| The magnetorheological brake using the new intelligent material magnetorheological fluid as the working medium has been widely concerned because of its advantages of good controllability and rapid response.The research on large torque magnetorheological brakes is relatively little,and the temperature rise effect will reduce the mechanical properties of magnetorheological fluids under multiple braking.The water-cooling magnetorheological brake is presented in this paper.And its braking performance and heat dissipation characteristics are investigated by using theoretical calculation,simulation analysis and experimental confirmation,which can provide theoretical and experimental references for the follow-up research.The main research contents are as follows:1.A water-cooled magnetorheological brake is designed,which uses multi-disc structure to increase the working area of the brake and increase its output torque.The mathematical model of the torque of the water-cooling MRB is infered based on Bingham model.The mathematical model of transient temperature field of water-cooling magnetorheological brake was established,and the cooling structure was designed to solve the problem of temperature rise during operation.2.The electromagnetic field for the water-cooling magnetorheological brake was simulated by using Comsol software.The magnetic field distribution cloud diagram and magnetic field diagram of the brake were obtained by simulation,and the influence of different cooling channel distribution on the magnetic field at the brake working gap was verified.At the same time,the theoretical output torque of the brake under different current in the excitation coil is calculated based on the established torque mathematical model and the simulated magnetic field distribution results.And the change rule between the output torque and current is analyzed.The results show that the output torque of the designed water-cooling magnetorheological brake can reach 102.68 N·m,which meets the design requirements.3.The heat-flow coupling simulation of the brake was carried out by Comsol,and the internal transient temperature variation rule of the brake under different working modes was obtained by simulation,and the temperature variation characteristics of the magnetorheological fluid in the brake under different cooling conditions were analyzed.The heat-flow coupling of the brake is analyzed theoretically to explore the law of heat transfer in the brake.The simulation results show that the mean temperature and maximum temperature of Mr Fluid decrease by 23.34% and 19.61% when the cooling structure is running,and the coolant velocity has a significant effect on the heat dissipation after the end of the brake.4.The water-cooling magnetorheological brake was fabricated and the test platform was built.The temperature characteristics and braking performance of MRB were tested,and the experimental data was collectd with Labview platform.The no-load speed change,output braking torque,torque response time and temperature rise characteristics of the brake were studied.The experimental results show that the actual output torque of the brake reaches96.24 N·m,and the torque response time is fast.With the increase of the internal temperature of the brake,the output torque decreases gradually,but the reduction of the torque decreases obviously after the cooling structure works. |
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