Ammonia excess dynamic detection method using a software algorithm without ammonia sensor

摘要

The present invention relates toAn apparatus and method for injecting a compound decomposing into ammonia and / or ammonia as a reducing agent into an exhaust gasOne or more SCR catalysts forming a first SCR unitOne or more SCR catalysts that form a second SCR unit and / or at least one ammonia oxidation catalyst and / or at least one ammonia slip catalystAn exhaust gas post treatment system comprising a nitrogen oxide sensor (NOx sensor) for determining the concentration of nitrogen oxide (NOx) in an exhaust pipe and the exhaust gas in the order of flow is provided.The amount of the compounds decomposed into ammonia and / or ammonia injected into the exhaust gas is adjusted using the nitrogen oxide concentration in the exhaust pipe determined by the NOx sensor.An internal combustion engine is characterized by determining the presence of nitrogen oxides from the NOx sensor signal and the presence or absence of ammonia excess in the NOx sensor region.