JP2013056312A - Ceramic honeycomb filter, manufacturing method therefor, and mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a filter for exhaust gas which has high removing capability for harmful substances by a catalyst and low pressure loss.SOLUTION: This filter includes an outflow-side cell 81 and an inflow-side cell 82 arrayed alternately. The outflow-side cell 81 and inflow-side cell 82 each have a rectangular sectional shape such that all sides perpendicular to a direction in which gas (fluid) flows are surrounded with main partition walls 10. The outflow-side cell 81 is provided with sub partition walls 11, 12 projecting from two opposite main partition walls 10 respectively, and the sub partition walls 11, 12 are set not to be in contact with each other. Consequently, the space in the outflow-side cell 81 having the sub partition walls 11, 12 formed is not divided by the sub partition walls 11, 12.

Description

  The present invention relates to a structure of a ceramic honeycomb filter used for purification of gas (exhaust gas) and a manufacturing method thereof. Moreover, it is related with the metal mold | die used for the manufacturing method.

In recent years, diesel engines that have better fuel efficiency and lower CO ₂ emissions than gasoline engines have attracted new international attention. However, there is a problem that the exhaust gas of the diesel engine contains a large amount of PM (Particulate Matter) and NOx (nitrogen oxide). Although efforts have been made to reduce PM and NOx with engine-only technology, the effect is insufficient. For this reason, a filter for removing PM and NOx in the exhaust gas is always used.

  As this filter, a ceramic honeycomb filter is widely used. The structure of a ceramic honeycomb filter (filter) is described in Patent Document 1, for example. Fig.10 (a) is sectional drawing along the gas distribution direction in this structure. FIG. 10B is a cross-sectional view in the GG direction, and FIG. 10C is a cross-sectional view in the H-H direction. These are gas flows at different positions along the gas flow direction. It is a cross-sectional view perpendicular to the direction.

  In this structure, a gas (exhaust gas) is shown from the left side to the right side of the ceramic honeycomb structure in which a large number of flow passages 80 partitioned by main partition walls 90 are provided in parallel, as indicated by white arrows. : Fluid). The main partition wall 90 is made of porous ceramics. Here, in some of the flow passages 80, the inlet side sealing material 91 is provided on the inlet side (left side), while in the remaining flow passages, the outlet side sealing is provided on the outlet side (right side). A stop material 92 is provided. With this configuration, some of the flow passages function as outflow side cells 81 whose fluid inflow side is sealed and whose fluid outflow side is not sealed. The remaining flow passage functions as an inflow side cell 82 in which the inflow side is not sealed but the outflow side is sealed. In FIG. 10A, a large number of flow paths are provided in parallel in the vertical direction, but a large number of flow paths are provided in parallel in the direction orthogonal to the flow paths.

  In this configuration, gas enters from the inlet side (left side) of the inflow side cell 82 and flows therethrough. However, since the outlet side of the inflow side cell is sealed, the gas flows through the main partition wall 90 to the adjacent flow passage (outflow side cell 81). In the outflow side cell, since the inlet side is sealed and the outlet side is not sealed, gas flows from the outlet side to the outside. In this configuration, if the main partition wall 90 is formed of porous ceramics, the main partition wall 90 can be used as a filter for collecting PM.

  On the other hand, by applying a catalyst to the surface of the flow passage (the surface of the main partition wall 90), NOx is changed to a salt form and accumulated in the filter, or a chemical reaction is generated to change to another form to exhaust. It can be removed from the gas. In other words, PM and NOx can be efficiently removed using the ceramic honeycomb filter having the configuration shown in FIG. In particular, since PM is removed from the exhaust gas in the outflow side cell 81, it is preferable to apply a catalyst for NOx purification to the inner surface of the outflow side cell 81.

  In manufacturing the filter having the configuration shown in FIG. 10, extrusion molding using a mold can be used. In this case, the form before the inlet side sealing material 91 and the outlet side sealing material 92 are formed in the structure of FIG. 10 is an extrusion in which a raw material (a clay made of a ceramic raw material) is passed through a mold. It can be easily obtained as a molded body by molding. Then, after the formed body is dried, cut, and fired, or before firing, the inlet side sealing material 91 and the outlet side sealing material 92 are formed, whereby the structure of FIG. 10 can be obtained. Thereafter, the catalyst can be formed on the inner surface of the flow passage by immersing the structure in a liquid containing the catalyst.

  In the technique described in Patent Document 1, the porosity and the like in the main partition wall 90 are optimized to achieve downsizing and high efficiency of the filter. This porosity and the like can be performed by adjusting ceramic raw materials, slurry, clay, and firing conditions.

