HONEYCOMB STRUCTURE AND METHOD FOR MANUFACTURING HONEYCOMB STRUCTURE

A honeycomb structure includes an incoming end having a concave shape; an outgoing end having a convex shape; and a plurality of cells each having a polygonal cross section and serving as a channel for a fluid, the channel extending from the incoming end to the outgoing end. The plurality of cells are separated from each other by separator walls. At least one of the plurality of cells has an area of a channel cross section perpendicular to a longitudinal direction, the area increasing from the incoming end toward the outgoing end.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to and incorporates by reference the entire contents of Japanese Patent Application No. 2020-148801 filed in Japan on Sep. 4, 2020.

FIELD

The present invention relates to a honeycomb structure and a method for manufacturing a honeycomb structure.

BACKGROUND

Recently, as a technical issue to be addressed in relation to a high electromagnetic pulse (EMP) defense technology, in order to protect electronic devices from strong electromagnetic waves, there has been a demand for a protective measure adapted to the nature of the electromagnetic waves that impose a threat. Specifically, some protective measures against high EMPs and high output microwaves are required in an opening of a ventilation duct, a cooling duct, or the like, in critical facilities such as power plants, data centers, and defense facilities.

CITATION LIST

Patent Literature

SUMMARY

Technical Problem

In order to ensure shielding performance against electromagnetic waves at 10 GHz, which is the frequency assumed for high EMPs, it is necessary to set the width of an opening of a channel to a size equal to or smaller than a half the wavelength of the electromagnetic wave of 30 mm, that is, to a size equal to or smaller than 15 mm. However, because a conventional opening structure with slits, such as those in a duct or a louver structure in a critical facility, has a slit width equal to or greater than 15 mm, such openings permit easy entry of the electric fields. By contrast, with a commercially available electromagnetic shield having a honeycomb structure (such as that disclosed in Patent Literature 1), not only auxiliary machinery power may be increased due to a pressure loss caused by the airflow, but also such electromagnetic shields can only be installed on a flat surface. Therefore, it has been difficult to fit into the openings with shapes that are different among the facilities.

The present invention is made in consideration of the above, and an object of the present invention is to provide a honeycomb structure and a method for manufacturing a honeycomb structure that are capable of not only ensuring the shielding performance but also suppressing a pressure loss.

Solution to Problem

A honeycomb structure according to the present disclosure includes an incoming end having a concave shape; an outgoing end having a convex shape; and a plurality of cells each having a polygonal cross section and serving as a channel for a fluid, the channel extending from the incoming end to the outgoing end. The plurality of cells are separated from each other by separator walls, and at least one of the plurality of cells has an area of a channel cross section perpendicular to a longitudinal direction, the area increasing from the incoming end toward the outgoing end.

Further, a honeycomb structure according to the present disclosure is made from an assembly of a plurality of polygonal prism-shaped cells having a polygonal cross section in which a passage in a longitudinal direction is provided. A side face of one of the plurality of polygonal prism-shaped cells and a side face of another polygonal prism-shaped cell adjacent to the one of the plurality of polygonal prism-shaped cells integrally form a separator wall. At least one of the plurality of polygonal prism-shaped cells has an area of the cross section, the area increasing from one end toward another end of the at least one of the plurality of polygonal prism-shaped cells in the longitudinal direction. A surface of the one end and a surface of the other end of the assembly in the longitudinal direction are curved toward a direction opposite to a direction in which the area increases.

Further, in a method for manufacturing the honeycomb structure according to the present disclosure, a 3D printer additively lays layers, with a protrusion that is to be on a side of the outgoing end as a base, toward the incoming end, so as to manufacture the honeycomb structure.

Advantageous Effects of Invention

According to the present invention, an object of the present invention is to provide a honeycomb structure and a method for manufacturing a honeycomb structure capable of not only ensuring the shielding performance but also suppressing a pressure loss.

DESCRIPTION OF EMBODIMENTS

A honeycomb structure and a method for manufacturing a honeycomb structure according to an embodiment of the present invention will now be explained in detail based on some drawings. The scope of the present invention is, however, not limited to the description of the embodiment. Furthermore, the elements described in the embodiment below include elements that are easily replaceable by those skilled in the art, elements that are substantially the same, or elements falling within the scope of equivalency. Furthermore, the elements described in the embodiment may be omitted, replaced, or modified variously, within the scope not deviating from the essence of the present invention. In the embodiment described below, the elements required in describing examples of the embodiment of the shock wave supply device according to the present invention will be explained, and explanations of the other elements will be omitted. In the explanation of the embodiment below, the same structures will be given the same reference numerals, and different structures will be given different ones.

Embodiments

To begin with, a configuration of a honeycomb structure10according to one embodiment will now be explained.FIG. 1is a perspective view schematically illustrating a part of the honeycomb structure10according to the embodiment.FIG. 2is a perspective view schematically illustrating a cell20in the honeycomb structure10illustrated inFIG. 1.FIG. 3is a table indicating the dimensions of the cell20illustrated inFIG. 2.FIG. 4is a cross-sectional view illustrating the honeycomb structure10according to the embodiment.

