Patent ID: 8443592

Claim:
An exhaust purification system of an internal combustion engine which is provided with an NO x storage reduction catalyst which is arranged in an engine exhaust passage, which stores NO x which is contained in exhaust gas when an air-fuel ratio of inflowing exhaust gas is lean, and which releases stored NO x when the air-fuel ratio of the inflowing exhaust gas becomes a stoichiometric air-fuel ratio or rich and an SO x trap material which is arranged in the engine exhaust passage upstream of the NO x storage reduction catalyst and which removes SO x which is contained in the exhaust gas, wherein, a main flow path which feeds fuel to combustion chambers of the engine body has connected to it a secondary flow path which bypasses the main flow path, while the secondary flow path has arranged in it a removal device which removes the sulfur constituent which is contained in the fuel and has arranged in it a opening and closing device which opens and closes the secondary flow path, and when an SO x removal rate of the SO x trap material becomes a predetermined removal rate judgment value or less or when a concentration of the SO x which flows into the SO x trap material becomes a predetermined concentration judgment value or more, at least part of the fuel which flows through the main flow path is made to flow into the secondary flow path and run through the removal device, and the case when an SO x removal rate of the SO x trap material becomes a predetermined removal rate judgment value or less includes at least one case of a case when a temperature of the SO x trap material becomes a low temperature side predetermined low temperature judgment value or less, a case when a temperature of the SO x trap material becomes a high temperature side predetermined high temperature judgment value or more, a case when an air-fuel ratio of the exhaust gas which flows into the SO x trap material becomes a predetermined air-fuel ratio judgment value or less, a case when a spatial velocity of the exhaust gas which flows into the SO x trap material becomes a predetermined velocity judgment value or more, and a case when an SO x stored amount of the SO x trap material becomes a predetermined stored amount judgment value or more.