JP7734812B2 - Gas generator - Google Patents

Description

The present invention relates to a gas generator incorporated into an airbag device as an occupant protection device fitted to an automobile or the like, and in particular to a so-called cylinder-type gas generator with a long, cylindrical outer shape that is suitable for incorporation into a side airbag device or the like.

Airbag systems, which are occupant protection devices, have become widespread in automobiles and other vehicles to protect passengers. Airbag systems are installed to protect passengers from the impact that occurs during a vehicle collision. When a vehicle crashes, the airbag instantly inflates and deploys, acting as a cushion to support the passenger's body.

The gas generator is incorporated into this airbag device. When a vehicle crashes, the control unit energizes the igniter, igniting the igniter. The flame generated in the igniter burns the gas generating agent, instantly generating a large amount of gas, which inflates and deploys the airbag.

Gas generators come in a variety of configurations, based on specifications such as their installation position relative to the vehicle and their output. One type is known as a cylinder-type gas generator. Cylinder-type gas generators have a long, cylindrical outer shape and are ideally suited for incorporation into side airbag devices, curtain airbag devices, knee airbag devices, seat cushion airbag devices, etc.

Typically, in a cylinder-type gas generator, an igniter is attached to one axial end of the housing, and a combustion chamber containing gas generating agent is provided at that end. A filter chamber containing a filter is provided at the other axial end of the housing, and a gas outlet is provided in the peripheral wall of the housing at the part that defines the filter chamber.

In a cylinder-shaped gas generator configured in this manner, gas generated in the combustion chamber flows into the filter chamber along the axial direction of the housing, passing through the inside of the filter, and after passing through the filter, the gas is ejected to the outside through the gas ejection port.

In general, it is important that the gas generating agent in a gas generator is airtightly sealed from the outside. This is because if the gas generating agent absorbs moisture, it may not be possible to obtain the desired gas output characteristics.

One method for preventing moisture absorption by the gas generating agent in a cylinder-type gas generator is to store the gas generating agent in a container made of a fragile material that melts or bursts due to the heat or pressure generated by the activation of the igniter, then seal the container and place it inside the housing. A cylinder-type gas generator that employs this method is disclosed, for example, in JP 2018-69924 A (Patent Document 1).

However, adopting the above method raises the issue of increased manufacturing costs. Specifically, the cost of the containers made from the aforementioned fragile materials is relatively high, and the process of sealing the container after placing the gas generating agent inside it requires considerable effort, which also increases manufacturing costs.

On the other hand, another method for preventing the gas generating agent from absorbing moisture in a cylinder-type gas generator is to provide O-rings, sealing tape, or other similar devices in various locations on the housing to hermetically seal the combustion chamber containing the gas generating agent. A cylinder-type gas generator employing this method is disclosed, for example, in Japanese Patent Laid-Open No. 2008-296763 (Patent Document 2).

In the cylinder-type gas generator disclosed in Patent Document 2, the housing is configured to include a substantially cylindrical housing body and a holder that holds an igniter and is inserted into the open end of the housing body. A sealing member, such as an O-ring, is interposed between the housing body and the holder, and a sealing member, such as sealing tape, is affixed to close a communication hole provided in a member separating the combustion chamber and filter chamber, thereby ensuring airtightness in these areas. Furthermore, by adopting this method, manufacturing costs can be reduced compared to using a sealed container.

Japanese Patent Application Laid-Open No. 2018-69924 Japanese Patent Application Laid-Open No. 2008-296763

However, in the cylinder-type gas generator disclosed in Patent Document 2, the functions and characteristics of the holder described above require holding the igniter, receiving the connector connected to the igniter, providing a strong connection with the housing body, and being strong enough to withstand the increase in internal pressure in the combustion chamber when the gas generator is activated. This inevitably results in a complex shape for the holder, and also requires high machining precision, resulting in the problem of high component costs for the holder.

Furthermore, since the holder is a relatively large metal part, there is also the problem that the weight of the cylinder-type gas generator inevitably increases.

The present invention has therefore been made to solve the above-mentioned problems, and aims to provide a gas generator that reduces manufacturing costs and weight.

A gas generator according to the present invention comprises a housing body, a holder assembly, and an igniter. The housing body is a cylindrical metal member containing a combustion chamber containing a gas generating agent. The holder assembly is inserted into the axial open end of the housing body and includes a through-hole-like hollow opening extending parallel to the axial direction of the housing body. The igniter includes an ignition section containing an ignition charge and a terminal pin connected to the ignition section, and is at least partially disposed within the hollow opening with the ignition section located on the combustion chamber side and the terminal pin located on the opposite side from the combustion chamber. The holder assembly includes a metal holder section located on the combustion chamber side that receives and holds the igniter, and a resin connector section located on the opposite side from the combustion chamber that can receive a connector connected to the terminal pin. The holder portion includes a cylindrical first body portion that defines the hollow opening and an annular protrusion that protrudes from the first body portion along the radial direction of the housing body. The connector portion includes a cylindrical second body portion that defines the hollow opening and a cylindrical portion that extends from the second body portion toward the combustion chamber. The cylindrical portion is inserted into the open end of the housing body and is inserted onto a portion of the first body portion that is located on the opposite side of the combustion chamber from the annular protrusion. In the gas generator based on the present invention, the diameter of the portion of the housing body corresponding to the cylindrical portion narrows radially inward, and the cylindrical portion is sandwiched and compressed by the housing body and the first body portion at the narrowed diameter portion, thereby sealing the gap between the housing body and the first body portion.

