honeycomb structure and matrix

Abstract

Honeycomb structure (1), comprising: a plurality of cells (2) that are adjacent to each other and have a square cross-section; a plurality of cell walls (3, 3e-h) that form the plurality of cells; and an outer circumferential wall (4) that is provided outside the plurality of cell walls (3, 3e-h) and that holds the cell walls (3, 3e-h), wherein, viewed in a cross-section perpendicular to a honeycomb central axis (10), the honeycomb structure (1) satisfies the following requirements 1 to 5: Requirement 1: the honeycomb structure (1) comprises a central region (11) with cell walls (3, 3e-h) having a wall thickness equal to the wall thickness of a cell wall (3, 3e-h) of four surrounding cells (200) around the honeycomb central axis (10) or the wall thickness of a cell wall (3, 3e-h) of a central cell (20, 201) with a cell center through which the honeycomb central axis (10) passes, and the honeycomb structure (1) comprises a reinforced outer perimeter region (12) with cell walls (3, 3e-h) around the central region (11), wherein the cell walls (3, 3e-h) have a wall thickness greater than the wall thickness of the cell wall (3, 3e-h) of the surrounding cells or the cell wall (3, 3e-h) of the central cell (20, 201); Requirement 2: A plurality of cells (2) arranged on an imaginary parallel line (L1) passing through the honeycomb central axis (10) and parallel to cell walls (3, 3e-h), or a plurality of cells arranged along an imaginary perpendicular line (L2) passing through the honeycomb central axis and orthogonal to cell walls (3, 3e-h) such that it extends through the midpoints of the cell walls (3, 3e-h), comprising a reference boundary cell (21) with cell walls (3, 3e-h) having different wall thicknesses on two sides parallel to the imaginary parallel line (L1) or the imaginary perpendicular line (L2), wherein the reference boundary cell (21) has a thin wall (3a) that is a thin cell wall on one side parallel to the imaginary parallel line or the imaginary perpendicular line and has a wall thickness that is designated as t1 is designated as a thick wall (3c),comprising a thick cell wall (3) on the other side parallel to the imaginary parallel line or the imaginary perpendicular line and having a wall thickness designated t3, an inner wall (3b) that is a cell wall (3, 3e-h) adjacent to a honeycomb center and orthogonal to the imaginary parallel line (L1) or the imaginary perpendicular line (L2) and having a wall thickness designated t2, and an outer wall (3d) that is a cell wall (3, 3e-h) adjacent to a honeycomb perimeter and orthogonal to the imaginary parallel line or the imaginary perpendicular line and having a wall thickness designated t4, wherein the following applies: , t 1 < t 3, t 2 < t 4, t 1 = t 2, and t 3 = t 4 ; Requirement 3: The honeycomb structure (1) comprises the following: a first cross-shaped reference unit (31) with four cell walls (3, 3e-h): the thin wall (3a), the inner wall (3b), a cell wall (3, 3e-h) extending in a direction opposite to that of the thin wall (3a) from a first reference cell vertex (311) corresponding to a connection between the thin wall (3a) and the inner wall (3b), and a cell wall (3, 3e-h) extending from the first reference cell vertex (311) in a direction opposite to that of the inner wall (3b), and a second cruciform reference unit (32) with four cell walls (3, 3e-h): the thick wall (3c), the outer wall (3d), a cell wall (3, 3e-h) extending in a direction opposite to the thick wall (3c) from a second reference cell vertex (322) corresponding to a connection between the thick wall (3c) and the outer wall (3d), and a cell wall extending from the second reference cell vertex (322) in a direction opposite to the outer wall (3d); Requirement 4: the honeycomb structure (1) comprises a plurality of cross-shaped units (33), each having four cell walls (3, 3e-h) extending vertically and horizontally from one another and connected to each other at alternating cell vertices (330) arranged along the cell walls (3, 3e-h) from the first reference cell vertex (311) or the second reference cell vertex (322) as the starting point; and Requirement 5: For each cross-shaped unit (33) in the central region (11) and in the reinforced outer edge region, the cell walls (3, 3e-h) of each of the cross-shaped units have a substantially equal wall thickness.

Description

[Technical field]

[0001] The present disclosure relates to a honeycomb structure and a matrix, and in particular to a honeycomb structure with square cells in cross-section and a matrix. [State of the art]

[0002] DE 10 2014 200 676 A1 discloses a honeycomb structure comprising a central section, an outer perimeter section, and a boundary partition. The central section has basal central cell walls and reinforced central cell walls. The outer perimeter section has basal outer perimeter cell walls and reinforced outer perimeter cell walls.The body satisfies R1 / P1 ≥ 0.5, R2 / P2 ≥ 0.5, T10 ≥ T20, T11 > T21, T3 > T10, T2 > T20, T3 ≥ T11 and T3 > T21, where R1 represents a distance from the boundary septum in a radial inward direction of the body, P1 represents an average cell axis distance in the central part, R2 represents a distance from the boundary septum in a radial outward direction of the body, P2 represents an average cell axis distance in the outer circumferential part, T10 represents an average thickness of the basal central cell walls, T20 represents an average thickness of the basal outer circumferential cell walls, T11 represents an average thickness of the reinforced central cell walls, T21 represents an average thickness of the reinforced outer circumferential cell walls and T3 represents an average thickness of the boundary septum. indicates.

[0003] DE 199 62 544 A1 discloses a method for coating a ceramic honeycomb body with a suspension. The honeycomb body has a cylindrical shape with two end faces and a lateral surface and is traversed from one end face to the other by axially parallel channels formed by channel walls. The coating of the honeycomb body is carried out using suitable methods. The method is characterized in that the honeycomb body is partially moistened and then coated.

[0004] In the automotive sector, exhaust gas purification systems for cleaning exhaust gases from combustion engines have traditionally been used. An exhaust gas purification system comprises a ceramic honeycomb structure contained within an exhaust pipe and a catalyst component held within this structure. The honeycomb structure typically consists of multiple adjacent cells, multiple cell walls forming the cells, and an outer circumferential wall located outside the cell walls to support them. The catalyst component is held against the cell wall surfaces. A typical ceramic honeycomb structure is extruded by inserting a green body, the raw material for the honeycomb structure, into a die.The matrix contains a plurality of green body inlets through which a green body is supplied, and a plurality of slots for receiving the green body supplied through the green body inlets to form part of the cell walls.

[0005] Patent literature 1 discloses a honeycomb structure with a plurality of cells having a square cross-section. In the honeycomb structure, the cells from the starting cell, which is an outermost peripheral cell, to the end cell, which is any cell in the range from the 5th to the 20th cell, have a cell partition thickness that is greater than a basic cell partition thickness. [Citation list][Patent literature]

[0006] [PTL 1] JP 4 473 505 B2 [Summary of the invention]

[0007] Recently tightened emissions control and fuel efficiency regulations require exhaust aftertreatment systems to have shorter warm-up times and lower pressure drops. Consequently, the cell walls of honeycomb structures have become thinner year after year. However, thinner walls reduce the structural strength of the honeycomb structure. This means that during a canning process, where the honeycomb structure containing the catalyst component is housed in an exhaust pipe, the structure is susceptible to fracture due to radially applied compressive stress.

[0008] As described above, techniques for preventing breakage during preservation include a method of improving structural strength by thickening the cell walls across the surface of several cells from the outer perimeter of the honeycomb structure toward the central axis. However, excessive cell wall thickening would lead to local distortion during extrusion of the honeycomb structure, such as a thin-walled area or a lack of green body at the outer perimeter of the article. Such a defect is induced because the cell wall arrangement requires a green body to be loaded from a green body inlet in a die into a plurality of slots of varying widths. More precisely, when a green body is loaded from a green body inlet in a die into a plurality of slots of varying widths, the resulting defect is caused by a lack of green body thickness.When filled, the green matter does not flow evenly into narrow slots, which offer high resistance to the flow of the green matter. As a result, distortions such as those described above tend to be induced.

[0009] Thus, a conventional honeycomb structure with a reinforced outer perimeter has a cell wall arrangement that can cause local deformation during extrusion, and this deformation can be a starting point for fracture, reducing structural strength and making it difficult to prevent fracture caused by stress concentration during the canning process.

[0010] The purpose of the present disclosure is to provide a honeycomb structure which, even with thickened outer peripheral cell walls, avoids a reduction in structural strength due to deformation and thus fracture due to stress concentration during canning, as well as a matrix for forming the honeycomb structure.

[0011] This problem is solved by the subject matter of claims 1 and 8. Advantageous further developments are found in the respective dependent claims.

[0012] One aspect of the present disclosure is a honeycomb structure with a plurality of cells lying side by side and having a square cross-section, a plurality of cell walls forming the plurality of cells, and an outer circumferential wall provided outside the plurality of cell walls and holding the cell walls, and viewed in a cross-section perpendicular to a honeycomb central axis, the honeycomb structure fulfills requirements 1 to 5: Requirement 1: The honeycomb structure comprises a central region with cell walls having a wall thickness equal to the wall thickness of a cell wall of four surrounding cells around the honeycomb central axis or the wall thickness of a cell wall of a central cell whose cell center is penetrated by the honeycomb central axis, and a reinforced outer perimeter region with cell walls around the central region, wherein the cell walls have a wall thickness greater than the wall thickness of the cell wall of the surrounding cell or the cell wall of the central cell; Requirement 2: A plurality of cells arranged on an imaginary parallel line passing through the honeycomb's central axis and parallel to cell walls, or a plurality of cells arranged along an imaginary perpendicular line passing through the honeycomb's central axis and orthogonal to cell walls such that it extends through the centers of the cell walls, comprising a reference boundary cell with cell walls of different thicknesses on two sides parallel to the imaginary parallel line or the imaginary perpendicular line, and wherein the reference boundary cell comprises a thin wall, which is a thin cell wall on one side parallel to the imaginary parallel line or the imaginary perpendicular line and has a wall thickness represented as t1; a thick wall, which is a thick cell wall on the other side parallel to the imaginary parallel line or the imaginary perpendicular line and has a wall thickness represented as t3; an inner wall, which is a cell wall adjacent to the honeycomb center and orthogonal to the imaginary parallel line or the imaginary perpendicular line and has a wall thickness represented as t2; and an outer wall, or outer wall, which is a cell wall adjacent to the honeycomb perimeter and orthogonal to the imaginary parallel line or the imaginary perpendicular line and has a wall thickness represented as t4. t1 <t3,t2<t4,t1=t2, und t3=t4; Requirement 3: The honeycomb structure includes the following: a first cruciform reference unit with four cell walls: the thin wall, the inner wall, the cell wall extending in the opposite direction to the thin wall from a first reference cell vertex corresponding to the connection between the thin wall and the inner wall, and the cell wall extending from the first reference cell vertex in the opposite direction to the inner wall, and a second cruciform reference unit with four cell walls: the thick wall, the outer wall, the cell wall extending in the opposite direction to the thick wall from a second reference cell vertex corresponding to the connection between the thick wall and the outer wall, and the cell wall extending from the second reference cell vertex in the opposite direction to the outer wall; Requirement 4: the honeycomb structure comprises a plurality of cross-shaped units, each having four cell walls extending vertically and horizontally from one another and connected to each other at alternating cell vertices arranged along the cell walls from the first reference cell vertex or the second reference cell vertex as the starting point; and Requirement 5: For each cross-shaped unit in the central area and in the reinforced outer edge area, the cell walls of each of the cross-shaped units have a substantially equal wall thickness.

