| 摘要 |
PROBLEM TO BE SOLVED: To improve the exhaust emission control performance, by promoting the activation of a catalyst device, or reducing the SOx amount of the catalyst device effectively, in a simple structure. SOLUTION: To each cylinder, a pair of exhaust ports 30a and 30b, and a pair of exhaust valves 36a and 36b whose opening and closing timing can be controlled variable, are provided. At the aggregating part of an exhaust manifold 28 where the exhaust ports 30a and 30b are aggregated at the downstream side, a catalyst device 48 is provided. When the catalyst temperature does not reach to a specific active temperature during a lean operation, or when the SOx amount accumulated in the catalyst device 48 exceeds a specific amount, a half valve operation that one side exhaust valve 36a of each cylinder is stopped in a valve closing condition is carried out.
|
