Design And Study Of The New Magnetic Field Modulated Magnetic Gear

Gears are widely used in torque transmission between shafts of mechanisms, whileit can accordingly change rotational speed and torque. The most widely usedmechanical gears have several disadvantages, such as low reliability, highmaintenance requirements and noise, which restrict its application. Because of thecharacteristics of the traditional mechanical gears, in recent years magnetic gearshave drawn a lot of attention. There is no mechanical contact between the input andoutput shafts in magnetic gears, so it has high reliability, high efficiency and no needof lubricating which mechanical gears do not have. This paper studied the magneticfield modulated principle, discussed the design principle of magnetic field modulatedmagnetic gear, and proposed improvement structure according to the disadvantage ofexisting structure.Taking a classical magnetic field modulated magnetic gear as an example, first ofall, the working principle was studied using the analytical method, andthe modulation function of the modulated ring on the magnetic field was discussed,also the relationship between inner and outer rotor permanent magnets pole pairs andmagnetic blocks was determined. The2-D finite element model was established, andthe air gap flux densities of various conditions were extracted in order to verify theanalytical analysis. The transmission ratio and parameters of existing structure wereoptimized, and the match principle of transmission ratio and the parameters whichhad the best performance were obtained.The existing structure has an obvious end leakage. The3-D finite element modelincluding end air was established in order to study the effect of the end leakage. Forthis problem, the improved magnetic field modulated magnetic gear was proposed.The parameters of new structure were optimized, and the torque transfercharacteristics which included static and steady state torque after optimization wereobtained to verify the improvement in the performance of new structure. Although the traditional structure was improved, the problem which still exists wasthe difficulty in assembling. For this problem, hybrid magnetic circuit magnetic gearwhich assembling process was simple was studied. This kind of magnetic gear alsohad disadvantage which is that the inner space utilization rate was very low. For thisproblem, the improved structure was proposed to make full use of the inner space ofhybrid magnetic circuit magnetic gear. For doing this, the maximum torque whichthe device could transfer was raised in condition of no increase of volume of thedevice, so the torque density was increased. The3-D finite element model of newstructure was established, and the parameters of which were optimized. The torquetransfer characteristics which included static and steady state torque afteroptimization were obtained, and were compared with the hybrid magnetic circuitmagnetic gear which didn’t make use of inner space to verify the improvement in theperformance of improved structure.