INTERNAL COMBUSTION ENGINE

摘要

In an engine exhaust passage, there are disposed a post-treatment unit, which is composed of SO_x trap catalyst (11), particulate filter (13) carrying a NO_x storage reduction catalyst and NO_x storage reduction catalyst (15), and fuel supply valve (17) for feeding of a fuel for post-treatment to the above post-treatment unit. When the level of deterioration of any of the catalysts exceeds a preset deterioration level, the method of feeding the fuel for post-treatment is reset so that the post-treatment fuel needed for exhaust gas purification is fed to the catalyst of the lowest deterioration level to thereby cause the catalyst of the lowest deterioration level to engage in the activity of exhaust gas purification.