  On the other hand, in the techniques described in Patent Document 2 and Patent Document 3, the efficiency of the filter is increased by providing a sub-partition that further subdivides the flow passage 80 in the configuration of FIG.

  Here, FIGS. 11A and 11B are cross-sectional views of portions corresponding to FIG. 10B in the ceramic honeycomb filters described in Patent Documents 2 and 3, respectively. In the example of FIG. 11A, the flow passage 80 is further subdivided by further providing the sub-partition walls 96 and 97 intersecting in the region surrounded by the main partition wall 90. Thereby, the surface area of the inner surface of the flow passage 80 can be increased, and the amount of catalyst to be supported can be increased. In the example of FIG. 11 (b), the sub-partition wall 98 is provided along the diagonal line of the flow passage 80 having a rectangular cross-sectional shape.

  Using such a technique, it is possible to obtain a filter that can remove PM and NOx with high efficiency.

JP 2004-162544 A JP 2003-205245 A JP 2008-246331 A

  In the technique described in Patent Document 1, since the surface area of the region surrounded by the main partition wall 90 is insufficient, the surface area capable of supporting the catalyst is insufficient. For this reason, NOx removal is particularly insufficient. That is, PM removal is sufficient, but removal of harmful substances by the catalyst is insufficient.

  On the other hand, in the techniques described in Patent Documents 2 and 3, since the sub-partition walls are provided as shown in FIGS. 11 (a) and 11 (b), the area capable of supporting the catalyst is increased. The NOx removal capability can be improved. However, since the space in the flow path is subdivided, the resistance when the gas flows through the flow path increases, and the pressure loss of the filter increases.

  That is, it has been difficult to obtain an exhaust gas filter having a high ability to remove harmful substances by a catalyst and a low pressure loss.

  The present invention has been made in view of such problems, and an object thereof is to provide an invention that solves the above problems.

In order to solve the above problems, the present invention has the following configurations.
The ceramic honeycomb filter of the present invention is formed of a ceramic honeycomb structure formed by being surrounded by four porous main partition walls and provided with a plurality of flow passages through which fluid flows adjacently in parallel. A part of the flow passage is sealed at the fluid inflow side and the fluid outflow side is not sealed, and the remaining flow passages of the flow passages are sealed at the outflow side without being sealed at the inflow side. A ceramic honeycomb filter in which a catalyst is supported on the inner surface of the outflow side cell and the inflow side cell, and is formed integrally with the main partition wall, protruding from the main partition wall, and The outflow side cell is provided with a sub-partition extending in the flow direction of the fluid without dividing the space in the flow passage.
The ceramic honeycomb filter of the present invention protrudes from each of two opposing main partition walls of the four main partition walls constituting the outflow side cell so that the sub partition walls do not contact each other in the outflow side cell. It is characterized by being formed.
In the ceramic honeycomb filter of the present invention, in the outflow side cell, the sub partition walls do not come into contact with each other in the outflow side cell from each of the two intersecting partition walls in the cross section perpendicular to the fluid flow direction. It is characterized by being formed to project.
In the ceramic honeycomb filter of the present invention, the sub partition wall is formed thinner than the main partition wall between the adjacent flow passages.
The ceramic honeycomb filter of the present invention is characterized in that the amount of the catalyst supported in the outflow side cell is larger than the amount of the catalyst supported in the inflow side cell.
The ceramic honeycomb filter of the present invention is characterized in that irregularities are formed on a surface of the sub-partition wall formed by extending in the one direction.
The mold according to the present invention is formed by extruding a molded body having a structure in which a plurality of the flow passages in the ceramic honeycomb filter are provided in parallel with each other by supplying a raw material under pressure in a direction in which a fluid flows in the flow passage. A mold used for obtaining a main partition wall forming groove that forms the plurality of main partition walls, a raw material supply hole communicating with the main partition wall forming groove, the raw material supply hole, and the main partition wall forming groove A sub partition wall forming groove for forming the sub partition wall is formed on the main partition wall forming groove side with respect to the intersecting portion.
In the mold of the present invention, the sub partition wall forming groove has a groove depth gradually increasing from the upstream side to the downstream side in the direction in which the raw material moves on the surface of the mold constituting the main partition wall forming groove. It is characterized by being formed large.
The method for manufacturing a ceramic honeycomb filter of the present invention is characterized in that a molded body is formed using the mold, and the molded body is fired to manufacture the ceramic honeycomb filter.

  Since the present invention is configured as described above, it is possible to obtain an exhaust gas filter having a high ability to remove harmful substances by a catalyst and a low pressure loss.

