JP6259334B2 - Honeycomb structure - Google Patents

Description

  The present invention relates to a honeycomb structure. More specifically, the present invention relates to a honeycomb structure that can favorably collect particulate matter contained in exhaust gas and can effectively suppress the outflow of the particulate matter once collected to the outside.

  In recent years, it has been demanded to collect “particulate matter mainly composed of carbon” discharged from internal combustion engines such as automobiles, railways, construction machines, and agricultural machines, particularly diesel engines. Hereinafter, the particulate matter may be referred to as “PM” or “particulate matter”. It is also required to collect PM discharged from a gasoline engine such as a GDI (Gasoline Direct Injection) engine. On the other hand, recently, one end of a predetermined cell and the other end of the remaining cell are plugged, and the predetermined cell and the remaining cell are alternately arranged. The sealed honeycomb structure is used as a diesel particulate filter (DPF). And the method of collecting PM discharged | emitted from a diesel engine etc. by such DPF is used actively (for example, refer patent document 1).

  According to such a DPF, the exhaust gas flows into the cell from the end face on the inlet side of the exhaust gas, the exhaust gas that has flowed into the cell passes through the partition wall, and the exhaust gas that has passed through the partition wall (in other words, purified gas) The exhaust gas is discharged from the end face on the outlet side. And when exhaust gas passes a partition, PM contained in exhaust gas is collected by a partition, and exhaust gas is purified.

  However, in the conventional “honeycomb structure with plugged portions formed on both end faces”, all of the inflowing exhaust gas passes through the partition walls, and most of the particulate matter in the exhaust gas is collected by the partition walls. Therefore, the pressure loss is likely to increase. In addition, ash (Ash) is generated by S, Ca, etc. contained in the engine oil and fuel, and the ash accumulates in the DPF cell after a long period of operation, resulting in an increase in pressure loss. It was.

  In order to solve such problems, there has been proposed a honeycomb structure (honeycomb filter) in which a plugging portion is formed only on an end surface on the exhaust gas outflow side (see, for example, Patent Documents 2 to 4). . In addition, a honeycomb structure in which a plugged portion is formed only on an end surface on the exhaust gas inflow side has been proposed (see, for example, Patent Document 5).

JP 2003-254034 A JP 2002-537965 A Japanese Patent No. 39442086 JP 2004-251137 A International Publication No. 2012/046484

  However, in the honeycomb filters described in Patent Documents 2 to 4, ash is accumulated in the cells in which the plugging portions are formed, and the spaces in the cells are filled with ash. There was a problem that the pressure loss increased. Moreover, in the honeycomb filter described in Patent Documents 2 to 4, PM in the exhaust gas is sequentially deposited on the outflow end face side of the cell in which the plugged portions are formed. Therefore, for example, when PM deposited on the outflow end face side burns at a time, the honeycomb filter locally becomes extremely hot, and damage such as cracks may occur near the outflow end face side of the honeycomb filter.

  In addition, as shown in FIG. 7A, the honeycomb structure described in Patent Document 5 tends to easily deposit particulate matter 813 in the opening on the inflow end face 811 side of the honeycomb structure 800. Here, FIG. 7A is a schematic diagram showing a cross section parallel to the cell extending direction of the conventional honeycomb structure. A honeycomb structure 800 shown in FIG. 7A is a honeycomb structure 800 in which plugging portions 805 are provided only on the inflow end surface 811. In such a honeycomb structure 800, a differential pressure is generated between the through-cell 802a and the inlet plugged cell 802b from a location where the plugged portion 805 on the inflow end face 811 side is interrupted. In this honeycomb structure 800, a large amount of particulate matter 813 contained in the exhaust gas G is deposited in the vicinity of the portion where the plugging portion 805 on the inflow end face 811 side is interrupted. Therefore, when the above-described deposition of the particulate matter 813 exceeds a certain amount, the particulate matter 813 locally deposited on the inflow end face 811 side is peeled off from the partition wall 801 as shown in FIG. 7B. There is. Even when the flow rate of the exhaust gas G flowing from the inflow end surface 811 increases, the particulate matter 813 locally deposited on the inflow end surface 811 side may be peeled off from the partition wall 801. Further, since the flow path of the through-cell 802a is easily blocked by the particulate matter 813, the flow rate of the exhaust gas G is increased at the closed portion, and the above-described separation of the particulate matter 813 may be more likely to occur. Then, the particulate matter 813 peeled off from the partition wall 801 passes through the through-cell 802 a and flows out from the outflow end surface 812 of the honeycomb structure 800. In this manner, the particulate matter 813 that has been peeled off from the partition wall 801 flows out of the outflow end surface 812 of the honeycomb structure 800 is hereinafter referred to as “blow-off”. Such a blow-off problem is a problem peculiar to the honeycomb structure 800 that has the through-cell 802a and collects the particulate matter 813 in the partition wall 801 that partitions the through-cell 802a. Currently, there is a demand for development of a honeycomb structure in which such blow-off is suppressed. FIG. 7B is a schematic view showing a state where the honeycomb structure shown in FIG. 7A is blown off. 7A and 7B, reference numeral 803 indicates an outer peripheral wall, and reference numeral 804 indicates a honeycomb substrate.

  The present invention has been made in view of the above-described problems of the prior art, and can successfully collect the particulate matter contained in the exhaust gas, and the particulate matter once collected. A honeycomb structure capable of effectively suppressing outflow to the outside is provided.

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

[1] A honeycomb base having a porous partition wall defining a plurality of cells that serve as fluid flow paths extending from an inflow end surface, which is an end surface on the exhaust gas inflow side, to an outflow end surface, which is an end surface on the exhaust gas outflow side. The partition wall has a porosity of 35 to 65%, and the cell substantially penetrates from the inflow end face side to the outflow end face side, and the inflow end face side of the honeycomb substrate. An inlet plugged cell in which the end of the cell is substantially plugged by the plugged portion, and the end of the cell is substantially plugged by the plugged portion on the outflow end face side of the honeycomb substrate. An outlet plugged cell that is plugged, and the number of through cells is 40 to 60% of the number of all the cells, and the number of inlet plugged cells is the inlet Total number of plugged cells and outlet plugged cells On the other hand, the specific penetration is 60 to 85%, and the through cell is arranged to be adjacent to the at least one inlet plugged cell and the at least one outlet plugged cell with the partition wall therebetween. A honeycomb structure including cells, wherein the number of the specific through cells is 70% or more with respect to the number of all the through cells.

[2] The honeycomb structure according to [1], wherein the partition wall has a thickness of 120 to 460 μm.

[3] The honeycomb structure according to [1] or [2], wherein the honeycomb substrate has a cell density of 15 to 100 cells / cm ² .

