JP2014196093A - Gas generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas generator that can stably control an autoignition operation even in the case where the operation is induced or the other cases and that has more excellent safety.SOLUTION: A gas generator 1A includes a housing, a gas generating agent 61 and an igniter 40. The housing includes: a top plate part 21; a bottom plate part 11; peripheral wall parts 12, 22 having a gas jetting port 23; and a fixation part 25 fixed to an external component. The igniter 40 is attached to the bottom plate part 11. The gas jetting port 23 is installed in the peripheral wall part 22 located closer to the top plate part 21 side than to the position where the fixation part 25 is installed. A lower side shell 10A constituting the bottom plate part 11 of the housing comprises a press molded product molded by pressing a rolled metallic plate-shaped member, and includes a fragile part 11a having relatively thin thickness. The fragile part 11a is formed by installing a loop-shaped groove part 16 in the lower side shell 10A.

Description

  The present invention relates to a gas generator incorporated in an occupant protection device, and more particularly to a so-called disk-type gas generator incorporated in an airbag device installed in a steering wheel of an automobile.

  2. Description of the Related Art Conventionally, airbag devices, which are occupant protection devices, have been widely used from the viewpoint of protecting occupants such as automobiles. The airbag device is equipped for the purpose of protecting the occupant from the impact generated when the vehicle or the like collides. The airbag is inflated and deployed instantaneously when the vehicle or the like collides, so that the airbag becomes a cushion of the occupant. It is to catch the body.

  The gas generator is incorporated in this airbag device, and ignites the igniter by energization from the control unit in the event of a vehicle collision, etc. This is a device for inflating and deploying the airbag. Note that the airbag device is mounted on, for example, an automobile steering wheel or an instrument panel.

  There are various types of gas generators, and there is a so-called disk-type gas generator as a gas generator suitably used for a driver side airbag device equipped on a steering wheel or the like. The disk-type gas generator has a short cylindrical housing whose end in the axial direction is closed, has a gas outlet on the peripheral wall of the housing, and surrounds an igniter located inside the housing. The gas generating agent and the filter are respectively housed in the housing so as to further surround the gas generating agent.

  In the gas generator, it is important to stably burn the gas generating agent during operation of the igniter. Here, in order to stably burn the gas generating agent, it is necessary to burn the gas generating agent in a predetermined high-pressure environment. Therefore, in the gas generator, the size of the gas outlet provided in the housing is large. The design is made so that the pressure inside the housing is increased to a considerable level when the igniter is operated by reducing the size to a predetermined size.

  On the other hand, when a fire occurs in a vehicle or the like equipped with an air bag device incorporating a gas generator, the temperature inside the gas generator is several hundred degrees by heating the gas generator from the outside. There are cases where the temperature is raised to a certain extent. In that case, if the temperature of the gas generating agent or transfer charge reaches its spontaneous ignition temperature, a so-called auto ignition operation is triggered in which the gas generating agent starts to burn without igniting the igniter. It becomes.

  When the auto-ignition operation is induced, the gas generator itself is already in a high temperature state due to heating from the outside, so that the pressure inside the housing is caused by the combustion of the gas generating agent during the operation of the igniter described above. There is a concern that the pressure will rise to a pressure much higher than required, which will cause damage to the housing. When such a damage occurs in the housing, fragments of the housing and internal components are scattered around, which causes a serious problem in terms of safety.

  There is US Pat. No. 5,346,251 (Patent Document 1) as a document disclosing a gas generator with improved safety even when the auto-ignition operation is induced. In the gas generator disclosed in Patent Document 1, a weak portion having a 1/4 arc shape in a plan view, which is relatively thin compared to the surroundings, is formed in a part of the housing, so that auto ignition is performed. The fragile portion is intentionally broken when the pressure inside the housing reaches a predetermined pressure during operation. As a result, the upper limit value of the pressure rise inside the housing when the auto ignition operation is induced is regulated, and the safety is improved by preventing the state from exceeding the upper limit value. ing.

US Pat. No. 5,346,251

  However, even when the configuration disclosed in Patent Document 1 is adopted, when the housing is configured by combining press-formed products formed by pressing one metal plate-like member, Even if the thickness of the fragile portion formed in the housing is made constant, there is a problem that a large variation occurs in the breaking pressure. For this reason, it is difficult to configure the housing to break at the intended pressure during auto-ignition operation or the like, and its design is extremely difficult.

  In addition, the above-mentioned Patent Document 1 does not specifically mention whether the position where the fragile portion is provided should be the top plate portion or the bottom plate portion of the housing, depending on the position where the fragile portion is provided, It is difficult to say that safety will necessarily increase.

  Therefore, the present invention has been made to solve the above-mentioned problems, and even when the pressure inside the housing becomes abnormally high, such as when an auto ignition operation is induced, the operation is stable. An object of the present invention is to provide a safer gas generator that can be controlled easily.

  In the gas generator, when the housing is configured by combining a press-molded product formed by pressing a single metal plate-like member, the inventor of the weakened portion formed in the housing. Even if the thickness is made constant, the cause of the large variation in the breaking pressure is found to be the relationship between the rolling direction of a single metal plate-like member and the shape of the thin fragile portion. The present invention has been completed by conceiving that the position where the fragile portion is provided is a predetermined position of the housing, thereby significantly improving safety.

  A gas generator according to a first aspect of the present invention includes a housing, a gas generating agent, and an igniter. The housing is made of a short cylindrical member having an accommodating space inside, and includes a top plate portion and a bottom plate portion that close the end portion in the axial direction, and a peripheral wall portion provided with a gas outlet. The said gas generating agent is arrange | positioned in the said accommodation space, and generates gas by burning. The igniter is for burning the gas generating agent, and is assembled to the bottom plate portion. The housing is erected outward from the peripheral wall portion, and further includes a fixing portion for fixing the housing to an external member. The gas outlet is provided on the peripheral wall portion of the portion located on the top plate portion side with respect to the position where the fixing portion is provided. The housing has a lower shell made of a press-formed product formed by pressing a single metal plate member, and the lower shell constitutes at least the bottom plate portion. Yes. The housing defining the housing space has a relatively thick non-fragile portion and a relatively thin weak portion, and the weak portion is linear on the lower shell. It is formed by providing the single groove part extended in. The shape of the single groove has rotational symmetry about the axis of the housing as a rotation center.

  In the gas generator based on the first aspect of the present invention, the single groove is preferably provided in a circumferential shape.

  A gas generator according to the second aspect of the present invention includes a housing, a gas generating agent, and an igniter. The housing is made of a short cylindrical member having an accommodating space inside, and includes a top plate portion and a bottom plate portion that close the end portion in the axial direction, and a peripheral wall portion provided with a gas outlet. The said gas generating agent is arrange | positioned in the said accommodation space, and generates gas by burning. The igniter is for burning the gas generating agent, and is assembled to the bottom plate portion. The housing is erected outward from the peripheral wall portion, and further includes a fixing portion for fixing the housing to an external member. The gas outlet is provided on the peripheral wall portion of the portion located on the top plate portion side with respect to the position where the fixing portion is provided. The housing has a lower shell made of a press-formed product formed by pressing a single metal plate member, and the lower shell constitutes at least the bottom plate portion. Yes. The housing defining the housing space has a relatively thick non-fragile portion and a relatively thin weak portion, and the weak portion is linear on the lower shell. Are formed by providing a plurality of grooves extending in the direction. The shape of the plurality of grooves has rotational symmetry about the axis of the housing as the center of rotation when the plurality of grooves are regarded as a unit.

  In the gas generator based on the second aspect of the present invention, each of the plurality of grooves is preferably provided in a circumferential shape.

  In the gas generator according to the second aspect of the present invention, each of the plurality of grooves is preferably provided in an arc shape.

  In the gas generator according to the second aspect of the present invention, it is preferable that each of the plurality of grooves is provided radially about the axis of the housing.