It is sectional drawing of the ceramic honeycomb filter which concerns on 1st Embodiment. It is sectional drawing of the ceramic honeycomb filter which concerns on 2nd Embodiment. It is a perspective view of the metal mold | die used when manufacturing the conventional ceramic honeycomb filter. It is the top view (a) of the metal mold | die used when manufacturing the conventional ceramic honeycomb filter, and its CC sectional drawing (b). It is a perspective view of the metal mold | die used when manufacturing the ceramic honeycomb filter which concerns on 1st Embodiment. It is the top view (a) of the metal mold | die used when manufacturing a ceramic honeycomb filter in 1st Embodiment, the sectional view (b) in the DD direction, and the sectional view (c) in the EE direction. . It is a perspective view of the metal mold | die used when manufacturing the ceramic honeycomb filter which concerns on 2nd Embodiment. It is the top view (a) of the metal mold | die used when manufacturing a ceramic honeycomb filter in 2nd Embodiment, and sectional drawing (b) of the FF direction. The enlarged view (a) of the cross section perpendicular | vertical to the gas distribution direction of the ceramic honeycomb filter which concerns on embodiment of this invention, the enlarged view (b) of the cross section of the same direction in a 1st modification, X in a 2nd modification It is sectional drawing (c) of -X direction, and sectional drawing (d) of the YY direction in a 3rd modification. It is sectional drawing which shows the structure of the conventional ceramic honeycomb filter. It is sectional drawing perpendicular | vertical to the gas distribution direction of the ceramic honeycomb filter of patent document 2 (a) and patent document 3 (b).

  The present invention will be described below with reference to specific embodiments. However, the present invention is not limited to these embodiments. Also in this ceramic honeycomb filter (filter), in the same manner as the filter shown in FIG. 10, a large number of flow passages are formed by the main partition walls, a part of the flow passages is on the inlet side, and the remaining flow passages are By sealing the outlet side, the former functions as an outflow side cell and the latter functions as an inflow side cell. Since the sub-partition is provided in the outflow side cell, the surface area inside the flow passage is increased. However, the pressure loss of this filter is about the same as that of a filter without a sub partition.

(First embodiment: Ceramic honeycomb filter)
FIG. 1A is a cross-sectional view in a direction perpendicular to the flow direction of the exhaust gas of the ceramic honeycomb filter (filter) according to the first embodiment. Here, many flow paths 80 surrounded by the main partition 10 are formed adjacent to each other. FIG. 1B is a cross-sectional view corresponding to the AA direction (the direction in which exhaust gas flows) in FIG. In this filter, the outflow side cells 81 and the inflow side cells 82 are alternately arranged. Further, both the outflow side cell 81 and the inflow side cell 82 have a rectangular cross-sectional shape formed by being surrounded by the main partition 10 in four directions perpendicular to the direction in which the gas (fluid) flows.

  Here, in the outflow side cell 81, a pair of sub-partition walls 11 and 12 are provided. In the outflow side cell 81, the sub-partition walls 11, 12 are provided so as to protrude from the two opposing main partition walls 10, and the sub-partition walls 11, 12 are set so as not to contact each other. For this reason, the space in the outflow side cell 81 in which the sub partitions 11 and 12 are formed is not divided by the sub partitions 11 and 12. The sub partition walls 11 and 12 are formed by extending along the direction in which the exhaust gas flows, and the sub partition walls 11 and 12 are formed integrally with the main partition wall 10. 1A shows a cross section perpendicular to the flow direction of gas (fluid), and the sub-partition walls 11 and 12 extend along this flow direction.

  The sub partition walls 11 and 12 are preferably configured so as not to hinder the flow of exhaust gas in the outflow side cell 81. For this reason, it is preferable to make the thickness in FIG. 1 of the subpartitions 11 and 12 thinner than the main partition 10 between adjacent flow paths.

Specifically, the thickness of the main partition 10 is 0.2 to 0.45 mm, the pitch between the main partitions 10 is 1.2 to 2.0 mm, and the thickness of the sub partitions 11 and 12 is 0.1 to 0. It is preferable to be 35 mm. If the thickness of the main partition wall 10 is less than 0.2 mm, the strength of the honeycomb structure is not preferable. On the other hand, when the thickness exceeds 0.45 mm, the pressure loss increases, which is not preferable. If the thickness of the sub-partition walls 11 and 12 is less than 0.1 mm, the strength decreases, the surface area on which the catalyst can be supported becomes insufficient, and NOx removal may be insufficient, which is not preferable. If this thickness exceeds 0.35 mm, the pressure loss increases, which is not preferable. The length H of the sub-barrier rib 11, 12 projects into flow path In FIG. 1 (a), must be less than the opening width W ₁ of the passage in the direction that projecting, 0 opening width W _1. A length of 1 to 0.8 times is preferable. When this length is less than 0.1 times, the surface area that can be catalyzed becomes insufficient, and when it exceeds 0.8 times, the pressure loss increases. The sub partition walls 11 and 12, a position equally dividing the opening width _{W 2} in the direction perpendicular to the direction of its protruding, for example, at a distance of _W 2/3 the center of the sub-partition walls 11, 12 from the main partition 10 It is preferable to arrange | position. Thereby, the rise in pressure loss can be suppressed small.