In the gas generator based on the present invention, the inner diameter of the cylindrical portion may be larger than the inner diameter of the second body portion, and the connector portion may be provided with an annular stepped surface connecting the inner circumferential surface of the second body portion and the inner circumferential surface of the cylindrical portion, thereby forming a first chamber defined by the annular stepped surface and the inner circumferential surface of the cylindrical portion at the axial end portion of the connector portion located on the combustion chamber side. In this case, it is preferable that the first body portion is inserted into the first chamber, and that the axial end face of the first body portion located opposite the combustion chamber side abuts the annular stepped surface.

In the gas generator according to the present invention, the inner diameter of the second barrel portion may be larger than the inner diameter of the first barrel portion, so that a second chamber defined by the axial end face of the first barrel portion located opposite the combustion chamber side and the inner circumferential surface of the second barrel portion may be provided at the axial end portion of the holder assembly located opposite the combustion chamber side. In this case, it is preferable that the second chamber constitutes a receiving portion for a connector to be connected to the terminal pin.

In the gas generator according to the present invention, the outer peripheral surface of the first body portion may have a diameter that decreases toward the combustion chamber.

The gas generator according to the present invention may further include a filter disposed inside the housing body, and a partition member disposed inside the housing body to separate the space inside the housing body in the axial direction of the housing body into a filter chamber in which the filter is disposed and the combustion chamber. In this case, the partition member may be fixed to the housing body by welding.

The present invention allows for a gas generator that is lightweight and has reduced manufacturing costs.

1 is a schematic view of a cylinder-shaped gas generator according to an embodiment. 2 is an enlarged cross-sectional view of the vicinity of an igniter of the cylinder-shaped gas generator shown in FIG. 1. FIG. 2 is an enlarged cross-sectional view of the vicinity of a partition member of the cylinder-shaped gas generator shown in FIG. 1. FIG. 4A to 4C are cross-sectional views showing a procedure for assembling a holder assembly in the cylinder-shaped gas generator shown in FIG. 1. 4A to 4C are cross-sectional views showing a procedure for assembling a holder assembly in the cylinder-shaped gas generator shown in FIG. 1. FIG. 10 is a cross-sectional view of a holder assembly of a cylinder-shaped gas generator according to first to fourth modified examples.

Embodiments of the present invention will now be described in detail with reference to the drawings. The embodiments shown below illustrate the application of the present invention to a cylinder-type gas generator incorporated in a side airbag device. In the embodiments shown below, identical or common parts are designated by the same reference numerals in the drawings, and their description will not be repeated.

Figure 1 is a schematic diagram of a cylinder-shaped gas generator according to an embodiment. Figures 2 and 3 are enlarged cross-sectional views of the vicinity of the igniter and the vicinity of the partition member of the cylinder-shaped gas generator shown in Figure 1, respectively. First, the configuration of the cylinder-shaped gas generator 1 according to this embodiment will be described with reference to Figures 1 to 3.

As shown in FIG. 1, the cylinder-shaped gas generator 1 according to this embodiment has a long, cylindrical outer shape and includes a long, cylindrical housing with one axial end and the other end closed. The housing includes a housing main body 10, a holder assembly 20, and a closing member 30.

The housing, which is composed of the housing main body 10, holder assembly 20, and closing member 30, contains internal components such as an igniter 40, partition member 50, gas generating agent 60, coil spring 70, and filter 80. Also located inside the housing are a combustion chamber S1, in which the gas generating agent 60 is primarily located, and a filter chamber S2, in which the filter 80 is located.

The housing body 10 forms the peripheral wall of the housing and is made of a long, cylindrical member with openings at both axial ends. The holder assembly 20 is made of a tubular member with a through-hole-like hollow opening extending parallel to the axial direction of the housing body 10, and includes a holder portion 20A and a connector portion 20B, which will be described later. The closure member 30 has a cup shape including a closure portion 31 and a side wall portion 32, and the peripheral surface of the side wall portion 32 has an annular recess 33 for crimping, which will be described later. This annular recess 33 for crimping, which will be described later, is formed on the peripheral surface of the side wall portion 32 so as to extend circumferentially.

The housing body 10 may be made of a metal member such as stainless steel, iron steel, aluminum alloy, or stainless alloy, or may be made of a press-formed product formed into a cylindrical shape by pressing a rolled steel plate, such as SPCE. The housing body 10 may also be made of an electric resistance welded pipe, such as STKM.

In particular, when the housing body 10 is constructed from a press-formed rolled steel plate or an electric resistance welded pipe, it can be formed more cheaply and easily than when using metal components such as stainless steel or steel, and the weight can be significantly reduced.

On the other hand, the holder portion 20A and the blocking member 30 of the holder assembly 20 are made of metal members such as stainless steel, iron and steel, aluminum alloy, and stainless alloy.

The holder assembly 20 is fixed to the housing body 10 so as to close one axial open end of the housing body 10. Specifically, with the holder assembly 20 inserted into the one open end of the housing body 10, a predetermined position of the housing body 10 is narrowed radially inward toward the outer peripheral surface of the holder assembly 20, thereby crimping and fixing the holder assembly 20 to the housing body 10. As a result, one axial end of the housing is formed by the holder assembly 20. Details of this crimping and fixing will be explained later.

