CN219672708U

CN219672708U - Honeycomb filter

Info

Publication number: CN219672708U
Application number: CN202320130797.1U
Authority: CN
Inventors: 中谷隆彦
Original assignee: NGK Insulators Ltd
Current assignee: NGK Insulators Ltd
Priority date: 2023-01-17
Filing date: 2023-01-17
Publication date: 2023-09-12
Anticipated expiration: 2033-01-17
Also published as: CN220227005U

Abstract

The utility model provides a honeycomb filter which has excellent ignition performance, low pressure loss and excellent erosion resistance and thermal shock resistance. The honeycomb filter includes: a columnar honeycomb structure (4) having porous partition walls (1) arranged so as to surround a plurality of cells (2); and a porous sealing part (5) which is arranged at any end of the cells, wherein the cells are shaped in such a manner that corners (21) of the polygon are chamfered into an arc shape with a radius of curvature R of 10-100 [ mu ] m in a cross section orthogonal to the direction in which the cells extend, the honeycomb structure comprises a central part (15) including a center of gravity O of the cross section and an outer peripheral part (16) positioned outside the central part in a cross section orthogonal to the direction in which the cells extend, the thickness T1 of the partition wall in the central part is configured to be 0.0127-0.0381 mm thicker than the thickness T2 of the partition wall in the outer peripheral part, and the area ratio of the central part in the cross section is 10-50%.

Description

Honeycomb filter

Technical Field

The present utility model relates to a honeycomb filter. More specifically, the present utility model relates to a honeycomb filter which exhibits excellent temperature characteristics (Light-off performance) and has low pressure loss and excellent erosion resistance and thermal shock resistance, which are exhibited by the purification performance of an exhaust gas purification catalyst.

Background

Conventionally, as a filter for trapping particulate matter in exhaust gas discharged from an internal combustion engine such as an engine of an automobile or a device for purifying toxic gas components such as CO, HC, NOx, a honeycomb filter using a honeycomb structure has been known (refer to patent document 1). The honeycomb structure has partition walls made of porous ceramics such as cordierite, and a plurality of cells are partitioned by the partition walls. In the honeycomb filter, the honeycomb structure is provided with plugged portions so that openings on the inflow end face side and openings on the outflow end face side of the cells are alternately plugged. That is, the honeycomb filter has the structure: the inflow cells whose inflow end face side is open and whose outflow end face side is sealed and the outflow cells whose inflow end face side is sealed and whose outflow end face side is open are alternately arranged with the partition walls interposed therebetween. In the honeycomb filter, porous partition walls play a role in filtering particulate matter in exhaust gas. Hereinafter, particulate matter contained in the exhaust gas may be referred to as "PM". "PM" is an abbreviation for "particulate matter".

The purification of exhaust gas by the honeycomb filter is performed as follows. First, the honeycomb filter is configured to: the inflow end face side thereof is located on the upstream side of the exhaust system from which the exhaust gas is discharged. The exhaust gas flows into the cells from the inflow end face side of the honeycomb filter. Then, the exhaust gas flowing into the inflow cells passes through the porous partition walls, flows into the outflow cells, and is discharged from the outflow end face of the honeycomb filter. PM and the like in the exhaust gas are trapped and removed when passing through the porous partition walls. Further, such a honeycomb filter may be loaded with an oxidation catalyst for promoting PM oxidation (combustion), an exhaust gas purifying catalyst for purifying harmful components such as NOx, and the like.

Conventionally, in a honeycomb structure for a honeycomb filter, a certain roundness (i.e., a curve shape) is provided at the intersection of partition walls that partition cells to ensure manufacturability and performance (for example, patent document 1). By providing the intersection portions of the partition walls with a certain roundness in this manner, for example, in a cross section of the honeycomb structure orthogonal to the direction in which the cells extend, the cells are shaped as polygons in which the corners of the polygons are rounded.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 10-264125

Disclosure of Invention

However, the technique of providing the roundness (R) of the intersection portion of the partition walls as described above has a problem that the mass of the honeycomb structure becomes large, and when the catalyst for purifying exhaust gas is supported on the honeycomb filter, the mass of the honeycomb structure increases, thereby preventing early activation of the catalyst. That is, there is a problem that the temperature characteristic, i.e., light-off performance (Light-off performance) exhibited by the purification performance of the exhaust gas purification catalyst cannot be ensured due to the increase in mass of the honeycomb structure. If the light-off performance is poor, the purification performance of the catalyst-supporting honeycomb filter becomes poor at the initial stage such as when the engine is started.

In addition, in the case where the roundness (R) of the intersection portion of the partition walls is provided, since the corner portions of the cells are rounded, there is a problem in that the Capacity (Capacity) of PM deposited in the cells is reduced when PM such as soot and Ash (Ash) in the exhaust gas is collected by the porous partition walls.

