JP2017094225A - Honeycomb structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a honeycomb structure suppressing the increase of pressure loss in all cells including the outermost peripheral cell.SOLUTION: In a honeycomb structure 1, a first cell 11a has plural outermost peripheral first cells 16a adjacent to an outer peripheral wall 14 and plural inner peripheral first cells 17a positioning inside a ceramic block 10 rather than the outermost peripheral first cells 16a. At least a part of the plural outermost peripheral first cells 16a is a short seal first cell 161a in which the length of a sealed portion in a longitudinal direction is shorter than that of the sealed portion in the same direction in the plural inner peripheral first cell 17a. In the plural outermost peripheral first cells 16a, the average length of the sealed portion in the longitudinal direction is shorter than that of the sealed portion in the same direction in the plural inner peripheral first cell 17a.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a honeycomb structure for collecting soot contained in exhaust gas discharged from an internal combustion engine such as a diesel engine.

  In recent years, there has been a problem that particulates such as soot contained in exhaust gas discharged from an internal combustion engine such as a diesel engine (hereinafter referred to as PM) harm the environment and the human body. Accordingly, various honeycomb structures made of porous ceramics have been proposed as filters for collecting PM in exhaust gas and purifying the exhaust gas.

  Conventionally, as this type of honeycomb structure, an outer peripheral wall, a cell wall formed inside the outer peripheral wall, and a plurality of cells partitioned by the cell wall and arranged in parallel so as to extend in the longitudinal direction There is known a honeycomb structure having a columnar ceramic block containing, and an outer peripheral coating layer formed on the outer periphery of the ceramic block. Of the plurality of cells in the longitudinal direction, either one of the end portions on the inlet side or the outlet side of the exhaust gas is sealed. Therefore, the exhaust gas that has flowed into the cell in which the end portion on the outlet side of the exhaust gas is sealed flows out of the cell in which the end portion on the inlet side of the exhaust gas is sealed after passing through the cell wall separating the cells. Therefore, when exhaust gas passes through the honeycomb structure, PM in the exhaust gas is collected on the cell wall. Thereby, exhaust gas can be purified.

  As a honeycomb structure having such a structure, for example, in Patent Document 1, the area and the shape in the cross section perpendicular to the longitudinal direction of a plurality of cells are equal, and the end portion on the outlet side of the exhaust gas is sealed. A honeycomb structure in which the number of cells is larger than the number of cells sealed at the end on the inlet side of exhaust gas is disclosed. In such a honeycomb structure, the total surface area of the cell wall defining the cell sealed at the end on the exhaust gas outlet side is equal to the cell wall partitioning the cell sealed at the end on the exhaust gas inlet side. Greater than the total surface area. Therefore, the cell wall surface area (hereinafter referred to as filtration area) that can contribute to PM filtration can be increased.

  Further, for example, in Patent Documents 2 and 3, a plurality of cells include a large-capacity cell group having a relatively large sum of areas in a cross section perpendicular to the longitudinal direction, and a small sum having a relatively small sum of areas in the cross section. A honeycomb structure including a volume cell group is disclosed. In such a honeycomb structure, the large-capacity cell group is an inflow side cell in which the end on the exhaust gas outlet side is sealed, so that the total surface area of the cell wall defining the inflow side cell is relatively large. Become. Therefore, the PM filtration area can be increased.

  Thus, in the honeycomb structure disclosed in Patent Documents 1 to 3, the PM filtration area can be increased. Thereby, since the thickness of PM layer deposited on a cell wall can be made thin, the raise of the pressure loss of a honeycomb structure at the time of PM collection can be suppressed. Therefore, the PM collection limit amount of the honeycomb structure can be increased.

  Further, Patent Document 4 discloses a honeycomb structure in which the thickness of the outer peripheral wall is thicker than the thickness of the cell wall formed inside the outer peripheral wall from the viewpoint of improving the mechanical strength of the honeycomb structure. Yes. Further, in Patent Document 5, the length in the longitudinal direction of the sealed portion of the cell (hereinafter referred to as the length of the sealing portion) from the viewpoint of dispersing the portion where the combustion heat concentrates in the honeycomb structure. There is disclosed a honeycomb structure which is intentionally made non-uniform.

U.S. Pat. No. 4,417,908 European Patent Application No. 1493479 European Patent Application No. 1514588 US Patent Application Publication No. 5952079 European Patent Application No. 0737801

  However, in the honeycomb structures disclosed in Patent Documents 1 to 3, the outermost peripheral cells adjacent to the outer peripheral wall are positioned so that the number of adjacent cells across the cell wall is more inside the ceramic block than the outermost peripheral cells. Less than the number of cells in the inner cell. For example, when the shape of the cross section perpendicular to the longitudinal direction of the cell is a quadrangle, the inner peripheral cell is adjacent to the four cells across the cell wall located in the four directions of the inner peripheral cell. On the other hand, since the outermost peripheral cell exists only in three directions even if there are many cell walls, it is adjacent to at most three cell walls across the cell wall. Thus, when the number of cells adjacent to each other with the cell wall interposed therebetween is small, the surface area of the cell wall through which the exhaust gas passes becomes small. Therefore, the filtration area of PM becomes small in the cell wall which divides the outermost peripheral cell. As a result, when collecting PM, the outermost peripheral cell of the honeycomb structure has a problem that pressure loss tends to increase. In addition, when the PM filtration area is reduced in the cell walls that define the outermost peripheral cells, the honeycomb structure has a variation in the PM filtration area as a whole. As a result, a turbulent flow of the exhaust gas tends to occur inside the honeycomb structure, and there is a problem that the pressure loss tends to increase as a whole.

  Moreover, since the thickness of the outer peripheral wall of the honeycomb structure disclosed in Patent Document 4 is larger than the thickness of the cell wall, the surface area of the cell wall defining the outermost peripheral cell is relatively small. Therefore, the filtration area of PM becomes small in the cell wall which divides the outermost peripheral cell. As a result, when collecting PM, the outermost peripheral cell of the honeycomb structure has a problem that pressure loss tends to increase. In addition, when the PM filtration area is reduced in the cell walls that define the outermost peripheral cells, the honeycomb structure has a variation in the PM filtration area as a whole. As a result, the turbulent flow of the exhaust gas tends to occur inside the honeycomb structure, so that there is a problem that the pressure loss tends to increase as a whole. However, Patent Document 4 does not mention at all the fact that the pressure loss deteriorates and the measures to improve it.

  Furthermore, since the honeycomb structure disclosed in Patent Document 5 has a different length of the sealing portion for each cell, the PM filtration area is different for each cell. As a result, there has been a problem that turbulent flow of exhaust gas tends to occur inside the honeycomb structure, and the pressure loss tends to increase as a whole honeycomb structure. Moreover, the honeycomb structure disclosed in FIG. 6 as a comparative example has a configuration in which the length of the sealing portion gradually increases from the outer periphery in the direction perpendicular to the longitudinal direction toward the central portion. However, the honeycomb structure having such a configuration increases the heat capacity of the central portion by increasing the length of the sealing portion in the central portion. As a result, the honeycomb structure has a problem that the heat capacity in the direction perpendicular to the longitudinal direction becomes non-uniform and cracks are likely to occur. However, Patent Document 5 does not mention at all about the pressure loss worsening, the heat capacity becoming non-uniform, and cracks being easily generated, and these improvement measures.

  The present invention has been made in view of the above situation, and an object thereof is to provide a honeycomb structure in which an increase in pressure loss is suppressed in all cells including the outermost peripheral cell.

  A honeycomb structure according to an embodiment of the present invention is arranged side by side so that an outer peripheral wall, a cell wall formed inside the outer peripheral wall, and a plurality of cells partitioned by the cell wall extend in the longitudinal direction. The plurality of cells each have a first cell sealed at one end and a second cell sealed at the other end. The first cell and the second cell are alternately arranged in at least one direction in a cross section perpendicular to the longitudinal direction, and the first cell includes a plurality of outermost walls adjacent to the outer peripheral wall. An outer peripheral first cell; and a plurality of inner peripheral first cells located inside the ceramic block with respect to the outermost peripheral first cell, and at least a part of the outermost outer periphery of the plurality of outermost peripheral first cells In the first cell, the length of the sealed portion in the longitudinal direction is the above-mentioned multiple. A short-sealed first cell shorter than the length in the longitudinal direction of the sealed portion in the inner peripheral first cell, and the plurality of outermost peripheral first cells have an average length in the longitudinal direction of the sealed portion. Is shorter than the average length in the longitudinal direction of the sealed portion in the plurality of inner peripheral first cells, and the average thickness of the outer peripheral wall is thicker than the average thickness of the cell walls (first configuration). ).

  With the above configuration, when the exhaust gas flows into the first cell, the surface area of the cell wall through which the exhaust gas passes can be increased in the cell wall that partitions the short-sealed first cell. As a result, an increase in pressure loss can be suppressed in the short-sealed first cell. Further, the honeycomb structure as a whole can reduce variation in the PM filtration area on the cell wall. Thereby, generation | occurrence | production of the turbulent flow of exhaust gas can be suppressed inside a honeycomb structure, and the raise of a pressure loss can be suppressed as the whole honeycomb structure.

