HONEYCOMB STRUCTURE

Provided is a honeycomb structure including a honeycomb substrate having partition walls defining cells extending from an inflow end face to an outflow end face, and plugging portions. The cells include at least one cell group consisting of a both-end plugged cell, an inlet cell adjacent to the both-end plugged cell, and an outlet cell adjacent to the both-end plugged cell. The partition walls defining the both-end plugged cell have a first common partition wall defining both of the inlet cell and the both-end plugged cell, and a second common partition wall defining both of the outlet cell and the both-end plugged cell. A first flow-through hole is formed in an end portion of the first common partition wall on the outflow end face side, and a second flow-through hole is formed in an end portion of the second common partition wall on the inflow end face side.

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Description

The present application is an application based on JP-2014-033448 filed on Feb. 24, 2014 with the Japanese Patent Office, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a honeycomb structure, and more particularly, relates to a honeycomb structure which is excellent in trapping efficiency and inhibits an increase of pressure loss when ash is accumulated.

2. Background Art

Heretofore, for the purpose of removing particulates (hereinafter also referred to as PM (Particulate Matter)) included in exhaust gas discharged from various engines and the like, exhaust gas purifying devices including honeycomb structure filter (honeycomb structure) have been used. There is known a honeycomb structure including a honeycomb structured honeycomb substrate and plugging portions disposed at open ends of inlet cells which are predetermined cells of this honeycomb substrate on the outflow end face side thereof and at open ends of outlet cells which are the residual cells on the inflow end face side (e.g., see Patent Documents 1 and 2). Specifically, the honeycomb substrate has porous partition walls defining a plurality of cells which form through channels for the exhaust gas.

When the exhaust gas including particulates flows into the honeycomb structure from the inflow end portion side which is one end portion, the exhaust gas is filtered by the partition walls to remove the particulates and purified gas is discharged from the outflow end portion side which is the other end portion. In such a manner, exhaust gas is purified by the honeycomb structure.

When the exhaust gas flows into the inlet cells of the honeycomb structure, the exhaust gas passes through the partition walls defining the inlet cells to flow into the outlet cells, since the open ends of the inlet cells on the outflow end face side are plugged. Furthermore, the open ends of the outlet cells on the inflow end face side are plugged, and hence the purified gas is discharged from the open ends on the outflow end face side. The PM accumulated in the honeycomb structure is burnt by raising the temperature of the exhaust gas every appropriate interval or by heating with an electric heater or the like. As described above, the PM is prevented from being excessively accumulated in the honeycomb structure.

Furthermore, some other honeycomb structures having plugging portions disposed only at one end portion or at the other end portion in order to prevent increase of pressure loss (e.g., see Patent Documents 3 and 4).

[Patent Document 1] JP-A-S49-038266

[Patent Document 2] JP-A-S56-148607

[Patent Document 3] JP-A-2003-035126

[Patent Document 4] JP-A-2004-108203

SUMMARY OF THE INVENTION

However, in honeycomb structures described in Patent Documents 1 and 2, one open end or the other open end of each cell is plugged, and hence pressure loss noticeably increases. Furthermore, when ash which is a noncombustible substance included in PM is accumulated, such accumulated ash is hard to be discharged from the honeycomb structure. Therefore, the pressure loss when ash is accumulated also noticeably increases. In a honeycomb structure described in Patent Document 3, there are cells in which no plugging portion is disposed, and hence as compared with the honeycomb structures described in Patent Documents 1 and 2, less ash is accumulated, and the pressure loss increase is low. However trapping efficiency of PM is deteriorated. In a honeycomb structure described in Patent Document 4, similarly to Patent Document 3, there are cells in which no plugging portion is disposed, and hence the pressure loss increase is low, however as compared with the honeycomb structures described in Patent Documents 1 and 2, the trapping efficiency of PM is deteriorated. Further, in the honeycomb structure described in Patent Document 4, the plugging portions are disposed in the cells on the outflow end portion side, and hence ash is easily deposited in the outflow end portion of the honeycomb structure. Ash deposited in this portion is hard to be discharged. In consequence, when the deposited ash is not discharged, the pressure loss disadvantageously increases. On the other hand, a great deal of labor is required to discharge ash.

In consequence, there has earnestly been desired development of a honeycomb structure which has a favorable trapping efficiency and inhibits increase of pressure loss when ash is accumulated.

The present invention has been developed in view of such problems of conventional technologies, and an object thereof is to provide a honeycomb structure which has a favorable trapping efficiency and inhibits increase of pressure loss when ash is accumulated.

According to the present invention, a honeycomb structure described in the following is provided.

[1] A honeycomb structure including a honeycomb substrate having partition walls defining a plurality of cells which form through channels for a fluid and extend from an inflow end face as one end face where the fluid flows in to an outflow end face as the other end face where the fluid flows out, and plugging portions disposed at open ends of the cells of the honeycomb substrate, wherein the plurality of cells include at least one cell group consisting of three cells which are a both-end plugged cell in which the plugging portions are disposed at both open ends on the inflow end face side and the outflow end face side, an inlet cell which is adjacent to the both-end plugged cell and in which the plugging portion is only disposed at the open end on the outflow end face side, and an outlet cell which is adjacent to the both-end plugged cell and in which the plugging portion is only disposed at the open end on the inflow end face side, the partition walls defining the both-end plugged cell constituting the cell group have a first common partition wall which is a common partition wall defining both of the inlet cell and the both-end plugged cell, and a second common partition wall which is a common partition wall defining both of the outlet cell and the both-end plugged cell, a first flow-through hole is formed in an end portion of the first common partition wall on the outflow end face side, and a second flow-through hole is formed in an end portion of the second common partition wall on the inflow end face side.

[2] The honeycomb structure according to the above [1], wherein in a cross section of the honeycomb substrate which is perpendicular to an extending direction of the cells, the inlet cell, the both-end plugged cell and the outlet cell constituting each of the at least one cell group are arranged so that a first center which is the center of the inlet cell, a second center which is the center of the both-end plugged cell and a third center which is the center of the outlet cell are positioned on a same straight line.

[3] The honeycomb structure according to the above [1], wherein in the cross section of the honeycomb substrate which is perpendicular to the extending direction of the cells, the inlet cell, the both-end plugged cell and the outlet cell constituting each of the at least one cell group are arranged to form an L-shape.

[4] The honeycomb structure according to any one of the above [1] to [3], wherein an open area of the first flow-through hole is from 0.3 to 3.5 times as large as an average value of sectional areas in the direction perpendicular to the cell extending direction of the inlet cell, the both-end plugged cell and the outlet cell constituting the cell group.

