EXHAUST PURIFICATION SYSTEM OF INTERNAL COMBUSTION ENGINE

摘要

An internal combustion engine wherein an exhaust purification catalyst and a hydrocarbon feed valve are arranged downstream in an exhaust passage. A first NOX purification method, which removes NOX by making a concentration of hydrocarbons that flows into the exhaust purification catalyst vibrate within predetermined amplitude and period ranges and a second NOX purification method which utilizes an adsorption action of NOX to the exhaust purification catalyst are used. A high pressure exhaust gas recirculation system (HPL) causing recirculation of high pressure exhaust gas and a low pressure exhaust gas recirculation system (LPL) causing recirculation of low pressure exhaust gas are provided. When performing an LPL recirculation while performing an NOX purification action by the second NOX purification method, if an acceleration operation occurs, the NOX purification action is switched to the NOX purification action by the first NOX purification method and recirculation is temporarily switched to the HPL recirculation.