Patent Description:
A known widely-used gas generator fills a gas generating agent in a combustion chamber formed in a housing, burns the gas generating agent by an igniter to generate combustion gas, and discharges the combustion gas to the exterior from a gas discharge port provided in the housing. Further, to cool the generated combustion gas and trap residues in such a gas generator, a cylindrical filter molded article is typically included.

In relation to this, a filter molded article for improving cooling performance and filtering performance of combustion gas has also been proposed (see Patent Documents <NUM> and <NUM>, and the like, for example). For example, Patent Document <NUM> discloses a filter for a gas generator that has a substantially cylindrical hollow shape and is formed of a winding body of a metal wire. The metal wire is formed of a long member in which a cross-sectional shape orthogonal to an extending direction of the metal wire is a V shape. A V-shaped groove defined by the metal wire is directed to a hollow portion side of the filter for the gas generator. Further, Patent Document <NUM> discloses a molded article for a filter in which one or a plurality of metal wires are combined and a radial protruding portion is formed on a surface of the metal wire.

However, in a tubular filter molded article, it is typically necessary to prevent a metal wire from being unwound by sintering the metal wire after the metal wire is wound around a core material. Further, when a gas generator is manufactured, the filter molded article is sandwiched between a top plate and a bottom plate of a housing and assembled in the housing in a compressed state. Thus, when shape retention (rigidity) of the filter molded article is insufficient, wires forming the filter molded article may be unwound.

In contrast, the filter for the gas generator described in Patent Document <NUM> has a small contact area between wires overlapping each other in a radial direction of a filter molded article. Thus, sintering force between the wires forming the filter molded article may be reduced, and shape retention (rigidity) of the filter molded article may become insufficient. Further, in the filter for the gas generator described in Patent Document <NUM>, it is necessary to roll a metal element wire having a circular cross-section into a bent plate shape having a V-shaped cross-section in course of manufacture of the filter, and thus it cannot be said that manufacturing is easy.

In the filter for a gas generator described in Patent Document <NUM>, a plurality of the protruding portions radially protrude on the surface of the metal wire. Thus, a contact area is less likely to be ensured due to contact between the protruding portions of the metal wire overlapping each other in a radial direction of the filter for the gas generator, and sintering force between the wires may become insufficient.

A technology of the present disclosure has been made in view of the above-described circumstances, and an object of the present disclosure is to provide a technology related to a filter molded article for a gas generator having excellent combustion gas filtering and cooling effects and also having more excellent shape retention and manufacturing ease than found in the related art.

To solve the above problem, the technology according to the present disclosure adopts the following configuration. In other words, the technology according to the present disclosure is a filter molded article for a gas generator that is housed in an outer shell container of the gas generator, and the filter molded article includes: a peripheral wall portion that is formed of a winding body of a filter wire and has a cylindrical hollow shape, the filter wire including a groove portion that is formed in one place in a circumferential direction of a metal wire having a circular or elliptical transverse cross-section and that extends along an extending direction of the metal wire, and including a circumferential surface formed in a portion other than the groove portion; a gas inflow surface that is formed of one surface from among an inner peripheral surface of the peripheral wall portion and an outer peripheral surface of the peripheral wall portion, and that is through which gas flows into the peripheral wall portion; and a gas outflow surface that is formed of the other surface from among the inner peripheral surface of the peripheral wall portion and the outer peripheral surface of the peripheral wall portion, and that is through which gas flows from the peripheral wall portion, wherein the groove portion is oriented opening toward the gas inflow surface in the peripheral wall portion.

In the filter molded article for the gas generator having the structure described above, combustion gas flows from the gas inflow surface into the peripheral wall portion, and flows from the gas outflow surface to the outside of the peripheral wall portion. Here, in the filter wire forming the peripheral wall portion, the groove portion is aligned opening toward the gas inflow surface side of the peripheral wall portion. Thus, a contact area in which the combustion gas is in contact with a surface of the filter wire in course of passing the combustion gas through the peripheral wall portion can be increased. Since the groove portion is oriented toward the gas inflow surface side of the peripheral wall portion as described above, the combustion gas that flows from the gas inflow surface can be smoothly guided to the groove portion of the filter wire. In this way, the combustion gas can pass through the peripheral wall portion of the filter molded article while repeatedly colliding with a recessed wall surface forming the groove portion of the filter wire. As a result, a combustion gas filtering effect and cooling effect by the filter molded article can be improved.

