JP5719181B2 - Honeycomb structure - Google Patents

Description

The present invention relates to a honeycomb structure.

Particulates such as soot (hereinafter also referred to as PM) contained in exhaust gas discharged from internal combustion engines such as vehicles such as buses and trucks and construction machinery and other harmful components may harm the environment and the human body. It has become a problem recently. Accordingly, various honeycomb structures made of porous ceramics have been proposed as honeycomb filters for collecting PM in exhaust gas and purifying the exhaust gas.

Conventionally known as such a honeycomb structure is a honeycomb structure comprising ceramic blocks in which a plurality of honeycomb fired bodies having a large number of cells are bundled (Patent Document 1). Of the honeycomb fired bodies used when manufacturing the conventional honeycomb structure described in Patent Document 1, examples of the honeycomb fired bodies positioned on the outermost periphery of the honeycomb structure are shown in FIGS. 16 (a) and 16 (b). ) Schematically. In the honeycomb fired body 1110 and the honeycomb fired body 1120 shown in FIGS. 16 (a) and 16 (b), the cell 1111 and the cell 1121 that are closest to the curved surface constituting the outer peripheral surface of the ceramic block are cross-sectional shapes perpendicular to the longitudinal direction (Hereinafter, also simply referred to as a cross-sectional shape) is substantially triangular or substantially trapezoidal, unlike the cross-sectional shape of the cells located inside the cells, and one side of the cells 1111 and 1121 is formed along the curved surface. Has been.

As a honeycomb structure capable of sealing cells of the honeycomb fired body without filling defects, a honeycomb structure as described in Patent Document 2 has been proposed. In Patent Document 2, in the cells of the honeycomb fired body constituting the honeycomb structure, the cells in contact with the outer peripheral wall constituting the outer periphery of the ceramic block among the outer peripheral walls of the honeycomb fired body (hereinafter referred to as the outermost peripheral portion). A honeycomb structure that facilitates filling with a plug material paste is disclosed by making the cross-sectional shape of the cells other than the outermost peripheral portion the same.
17A and 17B, the conventional honeycomb structure described in Patent Document 2 in which the cross-sectional shape of the cell located at the outermost peripheral portion and the cross-sectional shape of the cell located outside the outermost peripheral portion are the same. Examples of honeycomb fired bodies constituting the body are shown. The cross-sectional shapes of the cells 1151 of the honeycomb fired body 1150 and the cells 1161 of the honeycomb fired body 1160 are all square, and the positions of the cells are formed so that the cells 1151 or 1161 are arranged at equal intervals. Then, in order to make the cross-sectional shape of the cell located at the outermost peripheral portion the same as the cross-sectional shape of the cell located outside the outermost peripheral portion, the outer peripheral wall 1154 of the honeycomb fired body 1150 or the outer peripheral wall of the honeycomb fired body 1160 The step 1164 is provided with a step corresponding to the position of the cell 1151 or the cell 1161 located on the outermost periphery.

JP 2004-154718 A International Publication No. 2008/126335 Pamphlet

In the conventional honeycomb structure described in Patent Document 1, the cells 1111 of the honeycomb fired body 1110 shown in FIG. 16A and the cells 1121 of the honeycomb fired body 1120 shown in FIG. 16B are sealed. In this case, since the opening area of the cell is small, it is difficult to fill the sealing material paste, or the sealing material is likely to leak or protrude, which causes insufficient sealing of the cell, resulting in poor sealing. Will occur.

When a honeycomb structure manufactured using a honeycomb fired body with insufficient cell sealing is used as an exhaust gas purification filter, the exhaust gas flowing into the honeycomb structure flows out of the same cell without passing through the cell wall. Therefore, there is a problem that it does not function as a filter.

In the honeycomb fired body constituting the conventional honeycomb structure described in Patent Document 2, a step is provided on the outer peripheral wall of the honeycomb fired body. That is, on the outer peripheral wall of the honeycomb fired body constituting the conventional honeycomb structure described in Patent Document 2, in a cross section perpendicular to the longitudinal direction of the honeycomb fired body, convex portions 1155 as shown in FIG. A step formed by the concave portion 1156 or a step formed by the convex portion 1165 and the concave portion 1166 as shown in FIG. 17B is provided.
In such a honeycomb fired body constituting the conventional honeycomb structure, there is no sealing failure and the cells can be sufficiently sealed. However, when a honeycomb formed body is manufactured by extruding the wet mixture, the outer peripheral wall is formed on the outer peripheral wall of the honeycomb fired body in the cross section perpendicular to the longitudinal direction of the honeycomb fired body. There is a problem that it is difficult to form. The reason is considered as follows. It is difficult for the wet mixture to flow at the position of the convex portion or concave portion of the mold used in the extrusion molding, and the amount of the wet mixture filled in the convex portion or concave portion of the mold tends to be insufficient. As a result, since the outer peripheral wall having a desired shape cannot be produced, a molding defect occurs in which the convex portion of the outer peripheral wall is missing or the concave portion of the outer peripheral wall is partially thinned.
Furthermore, in the drying process after extrusion molding, the outer peripheral wall of the honeycomb molded body comes into contact with a conveying jig or the like, so that there is a problem that the convex portion present on the outer peripheral wall of the honeycomb molded body is missing, or the outer peripheral wall Since the amount of the wet mixture filled in the recesses is insufficient, there is a problem that cracks start from the recesses due to expansion and contraction due to temperature changes during drying or firing. As a result, defects in the honeycomb fired body increase, and the manufacturing efficiency of the honeycomb structure decreases.

Furthermore, when manufacturing a honeycomb structure using such a honeycomb fired body, the outer peripheral wall of the honeycomb fired body, the outer peripheral wall of the honeycomb block made of the honeycomb fired body, and the outer peripheral wall of the manufactured honeycomb structure are: Convex and concave portions still exist. Therefore, during the process of manufacturing the honeycomb structure, or when the honeycomb structure is used as a honeycomb filter, the honeycomb structure is exposed to high temperatures such as chipping of the outer peripheral wall of the honeycomb structure or regeneration treatment. Defects such as cracks starting from the convex portions and / or concave portions of the outer peripheral wall due to expansion and contraction of the fired body occur.

The present invention has been made in order to solve the above-described problem, and can be easily filled with a sealing material paste for sealing cells of a honeycomb fired body constituting the honeycomb structure, and the honeycomb fired body An object of the present invention is to provide a honeycomb structure capable of preventing the occurrence of chipping or cracking of the outer peripheral wall of the present invention or the outer peripheral wall of the honeycomb structure.

In order to achieve the above object, the honeycomb structure according to claim 1 is composed of a honeycomb fired body in which a large number of cells are arranged side by side in the longitudinal direction across the cell wall and an outer peripheral wall is formed around the cell. A honeycomb structure made of ceramic blocks,
Among the outer peripheral walls of the honeycomb fired body, the outer peripheral wall constituting the outer periphery of the ceramic block is a step outer peripheral wall provided with a step composed of a convex part and a concave part in a cross section perpendicular to the longitudinal direction of the honeycomb fired body. And
Since the convex portions and / or the concave portions are chamfered, the convex portions and / or the concave portions are configured by curves and / or straight lines in a cross section perpendicular to the longitudinal direction of the honeycomb fired body. It is characterized by being.

In the honeycomb structure according to claim 1, of the outer peripheral walls of the honeycomb fired body, the outer peripheral wall constituting the outer periphery of the ceramic block includes a convex portion and a concave portion in a cross section perpendicular to the longitudinal direction of the honeycomb fired body. A step is provided.
In the conventional honeycomb structure, cells having a cross-sectional shape different from the cross-sectional shape of the inner cell and having a small cell cross-sectional area (hereinafter also referred to as incomplete cells) remain in the manufacturing process of the honeycomb structure, Cell sealing failure occurred, reducing the efficiency of the cell sealing process. However, in the honeycomb structure according to claim 1, the number of incomplete cells located in the outermost peripheral portion of the honeycomb structure is reduced by providing a step including a convex portion and a concave portion on the outer peripheral wall of the honeycomb fired body. be able to. Thereby, since the cross-sectional area of the cell located in the outermost periphery part of a honeycomb structure can be increased, the filtration area increases, PM collection efficiency improves, and pressure loss also improves. Moreover, since the sealing material paste can be easily filled, sealing failure can be reduced and the manufacturing efficiency of the honeycomb structure can be improved.

In this specification, the cell wall of the honeycomb fired body refers to a portion that exists between two cells and separates the two cells. Further, in the present specification, the outer peripheral wall of the honeycomb fired body refers to a portion that exists around the honeycomb fired body and constitutes the outer periphery of the honeycomb fired body.

Further, in the honeycomb structure according to claim 1, the convex portions and / or concave portions in the cross section perpendicular to the longitudinal direction of the honeycomb fired body are obtained by chamfering the convex portions and / or concave portions of the outer peripheral wall. Is constituted by a curve and / or a straight line.
That is, in the honeycomb structure according to claim 1, the chamfered portion in the convex portion and / or the concave portion is configured by a curve and / or a straight line in a cross section perpendicular to the longitudinal direction of the honeycomb fired body. .
Therefore, at the time of extrusion molding when producing a honeycomb formed body, the convex portion of the outer peripheral wall is missing due to insufficient amount of the wet mixture filled in the convex portion or concave portion of the mold, or the concave portion of the outer peripheral wall is Partial thinning can be prevented. In addition, the outer peripheral wall of the honeycomb molded body comes into contact with a conveying jig or the like during the drying step, the firing step, the binding step, etc. after extrusion for producing the honeycomb fired body constituting the honeycomb structure. In addition, because the protrusions present on the outer peripheral wall of the honeycomb molded body are missing, or the amount of the wet mixture filled in the concave portions of the outer peripheral wall is insufficient, due to expansion and contraction due to temperature changes during drying or firing, It is possible to prevent cracks from starting from the concave portion of the outer peripheral wall. As a result, defects in the honeycomb formed body and the honeycomb fired body are reduced, and the manufacturing efficiency of the honeycomb structure can be improved.

Further, during the process of manufacturing the honeycomb structure according to claim 1 or when the honeycomb structure is used as a honeycomb filter, chipping generated on the convex portion of the outer peripheral wall of the honeycomb structure or high temperature It is possible to prevent defects such as cracks starting from the convex portions and / or concave portions of the outer peripheral wall due to expansion and contraction of the honeycomb fired body when exposed.

In the honeycomb structure according to claim 2, a plurality of the honeycomb fired bodies are bundled through the adhesive layer in the ceramic block.
Moreover, in the honeycomb structure according to claim 3, the ceramic block is formed by combining honeycomb fired bodies having different shapes,
The honeycomb fired body includes an outer honeycomb fired body positioned on the outer periphery of the ceramic block and an inner honeycomb fired body positioned on the inner side of the outer honeycomb fired body.

In the honeycomb structure according to a fourth aspect, in the cross section perpendicular to the longitudinal direction of the honeycomb fired body, the convex portions and / or the concave portions are constituted only by curves.
That is, in the honeycomb structure according to claim 4, the chamfered portion of the convex portion and / or the concave portion of the outer peripheral wall is configured by only a curve in a cross section perpendicular to the longitudinal direction of the honeycomb fired body. . Thus, in the cross section perpendicular to the longitudinal direction of the honeycomb fired body, when the shape of the convex portion and / or the concave portion of the outer peripheral wall is only a curved shape, the stress relaxation property is excellent. Therefore, it starts from a chip in the convex portion of the outer peripheral wall due to contact with a jig or the like during conveyance, or a convex portion and / or a concave portion of the outer peripheral wall due to expansion and contraction of the honeycomb fired body when exposed to a high temperature. Generation of cracks and the like can be further prevented.

In the honeycomb structure according to claim 5, the cell includes an outer peripheral cell in contact with an outer peripheral wall of the honeycomb fired body and an inner cell positioned on the inner side of the outer peripheral cell. Corners are formed, and at least one of the corners is chamfered.

In the honeycomb structure according to the fifth aspect, the corners formed on the inner walls of the peripheral cells (hereinafter, also simply referred to as “corner portions of the peripheral cells”) are chamfered. When the corners of the peripheral cells are chamfered, the stress is relieved compared to the case where the corners of the peripheral cells are sharp. Therefore, it starts from a chip in the convex portion of the outer peripheral wall due to contact with a jig or the like during conveyance, or a convex portion and / or a concave portion of the outer peripheral wall due to expansion and contraction of the honeycomb fired body when exposed to a high temperature. Generation of cracks and the like can be further prevented.

