Patent ID: 6318075
Filing Date: 2001-11-20
Classification: F01N,F02D,Y02A,Y02T

Abstract:
A method for periodically desulphating at least one of a nitrogen oxide storage vessel and a sulphur oxide storage vessel of an exhaust emission control system of a multi-cylinder internal combustion engine, comprising the steps of:setting a first rich fuel/air ratio for a first subset of the engine cylinders;setting a second fuel/air ratio for a second, remaining subset of the engine cylinders, the second fuel/air ratio being leaner than the first fuel air/ratio;feeding an engine exhaust emission including a reducing agent and oxygen to the at least one of the nitrogen oxide storage vessel and the sulphur oxide storage vessel during a desulphation period;during an initial storage vessel heating-up phase, setting a difference between the first fuel/air ratio and the second fuel/air ratio to a first level; andafter a predefined desulphation temperature is reached, setting the difference between the first fuel/air ratio and the second fuel/air ratio to a second level, the second level being lower than the first level.