The plugged honeycomb structure includes a plurality of honeycomb segments, a bonding layer, and plugging portions which plug open ends of cells of each honeycomb segment, and in the honeycomb segment, at least two types of cells having different sectional shapes are formed to constitute predetermined repeated arrangement patterns, and a ratio of a value R2s obtained by dividing an average sectional area S2.sub.in of inflow cells by an average sectional area S2.sub.out of outflow cells in a partial rim circumferential wall cell region is in a range of 1.7 times or more and 2.0 times or less to a value R1s obtained by dividing an average sectional area S1.sub.in of the inflow cells by an average sectional area S1.sub.out of the outflow cells in a whole rim partition wall cell region.

The plugged honeycomb structure includes a plurality of honeycomb segments, a bonding layer, and plugging portions which plug open ends of cells of each honeycomb segment, and in the honeycomb segment, at least two types of cells having different sectional shapes are formed to constitute predetermined repeated arrangement patterns, and in rim circumferential wall cells including rims of the cells surrounded with partition walls and segment circumferential walls, an inflow open area of each corner rim circumferential wall cell disposed in each corner portion of the honeycomb segment is 1.1 times or more as large as an average inflow open area of non-corner rim circumferential wall cells arranged in portions other than the corner portions, or an outflow open area of the corner rim circumferential wall cell is 1.1 times or more as large as an average outflow open area of the non-corner rim circumferential wall cells.

A ceramic honeycomb structure comprising pluralities of honeycomb segments each having pluralities of longitudinally penetrating flow paths partitioned by porous cell walls and plugs formed in the end portions of the flow paths, and a bonding material layer boding the peripheral walls of the honeycomb segments, the bonding material layer comprising silicon carbide particles as aggregate and a bonding phase bonding the silicon carbide particles, the bonding phase comprising at least a cordierite phase and a spinel phase, the molar ratio M1 of the cordierite phase [=cordierite phase/(cordierite phase+spinel phase)] being 0.50 or more and less than 1.0, and the content of (cordierite phase+spinel phase) in the bonding phase being 50% or more by mass.

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 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, wherein when a thermal expansion coefficient at 300 to 600 C. of a material constituting a honeycomb substrate is indicated by A (10.sup.6/ C.), the four-point bending strength of the material constituting the honeycomb substrate is indicated by B (MPa), the thickness of a thinnest portion in a portion partitioning outlet plugging cells of a partition wall 1 is indicated by t (mm), the thickness of a portion partitioning an outlet plugging cell and an inlet plugging cell of the partition wall is indicated by WT (mm), and the distance between the center of the outlet plugging cell and the center of the inlet plugging cell adjacent to each other is indicated by CP (mm), a relation of the following equation (1) is satisfied.
0.714WT+0.160t/CP0.163A/B+0.105(1)

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.

A honeycomb structure has a plurality of pillar honeycomb segments with a porous partition wall that defines 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 that bonds side surfaces of the plurality of honeycomb segments one another, the bonding layer contains a plurality of plate-shaped particles, the plate-shaped particles are laminated in a thickness direction X of the bonding layer at a cross section of the bonding layer cut off to the thickness direction of the bonding layer, the number of particles meets Expression: number of particles >10, and the number of particles and the number of particles meet a relationship of Expression: (number of particles /number of particles )>3.

A honeycomb structure including a honeycomb structure body, first plugging portions, and second plugging portions. The honeycomb structure body has a porous partition wall. The first plugging portions are disposed at an outflow side end face of inlet cells and an inflow side end face of outlet cells. The inlet cells are the predetermined cells of the honeycomb structure body. The outlet cells are the residual cells of the honeycomb structure body. The second plugging portions are not fired. The first plugging portions form a checkered pattern at the inflow side end face and the outflow side end face. The number of the second plugging portions is within 3% of the number of cell open ends where the first plugging portions are not formed, on both end faces of the honeycomb structure body.

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. The honeycomb filter has a ratio of length of the honeycomb filter to a diameter of the round cross sectional shape of less than 1.0. A total volume of the exhaust gas introduction cells is larger than a total volume of the exhaust gas emission cells.