感压膜片预张力对电容薄膜真空规输出特性的影响

电容薄膜真空规中感压膜片在安装时通常须先施加预张力,再固定。为研究感压膜片预张力对电容薄膜真空规输出特性的影响,以现有电容薄膜真空规为对象,基于COMSOL Multiphysics软件,建立有限元模型,得到了不同预张力下输出电容的仿真解,并与理论计算结果进行了比较,分析了预张力对输出电容的影响。同时分析了真空规线性度、灵敏度随预张力的变化规律,并对感压膜片在最大负载情况下的强度进行了校核。结果表明:预张力对真空规的输出特性影响明显,输出电容随预张力的增大而减小,输出电容理论计算值与仿真值基本吻合;预张力越大,真空规线性度越好,但灵敏度越低;当感压膜片预张力为50 MPa时,真空规的线性度为7.3%,灵敏度为0.0433 pF/Pa,通过电路补偿后,可获得较好的线性度与灵敏度;感压膜片最大负载情况下的应力为95.5 MPa,能够满足工作要求。

Effect of the Pretension of the Pressure-sensitive Diaphragm on the Output Characteristics of the Capacitance Diaphragm Gauge

In the capacitance diaphragm gauge,the pressure-sensitive diaphragm usually needs to be pretensioned before installation,and then fixed.In order to study the effect of pressure-sensitive diaphragm pretension on the output characteristics of the capacitance diaphragm gauge,taking existing capacitance diaphragm gauges as object,a finite element model is established based on the COMSOL Multiphysics software,and the simulation solutions of the output capacitance under different pretensions are obtained,and compared with the theoretical calculation results,and the effect of the pretension on the output capacitance is analyzed.At the same time,the variation regularity of linearity and sensitivity of capacitance diaphragm gauge with pretension are analyzed,and the strength of the pressure-sensitive diaphragm under the maximum load is checked.The results show that the pretension has a significant effect on the output characteristics of the capacitance diaphragm gauge.The output capacitance decreases with the increase of the pretension,the theoretical calculation value of output capacitance is basically consistent with the simulation value.The greater the pretension,the better the linearity of the capacitance diaphragm gauge,but the lower the sensitivity.When the pressure-sensitive diaphragm pretension is 50MPa,the linearity of capacitance diaphragm gauge is 7.3%,the sensitivity is 0.0433 pF/Pa,after the circuit compensation,the better linearity and sensitivity can be obtained.The stress of the pressure-sensitive diaphragm under the max-imum load is 95.5 MPa,which can meet the working requirements.