Further, since the air flow of the honeycomb filter is designed to be concentrated on the center portion of the cross section of the honeycomb filter orthogonal to the flow direction, the air flow of the honeycomb filter flows in the center portion of the honeycomb filter at a high temperature, and thus the air flow is likely to receive thermal shock and erosion (erosion) by foreign substances. Here, "erosion" means: the honeycomb structure, the hole sealing portion, and the like on the inflow end face side are worn out and removed by foreign matter accompanying the exhaust gas flow.

The present utility model has been made in view of the above-described problems of the prior art. According to the present utility model, there is provided a honeycomb filter excellent in light-off performance, low in pressure loss, and excellent in erosion resistance and thermal shock resistance.

According to the present utility model, there is provided a honeycomb filter shown below.

[1] A honeycomb filter is provided with:

a columnar honeycomb structure having porous partition walls arranged to surround a plurality of cells forming fluid flow paths extending from an inflow end face to an outflow end face; and

a porous sealing portion disposed at either one of an end portion on the inflow end face side and an end portion on the outflow end face side of the cell,

in a cross section orthogonal to the direction in which the cells extend, the cells are formed by chamfering corners of a polygon into an arc shape having a radius of curvature R of 10 to 100 μm,

the honeycomb structure includes, in the cross section orthogonal to the direction in which the cells extend, a central portion including a center of gravity O of the cross section and an outer peripheral portion located outside the central portion,

the thickness T1 of the partition wall in the central portion is 0.0127 to 0.0381mm thicker than the thickness T2 of the partition wall in the outer peripheral portion,

the area of the central portion is 10 to 50% of the total area of the cross section of the honeycomb structure.

[2] The honeycomb filter according to the above [1], wherein the porosity of the partition walls is 40 to 80%, and the average pore diameter of the partition walls is 5 to 21. Mu.m.

[3]According to [1]]Or [2]]The thickness T1 of the partition walls in the central portion and the thickness T2 of the partition walls in the peripheral portion of the honeycomb filter are 0.127 to 0.331mm, and the cell density of the honeycomb structure is 31.0 to 62.0 cells/cm ² 。

[4] The honeycomb filter according to [1] or [2], wherein the thickness T1 of the partition walls in the central portion is formed to be 0.0127 to 0.0254mm thicker than the thickness T2 of the partition walls in the outer peripheral portion,

the area of the central portion is 30 to 50% of the total area of the cross section of the honeycomb structure.

Effects of the utility model

The honeycomb filter of the present utility model exhibits the following effects, i.e., excellent light-off performance, low pressure loss, and excellent erosion resistance and thermal shock resistance.

Drawings

Fig. 1 is a perspective view schematically showing an embodiment of the honeycomb filter of the present utility model.

Fig. 2 is a plan view showing the inflow end face side of the honeycomb filter shown in fig. 1.

Fig. 3 is a sectional view schematically showing a section A-A' of fig. 2.

Fig. 4 is an enlarged plan view of the range enclosed by the dotted line indicated by P in fig. 2.

Description of the reference numerals

1: partition wall, 1a: central partition wall, 1b: peripheral partition wall, 2: compartment, 2a: inflow compartment, 2b: outflow compartment, 3: peripheral wall, 4: honeycomb structure, 5: hole sealing portion, 11: inflow end face, 12: outflow end face, 15: center portion, 16: outer peripheral portion, 21: corner, 100: honeycomb filter, T1: thickness (thickness of central partition wall), T2: (thickness of peripheral partition wall).

Detailed Description

Hereinafter, embodiments of the present utility model will be described, but the present utility model is not limited to the following embodiments. Thus, it should be understood that: the following embodiments are appropriately modified and improved based on the general knowledge of those skilled in the art within the scope of the present utility model without departing from the gist of the present utility model.

(1) Honeycomb filter:

one embodiment of the honeycomb filter of the present utility model is a honeycomb filter 100 as shown in fig. 1-4. Here, fig. 1 is a perspective view schematically showing an embodiment of the honeycomb filter of the present utility model. Fig. 2 is a plan view showing the inflow end face side of the honeycomb filter shown in fig. 1. Fig. 3 is a sectional view schematically showing a section A-A' of fig. 2. Fig. 4 is an enlarged plan view of the range enclosed by the dotted line indicated by P in fig. 2.

As shown in fig. 1 to 4, the honeycomb filter 100 of the present embodiment includes a honeycomb structure 4 and a plugged portion 5. The honeycomb structure 4 has a columnar shape and includes porous partition walls 1 arranged to surround a plurality of cells 2, and the plurality of cells 2 form fluid flow paths extending from an inflow end face 11 to an outflow end face 12. In the honeycomb filter 100, the honeycomb structure 4 has a columnar shape and has an outer peripheral wall 3 on its outer peripheral side surface. That is, the outer peripheral wall 3 is disposed so as to surround the partition walls 1 disposed in a lattice shape.