Further, the filter molded article according to the present disclosure includes the groove portion formed in one place in the circumferential direction of the filter wire, and includes the remaining region in the circumferential direction formed as the circumferential surface. Thus, a contact area of wire portions overlapping each other by winding the filter wire can be easily ensured. In this way, even when external force is applied to the peripheral wall portion of the filter molded article formed of the winding body of the filter wire, the filter wire is less likely to be unwound, and an occurrence of a loss of shape can be suppressed. Further, when the filter wire is manufactured, the groove portion may be formed in only one place in the circumferential direction of the metal wire, and thus the manufacturing of the filter wire is easy. As a result, the filter molded article having excellent shape retention (rigidity) and manufacturing ease can be provided.

Here, the groove portion may continuously extend from one end to an other end in an extending direction of the filter wire.

Further, the inner peripheral surface of the peripheral wall portion may be formed as the gas inflow surface, and the outer peripheral surface may be formed as the gas outflow surface, and the groove portion may be oriented inward in a radial direction of the peripheral wall portion.

Further, a groove edge portion located at a boundary portion between the circumferential surface and the groove portion may have a curved shape in a transverse cross-section of the filter wire.

Further, wire portions of the filter wire that are stacked in the radial direction of the peripheral wall portion may be sintered with each other.

Further, the technology of the present disclosure can also be determined as a gas generator including: an outer shell container; and the filter molded article according to any of the descriptions above housed in the outer shell container.

The present disclosure can provide a technology related to a filter molded article for a gas generator having excellent combustion gas filtering and cooling effects and also having more excellent shape retention and manufacturing ease than found in the related art.

A filter molded article and a gas generator including the filter molded article according to an embodiment of the present disclosure will be described below with reference to the drawings. Note that each of the configurations, combinations thereof, and the like in each embodiment is an example, and various additions to the configuration, omissions, substitutions, and other changes may be made as appropriate without departing from the spirit of the present invention. The present disclosure is not limited by the embodiments and is limited only by the claims.

<FIG> is a diagram schematically illustrating an internal structure taken along a center axis X of a gas generator <NUM> according to a first embodiment. Hereinafter, a cross-section taken along the center axis X of the gas generator <NUM> as illustrated in <FIG> may be referred to as a "longitudinal cross-section" of the gas generator <NUM>. Further, a direction along the center axis X of the gas generator <NUM> may be referred to as an "top-and-bottoom direction" of the gas generator <NUM>. Further, <FIG> illustrates a state of the gas generator <NUM> before actuation. Further, the gas generator <NUM> is, for example, an airbag gas generator for supplying an airbag with gas for expanding and inflating the airbag.

The gas generator <NUM> is configured to burn a gas generating agent <NUM> filling a housing <NUM> formed of an upper shell <NUM> and a lower shell <NUM>, and to discharge combustion gas. The housing <NUM> is an example of an outer shell container of the gas generator <NUM>. The upper shell <NUM> in the housing <NUM> includes an upper peripheral wall portion <NUM> having a cylindrical shape, and a top plate portion <NUM> that closes an upper end of the upper peripheral wall portion <NUM>. In the upper shell <NUM>, the top plate portion <NUM> has a substantially circular shape in a plan view, and a lower end portion of the upper peripheral wall portion <NUM> is formed as an open end. Further, a joining portion <NUM> extending outward in a radial direction in a flange shape is connected to the lower end portion of the upper peripheral wall portion <NUM> in the upper shell <NUM>.

The lower shell <NUM> in the housing <NUM> includes a lower peripheral wall portion <NUM> having a cylindrical shape, and a bottom plate portion <NUM> that closes a lower end of the lower peripheral wall portion <NUM> and to which an igniter <NUM> is fixed. In the lower shell <NUM>, the bottom plate portion <NUM> has a substantially circular shape in the plan view, and an upper end portion of the lower peripheral wall portion <NUM> is formed as an open end. Further, a joining portion <NUM> extending outward in the radial direction in a flange shape is connected to the upper end portion of the lower peripheral wall portion <NUM>. Note that a known igniter can be used as the igniter <NUM>.

As illustrated in <FIG>, the lower peripheral wall portion <NUM> of the lower shell <NUM> is formed of a first tubular wall portion <NUM>, a second tubular wall portion <NUM>, and a connecting wall portion <NUM> that connects the first tubular wall portion <NUM> and the second tubular wall portion <NUM>. The first tubular wall portion <NUM> is a tubular portion including the upper end portion of the lower peripheral wall portion <NUM> and is formed to have substantially the same diameter as the upper peripheral wall portion <NUM>. The second tubular wall portion <NUM> is a tubular portion including a lower end portion of the lower peripheral wall portion <NUM>, and has a diameter smaller than that of the first tubular wall portion <NUM>. The connecting wall portion <NUM> is a portion that has an annular shape and connects a lower end portion of the first tubular wall portion <NUM> and an upper end portion of the second tubular wall portion <NUM>. The joining portion <NUM> of the upper shell <NUM> and the joining portion <NUM> of the lower shell <NUM> formed as described above are joined by laser welding or the like while overlapping each other as illustrated in <FIG>. In this way, the housing <NUM> having a cylindrical shape with both ends in an axial direction (top-and-bottom direction) closed is formed. However, a shape of the upper shell <NUM> and the lower shell <NUM> in the housing <NUM> is not limited to an aspect illustrated <FIG>.

