Pressure based fluid gauging system

• US 6,434,494 B1
• Filed: 03/30/1999
• Issued: 08/13/2002
• Est. Priority Date: 03/30/1999
• Status: Expired due to Term

• Current Assignee: Simmonds Precision Products, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Simmonds Precision Products, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Forsythe, Arthur M. Jr., Maurice, Lisa Brackenbury
• Primary Examiner(s): Hilten, John S.
• Assistant Examiner(s): Bui, Bryan
• Application Number:
  US09/280,525
• Time in Patent Office: 1,232 Days
• Field of Search: 702/47, 702/50, 702/55, 702/138, 702/155, 702/156, 702/23-25, 733/14, 738/614.2, 738/614.6
• US Class Current: 702/50
• CPC Class Codes: G01F 23/14 by measurement of pressure
• CPC Class Codes: G01F 23/80 Arrangements for signal processing

Abstract

A method for gauging liquid in a container, the method comprising: a) assigning a local three axis coordinate system for the container; b) dividing the container into a plurality of regular volumes; c) disposing a first pressure sensor at a predetermined coordinate proximate the bottom surface of the container, with the pressure sensor producing an output related to detected fluid pressure at the predetermined coordinate; d) assigning to each of the volumes a corresponding volume location coordinate; e) numerically determining, for each of the regular volumes, a corresponding liquid mass value therein based on a relationship between the detected pressure at the predetermined coordinate and a calculated pressure at each of the volume location coordinates; and f) summing all of the numerically determined liquid mass values corresponding to the regular volumes to produce a total fluid mass for the container.

Claims

1. A method of gauging liquid in a container, the method comprising:

a) assigning a local three axis coordinate system for the container;

b) dividing the container into a plurality of regular columnar volumes, each of said regular columnar volumes defined by a predetermined cross-sectional area that is not dependent individually on the geometry of the container;

c) disposing a first pressure sensor at a predetermined coordinate proximate the bottom surface of the container, with said first pressure sensor producing an output related to detected fluid pressure at said predetermined coordinate;

d) assigning to each of said regular columnar volumes a corresponding volume location coordinate;

e) numerically determining, for each of said regular columnar volumes, a corresponding liquid mass value therein based on a relationship of said corresponding predetermined cross-sectional area and a calculated pressure at said volume location coordinate thereof based on said detected pressure at said predetermined coordinate; and

f) summing all of said numerically determined liquid mass values corresponding to said regular columnar volumes to produce a total fluid mass value for the container.

2. The method of claim 1 wherein the container is subdivided into a plurality of small columns each aligned with an axis coincident with a predetermined acceleration axis.

3. The method of claim 2 wherein said predetermined acceleration axis coincides with the gravitational axis.

4. The method of claim 1 comprising the steps of determining a container acceleration component that is normal to the liquid surface, detecting pitch and roll rotations of the container, and using said acceleration, pitch and roll data for the numerical determination of pressure in each of said regular volumes.

5. The method of claim 1 wherein said relationship is generally defined by a linear pressure equation:

6. The method of claim 5 wherein density is an assigned value.

7. The method of claim 1 comprising the step of detecting fluid pressure at a second predetermined coordinate using a second pressure sensor that is spaced from said first pressure sensor relative to the liquid surface.

8. The method of claim 7 wherein density of the liquid in the container is calculated based on pressure data from said first and second sensors.

9. The method of claim 7 comprising the steps of detecting fluid pressure at a third predetermined coordinate using a third pressure sensor, and numerically determining a liquid mass value for each said regular volume based on a pressure equation defining 1) a linear relationship between pressure at each sensor and a calculated pressure for each regular volume, and 2) a second order relationship between pressure at each said regular volume and deflection of the container about a deflection axis.

10. The method of claim 9 wherein the pressure equation is:

11. The method of claim 10 wherein in the constants are calculated values based on the pressure sensor data.

12. A method for gauging liquid in a container, the method comprising:

a) assigning a local three axis coordinate system for the container;

b) dividing the container into a plurality of regular volumes;

c) disposing a first pressure sensor at a predetermined coordinate proximate the bottom surface of the container, with said first pressure sensor producing an output related to detected fluid pressure at said predetermined coordinate;

d) assigning to each of said regular volumes a corresponding volume location coordinate;

e) numerically determining, for each of said regular volumes, a corresponding liquid mass value therein based on a relationship between said detected pressure at said predetermined coordinate and a calculated pressure at each of said volume location coordinates, said relationship being generally defined by a linear pressure equation;

13. A method for gauging liquid in a container, the method comprising:

a) assigning a local three axis coordinate system for the container;

b) dividing the container into a plurality of regular volumes;

c) disposing at least three pressure sensors at at least three corresponding predetermined coordinates proximate the bottom surface of the container, with said at least three pressure sensors producing corresponding outputs related to detected fluid pressures at said at least three corresponding predetermined coordinates;

d) assigning to each of said regular volumes a corresponding volume location coordinate;

e) numerically determining, for each of said regular volumes, a corresponding liquid mass value therein based on a pressure equation defining;

     1) a linear relationship between pressure at each sensor and a calculated pressure for each regular volume, and

     2) a second order relationship between pressure at each said regular volume and deflection of the container about a deflection axis; and

f) summing all of said numerically determined liquid mass values corresponding to said regular volumes to produce a total fluid mass value for the container.

14. The method of claim 13 wherein density of the liquid in the container is calculated based on pressure data from at least two pressure sensors of the at least three pressure sensors.

15. The method of claim 13 wherein the pressure equation is:

16. The method of claim 15 wherein in the constants are calculated values based on the pressure sensor data.