[5] The honeycomb structure according to any one of the above [1] to [4], wherein an open area of the second flow-through hole is from 0.3 to 3.5 times as large as the average value of the sectional areas in the direction perpendicular to the cell extending direction of the inlet cell, the both-end plugged cell and the outlet cell constituting the cell group.

[6] The honeycomb structure according to any one of the above [1] to [5], which is made of a porous ceramic material.

[7] The honeycomb structure according to any one of the above [1] to [6], wherein the honeycomb substrate is integrally formed.

[8] The honeycomb structure according to any one of the above [1] to [6], wherein the honeycomb substrate has a segment structure constituted of a plurality of honeycomb segments.

A honeycomb structure of the present invention has a trapping efficiency of the same degree as a trapping efficiency of a conventional honeycomb structure. That is, the honeycomb structure of the present invention is excellent in trapping efficiency. Furthermore, the honeycomb structure of the present invention has cell groups including three specific cells, and first flow-through holes and second flow-through holes are formed in predetermined partition walls, respectively. That is, in the honeycomb structure of the present invention, spaces where ash is deposited are present at two positions; at an end portion on the outflow end face side and at an end portion on the inflow end face side (see symbols X and Y of FIG. 2). Furthermore, in the honeycomb structure of the present invention, the ash which is accumulated in the honeycomb structure suitably joins a flow of an exhaust gas to be discharged outside along a route of an inlet cell, a both-end plugged cell and an outlet cell. Therefore, the honeycomb structure of the present invention inhibits an increase of a pressure loss when the ash is accumulated. As a result, maintenance operations when the ash is accumulated are performed less times, i.e., the maintenance operation may scarcely be needed to be performed. That is, the honeycomb structure is so-called free of maintenance in regard to deposition of ash.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view schematically showing one embodiment of a honeycomb structure of the present invention;

FIG. 2 is a sectional view schematically showing a cross section parallel to an extending direction of cells in the one embodiment of the honeycomb structure of the present invention;

FIG. 3 is an enlarged view schematically showing an enlarged part of a cross section perpendicular to the cross section shown in FIG. 2;

FIG. 4A is a plan view schematically showing an example of arrangement patterns of cell group in the honeycomb structure of the present invention;

FIG. 4B is a plan view schematically showing another example of the arrangement patterns of a cell group in the honeycomb structure of the present invention;

FIG. 4C is a plan view schematically showing still another example of the arrangement patterns of a cell group in the honeycomb structure of the present invention;

FIG. 4D is a plan view schematically showing a further example of the arrangement patterns of a cell group in the honeycomb structure of the present invention;

FIG. 4E is a plan view schematically showing a further example of the arrangement patterns of a cell group in the honeycomb structure of the present invention;

FIG. 4F is a plan view schematically showing a further example of the arrangement patterns of a cell group in the honeycomb structure of the present invention;

FIG. 4G is a plan view schematically showing a further example of the arrangement patterns of a cell group in the honeycomb structure of the present invention;

FIG. 4H is a plan view schematically showing a still further example of the arrangement patterns of a cell group in the honeycomb structure of the present invention;

FIG. 5A is a plan view schematically showing an example of arrangement patterns of cell groups in the honeycomb structure of the present invention;

FIG. 5B is a plan view schematically showing another example of the arrangement patterns of cell groups in the honeycomb structure of the present invention;

FIG. 6A is a plan view schematically showing an example of arrangement patterns of cell groups in the honeycomb structure of the present invention;

FIG. 6B is a plan view schematically showing another example of the arrangement patterns of cell groups in the honeycomb structure of the present invention;

FIG. 7A is a plan view schematically showing an example of arrangement patterns of cell groups in the honeycomb structure of the present invention;

FIG. 7B is a plan view schematically showing another example of the arrangement patterns of cell groups in the honeycomb structure of the present invention;

FIG. 8 is a plan view schematically showing an example of arrangement patterns of cell groups in the honeycomb structure of the present invention;

FIG. 9 is a plan view schematically showing an example of arrangement patterns of cell groups in the honeycomb structure of the present invention;

FIG. 10 is a plan view schematically showing an example of arrangement patterns of cell groups in the honeycomb structure of the present invention;

FIG. 11A is a plan view schematically showing an example of arrangement patterns of cell groups in the honeycomb structure of the present invention;

FIG. 11B is a plan view schematically showing another example of the arrangement patterns of cell groups in the honeycomb structure of the present invention;

FIG. 11C is a plan view schematically showing still another example of the arrangement patterns of cell groups in the honeycomb structure of the present invention;

FIG. 11D is a plan view schematically showing a further example of the arrangement patterns of cell groups in the honeycomb structure of the present invention;

FIG. 12A is an explanatory view schematically showing a manufacturing step of one embodiment of the honeycomb structure of the present invention;

FIG. 12B is an explanatory view schematically showing a manufacturing step of the one embodiment of the honeycomb structure of the present invention; and

FIG. 12C is an explanatory view schematically showing a manufacturing step of the one embodiment of the honeycomb structure of the present invention.

 DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present invention will be described. It should be understood that the present invention is not limited to the following embodiments and that the following embodiments, to which changes, improvements and the like are suitably added on the basis of ordinary knowledge of a person skilled in the art without departing from the scope of the present invention, also fall in the gist of the present invention.

[1] Honeycomb Structure:

One embodiment of a honeycomb structure of the present invention is a honeycomb structure 100 shown in FIG. 1. The honeycomb structure 100 includes a honeycomb substrate 10 having partition walls 1 defining a plurality of cells 2, and plugging portions 25 disposed at open ends of the cells 2 of the honeycomb substrate 10. The partition walls 1 define the plurality of cells 2 which form through channels for a fluid and extend from an inflow end face 11 as one end face where the fluid flows in to an outflow end face 12 as the other end face where the fluid flows out. The plurality of cells 2 include at least one cell group 5 including three cells which are a both-end plugged cell 2b in which the plugging portions 25 are disposed at both open ends on the inflow end face 11 side and the outflow end face 12 side, and an inlet cell 2a and an outlet cell 2c which are adjacent to the both-end plugged cell 2b. The inlet cell 2a is adjacent to the both-end plugged cell 2b, and has the plugging portion 25 disposed only on the outflow end face 12 side of the open ends. The outlet cell 2c is adjacent to the both-end plugged cell 2b, and has the plugging portion 25 disposed only on the inflow end face 11 side of the open ends. That is, one both-end plugged cell 2b is adjacent to an inlet cell 2a and an outlet cell 2c. The partition walls 1 defining the both-end plugged cell 2b constituting the cell group 5 have a first common partition wall 1a and a second common partition wall 1b. The first common partition wall 1a is the common partition wall 1 defining both of the inlet cell 2a and the both-end plugged cell 2b. The second common partition wall 1b is the common partition wall 1 defining both of the outlet cell 2c and the both-end plugged cell 2b. A first flow-through hole 7 is formed in an end portion of the first common partition wall 1a on the outflow end face 12 side, and a second flow-through hole 8 is formed in an end portion of the second common partition wall 1b on the inflow end face 11 side.

