| The cylindrical magnetic coupling is a developed type of coupling,which transmits power via magnetic field interaction without mechanical connection.The cylindrical magnetic coupling consists of active(outer)magnetic rotor,isolation sleeve,and driven(inner)magnetic rotor.For the purpose of non-contact transmission,the isolation sleeve is fitted in the middle of the outer magnetic rotor and the inner magnetic rotor in operation,so that the active seal is replaced by a static seal between the driving shaft and the driven shaft.In addition,this developed cylindrical magnetic coupling has been widely used in pump,food,energy and instrumentation industries due to the coupling without mechanical connection transmission,which can solve some problems regarding overload,soft start,driving/driven shafts alignment,and sealing in operation and installation process.The purposes of this dissertation were 1)to analyze the transmission characteristics(i.e.,transmission torque and eddy-current loss)of the cylindrical magnetic coupling via theoretical calculation and experimental measurement,and the effect of the relevant influencing factors(i.e.,electrical resistivity and thickness of isolation sleeve,angular offset,magnetic pole number,thickness of permanent magnet and air-gap)on the transmission characteristics,and propose some methods to improve the transmission characteristics of magnetic coupling to guide the design and manufacture of magnetic coupling in application;and 2)to prepare a nano-sized illtite-smectite(I/S)clay-glass fiber(GF)-polyphenylene sulfide(PPS)composite isolation sleeve with a low eddy-current loss and superior mechanical properties.In Chapter 1,the development and application of magnetic coupling were reviewed,and some advantages of magnetic coupling of mechanically transferring and preventing leakage were represented.This dissertation gave some classification methods of magnetic coupling according to the working principles and the applications in different industries.The methods of designing the cylindrical magnetic coupling were introduced based on three aspects,i.e.,air-gap magnetic field,transmission torque and eddy-current loss.The material composition and flaw of cylindrical magnetic coupling were described.In addition,the major research purposes and contents of this dissertation were also given.In Chapter 2,a transmission characteristics test platform for the measurement of the performance of cylindrical magnetic coupling was designed and manufactured.The structure of the platform for the static and dynamic performance was designed based on the static torque and eddy-current loss generation principle.Also,a software of designing the static and dynamic performance test platform was used.The operation principle of the platform was also introduced.In Chapter 3,the torque transmission principle of the magnetic coupling was analyzed.The formula of transmission torque was proposed according and the Gauss theorem and B-H curve of a rare-earth element permanent magnet material.The effects of angular offset,magnetic pole number,thickness of permanent magnet,air-gap were investigated via the theoretical evaluation with the transmission torque formula and the measurement by the static performance test platform.The results show that the measured results are in a reasonable agreement with the calculated data.In Chapter 4,the eddy-current loss principle in the magnetic coupling was analyzed,and the calculation formula of eddy-current loss was proposed based on the test data.The effects of electrical resistivity and thickness of isolation sleeve,magnetic pole number,thickness of permanent magnet and air-gap were investigated via the theoretical evaluation by the eddy-current formula and the measurement by the dynamic performance test platform.The results indicate that the more magnetic pole number and the greater thickness of permanent magnet,the more eddy-current loss of isolation sleeve as the area of permanent magnet will be.Also,the more thickness and electrical resistivity of isolation sleeve,the more eddy-current loss of isolation sleeve as the same structural parameters of magnetic coupling will be.In Chapter 5,in order to reduce the eddy-current loss of isolation sleeve in magnetic coupling,a composite material of low eddy-current and excellent mechanical properties with PPS resin and nano-sized I/S clay and GF was prepared.The effects of modifier type(i.e.,titanate coupling agent and epoxy resin)and content,content and particle size of the I/S clay,content of GF on the mechanical properties of the composite material were investigated.The results show that the notched impact strength is increased by 60.2% after added 5 wt.% of nano-sized I/S clay with particle size less than 100 nm of 64 wt.%,and modified by 2 wt.% epoxy resin.Furthermore,the tensile strength and flexural strength of the composite material can be enhanced when GF of 30 wt.% is added in the composite material.The nano-sized I/S clay-GF-PPS composite material for an isolation sleeve in magnetic coupling has a rather low eddy-current loss and a superior mechanical properties.In addition,the measured results of eddy-current loss for the composite material are in reasonable agreement with the simulated data.Finally,this dissertation gives the major conclusions and some prospects for future work based on the experimental results obtained. |
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