  In the gas generator based on the first aspect and the second aspect of the present invention, it is preferable that the groove is provided on the inner surface of the lower shell in a portion facing the accommodation space. .

  In the gas generator based on the first aspect and the second aspect of the present invention, the fragile portion is the lower shell of the portion that defines the gas generating agent storage chamber in which the gas generating agent is stored. It is preferable to be formed.

  In the gas generator based on the first aspect and the second aspect of the present invention, it is preferable that the fragile portion is formed on the bottom plate portion.

  In the gas generator based on the first aspect and the second aspect of the present invention, the lower shell is positioned closer to the bottom plate part than the position where the bottom plate part and the fixing part are provided. The peripheral wall portion of the portion to be configured may be configured, and in this case, the weakened portion is formed on the peripheral wall portion of the portion located on the bottom plate portion side from the position where the fixing portion is provided. It may be.

  According to the present invention, even when the pressure inside the housing becomes abnormally high, such as when an auto ignition operation is induced, a more safe gas that can stably control the operation. It can be a generator.

It is the schematic of the gas generator in Embodiment 1 of this invention. It is a principal part expanded sectional view of the gas generator shown in FIG. It is the top view and sectional drawing of the lower side shell of the gas generator shown in FIG. It is a schematic cross section of the airbag apparatus provided with the gas generator shown in FIG. It is the top view and sectional drawing of the lower side shell of the gas generator in Embodiment 2 of this invention. It is the top view and sectional drawing of the lower side shell of the gas generator in Embodiment 3 of this invention. It is the schematic of the gas generator in Embodiment 4 of this invention. 6 is a plan view and a cross-sectional view of a lower shell according to Comparative Example 2. FIG. 10 is a table showing test conditions and test results of Comparative Examples 1 and 2 and Examples 1 to 9 in a verification test. It is a graph which shows the test results of Comparative Examples 1 and 2 and Examples 1 to 9 in the verification test.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the embodiment described below, the present invention is applied to a disk-type gas generator incorporated in an airbag device mounted on a steering wheel or the like of an automobile. In the following embodiments, the same or common parts are denoted by the same reference numerals in the drawings, and description thereof will not be repeated.

(Embodiment 1)
FIG. 1 is a schematic diagram of a gas generator according to Embodiment 1 of the present invention. 2 is an enlarged cross-sectional view of a main part of a region II shown in FIG. 1 of the gas generator shown in FIG. 3 is a diagram showing the shape of the lower shell of the gas generator shown in FIG. 1, FIG. 3 (A) is a plan view of the lower shell, and FIG. 3 (B) is the lower shell. It is sectional drawing which followed the IIIB-IIIB line | wire shown in FIG. 3 (A). First, with reference to these FIG. 1 thru | or FIG. 3, the structure of 1 A of gas generators in this Embodiment is demonstrated.

  As shown in FIG. 1, the gas generator 1A according to the present embodiment has a short, substantially cylindrical housing that is closed at both ends in the axial direction. In the housing space provided inside the housing, The holding unit 30, the igniter 40, the cup-shaped member 50, the transfer agent 56, the gas generating agent 61, the lower holding member 62, the upper holding member 63, the cushion material 64, the filter 70, etc. are accommodated as internal components It consists of Further, a gas generating agent storage chamber 60 in which the gas generating agent 61 among the above-described internal components is mainly stored is located in the storage space provided inside the housing.

  The short, substantially cylindrical housing includes a lower shell 10 </ b> A and an upper shell 20. Each of the lower shell 10A and the upper shell 20 is made of a press-formed product formed by pressing a rolled metal plate member.

  Each of the lower shell 10A and the upper shell 20 is formed in a substantially cylindrical shape with a bottom, and a housing is configured by joining these opening surfaces so as to face each other. The lower shell 10 </ b> A 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. As a result, the axial end of the housing is closed by the top plate portion 21 and the bottom plate portion 11. For joining the lower shell 10A and the upper shell 20, electron beam welding, laser welding, friction welding, or the like can be suitably used.

  The upper shell 20 further includes a fixing portion 25 that is erected continuously outward from the lower end of the peripheral wall portion 22. The fixing portion 25 is a portion for fixing the housing to an external member (more specifically, a machine casing 110 (see FIG. 4) of the airbag device incorporated in the steering wheel 100), and is thereby installed. Later, the gas generator 1A is supported by the external member.

  As shown in FIGS. 1 and 3, a projecting cylindrical portion 13 protruding toward the top plate portion 21 side is provided at the center portion of the bottom plate portion 11 of the lower shell 10 </ b> A. A recess 14 is formed at the center of the bottom plate 11 of 10A. The projecting cylindrical portion 13 is a portion to which the igniter 40 is fixed via the holding portion 30 described above, and the recessed portion 14 is a portion that becomes a space for providing the female connector portion 34 in the holding portion 30. .

  The projecting cylindrical portion 13 is formed in a substantially cylindrical shape with a bottom, and an opening 15 having a circular shape in plan view is provided at an axial end located on the top plate portion 21 side. The opening 15 is a part through which the pair of terminal pins 42 of the igniter 40 is inserted. In addition, a plurality of convex portions 13a are projected from the axial end portion of the protruding cylindrical portion 13 on the top plate portion 21 side toward the top plate portion 21 so as to surround the opening 15 described above. Yes.

  The lower shell 10A is manufactured by pressing a metal plate member rolled as described above. Specifically, the lower shell 10A is illustrated by pressing a rolled metal plate member from above and below using, for example, a pair of molds including an upper mold and a lower mold. It is manufactured by being molded into the shape as described above.

  Here, as the metal plate-like member constituting the lower shell 10A, for example, a metal plate made of stainless steel, steel, an aluminum alloy, a stainless alloy, or the like is used, and preferably has a tensile stress of 440 MPa to 780 MPa. A so-called high-tensile steel plate that does not cause breakage or the like even when applied is preferably used. The press working may be performed by hot forging or cold forging, but is more preferably performed by cold forging from the viewpoint of improving dimensional accuracy.

  As shown in FIG. 1 to FIG. 3, a weak portion 11a is formed by providing a single loop-shaped groove 16 at a predetermined position of the lower shell 10A. It will be described later.

  The upper shell 20 is manufactured by pressing a metal plate member rolled as described above. Specifically, the upper shell 20 is illustrated by pressing a rolled metal plate member from above and below using, for example, a pair of molds including an upper mold and a lower mold. It is manufactured by being molded into the shape as described above. Here, as the metal plate-like member constituting the upper shell 20, a metal plate made of stainless steel, steel, an aluminum alloy, a stainless alloy, or the like can be used as in the case of the lower shell 10A described above. is there.

  As shown in FIG. 1, the igniter 40 is an ignition device for generating a flame, and includes an ignition unit 41 and the pair of terminal pins 42 described above. The ignition unit 41 includes therein an igniting agent that generates a flame by igniting and burning during operation, and a resistor for igniting the igniting agent. The pair of terminal pins 42 are connected to the ignition unit 41 to ignite the igniting agent.

  More specifically, the ignition unit 41 includes a squib cup formed in a cup shape, and a base that closes the open end of the squib cup and through which the pair of terminal pins 42 are inserted and held, A resistor (bridge wire) is attached so as to connect the tips of the pair of terminal pins 42 inserted in the squib cup, and a dot is placed in the squib cup so as to surround the resistor or close to the resistor. It has a configuration loaded with explosives.

  Here, nichrome wire or the like is generally used as the resistor, and ZPP (zirconium / potassium perchlorate), ZWPP (zirconium / tungsten / potassium perchlorate), lead tricinate, or the like is generally used as the igniting agent. The squib cup and the base portion described above are generally made of metal or plastic.

