Differential pressure sensor

Abstract

The invention provides a differential pressure sensor, which comprises a base, a central diaphragm, a measuring capacitance plate and a reference capacitance plate, wherein the central diaphragm divides a cavity into a first measuring chamber and a second measuring chamber, and the first measuring chamber and the second measuring chamber are respectively communicated with a first channel hole and a second channel hole; the first measuring chamber and the second measuring chamber are filled with an insulating medium; the measuring capacitor plate and the reference capacitor plate are in insulated connection; the measuring capacitor plates are arranged on the two sides of the central diaphragm and close to the central area of the central diaphragm and form measuring capacitors, and the number of the measuring capacitors is not less than two; the reference capacitor plates are arranged on the two sides of the central diaphragm and far away from the central area of the central diaphragm and form reference capacitors, and the number of the reference capacitors is not less than two. According to the invention, the reference capacitor is added, and the reference capacitor is arranged at the position far away from the central area of the central diaphragm, so that measurement errors caused by temperature change and static pressure change can be basically eliminated.

Description

technical field [0001] The present invention relates to the field of sensor technology, in particular, to a differential pressure sensor. Background technique [0002] Refer to the accompanying drawings in the manual image 3 , the metal capacitive sensor is generally two capacitors formed by two polar plates and an intermediate isolation diaphragm. In the case of pressure changes, the polar plates of the two capacitors will have corresponding deformation, so that the output capacitance value will change. This The change has a certain functional relationship with the pressure, but when the temperature changes or the static pressure changes, the metal structure of the capacitive sensor and the filling fluid between the plates will expand and contract, which will lead to capacitance value, The functional relationship among pressure value, temperature value, and static pressure value becomes complicated, and the measurement accuracy of pressure will decrease. [0003] Among th...

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Problems solved by technology

[0002] Refer to the accompanying drawings in the manual image 3 , the metal capacitive sensor is generally two capacitors formed by two polar plates and an intermediate isolation diaphragm. In the case of pressure changes, the polar plates of the two capacitors will have corresponding deformation, so that the output capacitance value will change. This The change has a certain functional relationship with the pressure, but when the temperature changes or the static pressure changes, the metal structure of the capacitive sensor and the filling fluid between the plates will expand and contract, which will lead to capacitance value, The functional relationship between pressure value, temperature value and static pressure value becomes complicated, and the measurement accuracy of pressure will decrease

[0003] Among them, the reason why the temperature factor leads to poor measurement accuracy is that under the premise of the same pressure at different temperatures, the plate deformation of the capacitor is affected by the temperature, that is to say, the capacitance value changes are inconsistent

[0004] The reason for the poor measurement accuracy caused by the static pressure factor is: there is a filling liquid inside the metal capacitive sensor, and the filling liquid will expand or compress with the change of static pressure and temperature, resulting in a change in the capacitance value, thereby affecting the measurement accuracy;

[0005] In the existing technology, the solution to the poor measurement accuracy caused by temperature factors requires a 24-hour temperature compensation test in a high and low temperature box, and there is no solution to the problem of poor measurement accuracy caused by static pressure

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