Impedance level meter for liquids in tanks

• US 6,938,478 B2
• Filed: 11/14/2002
• Issued: 09/06/2005
• Est. Priority Date: 11/14/2002
• Status: Expired due to Fees

• Current Assignee: Trinity Industries Incorporated
• Original Assignee: Herman Diaz Arias
• Inventors: Arias, Herman Diaz
• Primary Examiner(s): Williams, Hezron
• Assistant Examiner(s): FRANK, RODNEY T
• Application Number:
  US10/294,970
• Publication Number:
  US 20040093943A1
• Time in Patent Office: 1,027 Days
• Field of Search: 732/90.R, 733/04.R, 733/04.C
• US Class Current: 73/304.00R
• CPC Class Codes: G01F 23/24 by measuring variations of resistance of resistors due to contact with conductor fluid

Abstract

A method and a system for detecting the level of fluid in a container is provided: The level meter includes first, second and third generally parallel probes being positioned within the container. The first probe includes a first portion that is at least partially covered by an insulating material, and a second generally exposed end. The second probe is generally free of the insulating material and the third probe provides an electrical ground. An electronic unit is operable to measure electrical characteristics of the first and second probes to determine an amount of the second probe which is exposed to a fluid within the container.

Claims

1. A level meter, comprising:

first, second and third generally parallel probes being positioned within a container;

the first probe having a first portion at least partially covered by an insulating material, and a second generally exposed end;

the second probe being generally free of the insulating material and the third probe being an electrical ground; and

an electronic unit being operable to measure electrical characteristics of the first and second probes to determine a length of the second probe that is exposed to a fluid within the container.

2. The level meter of claim 1, further comprising a metal body cap coupled with a top portion of the container, the first, second and third probes extending through the metal body cap.

3. The level meter of claim 1, further comprising first, second and third spring connectors being operable to couple the first, second and third probes, respectively, with the electronic unit.

4. The level meter of claim 3, wherein the electronic unit further comprises a printed circuit board, and wherein the first, second and third spring connectors are operable to couple the first, second and third probes, respectively, with the printed circuit board.

5. The level meter of claim 4, further comprising a liquid crystal display being operable to display information regarding a level of the fluid within the container.

6. The level meter of claim 1, wherein the first, second and third probes are anodized.

7. The level meter of claim 1, wherein the first probe is electrically coupled with a first monostable multivibrator, and the second probe is electrically coupled with a second monostable multivibrator.

8. The level meter of claim 7, wherein the first and second monostable multivibrators comprise first and second triggers, respectively, the first trigger being electrically coupled with an output of the second monostable multivibrator, and the second trigger being electrically coupled with the an output of the first monostable multivibrator.

9. The level meter of claim 8, further comprising a circuit formed, at least in part, by the first and second monostable multivibrators, the circuit being operable to generate waveforms that correspond to the level of fluid.

10. The level meter of claim 1, wherein the first, second and third probes each comprise a metal or metal alloy, and each of the first, second and third probes are at least partially treated with a chemical to provide partial insulation thereto.

11. The level meter of claim 1, further comprising a printed circuit ribbon, wherein the first, second and third probes are formed upon the printed circuit ribbon.

12. The level meter of claim 11, wherein the printed circuit ribbon further comprises pulse width modulation circuitry.

13. The level meter of claim 12, wherein a distance between the first probe and the third probe, and between the second probe and the third probe comprises approximately between one and five millimeters.

14. A method for detecting a level of fluid in a container, comprising:

installing first, second and third generally parallel probes within a container;

the first probe having a first portion at least partially covered by an insulating material, and a second generally exposed end;

the second probe being generally free of the insulating material, and the third probe providing an electrical ground; and

measuring electrical characteristics of the first and second probes to determine a length of the second probe that is exposed to a fluid within the container.

15. The method of claim 14, wherein the first, second and third probes extend through a metal body cap that seals the container from ambient environment.

16. The method of claim 14, wherein the level meter further comprises an electronic unit, and further comprising coupling the first, second and third probes with the electronic unit using first, second and third spring connectors.

17. The method of claim 16, further comprising displaying information regarding a level of fluid within the container, using a liquid crystal display that is electrically coupled with the electronic unit.

18. The method of claim 14, further comprising chemically treating the first, second and third probes to provide partial insulation thereto.

19. The method of claim 14, further comprising anodizing the first, second and third probes.

20. The method of claim 14, further comprising electrically coupling the first probe with a first monostable multivibrator, and electrically coupling the second probe with a second monostable multivibrator.

21. The method of claim 20, further comprising electrically coupling a first trigger associated with the first monostable multivibrator with an output of the second monostable multivibrator, and electrically coupling a second trigger associated with the second monostable multivibrator, with an output of the first monostable multivibrator.

22. The method of claim 21, further comprising generating waveforms that correspond to the level of fluid using a circuit formed, at least in part, by the first and second monostable multivibrators.

23. The method of claim 14, further comprising forming the first, second and third probes upon a printed circuit ribbon.

24. A level meter for detecting a level of fluid having a relatively low impedance, within a container, comprising:

first and second generally parallel probes being positioned within a container;

the first probe having a first portion at least partially covered by an insulating material, and a second generally exposed end, and the second probe being generally free of the insulating material; and

an electronic unit being operable to measure electrical characteristics of the first and second probes, to determine a length of the second probe that is exposed to a fluid having a relatively low impedance, within the container.