RECREATIONAL VEHICLE HOLDING TANK SENSOR PROBE

• US 20090278699A1
• Filed: 05/12/2008
• Published: 11/12/2009
• Est. Priority Date: 05/12/2008
• Status: Active Grant

• Current Assignee: Valterra Products Incorporated
• Original Assignee: John Vander Horst
• Inventors: Horst, John Vander
• Granted Patent: US 8,410,948 B2
• Time in Patent Office: Days
• US Class Current: 340/603
• CPC Class Codes: G01F 23/24 by measuring variations of resistance of resistors due to contact with conductor fluid
• CPC Class Codes: G01F 23/242 Mounting arrangements for electrodes
• CPC Class Codes: G01F 23/243 Schematic arrangements of probes combined with measuring circuits

Abstract

A wastewater holding tank sensor probe for use in determining the presence of a conductive liquid held within a wastewater holding tank in a recreational vehicle is disclosed. The probe is less sensitive to the presence of conductive residue as a result of an improved geometry and/or choice of materials that reduce the leakage currents between the probe tip and the sensor probe attachment surface, typically the wall of the tank. This reduction in sensitivity to conductive residue buildup can be measured by a geometrically determined resistivity factor between the probe tip and the mounting surface of the probe. The reduction in sensitivity can also be measured by the length of the path through the conductive residue between the probe tip and the mounting surface of the probe. A variety of geometries and material choices to reduce the sensitivity of electrical conductance based sensor probes to conductive residue are disclosed.

Claims

1. A moving wastewater holding tank sensor probe for use in determining presence of conductive liquid within a wastewater holding tank, the moving wastewater holding tank sensor probe comprising:

an electrical contact configured for wiring into a level measuring circuit;

a probe tip configured for contact with fluid within the wastewater holding tank during normal operation;

an electrical conductor for electrically coupling the electrical contact and the probe tip, whereby the electrical conductor is configured for installation through an aperture in the wastewater holding tank during normal operation;

an electrical insulator at least partially encapsulating the electrical conductor, wherein;

the electrical insulator has exposed surface that is configured to be in contact with any fluid in the wastewater holding tank, and

a path from the probe tip and along the exposed surface toward the aperture, during normal operation, wherein the path has a resistivity factor that exceeds 0.5; and

a fitting suitable for sealing the aperture, wherein the fitting is annularly configured around at least one of the electrical contact and the electrical conductor.

2. The moving wastewater holding tank sensor probe for use in determining presence of conductive liquid within the wastewater holding tank as recited in claim 1, wherein the electrical conductor is threaded.

3. The moving wastewater holding tank sensor probe for use in determining presence of conductive liquid within the wastewater holding tank as recited in claim 1, wherein the resistivity factor exceeds one of 0.75, 1.0, 1.25, 1.5, 1.75, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, and 6.0.

4. The moving wastewater holding tank sensor probe for use in determining presence of conductive liquid within the wastewater holding tank as recited in claim 1, wherein at least two of the electrical contact, the electrical conductor and the probe tip are monolithic.

5. The moving wastewater holding tank sensor probe for use in determining presence of conductive liquid within the wastewater holding tank as recited in claim 1, wherein at least part of the electrical insulator is non-wetting.

6. The moving wastewater holding tank sensor probe for use in determining presence of conductive liquid within the wastewater holding tank as recited in claim 1, wherein:

at least one part of the electrical insulator has a cross-section perpendicular to a line between the probe tip and the electrical contact, the one part is at least one of ⅛

inch, ¼

inch, ⅜

inch, ½

inch, ⅝

inch, and ¾

inch long, and

the cross-section is less than one of 1/16 inch, 3/32 inch, ⅛

inch, 5/32 inch, 3/16 inch, 7/32 inch, ¼

inch, 9/32 inch, and 5/16 inch across.

7. The moving wastewater holding tank sensor probe for use in determining presence of conductive liquid within the wastewater holding tank as recited in claim 1, further comprising an orientation mark fixed relative to the electrical conductor configured to be visible from outside from the mobile wastewater holding tank.

8. The moving wastewater holding tank sensor probe for use in determining presence of conductive liquid within the wastewater holding tank as recited in claim 1, further comprising a shield that can be positioned to prevent the accumulation of debris on the probe tip.

9. The moving wastewater holding tank sensor probe for use in determining presence of conductive liquid within the wastewater holding tank as recited in claim 1, wherein the fitting is elastic.

