Research On Design And Operating Characteristics Of Double Cycloid Permanent Magnetic Gear

Mechanical gears are widely used due to their advantages of high transmission efficiency and high torque density.But in the condition of heavy load,due to its high-strength-contact transmission,it is easy to cause gear teeth to break,glue and wear which make transmission gearbox wholey broken.At the same time Mechanical gears also need regular maintenance,which affects the productivity.Although existing permanent magnetic gears adopt non-contact transmission,it is difficult to apply to actual productive condition due to the limitation of low torque density.In order to solve the above problems,this paper designs Double Cycloid Permanent Magnetic Gear(DCPMG),which can not only realize non-contact transmission,which prolongs the service life of the gearbox,but also achieve large torque density(up to about320k N·m/m~3).This paper firstly summarizes the mechanical structure and the operating mechanism of DCPMG.By analyzing the coupling principle of different methods of magnetization of permanent magnets,it is determined to use Halbach magnetization array.With the space harmonic method,the transmission ratio model of DCPMG is established.By defining the relationship of the harmonic number of the pole pairs,the relationship of the number of the pole pairs of the permanent magnets on the surface of each rotor and stator can be determined.With the principle of electromagnetism,the air gap magnetic density expression of single permanent magnetic ring of DCPMG is obtained.According to the changing state of inner and outer air gaps of DCPMG,the electromagnetic torque expressions of inner and outer air gaps are given,respectively based on the Lorentz force and the Maxwell tensor method,which lay a foundation for the subsequent analysis of the operating characteristics of DCPMG.Due to the complex cycloid motion of the high-speed rotor,its motion state cannot be adequately described in the Ansys maxwell environment.Therefore this paper establishes a dynamic equivalent model of DCPMG in the Ansys maxwell environment,and the no-load and loading analyses are carried out which are to verify the correctness of the equivalent model.The start-up characteristics of DCPMG are analyzed by graphical method,based on the theorem of moment of momentum and kinetic energy,and the finite element verification is carried out in Ansys maxwell environment,so as to determine the favorable start-up conditions for DCPMG.By analyzing the overload protection mechanism and eddy current loss characteristics of DCPMG,the self-regulation mode of DCPMG during overload is given,and it is found that the eddy current loss of DCPMG is low in stable operation.Based on the Maxwell tensor method,the resultant unbalanced magnetic force on the inner and outer air gaps of the high-speed eccentric rotor is calculated.And based on the response surface method,define the electromagnetic torque and the resultant unbalanced magnetic force as the response targets.By optimizing the structural parameters of DCPMG,the unbalanced magnetic force is reduced while increasing the output torque.