  When a collision is detected, a predetermined amount of current flows through the resistor via the terminal pin 42. When a predetermined amount of current flows through the resistor, Joule heat is generated in the resistor, and the ignition agent starts burning. The high temperature flame generated by the combustion ruptures the squib cup containing the igniting agent. The time from when the current flows through the resistor until the igniter 40 is activated is generally 2 milliseconds or less when a nichrome wire is used as the resistor.

  The igniter 40 is attached to the bottom plate part 11 in a state where the terminal pin 42 is inserted from the inside of the lower shell 10 </ b> A so that the terminal pin 42 is inserted into the opening 15 provided in the protruding cylindrical part 13. Specifically, a holding portion 30 made of a resin molded portion is provided around the protruding cylindrical portion 13 provided on the bottom plate portion 11, and the igniter 40 is held by the holding portion 30. Thus, the bottom plate portion 11 is fixed.

  Here, the size of the opening 15 provided in the projecting cylindrical portion 13 is configured to be smaller than the outer shape of the ignition portion 41 which is the maximum outer shape portion of the igniter 40. By configuring in this way, even if the holding part 30 is unexpectedly damaged, the igniter 40 passes through the opening 15 due to an increase in pressure inside the housing, and the outside of the housing. And the safe operation of the gas generator 1A is ensured.

  The holding portion 30 is formed by injection molding (more specifically, insert molding) using a mold, and the bottom plate portion 11 is passed through an opening 15 provided in the bottom plate portion 11 of the lower shell 10A. Insulating fluid resin material is attached to the bottom plate portion 11 so as to reach from a part of the inner surface to a part of the outer surface, and is solidified.

  The igniter 40 is inserted from the inside of the lower shell 10A so that the terminal pin 42 is inserted into the opening 15 when the holding portion 30 is molded. In this state, the igniter 40 and the lower shell The fluid resin material described above is poured so as to fill the space between 10A and fixed to the bottom plate part 11 via the holding part 30.

  As a raw material of the holding part 30 formed by injection molding, a resin material excellent in heat resistance, durability, corrosion resistance and the like after curing is suitably selected and used. In that case, it is not limited to a thermosetting resin typified by an epoxy resin or the like, but is typified by a polybutylene terephthalate resin, a polyethylene terephthalate resin, a polyamide resin (for example, nylon 6 or nylon 66), a polypropylene sulfide resin, or a polypropylene oxide resin. It is also possible to use a thermoplastic resin. When these thermoplastic resins are selected as raw materials, it is preferable to contain glass fibers or the like as fillers in these resin materials in order to ensure the mechanical strength of the holding portion 30 after molding. However, when sufficient mechanical strength can be ensured with only the thermoplastic resin, it is not necessary to add the filler as described above.

  The holding part 30 includes an inner covering part 31 that covers a part of the inner surface of the bottom plate part 11 of the lower shell 10A, an outer covering part 32 that covers a part of the outer surface of the bottom plate part 11 of the lower shell 10A, and a lower part It has the connection part 33 which is located in the opening part 15 provided in the baseplate part 11 of 10 A of side shells, and continues to the said inner side coating part 31 and the outer side coating part 32, respectively.

  The holding part 30 is fixed to the bottom plate part 11 on the surface of each of the inner covering part 31, the outer covering part 32 and the connecting part 33 on the bottom plate part 11 side. Further, the holding unit 30 is fixed to the side surface and the lower surface of the portion near the lower end of the ignition unit 41 of the igniter 40 and the surface of the portion near the upper end of the terminal pin 42 of the igniter 40. As a result, the opening 15 is completely embedded by the terminal pin 42 and the holding part 30, and the sealing property at the part is ensured, thereby ensuring the airtightness of the space inside the housing.

  The inner covering portion 31 of the holding portion 30 is provided so as to cover only the axial end portion of the protruding cylindrical portion 13 provided on the bottom plate portion 11, and thereby the inside of the housing of the protruding cylindrical portion 13. The outer peripheral surface located at is not covered by the holding portion 30 and is exposed.

  A female connector portion 34 is formed on a portion of the holding portion 30 facing the outside of the outer covering portion 32. The female connector portion 34 is a portion for receiving a male connector (not shown) of a harness for connecting the igniter 40 and a control unit (not shown), and the bottom plate portion 11 of the lower shell 10A. It is located in the hollow part 14 provided in. In the female connector portion 34, a portion near the lower end of the terminal pin 42 of the igniter 40 is disposed so as to be exposed. A male connector is inserted into the female connector portion 34, thereby realizing electrical continuity between the harness core wire and the terminal pin 42.

  Here, the holding | maintenance part 30 is formed so that the some convex part 13a provided in the protruding cylinder part 13 mentioned above may be covered. Specifically, the plurality of convex portions 13 a are embedded in the holding portion 30 by being covered by the inner covering portion 31 of the holding portion 30. Accordingly, it is possible to prevent the holding portion 30 from rotating relative to the bottom plate portion 11 after the injection molding, and the plurality of convex portions 13a provided on the protruding cylindrical portion 13 described above. Functions as a rotation preventing convex portion.

  The position at which the plurality of convex portions 13a as the rotation preventing convex portions are provided is not limited to the above, and any position as long as it is the surface of the bottom plate portion 11 to be covered by the holding portion 30. It may be provided. Moreover, the convex part 13a as a convex part for rotation prevention does not necessarily need to be provided with two or more, and may be one.

  Alternatively, the above-described injection molding may be performed using the lower shell 10A in which an adhesive layer is provided in advance at a predetermined position on the surface of the bottom plate portion 11 that is to be covered by the holding portion 30. The adhesive layer can be formed by previously applying an adhesive to a predetermined position of the bottom plate portion 11 and curing it.

  In this way, since the cured adhesive layer is positioned between the bottom plate portion 11 and the holding portion 30, the holding portion 30 made of the resin molded portion can be more firmly fixed to the bottom plate portion 11. It becomes possible. Therefore, it is possible to prevent the holding portion 30 from rotating relative to the bottom plate portion 11 after injection molding. Further, if the adhesive layer is provided in an annular 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 the portion.

  Here, as the adhesive to be applied in advance to the bottom plate portion 11, a material containing a resin material excellent in heat resistance, durability, corrosion resistance and the like after curing as a raw material is preferably used. Those containing a resin or a silicone resin as a raw material are particularly preferably used. In addition to the above resin materials, phenolic resins, epoxy resins, melamine resins, urea resins, polyester resins, alkyd resins, polyurethane resins, polyimide resins, polyethylene resins, polypropylene resins, Polyvinyl chloride resin, polystyrene resin, polyvinyl acetate resin, polytetrafluoroethylene resin, acrylonitrile butadiene styrene resin, acrylonitrile styrene resin, acrylic resin, polyamide resin, polyacetal resin, polycarbonate resin, Polyphenylene ether resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyolefin resin, polyphenylene sulfide resin, polysulfone resin, polyether sulfone resin, polyester Arylate resins, polyether ether ketone resin, polyamide-imide resin, liquid crystal polymer, styrene rubber, those containing olefin rubbers such as is available as an adhesive as described above.

  The position where the adhesive is applied is not particularly limited. For example, the outer surface of the bottom plate portion 11 where the protruding cylindrical portion 13 is formed (that is, covered by the outer covering portion 32 of the holding portion 30). The entire surface of the bottom plate portion 11) or only a part thereof, or the inner surface of the portion of the bottom plate portion 11 where the protruding cylindrical portion 13 is formed (that is, the portion covered by the inner covering portion 31 of the holding portion 30). Or the entire surface of the bottom plate portion 11 that is covered by the holding portion 30.

  In addition, when the squib cup and the base part constituting the igniter 41 are used as the igniter 40, the part of the igniter 40 to be covered by the holding part 30 is used. An adhesive layer may be provided by previously applying an adhesive at a predetermined position on the surface of the film. If comprised in this way, it will become possible to fix the igniter 40 firmly by the holding | maintenance part 30, like the case where the adhesive bond layer is previously provided in the baseplate part 11 mentioned above, and higher sealing performance in the said part. Can be secured.

