液压缸用外置式磁感应位移传感器设计

Design of external magnetic induction displacement sensor for hydraulic cylinder

针对液压缸内置式位移传感器安装工艺复杂、检修困难的问题,利用隧道磁阻(TMR)元件设计了一款外置式磁感应位移传感器。首先,对传感器的构成、工作原理及信号电路进行了设计和说明,通过Ansoft Maxwell电磁仿真平台建立了传感器模型;然后,对永磁环运动时的磁场状态及磁阻元件的输出信号进行了分析,提出了通过多个磁阻元件有效线性工作区叠加来计算永磁环位移的方法,并研究了液压缸缸筒对计算方法的影响;最后,利用实验装置对传感器的各项性能指标进行了测试。研究结果表明:在不同缸筒磁导率和厚度下,磁阻元件有效线性工作区对应的位移区间长度相等,传感器可对不同缸筒材质与厚度的液压缸进行测量,磁阻元件实际输出曲线的线性度为2.39%,精度为0.16%,满足测量误差小于1 mm时4%的线性度要求,传感器分辨率为0.0083%,且其重复性较好,其设计是可行的。

Aiming at the complicated installation process and difficult maintenance of the displacement sensor built into the hydraulic cylinder,an external magnetic induction displacement sensor was designed using tunneling magneto resistive(TMR)elements.Firstly,the composition,working principle and signal circuit of the sensor were introduced.Then,based on Ansoft Maxwell electromagnetic simulation platform,the sensor model was established.The magnetic field state of the permanent magnet ring and the output signal of the magneto resistive elements were analyzed.The method of calculating the displacement of the permanent magnet ring by superposition of effective linear working areas of multiple magneto resistive elements was put forward,and the influence of the hydraulic cylinder on the calculation method was studied.Finally,the performance indicators of the sensor were tested by the experimental device.The results show that under different cylinder permeability and thickness,the length of displacement interval corresponding to the effective linear working area of magnetoresistance element is equal,and the sensor can measure hydraulic cylinders with different cylinder materials and thicknesses.It is found that the linearity of the actual output curve of the magneto resistive element is 2.39%,and the accuracy is 0.16%,which meets the linearity requirement of 4%when the measurement error is less than 1 mm,the sensor resolution is 0.0083%,and the repeatability is good.The feasibility of the design is verified.