The honeycomb structure10is applied to a structure or equipment requiring not only shielding between an inlet and an outlet of a channel but also suppressing of the pressure loss in a fluid passing through the channel. The honeycomb structure10is applied to an electromagnetic shield for defending against entry of electromagnetic waves via an opening of a critical facility such as a power plant, a data center, or a defense facility, or to a heat exchanger, for example.

As illustrated inFIG. 1, the honeycomb structure10includes a plurality of cells20serving as a channel (passage) for a fluid, the channel extending from an incoming end12to an outgoing end14. Each of the cells20has a polygonal tubular shape on a cross section (hereinafter, referred to as a channel cross section) that is perpendicular to the longitudinal direction. In other words, the cell20is a cell having a shape of a hollow polygonal prism with a polygonal cross sectional shape, and the honeycomb structure10is an assembly of a plurality of the cells each having a polygonal prism shape. The channel cross sectional shape of the cell20is regular hexagonal in the embodiment, but may also be triangular, rectangular, octagonal, or any desired combinations thereof.

Adjacent ones of the cells20are separated from one another by separator walls22provided in a manner surrounding the spaces inside the cells20. A side face of the cell20and a side face of another adjacently positioned cell20integrally form a separator wall22. In other words, a cell20and another cell20adjacent thereto share a separator wall22, with the separator wall22positioned therebetween. The separator wall22has a plate with a flat shape and a constant thickness.

As illustrated inFIG. 2, the cell20has an incoming opening24and an outgoing opening26. The incoming opening24is one end of the cell20in the longitudinal direction, and opens to the side of the incoming end12of the honeycomb structure10. The outgoing opening26is another end of the cell20in the longitudinal direction, and opens to the outgoing end14of the honeycomb structure10.

The width of the cell20becomes larger from one end toward the other end in the longitudinal direction. More specifically, the cell20has a tapered tubular shape in which the channel cross sectional area increases from the incoming opening24toward the outgoing opening26. In the embodiment, the shape of the cell20has a linearly increasing width so that the angle formed by a direction parallel with the longitudinal direction and a side edge of the separator wall22is a constant increasing angle θ. In other words, the separator wall22of the cell20has a shape of an isosceles trapezoid with a base having a width W1on the side of the incoming opening24, another base having a width W2larger than the width W1on the side of the outgoing opening26, and two legs having a length L.

The honeycomb structure10according to the embodiment includes the cells20the all of which have the same shape, but may also include a plurality of types of cells320having different shapes, in the same manner as in a honeycomb structure210according to a second modification, which will be described later, for example. The honeycomb structure may also include some cells420having a straight shape in which the cross sectional area from the incoming opening424to the outgoing opening426is constant, instead of the tapered tubular shape, in the same manner as in a honeycomb structure410according to a fourth modification, which will be described later.

FIG. 3indicates an example of the range of the dimensions of the cells20capable of achieving an electromagnetic shielding performance of 80 dB at 10 GHz in the embodiment. The electromagnetic shielding performance can be adjusted using an average between the inlet cell size and the outlet cell size, and the cell length. When a different electromagnetic shielding performance is required, the ranges of these specifications change, and therefore, the specifications may fall outside of the ranges indicated inFIG. 3.

InFIG. 3, the distance H1between the facing separator walls22of a cell20at the incoming opening24will be referred to as an “inlet cell size”. The inlet cell size is set to a range equal to or more than 2.5 mm and equal to or less than 5 mm. The distance H2between the facing separator walls22of a cell20at the outgoing opening26will be referred to as an “outlet cell size”. The outlet cell size is set to a range equal to or more than 2.5 mm and equal to or less than 10 mm. The length L of the legs of the separator wall22will be referred to as a “cell length”. The cell length is set to a range equal to or more than 6 mm and equal to or less than 30 mm. The ratio of the outlet cell size with respect to the inlet cell size will be referred to as a “cell increase ratio”. In other words, the cell increase ratio is an increase ratio of a width of the channel cross section from the incoming opening24that opens to the incoming end12to the outgoing opening26that opens to the outgoing end14. The cell increase ratio is set to a range equal to or more than one and equal to or less than two.

InFIG. 4, a honeycomb structure910having a flat incoming end912and outgoing end914is illustrated in dotted lines, as a comparative example, in addition to the honeycomb structure10according to the embodiment. The cell20according to the embodiment has a tapered tubular shape in which a cross sectional area perpendicular to the longitudinal direction increases from the incoming opening24toward the outgoing opening26, as described earlier. Because the honeycomb structure10has a structure in which the cells20are connected one after another via the separator walls22, as illustrated inFIG. 4, the honeycomb structure10has a shape with the incoming end12having a concave shape and the outgoing end14having a convex shape, with these ends curved in the same direction that is the direction opposite to the direction of the width increase. In other words, the honeycomb structure10includes a cross section having a fan-like shape in a direction parallel with the channel. In the honeycomb structure10according to the embodiment, the incoming end12and the outgoing end14are curved as a whole in the same direction, but these surfaces may also have a part that is not curved as in a honeycomb structure410according to a fourth modification, which will be described later.

