Method for reducing the amount of nox in the exhaust gases of a motor vehicle

Abstract

The invention relates to a method for controlling a system for reducing the amount of NOx in the exhaust gases of a motor vehicle. The system comprises a storage chamber () which contains a pollutant-removing agent and which is arranged such that the temperature thereof is controlled by a heating device (). The system further comprises a supply module () arranged so as to inject the pollutant-removing agent into the exhaust gases, the supply module () comprising a device for measuring the pressure () or the temperature inside the storage chamber (), as well as a device () for proportioning the pollutant-removing agent. The control method involves, for example: defining a predetermined moving criterion, in particular on the basis of the engine torque during a first period; filtering the moving criterion with a filtering period (T) corresponding to the first period; comparing the filtered moving criterion with various thresholds in order to determine a type of moving; determining the elapsed time for each type of moving during a second period (T) in order to associate a trend representing moving conditions throughout said second period; calculating a set pressure or set temperature according to the type and the trend representing past moving conditions; comparing the set pressure or set temperature with the pressure or temperature measured by the pressure- or temperature-measuring device (); and heating the storage chamber () if the pressure or temperature inside the latter is lower than the set pressure or set temperature.