Micromechanical Inertial Latching Switch Design

MEMS provides the technical foundation for miniaturizing mechanical switches of fuse power. Based on MEMS technology, a micro mechanical inertial latching switch of fuze which can distinguish between normal launching acceleration pulse and accidental fall acceleration pulse is designed.Firstly, background and development of micro-mechanical latching switches are introduced. Function curves along with time axis, which are about normal launching acceleration pulse and accidental fall acceleration pulse of duty handling, are analyzed. Design specifications of switch:Length×width×height is5mm×5mm×1mm. Amplitude of normal launching acceleration pulse is3000g-10000g, and its pulse width is more than or equal to1ms. It makes switch latch. Amplitude of accidental fall acceleration pulse is10000g-15000g, and its pulse width ranges from100μs to300μs. Under accidental fall acceleration pulse, switch remains off. Switch should resist20000g-30000g overload. Structure of switch is integral, and power supply is stable. Working resistance of switch is less than1Ω.Secondly, mathematical and physical model of switch, which is consisted of distinguishing load mechanism of two degrees spring-mass system and latching mechanism of single degree spring-mass system, is established. According to the mathematical and physical model of switch, distinguishing mechanism and latching mechanism are designed. Simulation software verifies switch functions. Analysis shows that under normal launching acceleration, switch, whose maximum stress is less than the material tensile stress, finishes latching stably. And maximum on-resistance of switch is848.8mΩ. The stable connection time of switch depends on normal launching acceleration. Under accidental fall acceleration, switch whose maximum stress is less than the material yield strength keeps off. Switch can restore to its original position. Under high overload condition, tensile stress is less than the tensile stress and the switch is not destroyed. It meets the design requirements.Finally, process of switch is designed.