Structure Design And Analysis Of Dual - Threshold MEMS Universal Inertial Switch For Fuze

Modern warfare has changed from carpet-bombing to precision strikes and efficient mutilate. The traditional trigger fuze is difficult to adapt to modern warfare for the shortcoming of large volume, single target recognition and low reliability of large angle response. In order to make the trigger fuze smaller and more intelligent, a MEMS universal switch with two threshold is designed, which can make the naval gun Fuze distinguish the shock acceleration case by impacting water and impacting deck.The theoretical model of bi-threshold inertial switch is proposed and the relationship between spring mass system parameters and thresholds, response time, close time is analyzed by using this model. The structure of the switch is designed. The switch contain a spring-mass system and two groups of flexible electrode. The structure of center annular mass suspended by four S-shape springs is adopted as movable electrode and the flexible electrodes serve as fixed electrode. The flexible electrodes of the lower threshold are disposed outside the annular mass while the higher threshold electrodes are inside the annular massFinite element method is used to analysis the mode, threshold, response time, close time, load adaptability and ability to resist overload of the switch. The simulation results show that dispersion in radial of the low threshold is 430g-460g and the one of the high threshold is 700g-850g, the dispersion in axial directions of the low threshold is 360g～560g and the one of the high threshold is 700g-1000g. The contact time is 70μs under impact load with amplitude 450g and width 0.6ms while the contact time is 20μs under impact load with amplitude 900g and width 0.6ms.Processing scheme and machining process of the switch are designed. Principle that the proof mass colliding with two elastic electrodes, which have different gap to the proof mass, can be used to identify acceleration is verified by experiment.