Patent ID: 6026640
Filing Date: 2000-02-22
Classification: B01D,F01N,F02B,F02D,Y02T

Abstract:
A method of controlling an exhaust gas system of an internal combustion engine which operates mainly under a lean condition, which system comprises a nitrogen oxide reducing catalyst capable of adsorbing nitrogen oxide under a lean atmosphere and a nitrogen oxide sensor disposed downstream of the nitrogen oxide reducing catalyst; said method comprising the steps of:(a) switching temporarily the operation condition of said internal combustion engine into a stoichiometric condition or a rich condition so that the nitrogen oxide adsorbed to said nitrogen oxide reducing catalyst is detached or decomposed when an output of the nitrogen oxide sensor reaches a predetermined level,(b) returning the operational condition back to a lean condition when an electromotive force, or a pumping current of a first pumping cell, of the nitrogen oxide sensor reaches a predetermined level.