JP7003694B2 - Honeycomb structure - Google Patents

Description

The present invention relates to a honeycomb structure, and more particularly to a honeycomb structure having cells having a hexagonal cross section.

Conventionally, in the field of vehicles such as automobiles, an exhaust gas purifying device has been used to purify an exhaust gas discharged from an internal combustion engine. The exhaust gas purification device has a honeycomb structure made of ceramics housed in an exhaust pipe and a catalyst component held in the honeycomb structure. The honeycomb structure usually has a plurality of cells adjacent to each other, a plurality of cell walls forming the plurality of cells, and an outer peripheral wall provided on the outer periphery of the plurality of cell walls to hold the cell wall. There is. The catalyst component is retained on the cell wall surface.

According to the preceding Patent Document 1, in a honeycomb structure having an elliptical outer peripheral wall, 30 ° <θ <45 ° when the angle formed by the B axis and the C axis of the cell having a hexagonal cross section is θ. , A honeycomb structure having an isostatic strength of 4 MPa or more is described.

Japanese Unexamined Patent Publication No. 2004-181458

In recent years, due to stricter exhaust gas regulations and fuel consumption regulations, exhaust gas purification devices are required to have early warming up and low pressure loss. Along with this, in the honeycomb structure, the wall thickness of the cell wall is becoming thinner year by year. However, thinning the wall thickness reduces the structural strength of the honeycomb structure. Therefore, in the canning step of accommodating the honeycomb structure holding the catalyst component in the exhaust pipe, the honeycomb structure is liable to be broken by the compressive stress applied from the radial direction. In particular, the honeycomb structure having a cell having a hexagonal cross section has a lower structure strength than the honeycomb structure having a cell having a square cross section, and therefore is easily broken by stress concentration during canning.

On the other hand, in the above-mentioned conventional honeycomb structure, in order to improve the strength of the structure, the cells having a regular hexagonal shape are not deformed as much as possible (the cell deformation is up to the deformation in the range of 30 ° <θ <45 °). (Keep it), try to secure the strength. However, according to this technique, it is difficult to limit the regular hexagonal cells to partial deformation, and it is necessary to deform all the cells constituting the honeycomb structure. Therefore, in the conventional honeycomb structure, the pressure loss becomes large. Further, in the conventional honeycomb structure, since the outer peripheral wall of the honeycomb structure has an elliptical shape in the first place, the pressure loss tends to be large from this point as well.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a honeycomb structure capable of improving the strength of the structure while suppressing an increase in pressure loss.

One aspect of the present invention is provided on the outer periphery of a plurality of cells (2) having a hexagonal cross section adjacent to each other, a plurality of cell walls (3) forming the plurality of cells, and the plurality of cell walls. A honeycomb structure (1) having an outer peripheral wall (4) for holding a cell wall.
In cross-sectional view perpendicular to the honeycomb center axis (10)
A base region having a regular hexagonal center cell (20) in which the honeycomb center axis passes through the center of the cell, which is composed of a plurality of regular hexagonal cells.
It is configured to include a plurality of cells having a non-regular hexagonal shape, and has an outer peripheral strengthening region (12) arranged on the outer circumference of the base region.
The outer peripheral strengthening region is a direction perpendicular to the side (L) of the virtual regular hexagon when the virtual regular hexagon (H) whose B axis is tilted by 30 degrees with respect to the center cell is drawn coaxially with the center cell. A non-regular hexagonal flat cell (21) formed by using a pair of short cell walls (30) in which the length of the cell wall constituting the cell wall is shorter than the length of the cell wall in the base region. Have multiple
The plurality of the flat cells are arranged side by side along the sides of the virtual regular hexagon.
When viewed along the sides of the virtual regular hexagon, the cell pitch of the flat cell is equivalent to the cell pitch of the cell in the base region.
The lengths of the short cell walls of the flat cells arranged in the same row along the sides of the virtual regular hexagon are in the honeycomb structure (1), which are the same.

The honeycomb structure has the above configuration. That is, unlike the conventional honeycomb structure, the honeycomb structure positively deforms the cell in a certain direction by using a flat cell satisfying the above configuration only in the outer peripheral strengthening region where stress concentration is likely to occur during canning. The regular hexagonal cells in the base region are basically not deformed. Therefore, according to the honeycomb structure, it is possible to suppress an increase in pressure loss. Further, by arranging the flat cell having the short cell wall having high buckling strength in the outer peripheral strengthening region, the structural strength of the honeycomb structure can be improved.

The reference numerals in parentheses described in the scope of claims and the means for solving the problem indicate the correspondence with the specific means described in the embodiments described later, and limit the technical scope of the present invention. It's not a thing.

