Research On The Exploratory Experiment On GDI Injector Carbon Deposition

For the GDI engine injector exposed to high temperature and high pressure in the working environment,the injector nozzle will produce serious internal carbon deposition,carbon deposition will change the fuel injector characteristics,affecting the quality of oil and gas mixing,indirect on the engine power,Fuel economy,emissions have a fundamental impact.Therefore,it is necessary to carry out in-depth study of carbon deposition mechanism.In this study,according to the experimental needs,the experimental process is divided into two parts: carbon deposition exploration test and electric heating carbon deposition experiment.Cigarette generation exploration test: According to the experimental needs,the experimental team using dibble burner to simulate the fuel injector in the cylinder fuel injection process.The oil supply system uses SAIC NLE2.0 engine oil supply system,using NI-CRIO controller to control the work of highpressure pump and injector work,the fuel supply system can ensure the stability of the fuel supply system,as far as possible to ensure that the experimental situation Close to the actual engine conditions.The experimental results show that the injector does not produce too much carbon deposits after continuous injection,and the results show that under the continuous injection,the inside of the nozzle is less.According to the results of SEM scanning electron microscopy,at the higher injection frequency,the outside of the nozzle will produce more carbon deposition.According to the results of domestic and foreign research,the most influential effect of the injector is the internal deposition of the nozzle,and the understanding of the carbon deposition mechanism deepens the focus of our research on the deposition of carbon deposits inside the nozzle.Electric heating generation experiment: The experimental team designed an electric heating test bench for the formation of internal carbon deposition.The carbon deposition test program was developed with reference to ASTM D6421 fuel evaluation procedure.The carbon deposition process was developed: heating up for 4 minutes,Heat for 40 minutes,cool down for 16 minutes for a total of 44 cycles.The experimental results show that there is a temperature range between the tail temperature and the final temperature of the nozzle.When the nozzle head temperature is higher than the fuel final temperature,the temperature at the needle valve is due to the temperature gradient May be in the fuel T90 temperature and the final distillation temperature,conducive to the growth of carbon deposition.From the results of the flow characteristics of the experimental results,the nozzle within the carbon deposition will affect the flow rate of the injector,the impact of fueling duration is not particularly evident from the spray characteristics of the experimental results,we concluded that the needle ball seat The effect of carbon deposition on the flow characteristics of the injector is limited,and the effect on the fueling duration is obvious.The carbon deposition that affects the flow is different from the carbon deposition location that affects the duration of the fuel injection.The experimental team observed the injector spray pattern(spray penetration distance and spray cone angle)of the injector at different carbon deposition locations.When the ink inside the injection hole was more and the carbon deposition near the needle ball seat was less,the spray distance There is a tendency to change,the change of the spray cone angle is not particularly obvious.When the ink is less inside the injection hole,when the carbon deposition near the needle ball seat is large,the spray penetration distance tends to be small,and the change of the spray cone angle is not particularly obvious.The spray cone angle of the three groups showed a trend from large to small process,and then finally stabilized.