Optimization And Experimental Research On Spool Of High Frequency Response Piezoelectric Servo Valve

With the rapid development of aerospace industry and military equipment,higher requirements are put forward on the performance of hydraulic servo valves.Higher working pressure,larger flow,and high frequency response have become the development trend of hydraulic servo valves.Research has found that piezoelectric materials as the drive components of servo valves have more advantages than traditional electromagnetic-driven servo valves in many aspects.With the in-depth research of high-frequency response piezoelectric servo valves,according to the working conditions of high working pressure and large flow,the fluid force of the power stage spool and the inertial force of the spool itself on the dynamic performance of the servo valve cannot be ignored.The internal fluid force compensation and structural optimization of the valve have become the development process of large flow and high frequency response piezoelectric servo technical problems that need to be solved urgently.The study of this thesis is based on a three-stage piezoelectric servo valve with large flow and high frequency response under development.The goal is to obtain the best structure of valve chamber/spool with the lowest possible fluid force on the spool and the smallest possible spool quality.The spool structure ensures that the piezoelectric servo valve developed has better dynamic performance.The main work content is as follows:(1)Refer to relevant research documents,summarize the development status and technical bottlenecks of servo valves with large flow and high frequency response,explain the current research status of servo valve spool structure and fluid resistance,and point out that the advantages of piezoelectric servo valves with large flow and high frequency response and technical problems that need to be overcome urgently.(2)Analyze the type and formation mechanism of the fluid force acting on the spool of the servo valve in the actual movement process,explore the relationship between the fluid force and the valve chamber/spool structure parameters,and conduct an overall force analysis of the traditional spool movement process to obtain the force balance equation of the spool.(3)Based on the piezoelectric servo valve developed so far,the traditional structure of main spool and flow passage used by the piezoelectric servo valve are analyzed.Based on the established mathematical model of the spool structure parameters and fluid resistance,the fluid resistance compensation scheme is put forward,and the weight reduction design of the valve is carried out under the premise of satisfying the rigidity/strength.(4)According to the proposed spool fluid resistance compensation scheme,the fluid force and quality of the new spool are used as the objective functions,and the genetic algorithm is used to optimize the specific structural size parameters inside the servo valve to obtain the optimal valve chamber structure.(5)Based on fluid-solid coupling theory and dynamic grid technology,the traditional spool and the optimized new spool are numerically analyzed and calculated by using flow field simulation software,and the flow characteristics inside the piezoelectric servo valve with two different spools,such as the field distribution,the steady-state hydraulic force of the spool and the hydraulic force experienced during the movement of the spool,are compared.Through fluid-solid coupling analysis,the rigidity of the spool in the limit state is checked.The spool undergoes The modal analysis and transient response of the traditional spool and the new spool are simulated by using MATLAB/Simulink simulation software.(6)Build a piezoelectric servo valve test platform,conduct a dynamic performance test on the designed piezoelectric three-stage servo valve under no-load conditions,and compare the frequency characteristics and transient characteristics of piezoelectric servo valves with different spools.Compared with the traditional spool,the new spool with force compensation and weight reduction design has improved dynamic performance.