The honeycomb structure according to claim 6, wherein the chamfered corner portion includes a corner portion constituted by the stepped outer peripheral wall and a corner portion constituted by the stepped outer peripheral wall and the cell wall. It is.
Of the corners of the peripheral cells, the corners formed by the stepped outer peripheral wall and the corners formed by the stepped outer peripheral wall and the cell wall are chamfered. The stress added to the convex part or the concave part which has can be relieved. Therefore, generation | occurrence | production of the crack etc. which start from the chip | tip in the convex part of an outer peripheral wall or the convex part and / or recessed part of an outer peripheral wall can be prevented more.
In addition, since the thickness of the stepped outer peripheral wall of the honeycomb fired body can be made substantially the same including the thickness of the outer peripheral wall of the convex portion, deformation of the outer peripheral wall of the honeycomb molded body during extrusion molding can be prevented. .

In the honeycomb structure according to claim 7, the chamfering applied to at least one of the corners is an R chamfer, and the radius of curvature of the R chamfer is 0.3 to 2.5 mm.
R chamfering is excellent in stress relaxation because the corners of the peripheral cells are chamfered into a curved shape in a cross section perpendicular to the longitudinal direction of the honeycomb fired body. Accordingly, it is possible to further prevent the occurrence of cracks and the like starting from the convex portion and / or the concave portion of the outer peripheral wall.

In the honeycomb structure according to claim 8, the cell includes an outer peripheral cell in contact with an outer peripheral wall of the honeycomb fired body, and an inner cell positioned inside the outer peripheral cell,
The inner cell is a complete cell formed based on the basic formation pattern,
Out of the peripheral cells, the peripheral cells in contact with the stepped peripheral wall include incomplete cells whose cross-sectional shape perpendicular to the longitudinal direction is different from the complete cells.

The honeycomb structure according to claim 8, wherein the cross-sectional shape of the cell located at the outermost peripheral portion and the cross-sectional shape of the cell located outside the outermost peripheral portion are all the same. Unlike incomplete cells. Therefore, in the cross section perpendicular to the longitudinal direction of the honeycomb fired body, the number of convex portions or concave portions of the stepped outer peripheral wall of the honeycomb fired body can be reduced. As a result, at the time of extrusion molding, the amount of the wet mixture filled in the convex portion or concave portion of the mold is insufficient, so that the convex portion of the outer peripheral wall is missing, or the concave portion of the outer peripheral wall is partially thinned. Can be prevented. In addition, during the drying process or the firing process after extrusion, the protrusions present on the outer peripheral wall of the honeycomb molded body or the honeycomb fired body are missing due to contact with a jig or the like during transportation, or exposed to high temperatures. When the honeycomb fired body is expanded and contracted, it is possible to further prevent cracks from starting from the convex portions and / or concave portions of the outer peripheral wall.
Moreover, when such a honeycomb structure is used as an exhaust gas purification filter, a filtration area capable of collecting PM can be improved, and pressure loss can be reduced.

In the honeycomb structure according to claim 9, a shape of a cross section perpendicular to the longitudinal direction of the outer peripheral cell excluding the incomplete cell and a shape of a cross section perpendicular to the longitudinal direction of the inner cell are approximately It is a rectangle.

In the honeycomb structure according to claim 10, the outer peripheral cell excluding the incomplete cell, and the inner cell is composed of a large capacity cell and a small capacity cell,
The area of the cross section perpendicular to the longitudinal direction of the large capacity cell is larger than the area of the cross section perpendicular to the longitudinal direction of the small capacity cell.
In such a honeycomb structure, a large amount of PM can be collected when used as an exhaust gas purification filter.

In the honeycomb structure according to claim 11, the shape of a cross section perpendicular to the longitudinal direction of the large-capacity cell is substantially square, and the shape of a cross section perpendicular to the longitudinal direction of the small-capacity cell is substantially square. .
Further, in the honeycomb structure according to claim 12, the shape of the cross section perpendicular to the longitudinal direction of the large capacity cell is substantially octagonal, and the shape of the cross section perpendicular to the longitudinal direction of the small capacity cell is approximately. It is a rectangle.
In the honeycomb structure according to claim 13, in the cross section perpendicular to the longitudinal direction of the large capacity cell and the small capacity cell, each side of the cell is constituted by a curve.
Since the honeycomb structure according to any one of claims 11 to 13 has a cell having a cross-sectional shape as described above, when used as an exhaust gas purification filter, PM in exhaust gas can be suitably collected. it can.

In the honeycomb structure according to claim 14, the thickness of the stepped peripheral wall of the honeycomb fired body is larger than the thickness of the cell wall of the honeycomb fired body.
By making the thickness of the step outer peripheral wall larger than the thickness of the cell wall, the shape of the convex and concave portions constituting the step can be easily curved and / or linear in the cross section perpendicular to the longitudinal direction of the honeycomb fired body. And it will be easier.
Moreover, it can also be set as the honeycomb structure with high mechanical strength of an outer peripheral wall.

In the honeycomb structure according to claim 15, the thickness of the stepped peripheral wall of the honeycomb fired body is 1.3 to 3.0 times the thickness of the cell wall of the honeycomb fired body.
If the thickness of the step outer peripheral wall is 1.3 times or more the thickness of the cell wall of the honeycomb fired body, the protrusions and recesses of the outer peripheral wall constituting the step in the cross section perpendicular to the longitudinal direction of the honeycomb fired body It becomes easy to make the shape of the curve shape and / or linear shape. Further, it becomes easy to sufficiently secure the mechanical strength of the outer peripheral wall of the honeycomb structure.
On the other hand, when the thickness of the outer peripheral wall of the step is 3.0 times or less than the thickness of the cell wall of the honeycomb fired body, the aperture ratio of the honeycomb structure is difficult to decrease.

In the honeycomb structure according to claim 16, among the stepped peripheral walls of the honeycomb fired body, the outer peripheral walls other than the convex portions and the concave portions have substantially the same thickness.

In the honeycomb structure according to claim 17, each one end of the cells is alternately sealed.

In the honeycomb structure according to claim 18, a coat layer is formed on the outer peripheral surface of the ceramic block.

FIG. 1 is a perspective view schematically showing an example of the honeycomb structure of the first embodiment of the present invention. FIG. 2 is a cross-sectional view of the honeycomb structure shown in FIG. 1 taken along line AA. Fig.3 (a) is a perspective view which shows typically an example of the inner honeycomb fired body which comprises the honeycomb structure of 1st embodiment of this invention. Fig. 3 (b) is a cross-sectional view of the inner honeycomb fired body shown in Fig. 3 (a) taken along line BB. Fig. 4 (a) is a perspective view schematically showing an example of an outer honeycomb fired body constituting the honeycomb structure according to the first embodiment of the present invention. Fig. 4 (b) is a side view of the outer honeycomb fired body shown in Fig. 4 (a). Fig.5 (a)-FIG.5 (d) are the partial expanded sectional views which show typically an example of the shape of the chamfering given to the convex part which concerns on embodiment of this invention. FIG.5 (e)-FIG.5 (h) are the partial expanded sectional views which show typically an example of the shape of the chamfering given to the recessed part which concerns on embodiment of this invention. Fig.6 (a) is a perspective view which shows typically an example of the outer honeycomb fired body which comprises the honeycomb structure of 2nd embodiment of this invention. FIG. 6B is a side view of the outer honeycomb fired body shown in FIG. Fig.7 (a) is a side view which shows typically an example of the inner honeycomb fired body which comprises the honeycomb structure of 3rd embodiment of this invention. FIG. 7B is a side view schematically showing an example of the outer honeycomb fired body constituting the honeycomb structure of the third embodiment of the present invention. Fig. 8 (a) is a side view schematically showing another example of the inner honeycomb fired body constituting the honeycomb structure according to the third embodiment of the present invention. FIG. 8B is a side view schematically showing another example of the outer honeycomb fired body constituting the honeycomb structure of the third embodiment of the present invention. FIG. 9 is a side view schematically showing an example of the honeycomb structure of the fourth embodiment of the present invention. FIGS. 10A and 10B are side views schematically showing an example of the outer honeycomb fired body constituting the honeycomb structure according to the fourth embodiment of the present invention. FIG. 11 is a side view schematically showing an example of the honeycomb structure of the fifth embodiment of the present invention. 12 (a) and 12 (b) are side views schematically showing an example of an outer honeycomb fired body constituting the honeycomb structure of the fifth embodiment of the present invention. FIG. 13 is a side view schematically showing an example of a honeycomb structure according to another embodiment of the present invention. FIG. 14 is a side view schematically showing another example of a honeycomb structure of another embodiment of the present invention. FIGS. 15A and 15B are side views schematically showing an example of an end face of the inner honeycomb fired body constituting the honeycomb structure according to the embodiment of the present invention. FIG. 16 (a) is a perspective view schematically showing an example of a honeycomb fired body positioned on the outermost periphery of the honeycomb fired body among the honeycomb fired bodies used in manufacturing a conventional honeycomb structure. Fig. 16 (b) is a perspective view schematically showing another example of the honeycomb fired body positioned on the outermost periphery of the conventional honeycomb structure. FIG. 17A schematically shows an example of a honeycomb fired body constituting a conventional honeycomb structure in which the cross-sectional shape of the cell located at the outermost peripheral portion and the cross-sectional shape of the cell located outside the outermost peripheral portion are the same. FIG. FIG. 17B shows another example of the honeycomb fired body constituting the conventional honeycomb structure in which the cross-sectional shape of the cell located at the outermost peripheral portion is the same as the cross-sectional shape of the cell located outside the outermost peripheral portion. It is a side view showing typically.

(First embodiment)
Hereinafter, a first embodiment which is an embodiment of a honeycomb structure of the present invention will be described with reference to the drawings.

In the following description, the outer honeycomb fired body and the inner honeycomb fired body are simply referred to as a honeycomb fired body when it is not necessary to distinguish between them. Further, when there is no need to particularly distinguish the outer cell and the inner cell, and the complete cell and the incomplete cell, they may be simply expressed as cells.
In the present specification, when the section of the honeycomb structure, the section of the honeycomb fired body, or the section of the honeycomb formed body is simply expressed, the section perpendicular to the longitudinal direction of the honeycomb structure, respectively, It refers to a cross section perpendicular to the longitudinal direction or a cross section perpendicular to the longitudinal direction of the honeycomb formed body.
Further, in this specification, when simply expressed as the cross-sectional area of the honeycomb fired body, the area of the cross section perpendicular to the longitudinal direction of the honeycomb fired body is indicated.

FIG. 1 is a perspective view schematically showing an example of the honeycomb structure of the first embodiment of the present invention.
FIG. 2 is a cross-sectional view of the honeycomb structure shown in FIG. 1 taken along line AA.
In the honeycomb structure 100 shown in FIGS. 1 and 2, a plurality of honeycomb fired bodies 110 and 120 are bonded together via an adhesive layer 101 (101A to 101D) to form a ceramic block 103, and this ceramic block A coat layer 102 is formed on the outer periphery of 103. In addition, the coat layer should just be formed as needed.
Although the honeycomb fired bodies 110 and 120 constituting the honeycomb structure 100 will be described later, a porous body made of silicon carbide or silicon-containing silicon carbide is preferable.

In the honeycomb structure 100, as shown in FIG. 1 and FIG. 2, eight honeycomb fired bodies 120 at positions constituting the outer periphery of the ceramic block 103 and four honeycomb fired bodies positioned inside the honeycomb fired body 120. The body 110 is bound through adhesive layers 101 (101A to 101D) so that the cross-sectional shape of the ceramic block 103 (honeycomb structure 100) is substantially circular.

Hereinafter, the honeycomb fired body located at the position constituting the outer periphery of the ceramic block is referred to as an “outer honeycomb fired body”, and the honeycomb fired body positioned inside the outer honeycomb fired body is referred to as an “inner honeycomb fired body”. To do.
In the honeycomb structure of the present embodiment, the ceramic block is formed by combining the honeycomb fired bodies having different shapes, or the outer honeycomb fired body located on the outer peripheral portion of the ceramic block and the inner side of the outer honeycomb fired body. It can be said that the inner honeycomb fired body is positioned.