The honeycomb structure10protrudes the furthest at a central part16thereof in the channel cross section direction on the outgoing end14side. The honeycomb structure10may be provided with a plurality of cell groups28connected to each other in a fan-like cross section so that the cell groups28are arranged continuously, in accordance with the shape of the opening where the honeycomb structure10is installed, as illustrated inFIG. 4, for example. Each of the cell groups28is connected to an adjacent cell group28on their respective ends18in the channel cross section direction. More specifically, the separator wall22of the cell20at one end18of a cell group28, that is, the separator wall22not shared by any other cells20is connected, with the edge on the outgoing openings26side thereof, to the edge on the outgoing openings26side of the separator wall22of the cell20at one end18of the adjacent cell group28. In this manner, the fluid F passes through the inside of the cells20from the incoming end12toward the outgoing end14, and does not flow out from other than the cell20.

In the right half of the honeycomb structure10illustrated inFIG. 4, the separator walls22of the cells20are not illustrated, but the directions in which the fluid F passing through the cells20flows are indicated. The directions of the flow of the fluid F passing through the cells20of the honeycomb structure10are radial directions spreading correspondingly to the fan-like shape.

In the honeycomb structure10according to the embodiment, a channel area30increases from the incoming end12toward the outgoing end14. In the honeycomb structure10, because the flow velocity of the fluid F passing through the cells20decreases as the channel area30increases, the pressure loss is suppressed. The honeycomb structure10according to the embodiment has a larger channel area30than the channel area930of the honeycomb structure910in the comparative example. Therefore, the honeycomb structure10having a convex outgoing end14can suppress the pressure loss compared to the honeycomb structure910having a flat incoming end912and outgoing end914.

It is preferable for the honeycomb structure10according to the embodiment to be manufactured by a 3D printer for metals, for example. It is also possible to manufacture the honeycomb structure10by forming the structure using a 3D printer for resins or by extruding, and then by applying conductive coating thereto, or by plating. When a 3D printer is used in the manufacture, a base is manufactured on an area vertically below where the honeycomb structure10to be formed, and a structure that is to become the honeycomb structure10is then formed on the base. At this time, the honeycomb structure10is manufactured by additively laying layers on a protrusion provided on the side of the outgoing end14as a base, toward the incoming end12. In this manner, it is possible to form the separator walls22each separating adjacent cells20so that each separator wall22interposed therebetween is shared by the adjacent cells20. In this manner, a good electrical connection is achieved in a portion where the adjacent cells20are joined, so that it is possible to prevent entry of high EMPs. Furthermore, it is possible to form the separator walls22so as to have a uniform thickness. In this manner, the inner walls of the cells20are kept flat, and the pressure loss of the fluid F passing through the cells20can be suppressed.

First Application Mode

FIG. 5is a perspective view schematically illustrating a shield structure50in a first application mode that is an application of the honeycomb structure10according to the embodiment. The shield structure50is provided inside a rectangular frame60corresponding to an opening of a critical facility. The shield structure50includes a plurality of cell groups28provided in such an orientation that the directions of the flows of the fluid F, that is, the longitudinal directions of the cells20are inclined with respect to the direction of the opening of the frame60. The cell groups28are arranged in rows along one direction that is in parallel with one side of the rectangular frame60. The cell groups28are arranged in a stair-like shape in the other direction that is perpendicular to the one direction, in the frame60.

First Modification

A configuration of a honeycomb structure110according to a first modification will now be explained.FIG. 6is a cross-sectional view illustrating the honeycomb structure110according to the first modification. InFIG. 6, the parts that are the same as those according to the embodiment will be given the same reference numerals, and explanations thereof will be omitted. Furthermore, in the right half of the honeycomb structure110illustrated inFIG. 6, the separator walls22of the cells20are not illustrated, but the directions in which the fluid F passing through the cells20flows are indicated.

The honeycomb structure110according to the first modification is different from the honeycomb structure10according to the embodiment in having a straightening vane40. The straightening vane40is provided in a dead space32that is a space surrounded by the separator walls22of the cells20at the ends18of the adjacent cell groups28. The straightening vane40is provided on the separator walls22located at the connection between the adjacent cell groups28, in a manner projecting from the incoming end12. The straightening vanes40are provided along the ends18of the cell groups28(along the direction perpendicular to the paper surface inFIG. 6). The straightening vane40has a reversed triangular cross section in a direction perpendicular to the longitudinal direction.

The straightening vane40has receiving surfaces42that are connected to the incoming end12. It is preferable for a straightening angle φ formed by the end18of the receiving surface42and the separator wall22of the cell20to be equal to or more than 100 degrees. The straightening vane40receives the fluid F on the receiving surfaces42, so as to prevent the fluid F from flowing into the dead space32that is the space surrounded by the separator walls22of the cells20at the ends18of the adjacent cell groups28. In this manner, it is possible to suppress curving, which is caused by a flow of the fluid F near the end18of the cell group28in the honeycomb structure110, of other main flows of the fluid F.

