Study On The Development Of Heavy Duty Diesel Engine For CN Ⅴ Standard

With the requirement of energy saving and emission reduction of the internal combustion engine is becoming more and more urgent in our country;the legislation of vehicle is also getting more strict.From the time when national four emission standard carried out,every automotive vehicle manufacturer is getting ready to develop diesel engines which can satisfy national five emission standard in advance,to obtain the market opportunities and seize the market share.This works based on a model of diesel engine of Weichai with SCR after treatment,and the purpose is to research how to meet the request of national five emission standard.The emphasis of this research is divided into two aspects,the first one is to optimize internal combustion of engine,and the other one is to improve SCR efficiency.Firstly,the research is how to optimize internal combustion of the engine.The work includes the study of the effects of changing combustion chamber,injector and swirl ratio on diesel spray impinging point as well as performance of the engine based on simulation calibration;with the help of ASCMO,a kind of automatic calibration tool,we can obtain the effect of electric control elements on economical efficiency and emission by model analyzing.The main parameter is main injection timing,pilot injection quantity,pilot injection timing and rail pressure.Secondly,the research is how to improve SCR efficiency.This part is mainly based on SCR technologies.The research is to study the influence factor of SCR upstream temperature and SCR efficiency.In order to make it clear for us to upgrade from national four emissions standard to national five emission standard,we analyze the calibration strategy with the fixed combustion chamber,injector,turbocharger and SCR.Finally,the emission level has been improved to national five emission standard by engine test bed experiments.The result of this report has certain reference values on development of diesel engine with low emission to meet the demand of CN V emission legislation,it also has a significant social impact on decreasing diesel engine emission and reducing air pollution in our country.