JP5700518B2 - Honeycomb structure - Google Patents

Description

The present invention relates to a honeycomb structure, more particularly relates to a honeycomb structure that may be used as an excellent catalytic converter carrier purification performance of an exhaust gas discharged from a gasoline engine.

Conventionally, carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NO _x ), sulfur contained in exhaust gas discharged from stationary engines for automobiles, construction machinery, and industrial use, and combustion equipment. In order to purify a component to be purified such as oxide (SO _X ), a catalytic converter in which a purifying catalyst is supported on a catalyst carrier is used. As such a catalytic converter, for example, a converter having a structure in which a catalyst layer is supported on partition walls forming cells in a honeycomb structure is used. In such a catalytic converter, first, exhaust gas was introduced into the cell from one end face side of the catalytic converter, the exhaust gas was brought into contact with the catalyst layer of the partition wall, and then purified from the other end face side to the outside. The gas is exhausted. In this way, exhaust gas can be purified (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 2004-138022

  However, the catalytic converter described in Patent Document 1 has not been sufficient in exhaust gas purification performance (particularly, purification performance immediately after engine startup). Specifically, the contact frequency between the exhaust gas and the catalyst is not yet sufficient, and even if the exhaust gas and the catalyst are in contact, the exhaust gas does not reach the catalyst activation temperature immediately after the engine is started. There was a passage.

The present invention has been made in view of such problems of the prior art, and the problem is that the present invention can be used as a carrier for a catalytic converter excellent in purification performance of exhaust gas exhausted from a gasoline engine. A honeycomb structure is provided.

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

[1] In a cross section provided with a porous partition wall that defines a plurality of cells serving as fluid flow paths extending from the upstream end surface to the downstream end surface, and the end on the upstream end surface side is cut perpendicularly to the fluid flow direction. The partition walls forming the cells are curved, and the wall thickness of the curved portion formed of the curved partition walls is thinner than the wall thickness of portions other than the curved portions, and the partition walls of portions other than both end portions are A honeycomb structure that is not curved or has a degree of curvature smaller than that of the partition wall at the end on the upstream end surface side , and the plurality of cells have end portions on the side where the curved portions are formed. The one cell in a cross section in which the area of the opening of one cell in the projected view when projected onto a plane perpendicular to the fluid flow direction is cut in the middle of the central axis direction of the honeycomb structure. Against the opening area of , The ratio of the number of the deformation cells to the total number of cells is 60% or more, and the wall thickness of the curved portion is the wall of the uncurved portion. A honeycomb structure in which the thickness is 10 to 70% when the thickness is 100%, and the curved portion is formed within a range of 5 mm from an end surface on the side where the curved portion is formed .

  In the honeycomb structure of the present invention, in the cross section obtained by cutting the end portion on the upstream end surface side perpendicularly to the fluid flow direction, the partition walls forming the cells are curved. As a result, turbulent flow is generated in the exhaust gas flowing into the cell. Therefore, when the honeycomb structure of the present invention is used as a catalyst carrier (that is, when a catalytic converter including the honeycomb structure of the present invention is produced as a catalyst carrier), the contact frequency between the exhaust gas and the catalyst increases. The exhaust gas purification performance is improved. Further, since the wall thickness of the curved portion is thinner than the wall thickness of the non-curved portion, the heat capacity is lower than in the case where the wall thickness is the same, and the temperature of the curved portion is increased quickly due to the heat of the exhaust gas. Therefore, in the honeycomb structure of the present invention on which the catalyst is supported (that is, the catalytic converter), the curved portion reaches the catalyst activation temperature at an early stage immediately after the engine is started, and the exhaust gas is purified. The converter is excellent in exhaust gas purification performance immediately after engine startup.

1 is a perspective view schematically showing an embodiment of a honeycomb structure of the present invention. Fig. 2 is a plan view schematically showing an enlarged partial region of an upstream end face of the honeycomb structure of Fig. 1. Fig. 2 is a schematic diagram showing a cross section cut along a plane parallel to the central axis of the honeycomb structure shown in Fig. 1. FIG. 2 is a schematic diagram illustrating a partition wall in which an upstream end portion of the honeycomb structure illustrated in FIG. 1 is curved. FIG. 5 is an arrow view of the partition wall shown in FIG. 4 as viewed from the direction of arrow A. FIG. 5 is an arrow view of the partition wall shown in FIG. FIG. 2 is a projection view of a part of the end portion on the upstream end face side of the honeycomb structure shown in FIG. 1. FIG. 10 is an enlarged plan view schematically showing a partial region of an upstream end surface in still another embodiment of the honeycomb structure of the present invention. FIG. 9 is a projection view of a part of the end portion on the upstream end face side of the honeycomb structure shown in FIG. 8. 1 is a schematic view showing an embodiment of an exhaust gas purifying apparatus using a honeycomb structure of the present invention and showing a cross section cut along a plane parallel to the direction in which the exhaust gas flows.

  Hereinafter, embodiments of the present invention will be described. However, the present invention is not limited to the following embodiments, and based on ordinary knowledge of those skilled in the art without departing from the spirit of the present invention. It should be understood that modifications, improvements, and the like appropriately added to the embodiments described above fall within the scope of the present invention.

[1] Honeycomb structure:
1 to 3 show an embodiment of the honeycomb structure of the present invention, and the honeycomb structure 100 shown in FIGS. 1 to 3 serves as a fluid flow path extending from the upstream end surface 2 to the downstream end surface 3. In the cross section provided with a porous partition wall 5 that partitions and forms a plurality of cells 4 and the end on the upstream end surface 2 side is cut perpendicular to the fluid flow direction, the partition walls 5 that partition the cells 4 are curved, The wall thickness of the curved portion 10a formed of the curved partition wall 5 is thinner than the wall thickness of the portion other than the curved portion 10a (the non-curved portion 11a (see FIG. 4)). The honeycomb structure 100 has an outer peripheral wall 7 disposed on the outer periphery. However, the honeycomb structure of the present invention does not necessarily have an outer peripheral wall. FIG. 1 is a perspective view schematically showing one embodiment of the honeycomb structure 100 of the present invention, and FIG. 2 is an enlarged view of a partial region S of the upstream end surface 2 of the honeycomb structure of FIG. It is a top view typically shown. 3 is a schematic diagram showing a cross section cut along a plane parallel to the central axis of the honeycomb structure 100 shown in FIG. 1, and shows a cross section cut along a plane passing through the position of the arrow K shown in FIG. ing.