In the honeycomb structure 100 shown in FIG. 1 and FIG. 2, through-cells which are non-plugged cells (i.e., cells whose both open ends are opened) are not present, and hence deterioration of a trapping efficiency due to the presence of the through-cells can be prevented. That is, more suitable trapping efficiency can be obtained than a honeycomb structure in which one open end or the other open end of each cell is plugged; such a honeycomb structure as described in Patent Documents 3 and 4.

Furthermore, the honeycomb structure 100 inhibits an increase of a pressure loss when ash is accumulated. As a result, for the honeycomb structure 100, maintenance operations when the ash is accumulated are performed less times, and the maintenance operations may scarcely be needed to be performed. That is, the honeycomb structure 100 is so-called free of maintenance in regard to deposition of ash. Specifically, in the honeycomb structure 100, the ash is easily deposited at two positions; at an end portion on the outflow end face 12 side (shown by symbol “X” in FIG. 2) and at an end portion on the inflow end face 11 side (shown by symbol “Y” in FIG. 2), which are in through channels formed along a route of inlet cell 2a, both-end plugged cell 2b and outlet cell 2c. On the other hand, in a conventional honeycomb structure (such a honeycomb structure as described in Patent Document 1), ash is easily deposited only in an end portion on the outflow end face side. That is, the honeycomb structure 100 has a large space where the ash can be deposited. Consequently, the honeycomb structure 100 has a smaller degree of increase of pressure loss as compared with the conventional honeycomb structure, even when the amount of ash as much as can be deposited under predetermined conditions in the conventional honeycomb structure is accumulated in the present honeycomb structure. Furthermore, the ash accumulated in the honeycomb structure 100 suitably joins a flow of an exhaust gas to be discharged outside. For example, the ash present in the inlet cell 2a flows into the both-end plugged cell 2b from the first flow-through hole 7 formed in the partition wall 1 between the inlet cell 2a and the both-end plugged cell 2b. Next, the ash flows into the outlet cell 2c from the second flow-through hole 8 formed in the partition wall 1 between the both-end plugged cell 2b and the outlet cell 2c. Afterward, the ash is discharged from the honeycomb structure 100. In this way, the ash can be deposited in the large space and the accumulated ash joins the flow of the exhaust gas to be suitably discharged. Hence the through channels of the exhaust gas would not completely be closed, and the degree of increase of pressure loss due to the deposition of ash is reduced (increase of pressure loss is inhibited).

FIG. 1 is a perspective view schematically showing one embodiment of the honeycomb structure of the present invention. FIG. 2 is a sectional view schematically showing a cross section parallel to an extending direction of cells in the one embodiment of the honeycomb structure of the present invention.

The inlet cells, the both-end plugged cells and the outlet cells are preferably arranged as follows. That is, in a cross section of the honeycomb substrate which is perpendicular to the cell extending direction, a center of the inlet cell is “a first center”, a center of the both-end plugged cell is “a second center”, and a center of the outlet cell is “a third center”. Then, the inlet cell, the both-end plugged cell and the outlet cell are preferably arranged so that the first center, the second center and the third center are positioned on a same straight line. In the honeycomb structure 100, the inlet cell 2a, the both-end plugged cell 2b and the outlet cell 2c are arranged so that the center of the inlet cell 2a (first center), the center of the both-end plugged cell 2b (second center) and the center of the outlet cell 2c (third center) are positioned on the same straight line.

Furthermore, in another preferable configuration, the inlet cell, the both-end plugged cell and the outlet cell are arranged to form an L-shape as shown in FIG. 4A to FIG. 4H, when seen from the cell extending direction. That is, in this preferable configuration, the cell group consisting of three cells of one inlet cell, one both-end plugged cell and one outlet cell is formed into the L-shape.

That “the inlet cell, the both-end plugged cell and the outlet cell form the L-shape” indicates that the respective cells are arranged in a state where the first common partition wall and the second common partition wall are not in such a positional relation as to face each other, but are positioned to form two adjacent partition walls among the partition walls constituting the both-end plugged cell.

FIG. 4A is a plan view schematically showing an example of arrangement patterns of a cell group in the honeycomb structure of the present invention. FIG. 4B is a plan view schematically showing another example of the arrangement patterns of a cell group in the honeycomb structure of the present invention. FIG. 4C is a plan view schematically showing still another example of the arrangement patterns of a cell group in the honeycomb structure of the present invention. FIG. 4D is a plan view schematically showing a further example of the arrangement patterns of a cell group in the honeycomb structure of the present invention. FIG. 4E is a plan view schematically showing a further example of the arrangement patterns of a cell group in the honeycomb structure of the present invention. FIG. 4F is a plan view schematically showing a further example of the arrangement patterns of a cell group in the honeycomb structure of the present invention. FIG. 4G is a plan view schematically showing a further example of the arrangement patterns of a cell group in the honeycomb structure of the present invention. FIG. 4H is a plan view schematically showing a still further example of the arrangement patterns of a cell group in the honeycomb structure of the present invention.

The honeycomb structure of the present invention includes at least one cell group. That is, in the honeycomb structure of the present invention, the cell group as one set of three cells consisting of the inlet cell, the both-end plugged cell and the outlet cell may partially be present. Also when the above cell group is partially present, the advantageous effect of the present invention can be expected. When the cell group is partially present, for example, in a configuration, the cell groups are disposed in the central portion of the honeycomb structure (central portion in the cross section perpendicular to the cell extending direction), and the cells described below (through-cells or conventional type cells) are disposed in the outer circumferential portion (portion other than the central portion). That is, the cells disposed in the outer circumferential portion of the honeycomb structure may be cells which have no plugging portions at both ends (through-cells) or cells having plugging portions in a checkered pattern in both the end faces, only in the inflow end face, or only in the outflow end face (conventional type cells). The latter cells (conventional type cells) are the cells in which the plugging portions are disposed as in the conventional type honeycomb structure. Furthermore, the abovementioned arrangements in the central portion and the outer circumferential portion of the honeycomb structure may be reversed. In the honeycomb structure of the present invention, the “ratio of the cell groups” may suitably be determined in consideration of the required trapping efficiency or pressure loss. The ratio is preferably from 10 to 100% and further preferably from 30 to 100%. The “ratio of the cell groups” is the ratio of “number of the cell groups” to “value of ⅓ of the number of all the cells (number of all the cells regardless of the presence/absence of the plugging portions”. It is to be noted that the cells are counted excluding cells deformed by a circumferential wall or cells in which one or more sides (walls) forming each of the cells constitute the circumferential wall (hereinafter, these cells may be referred to as “incomplete cells”).