  In this configuration, even if the sub-partition walls 11 and 12 exist, the spaces in the single outflow side cell 81 are connected. However, the presence of the sub-partition walls 11 and 12 increases the surface area in the outflow side cell 81 by the surface area of the sub-partition walls 11 and 12. For this reason, in this outflow side cell 81, the amount of catalyst that can be carried increases, and the effect of the catalyst increases. That is, in this filter, a high NOx removal capability can be obtained. Further, when the catalyst is formed on the inner surface of the flow passage by immersing the above structure in a liquid containing the catalyst, the amount of the catalyst supported in the outflow side cell provided with the sub-partition walls 11 and 12 is determined by the amount of the catalyst in the inflow side cell. The amount can be larger than the supported amount.

  On the other hand, if the sub-partition walls 11 and 12 are formed thin, the resistance to the gas flow in the outflow side cell 81 is difficult to increase, and the gas flows through the flow path as compared with the case where the sub-partition walls 11 and 12 are not formed. The resistance is difficult to increase. For this reason, an increase in pressure loss of the filter is suppressed. That is, the exhaust gas filter has a high ability to remove harmful substances by the catalyst and a small increase in pressure loss. Further, even when the sub-partition walls 11 and 12 are formed thin, sufficient mechanical strength can be obtained by forming the sub-partition walls 11 and 12 integrally with the main partition wall 10.

(Second embodiment: Ceramic honeycomb filter)
FIG. 2 is a view showing a cross section of the ceramic honeycomb filter (filter) according to the second embodiment in the same manner as FIG. Also in this filter, as in the case of FIG. 1, sub-partition walls 21 and 22 are provided in one flow passage (outflow side cell) that is surrounded by the main partition wall 20. The sub-partition walls 21 and 22 are formed from the two partition wall intersections (locations where the main partition wall 20 intersects) facing each other in the flow path toward the center side in the cell cross section. However, the sub partition walls 21 and 22 do not contact each other, and the space in the flow path is not divided by the sub partition walls 21 and 22. The length H projecting into the flow path of the sub-partition walls 21 and 22 needs to be less than ½ of the diagonal length T of the two partition wall intersections facing each other in FIG. A length of 0.05 to 0.4 times is preferable. When this length is less than 0.05 times, the surface area that can be catalyzed becomes insufficient, and when it exceeds 0.4 times, the pressure loss increases. The sub partition walls 21 and 22 are formed to extend along the direction in which the exhaust gas (fluid) flows, and the sub partition walls 21 and 22 are formed integrally with the main partition wall 20.

  Even when the filter of FIG. 2 is used, as in the case of the first embodiment, the surface area in the flow path can be increased without increasing the resistance when the gas flows through the flow path. . For this reason, it is clear that this filter has a high ability to remove harmful substances by the catalyst and a low pressure loss. Further, since the sub-partition walls 21 and 22 are provided along the diagonal lines in the cross section of the flow passage, these surface areas can be increased.

(Third embodiment: Manufacturing method and mold used therefor)
The above ceramic honeycomb filter can be manufactured particularly easily by the manufacturing method described below. In this manufacturing method, a molded body having a honeycomb structure is obtained by pressurizing and supplying a plasticized clay to which extrusion molding can be applied to a mold. Thereafter, the formed body is dried, cut and fired to obtain a ceramic honeycomb structure. Thereafter, an inflow side and an outflow side sealing material are provided. In this manufacturing method, a known mold is used as the mold used at this time. The raw materials and other manufacturing processes are the same as those described in Patent Document 1.

  First, FIG. 3 is a perspective view showing a configuration of a mold used in manufacturing a honeycomb structure having a conventional structure in which a sub partition wall is not provided (a structure shown in FIG. 10 in which a sub partition wall is not provided). A top view thereof is shown in FIG. 4A, and a cross-sectional view in the CC direction is shown in FIG. Here, in the mold shown in FIG. 3, the lower side in the figure is the clay supply side into which the clay is press-fitted, and the upper side in the figure is the molding side from which the molded body is extruded. 3 and 4 partially show the mold, and in actuality, the mold is used in an integrated state outside the illustrated range. Using this mold, a honeycomb structure formed body in a state before the inlet side sealing material 91 and the outlet side sealing material 92 in FIG. 10 are formed is obtained.

