Applied Study On Exhaust Gas Recirculation To Diesel Engines

With the increasing of automobile numbers, automobiles gradually become the main source of air pollutions. In particular, the increasing percentage of diesel vehicles in the whole power vehicles will worsen the air quality, as the diesel engines emit a great deal of PM and NOx. It is difficult to decrease PM and NOx simultaneously by engine modification. Besides, their corresponding technologies are not mature and largely applied, therefore research for the control of diesel engine emissions has great social and practical SignificanceThe main aim of the thesis is to develop a kind of model system that uses variable EGR ration for control in order to decrease NOx efficiently. Subordinately, the technology for reducing both NOx and PM is also studied. In the thesis, the arrangement of EGR system and control strategy are studied, the performance of electronically controlled EGR system is introduced in detail. At the same time, the combination of the new model system and bag filter system are investigated. And the EGR valve opening stability has carried on the simple hydrodynamics simulation in matlab/simulink, confirmed this system to be consistent with the test result stability, could get up truly the good reduced NOx emissions function.