Analysis of braking performance of a new type of multi-pole bearing bush type magnetorheological brake considering electromagnetic force squeezing

In response to the problems of low torque, long braking time, and magnetic saturation of magnetorheological fluid in magnetorheological braking devices, which make it impossible to continue increasing the braking torque of the device by increasing the current. Based on the squeezing strengthening effect, the electromagnetic force generated by the electrified coil is used to attract the bearing on the stator to generate squeezing force, a multi-pole bearing bush-type magnetorheological brake considering electromagnetic force squeezing is designed. Through the theory of magnetic domains, the magnetic circuit was analyzed, and a finite element model of the magnetic field of the brake was established, The magnetic flux intensity and electromagnetic force of the device were analyzed. By conducting an analysis on the magnetic field and electromagnetic force generated by the brake structure, we derived mathematical equations to quantify the braking torque and duration. Subsequently, an in-depth assessment of the braking performance was undertaken. The results show that considering the electromagnetic force squeezing, the braking torque increases from 37.69 to 75.97 N·m. The braking torque of the new magnetorheological fluid brake considering electromagnetic force squeezing is increased by 2.01 times, effectively improving the controllable range of braking torque. With an input torque of 15 N·m, the braking time of the device with squeezing strengthening is 0.46 s, compared to 0.93 s without squeezing, representing a 50% reduction in braking time. The electromagnetic attraction can change with the magnitude of the current, and the response speed of the device is faster, greatly reducing the difficulty of control. A larger squeezing force is achieved without additional power sources, enhancing energy utilization efficiency.