When a plurality of cell groups are included, there is not any special restriction on an arrangement pattern of these cell groups, but the plurality of cell groups can be arranged as shown in, for example, FIG. 5A to FIG. 11D. It is to be noted that in FIG. 5A to FIG. 11D, “1” indicates the inlet cells. “2” indicates the both-end plugged cells. “3” indicates the outlet cells. Furthermore, FIG. 5A to FIG. 11D schematically show the arrangement patterns of the cell groups, and for the convenience in explaining the arrangement pattern of the cell groups, a part of the honeycomb structure is extracted and shown. Additionally, in FIG. 5A to FIG. 11D, depiction of the plugging portions is omitted.

Each of FIG. 5A to FIG. 11D is a plan view schematically showing the arrangement patterns of cell groups in the honeycomb structure of the present invention.

FIG. 5A and FIG. 5B show examples where the cell groups each including the inlet cell, the both-end plugged cell and the outlet cell arranged on the same straight line are arranged in a same order. FIG. 6A and FIG. 6B show examples where each of the arrangements shown in FIG. 5A and FIG. 5B is shifted as much as one cell (to the left side or the right side in the drawing or to the upside or the downside in the drawing) every row. FIG. 7A, FIG. 7B and FIG. 8 show examples where the number of the cells to be shifted (to the left side or the right side in the drawing) is changed in respective rows on the basis of the arrangement shown in FIG. 5A. FIG. 9 and FIG. 10 show examples where the cell groups shown in FIG. 4A, FIG. 4B and FIG. 4E are alternately arranged.

Furthermore, in the honeycomb structure of the present invention, as shown in FIG. 11A to FIG. 11D, the cell groups each including the inlet cell, the both-end plugged cell and the outlet cell arranged on a same straight line may be arranged while shifting as much as ½ cell to the horizontal direction of the drawing (to the left side or the right side in the drawing) every row.

In FIG. 5A and FIG. 5B among FIG. 5A to FIG. 8 and FIG. 11A to FIG. 11D, the inlet cell, the both-end plugged cell and the outlet cell are arranged on a straight line, respectively, and hence the plugging portions are easily formed which facilitates preparation.

In FIG. 6A, FIG. 6B and FIG. 8, all of four partition walls of each inlet cell are adjacent to the both-end plugged cell or the outlet cell, and hence the exhaust gas also flows through these partition walls. Therefore, in the arrangements (arrangement patterns) shown in FIG. 6A, FIG. 6B and FIG. 8, the pressure loss lowers as much as about 5% as compared with the other arrangement patterns.

In addition, a plurality of types of arrangement patterns shown in FIG. 5A to FIG. 11D may be combined and arranged.

An open area of the first flow-through hole is preferably from 0.3 to 3.5 times and further preferably from 0.5 to three times as large as an average value of sectional areas of the inlet cell, the both-end plugged cell and the outlet cell constituting the cell group. When the above “open area of the first flow-through hole” is smaller than the above lower limit value, there is the fear that the pressure loss increases. When the above “open area of the first flow-through hole” is in excess of the above upper limit value, there is the fear that isostatic strength deteriorates. The “sectional areas of the inlet cell, the both-end plugged cell and the outlet cell” are the areas of the respective cells in the cross section perpendicular to the cell extending direction. In the present description, the “average value of the sectional areas of the inlet cell, the both-end plugged cell and the outlet cell constituting the cell group” is the following value. That is, the above average value is a value obtained by multiplying a value of the sum of “sectional area of the inlet cell”, “sectional area of the both-end plugged cell” and “sectional area of the outlet cell” constituting one cell group by ⅓. It is to be noted that when the open area is calculated, a plurality of cell groups are suitably selected.

The “end portion on the outflow end face side” in which the first flow-through hole is formed is specifically a portion from the outflow end face of the honeycomb structure to a position of ⅓ of the length of the honeycomb structure in the cell extending direction (first flow-through hole forming region). The first flow-through hole is preferably formed in the above first flow-through hole forming region, but in the above first flow-through hole forming region, the hole is more preferably formed in a portion from the outflow end face of the honeycomb structure to a position of ⅕ of the length of the honeycomb structure in the cell extending direction.

An open area of the second flow-through hole is preferably from 0.3 to 3.5 times and further preferably from 0.5 to three times as large as the average value of the sectional areas of the inlet cell, the both-end plugged cell and the outlet cell constituting the cell group. When the above “open area of the second flow-through hole” is smaller than the above lower limit value, there is the fear that the pressure loss increases. When the above “open area of the second flow-through hole” is in excess of the above upper limit value, there is the fear that the isostatic strength deteriorates.

The “end portion on the inflow end face side” in which the second flow-through hole is formed is specifically a portion from the inflow end face of the honeycomb structure to the position of ⅓ of the length of the honeycomb structure in the cell extending direction (second flow-through hole forming region). The second flow-through hole is preferably formed in the above second flow-through hole forming region, but in the above second flow-through hole forming region, the hole is more preferably formed in a portion from the inflow end face of the honeycomb structure to the position of ⅕ of the length of the honeycomb structure in the cell extending direction.

There is not any special restriction on a shape of the opening of each of the first flow-through hole and the second flow-through hole, and the shapes of the openings of the respective flow-through holes may be the same or different. Examples of the shape of the opening of each flow-through hole include a circular shape, a semicircular shape, an elliptic shape, a semi-elliptic shape (shape obtained by cutting an ellipse along a short diameter), a triangular shape and a quadrangular shape. FIG. 3 shows the enlarged first flow-through holes 7. The shape of the opening of the first flow-through holes 7 is semi-elliptic. Such a semi-elliptic opening is easily formed. FIG. 3 is an enlarged view schematically showing an enlarged part of a cross section perpendicular to the cross section (cross section A-A) shown in FIG. 2.

The honeycomb structure of the present invention is preferably made of a porous ceramic material. That is, the honeycomb substrate and the plugging portions constituting the honeycomb structure are preferably made of the porous ceramic material. When the honeycomb structure is made of the porous ceramic material, catalyst is easily loaded onto the honeycomb structure. The honeycomb structure of the present invention may be made of a sintered metal obtained by forming and then sintering metal powder, or a metal foil.

