thick-walled portion of the cup-shaped member.

5. The housing further includes a filter disposed around the circumference of the housing. the cup-shaped member further includes an annular base portion provided in a direction along an inner bottom surface of the bottom plate portion, an abutting portion abutting an inner peripheral surface of an end portion of the filter on the bottom plate portion side, and a cylindrical erecting portion erected from the base portion toward the top plate portion side, 4. The gas generator according to claim 1, wherein the standing portion is integrally extended from the side wall portion of the cup-shaped member.

Images