Honeycomb filter

Patent metadata

Field	Value
Publication number	US-9702283-B2
Application number	US-201414449008-A
Country	US
Kind code	B2
Filing date	Jul 31, 2014
Priority date	Jul 31, 2013
Publication date	Jul 11, 2017
Grant date	Jul 11, 2017

Abstract

A honeycomb filter includes a silicon carbide honeycomb fired body, an end face, and porous cell walls. The silicon carbide honeycomb fired body includes a plurality of cells through which exhaust gas is to flow and which include exhaust gas introduction cells and exhaust gas emission cells. The silicon carbide honeycomb fired body includes silicon carbide grains having a silicon-containing oxide layer with a thickness of 0.1 to 2 μm on surfaces of the silicon carbide grains. The end face has an aperture ratio of not less than 20% at the exhaust gas emission side. The porous cell walls define rims of the plurality of cells. The plugged portions of the exhaust gas introduction cells are arranged in vertical and horizontal lines with the porous cell walls residing between the plugged portions in the end face at the exhaust gas emission side.

First claim

The invention claimed is:

1. A honeycomb filter comprising:
a silicon carbide honeycomb fired body comprising a plurality of cells through which exhaust gas is to flow and which include exhaust gas introduction cells and exhaust gas emission cells, the exhaust gas introduction cells each having an open end at an exhaust gas introduction side and a plugged end at an exhaust gas emission side, the exhaust gas emission cells each having an open end at the exhaust gas emission side and a plugged end at the exhaust gas introduction side, the silicon carbide honeycomb fired body including silicon carbide grains having a silicon-containing oxide layer with a thickness of 0.1 to 2 μm on surfaces of the silicon carbide grains, the exhaust gas introduction cells and the exhaust gas emission cells each having a uniform cross sectional shape except for a plugged portion in a cross section perpendicular to a longitudinal direction of the plurality of cells thoroughly from the exhaust gas introduction side to the exhaust gas emission side;
an end face with an aperture ratio of not less than 20% at the exhaust gas emission side; and
porous cell walls defining rims of the plurality of cells, the plugged portions of the exhaust gas introduction cells being arranged in vertical and horizontal lines with the porous cell walls residing between the plugged portions in the end face at the exhaust gas emission side,
wherein each of the exhaust gas emission cells is adjacently surrounded fully by the exhaust gas introduction cells across the porous cell walls,
wherein the exhaust gas introduction cells include first exhaust gas introduction cells and second exhaust gas introduction cells,
wherein each of the second exhaust gas introduction cells has a cross sectional area larger than a cross sectional area of each of the first exhaust gas introduction cells in the cross section perpendicular to the longitudinal direction of the plurality of cells,
wherein each of the exhaust gas emission cells has a cross sectional area equal to or larger than the cross sectional area of each of the second exhaust gas introduction cells in the cross section perpendicular to the longitudinal direction of the plurality of cells,
wherein, in the cross section perpendicular to the longitudinal direction of the plurality of cells, the exhaust gas introduction cells and the exhaust gas emission cells each have a polygonal shape, and
wherein, in the cross section perpendicular to the longitudinal direction of the plurality of cells,
a side forming a cross sectional shape of each of the first exhaust gas introduction cells faces one of the exhaust gas emission cells, a side forming a cross sectional shape of each of the second exhaust gas introduction cells faces one of the exhaust gas emission cells, and the side of each of the first exhaust gas introduction cells is longer than the side of each of the second exhaust gas introduction cells, or
a side forming a cross sectional shape of each of the first exhaust gas introduction cells faces one of the exhaust gas emission cells, and none of sides forming a cross sectional shape of each of the second exhaust gas introduction cells faces the exhaust gas emission cells.

2. The honeycomb filter according to claim 1 ,
wherein the end face at the exhaust gas emission side has an aperture ratio of not less than 25%.

3. The honeycomb filter according to claim 1 ,
wherein the plugged portions of the exhaust gas introduction cells have a width of not less than 0.5 mm.