Further, as illustrated in <FIG>, the igniter <NUM> is disposed in an internal space of the housing <NUM>. More specifically, an attachment hole 32a for fixing the igniter <NUM> is formed in a center portion in the bottom plate portion <NUM> of the lower shell <NUM>, and the igniter <NUM> is fixed to the bottom plate portion <NUM> via a resin in a state where the igniter <NUM> is inserted into the lower shell <NUM> from the attachment hole 32a.

Further, as illustrated in <FIG>, an inner tubular member <NUM> is provided inside the housing <NUM>. The inner tubular member <NUM> is fixed to the bottom plate portion <NUM> of the lower shell <NUM>. Further, the inner tubular member <NUM> has a cup shape, and a housing portion <NUM> that houses a known transfer charge <NUM> therein is formed. As illustrated in <FIG>, the igniter <NUM> is disposed and faces the housing portion <NUM> formed inside the inner tubular member <NUM>. Further, a combustion chamber <NUM> that houses the gas generating agent <NUM> is formed around the inner tubular member <NUM>. Furthermore, the inner tubular member <NUM> is provided with a communication hole <NUM> that communicates the housing portion <NUM> that houses the transfer charge <NUM> and the combustion chamber <NUM>. Note that the communication hole <NUM> in the inner tubular member <NUM> is closed by an appropriate sealing tape or the like, and the housing portion <NUM> of the inner tubular member <NUM> and the combustion chamber <NUM> may be isolated from each other before the gas generator <NUM> is actuated.

Further, as illustrated in <FIG>, a gas discharge port <NUM> for discharging the combustion gas generated by combustion of the gas generating agent <NUM> to the outside is provided in the upper peripheral wall portion <NUM> in the upper shell <NUM>. An installation aspect such as a number, a position, and a size of the gas discharge port <NUM> is not particularly limited, but a plurality of the gas discharge ports <NUM> may be arranged along a circumferential direction of the upper peripheral wall portion <NUM>, for example. Further, the gas discharge port <NUM> is closed by a sealing tape <NUM>, and is configured to suppress entry of moisture from the outside into the housing <NUM> before the gas generator <NUM> is actuated.

Furthermore, the gas generator <NUM> includes a filter molded article <NUM> housed in the housing <NUM>. The filter molded article <NUM> is disposed between the combustion chamber <NUM> inside the housing <NUM> and the gas discharge port <NUM>. The filter molded article <NUM> is a member for cooling the combustion gas generated by the combustion of the gas generating agent <NUM> when the gas generator <NUM> is actuated, and filtering and cooling the combustion gas by trapping combustion residue contained in the combustion gas.

The filter molded article <NUM> in the present embodiment includes a peripheral wall portion <NUM> molded into a cylindrical shape by winding a metal filter wire into multiple layers. A reference sign <NUM> illustrated in <FIG> indicates an outer peripheral surface of the peripheral wall portion <NUM>, and a reference sign <NUM> indicates an inner peripheral surface of the peripheral wall portion <NUM>. The peripheral wall portion <NUM> of the filter molded article <NUM> has an outer diameter smaller than an inner diameter of the first tubular wall portion <NUM> of the lower shell <NUM> and the upper peripheral wall portion <NUM> of the upper shell <NUM>, and an annular (doughnut-shaped) gap portion S1 is formed between the first tubular wall portion <NUM> of the lower shell <NUM> and the upper peripheral wall portion <NUM> of the upper shell <NUM>, and the peripheral wall portion <NUM>. In other words, in the example illustrated in <FIG>, the outer peripheral surface <NUM> of the peripheral wall portion <NUM> in the filter molded article <NUM> is disposed and faces the first tubular wall portion <NUM> of the lower shell <NUM> and the upper peripheral wall portion <NUM> of the upper shell <NUM> across the gap portion S1. Further, a part of the combustion chamber <NUM> is disposed in a hollow portion formed inside the peripheral wall portion <NUM>, and thus the inner peripheral surface <NUM> of the peripheral wall portion <NUM> is disposed and faces the combustion chamber <NUM>. In the filter molded article <NUM> disposed inside the housing <NUM> as described above, the inner peripheral surface <NUM> of the peripheral wall portion <NUM> functions as a gas inflow surface P1 through which gas flows into the peripheral wall portion <NUM>, and the outer peripheral surface <NUM> functions as a gas outflow surface P2 through which the gas flows from the peripheral wall portion <NUM>. Further, the filter molded article <NUM> is assembled in the housing <NUM> in a state where a lower end surface <NUM> and an upper end surface <NUM> of the peripheral wall portion <NUM> are respectively in contact with the connecting wall portion <NUM> of the lower shell <NUM> and the top plate portion <NUM> of the upper shell <NUM> and are compressed in the axial direction (top-and-bottom direction) of the peripheral wall portion <NUM>.