  According to the honeycomb structure of the present invention, the particulate matter contained in the exhaust gas can be well collected, and the once-collected particulate matter can be effectively suppressed from flowing out. . A honeycomb structure according to the present invention has a porous partition wall that forms a plurality of cells serving as fluid flow paths extending from an inflow end surface that is an end surface on the exhaust gas inflow side to an outflow end surface that is an end surface on the exhaust gas outflow side. And a honeycomb substrate having the above. In this honeycomb structure, the porosity of the partition walls of the honeycomb base material is 35 to 65%. In this honeycomb structure, the plurality of cells include a through cell, an inlet plugged cell, and an outlet plugged cell. Here, the penetration cell is a cell that penetrates substantially from the inflow end face side to the outflow end face side. The inlet plugged cell is a cell in which the end of the cell is substantially blocked by the plugged portion on the inflow end face side of the honeycomb base material. The outlet plugged cell is a cell in which the end of the cell is substantially plugged by the plugged portion on the outflow end face side of the honeycomb substrate. In this honeycomb structure, the number of penetrating cells is 40 to 60% with respect to the number of all cells. In this honeycomb structure, the number of inlet plugged cells is 60 to 85% with respect to the total number of inlet plugged cells and outlet plugged cells. The honeycomb structure includes a specific through cell, the through cell being disposed so as to be adjacent to the at least one inlet plugged cell and the at least one outlet plugged cell with a partition wall therebetween. The number of penetrating cells is 70% or more with respect to the number of all penetrating cells.

  In the honeycomb structure of the present invention, when exhaust gas flows into a through cell in which no plugging portion is disposed, the pressure in the through cell increases, and the pressure in the inlet plugged cell adjacent to the through cell Becomes relatively low with respect to the pressure in the penetrating cell. Therefore, a part of the exhaust gas passes through the partition wall from the through cell and flows into the inlet plugged cell, and the side of the inlet plugged cell where the plugged portion is not disposed (outflow end surface of the honeycomb substrate) The exhaust gas that has permeated through the partition wall is discharged from the end of the side. As described above, since part of the exhaust gas permeates the partition walls, the particulate matter contained in the exhaust gas accumulates on the partition walls in the through-cells, so that the particulate matter can be collected well. .

  In the honeycomb structure of the present invention, it is important that the specific through-cell is disposed so as to be adjacent to at least one inlet plugged cell and at least one outlet plugged cell with a partition wall therebetween. is there. By having such a specific penetration cell, it can be set as the honeycomb structure by which blow-off was controlled. That is, in this specific penetration cell, particulate matter is deposited on the partition wall that partitions the specific penetration cell and the inlet plugged cell from the vicinity of the plugging portion on the inflow end face side. However, particulate matter does not accumulate much on the partition walls that partition the specific through-cells and the outlet plugged cells. The reason for this is that the amount of exhaust gas moving from the specific through cell to the outlet plugged cell is smaller than the amount of exhaust gas moving from the specific through cell to the inlet plugged cell. Actually, the pressure in the outlet plugged cell may be increased by the pressure in the specific through-cell and the pressure in the outlet plugged cell. Therefore, the specific through-cell and the outlet plugged cell are separated from each other. On the surface of the partition wall on the side of the specific penetrating cell, the particulate matter may hardly be deposited. Therefore, particulate matter is unlikely to accumulate on at least one surface of the partition wall in the specific through cell (that is, the surface of the partition wall that partitions the specific through cell and the outlet plugged cell), and the flow path is blocked. It is hard to happen. For this reason, according to the honeycomb structure of the present invention, blow-off can be effectively suppressed.

1 is a perspective view schematically showing a first embodiment of a honeycomb structure of the present invention as seen from an inflow end face side. FIG. FIG. 2 is a perspective view schematically showing the first embodiment of the honeycomb structure of the present invention as seen from the outflow end face side. FIG. 3 is a plan view schematically showing the first embodiment of the honeycomb structure of the present invention as viewed from the inflow end face side. FIG. 2 is a plan view schematically showing the first embodiment of the honeycomb structure of the present invention as seen from the outflow end face side. [Fig. 3] Fig. 3 is a schematic view showing a cross section of the first embodiment of the honeycomb structure of the present invention parallel to the direction in which the exhaust gas flows. [Fig. 3] Fig. 3 is a schematic view showing a cross section of the first embodiment of the honeycomb structure of the present invention parallel to the direction in which the exhaust gas flows. It is an enlarged view which expands and shows the range enclosed with the broken line shown to the code | symbol X of FIG. 6A. It is a schematic diagram which shows a cross section parallel to the cell extending direction of the conventional honeycomb structure. FIG. 7B is a schematic view showing a state where the honeycomb structure shown in FIG. 7A is blown off.

  Embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments. Accordingly, it is understood that modifications, improvements, and the like to the following embodiments are also included in the scope of the present invention based on ordinary knowledge of those skilled in the art without departing from the spirit of the present invention. Should be.

(1) Honeycomb structure:
As shown in FIGS. 1 to 5, the first embodiment of the honeycomb structure of the present invention includes a porous partition wall 1 that partitions and forms a plurality of cells 2 that serve as fluid (ie, exhaust gas G) flow paths. This is a honeycomb structure 100 including the honeycomb substrate 4. The partition wall 1 defines a plurality of cells 2 extending from an inflow end surface 11 that is an end surface on the exhaust gas G inflow side to an outflow end surface 12 that is an end surface on the exhaust gas G outflow side. In the honeycomb structure 100 of the present embodiment, the porosity of the partition walls 1 of the honeycomb substrate 4 is 35 to 65%. Further, in the honeycomb structure 100 of the present embodiment, the plurality of cells 2 include through cells 2a, inlet plugged cells 2b, and outlet plugged cells 2c. Here, the penetration cell 2a is a cell 2 that penetrates substantially from the inflow end face 11 side to the outflow end face 12 side. The inlet plugged cell 2 b is a cell 2 in which the end of the cell 2 is substantially blocked by the plugged portion 5 on the inflow end face 11 side of the honeycomb substrate 4. The outlet plugged cell 2 c is a cell 2 in which the end of the cell 2 is substantially closed by the plugged portion 5 on the outflow end face 12 side of the honeycomb substrate 4. In the honeycomb structure 100 of the present embodiment, the number of the penetrating cells 2 a is 40 to 60% with respect to the number of all the cells 2. Further, the number of the inlet plugged cells 2b is 60 to 85% with respect to the total number of the inlet plugged cells 2b and the outlet plugged cells 2c. Further, in the honeycomb structure 100 of the present embodiment, the through cell 2a includes the specific through cell 2aa. The specific through-cell 2aa is a cell 2 arranged so as to be adjacent to the at least one inlet plugged cell 2b and at least one outlet plugged cell 2c with the partition wall 1 therebetween. And the number of this specific penetration cell 2aa is 70% or more with respect to the number of all penetration cells 2a. Hereinafter, for example, the penetration cell 2a and the inlet plugged cell 2b are “disposed adjacent to each other with the partition wall 1 therebetween”, and the through cell 2a and the inlet plugged cell 2b are “adjacently disposed”. Or simply “adjacent”.

