Honeycomb structure

Abstract

This honeycomb structure comprises a plurality of first cells 12 which are disposed in a honeycomb shape and which are joined in the Y direction and a second cell which is provided by partition walls 15(14) of two cells among the plurality of first cells 12 that are adjacent to each other in the Y direction, wherein: the partition walls 15(14) include a cell-forming wall 21 that forms the second cell 20 and a first joining wall 22 and a second joining wall 23 that are separate from each other with the cell-forming wall 21 therebetween; and a first flat surface which forms the first joining wall 22 and a second flat surface which forms the second joining wall 23 are not positioned in the same plane.

Description

Honeycomb structure

[0001] The present invention relates to a honeycomb structure.

[0002] Patent Document 1 discloses a honeycomb structure having a plurality of columnar cells extending in the vertical direction. The partition walls constituting each cell include a pair of double-wall structures arranged opposite each other and extending in the same direction. A space (small cell) different from the cells is formed in a part of each double-wall structure.

[0003] Japanese Patent Application Laid-Open No. 2022-75629

[0004] The honeycomb structure of Patent Document 1 improves the overall strength of the honeycomb structure by providing the above-mentioned spaces. Meanwhile, this honeycomb structure is formed by bonding together corrugated sheets, each having alternating peaks and valleys. When pressure is applied to this honeycomb structure from above and below, peeling easily occurs at the portion of the approximately hexagonal partition walls that make up the cells where the corrugated sheets are bonded together. In other words, when the honeycomb structure is used as an energy absorption member, there is a concern that the energy absorption efficiency of the entire honeycomb structure will decrease due to insufficient bonding strength at this portion.

[0005] An object of the present invention is to improve the energy absorption efficiency of a honeycomb structure having minute cells in its partition walls.

[0006] A honeycomb structure according to one aspect of the present invention includes a plurality of first cells arranged in a honeycomb shape and joined in a first direction, and second cells provided in two partition walls adjacent to each other in the first direction among the plurality of first cells. The partition walls include cell forming walls that form the second cells, and first and second joining walls that are separated from each other via the cell forming walls. A first plane that forms the first joining wall and a second plane that forms the second joining wall are not located on the same plane.

[0007] According to the present invention, it is possible to improve the energy absorption efficiency in a honeycomb structure having minute cells in its partition walls.

[0008] FIG. 1 is a perspective view of a honeycomb structure according to an embodiment. FIG. 2 is a view of the honeycomb structure shown in FIG. 1 as viewed from the Z direction. FIG. 3 is an enlarged cross-sectional view of a partition wall according to an embodiment. FIG. 4 is a view as viewed from the arrows A-A in FIG. 3. FIG. 5A is a view of a modified honeycomb structure as viewed from the Z direction. FIG. 5B is an enlarged cross-sectional view of the partition wall shown in FIG. 5A. FIG. 6 is an enlarged cross-sectional view of a first modified partition wall according to an embodiment. FIG. 7 is an enlarged cross-sectional view of a second modified partition wall according to an embodiment. FIG. 8 is a view of a modified honeycomb structure according to an embodiment as viewed from the Z direction.

[0009] Hereinafter, honeycomb structures 10 according to several embodiments will be described with reference to the drawings. In the following description, elements having the same functions are denoted by the same reference numerals, and redundant description will be omitted. For ease of description, mutually orthogonal X-direction (second direction), Y-direction (first direction), and Z-direction are defined. The X-direction is the ribbon direction of the corrugated sheet 11 and the direction in which rows of first cells 12 linearly arranged in the Y-direction are aligned (see FIG. 2). The Y-direction is the stacking direction and width direction (expansion direction) of the corrugated sheet 11. The Y-direction is also the direction in which the first cells 12 are arranged in multiple straight lines. The Z-direction is the extension direction of the first cells 12 (see FIG. 1) and the height direction (thickness direction) of the honeycomb structure 10.

