Design and experiments of a permanent magnetic inertial miniature switch

A novel permanent magnetic miniature inertial switch with parallel beams is designed with utilizing the nonlinear characteristic of the permanent magnetic force. The dynamic model of the inertial switch, subjected to magnetic force, squeeze-film damping force, inertial force, elastic force and contact force, is established. The good threshold characteristic and high contact reliability are shown by the results of the dynamic simulation and experiments. The average threshold acceleration of the switch samples is 51.6 g, which is only 3.2 percents different from the designed value of 50.0 g. Meanwhile, the cut-off accelerations are 7.5 g, 9.0 g and 27.0 g, respectively. Thus, the feasibility of introducing permanent magnet in the design of the inertial switch is validated, and the switches are simple in structure. The inertial switches with different threshold can be fabricated by regulating the design factors.