  Here, “the end portion of the cell is“ substantially blocked by the plugged portion ”” means that the end portion of the cell is blocked by the plugged portion so that the exhaust gas hardly passes through the cell. It means a state. There may be a small amount of gas flow passing through the plugged portion due to the slight gap formed during the plugging formation and the plugged portion 5 being a porous body. Further, “the cell penetrates“ substantially ”” means a state in which the exhaust gas can pass through the cell. This includes a case where the exhaust gas can pass through the cell even if the plugged portion or the like is disposed in the cell due to a state where a hole is opened in the plugged portion or the like. Further, in the columnar honeycomb structure 100 as shown in FIG. 1, the “cell extending direction” means the direction of the central axis of the columnar honeycomb structure 100.

  FIG. 1 is a perspective view schematically showing the first embodiment of the honeycomb structure of the present invention as seen from the inflow end face side. FIG. 2 is a perspective view schematically showing the first embodiment of the honeycomb structure of the present invention as seen from the outflow end face side. FIG. 3 is a plan view schematically showing the first embodiment of the honeycomb structure of the present invention as seen from the inflow end face side. FIG. 4 is a plan view seen from the outflow end face side, schematically showing the first embodiment of the honeycomb structure of the present invention. FIG. 5 is a schematic view showing a cross section of the first embodiment of the honeycomb structure of the present invention parallel to the direction in which the exhaust gas flows.

  According to the honeycomb structure 100 of the present embodiment, the particulate matter contained in the exhaust gas can be well collected, and the particulate matter once collected can be effectively prevented from flowing out. Can do. That is, as shown in FIG. 6A, according to the honeycomb structure 100 of the present embodiment, when the exhaust gas G is caused to flow from the inflow end face 11 of the honeycomb substrate 4, the particulate matter contained in the exhaust gas G is The through-cell 2a can be collected by the partition wall 1 that forms a partition. That is, when the exhaust gas G flows into the penetration cell 2a, the pressure in the penetration cell 2a increases, and the pressure in the inlet plugged cell 2b adjacent to the penetration cell 2a is relative to the pressure in the penetration cell 2a. It becomes low. Therefore, a part of the exhaust gas G passes through the porous partition wall 1 from the through cell 2a and flows into the inlet plugged cell 2b, and the exhaust gas G that has flowed into the inlet plugged cell 2b flows into the inlet plugged cell 2b. It discharges | emits from the edge part of the side by which the plugging part 5 is not arrange | positioned of the stop cell 2b. When the through cell 2a and the inlet plugged cell 2b are adjacent to each other, the exhaust gas G passes through the porous partition wall 1 positioned between the through cell 2a and the inlet plugged cell 2b, and the “through cell 2a To the inlet plugged cell 2b ". And since the particulate matter contained in exhaust gas G accumulates in the partition 1 in the penetration cell 2a when a part of the exhaust gas G permeates the partition 1 in this way, the particulate matter is collected. be able to. FIG. 6A is a schematic diagram showing a cross section of the first embodiment of the honeycomb structure of the present invention parallel to the direction in which the exhaust gas flows.

  In the honeycomb structure 100 of the present embodiment, the specific through-cell 2aa is disposed so as to be adjacent to the at least one inlet plugged cell 2b and the at least one outlet plugged cell 2c with the partition wall 1 therebetween. This is very important. By having such specific penetration cell 2aa, it can be set as honeycomb structure 100 by which blow-off was controlled. That is, in the specific penetration cell 2aa, the particulate matter 13 is deposited on the partition wall 1 separating the specific penetration cell 2aa and the inlet plugged cell 2b from the vicinity of the plugging portion 5 on the inflow end face 11 side. Arise. However, the particulate matter 13 does not accumulate much on the partition walls 1 separating the specific through-cells 2aa and the outlet plugged cells 2c. The reason for this is that the amount of exhaust gas G moving from the specific through cell 2aa to the outlet plugged cell 2c is smaller than the amount of exhaust gas G moving from the specific through cell 2aa to the inlet plugged cell 2b. Can be mentioned. Actually, the pressure in the outlet plugged cell 2c may be higher than the pressure in the specific through-cell 2aa and the pressure in the outlet plugged cell 2c. For this reason, deposition of particulate matter may hardly occur on the surface of the partition wall 1 separating the specific through cell 2aa and the outlet plugged cell 2c on the specific through cell 2aa side. For this reason, the particulate matter 13 is hardly deposited on at least one surface of the partition wall 1 in the specific penetration cell 2aa, and the inflow end face 11 side of the specific penetration cell 2aa is less likely to be narrowed by the deposition of the particulate matter 13. . And if the flow path in specific penetration cell 2aa can be ensured widely, even if the flow volume of exhaust gas G increases, the pressure concerning the deposited particulate matter 13 can be controlled, and the partition of particulate matter 13 The peeling off from 1 can be prevented. Therefore, according to the honeycomb structure 100 of the present embodiment, the particulate matter 13 once collected can be effectively prevented from flowing out (in other words, blow-off). The effect of effectively suppressing such blow-off is a remarkable effect peculiar to the honeycomb structure 100 having the penetrating cell 2a and collecting the particulate matter 13 in the partition wall 1 partitioning the penetrating cell 2a. is there.

  In the honeycomb structure of the present embodiment, the porosity of the partition walls is 35 to 65%. When the porosity of the partition walls is less than 35%, the pressure loss of the honeycomb structure increases. Further, when the porosity of the partition walls exceeds 65%, the collection efficiency for collecting the particulate matter is lowered, and the strength of the honeycomb structure is also lowered. In addition, when the porosity of the partition wall exceeds 65%, the blow-off suppressing effect may not be sufficiently exhibited. The porosity of the partition walls is preferably 37 to 63%, more preferably 40 to 60%, and particularly preferably 45 to 55%. The porosity of the partition wall is a value measured with a mercury porosimeter.

  In the honeycomb structure of the present embodiment, the number of penetrating cells is 40 to 60% with respect to the number of all cells. Hereinafter, the “ratio of the number of penetrating cells to the number of all cells” may be simply referred to as “the ratio of the number of penetrating cells” or “the ratio of the penetrating cells”. When the ratio of the penetrating cells is less than 40%, the pressure loss of the honeycomb structure greatly increases. When the ratio of the penetrating cells exceeds 60%, the collection efficiency for collecting the particulate matter of the honeycomb structure is lowered. The ratio of the penetrating cells is preferably 42 to 58%, and more preferably 45 to 55%.