Specifically, when the honeycomb structure is made of a ceramic material, the ceramic material is further preferably at least one selected from the group consisting of cordierite, silicon carbide, a silicon-silicon carbide based composite material, mullite, alumina, aluminum titanate, silicon nitride, and a silicon carbide-cordierite based composite material, from the viewpoint that the materials are excellent in strength and heat resistance. Among these materials, cordierite and silicon carbide are preferable.

The honeycomb substrate of the honeycomb structure of the present invention preferably has a segment structure constituted of a plurality of honeycomb segments. Such segment structure enables manufacturing a honeycomb structure which is hard to be integrally manufactured (e.g., large honeycomb structure).

The honeycomb substrate having the segment structure can specifically be a bonded assembly having a plurality of honeycomb segments and a bonding layer to bond the plurality of honeycomb segments to one another.

In addition, the honeycomb substrate of the honeycomb structure of the present invention is also preferably integrally formed. The honeycomb substrate integrally formed in this manner, simplifies the manufacturing steps. When the honeycomb substrate is “integrally formed”, it is meant that the honeycomb substrate is constituted of one member. That is, the whole honeycomb substrate is formed at a time by a method of extrusion or the like.

The respective members of the honeycomb structure of the present invention will further be described in the following.

[1-1] Honeycomb Substrate:

A thickness of the partition walls of the honeycomb substrate 10 is preferably from 40 to 600 μm, further preferably from 80 to 500 μm and especially preferably from 100 to 400 μm. When the above thickness of the partition walls is smaller than 40 μm, there is the fear that the strength of the partition walls may be insufficient. On the other hand, when the thickness is in excess of 600 μm, there is the fear that the pressure loss increases.

A porosity of the partition walls of the honeycomb substrate 10 is preferably from 25 to 80%, further preferably from 30 to 75% and especially preferably from 30 to 70%. When the above porosity is smaller than 25%, there is the fear that the pressure loss increases. On the other hand, when the porosity is in excess of 80%, there is the fear that the strength of the partition walls may be lower. Here, in the present description, “porosity” is a value measured by a mercury porosimeter.

An average pore diameter of the partition walls of the honeycomb substrate 10 is preferably from 5 to 100 μm, further preferably from 7 to 80 μm and especially preferably from 7 to 60 When the above average pore diameter is smaller than 5 μm, there is the fear that the pressure loss increases. On the other hand, when the average pore diameter is in excess of 100 μm, there is the fear that the exhaust gas purification performance deteriorates. Here, in the present description, “the average pore diameter” is a value measured by the mercury porosimeter.

A cell density of the honeycomb substrate 10 is preferably from 12 to 200 cells/cm2, further preferably from 15 to 150 cells/cm2 and especially preferably from 20 to 120 cells/cm2. When the above cell density is smaller than 12 cells/cm2, there is the fear that the isostatic strength lowers. On the other hand, when the cell density is in excess of 200 cells/cm2, there is the fear that the pressure loss increases.

A shape of each of the cells 2 in the cross section perpendicular to the extending direction of the cells 2 of the honeycomb substrate 10 can be, for example, quadrangular or hexagonal.

A length of the honeycomb substrate 10 (honeycomb structure 100) in the cell extending direction can be from 50 to 1000 mm or more (in excess of 1000 mm) In addition, when each end face of the honeycomb structure 100 is circular, a diameter of the end faces can be from 25 to 600 mm or more (in excess of 600 mm).

A shape of the honeycomb substrate 10 can be each of various shapes such as a columnar shape, an elliptic columnar shape, a quadrangular columnar shape and a hexagonal columnar shape. Among these shapes, the columnar shape and the quadrangular columnar shape are preferable.

[1-2] Plugging Portion:

A depth of each plugging portion (length in the cell extending direction) is preferably from 0.3 to 10 mm, further preferably from 0.5 to 8 min and especially preferably from 1 to 7 mm. When the depth of the plugging portion is smaller than the above lower limit value, there is the fear that the plugging portions drop out due to vibrations or the like. When the depth of the plugging portion is in excess of the above upper limit value and the honeycomb structure is used as a filter, there is the fear that portions of the honeycomb structure functioning as the filter decrease.

A material of the plugging portions can be the same as the material of the partition walls. In particular, the material of the plugging portions is preferably a porous ceramic material.

The honeycomb structure 100 shown in FIG. 1 has a circumferential wall 26, but does not necessarily have the circumferential wall 26. The circumferential wall 26 can be formed by applying an outer circumference coating ceramic material to an outer circumference of the honeycomb structure. Furthermore, the circumferential wall 26 may be formed simultaneously with the partition walls in a process of preparing the honeycomb substrate 10, when the honeycomb substrate is integrally formed by extrusion or the like.

[2] Manufacturing Method of Honeycomb Structure:

The honeycomb structure of the present invention can be manufactured, for example, as follows. The honeycomb structure in which the honeycomb substrate is integrally formed will be described.

First, a kneaded material to prepare the honeycomb substrate is prepared and this kneaded material is formed to prepare a honeycomb formed body (forming step).

Next, the obtained honeycomb formed body (or a honeycomb dried body after drying is performed as required) is fired to prepare a honeycomb fired body (honeycomb fired body preparing step).

Next, the prepared honeycomb fired body 50 is disposed so that the end portion thereof on the outflow end face 112 side is positioned on the upside as shown in FIG. 12A. Afterward, a resin member is pushed into each partition wall 3 in which a first flow-through hole is to be formed. Afterward, the honeycomb fired body 50 is inverted and disposed so that the end portion thereof on the inflow end face 111 side is positioned on the upside. Afterward, as shown in FIG. 12B, a resin member 20 is pushed into each partition wall 3 in which a second flow-through hole is to be formed, so that a portion of the partition wall 3 into which the resin member 20 is pushed is destroyed. It is to be noted that the partition walls 3 are very thin, and hence the resin members 20 can be pushed thereinto by manual force. When the resin members are used in this manner, the flow-through holes (first flow-through holes and second flow-through holes) each having a desirable size can surely be formed. That is, each resin member performs a function of a spacer, and the resin members burn away when fired, so that the flow-through holes (first flow-through holes and second flow-through holes) are formed.

There is not any special restriction on physical properties of the resin member, as long as the resin member performs the function as spacer and burns away when fired. As to a hardness of the resin member, the resin member may be hard to such an extent that a part of partition wall may be destroyed. It is to be noted that when the partition wall is partially destroyed, the resin member is not directly pushed, but the resin member may be pushed by using a needle, laser beams or the like. In this case, the hardness of the resin member can freely be set, and the resin member does not have to be hard to such an extent that the partition wall can be destroyed.

Specifically, as the resin member, a member made of polyethylene, a member made of nylon or the like may be used.