It is explanatory drawing which simplified and showed the cross-sectional structure perpendicular to the honeycomb central axis of the honeycomb structure of Embodiment 1. FIG. The cells included in the honeycomb structure of the first embodiment are schematically shown, (a) is a flat cell included in the outer peripheral strengthening region, and (b) is a deformed cell that can be included in the outer peripheral strengthening region, (c). ) Is a normal cell in the base region. It is explanatory drawing for demonstrating how to count the number of reinforcement columns in the outer peripheral reinforcement area. It is explanatory drawing which showed the same row in the outer peripheral reinforcement area. It is explanatory drawing which simplified and showed the cross-sectional structure perpendicular to the honeycomb central axis of the honeycomb structure of Embodiment 2. It is explanatory drawing which simplified and showed a part of the outer peripheral reinforcement region in the honeycomb structure of Embodiment 3. It is explanatory drawing which simplified and showed the cross-sectional structure perpendicular to the honeycomb central axis of the honeycomb structure of Embodiment 4. The cells included in the honeycomb structure of the fifth embodiment are schematically shown, (a) has a cell having a reinforcing portion included in the base region, and (b) has a reinforcing portion included in the outer peripheral reinforcing region. It is a flat cell. It is explanatory drawing which simplified and showed the cross-sectional structure perpendicular to the honeycomb central axis of the honeycomb structure of Embodiment 6. In order to explain a three-pronged unit, it is an explanatory diagram schematically showing an enlarged portion A of FIG. 9. It is explanatory drawing which simplified and showed the cross-sectional structure perpendicular to the honeycomb central axis of the honeycomb structure of the test body 1C in Experimental Example 1. FIG. It is explanatory drawing for demonstrating the evaluation method of a pressure loss in Experimental Example 1. FIG.

(Embodiment 1)
The honeycomb structure of the first embodiment will be described with reference to FIGS. 1 to 4. As illustrated in FIGS. 1 to 4, the honeycomb structure 1 of the present embodiment is made of ceramics (for example, cordierite or the like), and has a plurality of cells 2 having a hexagonal cross section adjacent to each other and a plurality of cells. It has a plurality of cell walls 3 forming 2 and an outer peripheral wall 4 provided on the outer periphery of the plurality of cell walls 3 to hold the cell wall 3. In addition, in FIG. 1, FIG. 3, and FIG. 4, the cell wall 3 is represented by a line for convenience, and the wall thickness and the like of the cell wall 3 are omitted.

In the present embodiment, the cell 2 is composed of a through hole extending along the honeycomb central axis 10, which is an axis passing through the center of the honeycomb structure 1. The cell 2 is a portion of the flow path through which the exhaust gas to be purified flows. The cross section referred to in the above-mentioned hexagonal cross section means a cross section perpendicular to the honeycomb central axis 10. Further, the hexagonal shape referred to in the above-mentioned hexagonal cross-section means a regular hexagon, a non-regular hexagon, a hexagon with rounded corners, a hexagon that is unintentionally distorted in manufacturing, and the like. The plurality of cell walls 3 are connected to and integrated with the cell walls 3 adjacent to each other. A catalyst component is supported on the wall surface of the cell wall 3 on the cell 2 side when the honeycomb structure 1 is used. The outer peripheral wall 4 has a circular shape in a cross-sectional view perpendicular to the honeycomb central axis 10. A plurality of cell walls 3 arranged near the inner side surface of the outer peripheral wall 4 are connected to the inner side surface of the outer peripheral wall 4. As a result, the plurality of cell walls 3 are integrally held by the outer peripheral wall 4.

As illustrated in FIG. 1, the honeycomb structure 1 has a base region 11 and an outer peripheral strengthening region 12 in a cross-sectional view perpendicular to the honeycomb central axis 10.

The base region 11 is configured to include a plurality of cells 2 having a regular hexagonal shape, and is a region having a central cell 20 having a regular hexagonal shape in which the honeycomb center axis 10 passes through the center of the cells. In the base region 11, the cell wall 3 included in the base region 11 can be specifically made to have the same wall thickness. More specifically, when the average value of the wall thickness of each cell wall 3 constituting the central cell 20 and the six cells 2 surrounding the central cell 20 is _tave , the cell wall included in the base region 11 is included. The wall thickness t of 3 can be in the range of 0.97 × t _ave to 1.03 × _ave . When the wall thickness of the cell wall 3 included in the base region 11 is within the above range, it can be said that the wall thickness is within the error range with respect to _ave , so that it can be said that the wall thickness is the same.

The outer peripheral strengthening region 12 is configured to include a plurality of cells 2 having a non-regular hexagonal shape, and is a region arranged on the outer circumference of the base region 11. Specifically, the outer peripheral strengthening region 12 is integrally connected to the base region 11. Note that FIG. 1 shows an example in which the outer peripheral strengthening region 12 is configured to continuously cover the base region 11 in the circumferential direction.

The outer peripheral strengthening region 12 has a plurality of non-regular hexagonal flat cells 21. Hereinafter, the flat cell 21 will be described.

As illustrated in FIG. 1, a virtual regular hexagon H whose B axis is tilted by 30 degrees with respect to the center cell 20 is drawn coaxially with the center cell 20. As shown in FIG. 2 (c), the pair of opposite cell vertices of the regular hexagonal cell 2 are connected in a cross-sectional view perpendicular to the honeycomb central axis, and the cell 2 is symmetrical with respect to the axis. The axis that becomes the shape is the C axis. The axis perpendicular to the C axis and passing through the center of the cell 2 is the B axis. In FIG. 1, the virtual regular hexagon H is drawn so that each vertex exists inside the outer peripheral wall 4.

In the outer peripheral strengthening region 12, the flat cell 21 has the length of the cell wall 3 forming the direction perpendicular to the side L of the virtual regular hexagon H as the base region 11 as exemplified in FIGS. 1 and 2 (a). It is formed by using a pair of short cell walls 30 that are shorter than the length of the cell wall 3 in the above. This will be described more specifically.