  In the mold having the conventional structure, a main partition wall forming groove 31 corresponding to the main partition wall 90 is formed in the mold member 30. Further, a raw material supply hole 32 is provided on the clay supply side (the lower side in FIGS. 3 and 4), and the raw material (soil) is pressurized and supplied in the direction of the white arrow in FIG. It is said. This raw material passes through the main partition wall forming groove 31 extending in the vertical direction of the figure in this mold. The main partition wall forming groove 31 is formed in a lattice shape in one direction in the top view (FIG. 4A) and in a direction perpendicular to the one direction, and is formed so as to penetrate in FIG. On the other hand, on the clay supply side of the mold member 30, the raw material drilled from the lower surface in FIG. 4B of the mold member 30 in communication with the intersecting portion of the intersecting main partition wall forming grooves 31. A supply hole 32 is formed. For this reason, the main partition wall forming groove 31 is connected to the raw material supply hole 32 on the lower surface side.

  With this configuration, the raw material supplied from the raw material supply hole 32 moves through the main partition wall forming groove 31 connected to the raw material supply hole 32 and moves upward in FIGS. The length of the mold from the clay supply side to the molding side can be, for example, about 20 mm. By continuously supplying the raw material from the raw material supply hole 32 under pressure, the honeycomb structure formed body can be continuously formed. Can be obtained.

  Further, in FIG. 4A, the raw material supply holes 32 have a main partition wall forming groove 31 formed in one direction and a main partition wall forming groove formed in a direction orthogonal thereto so that the raw material can be supplied smoothly. It is formed at 31 intersections. However, it is not necessary to form it corresponding to all the intersections, and if the number of raw material supply holes 32 is large, the mechanical strength of the mold is lowered, so that it may be formed at every other intersection.

  If the groove shape in the mold is the one corresponding to FIGS. 1 and 2, it is obvious that the molded body in the form of FIGS. 1 and 2 can be obtained and the filter can be manufactured using this. is there. However, when the groove corresponding to the sub partition wall is formed in the same manner as the groove corresponding to the main partition wall as shown in FIGS. 1 and 2, a fine portion is generated in the thickness of the mold member 30, Since the mechanical strength of the mold is greatly reduced, stable production becomes difficult.

  For this reason, in the metal mold used in the manufacturing method according to the present embodiment, the groove corresponding to the main partition is formed so as to be connected to the raw material supply hole as in FIGS. However, the groove corresponding to the sub-partition is not directly connected to the raw material supply hole, but is formed so as to be connected to the groove corresponding to the main partition.

  5 is a perspective view of a mold used in manufacturing the filter of the form of FIG. 1, FIG. 6 (a) is a top view thereof, FIG. 6 (b) is its DD direction, and FIG. 6 (c) is its top view. It is sectional drawing of the EE direction. 3 and 4, these drawings partially show the mold.

  In this mold, a main partition wall forming groove 41 corresponding to the main partition wall 10 in FIG. 1 is formed in the mold member 40 in the same manner as the main partition wall forming groove 31 in the structure of FIGS. Similarly, the material supply hole 42 is formed on the lower surface side. The main partition wall forming groove 41 is formed so as to penetrate the mold member 40 in the direction in which the raw material moves during extrusion molding. The main partition wall forming groove 41 is connected to the raw material supply hole 42 on the lower surface side (the side on which the raw material is supplied) as in the structure of FIGS.

  On the other hand, the sub partition molding grooves 43 corresponding to the sub partition walls 11 and 12 in FIG. 1 are formed so as to be connected to the main partition molding grooves 41, but as shown in the perspective view (FIG. 5), the bottom surface The side, that is, the raw material supply hole 42 is not directly connected. Specifically, the sub partition molding groove 43 is formed only on the upper side of the drawing (the downstream side in the direction in which the raw material moves: the molding side) from the intersection of the raw material supply hole 42 and the main partition molding groove 41. The sub partition molding groove 43 can also be regarded as a groove formed on the surface of the mold member 40 constituting the main partition molding groove 41. In this case, as shown in FIG. 6C, the groove depth d4 is gradually increased from the upstream side toward the downstream side in the direction in which the raw material moves on the surface.