As will be described later, the outer peripheral wall of the outer honeycomb fired body 120 is provided with a step including a convex portion and a concave portion in a cross section perpendicular to the longitudinal direction of the honeycomb fired body. Is provided with a step. And the coating layer 102 formed in the outer periphery of the ceramic block 103 is formed so that the recessed part provided in the level | step difference may be filled.

In addition, in this specification, a convex part means the convex part formed by one cell outside the outer peripheral wall which comprises the outer periphery of a ceramic block among the outer peripheral walls of a honeycomb fired body. Moreover, in this specification, a recessed part means the recessed part formed by two adjacent cells in the outer peripheral wall which comprises the outer periphery of a ceramic block among the outer peripheral walls of a honeycomb fired body.

As shown in FIG. 2, the honeycomb structure 100 includes, in a cross section, an adhesive layer 101C formed in a direction from a corner portion of one inner honeycomb fired body 110 toward the outer peripheral side surface of the honeycomb structure 100; The adhesive layer 101D formed in a direction from the space between the two inner honeycomb fired bodies 110 toward the outer peripheral side surface of the honeycomb structure 100 forms a predetermined angle (for example, 45 ° or the like).

As shown in FIG. 2, the shape of the cross section of the inner honeycomb fired body 110 is a substantially square (substantially square).
Further, as shown in FIG. 2, the cross section of the outer honeycomb fired body 120 has a shape surrounded by three line segments 120a, 120b, 120c and one substantially circular arc 120d. Two angles formed by two of the three line segments (an angle formed by the line segment 120b and the line segment 120c and an angle formed by the line segment 120a and the line segment 120b) are 90 °, respectively. 135 °. The shape of the substantially arc will be described later.

Hereinafter, the inner honeycomb fired body and the outer honeycomb fired body constituting the honeycomb structure of the present invention will be described with reference to the drawings.
Fig.3 (a) is a perspective view which shows typically an example of the inner honeycomb fired body which comprises the honeycomb structure of 1st embodiment of this invention. Fig. 3 (b) is a cross-sectional view of the inner honeycomb fired body shown in Fig. 3 (a) taken along line BB.
Fig. 4 (a) is a perspective view schematically showing an example of an outer honeycomb fired body constituting the honeycomb structure according to the first embodiment of the present invention. Fig. 4 (b) is a side view of the outer honeycomb fired body shown in Fig. 4 (a).

First, the inner honeycomb fired body will be described.
In the inner honeycomb fired body 110 shown in FIGS. 3 (a) and 3 (b), a large number of cells 111 are arranged in the longitudinal direction (in the direction of arrow a in FIG. 3 (a)) across the cell wall 113. The outer peripheral walls 114a to 114d are formed around the periphery. One end of the cell 111 is sealed with a sealing material 112.

Therefore, the exhaust gas G (in FIG. 3B, the exhaust gas is indicated by G and the flow of the exhaust gas is indicated by an arrow in FIG. 3B) always passes through the cell wall 113 that separates the cell 111. Then, the other end surface flows out from the other cell 111 opened. When exhaust gas G passes through the cell wall 113, PM and the like in the exhaust gas are collected, so that the cell wall 113 functions as a filter.

The cross-sectional shapes perpendicular to the longitudinal direction of the cells 111 of the inner honeycomb fired body 110 are all substantially square (substantially square), and the cross-sectional areas of the cells 111 are equal to each other. The cells 111 are formed so that the cells 111 are arranged at the same interval.

Next, the outer honeycomb fired body will be described.
In the outer honeycomb fired body 120 shown in FIGS. 4 (a) and 4 (b), as in the inner honeycomb fired body, a large number of cells 121 are separated from each other by the cell wall 123 in the longitudinal direction (in FIG. 4 (a)). , In the direction of arrow b), and outer peripheral walls 124a to 124d are formed around it. One end of the cell 121 is sealed with a sealing material 122.
Therefore, the exhaust gas flowing into the cell 121 with one end face opened always flows through the cell wall 123 separating the cell 121 and then flows out from the other cell 121 with the other end face opened. 123 functions as a filter. That is, the outer honeycomb fired body 120 is different in appearance from the inner honeycomb fired body 110, but has the same filter function as the inner honeycomb fired body 110.

Of the outer peripheral walls 124a to 124d of the outer honeycomb fired body 120, the shape of the cross section perpendicular to the longitudinal direction of the outer peripheral wall 124a constituting the outer periphery of the honeycomb structure (ceramic block) is substantially arc-shaped as described above. ing. Specifically, as shown in FIG. 4A and FIG. 4B, a step outer peripheral wall provided with a step formed by a convex portion 125 and a concave portion 126 corresponding to the position of the cell 121. Yes.

In the present embodiment, the convex portions and / or concave portions existing on the step outer peripheral wall are chamfered, so that the convex portions and / or concave portions are curved and / or in a cross section perpendicular to the longitudinal direction of the honeycomb fired body. Or it is comprised by the straight line. That is, the cross section of the chamfered portion (the cross section perpendicular to the longitudinal direction of the honeycomb fired body) is configured by a curve and / or a straight line.
4 (a) and 4 (b), the convex portion 125 and the concave portion 126 existing on the stepped outer peripheral wall 124a are chamfered, so that the convex portion in the cross section perpendicular to the longitudinal direction of the honeycomb fired body. 125 and the recessed part 126 have shown the example comprised by the curve.

Hereinafter, chamfering applied to the convex portion and / or the concave portion of the outer peripheral wall will be described with reference to the drawings.
Fig.5 (a)-FIG.5 (d) are the partial expanded sectional views which show typically an example of the shape of the chamfering given to the convex part which concerns on embodiment of this invention. FIG.5 (e)-FIG.5 (h) are the partial expanded sectional views which show typically an example of the shape of the chamfering given to the recessed part which concerns on embodiment of this invention.
In this specification, if the cross-sectional shape of the convex portion is a shape with the corners cut away as shown in FIGS. 5 (a) to 5 (d), “the convex portion is chamfered. " On the other hand, the cross-sectional shape of the concave portion is a shape as shown in FIGS. 5E to 5H, that is, a virtual convex portion exists in a portion where the outer honeycomb fired body does not exist. Assuming that this hypothetical convex part has a chamfered shape (the corner part has the same corner part shape as a pseudo chamfered part), “the concave part is chamfered. "
Further, the chamfered shape applied to the recess can be considered as a shape in which a filling portion is provided in the recess.

In addition, although the specific method to make the shape of the convex part of an outer peripheral wall and the shape of a recessed part into said shape is not specifically limited, For example, the metal mold | die which becomes said shape is produced, and extrusion molding The method of performing etc. is mentioned.

FIG. 5A and FIG. 5E show chamfering in which the corner portion has an arc shape. Such chamfering is referred to as R chamfering.
FIG. 5B and FIG. 5F show chamfering in which the shape of the convex portion or the virtual convex portion is cut off by one straight line so that only an obtuse angle exists. Such chamfering is referred to as C chamfering.
FIG. 5C, FIG. 5D, FIG. 5G, and FIG. 5H show chamfering that makes the shape of a corner cut by a plurality of straight lines.
Among the chamfers applied to the convex portions and / or concave portions of the outer peripheral wall, R chamfering or C chamfering is desirable, and R chamfering is more desirable.

When R-chamfering is performed on the convex portion and / or the concave portion of the outer peripheral wall, the desirable lower limit is 0.3 mm and the more desirable lower limit is 0.5 mm, while the desirable upper limit is 2. 5 mm.
When the radius of curvature of the R chamfer is 0.3 mm or more, the stress due to expansion and contraction of the honeycomb fired body when exposed to a protrusion or recess of the outer peripheral wall with a jig or the like at the time of conveyance or at a high temperature Concentration can be prevented. Further, when the radius of curvature of the R chamfer is 2.5 mm or less, the rounding of the convex portion or the concave portion of the outer peripheral wall is too large, so that the chamfering operation is not difficult.
The radius of curvature of the R chamfer means the radius of the arc in the R chamfer having the corners arcuate.

When C chamfering is performed on the convex portion and / or the concave portion of the outer peripheral wall, the desirable lower limit is 0.3 mm and the more desirable lower limit is 0.5 mm, while the desirable upper limit is 2. 5 mm.
The length of the C chamfer means the length of the two sides originally constituting the corner portion, the length of the side that is longer cut by the C chamfer.

The chamfering given to the convex part and / or the recessed part of the outer peripheral wall should just be given to at least one place, and the position of chamfering is not limited.
However, it is desirable that the number of chamfered portions be as large as possible, and it is more desirable that all the portions of the convex portion and the concave portion of the outer peripheral wall constituting the step are chamfered.

In the present embodiment, the convex portions and / or the concave portions of the outer peripheral wall are rounded, so that the convex portions and / or the concave portions are configured only by curves in the cross section perpendicular to the longitudinal direction of the honeycomb fired body. It is desirable that Among them, the convex portions and the concave portions are configured only by curves in the cross section perpendicular to the longitudinal direction of the honeycomb fired body by performing the chamfering on all the portions of the convex portions and the concave portions of the outer peripheral wall. Is more desirable.

As shown in FIGS. 4A and 4B, the shape of the cross section perpendicular to the longitudinal direction of the cells 121 of the outer honeycomb fired body 120 is all substantially square (substantially square). The cross-sectional areas are equal to each other. The positions of the cells 121 are designed so that the cells 121 are arranged at the same interval. The cells in contact with the outer peripheral wall and the cells not in contact with the outer peripheral wall have the same cross-sectional shape.

The thickness of the step outer peripheral wall 124a is substantially the same over the entire step outer peripheral wall 124a except for the convex portion and the concave portion. Further, the thickness of the stepped outer peripheral wall 124a excluding the convex portion and the concave portion is substantially the same as the thickness of the cell wall 123 and the other outer peripheral walls 124b to 124d.

Next, a method for manufacturing the honeycomb structure of the present embodiment will be described. The case where silicon carbide is used as the ceramic powder will be described.
(1) A forming step for producing a honeycomb formed body by extruding a wet mixture containing a ceramic powder and a binder is performed.
Specifically, first, a wet mixture for manufacturing a honeycomb formed body is prepared by mixing silicon carbide powder having different average particle sizes as ceramic powder, an organic binder, a liquid plasticizer, a lubricant, and water. To prepare.
Subsequently, the wet mixture is charged into an extruder. A honeycomb formed body having a predetermined shape is manufactured by extrusion molding.

Here, a honeycomb molded body having a substantially square (substantially square) cross section (a honeycomb molded body serving as an inner honeycomb fired body) or a cross section is surrounded by three line segments and one substantially circular arc. In order to produce a honeycomb formed body having a shape in which two angles of two of the line segments are 90 ° and 135 ° respectively (a honeycomb formed body that is an outer honeycomb fired body), Use an extrusion mold.
In the following steps, the term “honeycomb molded body” refers to these two types of honeycomb molded bodies without distinction.

(2) Next, the honeycomb formed body is cut into a predetermined length and dried using a microwave dryer, hot air dryer, dielectric dryer, vacuum dryer, vacuum dryer, freeze dryer, or the like. Then, a sealing step of filling a predetermined cell with a sealing material paste as a sealing material and sealing the cell is performed.
Here, as a sealing material paste, the thing similar to the said wet mixture can be used.

(3) Thereafter, a degreasing step of heating the organic substance in the honeycomb formed body in a degreasing furnace is performed, and the organic material is conveyed to the firing furnace, and the firing step is performed, as shown in FIGS. 3 (a) and 3 (b). Such an inner honeycomb fired body and an outer honeycomb fired body as shown in FIGS. 4A and 4B are manufactured.
Moreover, the conditions currently used when manufacturing a honeycomb fired body can be applied to the conditions of a cutting process, a drying process, a sealing process, a degreasing process, and a firing process.

(4) Subsequently, an adhesive paste layer is formed by applying an adhesive paste to predetermined side surfaces of the inner honeycomb fired body and the outer honeycomb fired body in which predetermined end portions of the respective cells are sealed. Then, a step of laminating other honeycomb fired bodies sequentially on this adhesive paste layer is repeated to perform a binding step for producing a ceramic block in which a predetermined number of honeycomb fired bodies are bound.
Here, as the adhesive paste, for example, a paste made of an inorganic binder, an organic binder, and inorganic particles is used. The adhesive paste may further contain inorganic fibers and / or whiskers.