As illustrated in FIG. 1, six first virtual straight lines V1 connecting the honeycomb central axis 10 and each vertex of the virtual regular hexagon H are drawn as auxiliary lines. Then, the description mainly focuses on the one-sixth portion of the honeycomb structure 1 between the adjacent first virtual straight lines V1. As shown in FIGS. 1 and 2, in the outer peripheral strengthening region 12, the length of the cell wall 3 forming the direction perpendicular to the side L of the virtual regular hexagon H is defined as h1. Further, in the base region 11, the length of the cell wall 3 forming the direction perpendicular to the side L of the virtual regular hexagon H is defined as h. At this time, h1 and h satisfy the relationship of h1 <h. That is, as illustrated in FIGS. 1 and 2 (c), the cell 2 in the base region 10 has a pair of cell walls 3 having a length h forming a direction perpendicular to the side L of the virtual regular hexagon H. It is composed of four cell walls 3 having a length h. On the other hand, the flat cell 30 in the outer peripheral strengthening region 12 is composed of a short cell wall 30 as a pair of cell walls 3 having a length h1 and four cell walls 3 having different lengths from the short cell wall 30. It is configured. The pair of short cell walls 30 are arranged so as to face each other. As described above, the flat cell 30 in the outer peripheral strengthening region 12 is distorted in the direction perpendicular to the side L of the virtual regular hexagon H due to the shortening of the cell wall 3 constituting the direction perpendicular to the side L of the virtual regular hexagon H. However, it has a non-regular hexagonal shape.

In the outer peripheral strengthening region 12, the plurality of flat cells 21 are arranged side by side along the side L of the virtual regular hexagon H, as shown in FIGS. 1 and 4. Whether the outer peripheral reinforcing region 12 is configured from the region up to any row in any row or more counted from the outer peripheral wall 4 side, that is, the number of reinforcing rows in the outer peripheral reinforcing region 12 is determined as follows. be able to.

In FIG. 1, in addition to the six first virtual straight lines V1 described above, six second virtual straight lines connecting the honeycomb central axis 10 and the midpoint between the vertices of the virtual regular hexagon H are shown. V2 is drawn. Here, the direction of a certain second virtual straight line V2 is set to the 0 degree direction (in FIG. 1, the direction of the second virtual straight line V2 at the 12 o'clock position is set to the 0 degree direction). At this time, the directions of the second virtual straight lines V2 located at positions of 60 degrees, 120 degrees, 180 degrees, 240 degrees, and 300 degrees clockwise from there are set to the 60 degree direction, the 120 degree direction, and the 180 degree direction, respectively. The direction is 240 degrees and the direction is 300 degrees. It should be noted that the direction of each of the first virtual straight lines V1 located at positions of 30 degrees, 90 degrees, 150 degrees, 210 degrees, 270 degrees, and 330 degrees clockwise from the second virtual straight line V2 in the 0 degree direction is 30 degrees, respectively. The direction is 90 degrees, 150 degrees, 210 degrees, 270 degrees, and 330 degrees.

As shown in FIG. 3, a short cell wall 30 parallel to each second virtual straight line in the direction of 60 degrees × n (where n = 0, 1, 2, 3, 4, 5) in the outer peripheral strengthening region 12 is shown. Then, from the outer peripheral wall 4 toward the inside of the honeycomb, the numbers are counted as the first, the second, and so on. Then, the short cell wall 30 does not appear inside the honeycomb from the mth position from the outer peripheral wall 4. That is, the flat cell 21 does not appear inside the honeycomb from the mth position from the outer peripheral wall 4. At this time, the outer peripheral strengthening region 12 is composed of regions up to the m-th row counting from the outer peripheral wall 4 side. That is, in this case, the number of reinforcement rows by the flat cell 21 in the outer peripheral reinforcement region 12 is m rows. Then, between the adjacent first virtual straight lines V1, a plurality of flat cells 21 are arranged side by side along the side L of the virtual regular hexagon H in each of the strengthening rows. In each flat cell 21 that constitutes the final row of reinforcement counting from the outer peripheral wall 4 side, the regular hexagon formed by connecting the cell apex 31 most on the honeycomb center side is the outer peripheral reinforcement region 12 and the base region 10. It becomes the boundary with. In the present embodiment, the above-mentioned virtual regular hexagon H is adjusted to a size forming a boundary between the outer peripheral strengthening region 12 and the base region 10. Therefore, the virtual regular hexagon H constitutes a boundary between the outer peripheral strengthening region 12 and the base region 10.

When viewed in the direction along the side L of the virtual regular hexagon H in the outer peripheral strengthening region 12, the cell pitch p1 of the flat cell 21 is in the base region 11 as shown in FIGS. 2 (a) and 2 (c) and FIG. It is equivalent to the cell pitch p of the cell 2 (p1≈p). The cell pitch p of the cell 2 in the base region 11 can be calculated as follows. The cell pitch is obtained for each cell constituting the center cell 20 and the six cells 2 surrounding the center cell 20. The average value pave of each obtained cell pitch is taken as the cell pitch _p of the cell 2 in the base region 11. On the other hand, the cell pitch p1 of the flat cell 21 obtains the cell pitch for each flat cell 21 arranged in the final row of reinforcement. The average value p1 _ave of each obtained cell pitch is defined as the cell pitch p1 of the flat cell 21 in the outer peripheral strengthening region 12. When the cell pitch p1 of the flat cell 21 is in the range of 0.97 × p to 1.03 × p, it can be said that it is within the error range with respect to the cell pitch p of the cell 2 in the base region 11, so that p and p1 Can be said to be equivalent to.