  Such a honeycomb structure 100 includes the curved partition walls 5 because the partition walls 5 that form the cells 4 are curved in a cross section obtained by cutting the end portion on the upstream end surface 2 side perpendicular to the fluid flow direction. Turbulent flow is generated in the exhaust gas flowing into the cell 4 by the curved portion 10a. Therefore, when the honeycomb structure 100 is used as a catalyst carrier, the contact frequency between the exhaust gas and the catalyst increases, and the exhaust gas purification performance is improved. Further, since the wall thickness of the curved portion is thinner than the wall thickness of the non-curved portion, the heat capacity is lower than in the case where the wall thickness is the same, and the temperature of the curved portion is increased quickly due to the heat of the exhaust gas. Therefore, in the honeycomb structure 100 on which the catalyst is supported (that is, the catalytic converter), the curved portion reaches the catalyst activation temperature at an early stage immediately after the engine is started, and the exhaust gas is purified. The exhaust gas purification performance in the case will be excellent.

  Further, the fluid (exhaust gas) flowing in the cell 4 becomes so high that the fluid is separated from the partition wall 5. Specifically, a fluid having a higher temperature flows toward the center of the cell 4 in a plane perpendicular to the fluid flow direction. And the said curved part can contact this higher temperature fluid by forming the said curved part. Therefore, the temperature increase rate of the partition wall is improved. Therefore, the honeycomb structure 100 easily reaches the activation temperature of the catalyst when the catalyst is supported, and the exhaust gas purification performance is improved.

[1-1] Bulkhead:
In the honeycomb structure of the present invention, the partition walls forming the cells are curved in a cross section obtained by cutting the end portion on the upstream end face side perpendicular to the fluid flow direction. In other words, in the partition wall of the honeycomb structure of the present invention, the end on the upstream end surface side is curved in a cross section perpendicular to the fluid flow direction. Here, only the end portion on the upstream end surface side may be curved in a cross section perpendicular to the fluid flow direction, and both the end portion on the upstream end surface side and the end portion on the downstream end surface side may be curved in the fluid flow direction. It may be curved in a cross section perpendicular to. That is, only in the cross section obtained by cutting the end portion on the upstream end surface side perpendicularly to the fluid flow direction, the partition wall forming the cell may be curved, or the end portion on the upstream end surface side is perpendicular to the fluid flow direction. The partition walls that form the cells may be curved in both the cross section cut into two and the cross section in which the end portion on the downstream end face side is cut perpendicular to the fluid flow direction. With the latter configuration, the exhaust gas that has flowed into the cells of the honeycomb structure also collides with the curved portion on the downstream end surface side, so the frequency of exhaust gas contacting the catalyst is increased, and the exhaust gas purification performance is further improved. improves.

  In the cross section obtained by cutting the end portion on the upstream end surface side perpendicularly to the fluid flow direction, the partition wall is preferably curved in a convex shape. If it is curved in such a shape, the high-temperature fluid flowing in the center of the cell and the curved portion are more likely to come into contact with each other, so that the rate of temperature rise of the partition wall after the engine is started is further improved. Therefore, in the honeycomb structure carrying the catalyst, the activation temperature of the catalyst is easily reached, and the exhaust gas purification performance is improved. The convex shape is a shape in which the central portion is raised more than the other portions, and examples thereof include an arc shape (see FIG. 2).

The honeycomb structure of the present invention, the partition wall portion other than both ends, or not curved, or the degree of curvature is less than the partition wall of the end portion of the upstream end face side. When a part other than both ends of the partition is not curved, an increase in pressure loss can be prevented. And, when the degree of curvature in the part other than both ends of the partition is smaller than the degree of curvature at the end on the upstream end face side, the pressure loss increases as compared with the case where the other ends are not curved, but both ends. Since the progress of the fluid is appropriately hindered by the curved portion other than the portion, turbulence is appropriately generated in the cell, and the PM collection efficiency is improved.

  Here, “the degree of curvature is smaller than that of the partition wall at the end on the upstream end face side” means that the flow of fluid through the cell is more disturbed at the portion other than both ends than at the end on the upstream end face side. Specifically, it means that “the opening portion of the one cell in the projection view when a portion other than the end portion on the side where the curved portion is formed is projected onto a plane perpendicular to the fluid flow direction” Is larger than “the area of the opening of one cell in the projection when the end on the side where the curved portion is formed is projected onto a plane perpendicular to the fluid flow direction”. .

  The partition wall 5 shown in FIGS. 4 and 5 shows an example in which the portion 11a other than the curved portion 10a has a flat plate shape (a plate shape that does not curve). FIG. 4 is a schematic view showing a partition wall in which one end of the honeycomb structure shown in FIG. 1 is curved. 5 is an arrow view of the partition wall shown in FIG. 5 is an arrow view of the partition wall shown in FIG.

  The honeycomb structure of the present invention is not particularly limited as long as the partition walls that form the cells are curved in the cross-section obtained by cutting the end portion on the upstream end surface side perpendicular to the fluid flow direction. It is preferable that the intersection 12 (see FIG. 2) of the partition wall is not curved. When the intersecting portion is curved, the compressive strength in the flow path direction (fluid flow direction) is reduced, so that when the force in the flow path direction is applied to the honeycomb structure, the honeycomb structure is easily broken. In particular, there is a risk of bending and breaking from the base of the curved portion of the intersection. On the other hand, when the intersecting portion is not curved as in the honeycomb structure of the present invention, the compressive strength in the flow channel direction does not decrease (the compressive strength is maintained). However, there is an advantage that the honeycomb structure is hardly broken.

  In the honeycomb structure of the present invention, the wall thickness of the curved portion formed by the curved partition walls is thinner than the wall thickness of the portion other than the curved portion (the portion that is not curved). As described above, the curved portion can be in contact with a higher temperature fluid. Therefore, even if the wall thickness of the curved portion is about the same as the wall thickness of the non-curved portion, the temperature rising rate is fast (the temperature rising rate is good), but the wall thickness of the curved portion is By making it thinner than the wall thickness of the uncurved part, the heat capacity is lowered, and the temperature raising rate is further increased. Therefore, the curved portion reaches the catalyst activation temperature at an early stage immediately after the engine is started, and the exhaust gas is purified. Moreover, since the temperature rising rate of the curved portion is fast, the temperature rising rate is also high for the entire honeycomb structure.