[0010] 1 and 2 , a honeycomb structure 10 is composed of, for example, a plurality of corrugated sheets 11. The corrugated sheets 11 have a cross-sectional shape that forms partition walls 14 of first cells 12, which will be described later, and are joined together in the Y direction. Note that joining refers to connecting structural materials by welding, bonding, brazing, or the like. These methods are appropriately selected depending on the material of the corrugated sheets 11.

[0011] The corrugated sheet 11 is a sheet material such as a metal foil such as aluminum, a fiber reinforced plastic (FRP) sheet, paper, etc. The thickness of the sheet material is not particularly limited, but is, for example, about 0.01 mm to 0.5 mm.

[0012] Examples of FRP include aramid fiber reinforced plastic (AFRP), carbon fiber reinforced plastic (CFRP), glass fiber reinforced plastic (GFRP), etc. The matrix resin of FRP is, for example, a thermosetting resin such as epoxy resin, polyester resin, vinyl ester resin, or phenolic resin, or a thermoplastic resin such as polypropylene resin, polyamide resin, polycarbonate resin, or polyetherimide resin.

[0013] 1 and 2, the honeycomb structure 10 includes a plurality of first cells 12 arranged in a honeycomb pattern. Each first cell 12 forms a space 13 having a substantially hexagonal cross section when viewed from the Z direction, and extends in the Z direction. As will be described later, the plurality of first cells 12 are joined in the Y direction via their respective first partition walls 15 (see FIG. 3).

[0014] 2 , the space 13 of each first cell 12 is formed by partition walls 14 that partition each first cell 12. The partition walls 14 include three pairs of partition walls that surround the space 13 of each first cell 12. Specifically, the partition walls 14 include a pair of first partition walls 15, 15, a pair of second partition walls 16, 16, and a pair of third partition walls 17, 17.

[0015] As shown in Fig. 2, the second cells 20 located on both sides of each first cell 12 in the second direction may be aligned in the X direction. In this case, it is possible to suppress an increase in the thickness of each corrugated sheet 11 constituting the partition walls 14 of the second cells 20 in the Y direction (width direction). Therefore, the corrugated sheets become compact, and it is possible to improve the productivity and yield when manufacturing the honeycomb structure 10.

[0016] A pair of first partition walls 15, 15 are aligned in the Y direction. Although each first partition wall 15 has a bent portion due to a first joining wall 22 and a second joining wall 23 (described later), the first partition wall 15 is generally parallel to the X-Z plane. A pair of second partition walls 16 are arranged in a direction tilted to one side with respect to the Y direction. The second partition walls 16 are formed flat. A pair of third partition walls 17 are aligned in a direction further tilted with respect to the alignment direction of the pair of second partition walls 16. Like the second partition walls 16, the third partition walls 17 are also formed flat. In one first cell 12, one of the first to third partition walls 15 to 17 of each pair is formed from a single corrugated sheet 11, and the other of the first to third partition walls 15 to 17 of each pair is formed from another single corrugated sheet 11.

[0017] For ease of explanation, the corrugated sheet 11 forming the first partition walls 15 of a first cell 12 is denoted by reference numeral 11A (see FIG. 3). The corrugated sheet 11 forming the first partition walls 15 of another first cell 12 adjacent to the first cell 12 in the Y direction is denoted by reference numeral 11B (see FIG. 3). The honeycomb structure 10 according to this embodiment is formed by a plurality of corrugated sheets 11 joined in the Y direction. To form this honeycomb structure 10, the corrugated sheet 11A is joined to the corrugated sheet 11B via the first partition walls 15. That is, the first partition walls 15 have a so-called double-wall structure formed by joining two corrugated sheets 11A and 11B together.

[0018] 2 and 3, the honeycomb structure 10 according to this embodiment includes second cells 20 provided in the partition walls 14 (i.e., first partition walls 15) of two cells adjacent to each other in the Y direction among the plurality of first cells 12. The first partition walls 15 include a cell forming wall 21, a first joining wall 22, and a second joining wall 23.

