Method of calculating the NOx storage capacity of a Lean NOx Trap device

摘要

Disclosed is a method of evaluating the NOx storage capacity of a Lean NOx Trap device 281 in an exhaust system 270 of an internal combustion engine 110 of an automotive system 100. The method comprises: calculating a BaseCap variable at a fixed NOx_base constant as function of catalyst temperature and sulphur content, calculating a slope variable as function of catalyst temperature and sulphur content; subtracting said NOx_base constant by a filtered NOx_in value and then multiplying such result by the slope variable and adding the previous result to said BaseCap variable, thus providing a NOx storage capacity. The age of the LNT may also be taken into account in the method which assumes a linear relationship between the NOx storage capacity and the amount of NOx reaching the LNT. A control system using the method and the associated computer program are also disclosed