System for triggering the purging of NOx trap depollution means

A system for triggering purging of depollution means comprising a NOx trap and integrated in a motor vehicle diesel exhaust line, the system comprising:

• means for establishing a first coefficient representing the degree to which the NOx trap is full of NOx;
• means for establishing a second coefficient representing the capacity of the NOx trap to reduce the stored NOx as a function of the NOx trap's temperature;
• means for establishing a third coefficient representative of the capacity of the engine to purge the NOx trap as a function of the engine operating point;
• means for establishing a fourth coefficient representative of the capacity of the engine to purge the NOx trap as a function of the corresponding excess fuel consumption and as a function of current fuel consumption;
• means for combining said coefficients to obtain a fifth and final coefficient;
• and
• comparator means for comparing the fifth and final coefficient with a threshold so that in the event of the threshold being crossed, a request is issued to trigger purging of the NOx trap.