Optimization Design And Braking Performance Analysis Of Rotary Magnetorheological Brake With Multi-fluid Flow Channels

Rotary magnetorheological(MR)brake is a kind of semi-active damping device which can effectively generate torque and dissipate motion energy.Compared with the linear MR damper,the rotary MR brake has many unique advantages such as compact design and low consumption of MR fluid,which can be better applied to the narrow working space.Rotary MR brake has wide application prospects in the engineering fields due to its easy to manufacture,maintenance and control,high reliability and durability.But the torque of rotary MR brake is too small to be applied to the situations where large braking torque is required.In this paper,in order to further improve output torque and torque density of rotary MR brake,the combination of rotating shaft and rotating sleeve and the combination of non-magnetic material and magnetic material are used to increase the number of fluid flow channels of the rotary MR brake,which can not only improve the braking torque performance,but also greatly reduce the axial size of the drum brake.The main research contents of this paper are as follows:1.A rotary MR brake with multi-fluid flow channels was designed,The fluid flow channel was divided into internal and external parts by setting the rotating sleeve.The magnetic flux was guided into the outside axial fluid flow channel by setting a non-magnetic material in the middle of the rotating sleeve which could improve the magnetic circuit structure greatly,and the effective damping gap of the brake was increased from two sections to four sections,the working area where the MR brake producing rheological effect was increased.The magnetic circuit was analyzed and calculated by analytical method according to the fundamental theorem of magnetic circuit,the effective fluid flow channels length and key parameters of the MR brake were calculated iteratively combined with the design conditions,and the strength was checked.The torque mathematical model was deduced based on Bingham model.The results show that the theoretical output brake torque of the designed magnetorheological brake satisfies the design requirements.2.The magnetic circuit of the rotary MR brake was simulated and optimized with EMAG and Design Opt moduel in ANSYS.The braking torque characteristics of the before and after optimization brake were compared and analyzed to fully verify the influence of the distribution of magnetic flux intensity by setting a non-magnetic material.The distribution of shear stress at the effective damping gap and the braking torque variation of rotary MR brake before and after optimization were observed under different applied current and rotational speed.The simulation results show that the optimized magnetorheological brake has a higher output torque.3.The rotary MR brake before and after optimization were prototyped and assembled,and the experimental test system was set up to test the performance of MR brake.The sensor signal acquisition system was designed to abtain rotational speed and braking torque values of the MR brake under different currents and speeds with Lab VIEW data acquisition software.The change of rotational speed and braking torque were analyzed and compared with the simulation results to verify the rationality of the optimized structure of the rotary MR brake.The experimental results show that the optimized brakes have better braking performance.