Patent ID: 8701392

Claim:
An exhaust purification system of an internal combustion engine comprising: an exhaust turbocharger having a compressor and an exhaust turbine, an exhaust purification catalyst arranged in an engine exhaust passage downstream of the exhaust turbine, a hydrocarbon feed valve arranged in the engine exhaust passage upstream of the exhaust purification catalyst, precious metal catalysts carried on exhaust gas flow surfaces of the exhaust purification catalyst; basic exhaust gas flow surface parts formed around the precious metal catalysts, wherein the exhaust purification catalyst has a property of reducing NOx contained in an exhaust gas if making a concentration of hydrocarbons which flow into the exhaust purification catalyst vibrate by within a predetermined range of amplitude and by within a predetermined range of period and has a property of being increased in storage amount of NO x which is contained in the exhaust gas if making a vibration period of the hydrocarbon concentration longer than the predetermined range, an electronic control unit configured to perform a first NOx purification logic which makes the concentration of hydrocarbons which flow into the exhaust purification catalyst vibrate by within the predetermined ranges of amplitude and period so as to remove the NOx and a second NOx purification logic which makes the vibration period of the hydrocarbon concentration longer than the predetermined range so as to store the NOx in the exhaust purification catalyst and makes an air-fuel ratio of the exhaust gas rich so as to release the stored NOx can be selectively used, wherein a high pressure exhaust gas recirculation system which recirculates a relatively high pressure exhaust gas in the engine exhaust passage upstream of the exhaust turbine to an inside of the intake passage downstream of the compressor and a low pressure exhaust gas recirculation system which recirculates a relatively low pressure exhaust gas in the engine exhaust passage downstream of the exhaust purification catalyst to an inside of the intake passage upstream of the compressor are provided, and wherein if an acceleration operation is performed with a degree of acceleration of a predetermined degree or more when an NOx purification action by the second NOx purification logic is being performed while performing an exhaust gas recirculation action by the low pressure exhaust gas recirculation system, the NOx purification action is switched to the NOx purification action by the first NOx purification logic and the exhaust gas recirculation action is temporarily switched to the exhaust gas recirculation action by the high pressure exhaust gas recirculation system.