A catalyst for cleaning exhaust gases, having a honeycomb body which configures a plurality of flow ducts through which a gas from a gas inlet side may flow in the axial direction to a gas outlet side, having an inner casing which encloses the honeycomb body having an outer casing which encloses the inner casing, and having an insulation region which is disposed between the inner casing and the outer casing. The honeycomb body, the inner casing, the outer casing and the insulation region are formed from exactly two tiers formed from metal foils that are stacked on top of one another and wound along a winding direction transverse to the axial direction.

A particulate filter 23 is configured by being provided with, arranged side by side, a plurality of honeycomb-shaped segments 29, 30, 31 having a plurality of cells 32. The density of cells in the segments 30, 31 disposed in the outer circumference part is set to be lower than the density of cells in the segments 29 disposed in the center part. In addition, the segments 30, 31 disposed in the outer circumference part are configured so that the density of the cells 32 becomes lower as the area of the end face becomes smaller.

A honeycomb filter includes a pillar-shaped honeycomb structure having porous partition walls provided, surrounding a plurality of cells which serve as fluid through channels extending from an inflow end face to an outflow end face, and porous plugging portions provided either at the ends on the inflow end face or the outflow end face of the cells, wherein the plugging portions are composed of a porous material, the honeycomb structure has a central region and a circumferential region, and a ratio of an area of the circumferential region with respect to that of the central region ranges from 0.1 to 0.5, a plugging length L1 in the cell extending direction of a central plugging portion in the central region is larger than a plugging length L2 of a circumferential plugging portion in the circumferential region, L1 ranges from 7 to 9 mm, and L2 from 3 to 6 mm.

An electric heating type carrier including a conductive honeycomb structure portion and a pair of electrode layers, wherein in a cross-section orthogonal to the direction in which the cells extend, the honeycomb structure portion is classified into following three regions: a first resistance region having a contact portion with a first electrode layer, a second resistance region having a contact portion with a second electrode layer, and a third resistance region that does not come into contact with either the first electrode layer or the second electrode layer, and traverses the cross-section so as to be sandwiched between the first resistance region and the second resistance region, and has a higher electrical resistance per unit volume (1 cm.sup.3) than an electrical resistance per unit volume (1 cm.sup.3) of the first resistance region and the second resistance region.

The exhaust gas cleaning catalyst according is provided with a substrate and a catalyst coat layer formed on a surface of the substrate. The catalyst coat layer is formed as a laminate structure having an upper layer and a lower layer. The upper layer is a Pd-free layer that does not contain Pd, and the lower layer is a Pd-containing layer. In addition, when a region of the lower layer that corresponds to 20% of the length of the exhaust gas cleaning catalyst from the exhaust gas inlet side end towards the exhaust gas outlet side of the exhaust gas cleaning catalyst is divided into four equal regions to be each 5% of the length, the relationship A>B>C is satisfied, where A, B, and C represents the Pd content in the first, second, and third region respectively.

A honeycomb structure includes a honeycomb structure body having porous partition walls, wherein a value of a porosity of the partition wall in a partitioning wall portion between the two cells is defined as a porosity A, a value of a porosity of the partition wall in an intersecting portion that is a region connecting two or more wall portions is defined as a porosity B, a value of A/B obtained by dividing the porosity A by the porosity B is from 0.5 to 0.95, and the porosity A is from 10 to 40%.

A honeycomb filter, including: a honeycomb structure, wherein the honeycomb structure includes a platinum group element-containing catalyst layer, the platinum group element-containing catalyst layer is disposed only on a side of an inner surface of the partition walls surrounding the outflow cells, and the platinum group element-containing catalyst layer is disposed in a range of at least up to 35% with respect to an overall length of the cells starting from the outflow end face and is not disposed in a range of at least up to 30% with respect to the overall length of the cells starting from the inflow end face, in an extending direction of the cells of the honeycomb structure.

The invention relates to an annular catalytic converter, having a first, tubular flow path, having a diverting region (4) and having a second, annular flow path, wherein the tubular flow path is formed by an inner pipe (1), wherein the annular flow path is formed between the inner pipe (1) and an outer pipe (2) surrounding the inner pipe, and the diverting region (4) is of pot-shaped form for the purposes of diverting the exhaust-gas flow from the tubular flow path into the annular flow path, wherein the inner pipe (1) and/or the outer pipe (2) has a conical cross section (D1, D2, D1, D4) that widens or narrows along the flow direction of the exhaust gas.

A particulate filter 23 is configured by being provided with, arranged side by side, a plurality of honeycomb-shaped segments 29, 30, 31 having a plurality of cells 32. The density of cells in the segments 30, 31 disposed in the outer circumference part is set to be lower than the density of cells in the segments 29 disposed in the center part. In addition, the segments 30, 31 disposed in the outer circumference part are configured so that the density of the cells 32 becomes lower as the area of the end face becomes smaller.

The present invention provides a particulate filter for use in an emission treatment system of a gasoline engine, the filter having an inlet side and an outlet side, wherein at least the inlet side is loaded with a synthetic ash.