Patent ID: 7988922

Claim:
A honeycomb filter comprising a pillar-shaped honeycomb fired body having a large number of cells longitudinally disposed in parallel with one another with a cell wall therebetween, with either one end of each of said cells sealed, said honeycomb filter allowing gases having flowed in through either one end face side to flow out from the other end face side, said honeycomb filter including: an outlet-side catalyst supporting area with a catalyst supporting layer formed from an end face on a gas outlet side of said honeycomb filter toward an end face on a gas inlet side of said honeycomb filter, said catalyst supporting layer having a catalyst supported thereon; an inlet-side catalyst supporting area with a catalyst supporting layer formed from an end face on the gas inlet side of said honeycomb filter toward an end face on the gas outlet side of said honeycomb filter, said catalyst supporting layer having a catalyst supported thereon; and a catalyst unsupporting area with substantially no catalyst supporting layer formed between said outlet-side catalyst supporting area and said inlet-side catalyst supporting area, said catalyst unsupporting area having substantially no catalyst supported thereon, wherein a thermal conductivity of said catalyst unsupporting area is larger than thermal conductivities of said outlet-side catalyst supporting area and said inlet-side catalyst supporting area, and wherein Y (%), Z (%), and X (%) satisfy the following inequalities (1) to (4): about 1≦Y≦about 19 (1) (880−70 Y )/9 ≦Z ≦(825−15 Y )/9(about 1 ≦Y ≦about 10) (2) (330−15 Y )/9 ≦Z ≦(1375−70 Y )/9(about 10 ≦Y ≦about 19) (3) X= 100 −Y−Z (4), Y (%) indicating a ratio of a length of said outlet-side catalyst supporting area in a longitudinal direction of said honeycomb filter to an entire length of said honeycomb filter in the longitudinal direction, Z (%) indicating a ratio of a length of said inlet-side catalyst supporting area in the longitudinal direction of said honeycomb filter to the entire length of said honeycomb filter in the longitudinal direction, X (%) indicating a ratio of a length of said catalyst unsupporting area in the longitudinal direction of said honeycomb filter to the entire length of said honeycomb filter in the longitudinal direction.