Adaptive management control for Urea-SCR system of clean diesel vehicle

A Urea-SCR system can significantly reduce the tailpipe-out nitrogen oxide (NO_x) of a diesel engine vehicle. However, future emission legislations in Europe and U.SA require the Urea-SCR system both to improve NO_x conversion efficiency and to suppress ammonia(NH₃)-slip at the same time. The robustness of the management control of the Urea-SCR system has to be significantly improved in regard to the part-to-part variations of Urea-solution injector and the aging effect of a SCR catalyst. Consequently, the management control was composed of a feedforward controller, a NH₃ storage controller and a feedback controller using an NH₃ sensor located downstream of the SCR catalyst, and a unique adaptive algorithm was applied to improve the robustness of the management control. As a result, it could improve the robustness of NO_x conversion efficiency, and reduce NO_x to the lower level than emission legislations´ requirement while keeping NH₃-slip at slight level.