EXHAUST EMISSION CONTROL DEVICE OF INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To provide an exhaust emission control device of an internal combustion engine, capable of efficiently purifying NOx in exhaust gas, eliminating sulfur poisoning of a NOx storage catalyst without affecting respective parts of the internal combustion engine, and being simplified. SOLUTION: The internal combustion engine having a NOx storage catalyst on an exhaust passage is provided with an excess air ratio control means. When engine output is insufficient, the excess air ratio is set to a theoretical air-fuel ratio or the vicinity of it at which NOx, CO and HC in exhaust gas can be simultaneously purified, by the excess air ratio control means and therefore, NOx, CO and HC in exhaust gas are simultaneously purified. A detecting means is provided for detecting that the sulfur poisoning amount of the NOx storage catalyst reaches a specified amount.