Catalytic converter

Abstract

A catalytic converter ( 10 ) includes i) an outer tube ( 1 ) that includes a cylindrical portion ( 1 a ), an upstream-side cone portion ( 1 b ), and a downstream-side cone portion ( 1 c ), and ii) a substrate ( 2 ) having a cell structure that is arranged in the cylindrical portion ( 1 a ) of the outer tube ( 1 ). The substrate ( 2 ) has a center region ( 2 a ) where a cell density is relatively high and a peripheral region ( 2 b ) where the cell density is relatively low, in a cross-section that is orthogonal to a length direction of the substrate ( 2 ). A projection portion when a connecting portion ( 5 ) of the exhaust duct ( 4 ) and the downstream-side cone portion ( 1 c ) is projected onto the substrate ( 2 ) is within the center region ( 2 a ).

1 . A catalytic converter comprising:
 an outer tube that is connected to an exhaust duct through which exhaust gas flows, the exhaust duct including an upstream-side exhaust duct and a downstream-side exhaust duct with respect to a direction of an exhaust-gas flow, the outer tube including a cylindrical portion, an upstream-side cone portion connected to the upstream-side exhaust duct, and a downstream-side cone portion connected to the downstream-side exhaust duct, the upstream-side cone portion extending from an upstream-side end of the cylindrical portion in such a manner that a cross-section diameter of the upstream-side cone portion decreases toward the upstream-side exhaust duct, the downstream-side cone portion extending from a downstream-side end of the cylindrical portion in such a manner that a cross-section diameter of the downstream-side cone portion decreases toward the downstream-side exhaust duct; and   a substrate having a cell structure and being arranged inside of the cylindrical portion of the outer tube, wherein   a catalyst layer in which a precious metal catalyst is carried on a carrier is formed on a cell wall surface of the substrate,   the substrate has a center region and a peripheral region in a cross-section orthogonal to a length direction of the substrate,   a cell density of the center region is higher than a cell density of the peripheral region,   a projection portion when a projection of a cross-section of a connecting portion of the exhaust duct and the downstream-side cone portion on the substrate falls within the center region,   a downstream-side surface of the substrate is directly opposite to an opening of the downstream-side exhaust duct, and   a diameter of the center region is larger than a diameter of the connecting portion of the exhaust duct and the downstream-side cone portion.