Patent ID: 8375706

Claim:
An exhaust gas purification system of an internal combustion engine, comprising: a NOx storage reduction catalyst that is arranged in an exhaust passage of the internal combustion engine; and an electronic control unit including logic that, when executed, performs the steps of: executing SOx poisoning recovery control to cause SOx occluded in said NOx storage reduction catalyst to be released therefrom by supplying a reducing agent to said NOx storage reduction catalyst from an upstream side thereof thereby to raise the temperature of said NOx storage reduction catalyst and at the same time to lower the air fuel ratio of an exhaust gas flowing into said NOx storage reduction catalyst; and estimating, with respect to the time of the start of the SOx poisoning recovery control, the degree of decrease of a SOx release speed resulting from a decrease in an amount of SOx occlusion of said NOx storage reduction catalyst in the course of said SOx poisoning recovery control, wherein said electronic control unit causes the temperature of said NOx storage reduction catalyst to rise up to a higher side target temperature in accordance with the increasing degree of decrease of said SOx release speed estimated by said electronic control unit.