Pressure compensated differential pressure sensor and method
AssigneeRosemount Inc.
InventorGerald R. Cucci
Life of this patent
Estimating the term…
Abstract
A differential pressure sensor senses a difference in pressure between a first input (low) pressure or "reference pressure" and a second input (high) pressure and provides a differential sensor signal representative of the difference in pressure. The reference pressure is sensed by a reference pressure sensor which provides a reference signal representative of the reference pressure. The differential sensor signal and the reference signal are provided to a correction circuit. The correction circuit, which is preferably a digital computer, adjusts the reference signal and provides an improved output signal as a function of the differential sensor signal and the adjusted reference signal.
Claims38
Apparatus for sensing a difference in pressure between a first pressure and a second pressure and providing an output signal representative of the difference in pressure, the apparatus comprising:
- differential pressure sensing means for providing a differential sensor signal representative of the difference in pressure between the first and second pressures;
- reference pressure sensing means for providing a reference sensor signal representative of the first pressure;
- memory storage means for providing correction data for known errors in the reference sensor signal and the differential sensor signal;
- and
- correcting means for providing the output signal as a function of the reference sensor signal, the differential sensor signal and the correction data, the output signal being more representative of the difference in pressure than is the differential sensor signal as a result of correction for known errors in both the reference sensor signal and the differential sensor signal.
A method of determining a difference in pressure between a first pressure and a second pressure and providing an output signal representative of the difference comprising the steps of:
- sensing the difference in pressure between the first and second pressures;
- providing a differential signal representative of the sensed difference in pressure;
- sensing the first pressure;
- providing a reference signal representative of the sensed first pressure;
- calculating a corrected differential pressure value as a function of the differential signal, the reference signal and previously stored correction values which provide corrections for known correctable errors in the differential signal and the reference signal;
- and
- providing the output signal as a function of the corrected differential pressure value.
A method of determining a difference in pressure at variable temperatures between a first pressure and a second pressure and providing an output signal representative of the difference in pressure comprising the steps of:
- sensing the difference in pressure;
- providing a differential signal representative of the sensed difference in pressure;
- sensing the first pressure;
- providing a reference signal representative of the sensed first pressure;
- sensing the temperature;
- providing a temperature signal representative of the sensed temperature;
- adjusting the temperature signal as a function of the temperature signal and a first set of previously stored correction values;
- adjusting the reference signal as a function of the adjusted temperature signal, the reference signal and a second set of previously stored correction values;
- and
- providing the output signal as a function of the adjusted temperature signal, the adjusted reference signal, the differential signal and a third set of previously stored correction values.
A two wire differential pressure sensing apparatus having two terminals for connection to two wires from a series connected source of DC voltage and a load through which a DC current of variable magnitude flows, the DC current providing sole energization for the apparatus, the apparatus comprising:
- differential pressure sensor means for providing a differential sensor signal which is a function of a difference in pressure between first and second pressures;
- reference pressure sensor means for providing a reference sensor signal which is a function of the first pressure;
- temperature sensor means for providing a temperature sensor signal which is representative of temperature of the apparatus;
- memory means for storing correction data uniquely associated with the differential pressure sensor means, the reference pressure sensor means and the temperature sensor means for correcting known correctable errors in the differential sensor signal, the reference sensor signal and the temperature sensor signal;
- digital computer means for computing a corrected differential pressure value based upon the differential sensor signal, the reference sensor signal, the temperature sensor signal and the correction data and for producing a control signal as a function of the corrected differential pressure value;
- and
- current control means coupled to the two terminals for controlling the magnitude of the DC current as a function of the control signal so that the magnitude of the DC current is representative of the corrected differential pressure value.
Apparatus for sensing a difference in pressure between a first pressure and a second pressure and providing an output signal representative of the difference in pressure, the apparatus comprising:
- differential pressure sensor means for providing a differential sensor signal which is a function of the difference in pressure between the first and second pressures;
- reference pressure sensor means for providing a reference sensor signal which is a function of the first pressure;
- memory storage means for providing correction data for reference sensor signal nonlinearities, differential sensor signal nonlinearities, and effects of variations of the reference sensor signal on the differential sensor signal;
- and
- correcting means for providing the output signal as a function of the reference sensor signal, the differential sensor signal and the correction data, the output signal being more representative of the difference in pressure than is the differential sensor signal as a result of correction for the reference sensor signal nonlinearities, the differential sensor signal nonlinearities, and the effects of variation of the reference sensor signal on the differential sensor signal.
Apparatus for sensing a difference in pressure between a first pressure and a second pressure and providing a corrected differential pressure value representative of the difference in pressure, the apparatus comprising:
- differential pressure sensor means for providing a differential sensor signal which is a function of the difference in pressure between the first and second pressures;
- reference pressure sensor means for providing a reference sensor signal which is a function of the first pressure;
- memory storage means for providing correction data for reference sensor signal nonlinearities, differential sensor signal nonlinearities, and effects of variations of the reference sensor signal on the differential sensor signal;
- and
- means for calculating the corrected differential pressure value based upon a predetermined formula which includes the reference sensor signal, the differential sensor signal and the correction data, the formula providing correction for the reference sensor signal nonlinearities, the differential sensor signal nonlinearities, and the effects of variation of the reference sensor signal on the differential sensor signal.
A method of determining a difference in pressure between a first pressure and a second pressure comprising the steps of:
- sensing the difference in pressure between the first and second pressures;
- providing a differential signal value representative of the sensed difference in pressure;
- sensing the first pressure;
- providing a reference signal value representative of the sensed first pressure;
- calculating a corrected differential pressure value based upon a formula which includes the differential signal value, the reference signal value and previously stored correction values representing corrections for known correctable errors in the differential signal value and the reference signal value;
- and
- providing the output signal as a function of the corrected differential pressure value.
A method of determining a difference in pressure at variable temperatures between a first pressure and a second pressure and providing an output signal representative of the difference in pressure comprising the steps of:
- sensing the difference in pressure;
- providing a differential signal value representative of the sensed difference in pressure;
- sensing the first pressure;
- providing a reference signal value representative of the second first pressure;
- sensing the temperature;
- providing a temperature signal value representative of the sensed temperature;
- calculating a corrected differential pressure value using a formula which simultaneously adjusts the differential signal value, the reference signal value, and the temperature signal value based upon a set of previously stored correction values;
- and
- providing the output signal as a function of the corrected differential pressure value.
Dependencies are inferred from the claim text.