(5) After that, a coating layer forming step is performed in which a coating material paste is applied to the outer peripheral surface of the substantially cylindrical ceramic block, dried and solidified to form a coating layer.
When the coating material paste is applied to the outer peripheral surface of the ceramic block, the coating material paste is applied so as to fill the recesses provided in the outer honeycomb fired body.
Here, the above-mentioned adhesive paste can be used as the coating material paste. Note that a paste having a composition different from that of the adhesive paste may be used as the coating material paste.
Note that the coat layer is not necessarily provided, and may be provided as necessary.
Through the above steps, the honeycomb structure of the present embodiment can be manufactured.

Hereinafter, effects of the honeycomb structure of the present embodiment will be listed.
(1) In the honeycomb structure of the present embodiment, among the outer peripheral walls of the honeycomb fired body, the outer peripheral wall constituting the outer periphery of the ceramic block has a convex portion and a concave portion in a cross section perpendicular to the longitudinal direction of the honeycomb fired body. A step consisting of is provided.
Therefore, the number of incomplete cells located on the outermost peripheral portion of the honeycomb structure can be reduced. Thereby, since the cross-sectional area of the cell located in the outermost periphery part of a honeycomb structure can be increased, the filtration area increases, PM collection efficiency improves, and pressure loss also improves. Moreover, since the sealing material paste can be easily filled, sealing failure can be reduced and the manufacturing efficiency of the honeycomb structure can be improved.

(2) In the honeycomb structure of the present embodiment, the convex portions and / or the concave portions in the cross section perpendicular to the longitudinal direction of the honeycomb fired body are obtained by chamfering the convex portions and / or the concave portions of the outer peripheral wall. , A curve and / or a straight line.
Therefore, at the time of extrusion molding when producing a honeycomb formed body, the convex portion of the outer peripheral wall is missing due to insufficient amount of the wet mixture filled in the convex portion or concave portion of the mold, or the concave portion of the outer peripheral wall is Partial thinning can be prevented. In addition, the outer peripheral wall of the honeycomb molded body comes into contact with a conveying jig or the like during the drying step, the firing step, the binding step, etc. after extrusion for producing the honeycomb fired body constituting the honeycomb structure. In addition, because the protrusions present on the outer peripheral wall of the honeycomb molded body are missing, or the amount of the wet mixture filled in the concave portions of the outer peripheral wall is insufficient, due to expansion and contraction due to temperature changes during drying or firing, It is possible to prevent cracks from starting from the concave portion of the outer peripheral wall. As a result, defects in the honeycomb formed body and the honeycomb fired body are reduced, and the manufacturing efficiency of the honeycomb structure can be improved.
Further, during the process of manufacturing the honeycomb structure of the present embodiment, or when the honeycomb structure is used as a honeycomb filter, defects such as chips and cracks generated in the outer peripheral portion of the honeycomb structure are eliminated. Can be prevented.

Example 1
Examples that more specifically disclose the first embodiment of the present invention will be described below. In addition, this invention is not limited only to these Examples.

(1) A silicon carbide coarse powder of 52.8% by weight having an average particle size of 22 μm and a silicon carbide fine powder of 22.6% by weight of an average particle size of 0.5 μm were mixed, and the resulting mixture was mixed. 2.1% by weight of acrylic resin, 4.6% by weight of organic binder (methylcellulose), 2.8% by weight of lubricant (Unilube manufactured by NOF Corporation), 1.3% by weight of glycerin, and 13.8% by weight of water Was added and kneaded to obtain a wet mixture, followed by a molding step of extrusion molding.
In this step, a raw honeycomb molded body having substantially the same shape as the inner honeycomb fired body 110 shown in FIGS. 3 (a) and 3 (b) and having no cell sealing, and FIG. A raw honeycomb molded body having substantially the same shape as the outer honeycomb fired body 120 shown in FIGS. 4A and 4B and having no cell plugged was produced.

(2) Next, the dried honeycomb molded body was produced by drying the raw honeycomb molded body using a microwave dryer. After that, cells were sealed by filling predetermined cells of the dried honeycomb molded body with a sealing material paste having the same composition as the wet mixture. After sealing the cells, the dried honeycomb molded body filled with the plug paste was again dried using a dryer.

(3) A degreasing treatment was performed by degreasing the dried honeycomb molded body after cell sealing at 400 ° C., and further, a firing treatment was performed at 2200 ° C. under a normal pressure argon atmosphere for 3 hours.
Thereby, an inner honeycomb fired body and an outer honeycomb fired body were produced.
The inner honeycomb fired body is formed of a porous silicon carbide sintered body, having a porosity of 45%, an average pore diameter of 15 μm, a size of 34.5 mm × 34.5 mm × 150 mm, and the number of cells (cell density). 46.5 cells / cm ² (300 cells / inch ² ), a cell wall thickness of 0.25 mm (10 mil), and a cell width of 1.42 mm.
The outer honeycomb fired body is also composed of a porous silicon carbide sintered body, and the porosity, average pore diameter, number of cells (cell density), cell wall thickness, and cell width are the same as the inner honeycomb fired body. It is. In addition, the outer honeycomb fired body is surrounded by three line segments and one substantially circular arc, and two angles formed by two of the three line segments are 90 ° and 135 °, respectively. (Line segment 120a = 20.8 mm, line segment 120b = 35.0 mm, line segment 120c = 35.7 mm shown in FIG. 2). A substantially circular arc 120d of the outer honeycomb fired body is a stepped peripheral wall provided with a step including a convex portion and a concave portion. All convex portions and concave portions are rounded with a chamfer, and the radius of curvature of the rounded chamfer is 0.5 mm.

(4) Adhesive paste is applied to predetermined side surfaces of the inner honeycomb fired body and the outer honeycomb fired body, and four inner honeycomb fired bodies and eight outer honeycomb fired bodies are provided through the adhesive paste. The individual pieces were bonded so as to have the arrangement shown in FIG. 1 to produce an aggregate of honeycomb fired bodies.
Further, the aggregate of the honeycomb fired bodies was heated at 180 ° C. for 20 minutes to dry and solidify the adhesive paste, thereby producing a cylindrical ceramic block with an adhesive layer thickness of 1 mm.
Here, as the adhesive paste, 30.0% by weight of silicon carbide particles having an average particle diameter of 0.6 μm, 21.4% by weight of silica sol (solid content 30% by weight), 8.0% by weight of carboxymethyl cellulose, and water An adhesive paste consisting of 40.6% by weight was used.

(5) A coating material paste layer was formed on the outer periphery of the ceramic block using a coating material paste having the same composition as the adhesive paste used in the step (4). At this time, the coating material paste was applied so as to fill the recesses provided in the outer honeycomb fired body.
Thereafter, this coating material paste layer was dried and solidified at 120 ° C. to produce a cylindrical honeycomb structure having a diameter of 143.8 mm and a length of 150 mm, on which the coating layer was formed on the outer periphery.

(Second embodiment)
Hereinafter, a second embodiment which is an embodiment of the present invention will be described.
The inner honeycomb fired body and the outer honeycomb fired body constituting the honeycomb structure of the present embodiment are the same as the inner honeycomb fired body and the outer honeycomb fired body constituting the honeycomb structure of the first embodiment of the present invention. It has the outer shape. The method of combining the outer honeycomb fired body and the inner honeycomb fired body constituting the ceramic block (honeycomb structure) is the same as that of the first embodiment of the present invention.
In the first embodiment of the present invention, in the outer honeycomb fired body, the cells in contact with the outer peripheral wall and the cells not in contact with the outer peripheral wall have the same cross-sectional shape, whereas in the present embodiment, In the outer honeycomb fired body, the cells in contact with the step outer peripheral wall include incomplete cells having a different cross-sectional shape from the cells not in contact with the step outer peripheral wall.

In the present specification, a complete cell is a cell having one type of shape or a combination of a plurality of different shapes when the cells constituting the honeycomb fired body are observed in a cross section perpendicular to the longitudinal direction. This is the smallest unit cell that is formed at a certain repetition in the vertical and horizontal directions. For example, in the outer honeycomb fired body 120 shown in FIGS. 4A and 4B, substantially square figures are repeated in a cross section perpendicular to the longitudinal direction of the outer honeycomb fired body. In this case, a substantially square cell is called a complete cell. For example, in the inner honeycomb fired body 310 shown in FIG. 7A, two types of cells having different cell cross-sectional areas are repeated. In this case, both two types of cells having different cell cross-sectional areas are collectively referred to as a complete cell. However, for convenience, one of the two types of cells having different cell cross-sectional areas may be referred to as a complete cell.
In this specification, the basic formation pattern refers to the shape of the complete cell.

In the present specification, an incomplete cell is a kind of outer peripheral cell in contact with the outer peripheral wall of the outer honeycomb fired body, and the cells constituting the outer honeycomb fired body are observed in a cross section perpendicular to the longitudinal direction. In this case, the cell has a partially chipped shape compared to the shape of the complete cell and has a cell cross-sectional area smaller than the cell cross-sectional area of the complete cell. When the complete cell is a cell of one type, a cell having a smaller cross-sectional area than the complete cell is referred to as an incomplete cell. Further, in the outer honeycomb fired body in which the complete cell is a repeated pattern in which two or more types of cells having different cell cross-sectional areas are combined, for example, a cell smaller than a cell having a relatively large cell cross-sectional area A cell having a cross-sectional area or a cell having a smaller cross-sectional area than a cell having a relatively small cell cross-sectional area is referred to as an incomplete cell.

Hereinafter, the outer honeycomb fired body constituting the honeycomb structure of the second embodiment of the present invention will be described.
Fig.6 (a) is a perspective view which shows typically an example of the outer honeycomb fired body which comprises the honeycomb structure of 2nd embodiment of this invention. FIG. 6B is a side view of the outer honeycomb fired body shown in FIG.

In the outer honeycomb fired body 220 shown in FIGS. 6A and 6B, the cells 221, 227a to 227e are in the longitudinal direction across the cell wall 223 (the direction of the arrow c in FIG. 6A). And outer peripheral walls 224a to 224d are formed around the periphery. Any one of the end portions of the cells 221, 227 a to 227 e is sealed with a sealing material 222.
Of the outer peripheral walls 224a to 224d, the outer peripheral wall 224a constituting the outer periphery of the honeycomb structure (ceramic block) is a stepped outer peripheral wall provided with a step including a convex portion 225 and a concave portion 226.

In the outer honeycomb fired body 220, the cells 221, 227a to 227e are composed of outer peripheral cells 227a to 227e in contact with the outer peripheral walls 224a to 224d and inner cells 221 located inside the outer peripheral cells 227a to 227e.

The inner cell 221 is formed in a lattice shape as a basic formation pattern. Each of the inner cells 221 has a substantially square (substantially square) cross-sectional shape, and the cross-sectional areas are equal to each other. As described above, since the inner cells 221 are formed based on the basic formation pattern, they are all complete cells.

Out of the outer peripheral cells 227a to 227e, the outer peripheral cell 227a in contact with the outer peripheral wall 224a, the outer peripheral cell 227b in contact with the outer peripheral wall 224b, and the outer peripheral cell 227c in contact with the outer peripheral wall 224c have the same cross-sectional shape as the inner cell 221. . That is, the peripheral cells 227a, 227b, and 227c are complete cells. This is because the inner cell 221 is in contact with the outer peripheral wall 224a, 224b or 224c while maintaining its basic formation pattern, so that it can be considered that the inner cell 221 becomes the outer peripheral cell 227a, 227b or 227c as it is. is there.

On the other hand, the outer peripheral cells 227d and 227e are different from the inner cell 221 which is a complete cell in the cross-sectional shape. That is, the peripheral cells 227d and 227e are incomplete cells whose cross-sectional shapes are different from complete cells.
As described above, cells that are not formed based on the basic formation pattern, that is, cells that have a smaller cross-sectional size perpendicular to the longitudinal direction than the substantially square (substantially square) of the inner cell that is the basic formation pattern are incomplete. This is a cell.

As described above, in the present embodiment, the peripheral cell includes an incomplete cell having a cross-sectional shape different from the complete cell in addition to the complete cell.
The outer peripheral cell 227e, which is an incomplete cell, is provided in contact with the stepped outer peripheral wall 224a. Further, the outer peripheral cell 227d, which is an incomplete cell, is provided so as to be in contact with the outer peripheral wall 224d. As described above, the stepped peripheral wall 224a constitutes the outer periphery of the ceramic block. Therefore, the peripheral cell 227e is formed at a position in contact with the outer peripheral wall constituting the outer periphery of the ceramic block among the outer peripheral walls provided in the honeycomb fired body constituting the honeycomb structure.

