温度对不同预加张力作用下的电容式压力变送器测量精度影响

Influence of Temperature on Measurement Accuracy of Capacitive Pressure Transmitter Under Different Pre-tension

为提高电容式压力变送器测量精度,研究温度和中心测量膜片预加张力对其影响。采用流固耦合等效分析方法,以测量膜片位移为分析指标,通过DIC(digital image correlation)实验验证预加张力大小,分析20~70℃时,不同预加张力条件下测量膜片位移变化。结果表明:无预加张力时,温度与位移为二次曲线;有预加张力时,温度与位移为线性关系,其线性系数是一种灵敏度系数。位移相对于基准位移的位移偏移量ε随温度增加;预加张力增加,ε减小。给定预加张力下,温度与ε为线性关系,其系数为两个灵敏度系数之差,给定温度下,预加张力与ε是非线性关系,预加张力与灵敏度系数为幂函数关系。结果可为提高电容式压力变送器可靠性提供参考。

In order to improve the measurement accuracy of capacitive pressure transmitter,the effects of temperature and pre-tension of central measuring diaphragm on it were studied.Using the fluid structure coupling equivalent analysis method,taking the measurement of diaphragm displacement as the analysis index,the pre-tension was verified by DIC experiment,and the variation of diaphragm displacement under different pre-tension conditions was analyzed at 20~70℃.Results show that without pre-tension,the temperature and displacement were quadratic curves.When there is pre-tension,the relationship between temperature and displacement is linear,and its linear coefficient is a sensitivity coefficient.Displacement offset of displacement relative to reference displacement ε increases with the increase of temperature.Given the pre-tension,the relationship between temperature and ε is linear,and its coefficient is the difference between the two sensitivity coefficients.At a given temperature,the relationship between the pre-tension andεis nonlinear,and the relationship between pre-tension and sensitivity coefficient is a power function.The results can provide reference for improving the reliability of capacitive pressure transmitter.