| The liquid-suspended three-degree-of-freedom motor is a electromechanical energy conversion device of multi-degree-of-freedom motion with novel structure,high efficient environmental protection,high integration and miniaturization.Considering the liquid suspension mechanism,the motor adopts a lubricating support structure.Under the condition of hydrodynamic lubrication,a layer of dynamic pressure oil film is formed in the gap between the stator and the rotor to isolate the stator and the rotor and support the load.The mechanical friction is converted into liquid friction,which greatly simplifies the complex mechanical structure and has a wide application prospect.However,the electromagnetic theory analysis,lubrication theory analysis and experiment of this kind of motor are still in the exploratory stage,which urgently requires in-depth research.The specific work of this paper is summarized as follows:Firstly,the structure and working principle of the new motor are introduced.The three-dimensional model of the motor is established,and the distribution of permanent magnet magnetic field,air gap magnetic field,internal and external magnetic fields of energized coil are calculated.Based on the electromagnetic field theory analysis,the electromagnetic structure of the motor is taken as the research object to carry out the analysis.The stator coil of the motor generates heat after being energized,so that the motor obtains temperature rise,and the temperature distribution leads to thermal stress distribution.The temperature rise,displacement and stress-strain distribution of the electromagnetic structure are obtained by the simulation calculation of the magnetic,thermal and solid sequence coupling of the motor.Secondly,the new type of motor considering liquid suspension mechanism has a special structure,so it is difficult to directly apply the lubrication theory of rectangular coordinate system and cylindrical coordinate system to this type of spherical bearing motor.In this paper,a mathematical and physical model suitable for lubrication theory analysis of permanent magnet spherical motor is established,the Reynolds equation and oil film thickness equation suitable for spherical bearing lubrication in spherical coordinate system are deduced,and the equations are solved numerically by finite difference method and MATLAB programming.The influence of different parameters on the lubrication performance of the motor is analyzed by using the control variable method;And the experimental platform for the oil film viscosity-temperature test is also built with the relationship between viscosity and test temperature and operation time derived.Thirdly,in order to deeply study the influence of oil film pressure distribution and the actual deformation of spherical bearings when cavitation phenomenon is considered,the simulation of gas-liquid two-phase flow phenomenon and fluid-solid coupling analysis of spherical bearings are realized by using multi-physical field coupling simulation calculation;The change of oil film pressure of spherical bearing with or without cavitation effect is studied;The oil film pressure distribution and gas phase volume fraction distribution at different rotational speeds are calculated;And an oil film pressure test platform for spherical rotor at different rotational speeds is built.The measured experimental data are consistent with the numerical results.Fourthly,the control variable method is used to analyze the influence of many variables on the mechanical properties of spherical bearing,such as displacement,stress and strain,etc.At the same time,the structure of spherical bearing is innovated,and a new type of spherical bearing with groove is designed.The inner surface of stator spherical shell is provided with spiral or annular groove.Then the spiral groove and annular groove bearing models are established.The structural static analysis is carried out on bearings with different groove numbers and groove radius,and the most superior spherical bearing with groove is selected through comparison.At last,a device for simulating the rotation of spherical rotor in liquid is proposed.The "rotating machinery,turbulent ?-?" physical field is used to analyze the hydrodynamic device model,and the turbulent field inside the rotor,the pressure of the rotor spherical shell and the free liquid level distribution are numerically simulated;A model test for the suspension of a dynamic spherical rotor in liquid was built,using the test device to obtain the power of the rotor at different speeds,the power difference between the numerical simulation and the experimental study is compared and analyzed to verify the accuracy of the numerical simulation. |
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