  Since the wall thickness of the curved portion is thinner than the wall thickness of the non-curved portion, when the temperature of the exhaust gas discharged from the engine is lowered, the temperature of the curved portion tends to be lowered. However, since the non-curved portion has a sufficient thickness, the heat of exhaust gas can be stored in this non-curved portion, and even if the temperature of the exhaust gas discharged from the engine decreases, the curved portion The temperature of the catalyst and the temperature of the exhaust gas when passing through the curved portion can be kept high by the heat stored in the portion that is not. Here, as shown in FIG. 3, the wall thickness T1 of the curved portion is the thickness of the tip of the curved portion 10a, and the wall thickness T0 of the non-curved portion is the thickness in the central axis direction of the honeycomb structure. It is the thickness of the partition wall in the section cut in the middle.

The wall thickness of the curved portion, the wall thickness of the portion that is not curved is 100% Ri 10% to 70% der, it is favorable preferable 30 to 50%. By setting it as the said range, the above-mentioned honeycomb structure with a high temperature increase rate as a whole can be obtained.

  The end of the partition wall refers to a portion in a range from the end surface to a position of 25 mm in the length in the central axis direction of the honeycomb structure (length in the fluid flow direction).

  In the partition wall, the curved portion, which is a curved portion inside the cell, is within the range from the end surface on the side where the curved portion is formed (the end surface closer to the curved portion) to a depth F of 15 mm (see FIG. 3). Preferably, it is formed in the range from the said end surface to the depth of 5 mm. Compared with the case outside the above range, the shape of the flow path changes abruptly (the cell bends suddenly), so that turbulent flow is likely to occur in a fluid such as exhaust gas. As a result, in the honeycomb structure of the present invention (that is, the catalytic converter) on which the catalyst is supported, the contact frequency between the exhaust gas and the catalyst is increased, and the exhaust gas purification performance is improved. When it is outside the above range, when the cell blockage rate is the same, the change in the shape of the flow path becomes gradual as compared with the case where it is within the above range. Therefore, it is difficult for turbulent flow to occur in the fluid in the flow path (cell). As a result, the contact frequency between the exhaust gas and the catalyst becomes low, and there is a possibility that sufficient purification performance cannot be obtained. The “end surface on the side on which the curved portion is formed” means both the upstream end surface and the downstream end surface when the curved portion is formed on the upstream end surface or the end on the downstream end surface side. . And the range of 15 mm from the said end surface is a range from the end surface in the side in which the curved part was formed to 15 mm in the center axis direction of a honeycomb structure. In other words, it means a range between the end surface and a plane perpendicular to the fluid flow direction formed at a position (depth F (see FIG. 3)) 15 mm away from the end surface in the fluid flow direction. To do.

In the plurality of cells, the area of the opening of one cell in the projection when the end portion on the side where the curved portion is formed is projected onto a plane perpendicular to the fluid flow direction is the center axis direction of the honeycomb structure. Including a deformation cell having a size of 10 to 60% with respect to the area of the opening of the one cell in the cross section obtained by cutting the honeycomb structure in the middle, the ratio of the number of deformation cells to the total number of cells is Ru der 60% or more. When such a deformation cell satisfies the above range, PM clogging hardly occurs and PM can be collected well. Here, the deformed cell is a cell that satisfies the above-mentioned conditions. In other words, the deformed cell is a cell that prevents the fluid from traveling straight in the cell by the curved portion, and has, for example, a curved portion. Even if the cell is partitioned by the partition wall, the cell does not fall under a deformed cell if the curved portion does not prevent the fluid from going straight through the cell.

  FIG. 7 shows a case where the end of the honeycomb structure 100 shown in FIG. 1 on the side where the curved portion 10a is formed (the end on the upstream end face 2 side) is projected onto a plane perpendicular to the fluid flow direction. A part of the projection is shown. In FIG. 7, the honeycomb structure 100 is cut at an area S1 of the opening 8 of one deformation cell 4a in the projection (FIG. 7) in the middle M (see FIG. 3) in the central axis direction of the honeycomb structure 100. The example which is in the range of 10 to 60% with respect to area S0 (square area shown with a broken line in FIG. 7) of the opening part 18 of the one deformation | transformation cell 4a in the cross section is shown. Hereinafter, the value calculated by (S1 / S0) × 100 may be referred to as “cell blocking rate”.

  In the honeycomb structure of the present invention, in the projection view of the end portion on the side where the curved portion is formed, the contour line of the curved portion when the projection view is enlarged 50 times is a plurality of the contour lines formed at the tip of the partition wall. It is preferably a wavy line resulting from projections of irregularities. Thus, since the contour line of the curved portion is wavy, the surface area is larger than when the contour line is smooth, so that the heat exchange rate is good and the temperature increase rate of the honeycomb structure is improved. Here, the “wavy line shape” is a waveform in which peaks and valleys having the same or different sizes appear irregularly. The honeycomb structure of the present invention has a partition wall on which the wavy outline is drawn, and the partition wall is formed on the end surface of the honeycomb structure (on the side where the wavy outline is drawn). The difference between the thinnest part and the thickest part in the end face is, for example, 20 to 500 μm. The difference is preferably 20 to 400 μm.

  FIG. 8 is a projection view of the end portion on the side where the curved portion 10a, which is a curved portion inside the cell 4, is formed, and an outline L ( In other words, the contour line L) of the curved portion 10a located inside the cell 4 is an example of a wavy line resulting from the projection of a plurality of irregularities formed at the tip of the partition wall 5. . FIG. 8 is a plan view schematically showing an enlarged partial region of the upstream end surface 2 in still another embodiment of the honeycomb structure of the present invention, and FIG. 9 is a honeycomb structure shown in FIG. It is a projection drawing of a part of edge part by the side of the upstream end face.

  The porosity of the partition walls 5 is preferably 25 to 65%, and more preferably 30 to 50%. If it is less than 25%, when the honeycomb structure also acts as a filter for collecting particulate matter in the exhaust gas, the collection performance may be reduced and the pressure loss may be increased. If it is larger than 65%, the strength of the honeycomb structure may be lowered. The porosity of the partition wall 5 is a value measured by a mercury porosimeter.

