Wireless fluid level measuring system

• US 7,255,004 B2
• Filed: 09/12/2005
• Issued: 08/14/2007
• Est. Priority Date: 09/13/2004
• Status: Active Grant

• Current Assignee: The United States of America As Represented By The Secretary of Agriculture, United States Department Of Health And Human Services
• Original Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Inventors: Taylor, Bryant D., Woodard, Stanley E.
• Primary Examiner(s): Williams; Hezron
• Assistant Examiner(s): West; Paul M
• Application Number:
  US11/229,438
• Publication Number:
  US 20060053880A1
• Time in Patent Office: 701 Days
• Field of Search: 733/04.C
• US Class Current: 73/304.00C
• CPC Class Codes: G01F 23/263 by measuring variations in capacitance of capacitors
• CPC Class Codes: G01F 23/265 for discrete levels
• CPC Class Codes: G01F 23/266 measuring circuits therefor
• CPC Class Codes: G01F 23/268 mounting arrangements of probes
• CPC Class Codes: G01F 23/802 Particular electronic circuits for digital processing equipment

Abstract

A level-sensing probe positioned in a tank is divided into sections with each section including (i) a fluid-level capacitive sensor disposed along the length thereof, (ii) an inductor electrically coupled to the capacitive sensor, (iii) a sensor antenna positioned for inductive coupling to the inductor, and (iv) an electrical conductor coupled to the sensor antenna. An electrically non-conductive housing accessible from a position outside of the tank houses antennas arrayed in a pattern. Each antenna is electrically coupled to the electrical conductor from a corresponding one of the sections. A magnetic field response recorder has a measurement head with transceiving antennas arrayed therein to correspond to the pattern of the housing'"'"'s antennas. When a measurement is to be taken, the measurement head is mechanically coupled to the housing so that each housing antenna is substantially aligned with a specific one of the transceiving antennas.

Claims

1. A system for measuring a fluid level in a tank, comprising:

a level-sensing probe adapted to be positioned in a tank containing a fluid such that said probe substantially spans the height of the tank, said probe divided into a plurality of sections with each of said sections including (i) a fluid-level capacitive sensor disposed along the length thereof, (ii) an inductor electrically coupled to said capacitive sensor, (iii) a sensor antenna positioned for inductive coupling to said inductor, and (iv) an electrical conductor coupled to said sensor antenna;

an electrically non-conductive housing adapted to be accessible from a position outside of the tank;

a plurality of housing antennas arrayed in a pattern within said housing with each of said housing antennas electrically coupled to said electrical conductor from a corresponding one of said plurality of sections; and

a magnetic field response recorder having a measurement head with a plurality of transceiving antennas arrayed therein to correspond to said pattern of housing antennas, said measurement head including means for mechanically coupling said measurement head to said housing wherein each of said housing antennas is substantially aligned with a specific one of said transceiving antennas.

2. A system as in claim 1 wherein said capacitive sensor associated with at least one of said sections is defined by capacitor plates of varying width.

3. A system as in claim 1 wherein said capacitive sensor associated with at least one of said sections is defined by capacitor plates separated by a varying gap.

4. A system as in claim 1 wherein said pattern is two-dimensional.

5. A system as in claim 1 wherein the tank has an opening used for filling the tank with the fluid, and wherein said housing is adapted to fit and cover the opening.

6. A system as in claim 1 wherein said magnetic field response recorder is hand-held.

7. A system as in claim 1 wherein each said inductor is a spiral inductor.

8. A system as in claim 7 wherein each said spiral inductor is positioned approximately perpendicular to said capacitive sensor corresponding thereto.

9. A system as in claim 1 wherein each said sensor antenna is a loop antenna.

10. A system as in claim 1 each of said housing antennas is a spiral antenna.

11. A system as in claim 1 wherein each of said transceiving antennas is a spiral antenna.

12. A system for measuring a fluid level in a tank, comprising:

a level-sensing probe adapted to be positioned in a tank containing a fluid such that said probe substantially spans the height of the tank, said probe divided into a plurality of sections with each of said sections including (i) a section housing having a bore formed therethrough along the length thereof wherein said bore associated with each of said sections is aligned with said bore associated with adjacent ones of said sections, (ii) first and second electrically-conductive plates mounted in said section housing and disposed on either side of said bore substantially all along the length thereof, (iii) a spiral inductor mounted in said section housing and electrically-coupled in parallel to said first and second electrically-conductive plates, (iv) a sensor antenna mounted in said section housing and positioned for inductive coupling to said spiral inductor, and (v) an electrical conductor mounted in said section housing and coupled to said sensor antenna;