The gas generator <NUM> formed as described above burns the transfer charge <NUM> housed in the housing portion <NUM> of the inner tubular member <NUM> by the igniter <NUM> being actuated when the airbag is required to expand and inflate as in a vehicle collision or the like, for example. For example, the igniter <NUM> may be configured to house an ignition charge inside a housing cup, burn the ignition charge during actuation, and thus discharge flame, high-temperature gas, or the like being a combustion product of the ignition charge to the outside of the housing cup. In this way, the transfer charge <NUM> in the housing portion <NUM> ignites, and the combustion gas of the transfer charge <NUM> breaks the seal tape closing the communication hole <NUM> of the inner tubular member <NUM>, and is discharged from the communication hole <NUM> to the combustion chamber <NUM>. As a result, the combustion gas of the transfer charge <NUM> comes into contact with the gas generating agent <NUM> housed in the combustion chamber <NUM>, and the gas generating agent <NUM> burns, thereby generating the combustion gas having high temperature and high pressure in the combustion chamber <NUM>.

Then, the combustion gas generated in the combustion chamber <NUM> as described above flows from the inner peripheral surface <NUM> (gas inflow surface P1) of the filter molded article <NUM> into the peripheral wall portion <NUM> and is cooled when passing through the peripheral wall portion <NUM> outward in the radial direction, and the combustion residue is trapped. The combustion gas passing through the peripheral wall portion <NUM> in such a manner flows from the outer peripheral surface <NUM> (gas outflow surface P2) to the gap portion S1, then breaks the sealing tape <NUM> closing the gas discharge port <NUM> by pressure of the combustion gas, and is discharged from the gas discharge port <NUM> to the outside of the housing <NUM>. The combustion gas discharged from the gas discharge port <NUM> of the housing <NUM> in such a manner is supplied to the airbag via an appropriate supply pipe or the like (not illustrated), and can thus expand and inflate the airbag.

Next, a detailed structure of the filter molded article <NUM> according to the present embodiment will be described. <FIG> is a top view of the filter molded article <NUM> according to the first embodiment. A reference sign <NUM> indicates a filter wire forming the peripheral wall portion <NUM> of the filter molded article <NUM>. The peripheral wall portion <NUM> of the filter molded article <NUM> is formed as a substantially cylindrical hollow winding body manufactured by winding the filter wire <NUM> along a circumferential direction of the peripheral wall portion <NUM> into multiple layers. Note that the number of times that the filter wire <NUM> forming the peripheral wall portion <NUM> is wound around is not particularly limited.

The peripheral wall portion <NUM> of the filter molded article <NUM> includes a hollow portion 11A extending along a center axis X1 direction (hereinafter, also simply referred to as an "axial direction") of the filter molded article <NUM> illustrated in <FIG>, and the hollow portion 11A forms at least a part of the combustion chamber <NUM> that houses the gas generating agent <NUM>. Note that the filter molded article <NUM> is disposed in the housing <NUM>, and the center axis X1 of the filter molded article <NUM> is coaxial with the center axis X of the gas generator <NUM>.

The filter wire <NUM> forming the peripheral wall portion <NUM> of the filter molded article <NUM> is wound layered along the circumferential direction of the filter molded article <NUM> (peripheral wall portion <NUM>). In this way, the peripheral wall portion <NUM> has a structure in which the filter wire <NUM> is stacked in a multilayer shape along the radial direction of the peripheral wall portion <NUM>. For example, the filter wire <NUM> is wound in an oblique direction and extends crossing both the circumferential direction and the axial direction of the peripheral wall portion <NUM> of the filter molded article <NUM>, with a winding direction of the filter wire <NUM> turning at one end portion (upper end portion) in the axial direction and an other end portion (lower end portion) in the axial direction, whereby the filter wire <NUM> has a mesh shape. However, the aspect of winding the filter wire <NUM> is not limited to the aspect described above. Further, the peripheral wall portion <NUM> of the filter molded article <NUM> may be formed of one filter wire <NUM>, or may be formed of a plurality of the filter wires <NUM>.

Here, <FIG> is a diagram illustrating a transverse cross-section of the filter wire <NUM> according to the first embodiment. Note that the transverse cross-section of the filter wire <NUM> is a cross-section in a direction orthogonal to a center axis X2 in which the filter wire <NUM> extends. The filter wire <NUM> is formed by processing a metal wire <NUM> having a circular or elliptical transverse cross-section. A material of the metal wire <NUM> forming the filter wire <NUM> is not particularly limited, but examples include copper plated steel, stainless steel, steel, a nickel alloy, iron, and the like.

