EXHAUST PURIFICATION SYSTEM OF INTERNAL COMBUSTION ENGINE

摘要

The exhaust purification system of an internal combustion engine is provided with an NOX selective reduction catalyst which is arranged in an engine exhaust passage and which has the function of absorbing NOX which is contained in exhaust gas when an air-fuel ratio of inflowing exhaust gas is lean, releasing the absorbed NOX when the air-fuel ratio of the inflowing exhaust gas becomes a stoichiometric air-fuel ratio or rich, and selectively reducing the NOX and with a fuel addition valve which feeds fuel to the NOX selective reduction catalyst. In the case of the region near the stoichiometric air-fuel ratio in the region where the air-fuel ratio of the exhaust gas flowing into the NOX selective reduction catalyst is lean, the fuel addition valve is used to feed fuel to the NOX selective reduction catalyst to selectively reduce the NOX.