  The thickness of the partition wall 5 is preferably 0.05 to 0.45 mm, and more preferably 0.10 to 0.25 mm. If it is thinner than 0.05 mm, the strength of the honeycomb structure may be lowered. If it is thicker than 0.45 mm, the pressure loss may increase. The thickness of the partition wall 5 is a value measured by a method of observing a cross section parallel to the central axis with a microscope. In addition, the thickness of the partition 5 is the thickness of the partition 5 in parts other than the curved part.

The cell density of the honeycomb structure 100 (the number of cells per unit area in a cross section perpendicular to the extending direction of the cells 4 of the honeycomb structure 100) is preferably 30 to 150 cells / cm ² , and is preferably 50 to 150. More preferably, the number of particles / cm ² . If it is less than 30 / cm ² , the canning property may be lowered. If it is greater than 150 / cm ² , the pressure loss may increase.

  The average pore diameter of the partition walls 5 is preferably 10 to 100 μm, and more preferably 15 to 80 μm. If it is smaller than 10 μm, the pressure loss may increase even when there is little accumulation of particulate matter on the partition walls. On the other hand, if it is larger than 100 μm, the honeycomb structure may become brittle and easily lost. The average pore diameter of the partition walls 5 is a value measured with a mercury porosimeter.

  The shape of the cell 4 of the honeycomb structure 100 is not particularly limited, but in the cross section orthogonal to the cell 4 extending direction, it is a polygon such as a triangle, a quadrangle, a pentagon, a hexagon, an octagon, a circle, or an ellipse. Preferably, it may be indefinite. A combination of a square and an octagon is also a preferred embodiment.

  Although the thickness of the outer peripheral wall 7 is not specifically limited, 1-7 mm is preferable. If it is thinner than 1 mm, the strength may decrease. If it is thicker than 7 mm, the pressure loss may increase.

  The shape of the cross section cut perpendicularly to the flow direction of the honeycomb structure 100 is not particularly limited, but is preferably a circle, an ellipse, a polygon, or the like. The honeycomb structure 100 is preferably cylindrical with the cell 4 extending direction as the central axis direction. Further, the size of the honeycomb structure 100 is not particularly limited, but the length in the extending direction of the cells 4 is preferably 50 to 400 mm. Specifically, when the honeycomb structure 100 has a columnar shape, the upstream end surface preferably has a diameter of 50 to 400 mm.

  It is preferable that the partition walls 5 and the outer peripheral wall 7 of the honeycomb structure 100 are mainly composed of ceramic. Specific examples of the material of the partition wall 5 and the outer peripheral wall 7 include silicon carbide, silicon-silicon carbide based composite material, cordierite, mullite, alumina, spinel, silicon carbide-cordierite based composite material, lithium aluminum silicate, and It is preferably at least one selected from the group consisting of aluminum titanates. Among these, cordierite having a small thermal expansion coefficient and excellent thermal shock resistance is preferable. The material of the partition wall 5 and the outer peripheral wall 7 is preferably the same, but may be different. In addition, the phrase “having ceramic as a main component” means that the ceramic is contained in an amount of 80% by mass or more.

[1-2] Catalyst:
The honeycomb structure of the present invention can be used as a carrier of a catalytic converter excellent in exhaust gas purification performance, and a catalyst converter can be obtained by loading a catalyst on the partition walls of the honeycomb structure of the present invention. The catalyst to be supported can be appropriately determined according to the purpose. Examples thereof include a three-way catalyst, an oxidation catalyst, a NO _X selective reduction catalyst, and a NO _X storage reduction catalyst. The supported amount per unit volume of the catalyst is preferably 10 to 300 g / liter, and more preferably 15 to 250 g / liter. When the loading amount is more than 300 g / liter, the pores of the partition walls 5 may be blocked, resulting in an increase in pressure loss.

A three-way catalyst refers to a catalyst that mainly purifies hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NO _x ). For example, a catalyst containing platinum (Pt), palladium (Pd), and rhodium (Rh) can be given. By this three-way catalyst, hydrocarbons are purified by water or carbon dioxide, carbon monoxide is converted to carbon dioxide, and nitrogen oxides are converted to nitrogen by oxidation or reduction.

  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 noble metals is preferably 0.1 to 10.0 g / liter per unit volume of the honeycomb structure 100.

Examples of the NO _X selective reduction catalyst include those containing at least one selected from the group consisting of metal-substituted zeolite, vanadium, titania, tungsten oxide, silver, and alumina.

Examples of the NO _X storage reduction catalyst include alkali metals and / or alkaline earth metals. Examples of the alkali metal include K, Na, Li and the like. Examples of the alkaline earth metal include Ca.

[2] Manufacturing method of honeycomb structure:
First, a forming raw material is kneaded to form a clay. Next, after the obtained kneaded material was extruded into a honeycomb shape to obtain an extruded molded body, at least one end of the extruded molded body was threaded with a stainless steel (SUS) thread (thickness 0.01). To 0.8 mm), a honeycomb molded body in which the ends of the partition walls are curved inward of the cells in a plane perpendicular to the fluid flow direction can be obtained by cutting with a cutting means such as a metal plate. Next, a honeycomb structure can be produced by firing the obtained honeycomb formed body. After the firing, a honeycomb structure (catalyst converter) on which the catalyst is supported can be manufactured by supporting the catalyst on the partition walls as necessary. In addition, after extruding the clay into a honeycomb shape, the end face of the partition wall can be curved to the inside of the cell by crushing the end face without cutting with a cutting means. Further, after extrusion molding into a honeycomb shape to obtain a columnar continuous honeycomb molded body that is long in the central axis direction, the obtained continuous honeycomb molded body may be cut by the cutting means to obtain a honeycomb molded body. Good. Here, according to the cutting means, the shape of the opening of the cell on the cut surface is difficult to maintain, and the partition wall is bent (curved). And the wall thickness of a curved part becomes thin as a partition is curved. In this way, the wall thickness of the curved portion can be made thinner than the wall thickness of the uncurved portion.

  Moreover, the outline of the opening in the cut surface can be roughened according to the type of cutting means and the cutting speed (that is, the outline of the opening can be jagged). In other words, the outline of the opening can be made wavy by appropriately setting the type of cutting means and the cutting speed.

