School of Mechanical Engineering , Taiyuan University of Science and Technology

针对煤矿机械中摩擦限矩器过载保护装置存在的寿命短、可靠性差的现状,提出一种由永磁涡流传动机构与摩擦离合器组合而成的新型的大功率快速分断式永磁涡流摩擦限矩器 (PMEFTL),其工作原理是:永磁涡流传动机构中磁体盘与导体盘之间的静态磁场引力对摩擦离合器的摩擦片施加轴向压力,形成摩擦限矩器的扭矩传输,借助过载瞬间主从摩擦片的相对滑差控制导体盘和磁体盘间轴向斥力,实现摩擦片脱离并快速切断传动系统。首先建立了 PMEFTL 的涡流磁场数学描述及其有限元模型,基于瞬态磁场分析研究了 PMEFTL 中永磁涡流机构产生轴向力的机制,提出了PMEFTL 的轴向力的麦克斯韦张量形式及摩擦限矩器转矩计算方程,表明永磁涡流机构的总轴向力由背铁轴向力和导体盘轴向力合成,随着滑差增大,背铁轴向力总是表现为引力并逐渐减小,导体盘轴向力总是表现为斥力,并逐渐增大,总轴向力则由引力逐渐变为斥力,并存在静态引力点和脱离转速点 2 个特征点。PMEFTL 的传递力矩与总轴向力成正比,过载打滑前,传递力矩等于摩擦副静摩擦力,过载打滑后,传递力矩由摩擦力矩和电磁力矩组成。其次基于三维有限元方法研究了PMEFTL 轴向力−滑差特性的影响因素,得出提高永磁体的厚度和占空比、增加导体齿槽数、减小导体齿槽占空比等都可以提升静态引力,进而提高 PMEFTL 的传动能力;脱离转速点与轴向引力和轴向斥力的相对关系有关,在静态引力确定的前提下,调节导体齿槽占空比、导体齿槽数可以调节脱离转速点。最后对 375 kW 的矿用 PMEFTL 的永磁体的厚度、占空比和极数与导体的占空比和槽数等设计参数进行优化,与初选参数相比,优化后静态引力提高 90%,摩擦副对数减少近 1 倍。PMEFTL 在煤矿机械的应用将有效提高传动系统的可靠性和使用寿命,减少相应的停机维修工作,提高生产效率。

In view of the current situation of short life and poor reliability of the overload protection device of friction moment limiter incoal mine machinery, a new high-power fast breaking permanent magnet eddy current friction Moment limiter (PMEFTL) is proposed,which is composed of permanent magnet eddy current transmission mechanism and friction clutch. Its working principle is as follows: Themagnet static magnetic attraction of permanent magnet eddy current drive mechanism between the plate and the conductor plate exerts axial pressure on friction clutch friction plate, forming friction limit of torque transmission torque, with the aid of instant overload masterslave friction plate relative slip control of axial repulsion between conductor plate and the magnet plate, friction plate from and quickly cutoff the transmission system. Firstly, the eddy current magnetic field mathematical description and finite element model of PMEFTL are established. Based on transient magnetic field analysis, the axial force generation mechanism of permanent magnet eddy current mechanismin PMEFTL is studied, and the axial force maxwell tensor form of PMEFTL and the torque calculation equation of friction torque limit areproposed. The results show that the total axial force of the permanent magnet eddy current mechanism is composed of the axial force of theback iron and that of the conductor disk, along with the increase of slip, back iron axial force is always characterized by gravity and gradually reduce, conductor plate of axial force is always characterized by repulsion, and gradually increase, the total axial force is gradually byattraction into a repulsive force, and static attraction point and disengage speed point two feature points. The transmitted torque ofPMEFTL is proportional to the total axial force. Before overload skidding, the transmitted torque is equal to the static friction force of thefriction pair; after overload skidding, the transmitted torque is composed of friction torque and electromagnetic torque. Secondly, the influencing factors of axial force slip characteristics of PMEFTL are studied based on three-dimensional finite element method. It is concludedthat increasing the thickness and duty cycle of permanent magnet, increasing the number of conductor grooves, and decreasing the dutycycle of conductor grooves can improve the static attraction and improve the transmission ability of PMEFTL. The detachment speed pointis related to the relative relationship between axial attraction and axial repulsion force. On the premise that static attraction is determined,the detachment speed point can be adjusted by adjusting the duty cycle of conductor cogs and the number of conductor cogs. Finally, thedesign parameters of the thickness, duty cycle, poles of the permanent magnet and the duty cycle and the number of slots of conductorplate of 375kW PMEFTL are optimized. Compared with the primary parameters, the static attraction is increased by 90% and the amountof friction pairs is reduced by nearly one time after optimization. The application of PMEFTL in coal mine machinery will effectively improve the reliability and service life of the transmission system, reduce the corresponding downtime and maintenance work, and improvethe production efficiency

国家自然科学基金资助项目(52075355)

王誉廷, 张宏. 新型大功率分断式永磁涡流摩擦限矩器的轴向力-滑差特性研究[J]. 煤炭科学技术, 2023, 51(4): 198-208.

WANG Yuting, ZHANG Hong. Research on the axial force-slip characteristics of permanent magnetic eddy current Frictional torquelimiter[J]. Coal Science and Technology, 2023, 51(4): 198-208.