Research On Response Characteristics Of Hydraulic Exhaust Valve For Small Bore Low-speed Diesel Engine

With the increasingly severe energy and environmental issues, variable valve technology has become an important way to improve diesel power, economic performance and reduce emissions to the air. As one form of variable valve technology, hydraulic exhaust valve has changed the driving mode of traditional mechanical exhaust valve, and it could adjust valve timing to meet the needs of different diesel engine operating conditions. In the working process of hydraulic exhaust valve, the size of the structural parameters would be changed due to the wear and tear of the exhaust valve parts,changing working conditions and environmental factors. The exhaust valve lift and the hydraulic system dynamic response could not meet the requirements. The quality of diesel ventilation would be affected. By studying the dynamic hydraulic exhaust valve dynamic response time,the dynamic response speed and the valve lift, the influence of different parameters on the hydraulic system of the exhaust valve is revealed, the significant effect parameters are derived. It is of great significance to optimize the engine performance.Wartsila RT-FLEX35 diesel engine hydraulic exhaust valve system was in-depth analysed in this paper. The hydraulic exhaust valve system simulation model was built by AMESim simulation platform , including servo oil rail, solenoid valve, VCU control unit and exhaust valve components, etc.By comparing the simulation model results with relevant data ,the model accuracy had been verified, and this model could be applied to research the exhaust hydraulic valve system.The hydraulic exhaust valve was analyzed by AMESim simulation model. The dynamic response of the exhaust valve and valve lift were researched in the typical condition, and obtained different parameters influence to the dynamic response time and valve lift. The exhaust valve speed was analysed in different conditions,and concluded that the exhaust valve speed was affected by rail pressure, cylinder pressure and the parameter variations. The key parameters which affected the speed were obtained through quantitative analysis. The interaction of different factors and the factors which influenced exhaust valve speed were studied by correlation analysis,and obtained the speed prediction model to predict the dynamic response speed of the exhaust valve.