  The cutting means advances while the end of the partition wall is deformed in the advancing direction of the cutting means when the extruded product is cut. Therefore, the cutting means has a large resistance value with respect to the extruded body to such an extent that the end of the partition wall can be deformed. Specific examples include stainless steel having the above thickness.

  The moving speed of the cutting means (cutting speed at the end of the extruded product) is not particularly limited as long as the partition wall is curved and the wall thickness of the curved part is thinner than the wall thickness of the uncurved part. Although it can determine suitably with the material and thickness of these, it is preferable that it is 10-20 cm / sec.

  The end portion on the side where the curved portion is not formed can be cut under known conditions by a known cutting means (sharp metal blade or the like) used for manufacturing a conventional honeycomb structure.

  The forming raw material is preferably a ceramic raw material added with a dispersion medium and an additive, and 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 3-10 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 8 to 15 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 individually by 1 type, and may be used in combination of 2 or more type. It is preferable that content of surfactant is 0.1-5.0 mass parts with respect to 100 mass parts of ceramic raw materials.

  It is preferable that content of a dispersion medium is 0.2-3.0 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) used and the particle size and blending amount of the pore former to be added, a porous substrate having a desired porosity and average pore size is obtained. Can do.

  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 molding 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.

  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.

  The method for supporting the catalyst on the partition walls of the honeycomb structure is not particularly limited, and examples thereof include a method of applying a catalyst slurry to the partition walls of the honeycomb structure, followed by drying and baking. The method for applying the catalyst slurry is not particularly limited, and can be applied by a known method. For example, first, a catalyst slurry containing a catalyst is prepared. Thereafter, the prepared catalyst slurry is caused to flow into the cell by dipping or suction. This catalyst slurry is preferably applied to the entire surface of the partition walls in the cell. And after making a catalyst slurry flow in in a cell, surplus slurry is blown off with compressed air. Thereafter, the catalyst slurry is dried and baked to obtain a honeycomb structure in which the catalyst is supported on the surface of the partition walls in the cell. The drying conditions are preferably 80 to 150 ° C. and 1 to 6 hours. Moreover, it is preferable that baking conditions shall be 450-700 degreeC and 0.5 to 6 hours. In addition, alumina etc. are mentioned as components other than the catalyst contained in a catalyst slurry.

[3] Exhaust gas purification device:
As shown in FIG. 9, an embodiment of the exhaust gas purifying apparatus of the present invention has a honeycomb structure 100 (honeycomb structure of the present invention), an inlet 22 into which exhaust gas G1 flows, and purified exhaust gas G2 flows out. A cylindrical can body 21 having an outlet 23 and accommodating the honeycomb structure 100, the honeycomb structure 100 having the upstream end face 2 facing the inlet 22 side of the can body 21 and the downstream end face 3 being a can It is arrange | positioned in the can 21 so that the outflow port 23 side of the body 21 may face. FIG. 9 is a schematic view showing an embodiment of the exhaust gas purifying apparatus of the present invention and showing a cross section cut along a plane parallel to the direction in which the exhaust gas flows.

  As described above, the exhaust gas purification apparatus 200 of the present embodiment includes the honeycomb structure 100, and the honeycomb structure 100 has the upstream end surface 2 facing the inlet 22 side of the can body 21 and the downstream end surface 3 is the can body 21. Therefore, turbulent flow is generated in the exhaust gas flowing into the cell 4 by the curved portion 10a of the honeycomb structure 100. Therefore, in the honeycomb structure (catalytic converter) on which the catalyst is supported, the contact frequency between the exhaust gas and the catalyst increases, and the exhaust gas purification apparatus having this catalytic converter improves the exhaust gas purification performance. Further, since the wall thickness of the curved portion 10a of the honeycomb structure 100 is thinner than the wall thickness of the non-curved portion, the heat capacity is lower than when the wall thickness is the same, and the curved portion 10a has the heat of exhaust gas. The temperature rise due to is fast. Therefore, in the honeycomb structure 100, the curved portion reaches the catalyst activation temperature at an early stage immediately after the engine is started and the exhaust gas is purified, and the exhaust gas purification apparatus having the catalytic converter has an exhaust gas purification performance immediately after the engine is started. Excellent.

[3-1] Honeycomb structure:
In the exhaust gas purification apparatus of the present invention, the honeycomb structure housed in the can is the honeycomb structure of the present invention. The number of honeycomb structures 100 can be determined as appropriate so that the pressure loss or the like becomes a desired value.

  When two or more honeycomb structures are arranged in the can body, the plurality of honeycomb structures are all “the upstream end surface 2 faces the inlet 22 side of the can body 21 and the downstream end surface 3 is the can body 21. It arrange | positions so that it may face the outflow port 23 side. When two or more honeycomb structures are arranged, the diameter of each honeycomb structure in the “cross section perpendicular to the cell extending direction” is the same as that of the other honeycomb structure “cross section orthogonal to the cell extending direction”. It is preferable that the diameter is the same, but there may be a honeycomb structure having a different diameter.

  For example, FIG. 9 shows an example of the exhaust gas purification apparatus 200 including one honeycomb structure 100. In the exhaust gas purification apparatus 200 shown in FIG. 9, one honeycomb structure 100 has an upstream end face 2 of a can body. 21 is arranged in the can 21 with the downstream end face 3 facing the outlet 23 side of the can body 21 while facing the inlet 22 side of the can 21.

[3-2] Can body:
In the exhaust gas purifying apparatus 200, the can body 21 is a cylindrical structure having an inlet 22 through which the exhaust gas G1 flows in and an outlet 23 through which the purified exhaust gas G2 flows out and housing the honeycomb structure 100. .

  The can body 21 is not particularly limited, and cans that are normally used for housing a honeycomb filter for purifying exhaust gas such as automobile exhaust gas can be used. Examples of the material of the can body 21 include metals such as stainless steel. The size of the can body 21 is preferably a size that can be press-fitted in a state where the cushion material 31 is wound around the honeycomb structure 100. The can body 21 is a portion in which both ends of the cylindrical shape are tapered and the diameters of the inlet 22 and the outlet 23 in the “cross section perpendicular to the direction in which the exhaust gas flows” are stored in the central honeycomb structure. It is preferably smaller than the diameter in the “cross section perpendicular to the direction in which the exhaust gas flows”. Specifically, the diameter of the central portion of the can 21 is preferably 60 to 410 mm. Moreover, as for the said diameter of the inflow port 22 and the outflow port 23 of the can body 21, 60-410 mm is preferable.

