A planetary magnetorheological transmission was proposed to overcome the problems caused by shear thinning and solid-liquid separation of magnetorheological fluid (MRF) in this study. The planetary magnetorheological transmission device (MRTD) was designed and fabricated. The magnetic field and flow field of the MRF inside the planetary MRTD were simulated using finite element method. The results show that both the magnetic and flow fields are non-uniform complex fields. The shear rate of the MRF in the shearing region decreases significantly due to planetary motion of the planetary components, and the solid-liquid separation can be prevented by the cyclic stirring effect of the planetary components, so that the MRF to produce a more stable and higher external magnetic field response than that of simple shearing. The performances of planetary MRTD were tested on the self-made experimental system. The results show that the output torque of MRTD increases linearly with the excitation current within a certain range, thus the output torque can be adjusted by controlling the excitation current when the input speed is constant. The output speed of the MRTD remain zero when the excitation current is less than the threshold current, then the gradually increases as the excitation current continues to increase, eventually approaching the synchronous rotation. The planetary MRTD exhibits a much longer response time compared to simple shearing MRTD, with the response time of the unloading stage is longer than that of the loading stage.
 

Magnetorheological fluid,Magnetorheological transmission device,Planetary structure,Transmission charccteristics