The blocking member 30 is fixed to the housing body 10 so as to block the other axial open end of the housing body 10. Specifically, with the blocking member 30 inserted into the other open end of the housing body 10, the portion of the housing body 10 corresponding to the annular recess 33 provided on the circumferential surface of the side wall portion 32 of the blocking member 30 is reduced in diameter radially inward and engages with the annular recess 33, thereby crimping and fixing the blocking member 30 to the housing body 10. As a result, the other axial end of the housing is defined by the blocking member 30.

These crimping methods are called eight-way crimping, which reduces the diameter of the housing body 10 radially inward in a generally uniform manner. By performing this eight-way crimping, crimped portions 12 and 13 are formed on the housing body 10. As a result, crimped portions 12 and 13 come into direct contact with the outer peripheral surface of the holder assembly 20 and the annular recess 33, respectively, preventing gaps from forming between them.

The assembly structure of the closing member 30 to the housing main body 10 is not limited to the assembly structure described above, and other assembly structures may be adopted. Furthermore, rather than forming the housing main body 10 and the closing member 30 as separate bodies, they may be constructed as a single member having a cylindrical shape with a bottom.

As shown in Figures 1 and 2, the igniter 40 is supported by the holder assembly 20 and is attached to the axial end of the housing. The igniter 40 is used to combust the gas generating agent 60 and is installed facing the interior space of the housing.

The igniter 40, which is also called a squib, is used to generate a flame. The igniter 40 includes a base 41, an ignition portion 42, and a pair of terminal pins 43. The base 41 is the portion that holds the ignition portion 42 and the pair of terminal pins 43, and is also the portion that is fixed to the holder assembly 20. The pair of terminal pins 43 are inserted into the base 41 to hold them.

The ignition unit 42 contains an ignition charge that ignites and burns to generate a flame when activated, and a resistor (bridge wire) for igniting the ignition charge. A pair of terminal pins 43 are connected to the ignition unit 42 to ignite the ignition charge.

More specifically, the ignition unit 42 includes a cup-shaped squib cup, to which the aforementioned resistor is attached so as to connect the tips of a pair of terminal pins 43 inserted into the squib cup, and an ignition charge is loaded into the squib cup so as to surround or be close to the resistor. Furthermore, a transfer charge may be loaded into the ignition unit 42 as needed.

Here, the resistor generally uses a nichrome wire or a resistance wire made of an alloy containing platinum and tungsten, and the ignition charge generally uses ZPP (zirconium potassium perchlorate), ZWPP (zirconium tungsten potassium perchlorate), lead tricinate, etc. Furthermore, the transfer charge may use a composition made of a metal powder/oxidizer, such as B/KNO ₃ , B/NaNO ₃ , or Sr(NO ₃ ) ₂ , a composition made of titanium hydride/potassium perchlorate, or a composition made of B/5-aminotetrazole/potassium nitrate/molybdenum trioxide.

When a collision is detected, a predetermined amount of current flows through the resistor via the terminal pin 43. This current flow generates Joule heat in the resistor, causing the ignition charge to begin burning. The high-temperature particles generated by the combustion split open the squib cup containing the ignition charge. The time from when current flows through the resistor to when the igniter 40 is activated is generally less than 2 milliseconds when nichrome wire is used for the resistor.

The igniter 40 is fixed to the holder assembly 20 with its ignition portion 42 protruding toward the interior of the housing and a portion of it positioned inside the hollow opening of the holder assembly 20. As a result, the ignition portion 42 of the igniter 40 is positioned on the combustion chamber S1 side, and its terminal pin 43 is positioned on the opposite side from the combustion chamber S1. Details of the fixing structure of the igniter 40 to the holder assembly 20 will be explained later.

As shown in Figures 1 and 3, a partition member 50 is disposed at a predetermined position in the space inside the housing. The partition member 50 is a member that divides the space inside the housing in the axial direction into a combustion chamber S1 and a filter chamber S2.

The partition member 50 has a cylindrical shape with a bottom and is made of a metal member such as stainless steel, iron or steel, aluminum alloy, or stainless alloy. The partition member 50 has a flat partition wall portion 51 arranged perpendicular to the axial direction of the housing main body 10, and a cylindrical annular wall portion 52 erected from the periphery of the partition wall portion 51. The partition member 50 is arranged so that the outer main surface of the partition wall portion 51 abuts against the filter 80, and the outer peripheral surface of the annular wall portion 52 abuts against the inner peripheral surface of the housing main body 10.

Scores 51a are provided on the main surface of the partition wall 51 that abuts against the filter 80. The scores 51a are designed to cause the partition wall 51 to break and form an opening as the internal pressure of the combustion chamber S1 increases due to combustion of the gas generating agent 60, and are composed of, for example, multiple grooves arranged radially and intersecting each other. The scores 51a are provided in the portion of the filter 80 that faces the hollow portion 81.

The partition member 50 is fixed by being inserted into the housing main body 10 and joined to the housing main body 10. More specifically, the partition member 50 is press-fitted into the housing main body 10 and fixed by welding the annular wall portion 52 of the partition member 50 to the housing main body 10 at or near the contact point between them.

As a result, a weld 90 extending along the circumferential direction of the housing main body 10 is formed on the housing main body 10 and the partition member 50 corresponding to the portion into which the partition member 50 is inserted. Note that electron beam welding, laser welding, resistance welding, etc. can be suitably used to weld the partition member 50 to the housing main body 10.

When the partition member 50 is fixed to the housing main body 10 by welding in this manner, the gap between the partition member 50 and the housing main body 10 is filled with the welded portion 90, thereby sealing the gap. Therefore, this configuration makes it possible to ensure airtightness in that area.