Next, as shown in FIG. 12C, in the honeycomb fired body 50 into which the resin members 20 has been pushed, a plugging material 23 is charged into spaces formed by pushing the resin members 20 thereinto (plugging material charging step).

It is to be noted that in the manufacturing method of the honeycomb structure of the present invention, a method without using the resin members may be employed. That is, a viscosity of the plugging material may be increased, so that each portion that becomes the flow-through hole is not closed with the plugging material, when the plugging material is charged thereinto.

Next, the honeycomb fired body into which the plugging material is charged is fired again to form the plugging portions (plugging portion forming step). The resin members burn away when fired in this manner, and portions where the resin members have been disposed become the first flow-through holes and the second flow-through holes. In such a manner, the honeycomb structure can be prepared.

In addition, the honeycomb structure may be prepared by grinding partition walls of the honeycomb dried body dried after forming or by burning using laser beams to form the flow-through holes each having the desirable size, and then charging the plugging material so that the portions which become the flow-through holes are not closed, followed by the firing.

EXAMPLES

Hereinafter, the present invention will specifically be described on the basis of examples, but the present invention is not limited to these examples.

Example 1

A pore former, an organic binder and water were added to a cordierite forming raw material to obtain a forming raw material. The forming raw material was mixed and kneaded to prepare a columnar kneaded material. As an organic binder, methylcellulose was used, and 5 parts by mass of methylcellulose was added to 100 parts by mass of the cordierite forming raw material. The water was added as a dispersing medium as much as 10 mass % to the whole forming raw material. The cordierite forming raw material is a raw material which becomes cordierite when fired. Specifically, the cordierite forming raw material is a ceramic raw material obtained by mixing “predetermined raw materials” to obtain a chemical composition in which silica (SiO2) is in a range of 42 to 56 mass %, alumina (Al2O3) is in a range of 30 to 45 mass %, and magnesia (MgO) is in a range of 12 to 16 mass %. “The predetermined raw materials” are raw materials selected from the group consisting of talc, kaolin, calcinated kaolin, alumina, aluminum hydroxide and silica.

Next, the kneaded material was extruded by using a predetermined die to obtain a honeycomb formed body having partition walls defining a plurality of cells and a circumferential wall formed simultaneously with the partition walls by the extrusion. In the honeycomb formed body, the cell shape (shape of each cell in the cross section perpendicular to the extending direction of the cells) was square and the whole shape was columnar.

Next, the obtained honeycomb formed body was dried by dielectric drying and hot air drying, and then fired at the highest temperature of 1420° C. for 100 hours to prepare a honeycomb fired body.

The obtained honeycomb fired body had a partition wall thickness of 100 μm and a cell density of 45 cells/cm2. Furthermore, the porosity of the partition walls of the honeycomb fired body was 50%. In addition, the average pore diameter of the honeycomb fired body was 18 μm. The honeycomb fired body had a columnar shape having a bottom surface diameter of 320 mm and a length of 300 mm in the cell extending direction. Additionally, the porosity and the average pore diameter were values measured by a mercury porosimeter.

Next, resin members made of polyethylene were pushed from the inflow end face side along the cell extending direction into the honeycomb structure so as to destroy predetermined end portions of partition walls, thereby removing portions (inflow end portions) from the partition wall. Afterward, portions (outflow end portions) of the partition wall on the outflow end face side were similarly removed.

Next, plugging material was charged into parts of region formed by removing the portions from the partition wall so that holes where the adjacent cells communicate with each other are left. That is, the plugging material was charged into each cell at a depth smaller than the depth of the removed portion. Afterward, the firing was performed again. In this way, the honeycomb structure made of a porous ceramic material was prepared.

The prepared honeycomb structure was such a honeycomb structure as shown in FIG. 1. The arrangement pattern of cell groups was such a pattern as shown in FIG. 5A. Specifically, inlet cells, both-end plugged cells and outlet cells were arranged so that centers of the three cells constituting each cell groups were positioned on a same straight line. Furthermore, a plurality of cell groups was present and the cell groups were vertically and horizontally aligned and arranged.

The open area of each first flow-through hole was 0.3 times as large as the average value of the sectional areas of the inlet cells, the both-end plugged cells and the outlet cells constituting the cell groups. Furthermore, the open area of each second flow-through hole was 0.3 times as large as the average value of the sectional areas of the inlet cells, the both-end plugged cells and the outlet cells constituting the cell groups. As to the calculation of the above open areas, 20 cell groups were randomly selected.

In addition, the ratio of the cell groups was 100%. It is to be noted that the ratio of the cell groups is a ratio of “number of the cell groups” to “value of ⅓ of the number of all the cells”. Furthermore, when the “number of the cell groups” is counted, a same cell is not counted twice. That is, it can be considered that the “number of the cell groups” is the number of the both-end plugged cells. It is to be noted that when the cells are counted, cells deformed by the circumferential wall or cells in which one or more sides forming each cell constitute a part of the circumferential wall (incomplete cells) are excluded. Furthermore, the shape of the opening of each of the first flow-through holes and second flow-through holes was quadrangular. The width of the opening of the flow-through hole was the same as the width of the inner dimension of each cell. Specifically, the partition wall destroyed by pushing the resin member made of polyethylene into the honeycomb structure as described above had a state where a part of the partition wall did not remain in the form of a so-called burr. It is to be noted that it can be considered, for example, that FIG. 3 shows a state where a part of each partition wall remains in the form of the so-called burr.

Next, as to the obtained honeycomb structure, “trapping efficiency”, “initial pressure loss” and “pressure loss after ash deposition” were measured and evaluated by the following methods. The results are shown in Table 1.

[Trapping Efficiency]

An exhaust gas (200° C.) including soot generated by a “soot generator which burns diesel fuel (light oil), thereby generating soot” was allowed to pass the honeycomb structure. The soot included in the exhaust gas before the exhaust gas passed the honeycomb structure was trapped with filter paper, and the weight (W1) of the soot was measured. The soot included in the exhaust gas which passed the honeycomb structure was trapped with filter paper, and the weight (W2) of the soot was measured. The obtained (W1) and (W2) were substituted into Equation (1) described below, to obtain the trapping efficiency (%).


((W1−W2)/W1)×100  Equation (1)

Afterward, the trapping efficiency was evaluated on the basis of the following standards. When the trapping efficiency improves as much as 15% or more as compared with trapping efficiencies of corresponding comparative examples each having plugging portions only at the inflow end face or only at the outflow end face (shown by “TE1 to TE6” in Table 2), the evaluation is “A”. When the improvement is 10% or more and smaller than 15%, the evaluation is “B”. When the improvement is 5% or more and smaller than 10%, the evaluation is “C”. When the improvement is smaller than 5%, the evaluation is “D”. It is to be noted that the improvement of the trapping efficiency of 5% or more can usually be considered to be preferable (practical). The results are shown in Table 1.