[0013] Another aspect of the present disclosure is a die for extruding a honeycomb structure comprising a plurality of adjacent cells with a square cross-section, a plurality of cell walls forming the plurality of cells, and an outer circumferential wall provided outside the plurality of cell walls and holding the cell walls, and comprising the die: a first matrix section with a plurality of green body inlets through which a green body is supplied as raw material for the honeycomb structure; and a second matrix section with a plurality of slots for receiving the green body supplied through the green body inlets, in order to form a section as the plurality of cell walls in the honeycomb structure.

[0014] The second matrix section contains a central slot region with slots forming a section as cell walls with a wall thickness equal to the wall thickness of a cell wall of four surrounding cells around the honeycomb central axis or the wall thickness of a cell wall of a central cell with the cell center, the honeycomb central axis passing through it, and a peripheral slot region with slots around the central slot region, the slots being wider than the slots of the central slot region. the majority of the green body inlets are not positioned at all slot vertices, which each correspond to the slot connection between four slots, and are positioned at alternating slot vertices along the slots, and the four slots, which extend radially from the slot apex next to each green body inlet, have essentially the same width.

[0015] The honeycomb structure has the configuration described above, and for each cross-shaped unit in the central region and the reinforced outer edge region, the cell walls of each cross-shaped unit have a substantially uniform wall thickness. Therefore, when the honeycomb structure is extruded through a die with multiple green body inlets and multiple slots, the cross-shaped units can be formed without feeding a green body to all slot vertices, which correspond to the slot connections between each set of four slots. The cross-shaped units can be formed by feeding a green body from the one corresponding green body inlet to each of the alternating slot vertices along the slots, and the green body being evenly distributed from the slot vertex to the four slots of equal width.More precisely, the honeycomb structure comprises cross-shaped units, each with cell walls of uniform thickness. This reduces the variance in resistance to green body flow between the four slots extending from the slot apex during the formation of each cross-shaped unit. Consequently, while the honeycomb structure has a reinforced outer edge, it is less likely to be locally distorted during extrusion. Therefore, the honeycomb structure avoids a reduction in structural strength due to deformation and prevents fracture caused by stress concentration during canning.

[0016] The die has the configuration described above. Therefore, when the honeycomb structure is extruded through the die, it is possible that the green body will not be fed to all slot vertices corresponding to the slot connections between each set of four slots. The green body can be guided from the one corresponding green body inlet along the slots to each of the alternating slot vertices and, from the slot vertex, distributed evenly to the four slots of equal width. More precisely, the die, in which the four slots extending radially from the slot vertex adjacent to each green body inlet have substantially the same width, allows for a reduction in the variance of resistance to green body flow between the four slots. Accordingly, the die reduces the possibility of local deformation occurring during the extrusion of the reinforced outer edge region.of the outer peripheral area of ​​the honeycomb structure. Therefore, the die can form the honeycomb structure, which is able to avoid a reduction in structural strength due to deformation.

[0017] It should be noted that reference numbers in parentheses in the claims refer to correspondences with certain parts mentioned in embodiments described later and do not limit the technical scope of the present disclosure. [Brief description of the drawings]

[0018] The above-mentioned and other objects, features and advantages of the present disclosure will be clearly evident from the detailed description given below with reference to the accompanying drawings: Fig. Figure 1 is a schematic diagram showing the cell wall arrangement of a honeycomb structure according to a first embodiment; Fig.Figure 2 is a diagram illustrating the concept of a reference boundary cell, a cross-shaped reference unit, and a cross-shaped unit for a honeycomb structure with four surrounding cells around the honeycomb central axis; Fig. Figure 3 is a diagram illustrating a method for counting the number of reinforced cells in a reinforced outer border area; Fig. Figure 4 is a schematic diagram showing the cell wall arrangement of a honeycomb structure according to a second embodiment; Fig. Figure 5 illustrates the concept of a reference boundary cell, a cross-shaped reference unit, and a cross-shaped unit for a honeycomb structure with a central cell whose cell center is traversed by the honeycomb central axis; Fig. Figure 6 is a schematic diagram showing the cell wall arrangement of a honeycomb structure according to a third embodiment; Fig.Figure 7 is a schematic diagram showing the cell wall arrangement of a honeycomb structure according to a fourth embodiment; Fig. Figure 8 is a schematic diagram showing the cell wall arrangement of a honeycomb structure according to a fifth embodiment; Fig. Figure 9 is a schematic diagram showing part of a die according to a sixth embodiment; Fig. Figure 10 is a diagram illustrating the positional relationship between green body inlets and slot vertices in the die according to the sixth embodiment; Fig. Figure 11 is a schematic representation of the flow pattern of a green body, which is guided from the green body inlets to the slot vertices in the die according to the sixth embodiment; Fig. Figure 12 is a diagram illustrating a feed ratio in the die according to the sixth embodiment; Fig. Figure 13 is a diagram illustrating a method for evaluating pressure loss in experimental example 3; Fig. Figure 14 is a diagram showing the relationship between the isostatic strength and the number of reinforced cells in the reinforced outer edge region in experimental example 3; Fig. Figure 15 is a diagram showing the relationship between the pressure loss and the number of reinforced cells in the reinforced outer edge area in experimental example 3; Fig. Figure 16 is a diagram showing the relationship between the stress ratio and the number of cells of the outer circumferential wall of a honeycomb structure according to the CAE analysis in experimental example 3; Fig.Figure 17 is a diagram showing the relationship between the isostatic strength and the wall thickness of the cell wall of the first cell in the reinforced outer edge region in experimental example 5; and Fig. Figure 18 is a schematic diagram illustrating the cell wall arrangement of a conventional honeycomb structure, shown as Pattern 1 in Experiment 1. [Description of embodiments](First embodiment)

[0019] A honeycomb structure according to a first embodiment is now demonstrated using the Fig. 1, Fig. 2 to Fig. 3 described. As in Fig.Figure 1 shows a honeycomb structure 1 according to the present embodiment, made of ceramic (e.g., cordierite), comprising a plurality of adjacent cells 2 with a square cross-section, a plurality of cell walls 3 forming the plurality of cells 2, and an outer circumferential wall 4 located outside the plurality of cell walls 3 and holding the cell walls 3. For simplicity, the thickness of each cell wall 3 is represented by the thickness of the line in each figure.

[0020] In the present embodiment, the cells 2 are through-holes extending along a honeycomb central axis 10 that passes through the center of the honeycomb structure 1. The cells 2 serve as flow channels through which the exhaust gas to be cleaned flows. It should be noted that the cross-section in the above phrase "quadrilateral in cross-section" means a cross-section perpendicular to the honeycomb central axis 10. The "quadrilateral" in the above phrase "quadrilateral in cross-section" is not necessarily limited to a square and may also mean quadrilaterals other than a square, including a quadrilateral with rounded corners and a quadrilateral that was accidentally warped during manufacturing. Each of the cell walls 3 is connected and integrated with the adjacent cell walls 3. Each cell wall 3 has a catalyst component that is carried on the wall surfaces facing the cells 2 when the honeycomb structure 1 is in use.The outer perimeter wall 4 is circular, as seen in a cross-section perpendicular to the honeycomb's central axis 10. The outer perimeter wall 4 has an inner surface that is connected to a plurality of cell walls 3 which adjoin the inner surface of the outer perimeter wall 4. Thus, the cell walls 3 are integrally held by the outer perimeter wall 4.

[0021] The honeycomb structure 1 fulfills the requirements 1 to 5 described below, as seen in a cross-section perpendicular to the honeycomb central axis 10. Each requirement will now be described. Requirement 1

[0022] The honeycomb structure comprises a central region with cell walls having a wall thickness equal to that of the cell walls of the four surrounding cells around the central axis of the honeycomb, and a reinforced outer perimeter region with cell walls around the central region that have a greater wall thickness than that of the cell walls of the surrounding cells. Requirement 1 will now be described in more detail.

[0023] As in Fig.As shown in Figure 1, the honeycomb structure 1 comprises a central region 11 and a reinforced outer perimeter region 12. If the four cells 2 surrounding the honeycomb central axis 10 are defined as surrounding cells 200, the central region 11 has cell walls 3 with a wall thickness equal to that of the cell walls 3 of the surrounding cells 200. Each surrounding cell 200 has four cell walls 3 that separate it from the surrounding cells 2. In the four surrounding cells 200, each of the cell walls 3 extending vertically and horizontally from the honeycomb central axis 10 is divided perpendicular to it by the adjacent surrounding cells 200. The wall thickness of the cell walls 3 of the surrounding cells 200 is specifically represented as the average of the wall thicknesses of the cell walls 3 that comprise the four surrounding cells 200. The central area 11 essentially comprises several cell walls 3 which are not thickened compared to the reinforced outer marginal area 12.It should be noted that when calculating the wall thickness of the cell walls 3 arranged around the surrounding cells 200 in the central area 11, the wall thickness of some thickened cell walls 3 inserted from the reinforced outer edge area 12 into the central area 11 is excluded with respect to the requirement 5 described later.

