汽车磁流变液制动器温度特性仿真与试验研究

Simulation and Experimental Study on Temperature Characteristics of Magnetorheological Fluid Brake for Vehicles

针对磁流变液制动器工作时内部热量聚集造成其制动性能下降问题,采用仿真分析与试验验证相结合的方法对其温度特性进行研究。首先分析计算磁流变液制动器的热量来源和生热率,在此基础上建立其温度场数学模型;其次分别针对汽车正常制动、紧急制动和频繁间隙制动等三种不同制动工况,进行磁流变液制动器的瞬态温度场仿真分析;最后搭建汽车磁流变液制动器试验平台开展输出制动力、制动性能和温度特性的试验研究。结果表明:在相同线圈电流下,磁流变液制动器表现出良好的恒减速度制动特性;不同制动工况下一个制动周期内工作间隙处的温度均呈现先迅速增大后逐渐降低的变化过程,并且制动初速度和线圈电流越大,温升幅度和速率均越大;整个制动周期内测点处温度的试验值与仿真值在数值和趋势上较为吻合,表明所建立的温度场仿真模型能够较好地反映磁流变液制动器实际制动过程的温度特性。

In view of the problem that the braking performance is decreased due to the heat accumulation in the braking process of the magnetorheological fluid brake(MRB),simulation analysis and experimental evaluation of temperature characteristics of MRB are performed.Based on the analysis and calculation of the heat source and heat generation rate of MRB,a mathematical model for the temperature field is established.Then,aiming at three different braking conditions for vehicles:normal braking,emergency braking and frequency interval braking,the transient temperature field of MRB is simulated and analyzed.Finally,an experimental platform is developed and several braking tests are carried out to evaluate the output braking torque,the braking performance and the temperature characteristic of MRB.Results show that the MRB exhibits a good constant deceleration braking property under a same coil current.During a braking period,the temperatures at the working gap first increase and then decrease under various conditions.Test results and simulation values for the temperature at the measuring point are in good agreement,which indicates that the established temperature simulation model can reflect quite well the actual temperature characteristic of the MRB.