Research Of Large Flow And High-water Based Electro-hydraulic Proportional Directional Valve

At present,the electro-hydraulic directional valves of the control system use switch valve generally,So it cannot control accurate action of hydraulic support,at the same time,the switch valves' rapid opening and closing will produce hydraulic shock under high pressure and large flow conditions that do the great harm to the components of system,but the electro-hydraulic proportional control technology can solve these problems well.Therefore,the large flow and high-water based electro-hydraulic proportional directional valve is necessary.Firstly,with the research of the valve structure principle and the design theory of the high-water based switch valve and oil medium proportional valve,the large flow and high-water based electro-hydraulic proportional directional valve are designed.The flow field characteristics of electro-hydraulic proportional directional valve under different parameters of structures are simulated and appropriate structural parameters are obtained based on the CFD technology;in view of thelarge fluid dynamics of master valve inlet spool under the high pressure and large flow conditions,fluid dynamic compensation is researched and the results show reason reasonable size of inlet valve spool neck and angle of cone of inlet valve sleeve hole can compensate the axial static fluid power of inlet valve spool well.The mathematical models are established and some key parameters are analyzed?The results show that closed loop feedback is existed;fixed damping hole R,reset spring of master valve spool and control cavity area play an important role in the steady-state and dynamic characteristics of the valve.The control system of high-water electro-hydraulic proportional directional valve is established and steady-state and dynamic characteristics of the pilot valve and master valve are researched based the AMESim.The results show adding flutter signal to input current signal can improve the control characteristic of pilot valve;the greater stiffness of spring of pilot valve,the worse load characteristic of pilot valve;the greater diameter of the fixed damping hole,the smaller overshoot and more stable characteristic of pilot valve.The greater stiffness of spring of master valve inlet spool,the smaller overshoot and more stable characteristic of maser valve inlet spool;with the longer time the inlet spool open,the larger hydraulic shock under direct current signal and Parabolic signal can reduce the hydraulic shock dramatically compared with direct current signal under the condition of not affecting the system response time.In this paper,the control theory,the computational fluid dynamics theory,computer simulation are used in the research of flow field characteristic,the static characteristics and the dynamic characteristics,the structure design and parameter optimization of high-water based electro-hydraulic proportional directional valve and the design.The results of research can provide reference for the design of large flow and high-water based proportional directional valve.