[Initial Pressure Loss]

Air was allowed to flow through the honeycomb structure at an atmospheric pressure (1 atm), room temperature (20° C.) and a rate of 15 m3/minute to measure the “initial pressure loss”. Afterward, the initial pressure loss was evaluated on the basis of the following standards.

When the initial pressure loss decreases as much as 30% or more as compared with pressure losses of corresponding comparative examples each having plugging portions in end portions on both of the inlet side and the outlet side (shown by “PD1 to PD3” in Table 2), the evaluation is “A”. When the decrease is smaller than 30% and 15% or more, the evaluation is “B”. When the decrease is smaller than 15% and 5% or more, the evaluation is “C”. When the decrease is smaller than 5%, the evaluation is “D”. It is to be noted that the decrease of the initial pressure loss of 5% or more can usually be considered to be preferable (i.e., practical). The results are shown in Table 1.

[Pressure Loss after Ash Deposition]

Ash discharged from engine was collected in advance, for example, at the above evaluation tests, which is prepared for use. First, in a state where the inflow end face of the honeycomb structure was disposed to face upside, 100 g of the ash was supplied into the honeycomb structure from the inflow end face. Next, this honeycomb structure was attached to an exhaust tube of a six-cylinder 6,000 cc diesel engine, and operated on conditions of 2,000 rpm and 100 N-m. After ten minutes from the start of the engine, “initial pressure loss after ash deposition” was measured. Afterward, the initial pressure loss after ash deposition was evaluated on the basis of the following standards. When the “initial pressure loss after ash deposition” increases as much as 5% or less from the “initial pressure loss”, the evaluation is “A”. When the increase is in excess of 5% and 10% or less, the evaluation is “B”. When the increase is in excess of 10% and 20% or less, the evaluation is “C”. When the increase is in excess of 20%, the evaluation is “D”. An increase of 20% or less can be considered to be practical. The results are shown in Table 1.

TABLE 1 Arrangement Partition wall Open area of first Open area of Initial pattern of cell thickness Cell density flow-through second flow- Trapping pressure Pressure loss after Structure groups (μm) (cells/cm2) hole (times) through hole (times) efficiency loss ash deposition Example 1 Integral FIG. 5A 140 65 0.3 0.3 A C B Example 2 Integral 140 65 0.5 0.5 A B A Example 3 Integral 140 65 0.5 1.0 A A A Example 4 Integral 140 65 1.0 0.5 A A A Example 5 Integral 140 65 1.0 1.0 A A A Example 6 Integral 140 65 2.0 2.0 A A A Example 7 Integral 140 65 3.0 3.0 A A A Example 8 Integral 140 65 3.5 3.5 B A A Example 9 Integral FIG. 6A 250 35 0.5 0.5 A B A Example 10 Integral 250 35 3.0 3.0 A A A Example 11 Integral FIG. 8  140 65 0.3 0.3 A C B Example 12 Integral 140 65 1.0 1.0 A A A Example 13 Integral FIG. 9  250 35 0.3 0.3 A C B Example 14 Integral 250 35 1.0 1.0 A A A Example 15 Integral FIG. 11C 140 65 0.3 0.3 A C B Example 16 Integral 140 65 0.5 0.5 A B A Example 17 Integral 140 65 2.0 3.0 A A A Example 18 Integral 140 65 3.5 3.5 B A A Example 19 Segment FIG. 7A 250 35 0.3 0.3 A C B Example 20 Segment 250 35 1.0 1.0 A A A Example 21 Segment FIG. 10 250 35 1.0 2.0 A A A Example 22 Segment 250 35 3.5 3.5 B A A

In the honeycomb structure of the present example, the evaluation of “trapping efficiency” was “A”, the evaluation of “initial pressure loss” was “C”, and the evaluation of “pressure loss after ash deposition” was “B”.

In Tables 1 and 2, “integral” in the column of “structure” indicates that the honeycomb structure is constituted of one extruded structure as in the present example. “Segment” in the column of “structure” indicates that the honeycomb structure is constituted by bonding a plurality of segment honeycomb structures with a bonding material.

Examples 2 to 22 and Comparative Examples 0.1 to 9

First, in Examples 2 to 18, the procedures of Example 1 were repeated to prepare honeycomb structures satisfying conditions shown in Tables 1 and 2.

In each of Examples 19 to 22, segment honeycomb structures each having a cross section of vertical size 40 mm×horizontal size 40 mm and length 300 mm were prepared. The prepared segment honeycomb structures were bonded with a bonding material to prepare a bonded honeycomb assembly, and the outer circumference of this bonded honeycomb assembly was ground. Afterward, an outer circumference coating having a thickness of 1 mm was further applied to prepare a honeycomb structure having a diameter of 320 mm and a length of 300 mm. Additionally, the thickness of the bonding material was 1 mm.

Comparative Examples 1 to 9 were honeycomb structures which have no flow-through holes to allow adjacent cells to communicate with each other or no both-end plugged cells having both end portions plugged. Furthermore, such honeycomb structures are conventional type honeycomb structures having plugging portions in a checkered pattern at both end faces, only in an inflow end face, or only in an outflow end face. Comparative Examples 1 to 3 are comparative examples corresponding to Examples 1 to 8, 11, 12 and 15 to 18. Comparative Examples 4 to 6 are comparative examples corresponding to Examples 9, 10, 13 and 14. Comparative Examples 7 to 9 are comparative examples corresponding to Examples 19 to 22.

Additionally, as to “trapping efficiency”, evaluation was performed on the basis of a comparative example which has a better trapping efficiency (i.e., having a larger trapping efficiency) of the two comparative examples corresponding to the example and each having plugging portions “only at the inflow end face” or “only at the outflow end face”. For example, the trapping efficiency of the honeycomb structure of Example 1 was evaluated on the basis of the honeycomb structure of Comparative Example 2 or 3 having a larger trapping efficiency TE1 or TE2.