[0024] The reinforced outer edge region 12 has cell walls 3 around the central region 11 that have a greater wall thickness than the cell walls 3 of the surrounding cells 200. More precisely, the reinforced outer edge region 12 comprises several cell walls 3 that are thicker compared to the central region 11. In the present embodiment, as shown in Fig.As shown in Figure 1, each cell wall 3 in the reinforced outer edge region 12 has the same wall thickness. As described later in another embodiment, the reinforced outer edge region 12 can comprise thickened cell walls 3 with different wall thicknesses, as long as the requirement described later in Figure 5 is met. Requirement 2

[0025] The majority of cells arranged on an imaginary parallel line passing through the honeycomb's central axis and parallel to the cell walls includes a reference boundary cell with cell walls of different thicknesses on both sides parallel to the imaginary parallel line, and wherein the reference boundary cell comprises a thin wall, which is a thin cell wall on one side parallel to the imaginary parallel line and has a wall thickness represented as t1, a thick wall, which is a thick cell wall on the other side parallel to the imaginary parallel line and has a wall thickness represented as t3, an inner wall, which is a cell wall adjacent to the honeycomb center and orthogonal to the imaginary parallel line and has a wall thickness represented as t2, and an outer wall, which is a cell wall adjacent to the honeycomb perimeter and orthogonal to the imaginary parallel line and has a wall thickness represented as t4, t1 < t3, t2 < t4, t1 = t2 and t3 = t4. Requirement 2 is now described.

[0026] Fig.Figure 1 shows the dashed lines L10, L190, L1180 and L1270, which run through the honeycomb central axis 10 and parallel to the cell walls 3. If in Fig. 1. It is assumed that a dashed line runs through the honeycomb central axis 10 and parallel to the cell walls 3 (in Fig. 1 the dashed line L10 in the direction of 12 o'clock), in the 0-degree direction, the directions of the dashed lines L190, L1180 and L1270 at 90 degrees, 180 degrees and 270 degrees clockwise from the dashed line L 10 are the 90-degree direction, the 180-degree direction and the 270-degree direction. Fig. Figure 2 is an enlarged view of cells 2 and cell walls 3 near L10, L190, L1180 or L1270 in Fig. 1.

[0027] As in Fig.As shown in Figure 1, the dashed lines L10, L190, L1180, and L1270 extend in the four directions of 90 degrees × n (note that n = 0, 1, 2, and 3) through the honeycomb central axis 10 and are parallel to the cell walls 3, and thus each of them is the imaginary parallel line L1 in requirement 2. The imaginary parallel line L1 is a straight line that runs radially through the honeycomb central axis 10. In each of the directions of 90 degrees × n (note that n = 0, 1, 2 and 3), when the majority of the cells 2 arranged on the imaginary parallel line L1 are viewed from the outer circumferential wall 4 in the direction of the honeycomb central axis 10, a cell 2 with cell walls 3 that differ in thickness from the neighboring cells 2 appears at a certain location, as shown in Fig.Figure 2 shows that the cell walls 3 on the two sides parallel to the imaginary parallel line L1 have different thicknesses. This cell 2 is a reference boundary cell 21.

[0028] The reference boundary cell 21 will now be discussed in more detail. In the reference boundary cell 21, the wall thickness of a thin wall 3a, i.e., the thin cell wall 3 on one side parallel to the imaginary parallel line L1, is represented as t1. The wall thickness of a thick wall 3c, i.e., the thick cell wall 3 on the other side parallel to the imaginary parallel line L1, is represented as t3. The wall thickness of an inner wall 3b, i.e., the cell wall 3 that borders the center of the honeycomb and is orthogonal to the imaginary parallel line L1, is represented as t2. The wall thickness of an outer wall 3d, i.e., the cell wall 3 that borders the perimeter of the honeycomb and is orthogonal to the imaginary parallel line L1, is represented as t4. Then, for the reference boundary cell 21, t1 < t3, t2 < t4, t1 = t2 and t3 = t4.

[0029] The above-mentioned wall thicknesses of the thin wall 3a, the thick wall 3c, the outer wall 3d and the inner wall 3b of the reference boundary cell 21 are each the average wall thickness measurement of the thin walls 3a, the average wall thickness measurement of the thick walls 3c, the average wall thickness measurement of the inner walls 3b and the average wall thickness measurement of the outer walls 3d of the reference boundary cell 21, which appear similar in the directions 90 degrees × n (note that n = 0, 1, 2 and 3). Requirement 3

[0030] The honeycomb structure includes the following: a first cruciform reference unit with four cell walls: a thin wall, an inner wall, a cell wall extending in the opposite direction to the thin wall from a first reference cell vertex corresponding to the connection between the thin wall and the inner wall, and a cell wall extending from the first reference cell vertex in the opposite direction to the inner wall, and A second cross-shaped reference unit with four cell walls: a thick wall, an outer wall, a cell wall extending in the opposite direction to the thick wall from a second reference cell vertex corresponding to the junction between the thick wall and the outer wall, and a cell wall extending from the second reference cell vertex in the opposite direction to the outer wall. Requirement 3 is now described.

[0031] As in Fig.As shown in Figure 2, a first cross-shaped reference unit 31 is defined by four cell walls 3: a thin wall 3a, an inner wall 3b, a cell wall 3e extending in the opposite direction to the thin wall 3a from a first reference cell vertex 311 corresponding to the connection between the thin wall 3a and the inner wall 3b, and a cell wall 3f extending from the first reference cell vertex 311 in the opposite direction to the inner wall 3b. A second cruciform reference unit 32 is defined by four cell walls 3: a thick wall 3c, an outer wall 3d, a cell wall 3g extending in the opposite direction to the thick wall 3c from a second reference cell vertex 322 corresponding to the connection between the thick wall 3c and the outer wall 3d, and a cell wall 3h extending from the second reference cell vertex 322 in the opposite direction to the outer wall 3d.

[0032] The wall thicknesses of cell wall 3e, cell wall 3f, cell wall 3g and cell wall 3h are each the average wall thickness measurement of cell walls 3e, the average wall thickness measurement of cell walls 3f, the average wall thickness measurement of cell walls 3g and the average wall thickness measurement of cell walls 3h of the reference boundary cells 21, which appear similar in the directions 90 degrees × n (note that n = 0, 1, 2 and 3). Requirement 4

[0033] The honeycomb structure comprises a plurality of cross-shaped units, each of which has four cell walls extending vertically and horizontally from one another and connected to each other at alternating cell apex points arranged along the cell walls from the first reference cell apex or the second reference cell apex as the starting point. Requirement 4 is now described.

[0034] The honeycomb structure 1 comprises sets of cell walls, each with four cell walls 3, extending radially from the corresponding cell apex 330 of a plurality of cells 2. As in Fig. As shown in Figure 1, the central region 11 and the reinforced outer edge region 12 each have two possibilities for how the cell wall sets can be selected. In one case, the honeycomb structure 1 can comprise a plurality of cell wall sets with four cell walls 3, which extend radially from the ones shown in Figure 1. Fig. 1 shown circular cell apex 330 extend. In the other case, the honeycomb structure 1 can comprise a plurality of cell wall sets with four cell walls 3, extending radially from the one shown in Fig. The unrounded cell vertex shown extends to 330.

[0035] Requirement 4 specifies the selection of one of the two cell wall sets mentioned above. More precisely, the cross-shaped units 33 are cell wall sets, each comprising four cell walls 3 extending vertically and horizontally from the cell walls 3 and connected to one another at alternating cell vertices 330. These cell walls are arranged along the cell walls 3 from the first reference cell vertex 311 or the second reference cell vertex 322, which is defined as the starting point in requirement 3. The cross-shaped units 33 in the present embodiment are therefore the cell wall sets in which the four cell walls 3 extend radially from the cell walls 3 defined in requirement 311. Fig. The circular cell apex 330 shown in 1 extend. Accordingly, the cell wall sets with the four cell walls 3, which extend radially from the in Fig. 1 shown unrounded cell vertices extend 330, not as cross-shaped units 33.

[0036] The honeycomb structure 1 comprises a plurality of cross-shaped units 33. More precisely, the honeycomb structure 1 has a cell arrangement in which adjacent cross-shaped units 33 are connected to each other. Requirement 5

[0037] For each cross-shaped unit in the central region and in the reinforced outer edge region, the cell walls of each of the cross-shaped units have a substantially equal wall thickness. Requirement 5 is now described.

[0038] The cross-shaped units 33 specified in the above-mentioned requirement 4 are minimum units for forming cells 2 with a square cross-section. In the present embodiment, as described in Fig.As shown in more detail in Figure 1, each cruciform unit 33 with its cell apex 330 within the central region 11 has cell walls 3 of the same wall thickness, and the cell walls 3 of a single cruciform unit 33 are also as thick as those of any other cruciform unit 33. For the cruciform units 33 with their cell apex 330 within the reinforced outer border region 12, each cruciform unit 33 has cell walls 3 of the same wall thickness, and all cell walls 3 of each cruciform unit 33 are thicker than the cell walls 3 of each cruciform unit 33 with its cell apex 330 within the central region 11.

[0039] The honeycomb structure 1 has the configuration described above, and for all cross-shaped units 33 within the central region 11 and the reinforced outer edge region 12, each cross-shaped unit 33 has cell walls 3 of the same wall thickness. Thus, for example, as described later in a sixth embodiment, when extruding the honeycomb structure 1 through a die 5 with a plurality of green body inlets 510 and a plurality of slots 520, the cross-shaped units 33 can be formed without supplying a green body to all slot vertices 521, which correspond to the slot connections between each group of four slots 520.The cross-shaped units 33 can be formed by feeding a green body from the one corresponding green body inlet 510 along the slots 520 to each of the alternating slot vertices 521, and by distributing the green body evenly from the slot vertex 521 into the four slots 520 of equal width. More precisely, the honeycomb structure 1 comprises the cross-shaped units 33, each of which has cell walls 3 of the same wall thickness, thus enabling a reduction in the variance in resistance to green body flow between the four slots 520 extending from the slot vertex 521 during the formation of each cross-shaped unit 33. Accordingly, while the honeycomb structure 1 has the reinforced outer edge region 12, it is less susceptible to local deformation during extrusion.Therefore, the honeycomb structure 1 is able to avoid a reduction in structural strength due to deformation and to prevent breakage due to stress concentration during canning.

