线圈水冷式电涡流缓速器磁热分析与试验

Electromagnetic Coupled Analysis and Experiment of Eddy Current Retarder With Water-cooled Coil for Heavy Trucks

我国山区卡车存在长时间下坡制动负荷大的问题,由于液力缓速器成本高和电涡流缓速器持续制动转矩热衰退严重,导致缓速器在卡车上推广缓慢.提出了一种线圈水冷式电涡流缓速器,将发热的缓速器定子和励磁线圈都设计为水冷结构,从而解决了电涡流缓速器长时间制动产生高温导致线圈励磁不稳定、制动转矩衰退等问题.采用电磁仿真的方法分析了缓速器装车前后的静态气隙磁通密度,计算了由于传动轴带来的漏磁磁通,并提出减少漏磁的方法,漏磁比例由21.2%降至3.4%.通过有限元法求解了缓速器定子和励磁线圈的温度场分布,并结合瞬态电磁场解出定子温度场、线圈温度场耦合下的缓速器制动转矩.针对18 t卡车试制了安装在后桥上的线圈水冷式电涡流缓速器样机并进行了台架试验与车载试验,台架试验结果表明缓速器转矩的试验值与仿真值吻合较好,误差在9.7%内,车辆满载试验时,最大减速度为0.61 m/s^(2).

In China’s mountainous areas,trucks have long-term downhill braking load problems.Due to the high cost of the hydraulic retarder and the severe thermal decay of the eddy current retarder when continuous braking,the retarder is promoted on trucks slowly.A new eddy current retarder that has a water-cooled coil was proposed in this paper.To solve the problem of unstable coil excitation due to high temperature caused by long-term braking,the heat-generating stator and excitation coil of retarder were both designed as water-cooled structures.The electromagnetic simulation method was used to analyze the static air-gap magnetic flux density before and after the retarder was assembled.The magnetic flux leakage was caused by the drive shaft.A method of reducing the magnetic leakage was proposed.The magnetic leakage ratio dropped from 21.2%to 3.4%.The problem of temperature field distribution of the retarder stator and excitation coil was solved by the finite element method.Combining with the transient electromagnetic field,the retarder braking torque under the coupling of the stator temperature field and the coil temperature field was solved.A prototype of the coil water-cooled eddy current retarder assembled on the rear axle of an 18-ton truck and the bench test and the vehicle test were carried out.The bench test results show that the experimental value of the retarder torque is in good agreement with the simulation value,and the error is within 9.7%.When the vehicle is fully loaded,the maximum braking deceleration of the truck is 0.61 m/s^(2).