The method of fixing the partition member 50 to the housing main body 10 is not limited to the above-mentioned methods using press-fitting and welding, and other fixing methods may also be used. In such cases, ensuring airtightness between the partition member 50 and the housing main body 10 can be achieved by, for example, providing an O-ring or sealing tape in an appropriate position.

As shown in Figures 1 to 3, within the space inside the housing, a gas generating agent 60 and a coil spring 70 are disposed in the space sandwiched between the holder assembly 20 and the partition member 50 (i.e., the combustion chamber S1).

The gas generating agent 60 is an agent that generates gas by being ignited and burning by thermal particles generated by the activation of the igniter 40. It is preferable to use a non-azide gas generating agent as the gas generating agent 60, and the gas generating agent 60 is generally configured as a molded body containing fuel, an oxidizer, and an additive.

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, nitroguanidine, guanidine nitrate, cyanoguanidine, or 5-aminotetrazole is preferably used.

Examples of oxidizing agents include basic metal salts such as basic copper nitrate and basic copper carbonate, perchlorates such as ammonium perchlorate and potassium perchlorate, and nitrates containing cations selected from alkali metals, alkaline earth metals, transition metals, and ammonia. Suitable nitrates include sodium nitrate and potassium nitrate.

Additives include binders, slag formers, and combustion modifiers. Suitable binders include organic binders such as metal salts of carboxymethyl cellulose and stearates, and inorganic binders such as synthetic hydrotalcite and acid clay. Suitable slag formers include silicon nitride, silica, and acid clay. Suitable combustion modifiers include metal oxides, ferrosilicon, activated carbon, and graphite.

The molded body of the gas generating agent 60 can be in a variety of shapes, including granular, pellet-like, cylindrical, and other granular shapes, as well as disk-like shapes. Cylindrical molded bodies can also be used with perforated shapes (such as single-hole or multi-hole cylindrical shapes) that have through holes inside. These shapes are preferably selected appropriately depending on the specifications of the airbag device in which the cylindrical gas generator 1 is incorporated. It is preferable to select the optimal shape for the specifications, such as a shape that changes the gas generation rate over time when the gas generating agent 60 burns. In addition to the shape of the gas generating agent 60, it is also preferable to select the size and filling amount of the molded body appropriately, taking into consideration the linear burning velocity and pressure exponent of the gas generating agent 60, etc.

The coil spring 70 is provided to prevent the gas generating agent 60, which is a molded body, from being crushed by vibration, etc., and has a spring portion 71 and a pressing portion 72 formed by bending metal wire. One end of the spring portion 71 is positioned so that it abuts the holder assembly 20 and/or the igniter 40, and the pressing portion 72 is formed at the other end. The pressing portion 72 is formed, for example, by metal wires arranged approximately parallel with a predetermined gap, and abuts the gas generating agent 60.

As a result, the gas generating agent 60 is elastically biased toward the partition member 50 by the coil spring 70, preventing it from moving inside the housing.

Here, the end of the coil spring 70 on the holder assembly 20 side surrounds the ignition portion 42 of the igniter 40 so as to be in contact with the ignition portion 42 or so as to be positioned close to the ignition portion 42 of the igniter 40 with a predetermined clearance. By configuring it in this way, when the squib cup of the ignition portion 42 breaks open upon activation of the igniter 40, the degree to which the squib cup opens is restricted by the coil spring 70.

As a result, by appropriately regulating the degree of opening of the squib cup, the direction of travel of the thermal particles generated in the ignition section 42 is narrowed to the axial direction of the housing body 10, allowing the thermal particles to be efficiently guided to the gas generating agent 60. In other words, the coil spring 70 surrounding the ignition section 42 also has the function of providing directionality to the direction of travel of the thermal particles generated in the ignition section 42.

As shown in FIG. 1, a filter 80 is disposed in the space within the housing, sandwiched between the closing member 30 and the partition member 50 (i.e., the filter chamber S2). The filter 80 is a cylindrical member having a hollow portion 81 extending parallel to the axial direction of the housing body 10, with one axial end face abutting against the side wall portion 32 of the closing member 30 and the other axial end face abutting against the partition wall portion 51 of the partition member 50.

The filter 80 functions as a cooling means for cooling the gas generated by the combustion of the gas generating agent 60 by removing the high-temperature heat contained in the gas as it passes through the filter 80, and also functions as a removal means for removing slag (residue) and other contaminants contained in the gas. As described above, by using the filter 80 made of a cylindrical member, the flow resistance to the gas flowing through the filter chamber S2 during operation is kept low, enabling efficient gas flow.

The filter 80 can be preferably made of an assembly of metal wire or metal mesh material made from stainless steel, iron, or the like. Specifically, it can be made of knitted wire mesh, plain woven wire mesh, an assembly of crimped woven metal wire, or any of these compressed together by a press.

The filter 80 can also be made of a wound perforated metal plate. In this case, examples of perforated metal plates that can be used include expanded metal, which is made by cutting staggered slits into a metal plate and expanding them to form holes and process them into a mesh-like structure, and hook metal, which is made by drilling holes into a metal plate and flattening the burrs that form around the holes by crushing them.

The housing body 10, in the portion defining the filter chamber S2, has multiple gas outlets 11 arranged circumferentially and axially. These multiple gas outlets 11 are used to guide gas that has passed through the filter 80 to the outside of the housing.

Next, with reference to Figure 1, the operation of the cylinder-shaped gas generator 1 according to this embodiment during operation will be described.

