Research On Dual Magnetostrictive Rods-based Electro-hydrostatic Actuator With Active Rotary Valve

With the development of aircraft towards high maneuverability,ultra-high speed and lightweight,higher requirements are put forward for the rapidity and stability of the actuator system.Electrohydrostatic actuator driven by smart materials have the advantages of fast response speed and compact structure,which provides the possibility for integrated,lightweight and efficient actuator system.At present,electro-hydrostatic actuators driven by a single smart material are studied by researchers,however,their output flow rate is small and the load capacity is weak,thus,actuators driven by a single smart material can not be applied to the actual situation.Generally,distribution valves used in such actuators are usually divided into two categories: passive valve and active valve.Actuators which are rectified by passive reed valve have poor output performance under a high driving frequency and the piston of the hydraulic cylinder can not achieve bidirectional motion;in contrast,Actuators which are rectified by active rotary valve can make full use of the high-frequency characteristics of the smart material,in addition to that,the active rotary valve integrate two functions: oil distribution valve and reversing valve,which make the actuator’s function more comprehensive,therefore,using the active rotary valve improves the output performance of the actuator.In this thesis,based on the applications of multi-smart materials unit at home and abroad and the related research on electro-hydrostatic actuator driven by smart material,a novel electro-hydrostatic actuator driven by dual magnetostrictive rods with active rotary valve is presented,and its theoretical and experimental research is carried out.Firstly,based on the working principle of electro-hydrostatic actuators driven by smart materials,the structure of an electro-hydrostatic actuator driven by dual magnetostrictive rods is designed.The structure of the active rotary valve,the matching motion between the speed of valve core and the driving frequency of the magnetostrictive pump,and the selection of the fit gap between the valve body and the valve core are analyzed.Then,finite element numerical analysis of the active rotary valve is carried out through the simulation software ANSYS/Fluent,and several factors which would affect the flow speed of the oil and the pressure drop across the valve port are determined.Those factors provide a reference for subsequent optimization of the valve’s structure.In addition,the mathematical model of the flow area of the active rotary valve is established in Matlab/simulink,and its change law is described accurately.Furthermore,the simulation model of the entire system is established by mathematically modelling each component of the actuator.The output flow of the actuator under different matching relations are obtained and the reflux phenomenon of the system is analyzed.The simulation results show that the designed actuator can realize a continuous bidirectional output displacement of the cylinder and the servo control of the actuator’s output flow rate can be realized.Finally,the experimental test platform of the actuator system is set up,and DSP technology is used as the controller.The experimental results show that: the optimum driving frequency of the designed actuator is 150 Hz,the maximum no-load output flow is 2.61L/min,and the maximum load is about 55 Kg.When the same total length of the magnetostrictive rod is selected,compared with the single magnetostrictive rod-based electro-hydrostatic actuator with passive valve or even with active rotary valve,the maximum output flow of the designed actuator is increased from 1.26 L/min to 2.61L/min,and the carrying capacity is also significantly improved.The main innovations in this thesis are the following: To adress the technical problems of low output flow rate,single direction and vibrating movement of actuators driven by single smart material,a novel electro-hydrostatic actuator driven by dual magnetostrictive rods is proposed.The simulation model of the designed actuator is built and the prototype is manufactured.The output performance of the designed actuator is studied.The results show that: the output displacement of the actuator is continuous,the load capacity is improved,the output flow rate is high,and the servo control of the actuator’s output flow rate can be realized.