The hole sealing portion 5 is disposed in an opening portion of each cell 2 on the inflow end face 11 side or the outflow end face 12 side. In the honeycomb filter 100 shown in fig. 1 to 4, the plugging portions 5 are disposed in the openings of the end portions of the predetermined cells 2 on the inflow end face 11 side and the openings of the end portions of the remaining cells 2 on the outflow end face 12 side, respectively. The compartment 2 in which the hole sealing portion 5 is disposed in the opening portion on the outflow end face 12 side and the inflow end face 11 side is opened is referred to as an inflow compartment 2a. The compartment 2 in which the hole sealing portion 5 is disposed in the opening portion on the inflow end face 11 side and the outflow end face 12 side is opened is referred to as an outflow compartment 2b. The inflow cells 2a and the outflow cells 2b are preferably alternately arranged with the partition wall 1 interposed therebetween. It is preferable that both end surfaces of the honeycomb filter 100 are formed in a checkered pattern by the hole sealing portions 5 and the "openings of the cells 2".

The honeycomb structural body 4 includes, in a cross section orthogonal to the direction in which the cells 2 extend, a central portion 15 including the center of gravity O of the cross section, and an outer peripheral portion 16 located outside the central portion 15. For example, as shown in fig. 2 and 3, a certain range from the center of gravity O to the outer periphery of the honeycomb structure 4 including the center of gravity O is "central portion 15", and a range on the outer periphery side of the central portion 15 is "outer periphery 16".

The honeycomb filter 100 of the present embodiment has particularly main characteristics in terms of the structure of the partition walls 1 in the central portion 15 and the outer peripheral portion 16 and the structure of the cells 2 surrounded by the partition walls 1. That is, first, the honeycomb filter 100 is configured to: in a cross section of the honeycomb structure 4 perpendicular to the direction in which the cells 2 extend, the cells 2 have a shape in which corners of a polygon are chamfered into circular arcs having a radius of curvature R of 10 to 100 μm. In fig. 4, reference numeral 21 denotes a corner 21 formed in a curve in the shape of the compartment 2 in a cross section orthogonal to the direction in which the compartment 2 extends. Hereinafter, the shape of the cells 2 in a cross section of the honeycomb structure 4 perpendicular to the direction in which the cells 2 extend may be referred to simply as "the shape of the cells 2". The honeycomb filter 100 of the present embodiment is configured as follows: the radius of curvature R of the corners, which is 50% or more of the total number of corners of the polygonal cells 2 as described above, is 10 to 100 μm.

The shape of the cells 2 is not particularly limited as long as the corners of the polygon are formed in a curved shape having the radius of curvature R. As described later, examples of the original polygon of the shape of the cell 2 include: quadrilateral, hexagonal, octagonal, etc. Hereinafter, the corner 21 of the compartment 2 formed in a curve may be referred to as "corner 21 of the compartment 2". The radius of curvature R of the curved portion of the corner 21 of the cell 2 is sometimes referred to simply as "radius of curvature R of the corner 21 of the cell 2". In the present specification, unless otherwise specified, the unit of the radius of curvature R of the corner 21 of the cell 2 is "μm".

The radius of curvature R of the corner 21 formed in a curve in each cell 2 can be measured as follows. First, the inflow end face 11 and the outflow end face 12 of the honeycomb filter 100 are photographed by an image measuring device. Then, the captured images of the inflow end face 11 and the outflow end face 12 are subjected to image analysis, whereby the radius of curvature R of the corner 21 of the cell 2 can be obtained. As a method of image analysis, for example, "VM-2520 (trade name)" manufactured by Nikon corporation may be used. By using the image analysis, the radius (or diameter) of the inscribed circle of the corner 21 of the cell 2 is obtained by curve fitting to the corner 21 of the cell 2, and the radius of curvature R of the corner 21 of the cell 2 can be obtained. In the honeycomb filter 100 of the present embodiment, the radius of curvature R of all the corners 21 of all the cells 2 is obtained in this way, and 50% or more of the corners 21, that is, 50 to 100% of the corners 21 have a radius of curvature R in the range of 10 to 100 μm.

Further, the honeycomb filter 100 is configured to: the thickness T1 of the partition wall in the central portion 15 is 0.0127 to 0.0381mm thicker than the thickness T2 of the partition wall in the outer peripheral portion 16. In the honeycomb filter 100, the ratio of the area of the central portion 15 to the total area of the cross section of the honeycomb structure 4 is 10 to 50%. Here, "center of gravity O" of the cross section of the honeycomb structural body 4 means: the geometric center of gravity (in other words, the geometric center) of the cross-section.