  Further, in order to effectively prevent the particulate matter once collected from peeling off from the partition wall, the number of specific through cells is 70% or more with respect to the number of all through cells. is important. Hereinafter, the “ratio of the number of specific through cells with respect to the number of all through cells” may be simply referred to as “number ratio of specific through cells” or “ratio of specific through cells”. If the ratio of the specific penetrating cell is less than 70%, the effect of suppressing the outflow of the particulate matter once collected may not be sufficiently exhibited. The ratio of the specific through cell is preferably 70 to 100%, and more preferably 90 to 100%. By setting the ratio of the specific penetrating cells in the numerical range as described above, the outflow of the particulate matter to the outside can be particularly effectively suppressed.

  It is also important that the number of inlet plugged cells is 60 to 85% with respect to the total number of inlet plugged cells and outlet plugged cells. Hereinafter, “the ratio of the number of inlet plugged cells to the total number of inlet plugged cells and outlet plugged cells” is simply referred to as “number ratio of inlet plugged cells” or “inlet plugged cells”. The ratio of " When the ratio of the inlet plugged cells is less than 60%, when the “ratio of through cells” and the “ratio of specific through cells” satisfy the numerical range required in the present invention, the outlet plugged cells The number of is relatively large. Here, as shown in FIG. 6B, the particulate matter 13 contained in the exhaust gas G flowing in from the inflow end face 11 of the outlet plugged cell 2c is collected on the inner surface of the partition wall 1 partitioning the outlet plugged cell 2c. Is done. Then, most of the particulate matter 13 collected on the inner surface of the partition wall 1 partitioning the outlet plugged cells 2c is deposited so as to be collected on the outflow end face 12 side of the honeycomb substrate 4. When the number of the outlet plugged cells 2c is relatively increased, the particulate matter 13 deposited on the outlet end face 12 side of the outlet plugged cells 2c is also relatively increased. The component of the particulate material 13 is a combustible material such as soot, and when the collected particulate material 13 burns, the honeycomb structure 100 may locally become high temperature. For example, in the honeycomb structure 100 of the present embodiment, the collected particulate matter 13 may be burned to regenerate the filter function. In such regeneration, if the amount of the particulate matter 13 deposited on the outlet end face 12 side of the outlet plugged cell 2c is large, a large thermal stress is generated on the outlet end face 12 side of the outlet plugged cell 2c, and the honeycomb The structure 100 may be damaged. If the ratio of the inlet plugged cells 2b is 60% or more, the ratio of the outlet plugged cells 2c is relatively low, and when the honeycomb structured body 100 is regenerated as described above, the honeycomb structured body 100 Is difficult to break. In addition, if the ratio of the inlet plugged cells exceeds 85%, the blowoff suppression effect may not be sufficiently exhibited. The ratio of the inlet plugged cells is preferably 65 to 80%, and more preferably 70 to 75%. By setting the ratio of the inlet plugged cells in the above numerical range, it is possible to effectively achieve both the effect of suppressing blow-off and the effect of improving the durability of the honeycomb structure.

  The through-cell is a “specific through-cell” disposed adjacent to at least one inlet plugged cell and at least one outlet plugged cell, and at least one of the inlet plugged cell and the outlet plugged cell. And “non-specific through-cells” arranged so as not to be adjacent to each other. Hereinafter, the term “penetration cell” simply includes both “specific penetration cell” and “non-specific penetration cell”.

  Nonspecific penetration cells can include cells of the following modes. The “non-specific through cell of the first aspect” is a cell in which all the cells adjacent to the non-specific through cell are entrance plugged cells. The “non-specific through cell of the second aspect” is a cell in which all cells adjacent to the non-specific through cell are outlet plugged cells. The “non-specific through cell of the third aspect” is a cell in which all the cells adjacent to the non-specific through cell are through cells. The “non-specific through cell of the fourth aspect” is a cell in which cells adjacent to the non-specific through cell are only through cells and inlet plugged cells. The “non-specific through cell of the fifth aspect” is a cell in which cells adjacent to the non-specific through cell are only through cells and outlet plugged cells.

  The shape of the cells of the honeycomb substrate is not particularly limited, but is preferably a polygon, such as a triangle, a quadrangle, a pentagon, a hexagon, an octagon, a circle, or an ellipse in a cross section perpendicular to the cell extending direction. Other irregular shapes may also be used.

  The thickness of the partition wall is preferably 120 to 460 μm, and more preferably 150 to 390 μm. If it is thinner than 120 μm, the strength of the honeycomb substrate may be lowered. If it is thicker than 460 μm, the collection performance may be reduced and the pressure loss may be increased. In addition, when treating exhaust gas discharged from a diesel engine, the amount of PM in the exhaust gas discharged from the diesel engine is relatively large, and thus there is a general tendency to reduce the number of cells (reduce the cell density). . Therefore, it is preferable that the thickness of the partition wall 1 is 200 to 390 μm in order to improve the balance between strength and collection performance. In addition, when processing exhaust gas discharged from a gasoline engine, the amount of PM in the exhaust gas discharged from the gasoline engine is relatively small, and thus usually tends to increase the number of cells (increase the cell density). . Therefore, it is preferable to set the partition wall thickness to 150 to 360 μm in order to improve the balance between strength and collection performance. The thickness of the partition wall is a value measured by a method of observing a cross section in the axial direction of the honeycomb substrate with a microscope.

  When the honeycomb substrate has a partition wall porosity of 35 to 65% and a partition wall thickness of 0.10 to 0.40 mm, more effectively suppressing an increase in pressure loss, Particulate matter in exhaust gas can be collected. Further, by adopting the porosity and partition wall thickness as described above, the strength of the honeycomb base material is not lowered.

The cell density of the honeycomb substrate (the number of cells per unit area in a cross section perpendicular to the cell extending direction of the honeycomb substrate) is preferably 15 to 100 cells / cm ² . If it is less than 15 cells / cm ² , the collection performance may be lowered. If it is greater than 100 cells / cm ² , PM accumulates in the vicinity of the inflow end face of the honeycomb substrate, and the cells are blocked by PM, so that the pressure loss may increase. Moreover, when processing the exhaust gas discharged | emitted from a diesel engine, it is still more preferable that it is 30-70 cells / cm < ² >. When it is less than 30 cells / cm ² , the collection performance may be lowered. If it is greater than 70 cells / cm ² , the pressure loss may increase. Moreover, when processing the exhaust gas discharged | emitted from a gasoline engine, it is still more preferable that it is 15-100 cells / cm < ² >. Since the exhaust gas discharged from a gasoline engine has a small amount of PM, the risk of clogging the cells is low, so the cell density can be increased, and the collection performance can be increased by increasing the cell density. it can. In addition, since the cell is difficult to block, continuous reproduction is also easy. When it is less than 15 cells / cm ² , the collection performance may be lowered, and when it is more than 100 cells / cm ² , the pressure loss during PM collection may be increased.