The filter wire <NUM> illustrated in <FIG> includes a groove portion <NUM> formed in one place in a circumferential direction of the metal wire <NUM> having a circular transverse cross-section, and has a cross-sectional structure in which a circumferential surface <NUM> is formed in a remainder in the circumferential direction, that is, in a portion other than the groove portion <NUM>. An outer surface of the filter wire <NUM> in the present embodiment is formed of a recessed wall surface <NUM> forming the groove portion <NUM>, and the circumferential surface <NUM>. The circumferential surface <NUM> of the filter wire <NUM> is, for example, a portion in which a circular or elliptical original shape of the metal wire <NUM> forming the filter wire <NUM> is maintained whole. On the other hand, the groove portion <NUM> of the filter wire <NUM> is a recessed portion that opens to a surface of the metal wire <NUM> and extends in a groove shape along an extending direction (center axis X2 direction) of the metal wire <NUM>. The filter wire <NUM> illustrated in <FIG> is the metal wire <NUM> of which an original shape is a circular transverse cross-section, and has a cross-sectional shape in which one place in the circumferential direction of the metal wire <NUM> is notched by the groove portion <NUM>, which has a V shape. However, a position, a shape, a size, and the like of the groove portion <NUM> illustrated in <FIG> are not particularly limited.

Further, the filter wire <NUM> in the present embodiment may include the groove portion <NUM> formed in one place in a circumferential direction of a metal wire having an elliptical transverse cross-section, and may include the circumferential surface <NUM> formed in a portion other than the groove portion <NUM> in the circumferential direction of the metal wire. As described above, the filter wire <NUM> in the present embodiment has a configuration in which the groove portion <NUM> formed in one place in the circumferential direction of the metal wire <NUM> having the circular or elliptical cross-section extends along the extending direction of the metal wire <NUM>, and the circumferential surface <NUM> is formed in the portion other than the groove portion <NUM>.

A method for manufacturing the filter wire <NUM> forming the filter molded article <NUM> is not particularly limited, but the filter wire <NUM> may be manufactured by preparing the metal wire <NUM> having the circular or elliptical transverse cross-section, and pressing a die member against the metal wire <NUM> to form the groove portion <NUM> along the extending direction of the metal wire <NUM>, for example. <FIG> are diagrams illustrating an example of the method for manufacturing the filter wire <NUM> according to the first embodiment. In the manufacturing of the filter wire <NUM>, first, the metal wire <NUM> before processing and a molding die <NUM> are prepared as illustrated in <FIG>. Here, an example of manufacturing the filter wire <NUM> by processing the metal wire <NUM> having the circular transverse cross-section will be described. The molding die <NUM> illustrated in <FIG> is divided into two members of a first die member 40A and a second die member 40B.

A first circumferential curved surface portion 41A formed as an arc-shaped curved surface is provided in the first die member 40A. On the other hand, a second circumferential curved surface portion 41B formed as an arc-shaped curved surface having the same radius of curvature as that of the first circumferential curved surface portion 41A, and a groove forming protrusion portion <NUM> are provided in the second die member 40B. The groove forming protrusion portion <NUM> is a protrusion for forming the groove portion <NUM> in the filter wire <NUM>, and has a shape corresponding to the groove portion <NUM>. Here, an example of manufacturing the filter wire <NUM> including the groove portion <NUM> having a V shape as illustrated in <FIG> is described, and thus the groove forming protrusion portion <NUM> is also formed having the V shape in the second die member 40B illustrated in <FIG>.

<FIG> is a front view of a state where the first die member 40A and the second die member 40B are combined. In the front view of the state where the first die member 40A and the second die member 40B are combined, a shape of a hole <NUM> formed in a region surrounded by the first circumferential curved surface portion 41A, the second circumferential curved surface portion 41B, and the groove forming protrusion portion <NUM> is the same shape as the transverse cross-section of the filter wire <NUM> illustrated in <FIG>.

Here, the groove forming protrusion portion <NUM> of the second die member 40B is pressed into the surface of the metal wire <NUM> by an appropriate mechanical means, and the first die member 40A and the second die member 40B are combined as illustrated in <FIG>. From this state, for example, the metal wire <NUM> is pulled out in a direction of an arrow A illustrated in <FIG> while the molding die <NUM> including the combination of the first die member 40A and the second die member 40B is fixed. As a result, the groove portion <NUM> having the same shape as that of the groove forming protrusion portion <NUM> of the second die member 40B is formed in the surface of the metal wire <NUM> along the extending direction (axial direction) of the metal wire <NUM>. By processing the metal wire <NUM> in such a manner, the filter wire <NUM> including the groove portion <NUM> in one place in the circumferential direction as illustrated in <FIG> can be manufactured. Note that, in <FIG>, instead of pulling out the metal wire <NUM> in one direction while the molding die <NUM> is fixed, the molding die <NUM> may be moved along the extending direction (axial direction) of the metal wire <NUM> while the metal wire <NUM> is fixed. With such a technique, the filter wire <NUM> in the present embodiment can also be suitably manufactured.