Second Application Mode

FIG. 7is a perspective view schematically illustrating a shield structure150in a second application mode that is an application of the honeycomb structure110according to the first modification.FIG. 8is a perspective view of the shield structure150illustrated inFIG. 7seen from another direction. InFIGS. 7 and 8, the incoming openings24and the outgoing openings26of the cells20on the incoming end12and the outgoing end14are illustrated in a simplified manner as a grid pattern. As illustrated inFIGS. 7 and 8, the shield structure150includes a plurality of dome portions152and inter-dome portions154.

The honeycomb structure110according to the first modification is applied to the dome portion152. The dome portion152has a hemispheric shape formed by connecting the cells20evenly in the channel cross section direction. The dome portion152has a dome shape in which the incoming end12has a concave spherical surface, and the outgoing end14has a convex spherical surface. The straightening vanes40are provided along the ends18of the dome portions152on the incoming end12(seeFIG. 6). The straightening vane40is provided in a ring-like shape along the end18of the dome portion152.

The inter-dome portion154is a space surrounded by the edges of the three dome portions152. The inter-dome portion154is formed by the cells20connected to one another, in the same manner as the dome portion152. Arranged in the inter-dome portion154are not only the cells20with a tapered tubular shape having an increasing width from the incoming opening24toward the outgoing opening26, the tapered tubular shape being the same as that according to the embodiment, but also cells with a straight shape having a channel cross section whose area is constant across a range from the incoming opening to the outgoing opening.

The shield structure150is a structure in which a plurality of hexagonal structures each having the corresponding dome portion152are connected to one another, via the side faces of the hexagons. In other words, the inter-dome portions154correspond to the corners of the hexagons.

FIG. 9is a graph indicating a ratio of a pressure loss in the shield structure150in the second application mode, with respect to that in a comparative example. The shield structure in the comparative example is a structure using a honeycomb structure910according to the comparative example illustrated inFIG. 4, instead of the honeycomb structure110according to the first modification. In other words, in the shield structure in the comparative example, the incoming end912and the outgoing end914of the honeycomb structure910are flat.

In the shield structure150having the dome-shaped honeycomb structure110in the second application mode, the pressure loss of the fluid F passing through the cells20is approximately 30 percent less than that passing through the cells920in the shield structure with the flat honeycomb structure910according to the comparative example, as illustrated inFIG. 9. In this manner, in the shield structure150in the second application mode, the pressure loss is suppressed because the flow velocity of the fluid F passing through the cells20decreases as the channel area increases from the incoming end12toward the outgoing end14of the honeycomb structure110in the dome portion152. Furthermore, the straightening vanes40provided to the ends18of the respective dome portions152on the side of the incoming end12receive the fluid F, thereby further suppressing the pressure loss.

Second Modification

A configuration of a honeycomb structure210according to a first modification will now be explained.FIG. 10is a cross-sectional view illustrating the honeycomb structure210according to the second modification. InFIG. 10, the parts that are the same as those according to the first modification will be given the same reference numerals, and explanations thereof will be omitted. Furthermore, in the right half of the honeycomb structure210illustrated inFIG. 10, the separator walls222of the cells220are not illustrated, but the directions in which the fluid F passing through the cells220flows are indicated.

The honeycomb structure210according to the second modification has the incoming end12having a concave shape and the outgoing end14having a convex shape, in the same manner as the honeycomb structure10according to the embodiment and the honeycomb structure110according to the first modification. In the second modification, the curvatures of the incoming end12and the outgoing end14of the honeycomb structure210are the same as those of the incoming end12and the outgoing end14according to the embodiment and the first modification.

The honeycomb structure210according to the second modification is different from the honeycomb structure110according to the first modification in including cells220instead of the cells20. In the cells220, adjacent cells220are separated from one another by the separator walls222, in the same manner as in the cells20according to the embodiment and the first modification.

The cell220has an incoming opening224that opens to the incoming end12, and an outgoing opening226that opens to the outgoing end14. The honeycomb structure210is provided with a plurality of cell groups228connected to each other in a fan-like cross section so that the cell groups228are arranged continuously, in the same manner as in the honeycomb structures10,110according to the embodiment and the first modification.

In the honeycomb structure210, among the cells220, cells220positioned in the central part16of the cell group228in the channel cross section direction have different sizes from those of the cells220positioned near the ends18. More specifically, the cells220positioned near the ends18have larger channel cross sectional areas than the cells220positioned in the central part16. Furthermore, the cells220positioned near the ends18has higher increase ratios of the channel cross sectional width from the incoming end12to the outgoing end14, than the cells220positioned in the central part16.

