A Study On Injection Rate Of Comment Rail System By The Zeuch Method

In the last 20 years,the rapid development of the electric control high-pressure comment rail system has been one of the most important studies in the field of diesel engine research.It is easy for high pressure common rail system to actualize flexible control of fuel injection,which makes the fuel injection timing and injection times out of the bondage of diesel engine rotating speed.Fuel injection rate is the basis of the strategy research of high pressure common rail fuel injection system,as well as the important reference basis of the research of mixture formation and combustion process in cylinder.Fuel injection rate directly affects the engine combustion quality,affecting its performance,fuel economy and emission characteristics,mechanical durability,vibration noise,and other important performance indexes.So,the fuel injection rate research has great significance of engine design and development.In this paper the test methods of the fuel injection rate were discussed,and a test platform basis on the principle of Zeuch method is designed and built.In this paper,the test platform of hydraulic mechanical module structure is designed,and according to the experimental requirements,a controlling system based on MCU and a test system based on virtual instrument were design in this paper.In the experiment,the operation method and the data analysis method of the fuel injection rate test platform are discussed and optimized.And the effect of different test conditions on the measurement effect is compared.It is found that the measuring result is better when the back pressure of the system is above 1MPa,and the measuring result is affected by the location of the injector of pressure sensor.The precision of the measuring device is analyzed and compared by using the high precision electronic analytical balance,and the elastic modulus of diesel is corrected by the calibration,after that,the measurement error is less than 1%.The fuel injection rate test result is also compared with EFS8246,and test reliability of the platform is validatedIn this paper,the characteristics of fuel injection rate of the injector of common rail system are experimentally analyzed by using the designed fuel injection measuring device,and the variation of fuel injection rate and the influencing factors under different working conditions are analyzed and discussed.The response time of the needle valve opening and closing,and the maximum duration of the needle valve lifting are analyzed.The experimental analysis of the multiple injection law is carried out by using the designed measuring device.It is found that the promotion of the injection rate between the pre-injection and the main-injection is the most obvious when the injection interval is 0.5ms,with the pulse width is 0.5ms and the rail pressure of 80 MPa.To study the formation mechanism of fuel injection rate,the pressure of the storage chamber is also tested and studied in this paper.It is found that the pressure fluctuation in the storage chamber after pre-injection will affect the change of the pressure in the storage chamber during the main injection process.Because of the superposition of the pressure wave in the storage chamber,the main injection rate is changed in the process of multiple injection.