Honeycomb filter and ceramic filter assembly

• US 7,427,309 B2
• Filed: 09/21/2005
• Issued: 09/23/2008
• Est. Priority Date: 09/29/1999
• Status: Expired due to Term

• Current Assignee: Ibiden Co., Ltd.
• Original Assignee: Ibiden Co., Ltd.
• Inventors: Ohno, Kazushige, Shimato, Koji, Tsuji, Masahiro
• Primary Examiner(s): Greene; Jason M
• Application Number:
  US11/230,844
• Publication Number:
  US 20060021310A1
• Time in Patent Office: 1,098 Days
• Field of Search: 553/853, 554/83, 555/02, 555/23, 555/24, 555/29, 55D/IG.5, 55D/IG.30, 428/327, 428/116, 428/117, 428/119, 428/188, 428/690, 428/913, 428/118, 502/493, 156/89, 264/628, 264/630, 603/11
• US Class Current: 55/523
• CPC Class Codes: B01D 2279/30 for treatment of exhaust gases from IC Engines
• CPC Class Codes: B01D 39/2075 sintered or bonded by inorganic agents
• CPC Class Codes: B01D 39/2086 sintered or bonded by inorganic agents
• CPC Class Codes: B01D 46/2429 of the honeycomb walls or cells
• CPC Class Codes: B01D 46/2448 of the adhesive layers, i.e. joints between segments
• CPC Class Codes: B01D 46/24491 Porosity
• CPC Class Codes: B01D 46/24492 Pore diameter
• CPC Class Codes: B01D 46/24494 Thermal expansion coefficient, heat capacity or thermal conductivity
• CPC Class Codes: B01D 46/2455 of the whole honeycomb or segments
• CPC Class Codes: B01D 46/2462 the outer peripheral sealing
• CPC Class Codes: B01D 46/2466 of the adhesive layers, i.e. joints between segments
• CPC Class Codes: B01D 46/2474 of the walls along the length of the honeycomb
• CPC Class Codes: B01D 46/2478 Structures comprising honeycomb segments
• CPC Class Codes: B01D 46/2482 Thickness, height, width, length or diameter
• CPC Class Codes: B01D 46/2484 Cell density, area or aspect ratio
• CPC Class Codes: B01D 46/2486 characterised by the shapes or configurations
• CPC Class Codes: B01D 46/2496 Circular
• CPC Class Codes: B01D 46/2498 The honeycomb filter being defined by mathematical relationships
• CPC Class Codes: B29C 48/11 comprising two or more partially or fully enclosed cavities, e.g. honeycomb-shaped
• CPC Class Codes: B29C 48/12 Articles with an irregular circumference when viewed in cross-section, e.g. window profiles
• CPC Class Codes: C04B 14/324 : Silicon carbide
• CPC Class Codes: C04B 14/4656 : Al-silicates, e.g. clay
• CPC Class Codes: C04B 2111/00612 : as one or more layers of a layered structure
• CPC Class Codes: C04B 2111/00793 : as filters or diaphragms
• CPC Class Codes: C04B 2235/383 : Alpha silicon carbide
• CPC Class Codes: C04B 2235/5224 : Alumina or aluminates
• CPC Class Codes: C04B 2235/5228 : Silica and alumina, including aluminosilicates, e.g. mullite
• CPC Class Codes: C04B 2235/5264 : characterised by the diameter of the fibers
• CPC Class Codes: C04B 2235/5436 : micrometer sized, i.e. from 1 to 100 micron
• CPC Class Codes: C04B 2235/5445 : submicron sized, i.e. from 0,1 to 1 micron
• CPC Class Codes: C04B 2235/5472 : Bimodal, multi-modal or multi-fraction
• CPC Class Codes: C04B 2237/08 : Non-oxidic interlayers
• CPC Class Codes: C04B 2237/083 : Carbide interlayers, e.g. silicon carbide interlayers
• CPC Class Codes: C04B 2237/09 : wherein the active component for bonding is not the largest fraction of the interlayer
• CPC Class Codes: C04B 2237/365 : Silicon carbide
• CPC Class Codes: C04B 24/383 : Cellulose or derivatives thereof
• CPC Class Codes: C04B 28/24 : containing alkyl, ammonium or metal silicates; containing silica sols reaction mixtures resulting in mineral polymers C04B28/006; polymeric reaction products of alkali metal silicates with isocyanates C08G18/3895
• CPC Class Codes: C04B 35/565 : based on silicon carbide
• CPC Class Codes: C04B 35/6269 : Curing of mixtures
• CPC Class Codes: C04B 37/005 : consisting of glass or ceramic material
• CPC Class Codes: C04B 38/0009 : characterised by features relating to the cell walls, e.g. wall thickness or distribution of pores in the walls
• CPC Class Codes: C04B 38/0054 : the pores being microsized or nanosized
• CPC Class Codes: C04B 38/0074 : expressed as porosity percentage
• CPC Class Codes: C04B 38/008 : Bodies obtained by assembling separate elements having such a configuration that the final product is porous or by spirally winding one or more corrugated sheets
• CPC Class Codes: C04B 41/5089 : Silica sols, alkyl, ammonium or alkali metal silicate cements
• CPC Class Codes: F01N 2260/10 : for avoiding stress caused by expansions or contractions due to temperature variations
• CPC Class Codes: F01N 2330/06 : Ceramic, e.g. monoliths
• CPC Class Codes: F01N 2330/14 : Sintered material
• CPC Class Codes: F01N 2330/30 : Honeycomb supports characterised by their structural details
• CPC Class Codes: F01N 2450/28 : by using adhesive material, e.g. cement
• CPC Class Codes: F01N 3/0222 : the structure being monolithic, e.g. honeycombs
• CPC Class Codes: Y02T 10/12 : Improving ICE efficiencies
• CPC Class Codes: Y10S 264/48 : Processes of making filters
• CPC Class Codes: Y10S 55/05 : Methods of making filter
• CPC Class Codes: Y10S 55/30 : Exhaust treatment
• CPC Class Codes: Y10T 428/24149 : Honeycomb-like