  The average pore diameter of the partition walls is preferably 80 μm or less, more preferably 0.1 to 80 μm, still more preferably 1 to 80 μm, and particularly preferably 5 to 25 μm. If it is larger than 80 μm, the honeycomb base material becomes brittle and easily lost, and particulate matter may enter the partition walls, resulting in depth filtration. Such a partition wall having a large average pore diameter is not preferable because the particulate matter collecting performance tends to be lowered with PM collection. Moreover, it is not preferable that the average pore diameter of the partition walls is smaller than 0.1 μm because the pressure loss increases even when the particulate matter is little deposited. Furthermore, if the average pore diameter of the partition walls is smaller than 5 μm, the wall permeation resistance (resistance when exhaust gas permeates through the partition walls) when an oxidation catalyst is supported may increase. Moreover, when the average pore diameter of a partition is larger than 25 micrometers, ash (Ash) accumulates inside a partition and possibility that a collection performance will deteriorate after long-term use may become high. The average pore diameter of the partition wall is a value measured with a mercury porosimeter.

  Although the thickness of the outer peripheral wall 3 of the honeycomb base material 4 is not specifically limited, 0.5-6 mm is preferable. If it is thinner than 0.5 mm, cells near the outer periphery are likely to be chipped, and the strength may be reduced. If it is thicker than 6 mm, the pressure loss may increase.

  The shape of the honeycomb substrate (in other words, the shape of the honeycomb structure) is not particularly limited, but a cylindrical shape, an elliptical columnar shape on the bottom, a polygonal columnar shape such as a square, pentagon, hexagon, etc. on the bottom Is preferred. The honeycomb structure preferably has a column shape with the cell extending direction as the central axis direction. The size of the honeycomb substrate (in other words, honeycomb structure) is not particularly limited, but the length in the cell extending direction is preferably 76.2 to 203.2 mm. Since the length of the honeycomb substrate is in such a range, the honeycomb structure can treat the exhaust gas with excellent collection performance without increasing the pressure loss. When it is shorter than 76.2 mm, the collection performance may be deteriorated. On the other hand, if it is longer than 203.2 mm, the improvement in the collection performance cannot be expected so much, but rather the pressure loss may increase. Considering the balance between collection performance and pressure loss, the length of the honeycomb substrate is more preferably 76.2 to 203.2 mm. This is particularly effective when a plurality of honeycomb structures are arranged in series in the storage container. For example, when the outer shape of the honeycomb base material (in other words, the honeycomb structure) is cylindrical, the diameter of the bottom surface (end surface) is preferably 101.6 to 266.7 mm. The diameter of the bottom surface of the honeycomb base material is appropriately selected within the above range according to the engine displacement and output.

  The partition walls and the outer peripheral wall of the honeycomb base material are preferably composed mainly of ceramic. Specific examples of the material for the partition wall and the outer peripheral wall include silicon carbide, silicon-silicon carbide composite material, cordierite, mullite, alumina, spinel, silicon carbide-cordierite composite material, lithium aluminum silicate, and aluminum titanate. It is preferably at least one selected from the group consisting of Among these, silicon carbide having excellent thermal conductivity and cordierite having a small thermal expansion coefficient and excellent thermal shock resistance are preferable. In a normal DPF, it is necessary to increase the PM deposition amount and lengthen the regeneration interval. Therefore, a material having a large heat capacity such as silicon carbide is preferable. However, in the present invention, the heat capacity that facilitates continuous regeneration is relatively small. Cordierite is particularly preferred. The material of the partition wall and the outer peripheral wall is preferably the same, but may be different. In addition, the phrase “mainly composed of ceramic” means that 90% by mass or more of ceramic is contained.

  The depth of the plugged portions of the inlet plugged cell and the outlet plugged cell is preferably 1 to 10 mm, and more preferably 1 to 5 mm. If it is shallower than 1 mm, the strength of the plugged portion may be lowered. If it is deeper than 10 mm, the area of the partition that collects the particulate matter may be small. Here, the depth of the plugged portion means the length of the plugged portion in the cell extending direction.

  The material of the plugging portion is preferably the same as the material of the partition walls of the honeycomb substrate.

  The value obtained by subtracting the depth of the plugging portion from the length in the cell extending direction of the honeycomb structure is preferably 25 mm or more, more preferably 25 to 500 mm, and more preferably 50 to 200 mm. Particularly preferred. If it is shorter than 25 mm, the filter area may be small. Moreover, when it is longer than 500 mm, the pressure loss is high, and it is necessary to increase the cell density. However, if the cell density is increased, the collection efficiency may deteriorate. Furthermore, when the length is 25 to 50 mm, the effect of improving the collection performance by increasing the length is large, and when the length is 200 mm or more, it is difficult to obtain the effect. Therefore, when the honeycomb structure is used in the exhaust gas purification device, the exhaust gas purification device. May be disadvantageous in terms of downsizing.

  The honeycomb structure of the present embodiment may be one in which an oxidation catalyst is supported on at least a part of the partition walls. More specifically, it is preferable that the catalyst is supported on the partition walls of the honeycomb substrate constituting the honeycomb structure. The supported amount of the catalyst per unit volume is preferably 0.1 to 150 g / liter, and more preferably 10 to 80 g / liter. “G / liter” indicates the number of grams (g) of catalyst per liter of honeycomb structure. If the amount is less than 0.1 g / liter, the catalytic effect may be difficult to be exhibited. When the amount is more than 150 g / liter, the pores of the partition walls are blocked, resulting in an increase in pressure loss and a significant reduction in collection efficiency. In the case of an oxidation catalyst that forms a washcoat layer, the supported amount of catalyst per unit volume is preferably 10 to 150 g / liter. If the amount of catalyst supported is less than 10 g / liter, it may be difficult to form a washcoat layer.

  Examples of the oxidation catalyst include those containing noble metals, and specifically, those containing at least one selected from the group consisting of Pt, Rh and Pd are preferable. The total amount of the noble metal is preferably 0.1 to 5 g / liter per unit volume of the honeycomb structure.

(2) Manufacturing method of honeycomb structure:
A method for manufacturing the honeycomb structure of the present invention will be described below.

  First, a honeycomb substrate having porous partition walls is prepared. Specifically, first, the forming raw material is kneaded to form a clay. Next, the obtained clay is extruded into a honeycomb shape to obtain a honeycomb formed body.

  The forming raw material is preferably a ceramic raw material added with a dispersion medium and an additive. Examples of the additive include an organic binder, a pore former, and a surfactant. Examples of the dispersion medium include water.

