EXHAUST SYSTEM OF INTERNAL COMBUSTION ENGINE

PROBLEM TO BE SOLVED: To enhance the purifying performance of exhaust gas by preventing an excessive temperature rise of a catalyst, and keeping the temperature of the catalyst at an adequate value in an exhaust system of an internal combustion engine. SOLUTION: In the exhaust system of the internal combustion engine, a turbocharger having a turbine operated by exhaust gas is provided on an exhaust pipe of the internal combustion engine, a catalyst is provided on the exhaust pipe at the downstream side of the turbocharger, and a main exhaust port from which the exhaust gas operating the turbine flows out and a sub-exhaust port from which the exhaust gas not passing through the turbine flows out when a waste gate valve is opened are provided at the turbocharger. The exhaust pipe at the downstream side of the turbocharger is divided into a main exhaust pipe to be connected to the main exhaust port, and a sub-exhaust pipe connected to the sub exhaust port. The catalyst is arranged in the main exhaust pipe, and the sub-exhaust pipe is merged with the main exhaust pipe at the downstream side of the catalyst. The sub-exhaust pipe is formed in a shape surrounding an outer peripheral part in the radial direction of the catalyst. COPYRIGHT: (C)2011,JPO&INPIT