an electrically non-conductive housing adapted to be accessible from a position outside of the tank;

a plurality of housing antennas arrayed in a pattern within said housing with each of said housing antennas electrically coupled to said electrical conductor from a corresponding one of said plurality of sections; and

a magnetic field response recorder having a measurement head with a plurality of transceiving antennas arrayed therein to correspond to said pattern of housing antennas, said measurement head including means for mechanically coupling said measurement head to said housing wherein each of said housing antennas is substantially aligned with a specific one of said transceiving antennas for inductive coupling thereto.

13. A system as in claim 12 wherein, for a lowest one of said sections in the tank, said first and second electrically-conductive plates are (i) mirror images of one another along the lengths thereof, and (ii) defined by two different widths along the lengths thereof.

14. A system as in claim 12 wherein, for a lowest one of said sections in the tank, said first and second electrically-conductive plates are (i) mirror images of one another along the lengths thereof, and (ii) separated by different gaps along the lengths thereof.

15. A system as in claim 12 wherein said pattern is two-dimensional.

16. A system as in claim 12 wherein the tank has an opening used for filling the tank with a fluid, and wherein said housing is adapted to fit and cover the opening.

17. A system as in claim 12 wherein said magnetic field response recorder is hand-held.

18. A system as in claim 12 wherein each said spiral inductor is positioned approximately perpendicular to said first and second electrically-conductive plates corresponding thereto.

19. A system as in claim 12 wherein each said sensor antenna is a loop antenna.

20. A system as in claim 12 each of said housing antennas is a spiral antenna.

21. A system as in claim 12 wherein each of said transceiving antennas is a spiral antenna.

22. A system for measuring a fluid level in a tank, comprising:

a level-sensing probe adapted to be positioned in a tank containing a fluid such that said probe substantially spans the height of the tank, said probe divided into a plurality of sensing sections with each of said sensing sections including (i) a section housing made of a solid material inert with respect to the fluid and having a bore formed therethrough along the length thereof wherein said bore associated with each of said sensing sections is aligned with said bore associated with adjacent ones of said sensing sections, (ii) first and second electrically-conductive plates embedded in said section housing and disposed on either side of said bore substantially all along the length thereof, (iii) a spiral inductor embedded in said section housing, electrically-coupled in parallel to said first and second electrically-conductive plates, and disposed approximately perpendicular to said first and second electrically-conductive plates, (iv) a sensor antenna embedded in said section housing and positioned for inductive coupling to said spiral inductor, and (v) an electrical conductor embedded in said section housing and coupled to said sensor antenna;

an electrically non-conductive housing adapted to be fitted to and cover an opening used to fill the tank with the fluid;

a plurality of housing antennas arrayed in a two-dimensional pattern within said housing with each of said housing antennas electrically coupled to said electrical conductor from a corresponding one of said plurality of sensor sections; and

a magnetic field response recorder having a measurement head with a plurality of transceiving antennas arrayed therein to correspond to said two-dimensional pattern of housing antennas, said measurement head including means for mechanically coupling said measurement head to said housing wherein each of said housing antennas is substantially aligned with a specific one of said transceiving antennas for inductive coupling thereto wherein said magnetic field response recorder can interrogate each of said sensing sections independently.

23. A system as in claim 22 wherein, for a lowest one of said sensing sections in the tank, said first and second electrically-conductive plates are (i) mirror images of one another along the lengths thereof, and (ii) defined by two different widths along the lengths thereof.

24. A system as in claim 22 wherein, for a lowest one of said sections in the tank, said first and second electrically-conductive plates are (i) mirror images of one another along the lengths thereof, and (ii) separated by different gaps along the lengths thereof.

25. A system as in claim 22 wherein said magnetic field response recorder is hand-held.

26. A system as in claim 22 wherein each said sensor antenna is a loop antenna.

27. A system as in claim 22 each of said housing antennas is a spiral antenna.

28. A system as in claim 22 wherein each of said transceiving antennas is a spiral antenna.