Abstract

A ceramic filter assembly having improved exhaust gas processing efficiency. The ceramic filter assembly (9) is produced by adhering with a ceramic seal layer (15) outer surfaces of a plurality of filters (F1), each of which is formed from a sintered porous ceramic body. The seal layer (15) has a thickness of 0.3 mm to 3 mm and a thermal conductance of 0.1 W/mK to 10 W/mk.

Claims

1. 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 is formed from a sintered porous ceramic body,

wherein the assembly as a whole has a generally circular cross-section, and wherein the seal layer has a thickness of 0.3 to 3 mm and a thermal conductance of 0.1 to 10 W/mk.

2. The ceramic filter assembly according to claim 1, wherein the seal layer includes 70 wt % or less of ceramic fiber as a solid.

3. The ceramic filter assembly according to claim 1, wherein the seal layer includes ceramic fibers having fiber lengths of 100 mm or less.

4. The ceramic filter assembly according to claim 1, wherein the seal layer includes as a solid 3 wt % to 80 wt % of inorganic grains.

5. The ceramic filter assembly according to claim 1, wherein the assembly is a diesel particulate filter.

6. The ceramic filter assembly according to claim 1, wherein the seal-layer includes at least inorganic fibers, an inorganic binder, an organic binder, and inorganic particles and is formed from an elastic material obtained by bonding the inorganic fibers and inorganic grains, which are three-dimensionally interlinked with one another, with the inorganic binder and the organic binder.

7. The ceramic filter assembly according to claim 1, wherein the seal layer is formed from 10 wt % to 70 wt % of silica-alumina ceramic fiber, 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.

8. The ceramic 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.

9. The ceramic filter assembly according to claim 1, 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.

10. The ceramic filter assembly according to claim 1, wherein the filter has an average porosity of 30 to 70%.

11. The ceramic filter assembly according to claim 1, wherein the filter has a thermal conductance of 20 to 80 W/mk.

12. The ceramic filter assembly according to claim 1, wherein the seal layer has a thickness of 0.5 to 1.0 mm and a thermal conductance of 0.3 to 10 W/mk.

13. An exhaust gas purification apparatus having 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.

14. The exhaust gas purification apparatus according to claim 13, wherein a middle portion of the casing has a diameter larger than that of the exhaust gas passage.

15. The exhaust gas purification apparatus according to claim 13, wherein a thermal insulative material composed of a mat-like material including ceramic fibers is arranged between the outer surface of the ceramic filter assembly and the inner surface of the casing.

16. 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

the ceramic filter assembly is a diesel particulate filter, and includes round surfaces defined on chamfered corners of the outer surface of each honeycomb filter, wherein the round surfaces have a radius of curvature (R) of 0.3 mm to 2.5 mm.

18. The ceramic filter assembly according to claim 16, wherein the filters are arranged in a state offset from one another in a direction perpendicular to a filter axial direction.

