Study On Two Stage Electronic-hydraulic Servo Valve's Electromagnetic Feild For Direction Position's Force Feedback

Electro-hydraulic servo valve is an important component of electro-hydraulic servo system,the merits of its performance,is directly related to the whole system of control accuracy and response speed,but also a direct impact on system reliability and life expectancy. Bandwidth electro-hydraulic servo valve by valve torque motor moving iron type determined by the natural frequency.while a direct impact on the size of electromagnet torque motor size, it directly determines the quality of torque motor size,so choose the size of a small electromagnetic force large magnetic moment can increase the natural frequency of the motor, thereby enhancing the servo valve to control the speed and precision response. In this paper,introduce the working principle of torque motor,an important performance magnetic materials based on two studies:First:Selection of magnetic material.Before regular use of electro-magnet of the magnetic material Alnico,aluminum nickel and cobalt is very low coercivity,high magnetic permeability,however,it is easy to demagnetization.And Nd-Fe-B have a "magnetic king" of that high coercivity,high magnetic permeability,can not be Demagnetization and energy product of Nd-Fe-B Alnico magnetic energy is the product of 5 times,in the same electromagnetic torque circumstances,is the size of Nd-Fe-B Alnico 1/5,quality is also AINiCo 1/5,while the motor is the natural frequency of 5^1/5 times before.So instead of using Nd-Fe-B Alnico motor to reduce the size of the torque,but also on reducing the size of the servo valve,a reduction of quality,cost savings.Second:Magnetization direction of magnet.Different magnetization direction of magnet, the electromagnetic force have been different,this article from the axial direction of magnetization and radial magnetization direction,the direction of magnetization mixed,45°angle the direction of magnetization along the magnetization direction of magnetic line of force,and ANSYS simulation of electromagnetic fields resulted in several directions after magnetizing the electromagnetic force,namely the axial direction F = 100;radial direction F = 96.2;mixed Magnetizing - two coaxial magnet placed inside and outside,inside and outside the radius ratio of 2/3,the external magnet radial magnetization,internal magnet axial magnetizationF = 126.3;45°tilted magnetic force F = 138.7;the direction of magnetic line of force along the outside F = 144.2.The results show that the outside along the magnetization direction of magnetic line of force is the best direction of magnetization.