  As shown in the top view (FIG. 6A), in this case as well, the raw material supply holes 42 have the main partition wall forming groove 41 formed in one direction and the main partition wall forming groove formed in a direction perpendicular thereto. It is formed at every other place of 41 intersections. As shown in FIG. 6A, each of the two sub-partition molding grooves 43 at a location corresponding to one flow passage is set to a position close to the closest raw material supply hole 42.

  When the raw material is supplied from the raw material supply hole 42 in the mold having the above structure, the raw material is directly supplied from the raw material supply hole 42 to the main partition wall forming groove 41, and the inside of the main partition wall forming groove 41 is directed from the lower surface side to the upper surface side. The raw material flows. At this time, the raw material is not directly supplied from the raw material supply hole 42 to the sub partition molding groove 43, but the raw material is indirectly supplied from the main partition molding groove 41. For this reason, a raw material is supplied also to the sub-partition molding groove 43, and a molded body having the cross-sectional shape of FIG. 1 is obtained on the upper surface side.

  Then, the ceramic honeycomb filter shown in FIG. 1 is obtained by forming the inlet side sealing material 91 and the outlet side sealing material 92 before or after firing the formed body.

  That is, the ceramic honeycomb filter according to the first embodiment can be easily manufactured by performing extrusion molding using the mold shown in FIGS.

  7 is a perspective view of a mold used when manufacturing the filter of the form of FIG. 2, FIG. 8A is a top view thereof, and FIG. 8B is a cross-sectional view in the FF direction. . 3 and 4, these drawings partially show the mold. In the perspective view (FIG. 7), an enlarged view in which only a portion corresponding to one flow path in the mold (a portion surrounded by a broken line) is changed in direction is also shown.

  Also in this mold, in the mold member 50, the main partition wall forming groove 51 corresponding to the main partition wall 20 in FIG. 2 is formed in the same manner as the main partition wall forming groove 31 in the structure of FIGS. Similarly, the material supply holes 52 are formed on the lower surface side. The main partition wall forming groove 51 is connected to the raw material supply hole 52 in the same manner as the structure of FIGS.

  On the other hand, the sub partition molding grooves 53 corresponding to the sub partition walls 21 and 22 in FIG. 2 are formed connected to the main partition molding grooves 51, but as shown in the perspective view (FIG. 7), That is, it is not formed on the side where the material supply holes 52 are present. Specifically, as shown in the enlarged view of FIG. 7, it is formed only on the upper side (downstream side in the direction in which the raw material moves) above the intersection of the raw material supply hole 52 and the main partition wall forming groove 51. Further, the sub partition wall forming groove 53 formed on the surface of the mold member 50 constituting the main partition wall forming groove 51 is gradually deepened from the upstream side to the downstream side in the direction in which the raw material moves on this surface. It is formed to become. That is, the sub partition wall forming groove 53 is formed such that the groove depth d5 shown in the enlarged view in FIG. 7 gradually increases on the side surface constituting the main partition wall forming groove 51. However, in order to obtain the configuration shown in FIG. 2, the two sub-partition molding grooves 53 are not in contact with each other at a location corresponding to one flow path on the uppermost surface of the mold.

  A ceramic honeycomb filter having the configuration shown in FIG. 2 can be stably manufactured using this mold.

  A ceramic honeycomb filter having sub-partition walls as shown in FIGS. 1 and 2 can be manufactured using the molds shown in FIGS. At this time, the raw material is pressurized and supplied from the lower side of the drawing in the raw material supply holes 42 and 52. Since the pressure at this time works from the lower side to the upper side in the figure, this pressure works effectively when the raw material is supplied to the main partition wall forming grooves 41 and 51. However, the sub partition molding grooves 43 and 53 are not directly connected to the raw material supply holes 42 and 52, respectively, and the material supply to the sub partition molding grooves 43 and 53 is directed from the main partition molding grooves 41 and 51 in the lateral direction. It is done. For this reason, in order to fill the sub partition molding grooves 43 and 53 with the raw material without gaps, it is necessary to adjust the density and viscosity of the raw material (kneaded material).

  However, it is also possible to intentionally generate voids during this filling. Thereby, it is also possible to make the surface shape of the sub-partition wall 11 (12) in FIG. As long as the flow of the exhaust gas in the flow passage is not obstructed, it is effective to make the surface shape curved because the surface area of the sub partition 11 (12) can be increased and the amount of catalyst supported can be increased. is there.

FIGS. 9B to 9D are examples showing the shape of the sub-partition wall 11 (12) in such a case. FIG. 9A is an enlarged view of a cross section perpendicular to the exhaust gas flow direction of the outflow side cell 81 shown in FIG. 1A. Here, all the surfaces constituting the sub-partition wall 11 (12) are shown. It is planar. FIGS. 9B to 9D show examples in which these surfaces are curved.

