Exhaust purification apparatus of compression ignition type internal combustion engine

An exhaust purification apparatus for an exhaust passage of a compression ignition type internal combustion engine, the exhaust purification apparatus comprising:

• an SOx trap catalyst that traps SOx contained in exhaust gas, NOx storing catalyst in the exhaust passage downstream of the SOx trap catalyst, the NOx storing catalyst storing NOx contained in the exhaust gas when an air-fuel ratio of inflowing exhaust gas is lean and releasing the stored NOx when the air-fuel ratio of the exhaust gas a stoichiometric air-fuel ratio or rich, wherein the SOx trap catalyst:
• traps the SOx contained in the exhaust gas when the air-fuel ratio of the exhaust gas flowing into the SOx trap catalyst is lean,
• allows the trapped SOx to gradually diffuse inside the SOx trap catalyst when the air-fuel ratio of the exhaust gas is lean and the SOx trap catalyst rises in temperature,
• releases the trapped SOx when the air-fuel ratio of the exhaust gas flowing into the SOx trap catalyst becomes rich and the temperature of the SOx trap catalyst is at least the SOx release temperature;
• air-fuel ratio controlling means for controlling the air-fuel ratio of the exhaust gas flowing into the SOx trap catalyst to be lean without making the air-fuel ratio rich during an engine operation;
• and
• deterioration judging means for judging if the SOx trap catalyst has deteriorated, wherein
• the temperature of the SOx trap catalyst is raised in a state where the air-fuel ratio of the exhaust gas is lean and the NOx amount released from the SOx trap catalyst is detected, and the deterioration judging means judges if the SOx trap catalyst has deteriorated based on the detected amount of NOx released from the SOx trap catalyst.