  The ceramic raw material is selected from the group consisting of silicon carbide, silicon-silicon carbide based composite material, cordierite forming raw material, mullite, alumina, spinel, silicon carbide-cordierite based composite material, lithium aluminum silicate, and aluminum titanate. At least one kind is preferred. Among these, a cordierite-forming raw material having a small thermal expansion coefficient and excellent thermal shock resistance is preferable.

  Examples of the organic binder include methyl cellulose, hydroxypropoxyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, and polyvinyl alcohol. Among these, it is preferable to use methyl cellulose and hydroxypropoxyl cellulose in combination. It is preferable that content of an organic binder is 5-25 mass parts with respect to 100 mass parts of ceramic raw materials.

  The pore former is not particularly limited as long as it becomes pores after firing, and examples thereof include starch, foamed resin, water absorbent resin, silica gel and the like. The pore former content is preferably 10 to 20 parts by mass with respect to 100 parts by mass of the ceramic raw material.

  As the surfactant, ethylene glycol, dextrin, fatty acid soap, polyalcohol and the like can be used. These may be used alone or in a combination of two or more. It is preferable that content of surfactant is 3-20 mass parts with respect to 100 mass parts of ceramic raw materials.

  It is preferable that content of a dispersion medium is 10-30 mass parts with respect to 100 mass parts of ceramic raw materials.

  By adjusting the particle size and blending amount of the ceramic raw material (aggregate particles) to be used and the particle size and blending amount of the pore former to be added, a porous substrate (honeycomb substrate) having a desired porosity and average pore size Material).

  The method of kneading the forming raw material to form the kneaded material is not particularly limited, and examples thereof include a method using a kneader, a vacuum kneader or the like. Extrusion can be performed using a die having a desired cell shape, partition wall thickness, and cell density. As the material of the die, a cemented carbide which does not easily wear is preferable.

  Next, an opening of a part of cells (specifically, a cell serving as an inlet plugged cell) on one end face (inflow end face) of the obtained honeycomb formed body is plugged. Examples of the method of plugging the opening of the cell include a method of filling the opening of the cell with a plugging material. As a method of filling the plugging material, first, a mask is applied to the inflow end face of the honeycomb formed body so as to close the opening portions of the cells serving as the through cells and the cells serving as the outlet plugged cells. Here, there is no restriction | limiting in particular in how to give a mask, According to the manufacturing method of a conventionally well-known honeycomb structure, it can carry out. Also, here, first, the opening portions of the cells to be the inlet plugged cells are plugged, and then the opening portions of the cells to be the outlet plugged cells are plugged. However, there is no particular limitation on the order of plugging the cell openings.

  Separately, a slurry-like plugging material containing a ceramic raw material, water or alcohol, and an organic binder is stored in a storage container. The ceramic raw material is preferably the same as the ceramic raw material used as the raw material for the honeycomb formed body. The ceramic raw material is preferably 68 to 90% by mass of the whole plugging material. Moreover, it is preferable that water or alcohol is 8-30 mass% of the whole plugging material, and it is preferable that an organic binder is 0.1-2.0 mass% of the whole plugging material. Examples of the organic binder include hydroxypropoxyl methylcellulose and methylcellulose.

  Then, the end portion on which the mask is applied is immersed in a storage container, and a plugging material is filled into the opening of the cell where the mask is not applied to form a plugged portion. The plugging material preferably has a viscosity of 600 to 1200 Pa · s. In addition, the viscosity of the plugging material is a value measured at a rotation speed of 30 rpm with a rotary viscometer at a temperature of 30 ° C.

  Next, the openings of some other cells on the other end face (outflow end face) of the honeycomb formed body are plugged. Specifically, a mask is applied to the outflow end face of the honeycomb formed body so as to close the openings of the cells to be the through cells and the cells to be the inlet plugged cells. Then, the plugging material is filled in the opening of the cell to be the outlet plugged cell by the same method as described above.

  Next, the honeycomb formed body in which the opening portions of the cells are filled with the plugging material is fired. The firing temperature can be appropriately determined depending on the material of the honeycomb formed body. For example, when the material of the honeycomb formed body is cordierite, the firing temperature is preferably 1380 to 1450 ° C, and more preferably 1400 to 1440 ° C. The firing time is preferably about 3 to 10 hours.

  The honeycomb formed body may be dried before firing. The drying method is not particularly limited, and examples thereof include hot air drying, microwave drying, dielectric drying, reduced pressure drying, vacuum drying, freeze drying, etc. Among these, dielectric drying, microwave drying Or it is preferable to perform hot-air drying individually or in combination. The drying conditions are preferably a drying temperature of 30 to 150 ° C. and a drying time of 1 minute to 2 hours.

  Further, before forming the plugged portions in the honeycomb formed body, the honeycomb formed body is fired to obtain a honeycomb fired body, and the cells serving as the inlet plugged cells and the outlet plugged cells of the obtained honeycomb fired body After the plugging portion is formed in the opening of the cell to be, it may be further baked. As described above, the honeycomb structure of the present embodiment can be manufactured.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples.

Example 1
(Honeycomb structure)
First, 13 parts by mass of a pore former, 35 parts by mass of a dispersion medium, 6 parts by mass of an organic binder, and 0.5 parts by mass of a dispersant are added to 100 parts by mass of a cordierite forming raw material, and mixed and kneaded. A clay was prepared. As the cordierite forming raw material, alumina, aluminum hydroxide, kaolin, talc, and silica were used. Water was used as the dispersion medium, coke having an average particle diameter of 1 to 10 μm was used as the pore former, hydroxypropylmethylcellulose was used as the organic binder, and ethylene glycol was used as the dispersant. By controlling the particle diameter and amount of the pore former, the pore diameter and porosity of the partition walls were controlled.

  Next, the kneaded material was extruded using a predetermined mold to obtain a honeycomb formed body having a square cell shape and a columnar overall shape.

  Next, the honeycomb formed body was dried with a microwave dryer and further completely dried with a hot air dryer, and then both end faces of the honeycomb formed body were cut and adjusted to a predetermined size.

  Next, a mask is applied to the inflow end face of the honeycomb molded body so as to close the opening of the cell serving as the through cell and the outlet plugged cell, and the end on the inflow end face side where the mask is applied is cordierite. It was immersed in the plugging slurry containing the chemical conversion raw material. Thereby, the plugging slurry was filled in the end portion on the inflow end face side of the cell to be the inlet plugged cell. Next, a mask is applied to the outflow end face of the honeycomb formed body so as to close the opening of the cell serving as the through cell and the inlet plugged cell, and the end on the outflow end face side where the mask is applied is cordierite. It was immersed in the plugging slurry containing the chemical conversion raw material. Thereby, the plugging slurry was filled in the end portion on the outflow end face side of the cell to be the outlet plugged cell.