[0019] The first and second joining walls 22 and 23 are spaced apart in the X and Y directions via the cell forming wall 21. The first and second joining walls 22 and 23 extend parallel to each other. In other words, if the plane of the first joining wall 22 is defined as the first plane and the plane of the second joining wall 23 is defined as the second plane, the first and second planes are not coplanar. Therefore, the first joining surface 22a of the corrugated sheets 11A and 11B formed on the first joining wall 22 and the second joining surface 23a of the corrugated sheets 11A and 11B formed on the second joining wall 23 are also not coplanar. In other words, the first plane including the first joining wall 22 (first joining surface 22a) is offset in the Y direction by a length D of the space 24 of the second cell 20 along the Y direction from the second plane including the second joining wall 23 (second joining surface 23a).

[0020] The cell forming wall 21 is formed by the corrugated sheets 11A and 11B spaced apart from each other in the X and Y directions. That is, the cell forming wall 21 does not have a joining surface between the corrugated sheets 11A and 11B. For example, as shown in FIG. 3 , the corrugated sheet 11A extends from the first joining wall 22 in the X direction, bends in the direction opposite the Y direction, and extends to the second joining wall 23. On the other hand, the corrugated sheet 11B extends from the second joining wall 23 in the direction opposite the X direction, bends in the Y direction, and extends to the first joining wall 22. As a result, the cell forming wall 21 constitutes the second cell 20, and the second cell 20 forms a space 24 having a substantially rectangular cross section when viewed from the Z direction.

[0021] As described above, the first and second joining walls 22 and 23 are not located on the same plane but are separated from each other in the X and Y directions via the second cells 20. When the honeycomb structure 10 is subjected to a relatively large pressure, such as an impact, from the Z direction, as shown in FIG. 4 , a force (indicated by the open arrows) that separates the second joining surface 23a from one side to the other in the Y direction is generated at the end of the second joining surface 23a in the Z direction. Similar forces are also generated at the end of the first joining surface 22a. These forces may cause the corrugated sheets 11A and 11B to peel from each other. In contrast, the first and second joining surfaces 22a and 23a of the same first partition wall 15 do not form a single ridge. That is, they are separated from each other. Therefore, the peel force is less likely to be transmitted from one of the first joining surface 22a and the second joining surface 23a to the other. Furthermore, even if a crack that develops into separation occurs in one of the first bonding surface 22 a and the second bonding surface 23 a, the crack is less likely to develop into the other, thereby improving the resistance to forces that would separate the bonding surfaces.

[0022] Furthermore, a portion of the cell forming wall 21 is connected to the first joining wall 22 in a direction intersecting the first joining wall 22. Similarly, another portion of the cell forming wall 21 is connected to the second joining wall 23 in a direction intersecting the second joining wall 23. In other words, the cell forming wall 21 is positioned in a direction in which the first joining wall 22 and the second joining wall 23 are easily deflected. The above-mentioned peeling force generates in-plane shear forces indicated by the multiple arrows in the figure within the cell forming wall 21, and these shear forces suppress the occurrence and progression of peeling at each joining surface. In other words, the cell forming wall 21 functions as a so-called rib. Therefore, according to this embodiment, the mechanical strength of a honeycomb structure having minute cells in its partition walls can be improved, and peeling at the joining surfaces can be suppressed. As a result, compressive failure due to buckling is more likely to occur, and energy absorption efficiency can be improved.

[0023] As shown in Figures 5A and 5B, the cell-forming walls 21 may be curved in a cross section perpendicular to the Z direction. That is, each of the corrugated sheets 11A and 11B of the cell-forming walls 21 may extend from one of the first joining walls 22 and the second joining walls 23 to the other so as to curve outward toward the outside of the space 24. By configuring the cell-forming walls 21 as a pair of curved walls, it is possible to alleviate stress concentration that occurs locally in the cell-forming walls 21. This increases the mechanical strength of the cell-forming walls 21 (i.e., the second cells 20), thereby improving the energy absorption efficiency of the second cells 20. Furthermore, during the manufacturing of the corrugated sheet 11, stress concentration due to excessive bending in the portions that will become the cell-forming walls 21 can be suppressed.

