Research On Diesel Engineperformancemeeting The Nationalstage ? Emission Regulation

State six phase emission regulationswill be implemented from 2020.Emission limits are tightened.The test cycle is closer to the actual operation of the vehicle.The test conditions are more in line with China's conditions.The three-stage fuel consumption regulations require a further reduction in vehicle fuel consumption at that time,which will bring double pressure to the state six phaseengine research.Time is pressing to develop a legal and competitivediesel engine.Explore new technologies and development methods is necessary.In this paper,a four-valve common rail diesel engine is used as the research object,and the application of EGR technology based on VGT is studied in the state six diesel engine,and the nozzle parameters and the combustion chamber shape are optimized.The main work of the paper is as follows:1.From the regulatory requirements,design afeasibleengine technology upgrade route,develop a performance program,the test method process and evaluation principlesis clear.2.The influence of VGT and EGR on the main performance parameters such as engine inlet and outlet pressure,pump gas loss,NOx,smoke and fuel consumption were studied by orthogonal test.thenthree VGT turbochargers are matched and selected.3.The effects of fuel injection pressure and injection timing on the combustion starting point,combustion center,duration,heat release rate and performance indexesare studied.4.Study on the nozzle parameters such as fuel injector flow rate,cone angle,hole number and combustion chamber shape on emissions and performance.5.Finally,in the fixed under the WHSC steady-state operating point calibration test to assess the development objectives of accessibility.Research indicates that sufficient EGR rate can be achieved by adjusting the VGT/EGR in the specified area,and the effect of NOx reduction is significant.In the high-speed conditions,after the introduction of EGR pump gas loss will be significantly reduced,leading to fuel economy improved.The injection timing affects the combustion exothermic phase,The injection pressure affects the shape of the exothermic curve.In high-speed high-load conditions,improve the injection pressure can improve the combustion efficiency,reduce smoke emissions,but the effect is limited.The nozzle flow,cone angle,and hole number have an effect on the combustion characteristics.Although the new dual-zone combustion chamber has the fuel economy advantages in the low-speedlow-load,but the advantage is not prominent.Finally,the WHSC raw emission cycle test results meet the raw emission development targets.