  FIG. 9B shows an example in which the side surface of the sub partition wall 11 (12) substantially orthogonal to the surface of the main partition wall 10 has a curved shape in a cross section perpendicular to the flow direction of the exhaust gas. It is sectional drawing shown similarly. In this case, these side surfaces of the sub-partition wall 11 (12) undulate along the direction protruding from the main partition wall 10.

FIG. 9C is a cross-sectional view corresponding to the cross section in the XX direction in FIG. In FIG. 9C, these side surfaces are curved in this cross section. In this case, these side surfaces undulate along the direction in which the exhaust gas flows.

  FIG. 9D is a cross-sectional view corresponding to the cross section in the YY direction in FIG. In FIG.9 (d), the surface which comprises the top part of the subpartition 12 is wavy along the flow direction of exhaust gas.

  FIGS. 9B to 9D are modifications of the sub-partition wall 11 (12) in the first embodiment, but also for the sub-partition wall 21 (22) in the second embodiment. It is clear that a similar configuration can be applied. It is also clear that the forms of FIGS. 9B to 9D can be combined. In such a case, since the effective surface area of the sub-partition walls 11 (12) and 21 (22) is further increased, more catalyst can be supported.

  Due to the presence of unevenness due to this undulation, the surface area of the surface where the unevenness is formed (the surface extending in the gas flow direction formed by the top of the sub-partition wall) is 1.05 to 1 compared to the surface area when there is no unevenness. .30 times is preferable. When the ratio is less than 1.05 times, the surface area on which the catalyst can be supported becomes insufficient, and NOx removal may be insufficient, which is not preferable. On the other hand, when it exceeds 1.30 times, the flow path resistance increases and the pressure loss may increase, which is not preferable.

(Example)
Actually, a ceramic honeycomb filter having the above structure having the outer diameter of 270 mm, the total length of 300 mm, and the main component of the crystal phase being cordierite (the same configuration as FIG. 1 and FIG. 2) is manufactured and distributed by the above manufacturing method. A catalyst made of TiO ₂ , WO ₃ , V ₂ O ₅ was supported on the inner surface of the road and the characteristics thereof were examined. The results will be described below.

Various ceramic honeycomb filters with different main partition pitches and wall thicknesses were manufactured from the same material, and the pressure loss and purification performance when the sub-partition was formed (Example) and when it was not formed were compared. Incidentally, the sub partition wall 11, 12 of the structure of FIG. 1, a position equally dividing the opening width _{W 2,} i.e., the center of the sub-partition walls 11 and 12 is arranged at a distance of _W 2/3 from the main partition 10.

As the pressure loss, a pressure loss test stand was used, and the difference in pressure between the inflow side and the outflow side with respect to air having a flow rate of 10 Nm ³ / min was measured. Here, on the basis of the pressure loss in Comparative Example 1, when this value is 150% or more, ×, when 125% or more and less than 150%, Δ, when 100% or more and less than 125%, ○, less than 100% The case was marked ◎.

In order to evaluate the purification performance, an exhaust gas containing an exhaust gas temperature of 300 ° C. and NOx of 400 ppm was introduced into the ceramic honeycomb filter in which a catalyst was applied. At this time, for example, as described in Patent Document 1, NOx is decomposed by adding urea to the exhaust gas. For this reason, the same amount of urea as the NOx amount of this exhaust gas was added in terms of N, and the NOx amount in the gas at the outlet of the ceramic honeycomb filter was measured. Based on the measured amount of NOx, the removed NOx rate (NOx purification rate) was calculated. Based on the NOx purification rate in Comparative Example 1, this value is less than 80% x, 80% or more is less than 100%, Δ is 100% or more and less than 125%, ○ is 125% or more. ◎.

  In the examples, since the above manufacturing method was used, irregularities were formed on the surface extending in the gas flow direction formed by the top of the sub partition wall. The ratio of this surface area compared to the case without unevenness was also measured. The unevenness was adjusted by changing the extrusion pressure.

  Comparative Examples 1 to 4 are manufactured by changing the pitch and wall thickness of the main partition walls of the honeycomb filter having the structure shown in FIG. The comparative example 5 is a form in which the sub partition walls 96 and 97 divide the space in the flow passage in a cross shape (FIG. 11A), and the comparative example 6 is a case where the sub partition wall 98 divides the space in the flow passage on a diagonal line. The honeycomb filter of the form (FIG. 11B) was obtained.