In the outer peripheral strengthening region 12, the lengths h1 of the short cell walls 30 of the flat cells 21 arranged in the same row in the direction along the side L of the virtual regular hexagon H are the same. Here, when the average value of the length h1 of the short cell wall 30 of the flat cells 21 in the same row is h1 _ave , the length h1 of the short cell wall 30 of each flat cell 21 in the same row is 0. When it is in the range of 97 × h1 _ave to 1.03 × h1 _ave , it can be said that it is in the error range with respect to h1 _ave , so it can be said that the dimensions are equivalent to each other. In order to confirm that the above-mentioned relationship h1 <h is satisfied, the average value of the lengths of the short cell walls 30 of each flat cell 21 in the final strengthening row is applied to h1 and h is set to h1. May apply the average value of the lengths of the cell walls 3 facing the same direction as h1 to be compared in each cell constituting the central cell 20 and the six cells 2 surrounding the central cell 20.

Specifically, the wall thickness of the cell wall 3 in the outer peripheral strengthening region 12 may be the same for all of the cell walls 3 in the outer peripheral strengthening region 12, or the cell walls 3 having different wall thicknesses. Can also be configured to include. This embodiment is an example in which all of the cell walls 3 in the outer peripheral strengthening region 12 have the same wall thickness. When the average value of the wall thicknesses of all the cell walls 3 in the outer peripheral strengthening region 12 is t1 _ave , the wall thickness t1 of the cell walls 3 is in the range of 0.97 × t1 _ave to 1.03 × t1 _ave . At that time, since it can be said that it is within the range of error with respect to t1 _ave , it can be said that the dimensions are equivalent to each other. In this embodiment, the wall thickness of the cell wall 3 in the outer peripheral strengthening region 12 is not thickened with respect to the wall thickness of the cell wall 3 in the base region 12. That is, it can be said that this embodiment is an example in which the outer peripheral strengthening region 12 is mainly strengthened by the shape of the flat cell 21.

In the honeycomb structure 1, the outer peripheral reinforcing region 12 is preferably composed of regions up to any one row at least in the fourth row or more counting from the outer peripheral wall 4 side. That is, it is preferable that the outer peripheral strengthening region 12 has the flat cells 21 up to any one row located at least in the fourth row or more counting from the outer peripheral wall 4 side. This is because the stress generated during canning takes a high value in the region from the outer peripheral wall 4 to the fourth row portion. Therefore, according to the above configuration, it is possible to improve the strength of the structure with the minimum necessary configuration. Note that FIG. 1 shows an example in which the outer peripheral strengthening region 12 is composed of regions up to the fourth row counting from the outer peripheral wall 4 side.

In the honeycomb structure 1, the outer peripheral reinforcing region 12 is preferably composed of regions up to any row within the 20th row at most from the outer peripheral wall 4 side. Even if the outer peripheral strengthening region 12 is composed of a region larger than the 20th row, a large improvement in the strength of the honeycomb structure 1 cannot be expected. Further, the number of cells in the honeycomb structure 1 increases toward the outer peripheral portion. Therefore, as the amount of the flat cells 21 on the outer peripheral portion increases, the pressure loss of the honeycomb structure 1 tends to increase. Therefore, by adopting the above configuration, it is possible to obtain the honeycomb structure 1 in which the strength of the structure can be easily improved while suppressing the increase in the pressure loss.

From the viewpoint of ensuring the above effect, the outer peripheral strengthening region 12 is more preferably composed of regions up to any row within the 12th row at most from the outer peripheral wall 4 side. can.

The cell density in the honeycomb structure 1 can be, for example, 46.5 cells / cm ² to 155 cells / cm ² (300 cpsi to 1000 cpsi).

In the honeycomb structure 1, the outer peripheral strengthening region 12 can include the deformed cell 22 in addition to the flat cell 21 described above, as shown in FIGS. 2 (b) and 1. In the outer peripheral strengthening region 12, the deformed cell 22 can be generated by using the flat cell 21 in which the regular hexagonal cell 2 in the base region 11 is distorted in one direction in the outer peripheral strengthening region 12 in the first virtual straight line V1 direction. It has a role of absorbing the cell deformation of the portion of the outer peripheral strengthening region 12 and arranging the plurality of flat cells 21 in the same row direction so as to fit well. Further, the deformed cell 22 also has a role of continuously connecting the same rows of the flat cells 21 along the two adjacent sides L of the virtual hexagon H. Specifically, the deformed cell 22 is a virtual regular hexagon extending from each vertex of the virtual regular hexagon H on each of the six first virtual straight lines V1 connecting the honeycomb central axis 10 and each vertex of the virtual regular hexagon H. Using a first cell wall 341 forming a direction perpendicular to one of the two sides L of the hexagon H and a second cell wall 342 forming a direction perpendicular to the other of the two sides L. It is formed. Hereinafter, the modified cell 22 will be described.

As shown in FIG. 1, when the apex of the regular hexagon forming the boundary between the base region 11 and the outer peripheral strengthening region 12 exists inside the outer peripheral wall 4 (within the honeycomb diameter of the honeycomb structure 1), the deformed cell 22 Appears at least one on each of the six first virtual straight lines V1. Note that FIG. 1 shows an example in which two deformed cells 22 having different sizes and shapes are arranged side by side on each first virtual straight line V1. Of the two deformed cells 22, the deformed cell 22 on the base region 11 side has a hexagonal shape (non-regular hexagonal shape). Further, of the two deformed cells 22, the deformed cell 22 on the outer peripheral wall 4 side has a pentagonal shape (non-regular pentagonal shape).

