Exhaust gas purification control apparatus of engine

Abstract

An exhaust gas purification control apparatus is used for an engine provided with a NOx catalyst 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 the NOx catalyst, and characterized in that thed exhaust gas purification control apparatus comprises a sulphur component calculating means for calculating or estimating a quantity of sulphur components in the exhaust gas and an operation mode changing means for changing an air fuel ratio of the engine on the basis of the detected value of the sulphur components, and the calculated or estimated value of sulphur components is a prescribed value or more, the 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.

Dependencies are inferred from the claim text.