[0024] As shown in FIG. 6 , the first and second joining walls 22 and 23 may be bonded together at their joints. For example, the first joining wall 22 may have an adhesive layer 22b formed therein as a first joining surface 22a. Similarly, the second joining wall 23 may have an adhesive layer 23b formed therein as a second joining surface 23a. In this case, the adhesive layers 22b and 23b are formed with an adhesive used to bond the corrugated sheet 11. When the corrugated sheet 11 is made of resin, bonding generally provides a stronger bonding strength than welding. Therefore, peeling of the bonding surface (i.e., the adhesive layer) can be suppressed compared to welding of the corrugated sheet. For example, when the honeycomb structure 10 according to this embodiment is used as an energy absorbing member, the progression of failure due to buckling of the partition walls 14, which is the original energy absorption failure mode, can be accelerated.

[0025] The adhesive can be appropriately selected depending on the material of the honeycomb structure 10. Typical examples include elastic adhesives such as silicone-based, modified silicone-based, epoxy-based, urethane-based, nitrile rubber-based, and butyl rubber-based. The use of an elastic adhesive can suppress the occurrence and progression of cracks in the adhesive layers 22b and 23b, and can accelerate the progression of destruction due to buckling of the partition walls 14. However, the adhesive is not limited to the above elastic adhesives, as long as excessive cracking or peeling does not occur when the partition walls 14 buckle against the applied pressure. For example, the adhesive may be a thermoplastic resin adhesive such as a vinyl acetate-based adhesive, or an epoxy-based or polyurethane-based thermosetting resin adhesive.

[0026] 7, the second cells 20 may be filled with the above-mentioned adhesive. By filling the spaces 24 with the adhesive, the bonding strength between the corrugated sheets 11 can be increased.

[0027] 8, the second cells 20, 20 located on both sides of each first cell 12 in the X direction may be offset from each other in the Y direction. In any embodiment, the first joining wall 22 (first joining surface 22a) and the second joining wall 23 (second joining surface 23a) are parallel to the XZ plane. Therefore, when pressure is applied to the honeycomb structure 10 from the Z direction, a peeling force is generated in each first partition wall in a direction parallel to the Y direction.

[0028] 8, the second cells 20, 20 adjacent to each other via the first cell 12 are the pair of cells closest to each other along the Y direction. By displacing at least a plurality of such pairs of second cells 20, 20 from the same plane parallel to the XZ plane and by shifting them from each other in the Y direction, it is possible to prevent localized peeling at the bonding surface from progressing in the X direction.

[0029] The above-described embodiments and modifications are merely examples described to facilitate understanding of the invention. The technical scope of the invention is not limited to the specific technical matters disclosed in the above-described embodiments and modifications, but also includes various modifications, changes, alternative technologies, etc. that can be easily derived therefrom.

[0030] REFERENCE SIGNS LIST 10 honeycomb structure 11, 11A, 11B corrugated sheet 12 first cell 13 space 14 partition wall 20 second cell 21 cell forming wall 22 first joining wall 23 second joining wall 24 space

Claims

1. A honeycomb structure comprising: a plurality of first cells arranged in a honeycomb pattern and joined in a first direction; and second cells provided in the partition walls of two of the plurality of first cells that are adjacent to each other in the first direction, wherein the partition walls include cell forming walls that form the second cells, and first and second joining walls that are separated from each other via the cell forming walls, and wherein a first plane that forms the first joining wall and a second plane that forms the second joining wall are not located on the same plane.

2. The honeycomb structure according to claim 1, wherein the second cells located on both sides of each of the first cells in a second direction perpendicular to the first direction are offset from each other in the first direction.

3. The honeycomb structure according to claim 1, wherein the second cells located on both sides of each of the first cells in a second direction perpendicular to the first direction are aligned in the second direction.

4. A honeycomb structure according to claim 2 or 3, wherein the cell forming walls are curved in a cross section perpendicular to the extension direction of the plurality of first cells.

5. A honeycomb structure according to claim 2 or 3, wherein the first joint wall and the second joint wall are both bonded at their joints.

6. The honeycomb structure according to claim 5, wherein the second cells are filled with an adhesive.

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