When the filter wire <NUM> manufactured as described above is wound, for example, one end of the filter wire <NUM> is fixed to a predetermined position of a core material <NUM> having a columnar shape as illustrated in <FIG>, and the core material <NUM> is rotated along a rotating shaft B in this state, and thus the filter wire <NUM> is wound around an outer peripheral surface 50A of the core material <NUM> while being supplied to the core material <NUM> along an arrow C direction. At this time, the filter wire <NUM> may be wound oblique to the core material <NUM> by reciprocating, along an arrow D direction illustrated in <FIG>, a position of the filter wire <NUM> supplied to the core material <NUM> with respect to a rotating shaft B direction of the core material <NUM>. Furthermore, in the present embodiment, when the filter wire <NUM> is wound around the core material <NUM>, the filter wire <NUM> is supplied to the core material <NUM> with the groove portion <NUM> of the filter wire <NUM> facing the outer peripheral surface 50A side of the core material <NUM>. In this way, the filter wire <NUM> can be wound in a state where the groove portion <NUM> of the filter wire <NUM> is aligned facing the outer peripheral surface 50A side of the core material <NUM>. After the winding of the filter wire <NUM> around the core material <NUM> ends, the filter wire <NUM> is cut, and the core material <NUM> is removed from the obtained cylindrical winding body. The winding body manufactured in such a manner may be then subjected to heat treatment for sintering, and wire portions overlapping each other on the filter wire <NUM> may be heated to be integral.

The filter molded article <NUM> obtained as described above includes the groove portion <NUM> formed in one place in the circumferential direction of the metal wire <NUM> having the circular or elliptical transverse cross-section, with the groove portion <NUM> extending along the extending direction of the metal wire <NUM>. Furthermore, the filter molded article <NUM> includes the circumferential surface <NUM> formed in the portion other than the groove portion <NUM>. Then, the filter molded article <NUM> is assembled in the housing <NUM> in a state where the lower end surface <NUM> and the upper end surface <NUM> of the peripheral wall portion <NUM> are respectively in contact with the connecting wall portion <NUM> of the lower shell <NUM> and the top plate portion <NUM> of the upper shell <NUM>, and the whole filter molded article <NUM> is compressed in the axial direction (top-and-bottom direction) as described above.

Here, <FIG> is a diagram schematically illustrating a relationship between an opening direction of the groove portion <NUM> in the filter wire <NUM> forming the filter molded article <NUM> according to the first embodiment, and a flow direction G of the combustion gas that passes through the peripheral wall portion <NUM>. As illustrated in <FIG>, the groove portion <NUM> extending along the extending direction of the filter wire <NUM> is oriented opening toward the gas inflow surface P1 (in the present embodiment, the inner peripheral surface <NUM>) side of the peripheral wall portion <NUM>. Further, in the present embodiment, the groove portion <NUM> in the filter wire <NUM> forming the filter molded article <NUM> (peripheral wall portion <NUM>) continuously extends from one end to an other end in the extending direction of the filter wire <NUM>. Note that, for the sake of illustration, <FIG> illustrates a situation where the filter wire <NUM> forming the peripheral wall portion <NUM> is wound around three times, but the number of times that the filter wire <NUM> is actually wound around is not particularly limited.

According to the filter molded article <NUM> formed as described above, the groove portion <NUM> is aligned facing toward the gas inflow surface P1 (inner peripheral surface <NUM>) side of the peripheral wall portion <NUM>. In this way, in a gas path in which the combustion gas flows from the gas inflow surface P1 (inner peripheral surface <NUM>) into the peripheral wall portion <NUM> and flows from the gas outflow surface P2 (outer peripheral surface <NUM>), a contact area in which the combustion gas is in contact with a surface of the filter wire <NUM> can be further increased than that in a filter molded article manufactured by using a filter wire having a smooth surface (without the groove <NUM> being formed). Further, since each groove portion <NUM> of the filter wire <NUM> is aligned opening toward the gas inflow surface P1 (inner peripheral surface <NUM>) side, the filter molded article <NUM> can smoothly guide, to the groove portion <NUM> of the filter wire <NUM>, the combustion gas that flows from the gas inflow surface P1 (inner peripheral surface <NUM>) into the peripheral wall portion <NUM>. In this way, the combustion gas can pass through the peripheral wall portion <NUM> while repeatedly colliding with the recessed wall surface <NUM> (see <FIG>) forming the groove portion <NUM> of the filter wire <NUM>. As a result, by efficiently trapping the combustion residue contained in the combustion gas, a filtering effect can be improved, and a cooling effect of the combustion gas can be improved.