  Further, in the present embodiment, the case where the holding unit 30 is configured to be integrated with the igniter 40 and the lower shell 10A is illustrated when the holding unit 30 is molded. The holding unit 30 may be integrated only with the lower shell 10A, and the igniter 40 may be assembled to the molded holding unit 30 by, for example, fitting. In that case, since the holding part 30 is fixed only to the lower shell 10A, the sealing performance between the holding part 30 and the igniter 40 is not secured by this alone. If an appropriate sealing process is performed such as arranging an O-ring on the surface, sufficient sealing performance can be ensured.

  A cup-shaped member 50 is assembled to the bottom plate portion 11 so as to cover the protruding cylindrical portion 13, the holding portion 30 and the igniter 40. The cup-shaped member 50 has a substantially cylindrical shape with an open end on the bottom plate portion 11 side, and includes a heat transfer chamber 55 in which a charge transfer agent 56 is accommodated. The cup-shaped member 50 is directed toward the gas generating agent storage chamber 60 in which the gas generating agent 61 is stored so that the heat transfer chamber 55 provided therein faces the ignition part 41 of the igniter 40. Are arranged so as to protrude.

  The cup-shaped member 50 includes a top wall portion 51 and a side wall portion 52 that define the above-described transfer chamber 55, and an extending portion 53 that extends radially outward from a portion of the side wall portion 52 on the opening end side. have. The extending portion 53 is formed so as to extend along the inner surface of the bottom plate portion 11 of the lower shell 10A. Specifically, the extending portion 53 has a shape that is curved so as to follow the shape of the inner bottom surface of the bottom plate portion 11 in the vicinity of the portion where the protruding cylindrical portion 13 is provided, and the diameter thereof. A distal end portion 54 extending in a flange shape is included in a portion on the outer side in the direction.

  The distal end portion 54 of the extending portion 53 is disposed between the bottom plate portion 11 and the lower holding member 62 along the axial direction of the housing, whereby the bottom plate portion 11 and the lower side are disposed along the axial direction of the housing. It is sandwiched between the holding member 62. Here, the lower holding member 62 is pressed toward the bottom plate portion 11 by the gas generating agent 61, the cushion material 64, the upper holding member 63, and the top plate portion 21 disposed above the lower holding member 62. The cup-shaped member 50 is in a state in which the distal end portion 54 of the extending portion 53 is pressed toward the bottom plate portion 11 by the lower holding member 62 and is fixed to the bottom plate portion 11.

  The portion of the cup-shaped member 50 on the opening end side of the side wall portion 52 is extrapolated to the inner covering portion 31 that is a portion located inside the housing of the holding portion 30 so as to be press-fitted and fixed to the holding portion 30. Has been. The press-fit fixing is a fixing portion for facilitating the assembly work when the cup-shaped member 50 is assembled to the housing. The cup-shaped member 50 is also fixed to the bottom plate portion by the press-fit fixing. 11 will be fixed.

  The cup-shaped member 50 does not have an opening in any of the top wall portion 51 and the side wall portion 52 and surrounds a heat transfer chamber 55 provided therein. The cup-shaped member 50 ruptures or melts as the pressure in the transfer chamber 55 rises or conduction of generated heat occurs when the transfer powder 56 is ignited by the operation of the igniter 40. A material having a relatively low mechanical strength is used.

  Therefore, as the cup-shaped member 50, a metal member such as aluminum or an aluminum alloy, a thermosetting resin typified by an epoxy resin, a polybutylene terephthalate resin, a polyethylene terephthalate resin, a polyamide resin (for example, nylon 6 or nylon) 66), and those made of a resin member such as a thermoplastic resin typified by polypropylene sulfide resin, polypropylene oxide resin and the like are preferably used.

  In addition to the above, the cup-shaped member 50 is made of a metal member having high mechanical strength such as iron or copper, and has an opening in the side wall portion 52. It is also possible to use one having a seal tape attached so as to close the opening.

The transfer charge 56 filled in the transfer chamber 55 is ignited by the flame generated by the operation of the igniter 40 and burns to generate hot particles. The charge transfer agent 56 must be capable of reliably starting the combustion of the gas generating agent 61, and is generally composed of a metal powder / oxidizer represented by B / KNO ₃ or the like. Things are used. As the charge transfer agent 56, a powdery one, a one molded into a predetermined shape by a binder, or the like is used. Examples of the shape of the charge transfer agent 56 molded by the binder include various shapes such as a granular shape, a columnar shape, a sheet shape, a spherical shape, a single-hole cylindrical shape, a porous cylindrical shape, and a tablet shape.

  A gas generating agent storage chamber 60 in which a gas generating agent 61 is stored is placed in a space surrounding the portion where the cup-shaped member 50 is disposed in the space inside the housing composed of the lower shell 10A and the upper shell 20. Is located. Specifically, as described above, the cup-shaped member 50 is disposed so as to protrude into the gas generating agent storage chamber 60 formed inside the housing, and the outer surface of the side wall portion 52 of the cup-shaped member 50. A space provided in a portion facing the gas generating agent accommodating chamber 60 is configured.

  A filter 70 is disposed along the inner periphery of the housing in a space surrounding the gas generating agent storage chamber 60 in the radial direction of the housing. The filter 70 has a cylindrical shape, and is arranged so that the central axis thereof substantially matches the axial direction of the housing, whereby the gas generating agent storage chamber 60 in which the gas generating agent 61 is stored. Is surrounded in the radial direction.

  The gas generating agent 61 is an agent that generates gas by being ignited and burned by hot particles generated when the igniter 40 is operated. As the gas generating agent 61, it is preferable to use a non-azide-based gas generating agent, and the gas generating agent 61 is generally formed as a molded body containing a fuel, an oxidizing agent, and an additive. As the fuel, for example, a triazole derivative, a tetrazole derivative, a guanidine derivative, an azodicarbonamide derivative, a hydrazine derivative, or a combination thereof is used. Specifically, for example, nitroguanidine, guanidine nitrate, cyanoguanidine, 5-aminotetrazole and the like are preferably used. The oxidizing agent is selected from basic nitrates such as basic copper nitrate, perchlorates such as ammonium perchlorate and potassium perchlorate, alkali metals, alkaline earth metals, transition metals, and ammonia. Nitrate containing cation is used. As the nitrate, for example, sodium nitrate, potassium nitrate and the like are preferably used. In addition, examples of the additive include a binder, a slag forming agent, and a combustion adjusting agent. As the binder, for example, an organic binder such as a metal salt of carboxymethyl cellulose or a stearate, or an inorganic binder such as synthetic hydroxytalcite or acidic clay can be suitably used. As the slag forming agent, silicon nitride, silica, acid clay, etc. can be suitably used. Moreover, as a combustion regulator, a metal oxide, ferrosilicon, activated carbon, graphite, etc. can be used suitably.

  The shape of the molded body of the gas generating agent 61 includes various shapes such as granular shapes, pellet shapes, granular shapes such as columnar shapes, and disk shapes. In addition, in the cylindrical shape, a porous (for example, a single-hole cylindrical shape or a porous cylindrical shape) having a through hole inside the molded body is also used. These shapes are preferably selected as appropriate according to the specifications of the airbag apparatus in which the gas generator 1A is incorporated. For example, the shape in which the gas generation rate changes with time during the combustion of the gas generating agent 61 is selected. It is preferable to select an optimal shape according to the specifications. 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 in consideration of the linear combustion rate, the pressure index, etc. of the gas generating agent 61.