  In Example 1, the plugging slurry is applied to the cell opening so that the ratio of the through-cells is 50%, the ratio of the specific through-cells is 75%, and the ratio of the inlet plugged cells is 85%. Filled.

  Next, the honeycomb formed body on which the plugged portions were formed was dried with a hot air dryer, and further fired at 1410 to 1440 ° C. for 5 hours. In this way, a honeycomb structure including a honeycomb base material in which a plurality of cells were defined by the porous partition walls 1 was obtained. In this honeycomb structure, a plurality of cells are constituted by three types of cells, a through cell, an inlet plugged cell, and an outlet plugged cell.

The honeycomb substrate of the obtained honeycomb structure had a cylindrical shape with a cross-sectional diameter of 143.8 mm perpendicular to the central axis and a length of 152.4 mm in the central axis direction. The partition wall thickness was 305 μm, and the cell density was 46.5 cells / cm ² . The shape of the cell was a square. The material of the honeycomb substrate was cordierite. The porosity of the partition walls was 50%, and the average pore diameter of the partition walls was 20 μm. The porosity and average pore diameter of the partition walls are values measured by a mercury porosimeter (trade name: Autopore 9500, manufactured by Micromeritics). Table 1 shows the honeycomb substrate material, partition wall thickness (mm), cell density (cell / cm ² ), honeycomb substrate diameter (mm) and length (mm), porosity (%), average fineness. The pore diameter (μm) is shown.

  In the honeycomb structure of Example 1, the ratio of the through cells was 50%, the ratio of the specific through cells was 75%, and the ratio of the inlet plugged cells was 85%. Table 2 shows the ratio (%) of the penetrating cell, the ratio (%) of the specific penetrating cell, and the ratio (%) of the inlet plugged cell. In addition, in the column “Presence / absence of specific through-cells” in Table 2, the presence / absence of through-holes (that is, specific through-cells) sharing a partition wall with both the inlet plugged cells and the outlet plugged cells is shown. In the case of having a specific through cell, “Yes” is written in the “Presence / absence of specific through cell” column. When there is no specific through cell, “None” is written in the “Presence of specific through cell” column.

  About the obtained honeycomb structure, “the collection efficiency (%)”, “the soot accumulation amount per unit volume (g / L) of the honeycomb structure at the time of crack generation during regeneration”, and “Pressure loss (kPa)” was measured. The obtained honeycomb structure was subjected to “blow-off test” and “durability evaluation” by the following methods. The results are shown in Table 3.

(Collection efficiency)
Soot is generated using a burner that uses light oil as fuel. A predetermined amount of air is mixed with the combustion gas so that the flow rate of the entire gas is 1.5 Nm ³ / min, and the obtained mixed gas is introduced into the honeycomb structure. The temperature of the mixed gas is 200 ° C. The test time is 120 minutes. Sampling was performed after the test. The concentration of the particulate matter in the mixed gas is set to 4 g / hour. The exhaust gas is sampled for about 2 minutes by a vacuum pump from sampling pipes provided on the upstream side and downstream side of the honeycomb structure. Then, when sampling the exhaust gas, PM is collected on the filter paper by passing the exhaust gas through a holder in which the filter paper is set. In addition, the mass of the filter paper is measured in advance. The mass of PM in the exhaust gas sampled from the upstream side of the honeycomb structure (the mass of PM collected on the filter paper) and the mass of PM in the exhaust gas sampled from the downstream side of the honeycomb structure (collected on the filter paper) From the PM mass, the collection efficiency (%) is calculated. Specifically, the collection efficiency (%) is obtained by the following formula (1). When the collection efficiency is 40% or more, the honeycomb structure can be favorably used as a filter for collecting particulate matter in the exhaust gas.
Collection efficiency (%) = {(PM mass A−PM mass B) / PM mass A} × 100 (1)
(However, in the above formula (1), “PM mass A” represents the mass (g) of PM collected on the filter paper from the upstream side of the honeycomb structure. “PM mass B” represents the honeycomb structure. (The mass (g) of PM collected on the filter paper from the downstream side is shown.)

(Crack generation amount during regeneration)
Exhaust gas discharged from a diesel engine (3.0 liters, direct injection common rail, inline 6 cylinder) is caused to flow into the honeycomb structure, and a predetermined amount of soot is collected by the partition walls of the honeycomb structure. Thereafter, the fuel injection amount is increased from post-injection with the engine speed of 1700 rpm and the engine torque of 86 Nm, the exhaust gas temperature is raised, and the collected soot is combusted. In this way, the honeycomb structure in which the soot is collected is regenerated by burning the soot. The temperature of the exhaust gas flowing into the honeycomb structure is 600 ° C. The amount of soot collected by the partition walls of the honeycomb structure is increased stepwise by 0.1 g / L (by mass per unit volume of the honeycomb structure), and cracks are generated in the honeycomb structure. Until then, regeneration of the honeycomb structure is repeated. The amount (g) of soot per unit volume (1 L) of the honeycomb structure when cracks occur in the honeycomb structure is defined as “crack generation soot accumulation amount (g / L) during regeneration”. Whether or not a crack has occurred is visually confirmed. When the crack generation soot accumulation amount during regeneration is 5.0 g / L or more, the honeycomb structure can be favorably used as a filter for collecting particulate matter in the exhaust gas.

(Pressure loss)
The exhaust gas discharged from the diesel engine (3.0 liters, direct injection common rail, in-line 6 cylinders) is caused to flow into the honeycomb structure so that the amount of soot accumulated is 4 g / L. To collect cocoons. Then, with the soot accumulation amount of 4 g / L, 200 ° C. engine exhaust gas was introduced at a flow rate of 3.0 Nm ³ / min to measure the pressure on the inflow end face side and the outflow end face side of the honeycomb structure. And the pressure loss (kPa) was calculated | required by calculating the pressure difference. When the pressure loss is 5.6 kPa or less, the honeycomb structure can be favorably used as a filter for collecting particulate matter in the exhaust gas.

(Blow-off test)
Exhaust gas discharged from a diesel engine (3.0 liters, direct injection common rail, in-line 6 cylinders) is caused to flow into the honeycomb structure to deposit 10.0 g / L of soot on the honeycomb structure. Next, an idling operation was performed after the engine was started, and after 5 seconds, the engine was operated for 2 minutes at a rotation speed of 2000 rpm and a torque of 178 N · m. After the start of operation, the amount of soot per 1 m ³ in the exhaust gas discharged from the outflow end face of the honeycomb structure is measured by a soot sensor manufactured by AVL. The maximum value measured by the soot sensor is taken as the blow-off amount (mg / m ³ ). When the amount of blow-off is less than 1000 mg / m ³ , no blow-off occurs and the blow-off test is passed. When the blow-off test is acceptable, “OK” is written in the “Blow-off test” column of Table 3. On the other hand, when the amount of blow-off is 1000 mg / m ³ or more, it is assumed that blow-off has occurred, and the blow-off test is rejected. If the blow-off test fails, “NG” is written in the “Blow-off test” column of Table 3.

