Research on electromagnetic relay's dynamic characteristics disturbed by uniform static magnetic field

Electromagnetic relay is a widely used apparatus which usually works in a magnetic disturbance environment. To evaluate its electromagnetic compatibility (EMC) in a static magnetic field, dynamic characteristics of a clapper relay in a uniform static magnetic field situation based on the finite element method (FEM) is studied. Influences of the magnetic field on dynamic parameters (delay time, pick-up time, end pressure, and final velocity) as well as a situation in which the relay cannot function normally are analyzed. Simulation reveals that the external magnetic field which weakens the relay’s air-gap field has a greater influence on the relay’s dynamic parameters than the one strengthening the field. The validity of the simulation is verified by measured results of coil current and armature displacement.

EHD喷墨打印制备微热板气敏材料的研究

采用静电流体动力学(EHD)喷墨打印技术在微热板上沉积了气敏材料。将纳米气敏材料分散到溶剂中制备出墨水,研究了墨水材料、打印距离和针头尺寸等参数对起始电压的影响,实验结果与理论估算相一致。在制备微热板气体传感器的过程中,利用计算机控制三坐标平移台移动实现微热板与打印点的对准。采用外径为300μm、内径为180μm的针头,调节打印距离和电压,实现了气敏材料在微热板上的定位微滴打印。EHD喷墨微滴打印过程稳定,无针头堵塞现象,液滴直径约65μm,满足微热板打印需求。制备的气体传感器对甲醛表现出良好的气敏响应。