  Further, conventionally, in the outermost peripheral cell adjacent to the outer peripheral wall, as shown in FIG. 1 (a), when exhaust gas flows from one cell through the cell wall located between the cells to the other cell, It was thought. That is, the outer peripheral wall was thought not to contribute to PM filtration. However, as shown in FIG. 1 (a), most of the exhaust gas flowing in the outermost peripheral cell flows from one cell to the other cell through the cell wall located between the cells. On the other hand, as shown in FIG. 1B, a part of the exhaust gas flows from one cell to the other cell through the outer peripheral wall (hereinafter referred to as a bypass route). A dense outer coat layer is often formed on the outer periphery of the outer peripheral wall. Therefore, in the detour path, by increasing the thickness of the outer peripheral wall, the area of the outer peripheral wall through which the exhaust gas can pass can be increased. On the other hand, when the thickness of the outer peripheral wall is increased, the pressure loss increases in the outermost peripheral cell in contact with the outer peripheral wall. Therefore, in the honeycomb structure according to the first configuration, the average thickness of the outer peripheral wall is larger than the average thickness of the cell wall, and at least some of the outermost peripheral first cells among the plurality of outermost peripheral first cells. A short-sealed first cell in which the length in the longitudinal direction of the sealed portion is shorter than the length in the longitudinal direction of the portion sealed in the plurality of inner peripheral first cells. That is, in the honeycomb structure according to the first configuration, even when the average thickness of the outer peripheral wall is thicker than the average thickness of the cell wall, the exhaust gas is generated on the cell wall and the outer peripheral wall that define the short-sealed first cell. It is possible to increase the surface area of the cell wall and the outer peripheral wall that pass therethrough. That is, an increase in pressure loss can be suppressed in the short-sealed first cell. In addition, by suppressing an increase in pressure loss in the short-sealed first cell, the difference between the pressure loss in the short-sealed first cell and the pressure loss in the inner peripheral cell is reduced, and turbulence of the exhaust gas is generated inside the honeycomb structure. The flow is less likely to occur. As a result, an increase in pressure loss can be suppressed as the entire honeycomb structure.

  In the honeycomb structure according to the first configuration, the average thickness of the outer peripheral wall is larger than the average thickness of the cell wall. When the average thickness of the outer peripheral wall is large, the honeycomb structure simply has improved mechanical strength as a whole. On the other hand, the heat capacity of the outer peripheral wall is larger than the heat capacity of the cell wall. Therefore, the honeycomb structure as a whole has a large variation in heat capacity, and cracks are likely to occur. However, in the honeycomb structured body according to the first configuration, in the short-sealed first cell, the length in the longitudinal direction of the sealed portion is the length of the portion sealed in the plurality of inner peripheral first cells. Shorter than the length of the direction. Therefore, the heat capacity is relatively small in the short-sealed first cell. As a result, in the portion where the outer peripheral wall and the short-sealed first cell are adjacent, the heat capacity is approximately the same as the heat capacity in the inner peripheral first cell. Therefore, since the honeycomb structure has a uniform heat capacity as a whole, occurrence of cracks can be suppressed.

  In the first configuration, all of the plurality of outermost peripheral first cells are the short-sealed first cells (second configuration).

  Thereby, in the cell wall and outer peripheral wall which divide all the outermost periphery 1st cells, the surface area of the cell wall and outer peripheral wall through which exhaust gas passes can be enlarged. As a result, an increase in pressure loss can be suppressed in the outermost peripheral first cell. Moreover, the honeycomb structure as a whole can further reduce variation in the filtration area of PM on the cell wall. Thereby, generation | occurrence | production of the turbulent flow of exhaust gas can be suppressed inside a honeycomb structure, and the raise of a pressure loss can be suppressed more as a whole honeycomb structure.

  In the first or second configuration, the length in the longitudinal direction of the sealed portion of the short-sealed first cell and the average length in the longitudinal direction of the sealed portion of the inner peripheral first cell The difference is 0.5 to 5.0 mm (third configuration).

  The difference between the length in the longitudinal direction of the sealed portion of the short-sealed first cell and the average length in the longitudinal direction of the sealed portion of the inner peripheral first cell (hereinafter, the length of the sealed portion) If the difference is less than 0.5 mm, there is no significant difference compared to the conventional configuration. Therefore, the PM filtration area in the cell wall that partitions the short-sealed first cell cannot be sufficiently increased, and an increase in pressure loss of the honeycomb structure may not be suppressed. Further, if the difference in length of the sealing portion exceeds 5.0 mm, the length in the longitudinal direction of the sealed portion of the short-sealed first cell is sealed by the inner peripheral first cell. It becomes extremely shorter than the average length in the longitudinal direction. Therefore, the sealing material may escape from the end of the short-sealed first cell due to the pressure of the exhaust gas that has entered the honeycomb structure.

  Moreover, since the heat capacity of the honeycomb structure is uniform as a whole when the difference in the length of the sealing portion is 0.5 to 5.0 mm, the occurrence of cracks can be suppressed. When the difference in the length of the sealing portion is less than 0.5 mm, there is no significant difference compared to the configuration of the conventional honeycomb structure. Therefore, the heat capacity of the outer peripheral wall becomes larger than the heat capacity of the cell wall. Therefore, the honeycomb structure as a whole has a large variation in heat capacity, and cracks are likely to occur. When the difference in the length of the sealing portion exceeds 5.0 mm, the length in the longitudinal direction of the sealed portion of the short-sealed first cell is the same as that of the inner peripheral first cell. It becomes extremely shorter than the average length in the longitudinal direction. For this reason, the short-sealed first cell has a smaller heat capacity. As a result, in the portion where the short-sealed first cell and the outer peripheral wall are adjacent, the heat capacity may be smaller than the heat capacity in the inner peripheral first cell. As a result, the honeycomb structure as a whole has a non-uniform heat capacity, and cracks may occur.

  In any one of the first to third configurations, all of the plurality of inner peripheral first cells have a length in a longitudinal direction of a sealed portion, the plurality of inner peripheral first cells. It is 0.75-1.25 times with respect to the average length of the longitudinal direction of the part sealed in (4th structure).

  With the above configuration, when the exhaust gas flows into the first cell, the surface area of the cell wall through which the exhaust gas passes can be made uniform on the cell wall that partitions the inner peripheral first cell. As a result, variation in the filtration area of PM on the cell wall can be reduced. Thereby, generation | occurrence | production of the turbulent flow of exhaust gas can be suppressed inside a honeycomb structure, and the raise of a pressure loss can be suppressed as the whole honeycomb structure.

  In any one of the first to fourth configurations, the second cell includes a plurality of outermost peripheral second cells adjacent to the outer peripheral wall, and the ceramic block more than the outermost peripheral second cell. A plurality of inner peripheral second cells located on the inner side, and at least some of the outermost peripheral second cells of the plurality of outermost peripheral second cells have a length in a longitudinal direction of a sealed portion, The plurality of inner peripheral second cells are short sealed second cells shorter than the length in the longitudinal direction of the sealed portion, and the plurality of outermost peripheral second cells are arranged in the longitudinal direction of the sealed portion. The average length is shorter than the average length in the longitudinal direction of the portion sealed in the plurality of inner peripheral second cells (fifth configuration).

  With the above configuration, the first cell adjacent to the short-sealed second cell across the cell wall has the surface area of the cell wall and the outer peripheral wall through which the exhaust gas passes in the cell wall and the outer peripheral wall defining the first cell. Can be larger. As a result, an increase in pressure loss can be suppressed in the first cell adjacent to the short-sealed second cell across the cell wall. Moreover, the honeycomb structure as a whole can further reduce variation in the filtration area of PM on the cell wall. Thereby, generation | occurrence | production of the turbulent flow of exhaust gas can be suppressed inside a honeycomb structure, and the raise of a pressure loss can be suppressed more as a whole honeycomb structure.

  In any one of the first to fifth configurations, the short-sealed first cell is sealed in the plurality of inner peripheral second cells in the longitudinal direction of the sealed portion. Shorter than the length in the longitudinal direction of the formed portion (sixth configuration).

  With the above configuration, when the exhaust gas flows into the first cell, the surface area of the cell wall and the outer peripheral wall through which the exhaust gas passes can be sufficiently increased in the cell wall and the outer peripheral wall that define the short-sealed first cell. . As a result, an increase in pressure loss can be suppressed in the short-sealed first cell. Further, the honeycomb structure as a whole can reduce variation in the PM filtration area on the cell wall. Thereby, generation | occurrence | production of the turbulent flow of exhaust gas can be suppressed inside a honeycomb structure, and the raise of a pressure loss can be suppressed more as a whole honeycomb structure.

  In any one of the first to sixth configurations, the first cell is an inlet-side cell into which exhaust gas flows, and the second cell is an outlet-side cell from which exhaust gas flows out (first 7 configuration).

  By making the first cell the inlet side cell, the cell wall and the outer peripheral wall defining the short-sealed first cell can increase the surface area on the inflow side of the cell wall and the outer peripheral wall through which the exhaust gas passes. As a result, an increase in pressure loss can be suppressed in the short-sealed first cell. Further, the honeycomb structure as a whole can reduce variation in the PM filtration area on the cell wall. Thereby, generation | occurrence | production of the turbulent flow of exhaust gas can be suppressed inside a honeycomb structure, and the raise of a pressure loss can be suppressed more as a whole honeycomb structure.