From the above, regarding the peripheral cells, the cross-sectional shape of the peripheral cells excluding the incomplete cells is substantially quadrangular (substantially square) as in the inner cell, and the cross-sectional areas are equal to each other.

In the present embodiment, the outer peripheral cells in contact with the stepped outer peripheral wall of the outer honeycomb fired body only need to include at least one incomplete cell, and the number of incomplete cells is particularly limited as long as there is a step in the stepped outer peripheral wall. It is not limited. That is, the incomplete cell may be provided in consideration of the shape of the outer peripheral wall of the outer honeycomb fired body and the shape of the outer peripheral cell defined by the outer peripheral wall.

The cross-sectional area of the incomplete cell is not particularly limited, but the cross-sectional area of the incomplete cell may be a predetermined size that facilitates filling with the sealing material paste and does not cause a sealing failure.
Specifically, the incomplete cell is desirably a cell in which a circle having a diameter of 0.90 mm can be inserted into the inside of the cross-sectional shape perpendicular to the longitudinal direction of the cell, and the inside of the cross-sectional shape perpendicular to the longitudinal direction of the cell. It is more preferable that the cell has a diameter of 0.95 mm.
In such a case, it is easy to fill the cell with the sealing material paste, the sealing material does not leak or protrude, the incomplete cell can be sealed well, and sealing failure is unlikely to occur.

As in the first embodiment of the present invention, also in this embodiment, by chamfering the convex portion and / or the concave portion present on the stepped outer peripheral wall, in a cross section perpendicular to the longitudinal direction of the honeycomb fired body, The convex part and / or the concave part are constituted by a curve and / or a straight line.
6 (a) and 6 (b), the convex portions 225 and the concave portions 226 existing on the stepped outer peripheral wall 224a are chamfered, so that the convex portions are formed in a cross section perpendicular to the longitudinal direction of the honeycomb fired body. 225 and the recessed part 226 have shown the example comprised by the curve.

Moreover, in this embodiment, the corner | angular part is formed in the inner wall of an outer periphery cell, and the chamfering is given to the said corner | angular part.
It can be considered that the chamfering applied to the corners of the peripheral cell is provided with a filling portion at the corner of the peripheral cell. In that case, the cross-sectional shape of the filling portion is not particularly limited, but is preferably a substantially right triangle shape, or a shape in which the hypotenuse of the substantially right triangle is curved or bent toward the inside or the outside of the cell. . In particular, if the right triangle is an isosceles right triangle, the filling part has a symmetrical shape with respect to the corner, so the weight balance and heat conduction balance near the corner are good, and heat and force are efficiently distributed. This is desirable.

As the chamfered shape (cross-sectional shape perpendicular to the longitudinal direction of the cell) applied to the corner of the peripheral cell, the same shape as shown in FIGS. 5 (e) to 5 (h) can be considered. .
In that case, “the shape where the hypotenuse is curved or bent” means that, as shown in FIG. 5 (e), among the three vertices of a right triangle, two sharp vertices are connected and smoothly curved. Or, as shown in FIG. 5 (f), FIG. 5 (g), or FIG. 5 (h), formed by connecting two vertices that form an acute angle of a right triangle with one or more line segments Means.
Among the chamfers applied to the corners of the peripheral cells, R chamfering or C chamfering is desirable, and R chamfering is more desirable.

When R-chamfering is performed on the corners of the peripheral cells, the desired lower limit of the radius of curvature of the R-chamfering is 0.3 mm, the more desirable lower limit is 0.5 mm, and the desirable upper limit is 2.5 mm.
If the radius of curvature of the R chamfer is less than 0.3 mm, it may not be possible to sufficiently suppress the concentration of stress on the convex portion or the concave portion. On the other hand, if the radius of curvature of the R chamfer exceeds 2.5 mm, the roundness of the corners of the outer peripheral cell is too large, and on the contrary, cracks may easily occur.

When C-chamfering is performed on the corners of the peripheral cells, the desirable lower limit is 0.3 mm, and the more desirable lower limit is 0.5 mm, while the desirable upper limit is 2.5 mm.

The chamfering applied to the corners of the peripheral cells only needs to be applied to at least one corner of the peripheral cells. Therefore, chamfering may be applied to corners of complete cells, or chamfering may be applied to corners of incomplete cells. Among the peripheral cells, it is desirable that the corners of the peripheral cells in contact with the stepped peripheral wall are chamfered.

In addition, the position of the chamfered cell is not limited, but the corner portion constituted by the step outer peripheral wall and the corner portion constituted by the step outer peripheral wall and the cell wall should be chamfered. desirable.
The “corner portion constituted by the step outer peripheral wall” refers to a corner portion closest to the convex portion of the step outer peripheral wall among the corner portions of the outer peripheral cell in contact with the step outer peripheral wall. In addition, the “corner portion constituted by the step outer peripheral wall and the cell wall” refers to a corner portion present at the branch portion between the step outer peripheral wall and the cell wall among the corner portions of the outer peripheral cell that contacts the step outer peripheral wall. . In the outer honeycomb fired body 220 shown in FIG. 6B, among the corner portions 228a to 228d of the outer peripheral cell 227a, the corner portion 228a corresponds to the “corner portion constituted by the stepped outer peripheral wall”, and the corner portion 228d. Corresponds to “a corner portion constituted by a stepped peripheral wall and a cell wall”.

Next, an inner honeycomb fired body constituting the honeycomb structure according to the second embodiment of the present invention will be described.
The inner honeycomb fired body is the same as the inner honeycomb fired body described in the first embodiment of the present invention.
All the cells provided in the inner honeycomb fired body are complete cells. Further, chamfering may or may not be applied to the corners of the outer peripheral cells (referred to as cells contacting the outer peripheral wall of the inner honeycomb fired body) in the inner honeycomb fired body.

In the method for manufacturing a honeycomb structured body of the present embodiment, the method is the same as that of the first embodiment of the present invention except that a honeycomb molded body having a predetermined shape is manufactured by changing the shape of a mold used for extrusion molding. Thus, a honeycomb structure can be manufactured.

In the present embodiment, the effects (1) and (2) described in the first embodiment of the present invention can be exhibited, and the following effects can be exhibited.
(3) In the honeycomb structure of the present embodiment, the peripheral cell in contact with the stepped peripheral wall includes incomplete cells. Therefore, in the cross section perpendicular to the longitudinal direction of the honeycomb fired body, the number of convex portions or concave portions of the stepped outer peripheral wall of the honeycomb fired body can be reduced. As a result, at the time of extrusion molding, the amount of the wet mixture filled in the convex portion or concave portion of the mold is insufficient, so that the convex portion of the outer peripheral wall is missing, or the concave portion of the outer peripheral wall is partially thinned. Can be prevented. In addition, during the drying process or the firing process after extrusion, the protrusions present on the outer peripheral wall of the honeycomb molded body or the honeycomb fired body are missing due to contact with a jig or the like during transportation, or exposed to high temperatures. When the honeycomb fired body is expanded and contracted, it is possible to further prevent cracks from starting from the convex portions and / or concave portions of the outer peripheral wall.
Moreover, when such a honeycomb structure is used as an exhaust gas purification filter, a filtration area capable of collecting PM can be improved, and pressure loss can be reduced.

(4) In the honeycomb structure of the present embodiment, the corners of the peripheral cells (corners formed on the inner walls of the peripheral cells) are chamfered. When the corners of the peripheral cells are chamfered, the stress is relieved compared to the case where the corners of the peripheral cells are sharp. Therefore, it starts from a chip in the convex portion of the outer peripheral wall due to contact with a jig or the like during conveyance, or a convex portion and / or a concave portion of the outer peripheral wall due to expansion and contraction of the honeycomb fired body when exposed to a high temperature. Generation of cracks and the like can be further prevented.

(5) In the honeycomb structure of the present embodiment, the chamfered corners are corners constituted by stepped outer peripheral walls and corners constituted by stepped outer peripheral walls and cell walls.
Of the corners of the peripheral cells, the corners formed by the stepped outer peripheral wall and the corners formed by the stepped outer peripheral wall and the cell wall are chamfered. The stress added to the convex part or the concave part which has can be relieved. Therefore, generation | occurrence | production of the crack etc. which start from the chip | tip in the convex part of an outer peripheral wall or the convex part and / or recessed part of an outer peripheral wall can be prevented more.
In addition, since the thickness of the stepped outer peripheral wall of the honeycomb fired body can be made substantially the same including the thickness of the outer peripheral wall of the convex portion, deformation of the outer peripheral wall of the honeycomb molded body during extrusion molding can be prevented. .

(6) In the honeycomb structure of the present embodiment, the chamfering applied to the corner is R chamfering, and the radius of curvature of the R chamfering is 0.3 to 2.5 mm.
R chamfering is excellent in stress relaxation because the corners of the peripheral cells are chamfered into a curved shape in a cross section perpendicular to the longitudinal direction of the honeycomb fired body. Accordingly, it is possible to further prevent the occurrence of cracks and the like starting from the convex portion and / or the concave portion of the outer peripheral wall.

(Third embodiment)
Hereinafter, a third embodiment which is an embodiment of the present invention will be described.
The inner honeycomb fired body and the outer honeycomb fired body constituting the honeycomb structure of the present embodiment are the same as the inner honeycomb fired body and the outer honeycomb fired body constituting the honeycomb structure of the second embodiment of the present invention. It has the outer shape. The combination of the outer honeycomb fired body and the inner honeycomb fired body constituting the ceramic block (honeycomb structure) is also the same as in the second embodiment of the present invention.
In the present embodiment, in the inner honeycomb fired body and the outer honeycomb fired body, the outer peripheral cell and the inner cell excluding the incomplete cells are composed of a large capacity cell and a small capacity cell. The area of the cross section perpendicular to the direction is larger than the area of the cross section perpendicular to the longitudinal direction of the small capacity cell.

Fig.7 (a) is a side view which shows typically an example of the inner honeycomb fired body which comprises the honeycomb structure of 3rd embodiment of this invention. FIG. 7B is a side view schematically showing an example of the outer honeycomb fired body constituting the honeycomb structure of the third embodiment of the present invention.

First, the inner honeycomb fired body will be described.
In the inner honeycomb fired body 310 shown in FIG. 7A, cells 311a and 311b are arranged side by side across the cell wall 313, and outer peripheral walls 314a to 314d are formed around the cells 311a and 311b. The cells 311a and 311b include a large-capacity cell 311a and a small-capacity cell 311b. The cross-sectional area of the large-capacity cell 311a (the cross-sectional area perpendicular to the longitudinal direction) is larger than the cross-sectional area of the small-capacity cell 311b. ing. The large capacity cells 311a and the small capacity cells 311b are alternately arranged.
7A, the large capacity cell 311a has a substantially octagonal cross section, and the small capacity cell 311b has a substantially quadrangular cross section. Thus, since the cells 311a and 311b are formed based on the basic formation pattern, it can be said that they are complete cells.

In the large-capacity cell 311a, one end face side end portion of the inner honeycomb fired body 310 is opened, and the other end face side end portion is sealed with a sealing material (not shown). On the other hand, the small-capacity cell 311b is sealed with a sealing material 312 at one end face side of the inner honeycomb fired body 310, and the other end face side end is opened.
Therefore, the exhaust gas flowing into the large-capacity cell 311a always passes through the cell wall 313 that separates the large-capacity cell 311a and the small-capacity cell 311b, and then flows out from the small-capacity cell 311b. Functions as a filter.

Next, the outer honeycomb fired body will be described.
Also in the outer honeycomb fired body 320 shown in FIG. 7 (b), the cells 321a, 321b, 327a to 327e are arranged in parallel with the cell wall 323 therebetween, as in the inner honeycomb fired body. 324a to 324d are formed.
Of the outer peripheral walls 324a to 324d, the outer peripheral wall 324a constituting the outer periphery of the honeycomb structure (ceramic block) is a stepped outer peripheral wall provided with a step formed by a convex portion 325 and a concave portion 326.

In the outer honeycomb fired body 320, the cells 321a, 321b, 327a to 327e are composed of outer peripheral cells 327a to 327e in contact with the outer peripheral walls 324a to 324d, and inner cells 321a and 321b located inside the outer peripheral cells 327a to 327e. .