Referring to FIG. 1, when a vehicle equipped with a cylinder-shaped gas generator 1 according to this embodiment collides, the collision is detected by collision detection means separately provided in the vehicle, and based on this, the igniter 40 is activated by current supplied from a control unit separately provided in the vehicle.

When the igniter 40 is activated, the pressure inside the ignition section 42 increases due to the combustion of the ignition charge and/or the transfer charge, causing the squib cup of the ignition section 42 to burst, and the hot particles generated by the combustion of the ignition charge and/or the transfer charge to flow out of the ignition section 42.

The thermal particles flowing out from the ignition section 42 are given directionality by the coil spring 70 described above, allowing them to reach the gas generating agent 60 contained within the combustion chamber S1. Once the thermal particles reach the gas generating agent 60, they combust the gas generating agent 60, generating a large amount of gas within the combustion chamber S1.

As a result, the pressure in the combustion chamber S1 rises, and when the internal pressure of the combustion chamber S1 reaches a predetermined pressure, the portion of the partition member 50 where the score 51a is provided breaks. This creates an opening in the partition member 50 at the portion facing the hollow portion 81 of the filter 80, and the combustion chamber S1 and the filter chamber S2 become connected via this opening.

As a result, gas generated in the combustion chamber S1 flows into the filter chamber S2 through an opening formed in the partition member 50. The gas that flows into the filter chamber S2 flows axially through the hollow portion 81 of the filter 80, then changes direction radially and flows through the interior of the filter 80. During this process, the filter 80 removes heat, cooling the gas, and also removes slag contained in the gas.

After passing through the filter 80, the gas is ejected to the outside of the housing through a gas outlet 11 provided in the housing main body 10. The ejected gas is introduced into the airbag provided adjacent to the cylindrical gas generator 1, causing the airbag to inflate and deploy.

As described above, the cylinder-shaped gas generator 1 according to this embodiment has a holder assembly 20 as part of the housing, and the holder assembly 20 is attached to the open end of the housing main body 10 at the aforementioned one end. Below, the configuration of the holder assembly 20, the fixing structure of the igniter 40 to the holder assembly 20, and the fixing structure of the holder assembly 20 to the housing main body 10 will be described in detail with reference to Figure 2.

As shown in FIG. 2, the holder assembly 20 has a metal holder portion 20A located on the combustion chamber S1 side and a resin connector portion 20B located on the opposite side from the combustion chamber S1. The holder assembly 20 is constructed as an integrated part by previously assembling the holder portion 20A and connector portion 20B to each other, and this is attached to the opening on the above-mentioned one end side of the housing main body 10.

The holder portion 20A is composed of a flat, approximately disk-shaped member with a through-hole extending axially in its center, and includes a cylindrical first body portion 21 and an annular protrusion 22 that protrudes outward from the outer peripheral surface of the first body portion 21.

The holder portion 20A is inserted into the housing body 10 so that its axial direction is parallel to the axial direction of the housing body 10. As a result, the through-hole provided in the holder portion 20A defines part of the hollow opening of the holder assembly 20, and the annular protrusion 22 protrudes from the first body portion 21 in the radial direction of the housing body 10. The annular protrusion 22 is provided at the end of the first body portion 21 on the combustion chamber S1 side.

The holder portion 20A defines the combustion chamber S1 provided inside the housing main body 10 and functions as a pressure bulkhead. Therefore, as described above, the holder portion 20A is constructed from a metal member so that it has sufficient strength to withstand the increase in internal pressure in the combustion chamber S1 when the cylinder-shaped gas generator 1 is activated.

The holder portion 20A also serves as a component for receiving and holding the igniter 40, and has a recessed accommodation portion 23a at its axial end on the combustion chamber S1 side to receive the igniter 40. This accommodation portion 23a is connected to a through-hole provided in the holder portion 20A. A crimping portion 23b is provided at the end of the holder portion 20A on the combustion chamber S1 side, surrounding the accommodation portion 23a. The crimping portion 23b is used to crimp and secure the igniter 40 to the holder portion 20A.

The igniter 40 is fixed to the holder part 20A with its base 41 housed in the housing part 23a of the holder part 20A. Specifically, the base 41 is inserted into the housing part 23a of the holder part 20A and is fastened against the bottom surface of the housing part 23a. In this state, the crimping part 23b on the holder part 20A is bent, thereby fixing the igniter 40 to the holder part 20A. In this way, the igniter 40 is held by the holder part 20A.

A sealing member 29, such as an O-ring, is interposed between the holder portion 20A and the igniter 40, filling the gap between the holder portion 20A and the igniter 40 with the sealing member 29, thereby sealing the gap. Therefore, this configuration ensures airtightness in this area. Note that the method of fixing the igniter 40 is not limited to the method using the crimped portion 23b described above, and other fixing methods may also be used.

The connector portion 20B is composed of a generally cylindrical member having a through-hole extending axially in its center, and includes a cylindrical second body portion 24, a cylindrical portion 25 extending axially from one axial end of the second body portion 24, and a flange portion 26 provided at the other axial end of the second body portion 24.

A portion of the connector portion 20B is inserted into the housing body 10 so that its axial direction is parallel to the axial direction of the housing body 10. More specifically, the connector portion 20B, excluding the flange portion 26, is inserted into the open end of the housing body 10, and the flange portion 26 abuts against the axial end face of the housing body 10 outside the housing body 10. As a result, the through portion provided in the connector portion 20B defines part of the hollow opening of the holder assembly 20, and the tubular portion 25 extends from the second body portion 24 toward the combustion chamber S1.