As to each of the above honeycomb structures, the procedures of Example 1 were repeated to measure and evaluate “trapping efficiency”, “initial pressure loss” and “pressure loss after ash deposition”. The results are shown in Tables 1 and 2. In Table 2, “both end faces” in the column of “arrangement of plugging portions” indicate that plugging portions are formed in end portions of predetermined cells on the inflow end face side and end portions of the residual cells on the outflow end face side wherein the plugging portions are arranged alternately (in a zigzag manner) so as to form so-called checkered patterns at both of the end faces. In Table 2, “inflow end face only” in the column of “arrangement of plugging portions” indicates that the plugging portions are disposed only in the end portions on the inflow end face side, and the plugging portions are not disposed in the end portions on the outflow end face side wherein the above plugging portions are arranged to form the so-called checkered pattern in the inflow end face. In Table 2, “only the outflow end face” in the column of “the arrangement of the plugging portions” indicates that the plugging portions are disposed only in the end portions on the outflow end face side, the plugging portions are not disposed in the end portions on the inflow end face side wherein the above plugging portions are arranged to form the so-called checkered pattern at the outflow end face.

TABLE 2 Partition wall Initial thickness Cell density Arrangement of Trapping pressure Structure (μm) (cells/cm2) plugging portions efficiency loss Comparative Integral 140 65 Both end face — PD1 Example 1 Comparative Integral 140 65 Inflow end face only TE1 — Example 2 Comparative Integral 140 65 Outflow end face TE2 — Example 3 only Comparative Integral 250 35 Both end face — PD2 Example 4 Comparative Integral 250 35 Inflow end face only TE3 — Example 5 Comparative Integral 250 35 Outflow end face TE4 — Example 6 only Comparative Segment 250 35 Both end face — PD3 Example 7 Comparative Segment 250 35 Inflow end face only TE5 — Example 8 Comparative Segment 250 35 Outflow end face TE6 — Example 9 only

It has been confirmed that the honeycomb structures of Examples 1 to 22 have improved initial pressure loss and trapping efficiency as compared with the honeycomb structures of Comparative Examples 1 to 9. Furthermore, it can be confirmed that the pressure loss after ash deposition increases less and maintenance operations to be performed when the ash is accumulated is not required. Additionally, after the test, each honeycomb structure was disassembled to observe the insides of the cells. A small amount of ash has been deposited, and it can be considered that most of the ash has been discharged together with the exhaust gas from the engine.

INDUSTRIAL APPLICABILITY

A honeycomb structure of the present invention can be used as a filter to purify exhaust gas discharged from a car or the like.

DESCRIPTION OF SYMBOLS

1 and 3: partition wall, 1a: first common partition wall, 1b: second common partition wall, 2: cell, 2a: inlet cell, 2b: both-end plugged cell, 2c: outlet cell, 5: cell group, 7: first flow-through hole, 8: second flow-through hole, 10: honeycomb substrate, 11: inflow end face, 12 and 112: outflow end face, 20: resin member, 23: plugging material, 25: plugging portion, 26: circumferential wall, 50: honeycomb fired body, and 100: honeycomb structure.

Claims

1. A honeycomb structure comprising:

a honeycomb substrate having partition walls defining a plurality of cells which form through channels for a fluid and extend from an inflow end face as one end face where the fluid flows in to an outflow end face as the other end face where the fluid flows out; and
plugging portions disposed at open ends of the cells of the honeycomb substrate,
wherein the cells include at least one cell group consisting of three cells which are a both-end plugged cell in which the plugging portions are disposed at both open ends on the inflow end face side and the outflow end face side, an inlet cell which is adjacent to the both-end plugged cell and in which the plugging portion is only disposed at the open end on the outflow end face side, and an outlet cell which is adjacent to the both-end plugged cell and in which the plugging portion is only disposed at the open end on the inflow end face side,
the partition walls defining the both-end plugged cell constituting the cell group have a first common partition wall which is a common partition wall defining both of the inlet cell and the both-end plugged cell, and a second common partition wall which is a common partition wall defining both of the outlet cell and the both-end plugged cell,
a first flow-through hole is formed in an end portion of the first common partition wall on the outflow end face side, and
a second flow-through hole is formed in an end portion of the second common partition wall on the inflow end face side.

2. The honeycomb structure according to claim 1,

wherein in a cross section of the honeycomb substrate which is perpendicular to an extending direction of the cells, the inlet cell, the both-end plugged cell and the outlet cell constituting each of the at least one cell group are arranged so that a first center which is the center of the inlet cell, a second center which is the center of the both-end plugged cell and a third center which is the center of the outlet cell are positioned on a same straight line.

3. The honeycomb structure according to claim 1,

wherein in the cross section of the honeycomb substrate which is perpendicular to the extending direction of the cells, the inlet cell, the both-end plugged cell and the outlet cell constituting each of the at least one cell group are arranged to form an L-shape.

4. The honeycomb structure according to claim 1,

wherein an open area of the first flow-through hole is from 0.3 to 3.5 times as large as an average value of sectional areas in the direction perpendicular to the cell extending direction of the inlet cell, the both-end plugged cell and the outlet cell constituting the cell group.

5. The honeycomb structure according to claim 2,

wherein an open area of the first flow-through hole is from 0.3 to 3.5 times as large as an average value of sectional areas in the direction perpendicular to the cell extending direction of the inlet cell, the both-end plugged cell and the outlet cell constituting the cell group.

6. The honeycomb structure according to claim 3,

wherein an open area of the first flow-through hole is from 0.3 to 3.5 times as large as an average value of sectional areas in the direction perpendicular to the cell extending direction of the inlet cell, the both-end plugged cell and the outlet cell constituting the cell group.

7. The honeycomb structure according to claim 1,

wherein an open area of the second flow-through hole is from 0.3 to 3.5 times as large as the average value of the sectional areas in the direction perpendicular to the cell extending direction of the inlet cell, the both-end plugged cell and the outlet cell constituting the cell group.

8. The honeycomb structure according to claim 2,

wherein an open area of the second flow-through hole is from 0.3 to 3.5 times as large as the average value of the sectional areas in the direction perpendicular to the cell extending direction of the inlet cell, the both-end plugged cell and the outlet cell constituting the cell group.

9. The honeycomb structure according to claim 3,

wherein an open area of the second flow-through hole is from 0.3 to 3.5 times as large as the average value of the sectional areas in the direction perpendicular to the cell extending direction of the inlet cell, the both-end plugged cell and the outlet cell constituting the cell group.

10. The honeycomb structure according to claim 1,

which is made of a porous ceramic material.

11. The honeycomb structure according to claim 1,

wherein the honeycomb substrate is integrally formed.

12. The honeycomb structure according to claim 1,

wherein the honeycomb substrate has a segment structure constituted of a plurality of honeycomb segments.
Patent History
Publication number: 20150240679
Type: Application
Filed: Feb 12, 2015
Publication Date: Aug 27, 2015
Inventors: Toshio YAMADA (Nagoya-City), Shogo HIROSE (Nagoya-City), Toshihiro HIRAKAWA (Nagoya-City)
Application Number: 14/620,507
Classifications
International Classification: F01N 3/022 (20060101);