10. The moving wastewater holding tank sensor probe for use in determining presence of conductive liquid within the wastewater holding tank as recited in claim 1, wherein the fitting is suitable for spin welding.

11. A holding tank sensor probe for use in determining presence of conductive liquid within a mobile wastewater holding tank, the holding tank sensor probe comprising:

an electrical contact;

a probe tip;

an electrical conductor for electrically coupling the electrical contact and the probe tip, whereby the electrical conductor is configured for installation at least partially within the mobile wastewater holding tank during normal operation; and

an electrical insulator between the probe tip and the electrical conductor, wherein;

the electrical insulator has exposed surface, and

a path from the probe tip and along the exposed surface away from the probe tip to a most proximate point on a wall of the tank passes a distance in excess of 0.75 inch.

12. The holding tank sensor probe for use in determining presence of conductive liquid within the mobile wastewater holding tank as recited in claim 11, wherein the path further comprises a resistivity factor that exceeds at least one of 0.5, 0.75, 1.0, 1.25, 1.5, 1.75, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, and 6.0.

13. The holding tank sensor probe for use in determining presence of conductive liquid within the mobile wastewater holding tank as recited in claim 11, wherein the distance exceeds 1.0 inch, 1.25 inches, 1.5 inches, 1.75 inches, 2.0 inches, 2.25 inches, 2.5 inches, 2.75 inches, and 3.0 inches.

14. The holding tank sensor probe for use in determining presence of conductive liquid within the mobile wastewater holding tank as recited in claim 11, further comprising a cap proximate to the electrical conductor, wherein the cap compresses an o-ring to seal the electrical insulator.

15. The holding tank sensor probe for use in determining presence of conductive liquid within the moving wastewater holding tank as recited in claim 11, wherein:

the path includes a change in direction of 120 degrees or more, and the thickness of the insulator proximate to the change in direction is 5/32 inch or less.

16. The holding tank sensor probe for use in determining presence of conductive liquid within the moving wastewater holding tank as recited in claim 11, wherein:

the path includes a change in direction of 120 degrees or more, and

the radius of the change in direction is 5/64 inch or less.

17. The holding tank sensor probe for use in determining presence of conductive liquid within the mobile wastewater holding tank as recited in claim 11, wherein the electrical insulator, along a radius of a cross-section perpendicular to a line between the probe tip and the electrical contact, has a first portion and a second portion, which are separated by free space.

18. The holding tank sensor probe for use in determining presence of conductive liquid within the mobile wastewater holding tank as recited in claim 11, further comprising a shield configured to prevent the accumulation of debris and an orientation mark fixed relative to the electrical conductor configured to be visible from outside from the mobile wastewater holding tank.

19. A holding tank sensor probe for use in determining presence of conductive liquid within a mobile wastewater holding tank, the holding tank sensor probe comprising:

an electrical contact;

a probe tip;

an electrical conductor for electrically coupling the electrical contact and the probe tip, whereby the electrical conductor is configured for installation through an aperture in the mobile wastewater holding tank during normal operation; and

an electrical insulator between the probe tip and the electrical conductor, wherein;

the electrical insulator has a cross section, and

the cross section has a maximum dimension of 5/16 inch or less in at least one part.

20. The holding tank sensor probe for use in determining presence of conductive liquid within the mobile wastewater holding tank as recited in claim 19, wherein the path further comprises a resistivity factor that exceeds one of 0.5, 0.75, 1.0, 1.25, 1.5, 1.75, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, and 6.0.

21. The holding tank sensor probe for use in determining presence of conductive liquid within the mobile wastewater holding tank as recited in claim 19, wherein the maximum dimension is at least one of 1/16 inch, 3/32 inch, ⅛

inch, 5/32 inch, 3/16 inch, 7/32 inch, ¼

inch, 9/32 inch, and 5/16.

22. The holding tank sensor probe for use in determining presence of conductive liquid within the mobile wastewater holding tank as recited in claim 19, wherein a path from the probe tip and along the exposed surface away from the probe tip to a most proximate point on a wall of the tank passes a distance that exceeds one of 0.75 inch, 1.0 inch, 1.25 inches, 1.5 inches, 1.75 inches, 2.0 inches, 2.25 inches, 2.5 inches, 2.75 inches, and 3.0 inches.

23. The holding tank sensor probe for use in determining presence of conductive liquid within the mobile wastewater holding tank as recited in claim 19, further comprising a shield that can be positioned to prevent the accumulation of debris on the probe tip and an orientation mark fixed relative to the electrical conductor configured to be visible from outside the mobile wastewater holding tank.