The honeycomb filter 100 of the present embodiment configured as described above is excellent in light-off performance, and can realize low pressure loss, excellent erosion resistance, and thermal shock resistance. That is, as described above, the honeycomb filter 100 according to the present embodiment is configured such that the corners 21 of the cells 2 have a circular arc shape with a predetermined radius of curvature R, and thus, it is expected that manufacturability and various performance improvements due to the circular arc-shaped corners 21 are improved. On the other hand, in the conventional honeycomb filter in which the corners 21 of the cells 2 are formed in the shape of circular arc, the thickness of the partition walls 1 is not distributed in the circumferential direction of the cross section of the honeycomb structure 4, and the thickness of the partition walls 1 is constant in the circumferential direction. In the honeycomb filter 100 of the present embodiment, the thickness T1 of the partition wall 1 in the central portion 15 is made 0.0127 to 0.0381mm thicker than the thickness T2 of the partition wall in the outer peripheral portion 16, so that the honeycomb filter 100 is made lightweight, and thus the light-off performance is excellent. For example, when the catalyst for purifying exhaust gas is supported on the honeycomb filter 100 of the present embodiment, the catalyst is activated early, and excellent purification performance can be achieved even at the initial stage such as at the time of engine start.

In the honeycomb filter 100 of the present embodiment, the thickness T2 of the partition walls 1 in the outer peripheral portion 16 is relatively reduced, so that the aperture ratio of the cells 2 in the honeycomb filter 100 is increased, and a low pressure loss can be achieved. Further, by making the thickness T1 of the partition wall 1 in the central portion 15 susceptible to thermal shock and erosion by foreign matter relatively thick, excellent erosion resistance and thermal shock resistance can be achieved. If the area ratio of the central portion 15 is less than 10%, the effect of improving the erosion resistance and the thermal shock resistance of the central portion 15 may be insufficient. On the other hand, if the area ratio of the central portion 15 exceeds 50%, the effect of reducing the pressure loss may be insufficient.

The radius of curvature R of the corners 21 of the cells 2 is 10 to 100 μm. If the radius of curvature R is less than 10 μm, there is a case where optimization of erosion resistance and thermal shock resistance due to the corner 21 of the cell 2 being formed in a curve cannot be sufficiently exhibited. On the other hand, if the radius of curvature R exceeds 100 μm, the increase in mass due to the corner 21 of the cell 2 being formed in a curve is excessive, resulting in a decrease in light-off performance and a deterioration in pressure loss. The radius of curvature R of the corner 21 of the cell 2 is not particularly limited, and is preferably 20 to 90 μm, more preferably 40 to 80 μm, for example.

As described above, the thickness T1 of the partition wall 1 in the central portion 15 is 0.0127 to 0.0381mm thicker than the thickness T2 of the partition wall in the outer peripheral portion 16. Hereinafter, the partition wall 1 in the central portion 15 may be referred to as a "central partition wall 1a". The partition wall 1 in the outer peripheral portion 16 is sometimes referred to as "outer Zhou Gebi 1b". For example, a scanning electron microscope or a microscope (microscope) may be used to measure the thickness T1 of the center partition wall 1a and the thickness T2 of the outer peripheral partition wall 1 b. The thickness T1 of the center partition wall 1a is preferably a substantially constant thickness in the center portion 15. The thickness T2 of the outer peripheral wall 1b is preferably substantially constant in the outer peripheral portion 16. For example, the thickness T1 of the center partition wall 1a is preferably within ±0.0127mm in the center portion 15. The thickness T2 of the outer peripheral wall 1b is preferably within ±0.0127mm in the outer peripheral portion 16. In a cross section of the honeycomb structure 4 perpendicular to the direction in which the cells 2 extend, a measurement point is determined in a cross direction starting from the center of gravity O of the cross section, and the thickness T1 of the center partition wall 1a and the thickness T2 of the outer peripheral partition wall 1b are measured. More specifically, in the cross direction of the cross section, 10 measurement points are specified for each direction at a position of the area ratio of the cross section of 10%, and the thicknesses T1 and T2 of the partition wall 1 at each measurement point are measured.

If the increase in the thickness T1 of the center bulkhead 1a relative to the thickness T2 of the outer peripheral bulkhead 1b is less than 0.0127mm, insufficient effects of improving the erosion resistance and the thermal shock resistance may occur. Conversely, even if the thickness T1 of the center bulkhead 1a exceeds 0.0381mm relative to the thickness T2 of the outer peripheral bulkhead 1b, there is a case where the pressure loss increases. Although not particularly limited, the thickness T1 of the center partition wall 1a is preferably 0.0127 to 0.0381mm, more preferably 0.0127 to 0.0254mm, thicker than the thickness T2 of the outer peripheral partition wall 1 b.

The specific value of the thickness T1 of the center partition wall 1a and the thickness T2 of the outer peripheral partition wall 1b is not particularly limited. For example, the thickness T1 of the center partition wall 1a and the thickness T2 of the outer peripheral partition wall 1b are preferably 0.203 to 0.343mm. More specifically, the thickness T1 of the center partition wall 1a, which is relatively thick, of the partition wall 1 is more preferably 0.216 to 0.343mm. On the other hand, the thickness T2 of the outer peripheral partition wall 1b, which is relatively thin in the thickness of the partition wall 1, is more preferably 0.203 to 0.305mm. If the thickness T1 of the center partition wall 1a is too small, the trapping performance of the honeycomb filter 100 may be lowered, and the mechanical strength of the honeycomb filter 100 may be lowered. On the other hand, if the thickness T1 of the center bulkhead 1a is too large, the pressure loss may increase.