  The filter 70 is, for example, one obtained by winding and sintering a metal wire such as stainless steel or steel, one obtained by pressing a net material knitted with a metal wire, or by winding a perforated metal plate. Things are used. Here, as the net material, specifically, a knit metal mesh, a plain weave metal mesh, an assembly of crimped metal wires, or the like is used. In addition, as a perforated metal plate, for example, expanded metal that has been cut into a zigzag pattern on the metal plate and expanded to form a hole and processed into a mesh shape, or a hole is formed in the metal plate and at that time A hook metal or the like obtained by flattening the burr generated at the periphery of the hole is used. In this case, the size and shape of the hole to be formed can be appropriately changed as necessary, and holes of different sizes and shapes may be included on the same metal plate. In addition, as a metal plate, a steel plate (mild steel), a stainless steel plate, for example can be used suitably, and nonferrous metal plates, such as aluminum, copper, titanium, nickel, or these alloys, can also be utilized.

  The filter 70 functions as a cooling means for cooling the gas by taking away the high-temperature heat of the gas when the gas generated in the gas generating agent storage chamber 60 passes through the filter 70, and in the gas. It also functions as a removing means for removing contained residues (slag) and the like. Therefore, in order to sufficiently cool the gas and prevent the residue from being discharged to the outside, it is necessary to ensure that the gas generated in the gas generating agent storage chamber 60 passes through the filter 70. It is.

  A plurality of gas jets 23 are provided in the peripheral wall portion 22 of the upper shell 20 at the portion facing the filter 70 (that is, the peripheral wall portion of the portion located on the top plate portion 21 side from the position where the fixing portion 25 is provided). Is provided. The gas outlet 23 is for leading the gas that has passed through the filter 70 to the outside of the housing. A seal tape 24 is affixed to a main surface located on the filter 70 side of the peripheral wall portion 22 of the upper shell 20 so as to close the gas ejection port 23. As this sealing tape 24, an aluminum foil or the like having an adhesive member applied on one side is used. Thereby, the airtightness of the gas generating agent accommodation chamber 60 is ensured.

  In the gas generating agent storage chamber 60, a lower holding member 62 is disposed in the vicinity of the end located on the bottom plate portion 11 side. The lower holding member 62 has an annular shape and is disposed so as to cover the boundary portion between the filter 70 and the bottom plate portion 11. The lower holding member 62 positions and holds the filter 70 by contacting the inner peripheral surface located on the bottom plate portion 11 side of the filter 70, and the tip portion 54 of the cup-shaped member 50 between the bottom plate portion 11 and the lower holding member 62. The cup-shaped member 50 is held by sandwiching.

  During operation, the lower holding member 62 flows out of the gap between the lower end of the filter 70 and the bottom plate portion 11 without passing through the inside of the filter 70 without gas generated in the gas generating agent storage chamber 60. To prevent it. The lower holding member 62 is formed by, for example, pressing a metal plate-like member, and preferably a steel plate such as ordinary steel or special steel (for example, a cold-rolled steel plate or a stainless steel plate). ).

  An upper holding member 63 is disposed at an end portion of the gas generating agent storage chamber 60 located on the top plate portion 21 side. The upper holding member 63 has a substantially disc shape, and is disposed so as to cover the boundary portion between the filter 70 and the top plate portion 21. The upper holding member 63 positions and holds the filter 70 by contacting the inner peripheral surface located on the top plate portion 21 side of the filter 70, and holds the cushion material 64 disposed therein.

  When the upper holding member 63 is in operation, the gas generated in the gas generating agent storage chamber 60 flows out from the gap between the upper end of the filter 70 and the top plate portion 21 without passing through the inside of the filter 70. To prevent it. The upper holding member 63 is formed by, for example, pressing a metal plate-like member, like the lower holding member 62, and preferably a steel plate such as ordinary steel or special steel (for example, Cold rolled steel plate, stainless steel plate, etc.).

  An annular cushion material 64 is disposed inside the upper holding member 63 so as to contact the gas generating agent 61 accommodated in the gas generating agent accommodating chamber 60. Accordingly, the cushion material 64 is positioned between the top plate portion 21 and the gas generating agent 61 in the portion on the top plate portion 21 side of the gas generating agent storage chamber 60, and the gas generating agent 61 is placed on the bottom plate portion 11. It is pressing toward the side. The cushion material 64 is provided for the purpose of preventing the gas generating agent 61 made of a molded body from being crushed by vibration or the like, and is preferably a ceramic fiber molded body, rock wool, foamed resin (for example, (Such as foamed silicone, foamed polypropylene, foamed polyethylene, etc.), chloroprene, and a member made of rubber typified by EPDM.

  FIG. 4 is a schematic cross-sectional view of an airbag apparatus equipped with the gas generator shown in FIG. Next, with reference to this FIG. 4, the assembly structure to the airbag apparatus of 1 A of gas generators in this Embodiment is demonstrated.

  As shown in FIG. 4, the steering wheel 100 mainly includes a machine frame 110 located inside and a resin cover 120 that covers the surface, and is located inside the resin cover 120 and closer to the occupant side than the machine frame 110. The airbag 130 is accommodated in the space in which the airbag 130 is folded. The gas generator 1A is fixed to the machine casing 110 among them.

  Specifically, the fixing portion 25 provided in the upper shell 20 is provided with a through hole, and the machine frame 110 at a position corresponding to the through hole is also provided with a through hole. Then, the fixing bars 111 are inserted into the through holes in a state where the through holes are aligned with each other, and nuts are fastened from both sides of the fixing bar 111 so that the gas generator 1A is attached to the machine frame 110. Fixed.

  Further, a pressing member 112 is disposed between the nuts attached to the fixing bar 111, and an end portion of the folded airbag 130 is sandwiched between the machine frame 110 and the pressing member 112. . Thereby, the airbag 130 is also fixed to the machine casing 110.

  Here, in the gas generator 1A, the end on the side where the upper shell 20 is located is arranged on the occupant side, and the lower shell 10A is arranged on the non-occupant side (that is, the side where the occupant is not located). , Fixed to the machine casing 110. As a result, the gas outlet 23 provided in the upper shell 20 is disposed at a position closer to the passenger than the machine casing 110 and faces the inside of the folded airbag 130. On the other hand, the fragile portion 11 a provided in the lower shell 10 </ b> A is arranged at a position closer to the non-occupant side than the machine casing 110.

  Next, the operation of the gas generator 1A in the present embodiment described above will be described with reference to FIG.

  When a vehicle on which the gas generator 1A according to the present embodiment is mounted collides, the collision is detected by a collision detection unit provided separately in the vehicle, and based on this, a control unit provided separately in the vehicle The igniter 40 is activated by energization. The transfer charge 56 accommodated in the transfer chamber 55 is ignited and burned by the flame generated by the operation of the igniter 40 and generates a large amount of heat particles. The cup-shaped member 50 is ruptured or melted by the combustion of the charge transfer agent 56, and the above-described hot particles flow into the gas generating agent storage chamber 60.

  Due to the flowing heat particles, the gas generating agent 61 accommodated in the gas generating agent accommodating chamber 60 is ignited and burned to generate a large amount of gas. The gas generated in the gas generating agent storage chamber 60 passes through the inside of the filter 70. At this time, heat is taken away by the filter 70 and cooled, and slag contained in the gas is removed by the filter 70. It flows into the outer peripheral edge of the housing.

  As the internal pressure of the housing increases, the sealing by the sealing tape 24 that has closed the gas outlet 23 of the upper shell 20 is broken, and gas is jetted out of the housing through the gas outlet 23. The jetted gas is introduced into an airbag provided adjacent to the gas generator 1A, and the airbag is inflated and deployed.

  As described above, in the gas generator 1A according to the present embodiment, the fragile portion 11a is formed by providing the single loop-shaped groove 16 at a predetermined position of the lower shell 10A. Hereinafter, the groove 16 and the fragile portion 11a will be described in more detail with reference to FIGS.