  In the honeycomb structure according to the embodiment of the present invention, at least a part of the outermost peripheral first cells among the plurality of outermost peripheral first cells has a length in a longitudinal direction of the sealed portion having a plurality of inner peripheries. The first cell is a short-sealed first cell shorter than the length in the longitudinal direction of the portion sealed in the first cell, and the plurality of outermost peripheral first cells have a plurality of average lengths in the longitudinal direction of the sealed portion. The inner peripheral first cell is shorter than the average length in the longitudinal direction of the sealed portion. Therefore, when the exhaust gas flows into the first cell, the surface area of the cell wall and the outer peripheral wall through which the exhaust gas passes can be increased in the cell wall and the outer peripheral wall defining the short-sealed first cell. As a result, an increase in pressure loss can be suppressed in the short-sealed first cell. Further, the honeycomb structure as a whole can reduce variation in the PM filtration area on the cell wall. Thereby, generation | occurrence | production of the turbulent flow of exhaust gas can be suppressed inside a honeycomb structure, and the raise of a pressure loss can be suppressed as the whole honeycomb structure.

1 (a) and 1 (b) are diagrams schematically showing the flow of exhaust gas in a part of a cross section perpendicular to the longitudinal direction of a conventional honeycomb structure. FIG. 2 is a perspective view schematically showing the honeycomb structure 1 according to the embodiment of the present invention. FIG. 3 is a cross-sectional view of the honeycomb structure 1 shown in FIG. 2 taken along the line III-III. FIG. 4 is a diagram schematically showing a configuration of a simulation model for calculating the pressure loss in a part of a cross section perpendicular to the longitudinal direction of the honeycomb structures of Example 1, Example 2, and Comparative Example 1. . FIG. 5 is a diagram schematically showing a configuration of a simulation model for calculating pressure loss in a part of a cross section parallel to the longitudinal direction of the honeycomb structures of Example 1, Example 2, and Comparative Example 1. . FIG. 6 is a graph showing pressure loss in the simulation models of Example 1, Example 2, and Comparative Example 1. FIG. 7 is a perspective view schematically showing an aggregated honeycomb structure 2 that is an example of a honeycomb structure according to another embodiment. FIG. 8 is a perspective view schematically showing an example of one ceramic member constituting the honeycomb structure 2 shown in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the dimension of the structural member in each figure does not represent the dimension of an actual structural member, the dimension ratio of each structural member, etc. faithfully.

1. Configuration of Honeycomb Structure First, the configuration of the honeycomb structure 1 according to an embodiment of the present invention (hereinafter also referred to as the present embodiment) will be described.

(overall structure)
FIG. 2 is a perspective view schematically showing the honeycomb structure 1 according to the embodiment of the present invention. FIG. 3 is a cross-sectional view taken along the line III-III of the honeycomb structure 1 shown in FIG.

  As shown in FIG. 2, the honeycomb structure 1 is formed in a columnar shape as a whole. The honeycomb structure 1 includes a columnar ceramic block 10 and an outer peripheral coat layer 15 formed on the outer periphery of the ceramic block 10 to protect the cells 11 provided in the ceramic block 10.

  2 and 3, the ceramic block 10 includes an outer peripheral wall 14, a cell wall 12 formed inside the outer peripheral wall 14, and a plurality of cells 11 partitioned by the cell wall 12. Are arranged side by side so as to extend in the longitudinal direction. The plurality of cells 11 include a first cell 11 a in which one end portion is sealed with the sealing material 13 among both end portions in the longitudinal direction, and the other end portion is sealed with the sealing material 13. And a second cell 11b. The first cell 11a and the second cell 11b are alternately arranged in parallel along two orthogonal directions in the cross section perpendicular to the longitudinal direction, that is, along the X direction and the Y direction shown in FIG. Here, the longitudinal direction means the extending direction of the columnar honeycomb structure, that is, the Z direction shown in FIG. In addition, it is preferable that the circular diameter of the ceramic block 10 is 100-150 mm. Moreover, it is preferable that the length of the said longitudinal direction is 100-180 mm.

  Hereinafter, each configuration of the honeycomb structure 1 will be described in detail.

(Multiple cells)
As shown in FIGS. 2 and 3, the plurality of cells 11 includes a first cell 11a and a second cell 11b. One end of the first cell 11 a is sealed with a sealing material 13. The other end of the second cell 11 b is sealed with the sealing material 13. That is, the other end of the first cell 11a is open, and the one end of the second cell 11b is open.

  The first cell 11a has a plurality of outermost peripheral first cells 16a adjacent to the outer peripheral wall 14, and a plurality of inner peripheral first cells 17a located inside the ceramic block 10 relative to the outermost peripheral first cells 16a. The second cell 11b includes a plurality of outermost peripheral second cells 16b adjacent to the outer peripheral wall 14, and a plurality of inner peripheral second cells 17b located inside the ceramic block 10 relative to the outermost peripheral second cell 16b. Have. The outermost peripheral first cell 16a and the outermost peripheral second cell 16b are also referred to as the outermost peripheral cell, and the inner peripheral first cell 17a and the inner peripheral second cell 17b are also referred to as inner peripheral cells.

  The inner peripheral first cell 17a and the inner peripheral second cell 17b are quadrangles whose cross sections perpendicular to the longitudinal direction have the same size. On the other hand, the outermost peripheral first cell 16 a and the outermost peripheral second cell 16 b have a shape such that a part of the cross section extends along the outer periphery of the ceramic block 10 in the cross section perpendicular to the longitudinal direction. The outermost peripheral first cell 16a and the outermost peripheral second cell 16b are different from each other in shape and area of the cross section. Here, the shape of the cross section perpendicular to the longitudinal direction refers to the shape formed by the inner wall of the cell wall that partitions each cell in the cross section perpendicular to the longitudinal direction. Further, the area of the cross section perpendicular to the longitudinal direction refers to the area of the portion surrounded by the inner wall of the cell wall that divides each cell in the cross section perpendicular to the longitudinal direction.

In the honeycomb structure 1 according to the present embodiment, the number per unit area of the cells 11 in the cross section perpendicular to the longitudinal direction is preferably 31 to 62 / cm ² (200 to 400 / inch ² ). .

(Cell wall and outer wall)
As described above, the ceramic block 10 includes the outer peripheral wall 14 and the cell wall 12 formed inside the outer peripheral wall 14. As shown in FIG. 2, the cell wall 12 is provided so as to partition the first cell 11a and the second cell 11b. That is, the first cell 11 a and the second cell 11 b are each surrounded by the cell wall 12. In addition, as shown in FIG. 2, in the honeycomb structure 1, since the first cell 11a and the second cell 11b are provided side by side, the cell wall 12 and the second cell 11b that partition the first cell 11a are provided. The cell wall 12 to be divided is the same cell wall 12.

  The thickness of the cell wall 12 is preferably 150 to 300 μm. When the thickness of the cell wall 12 is less than 150 μm, the strength of the honeycomb structure 1 may not be sufficient. On the other hand, when the thickness of the cell wall 12 exceeds 300 μm, the exhaust gas passage resistance increases, and thus the pressure loss of the honeycomb structure may increase. Here, the thickness of the cell wall 12 refers to the shortest distance between the inner wall of the cell wall 12 that partitions the first cell 11a and the inner wall of the cell wall 12 that partitions the second cell 11b. Further, the average thickness of the outer peripheral wall 14 is thicker than the average thickness of the cell wall 12. The thickness of the outer peripheral wall 14 is preferably 400 to 800 μm.

  The thickness of the cell wall 12 and the outer peripheral wall 14 is measured by the following method. First, the honeycomb structure 1 is cut into two so that the lengths in the longitudinal direction are equal, and then the cut surface is observed with a microscope. And let the average value of the value measured in arbitrary 10 places be the thickness of the cell wall 12 and the outer peripheral wall 14, respectively.

  The cell wall 12 and the outer peripheral wall 14 are preferably made of a porous ceramic member. The material of the porous ceramic member is not particularly limited. For example, carbide ceramics such as silicon carbide, titanium carbide, tantalum carbide, and tungsten carbide, nitride ceramics such as aluminum nitride, silicon nitride, boron nitride, and titanium nitride. And oxide ceramics such as alumina, zirconia, cordierite, mullite, and aluminum titanate, and silicon-containing silicon carbide. Among these, cordierite, aluminum titanate and the like which are excellent in thermal shock resistance are preferable.

  When the cell wall 12 is made of a porous ceramic member, the porosity is not particularly limited, but is preferably 20 to 80%. If the porosity is less than 20%, the surface of the cell wall 12 is likely to be clogged with PM, so that the pressure loss of the honeycomb structure 1 may increase. On the other hand, when the porosity exceeds 80%, the strength of the honeycomb structure 1 may decrease.

  The porosity is measured using a mercury intrusion method under the conditions of a contact angle of 130 ° and a surface tension of 485 mN / m.

(Encapsulant)
As shown in FIGS. 2 and 3, in the honeycomb structure 1 according to the present embodiment, one end of each of the first cells 11 a and the second cells 11 b is sealed with a sealing material 13. All of the plurality of outermost first cells 16a have a sealed portion in which the length in the longitudinal direction (hereinafter referred to as the length of the sealing portion) is the sealing portion in the plurality of inner peripheral first cells 17a. The short-sealed first cell 161a is shorter than the length of the first cell 161a. Therefore, in the plurality of outermost peripheral first cells 16a, the average length in the longitudinal direction of the sealed portion (hereinafter referred to as the average length of the sealing portion) is the sealing portion in the plurality of inner peripheral first cells 17a. Shorter than the average length. In the honeycomb structure 1, not all of the plurality of outermost peripheral first cells 16a may be the short-sealed first cells 161a.

