Exhaust gas purification system for internal combustion engine

An exhaust gas purification system for an internal combustion engine, having an exhaust gas purification device having the property of occluding SOx in an exhaust gas emitted from said internal combustion engine and collecting particulate matter contained in the exhaust gas, said system comprising:

• a collection amount estimation device that estimates an amount of particulate matter collected in said exhaust gas purification device;
• a collection ability regeneration control device that controls the temperature of said exhaust gas purification device to be a predetermined temperature when the amount of collected particulate matter estimated by said collection amount estimation device exceeds a predetermined amount of collection;
• an SOx amount estimation device that estimates an amount of SOx occluded in said exhaust gas purification device;
• a rich spike control device that alternately controls the air-fuel ratio of the exhaust gas flowing into said exhaust gas purification device to be a rich-side air-fuel ratio or to be a lean-side air-fuel ratio when the amount of SOx occlusion estimated by said SOx amount estimation device exceeds a predetermined amount of SOx occlusion;
• and
• a rich spike priority control device that executes the control of said rich spike control device in preference to the control of said collection ability regeneration control device when the amount of collected particulate matter estimated by said collection amount estimation device exceeds the predetermined amount of collection, and when the amount of SOx occlusion estimated by said SOx amount estimation device exceeds the predetermined amount of SOx occlusion.