Honeycomb filter
A honeycomb segment has two kinds of cells having different cross-sectional areas in a cross-section cut along a plane perpendicular to the longitudinal direction of the segment. When the cells are cut along a plane perpendicular to the longitudinal direction of the cells, each cross-sectional area of first cells (large cells) is larger than that of second cells (small cells). The first cells are formed into an octagon where corners are cut off or into a square having circular arc corners. The second cells are formed into a square. The thickness of a 1-1 wall between the adjacent first cells is larger than that of a 1-2 wall between each first cell and each second cell adjacent to the first cell.
1. A honeycomb filter including porous partition walls which define a plurality of cells as through channels of a fluid, first cells opened in one end of the filter and plugged in the other end thereof and second cells plugged in the one end and opened in the other end being alternately arranged, the fluid flowing into the one end of the filter where the first cells open being passed through the partition walls and being discharged as the passed fluid into the second cells, the passed fluid being discharged from the other end of the filter where the second cells open,
wherein each cross-sectional area of the first cells is larger than that of the second cells in a cross section cut along a plane perpendicular to the longitudinal direction of the cells,
the first cells and the second cells are alternately arranged in a first direction and a second direction perpendicular to the first direction in the cross section cut along the plane perpendicular to the longitudinal direction of the cells,
the thickness of a 1-1 wall between the adjacent first cells is larger than that of a 1-2 wall between each first cell and the second cell adjacent to the first cell, and
the thicknesses of the porous partition walls satisfy the following formula (1):
1<Rib 1-1 /Rib 1-2 <1.175 (1),
in which
Rib 1-1 is the thickness of the 1-1 wall between the adjacent first cells; and
Rib 1-2 : the thickness of the 1-2 wall between the first cell and the second cell adjacent to the first cell.
2. The honeycomb filter according to claim 1 , wherein the first cells are formed into an octagon where corners are cut off or into a square having circular arc corners, and
the second cells are formed into a square.
3. The honeycomb filter according to claim 1 , wherein the thicknesses of the walls between the cells and the widths of the cells satisfy the following formula (2):
Rib
1
-
1
≥
2
2
l
-
1
2
W
1
+
1
2
W
2
=
Rib
1
-
2
,
(
2
)
in which
W 1 : the width of the first cell;
W 2 : the width of the second cell; and
l: the thickness of the wall between the adjacent second cells.
4. The honeycomb filter according to claim 2 , wherein the thicknesses of the walls between the cells and the widths of the cells satisfy the following formula (2):
Rib
1
-
1
≥
2
2
l
-
1
2
W
1
+
1
2
W
2
=
Rib
1
-
2
,
(
2
)
in which
W 1 : the width of the first cell;
W 2 : the width of the second cell; and
l: the thickness of the wall between the adjacent second cells.
5. The honeycomb filter according to claim 1 , wherein a plurality of honeycomb segments including the first cells and the second cells being arranged in parallel with one another in the longitudinal direction are joined via joining material layers.
6. The honeycomb filter according to claim 2 , wherein a plurality of honeycomb segments including the first cells and the second cells being arranged in parallel with one another in the longitudinal direction are joined via joining material layers.
7. The honeycomb filter according to claim 3 , wherein a plurality of honeycomb segments including the first cells and the second cells being arranged in parallel with one another in the longitudinal direction are joined via joining material layers.
8. The honeycomb filter according to claim 4 , wherein a plurality of honeycomb segments including the first cells and the second cells being arranged in parallel with one another in the longitudinal direction are joined via joining material layers.