EXHAUST PURIFICATION DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

In an internal combustion engine, a SOx trap catalyst (12), a NOx occlusion catalyst (14), and a fuel addition valve (15) are arranged in an exhaust path of the engine. To make the air-fuel ratio of exhaust gas that flows into the NOx occlusion catalyst (14) a theoretical air-fuel ratio or rich in order to cause NOx to be released from the NOx occlusion catalyst (14), additional fuel is supplied into a combustion chamber (2) and fuel is added from the fuel addition valve (15). In this process, the amount of the additional fuel supplied into the combustion chamber (2) is controlled so that the air-fuel ratio of the exhaust gas discharged from the combustion chamber (2) has a smallest value within the range where SOx is not released from the SOx trap catalyst (12).