The central portion 15 is a constant range from the center of gravity O of the cross section of the honeycomb structure 4 to the outer periphery of the cross section, and is a range in which the thickness of the partition wall 1 (i.e., the thickness T1 of the central partition wall 1 a) is relatively thick. The ratio of the area of the central portion 15 to the total area of the cross section of the honeycomb structure 4 is not particularly limited, but is, for example, preferably 10 to 50%, more preferably 30 to 50%. If the area ratio of the central portion 15 is less than 10%, the effect of improving the erosion resistance and the thermal shock resistance of the central portion 15 may be insufficient. On the other hand, if the area ratio of the central portion 15 exceeds 50%, the pressure loss may increase. For example, in the honeycomb filter 100 of the present embodiment, more preferably: the thickness T1 of the central partition wall 1a is 0.0127-0.0254 mm thicker than the thickness T2 of the peripheral partition wall 1b, and the area ratio of the central portion 15 is 30-50%. The area ratio of the central portion 15 is measured as follows. First, as described above, the thicknesses T1 and T2 of the partition walls 1 are measured at each measurement point in the cross direction of the cross section of the honeycomb structure 4. Since the measurement point is 10 parts per 10% of the area ratio of the cross section in the cross direction, the average value of the thicknesses of the partition walls 1 from the outer periphery of the honeycomb structure 4 to the 5 th part (i.e., the part having the area ratio of 50%) is determined as the "reference thickness". Then, a point at which the difference from the reference thickness exceeds 0.0127mm for the first time is defined as a boundary between the central portion 15 and the outer peripheral portion 16, and the area of the central portion 15, which is a range inside the boundary, is obtained. The percentage of the ratio of the area of the central portion 15 to the cross-sectional area of the honeycomb structural body 4 is "area ratio (%) of the central portion 15".

The porosity of the partition wall 1 is preferably 40 to 80%, more preferably 40 to 70%, and particularly preferably 45 to 65%. With such a configuration, the honeycomb filter 100 can be suitably used as a filter for purifying exhaust gas discharged from an engine of an automobile. The porosity of the partition wall 1 is a value measured by mercury porosimetry. For example, the porosity of the partition wall 1 can be measured by using Autopore 9500 (trade name) manufactured by Micromeritics corporation. A part of the partition wall 1 may be cut out from the honeycomb structure 4 to prepare a sample sheet, and the porosity of the partition wall 1 may be measured using the sample sheet thus obtained. The porosity of the partition walls 1 is preferably a constant value throughout the entire area of the honeycomb structure 4.

The average pore diameter of the partition wall 1 is preferably 5 to 21. Mu.m, more preferably 6 to 20. Mu.m, particularly preferably 7 to 19. Mu.m. The average pore diameter of the partition walls 1 is a value measured by mercury porosimetry. For example, the average pore diameter of the partition wall 1 can be measured by using Autopore 9500 (trade name) manufactured by Micromeritics corporation, and the measurement method and the like are the same as those of the partition wall 1. The honeycomb filter 100 of the present embodiment is preferably: the porosity of the partition wall 1 is 40 to 80% and the average pore diameter of the partition wall 1 is 9 to 21 μm.

The cell density of the honeycomb structure 4 is preferably 31.0 to 62.0 cells/cm ² More preferably 31.0 to 54.3 pieces/cm ² Particularly preferably 31.0 to 46.5 pieces/cm ² . With such a configuration, the honeycomb filter 100 can be suitably used as a filter for purifying exhaust gas discharged from an engine of an automobile. If the cell density is too small, the pressure loss may increase. On the other hand, if the compartment density is too large, the purification performance sometimes decreases. The honeycomb filter 100 of the present embodiment is more preferably: the thickness T1 of the central partition wall 1a and the thickness T2 of the peripheral partition wall 1b are 0.127-0.331 mm, and the cell density of the honeycomb structure 4 is 31.0-62.0 cells/cm ² 。

The shape of the compartment 2 partitioned by the partition wall 1 is not particularly limited. For example, the shape of the cell 2 in a cross section orthogonal to the direction in which the cell 2 extends may be a polygon having corners formed in a curved shape. Hereinafter, a polygon having corners formed in a curved shape may be simply referred to as a "polygon" or a "substantially polygon". For example, the shape of the compartment 2 is preferably a substantially triangle, a substantially quadrangle, a substantially pentagon, a substantially hexagon, a substantially octagon, and more preferably a substantially quadrangle. In the shape of the above-described compartment 2, the substantially quadrangular shape means: the corners of the quadrangle are formed in a curved shape, and the same applies to the other examples of the polygon described above.