  As described above, in the honeycomb structure 1, the average thickness of the outer peripheral wall 14 is larger than the average thickness of the cell walls 12. When the average thickness of the outer peripheral wall 14 is large, the honeycomb structure 1 simply has improved mechanical strength as a whole. On the other hand, the heat capacity of the outer peripheral wall 14 is larger than the heat capacity of the cell wall 12. Therefore, the honeycomb structure 1 as a whole has large variations in heat capacity, and cracks are likely to occur. However, in the honeycomb structure 1, in all of the plurality of outermost peripheral first cells 16a, the length of the sealing portion is shorter than the length of the sealing portion in the plurality of inner peripheral first cells 17a. Therefore, in the outermost peripheral first cell 16a, the heat capacity becomes relatively small. As a result, the outer peripheral wall 14 and the outermost outer peripheral first cell 16a are adjacent to each other, so that the heat capacity becomes approximately the same as the heat capacity of the inner peripheral first cell 17a. Therefore, since the honeycomb structure 1 has a uniform heat capacity as a whole, the occurrence of cracks can be suppressed.

  The short-sealed first cells 161 a are provided at equal intervals on the entire outermost periphery composed of the outermost peripheral cells adjacent to the outer peripheral wall 14. However, in the honeycomb structure 1, the short-sealed first cells 161a may not be provided at equal intervals on the entire outermost periphery.

  The difference between the length of the sealing portion of the short sealing first cell 161a and the average length of the sealing portion of the inner peripheral first cell 17a (referred to as the length indicated by p in FIG. The difference in length) is preferably 0.5 to 5.0 mm. Further, the difference in the length of the sealing part is more preferably 0.7 mm or more, and more preferably 4.0 mm or less.

  When the difference in the length of the sealing portion is 0.5 to 5.0 mm, the honeycomb structure 1 has a uniform heat capacity as a whole, so that the occurrence of cracks can be suppressed. When the difference in the length of the sealing portion is less than 0.5 mm, there is no significant difference compared to the configuration of the conventional honeycomb structure. Therefore, the heat capacity of the outer peripheral wall 14 is larger than the heat capacity of the cell wall 12. Therefore, the honeycomb structure 1 as a whole has a large variation in heat capacity, and cracks are likely to occur. When the difference in the length of the sealing part exceeds 5.0 mm, the length of the sealing part of the short sealing first cell 161a is equal to the average length of the sealing part of the inner peripheral first cell 17a. Compared to extremely short. Therefore, the short-sealed first cell 161a has a smaller heat capacity. As a result, in the portion where the short-sealed first cell 161a and the outer peripheral wall 14 are adjacent, the heat capacity may be smaller than the heat capacity in the inner peripheral first cell 17a. As a result, the honeycomb structure 1 as a whole may have a non-uniform heat capacity and cracks may occur.

  The length of the sealing portion refers to a value measured at the position of the center of gravity of the cross-sectional shape perpendicular to the longitudinal direction of the cell. Specifically, in the case of the inner peripheral first cell 17a, the shape of the cross section is a quadrangle. Therefore, the length of the sealing portion is measured at the center of gravity of the square. Moreover, in the case of the short sealing 1st cell 161a, the shape of the said cross section consists of one circular arc side and a some linear side. Therefore, the one arcuate side is replaced with one straight side to form a triangle, a quadrangle, or a pentagon composed of a plurality of straight sides. And the length of a sealing part is measured in the gravity center position of the said triangle, the said square, or the said pentagon. In addition, even if the sealing material 13 is not filled to the edge part of the said cell of the said longitudinal direction, it does not affect the filtration area of PM. Therefore, the length of the sealing portion is always measured from the end portion of the cell regardless of whether or not the sealing material 13 is filled up to the end portion of the cell in the longitudinal direction.

  The length of the sealing portion is calculated using a measurement microscope. Moreover, the average length of a sealing part is obtained by calculating the length of 20 arbitrary sealing parts by the said method, and calculating | requiring these average values.

  In all of the plurality of inner peripheral first cells 17a, the length of the sealing portion is 0.75 to 1.25 times the average length of the sealing portions in the plurality of inner peripheral first cells 17a.

  In the honeycomb structure 1 according to the present embodiment, at least some of the outermost peripheral second cells out of the plurality of outermost peripheral second cells 16b have a sealing portion length of the sealing portion in the inner peripheral second cell 17b. The plurality of outermost peripheral second cells 16b are shorter in length than the average length of the sealing portions in the plurality of inner peripheral second cells 17b. Short is preferred. The length of the sealing portion of the short-sealed second cell is preferably the same as the length of the sealing portion of the short-sealed first cell 161a described above.

  The short-sealed first cell 161a has a length of the sealing portion shorter than the length of the sealing portion in the plurality of inner peripheral second cells 17b.

  Although the material of the sealing material 13 is not specifically limited, It is preferable that it is the same material as the cell wall 12 mentioned above.

  In the honeycomb structure 1 according to the present embodiment, the flow path of the exhaust gas is such that the first cell 11a becomes an inlet side cell into which the exhaust gas flows and the second cell 11b becomes an outlet side cell from which the exhaust gas flows out. Placed in. As a result, as shown in FIG. 3, the exhaust gas G (in FIG. 3, the exhaust gas is G and the direction in which the exhaust gas flows is indicated by an arrow) is changed from the first cell 11a having the other end opened to the first cell 11a. Flows through the cell wall 12 located between the first cell 11b and the second cell 11b, and flows into the second cell 11b having one end opened. That is, when the exhaust gas G passes through the cell wall 12, PM in the exhaust gas G is collected on the cell wall 12, whereby the exhaust gas G can be purified.

  Therefore, at least some of the outermost peripheral first cells 16a among the plurality of outermost peripheral first cells 16a are short-sealed first cells 161a, and the plurality of outermost peripheral first cells 16a is the average length of the sealing portion. However, when the exhaust gas flows into the first cell 11a due to being shorter than the average length of the sealing portions in the plurality of inner peripheral first cells 17a, the exhaust gas in the cell wall 12 that partitions the short sealed first cell 161a. The surface area of the cell wall 12 through which can pass can be increased. As a result, an increase in pressure loss can be suppressed in the short-sealed first cell 161a. Moreover, the honeycomb structure 1 can reduce the variation in the PM filtration area in the cell wall 12 as a whole. Thereby, generation | occurrence | production of the turbulent flow of exhaust gas can be suppressed inside a honeycomb structure, and the raise of a pressure loss can be suppressed as the honeycomb structure 1 whole.

  Further, the average thickness of the outer peripheral wall 14 is thicker than the average thickness of the cell wall 12, and at least some of the outermost peripheral first cells 16a are the length of the sealing portion. However, the short-sealed first cell 161a is shorter than the length of the sealing portion in the plurality of inner peripheral first cells 17a. Thereby, even when the average thickness of the outer peripheral wall 14 is thicker than the average thickness of the cell wall 12, the cell wall 12 and the outer peripheral wall 14 that define the short-sealed first cell 161a and the cell wall 12 through which exhaust gas passes and The surface area of the outer peripheral wall 14 can be increased. That is, an increase in pressure loss can be suppressed in the short-sealed first cell 161a. Further, by suppressing the increase in pressure loss in the short-sealed first cell 161a, the difference between the pressure loss in the short-sealed first cell 161a and the pressure loss in the inner peripheral cell is reduced, and the exhaust gas is exhausted inside the honeycomb structure. Turbulence is less likely to occur. As a result, an increase in pressure loss can be suppressed as the honeycomb structure 1 as a whole.

  Further, since all the outermost peripheral first cells 16a are the short-sealed first cells 161a, the cell wall 12 and the outer peripheral wall 14 that define all the outermost peripheral first cells 16a pass through the exhaust gas. And the surface area of the outer peripheral wall 14 can be enlarged. As a result, an increase in pressure loss can be suppressed in the outermost peripheral first cell 16a. Moreover, the honeycomb structure 1 can reduce the variation in the PM filtration area in the cell wall 12 as a whole. Thereby, generation | occurrence | production of the turbulent flow of exhaust gas can be suppressed inside a honeycomb structure, and the raise of a pressure loss can be suppressed more as the honeycomb structure 1 whole.

  In addition, the short-sealed first cells 161 a are arranged at equal intervals on the entire outermost periphery composed of the outermost peripheral cells adjacent to the outer peripheral wall 14. Therefore, variation in the filtration area of PM can be reduced in the cell wall 12 that partitions the outermost peripheral cell.

  Furthermore, when the difference in the length of the sealing portion is less than 0.5 mm, there is no significant difference compared to the conventional configuration. Therefore, the PM filtration area on the cell wall 12 that partitions the short-sealed first cell 161a cannot be sufficiently increased, and an increase in pressure loss of the honeycomb structure 1 may not be suppressed. When the difference in the length of the sealing portion exceeds 5.0 mm, the length of the sealing portion of the short-sealed first cell 161a is equal to the average length of the sealing portion of the inner peripheral first cell 17a. Compared to extremely short. Therefore, the sealing material 13 may come off the end of the short-sealed first cell 161a due to the pressure of the exhaust gas that has entered the honeycomb structure 1.

