电容式微加速度计的气膜阻尼分析

针对电容式微加速度计中的气膜阻尼问题,基于稀薄气体动力学理论和滑流修正的压膜雷诺方程,分析了敏感质量块在轴向运动中受到的气膜阻尼效应,得到了阻尼力和阻尼系数的简化解析解。研究结果表明,敏感质量块受到的气膜阻尼力不但与尺寸和速度有关,还与固体壁面的材质、表面粗糙度和光洁度等特性有关。通过实例分析给出了三种减小气膜阻尼的方法,指出动量协调系数是影响气膜阻尼(尤其是压膜阻尼)的关键因素之一。

Analysis on Gas Film Damping of Capacitive Micro Accelerometers

Based on the rarefied gas dynamics theory and the squeeze film Reynolds equation amended with slip flow boundary condition, the gas film damping effect on the sensitive proof mass, moving along its axial direction, is analyzed for capacitive micro accelerometers. Simplified analysis solutions are obtained for damping force and damping coefficient. It shows that gas film damping force has relations not only with the accelerometer dimensions and velocity of the sensitive proof mass, but also with the factors, such as solid wall material, surface roughness, smooth finish, and so on. Three methods have been proposed to decrease the gas film damping of capacitive micro accelerometers through sample analysis. Finally, it is pointed out that accomodation coefficient is an key factor for gas film damping, especially for squeezed film damping.