The outer peripheral wall 3 of the honeycomb structure 4 may be integrally formed with the partition walls 1, or may be an outer peripheral coating layer formed by applying an outer peripheral coating material to the outer peripheral side of the partition walls 1. For example, although not shown, the partition wall and the outer peripheral wall may be integrally formed at the time of manufacture, the formed outer peripheral wall may be removed by a known method such as grinding, and then an outer peripheral coating layer may be provided on the outer peripheral side of the partition wall.

The shape of the honeycomb structural body 4 is not particularly limited. The shape of the honeycomb structure 4 may be: the inflow end face 11 and the outflow end face 12 have a columnar shape such as a circle, an ellipse, or a polygon.

The size of the honeycomb structure 4, for example, the length from the inflow end face 11 to the outflow end face 12, and the size of the cross section of the honeycomb structure 4 orthogonal to the direction in which the cells 2 extend are not particularly limited. When the honeycomb filter 100 is used as a filter for purifying exhaust gas, the respective sizes may be appropriately selected so as to obtain the optimum purification performance.

The material of the partition wall 1 is not particularly limited. For example, the material of the partition wall 1 may include at least 1 selected from the group consisting of silicon carbide, cordierite, a silicon-silicon carbide composite, a cordierite-silicon carbide composite, silicon nitride, mullite, alumina, and aluminum titanate. The material constituting the partition wall 1 is preferably a material having a content of 90 mass% or more, more preferably 92 mass% or more, and particularly preferably 95 mass% or more of the materials listed in the above group. The silicon-silicon carbide composite material is: a composite material formed by using silicon carbide as aggregate and silicon as a binding material. In addition, the cordierite-silicon carbide composite material is: a composite material formed by taking silicon carbide as aggregate and cordierite as a binding material.

The material of the hole sealing portion 5 is preferably a material that is preferable as the material of the partition wall 1. The material of the hole sealing portion 5 and the material of the partition wall 1 may be the same material or may be different materials.

The honeycomb filter 100 preferably has a catalyst for purifying exhaust gas supported on partition walls 1 partitioning a plurality of cells 2. The supporting of the catalyst on the partition wall 1 means: catalyst is applied to the surfaces of the partition walls 1 and to the inner walls of the pores formed in the partition walls 1. With such a configuration, CO, NOx, HC and the like in the exhaust gas can be rendered harmless by a catalytic reaction. In addition, oxidation of PM such as trapped soot can be promoted. In the honeycomb filter 100 of the present embodiment, it is particularly preferable that the catalyst is supported in the pores of the porous partition walls 1. With such a configuration, the catalyst is supported in a low catalyst amount, and thus the trapping performance and the pressure loss can be simultaneously improved. Further, after the catalyst is supported, the airflow becomes uniform, and improvement of the purification performance can be expected.

The catalyst supported on the partition wall 1 is not particularly limited. For example, a catalyst containing a platinum group element and an oxide of at least one element selected from aluminum, zirconium, and cerium is given.

(2) The manufacturing method of the honeycomb filter comprises the following steps:

the method for producing the honeycomb filter of the present utility model is not particularly limited, and the following methods are exemplified. First, a plastic blank for manufacturing a honeycomb structure is prepared. The green body for producing the honeycomb structure may be prepared by appropriately adding an additive such as a binder, a pore-forming material, and water to a material selected from the preferable materials of the partition walls as a raw material powder.

Next, the thus obtained preform is extruded to produce a cellular molded body having partition walls dividing into a plurality of cells and a columnar shape disposed around the outer peripheral wall of the partition walls. In extrusion molding, as a die for extrusion molding, a die having a slit provided on an extrusion surface of a preform to be a turned shape of a honeycomb molding to be molded may be used. In particular, as the die for extrusion molding, a die provided with a slit having a thickness T1 of the partition wall in the central portion thicker than a thickness T2 of the partition wall in the outer peripheral portion by 0.0127 to 0.0381mm is preferably used. The die for extrusion molding is preferably: the cells are formed by chamfering corners of a polygon into an arc shape having a radius of curvature R of 10 to 100 μm. Next, the obtained honeycomb formed body is dried by, for example, microwave and hot air.

Next, plugged portions are disposed in the openings of the cells of the dried honeycomb formed article. Specifically, for example, a plugging material containing a raw material for forming a plugged portion is first prepared. Next, a mask was applied to the inflow end face of the honeycomb formed body so as to cover the inflow cells. Next, the plugging material prepared previously was filled in the openings of the outflow cells on the inflow end face side of the honeycomb formed body without applying a mask. Thereafter, the openings of the inflow cells were also filled with a plugging material in the same manner as described above with respect to the outflow end face of the honeycomb formed body.

