Differential pressure sensor

Abstract

A differential pressure sensor comprises a housing having first and second inlets; a rod-shaped capacitive displacement sensor affixed to the housing in the interior thereof; a first electrode constituted by an end face of the displacement sensor; a second electrode constituted by a diaphragm extending generally parallel to and at a distance from the first electrode; a bellows affixed to the housing and the diaphragm along a circumference thereof; a first chamber defined within the housing and communicating with the first inlet; and a second chamber defined within the housing and communicating with the second inlet. The first and second chambers are separated fluid tight from one another. One of the faces of the diaphragm is exposed to the pressure of a first fluid admitted to the first chamber through the first inlet and the other face of the diaphragm is exposed to the pressure of a second fluid admitted to the second chamber through the second inlet. As a result, the diaphragm is displaced and the distance from the first electrode is varied as a function of the difference between the pressures of the first and second fluids to vary the capacitance of the capacitive displacement sensor.