[0040] The honeycomb structure 1 can have a wall thickness difference ratio of 10% or less, calculated according to the formula: 100 × (tmax - tmin) / tmax, where tmax denotes the maximum wall thickness of the four cell walls 3, each forming the cross-shaped unit 33, and tmin denotes the minimum wall thickness.

[0041] When each cross-shaped unit 33 of the honeycomb structure 1 is formed, the above configuration facilitates the reduction of the variance in resistance to green body flow between the four slots 520 extending from the slot vertex 521 and reduces the possibility of the occurrence of shape defects such as unconnected cell walls 3 between adjacent cross-shaped units 33. Thus, the above configuration enables the fabrication of the honeycomb structure 1 with sufficient average isostatic strength and minimal isostatic strength, even if the materials may vary. The above configuration also enables the fabrication of the honeycomb structure 1, which effectively reduces the defect rate associated with distortion.

[0042] To ensure the structural strength of the honeycomb structure 1, the wall thickness difference ratio can preferably be less than 10%, more preferably 9% or less, even more preferably 8% or less, even more preferably 7% or less, and even more preferably 6% or less. The wall thickness difference ratio can even more preferably be 5% or less. Even with different wall thicknesses, such a wall thickness difference ratio can reduce the possibility of forming a cross-shaped unit 33 with distortion, which can reduce the structural strength of the honeycomb structure 1.

[0043] In the honeycomb structure 1, the number of cells enclosed in the reinforced outer edge area 12 by the outer circumferential wall 4 in the direction of the honeycomb central axis 10 is determined in the manner described below.

[0044] In each of the directions of 90 degrees × n (note that n = 0, 1, 2, and 3), the first cell is considered to be cell 2 on the imaginary parallel line L1 and on the outer perimeter wall 4. Although cell 2 on the outer perimeter wall 4 is not normally square in cross-section, such an incomplete cell also counts as cell 2. In each of the directions of 90 degrees × n (note that n = 0, 1, 2, and 3), the number of cells 2 arranged on the imaginary parallel line L1 is counted from the first cell in the direction of the honeycomb's central axis 10. Then, as shown in Fig.Figure 3 shows that at the (m+1)th cell of cell 2 on the outer circumferential wall 4, there is a cell 2 which has a cruciform unit 33 formed from the cell walls 3, the wall thickness being equal to that of the cell walls 3 of the surrounding cells 200. Note that m is a natural number. The (m+1)th cell 2 and the preceding mth cell 2 have between them a bounding cell wall 3, which is called the inner-outer boundary wall 30. The inner-outer boundary wall 30 is divided in the wall thickness direction into two parts by an angle bisector T, and an imaginary circle C is drawn that is tangent to the angle bisector T. The imaginary circle C is a concentric circle whose center coincides with the honeycomb central axis 10.If the cell walls 3 of the cross-shaped units 33, with their cell vertices 330 outside the imaginary circle C, are reinforced such that they are thicker than the cell walls 3 of the surrounding cells 200, the reinforced outer border region 12 extends to the m-th cell 2 in the direction from the outer circumferential wall 4 to the honeycomb central axis 10. In other words, the reinforced outer border region 12 comprises m reinforced cells. The imaginary circle C is the boundary circle between the central region 11 and the reinforced outer border region 12. However, with respect to requirement 5 described above, the central region 11 may include some cell walls at its periphery that are 3 times thicker than the cell walls 3 of the surrounding cells 200. With respect to requirement 5 described above, for examplethe periphery of the central area 11 some of the cell walls 3 of the cruciform units 33 with their cell vertices 330 within the reinforced outer peripheral area 12 or marginal area 12 exhibit.

[0045] For the honeycomb structure 1 in Fig. Figure 1 shows an example of the present embodiment in which the reinforced outer edge region 12 extends to the fourth cell 2 in the direction from the outer circumferential wall 4 towards the honeycomb central axis 10, assuming that the reinforced outer edge region 12 comprises four reinforced cells. The present embodiment also shows an example in which the cell walls 3 forming the cells 2 in the reinforced outer edge region 12 have a substantially uniform wall thickness between the first and fourth cells 2 from the outer circumferential wall 4 towards the honeycomb central axis 10.

[0046] In the honeycomb structure 1, the reinforced outer edge region 12 is preferably a region extending from the outer circumferential wall 4 to the fourth or each subsequent cell 2 in the direction of the honeycomb central axis 10. This is because the honeycomb structure 1 with its reinforced outer edge region 12 with four or more reinforced cells advantageously exhibits isostatic strength that can be improved more easily than a honeycomb structure 1 with its reinforced outer edge region 12 with fewer than four reinforced cells. Furthermore, CAE analysis revealed that the stress generated in the honeycomb structure 1 with cells 2 having a square cross-section increases towards the outer periphery. In particular, the region extending from the outer circumferential wall 4 to the fourth cell 2 in the direction of the honeycomb central axis 10 exhibits a high stress concentration during canning.Thus, the above configuration enables effective prevention of breakage due to stress concentration during the canning process and has the advantage that the structural strength of the honeycomb structure 1 can be easily improved.

[0047] To ensure the above-mentioned effects, the reinforced outer edge area 12 can preferably be an area extending from the outer circumferential wall 4 to the fifth or each subsequent cell 2 in the direction of the honeycomb central axis 10.

[0048] In the honeycomb structure 1, the reinforced outer edge region 12 is preferably a region extending from the outer circumferential wall 4 to the 20th or any preceding cell 2 in the direction of the honeycomb central axis 10. Even if the reinforced outer edge region 12 extends to any cell 2 after the 20th cell in the direction from the outer circumferential wall 4 to the honeycomb central axis 10, the structural strength of the honeycomb structure 1 is not significantly improved. The number of cells in the honeycomb structure 1 increases towards the outer periphery. Accordingly, thickening the cell walls 3 adjacent to the outer periphery increases the pressure loss in the honeycomb structure 1. In particular, if the reinforced outer edge region 12 contains more than 20 reinforced cells, the pressure loss in the honeycomb structure 1 tends to increase significantly.Thus, the above configuration enables the avoidance of an increase in pressure loss and a reduction in structural strength due to deformation, as well as the prevention of fractures due to stress concentration during preservation.

[0049] To ensure the effects mentioned above, the reinforced outer peripheral area 12 can preferably be an area extending from the outer circumferential wall 4 to the 18th or any preceding cell 2 in the direction of the honeycomb central axis 10. The honeycomb structure 1 can have a cell density of, for example, 46.5 cells / cm² to 155 cells / cm² (300 cpsi to 1000 cpsi). (Second embodiment)

[0050] A honeycomb structure 1 according to a second embodiment is now described with reference to Fig. 4 and Fig.5 described. Among the reference numerals used in the second and subsequent embodiments, the same reference numerals as in a previous embodiment denote the same or corresponding components as in the previous embodiment, unless otherwise specified.

[0051] The honeycomb structure 1 fulfills the requirements 1 to 5 described below, as seen in a cross-section perpendicular to the honeycomb central axis 10. Each requirement will now be described. Requirement 1

[0052] The honeycomb structure comprises a central region with cell walls having a wall thickness equal to that of the central cell, through whose cell center the honeycomb's central axis passes, and a reinforced outer perimeter region with cell walls surrounding the central region that have a greater wall thickness than that of the central cell. Requirement 1 will now be described in more detail.

[0053] As in Fig.As shown in Figure 1, the honeycomb structure 1 comprises a central region 11 and a reinforced outer perimeter region 12. If the cell 2, with its center through which the honeycomb central axis 10 passes, is defined as a central cell 201, then the central region 11 has cell walls 3 with a wall thickness equal to that of the cell walls 3 of the central cell 201. The central cell 201 has four cell walls 3 that separate it from the surrounding cells 2. The wall thickness of the cell walls 3 of the central cell 201 is specifically represented as the average of the wall thicknesses of the four cell walls 3 surrounding the central cell 201. The central region 11 essentially comprises several cell walls 3 that are not thickened compared to the reinforced outer perimeter region 12.It should be noted that when calculating the wall thickness of the cell walls 3 surrounding the central cell 201 in the central area 11, the wall thickness of some thickened cell walls 3 inserted from the reinforced outer edge area 12 into the central area 11 is excluded with respect to the requirement 5 described later.

[0054] The reinforced outer edge region 12 has cell walls 3 around the central region 11 that have a greater wall thickness than the cell walls 3 of the central cell 201. More precisely, the reinforced outer edge region 12 comprises several cell walls 3 that are thicker compared to the central region 11. In the present embodiment, as in Fig.As shown in Figure 4, each cell wall 3 in the reinforced outer edge region 12 has the same wall thickness. As described later in another embodiment, the reinforced outer edge region 12 can comprise thickened cell walls 3 with different wall thicknesses, as long as the requirement described later in Figure 5 is met. Requirement 2

[0055] The majority of cells arranged along an imaginary vertical line passing through the honeycomb's central axis and orthogonal to the cell walls, such that it extends through the centers of the cell walls, includes a reference boundary cell with cell walls of different thicknesses on both sides parallel to the imaginary vertical line, and wherein the reference boundary cell comprises a thin wall, which is a thin cell wall on one side parallel to the imaginary perpendicular line and has a wall thickness represented as t1, a thick wall, which is a thick cell wall on the other side parallel to the imaginary perpendicular line and has a wall thickness represented as t3, an inner wall, which is a cell wall adjacent to the center of the honeycomb and orthogonal to the imaginary perpendicular line and has a wall thickness represented as t2, and an outer wall, which is a cell wall adjacent to the perimeter of the honeycomb and orthogonal to the imaginary perpendicular line and has a wall thickness represented as t4, t1 <t3,t2<t4,t1=t2, und t3=t4.

