Research On Simulation And Experiment Of Electronic Control DME Injector

In the current engine research area, it has been found that to reduce the emission of NOx and PM without decreasing fuel economy is difficult to achieve especially with the increasing requirements of emission regulation. Hence the electronic-controlled common-rail fuel injection system and clean alternative fuel technology have been widely concerned about.DME, a new alternative fuel, is believed to be the most promising clean alternative fuel to the diesel engine in the new century. But the wear abrasion and leakage problem caused by low viscosity in the injection system has obstructed the development of the DME. Hence, a new injection system was designed previously in this project, including a new injector and a pressure-exchanger. Based on this design, this report is aimed improve the structure of injector such as variable free lift and effective lift, modificted the sealcontact face, added a guide component for needle valve to guarantee its straight movement.Another aim of this report is to investigate the injection characteristics and also a measuring system has been designed. By comparing the data from simulation and experiment, analyzing the factors and causations which affecting the response time and oil mass characteristics of injector, some conclusions have been found as follows: The response time of injector is affected by three main factors: higher driving voltage leads to less response time; smaller free lift makes the injector opening earlier and longer effective lift makes it closing later.Spray speed is affected mostly by the common rail pressure. When needle valve opened, the higher pressure caused faster spray speed. Furthermore, there are some other affections from free lift in the earlier injection stage while effective lift affecting the later stage.Oil mass characteristic is related to several factors including common rail pressure, free lift, effective life,pre-injection and especially the drive voltage. According to above factors, we select a optimizational parameter of injector structure that free lift is 0.25mm while effective lift is 0.35mm which has a better linear oil mass characteristic.