Patent ID: 8099948

Claim:
An exhaust system of an internal combustion engine having a plurality of cylinders, comprising: a first cylinder group and a second cylinder group which constitute all of the cylinders of the engine; a first exhaust passage and a second exhaust passage that are connected to respective exhaust manifolds of the first cylinder group and the second cylinder group, the first exhaust passage and the second exhaust passage having respective junction points through which the first and second exhaust passages communicate with each other; a turbine of a turbocharger disposed downstream of the junction point of the first exhaust passage; a first catalytic converter disposed downstream of the turbine in the first exhaust passage; a first control valve disposed downstream of the junction point of the first exhaust passage; a second catalytic converter disposed downstream of the junction point of the second exhaust passage; a second control valve disposed downstream of the junction point of the second exhaust passage; and a controller that controls opening amounts of the control valves disposed in the first exhaust passage and the second exhaust passage so that exhaust gas of all of the cylinders mainly passes one of the first catalytic converter and the second catalytic converter during a fuel-supply cutoff period, wherein during the fuel-supply cutoff period, temperatures of the first catalytic converter and the second catalytic converter are measured or estimated, and if the temperature of the second catalytic converter is lower than the temperature of the first catalytic converter, the controller controls the opening amounts of the control valves disposed in the first exhaust passage and the second exhaust passage so that the exhaust gas of all of the cylinders mainly passes the second catalytic converter.