  In all of the plurality of inner peripheral first cells 17a, the length of the sealing portion is 0.75 to 1.25 times the average length of the sealing portions in the plurality of inner peripheral first cells 17a. When the exhaust gas flows into the first cell 11a, the surface area of the cell wall 12 through which the exhaust gas passes can be made uniform in the cell wall 12 that partitions the inner peripheral first cell 17a. As a result, variation in the PM filtration area on the cell wall 12 can be reduced. Thereby, generation | occurrence | production of the turbulent flow of exhaust gas can be suppressed inside a honeycomb structure, and the raise of a pressure loss can be suppressed as the honeycomb structure 1 whole.

  Also, at least some of the outermost peripheral second cells 16b among the plurality of outermost peripheral second cells 16b are short-sealed second cells, and the plurality of outermost peripheral second cells 16b have an average length of the sealing portion. The first cell 11a adjacent to the short-sealed second cell across the cell wall 12 by dividing the first cell 11a by being shorter than the average length of the sealing portion in the plurality of inner peripheral second cells 17b In the cell wall 12 and the outer peripheral wall 14 to be performed, the surface areas of the cell wall 12 and the outer peripheral wall 14 through which the exhaust gas passes can be increased. As a result, an increase in pressure loss can be suppressed in the first cell 11a adjacent to the short-sealed second cell with the cell wall 12 interposed therebetween. In addition, the honeycomb structure 1 as a whole can further reduce variations in the PM filtration area on the cell walls 12. Thereby, generation | occurrence | production of the turbulent flow of exhaust gas can be suppressed inside a honeycomb structure, and the raise of a pressure loss can be suppressed more as the honeycomb structure 1 whole.

  The short-sealed first cell 161a has a length of the sealing portion shorter than the length of the sealing portion in the plurality of inner peripheral second cells 17b. Therefore, when the exhaust gas flows into the first cell 11a, the surface area of the cell wall 12 and the outer peripheral wall 14 through which the exhaust gas passes is sufficiently increased in the cell wall 12 and the outer peripheral wall 14 that define the short-sealed first cell 161a. be able to. As a result, an increase in pressure loss can be suppressed in the short-sealed first cell 161a. Moreover, the honeycomb structure 1 can reduce the variation in the PM filtration area in the cell wall 12 as a whole. Thereby, generation | occurrence | production of the turbulent flow of exhaust gas can be suppressed inside a honeycomb structure, and the raise of a pressure loss can be suppressed more as the honeycomb structure 1 whole.

  Further, since the first cell 11a is an inlet side cell, the cell wall 12 and the outer peripheral wall 14 that define the short-sealed first cell 161a have a surface area on the inflow side of the cell wall 12 and the outer peripheral wall 14 through which the exhaust gas passes. Can be increased. As a result, an increase in pressure loss can be suppressed in the short-sealed first cell 161a. Moreover, the honeycomb structure 1 can reduce the variation in the PM filtration area in the cell wall 12 as a whole. Thereby, generation | occurrence | production of the turbulent flow of exhaust gas can be suppressed inside a honeycomb structure, and the raise of a pressure loss can be suppressed more as the honeycomb structure 1 whole.

(Outer peripheral coat layer)
In the honeycomb structure 1 according to the present embodiment, the outer peripheral coat layer 15 is formed on the outer periphery of the ceramic block 10. The outer peripheral coat layer 15 serves to protect the cells 11 provided in the ceramic block 10. Therefore, when the outer peripheral coat layer 15 is formed on the outer periphery of the ceramic block 10, the honeycomb structure 1 having excellent mechanical properties such as compressive strength can be obtained. The outer peripheral coat layer 15 also serves to prevent leakage of exhaust gas from the honeycomb structure 1 when the honeycomb structure 1 is used as a filter for purifying exhaust gas, for example. The outer peripheral coat layer 15 may not be formed.

  When the outer peripheral coat layer 15 is formed on the outer periphery of the ceramic block 10, the thickness of the outer peripheral coat layer 15 is preferably 0.1 to 3.0 mm.

  The material of the outer peripheral coat layer 15 is not particularly limited, and examples thereof include a material composed of an inorganic binder, an organic binder, inorganic fibers and / or inorganic particles.

  The inorganic binder is not particularly limited, and examples thereof include silica sol and alumina sol. Among these, the inorganic binder is preferably silica sol. Moreover, these may be used independently as said inorganic binder, and may use 2 or more types together.

  The organic binder is not particularly limited, and examples thereof include polyvinyl alcohol, methyl cellulose, ethyl cellulose, carboxymethyl cellulose and the like. Among these, the organic binder is preferably carboxymethyl cellulose. Moreover, these may be used independently as said organic binder, and may use 2 or more types together.

  The inorganic fiber is not particularly limited, and examples thereof include ceramic fibers such as silica-alumina, mullite, alumina, and silica. Among these, the inorganic fiber is preferably a silica-alumina fiber. Moreover, these may be used independently as said inorganic fiber, and may use 2 or more types together.

  The inorganic particles are not particularly limited, and examples thereof include carbides and nitrides. More specifically, an inorganic powder or whisker made of silicon carbide, silicon nitride, boron nitride or the like can be used. Among these, the inorganic particles are preferably silicon carbide having excellent thermal conductivity. These may be used alone as the inorganic particles, or two or more of them may be used in combination.

2. Next, an example of a method for manufacturing the honeycomb structure 1 according to the embodiment of the present invention will be described. Hereinafter, a manufacturing method in the case where silicon carbide is used as the ceramic powder that is the main component of the wet mixture that is the raw material of the honeycomb structure 1 will be described.

  The honeycomb structure 1 can be manufactured by performing a forming process, a drying process, a sealing process, a degreasing and firing process, and a peripheral coat layer forming process as necessary.

(Molding process)
First, a wet mixture as a raw material is prepared by mixing silicon carbide powder having different average particle diameters, an inorganic binder and / or organic binder, a liquid plasticizer, a lubricant, and water.

  Although it does not specifically limit as said silicon carbide powder from which said average particle diameter differs, For example, it is about 0.1-1.0 micrometer with respect to 100 weight part of silicon carbide powder which has an average particle diameter of about 3.0-50 micrometers. What contains 5-65 weight part of silicon carbide powder which has an average particle diameter is preferable. This is because the honeycomb structure can be easily made into a porous structure by mixing the silicon carbide powders having different average particle diameters with the above composition.

  The organic binder is not particularly limited, and examples thereof include polyvinyl alcohol, methyl cellulose, ethyl cellulose, carboxymethyl cellulose and the like. Among these, the organic binder is preferably methyl cellulose or carboxymethyl cellulose. Moreover, these may be used independently as said organic binder, and may use 2 or more types together.

  The inorganic binder is not particularly limited, and examples thereof include silica sol and alumina sol. Among these, the inorganic binder is preferably silica sol. Moreover, these may be used independently as said inorganic binder, and may use 2 or more types together.

  It does not specifically limit as said plasticizer, For example, glycerol etc. are mentioned.

  The lubricant is not particularly limited, and examples thereof include polyoxyalkylene compounds such as polyoxyethylene alkyl ether and polyoxypropylene alkyl ether. More specifically, examples of the lubricant include polyoxyethylene monobutyl ether, polyoxypropylene monobutyl ether, and polyoxypropylene stearyl ether. Moreover, these may be used independently as the said lubricant, and may use 2 or more types together.

  Subsequently, the wet mixture is put into an extruder and extruded into a predetermined shape to produce a honeycomb formed body having a predetermined shape. At this time, by changing the shape of the mold, it is possible to produce honeycomb formed bodies having various cross-sectional shapes in a cross section perpendicular to the longitudinal direction.

(Drying process)
Next, the honeycomb formed body is dried using a microwave dryer, a hot air dryer, a dielectric dryer, a vacuum dryer, a vacuum dryer, a freeze dryer, or the like.

(Sealing process)
Then, the sealing process which seals the said cell by filling the sealing material paste used as a sealing material in a predetermined | prescribed cell is performed. In the sealing step, for example, after masking the cells that are not to be sealed and the cells that are to be short-sealed cells, the sealing material paste is collectively applied to cells that are to be sealed among the cells to be sealed. Fill (hereinafter referred to as first filling). Then, after masking the cells other than the cells to be short-sealed cells, the cells to be short-sealed cells are collectively filled with a sealing material paste (hereinafter referred to as second filling) (hereinafter referred to as sealing method X). Called). In addition, it does not specifically limit as a material of sealing material paste, For example, the said wet mixture can be used.

  Thereby, the length of the sealing part of the outermost periphery 1st cell 16a can be made shorter than the length of the sealing part in the inner periphery 1st cell 17a. In addition, the length of the sealing portion of the outermost peripheral second cell 16b can be made shorter than the length of the sealing portion of the inner peripheral second cell 17b.

  Note that the method for manufacturing such a honeycomb structure is not limited to the above-described method. For example, when performing the second filling, a mask may be applied only to the cells that are not sealed, and all the cells to be sealed may be collectively filled with the sealing material paste. At this time, among the cells to be sealed, the cells other than the cells to be short-sealed cells are filled with the sealing material paste in two steps of the first filling and the second filling.