4. The honeycomb filter according to claim 1 ,
wherein, in the cross section perpendicular to the longitudinal direction of the plurality of cells, the exhaust gas introduction cells and the exhaust gas emission cells each have the polygonal shape, and
wherein, in the cross section perpendicular to the longitudinal direction of the plurality of cells, length of the side forming the cross sectional shape of each of the second exhaust gas introduction cells is not more than 0.8 times length of the side forming the cross sectional shape of each of the first exhaust gas introduction cells.

5. The honeycomb filter according to claim 1 ,
wherein, in the cross section perpendicular to the longitudinal direction of the plurality of cells, the exhaust gas emission cells are each octagonal, the first exhaust gas introduction cells are each square, and the second exhaust gas introduction cells are each octagonal.

6. The honeycomb filter according to claim 1 ,
wherein, in the cross section perpendicular to the longitudinal direction of the plurality of cells, the cross sectional area of each of the second exhaust gas introduction cells is equal in size to the cross sectional area of each of the exhaust gas emission cells, and
wherein the cross sectional area of each of the first exhaust gas introduction cells is 20 to 50% size of the cross sectional area of each of the second exhaust gas introduction cells.

7. The honeycomb filter according to claim 5 ,
wherein the porous cell walls separating the plurality of cells have a uniform thickness in any part of the honeycomb filter.

8. The honeycomb filter according to claim 5 ,
wherein, in the cross section perpendicular to the longitudinal direction of the plurality of cells, the exhaust gas emission cells have octagonal cross sections, the first exhaust gas introduction cells have square cross sections, and the second exhaust gas introduction cells have octagonal cross sections,
wherein, in the cross section perpendicular to the longitudinal direction of the plurality of cells, the cross sectional shape of each of the second exhaust gas introduction cells is congruent with a cross sectional shape of each of the exhaust gas emission cells, and
wherein, in the cross section perpendicular to the longitudinal direction of the plurality of cells, the exhaust gas emission cells, the first exhaust gas introduction cells, and the second exhaust gas introduction cells are arranged in a manner that
the exhaust gas emission cells are each surrounded by alternately arranged four pieces of the first exhaust gas introduction cells and four pieces of the second exhaust gas introduction cells across the porous cell walls,
provided that hypothetical segments connecting geometric centers of gravity of octagonal cross sections of the four pieces of the second exhaust gas introduction cells surrounding a reference exhaust gas emission cell of the exhaust gas emission cells are given, an intersection of two segments crossing the reference exhaust gas emission cell is identical with a geometric center of gravity of an octagonal cross section of the reference exhaust gas emission cell, and
four segments not crossing the reference exhaust gas emission cell form a square, and midpoints of respective sides of the square are identical with geometric centers of gravity of square cross sections of the four pieces of the first exhaust gas introduction cells surrounding the reference exhaust gas emission cell,

wherein, in the cross section perpendicular to the longitudinal direction of the plurality of cells, a side facing one of the first exhaust gas introduction cells across a first cell wall among sides forming the cross sectional shape of one of the exhaust gas emission cells is parallel to a side facing one of the exhaust gas emission cells across the first cell wall among sides forming the cross sectional shape of one of the first exhaust gas introduction cells,
wherein, in the cross section perpendicular to the longitudinal direction of the plurality of cells, a side facing one of the second exhaust gas introduction cells across a second cell wall among sides forming the cross sectional shape of one of the exhaust gas emission cells is parallel to a side facing o

Assignees

• Ibiden Co Ltd

Inventors

• Shibata Toshiaki
• Miwa Yuki

Classifications

• C04B35/565

  based on silicon carbide · CPC title

• C04B2111/0081

  as catalysts or catalyst carriers · CPC title

• C04B2235/3826

  Silicon carbides · CPC title

• C04B38/0009

  characterised by features relating to the cell walls, e.g. wall thickness or distribution of pores in the walls · CPC title

• F01N2370/22

  used in non-catalytic purification apparatus · CPC title