  As shown in FIGS. 1 to 3, a loop-shaped groove portion 16 as a single groove portion extending linearly is provided on a portion of the inner surface of the lower shell 10 </ b> A facing the gas generating agent storage chamber 60. ing. The loop-shaped groove portion 16 is configured by a concave portion having a circular shape in a plan view and having a V-shaped concave surface, and has rotational symmetry (so-called continuous symmetry) around the axis of the lower shell 10A. Have. The loop-shaped groove portion 16 may be formed at the same time as the pressing process when the lower shell 10A is manufactured, or may be formed by adding a cutting process before and after the pressing process. Good.

  The loop-shaped groove portion 16 is provided to form the fragile portion 11a in a part of the housing which is a pressure vessel, and the fragile portion 11a formed by the loop-shaped groove portion 16 is located around the periphery. The lower shell 10A is configured to be thinner than the non-fragile portion. As a result, when the auto ignition operation is induced, the lower shell 10A can be intentionally broken starting from any part of the weakened part 11a, and the auto ignition operation is induced. The behavior of the gas generator 1A can be controlled.

  Here, as described above, when the housing is configured by combining press-formed products formed by pressing a single metal plate-like member, the thickness of the weakened portion formed in the housing is reduced. Even if it is configured to be constant, there is a problem that a large variation occurs in the breaking pressure. The cause of the problem is that when an external force is applied to the rolled metal plate member and sheared, the breaking strength depends on the relationship between the shear direction and the rolling direction of the metal plate member. This is due to the difference.

  That is, in the case where the fragile portion is formed by providing the groove portion in the lower shell, when the rolling direction and the extending direction of the groove portion match, the breaking strength becomes the smallest, and the rolling direction and the extending direction of the groove portion The breaking strength is maximized when the two are orthogonal. Therefore, when forming the fragile part by providing the groove part, it is possible to configure so as not to cause a large variation in breaking strength by forming the groove part after managing the rolling direction, It is very difficult to manage the rolling direction when considering mass productivity.

  However, as described above, if the fragile portion 11a is formed by providing the loop-shaped groove portion 16 that is not interrupted as in the present embodiment, the groove portion 16 formed without managing the rolling direction. Since there is always a portion where the extending direction of the steel and the rolling direction are substantially parallel, the above-described variation in the breaking strength can be suppressed. That is, as shown in FIG. 3A, in the case where the rolling direction faces any direction of the lower shell 10A (in the drawing, the rolling direction is representatively shown as four directions DR1 to DR4. The relationship between the rolling direction and the fragile portion 11a is uniform, and there is no difference in this relationship for each product. As a result, there is almost no variation in the breaking strength of the housing. Therefore, even when an auto-ignition operation is induced, the housing can be controlled to break when the pressure inside the housing reaches a predetermined pressure.

  Here, the thickness of the fragile portion 11a is necessary to stably burn the gas generating agent 61 in the normal operation state of the gas generator 1A in which the gas generating agent 61 burns when the igniter 40 operates. Even when pressure is applied to the fragile portion 11a, when the thickness is such that it does not break and the pressure inside the housing becomes higher than that in the normal operation state, the pressure is predetermined. Is set to a thickness at which a part of the fragile portion 11a starts and the lower shell 10A is broken. Thereby, during the normal operation of the gas generator 1A, the housing can be prevented from being broken, and the operation can be guaranteed.

  Further, since the upper limit value of the pressure rise inside the housing when the auto ignition operation is induced is determined by the thickness, size, shape, etc. of the weakened portion 11a, the shape and size of the loop-shaped groove portion 16 are determined. This can be defined to a desired value by changing the above. That is, as described above, when the loop-shaped groove portion 16 is constituted by a concave portion having a circumferential shape in plan view and having a V-shaped concave surface, its width W and depth D (see FIGS. 2 and 3). The upper limit value can be set to a desired value by changing. In order to configure the loop-shaped groove 16 so as to face the gas generating agent storage chamber 60, a distance d from the center of the bottom-side shell 10A formed in a substantially cylindrical shape with a bottom (FIGS. 1 and 3). Can be realized by adjusting so that the reference is within a predetermined range.

  Further, it is preferable that the area of the loop-shaped groove portion 17 provided for forming the fragile portion 11a in a plan view is sufficiently smaller than the area of the inner surface of the bottom plate portion 11 of the lower shell 10A. . This is because it is difficult to ensure the pressure resistance in a normal operation state when the area of the fragile portion 11a is increased by increasing the area of the loop-shaped groove 16 when viewed in plan. In order to avoid this, it is preferable to form a smaller area when the fragile portion 11a is viewed in plan.

  In the present embodiment, as illustrated, the case where the loop-shaped groove 16 is provided so as to have a V-shaped concave surface is illustrated, but the shape is not limited to this. It may be provided so as to have a concave surface such as a concave shape, a U-shape, or a curved surface shape, or may be provided so as to have a concave surface of another shape.

  Furthermore, as described above, in the gas generator 1A in the present embodiment, the fragile portion 11a is provided in the bottom plate portion 11 of the lower shell 10A. By configuring in this way, as shown in FIG. 4, in the installed state, the fragile portion 11a is located on the non-occupant side when viewed from the gas generator 1A, and in the event that an auto ignition operation is induced by any chance, etc. In addition, the portion provided with the fragile portion 11a becomes the fracture portion BP of the housing, and high-temperature and high-pressure gas is ejected in the direction of the arrow AR shown in the drawing.

  Therefore, even if the housing breaks and the fragments of the housing and the internal components are scattered around, it will be scattered toward the non-occupant side and can be prevented from flying toward the occupant side. Even if there are passengers who have escaped, the damage can be reduced.

  As described above, by using the gas generator 1A in the present embodiment, even when an auto ignition operation is induced, the operation can be stably controlled, and safety is further improved. Gas generator.

  In the present embodiment, the case where only one loop-shaped groove portion 16 is provided in the bottom plate portion 11 of the lower shell 10A is illustrated, but a plurality of the loop-shaped groove portions 16 are provided concentrically. Also good.

(Embodiment 2)
FIG. 5 is a diagram showing the shape of the lower shell of the gas generator according to Embodiment 2 of the present invention. FIG. 5 (A) is a plan view of the lower shell, and FIG. 5 (B) is the lower side. It is sectional drawing along the VB-VB line | wire shown in FIG. 5 (A) of a shell. Hereinafter, the structure of the gas generator 1B in the present embodiment will be described with reference to FIG. The gas generator 1B according to the present embodiment includes a lower shell 10B shown in FIG. 5 instead of the lower shell 10A of the gas generator 1A according to the first embodiment.

  As shown in FIG. 5, the bottom plate portion 11 of the lower shell 10B is provided with four substantially 1/4 arc-shaped groove portions 17 as a plurality of linearly extending groove portions on the circumference at equal intervals. Thereby, the four weak parts 11a are formed. Each of the substantially ¼ arc-shaped groove portions 17 is formed by a concave portion having a V-shaped concave surface as in the case of the first embodiment described above, whereby each of the four weak portions 11a. Is configured to be thinner than the non-fragile portion of the lower shell 10B located in the periphery thereof. Here, since these four approximately 1/4 arc-shaped groove portions 17 are provided at equal intervals on the circumference as described above, when these are regarded as one body, the lower shell 10B It has rotational symmetry (so-called discrete symmetry) around the axis.

  Even in such a configuration, in the same manner as in the case of the gas generator 1A in the first embodiment described above, even when the rolling direction is directed to any direction of the lower shell 10B (in the drawing) Shows the four rolling directions of DR1 to DR4 as a representative), and the relationship between the rolling direction and the fragile portion 11a is almost uniform, and there is almost no difference in this relationship for each product. There will be little variation in the breaking strength of the housing. Therefore, by using the gas generator 1B in the present embodiment, even when an auto ignition operation is induced, the operation can be stably controlled, and the gas generator with further improved safety. It can be.