In the honeycomb structure210having the outgoing end14protruding in a concave shape, the fluid F becomes collected at the central part16, and does not easily flow into the end18. In the second modification, setting the increase ratio of the channel cross sectional area and the increase ratio of the width for the cells220of the end18higher than the central part16suppresses the differences in the flow velocities of the fluid F on the incoming end12. Allowing the fluid F to flow at a constant velocity across the entire cell groups228can suppress the pressure loss.

Third Modification

A configuration of a honeycomb structure310according to a third modification will now be explained.FIG. 11is a cross-sectional view illustrating the honeycomb structure310according to the third modification. In the right half of the honeycomb structure310illustrated inFIG. 11, the separator walls322of the cells320are not illustrated, but the directions in which the fluid F passing through the cells320flows are indicated.

The honeycomb structure310according to the third modification has an incoming end312having a concave shape, and an outgoing end314having a convex shape. The honeycomb structure310according to the third modification includes a plurality of cells320and a straightening vane340instead of the cells220and the straightening vane40, which is difference from the honeycomb structure210according to the second modification. Adjacent cells320of the cells320are separated from one another by the separator walls322in the same manner as the cells20,220in the embodiment, the first modification, and the second modification.

The cell320has an incoming opening324that opens to the incoming end312, and an outgoing opening326that opens to the outgoing end314. The honeycomb structure310is provided with a plurality of cell groups328connected to each other in a fan-like cross section so that the cell groups328are arranged continuously, in the same manner as in the honeycomb structure10,110,210according to the embodiment, the first modification, and the second modification.

In the honeycomb structure310, among the cells320, cells320positioned in the central part316of the cell group328in the channel cross section direction have different sizes from those of the cells320positioned near the end318. More specifically, the cells320positioned near the end318have larger channel cross sectional areas than the cells320positioned in the central part316. The cells320positioned near the end318also have larger channel lengths between the incoming end312and the outgoing end314than the cells320positioned in the central part316.

In other words, the curvatures of the incoming end312and the outgoing end314of the honeycomb structure310according to the third modification are smaller than the incoming end12and the outgoing end14according to the embodiment, the first modification, and the second modification. Furthermore, setting the curvature of the incoming end312smaller than the outgoing end314in the honeycomb structure310suppress the dead space332between the cell320at the end318and the cell320at the end318of an adjacent cell group328. In this manner, it is possible to suppress curving, which is caused by a flow of the fluid F near the end318of the cell group328in the honeycomb structure310, of other main flows of the fluid F.

The honeycomb structure310also includes a straightening vane340projecting from the incoming end312, in a dead space332that is the space surrounded by the separator walls322of the cells320at the ends318of the adjacent cell groups328. When the receiving surface342of the straightening vane340receives the fluid F, it possible to further suppress curving, which is caused by a flow of the fluid F near the end318of the cell group328in the honeycomb structure310, of other main flows of the fluid F, thereby suppressing the pressure loss.

Fourth Modification

A configuration of a honeycomb structure410according to a fourth modification will now be explained.FIG. 12is a cross-sectional view illustrating the honeycomb structure410according to the fourth modification. In the honeycomb structure410illustrated inFIG. 12, the right half is illustrated with the separator walls422of the cells420omitted, and indicates the directions of the fluid F passing through the cells420.

The honeycomb structure410according to the fourth modification has an incoming end412of a concave shape and an outgoing end414of a convex shape. The honeycomb structure410according to the fourth modification includes a plurality of cells420and a straightening vane440instead of the cells320and the straightening vane340, which is difference from the honeycomb structure310according to the third modification. Adjacent cells420of the cells420are separated from one another by the separator walls422, in the same manner as the cells20,220,320in the embodiment, the first modification, the second modification, and the third modification.

The cell420has an incoming opening424that opens to the incoming end412, and an outgoing opening426that opens to the outgoing end414. The honeycomb structure410is provided with a plurality of cell groups428connected to each other in a fan-like cross section so that the cell groups428are arranged continuously, in the same manner as in the honeycomb structure10,110,210,310according to the embodiment, the first modification, the second modification, and the third modification.

In the honeycomb structure410, among the cells420, cells420positioned in the central part416of the cell group428in the channel cross section direction have different sizes from those of the cells420positioned near the end418. More specifically, the cells420positioned near the end418have larger channel cross sectional areas than the cells420positioned in the central part416. Furthermore, the cells420positioned near the end418have larger channel lengths from the incoming end412to the outgoing end414than the cells420positioned in the central part416. The cells420positioned in the central part416also have a straight shape where the shape and the area of the channel cross section from the incoming end412to the outgoing end414are constant.

In other words, in the fourth modification, the central part416of the cell group428is flat in the honeycomb structure410. In this manner, with the cell group428having a convex shape on the outgoing end414side as a whole, in the same manner as the honeycomb structure10according to the embodiment, the honeycomb structure410can suppress the pressure loss of the fluid F and can also be provided in a shape suitable for a structure to which the honeycomb structure10is applied and a surrounding environment.

