Patent ID: 9719388
Date: 2017-08-01
CPC Classifications: F01N,Y02T

Claim:
1. An exhaust cooling system for an internal combustion engine, the exhaust cooling system comprising: an exhaust purification catalyst arranged in an exhaust passage of the internal combustion engine; a cooling unit configured to cool the exhaust passage upstream of the exhaust purification catalyst; a heat transmission inhibition portion configured such that heat transfer between the exhaust passage downstream of a location cooled by the cooling unit and the cooling unit is inhibited; a curved section positioned in the exhaust passage from a location where the heat transmission inhibition portion is provided to the exhaust purification catalyst; and a heat radiation suppression portion provided in the curved section, the heat radiation suppression portion being configured to suppress heat radiation transmitted from exhaust gas flowing in the curved section to an atmosphere around the curved section through curved section passage walls forming the curved section, wherein the curved section includes an inner curved section with a curvature radius and an outer curved section with a curvature radius, that is larger than the curvature radius of the inner curved section, in a cross section including a central axis in a longitudinal direction of the exhaust passage; the heat radiation suppression portion is provided at the inner curved section and the outer curved section; the heat radiation suppression portion is configured such that a heat radiation suppression capacity of the heat radiation suppression portion in the inner curved section is higher than a heat radiation suppression capacity of the heat radiation suppression portion in the outer curved section, and a coat layer is applied on the inner curved section and the outer curved section such that the heat radiation suppression capacity of the inner curved section is higher than that of the outer curved section.