Here, the groove portion <NUM> of the filter wire <NUM> is formed in a recessed shape being recessed from the circumferential surface <NUM> to the center axis side of the filter wire <NUM>, but a proportion of the circumferential surface <NUM> in the entire peripheral surface (circumferential direction) of the filter wire <NUM> is great. Thus, when the filter wire <NUM> is wound, a contact area in which overlapping wire portions are in contact with each other is increased. Then, the circumferential surface <NUM> of the filter wire <NUM> contributes to ensuring of an area (hereinafter, referred to as a "sintering area") in which the overlapping wire portions are sintered with each other in the filter wire <NUM>. On the other hand, for example, in the case of a bent flat plate shape as in the filter wire disclosed in Patent Document <NUM>, edge portions in a transverse cross-section of the filter wire tend to be in a line contact or a point contact. As a result, there is a concern that the contact area of overlapping wire portions is small. Further, when a plurality of protrusions (protruding portions) are formed in a circumferential direction of a filter wire as in the filter wire disclosed in Patent Document <NUM>, the filter wire is wound in an aspect where the protrusions of the filter wire are in contact with each other, and there is a concern that the contact area of overlapping wire portions is small. As a result, in a known filter molded article, a sintering area of a wound filter wire may become insufficient, a shape may be lost when external force is applied to the filter molded article, and the filter wire may be easily unwound.

In contrast, in the filter molded article <NUM> in the present embodiment, the groove portion <NUM> is formed only in one place (single place) in the circumferential direction of the filter wire <NUM>, and the circumferential surface <NUM>, in which the original shape of the metal wire <NUM> forming the filter wire <NUM> is maintained whole, is formed in the remaining region in the circumferential direction. In this way, the contact area of wire portions overlapping each other by winding the filter wire <NUM> is easily ensured, and the sintering area of the wires can be sufficiently ensured. As a result, even when the external force is applied to the filter molded article <NUM>, the filter wire <NUM> is less likely to be unwound, and an occurrence of a loss of shape can be suppressed. For example, even when the filter molded article <NUM> is compressed in the axial direction (top-and-bottom direction) by the lower shell <NUM> and the upper shell <NUM> during assembly of the filter molded article <NUM> into the housing <NUM>, an occurrence of a loss of shape in the filter molded article <NUM> and unwinding of the filter wire <NUM> can be suitably suppressed due to high shape retention (rigidity) of the filter molded article <NUM>.

Further, in the filter molded article described in Patent Document <NUM>, the filter wire needs to be rolled and processed into a bent plate shape having a V-shaped transverse cross-section during manufacturing. Further, since the filter wire having the bent plate shape formed in such a manner has great resistance to winding, it cannot be said that the filter molded article has an excellent manufacturing property. In contrast, according to the filter molded article <NUM> in the present embodiment, by only forming the groove portion <NUM> in only one place in the circumferential direction of the metal wire <NUM> forming the filter wire <NUM>, the original shape (that is, the circular or elliptical shape) of the metal wire <NUM> is maintained in the remaining circumferential surface <NUM>. Thus, manufacturing ease is excellent. As described above, according to the present embodiment, the filter molded article <NUM> having more excellent shape retention (rigidity) and manufacturing ease than found in the related art can be provided.

Furthermore, in the filter molded article <NUM> in the present embodiment, the groove portion <NUM> of the filter wire <NUM> continuously extends from one end to an other end in the extending direction of the filter wire <NUM>. In this way, the combustion gas filtering effect and cooling effect in the filter molded article <NUM> can be further improved. However, in the filter wire <NUM> in the filter molded article <NUM>, the groove portion <NUM> may not continuously extend across the entire section in the extending direction. For example, the groove portion <NUM> may be disposed and intermittently extend along the extending direction of the filter wire <NUM>.

Furthermore, in the filter wire <NUM> of the filter molded article <NUM>, the wire portions stacked (overlapping) in the radial direction of the peripheral wall portion <NUM> are sintered with each other. According to the configuration, the filter wire <NUM> after molding into the cylindrical shape is less likely to be unwound, and the shape retention (rigidity) of the filter molded article <NUM> can be further improved.

