Abstract: 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.

Key words: micro-electro-mechanical system(MEMS), micro acceleration switch, permanent magnetic force, gas damp, surface contact force