| 摘要 |
<p>The invention relates to a method for controlling the amount of urea (14) injected in a nitrogen oxide processing system with selective catalytic reduction, or SCR, to be mounted in the exhaust line (12) of a vehicle engine, said processing comprising chemically reducing in a catalyst (19), or SCR catalyst, the nitrogen oxides by the addition of the ammonia contained in the urea (14), wherein said method comprises the following steps: injecting (18) a predetermined amount of urea into the system; measuring (19) after the injection the amounts of nitrogen oxides and ammonia at the outlet of the SCR catalyst (10); injecting a new amount corresponding to the amount previously injected multiplied by an initial injection ratio; measuring the amounts of nitrogen oxides and ammonia at the outlet of the SCR catalyst (10) and comparing them to the previously measured values; and calculating a new injection ratio according to the evolution of the measured amounts, the last three steps being repeated until an optimal urea amount is obtained.</p> |