  In the exhaust gas purification apparatus 200, when two or more honeycomb structures 100 are arranged in the can 21, the distance between the honeycomb structures 100 (that is, between the inflow end face and the outflow end face of the adjacent honeycomb structures facing each other). Is preferably 1 to 90 mm, and more preferably 2 to 50 mm. If it is shorter than 1 mm, the adjacent honeycomb structures 100 may come into contact with each other and breakage may occur. If it is longer than 90 mm, the exhaust gas purifying apparatus 200 may become large.

  The honeycomb structure 100 is preferably press-fitted into the can body 21 with the cushion material 31 wound around the outer periphery. When housed in such a state, the honeycomb structure 100 can be prevented from moving in the can body 21 and can be stabilized in the can body 21. This prevents the honeycomb structure 100 from being damaged. Although it does not specifically limit as the cushioning material 31, A heat resistant inorganic insulation mat etc. can be mentioned.

  The honeycomb structure 100 is preferably housed in the can body 21 with both end surfaces fixed by the fasteners 32. The fastener 32 may be a ring shape in which the center portion of the flat plate is removed, or may be a plate shape that fastens a part of the outer edge of the end face of the honeycomb structure 100. The material of the fastener 32 may be a ceramic or a metal such as stainless steel or steel.

[4] Manufacturing method of exhaust gas purification device:
As a method of manufacturing an embodiment of the exhaust gas purification apparatus of the present invention (exhaust gas purification apparatus 200) shown in FIG. 9, the outer periphery of the embodiment of the honeycomb structure of the present invention (honeycomb structure 100), A method of obtaining the exhaust gas purification device 200 by winding the cushion 31 material and press-fitting the honeycomb structure 100 around which the cushion material 31 is wound into the can body 21 is preferable.

  Examples of the cushion material 31 include a heat-resistant inorganic insulating mat. When housed in this manner, the honeycomb structure 100 can be prevented from moving in the can 21.

  The can 21 can be produced by a known method. For example, a plate material made of ferritic stainless steel can be produced by pressing and welding. The conditions such as the shape and size of the can body are preferably the conditions that are preferable in the embodiment of the exhaust gas purification apparatus of the present invention.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples. In Examples and Comparative Examples, the average pore diameter of the partition walls is a value measured by a mercury porosimeter, and the porosity is a value measured by Archimedes method.

(Example 1)
Talc, kaolin, alumina, silica and the like were prepared at a predetermined blending ratio so as to be cordierite after firing, and an organic binder, a surfactant, and water were added to obtain a clay.

  The obtained kneaded material was formed into a cylindrical honeycomb shape using an extrusion molding machine to obtain an extrusion molded body, and then one end of the extrusion molded body was threaded with a stainless steel (SUS) thread (thick And the other end with a sharp metal blade, the end on the upstream end face side of the partition wall is curved inside the cell in a plane perpendicular to the fluid flow direction. Thus, a cylindrical honeycomb formed body in which the end on the downstream end face side was not curved was obtained. As shown in FIGS. 4 and 5, all of the curved portions of the obtained honeycomb formed body had a shape gradually rising from the center of the flow path toward the end face. The moving speed of the yarn when cutting with the yarn was 18 cm / sec.

  The obtained honeycomb formed body was dried at 120 ° C. for 1 hour using a hot air dryer, and then fired at 1350 to 1450 ° C. for 6 hours to obtain a honeycomb structure.

This honeycomb structure has a cell blockage rate of 40% and a curved portion forming range of 2 mm (that is, curved within a range from the end surface on the side where the curved portion is formed (upstream end surface) to a depth of 2 mm. The ratio of the number of deformed cells was 70%, the thickness ratio was 30%, and the contour line (contour line of the curved portion) was smooth. The honeycomb structure of the present example has a thickness ratio of 30% as described above (that is, when the wall thickness of the non-curved portion is 100%, the wall thickness of the curved portion is 30%). Therefore, the wall thickness of the curved portion was thinner than the wall thickness of the non-curved portion (portion other than the curved portion). In addition, this honeycomb structure has a partition wall thickness of 120 μm, a cell density of 62 cells / cm ² , an end face diameter of 93 mm, a central axis direction length of 76 mm, and an average partition wall thickness of The pore diameter was 4 μm, and the porosity of the partition walls was 32%. The “thickness ratio” is the ratio of the thickness of the partition at a position 1 mm from the tip of the curved partition (curved portion) to the thickness of the partition at the intermediate position in the fluid flow direction. The thickness of the partition wall is a value obtained by cutting the honeycomb structure parallel to the central axis direction and measuring the thickness of the partition wall at a position of 1 mm from the end face. The average pore diameter of the partition walls is a value measured by a mercury porosimeter, and the porosity is a value measured by the Archimedes method. In Tables 1 and 2, the case where the contour line is wavy is shown as “wavy”, and the case where the contour is not wavy is shown as “smooth”. “Smooth” means that the difference between the thinnest and the thickest partition walls on the end face of the honeycomb structure is less than 10 μm.

  With respect to the obtained honeycomb structure, “heating rate” and “strength” were evaluated by the following methods. The evaluation results are shown in Table 1. The “cell blockage rate” in Table 1 represents the average value of the cell blockage rates of all cells. The value (mm) of the formation range of the curved portion indicates the depth from the end surface (upstream end surface) on the side where the curved portion is formed.

[Raising rate]
The temperature of the partition wall at the end portion on the downstream end face side of the honeycomb structure when a gas (high temperature fluid) of 600 ° C. is introduced from the upstream end face side of the honeycomb structure at a rate of 10 Nm ³ / min using a gas burner device. The rise was measured using a thermocouple. When the temperature of the curved portion 40 seconds after the start of the test is higher by 30 ° C. or more than the temperature of the partition wall at the downstream end face side of the honeycomb structure of Comparative Example 1, “AA” is set. “A”, “B” when the temperature was higher by 10 ° C. to 19 ° C., and “C” when the temperature was lower than 10 ° C. This evaluation is shown as “temperature increase rate” in Table 1. In addition, if the temperature increase rate increases, the purification performance per unit time is improved. Therefore, the higher the rate of temperature rise, the higher the purification performance. Therefore, a honeycomb structure having a high temperature rising rate has a high purification performance.