[0056] Fig.Figure 4 shows the dashed lines L20, L290, L2180 and L2270, which pass through the honeycomb central axis 10 and orthogonally to the cell walls 3, so that they pass through the centers of the cell walls 3. If in Fig. 4 is assumed to be a dashed line running through the honeycomb central axis 10 and orthogonal to the cell walls 3 (in Fig. 4 the dashed line L20 in the direction of 12 o'clock), in the 0-degree direction, the directions of the dashed lines L290, L2180 and L2270 at 90 degrees, 180 degrees and 270 degrees clockwise from the dashed line L20 are the 90-degree direction, the 180-degree direction and the 270-degree direction. Fig. Figure 5 is an enlarged view of cells 2 and cell walls 3 on and near L20, L290, L2180 or L2270 in Fig. 4.

[0057] As in Fig.As shown in Figure 4, the dashed lines L20, L290, L2180, and L2270 run in the four directions of 90 degrees × n (note that n = 0, 1, 2, and 3) through the honeycomb central axis 10 and are orthogonal to the cell walls 3 in such a way that they extend through the centers of the cell walls 3, and thus each of them is the imaginary perpendicular line L2 in requirement 2. The imaginary perpendicular or perpendicular line L2 is a straight line that runs radially through the honeycomb central axis 10. In each of the directions of 90 degrees × n (note that n = 0, 1, 2 and 3), when the majority of the cells 2 arranged along the imaginary perpendicular line L2 from the outer circumferential wall 4 in the direction of the honeycomb central axis 10, a cell 2 with cell walls 3 that differ in thickness from the neighboring cells 2 appears at a certain location, as in Fig.Figure 5 illustrates this. For cell 2, the cell walls 3 on the two sides running parallel to the imaginary vertical line L2 have different thicknesses. This cell 2 is a reference boundary cell 21. The remainder of requirement 2 is the same as in the first embodiment and is not described again. Furthermore, requirements 3 to 5 are also essentially the same as in the first embodiment and are not described again.

[0058] The honeycomb structure 1 according to the first embodiment described above has a cell arrangement with the four surrounding cells 200 around the honeycomb central axis 10. In contrast, the honeycomb structure 1 according to the present embodiment has a cell arrangement in which the central cell 201 forms the cell center through which the honeycomb central axis 10 passes. Similar to the honeycomb structure 1 according to the first embodiment, the honeycomb structure 1 according to the present embodiment, with its reinforced outer edge region 12, is less susceptible to local deformation during extrusion. Therefore, the honeycomb structure 1 according to the present embodiment avoids a reduction in structural strength due to deformation and prevents fracture due to stress concentration during canning. The other configuration and functional effects are the same as in the first embodiment.

[0059] The method of counting the number of reinforced cells in the reinforced outer edge region 12 of the honeycomb structure 1 according to the present embodiment is understood to mean that “cells 2 arranged on the imaginary parallel line L1” is appropriately translated, according to the method of counting the number of reinforced cells described in the first embodiment, into “cells 2 arranged along the imaginary vertical line L2” according to the present embodiment. (Third embodiment)

[0060] A honeycomb structure according to a third embodiment is now described with reference to Fig. 6 described.

[0061] As in Fig.Figure 6 shows that the honeycomb structure 1 according to the present embodiment is an example in which the reinforced outer edge region 12 extends to the fourth cell 2 in the direction from the outer circumferential wall 4 towards the honeycomb central axis 10. The honeycomb structure 1 according to the present embodiment is similar to the honeycomb structure 1 according to the first embodiment in the reinforced outer edge region 12 with four reinforced cells.

[0062] However, the honeycomb structure 1 in the present embodiment differs from the honeycomb structure 1 according to the first embodiment in that the wall thickness of the cell walls 3, which the cells 2 form in the reinforced outer edge region 12, decreases from the outer circumferential wall 4 in the direction of the honeycomb central axis 10.

[0063] More precisely, in the present embodiment, the wall thickness of the cell walls 3, which form the cells 2 in the reinforced outer edge region 12, is greatest in the first cell 2 in the direction from the outer circumferential wall 4 to the honeycomb central axis 10 and gradually decreases from the outer circumferential wall 4 to the honeycomb central axis 10.

[0064] This configuration makes it possible to avoid an increase in pressure loss and to ensure the structural strength of the honeycomb structure 1 compared to a honeycomb structure 1 in which the cells 2 in the reinforced outer edge region 12 have uniformly thickened cell walls 3. This is because the configuration allows a gradual decrease in stress towards the honeycomb center and minimizes the influence on pressure loss, compared to cases in which the cells 2 in the reinforced outer edge region 12 have uniformly thickened cell walls 3.

[0065] In the reinforced outer edge region 12, the wall thickness of the cell walls 3 forming the Xth cell 2 in the direction from the outer circumferential wall 4 to the honeycomb central axis 10 (note that X is a natural number not less than two and not greater than the number of reinforced cells in the reinforced outer edge region) is the average wall thickness measurement of the cell walls 3 forming the Xth cell 2 in the directions 90 degrees × n (note that n = 0, 1, 2 and 3).

[0066] In the present embodiment, the reinforced outer edge region 12 in particular comprises a plurality of concentric regions around the honeycomb central axis 10, and the cell walls 3 in different concentric regions have different wall thicknesses. An example of the reinforced outer edge region 12 is described below, in which the region including the Xth cell 2 from the outer circumferential wall 4 has cell walls 3 with different wall thicknesses than the region including the preceding (X-1)th cell 2.

[0067] In principle, the method of counting the number of reinforced cells in the reinforced outer edge region 12 described in the first embodiment can be used for the majority of cells 2 arranged on the imaginary parallel line L1 in each of the directions of 90 degrees × n (note that n = 0, 1, 2, and 3). More precisely, in the example above, the Xth cell 2 and the (X-1)th cell 2 have an inner bounding cell wall 3 between them, which is referred to as the inner bounding wall 300. The inner bounding wall 300 is divided into two equal parts in the direction of the wall thickness by an angle bisector (not shown), and an imaginary circle Ci is drawn tangent to the angle bisector. The imaginary circle Ci is a concentric circle whose center coincides with the honeycomb center axis 10.The cell walls 3 of the cruciform units 33, with their cell vertices 330 on and outside the imaginary circle Ci, are thickened such that they are thicker than the cell walls 3 of the cruciform units 33, with their cell vertices 330 inside the imaginary circle Ci. Thus, in the reinforced outer boundary region 12, the region including the (X-1)th cell from the outer perimeter wall 4 can have cell walls that are 3 thicker than the cell walls 3 of the region including the X-th cell 2 from the outer perimeter wall 4.

[0068] In the reinforced outer edge area 12 of the in Fig.In the exemplary honeycomb structure 1 shown in Figure 6, the wall thickness of the cell walls 3 in the area including the fourth cell 2 from the outer perimeter wall 4 is less than the wall thickness of the cell walls 3 in the area including the third cell 2 from the outer perimeter wall 4, less than the wall thickness of the cell walls 3 in the area including the second cell 2 from the outer perimeter wall 4, less than the wall thickness of the cell walls 3 in the area including the first cell 2 from the outer perimeter wall 4.

[0069] In the Fig.In the honeycomb structure 1 shown in Figure 6, an imaginary circle Ci1, drawn within the reinforced outer boundary region 12, is a boundary circle that forms the border between the region of the first cell and the region of the second cell. Similarly, an imaginary circle Ci2, drawn within the reinforced outer boundary region 12, is a boundary circle that forms the border between the region of the second cell and the region of the third cell. An imaginary circle Ci3, drawn within the reinforced outer boundary region 12, is a boundary circle that forms the border between the region of the third cell and the region of the fourth cell. All cruciform units 33, with their cell vertices 330 located between the outer perimeter wall 4 and the imaginary circle Ci1, have cell walls 3 of the same thickness.Similarly, all cross-shaped units 33 with their cell vertices 330 between the imaginary circle Ci1 and the imaginary circle Ci2 have cell walls 3 of the same wall thickness. All cross-shaped units 33 with their cell vertices 330 between the imaginary circle Ci2 and the imaginary circle Ci3 have cell walls 3 of the same wall thickness. All cross-shaped units 33 with their cell vertices between the imaginary circle Ci3 and the imaginary circle C have cell walls 3 of the same wall thickness.

[0070] In the present embodiment, the cell walls 3, which are enclosed in the reinforced outer peripheral region or edge region 12 and form the first cell 2 in the direction from the outer peripheral wall 4 to the honeycomb central axis 10, can be 1.4 or more times and preferably 1.5 or more times as thick as the cell walls 3 that form the surrounding cells 200 in the central region 11.

[0071] This configuration facilitates stress reduction in the area of ​​the first cell, which experiences the highest stress concentration during preservation. Therefore, this configuration has the advantage of slightly improving the structural strength of honeycomb structure 1.

[0072] The wall thickness of the cell walls 3 forming the surrounding cells 200 in the central region 11 is the average wall thickness measurement of the cell walls 3 forming the surrounding cells 200. The other configuration and functional effects are the same as in the first embodiment. (Fourth embodiment)

[0073] A honeycomb structure according to a fourth embodiment is now demonstrated using Fig. 7 described.

[0074] As in Fig.Figure 7 shows that the honeycomb structure 1 according to the present embodiment is an example with a central cell 201, the cell center of which is traversed by the honeycomb central axis 10. In the present embodiment, the method of counting the number of reinforced cells in the reinforced outer peripheral area 12 can also be used in a similar way for the majority of the cells 2, which are arranged along the imaginary vertical line L2 in each of the directions of 90 degrees × n (note that n = 0, 1, 2 and 3) in accordance with the third embodiment.

[0075] The honeycomb structure 1 according to the present embodiment is an example in which the reinforced outer edge region 12 extends to the fourth cell 2 in the direction from the outer circumferential wall 4 towards the honeycomb central axis 10, and the reinforced outer edge region 12 contains four reinforced cells. In the reinforced outer edge region 12 of the honeycomb structure 1, the wall thickness of the cell walls 3 of the region, including the fourth cell 2, is determined by the outer circumferential wall 4. <die Wanddicke der Zellwände 3 des Bereichs einschließlich der dritten Zelle 2 von der äußeren Umfangswand 4 <die Wanddicke der Zellwände 3 des Bereichs einschließlich der zweiten Zelle 2 von der äußeren Umfangswand 4 <die Wanddicke der Zellwände 3 des Bereichs einschließlich der ersten Zelle 2 von der äußeren Umfangswand 4.

