Capacitive pressure transmitter
First Claim
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1. A capacitive pressure transmitter comprising:
- a capacitive pressure sensor including;
a sensor body defining a chamber therein, the sensor body having a plurality of sensor inlets in fluidic communication with the chamber;
a conductive deflectable diaphragm disposed in the chamber;
at least one capacitive plate disposed in the chamber relative to the diaphragm such that diaphragm deflection generates a change in capacitance between the at least one plate and the diaphragm; and
a non-conductive layer interposed between the at least one plate and the diaphragm; and
a process media inlet operably coupled to one of the plurality of sensor inlets and adapted to couple to a source of process media to bring the process media into direct contact with the measuring diaphragm;
a second transmitter inlet operably coupled to the other of the plurality of sensor inlets;
sensor circuitry coupled to the capacitive pressure sensor to generate a sensor signal based upon the capacitance of the capacitive pressure sensor; and
transmitter circuitry coupled to the sensor circuitry to transmit information relative to the sensor signal over a process communication loop.
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Abstract
A capacitive pressure transmitter is provided. In one aspect, the transmitter includes a capacitive pressure sensor coupled directly to the measured media without any intervening fluid isolation. A filter is preferably used to keep particulates from reaching the measuring diaphragm. In another aspect, a capacitive pressure transmitter is provided with at least one self-contained isolator interposed between a process connection and the capacitive pressure sensor. In both aspects, the capacitive pressure transmitter is relatively small and preferably constructed from materials that facilitate low-cost manufacture.
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Citations
10 Claims
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1. A capacitive pressure transmitter comprising:
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a capacitive pressure sensor including;
a sensor body defining a chamber therein, the sensor body having a plurality of sensor inlets in fluidic communication with the chamber;
a conductive deflectable diaphragm disposed in the chamber;
at least one capacitive plate disposed in the chamber relative to the diaphragm such that diaphragm deflection generates a change in capacitance between the at least one plate and the diaphragm; and
a non-conductive layer interposed between the at least one plate and the diaphragm; and
a process media inlet operably coupled to one of the plurality of sensor inlets and adapted to couple to a source of process media to bring the process media into direct contact with the measuring diaphragm;
a second transmitter inlet operably coupled to the other of the plurality of sensor inlets;
sensor circuitry coupled to the capacitive pressure sensor to generate a sensor signal based upon the capacitance of the capacitive pressure sensor; and
transmitter circuitry coupled to the sensor circuitry to transmit information relative to the sensor signal over a process communication loop. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A capacitive pressure transmitter comprising:
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a capacitive pressure sensor having a first and second sensor inlets, wherein each inlet is fluidically coupled to a side of a conductive deflectable measuring diaphragm;
a self-contained isolator having a process fluid inlet, and an isolator fluid outlet operably coupled to the first sensor inlet, the self-contained isolator also having an isolator diaphragm disposed to fluidically isolate the process fluid inlet from the isolator fluid outlet while providing a pressure at the isolator fluid outlet related to a pressure at the process fluid inlet;
a second transmitter inlet operably coupled to the second sensor inlet;
sensor circuitry coupled to the capacitive pressure sensor to generate a sensor signal based upon the capacitance of the capacitive pressure sensor; and
transmitter circuitry coupled to the sensor circuitry to transmit information relative to the sensor signal over a process communication loop. - View Dependent Claims (9, 10)
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Specification