[Compressive fracture strength]
Using a compression tester (“Instron 4206” manufactured by Instron), a load is continuously applied in the flow direction of the fluid of the honeycomb structure at a head speed of 1 mm / min or less, so that the flow direction of the honeycomb structure is increased. The compressive fracture strength was measured. Thereafter, the compression fracture strength was evaluated according to the following evaluation criteria. When the compressive fracture strength of each honeycomb structure is 50 to 100% of the compressive fracture strength of the honeycomb structure of Comparative Example 1, it is “AA”, and when it is 30 to 49%, it is “A”. When it was 29%, it was “B”, and when it was less than 5%, it was “C”. This evaluation is shown as “strength” in Table 1.

  In Table 1, “-” in the “shape” column indicates that the honeycomb structure has a shape in which the end portion of the partition wall is not curved (the curved portion is not formed). It shows that the end portion of the partition wall is curved (a curved portion is formed). The “convex” specifically indicates a shape as shown in FIGS. 4 and 5. That is, in the cross section obtained by cutting the end portion perpendicular to the fluid flow direction, the partition walls forming the cells are curved in a convex shape, and are gradually raised from the center of the honeycomb structure toward the end surface. Indicates that the shape is the most raised on the end face of the body.

  In addition, the exhaust gas purification apparatus provided with the honeycomb structure manufactured in this example was manufactured as follows. First, a metal (specifically, ferritic stainless steel) can body having an inflow port and an outflow port provided with a partition plate having a thickness of 2 mm was prepared. Next, the obtained honeycomb structure was accommodated in the can body. When storing, the outer periphery of the honeycomb structure is covered with a mat mainly composed of ceramic fibers, and the upstream end surface faces the inlet side of the can body and the downstream end surface is the outlet side of the can body The honeycomb structure was press-fitted into the can and fixed so that the An exhaust gas purification device was produced as described above. Since this exhaust gas purifying apparatus includes the honeycomb structure manufactured in the present example with favorable evaluation results of “temperature increase rate” and “strength”, when the honeycomb structure of the present example is used as a catalyst carrier, The exhaust gas purification performance is improved.

( Examples 3-6, 8, 9, 13, 14, 16, 17, Reference Examples 2, 7, 10-12, 15 )
Cell closure rate, the formation range of the curved portion, the ratio of the number of variations cells, the thickness ratio, and except that the contour line is as respectively to those shown in Table 1, in the same manner as in Example 1, Examples and A honeycomb structure of a reference example was produced. With respect to each of the manufactured honeycomb structures, “heating rate” and “strength” were evaluated by the following methods. The evaluation results are shown in Table 1.

(Example 18)
Talc, kaolin, alumina, silica and the like were prepared at a predetermined blending ratio so as to be cordierite after firing, and an organic binder, a surfactant, and water were added to obtain a clay.

  The obtained kneaded material was molded into a cylindrical honeycomb shape by using an extrusion molding machine to obtain an extrusion molded body, and then both ends of the extrusion molded body were made of stainless steel (SUS) thread (thick By cutting at a thickness of 0.05 mm, the downstream end (one end) and the upstream end (the other end) of the partition wall are curved in a plane perpendicular to the fluid flow direction. A cylindrical honeycomb formed body was obtained. The moving speed of the yarn when cutting with the yarn was 18 cm / sec.

  The obtained honeycomb formed body was dried at 120 ° C. for 1 hour using a hot air dryer, and then fired at 1350 to 1450 ° C. for 6 hours to obtain a honeycomb structure.

This honeycomb structure has a cell blockage rate of 40% at the end portion on the upstream end surface side, and the formation range of the curved portion is 2 mm (that is, the curved portion is formed within a range of 2 mm from the upstream end surface). ), The thickness ratio was 30%, the ratio of the number of deformed cells to the total number of cells (the ratio of the number of deformed cells) was 70%, and the shape of the “contour line” was “smooth”. Then, at the end on the downstream end face side, the cell blocking rate is 40%, the formation range of the bending portion is 2 mm (that is, the bending portion is formed in the range of 2 mm from the downstream end face), and the thickness The ratio was 30%, the ratio of the number of deformed cells to the total number of cells (the ratio of the number of deformed cells) was 70%, and the shape of the “contour line” was “smooth”. The honeycomb structure has a partition wall thickness (thickness of the partition wall at a middle position in the fluid flow direction) of 120 μm, a cell density of 62 cells / cm ² , and an end face diameter of 93 mm. The length in the central axis direction (length in the fluid flow direction) was 76 mm, the average pore diameter of the partition walls was 4 μm, and the porosity of the partition walls was 32%.

  With respect to the obtained honeycomb structure, “heating rate” and “strength” were evaluated by the above methods. The evaluation results are shown in Table 1.

(Example 19)
Talc, kaolin, alumina, silica and the like were prepared at a predetermined blending ratio so as to be cordierite after firing, and an organic binder, a surfactant, and water were added to obtain a clay.

  The obtained kneaded material was formed into a cylindrical honeycomb shape using an extrusion molding machine to obtain an extrusion molded body, and then one end of the extrusion molded body was threaded with a stainless steel (SUS) thread (thick 0.07 mm), and the other end with a sharp metal blade, the end on the upstream end face side of the partition wall is curved inside the cell in a plane perpendicular to the fluid flow direction. Thus, a cylindrical honeycomb formed body in which the end on the downstream end face side was not curved was obtained. The moving speed of the yarn when cutting with the yarn was 10 cm / second.

  The obtained honeycomb formed body was dried at 120 ° C. for 1 hour using a hot air dryer, and then fired at 1350 to 1450 ° C. for 6 hours to obtain a honeycomb structure.

This honeycomb structure has a cell blockage rate of 40% at the end portion on the upstream end surface side, and the formation range of the curved portion is 2 mm (that is, the curved portion is formed within a range of 2 mm from the upstream end surface). ), The thickness ratio is 30%, the ratio of the number of deformed cells to the total number of cells (the ratio of the number of deformed cells) is 70%, and the shape of the “contour line” is “wavy” . The honeycomb structure has a partition wall thickness (thickness of the partition wall at a middle position in the fluid flow direction) of 120 μm, a cell density of 62 cells / cm ² , and an end face diameter of 93 mm. The length in the central axis direction (length in the fluid flow direction) was 76 mm, the average pore diameter of the partition walls was 4 μm, and the porosity of the partition walls was 32%.

