초록 ▼

A column shaped filter having a honeycomb structure including a number of through holes extending parallel with one another in the length direction with wall portion interposed therebetween. The through holes are constituted by large-capacity through holes having a relatively larger cross-sectional

A column shaped filter having a honeycomb structure including a number of through holes extending parallel with one another in the length direction with wall portion interposed therebetween. The through holes are constituted by large-capacity through holes having a relatively larger cross-sectional area in the cross section perpendicular to the length direction and small-capacity through holes having a relatively smaller cross-sectional area in the cross section. The numbers of the two types of through holes are substantially set to the same. The large-capacity through holes are sealed at one end of the filter, while the small-capacity through holes are sealed at the other end of the filter. The large-capacity and small-capacity through holes have a ratio of partition wall length, α, and an aperture ratio, β, and α and β satisfy β≧(20/9)α2+1 (where 0<α≦1.5 and 1<β≦6).

대표청구항 ▼

The invention claimed is: 1. A filter comprising: a honeycomb structural body having a plurality of through holes extending parallel with one another in a length direction of the honeycomb structural body, the honeycomb structural body having a wall portion interposed between the through holes; and

The invention claimed is: 1. A filter comprising: a honeycomb structural body having a plurality of through holes extending parallel with one another in a length direction of the honeycomb structural body, the honeycomb structural body having a wall portion interposed between the through holes; and a sealing material layer formed on a circumference of the honeycomb structural body, wherein said plurality of through holes includes a plurality of large-capacity through holes and a plurality of small-capacity through holes, said large-capacity through holes and said small-capacity through holes being substantially same in numbers, said large-capacity through holes are sealed at one end of said honeycomb structural body, said small-capacity through holes are sealed at the other end of said honeycomb structural body, said large-capacity through holes and said small-capacity through holes have a ratio of partition wall length, α, and an aperture ratio, β, and said α and said β satisfy 0<α≦1.5, 2≦β≦2.75, and β≧(20/9)α2+1. 2. The filter according to claim 1, wherein the large-capacity through holes have a total cross-section area which is larger than a total cross-section area of the small-capacity through holes. 3. The filter according to claim 1, wherein the large-capacity through holes have an octagonal shape in a cross-section perpendicular to the length direction and the small-capacity through holes have a quadrangle or square shape in the cross-section. 4. The filter according to claim 1, wherein the large-capacity through holes and small-capacity through holes are alternately formed in the honeycomb structural body. 5. The filter according to claim 1, wherein at least one of the plurality of large-capacity through holes and the plurality of small-capacity through holes has a polygonal shape in a cross section perpendicular to the length direction. 6. The filter according to claim 1, wherein at least one of the plurality of large-capacity through holes and the plurality of small-capacity through holes has one of an octagonal shape, a quadrangle shape and a square shape in a cross section perpendicular to the length direction. 7. The filter according to claim 1, wherein in the cross-section, at least one angle formed at a point where a first wall portion, which is shared by a large-capacity through hole and an adjacent large capacity through hole, intersects a second wall portion, which is shared by a large-capacity through hole and an adjacent small-capacity through hole, is an obtuse angle. 8. The filter according to claim 1, wherein in said cross-section, at least one of the plurality of large-capacity through holes and the plurality of small-capacity through holes has chamfered corner portions. 9. The filter according to claim 1, wherein a distance between centers of gravity in the cross-section of nearest ones of the large-capacity through holes is same as a distance between centers of gravity in the cross-section of nearest ones of the small-capacity through holes. 10. The filter according to claim 1, having an isostatic strength of 7 MPa or more. 11. The filter according to claim 1, having a compression strength of A-axis of 18 MPa or more. 12. The filter according to claim 1, which is configured to be an exhaust gas purifying apparatus in a vehicle. 13. A filter comprising: a plurality of porous ceramic members each having a plurality of through holes extending parallel with one another in a length direction of the porous ceramic members, each of the porous ceramic members having a wall portion interposed between the through holes; and a first sealing material layer formed on a circumference of the plurality of porous ceramic members, wherein said plurality of through holes includes a plurality of large-capacity through holes and a plurality of small-capacity through holes, said large-capacity through holes and said small-capacity through holes being substantially same in numbers, said large-capacity through holes are sealed at one end of said porous ceramic members, said small-capacity through holes are sealed at the other end of said porous ceramic members, said large-capacity through holes and said small-capacity through holes have a ratio of partition wall length, α, and an aperture ratio, β, and said α and said β satisfy 0<α≦1.5, 2≦β≦2.75, and β≧(20/9)α2+1. 14. The filter according to claim 13, wherein the plurality of porous ceramic members are combined with one another with a second sealing material. 15. The filter according to claim 13, wherein the large-capacity through holes have a total cross-section area which is larger than a total cross-section area of the small-capacity through holes. 16. The filter according to claim 13, wherein the large-capacity through holes have an octagonal shape in a cross-section perpendicular to the length direction and the small-capacity through holes have a quadrangle or square shape in the cross-section. 17. The filter according to claim 13, wherein the large-capacity through holes and small-capacity through holes are alternately formed in each of the porous ceramic members. 18. The filter according to claim 13, wherein at least one of the plurality of large-capacity through holes and the plurality of small-capacity through holes has a polygonal shape in a cross section perpendicular to the length direction. 19. The filter according to claim 13, wherein at least one of the plurality of large-capacity through holes and the plurality of small-capacity through holes has one of an octagonal shape, a quadrangle shape and a square shape in a cross section perpendicular to the length direction. 20. The filter according to claim 13, wherein in the cross-section, at least one angle formed at the point where a first wall portion, which is shared by a large-capacity through hole and an adjacent large-capacity through hole, intersects a second wall portion, which is shared by a large-capacity through hole and an adjacent small-capacity through hole, is an obtuse angle. 21. The filter according to claim 13, wherein in said cross-section, at least one of the plurality of large-capacity through holes and the plurality of small-capacity through holes has chamfered corner portions. 22. The filter according to claim 13, wherein a distance between centers of gravity in the cross-section of nearest ones of the large-capacity through holes is same as a distance between centers of gravity in the cross-section of nearest ones of the small-capacity through holes. 23. The filter according to claim 13, having an isostatic strength of 7 MPa or more. 24. The filter according to claim 13, having a compression strength of A-axis of 18 MPa or more. 25. The filter according to claim 13, which is configured to be an exhaust gas purifying apparatus in a vehicle.