Honeycomb filter and ceramic filter assembly

Abstract

An integral honeycomb filter assembly is produced by adhering ceramic seal layer outer surfaces of a plurality of honeycomb filters. Each of the plurality of honeycomb filters has a plurality of cells defined by a cell wall, and purifies fluid including particulates with the cell wall. A ratio L/S between a filter length L in a flow direction of a processed fluid and a filter cross-section S in a direction perpendicular to the flow direction for each honeycomb filter is 0.06 to 0.75 mm/mm 2 . A ratio L/S between a filter length L in a flow direction of a processed fluid and a filter cross-section S in a direction perpendicular to the flow direction for the integral honeycomb filter assembly is 0.06 to 0.75 mm/mm 2 .

1 . An integral honeycomb filter assembly produced by adhering with a ceramic seal layer outer surfaces of a plurality of honeycomb filters, each of which has a plurality of cells defined by a cell wall, and which purifies fluid including particulates with the cell wall, wherein
 a ratio L/S between a filter length L in a flow direction of a processed fluid and a filter cross-section S in a direction perpendicular to the flow direction for each honeycomb filter is 0.06 to 0.75 mm/mm 2 , and   a ratio L/S between a filter length L in a flow direction of a processed fluid and a filter cross-section S in a direction perpendicular to the flow direction for the integral honeycomb filter assembly is 0.06 to 0.75 mm/mm 2 .   
   
   
       2 . An elongated honeycomb filter formed from a sintered porous ceramic body, wherein a ratio L/S between a filter length L in a flow direction of a processed fluid and a filter cross-section S in a direction perpendicular to the flow direction is 0.15 to 0.75 mm/mm 2 . 
   
   
       3 . The honeycomb filter assembly according to  claim 1 , wherein the assembly is formed from a sintered porous silicon-carbide. 
   
   
       4 . The honeycomb filter according to  claim 2 , wherein the filter is formed from a sintered porous silicon-carbide. 
   
   
       5 . The honeycomb filter assembly according to  claim 1 , wherein the filters are arranged in a state offset from one another in a direction perpendicular to a filter axial direction. 
   
   
       6 . The honeycomb filter assembly according to  claim 1 , wherein an outer surface of each cell wall carries at least one oxide catalyst selected from a platinum group element, other metal elements and oxides of these metal elements. 
   
   
       7 . The honeycomb filter according to  claim 2 , wherein the filter has a plurality of cells, and each cell has an outer surface which carries at least one oxide catalyst selected from a platinum group element, other metal elements and oxides of these metal elements. 
   
   
       8 . The honeycomb filter assembly according to  claim 1 , wherein the average pore diameter of the honeycomb filter is 1 to 50 μm. 
   
   
       9 . The honeycomb filter according to  claim 2 , wherein the average pore diameter of the honeycomb filter is 1 to 50 μm. 
   
   
       10 . The honeycomb filter assembly according to  claim 1 , wherein the filter has an average porosity of 30 to 70%. 
   
   
       11 . The honeycomb filter according to  claim 2 , wherein the filter has an average porosity of 30 to 70%. 
   
   
       12 . The honeycomb filter assembly according to  claim 1 , wherein the filter has an outer form of a triangular pole-like shape or hexagonal pole-like shape. 
   
   
       13 . The honeycomb filter according to  claim 2 , wherein the filter has an outer form of a triangular pole-like shape or hexagonal pole-like shape. 
   
   
       14 . The honeycomb filter assembly according to  claim 1 , wherein the assembly is a diesel particulate filter. 
   
   
       15 . The honeycomb filter according to  claim 2 , wherein the assembly is a diesel particulate filter. 
   
   
       16 . The honeycomb filter assembly according to  claim 1 , wherein the assembly has an outer form in a round cross-section or oval cross-section. 
   
   
       17 . The honeycomb filter assembly according to  claim 1 , wherein the seal layer includes at least inorganic fibers, an inorganic binder, an organic binder, and inorganic grains and is formed from an elastic material obtained by bonding the inorganic fibers and inorganic grains, which three-dimensionally intersected one another, with the inorganic binder and the organic binder. 
   
   
       18 . The honeycomb filter assembly according to  claim 1 , wherein the seal layer is formed from 10 wt % to 70 wt % of silica-alumina ceramic fiber as a solid, 1 wt % to 30 wt % of silica sol, 0.1 wt % to 5.0 wt % of carboxymethyl cellulose, and 3 wt % to 80 wt % of silicon carbide powder. 
   
   
       19 . An exhaust gas purification apparatus including the ceramic filter assembly according to  claim 1  arranged in a casing that is located in an exhaust gas passage of an internal combustion engine. 
   
   
       20 . An integral honeycomb filter assembly produced by adhering with a ceramic seal layer outer surfaces of a plurality of honeycomb filters, each of which has a plurality of cells defined by a cell wall, and which purifies fluid including particulates with the cell wall,
 wherein a specific surface area of grains forming the cell wall is 0.1 m 2 /g or more, and a filter length L in a flow direction of a processed fluid is 167-300 mm.   
   
   
       21 . The honeycomb filter assembly according to  claim 20 , wherein an outer surface of each cell wall carries at least one oxide catalyst selected from a platinum group element, other metal elements and oxides of these metal elements. 
   
