| 摘要 |
The invention has an object to calculate a NOx amount in exhaust gas accurately and stably with an influence of a fuel injection timing also taken into consideration. An engine 10 includes a fuel injection valve 14, a NOx reduction catalyst 30, an ECU 60 and the like. The ECU 60 calculates the NOx amount in the exhaust gas based on at least two parameters constituted of exponentiation of an injection timing of an effective injection that is a fuel injection that contributes to combustion in a cylinder, and exponentiation of an intake oxygen concentration. The effective injection is a general term for a main injection, an after injection and a pilot injection. Thereby, the injection timing of the effective injection which is highly correlated with a generation amount of NOx can be reflected in a calculation value of a NOx concentration. Accordingly, the NOx amount can be accurately and stably calculated without being influenced by a machine difference of internal combustion engines, an operation situation and the like. |
