Dynamic Simulation of the Two-Direction Micro-Electro-Mechanical System Inertial Switch

摘要

To sense the change of acceleration from two directions, a Micro-Electro-Mechanical System inertial switch with two sensitive directions is designed. The switch incorporates frame, inertia mass with a unique flexible box and four serpentine suspension springs which support the inertia mass suspending. The switch can sense the acceleration that is more than or equal to 1500 g in x direction and the 800 g in y direction. The dynamic modeling of the design is obtained using finite element method (FEM) in the commercial code ANSYS to confirm the gap between the inertia mass and the fixed electrode. The sensitivity is determined by response time and the reliability is determined by time of the inertia mass contacting with the fixed electrode. To verify the sensitivity and the reliability of the switch, the impact process is simulated. The response time and the contact time are achieved respectively under the triangle wave impulse with 1500 g peak value in x direction and the triangle wave impulse with 800 g peak value in y direction. The relationship between threshold acceleration and inertia mass thickness H of the micro-switch is investigated by finite element simulation. With the inertia mass thickness decreasing, the threshold of the switch will increase, and the response time of the inertial switch will decrease.