永磁微加速度开关设计与仿真

Modeling and simulation of a micro magnetic acceleration switch

基于永磁铁磁力随位移的非线性变化特性,提出了一种新型磁力微加速度开关设计方案.建立了含有永磁力、气膜阻尼力、表面接触力、惯性力的开关系统动力学分析模型,给出了质量块在开关多种工作状态下的运动微分方程.对开关工作过程中质量块位置、永磁力、空气阻尼力、质量块与触点接触力等参数的变化规律进行了仿真,结果表明:该设计可以受控于加速度门限完成闭合-断开功能;微开关系统阻尼由质量块与封装外壳间隙厚度决定,为一变阻尼系统;开关闭合时电接触可靠性取决于质量块对触点的压力;开关闭合和截止所需的激励加速度门限值受永磁铁磁力和支撑梁刚度参数的控制.

According to the characteristic that the force between a permanent magnetic couple changes nonlinearly with the magnetic displacement, a novel micro acceleration-switch of permanent magnetic force is designed. The dynamic model for the micro switch including the permanent magnetic force, the gas damping force, the contact force and the inertia force is established. The motion differential equations for the mass in several work conditions are presented. The law of the variation of the mass position, the permanent magnetic force, the gas damp force, the contact force between the mass and the contactors in switch work condition is simulated. Results indicate that the micro switch is a damp-varying system and that the damp is determined by the gas between the mass and the encapsulation. The reliability of electrical contact depends on the pressure between the mass and the contactor. The acceleration threshold of the switch is controlled by such parameters as magnetic force and stiffness of the micro cantilever.