As shown in FIGS. 1 and 2B, in the deformed cell 22, the length h2 of the first cell wall 341 and the second cell wall 342 of the deformed cell 22 is perpendicular to each side L of the virtual regular hexagon H. The length h of the cell wall 3 of the base region 11 constituting the above direction is shorter than the length h (h2 <h). Further, the length h2 of the first cell wall 341 and the second cell wall 342 of the deformed cell 22 is the length of the short cell wall 30 of the flat cell 21 arranged in the same row in the direction along the side L of the virtual regular hexagon H. It is equivalent to h1 (h1 ≈ h2 when viewed in the same row). Here, as h1, the average value of the lengths of the short cell walls 30 of the flat cells 21 in the same row is used. Further, as h2, the first cell wall 341 and the first cell wall 341 of each deformed cell 22 in the same row as the flat cell 21 in the direction of 30 degrees × n (where n = 1, 3, 5, 7, 9, 11). The average length of the second cell wall 342 is used. Then, comparing h1 and h2, when h2 is within the range of 0.97 × h1 to 1.03 × h1, it can be said that it is within the error range with respect to h1, so that they are equivalent to each other. Can be done.

When the outer peripheral strengthening region 12 of the honeycomb structure 1 has the deformed cell 22, it is possible to spread the flat cell 21 having increased buckling strength from the outer peripheral wall 4 to the inner peripheral portion. Further, the modified cell 22 continuously connects the rows of the flat cells 21 along the two adjacent sides L of the virtual hexagon H described above. Therefore, in the above case, the structure strength of the honeycomb structure 1 can be ensured.

The honeycomb structure 1 has the above configuration. That is, unlike the conventional honeycomb structure, the honeycomb structure 1 positively constants the cell 2 by using the flat cell 21 satisfying the above configuration only in the outer peripheral strengthening region 12 where stress concentration is likely to occur during canning. It is deformed in the direction, and the regular hexagonal cell 2 in the base region 11 is basically not deformed. Therefore, according to the honeycomb structure 1, it is possible to suppress an increase in pressure loss. Further, by arranging the flat cell 21 having the short cell wall 30 having high buckling strength in the outer peripheral strengthening region 12, the structure strength of the honeycomb structure 1 can be improved.

(Embodiment 2)
The honeycomb structure of the second embodiment will be described with reference to FIG. In addition, among the reference numerals used in the second and subsequent embodiments, the same reference numerals as those used in the above-mentioned embodiments represent the same components and the like as those in the above-mentioned embodiments, unless otherwise specified.

As shown in FIG. 5, that is, when a regular hexagon forming a boundary between the base region 11 and the outer peripheral strengthening region 12 is drawn, the apex of the hexagon is outside the outer peripheral wall 4 (outside the honeycomb diameter of the honeycomb structure 1). ) Exists. In FIG. 5, the virtual regular hexagon H is drawn as a regular hexagon forming a boundary between the base region 11 and the outer peripheral strengthening region 12. In this case, among the cells 2 in the base region 11, the cells 2 located on the outermost side in the radial direction of the honeycomb lined up along the first virtual straight line V1 are connected to the outer peripheral wall 4. That is, in the honeycomb structure 1 of the present embodiment, unlike the honeycomb structure 1 of the first embodiment, the deformation cell 22 does not appear on the first virtual straight line V1. The outer peripheral strengthening region 12 covers the outer circumference of the base region discontinuously in the circumferential direction. Other configurations are the same as those in the first embodiment.

Even if it has such a configuration, it can basically exert the same effect as that of the first embodiment. However, in the honeycomb structure 1 of the first embodiment, the flat cell 21 can be arranged further inside to form the outer peripheral strengthening region 12.

(Embodiment 3)
The honeycomb structure of the third embodiment will be described with reference to FIG.

As shown in FIG. 6, in the honeycomb structure 1 of the present embodiment, the length of the short cell wall 30 in the plurality of flat cells 21 in the outer peripheral strengthening region 12 becomes shorter as it gets closer to the outer peripheral wall 4.

The stress generated during canning increases as it approaches the outer peripheral wall 4. In the case of having the above configuration, the buckling stress of the short cell wall 30 becomes higher as the flat cell 21 is located closer to the outer peripheral wall 4. Therefore, according to the above configuration, the honeycomb structure 1 capable of effectively improving the strength of the structure can be obtained.

The length of the short cell wall 30 in the flat cell 21 is configured to gradually decrease toward the outer peripheral wall 4, or gradually decrease toward the outer peripheral wall 4, for example. Can be done.

Other configurations and effects are the same as in the first embodiment.

(Embodiment 4)
The honeycomb structure of the fourth embodiment will be described with reference to FIG. 7.

As shown in FIG. 7, in the honeycomb structure 1 of the present embodiment, the wall thickness of the cell wall 3 in the outer peripheral strengthening region 12 is thicker than the wall thickness of the cell wall 3 in the base region 11.