The inner cells 321a and 321b of the outer honeycomb fired body 320 are complete cells, similar to the cells 311a and 311b provided in the inner honeycomb fired body 310. That is, the inner cells 321a and 321b, which are complete cells, are composed of a large capacity cell 321a and a small capacity cell 321b, and the cross sectional area of the large capacity cell 321a (the area of the cross section perpendicular to the longitudinal direction) is small capacity cell 321b. The cross-sectional area is larger.
In the large capacity cell 321a, one end face side end of the outer honeycomb fired body 320 is opened, and the other end face side end is sealed with a sealing material (not shown). On the other hand, the small-capacity cell 321b is sealed with a sealing material 322 at one end face side of the outer honeycomb fired body 320, and the other end face side end is opened.
Therefore, the exhaust gas flowing into the large capacity cell 321a always passes through the cell wall 323 that separates the large capacity cell 321a and the small capacity cell 321b, and then flows out from the small capacity cell 321b. Functions as a filter.

Out of the peripheral cells 327a to 327e of the outer honeycomb fired body 320, the outer peripheral cell 327a that is in contact with the outer peripheral wall 324a, the outer peripheral cell 327b that is in contact with the outer peripheral wall 324b, and the outer peripheral cell 327c that is in contact with the outer peripheral wall 324c are 320 has the same cross-sectional shape as the large-capacity cell 321a which is the inner cell of 320. That is, the outer peripheral cells 327a, 327b, and 327c of the outer honeycomb fired body 320 are complete cells.
On the other hand, among the outer peripheral cells 327a to 327e of the outer honeycomb fired body 320, the outer peripheral cell 327d and the outer peripheral cell 327e have cross-sectional shapes that are inner cells of the outer honeycomb fired body 320 and are complete cells. This is different from the large capacity cell 321a. That is, the outer peripheral cells 327d and 327e of the outer honeycomb fired body 320 are incomplete cells having a cross-sectional shape different from that of a complete cell.
That is, in the outer honeycomb fired body 320 shown in FIG. 7B, the peripheral cell includes incomplete cells having a cross-sectional shape different from the complete cell in addition to the complete cell.
The outer peripheral cell 327e which is an incomplete cell is provided so as to be in contact with the step outer peripheral wall 324a. Further, the outer peripheral cell 327d that is an incomplete cell is provided so as to be in contact with the outer peripheral wall 324d.
In the outer honeycomb fired body 320 shown in FIG. 7B, the outer peripheral cells excluding incomplete cells are composed of large-capacity cells and small-capacity cells, like the inner cells.

In the present embodiment, the angular cell may not include an incomplete cell. In that case, it can be said that this embodiment is a form in which a cell having a cross-sectional area is used as the cell shape of the first embodiment of the present invention.

As a cross-sectional shape of the large-capacity cell and the small-capacity cell, the cross-sectional area of the large-capacity cell may be larger than that of the small-capacity cell. Therefore, the cross-sectional shapes of the large-capacity cell and the small-capacity cell are not limited to shapes that are substantially octagonal and substantially quadrangular, respectively, and any cross-sectional shape can be adopted. For example, the following shapes may be used.
Fig. 8 (a) is a side view schematically showing another example of the inner honeycomb fired body constituting the honeycomb structure according to the third embodiment of the present invention. FIG. 8B is a side view schematically showing another example of the outer honeycomb fired body constituting the honeycomb structure of the third embodiment of the present invention.
In the inner honeycomb fired body 330 shown in FIG. 8 (a) and the outer honeycomb fired body 340 shown in FIG. 8 (b), the cross-sectional shape of the large-capacity cell is a substantially square (substantially square). The cross-sectional shape is substantially a quadrangle (substantially square).

The cross-sectional shapes of the large-capacity cell and the small-capacity cell may have a right-angle portion, and the portion corresponding to the right-angle portion is a circular arc (a shape in which the cell is pseudo R-chamfered) or C-chamfered. It may be a shape (a shape in which a cell is pseudo-chamfered).

Also in this embodiment, as in the first embodiment and the second embodiment of the present invention, the chamfering is applied to the convex portion and / or the concave portion existing on the stepped outer peripheral wall, so that the length of the honeycomb fired body is increased. In the cross section perpendicular to the direction, the convex portion and / or the concave portion are constituted by a curved line and / or a straight line.
In the outer honeycomb fired body 320 shown in FIG. 7B, the chamfering is applied to the convex portion 325 and the concave portion 326 present on the stepped outer peripheral wall 324a, so that in the cross section perpendicular to the longitudinal direction of the honeycomb fired body, The example in which the convex part 325 and the recessed part 326 are comprised by the curve is shown. Similarly, in the outer honeycomb fired body 340 shown in FIG. 8B, the convex portions 345 and the concave portions 346 present on the stepped outer peripheral wall 344a are chamfered, so that the vertical direction of the honeycomb fired body is perpendicular to the longitudinal direction. In the cross section, an example in which the convex portion 345 and the concave portion 346 are configured by curves.

In the outer honeycomb fired body constituting the honeycomb structure of the present embodiment, the corner portions of the peripheral cells may be chamfered or chamfered as in the second embodiment of the present invention. It does not have to be.
Also in the inner honeycomb fired body constituting the honeycomb structure of the present embodiment, the corners of the peripheral cells may be chamfered or may not be chamfered.

In the method for manufacturing a honeycomb structured body of the present embodiment, the method is the same as that of the first embodiment of the present invention except that a honeycomb molded body having a predetermined shape is manufactured by changing the shape of a mold used for extrusion molding. Thus, a honeycomb structure can be manufactured.

Also in this embodiment, the effects (1) and (2) described in the first embodiment of the present invention and the effects (3) to (6) described in the second embodiment of the present invention can be exhibited. it can.

(Fourth embodiment)
Hereinafter, a fourth embodiment which is an embodiment of the present invention will be described.
In this embodiment, the outer shape of the inner honeycomb fired body is the same as that of the first to third embodiments of the present invention, but the outer shape of the outer honeycomb fired body is the first embodiment of the present invention. -Different from the third embodiment.
Specifically, in this embodiment, the combination structure of the honeycomb fired bodies is different from the first to third embodiments of the present invention. That is, a honeycomb fired body having a substantially square (substantially square) cross-sectional shape is used as the inner honeycomb fired body, and a plurality of types of honeycomb fired bodies having a predetermined shape having different cross-sectional shapes are used as the outer honeycomb fired body. A ceramic block having a predetermined shape (for example, a substantially circular cross section) can be formed by assembling the inner honeycomb fired body and a plurality of types of outer honeycomb fired bodies through the adhesive layer.

FIG. 9 is a side view schematically showing an example of the honeycomb structure of the fourth embodiment of the present invention.
FIGS. 10A and 10B are side views schematically showing an example of the outer honeycomb fired body constituting the honeycomb structure according to the fourth embodiment of the present invention.

The honeycomb structure 400 shown in FIG. 9 includes eight outer honeycomb fired bodies 420 having three straight lines as shown in FIG. 10A and two straight lines as shown in FIG. 10B. Four outer honeycomb fired bodies 430 having a shape and four inner honeycomb fired bodies 410 arranged on the inner side thereof are bonded through adhesive layers 401A to 401D to form a ceramic block 403. Further, a coat layer 402 is formed on the outer periphery of the ceramic block 403. In addition, the coat layer should just be formed as needed.

As shown in FIG. 9, the shape of the cross section of the inner honeycomb fired body 410 is a substantially square (substantially square).
Further, as shown in FIG. 9, the cross section of the outer honeycomb fired body 420 has a shape surrounded by three line segments 420a, 420b, 420c and one substantially arc 420d. Two angles formed by two of the three line segments (an angle formed by the line segment 420b and the line segment 420c and an angle formed by the line segment 420a and the line segment 420b) are both 90 °. It is.
Furthermore, the cross section of the outer honeycomb fired body 430 has a shape surrounded by two line segments 430a and 430b and one substantially arc 430c. The angle formed by these two line segments (the angle formed by the line segments 430a and 430b) is 90 °.
Moreover, the honeycomb fired bodies 410, 420, and 430 are desirably porous bodies made of silicon carbide or silicon-containing silicon carbide.

Also in this embodiment, as in the first to third embodiments of the present invention, of the outer peripheral walls of the outer honeycomb fired body, the outer peripheral wall constituting the outer periphery of the honeycomb structure (ceramic block) is a honeycomb. In the cross section perpendicular to the longitudinal direction of the fired body, a stepped outer peripheral wall is provided with a step formed by a convex portion and a concave portion.
In the outer honeycomb fired body 420 shown in FIG. 10 (a), of the outer peripheral walls 424a to 424d formed around the outer peripheral wall 424a, the outer peripheral wall 424a constituting the outer periphery of the honeycomb structure (ceramic block) has a convex portion 425 and a concave portion. A step outer peripheral wall provided with a step consisting of 426 is provided.
Further, in the outer honeycomb fired body 430 shown in FIG. 10B, the outer peripheral wall 434 a that constitutes the outer periphery of the honeycomb structure (ceramic block) among the outer peripheral walls 434 a to 434 c formed around the convex portion 435. And a stepped outer peripheral wall provided with a step formed by a recess 436.

And by chamfering the convex part and / or the concave part of the outer peripheral wall, the convex part and / or the concave part is constituted by a curve and / or a straight line in a cross section perpendicular to the longitudinal direction of the honeycomb fired body. Yes.
In the outer honeycomb fired body 420 shown in FIG. 10 (a), the convex portions 425 and the concave portions 426 existing on the stepped outer peripheral wall 424a are chamfered, so that in a cross section perpendicular to the longitudinal direction of the honeycomb fired body, The example which the convex part 425 and the recessed part 426 are comprised by the curve is shown. Similarly, in the outer honeycomb fired body 430 shown in FIG. 10 (b), the convex portions 435 and the concave portions 436 existing on the stepped peripheral wall 434a are chamfered, so that they are perpendicular to the longitudinal direction of the honeycomb fired body. In the cross section, an example in which the convex portion 435 and the concave portion 436 are configured by curves.

The cross-sectional shapes of the cells provided in the outer honeycomb fired body are all substantially square (substantially square) as in the first and second embodiments of the present invention, and the cross-sectional areas of the cells are mutually The same shape may be sufficient, and the shape which consists of a large capacity cell and a small capacity cell may be sufficient like 3rd embodiment of this invention.

In addition, in the outer honeycomb fired body 420 shown in FIG. 10 (a) and the outer honeycomb fired body 430 shown in FIG. 10 (b), the cell cross-sectional shape in contact with the outer peripheral wall and the outer peripheral wall are not in contact. The cross-sectional shape of the cell is the same. However, in the present embodiment, as in the second embodiment of the present invention, the outer peripheral cell in contact with the outer peripheral wall may include an incomplete cell.
Further, the corner portions of the outer peripheral cells of the outer honeycomb fired body may or may not be chamfered as in the second embodiment of the present invention.

The inner honeycomb fired body may be the same as the inner honeycomb fired body described in the first to third embodiments of the present invention, corresponding to the configuration of the outer honeycomb fired body.
Further, in the inner honeycomb fired body, the corner portions of the outer peripheral cells may be chamfered or may not be chamfered.

In the method for manufacturing a honeycomb structure according to the present embodiment, the shape of a mold used for extrusion molding is changed to produce a honeycomb molded body having a predetermined shape, and the inner honeycomb is formed when the binding process is performed. A honeycomb structure can be manufactured in the same manner as in the first embodiment of the present invention except that the fired body and the outer honeycomb fired body are bundled at predetermined positions.

Also in this embodiment, the effects (1) and (2) described in the first embodiment of the present invention and the effects (3) to (6) described in the second embodiment of the present invention can be exhibited. it can.

(Fifth embodiment)
Hereinafter, a fifth embodiment which is an embodiment of the present invention will be described.
In this embodiment, the outer shape of the inner honeycomb fired body is the same as that of the first embodiment to the fourth embodiment of the present invention, but the outer shape of the outer honeycomb fired body is the first embodiment of the present invention. -Different from the fourth embodiment.
In this embodiment, a honeycomb fired body having a substantially square (substantially square) cross-sectional shape is used as the inner honeycomb fired body, and a plurality of types of honeycomb fired bodies having different shapes having different cross-sectional shapes are used as the outer honeycomb fired body. The point of use is the same as that of the fourth embodiment of the present invention, but the combined structure of the honeycomb fired bodies is different from that of the first to fourth embodiments of the present invention.
Specifically, the number of inner honeycomb structures constituting the honeycomb structure is larger than the number of inner honeycomb structures constituting the honeycomb structures of the first to fourth embodiments of the present invention.