(Durability evaluation)
After exhaust gas discharged from a diesel engine (3.0 liter, direct injection common rail, inline 6 cylinder) flows into the honeycomb structure, 10.0 g / L of soot is deposited in the honeycomb structure, and then the diesel engine ( The honeycomb structure is installed in the exhaust system of 3.0 liters, direct injection common rail, in-line 6 cylinders). Durability was evaluated by a forced regeneration test in which the engine was operated at an engine speed of 2000 rpm and a torque of 178 N · m and the exhaust gas temperature reached 600 ° C. and then dropped to idle. After the test, the presence or absence of cracks was confirmed visually, and if no cracks were observed, the durability evaluation was passed, and “OK” was entered in the column of “Durability Evaluation” in Table 3. On the other hand, when a crack is observed, the durability evaluation is rejected, and “NG” is written in the column of “Durability Evaluation” in Table 3.

(Examples 2 to 23, Comparative Examples 1 to 8)
The composition of the honeycomb substrate was changed as shown in Table 1, and the ratio of the through cells (%), the ratio of the specific through cells (%), and the ratio of the inlet plugged cells (%) are shown in Table 2. A honeycomb structure was manufactured in the same manner as in Example 1 except that the above was changed. In Example 22, the material of the honeycomb substrate was silicon carbide. In Example 23, the material of the honeycomb substrate was aluminum nitride.

  With respect to the honeycomb structures of Examples 1 to 23 and Comparative Examples 1 to 8, in the same manner as in Example 1, “capturing efficiency (%)” and “crack generation soot accumulation amount during regeneration (g / L) ) ”And“ pressure loss (kPa) ”. Further, with respect to the obtained honeycomb structure, “blow-off test” and “durability evaluation” were performed in the same manner as in Example 1. The results are shown in Table 3.

(result)
As shown in Table 3, the honeycomb structures of Examples 1 to 23 have a collection efficiency of 40% or more, and can be favorably used as a filter for collecting particulate matter in exhaust gas. It was. In addition, the honeycomb structures of Examples 1 to 23 have a large amount of crack generation soot accumulation during regeneration (the honeycomb structures of Examples 1 to 23 are 5 g / L or more), and particulate matter in the exhaust gas is not contained. It was able to collect well. In particular, since the honeycomb structures of Examples 1 to 23 have a large amount of crack generation soot accumulation during regeneration, the regeneration interval can be lengthened. Further, the honeycomb structures of Examples 1 to 23 had a pressure loss of 5.6 kPa or less when the accumulation amount of soot was 4 g / L, and even when a predetermined amount of soot was deposited on the partition wall, The pressure loss was low. Furthermore, the honeycomb structures of Examples 1 to 23 were able to obtain good results both in the blow-off test and the durability evaluation.

  The honeycomb structures of Comparative Examples 1 and 2 had a very high pressure loss when the amount of soot deposited was 4 g / L because the ratio of the penetrating cells was 30%. That is, it was found that when the ratio of the through-cells is about 30%, the pressure loss becomes too high to use the honeycomb structure as a filter for collecting particulate matter in the exhaust gas.

  The honeycomb structures of Comparative Examples 3 and 4 had a low collection efficiency because the percentage of penetrating cells was 70%. Further, the honeycomb structures of Comparative Examples 3 and 4 also failed the blow-off test. Further, since the honeycomb structure of Comparative Example 4 has a small amount of crack generation soot accumulation during regeneration, cracks may occur when regeneration is performed with a large amount of soot accumulation.

  Since the honeycomb structure of Comparative Example 5 had a porosity of 30%, the pressure loss was very high when the amount of soot deposited was 4 g / L. The honeycomb structure of Comparative Example 6 had a porosity of 70%, so the collection efficiency was low, and the amount of crack generation soot accumulated during regeneration was small. The honeycomb structure of Comparative Example 6 also failed in the blow-off test and durability evaluation.

  The honeycomb structure of Comparative Example 7 had a low collection efficiency because the ratio of the specific penetrating cells was 65%. Moreover, the honeycomb structure of Comparative Example 7 also failed the blow-off test. In the honeycomb structure of Comparative Example 7, the ratio of the inlet plugged cells was also out of 60 to 85%.

  The honeycomb structure of Comparative Example 8 had a low collection efficiency because the ratio of the inlet plugged cells was 50%, and had a large amount of crack generation soot accumulation during regeneration. Further, the honeycomb structure of Comparative Example 8 also failed in the durability evaluation.

  The honeycomb structure of the present invention can be used as a filter for purifying exhaust gas.

1: partition wall, 2: cell, 2a: penetration cell, 2aa: specific penetration cell, 2b: inlet plugging cell, 2c: outlet plugging cell, 3: outer peripheral wall, 4: honeycomb substrate, 5: plugging Stop portion, 11: Inflow end surface, 12: Outflow end surface, 13: Particulate matter, 100, 800: Honeycomb structure, 801: Partition wall, 802: Cell, 802a: Through cell, 802b: Inlet plugged cell, 803: Outer peripheral wall, 804: honeycomb substrate, 805: plugging portion, 813: particulate matter, G: exhaust gas.

Claims (3)

A honeycomb base material having a porous partition wall that forms a plurality of cells serving as fluid flow paths extending from an inflow end surface that is an end surface on the exhaust gas inflow side to an outflow end surface that is an end surface on the exhaust gas outflow side. ,
The partition wall has a porosity of 35 to 65%;
The cell substantially penetrates from the inflow end surface side to the outflow end surface side, and the end of the cell is substantially plugged by the plugging portion on the inflow end surface side of the honeycomb substrate. An inlet plugged cell, and an outlet plugged cell in which an end of the cell is substantially blocked by a plugged portion on the outflow end face side of the honeycomb substrate,
The number of penetrating cells is 40-60% of the number of all the cells,
The number of the inlet plugged cells is 60 to 85% with respect to the total number of the inlet plugged cells and the outlet plugged cells,
The penetrating cell includes at least one inlet plugged cell and at least one outlet plugged cell and the specific penetrating cell disposed adjacent to the partition wall,
A honeycomb structure, wherein the number of the specific through cells is 70% or more with respect to the number of all the through cells.   The honeycomb structure according to claim 1, wherein the partition wall has a thickness of 120 to 460 µm. The cell density of the honeycomb substrate is 15 to 100 cells / cm ^2, the honeycomb structure according to claim 1 or 2.

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