According to this configuration, the outer peripheral strengthening region 12 has a larger buckling stress per column length of one cell wall 3 constituting the hexagonal cell 2 than the base region 11. Therefore, the honeycomb structure 1 of the present embodiment is advantageous in improving the structure strength as compared with the honeycomb structure 1 of the first embodiment, which is an example in which the wall thickness of the cell wall 3 of the outer peripheral strengthening region 12 is not thickened. Is.

Whether or not the wall thickness t1 of the cell wall 3 in the outer peripheral strengthening region 12 is thicker than the wall thickness t of the cell wall 3 in the base region 11 is determined by determining the wall thickness t1 of the cell wall 3 in the outer peripheral strengthening region 12. It can be confirmed by comparing with the above-mentioned average value _tave in the first embodiment.

Other configurations and effects are the same as in the first embodiment.

(Embodiment 5)
The honeycomb structure of the fifth embodiment will be described with reference to FIG.

As shown in FIG. 8, in the honeycomb structure 1 of the present embodiment, both the base region 11 region and the outer peripheral strengthening region 12 have a reinforcing portion 32 having a corner R surface portion 321 at the cell apex portion 31. There is. The dimension of the corner radius portion 321 in the outer peripheral strengthening region 12 is larger than the dimension of the corner radius surface portion 321 in the base region 11.

According to this configuration, in the outer peripheral strengthening region 12, the column length of the cell wall 3 between the corner radius portions 321 is shorter than that in the base region 11. Therefore, the outer peripheral strengthening region 12 has a larger buckling stress per column length of one cell wall 3 constituting the hexagonal cell 2 than the base region 11. Therefore, the honeycomb structure 1 of the present embodiment is advantageous in improving the strength of the structure as compared with the honeycomb structure 1 of the first embodiment, which is an example of not having the reinforcing portion 32.

The above-mentioned reinforcing portion 32 may be formed in all the cell apex portions 31 of the base region 11 and the outer peripheral reinforcing portion 12, or even if there is a cell apex portion 31 in which the reinforcing portion 32 is not formed. good. The reinforcing portion 32 is a portion in which the cell apex portion 31 connecting the cell walls 3 to each other is thickened. That is, in the cell apex portion 31, the portion protruding inward of the cell 2 from the extension line 300 extending the flat surface portion of each cell wall 3 is referred to as the reinforcing portion 32. Specifically, the corner R surface portion 321 of the reinforcing portion 32 has a curved surface portion on the surface that is convex toward the cell apex portion 31 side.

The dimension of the angle R surface portion 321 in the base region 11 can be calculated as follows. For each cell vertex portion 31 constituting the central cell 20 and the six cells 2 surrounding the central cell 20, each corner R surface portion 321 (outside the cell 2 or inside the cell 2) formed on each cell vertex portion 31. The radius of the inscribed circle when the inscribed circle in contact with (including) is drawn (FIG. 8 (a)). Then, the average value r _ave of the radius of the inscribed circle is set to the dimension r of the angle R surface portion 321 in the base region 11. On the other hand, the dimension of the corner R surface portion 321 in the outer peripheral strengthening region 12 is the radius r1 of the inscribed circle when the inscribed circle in contact with the corner R surface portion 321 is drawn, as shown in FIG. 8 (b). Whether or not the dimension of the corner R surface portion 321 in the outer peripheral strengthening region 12 is larger than the dimension of the corner R surface portion 321 in the base region 11 is determined by averaging the dimension r1 of the corner R surface portion 321 in the outer peripheral reinforcement region 12 as described above. It can be confirmed by comparing with the value r _ave .

Other configurations and effects are the same as in the first embodiment.

(Embodiment 6)
The honeycomb structure of the sixth embodiment will be described with reference to FIGS. 9 and 10.

As shown in FIG. 9, in the honeycomb structure 1 of the present embodiment, the outer peripheral strengthening region 12 is viewed in a cross-sectional view perpendicular to the honeycomb central axis 10 in a direction along the side L of the virtual regular hexagon H. The area of the three-pronged unit 33 including the three cell walls 3 extending radially from the cell apex 31 located one by one along the cell wall 3 is equalized between the adjacent three-pronged units 33. Includes a reinforced structure. The circles in FIG. 9 indicate the positions of the soil supply holes of the mold (not shown) used in the manufacture of the honeycomb structure 1 (also in FIGS. 1, 4, 5, and 7 described above). The same is true). In addition, the raw material of the cell wall 3 of the honeycomb structure 1 prepared in the form of clay is supplied to the clay supply hole.

When the cell wall 3 is thickened or the size of the corner radius portion 321 is enlarged in the outer peripheral strengthening region 12, the cross-sectional area of the slit of the mold used at the time of molding the honeycomb structure 1 increases. As a result, the supply amount of the raw material required to form the cell wall 3 of the outer peripheral strengthening region 12 increases, the molding speed becomes slow, and the cell 2 is easily distorted. On the other hand, according to the above configuration, a reinforced structure having the same area between adjacent three-pronged units 33 is included. Therefore, according to the above configuration, it becomes easy to reduce the strain in the outer peripheral strengthening region 12 at the time of molding the honeycomb structure 1, and it becomes easy to improve the strength of the structure.

The area of the three-pronged unit 33 described above is specifically the area of the portion surrounded by the thick line as illustrated in FIG. That is, the total cross-sectional area of the three cell walls 3 (including the reinforcing portion 32), which are supplied by the soil supply holes at the time of forming the honeycomb, is the area of the portion surrounded by the thick line in FIG. Further, the boundary between the adjacent three-pronged units 33 is determined by drawing the center line M of the cell wall 3 and dividing the intersection portion of the adjacent three-pronged units 33 into three, as illustrated in FIG.

