The Structure Design And Performance Analysis Of A Low Inertia Switch

The inertial switch is a precision inertial device that perceives inertial acceleration and completes switching mechanical action.It is widely used in airbags,transport systems,crash recorders,armed and firing systems.MEMS inertial switch is not only small,fast response,low energy consumption,able to capture the weak signal and easy integration,especially for automotive,ammunition special environment.At present,the inertial switch research is aimed at high threshold inertial switches,which can be used for acceleration monitoring in weapon explosion systems.This type of switch can respond quickly to the impact acceleration signal and complete the acceleration detection.These acceleration signals have the characteristics of short shock time and narrow excitation pulse width.The low-threshold inertial switch(1g-30g)responses to the quasi-static,almost zero frequency of the acceleration signal.The sensitive structure is characterized by a small spring stiffness and a large mass.This low spring stiffness and large-mass composite structure in the MEMS structure is not easy to realize.In addition,there are some high-frequency interference signals generated by shock or vibration in the low-threshold inertial switch operating environment.In the design,the "spring-mass" structure of the low-g inertial switch must have a lower natural frequency and appropriate damping conditions,so that the structure itself can achieve mechanical filtering.And it can reduce the vibration or shock and other interference signal response,to avoid inertia switch malfunction.The main research work is as follows:(1)The low-threshold inertial switch was designed with the spiral beam as the elastic element,and the static analysis model was established.The static analysis model was established,and the stiffness characteristics of the elastic element of the spiral beam were analyzed.The theory results are compared with the finite element(ANSYS)simulation results.The stiffness error is 8%.Under the 10 v voltage drive,the static closure threshold of the switch is 10.756 g.(2)A damping analysis model of low threshold inertial switch is established.The damping coefficient of the system is retrieved by experiment.The damping adjustment technique based on the design of mass block is put forward.(3)The dynamic model of the switch is established using the MATLAB programming language.Then the study on the dynamic characteristics of switch by numerical solution is carried out.The influence of the half-sine inertia excitation on the performance of the threshold,the response time and the turn-on time are analyzed and then we study the effect of the electrostatic force generated by the operating voltage on the switching performance parameter.On the basis of this,the response characteristics of the switch under the combined action of the electrostatic force generated by the working voltage and the damping force generated by the mass flow are analyzed.The anti-overload characteristics of the switch,the response characteristics of the switch under different excitation(excitation pulse width,excitation form)and the suitable working environment are analyzed.Finally,the influence of contact force on the response characteristics of the switch is analyzed.This paper lays the foundation for the design and analysis of low threshold inertial switch based on spiral beam structure.