  In the present embodiment, the case where four fragile portions 11a are formed by providing four substantially circular arc-shaped groove portions 17 on the circumference at equal intervals is illustrated. However, it is arranged on the circumference. The number of arc-shaped groove portions 17 to be formed is not limited to this, and may be set to any number as long as it is plural. However, from the viewpoint of stably controlling the operation of the gas generator when an auto-ignition operation is induced, it is not preferable that the distance between the adjacent weak portions 11a is too large. It is preferable that they are arranged close to each other.

(Embodiment 3)
6A and 6B are diagrams showing the shape of the lower shell of the gas generator according to Embodiment 3 of the present invention. FIG. 6A is a plan view of the lower shell, and FIG. 6B is the lower side. It is sectional drawing along the VIB-VIB line | wire shown in FIG. 6 (A) of a shell. Hereinafter, the structure of the gas generator 1C in the present embodiment will be described with reference to FIG. The gas generator 1C in the present embodiment includes a lower shell 10C shown in FIG. 6 instead of the lower shell 10A of the gas generator 1A in the first embodiment described above.

  As shown in FIG. 6, the bottom plate portion 11 of the lower shell 10C is provided with eight linear groove portions 18 as a plurality of linearly extending groove portions at equal intervals in the radial direction. Part 11a is formed. Each linear groove portion 18 is configured by a concave portion having an elliptical shape in a plan view (more strictly, a track shape) and a curved concave surface extending along the radial direction of the lower shell 10C. Thus, each of the eight fragile portions 11a is configured to be thinner than the non-fragile portion of the lower shell 10C located around the fragile portion 11a. Here, since these eight linear grooves 18 are provided radially at equal intervals as described above, when these are regarded as one body, the axis of the lower shell 10C is rotated around the rotation center. It has symmetry (so-called discrete symmetry).

  Even in such a configuration, in the same manner as in the case of the gas generator 1A in the first embodiment described above, even when the rolling direction is directed to any direction of the lower shell 10B (in the drawing) Shows the four rolling directions of DR1 to DR4 as a representative), and the relationship between the rolling direction and the fragile portion 11a is almost uniform, and there is almost no difference in this relationship for each product. There will be little variation in the breaking strength of the housing. Therefore, by using the gas generator 1C in the present embodiment, even when an auto ignition operation is induced, the operation can be stably controlled, and the gas generator with further improved safety. It can be.

  In the present embodiment, the case where eight fragile portions 11a are formed by providing eight linear grooves 18 at equal intervals in the radial direction is illustrated, but the linear grooves 18 arranged radially are illustrated. The number is not limited to this, and any number may be set as long as it is plural. However, from the viewpoint of stably controlling the operation of the gas generator when an auto-ignition operation is induced, it is not preferable that the distance between the adjacent weak portions 11a is too large. It is preferable that at least four or more are provided so as to be closely arranged.

(Embodiment 4)
FIG. 7 is a schematic view of a gas generator according to Embodiment 4 of the present invention. Hereinafter, the structure of the gas generator 1D in the present embodiment will be described with reference to FIG. The gas generator 1D in the present embodiment includes a lower shell 10D shown in FIG. 7 instead of the lower shell 10A of the gas generator 1A in the first embodiment described above.

  As shown in FIG. 7, in the gas generator 1D according to the present embodiment, the bottom plate portion 11 of the lower shell 10D is not provided with a loop-shaped groove, and instead the peripheral wall portion of the lower shell 10D. By providing the loop-shaped groove 16 at a predetermined position of 12, the fragile portion 12a is formed in the lower shell 10D. The loop-shaped groove portion 16 provided in the peripheral wall portion 12 has the same shape as that in the above-described first embodiment, whereby the fragile portion 12a is formed on the lower shell 10D located around the periphery. The thickness is smaller than that of the non-fragile portion.

  Here, when the loop-shaped groove portion 16 is provided in the peripheral wall portion 12 of the lower shell 10D as in the present embodiment, the fragile portion 12a provided in the lower shell 10D faces the gas generating agent storage chamber 60. Instead, it faces the space between the filter 70 and the peripheral wall portions 12, 22 of the housing. However, in this case as well, since the space is in communication with the gas generating agent storage chamber 60 via the space inside the filter 70, when the auto ignition operation is induced, the weak portion 12a is started. As a result, the lower shell 10D can be intentionally broken.

  Therefore, even in the case of such a configuration, the operation can be stably controlled even when the auto ignition operation is induced as in the case of the gas generator 1A in the first embodiment described above. It becomes possible and it can be set as the gas generator whose safety | security was improved more.

  Although illustration is omitted here, instead of the loop-shaped groove portion 16, an arc-shaped groove portion 17 as in the second embodiment described above or a radial groove portion 18 as in the third embodiment described above is provided. It is good also as providing in the predetermined position of the surrounding wall part 12 of lower part side shell 10D. In this case, the same effect can be obtained.

  Hereinafter, a verification test performed for verifying the effect of the present invention will be described. 8A and 8B are diagrams showing the shape of the lower shell according to Comparative Example 2. FIG. 8A is a plan view of the lower shell, and FIG. 8B is FIG. 8A of the lower shell. It is sectional drawing along the VIIIB-VIIIB line | wire shown in it. FIG. 9 is a table showing test conditions and test results of Comparative Examples 1 and 2 and Examples 1 to 9 in the verification test. FIG. 9 is a graph showing the test results of Comparative Examples 1 and 2 and Examples 1 to 6 in the verification test.

  In the verification test, as Examples 1 to 8, eight types and five samples according to the configuration of the housing provided in the gas generator 1A in the first embodiment to which the present invention is applied are manufactured. As Example 9, one type and five samples according to the configuration of the housing provided in the gas generator 1C according to the above-described third embodiment to which the present invention is applied are manufactured, and as Comparative Examples 1 and 2 Two types of housings included in a gas generator to which the present invention is not applied were manufactured in five samples, and the breaking pressure (that is, the breaking strength) was measured by applying these samples to a hydroburst tester. . Note that the shapes and dimensions of the samples according to Examples 1 to 9 and Comparative Examples 1 and 2 were all set in common.

  The samples according to Examples 1 to 8 have a constant depth and the number of concave surfaces of the loop-shaped grooves 16 as compared with the lower shell 10A provided in the gas generator 1A according to Embodiment 1 described above. D and width W (see FIGS. 2 and 3) and a distance d (see FIGS. 1 and 3) from the center of the lower shell 10A are made different, and details thereof are as shown in FIG. is there.

  In the sample according to Example 9, the concave shape, the depth D, and the width of the linear grooves 18 provided radially at equal intervals in the lower shell 10C provided in the gas generator 1C in the above-described third embodiment. W, length L, and distance d from the center of the lower shell 10X (see FIG. 6) are set as shown in FIG.

  The sample according to Comparative Example 1 is not provided with the loop-shaped groove portion 16 as compared with the lower shell 10A provided in the gas generator 1A in the first embodiment, and therefore has no weak portion 11a. I do not have it.

  As shown in FIG. 8, the sample according to Comparative Example 2 is a linear groove provided radially at equal intervals as compared to the lower shell 10C provided in the gas generator 1C in the third embodiment. By providing a single linear groove 19 instead of 18, a single linear fragile portion 11b extending in the radial direction is formed in the bottom plate portion 11 of the lower shell 10X. The details of the concave shape, depth D, width W, length L, and distance d (see FIG. 8) from the center of the lower shell 10X of the single linear groove 19 are shown in FIG. Street.

  As shown in FIG. 9 and FIG. 10, when the samples according to Comparative Examples 1 and 2 and Examples 1 to 9 were subjected to a hydroburst tester, both of the samples according to Comparative Example 1 were upper shells (that is, In the state of being incorporated in the airbag device, a breakage occurs in the portion of the housing located on the occupant side, and the remaining samples in Comparative Example 2 and Examples 1 to 9 both have a lower shell (that is, an airbag). It was confirmed that breakage occurred in the portion of the housing located on the non-occupant side in the state of being incorporated into the apparatus.