The honeycomb structure410also includes a straightening vane440projecting from the incoming end412, in a dead space432that is the space surrounded by the separator walls422of the cells420at the ends418of the adjacent cell groups428. When the receiving surface442of the straightening vane440receives the fluid F, it is possible to suppress curving, which is caused by a flow of the fluid F near the end418of the cell group428in the honeycomb structure410, of other main flows of the fluid F, thereby suppressing the pressure loss.

Fifth Modification

A configuration of a honeycomb structure510according to a fifth modification will now be explained.FIG. 13is a cross-sectional view illustrating the honeycomb structure510according to the fifth modification. In the right half of the honeycomb structure510illustrated inFIG. 13, the separator walls522of the cells520are not illustrated, but the directions in which the fluid F passing through the cells520flows are indicated.

The honeycomb structure510according to the fifth modification has an incoming end512having a concave shape, and an outgoing end514having a convex shape. The honeycomb structure510according to the fifth modification is different from the honeycomb structure310according to the third modification in including a plurality of cells520and a straightening vane540, instead of the cells320and the straightening vane340. Adjacent cells520of the cells520are separated from one another by the separator walls522, in the same manner as in the cells20,220,320,420in the embodiment, the first modification, the second modification, the third modification, and the fourth modification.

The cell520has an incoming opening524that opens to the incoming end512, and an outgoing opening526that opens to the outgoing end514. The honeycomb structure510is provided with a plurality of cell groups528connected to each other in a fan-like cross section so that the cell groups528are arranged continuously, in the same manner as in the honeycomb structures10,110,210,310,410according to the embodiment, the first modification, the second modification, the third modification, and the fourth modification.

In the honeycomb structure510, among the cells520, cells520positioned in the central part516of the cell group528in the channel cross section direction have different sizes from those of the cells520positioned near the end518. More specifically, the cells520positioned near the end518have larger channel cross sectional areas than the cells520positioned in the central part516. Furthermore, the cells520positioned near the end518have larger channel lengths between the incoming end512and the outgoing end514, than the cells520positioned in the central part516.

In the fifth modification, the curvatures of the incoming end512and the outgoing end514of the honeycomb structure510are greater than the incoming end12,312and the outgoing end14,314according to the embodiment, the first modification, the second modification, and the third modification. In this manner, with the cell group528having a convex shape on the outgoing end514side as a whole, in the same manner as the honeycomb structure10according to the embodiment, the honeycomb structure510can suppress the pressure loss of the fluid F and can also be provided in a shape suitable for a structure to which the honeycomb structure510is applied and a surrounding environment. Specifically, by increasing the curvatures of the incoming end512and the outgoing end514, the size in a direction intersecting with a direction in which the fluid F flows (the right-left direction inFIG. 13) can be suppressed. In this manner, the honeycomb structure510can be installed in a location with a limited installation space.

The honeycomb structure510also includes a straightening vane540projecting from the incoming end512, in a dead space532that is the space surrounded by the separator walls522of the cells520at the ends518of the adjacent cell groups528. When the receiving surface542of the straightening vane540receives the fluid F, it is possible to suppress curving, which is caused by a flow of the fluid F near the end518of the cell group528in the honeycomb structure510, of other main flows of the fluid F, thereby suppressing the pressure loss.

Actions and Effects Achieved by Embodiments

A method for manufacturing the honeycomb structure10,110,210,310,410,510and the honeycomb structure10,110,210,310,410,510according to the embodiments is recognized as follows, for example.

The honeycomb structure10,110,210,310,410,510according to a first aspect includes the incoming end12,312,412,512having a concave shape, the outgoing end14,314,414,514having a convex shape, and a plurality of the cells20,220,320,420,520each having a polygonal cross section and serving as a channel for the fluid F, the channel extending from the incoming end12,312,412,512to the outgoing end14,314,414,514. The cells20,220,320,420,520are separated from one another by the separator walls22,222,322,422,522, and at least some of the cells20,220,320,420,520among the cells20,220,320,420,520increase an area of the channel cross section perpendicular to the longitudinal direction of the cells20,220,320,420,520from the incoming end12,312,412,512toward the outgoing end14,314,414,514.

The honeycomb structure10,110,210,310,410,510according to the first aspect has the channel area that increases in the direction from the incoming end12,312,412,512toward the outgoing end14,314,414,514. In the honeycomb structure10,110,210,310,410,510, because the flow velocity of the fluid F passing through the cells20,220,320,420,520decreases as the channel area increases, the pressure loss is suppressed. In other words, because the honeycomb structure10,110,210,310,410,510has the outgoing end14,314,414,514having a convex shape, the pressure loss can be suppressed compared with the honeycomb structure910in which the incoming end912and the outgoing end914are flat. Therefore, it is possible to suppress the pressure loss while maintaining the shielding performance.

In the honeycomb structure10,110,210,310,410,510according to a second aspect, a plurality of the cells20,220,320,420,520and the adjacent cells20,220,320,420,520with separator walls22,222,322,422,522interposed therebetween are provided so as to share the separator walls22,222,322,422,522. In this manner, electrical connection in a portion where the adjacent cells20,220,320,420,520are joined is good compared with the conventional honeycomb structure where the cells share no separator wall with each other, which can improve the shielding performance for preventing the entry of the high EMPs.

