Effect of Circumferential Magnetic Field on Braking Performance of a Direct Vane Magnetorheological Fluid Retarder

The hydraulic retarder used in commercial vehicles can provide hydraulic damping to generate braking torque, reducing the pressure of the braking system on the slope section and increasing the safety. In this paper, the magnetorheological fluid with fast magnetic field reflection characteristics is used to increase the response speed of the hydraulic retarder, which can effectively reduce the response time of the hydraulic retarder. In this paper, the influence of the change of circumferential magnetic field on the braking torque of the magnetorheological fluid retarder is studied. This paper analyzed the internal flow characteristics and braking mechanism of the hydraulic retarder based on the traditional hydraulic retarder, established the mathematical model of the magnetorheological hydraulic retarder which based on the straight blade structure ,and studied the variation of the braking torque of the magnetorheological fluid retarder when the rotational speed changed under the condition of no magnetic field .Then based on the Bingham model, the relationship between the braking torque of the magnetorheological fluid retarder with the intensity of the circumferential magnetic field is analyzed under the condition of constant temperature and liquid filling rate. In this paper, the experiments are conducted to studied the variation of the braking torque when the rotational speed changed and the variation of the braking torque when the rotational speed changed. The traditional hydraulic retarder is used as a reference group in the experiment, and the braking performances of the traditional hydraulic retarder and magnetorheological fluid retarder are compared. The results show that the magnetorheological fluid retarder can provide more braking torque at the same speed.