| Magnetorheological Fluid(MRF),as a new type of smart material,is mainly composed of micron-sized ferromagnetic particles,carrier liquids and trace additives.In the absence of an external magnetic field,MRF behaves as a Newtonian fluid.Under the action of an external magnetic field,the apparent viscosity of MRF will change to a large extent,which is manifested as the characteristics of Bingham fluid.The rheological properties of MRF can undergo rapid,reversible and convenient control.Magnetorheological Transmission Device(MRTD)is a novel power transmission device.This device mainly relies on MRF as the medium for power transmission.The output characteristics of the device are continuously adjustable,which can effectively transmit the output torque and speed has far-reaching development significance and application prospects.According to the problems existing in the current MRTD research,this paper studies the following aspects.The mechanism of magnetorheology was studied,the MRF required for the experiment was prepared,and the factors affecting the performance of MRF were analyzed.In order to clearly understand the manifestation of MRF under the action of magnetic field,observe the speed of ferromagnetic particles gathering into chains,and observe MRF in real time through a microscope,mainly to observe the dynamic change of MRF from the condition without magnetic field to the condition with magnetic field,A constitutive model of the yield stress of magnetorheological fluid with magnetic field is proposed.A permanent magnet axial adjustment type MRTD is designed.This device is different from the traditional pure shear type transmission device,and the shear-squeeze joint action can exert the device’s ability to transmit torque to a greater extent,and better exert the advantages of MRF.A magnetically conductive column structure is designed to interfere with the flow field of the MRF in the work area,and to increase the magnetic field strength in the work area.By interfering with the flow field,the phenomenon of solid-liquid separation caused by centrifugation is reduced.The magnetic circuit design of the new MRTD is performed,and the magnetic field simulation and flow field simulation analysis are performed.Based on the theoretical analysis of the structure of the magnetically conductive column.Establish the mathematical model of MRTD magnetic pole,and the theoretical analysis of the MRF can provide the size of the transmission torque and the factors that affect the transmission torque,through the structural analysis of MRTD,determine the size parameters of each part,and establish a complete set of MRTD design and manufacturing methods.The experimental tests were carried out to test the transmission characteristics of the new MRTD.Mainly to test its no-load characteristics,static load characteristics,speed regulation characteristics and torque regulation characteristics.Experimental results show that the transmission device designed in this subject can continuously and stably transmit torque under no-load conditions.With the increase of the input speed of the motor,when there is a load on the output,the output can gradually change from fixed to almost synchronous rotation,showing a certain linear relationship,and the increase of the magnetic field strength will effectively adjust the output speed.When the magnetic field strength is constant,the output torque of the entire transmission device increases as the input speed of the motor increases,the output torque is continuous and stable,and has a better transmission effect.The results obtained by this institute are mainly to provide some experimental basis for the industrial application of MRTD,and to provide a basis for the promotion of magnetorheological transmission technology. |
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