FIG. 11 is a side view schematically showing an example of the honeycomb structure of the fifth embodiment of the present invention.
12 (a) and 12 (b) are side views schematically showing an example of an outer honeycomb fired body constituting the honeycomb structure of the fifth embodiment of the present invention.

A honeycomb structure 500 shown in FIG. 11 includes eight outer honeycomb fired bodies 520 having a shape including three straight lines as shown in FIG. 12 (a) and three straight lines as shown in FIG. 12 (b). A plurality of shaped outer honeycomb fired bodies 530 and nine inner honeycomb fired bodies 510 arranged on the inside thereof are bonded together via adhesive layers 501 and 501A to 501D to form a ceramic block 503. Furthermore, a coat layer 502 is formed on the outer periphery of the ceramic block 503. In addition, the coat layer should just be formed as needed.

As shown in FIG. 11, the shape of the cross section of the inner honeycomb fired body 510 is a substantially square (substantially square).
Further, as shown in FIG. 11, the cross section of the outer honeycomb fired body 520 has a shape surrounded by three line segments 520a, 520b, and 520c and one substantially arc 520d. Two angles formed by two of the three line segments (an angle formed by the line segment 520a and the line segment 520b and an angle formed by the line segment 520b and the line segment 520c) are both 90 °. .
The cross section of the outer honeycomb fired body 530 is a substantially fan-shaped unit surrounded by three line segments 530a, 530b, and 530c and one substantially arc 530d. Two angles formed by two of the three line segments (an angle formed by the line segment 530b and the line segment 530c and an angle formed by the line segment 530a and the line segment 530b) are 90 ° and 135, respectively. °.
In addition, the honeycomb fired bodies 510, 520, and 530 are desirably porous bodies made of silicon carbide or silicon-containing silicon carbide.

Also in this embodiment, the outer peripheral wall constituting the outer periphery of the honeycomb structure (ceramic block) among the outer peripheral walls of the outer honeycomb fired body is the same as in the first to fourth embodiments of the present invention. In the cross section perpendicular to the longitudinal direction of the fired body, a stepped outer peripheral wall is provided with a step formed by a convex portion and a concave portion.
In the outer honeycomb fired body 520 shown in FIG. 12 (a), of the outer peripheral walls 524a to 524d formed around the outer peripheral wall 524a constituting the outer periphery of the honeycomb structure (ceramic block), the convex portion 525 and the concave portion are formed. The outer peripheral wall of the step is provided with a step consisting of 526.
Further, in the outer honeycomb fired body 530 shown in FIG. 12B, the outer peripheral wall 534 a constituting the outer periphery of the honeycomb structure (ceramic block) among the outer peripheral walls 534 a to 534 d formed around the convex portion 535. And a stepped outer peripheral wall provided with a step formed by a recess 536.

And by chamfering the convex part and / or the concave part of the outer peripheral wall, the convex part and / or the concave part is constituted by a curve and / or a straight line in a cross section perpendicular to the longitudinal direction of the honeycomb fired body. Yes.
In the outer honeycomb fired body 520 shown in FIG. 12 (a), the convex portion 525 and the concave portion 526 existing on the stepped outer peripheral wall 524a are chamfered, so that in a cross section perpendicular to the longitudinal direction of the honeycomb fired body, The example which the convex part 525 and the recessed part 526 are comprised by the curve is shown. Similarly, in the outer honeycomb fired body 530 shown in FIG. 12 (b), the convex portions 535 and the concave portions 536 existing on the stepped outer peripheral wall 534a are chamfered, so that they are perpendicular to the longitudinal direction of the honeycomb fired body. In the cross section, an example in which the convex portion 535 and the concave portion 536 are configured by curves.

The cross-sectional shapes of the cells provided in the outer honeycomb fired body are all substantially square (substantially square) as in the first and second embodiments of the present invention, and the cross-sectional areas of the cells are mutually The same shape may be sufficient, and the shape which consists of a large capacity cell and a small capacity cell may be sufficient like 3rd embodiment of this invention.

In addition, in the outer honeycomb fired body 520 shown in FIG. 12 (a) and the outer honeycomb fired body 530 shown in FIG. 12 (b), the cell cross-sectional shape in contact with the outer peripheral wall and the outer peripheral wall are not in contact. The cross-sectional shape of the cell is the same. However, in the present embodiment, as in the second embodiment of the present invention, the outer peripheral cell in contact with the outer peripheral wall may include an incomplete cell.
Further, the corner portions of the outer peripheral cells of the outer honeycomb fired body may or may not be chamfered as in the second embodiment of the present invention.

The inner honeycomb fired body may be the same as the inner honeycomb fired body described in the first to fourth embodiments of the present invention, corresponding to the configuration of the outer honeycomb fired body.
Further, in the inner honeycomb fired body, the corner portions of the outer peripheral cells may be chamfered or may not be chamfered.

In the method for manufacturing a honeycomb structure according to the present embodiment, the shape of a mold used for extrusion molding is changed to produce a honeycomb molded body having a predetermined shape, and the inner honeycomb is formed when the binding process is performed. A honeycomb structure can be manufactured in the same manner as in the first embodiment of the present invention except that the fired body and the outer honeycomb fired body are bundled at predetermined positions.

Also in this embodiment, the effects (1) and (2) described in the first embodiment of the present invention and the effects (3) to (6) described in the second embodiment of the present invention can be exhibited. it can.

(Other embodiments)
In the first embodiment of the present invention, in the outer honeycomb fired body and the inner honeycomb fired body constituting the honeycomb structure, the corners of the peripheral cells are not chamfered. However, also in the outer honeycomb fired body 120 shown in FIGS. 4A and 4B, the corners of the peripheral cells may be chamfered as in the second embodiment of the present invention. . Further, also in the inner honeycomb fired body 110 shown in FIGS. 3A and 3B, the corners of the peripheral cells may be chamfered.

In the honeycomb structure of the present invention, when the ceramic block is composed of an inner honeycomb fired body and an outer honeycomb fired body, the number of inner honeycomb fired bodies is not limited to a plurality, and is one. May be.
Specifically, as shown in FIG. 13, the honeycomb structure has a cross-sectional shape of one honeycomb fired body positioned at the center of the honeycomb structure and honeycomb fired positioned at the outer periphery of the honeycomb structure. The shape which consists of a body may be sufficient.
FIG. 13 is a side view schematically showing an example of a honeycomb structure according to another embodiment of the present invention.

The configuration of the honeycomb structure 600 shown in FIG. 13 is the same as that of the honeycomb structure 100 shown in FIGS. 1 and 2 except that the number of inner honeycomb fired bodies is different.
That is, in the honeycomb structure 600 shown in FIG. 13, instead of the four inner honeycomb fired bodies 110 bound through the adhesive layer 101A of the honeycomb structure 100 shown in FIG. A honeycomb fired body 610 is provided.
Although the inner honeycomb fired body 610 shown in FIG. 13 has a larger cross-sectional area than the inner honeycomb fired body 110 shown in FIG. 2, its function is the same. The outer honeycomb fired body 620 shown in FIG. 13 is the same as the honeycomb fired body 120 constituting the honeycomb structure 100 shown in FIG.

In the honeycomb structure of the present invention, when the ceramic block is composed of the inner honeycomb fired body and the outer honeycomb fired body, the cross-sectional area of the cross section perpendicular to the longitudinal direction of the inner honeycomb fired body is 900 to 2500 mm. ² is desirable.
When the cross-sectional area of the inner honeycomb fired body is in the above range, when the honeycomb structure is used as a honeycomb filter, the honeycomb fired body is expanded and contracted when exposed to a high temperature such as a regeneration process. This is because cracks are hardly generated in the honeycomb fired body.

In the honeycomb structure of the present invention, the ceramic block may not be composed of the inner honeycomb fired body and the outer honeycomb fired body.
For example, the cross-sectional shape of the honeycomb structure may be a shape as shown in FIG.
FIG. 14 is a side view schematically showing another example of a honeycomb structure of another embodiment of the present invention.
In the honeycomb structure 700 shown in FIG. 14, one type of honeycomb fired body 710 is bundled together through adhesive layers 701 </ b> A to 701 </ b> D to form a ceramic block 703, and the outer periphery of the ceramic block 703 is coated. A layer 702 is formed.
In the honeycomb structure 700 shown in FIG. 14, the honeycomb fired body 710 has a cake-like shape and the ceramic block 703 is divided into four parts. However, in the honeycomb structure of the present invention, the ceramic block is divided. The number of honeycomb fired bodies is not particularly limited.

In the honeycomb structured body of the present invention, the ceramic block may be composed of a honeycomb fired body having a cake shape. The number of the honeycomb fired bodies having a cake-like shape may be one or plural, and the number is not particularly limited.
The cake-like shape refers to the shape of one columnar body obtained by cutting a cylinder into a plurality of pieces so as to pass through its central axis. When a plurality of cake-like honeycomb fired bodies are combined, a cylindrical shape is obtained.
Furthermore, in the honeycomb structure of the present invention, the ceramic block may be composed of one honeycomb fired body. When the ceramic block is composed of one honeycomb fired body, the honeycomb fired body is preferably made of cordierite or aluminum titanate. Even when the ceramic block is composed of one honeycomb fired body, it is considered that the same effect as that obtained when the ceramic block is composed of a plurality of honeycomb fired bodies is obtained.

In the present invention, of the outer peripheral walls of the honeycomb fired body, the outer peripheral wall constituting the outer periphery of the ceramic block has a stepped outer periphery provided with a step formed by a convex portion and a concave portion in a cross section perpendicular to the longitudinal direction of the honeycomb fired body. As long as it is a wall, the ceramic block may consist of one honeycomb fired body or a combination of honeycomb fired bodies of any shape.

In the honeycomb structure of the present invention, when a complete cell is composed of a large capacity cell and a small capacity cell, the form of the large capacity cell and the small capacity cell is not limited to the form described in the previous embodiments. Absent.
FIGS. 15A and 15B are side views schematically showing an example of an end face of the inner honeycomb fired body constituting the honeycomb structure according to the embodiment of the present invention.
Each of these drawings is a side view as seen from one end face side of the inner honeycomb fired body, that is, from the end face side where the small-capacity cells are sealed.
Other embodiments of the cross-sectional shapes of the large capacity cell and the small capacity cell will be described with reference to these drawings.

In the inner honeycomb fired body 810 shown in FIG. 15 (a), the shape of the cross section perpendicular to the longitudinal direction of the large capacity cell 811a is a substantially quadrangular shape in which the portion corresponding to the corner is arcuate. The shape of the cross section perpendicular to the longitudinal direction of the capacity cell 811b is substantially rectangular.

In the inner honeycomb fired body 820 shown in FIG. 15B, the cross section perpendicular to the longitudinal direction of the large capacity cell 821a and the small capacity cell 821b has a shape in which each side of the cell is constituted by a curve.
That is, in FIG.15 (b), the cross-sectional shape of the cell wall 823 shown with the continuous line is a curve.
The cross-sectional shape of the large-capacity cell 821a is a shape in which the cell wall 823 is convex outward from the center of the cell cross-section, while the cross-sectional shape of the small-capacity cell 821b is the cell wall 823 from the outside of the cell cross-section. Convex shape toward the center.
The cell wall 823 has a “corrugated” shape that undulates in the horizontal direction and the vertical direction of the cross section of the inner honeycomb fired body, and the corrugated crest portion of the adjacent cell wall 823 (the amplitude referred to as a sine curve). Are located closest to each other, thereby forming a large-capacity cell 821a in which the cross-sectional shape of the cell expands outward and a small-capacity cell 821b in which the cross-sectional shape of the cell is recessed inward. The amplitude of the waveform may be constant or may vary, but is preferably constant.

The outer honeycomb fired body may also have a cross-sectional shape of a large-capacity cell and a small-capacity cell as shown in FIG. 15 (a) or FIG. 15 (b). When the outer peripheral cells of the outer honeycomb fired body include incomplete cells, the outer peripheral cells excluding the incomplete cells and the inner cells are as shown in FIG. 15A or FIG. 15B. It is only necessary to have a cross-sectional shape of a large capacity cell and a small capacity cell.