  When Examples 1 to 3 and Comparative Example 1 having the same pitch and wall thickness of the main partition walls, Examples 4 to 6 and Comparative Example 2, and Examples 11 to 13 and Comparative Example 4 were compared, respectively, In addition, Examples 1-3, Examples 4-6, and Examples 11-13 have low pressure loss and high purification performance.

  Further, in Examples 1 and 2, and Examples 5 and 6 in which parameters other than the unevenness are the same, the higher purification performance is obtained in Examples 1 and 6 with large unevenness. It was.

  That is, it was confirmed that in the example having the sub-partition wall, lower pressure loss and higher purification performance were obtained than in the comparative example. At this time, in the examples, it was also confirmed that the purification performance could be further improved by forming irregularities on the surface of the sub-partition wall. Further, even in the case where the sub partition wall was provided, in Comparative Examples 5 and 6 in which the space in the flow passage was divided, the pressure loss was high.

  In the above example, a pair of sub-partition walls are provided in one flow passage (outflow side cell). However, the space inside the flow passage is not divided, and the resistance when gas flows through the flow passage is increased. This configuration is optional so long as the surface area can be increased. For example, the number of sub-partitions may be one, or a number of thin sub-partitions may be provided. Even when a pair of sub-partitions are provided, it is not necessary to have a symmetrical configuration as shown in FIGS.

  Further, in the above molds (FIGS. 6 and 8, etc.), the sub partition wall forming groove is set to linearly increase the groove depth from the upstream side to the downstream side. As long as the above can be obtained, this configuration is arbitrary.

10, 20, 90 Main partition walls 11, 12, 21, 22, 96, 97, 98 Sub partition walls 30, 40, 50 Mold members 31, 41, 51 Main partition wall forming grooves 32, 42, 52 Raw material supply holes 43, 53 Sub-partition molding groove 80 Inflow passage 81 Outflow side cell 82 Inflow side cell 91 Inlet side sealing material 92 Outlet side sealing material

Claims (9)

A part of the flow passages of the ceramic honeycomb structure, which is formed by being surrounded by four porous main partition walls and in which a plurality of flow passages through which fluid flows are provided in parallel, The outflow side cell in which the fluid inflow side is sealed and the fluid outflow side is not sealed, and the remaining flow passage of the flow passages is an inflow side cell in which the inflow side is not sealed but the outflow side is sealed, and the outflow A ceramic honeycomb filter in which a catalyst is supported on the inner surface of the side cell and the inflow side cell,
In the flow passage, the outflow side cell includes a sub-partition that protrudes from the main partition and is integrally formed with the main partition and extends in the fluid flow direction without dividing the space in the flow passage. A ceramic honeycomb filter characterized by that.   The sub-partition wall is formed so as to protrude from each of two opposing main partition walls out of the four main partition walls constituting the outflow-side cell so as not to contact each other in the outflow-side cell. The ceramic honeycomb filter according to claim 1.   In the outflow side cell, the sub-partition wall is formed so as to protrude from each of two opposing partition wall intersections in a cross section perpendicular to the fluid flow direction so as not to contact each other in the outflow side cell. The ceramic honeycomb filter according to claim 1, wherein the ceramic honeycomb filter is characterized in that:   The ceramic honeycomb filter according to any one of claims 1 to 3, wherein the sub partition wall is formed thinner than a main partition wall between the adjacent flow passages.   The ceramic honeycomb filter according to any one of claims 1 to 4, wherein a loading amount of the catalyst in the outflow side cell is larger than a loading amount of the catalyst in the inflow side cell.   The ceramic honeycomb filter according to any one of claims 1 to 5, wherein unevenness is formed on a surface formed by extending in the one direction in the sub-partition wall. 5. A molded body having a structure in which a plurality of the flow passages are provided in parallel in the ceramic honeycomb filter according to claim 1, and a raw material along a direction in which a fluid flows in the flow passages. A mold used for obtaining by extrusion molding,
A main partition wall forming groove for forming the plurality of main partition walls;
A raw material supply hole communicating with the main partition wall forming groove;
A sub partition wall forming groove for forming the sub partition wall connected to the main partition wall forming groove on the main partition wall forming groove side with respect to the intersection of the raw material supply hole and the main partition wall forming groove,
A mold characterized in that is formed.   The auxiliary partition wall forming groove is formed such that the groove depth is gradually increased from the upstream side to the downstream side in the direction in which the raw material moves on the surface of the mold constituting the main partition wall forming groove. The mold according to claim 7.   A method for manufacturing a ceramic honeycomb filter, comprising: forming a molded body using the mold according to claim 7 or 8; and firing the molded body to manufacture the ceramic honeycomb filter.

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