The honeycomb structures110,210,310,410,510according to a third aspect include the straightening vanes40,340,440,540projecting from the separator walls22,222,322,422,522that are not shared by cells20,220,320,420,520adjacent to each other toward the incoming ends12,312,412,512. The straightening vane40,340,440,540receives the fluid F, to prevent the fluid F from flowing into the dead space32,332,432,532that is the space surrounded by the separator walls22,222,322,422,522not shared by any adjacent cells20,220,320,420,520. In this manner, it is possible to suppress curving, which is caused by a flow of the fluid F near the ends18,318,418,518in the honeycomb structures110,210,310,410,510, of other main flows of the fluid F.

In the honeycomb structure10,110,210,310,410,510according to a fourth aspect, the separator walls22,222,322,422,522have a uniform thickness. In this manner, the inner walls of the cells20,220,320,420,520become flat, so that it becomes possible to suppress the pressure loss of the fluid F passing through the cells20,220,320,420,520.

In the honeycomb structure10,110,210,310,410,510according to a fifth aspect, the cells20,220,320,420,520have a channel cross section with a regular hexagonal shape. With this configuration, because the high EMPs do not diffusely reflect on the separator walls22,222,322,422,522facing each other in the cells20,220,320,420,520, the shielding performance can be improved.

In the honeycomb structure10,110,210,310,410,510according to a sixth aspect, the cells20,220,320,420,520have an increase ratio of a width of the channel cross section from the incoming end12,312,412,512to the outgoing end14,314,414,514that is equal to or more than one and equal to or less than two. Because the flow velocity of the fluid F passing through the cells20,220,320,420,520decreases as the channel area increases, it is possible to reduce the pressure loss, thereby suppressing the pressure loss while maintaining the shielding performance.

The honeycomb structure110according to a seventh aspect has a dome shape in which the incoming end12has a concave spherical surface and the outgoing end14has a convex spherical surface. In other words, the fluid F passing through the cells20of the honeycomb structure110flow in radially spreading directions. Because the flow velocity of the fluid F passing through the cells20decreases as the channel area increases, it is possible to suppress the pressure loss, thereby suppressing the pressure loss while maintaining the shielding performance.

In the honeycomb structure210,310,410,510according to an eighth aspect, among the cells220,320,420,520, the cells220,320,420,520positioned at the end18,318,418,518in the channel cross section direction have larger channel cross sectional areas than the cells220,320,420,520positioned in the central part16,316,416,516in the channel cross section direction. In the honeycomb structure210,310,410,510having the outgoing end14,314,414,514protruding in a concave shape, the fluid F becomes collected at the central part16,316,416,516, and does not tend to flow into the end18,318,418,518. By setting the channel cross sectional area of the cells220,320,420,520near the end18,318,418,518larger than the central part16,316,416,516, it is possible to suppress the difference in the flow velocities of the fluid F on the incoming end12,312,412,512. In this manner, because it is possible to cause the fluid F to flow at a constant velocity across the entire honeycomb structure210,310,410,510, the pressure loss can be suppressed.

In the honeycomb structure310,410,510according to a ninth aspect, among the cells320,420,520, cells320,420,520, the cells320,420,520positioned at the end318,418,518in the longitudinal direction have larger lengths than the cells320,420,520positioned in the central part316,416,516in the channel cross section direction. In this manner, the honeycomb structure310,410,510keeps the curvature of the incoming end312,412,512smaller than that of the outgoing end314,414,514, and keeps the dead space332,432,532that is the space surrounded by the separator walls322,422,522not shared by any adjacent cells320,420,520small. In this manner, it is possible to suppress curving, which is caused by a flow of the fluid F near the end318,418,518of the honeycomb structure310,410,510, of other main flows of the fluid F.

The honeycomb structure10,110,210,310,510according to a tenth aspect, the incoming end12,312,512and the outgoing end14,314,514are curved as a whole in a direction of the side of the incoming end12,312,512. In other words, the fluid F passing through the cells20,220,320,520of the honeycomb structure10,110,210,310,510flows in radially spreading directions. Because the flow velocity of the fluid F passing through the cells20,220,320,520decreases as the channel area increases, it is possible to suppress the pressure loss, thereby suppressing the pressure loss while maintaining the shielding performance.

In the honeycomb structure410according to an eleventh aspect, among the cells420, the cells420positioned in the central part of the channel cross section direction have the cross sections the shape and area of which are constant from the incoming end412to the outgoing end414. In this manner, the central part416of the honeycomb structure410is kept flat. Therefore, because the honeycomb structure410as a whole has a shape that is convex toward the outgoing end414, the honeycomb structure410can suppress the pressure loss of the fluid F and can also be provided in a shape suitable for a structure to which the honeycomb structure410is applied and a surrounding environment.