  Moreover, when the average value of the breaking strength of the sample according to Comparative Example 1 was set to 100%, in the sample according to Comparative Example 2, the breaking strength varied in the range of about 12%, whereas In the samples according to Examples 1 to 6, it was confirmed that the variation in breaking strength was generally limited to a range of 4% to 5%. In addition, when comparing between the samples according to Examples 1 to 8, it was also confirmed that the breaking strength gradually decreased as the volume of the loop-shaped groove portion increased.

  Based on the above results, by using the gas generator as in the embodiment of the present invention described above, it is possible to stably control the operation even when the auto ignition operation is induced, etc. It can be said that it was confirmed experimentally that a gas generator with improved safety can be obtained.

  In the first to fourth embodiments of the present invention described above, the case where the fragile portion is formed by providing a groove portion having a predetermined shape on the inner surface of the lower shell is illustrated. The fragile portion may be formed by providing a groove portion having a shape, or the fragile portion may be formed by providing groove portions having a predetermined shape on the inner surface and the outer surface of the corresponding position of the lower shell. In addition, when it is set as the structure which does not provide a groove part in the outer surface of a lower side shell, since the corner | angular part which may arise by providing the said groove part in the outer surface of a gas generator will not generate | occur | produce, the handling is advantageous. Become. In addition, when the groove portion is not provided on the inner surface of the lower shell, the position where the fragile portion is formed is the lower shell of the portion directly facing the gas generating agent accommodated in the gas generating agent accommodating chamber. In this case, it is possible to prevent the gas generating agent from being crushed by corners that may be generated by providing the groove.

  Moreover, in Embodiments 1 to 4 of the present invention described above, the case where the fragile portion is formed by providing a groove portion having a predetermined shape only in either the bottom plate portion or the peripheral wall portion of the lower shell is illustrated. The fragile portion may be formed by providing the groove portion of a predetermined shape so as to straddle both the bottom plate portion and the peripheral wall portion of the lower shell, and the plurality of groove portions of the predetermined shape include the bottom plate portion and the peripheral wall of the lower shell. A plurality of weak parts may be formed by being provided in both of the parts.

  Moreover, in Embodiment 1 thru | or 4 of this invention mentioned above, although the case where the lower side shell had not only a bottom plate part but a surrounding wall part was illustrated, the lower side shell has only a bottom plate part. Of course, the present invention can also be applied to the case of the above. In that case, a weak part should just be formed by providing the groove part of a predetermined shape in the bottom plate part of the lower shell.

  Moreover, in Embodiment 1 thru | or 4 of this invention mentioned above, although the case where the fixing | fixed part for fixing a gas generator to an external member was provided in the upper side shell was illustrated, the said fixing | fixed part is a lower part. It may be provided in the side shell.

  In the above-described first to fourth embodiments of the present invention, it is constituted by a press-molded product formed by pressing a rolled metal plate-like member not only on the lower shell but also on the upper shell. However, the upper shell is not necessarily limited to this, and a shell formed by a combination of pressing and other processing (forging, drawing, cutting, etc.) is used. You may use what was formed only by the said other process.

  Further, in the first to fourth embodiments of the present invention described above, the case where the projecting cylindrical portion is provided in the lower shell is illustrated, but the present invention is applied to a gas generator having a configuration in which the projecting cylindrical portion is not provided. Of course, it is also possible to apply.

  Furthermore, in the above-described first to fourth embodiments of the present invention, the case where the fixing of the igniter to the lower shell is made possible by injection molding the holding portion made of the resin molding portion is illustrated. Of course, the present invention can also be applied to a gas generator in which the igniter is fixed to the shell by other alternative means. Naturally, specific shapes of internal components such as the holding portion, the igniter, the cup-shaped member, the filter, the lower holding member, and the upper holding member can be appropriately changed.

  Thus, the above-described embodiment disclosed herein is illustrative in all respects and is not restrictive. The technical scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1A to 1D Gas generator, 10A to 10D Lower side shell, 11 Bottom plate part, 11a Fragile part, 12 Peripheral wall part, 12a Fragile part, 13 Projecting cylindrical part, 13a Convex part, 14 Depressed part, 15 Open part, 16 ~ 18 groove portion, 20 upper shell, 21 top plate portion, 22 peripheral wall portion, 23 gas ejection port, 24 seal tape, 25 fixing portion, 30 holding portion, 31 inner covering portion, 32 outer covering portion, 33 connecting portion, 34 female Type connector part, 40 igniter, 41 ignition part, 42 terminal pin, 50 cup-shaped member, 51 top wall part, 52 side wall part, 53 extension part, 54 tip part, 55 fire transfer chamber, 56 transfer powder, 60 gas Generating agent storage chamber, 61 Gas generating agent, 62 Lower holding member, 63 Upper holding member, 64 Cushion material, 70 Filter, 100 Steering wheel, 110 Machine frame, 111 Fixing bar, 112 holding member, 120 resin cover, 130 airbag.

Claims (10)

A short cylindrical housing including a top plate portion and a bottom plate portion for closing an end portion in the axial direction, and a peripheral wall portion provided with a gas outlet, and having an accommodation space therein;
A gas generating agent disposed in the housing space and generating gas by burning;
An igniter that is assembled to the bottom plate portion and burns the gas generating agent;
The housing further includes a fixing portion that is erected outward from the peripheral wall portion and that fixes the housing to an external member;
The gas ejection port is provided in the peripheral wall portion of the portion located on the top plate portion side from the position where the fixing portion is provided,
The housing comprises a lower shell made of a press-formed product formed by pressing at least the bottom plate portion and pressing one metal plate-like member,
The housing defining the housing space has a relatively thick non-fragile portion and a relatively thin weak portion,
The fragile portion is formed by providing a single groove extending linearly in the lower shell,
The shape of the single groove part is a gas generator having rotational symmetry about the axis of the housing as a rotation center.   The gas generator according to claim 1, wherein the single groove portion is provided in a circumferential shape. A short cylindrical housing including a top plate portion and a bottom plate portion for closing an end portion in the axial direction, and a peripheral wall portion provided with a gas outlet, and having an accommodation space therein;
A gas generating agent disposed in the housing space and generating gas by burning;
An igniter that is assembled to the bottom plate portion and burns the gas generating agent;
The housing further includes a fixing portion that is erected outward from the peripheral wall portion and that fixes the housing to an external member;
The gas ejection port is provided in the peripheral wall portion of the portion located on the top plate portion side from the position where the fixing portion is provided,
The housing comprises a lower shell made of a press-formed product formed by pressing at least the bottom plate portion and pressing one metal plate-like member,
The housing defining the housing space has a relatively thick non-fragile portion and a relatively thin weak portion,
The fragile portion is formed by providing a plurality of grooves extending linearly in the lower shell,
The shape of the plurality of groove portions is a gas generator having rotational symmetry about the axis of the housing when the plurality of groove portions are regarded as one body.   The gas generator according to claim 3, wherein each of the plurality of grooves is provided in a circumferential shape.   The gas generator according to claim 3, wherein each of the plurality of grooves is provided in an arc shape.   4. The gas generator according to claim 3, wherein each of the plurality of grooves is provided radially about the axis of the housing.   The gas generator according to any one of claims 1 to 6, wherein the groove is provided on an inner surface of the lower shell in a portion facing the accommodation space.   The gas generator according to any one of claims 1 to 7, wherein the fragile portion is formed in the lower shell of a portion that defines a gas generating agent storage chamber in which the gas generating agent is stored.   The gas generator according to any one of claims 1 to 8, wherein the fragile portion is formed in the bottom plate portion. The lower shell constitutes the bottom plate portion and the peripheral wall portion of the portion located on the bottom plate portion side from the position where the fixing portion is provided,
The gas generator according to any one of claims 1 to 8, wherein the fragile portion is formed on the peripheral wall portion of a portion located closer to the bottom plate portion than a position where the fixing portion is provided.

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