  Further, for example, the sealing material paste may be dried between the first filling and the second filling. In that case, in the second filling, if only the cells that are not sealed are masked, only the cells that become short-sealed cells can be filled with the sealing material paste.

(Degreasing and firing process)
Next, the honeycomb formed body is heated to 300 to 650 ° C. in a degreasing furnace to perform a degreasing step for removing organic substances in the honeycomb formed body. Then, a honeycomb fired body (ceramic block) is produced by carrying the firing process of conveying the degreased honeycomb formed body to a firing furnace and heating to 2,000 to 2200 ° C. In the case where the outer peripheral coat layer is not formed in a later step, the ceramic block is also referred to as a honeycomb structure. Moreover, the sealing material paste with which the edge part of the cell was filled is baked by heating after a baking process, and becomes a sealing material.

  In addition, the conditions which are not described in the said drying process, the said sealing process, the said degreasing | defatting, and a baking process can apply the conditions similar to the past.

(Outer peripheral coat layer forming step)
Subsequently, an outer periphery coating layer is formed by applying an outer periphery coating material paste to the outer peripheral surface of the ceramic block and drying and solidifying the paste. The outer peripheral coat layer is not necessarily provided on the outer periphery of the ceramic block, and may be provided as necessary.

  As described above, for example, a material composed of an inorganic binder, an organic binder, and inorganic fibers and / or inorganic particles can be used as the material of the outer periphery coating material paste.

  Through the above steps, the honeycomb structure 1 according to the embodiment of the present invention can be manufactured. The honeycomb structure 1 according to the embodiment of the present invention can be suitably used as a filter for collecting PM contained in exhaust gas discharged from an internal combustion engine such as a diesel engine.

3. Operational Effects Hereinafter, the operational effects of the honeycomb structure according to the embodiment of the present invention will be listed.

  (1) In the honeycomb structure 1 according to the embodiment of the present invention, at least some of the outermost peripheral first cells 16a among the plurality of outermost peripheral first cells 16a have a sealing portion having a plurality of inner peripheral lengths. The short-sealed first cell 161a is shorter than the length of the sealing portion in the first cell 17a, and the plurality of outermost peripheral first cells 16a have an average length of the sealing portion of the plurality of inner peripheral first cells 17a. Shorter than the average length of the sealing portion. With this configuration, when the exhaust gas flows into the first cell 11a, the surface area of the cell wall 12 through which the exhaust gas passes can be increased in the cell wall 12 that partitions the short-sealed first cell 161a. As a result, an increase in pressure loss can be suppressed in the short-sealed first cell 161a. Moreover, the honeycomb structure 1 can reduce the variation in the PM filtration area in the cell wall 12 as a whole. Thereby, generation | occurrence | production of the turbulent flow of exhaust gas can be suppressed inside a honeycomb structure, and the raise of a pressure loss can be suppressed as the honeycomb structure 1 whole.

  In the honeycomb structure 1, the average thickness of the outer peripheral wall 14 is larger than the average thickness of the cell wall 12, and at least some of the outermost peripheral first cells 16a among the plurality of outermost peripheral first cells 16a are: The length of the sealing part is the short sealed first cell 161a shorter than the length of the sealing part in the plurality of inner peripheral first cells 17a. Thereby, even when the average thickness of the outer peripheral wall 14 is thicker than the average thickness of the cell wall 12, the cell wall 12 and the outer peripheral wall 14 that define the short-sealed first cell 161a and the cell wall 12 through which exhaust gas passes and The surface area of the outer peripheral wall 14 can be increased. That is, an increase in pressure loss can be suppressed in the short-sealed first cell 161a. Further, by suppressing the increase in pressure loss in the short-sealed first cell 161a, the difference between the pressure loss in the short-sealed first cell 161a and the pressure loss in the inner peripheral cell is reduced, and the exhaust gas is exhausted inside the honeycomb structure. Turbulence is less likely to occur. As a result, an increase in pressure loss can be suppressed as the honeycomb structure 1 as a whole.

  In the honeycomb structure 1, the average thickness of the outer peripheral wall 14 is larger than the average thickness of the cell walls 12. When the average thickness of the outer peripheral wall 14 is large, the honeycomb structure 1 simply has improved mechanical strength as a whole. On the other hand, the heat capacity of the outer peripheral wall 14 is larger than the heat capacity of the cell wall 12. Therefore, the honeycomb structure 1 as a whole has large variations in heat capacity, and cracks are likely to occur. However, in the honeycomb structure 1, the length of the sealing portion in the short sealing first cell 161a is shorter than the length of the sealing portion in the plurality of inner peripheral first cells 17a. Therefore, in the short-sealed first cell 161a, the heat capacity becomes relatively small. As a result, in the portion where the outer peripheral wall 14 and the short-sealed first cell 161a are adjacent, the heat capacity is approximately the same as the heat capacity in the inner peripheral first cell 17a. Therefore, since the honeycomb structure 1 has a uniform heat capacity as a whole, the occurrence of cracks can be suppressed.

  (2) In the honeycomb structure 1 according to the embodiment of the present invention, all of the plurality of outermost peripheral first cells 16a are short-sealed first cells 161a. Therefore, in the cell wall 12 and the outer peripheral wall 14 that partition all the outermost peripheral first cells 16a, the surface areas of the cell wall 12 and the outer peripheral wall 14 through which the exhaust gas passes can be increased. As a result, an increase in pressure loss can be suppressed in the outermost peripheral first cell 16a. In addition, the honeycomb structure 1 as a whole can further reduce variations in the PM filtration area on the cell walls 12. Thereby, generation | occurrence | production of the turbulent flow of exhaust gas can be suppressed inside a honeycomb structure, and the raise of a pressure loss can be suppressed more as the honeycomb structure 1 whole.

  (3) In the honeycomb structure 1 according to the embodiment of the present invention, the difference between the length of the sealing portion of the short sealing first cell 161a and the average length of the sealing portion of the inner peripheral first cell 17a (hereinafter, The difference between the lengths of the sealing portions) is 0.5 to 5.0 mm. There is no big difference compared with the conventional structure as the difference of the length of the said sealing part is less than 0.5 mm. Therefore, the PM filtration area on the cell wall 12 that partitions the short-sealed first cell 161a cannot be sufficiently increased, and an increase in pressure loss of the honeycomb structure 1 may not be suppressed. Further, when the difference in the length of the sealing portion exceeds 5.0 mm, the length of the sealing portion of the short sealing first cell 161a is compared with the length of the sealing portion of the inner peripheral first cell 17a. Become extremely short. Therefore, the sealing material 13 may come off the end of the short-sealed first cell 161a due to the pressure of the exhaust gas that has entered the honeycomb structure 1.

  Moreover, since the heat capacity of the honeycomb structure 1 is uniform as a whole when the difference in the length of the sealing portion is 0.5 to 5.0 mm, the occurrence of cracks can be suppressed. When the difference in the length of the sealing portion is less than 0.5 mm, there is no significant difference compared to the configuration of the conventional honeycomb structure. Therefore, the heat capacity of the outer peripheral wall 14 is larger than the heat capacity of the cell wall 12. Therefore, the honeycomb structure 1 as a whole has a large variation in heat capacity, and cracks are likely to occur. When the difference in the length of the sealing portion exceeds 5.0 mm, the length of the sealing portion of the short-sealed first cell 161a is compared with the length of the sealing portion of the inner peripheral first cell 17a. Become extremely short. Therefore, the short-sealed first cell 161a has a smaller heat capacity. As a result, in the portion where the short-sealed first cell 161a and the outer peripheral wall 14 are adjacent, the heat capacity may be smaller than the heat capacity in the inner peripheral first cell 17a. As a result, the honeycomb structure 1 as a whole may have a non-uniform heat capacity and cracks may occur.

  (4) In the honeycomb structure 1 according to the embodiment of the present invention, all of the plurality of inner peripheral first cells 17a have a sealing portion length that is an average of the sealing portions in the plurality of inner peripheral first cells 17a. 0.75 to 1.25 times the length. With the above configuration, when the exhaust gas flows into the first cell 11a, the surface area of the cell wall 12 through which the exhaust gas passes can be made uniform in the cell wall 12 that partitions the inner peripheral first cell 17a. As a result, variation in the PM filtration area on the cell wall 12 can be reduced. Thereby, generation | occurrence | production of the turbulent flow of exhaust gas can be suppressed inside a honeycomb structure, and the raise of a pressure loss can be suppressed as the honeycomb structure 1 whole.

  (5) In the honeycomb structure 1 according to the embodiment of the present invention, the second cell 11b includes a plurality of outermost peripheral second cells 16b adjacent to the outer peripheral wall 14, and the ceramic block 10 than the outermost peripheral second cell 16b. A plurality of innermost peripheral second cells 17b, and at least some of the outermost peripheral second cells 16b of the plurality of outermost peripheral second cells 16b have a sealing portion length of the inner peripheral It is a short sealed second cell shorter than the length of the sealing portion in the second cell 17b, and the plurality of outermost peripheral second cells 16b has an average length of the sealing portion in the plurality of inner peripheral second cells 17b. It is shorter than the average length of the sealing part. Therefore, the first cell 11a adjacent to the short-sealed second cell across the cell wall 12 includes the cell wall 12 and the outer peripheral wall through which the exhaust gas passes in the cell wall 12 and the outer peripheral wall 14 that partition the first cell 11a. The surface area of 14 can be increased. As a result, an increase in pressure loss can be suppressed in the first cell 11a adjacent to the short-sealed second cell with the cell wall 12 interposed therebetween. In addition, the honeycomb structure 1 as a whole can further reduce variations in the PM filtration area on the cell walls 12. Thereby, generation | occurrence | production of the turbulent flow of exhaust gas can be suppressed inside a honeycomb structure, and the raise of a pressure loss can be suppressed more as the honeycomb structure 1 whole.