  With respect to the obtained honeycomb structure, “heating rate” and “strength” were evaluated by the above methods. The evaluation results are shown in Table 1.

( Examples 21-24, 26, 27, 31, 32, 34, 35, Reference Examples 20, 25, 28-30, 33 )
Cell closure rate, the formation range of the curved portion, the ratio of the number of variations cells, the thickness ratio, and except that the contour line is to respectively as shown in Table 2, in the same manner as in Example 19, Examples and A honeycomb structure of a reference example was produced. With respect to each manufactured honeycomb structure, “heating rate” and “strength” were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

(Example 36)
Talc, kaolin, alumina, silica and the like were prepared at a predetermined blending ratio so as to be cordierite after firing, and an organic binder, a surfactant, and water were added to obtain a clay.

  The obtained kneaded material was molded into a cylindrical honeycomb shape by using an extrusion molding machine to obtain an extrusion molded body, and then both ends of the extrusion molded body were made of stainless steel (SUS) thread (thick Is formed into a cylindrical honeycomb shape in which the end portion on the upstream end surface side and the end portion on the downstream end surface side of the partition wall are curved inward of the cell in a plane perpendicular to the fluid flow direction. Got the body. The moving speed of the yarn when cutting with the yarn was 12 cm / second.

  The obtained honeycomb formed body was dried at 120 ° C. for 1 hour using a hot air dryer, and then fired at 1350 to 1450 ° C. for 6 hours to obtain a honeycomb structure.

This honeycomb structure has a cell blockage rate of 40% at the end portion on the upstream end surface side, and the formation range of the curved portion is 2 mm (that is, the curved portion is formed within a range of 2 mm from the upstream end surface). ) The thickness ratio was 30%, the ratio of the number of deformed cells to the total number of cells (the ratio of the number of deformed cells) was 60%, and the shape of the “contour line” was “wavy line” . Then, at the end on the downstream end face side, the cell blocking rate is 40%, the formation range of the bending portion is 2 mm (that is, the bending portion is formed in the range of 2 mm from the downstream end face), and the thickness The ratio was 30%, the ratio of the number of deformed cells to the total number of cells (the ratio of the number of deformed cells) was 60%, and the shape of the “contour line” was “wavy line”. The honeycomb structure has a partition wall thickness (thickness of the partition wall at a middle position in the fluid flow direction) of 120 μm, a cell density of 62 cells / cm ² , and an end face diameter of 93 mm. The length in the central axis direction (length in the fluid flow direction) was 76 mm, the average pore diameter of the partition walls was 4 μm, and the porosity of the partition walls was 32%.

  With respect to the obtained honeycomb structure, “heating rate” and “strength” were evaluated by the above methods. The evaluation results are shown in Table 2.

(Comparative Example 1)
Talc, kaolin, alumina, silica and the like were prepared at a predetermined blending ratio so as to be cordierite after firing, and an organic binder, a surfactant, and water were added to obtain a clay.

  The obtained clay was formed into a cylindrical honeycomb shape by using an extrusion molding machine to obtain an extrusion-molded body, and then both ends were cut with a sharp metal blade to form a cylindrical shape in which the partition walls were not curved. A honeycomb formed body was obtained.

  The obtained honeycomb formed body was dried at 120 ° C. for 1 hour using a hot air dryer, and then fired at 1300 to 1450 ° C. for 6 hours to obtain a honeycomb structure.

  With respect to the manufactured honeycomb structure, “heating rate” and “strength” were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

As is clear from Tables 1 and 2, the honeycomb structure shown in the example has a higher temperature rise rate than the honeycomb structure of Comparative Example 1, and the purification performance of exhaust gas exhausted from the gasoline engine It can be confirmed that it can be used as a carrier of an excellent catalytic converter.

In Examples 5 to 6, since the value of the thickness ratio (%) is small, that is, the heat capacity of the curved portion is sufficiently low, the temperature rising rate was evaluated better than Examples 3 and 4. .

In Examples 1 , 3, and 4, the value of the thickness ratio (%) satisfies a predetermined range, and thus the evaluation of strength (strength of the curved portion) was better than in Examples 5 and 6.

In Reference Example 2, the value of the thickness ratio (%) is too large, that is, the difference in wall thickness between the curved portion and the non-curved portion is small. "Is not enough.

  The honeycomb structure of the present invention and the exhaust gas purification apparatus of the present invention can be suitably used for purification of exhaust gas discharged from a gasoline engine.

2: upstream end face, 3: downstream end face, 4: cell, 4a: deformation cell, 5: partition wall, 7: outer peripheral wall, 8, 18: opening, 10a: curved part, 11a: part other than curved end part, 12: Crossing part, 21: Can body, 22: Inlet, 23: Outlet, 31: Cushion material, 32: Fastener, 100: Honeycomb structure, 200: Exhaust gas purification device, G1: Exhaust gas, G2: Purified Exhaust gas.

Claims (1)

Comprising a porous partition wall defining a plurality of cells that serve as fluid flow paths extending from the upstream end surface to the downstream end surface;
In the cross section obtained by cutting the end portion on the upstream end surface side perpendicularly to the fluid flow direction, the partition wall defining the cell is curved,
The wall thickness of the curved portion formed of the curved partition wall is thinner than the wall thickness of the portion other than the curved portion,
The partition walls of portions other than both end portions are not curved, or a honeycomb structure having a smaller degree of curvature than the partition walls at the end portion on the upstream end surface side ,
In the plurality of cells, the area of the opening of one cell in the projection when the end on the side where the curved portion is formed is projected onto a plane perpendicular to the fluid flow direction is the center of the honeycomb structure. A deformation cell having a size of 10 to 60% with respect to the area of the opening of the one cell in a cross section obtained by cutting the honeycomb structure in the middle in the axial direction, The percentage of the number is 60% or more,
The wall thickness of the curved portion is 10 to 70%, where the wall thickness of the non-curved portion is 100%,
The honeycomb structure, wherein the bending portion is formed within a range of 5 mm from an end surface on a side where the bending portion is formed .

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