Study On Proportional Electromagnetic Valve Drivers

Proportional electromagnetic valve is an important element in hydraulic pressure systems. The operation behavior of a hydraulic system mainly depends on the characteristic of the electromagnetic actuator used. Therefore, how to improve property of the actuator (driver) used for proportional valve is an important subject in the field. As an actuator driving a proportional valve, linear motor has its potential advantages, so has been found some applications and attracts in researcher's attention. As the same reason, it is the purpose of the study in this thesisLinear motor as driver of electromagnetic valve may be divided into three kinds, proportional solenoid, permanent magnetic moving winding linear motor and hybrid linear force motor. Inchapter two, chapter three, and chapter four of this thesis, each kinds of the three kinds of actuator is presented respectively. Proportional solenoid has the advantages of simple structure and cheap cost, but hard to get the good property by designing. In this thesis a well designed proportional solenoid is introduced. The solenoid can output quasi constant force within a certain displacement range. Permanent magnetic moving winding liner motor can offer good force-displacement characteristic and the force is proportional to winding current. So it can be controlled easily and can be used in many situations. A simple analytical formulas derived in this thesis are used to design this kind of motor. The results calculated are the same as those calculated by Finite Element Method and so to prove the correctness of the method presented. Hybrid linear force motor because of high output force and easily control may be used in many situations. A kind of linear motor produced by Moog company is analyzed here, A sample linear force motor is made on the basis of the analysis. And then output force characteristics by measured are obtained by experiment. The results of experiment prove that the theory results are correct.This thesis presents two approaches analytical method and finite element method. Analytical method is a kind of simple approach for magnetic calculation. It may get the analytical formulas to calculate the parameter of the motor approximately under some equivalent conditions. The finite element method can get the exact results, but can not find the relationship about the parameters in an analytical form, besides, the calculation process is complex. Now, with the development of computer finite element field analysis be comes easy to use. The solvers used in here are Magnetostatic solver and Transient solver of Ansoft. This solver can clearly display the result curve when every parameter varies. In the second chapter, parameter calculation solver in Magnetostatic is used for getting output curves when special dimension of the actuator is changed. In the third chapter finite element field method prove that the results are correct calculated by analytical approach. In the forth chapter a actual linear force motor is analyzed by finite element method. The experiment results are very close to the results calculated by finite element field method, and it proves that the calculation solutions are correct. Using the Transient solver,transient characteristics are obtained under the conditions supplied certain voltage. The research results can offer the theory base for the further application to control system.