Aiming at the failure of SCR catalyst due to aging,sulfur poisoning and other factors,this paper evaluates its failure based on conversion efficiency,and introduces a failure factor to characterize the failure degree of SCR catalyst.On this basis,the urea injection amount under different working conditions is modified to ensure that the exhaust emissions meet the OBD limit.Finally,taking a type of 6-cylinder high pressure common rail diesel engine as an object,a post-processing system which has been partially aged and failed is installed to carry out bench verification.The test results show that:After the failure factor is corrected,emission of engine exhaust is 1.4 g/(kW·h)under steady cycle condition and 1.77 g/(kW·h)under transient cycle condition,which is basically equivalent to the value before the catalyst failure,and both are lower than the four-stage regulations of non-road countries,effectively reducing the negative impact of catalyst failure on SCR system.
SCR SystemUrea DosingFault DiagnosisFault Tolerance Control
维普
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