Patent ID: 7669410

Claim:
A method of sulfur purge control of an exhaust gas purification system, comprising: providing a NOx occlusion reduction type catalyst for occluding NOx when an air fuel ratio in the exhaust gas is lean, and releasing and reducing the occluded NOx when the air fuel ratio in the exhaust gas is rich; providing an oxidation catalyst on an upstream side of the NOx occlusion reduction type catalyst: sensing a need for sulfur purge; executing the sulfur purge control for recovering deterioration of the NOx occlusion reduction type catalyst caused by sulfur poisoning thereof, including raising a temperature of the NOx occlusion reduction type catalyst until the temperature is equal to or greater than sulfur resolution temperature, judging whether a temperature difference between an inlet side and an outlet side of the NOx occlusion reduction type catalyst is within a given range, and when it is judged that the temperature difference is not within the given range, raising a temperature of the NOx occlusion reduction type catalyst until the temperature difference is within the given range.