[0076] In the present embodiment, the cell walls 3, which are enclosed in the reinforced outer peripheral region or edge region 12 and form the first cells 2 in the direction from the outer peripheral wall or circumferential wall 4 to the honeycomb central axis 10, can be 1.4 or more times and preferably 1.5 or more times as thick as the cell walls 3 that form the central cell 201 in the central region 11.

[0077] This configuration facilitates stress reduction in the area of ​​the first cell, which experiences the highest stress concentration during preservation. Therefore, this configuration has the advantage of slightly improving the structural strength of honeycomb structure 1.

[0078] The wall thickness of the cell walls 3 forming the central cell 201 in the central region 11 is the average wall thickness measurement of the cell walls 3 forming the central cell 201. The remaining configuration and functional effects are the same as in the third embodiment. (Fifth embodiment)

[0079] A honeycomb structure according to a fifth embodiment is now demonstrated using Fig. 8 described.

[0080] As in Fig.Figure 8 shows that the honeycomb structure 1 according to the present embodiment is an example in which the reinforced outer edge region 12 is a region extending from the outer circumferential wall 4 to the third cell 2 in the direction of the honeycomb central axis 10, and the reinforced outer edge region 12 contains three reinforced cells. In the reinforced outer edge region 12 of the honeycomb structure 1, the wall thickness of the cell walls 3 of the region, including the third cell 2, from the outer circumferential wall 4 <die Wanddicke der Zellwände 3 des Bereichs einschließlich der zweiten Zelle 2 von der äußeren Umfangswand 4 <die Wanddicke der Zellwände 3 des Bereichs einschließlich der ersten Zelle 2 von der äußeren Umfangswand 4. Die übrigen Konfigurations- und Funktionseffekte sind die gleichen wie bei der dritten Ausführungsform. (Sixth embodiment)

[0081] A die 5 according to a sixth embodiment is now described with reference to the Fig. 9, Fig. 10 to Fig. 11. According to the present embodiment, the die 5 is a die for extruding a honeycomb structure 1 with a plurality of cells 2, which are arranged side by side and have a square cross-section, a plurality of cell walls 3, which form the plurality of cells 2, and an outer circumferential wall 4, which is provided outside the plurality of cell walls 3 and holds the cell walls 3. For the parts of the honeycomb structure 1, reference can be made, if necessary, to the first to fifth embodiments described above.

[0082] As in Fig. 9, Fig. 10 to Fig.As shown in Figure 11, the die 5 according to the present embodiment comprises a first die section 51 and a second die section 52. The first die section 51 contains a plurality of green body inlets 510 through which a green body is supplied as raw material for the honeycomb structure 1. In the present embodiment, the green body inlets 510 are cylindrical through-holes. The green body is typically a clayey substance produced from the raw material for the cell walls 3 of the honeycomb structure 1.

[0083] The second matrix section 52 contains a plurality of slots 520 for receiving the green body, which is supplied through the green body inlets 510 to form a section like the plurality of cell walls 3 in the honeycomb structure 1. The second matrix section 52 also contains a central slot region (not shown) and a peripheral slot region (not shown). The central slot region is a part for forming a section as cell walls 3 with a wall thickness equal to the wall thickness of the cell walls 3 of the four surrounding cells 200 around the honeycomb central axis 10, or of the cell walls 3 of the central cell 20 with the cell center through which the honeycomb central axis 10 passes. That is, the central slot region is a part for forming the central region 11 of the honeycomb structure 1. The peripheral slot region is a part with slots 520 around the central slot region that are wider than the slots 520 of the central slot region.That is, the peripheral slot area is part of the formation of the reinforced outer edge area 12 of the honeycomb structure 1.

[0084] Fig. Figure 10 illustrates the positional relationship between the green body inlets 510 and the slot vertices 521. Fig. Figure 10 is an illustration of the matrix 5, which forms the honeycomb structure 1 including the four surrounding cells 200 around the honeycomb central axis 10. Fig. For simplicity, the 520 slots are shown as lines. Fig. In section 10, the width differences between slots 520 and the central and peripheral slot areas have been omitted. As in Fig.As shown in Figure 10, the green body inlets 510 of the first matrix section 51 in the matrix 5 are not positioned at all slot vertices 521, each corresponding to the slot connection between four slots 520 of the second matrix section 52. The green body inlets 510 of the first matrix section 51 are positioned at alternating slot vertices 521 along the slots 520 of the second matrix section 52.

[0085] The die 5 has the configuration described above. Therefore, when the honeycomb structure 1 is extruded through the die 5, the green body may not be able to reach all slot vertices 521, which correspond to the slot connections between each set of four slots 520. As shown in Fig. As shown in Figure 10, the green body can be guided from the one corresponding green body inlet 510 along the slots 520 to each of the alternating slot vertices 521, and as shown in Fig.As shown in Figure 11, the green body can be spread evenly from the slot apex 521 into the four slots 520 of equal width. More precisely, the die 5, in which the four slots 520, extending radially from the slot apex 521 next to each green body inlet 510, have substantially the same width, enables the reduction of the variance in resistance to green body flow between the four slots 520. Accordingly, the die 5 reduces the possibility of local deformation occurring during the extrusion of the reinforced outer edge region 12 of the honeycomb structure 1.

[0086] Therefore, the die 5 can form the honeycomb structure 1, which is able to prevent a reduction in structural strength due to deformation. The honeycomb structures 1 shown in the first to fifth embodiments can be specifically designed, for example, as described below.

[0087] A matrix 5 is prepared, comprising a second matrix section 52 with slot widths and slot arrangement corresponding to the wall thicknesses and cell wall arrangement of the multiple cell walls 3 of each honeycomb structure 1, and a first matrix section 51 with green body inlets 510 arranged such that their hole centers coincide with alternating slot apex points 521 in the second matrix section 52. The arrangement of the green body inlets 510 in the first matrix section 51 of the matrix 5 corresponds to the arrangement of the cell apex points 330 (in Fig.1, 4 and 6 to 8 (indicated circles) of the cross-shaped units 33 in the honeycomb structure 1 to be formed. Then, in the extrusion step, the green body inlets 510 are fed with a green body, and the green body is guided to the slot vertices 521. As a result, the green body fed to each slot vertex 521 spreads into the four slots 520 extending radially from the slot vertex 521. Furthermore, the green body spreading in the slots 520 combines with a green body fed in a similar manner from the adjacent green body inlets 510 to their slot vertices 521 and spreads in the slots 520, and the resulting article is extruded from the die 5. After extrusion, known steps can be used. In this way, the honeycomb structures 1 shown in the first to fifth embodiments can be produced.

[0088] The die 5 can have a width difference ratio of 10% or less, calculated according to the formula: 100 × (wmax - wmin) / wmax, where wmax denotes the maximum width and wmin the minimum width of the four slots 520 extending radially from each of the slot vertices 521 at the green body inlets 510.

[0089] When each cross-shaped unit 33 of the honeycomb structure 1 is formed, the above configuration facilitates the reduction of the variance in resistance to green body flow between the four slots 520 extending from the slot vertex 521 and reduces the possibility of the occurrence of shape defects such as unconnected cell walls 3 between adjacent cross-shaped units 33. Thus, the above configuration enables the fabrication of the honeycomb structure 1 with sufficient average isostatic strength and minimal isostatic strength, even if the materials may vary. The above configuration also enables the fabrication of the honeycomb structure 1, which effectively reduces the defect rate associated with distortion.

[0090] To ensure the structural strength of the extruded honeycomb structure 1, the width difference ratio can preferably be less than 10%, more preferably 9% or less, even more preferably 8% or less, even more preferably 7% or less, and even more preferably 6% or less. The width difference ratio can even more preferably be 5% or less, which simplifies the fabrication of the honeycomb structure 1 exhibiting the aforementioned wall thickness difference ratio of 5% or less.

[0091] In the die 5, the green body inlets 510 can have a defined hole diameter to achieve a constant feed ratio. This configuration facilitates the uniform feeding of the green body from each green body inlet 510 to the slots 520. The configuration thus provides the die 5, which easily produces a honeycomb structure 1, with each cross-shaped unit having 33 cell walls 3 of the same wall thickness. The feed ratio, as in Fig. As shown in Figure 12, the cross-sectional area is calculated by dividing the cross-sectional area of ​​the four slots 520, which extend radially from a slot vertex 521, by the cross-sectional area of ​​the green body inlet 510. The cross-section is perpendicular to the hole axis of the green body inlet 510.

[0092] The die 5 preferably satisfies the relationship: the hole diameter of the green body inlets 510, which are connected to the central slot area, <der Lochdurchmesser der Grünkörpereinlässe 510, die mit dem peripheren Schlitzbereich verbunden sind. In dieser Konfiguration nimmt die Menge eines zuzuführenden Grünkörpers mit der Breite der verdickten Schlitze 520 zu, so dass eine entsprechende Vergrößerung des Durchmessers der Zuführlöcher eine effektive Erfassung eines extrudierten Artikels mit einer Zellwanddickendifferenz ermöglicht, die der Schlitzbreitendifferenz entspricht. <Experimentelles Beispiel 1>

[0093] As shown in Table 1, samples of honeycomb structures were prepared whose reinforced outer edges had a varying number of reinforced cells and cell walls with different wall thicknesses, and their isostatic strengths were measured (the mean of n = 20; the same applies below). In this experimental example, honeycomb structures with four surrounding cells around the central axis of the honeycomb were prepared.

[0094] More precisely, as in Fig.As shown in Figure 6, Sample 3 has a central region and a reinforced outer edge region in which the cell walls of all cross-shaped units have a substantially equal wall thickness, and thus meets requirement 5. Sample 4 is essentially the same as Sample 3, although it has a different number of reinforced cells. In contrast, Samples 1 and 2 do not meet requirement 5. More precisely, Sample 1 is a conventional honeycomb structure and contains, as shown in Figure 6, a central region and a reinforced outer edge region in which the cell walls of all cross-shaped units have a substantially equal wall thickness. Fig. Figure 18 shows a portion in which at least one of the four cell walls extending radially from each cell apex has a wall thickness that differs from that of the other cell walls. Although not shown, sample 2 is similar to sample 1.