In the honeycomb structure of the present invention, the thickness of the outer peripheral wall of the step may be the same as the thickness of the cell wall or may be larger than the thickness of the cell wall.
When the thickness of the step outer peripheral wall is larger than the thickness of the cell wall, the thickness of the step outer peripheral wall is desirably 1.3 to 3.0 times the thickness of the cell wall.

The shape of the honeycomb structure of the present invention is not limited to a substantially cylindrical shape, and may be any column shape such as a substantially elliptical column shape or a substantially polygonal column shape.

In the honeycomb structure of the present invention, the ends of the cells may not be sealed. Such a honeycomb structure can be used as a catalyst carrier.

In the honeycomb structure of the present invention, when the honeycomb structure is used as a filter, the porosity of the honeycomb fired body constituting the honeycomb structure is not particularly limited, but is preferably 35 to 60%.
When the porosity of the honeycomb fired body is less than 35%, the filter may be clogged immediately. On the other hand, if the porosity of the honeycomb fired body exceeds 60%, the strength of the honeycomb fired body is reduced, and thus the filter may be easily broken.

Further, in the honeycomb structure of the present invention, when the honeycomb structure is used as a filter, the average pore diameter of the honeycomb fired body constituting the honeycomb structure is preferably 5 to 30 μm.
When the average pore diameter of the honeycomb fired body is less than 5 μm, the filter may easily be clogged. On the other hand, if the average pore diameter of the honeycomb fired body exceeds 30 μm, the particulates may pass through the pores, and the honeycomb fired body may not collect the particulates and may not function as a filter. It is.

The porosity and pore diameter can be measured by, for example, a conventionally known mercury porosimetry.

The cell density in the cross section of the honeycomb fired body of the present invention is not particularly limited, but a desirable lower limit is 31.0 / cm ² (200 / inch ² ), and a desirable upper limit is 93.0 / cm ² (600 Pieces / inch ² ), a more desirable lower limit is 38.8 pieces / cm ² (250 pieces / inch ² ), and a more desirable upper limit is 77.5 pieces / cm ² (500 pieces / inch ² ).
Further, the thickness of the cell wall of the honeycomb fired body is not particularly limited, but is desirably 0.1 to 0.4 mm.

In the honeycomb structure of the present invention, the shape of the cross section perpendicular to the longitudinal direction of the honeycomb fired body of each cell of the honeycomb fired body is not particularly limited, and is, for example, substantially circular, substantially elliptical, substantially square, Any shape such as a pentagon, a substantially hexagon, a substantially trapezoid, and a substantially octagon may be used. Various shapes may be mixed.

The main component of the material of the honeycomb fired body constituting the honeycomb structure of the present invention is not limited to silicon carbide or silicon-containing silicon carbide. Other ceramic raw materials include, for example, aluminum nitride, silicon nitride, and boron nitride. And ceramic powders such as nitride ceramics such as titanium nitride, carbide ceramics such as zirconium carbide, titanium carbide, tantalum carbide and tungsten carbide, and oxide ceramics such as cordierite and aluminum titanate.
Among these, when the honeycomb structure is composed of a plurality of honeycomb fired bodies, non-oxide ceramics are preferable, and silicon carbide or silicon-containing silicon carbide is particularly preferable. It is because it is excellent in heat resistance, mechanical strength, thermal conductivity and the like.

The particle size of the ceramic powder is not particularly limited, but it is preferable that the size of the honeycomb fired body manufactured through the subsequent firing step is small compared to the size of the degreased honeycomb formed body.

The organic binder contained in the wet mixture used when producing the honeycomb fired body constituting the honeycomb structure of the present invention is not particularly limited, and examples thereof include methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, polyethylene glycol and the like. . Of these, methylcellulose is desirable. In general, the blending amount of the organic binder is desirably 1 to 10 parts by weight with respect to 100 parts by weight of the ceramic powder.

It does not specifically limit as a plasticizer contained in a wet mixture, For example, glycerol etc. are mentioned.
The lubricant contained in the wet mixture is not particularly limited, and examples thereof include polyoxyalkylene compounds such as polyoxyethylene alkyl ether and polyoxypropylene alkyl ether.
Specific examples of the lubricant include polyoxyethylene monobutyl ether and polyoxypropylene monobutyl ether.
In some cases, the plasticizer and the lubricant may not be contained in the wet mixture.

In preparing the wet mixture, a dispersion medium liquid may be used. Examples of the dispersion medium liquid include water, an organic solvent such as benzene, and an alcohol such as methanol.
Furthermore, a molding aid may be added to the wet mixture.
The molding aid is not particularly limited, and examples thereof include ethylene glycol, dextrin, fatty acid, fatty acid soap, polyalcohol and the like.

Furthermore, a pore-forming agent such as balloons that are fine hollow spheres containing oxide ceramics, spherical acrylic particles, and graphite may be added to the wet mixture as necessary.
The balloon is not particularly limited, and examples thereof include an alumina balloon, a glass micro balloon, a shirasu balloon, a fly ash balloon (FA balloon), and a mullite balloon. Of these, alumina balloons are desirable.

Examples of the inorganic binder contained in the adhesive paste and the coating material paste include silica sol and alumina sol. These may be used alone or in combination of two or more. Among inorganic binders, silica sol is desirable.

Examples of the inorganic particles contained in the adhesive paste and the coating material paste include carbide particles and nitride particles. Specific examples include silicon carbide particles, silicon nitride particles, and boron nitride particles. These may be used alone or in combination of two or more. Among the inorganic particles, silicon carbide particles having excellent thermal conductivity are desirable.

Examples of the inorganic fiber and / or whisker included in the adhesive paste and the coating material paste include inorganic fiber and / or whisker made of silica-alumina, mullite, alumina, silica and the like. These may be used alone or in combination of two or more. Among inorganic fibers, alumina fiber is desirable. The inorganic fiber may be a biosoluble fiber.

The honeycomb structure of the present invention may carry a catalyst for purifying exhaust gas. As the catalyst to be supported, for example, a noble metal such as platinum, palladium, or rhodium is desirable. Further, as other catalysts, for example, alkali metals such as potassium and sodium, and alkaline earth metals such as barium can be used. These catalysts may be used alone or in combination of two or more.

In the binding step in manufacturing the honeycomb structure of the present invention, in addition to the method of applying the adhesive paste to the side surface of each honeycomb fired body, for example, the shape of the ceramic block (or aggregate of honeycomb fired bodies) to be produced Alternatively, each honeycomb fired body may be temporarily fixed in a substantially identical form, and an adhesive paste may be injected between the honeycomb fired bodies.

100, 400, 500, 600, 700 Honeycomb structure 101, 101A to 101D, 401A to 401D, 501, 501A to 501D, 601A to 601D, 701A to 701D Adhesive layer 102, 402, 502, 602, 702 Coat layer 103 , 403, 503, 603, 703 Ceramic block 110, 120, 220, 310, 320, 330, 340, 410, 420, 430, 510, 520, 530, 610, 620, 710, 810, 820, 1110, 1120, 1150, 1160 Honeycomb fired bodies 111, 121, 221, 227a to 227e, 311a, 311b, 321a, 321b, 327a to 327e, 331a, 331b, 341a, 341b, 347a to 347e, 421, 431, 521, 5 1, 811a, 811b, 821a, 821b, 1111, 1121, 1151, 1161 Cell 113, 123, 223, 313, 323, 333, 343, 423, 433, 523, 533, 823 Cell walls 114a to 114d, 124a to 124d 224a to 224d, 314a to 314d, 324a to 324d, 334a to 334d, 344a to 344d, 424a to 424d, 434a to 434c, 524a to 524d, 534a to 534d, 1154, 1164 outer peripheral walls 125, 225, 325, 345, 425, 435, 525, 535, 1155, 1165 Convex part (convex part of outer peripheral wall)
126, 226, 326, 346, 426, 436, 526, 536, 1156, 1166 Recess (recess of outer peripheral wall)

Claims (17)

A honeycomb structure made of a ceramic block composed of a honeycomb fired body in which a large number of cells are arranged in parallel in the longitudinal direction across a cell wall, and an outer peripheral wall is formed around the cell,
Of the outer peripheral wall of the honeycomb fired body, the outer peripheral wall constituting the outer periphery of the ceramic block is a step outer peripheral wall provided with a step composed of a convex part and a concave part in a cross section perpendicular to the longitudinal direction of the honeycomb fired body And
Since the convex portions and / or the concave portions are chamfered, the convex portions and / or the concave portions are configured by curves and / or straight lines in a cross section perpendicular to the longitudinal direction of the honeycomb fired body. And
The cell is composed of an outer peripheral cell in contact with an outer peripheral wall of the honeycomb fired body, and an inner cell located on the inner side of the outer peripheral cell,
The inner cell is a complete cell formed based on a basic formation pattern,
Among the peripheral cells, the peripheral cells in contact with the stepped peripheral wall include incomplete cells whose cross-sectional shape perpendicular to the longitudinal direction is different from the complete cells,
The incomplete cell is a cell in which a circle having a diameter of 0.90 mm can be inserted into a cross-sectional shape perpendicular to the longitudinal direction of the cell . 2. The honeycomb structure according to claim 1, wherein a plurality of the honeycomb fired bodies are bundled through an adhesive layer in the ceramic block. The ceramic block is a combination of honeycomb fired bodies having different shapes,
The honeycomb structure according to claim 2, wherein the honeycomb fired body includes an outer honeycomb fired body positioned on an outer peripheral portion of the ceramic block and an inner honeycomb fired body positioned on the inner side of the outer honeycomb fired body. . The honeycomb structure according to any one of claims 1 to 3, wherein in the cross section perpendicular to the longitudinal direction of the honeycomb fired body, the protrusions and / or the recesses are configured only by curves. The inner wall of the front Kigaishu cells has corner portions formed,
The honeycomb structure according to any one of claims 1 to 4, wherein at least one corner is chamfered. 6. The honeycomb structure according to claim 5, wherein the chamfered corner is a corner formed by the stepped outer peripheral wall and a corner formed by the stepped outer peripheral wall and the cell wall. . The honeycomb structure according to claim 5 or 6, wherein the chamfering applied to at least one of the corners is an R chamfer, and a radius of curvature of the R chamfer is 0.3 to 2.5 mm. The shape of a cross section perpendicular to the longitudinal direction of the outer peripheral cell excluding the incomplete cell and the shape of a cross section perpendicular to the longitudinal direction of the inner cell are substantially quadrangular . The honeycomb structure according to 1. The outer peripheral cell excluding the incomplete cell and the inner cell are composed of a large capacity cell and a small capacity cell,
The honeycomb structure according to any one of claims 1 to 7 , wherein an area of a cross section perpendicular to the longitudinal direction of the large capacity cell is larger than an area of a cross section perpendicular to the longitudinal direction of the small capacity cell. The honeycomb structure according to claim 9 , wherein a shape of a cross section perpendicular to the longitudinal direction of the large-capacity cell is a substantially square shape, and a shape of a cross section perpendicular to the longitudinal direction of the small-capacity cell is a substantially square shape. The honeycomb structure according to claim 9 , wherein a shape of a cross section perpendicular to the longitudinal direction of the large capacity cell is substantially octagonal, and a shape of a cross section perpendicular to the longitudinal direction of the small capacity cell is substantially square. The honeycomb structure according to claim 9 , wherein, in a cross section perpendicular to the longitudinal direction of the large-capacity cell and the small-capacity cell, each side of the cell is configured by a curve. The honeycomb structure according to any one of claims 1 to 12 , wherein a thickness of the stepped peripheral wall of the honeycomb fired body is larger than a thickness of the cell wall of the honeycomb fired body. The honeycomb structure according to claim 13 , wherein the thickness of the stepped peripheral wall of the honeycomb fired body is 1.3 to 3.0 times the thickness of the cell wall of the honeycomb fired body. The honeycomb structure according to any one of claims 1 to 14 , wherein, of the stepped outer peripheral wall of the honeycomb fired body, the outer peripheral walls other than the convex portion and the concave portion have substantially the same thickness. The honeycomb structure according to any one of claims 1 to 15 , wherein one end of each of the cells is alternately sealed. The honeycomb structure according to any one of claims 1 to 16 , wherein a coat layer is formed on an outer peripheral surface of the ceramic block.

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