| 摘要 |
In an internal combustion engine, hydrocarbons are intermittently injected into an engine exhaust passage from a hydrocarbon feed valve (15) to remove the NO X contained in exhaust gas. A suitable injection interval of hydrocarbons corresponding to an operating state of the engine is calculated with a predetermined fixed calculation period. When the elapsed time from when the previous injection was performed reaches or exceeds the latest calculated optimal injection interval, the injection of hydrocarbons from the reducing agent feed valve (15) is executed. |