20. The ceramic filter assembly according to claim 16, 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.

22. The ceramic filter assembly according to claim 16, wherein the average pore diameter of the honeycomb filter is 1 to 50 μ

m.

24. The ceramic filter assembly according to claim 16, wherein the filter has an average porosity of 30 to 70%.

26. The ceramic filter assembly according to claim 16, wherein the assembly has an outer form in a round cross-section or oval cross-section.

28. An exhaust gas purification apparatus having the ceramic filter assembly according to claim 16 arranged in a casing that is located in an exhaust gas passage of an internal combustion engine.

17. 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 the ceramic filter assembly is formed from a sintered porous silicon carbide, and includes round surfaces defined on chamfered corners of the outer surface of each honeycomb filter, wherein the round surfaces have a radius of curvature (R) of 0.3 mm to 2.5 mm.

19. The ceramic filter assembly according to claim 17, wherein the filters are arranged in a state offset from one another in a direction perpendicular to a filter axial direction.

21. The ceramic filter assembly according to claim 17, 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.

23. The ceramic filter assembly according to claim 17, wherein the average pore diameter of the honeycomb filter is 1 to 50 μ

m.

25. The ceramic filter assembly according to claim 17, wherein the filter has an average porosity of 30 to 70%.

27. The ceramic filter assembly according to claim 17, wherein the assembly has an outer form in a round cross-section or oval cross-section.

29. An exhaust gas purification apparatus having the ceramic filter assembly according to claim 17 arranged in a casing that is located in an exhaust gas passage of an internal combustion engine.

30. An integral ceramic filter assembly produced by adhering with a ceramic seal layer outer surfaces of a plurality of filters, each of which is formed from a sintered porous ceramic body,

wherein the assembly as a whole has a generally circular cross-section, and wherein a ceramic smoothing layer is provided on the outer surface of the assembly.

31. The ceramic filter assembly according to claim 30, wherein the smoothing layer has a thickness of 0.1 mm to 10 mm.

32. The ceramic filter assembly according to claim 30, wherein the seal layer is thinner than the smoothing layer.

33. The ceramic filter assembly according to claim 30, wherein the smoothing layer is made from the same material as the seal layer.

34. The ceramic filter assembly according to claim 30, wherein the assembly is a diesel particulate filter.

35. The ceramic filter assembly according to claim 30, wherein the assembly is formed from a sintered porous silicon carbide.

36. The ceramic filter assembly according to claim 30, wherein the seal layer includes at least inorganic fibers, an inorganic binder, an organic binder, and inorganic particles and is formed from an elastic material obtained by bonding the inorganic fibers and inorganic grains, which are three-dimensionally interlinked one another, with the inorganic binder and the organic binder.

37. The ceramic filter assembly according to claim 30, wherein the seal layer ss formed from 10 wt % to 70 wt % of silica-alumina ceramic fiber, 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.

38. The ceramic filter assembly according to claim 30, wherein the filters are arranged in a state offset from one another in a direction perpendicular to a filter axial direction.

39. The ceramic filter assembly according to claim 30, 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.

40. The ceramic filter assembly according to claim 30, wherein the average pore diameter of the honeycomb filter is 1 to 50 μ

m.

41. The ceramic filter assembly according to claim 30, wherein the filter has an average porosity of 30 to 70%.

42. The ceramic filter assembly according to claim 30, wherein pits defined by ridges and valleys partially exposed from the outer surface are provided extending in the axial direction of the assembly, and wherein the pits are filled with the ceramic smoothing layer.

43. The ceramic filter assembly according to claim 30, wherein the smoothing, layer is made from the different material from the seal layer.

44. The ceramic filter assembly according to claim 30, wherein the smoothing layer has a thermal conductance of 0.1 to 10 W/mk.

45. An exhaust gas purification apparatus having the ceramic filter assembly according to claim 30 arranged in a casing that is located in an exhaust gas passage of an internal combustion engine.

46. Method for manufacturing a ceramic honeycomb structural body comprising the steps of:

making ceramic honeycomb filter which is formed from a sintered porous ceramic body;

adhering outer surfaces of a plurality of the filters with a ceramic seal layer to produce an integral ceramic filter assembly;

cutting the peripheral portion of the assembly to form an outer shape thereof; and

applying a paste to the exposed outer surface of the assembly to provide a smoothing layer.

47. 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 0.06 to 0.75 mm/mm², and the filter length L is 167 to 300 mm;

and

wherein the filters are arranged in a state offset from one another in a direction perpendicular to a filter axial direction.