  (6) In the honeycomb structure 1 according to the embodiment of the present invention, the short-sealed first cell 161a has a length of the sealing portion shorter than the length of the sealing portion in the plurality of inner peripheral second cells 17b. . With the above configuration, when the exhaust gas flows into the first cell 11a, the cell wall 12 and the outer peripheral wall 14 that define the short-sealed first cell 161a have a sufficient surface area of the cell wall 12 and the outer peripheral wall 14 through which the exhaust gas passes. Can be large. As a result, an increase in pressure loss can be suppressed in the short-sealed first cell 161a. Moreover, the honeycomb structure 1 can reduce the variation in the PM filtration area in the cell wall 12 as a whole. Thereby, generation | occurrence | production of the turbulent flow of exhaust gas can be suppressed inside a honeycomb structure, and the raise of a pressure loss can be suppressed more as the honeycomb structure 1 whole.

  (7) In the honeycomb structure 1 according to the embodiment of the present invention, the first cell 11a is an inlet-side cell into which exhaust gas flows, and the second cell 11b is an outlet-side cell from which exhaust gas flows out. Since the first cell 11a is an inlet side cell, the cell wall 12 and the outer peripheral wall 14 that define the short-sealed first cell 161a increase the surface area on the inflow side of the cell wall 12 and the outer peripheral wall 14 through which the exhaust gas passes. can do. As a result, an increase in pressure loss can be suppressed in the short-sealed first cell 161a. Moreover, the honeycomb structure 1 can reduce the variation in the PM filtration area in the cell wall 12 as a whole. Thereby, generation | occurrence | production of the turbulent flow of exhaust gas can be suppressed inside a honeycomb structure, and the raise of a pressure loss can be suppressed more as the honeycomb structure 1 whole.

  Hereinafter, examples that more specifically disclose the present embodiment will be described. In addition, this invention is not limited only to these Examples.

<Manufacture of honeycomb structure>
Example 1
First, 31.3 parts by weight of talc powder having an average particle diameter of 23 μm, 12.3 parts by weight of fine powder of kaolin having an average particle diameter of 3.5 μm, and 11.4 parts by weight of an average particle diameter of 6.5 μm Alumina, 12.3 parts by weight of aluminum hydroxide having an average particle diameter of 13 μm, and 9.6 parts by weight of quartz powder having an average particle diameter of 23 μm were mixed. 3.8 parts by weight of an organic binder (methylcellulose), 0.8 part by weight of sodium stearate and 18.5 parts by weight of water are added to the resulting mixture, kneaded, and wet mixture ( A raw material paste) was obtained. Thereafter, the obtained wet mixture was extruded to produce a cylindrical honeycomb formed body.

  Next, a dry body of the honeycomb formed body was manufactured by blowing hot air of 95 to 105 ° C. using a microwave dryer.

  Thereafter, the predetermined cells of the dried honeycomb molded body were filled with a sealing material paste to seal the cells. Specifically, first, at one end portion in the longitudinal direction of the dry body, all the outermost peripheral first cells arranged at equal intervals in the circumferential direction of the dry body have the length of the sealing portion of all The sealing material paste was filled so that it might become shorter than the length of the sealing part in an inner peripheral 1st cell. Filling with the sealing material paste was performed using the sealing method X. Next, at the other end in the longitudinal direction of the dry body, after masking the non-sealed cells of the outermost peripheral second cells and the inner peripheral second cells, the sealing material paste is applied to the cells to be sealed. Filled together. In addition, the said wet mixture was used for the sealing material paste.

  Subsequently, after the degreasing treatment of degreasing the dried body of the honeycomb molded body in which the cells are sealed at 450 ° C. for 5 hours, the firing treatment is performed under the conditions of 1425 ° C. and 7 hours under an atmospheric pressure of argon atmosphere. A honeycomb structure of Example 1 was produced.

  The honeycomb structure obtained had a diameter of 103 mm and a length in the longitudinal direction of 103 mm. The shape of the cross section perpendicular to the longitudinal direction of the cell was a square having an average length of one side of 1.13 mm. Furthermore, the thickness of the outer peripheral wall was an average of 0.50 mm, the thickness of the cell wall was an average of 0.31 mm, and the porosity of the cell wall was 45%. In addition, the measurement of the thickness of an outer peripheral wall and a cell wall was performed using the measurement microscope (The Nikon Corporation make, MM-800 / LMFA). Other shapes and sizes of the cells and the cell walls were the same as those of the honeycomb structure shown in FIGS.

(Example 2)
The honeycomb structure of Example 2 has the length of the sealing portion in all the outermost peripheral second cells arranged at equal intervals in the circumferential direction of the dry body at the other end in the longitudinal direction of the dry body. It was obtained by the same method as in Example 1 except that the sealing material paste was filled so as to be shorter than the length of the sealing portion in all the inner peripheral second cells. Note that the sealing material paste was filled using the sealing method X. The obtained honeycomb structure of Example 2 had the same shape and size as the honeycomb structure of Example 1 except that the length of the sealing portion was different at the other end in the longitudinal direction. .

(Comparative Example 1)
In the honeycomb structure of Comparative Example 1, the length of the sealing portion is equalized after masking the cells that are not sealed at one end and the other end in the longitudinal direction of the dried body, respectively. This was obtained in the same manner as in Example 1 except that the cells to be sealed were filled with the sealing material paste at once. The obtained honeycomb structure of Comparative Example 1 had the same shape and size as the honeycomb structure of Example 1 except that the length of the sealing portion was different at one end in the longitudinal direction. .

<Measurement of the length of the sealing part>
The honeycomb structures manufactured in Example 1, Example 2, and Comparative Example 1 were divided into four sections having a sector shape with a central angle of 90 ° in a cross section perpendicular to the longitudinal direction, and (i) to ( A columnar sample piece of iv) was prepared. Then, five sealed outermost cells and inner circumferential cells were selected at one end and the other end in the longitudinal direction of each sample piece, and the lengths of the sealed portions were measured. As the outermost peripheral cell, a cell whose cross-sectional shape perpendicular to the longitudinal direction was close to a square was selected. Moreover, the length of the sealing part was measured using the measurement microscope (the Nikon Corporation make, MM-800 / LMFA). Table 1 shows the measurement results of the length of the sealing portion. The values of (i) to (iv) in Example 1, Example 2 and Comparative Example 1 shown in Table 1 are average values of five measured values in each sample, and the average values in Table 1 are (i ) To (iv) are average values.

<Evaluation of pressure loss>
The pressure loss in the honeycomb structures of Example 1, Example 2, and Comparative Example 1 was evaluated by simulation analysis. The simulation software used was AcuSolve (general-purpose thermal fluid analysis software, manufactured by Altea Engineering Co., Ltd.). First, simulation models having the same shape and size as the honeycomb structures of Example 1, Example 2, and Comparative Example 1 were produced. In the simulation models of Example 1, Example 2, and Comparative Example 1, the lengths of the sealing portions were the average values shown in Table 1, respectively. FIG. 4 is a diagram schematically showing a configuration of a simulation model for calculating pressure loss in a part of a cross section perpendicular to the longitudinal direction of the honeycomb structures of Example 1, Example 2, and Comparative Example 1. is there. FIG. 5 schematically shows the configuration of a simulation model for calculating the pressure loss in a part of the cross section parallel to the longitudinal direction of the honeycomb structures of Example 1, Example 2, and Comparative Example 1. FIG. The cell wall at the portion indicated by the shaded Q in FIGS. 4 and 5 is formed of a dense body (that is, the porosity is 0%) and has a structure in which the exhaust gas cannot pass.

  Next, in the simulation models of Example 1, Example 2, and Comparative Example 1, by supplying air at 25 ° C. at a rate of 300 L / h to the cell wall inside the portion indicated by the shaded Q, The pressure loss, which is the difference in pressure between the end of the honeycomb structure on the exhaust gas inlet side and the end of the exhaust gas outlet side, was calculated. The result of pressure loss is shown in FIG. In FIG. 6, the solid line represents the simulation model of Example 1, the broken line represents the simulation model of Example 2, and the dotted line represents the pressure loss in the simulation model of Comparative Example 1.

  In the honeycomb structure of Example 1, all the outermost peripheral first cells arranged at equal intervals in the circumferential direction have a shorter length of the sealing portion than the length of the sealing portion in the inner peripheral first cell. It is a sealing first cell. Therefore, the filtration area of PM in the cell wall which divides the outermost peripheral first cell can be increased. As a result, the simulation model of Example 1 can suppress an increase in pressure loss as shown in FIG.

  In the honeycomb structure of Example 2, the outermost peripheral first cells are short-sealed first cells, and all the outermost peripheral second cells arranged at equal intervals in the circumferential direction are The length is shorter than the length of the sealing part in the inner peripheral second cell. Therefore, it is possible to further increase the PM filtration area on the cell wall that partitions the outermost peripheral first cell and the outermost peripheral second cell. As a result, the simulation model of Example 2 can further suppress an increase in pressure loss as shown in FIG.

