A honeycomb structure has a pillar-shaped honeycomb structure body having porous partition walls which defines cells which forms a passage of liquid extended from an inflow end face toward an outflow end face, a circumferential wall arranged to surround a circumference of the partition walls. The honeycomb structure body has an outermost circumference cell structure including a complete cell arranged at the outermost circumference of the honeycomb structure body, a center cell structure formed by the cells arranged at a center part at an inner side to the outermost circumference cell structure, and a boundary wall arranged at a boundary part between the outermost circumference cell structure and the center cell structure. The outermost circumference cell structure and the center cell structure are formed as different structures to each other, and a thickness of the boundary wall is set to be thicker than a thickness of the circumferential wall.

A particulate filter (1) is provided having a first wall flow region (2) and a second flow through region (3). The filter is provided with a catalytic washcoat, whereby the filter can be used to remove both particulate matter and harmful gaseous emissions from an exhaust gas stream.

A honeycomb structure includes a central area and a reinforced outer peripheral area. A reference boundary cell with an inner wall orthogonal to an imaginary straight line, adjacent to the honeycomb center, and thinner than an outer wall adjacent to the honeycomb periphery has a reference wall different in wall thickness from the other three cell walls among the remaining four cell walls excluding the inner wall and the outer wall. The honeycomb structure includes a reference Y-shaped unit having the reference wall, the outer wall, and a cell wall. The honeycomb structure includes a plurality of Y-shaped units extending in the same directions as the reference Y-shaped unit. For every Y-shaped unit in the central area and the reinforced outer peripheral area of the honeycomb structure, the cell walls of each Y-shaped unit has an equal wall thickness.

An object of the present invention is to provide a honeycomb filter having low pressure loss and high collection efficiency. The honeycomb filter of the present invention comprises a ceramic honeycomb substrate in which a multitude of cells through which a fluid flows are disposed in parallel in a longitudinal direction and are separated by cell walls, each cell being sealed at an end section at either the fluid inlet side or the fluid outlet side, and a filter layer which, among the surfaces of the cell walls, is formed on the surface of the cell walls of those cells in which the end section at the fluid inlet side is open and the end section at the fluid outlet side is sealed by a sealing material, wherein the filter layer comprises spherical ceramic particles, and the average particle size of the spherical ceramic particles increases gradually from the fluid inlet side toward the fluid outlet side.

The honeycomb structure includes a pillar-shaped honeycomb structure body having porous partition walls, as to the honeycomb structure body, in a plane perpendicular to a cell extending direction, a cell structure of a central cell structure differs from a cell structure of a circumferential cell structure, and in the plane, a geometric center of gravity of the honeycomb structure body exists at a position which is away from a geometric center of gravity of the central cell structure, and a distance between the respective centers of gravity is larger than a length of a half of a cell pitch of an outermost circumferential cell structure including complete cells formed at an outermost circumference of the honeycomb structure body.

A heating device comprises a heating element having a central area and a peripheral edge. The heating element has a series of slots delimiting a series of longitudinal branches connected to one another by elbows. The central area is made of a first electrically conductive material that is permeable to exhaust gases and has a first relative density. The elbows are located in the peripheral edge and are made of a second electrically conductive material and that has a second relative density greater than the first relative density.

An exhaust emission control filter is provided that can reduce the pressure loss and has a high exhaust conversion performance and particulate matter capturing performance. An exhaust emission control filter includes: a filter base material having a wall flow structure; and an exhaust conversion catalyst carried on partitions of the filter base material. The median gas pore diameter (D50) of the filter base material after the exhaust conversion catalyst is carried on the filter base material is 17 μm or more. The half width of the gas pore distribution of the filter base material ranges from 7 to 15 μm. The exhaust conversion catalyst is ununiformly carried in a high-density layer having a relatively high density of the exhaust conversion catalyst and a low-density layer having a relatively low density of the exhaust conversion catalyst. The maximum gas pore diameter of the high-density layer is 11.7 μm or less.

To provide an exhaust gas purification filter having a high capability of collecting particulate matter. The exhaust gas purification filter includes a filter base material having a wall flow structure and an exhaust gas purification catalyst. A wash coating amount of the exhaust gas purification catalyst ranges from 60 to 110 g/L or less. When the exhaust gas purification filter is divided into an upstream part, a middle part, and a downstream part, and average values of catalyst area ratios of the exhaust gas purification catalyst supported by surfaces of the partition walls are acquired at predetermined locations in cells on an inflow side and cells on an outflow side, a minimum value, among the average values, is 28% or greater. A maximum value, among sizes of pores in the partition walls after the exhaust gas purification catalyst is supported, is 14.6 μm or less.

The invention relates to a wall-flow filter as a particle filter with catalytically active coatings in the channels which are closed in a gastight manner at the opposing closed ends of the channels A at the first end, wherein the inlet region of the filter is additionally supplied with a dry powder-gas aerosol which contains metal compounds with a high melting point (such as the metal oxides Al2O3, SiO2, FeO2, TiO2, ZnO2, etc. for example) and which is to simultaneously improve the catalytic activity and the degree of filtration efficiency with respect to the exhaust gas back-pressure.

An exhaust gas purifying catalyst includes: a wall-flow structure substrate including an inlet cell, an outlet cell, and a porous partition; a first catalyst layer formed inside the partition such that a thickness of the first catalyst layer is between 40% and 60%, inclusive, of an overall thickness T.sub.w of the partition; and a second catalyst layer formed inside the partition such that the second catalyst layer extends across an entire region of the partition in a thickness direction thereof.