SCR Aftertreatment System Research And Development Of Electronic Controls Diesel Engine

PM and NOx are the main pollutants in diesel engines. How to reduce the composition ofthe two exhaust gas to the state IV emission levels is difficult and research hot spots in dieseltechnology area today.This thesis studied thoroughly the operation mechanism of SCR and thephysical and chemical characteristics of catalyst.On the basis of the methods of experimentvalidate the theory,establishing SCR after-treatment platform.This platform has excellentreliability,usability, scalability,the test result indicate that the emission of engine meet the CNIV regulation required level.I compare and analyse all kind of after-treatment system,I consider the technologyfeasibility,performance index and cost factor,I choose the SCR after-treatment system as themethod of reduce exhaust gas.I describe the detail of detection and control link of SCRafter-treatment system.On the basis of SCR after-treatment platform,simulation design withSCR control strategy and OBD diagnostic strategy to testify the reasonableness andefficiency.In order to reduce the PM and NOx,real-time collect the related information ofvehicle,this project adopted CAN bus which communicate and control data to interact databetween bus pitch points of ECU,DCU,GROUDFUS Urea Dosing Pump and NOx-Sensoreffectively,validate the pitch pom strategy.Virtual net simulation environment is setup accordwith J1939 communication protocol in the simulation and this net is used to test practicalpitch points．By this net，the communication is realized among practical hardware，DCUvirtual pitch points and virtual meter pitch points.In order to achieve the test,SCR bench testing system is established and the experimentand primary data calibration are analyzed.The test result indicate that the result meet therequired of CN IV emission regulation.The SCR after-treatment system of diesel engine research in this thesis, has excellentreliability,usability, scalability, etc.After improve the software and hardware to match theengine,making SCR after-treatment system performance have significantly improved,SCRsystem able to realize the system’s real-time response request.The research and developmentof the after-treatment technology has important practical sence and real value for improvingdomestic CN IV diesel engine emission level.