Dynamic Flow Control Strategies of Vehicle SCR Urea Dosing System

来源 :中国机械工程学报 | 被引量 : 0次 | 上传用户:laijiren_ruby1
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Selective Catalyst Reduction(SCR) Urea Dosing System(UDS) directly affects the system accuracy and the dynamic response performance of a vehicle. However, the UDS dynamic response is hard to keep up with the changes of the engine’s operating conditions. That will lead to low NOX conversion efficiency or NH3 slip. In order to optimize the injection accuracy and the response speed of the UDS in dynamic conditions, an advanced control strategy based on an air-assisted volumetric UDS is presented. It covers the methods of flow compensation and switching working conditions. The strategy is authenticated on an UDS and tested in different dynamic conditions. The result shows that the control strategy discussed results in higher dynamic accuracy and faster dynamic response speed of UDS. The inject deviation range is improved from being between–8%and 10%to–4%and 2%and became more stable than before, and the dynamic response time was shortened from 200 ms to 150 ms . The ETC cycle result shows that after using the new strategy the NH3 emission is reduced by 60%, and the NOX emission remains almost unchanged. The trade-off between NOX conversion efficiency and NH3 slip is mitigated. The studied flow compensation and switching working conditions can improve the dynamic performance of the UDS significantly and make the UDS dynamic response keep up with the changes of the engine’s operating conditions quickly.
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