US-20260124570-A1 - HONEYCOMB FILTER

US20260124570A1US 20260124570 A1US20260124570 A1US 20260124570A1US-20260124570-A1

Abstract

A honeycomb filter includes a pillar-shaped honeycomb structure body having a porous partition wall arranged to surround a plurality of cells and a plugging portion, wherein the sectional shape of inflow cells is octagonal and the sectional shape of outflow cells is quadrangular, the area ratio of a sectional area of the outflow cell to the sectional area of the inflow cell is 1.60-1.90, in the honeycomb structure body, the central part of the section orthogonal to the extending direction of the cells is composed of a cell straight region in which the cells extend in a straight line and the outer periphery of the section is composed of a cell curvature region in which the cells extend in a curved manner, and the percentage of the ratio of the curvature height of the cell curvature region to the total length of the honeycomb structure body is 1.00-3.00%.

Inventors

Yuta Nakagoshi
Fumihiko YOSHIOKA
Kyohei Kato
Ren Kasuga

Assignees

NGK INSULATORS, LTD.

Dates

Publication Date: 20260507
Application Date: 20251021
Priority Date: 20241101

Claims (3)

1 . A honeycomb filter comprising: a pillar-shaped honeycomb structure body having a porous partition wall arranged so as to surround a plurality of cells which serve as fluid through channels extending from an inflow end face to an outflow end face; and a plugging portion disposed so as to plug an end on either the inflow end face side or the outflow end face side of the cells, wherein the cells having the plugging portion at ends on the outflow end face side and that are open on the inflow end face side are inflow cells, the cells having the plugging portion at ends on the inflow end face side and that are open on the outflow end face side are outflow cells, in a section orthogonal to the extending direction of the cells of the honeycomb structure body, the sectional shape of the inflow cells is octagonal and the sectional shape of the outflow cells is quadrangular, except for the cells disposed at the outermost circumference of the honeycomb structure body, the area ratio (S 1 /S 2 ) of a sectional area S 2 of the outflow cell having a quadrangular sectional shape to the sectional area S 1 of the inflow cell having an octagonal sectional shape is 1.60 to 1.90, in the honeycomb structure body, the central part of the section orthogonal to the extending direction of the cells is composed of a cell straight region in which the cells extend in a straight line from the inflow end face to the outflow end face, and the outer periphery of the section is composed of a cell curvature region in which the cells extend in a curved manner toward the outer peripheral side in the midway part from the inflow end face to the outflow end face, the length of the honeycomb structure body from the inflow end face to the outflow end face is defined as the total length L, the distance to the extreme point of curvature toward the outer peripheral side of the cell curvature region starting from the boundary between the cell straight region and the cell curvature region is defined as the curvature height h, and the percentage of the ratio of the curvature height h of the cell curvature region to the total length L of the honeycomb structure body (h/L×100%) is 1.00 to 3.00%.
2 . The honeycomb filter according to claim 1 , wherein a thickness of the partition wall is 0.17 to 0.36 mm.
3 . The honeycomb filter according to claim 1 , wherein a cell density of the honeycomb structure body is 30 to 63 cells/cm 2 .

Description

This application claims the benefit of priority from the prior Japanese Patent Application No. 2024-192860, filed on Nov. 1, 2024, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD The present invention relates to a honeycomb filter. More specifically, the present invention relates to a honeycomb filter which can effectively suppress the increase in pressure loss when particulate matter such as soot adheres to the surface of a partition wall and achieve excellent purification performance when loaded with an exhaust gas purifying catalyst. DESCRIPTION OF RELATED ART Conventionally, a honeycomb filter using a honeycomb structure has been known as a filter for trapping particulate matter in exhaust gas emitted from an internal combustion engine such as an automobile engine, or a device for purifying toxic gas components such as CO, HC, and NOx (see Patent Document 1). The honeycomb structure includes a partition wall made of porous ceramics such as cordierite and a plurality of cells defined by the partition wall. A honeycomb filter includes such a honeycomb structure provided with plugging portions so as to plug the open ends on the inflow end face side and the outflow end face side of the plurality of cells alternately. In other words, the honeycomb filter has a structure in which inflow cells having the inflow end face side open and the outflow end face side plugged and outflow cells having the inflow end face side plugged and the outflow end face side open are arranged alternately with the partition wall therebetween. In the honeycomb filter, the porous partition wall serves as a filter for trapping the particulate matter in exhaust gas. Hereinafter, the particulate matter contained in exhaust gas may be referred to as “PM”. The “PM” is an abbreviation for “Particulate Matter”. Exhaust gas is purified by a honeycomb filter as follows. First, the honeycomb filter is disposed such that the inflow end face side is positioned on the upstream side of an exhaust system through which exhaust gas is emitted. The exhaust gas flows into inflow cells from the inflow end face side of the honeycomb filter. Then, the exhaust gas that has flowed into the inflow cells passes through a porous partition wall, flows toward outflow cells, and is emitted from the outflow end face of the honeycomb filter. When PM in the exhaust gas is continuously removed by the honeycomb filter, PM such as soot accumulates inside the honeycomb filter, reducing the purification efficiency and increasing the pressure loss of the honeycomb filter. Therefore, for example, in purification devices using the honeycomb filter, a “regeneration process” is performed to burn PM that has accumulated inside the honeycomb filter. [Patent document 1] International Publication WO 2006/095835 A honeycomb filter used to purify exhaust gas emitted from engines of automobiles and the like has a problem that pressure loss increases due to adhesion of particulate matter such as soot on the surface of the partition wall. Therefore, there is a demand for the development of a honeycomb filter that can suppress the increase in pressure loss. For example, as one of the measures for reducing pressure loss, studies have been conducted on “thinner walls” to reduce the thickness of the partition walls of a honeycomb filter. However, reducing the thickness of the partition wall causes a decrease in trapping performance of the honeycomb filter. In addition, when the thickness of the partition wall is reduced, the heat capacity of the entire honeycomb filter becomes lower, and the honeycomb filter is more easily damaged in the regeneration process as described above. On the other hand, increasing the thickness of the partition wall increases the pressure loss of the honeycomb filter and increases the mass of the honeycomb filter, which leads to a deterioration in catalytic performance (in other words, purification performance) of the exhaust gas purifying catalyst loaded on the honeycomb filter. SUMMARY OF THE INVENTION The present invention was made in view of the problems with the prior arts described above. The present invention provides a honeycomb filter that can effectively suppress the increase in pressure loss when particulate matter such as soot adheres to the surface of the partition wall, and can achieve excellent purification performance when loaded with an exhaust gas purifying catalyst. According to the present invention, a honeycomb filter described below is provided. [1] A honeycomb filter including: a pillar-shaped honeycomb structure body having a porous partition wall arranged so as to surround a plurality of cells which serve as fluid through channels extending from an inflow end face to an outflow end face; and a plugging portion disposed so as to plug an end on either the inflow end face side or the outflow end face side of the cells, wherein the cells having the plugging portion at ends on the outflow end face side and th