The honeycomb structure10,110,210,310,410,510according to a twelfth aspect is a honeycomb structure10,110,210,310,410,510including an assembly of a plurality of polygonal prism-shaped cells (the cell20,220,320,420,520) each having a polygonal cross section in which a passage in the longitudinal direction is provided. In the honeycomb structure10,110,210,310,410,510, a side face of one of the polygonal prism-shaped cells and a side face of another one of the adjacent polygonal prism-shaped cells integrally form a separator wall22,222,322,422,522; at least some of the polygonal prism-shaped cells among the plurality of polygonal prism-shaped cells have a cross sectional area having a width increasing from one ends (the incoming end12,312,412,512) toward the other ends (the outgoing end14,314,414,514) of the polygonal prism-shaped cells in the longitudinal direction; and the surface of the one end and the surface of the other end of the assembly in the longitudinal direction are curved toward the direction opposite to the direction in which the width increases.

The honeycomb structure10,110,210,310,410,510according to the twelfth aspect achieves a good electrical connection in a portion where the adjacent polygonal prism-shaped cells are joined compared with the conventional honeycomb structure in which one side face of the polygonal prism-shaped cell is not integrated with that of another adjacent polygonal prism-shaped cell, which can improve the shielding performance for preventing the entry of the high EMPs. Furthermore, the fluid F passing through the polygonal prism-shaped cells flows in radially spreading directions, and the flow velocity thereof decreases as the channel area increases. Therefore, it is possible to reduce the pressure loss, thereby suppressing the pressure loss while maintaining the shielding performance.

The honeycomb structure10,110according to a thirteenth aspect is the shield structure50,150provided so as to close an opening in a given facility, and is intended to prevent entry of high EMPs from the opening. The honeycomb structure10,110can be built into any desired shape by adjusting the width of the channel cross section, the channel length, and the increase ratio of the cells20across the range from the incoming end12to the outgoing end14, and thus can be applied to an opening having a complicated shape.

The honeycomb structure10according to a fourteenth aspect is provided in such an orientation that the longitudinal directions of the cells20are inclined with respect to the direction in which the opening opens. Even when the direction of the flow of the fluid F is inclined with respect to the direction in which the opening opens in the manner described above, the honeycomb structure10can be provided in a shape suitable for a structure to which the honeycomb structure10is applied and a surrounding environment.

The honeycomb structure110according to a fifteenth aspect is provided in such a manner that a plurality of hexagonal structures each having the dome portion152are connected with the respective side faces of the hexagons connected to one another, the dome portion152having the incoming end12with a concave spherical surface and the outgoing end14with a convex spherical surface. In other words, the fluid F passing through the cells20in the dome portion152flows in radially spreading directions. Because the flow velocity of the fluid F passing through the cells20in the dome portion152decreases as the channel area increases, it is possible to suppress the pressure loss, thereby suppressing the pressure loss while maintaining the shielding performance.

In the honeycomb structure110according to a sixteenth aspect, cells each having a cross section the shape and area of which are constant from the incoming end12to the outgoing end14are arranged in a space surrounded by a plurality of the dome portions152. By increasing the channel area in the dome portion152and arranging the straight cells in the space surrounded by the dome portion152, it is possible to reduce the dead space, and to further suppress the pressure loss.

The honeycomb structure110according to a seventeenth aspect includes the straightening vane40that is provided in a ring-like shape along the end18of the dome portion152, and that projects from the separator wall22toward the incoming end12. In this manner, it is possible to suppress curving, which is caused by a flow of the fluid F near the end18of the dome portion152, of other main flows of the fluid F.

In a method for manufacturing the honeycomb structure10,110,210,310,410,510according to an eighteen aspect, the honeycomb structure10,110,210,310,410,510is manufactured by additively laying layers on a protrusion provided on the side of the outgoing end14,314,414,514as a base, toward the incoming end12,312,412,512, using a 3D printer. In other words, by setting the side with a larger cross sectional area as a lower layer, the honeycomb structure10,110,210,310,410,510can be manufactured stably. Furthermore, the raft can be removed easily after the manufacture.

In a method for manufacturing the honeycomb structure10,110,210,310,410,510according to a nineteenth aspect, the honeycomb structure10,110,210,310,410,510is manufactured by extrusion. In this manner, the cells20,220,320,420,520can be manufactured integrally, so that it is possible to form the separator walls22,222,322,422,522separating the adjacent cells20,220,320,420,520, as the walls shared between the adjacent cells20,220,320,420,520. Therefore, a good electrical connection is achieved in a portion where the adjacent cells20,220,320,420,520are joined, so that the shielding performance for preventing the entry of the high EMPs can be improved.

Some embodiments of the present invention have been explained above, but none of the descriptions in these embodiments is not intended to limit the scope of the embodiments in any way. Furthermore, the shield structure50,150for preventing the entry of the high EMP has been explained as an example in the application modes, but the honeycomb structure10,110,210,310,410,510according to the embodiment may also be applied to a heat exchanger, for example.

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