[0095] The details will now be described using samples 1 and 3 as examples. In this experimental example, the honeycomb structure of each sample had an outer circumferential wall with a thickness of 0.35 mm and an outer shape with a diameter of 117 mm and a height of 100 mm. The slots of the die were as follows: • Slot width in the central slot area: 70 µm, slot spacing: 1.19 mm, radius dimension of the slotted apex: 0.1 mm • Slot width for the first cell in the peripheral slot area: 117 µm, slot spacing: 1.19 mm, radius dimension of the slotted apex: 0.1 mm • Slot width for the second cell in the peripheral slot area: 103 µm, slot spacing: 1.19 mm, radius dimension of the slotted apex: 0.1 mm • Slot width for third cell in peripheral slot area: 90 µm, slot spacing: 1.19 mm, radius dimension of the slotted apex: 0.1 mm • Slot width for the fourth cell in the peripheral slot area: 77 µm, slot spacing: 1.19 mm, radius dimension of the slotted apex: 0.1 mm

[0096] A honeycomb structure with the cell walls described below was extruded using the matrix described above. • Cell wall thickness in the central area: 65 µm, cell wall spacing: 1.1 mm, radius of the cell apex: 0.15 mm • Cell wall thickness of the first cell in the reinforced outer edge region: 112 µm, cell wall spacing: 1.1 mm, radius dimension of the cell apex: 0.15 mm • Cell wall thickness of the second cell in the reinforced outer edge region: 98 µm, cell wall spacing: 1.1 mm, radius dimension of the cell apex: 0.15 mm • Cell wall thickness of the third cell in the reinforced outer edge region: 85 µm, cell wall spacing: 1.1 mm, radius dimension of the cell apex: 0.15 mm • Cell wall thickness of the fourth cell in the reinforced outer edge region: 72 µm, cell wall spacing: 1.1 mm, radius dimension of the cell apex: 0.15 mm [Table 1] Sample No. Satisfaction of requirement 5 Wall thickness of the cell walls of the reinforced outer edge region (µm) Isostatic strength (MPa) Maximum isostatic strength (MPa) Minimum isostatic strength (MPa) 1st cell 2nd cell 3rd cell 4th cell 5th cell 6th cell 1 Unsatisfied 112 98 85 72 - - 0,70 0,92 0,54 2 Unsatisfied 112 100 90 79 74 72 0,74 1,08 0,37 3 Satisfactory 112 98 85 72 - - 4,2 5,6 3,7 4 Satisfactory 112 100 90 79 74 72 5,1 6,5 4,2

[0097] Table 1 shows the following. Samples 1 and 2 exhibited low isostatic strengths. Upon investigation into the cause, a distortion, such as a thin cell wall area or a lack of green body, was found at the outer edges of samples 1 and 2. A cell wall tear was then observed at the point of distortion. This is because the cell wall arrangements of samples 1 and 2 inevitably caused a green body to be fed from a single green body inlet in the die into a plurality of slots of varying widths, resulting in uneven flow of the green body in narrow slots with high resistance to flow.

[0098] In contrast, samples 3 and 4 exhibited higher isostatic strengths than samples 1 and 2. This is because samples 3 and 4 contained cross-shaped units, each with cell walls of equal thickness. In forming each cross-shaped unit, the uniform wall thickness reduced the variance in resistance to green body flow between the four slits extending from the slit vertex, resulting in a lower possibility of local distortion. <Experimentelles Beispiel 2>

[0099] As shown in Table 2, the specimens were prepared in the same way as specimen 3 in experimental example 1 with different wall thickness difference ratios in their cross-shaped units, and their isostatic strengths were measured.

[0100] The wall thickness difference was measured using a QV-H4A CNC image processing device from Mitutoyo Corporation. Light was passed through the samples, which were then observed with a camera, and the wall thicknesses of all cell walls were automatically measured. This device can identify abnormal readings resulting from distortion and detect the distortion through an image. At the location of the distortion, the apparatus determines the cell wall thickness as a measurement error of 0. [Table 2] Sample No. Satisfaction of requirement 5 Wall thickness difference ratio (%) Wall thickness of the cell walls of the reinforced outer edge region (µm) Isostatic strength (MPa) Maximum isostatic strength (MPa) Minimum isostatic strength (MPa) 1st cell 2nd cell 3rd cell 4th cell 5 Satisfactory ≤ 2% 112 98 85 72 4,2 5,6 3,7 6 Satisfactory > 2%, ≤5% 112 98 85 72 4,2 6,0 3,1 7 Satisfactory > 5%, ≤7% 112 98 85 72 3,0 5,4 1,11 8 Satisfactory > 7%, ≤10% 112 98 85 72 3,2 5,7 1,04 9 Satisfactory > 10%, ≤12% 112 98 85 72 0,93 1,64 0,41

[0101] Table 2 shows the following. Samples 5 and 6 showed no reduction in isostatic strength (average) and exhibited comparable levels of maximum and minimum isostatic strengths. The results show that even with differing wall thicknesses, a wall thickness difference ratio of 5% or less can reduce the possibility of forming a cross-shaped unit with deformation that may reduce the structural strength of the honeycomb structure.

[0102] Samples 7 and 8 exhibited reductions in minimum isostatic strength, although their maximum isostatic strengths changed only slightly. When an image of sample 8, which was yet to be fractured, was obtained, cell wall spalling was found in some cross-shaped units with a wall thickness difference ratio of 10%. The results suggest that the probability of cell wall spalling increases as the wall thickness difference ratio approaches 10%. Furthermore, ensuring isostatic strength becomes easier as the wall thickness difference ratio decreases. This is because a reduction in distortion reduces the number of samples with low isostatic strength.

[0103] In contrast, with a wall thickness difference ratio of more than 10%, as in sample 9, distortions were observed in all workpieces (n = 20), and each workpiece exhibited low isostatic strength. <Experimentelles Beispiel 3>

[0104] As shown in Table 3, the samples were prepared in the same way as sample 3 in experimental example 1 with a different number of reinforced cells in their reinforced outer edge regions, and their isostatic strengths and pressure losses were measured.

[0105] The pressure loss was measured in the manner described below. As in Fig.As shown schematically in Figure 13, an evaluation converter 9 was prepared with pipe sections 91, a housing section 92 containing a honeycomb structure 1, and conical sections 93 connecting the pipe sections 91 and the housing section 92. The pipe sections 91 had a diameter φ1 of 50.5 mm. The housing section 92 had a diameter φ2 of 123 mm. The tapered sections 93 had a length l1 of 55 mm. One end face of the honeycomb structure 1 and the adjacent conically tapered section 93 were separated by a distance l2 of 5 mm. The other end face of the honeycomb structure 1 and the adjacent conically tapered section 93 were separated by a distance l3 of 10 mm. Honeycomb structure 1 received exhaust gas flowing at a rate of 7 m³ / min and with a gas temperature of 600°C. The exhaust gas was generated by a 4.6L V8 engine. [Table 3] Sample No. Satisfaction of requirement 5 Reinforced outer edge area Isostatic strength (MPa) Pressure loss (kPa) Number of reinforced cells (cells) Cell wall thickness (µm) 10 Satisfactory 0 75 1,6 4,97 11 Satisfactory 2 75 1,4 5,07 12 Satisfactory 4 75 2,6 5,12 13 Satisfactory 6 75 2,5 5,17 14 Satisfactory 8 75 3,2 5,19 15 Satisfactory 10 75 3,7 5,20 16 Satisfactory 18 75 3,8 5,22 17 Satisfactory 20 75 3,9 5,22 18 Satisfactory 22 75 3,7 5,32 19 Satisfactory 25 75 4,1 5,62 20 Satisfactory 30 75 3,7 6,16

[0106] Table 3 and Fig. 14, Fig. 15 to Fig. 16 show the following. Table 3 and Fig. 14 and Fig. 15 show that the isostatic strength can be improved more easily than in a honeycomb structure whose reinforced outer edge region is an area extending from the outer circumferential wall to the fourth or each subsequent cell in the direction of the honeycomb central axis, or the reinforced outer edge region has four or more reinforced cells. Fig. Figure 16 shows the relationship between the stress ratio and the number of cells from the outer circumferential wall of a honeycomb structure according to CAE analysis. Fig.Figure 16 shows that the stress generated in a honeycomb structure with square-sectioned cells increases towards the outer edge. Specifically, it is observed that the generated stress rises sharply in the region from the outer periphery wall to the fourth cell in the direction of the honeycomb's central axis. The results also suggest that the reinforced outer edge region with four or more reinforced cells effectively prevents fractures caused by stress concentration during preservation and offers the advantage of slightly improving the structural strength of the honeycomb structure.

[0107] In contrast, Table 3 and Fig.15. Reinforced outer edge regions with more than 20 reinforced cells exhibit a tendency towards a sharp increase in pressure drop within the honeycomb structure. This may be due to a significant influence of the thickening of the cell walls themselves near the honeycomb center, where exhaust gases tend to concentrate. The results suggest that the number of reinforced cells in the reinforced outer edge region is preferably 20 or fewer to prevent an increase in pressure drop, a reduction in structural strength due to deformation, and fracture due to stress concentration during preservation. <Experimentelles Beispiel 4>

[0108] As shown in Table 4, the samples were prepared in the same way as Sample 3 in Experiment 1, with their reinforced outer edge regions having a different number of reinforced cells and cell walls of varying thicknesses, and their isostatic strengths and pressure drop, as described in Experiment 3, were measured. In this experiment, the prepared samples were specifically classified into samples with either a reinforced outer perimeter region or an outer edge region, where each cell wall of its cells has the same thickness from the first cell to the last cell of the reinforced outer perimeter region in the direction from the outer perimeter wall or outer edge region.outer circumferential wall towards the honeycomb central axis, and samples which each have a reinforced outer circumferential area, wherein the wall thicknesses of their cell walls are greatest in the first cell in the direction from the outer circumferential wall towards the honeycomb central axis and gradually decrease from the outer circumferential wall towards the honeycomb central axis.

