| 摘要 |
PROBLEM TO BE SOLVED: To suppress variation in combustion caused by fuel addition while ensuring accuracy of fuel addition when providing an exhaust gas recirculation device for recirculating exhaust gas from downstream of a fuel adding valve arranged in an exhaust emission passage. SOLUTION: A diesel particulate filter and a NOx occlusion reducing catalyst are arranged on the exhaust emission passage, and the fuel adding valve is arranged upstream of an exhaust emission control device. The fuel adding valve adds fuel into the exhaust emission passage for regenerating a catalyst. The exhaust emission control system is provided with a high-pressure loop exhaust gas recirculation device for recirculating the exhaust gas from upstream of the exhaust emission control device to an intake side and a low-pressure loop exhaust gas recirculation device for recirculating the exhaust gas from downstream of the exhaust emission control device to the intake side. When fuel is added for regenerating the catalyst, an addition control means determines for every control intervals, the unit amount added which is the amount of fuel added in one fuel addition. The addition control means adds the minimum amount of fuel injected when the unit amount added is smaller than the minimum amount of injected by the fuel adding means, and also subtracts the excess amount of fuel when the minimum amount of fuel injected is added, from the amount of fuel added in the subsequent fuel addition. COPYRIGHT: (C)2008,JPO&INPIT
|