   
       22 . The honeycomb filter assembly according to  claim 20 , wherein the filter has an average pore diameter of 1 to 50 μm. 
   
   
       23 . The honeycomb filter assembly according to  claim 20 , wherein the filter has an average porosity of 30 to 70%. 
   
   
       24 . The honeycomb filter assembly according to  claim 20 , wherein a cell number per square inch is in the range of 120 to 180. 
   
   
       25 . The honeycomb filter assembly according to  claim 20 , wherein a thickness of the cell wall is in the range of 0.20 to 0.46 mm. 
   
   
       26 . The honeycomb filter assembly according to  claim 20 , wherein among the pores of the filter, 20% to 50% are through pores. 
   
   
       27 . The honeycomb filter assembly according to  claim 20 , wherein the filter is made of sintered porous silicon carbide, and the impurities included therein is 5 wt % or less. 
   
   
       28 . The honeycomb filter assembly according to  claim 20 , wherein the specific surface area of the particles forming the cell wall is 0.1 to 1.0 m 2 /g. 
   
   
       29 . The honeycomb filter assembly according to  claim 20 , wherein the specific surface area of the particles forming the cell wall is 0.3 to 0.8 m 2 /g. 
   
   
       30 . An exhaust gas purification apparatus including the honeycomb filter assembly according to  claim 20  arranged in a casing that is located in an exhaust gas passage of an internal combustion engine. 
   
   
       31 . A honeycomb filter having a plurality of cells defined by a cell wall and purifying fluid including particulates with the cell wall,
 wherein the cell wall is formed from a sintered porous ceramic body, and a specific surface area of grains forming the cell wall is 0.1 m 2 /g or more.   
   
   
       32 . The honeycomb filter according to  claim 31 , wherein the cell wall has an outer surface which carries at least one oxide catalyst selected from a platinum group element, other metal elements and oxides of these metal elements. 
   
   
       33 . The honeycomb filter according to  claim 31 , wherein the filter has an average pore diameter of 1 to 50 μm. 
   
   
       34 . The honeycomb filter according to  claim 31 , wherein the filter has an average porosity of 30 to 70%. 
   
   
       35 . The honeycomb filter according to  claim 31 , wherein a cell number per square inch is in the range of 120 to 180. 
   
   
       36 . The honeycomb filter according to  claim 31 , wherein a thickness of the cell wall is in the range of 0.20 to 0.46 mm. 
   
   
       37 . The honeycomb filter according to  claim 31 , wherein among the pores of the filter, 20% to 50% are through pores. 
   
   
       38 . The honeycomb filter according to  claim 31 , wherein the specific surface area of the particles forming the cell wall is 0.1 to 1.0 m 2 /g. 
   
   
       39 . The honeycomb filter according to  claim 31 , wherein the specific surface area of the particles forming the cell wall is 0.3 to 0.8 m 2 /g. 
   
   
       40 . An exhaust-gas purification apparatus including the honeycomb filter according to  claim 31  arranged in a casing that is located in an exhaust gas passage of an internal combustion engine. 
   
   
       41 . A honeycomb filter formed from a sintered porous ceramic body, wherein an average pore diameter of the honeycomb filter is 8 to 12 μm, an average porosity is 30 to 50%, and the honeycomb filter has 20% or more of through pores. 
   
   
       42 . The honeycomb filter according to  claim 41 , wherein the average pore diameter is 8 to 12 um, the average porosity is 35 to 49%, and the ratio of through pores is 20 to 80%. 
   
   
       43 . The honeycomb filter according to  claim 41  comprising a plurality of cells including a first cell having a first end surface sealed by a sealing body and a second cell adjacent to the first cell, the second cell having a second end surface that is opposite to the first surface, the second end surface being sealed by a sealing body, wherein the cell number per square inch is 120 or more, and the thickness of a cell wall defining the cells is 0.46 mm or less. 
   
   
       44 . The honeycomb filter according to  claim 41 , wherein the filter has a plurality of cells, and each cell has an outer surface which carries at least one oxide catalyst selected from a platinum group element, other metal elements and oxides of these metal elements. 
   
   
       45 . The honeycomb filter according to  claim 41 , wherein the filter is formed from a sintered porous silicon carbide body, and the impurities included in the sintered porous silicon carbide is 5 wt % or less. 
   
   
       46 . The honeycomb filter according to  claim 41 , wherein the impurities include Al, Fe, O and free C. 
   
   
       47 . An integral ceramic filter assembly produced by adhering with a ceramic seal layer outer surfaces of a plurality of elongated honeycomb filters, each of which being formed from a sintered porous ceramic body, wherein
 an average pore diameter of the honeycomb filter is 5 to 15 um,   an average porosity is 30 to 50%, and   the honeycomb filter has 20% or more of through pores.   
   
   
       48 . The ceramic filter assembly according to  claim 47 , wherein the average pore diameter is 8 to 12 um, the average porosity is 35 to 49%, and the ratio of through pores is 20 to 80%. 
   
   
       49 . An exhaust gas purification apparatus including the honeycomb filter according to of  claim 47  arranged in a casing that is located in an exhaust gas passage of an internal combustion engine to eliminate particulates included in exhaust gas. 
   
   
       50 . The exhaust gas purification apparatus according to  claim 47 , wherein the total volume of the honeycomb filter is ¼ to 2 times the total displacement of the internal combustion engine.