Here, the holder portion 20A is fixed by being press-fitted into the connector portion 20B. More specifically, the first body portion 21 of the holder portion 20A is press-fitted into the tubular portion 25 of the connector portion 20B, which brings the first body portion 21 and the tubular portion 25 into pressure contact, thereby fixing the holder portion 20A and the connector portion 20B so that they do not easily come apart.

The connector portion 20B is intended to receive a connector that is connected to the terminal pin 43 of the igniter 40. The terminal pin 43 of the igniter 40 is arranged inside this connector portion 20B. The through-hole provided in the connector portion 20B described above forms the portion for receiving this connector.

More specifically, in the cylinder-shaped gas generator 1, the igniter 40 must be electrically connected to an external control unit (not shown) of the vehicle or the like, and this electrical connection is typically made using a harness. A male connector is attached to the end of this harness, and the connector portion 20B must be provided with a female connector that can be connected to this male connector. The penetration portion provided in the connector portion 20B constitutes this female connector.

In addition, by inserting the male connector of the harness into the penetration section, which functions as a female connector, electrical continuity is established between the core wire of the harness and the terminal pin 43, thereby connecting the igniter 40 to a control unit such as a vehicle.

The connector portion 20B also functions as a member that ensures airtightness between the housing main body 10 and the holder portion 20A. The part that ensures airtightness between the housing main body 10 and the holder portion 20A is primarily the cylindrical portion 25 of the connector portion 20B.

Specifically, the cylindrical portion 25 is inserted into the open end of the housing main body 10 and is inserted onto the first body portion 21 of the holder portion 20A. As a result, in the portion of the housing main body 10 where the cylindrical portion 25 is located in the axial direction, the first body portion 21 of the holder portion 20A, the cylindrical portion 25 of the connector portion 20B, and the housing main body 10 are arranged in this order from the radial inside to the radial outside of the housing main body 10. In other words, the first body portion 21 is surrounded by the cylindrical portion 25, and the cylindrical portion 25 is surrounded by the housing main body 10.

The housing main body 10 has a crimped portion 12 that tapers radially inward in the portion corresponding to the cylindrical portion 25 (i.e., the portion covering the cylindrical portion 25). The provision of this crimped portion 12 allows the cylindrical portion 25 of the connector portion 20B, which is made of a resin material, to be sandwiched between the crimped portion 12 of the housing main body 10, which is made of a metal member, and the first body portion 21 of the holder portion 20A, which is also made of a metal member, thereby sealing the gap between the housing main body 10 and the first body portion 21 with the cylindrical portion 25.

When the crimped portion 12 is provided on the housing main body 10, the tubular portion 25 is sandwiched between the housing main body 10 and the first body portion 21, and the tubular portion 25 is subjected to the load, causing compressive deformation. As a result, the tubular portion 25 and the housing main body 10 come into close contact with each other, and the tubular portion 25 and the first body portion 21 also come into close contact with each other.

As a result, the cylindrical portion 25 is interposed between the housing main body 10 and the first body portion 21 while being in close contact with both, thereby sealing the gap described above. Therefore, by configuring it in this way, it is possible to ensure airtightness in that area.

The material of the connector portion 20B is not particularly limited, but suitable materials include nylon-based resins such as nylon 6, nylon 66, and those filled with glass filler, polyacetal (POM) resin, polycarbonate (PC) resin, polyphenylene sulfide (PPS) resin, and polybutylene terephthalate (PBT) resin.

In addition, the holder portion 20A is provided with an annular protrusion 22 at a position closer to the combustion chamber S1 than the first body portion 21. Therefore, the annular protrusion 22 also functions as a stopper that prevents the holder assembly 20 from falling out of the housing main body 10. This function of the annular protrusion 22 as a stopper is exerted not only during manufacture of the cylinder-shaped gas generator 1 and when it is not in operation, but also when it is subjected to pressure associated with an increase in the internal pressure of the combustion chamber S1 during operation.

Here, in the cylinder-shaped gas generator 1 according to this embodiment, the inner diameter R1 of the tubular portion 25 is larger than the inner diameter R2 of the second body portion 24, and the connector portion 20B is provided with an annular stepped surface 27 that connects the inner circumferential surface 24a of the second body portion 24 and the inner circumferential surface 25a of the tubular portion 25. As a result, a first chamber 28a defined by the annular stepped surface 27 and the inner circumferential surface 25a of the tubular portion 25 is provided at the axial end of the connector portion 20B located on the combustion chamber S1 side.

The first body portion 21 of the holder portion 20A is inserted into this first chamber 28a, and the axial end face 21a of the first body portion 21, located on the opposite side from the combustion chamber S1, abuts against the annular step surface 27.

By configuring it in this way, the holder portion 20A and the connector portion 20B can be fixed together by press-fitting the holder portion 20A into the connector portion 20B, as described above, and the holder portion 20A and the connector portion 20B can be positioned accurately along the axial direction of the housing main body 10.

Furthermore, in the cylinder-shaped gas generator 1 according to this embodiment, the inner diameter R2 of the second body 24 is larger than the inner diameter R3 of the first body 21. As a result, a second chamber 28b is provided at the axial end of the holder assembly 20 opposite the combustion chamber S1 side, the second chamber 28b being defined by the axial end surface 21a of the first body 21, which is located opposite the combustion chamber S1 side, and the inner circumferential surface 24a of the second body 24.

