Simulation And Experimental Research On Dynamic Characteristics Of Low-speed Engine Exhaust Control Test Bench

For the marine low-speed two-stroke diesel engine,the exhaust control mainly adopts the ME-C of MAN company and the electro-hydraulic driving exhaust valve driving mechanism used in the Flex type intelligent diesel engine of W?rtsil?company.In recent years,with the development of independent research and the plan of domestic marine low-speed engine,the driving mechanism of electro-hydraulic exhaust valve has become the mainstream of low-speed engine exhaust control.However,there are still some problems in the design of our own products,such as the motion control stability of large inertia valve,the dynamic characteristics of complex electro-hydraulic drive system and so on.In view of the above problems,the domestic research is usually carried out through simulation or single cycle platform test,the research means and the limitations of the test platform,but it is still unable to reveal the parameter influence characteristics and lift jitter and other instability problems in the actual driving process of the air valve.Based on 340 EF type low-speed two-stroke diesel engine,this paper presents and designs a set of test-bench for exhaust drive control of two-stroke low-speed diesel engine,which can simulate the cylinder pressure and exhaust back pressure under different working conditions in real time.Through the design of bench scheme,AMESim modeling and simulation,and test verification,the influence of system drive pressure,air spring pressure and other parameters on the exhaust gas distribution drive characteristics is studied.First of all,based on the electro-hydraulic exhaust valve drive system of 340 EF marine low-speed engine,a valve controlled cylinder device is designed to realize the simulation of cylinder pressure and exhaust back pressure,which is used to simulate the influence of cylinder pressure and exhaust back pressure on exhaust valve in real-time in the process of valve movement,to make the valve drive work in a dynamic environment close to the actual situation,and to make up for the lack of single cycle test and research Carry out multi cycle test research in the test environment.Secondly,in AMESim software,the simulation model of the flexible exhaust test-bed of the low-speed machine is built,and the calibration of the exhaust valve drive system under the four loads of 25%,50%,75% and 100% is completed.By using the verified simulation model,the influence of the system driving pressure and air spring pressure on the driving characteristics of the air valve,such as the opening phase,the opening process duration,the closing phase and the stable lift of the air valve,is analyzed.Thirdly,according to the results of model simulation,optimize the design scheme,build the exhaust control test-bed of low-speed machine,including the driving mechanism of electro-hydraulic exhaust valve,cylinder pressure and exhaust back pressure simulation device,driving oil source,x PC control and data acquisition system,and complete the calibration of air valve lift test.Finally,based on the above-mentioned test-bed,carry out the experimental research on the movement characteristics of the valve under the condition of no cylinder pressure simulation and with cylinder pressure simulation,explore the stability and dynamic characteristics of the valve movement control,and reveal the influence law of the dynamic characteristics.The relevant research results provide theoretical reference and experimental verification platform for the follow-up research of low-speed air valve improvement design and flexible exhaust.