| 摘要 |
PROBLEM TO BE SOLVED: To provide an internal combustion engine which can realize early activation by rapidly raising the temperature of a catalyst and can prevent previously the discharge of a harmful component such as unburned HC. SOLUTION: In this internal combustion engine 1 executing lean operation, valve timing variable means 4a, 4b are arranged which can change valve opening periods of exhaust valves 8a, 8b, and also an exhaust interference means 18 is arranged which is set to a shape that exhaust gas remains in its inside, and when requiring the activation of catalysts 20a, 20b, the valve opening periods of the exhaust valves 8a, 8b are extended by the valve timing variable means 4a, 4b. Thereby, overlap between air cylinders is increased, exhaust gas from the air cylinders is interfered over a longer period of time in the inside of the exhaust interference means 18, and unburned HC in exhaust gas can be burnt by reacting to excess O2 produced in lean operation.
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