| 摘要 |
The invention relates to a method for cleaning an SCR system whereby reducing agent is supplied to an exhaust flow upstream of an SCR catalyst (260), NuOmicronx contents of the exhaust flow are determined upstream and downstream of said SCR catalyst (260) and reducing agent crystals are removed by a high-temperature procedure. The method comprises the steps of - determining (s430) a ratio (K1) between respective NOx contents determined downstream and upstream of said SCR catalyst (260) at a temperature (T1) of said SCR catalyst (260) at which reducing agent crystals do not vaporise, - raising the temperature (s440) of the exhaust flow in order to vaporise reducing agent crystals with a view to cleaning, - determining (s450) a ratio (Kn) between respective NOx contents determined downstream and upstream of said SCR catalyst (260) at a temperature (T2) of said SCR catalyst (260) at which reducing agent crystals vaporise, - comparing (s460) said ratios (K1, Kn) and using this comparison as a basis for deciding whether reducing agent crystals have been removed to an intended extent. The invention relates also to a computer programme product containing programme code (P) for a computer (200; 210) for implementing a method according to the invention. The invention relates also to a device and a motor vehicle equipped with the device. |