When comparing the areas of adjacent three-pronged units 33, when the area of one three-pronged unit 33 is within the range of 0.97 to 1.03 times the area of the other three-pronged unit 33. Since it can be said that it is within the range of error, it can be said that the areas are equivalent to each other.

Other configurations may be the same as those of the fourth or fifth embodiment. Further, other effects are the same as those in the fourth or fifth embodiment.

<Experimental Example 1>
As shown in Tables 1 and 2, it has a test piece 1C having a plurality of cells having a hexagonal cross section and having a honeycomb structure whose outer periphery is not reinforced, and a plurality of cells having a hexagonal cross section. Test bodies 1 to 15 composed of a honeycomb structure having a reinforced outer circumference were produced by extrusion molding with a mold. The produced honeycomb structure has a cylindrical outer peripheral wall, and all of them have a honeycomb diameter: diameter of 117 mm, a honeycomb base material length of 100 mm, and an outer peripheral wall thickness of 0.35 mm.

Here, as shown in FIG. 11, the test body 1C has a cell structure in which the outer peripheral reinforcing region 12 is not provided and the cells 2 having a regular hexagonal shape are spread from the honeycomb central axis 10 to the outer peripheral wall 4. .. This test body 1C is an example of a conventional honeycomb structure. On the other hand, the test bodies 1 to 4, 9, and 10 have an outer peripheral strengthening region 12 according to FIG. 5, have a flat cell 21, but do not have a deformed cell 22. Further, the test bodies 5 to 8 and 11 to 15 have an outer peripheral strengthening region 12 according to FIG. 1, and are examples having both a flat cell 21 and a deformed cell 22.

Then, for each test piece, the isostatic strength (mean value of n = 20, hereinafter omitted) and the pressure loss were measured.

The pressure loss was measured as follows. As schematically shown in FIG. 12, the piping portion 91, the accommodating portion 92 in which the honeycomb structure 1 is housed, and the enlarged diameter portion 93 connecting the piping portion 91 and the accommodating portion 92 are provided. The evaluation converter 9 to have was prepared. The diameter φ1 of the piping portion 91 was set to 50.5 mm. The diameter φ2 of the accommodating portion 92 was set to 123 mm. The length l1 of the enlarged diameter portion 93 was set to 55 mm. The distance l2 between one end surface of the honeycomb structure 1 and the enlarged diameter portion 93 on the one end surface side was set to 5 mm. The distance l3 between the other end surface of the honeycomb structure 1 and the enlarged diameter portion 93 on the other end surface side was set to 10 mm. The gas flow rate of the exhaust gas flowing through the honeycomb structure 1 was 7 m ³ / min, and the gas temperature was 600 degrees. A 4.6L V8 engine was used as the engine that generates exhaust gas.

As shown in Tables 1 and 2, in the test bodies 1 to 4, 9, and 10, h1 <h, p1≈p, and h1 of the flat cells in the same row of the outer peripheral strengthening region are equivalent. Further, in the test bodies 5 to 8 and 11 to 15, h1 <h, h2 <h, p1≈p, h1 of the flat cell in the same row of the outer peripheral strengthening region and h2 of the deformed cell are equivalent. Therefore, in each of the test bodies 1 to 15, the structure strength is improved while suppressing the increase in pressure loss as compared with the test body 1C as a comparative example having no outer peripheral strengthening region. confirmed. The exhaust pipe portion 91 connected to the catalytic converter is circular. Therefore, even after the exhaust gas flow spreads in the enlarged diameter portion 93, the exhaust gas flow has a circular shape and flows into the honeycomb structure. The pressure loss when flowing into the honeycomb structure becomes smaller when the cross-sectional area of the honeycomb structure effective for inflow is larger because the gas flow rate flowing into one cell becomes smaller. On the other hand, when the outer shape of the honeycomb structure is elliptical, the exhaust gas inflow portion is limited on the short axis side because the inflow gas is circular, and the cross-sectional area of the effective honeycomb structure becomes small. .. Therefore, the pressure loss becomes high. That is, in the elliptical honeycomb structure, there is a wasteful portion on the long axis side where the exhaust gas does not flow in.

Further, when the test bodies 1 to 15 are compared, the following can be found. Comparing the specimens 1 to 4, it can be seen that the isostatic strength is increased by shortening the length h1 of the short cell wall in the flat cell and increasing the flatness of the flat cell.

Comparing the test bodies 1 to 4, 9, and 10 with the test bodies 5, 7, 11, and 12, it is better to introduce the deformed cell in the outer peripheral strengthening region and increase the number of strengthening rows by the flat cell. It can be seen that a higher isostatic strength can be obtained as compared with the case where the above is not introduced.

Comparing the test bodies 5, 7, 11 and 12 with the test bodies 8 and 13, the length of the short cell wall in the flat cell is configured to be shorter as it approaches the outer peripheral wall in the outer peripheral strengthening region. It can be seen that it becomes easier to improve the isostatic strength while suppressing the increase in pressure loss.

Comparing the test bodies 1 to 5, 7, and 8 with the test bodies 9 to 13, the wall thickness of the cell wall in the outer peripheral strengthening region is made thicker than the wall thickness of the cell wall in the base region, so that the flat cell It can be seen that higher isostatic strength can be obtained by the synergistic effect with the effect of introduction.

