EXHAUST PURIFICATION SYSTEM OF INTERNAL COMBUSTION ENGINE

摘要

In an internal combustion engine, a hydrocarbon feed valve (15) and an exhaust purification catalyst (13) are arranged in an engine exhaust passage. When releasing the stored NOx from the exhaust purification catalyst (13), usually combustion gas of a rich air-fuel ratio is generated in the combustion chamber (2) to make the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst (13) rich. When releasing the stored NOx from the exhaust purification catalyst (13) in case where the temperature of the exhaust purification catalyst (13) is low, the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst (13) is made rich by injecting hydrocarbons from the hydrocarbon feed valve (15).