Research On Key Technologies Of New Proportional Electromagent With Magnet-grid Sleeve

As key components of electrohydraulic servo/proportional valves, the proportional electromagnet plays an important role in electric-hydraulic systems in both military and civil industry. The magnetic isolation ring of traditional proportional electromagnet is usually made manully, which is labor-intensive, process-perplexed, high-cost and easy to form gas cavity. For this reason, it cannot satisfy the standard of sustainable development of modern industry. The new proportional electromagnet with magnet-grid sleeve can effectively simplify the process and reduce costs, which is good for automated production. Furthermore, it can solve the widespread problem of shortage of workers, better satisfy the booming market demand, and promot the development of related theory and technology.For the target of simplifying the process, reducing cost, and improving the performance, the key technologies of the new proportional electromagnet with magnet-grid sleeve are systematically, deeply researched, based on theory analysis, analytical calcution, numerical simulation and experimental study. To solve the problem of high cost and sophisticated process of traditional proportional electromagnet sleeve, a novel proportional electromagnet is proposed, in which the single piece sleeve by magnetic-grid structure is adopted. Based on the magnetic analysis and simulation, the influence of various structural parameters is presented in detail. And based on the temperature field model and the stress analysis and design theory, the temperature rise and the intensity of the sleeve are verified. The results of simulation and test of the new proportional electromagnet with magnet-grid sleeve show that the new proportional electromagnet has good static and dynamic characteristics, with a linear working range of 3.6mm, a rated output force of 54N, an output foce hysteresis of less than 2.7%, an electric current hysteresis of 2.2%, and a 50Hz frequency response.The main content of each chapter is summarized as following:In chapter 1, from standpoints of the electromechanical converters for the electrohydraulic servo/proportional valves, the research progress on the key technologies of proportional electromagnet is introduced. The structural, principal, classification, development trend of the electromechanical converters for valves are summarized.In chapter 2, the typical structure and the working principle of the widely used proportional electromagnet are introduced. Based on the related laws of magnetic circuit and magnetic field theory, the characteristics and applications of magnetic circuit analysis method and numerical magnetic field method are introduced separately. The static model of the coil magnetic excitation, the dynamic model and the finite element method model of the proportional electromagnet are established, ande based on which the analytic equation of magnetic output force and the equation of finite element are obtained. In chapter 3, a new proportional electromagnet with magnet-grid sleeve is proposed, the structural advantages and working principles of which are analysed. Based on the analysis and finite element simulation of magnetic circuit, the effects of various structural parameters are deeply analysed, and the static characteristic simulation curves of the proportional electromagnet are obtained. Based on the principles of heat and magnetics, the temperature rise model and the transient temperature field finite element model of the coil are established, and the results of simulation show that the temperature rise is in the working range of the materials. Based on the stress analysis ande design method, the finite element model of the single-piece sleeve is established, simulated ande linearized. And according to the stress classification and stress assessment law, the linearization result shows that the sleeve can endure internal pressure which is large enough.In chapter 4, the constitution and principal of a test system for force characteristics, the performances and test methods of proportional electromagnet are introduced. A proportional electromagnet with magnet-grid sleeve is designed and made, the static and dynamic characteristics of which are tested by the test system. The static and dynamic test results of the proportional electromagnet with magnet-grid sleeve are compared with the simulation results, and the static magnetic field finite element model is verified.In chapter 5, all achievements of the dissertation are summarized and the further research work is put forward.