This second chamber 28b corresponds to the through-hole provided in the connector portion 20B described above, and constitutes the female connector described above to be provided in the connector portion 20B.

This configuration makes it possible to easily install the female connector described above on the connector portion 20B, further simplifying the configuration of the holder assembly 20.

Figures 4 and 5 are cross-sectional views showing the procedure for assembling the holder assembly in the cylinder-shaped gas generator shown in Figure 1. Next, with reference to Figures 4 and 5, the procedure for assembling the holder assembly 20 in the cylinder-shaped gas generator 1 according to this embodiment will be described.

When assembling the holder assembly 20 to the housing main body 10, first, as shown in Figure 4, the holder portion 20A is prepared with the igniter 40 assembled, and then this is assembled to the connector portion 20B. Specifically, the first body portion 21 of the holder portion 20A is press-fitted into the cylindrical portion 25 of the connector portion 20B, thereby assembling the holder portion 20A with the igniter 40 assembled to the connector portion 20B.

Next, the housing body 10 is fitted onto the holder assembly 20, in which the holder portion 20A is assembled to the connector portion 20B. At this time, the open end of the housing body 10 is fitted onto the holder assembly 20 so as to cover the second body portion of the connector portion 20B, and the axial end face of the housing body 10 is abutted against the flange portion 26 of the connector portion 20B.

At this time, the holder portion 20A may be press-fit into the housing main body 10. That is, the housing main body 10 may be fitted onto the holder assembly 20 so that the circumferential surface of the annular protrusion 22 of the holder portion 20A is in pressure contact with the inner circumferential surface of the housing main body 10. With this configuration, the housing main body 10 and the holder assembly 20 are temporarily fixed by this press-fitting, making subsequent handling easier.

Next, as shown in Figure 5, a crimping process is performed to reduce the diameter of a predetermined position of the housing body 10. More specifically, the portion of the housing body 10 corresponding to the cylindrical portion 25 of the connector portion 20B is reduced in diameter radially inward (i.e., in the direction of arrow A in the figure), thereby forming a crimped portion 12 on the housing body 10.

As a result, the tubular portion 25 of the connector portion 20B is sandwiched between the crimping portion 12 of the housing main body 10 and the first body portion 21 of the holder portion 20A, and the tubular portion 25 seals the gap between the housing main body 10 and the first body portion 21.

By going through the above-described series of steps, the assembly of the holder assembly 20 to the housing main body 10 is completed, and the open end on the aforementioned one end side of the housing main body 10 is closed by the holder assembly 20.

By configuring the cylinder-shaped gas generator according to the present embodiment as described above, the gap between the housing body 10 and the holder assembly 20 can be sealed by the cylindrical portion 25 of the resin connector portion 20B, which is part of the holder assembly 20. This eliminates the need to use a separate sealing member such as an O-ring to seal this portion, reducing component costs and significantly simplifying assembly.

Furthermore, by constructing the holder, which was previously constructed from a single metal part, as a composite part consisting of a metal holder portion 20A and a resin connector portion 20B, the amount of metal material used can be dramatically reduced, resulting in a significant weight reduction. In addition, the high-precision machining required when constructing a holder from a single metal part is no longer necessary, and the holder configuration is greatly simplified, which also makes it possible to reduce material and processing costs.

Therefore, by using the cylinder-shaped gas generator 1 according to this embodiment, manufacturing costs can be reduced and the weight can be reduced compared to conventional devices.

Figure 6 is a cross-sectional view of a holder assembly for a cylinder-shaped gas generator according to first to fourth modified examples based on the embodiment described above. Below, holder assembly 20 for cylinder-shaped gas generators 1A to 1D according to first to fourth modified examples will be described with reference to Figure 6.

The holder assembly 20 of the cylinder-shaped gas generator 1A according to the first modified example shown in Figure 6 (A) differs from the embodiment described above only in the shape of the first barrel portion 21 of the holder portion 20A.

Specifically, in the holder assembly 20 according to the first modification, the outer peripheral surface 21b of the first body 21 has an inclined shape that narrows in diameter toward the combustion chamber S1 side (i.e., the side opposite the connector portion 20B). Therefore, before the holder assembly 20 is assembled to the housing main body 10, a gap is formed between the cylindrical portion 25 of the connector portion 20B and the first body 21 of the holder portion 20A.

With this configuration, when the crimped portion 12 is provided on the housing body 10, the tubular portion 25 of the connector portion 20B is subjected to a load and compressively deformed while tilting radially inward of the housing body 10. At this time, the load applied to the first body portion 21 of the holder portion 20A by the crimped portion 12 provided on the housing body 10 acts toward the side where the terminal pin 43 of the igniter 40 is located.

Therefore, when this configuration is adopted, the fixing force of the crimping portion 12 is applied more firmly to the holder portion 20A, and in addition to the effects described in the above embodiment, it is possible to obtain the effect of more reliably preventing the holder assembly 20 from falling out of the housing main body 10.

The holder assemblies 20 of cylinder-shaped gas generators 1B to 1D according to second to fourth modified examples shown in Figures 6(B) to 6(D) differ from the above-described embodiment only in the shape of the cylindrical portion 25 of the connector portion 20B.

Specifically, in the holder assemblies 20 according to the second to fourth variants, a recessed portion is pre-formed on the outer peripheral surface of the cylindrical portion 25 at a position corresponding to the crimped portion 12 provided on the housing main body 10.