[0109] Table 4 shows the following. The comparisons between patterns 21 and 22, patterns 23 and 24, and patterns 25 and 26 in Table 4 show that the structural strength of a honeycomb structure can be ensured without an increase in pressure loss for a reinforced outer perimeter region, where the wall thicknesses of its cell walls are greatest at the first cell in the direction from the outer perimeter wall towards the honeycomb central axis and gradually decrease from the outer perimeter wall towards the honeycomb central axis. This is because, compared to a reinforced outer perimeter region whose cells have uniformly thickened cell walls, this configuration allows for a gradual decrease in stress towards the center of the honeycomb and minimizes the influence on pressure loss. <Experimentelles Beispiel 5>

[0110] As shown in Table 5, the samples were prepared in the same way as Sample 3 in Experimental Example 1, with their reinforced outer perimeter regions exhibiting cell walls of varying thicknesses, and their isostatic strengths were measured. In this experimental example, the cell walls forming the central cells within the central region had a mean wall thickness of 65 µm. The cells within the reinforced outer perimeter regions had uniformly thickened cell walls. For the reinforced outer perimeter regions, the mean wall thicknesses of the cell walls forming the first cells in the direction from the outer perimeter wall or border wall to the honeycomb mid-axis are listed in Table 5. [Table 5] Sample No. Satisfaction of requirement 5 Reinforced outer edge area Isostatic strength (MPa) Number of reinforced cells (cells) Cell wall thickness (µm) Wall thickness of the cell wall of the first cell / Wall thickness of the cell wall of the central cell 13 Satisfactory 6 75 1,15 2,5 27 Satisfactory 6 90 1,38 2,7 28 Satisfactory 6 105 1,62 3,4 29 Satisfactory 6 112 1,72 3,6 30 Satisfactory 6 120 1,85 3,6

[0111] Table 5 and Fig. Figure 17 shows the following. According to Table 5 and Fig.17. The isostatic strength of the honeycomb structure can be easily improved if the first cell has cell walls with a wall thickness that is 1.4 times or more than the wall thickness of the central cell. The results indicate that this configuration facilitates the reduction of stress in the region of the first cell, which experiences the highest stress concentration during the canning process, and offers an advantage in slightly improving the structural strength of the honeycomb structure. Reference symbol list 1 honeycomb structure 2 adjacent cells 3a thin wall(s) 3b Interior wall(s) 3c thick wall(s) 3D exterior wall(s) 4 outer perimeter wall 5 die 9 evaluation converters 10 honeycomb central axis 11 central area 12 reinforced outer edge area 20, 201 central cell 21 Reference boundary cell 30 Interior-Exterior Boundary Wall 33 cross-shaped unit 51 first matrix section 52 second matrix section 91 pipe sections 92 Accommodation section 93 rejuvenated sections 201 central cell 300 inner boundary wall 311 first reference cell vertex 322 second reference cell vertex 330 cell apex 510 Green body inlet 520 thickened slots 521 Slot vertex

Claims

[1] Honeycomb structure (1), comprising: a plurality of cells (2) that are adjacent to each other and have a square cross-section; a plurality of cell walls (3, 3e-h) that form the plurality of cells; and an outer circumferential wall (4) that is provided outside the plurality of cell walls (3, 3e-h) and that holds the cell walls (3, 3e-h), wherein, viewed in a cross-section perpendicular to a honeycomb central axis (10), the honeycomb structure (1) satisfies the following requirements 1 to 5: Requirement 1: the honeycomb structure (1) comprises a central region (11) with cell walls (3, 3e-h) having a wall thickness equal to the wall thickness of a cell wall (3, 3e-h) of four surrounding cells (200) around the honeycomb central axis (10) or the wall thickness of a cell wall (3, 3e-h) of a central cell (20, 201) with a cell center through which the honeycomb central axis (10) passes, and the honeycomb structure (1) comprises a reinforced outer perimeter region (12) with cell walls (3, 3e-h) around the central region (11), wherein the cell walls (3, 3e-h) have a wall thickness greater than the wall thickness of the cell wall (3, 3e-h) of the surrounding cells or the cell wall (3, 3e-h) of the central cell (20, 201); Requirement 2: A plurality of cells (2) arranged on an imaginary parallel line (L1) passing through the honeycomb central axis (10) and parallel to cell walls (3, 3e-h), or a plurality of cells arranged along an imaginary perpendicular line (L2) passing through the honeycomb central axis and orthogonal to cell walls (3, 3e-h) such that it extends through the midpoints of the cell walls (3, 3e-h), comprising a reference boundary cell (21) with cell walls (3, 3e-h) having different wall thicknesses on two sides parallel to the imaginary parallel line (L1) or the imaginary perpendicular line (L2), wherein the reference boundary cell (21) has a thin wall (3a) that is a thin cell wall on one side parallel to the imaginary parallel line or the imaginary perpendicular line and has a wall thickness that is designated as t1 is designated as a thick wall (3c),comprising a thick cell wall (3) on the other side parallel to the imaginary parallel line or the imaginary perpendicular line and having a wall thickness designated t3, an inner wall (3b) that is a cell wall (3, 3e-h) adjacent to a honeycomb center and orthogonal to the imaginary parallel line (L1) or the imaginary perpendicular line (L2) and having a wall thickness designated t2, and an outer wall (3d) that is a cell wall (3, 3e-h) adjacent to a honeycomb perimeter and orthogonal to the imaginary parallel line or the imaginary perpendicular line and having a wall thickness designated t4, wherein the following applies in this respect: t1 <t3,t2<t4,t1=t2, und t3=t4; Requirement 3: The honeycomb structure (1) comprises the following: a first cross-shaped reference unit (31) with four cell walls (3, 3e-h): the thin wall (3a), the inner wall (3b), a cell wall (3, 3e-h) extending in a direction opposite to that of the thin wall (3a) from a first reference cell vertex (311) corresponding to a connection between the thin wall (3a) and the inner wall (3b), and a cell wall (3, 3e-h) extending from the first reference cell vertex (311) in a direction opposite to that of the inner wall (3b), and a second cruciform reference unit (32) with four cell walls (3, 3e-h): the thick wall (3c), the outer wall (3d), a cell wall (3, 3e-h) extending in a direction opposite to the thick wall (3c) from a second reference cell vertex (322) corresponding to a connection between the thick wall (3c) and the outer wall (3d), and a cell wall extending from the second reference cell vertex (322) in a direction opposite to the outer wall (3d); Requirement 4: the honeycomb structure (1) comprises a plurality of cross-shaped units (33), each having four cell walls (3, 3e-h) extending vertically and horizontally from one another and connected to each other at alternating cell vertices (330) arranged along the cell walls (3, 3e-h) from the first reference cell vertex (311) or the second reference cell vertex (322) as the starting point; and Requirement 5: For each cross-shaped unit (33) in the central region (11) and in the reinforced outer edge region, the cell walls (3, 3e-h) of each of the cross-shaped units have a substantially equal wall thickness. [2] Honeycomb structure (1) according to claim 1, wherein the honeycomb structure (1) has a wall thickness difference ratio of 10% or less, the ratio being calculated according to the following formula: 100×(tmax−tmin) / tmax, where tmax represents a maximum wall thickness and tmin represents a minimum wall thickness of the four cell walls (3, 3e-h) that form each cross-shaped unit. [3] Honeycomb structure (1) according to claim 2, wherein the wall thickness difference ratio is 5% or less. [4] Honeycomb structure (1) according to one of claims 1 to 3, wherein the reinforced outer edge region (12) extends to a fourth or each subsequent cell in a direction from the outer circumferential wall (4) to the honeycomb central axis (10). [5] Honeycomb structure (1) according to any one of claims 1 to 4, wherein the reinforced outer edge region (12) extends to a 20th or any previous cell in a direction from the outer circumferential wall (4) to the honeycomb central axis (10). [6] Honeycomb structure (1) according to any one of claims 1 to 5, wherein the wall thickness of the cell walls (3, 3e-h) forming the cells in the reinforced outer edge region (12) is greatest in the first cell (2) in a direction from the outer circumferential wall (4) to the honeycomb central axis (10) and gradually decreases from the outer circumferential wall (4) to the honeycomb central axis (10). [7] Honeycomb structure (1) according to any one of claims 1 to 6, wherein the cell walls (3, 3e-h) enclosed in the reinforced outer edge region (12) and forming the first cell (2) in a direction from the outer circumferential wall (4) to the honeycomb central axis are 1.4 or more times as thick as the cell walls (3, 3e-h) forming the surrounding cells or the central cell (20, 201) in the central region (11). [8] A die (5) for extruding a honeycomb structure (1) with a plurality of cells (2) arranged side by side and having a square cross-section, with a plurality of cell walls (3, 3e-h) forming the plurality of cells, and with an outer circumferential wall (4) provided outside the plurality of cell walls (3, 3e-h) and holding the cell walls (3, 3e-h), wherein the die (5) comprises the following: a first matrix section (51) with a plurality of green body inlets (510) through which a green body is supplied as raw material for the honeycomb structure (1); and a second matrix section (52) with a plurality of slots (520) for receiving the green body supplied through the green body inlets (510) in order to form a section as the plurality of cell walls (3, 3e-h) in the honeycomb structure (1), wherein the second matrix section (52) has a central slot region with slots (520) for forming a section as cell walls (3, 3e-h) with a wall thickness equal to the wall thickness of a cell wall (3, 3e-h) of four surrounding cells (200) around a honeycomb central axis (10) or the wall thickness of a cell wall (3, 3e-h) of a central cell (20, 201) with a cell center through which the honeycomb central axis (10) passes, and a peripheral slot region with slots (520) around the central slot region, wherein the slots (520) are wider than the slots (520) of the central slot region, the majority of green body inlets (510) are not positioned at all slot vertices (521), each corresponding to a slot connection between four slots (520), and are positioned at alternating slot vertices (521) along the slots (520), and the four slots (520) extending radially from the slot apex (521) next to each green body inlet (510) have essentially the same width. [9] Die (5) according to claim 8, wherein the die (5) has a width difference ratio of 10% or less, the ratio being calculated according to a formula: 100×(wmax−wmin) / wmax, where wmax denotes a maximum width and wmin a minimum width of the four slots (520) extending radially from each of the slot vertices (521) at the green body inlets. [10] Die (5) according to claim 9, wherein the width difference ratio is 5% or less. [11] Die (5) according to one of claims 8 to 10, wherein the green body inlets (510) have a hole diameter defined such that a constant feed ratio is ensured.

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