| 摘要 |
The invention relates to a process for controlling the injection of urea in a selective catalytic reduction, known as CR, system for treating nitrogen oxides, intended to be installed in the exhaust line (6) of a motor vehicle (1) engine (2), wherein the treatment comprises chemically reducing, in a catalyst (3), known as SCR catalyst, the nitrogen oxides by adding ammonia contained in urea, the process comprising the following steps: - the temperature of the gases in the exhaust line (6) of the engine (2), upstream of the SCR catalyst (3), is measured, - if the temperature measured is above a predetermined minimum value, called minimum injection temperature, an order is given to inject urea (5), - if the temperature measured is below the minimum injection temperature, the following substeps are carried out: - a mass of ammonia stored in the SCR catalyst (3) is determined, - the amount of ammonia required to obtain a nitrogen oxide conversion greater than a predetermined value is determined, if the mass of ammonia stored in the catalyst is below this required amount, an order is given to activate a method of heating the exhaust gases, and to inject urea into the system. |
