Patent ID: 8534048

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, stores NO x which is contained in exhaust gas when an air-fuel ratio of inflowing exhaust gas is lean, and releases the stored NO x when the air-fuel ratio of the inflowing exhaust gas becomes a stoichiometric air-fuel ratio or rich, an oxidation catalyst which is arranged downstream of the NO x storage reduction catalyst in the engine exhaust passage, an exhaust gas tank which is connected to the engine exhaust passage between the NO x storage reduction catalyst and the oxidation catalyst, and a flow path changing device which closes the engine exhaust passage from the NO x storage reduction catalyst toward the oxidation catalyst and makes the exhaust gas flow into the tank, wherein when making the air-fuel ratio of the exhaust gas which flows into the NO x storage reduction catalyst the stoichiometric air-fuel ratio or rich, the system closes the engine exhaust passage toward the oxidation catalyst and changes the flow path so that the exhaust gas flows into the tank and at least part of the stoichiometric air-fuel ratio or rich air-fuel ratio exhaust gas which flows out from the NO x storage reduction catalyst is stored in the tank.