Here, in the holder assembly 20 according to the second modified example shown in FIG. 6(B), the concave portion is configured to have a C-shaped cross section. In the holder assembly 20 according to the third modified example shown in FIG. 6(C), the thin-walled portion formed in the tubular portion 25 by providing the concave portion is configured to extend from a position corresponding to the crimped portion 12 provided on the housing main body 10 toward the combustion chamber S1 side (i.e., the side opposite the flange portion 26 of the connector portion 20B). In the holder assembly 20 according to the fourth modified example shown in FIG. 6(D), the thin-walled portion formed in the tubular portion 25 by providing the concave portion is configured to extend from a position corresponding to the crimped portion 12 provided on the housing main body 10 toward the side opposite the combustion chamber S1 side (i.e., the side opposite the flange portion 26 of the connector portion 20B).

With this configuration, when the crimped portion 12 is provided on the housing main body 10, the adhesion between the crimped portion 12 of the housing main body 10 and the tubular portion 25 of the connector portion 20B is improved.

Therefore, when this configuration is adopted, in addition to the effects described in the above embodiment, it is possible to improve the sealing performance between the housing main body 10 and the first body portion 21.

The characteristic configurations shown in the above-described embodiments of the present invention and their variations can naturally be combined with each other within the scope of the spirit of the present invention.

In addition, in the above-described embodiment and its modifications of the present invention, the present invention has been described as being applied to a cylindrical gas generator incorporated into a side airbag device, but the application of the present invention is not limited to this. It can also be applied to cylindrical gas generators incorporated into curtain airbag devices, knee airbag devices, seat cushion airbag devices, etc., as well as so-called T-shaped gas generators that have an elongated outer shape similar to a cylindrical gas generator.

As such, the above-described embodiments and their variations disclosed herein are illustrative in all respects and are not limiting. The technical scope of the present invention is defined by the claims, and includes all modifications that are equivalent in meaning to and within the scope of the claims.

1, 1A to 1D: Cylinder-shaped gas generator, 10: Housing body, 11: Gas outlet, 12, 13: Crimping portion, 20: Holder assembly, 20A: Holder portion, 20B: Connector portion, 21: First barrel portion, 21a: Axial end face, 21b: Outer circumferential surface, 22: Annular protrusion portion, 23a: Storage portion, 23b: Crimping portion, 24: Second barrel portion, 24a: Inner circumferential surface, 25: Cylindrical portion, 25a: Inner circumferential surface, 26: Flange portion, 27: Annular stepped surface, 28a: First chamber, 28b: Second chamber, 29: Sealing member, 30: Closing member, 31: Closing portion, 32: Side wall portion, 33: Annular recess, 40: Igniter, 41: Base portion, 42: Ignition portion, 43: Terminal pin, 50: Partition member, 51: Partition portion, 51a: Score, 52 Annular wall portion, 60 gas generating agent, 70 coil spring, 71 spring portion, 72 pressing portion, 80 filter, 81 hollow portion, 90 welded portion, S1 combustion chamber, S2 filter chamber.

Claims (6)

a cylindrical housing body including a combustion chamber in which a gas generating agent is accommodated;
a holder attached to an axial opening end of the housing body;
an igniter having an ignition unit including a squib cup loaded with an ignition charge and a terminal pin connected to the ignition unit, the ignition unit being held by the holder in a state where the ignition unit is located on the combustion chamber side and the terminal pin is located on the opposite side from the combustion chamber side;
a restricting means for restricting the degree of opening of the squib cup when the squib cup is torn open upon activation of the igniter,
a restricting means configured by a coil spring housed in the combustion chamber, one end of which abuts against the holder and/or the igniter and the other end of which abuts against the gas generating agent, and which surrounds the ignition portion at the end on the holder side; A gas generator as described in claim 1, wherein the end of the coil spring on the holder side is in contact with the ignition part or is positioned close to the ignition part with a predetermined clearance. The coil spring in the portion surrounding the ignition part is cylindrical,
2. The gas generator according to claim 1, wherein the coil spring has a diameter that increases with increasing distance from the ignition portion along the axial direction of the housing body. The gas generator according to claim 1, wherein the coil spring elastically biases the gas generating agent in a direction opposite to the igniter side. The gas generator according to claim 4, wherein the other end of the coil spring is provided with a pressing portion that presses against the gas generating agent. The housing body is made of metal,
the holder includes a through-hole-shaped hollow opening extending in a direction parallel to the axial direction of the housing body, and is assembled to the open end of the housing body by being inserted into the open end,
the igniter is at least partially disposed within the hollow opening;
the holder comprises a holder assembly including: a metal holder portion located on the combustion chamber side and configured to receive and hold the igniter; and a resin connector portion located on the opposite side from the combustion chamber side and configured to receive a connector to be connected to the terminal pin,
the holder portion includes a cylindrical first body portion that defines the hollow opening, and an annular protrusion that protrudes from the first body portion along a radial direction of the housing main body,
the connector portion includes a cylindrical second body portion that defines the hollow opening, and a cylindrical portion that extends from the second body portion toward the combustion chamber,
the cylindrical portion is inserted into the open end of the housing body and is inserted around the first body portion at a portion thereof located on the opposite side from the combustion chamber side as viewed from the annular protrusion,
6. The gas generator according to claim 1, wherein a portion of the housing body corresponding to the cylindrical portion is tapered radially inward, whereby the cylindrical portion is sandwiched and compressed by the housing body at the tapered portion and the first barrel portion, whereby a gap between the housing body and the first barrel portion is sealed by the cylindrical portion.