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

摘要

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 (8) which contains a pollutant-removing agent and which is arranged such that the temperature thereof is controlled by a heating device (9). The system further comprises a supply module (6) arranged so as to inject the pollutant-removing agent into the exhaust gases, the supply module (6) comprising a device for measuring the pressure (6a) or the temperature inside the storage chamber (8), as well as a device (6b) 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 (T1) 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 (T2) 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 (6a); and heating the storage chamber (8) if the pressure or temperature inside the latter is lower than the set pressure or set temperature.