Honeycomb filter

Patent metadata

Field	Value
Publication number	US-9550175-B2
Application number	US-201414448989-A
Country	US
Kind code	B2
Filing date	Jul 31, 2014
Priority date	Jul 31, 2013
Publication date	Jan 24, 2017
Grant date	Jan 24, 2017

Abstract

A honeycomb filter includes a plurality of cells, porous cell walls, and an oxidation catalyst. The plurality of cells include exhaust gas introduction cells and exhaust gas emission cells. The oxidation catalyst is supported inside the porous cell walls in an amount of 5 to 60 g/L. The exhaust gas emission cells have an average cross sectional area larger than an average cross sectional area of the exhaust gas introduction cells in the cross section perpendicular to the longitudinal direction. A total volume of the exhaust gas introduction cells is larger than a total volume of the exhaust gas emission cells.

First claim

The invention claimed is:

1. A honeycomb filter 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;
porous cell walls defining rims of the plurality of cells;
an oxidation catalyst supported inside the porous cell walls in an amount of 5 to 60 g/L;
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;
the exhaust gas emission cells having an average cross sectional area larger than an average cross sectional area of the exhaust gas introduction cells in the cross section perpendicular to the longitudinal direction; and
a total volume of the exhaust gas introduction cells being larger than a total volume of the exhaust gas emission cells,
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, 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.

3. 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.

4. The honeycomb filter according to claim 3 ,
wherein the porous cell walls separating the plurality of cells have a uniform thickness in any part of the honeycomb filter.

5. The honeycomb filter according to claim 3 ,
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 the 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 the 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 one of the exhaust gas emission cells across the second cell wall among sides forming the cross sectional shape of one of the second 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 cell wall among sides forming the cross sectional shape of one of the first exhaust gas introduction cells is parallel to a side facing one of the first exhaust gas introduction cells across the cell wall among sides forming the cross sectional shape of one of the second exhaust gas introduction cells, and
wherein, in the cross section perpendicular to the longitudinal direction of the plurality of cells, distances between parallel sides are the same.

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 f

Assignees

• Ibiden Co Ltd

Inventors

• Shibata Toshiaki
• Miwa Yuki

Classifications

• F01N3/103

  Oxidation catalysts for HC and CO only · CPC title

• F01N3/0222

  the structure being monolithic, e.g. honeycombs · CPC title

• B01J27/224 Primary

  Silicon carbide · CPC title

• F01N2330/48

  characterised by the number of flow passages, e.g. cell density · CPC title

• F01N2330/34

  with flow channels of polygonal cross section · CPC title