PROCÉDÉ ET DISPOSITIF DE COMMANDE DE QUANTITÉ D'INJECTION POUR SYSTÈME D'INJECTION D'URÉE DE SCR DANS UN MOTEUR

摘要

The present application provides a method for controlling an injection amount of an SCR urea injection system in an engine, the method comprising: using an ammonia loading amount model to calculate a current ammonia loading amount in an SCR reactor on the basis of an injected aqueous urea solution amount and a consumed ammonia amount; obtaining a first urea injection amount on the basis of a target ammonia loading amount and the current ammonia loading amount; using an SCR efficiency model to calculate a second urea injection amount on the basis of a catalyst temperature, an exhaust gas mass flow rate and an aging coefficient in the SCR reactor, a nitrogen-oxygen compound concentration upstream of the SCR reactor, and the current ammonia loading amount; combining the first and second urea injection amounts to obtain a combined urea injection amount; and obtaining a target urea injection amount injected to the SCR reactor on the basis of the combined urea injection amount and a urea injection amount limit value. Using the method described above, the amount of urea injected into the SCR reactor can be precisely controlled, thereby preventing the occurrence of urea crystallization in an engine exhaust pipeline and the SCR reactor.