A honeycomb filter includes a plurality of cells and porous cell walls. Exhaust gas is to flow through the plurality of cells. The plurality of cells include exhaust gas introduction cells and exhaust gas emission cells. The honeycomb filter has a round cross sectional shape. Each of the exhaust gas emission cells is adjacently surrounded fully by the exhaust gas introduction cells. In the cross section, the exhaust gas introduction cells and the exhaust gas emission cells each have a polygonal shape. In the cross section, 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.

An exhaust gas purifying device includes a honeycomb catalyst body, a plugged honeycomb structure and a can member to receive therein the honeycomb catalyst body and the plugged honeycomb structure, and the plugged honeycomb structure disposed at a position on a downstream side of the honeycomb catalyst body is designed so that a pressure loss in an end face central region of at least one of a second inflow side end face and a second outflow side end face of a second honeycomb substrate is larger than a pressure loss of an end face circumferential region positioned around the end face central region.

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.

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 segments. The honeycomb segment is configured so that the cells having at least two kinds of different shapes are disposed in a cross section orthogonal to an extension direction of the cells, the honeycomb segment has a center region configured by repeating units to maintain a repeated pattern including cell arrangement in which inflow cells surround an inflow cell, and a circumferential region located at the circumference of the center region, the circumferential region has open frontal area that is larger than open frontal area of the center region at the inflow end face of the honeycomb segment, the segment circumferential wall and the bonding layer have a special range of a thickness.

A plugged honeycomb structure includes: a plurality of honeycomb segments, a bonding layer, and a plugging portions to plug open ends of cells of each of the honeycomb segments. The honeycomb segment is configured so that the cells having at least two kinds of different shapes are disposed in a cross section orthogonal to an extension direction of the cells, the honeycomb segment has a center region and an circumferential region located in the circumference of the center region, the center region has a cell arrangement pattern such that inflow cells surround one outflow cell, in the inflow end face of the honeycomb segment, the circumferential region has an open frontal area that is smaller than an open frontal area of the center region, the segment circumferential wall of the honeycomb segment and the bonding layer have a special thickness.

There is provided a honeycomb structure where a crack at honeycomb segments, which constitute a honeycomb bonded assembly, is reduced. A honeycomb structure has a pillar-shaped honeycomb bonded assembly that has a plurality of pillar-shaped honeycomb segments having a porous partition wall defining a plurality of cells extending from an inflow end face as one end face to an outflow end face as another end face and becoming channels for a fluid, and a bonding layer bonding side surfaces of the plurality of honeycomb segments, and in the honeycomb bonded assembly, at 25 to 800 C., a thermal expansion coefficient of the bonding layer is larger than a thermal expansion coefficient of the honeycomb segment.

There is disclosed a plugged honeycomb structure. A plugged honeycomb structure includes a honeycomb structure body of a segment structure and plugging portions disposed in open ends of cells formed in the honeycomb structure body, the honeycomb structure body has outer segments and inner segments disposed on an inner side than the outer segments in a cross section of the honeycomb structure body, and a material constituting the outer segments has a smaller heat capacity per unit volume than a material constituting the inner segments.

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.

A monolithic honeycomb element includes a collection of adjacent ducts of mutually parallel axes separated by walls made of a porous material, the element having, in transverse cross section, a polygonal, notably quadratic cross section delimited by exterior wall elements, wherein at least one corner of the polygon, has, along the bisector of the angle at the corner, an additional thickness, such that the total thickness of the external wall, likewise measured along the bisector of the angle at the corner, is greater than the mean thickness of the exterior walls by a factor of at least 1.43, the additional thickness being obtained at least in part by an additional quantity of porous material on the external face of the corner.

A filter including a plurality of pillar-shaped honeycomb structure segments made of porous ceramics, side faces of the segments being bonded together via a bonding material, wherein each of the pillar-shaped honeycomb structure segments includes an outer peripheral side wall, and partition walls partitioning a plurality of cells extending from a first end face to a second end face, and in each of the pillar-shaped honeycomb structure segments, an average porosity of the outer peripheral side wall is lower than that of the partition walls.