Research on the Performance of Magnetorheological Fluid Auxiliary Braking Devices Thermal Management System Based on Flat Plate Heat Pipes

To prevent braking recession, heavy commercial vehicles are often equipped with fluid auxiliary braking devices, such as hydraulic retarder. Hydraulic retarder can convert the vehicle’s kinetic energy to the fluid heat energy, which can enormously alleviate the main brake’s workload. The traditional hydraulic retarder can provide enough braking torque but has a delay during the braking. In this paper, a new type of magnetorheological fluid (MR fluid) hydraulic retarder is introduced by replacing the traditional fluid with magnetorheological fluid because of its linear braking torque and quick response. By changing the magnetic field intensity, it is easier to control the braking torque than the traditional hydraulic retarder. The rise of magnetorheological fluid temperature during the braking period will reduce the hydraulic retarder’s performance. To research, the influence of temperature on the retarder’s braking torque, the model of MR fluid is established through the theory of one-dimensional flow theory of hydraulic retarders. In this paper, the braking torque of retarder is calculated based on the Bingham model. In order to get a higher performance, a cooling system of magnetorheological fluid hydraulic retarder is designed. In this study, flat plate heat pipes (FPHP) are used to manage the temperature of the retarder by optimizing the coupling relationship between the heat generation of the retarder and the FPHP. The change of the temperature and the optimal working temperature range of the retarder are also researched after adding the cooling system. Research shows that the temperature’s influence on the braking torque is non-linear when the retarder is working continuously. After adding the cooling system on retarder, the temperature when working is decreased by 5~8°C and the braking torque is also increased obviously. Used in commercial vehicles, it offers a new method for magnetorheological fluid hydraulic retarder thermal management in the future.