Patent ID: 6772587
Filing Date: 2004-08-10
Classification: F01N,F02D,Y02T

Abstract:
An exhaust gas purification control apparatus of an engine having a NOx catalyst for absorbing or adsorbing NOx when an air fuel ratio of exhaust gas from the engine is lean and reducing the absorbed or adsorbed NOx when the exhaust gas is at the stoichiometric air fuel ratio or richer in fuel, and an exhaust sensor arranged upstream or downstream of said NOx catalyst, comprisingsulphur component calculating means for calculating or estimating a quantity of sulphur components in the exhaust gas; and operation mode changing means for changing operation modes of the engine to prevent poisoning of said NOx catalyst with sulfur components by changing an air fuel ratio of the engine on the basis of the detected value of the sulphur components, wherein when the calculated or estimated value of the sulphur components is a prescribed value or more, said mode operation changing means decreases frequencies of lean mode operation of the engine, shortens continuation time of the lean mode operation or prohibits the lean mode operation.