| Electro-hydraulic servo valve is the core componets of the electro-hydraulic servo valve control system, and the connection between electrical control components and hydraulic actuators. Its performance directly restricts the response characteristics, control precision, reliability and longevity of the electro-hydraulic servo control system. Electro-hydraulic servo valve is a complex component integration of mechanics-electronics-hydraulics; Its dynamic characteristic is decided by many factors. So how to further study the characteristics of electro-hydraulic servo valve, and seek effective methods will be the research emphasis for the researcher in the future. Taking the nozzle-flapper force feedback type two-stage electro-hydraulic servo valve as the main research object, the paper analyze the structure principle, static characteristic and dynamic characteristic and main performance indicators, and then uses different modeling methods to establish simulation model and dynamic analysis, studies of the key factors that influences the servo valve characteristics.Firstly, the paper has established the complete mathematical model of each section of the electro-hydraulic servo valve by using analytical method, which is provided a theoretical basis for other modeling methods. The main structure parameters of torque motor were analyzed emphatically on the influence of the transient response of servo valve to find out the most affected key parameter which was easy to modify and the same time. Then established bond graph model of electro-hydraulic servo valve from the point of view of the power flow, the model has clearly showed the transformation, distribution, and dissipation of various energy in the servo valve. The state equation deduced through the model can be used to verify and supplement the mathematical model because the nonlinear factors of each link has been fully considered. Finally, the graphical model of electro-hydraulic servo valve was established by using AMEsim software, and the main static and dynamic characteristics and performance indicators were analyzed in detail.The results showed that the dynamic characteristics of servo valve is the combined effect of different factors and parameters, and the variation of torque motor parameters has important effects on dynamic performance of servo valve, so it should not be only linearization simply in the simulation. Each modeling method has its different emphasis, but together they complement each other nicely to make a comprehensive study on the characteristics of the servo valve. The study on characteristics and simulation modeling method of servo valve is of great significance for the optimization and improvement, and the same idea can also be applied to the simulation of other hydraulic components. |
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