Here, <FIG> is a diagram illustrating a transverse cross-section of a filter wire 12A according to a first modified example of the first embodiment. In the filter wire 12A according to the first modified example, a groove edge portion <NUM> located at a boundary portion between the circumferential surface <NUM> and the groove portion <NUM> has a curved shape in the transverse cross-section of the filter wire 12A. In the example illustrated in <FIG>, the groove portion <NUM> has a V shape, and the groove edge portion <NUM> of the groove portion <NUM> has a round shape.

<FIG> is a diagram schematically illustrating a part of a longitudinal cross-section of the peripheral wall portion <NUM> formed by winding the filter wire 12A according to the first modified example. As illustrated in <FIG>, the filter wire 12A is wound, and thus the groove edge portion <NUM> in the groove portion <NUM> of the filter wire 12A is in contact with the circumferential surface <NUM> of the filter wire 12A overlapping in the radial direction of the peripheral wall portion <NUM>. The groove edge portion <NUM> in the groove portion <NUM> has a curved shape (round shape) as in the filter wire 12A according to the present modified example. Thus, a suitable contact relationship between the circumferential surface <NUM> in a wire portion adjacent in the radial direction of the peripheral wall portion <NUM>, and the groove edge portion <NUM> in the groove portion <NUM> can be obtained. In this way, the contact area of overlapping wire portions on the filter wire 12A can be further increased. As a result, the sintering area of the filter wire 12A can be further increased, and the shape retention of the filter molded article <NUM> can be more suitably improved.

Here, <FIG> is a diagram illustrating a transverse cross-section of a filter wire 12B according to a second modified example of the first embodiment. <FIG> is a diagram illustrating a transverse cross-section of a filter wire 12C according to a third modified example of the first embodiment. The filter wire 12B illustrated in <FIG> includes the groove portion <NUM> having a rectangular shape. Further, the filter wire 12C illustrated in <FIG> includes the groove portion <NUM> having a circular shape. In this way, in the present embodiment, a shape of the groove portion <NUM> is not particularly limited. Further, in the filter wires 12B and 12C illustrated in <FIG> and <FIG>, a groove edge portion of the groove portion <NUM> may have a curved shape as described in <FIG>.

Furthermore, the gas generator to which the filter molded article <NUM> in the present embodiment is applied is not limited to the gas generator <NUM> illustrated in <FIG>, and can be applied to various gas generators. For example, in the gas generator <NUM> illustrated in <FIG>, the gas generating agent <NUM> is disposed in the hollow portion 11A in the filter molded article <NUM>, but limitation to such an aspect is not intended. For example, the filter molded article <NUM> may be incorporated into the housing <NUM>, and thus and the hollow portion 11A in the filter molded article <NUM> may be formed as a space through which the combustion gas generated by the combustion of the gas generating agent <NUM> flows. Further, in the embodiment described above, the aspect in which the inner peripheral surface <NUM> of the peripheral wall portion <NUM> in the filter molded article <NUM> is set as the gas inflow surface P1 and the outer peripheral surface <NUM> of the peripheral wall portion <NUM> is set as the gas outflow surface P2 is described as an example, but no such limitation is intended. In other words, depending on a specification of the gas generator to which the filter molded article <NUM> is applied, the gas inflow surface P1 of the peripheral wall portion <NUM> in the filter molded article <NUM> may be formed of the outer peripheral surface <NUM>, and the gas outflow surface P2 of the peripheral wall portion <NUM> may be formed of the inner peripheral surface <NUM>. As a matter of course, in the case of this aspect, the groove portion <NUM> of the filter wire <NUM> may be oriented opening toward the outer peripheral surface <NUM> forming the gas inflow surface P1 of the peripheral wall portion <NUM>. As a result, the filter molded article <NUM> having excellent combustion gas filtering and cooling effects and also having more excellent shape retention (rigidity) and manufacturing ease can be provided.

Claim 1:
A filter molded article (<NUM>) for a gas generator that is housed in an outer shell container of the gas generator, the filter molded article, comprising:
a peripheral wall portion (<NUM>) that is formed of a winding body of a filter wire (<NUM>) and has a cylindrical hollow shape, the filter wire including a groove portion (<NUM>) that is formed in one place in a circumferential direction of a metal wire having a circular or elliptical transverse cross-section and that extends along an extending direction of the metal wire, and including a circumferential surface formed in a portion other than the groove portion;
a gas inflow surface (<NUM>) that is formed of one surface from among an inner peripheral surface of the peripheral wall portion and an outer peripheral surface of the peripheral wall portion, and that is through which gas flows into the peripheral wall portion; and
a gas outflow surface (<NUM>) that is formed of the other surface from among the inner peripheral surface of the peripheral wall portion and the outer peripheral surface of the peripheral wall portion, and that is through which gas flows from the peripheral wall portion, wherein
the groove portion (<NUM>) is oriented so as to open toward the gas inflow surface in the peripheral wall portion.