  On the other hand, in the honeycomb structure of Comparative Example 1, all the sealed cells have the same length of the sealing portion. Therefore, it is not possible to sufficiently increase the PM filtration area on the cell wall that partitions the outermost peripheral cell. As a result, in the simulation model of Comparative Example 1, the pressure loss increases as shown in FIG.

  Note that the honeycomb structures of Example 1, Example 2, and Comparative Example 1 had no defects or the like even when a mat made of inorganic fibers was wound around the honeycomb structure and pressed into a metal casing. Therefore, it has sufficient mechanical strength.

  In the honeycomb structure of Example 1, the average length of the sealing portion of the outermost peripheral first cell is shorter than the average length of the sealing portion of the inner peripheral first cell. Further, in the honeycomb structure of Example 2, the average length of the sealing portion of the outermost peripheral first cell and the outermost peripheral second cell is the average length of the sealing portion of the inner peripheral first cell and the inner peripheral second cell. Each is shorter. However, the honeycomb structure sealing material of Example 1 and Example 2 was not damaged even when a mat made of inorganic fibers was wound around the honeycomb structure and pressed into a metal casing. . Therefore, it has sufficient mechanical strength. Further, the sealing materials for the honeycomb structures of Example 1 and Example 2 were not confirmed to drop even when air at 25 ° C. was supplied to the honeycomb structure after the press-fitting at a rate of 300 L / h. .

(Other embodiments)
The honeycomb structure 1 according to the above embodiment is an integral honeycomb structure formed as a whole. However, the honeycomb structure 1 is not limited to an integral honeycomb structure, and may be a collective honeycomb structure in which a plurality of ceramic members are bound through an adhesive layer.

  Hereinafter, an aggregated honeycomb structure which is an example of a honeycomb structure according to another embodiment will be described.

  FIG. 7 is a perspective view schematically showing a collective honeycomb structure 2 which is an example of a honeycomb structure according to another embodiment, and FIG. 8 is a diagram showing 1 constituting the honeycomb structure 2 shown in FIG. It is a perspective view which shows an example of two ceramic members typically.

  As shown in FIG. 7, the aggregated honeycomb structure 2 includes a ceramic block 20 in which a plurality of ceramic members 26 are bound via an adhesive layer 27, and an outer peripheral coat layer 25 formed on the outer periphery of the ceramic block 20. Have

  As shown in FIG. 8, the ceramic member 26 is a quadrangular columnar member in which a plurality of cells 21 are arranged side by side so as to extend in the longitudinal direction with the cell wall 22 therebetween. In the plurality of cells 21, either one of the ends in the longitudinal direction is sealed with a sealing material 23. The plurality of cells 21 includes a first cell 21a sealed at one end and a second cell 21b sealed at the other end. The first cell 21a and the second cell 21b are alternately arranged in two directions orthogonal to each other when viewed from the longitudinal direction (that is, the X direction and the Y direction shown in FIG. 8). The first cell 21a and the second cell 21b have a quadrangular cross-sectional shape perpendicular to the longitudinal direction.

  For the adhesive layer 27 and the outer peripheral coat layer 25, the same material as that of the outer peripheral coat layer 15 of the honeycomb structure 1 according to the above embodiment can be used.

  For example, the aggregated honeycomb structure 2 may be formed by, for example, forming a quadrangular prism-shaped honeycomb formed body in a forming process, and then drying, sealing, degreasing and firing processes, bundling processes, cutting processes, and outer coating layers as necessary. It can manufacture by performing a formation process. Until the firing step, the same conditions as in the method for manufacturing the honeycomb structure 1 according to the above embodiment can be applied.

(Bundling process)
After the firing step, a plurality of honeycomb fired bodies are sequentially stacked and bonded via an adhesive paste on a support table to produce a honeycomb aggregate. As a material for the adhesive paste, for example, a material composed of an inorganic binder, an organic binder, and inorganic fibers and / or inorganic particles can be used. Then, the honeycomb aggregate is heated to heat and solidify the adhesive paste to form an adhesive layer. Thereby, a square columnar ceramic block is obtained.

(Cutting process)
Next, a cylindrical ceramic block is obtained by cutting the outer periphery of the quadrangular columnar ceramic block into a cylindrical shape using a diamond cutter or the like.

  About the other process, the conditions similar to the manufacturing method of the honeycomb structure 1 which concerns on the said embodiment are applicable.

  The honeycomb structure 1 according to the embodiment is formed in a columnar shape. However, the shape of the honeycomb structure may be, for example, a prismatic shape, an elliptical columnar shape, or the like whose bottom surface is a polygon such as a triangle, a quadrangle, a hexagon, or an octagon.

  In the honeycomb structure 1 according to the embodiment, the shape of the cross section perpendicular to the longitudinal direction of the cell is a quadrangle. However, the cell shape may be, for example, a polygon such as a triangle, a quadrangle, a hexagon, or an octagon, a shape in which corners of these polygons are configured by curves, a circle, an ellipse, or the like.

  In the honeycomb structure 1 according to the embodiment, the first cells 11a and the second cells 11b are alternately arranged in parallel along two orthogonal directions in a cross section perpendicular to the longitudinal direction. However, the honeycomb structure 1 is not limited to the above configuration, and the first cells 11a and the second cells 11b are alternately arranged in parallel in at least one direction in the cross section perpendicular to the longitudinal direction. That's fine. For example, when the shape of the cross section perpendicular to the longitudinal direction of the cell is a hexagon, the first cell 11a and the second cell 11b are along the three directions whose angles are different by 60 ° in the cross section perpendicular to the longitudinal direction. Are alternately arranged.

The honeycomb structure 1 according to the above-described embodiment may carry a catalyst for purifying exhaust gas on the cell wall. The catalyst to be supported is preferably a noble metal such as platinum, palladium or rhodium, and more preferably platinum. Further, as other catalysts, for example, alkali metals such as potassium and sodium, and alkaline earth metals such as barium can be used. These catalysts may be used alone or in combination of two or more. When these catalysts are supported, CO and HC, and toxic gas, such as NO _X can be suitably purified.

DESCRIPTION OF SYMBOLS 1 Honeycomb structure 10 Ceramic block 11 Several cell 11a 1st cell 11b 2nd cell 12 Cell wall 14 Outer peripheral wall 16a Outermost periphery 1st cell 17a Inner periphery 1st cell 161a Short sealing 1st cell

Claims (7)

Honeycomb structure having a columnar ceramic block including an outer peripheral wall, a cell wall formed inside the outer peripheral wall, and a plurality of cells partitioned by the cell wall and arranged in parallel to extend in the longitudinal direction Body,
The plurality of cells include a first cell sealed at one end and a second cell sealed at the other end,
The first cells and the second cells are alternately arranged in at least one direction in a cross section perpendicular to the longitudinal direction,
The first cell has a plurality of outermost peripheral first cells adjacent to the outer peripheral wall, and a plurality of inner peripheral first cells located inside the ceramic block than the outermost peripheral first cell,
Among the plurality of outermost peripheral first cells, at least some of the outermost peripheral first cells have a length in a longitudinal direction of a sealed portion, and a length of a portion sealed in the plurality of innermost peripheral first cells. Short-sealed first cell shorter than the length in the direction,
The plurality of outermost peripheral first cells have an average length in a longitudinal direction of a sealed portion shorter than an average length in a longitudinal direction of a portion sealed in the plurality of inner peripheral first cells,
The honeycomb structure according to claim 1, wherein an average thickness of the outer peripheral wall is larger than an average thickness of the cell wall.   The honeycomb structure according to claim 1, wherein all of the plurality of outermost first cells are the short-sealed first cells. The difference between the length in the longitudinal direction of the sealed portion of the short-sealed first cell and the average length in the longitudinal direction of the sealed portion of the inner peripheral first cell is 0.5 to 5.0 mm. The honeycomb structure according to claim 1 or 2, wherein   In all of the plurality of inner peripheral first cells, the length in the longitudinal direction of the sealed portion is 0 with respect to the average length in the longitudinal direction of the portion sealed in the plurality of inner peripheral first cells. The honeycomb structure according to any one of claims 1 to 3, wherein the honeycomb structure has a magnification of .75 to 1.25. The second cell has a plurality of outermost peripheral second cells adjacent to the outer peripheral wall, and a plurality of inner peripheral second cells located inside the ceramic block than the outermost peripheral second cell,
Among the plurality of outermost peripheral second cells, at least some of the outermost peripheral second cells have a length in a longitudinal direction of a sealed portion, and a length of a portion sealed in the plurality of inner peripheral second cells. A short-sealed second cell shorter than the length in the direction;
The plurality of outermost peripheral second cells have an average length in a longitudinal direction of a sealed portion shorter than an average length in a longitudinal direction of a portion sealed in the plurality of inner peripheral second cells. The honeycomb structure according to any one of 1 to 4.   The short sealed first cell has a length in a longitudinal direction of a sealed portion shorter than a length in a longitudinal direction of a portion sealed in the plurality of inner peripheral second cells. The honeycomb structure according to any one of the above.   The honeycomb structure according to any one of claims 1 to 6, wherein the first cell is an inlet-side cell into which exhaust gas flows, and the second cell is an outlet-side cell from which exhaust gas flows out. .

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