EXHAUST PURIFICATION DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

In an internal combustion engine, a pre-catalyst (12) and a post-catalyst (14), which are NOx adsorption catalysts, are arranged in an engine exhaust path. When the catalysts (12, 14) are to be recovered from their SOx poisoning, the temperature of the catalysts (12, 14) is raised to an SOx discharge temperature, and the processing for recovery from the SOx poisoning with enriching the air-fuel ratio of the exhaust gas flowing into the catalysts (12, 14) is performed. The frequency of the processing for recovery from the SOx poisoning performed for the post-catalyst (14) is set higher than the frequency of the processing performed for the pre-catalyst (12).