混合励磁式电涡流制退机电磁场与阻力特性分析

Analysis of Electromagnetic Field and Resistance Characteristicsof Hybrid Excitation Eddy Current Braking Machine

电涡流制退机具有无液体泄漏、无需密封、阻力稳定的优势。与目前应用较多的永磁式电涡流制退机相比,混合励磁式电涡流制退机采用线圈替代了一部分永磁体,对阻力特性的调节效果更好。对比了混合励磁式电涡流制退机2种可能的结构形式,然后根据磁路分析与初步计算选择出具有更好阻力性能的结构。针对该结构,利用等效磁路法计算气隙磁场,采用子域模型考虑感生涡流影响,建立了求解混合励磁式电涡流制退机阻力值的等效子域模型。根据某口径火炮反后坐要求,确定了制退机的主要尺寸参数,完成了混合励磁式电涡流制退机结构参数的前期设计,并通过数值计算对解析计算结果进行了验证。接着,针对某口径火炮发射时的工况建立仿真模型,以炮膛合力曲线和复进机力的后坐行程函数曲线作为条件输入,分析强冲击载荷下混合励磁式电涡流制退机的电磁阻尼力、后坐位移和后坐速度规律。最后,分析了不同气隙宽度与内筒的电导率对电磁阻尼力的影响,结果表明气隙宽度越小电磁阻尼力越大,同时过大的内筒电导率会导致电磁阻尼力呈现“马鞍”型。本文研究可为混合励磁式电涡流制退机的工程化应用提供理论基础。

The eddy current braking machines have the advantages of no liquid leakage,no sealing required,and stable resistance.Compared with the more widely used permanent magnet eddy current braking machine,hybrid excitation eddy current braking machine replaces part of the permanent magnet with a coil an achieves better resistance characteristics.In this paper,two possible structure of hybrid excitation eddy current braking machines was compared.Based on magnetic circuit analysis and preliminary calculations,the structure with better resistance performance was selected.Equivalent magnetic circuit method was utilized to calculate the air gap magnetic field and subdomain models were adopted to consider effects of induced eddy current.Then,an equivalent subdomain model was established for calculating the resistance value of hybrid excitation eddy current braking machines.According to the requirements of a certain caliber artillery recoil,the main dimensional parameters of the braking machine were determined,and the preliminary design of the structural parameters of hybrid excitation eddy current braking machines was obtained.The analytical calculation results were verified by numerical calculation.Based on the working conditions when a certain caliber artillery is fired,the chamber force curve and recoil stroke function curve of complex feed mechanism were adopted as input conditions.A simulation model was established to analyze the electromagnetic damping force,recoil displacement and recoil velocity of hybrid excitation eddy current braking machine under strong impact load.Finally,the influence of different air gap widths and inner cylinder conductivity on electromagnetic damping force is analyzed.The results show that the smaller the air gap width is,the larger the electromagnetic damping force is.Meanwhile,higher conductivity of the inner cylinder will lead to the electromagnetic damping force showing a“saddle”type.The research provides a theoretical basis for the engineering application of the hybrid excitation-type eddy-current braking machine.