Next, a honeycomb formed body having a plugged portion disposed at any one of the openings of the cells was sintered to produce a honeycomb filter. The firing temperature and the firing atmosphere vary depending on the raw materials, and if the person skilled in the art is able to select the firing temperature and the firing atmosphere optimal for the selected material.

Examples

Hereinafter, the present utility model will be described in further detail with reference to examples, but the present utility model is not limited to these examples.

Example 1

10 parts by mass of a pore-forming material, 4 parts by mass of a dispersion medium, and 4 parts by mass of an organic binder were added to 100 parts by mass of a cordierite forming raw material, and the mixture was mixed and kneaded to prepare a green body. Alumina, aluminum hydroxide, kaolin, talc, and silica were used as cordierite forming raw materials. As the dispersion medium, water was used. As the organic binder, methylcellulose (methyl cellulose) is used. As the dispersant, dextrin (dextran) was used. As the pore-forming material, a water-absorbent polymer having an average particle diameter of 5 μm was used. In this example, the average particle size of each raw material is: particle diameter (D50) at 50% of the cumulative value in the particle size distribution obtained by the laser diffraction scattering method.

Next, the preform was extruded using a die for producing a honeycomb molding, to obtain a honeycomb molding having a cylindrical overall shape. The cells of the honeycomb formed body are quadrangular in shape.

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

Next, a plugging material for forming a plugged portion is prepared. Thereafter, a plugging material is used to form plugging portions in openings of predetermined cells on the inflow end face side and openings of remaining cells on the outflow end face side of the dried honeycomb formed body.

Next, the honeycomb formed body having each plugged portion was degreased and fired to produce the honeycomb filter of example 1.

The honeycomb filter of example 1 has a cylindrical shape with a circular shape on the inflow end face and the outflow end face. The diameters of the inflow end face and the outflow end face were 118.4mm. In addition, the length in the direction in which the cells of the honeycomb filter extend was 127mm. In the honeycomb filter of example 1, the thickness T1 of the center partition wall was 0.2159mm, and the thickness T2 of the outer peripheral partition wall was 0.2032mm. The thickness of each partition wall is shown in table 1. The thickness T1 of the center partition wall increases by 0.0127mm relative to the thickness T2 of the outer peripheral partition wall. The results are shown in the column "increase in center bulkhead (mm)" of Table 1. The ratio of the area of the central portion to the total area of the cross section of the honeycomb structure was 10%.

In the honeycomb filter of example 1, in a cross section orthogonal to the direction in which cells extend, the cells were substantially quadrangular in shape in which corners of the quadrangle were arc-shaped with a radius of curvature R of 10 μm. In the honeycomb filter of example 1, the cell density was 47 cells/cm ² . The porosity of the partition wall was 63%, and the average pore size of the partition wall wasThe diameter was 19. Mu.m. The results are shown in Table 1. The porosity of the partition walls and the average pore diameter were measured by using an Autopore 9500 (trade name) manufactured by Micromeritics corporation.

TABLE 1

The honeycomb filter of example 1 was evaluated for "light-off property", "pressure loss", "erosion resistance", "thermal shock resistance" and "moldability (yield)" by the following methods. The mass of the honeycomb filter of example 1 was measured, and the mass ratio to the mass of the honeycomb filter of comparative example 1 described later was obtained. Based on the results of evaluation of "light-off property", "pressure loss", "erosion resistance" and "thermal shock resistance", the following method was used to perform "comprehensive evaluation". The results are shown in Table 2.

[ ignition Performance ]

The temperature of the center portion of the honeycomb filter was measured by flowing 400℃gas through the honeycomb filter, and the time required for the temperature of the center portion to reach 400℃was measured. Based on the time measured in this way (i.e., the time required for the temperature of the central portion of the honeycomb filter to reach 400 ℃), the evaluation of the light-off performance was performed. Specifically, the ratio (%) of the time required for the temperature of the central portion of the honeycomb filter of comparative example 1 to reach 400 ℃ was obtained for each example and comparative example, where the time required for the temperature of the central portion of the honeycomb filter to reach 400 ℃ was 100.0%. In the evaluation of the light-off performance, the case where the ratio of the value of the time required for the temperature of the central portion of the honeycomb filter to reach 400 ℃ was 105% or less was regarded as acceptable.

[ pressure loss ]

At 25 ℃ for 10m ³ The gas/min flowed through the honeycomb filter, and the pressure difference between the inflow end face side and the outflow end face side of the honeycomb filter in this state was measured. Then, the value of the pressure loss of the honeycomb filter of comparative example 1 was obtained asRatio (%) of the value of the pressure loss of each example and comparative example at 100.0%. In the evaluation of the pressure loss, the case where the ratio of the pressure loss value was 100% or less was regarded as acceptable.

