The exhaust gas purification device provided with a particulate filter disposed in an exhaust passage of an internal combustion engine and capturing particulate matter in exhaust gas discharged from the internal combustion engine. The particulate filter is provided with a wall-flow part having an inlet-side cell that is open only at an end on an exhaust gas inflow side, an outlet-side cell that is adjacent to this inlet-side cell and is open only at an end on an exhaust gas outflow side, and a porous wall that partitions the inlet-side cell from the outlet-side cell, and is also provided with a straight-flow part having a through cell that penetrates the filter in an axial direction thereof and is open at the end on the exhaust gas inflow side as well as the end on the exhaust gas outflow side.

Honeycomb monolith structure, especially for use as catalyst or support for a catalyst in selective catalytic reduction (SCR) of nitrogen oxides, comprising: a plurality of cell walls defining a plurality of polygonal channels, the plurality of cell walls and channels extending in parallel along a common direction from an entrance end to an outlet end of the structure in the fluid flow direction. The transversal cross section of a polygonal channel has the shape of a convex polygon in closest packing, wherein more than 50% of the internal angels between two adjacent walls of the convex polygon are above 90 degrees and wherein the cell aspect ratio L.sub.L/L.sub.S is greater than 1.5. The monolith structure has an outer row of polygons in shifted direction perpendicular to each other at the two side edges of the monolith which are parallel to the longest direction of the cells/channels.

A honeycomb filter includes a plugged honeycomb structure body which has cell rows arranged along one direction in a cross section of the honeycomb structure body and including a first cell row constituted of inflow cells and a second cell row including outflow cells. A width P1 (mm) of the first cell row, a width P2 (mm) of the second cell row and a curvature radius R (m) of a curved shape of corner portions of a polygonal shape of each cell satisfy relations of Equations (1) and (2) below: Equation (1): 2100(P1/P2100)50, and Equation (2): 0.4(R/1000)/((P1+P2)/2)10020.

A manufacturing method of a honeycomb structure includes a forming step of forming a honeycomb formed body by use of a kneaded material containing a cordierite forming raw material, a slurry coating step of coating a coating layer forming slurry which contains a cordierite forming raw material on four regions in a rotation area when each of two straight lines passing through the center of gravity of the cross section and extending in a diagonal direction of main quadrangular cells is rotated in a range of x of the center of gravity in a circumferential surface, and a firing step of firing the honeycomb formed body on which the slurry is coated. The value x is in a range of 7 to 45, and the slurry is adjusted so that the coating layer has a porosity higher than that of the honeycomb structure body as much as 5% or more.

A plugged honeycomb structure includes: a plurality of honeycomb segments, a bonding layer, and plugging portions to plug open ends of cells of the honeycomb segment. Each honeycomb segment is configured so that the cells having at least two types of different shapes have a predetermined repeated sequence pattern. A circumferential-wall partially surrounded cell in which a partition wall and a segment circumferential wall are disposed so as to surround the cell has an area of open end that has a specific ratio to an area of open end of a partition-wall entirely surrounded cell including the cross-sectional shape of the circumferential-wall partially surrounded cell. The repeated sequence pattern of the cells is kept at a boundary between two of the honeycomb segments bonded with the bonding layer at an inflow end face and an outflow end face.

Particulate filter provided in the exhaust gas purification device includes: a wall-flow part having an inlet-side cell that is open only at an end on an exhaust gas inflow side, outlet-side cell adjacent to this inlet-side cell and is open only at an end on an exhaust gas outflow side, a porous wall partitions the inlet-side cell from the outlet-side cell; a straight-flow part having a through cell that penetrates the filter in axial direction and is open at the end on the exhaust gas inflow side as well as the end on the exhaust gas outflow side. In a cross section of the filter orthogonal to its axial direction, cross-sectional areas of the inlet-side cell and outlet-side cell present in an outer peripheral region of the cross section are larger than cross-sectional areas of the inlet-side cells and the outlet-side cell in a central region of the cross section.

A honeycomb filter includes a plurality of honeycomb fired bodies and adhesive layers. Each of the plurality of honeycomb fired bodies includes a plurality of cells, porous cell walls, and an outer wall. The plurality of cells includes exhaust gas introduction cells and exhaust gas emission cells. The exhaust gas introduction cells and the exhaust gas emission cells each have a uniform cross-sectional shape throughout from the exhaust gas inlet side to the exhaust gas outlet side excluding a plugged portion in a cross section perpendicular to a longitudinal direction of the plurality of cells. Each of the exhaust gas emission cells is adjacently surrounded fully by the exhaust gas introduction cells across the porous cell walls. The plurality of cells includes outer cells which are adjacent to the outer wall and which include the exhaust gas introduction cells.

An exhaust gas purification filter has a honeycomb structure body and upstream side plug members. Cell holes are composed of inlet cell holes and outlet cell holes. In a central area and an outer peripheral area, a gas flow channel cross sectional area Sc1 of the outlet cell holes is larger than a gas flow channel cross sectional area So1 of the inlet cell holes, where Sc1<So1. A first ratio Rc is smaller than a second ratio Ro. The first ratio Rc is a ratio of Sc1 and Sc2. The second ratio Ro is a ratio of So1 to So2. In a first direction X and a second direction Y, the inlet cell holes and the outlet cell holes are alternately arranged, and the cell walls in the central area are larger in thickness than the cell walls in the outer peripheral area.

A honeycomb filter includes a plurality of honeycomb fired bodies. Each of the plurality of honeycomb fired bodies includes an outer wall, a plurality of cells, and porous cell walls. The plurality of cells include exhaust gas introduction cells each having an open end at an exhaust gas inlet side and a plugged end at an exhaust gas outlet side and exhaust gas emission cells each having an open end at the exhaust gas outlet side and a plugged end at the exhaust gas inlet side. Sub-cells adjacent to the outer wall include exhaust gas introduction sub-cells among the exhaust gas introduction cells and exhaust gas emission sub-cells among the exhaust gas emission cells. A total volume of the exhaust gas emission sub-cells adjacent to the outer wall is greater than a total volume of the exhaust gas introduction sub-cells adjacent to the outer wall.

A honeycomb filter includes a plurality of cells and porous cell walls. The plurality of cells defines exhaust gas passages. The plurality of cells includes exhaust gas introduction cells and exhaust gas emission cells. Each of the exhaust gas emission cells is adjacently surrounded fully by the exhaust gas introduction cells across the porous cell walls. The exhaust gas introduction cells include first exhaust gas introduction cells and second exhaust gas introduction cells. A cross-sectional area of each of the exhaust gas emission cells in a cross section perpendicular to a longitudinal direction of the plurality of cells is equal to or larger than a cross-sectional area of each of the second exhaust gas introduction cells in the cross section. The exhaust gas introduction cells and the exhaust gas emission cells have one of a first structure and a second structure in the cross section.