Research On Electromagnetic Servo Mechanism For Axial Force Control Of Scroll Machine

Miniature cryogenic refrigeration system is widely used in aerospace,medical equipment,integrated circuit,automobile and other fields.How to develop an efficient,stable and reliable refrigeration cycle system with small volume has become the current research direction.Microexpander has become an effective solution and research hotspot due to its direct drive,compact structure and small size.However,compared with the advantages mentioned above,the axial force of the miniature expansion machine is difficult to control in the process of high-speed translational operation,and the leakage problem is always the main factor affecting the development of the scroll machine.Therefore,it is one of the key problems to realize the balance of axial gas separation force and axial sealing of rotor and stator vortex disc.For the research on axial force control of vortex machine,the main work in this paper is as follows:In this paper,the working principle of vortex machine and the reason of axial force are introduced briefly.In order to meet the requirements of axial sealing during operation,the mechanical structure,temperature and balance characteristics of the micro expansion machine were studied,and the electromagnetic mechanism of axial force balance for the micro scroll machine with integrated structure,compact size and internal insulation was proposed.Secondly,the horizontal interference force will be generated when the axial force balance electromagnetic mechanism performs high speed translation inside the vortex machine.The horizontal force should meet the requirements of the micro-vortex machine.Therefore,based on the size limitation of the electromagnetic placed inside the scroll machine,the single parameter optimization and global optimization of the axial and horizontal forces of the dynamic electromagnetic servo structure and the static ring permanent magnet structure were carried out to meet the requirements of the axial and horizontal forces of the micro-scroll machine.Thirdly,a solution was proposed to solve the problem of static and static vortex disc wear caused by the static ring permanent magnet structure during operation.The magnetic field distribution characteristics of permanent magnet and core of the static ring permanent magnet structure were studied,and a steady-state adjustable electromagnetic servo structure with the coil outside was established.The coil current is controlled by the exhaust pressure to reduce the axial force and extend the life of the vortex machine.At last,two kinds of experimental test schemes are proposed for the static ring permanent magnet structure.One is to measure axial force by spring tension and compression tester,which has the feature of easy clearance adjustment.Another method is to build a two-dimensional linear motor platform to simulate translational platform and a three-dimensional force sensor for three-dimensional force measurement.By comparing the simulation and experimental results,the accuracy and error sources of the experimental method are explored and summarized.