[ erosion resistance ]

Making 800 ℃ and 10m ³ The gas per minute was flowed at an inflow angle of 30 degrees to the inflow end face of the honeycomb filter, and 20mg of silicon carbide powder was put into the gas. After the silicon carbide powder in the gas passes through the honeycomb filter, the amount of end face chipping of the honeycomb filter (hereinafter referred to as "end face chipping amount") was measured. Then, the ratio (%) of the values of the erosion resistance of the honeycomb filters of the examples and comparative examples was obtained when the value of the erosion resistance (hereinafter referred to as "erosion resistance") of the end face removal amount of the honeycomb filter of comparative example 1 was set to 100.0%. The case where the erosion resistance ratio was 105% or more was regarded as acceptable.

[ thermal shock resistance ]

900 ℃ and 10m ³ The gas/min was flowed in a honeycomb filter for 5min, after which the temperature was 250℃and 10m ³ The gas flow per min was 5min. The number of cycles in which cracks were generated in the inlet end face of the honeycomb filter was measured by setting the above-described process to 1 cycle. Then, the ratio (%) of the number of cycles of cracking at the inflow end face of the honeycomb filter in each of examples and comparative examples was determined, where the number of cycles of cracking at the inflow end face of the honeycomb filter in comparative example 1 was 100.0%. In the evaluation of the thermal shock resistance, the case where the number of cycles of crack generation at the inflow end face was 105% or more was regarded as being acceptable.

[ formability (yield) ]

The appearance of the product (dried honeycomb formed body) obtained by molding by extrusion molding and drying was checked to confirm whether or not there was any defect in appearance such as a crack. Then, the ratio (%) of the values of the yields of the honeycomb filters of the examples and comparative examples was obtained when the value of the yield of the honeycomb filter of comparative example 1 was set to 100.0%. In the evaluation of the moldability (yield), the case where the ratio of the value of the yield was 85% or more was regarded as being acceptable.

[ comprehensive evaluation ]

Based on the results of evaluation of the light-off property, the pressure loss, the erosion resistance and the thermal shock resistance, comprehensive evaluation was performed based on the following evaluation criteria.

When all the evaluations of the light-off property, the pressure loss, the erosion resistance and the thermal shock resistance are acceptable, they are described as "excellent" or "ok" in the column of "comprehensive evaluation".

When 1 or more of the evaluation of the light-off performance, the pressure loss, the erosion resistance and the thermal shock resistance is failed, the "total evaluation" column is described as "poor".

TABLE 2

(examples 2 to 17 and comparative examples 1 to 6)

A honeycomb filter was produced in the same manner as the honeycomb filter of example 1 except that the structure of the honeycomb filter was changed as shown in tables 1 and 3.

The honeycomb filters of examples 2 to 17 and comparative examples 1 to 6 were evaluated in the same manner as in example 1. The results are shown in tables 2 and 4.

TABLE 3 Table 3

TABLE 4 Table 4

(results)

And (3) confirming: the honeycomb filters of examples 1 to 17 exceeded the respective performances of the honeycomb filter of comparative example 1 as a reference in all of the evaluation of the light-off performance, the pressure loss, the erosion resistance, and the thermal shock resistance. In particular, the honeycomb filter of example 13 was excellent in all properties including moldability.

In the honeycomb filter of comparative example 2, the radius of curvature R of the corner portions of the cells was 200 μm, and therefore, the results of deterioration in light-off performance and pressure loss were seen.

In the honeycomb filter of comparative example 3, the radius of curvature R was 125 μm, and therefore, the deterioration of the light-off performance and the pressure loss occurred.

In the honeycomb filters of comparative examples 4 and 5, the radius of curvature R of the corner portions of the cells was large, and even if the increase in the thickness T1 of the center partition wall relative to the thickness T2 of the outer peripheral partition wall was adjusted, improvement in light-off performance and pressure loss was insufficient.

In the honeycomb filter of comparative example 6, the increase in the thickness T1 of the center partition wall relative to the thickness T2 of the outer peripheral partition wall was excessive, and as a result, the light-off performance and the pressure loss were deteriorated. In addition, the honeycomb filter of comparative example 6 exhibited very poor molding yield.

Industrial applicability

The honeycomb filter of the present utility model can be used as a filter for trapping particulate matter in exhaust gas.

Claims

1. A honeycomb filter is provided with:

it is characterized in that the method comprises the steps of,

2. The honeycomb filter of claim 1,

the porosity of the partition walls is 40-80%, and the average pore diameter of the partition walls is 5-21 mu m.

3. A honeycomb filter according to claim 1 or 2, characterized in that,

the thickness T1 of the partition walls in the central portion and the thickness T2 of the partition walls in the outer peripheral portion are 0.127-0.331 mm, and the cell density of the honeycomb structure is 31.0-62.0 cells/cm ² 。

4. A honeycomb filter according to claim 1 or 2, characterized in that,

the thickness T1 of the partition wall in the central portion is 0.0127-0.0254 mm thicker than the thickness T2 of the partition wall in the outer peripheral portion,