| Electro-hydraulic servo valve is the core element of servo system, which likes a link to connect electrical and hydraulic. It input analog signal and output modulation of flow and pressure. Because of the advantages of fast response, high power magnification, good linearity, small dead zone, dual-nozzle-flapper electro-hydraulic servo valve is widely used in the servo system. It control bit corner through controling input torque motor current, so that alter the gap between the flap and nozzle, which causes pressure difference form the nozzle ends, so that promoting the slide valve core move, achieving the purpose that control output pressure and output flow finally. The important indexes to measure servo valve performance are by stress-flow characteristic and dynamic characteristics, which the later can present the its response speed and stability properties directly. Therefore, basing on the dual-nozzle-flapper electro-hydraulic servo valve characteristics, the study for the right design and test of electro-hydraulic servo valve has the extremely vital significance.First, taking dual-nozzle-flapper electro-hydraulic servo valve as research object, introduce the structure and analysis working principle, understanding each part function and working characteristics, Then calculate the valve dynamic mathematical model in detail from the torque motor to valve controlling cylinder, so concludes the total dynamic mathematical model and block charts. Calculating the stability of a group of servo valve with the structural parameters and function parameters by the given initial conditions. We know that servo valves dynamic performance is not be determine by a certain parameters but by many objective parameter through the main circuit in servo valve on the dynamic design. I select the objective parameters which determine the stability and response of the system as focal point before simulation analysis. Finally by the Simulink soft, reserch the system opened-loop and closed-loop Byrd figure and dynamic performance, and check the correctness of the calculation formula.In brief, through the simulation on open loop and closed-loop transfer function of system, draw step response figure, the open cycle and closed cycle Bord figure in the main loop. it can be concluded the relationship between the objective parameters and servo valves stability and bandwidth through altering the objective parameters continully. The results of the analysis and the ones from theoretical formula was consistent. The open cycle and closed cycle Bord figure by Simulink are more intuitive and accurate in reflecting the relationship on objective parameter and servo valves stability and response than math caculation, which means the simulation is feasible and provides reference and basis for the optimization design of the servo valve. |
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