Comparing the test bodies 3 and 4 with the test bodies 14 and 15, the effect of introducing the flat cell is obtained by expanding the dimension of the corner radius portion in the outer peripheral strengthening region to be larger than the dimension of the corner radius portion in the base region. It can be seen that a higher isostatic strength can be obtained by the synergistic effect.

Comparing the test piece 5 and the test piece 6, when looking at the direction along the side of the virtual regular hexagon in the cross-sectional view perpendicular to the honeycomb central axis, from the cell apex which is one by one along the cell wall. In sample 5, the area of the three-pronged unit including the three radially extending cell walls was equalized between the adjacent three-pronged units, and the area of the three-pronged unit was equalized between the adjacent three-pronged units. The average isostatic strength and the minimum isostatic strength were higher than those of the different sample 6. The maximum isostatic strength did not change so much between the sample 5 and the sample 6. This is because when the cross-sectional areas of the three-pronged units are different, molding defects such as cell twisting often occur during the extrusion molding of the honeycomb structure.

The present invention is not limited to each of the above embodiments and experimental examples, and various modifications can be made without departing from the gist thereof. In addition, each configuration shown in each embodiment and each experimental example can be arbitrarily combined.

1 Honeycomb structure 10 Honeycomb central axis 11 Base area 12 Outer peripheral reinforcement area 2 Cell 20 Central cell 21 Flat cell 3 Cell wall 30 Short cell wall 4 Outer wall p Outer wall p Cell pitch in base area p1 Cell pitch in flat cell h In base area Length of cell wall constituting the direction perpendicular to the side of the virtual regular hexagon h1 Length of the short cell wall constituting the direction perpendicular to the side of the virtual regular hexagon in the outer peripheral reinforcement region H Virtual regular hexagon L Virtual regular hexagon Honeycomb

Claims (7)

A plurality of cells (2) having a hexagonal cross section adjacent to each other, a plurality of cell walls (3) forming the plurality of cells, and an outer peripheral wall provided on the outer periphery of the plurality of cell walls to hold the cell walls. (4) and a honeycomb structure (1) having
In cross-sectional view perpendicular to the honeycomb center axis (10)
A base region having a regular hexagonal center cell (20) in which the honeycomb center axis passes through the center of the cell, which is composed of a plurality of regular hexagonal cells.
It is configured to include a plurality of cells having a non-regular hexagonal shape, and has an outer peripheral strengthening region (12) arranged on the outer circumference of the base region.
The outer peripheral strengthening region is a direction perpendicular to the side (L) of the virtual regular hexagon when the virtual regular hexagon (H) whose B axis is tilted by 30 degrees with respect to the center cell is drawn coaxially with the center cell. A non-regular hexagonal flat cell (21) formed by using a pair of short cell walls (30) in which the length of the cell wall constituting the cell wall is shorter than the length of the cell wall in the base region. Have multiple
The plurality of the flat cells are arranged side by side along the sides of the virtual regular hexagon.
When viewed along the sides of the virtual regular hexagon, the cell pitch of the flat cell is equivalent to the cell pitch of the cell in the base region.
Honeycomb structure (1) in which the lengths of the short cell walls of the flat cells arranged in the same row along the sides of the virtual regular hexagon are the same. The outer peripheral reinforcement region is the virtual regular hexagon extending from each vertex of the virtual regular hexagon on each of the six first virtual straight lines (V1) connecting the center axis of the honeycomb and the vertices of the virtual regular hexagon. A modified cell (22) formed by using a first cell wall (341) forming a direction perpendicular to one of the two sides of the above and a second cell wall (342) forming a direction perpendicular to the other. ) Has at least one
The lengths of the first cell wall and the second cell wall of the deformed cell are shorter than the length of the cell wall in the base region constituting the direction perpendicular to each side of the virtual regular hexagon. Ori,
The lengths of the first cell wall and the second cell wall of the deformed cell are equal to the length of the short cell wall of the flat cell arranged in the same row in the direction along the side of the virtual regular hexagon. The honeycomb structure according to claim 1. The honeycomb structure according to claim 1 or 2, wherein the length of the short cell wall in each of the flat cells becomes shorter as it gets closer to the outer peripheral wall. The honeycomb structure according to any one of claims 1 to 3, wherein the outer peripheral reinforcing region is composed of regions up to any one row at least in the fourth row or more counting from the outer peripheral wall side. The honeycomb structure according to any one of claims 1 to 4, wherein the wall thickness of the cell wall in the outer peripheral strengthening region is thicker than the wall thickness of the cell wall in the base region. Both the base region and the outer peripheral strengthening region have a reinforcing portion (32) having a corner radius portion (321) at the cell apex portion (31).
The honeycomb structure according to any one of claims 1 to 5, wherein the dimension of the corner R surface portion in the outer peripheral strengthening region is larger than the dimension of the corner R surface portion in the base region. The outer peripheral strengthening region is when viewed in the direction along the side of the virtual regular hexagon in the cross-sectional view perpendicular to the honeycomb center axis.
The area of the three-pronged unit (33) including the three cell walls extending radially from the cell apex (31) located one by one along the cell wall is between the adjacent three-pronged units. The honeycomb structure according to any one of claims 1 to 6, which includes a reinforced structure equivalent to that in the above.

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