Fuel density measuring device, system, and method using magnetostrictive probe bouyancy

• US 20060266113A1
• Filed: 05/31/2005
• Published: 11/30/2006
• Est. Priority Date: 05/31/2005
• Status: Active Grant

• Current Assignee: Veeder-Root Co (Vontier Corp.)
• Original Assignee: Veeder-Root Co (Vontier Corp.)
• Inventors: Hart, Robert P.
• Granted Patent: US 7,454,969 B2
• Time in Patent Office: Days
• US Class Current: 73/447
• CPC Class Codes: G01F 23/2963 magnetostrictive
• CPC Class Codes: G01F 23/68 using electrically actuated indicating means
• CPC Class Codes: G01F 23/72 using magnetically actuated indicating means
• CPC Class Codes: G01N 9/18 Special adaptations for indicating, recording, or control
• CPC Class Codes: G01N 9/20 by balancing the weight of the bodies

Abstract

A magnetostrictive fuel level probe includes a spring-loaded foot. The probe shaft of the fuel level probe moves up and down within the spring-loaded foot as a function of fuel density. The spring-loaded foot includes a reference magnet whose height relative to the bottom of a fuel storage tank is fixed. Currents generated by the fuel level probe allow measurement of how much of the fuel level probe is positioned above the reference magnet, and from this measurement, the buoyancy of the fuel level probe may be measured. From the buoyancy of the fuel level probe, the fuel density may be calculated.

Claims

1. A fuel level probe, comprising:

a probe shaft adapted to be positioned in a fuel tank; and

a spring-loaded foot positioned on a terminal end of the probe shaft.

2. The fuel level probe of claim 1, wherein the spring-loaded foot comprises a reference magnet whose height relative to a bottom of the fuel tank is fixed.

3. The fuel level probe of claim 1, wherein the fuel level probe is adapted to measure values from which fuel density can be derived.

4. The fuel level probe of claim 3, further comprising a fuel level float adapted to float at a top surface of fuel within the fuel tank and provide an indication of a fuel level within the fuel tank for the fuel level probe.

5. The fuel level probe of claim 3, wherein the fuel level probe is adapted to report data about values from which the fuel density can be derived to a remote location.

6. The fuel level probe of claim 4, further comprising a water level float adapted to float at a level proximate a water-fuel interface within the fuel tank and further adapted to provide an indication of a water level within the fuel tank for the fuel level probe.

7. The fuel level probe of claim 1, wherein the spring-loaded foot comprises an inner cup and an outer cup.

8. The fuel level probe of claim 7, wherein the spring-loaded foot further comprises a spring positioned between the inner and outer cups.

9. The fuel level probe of claim 8, wherein the inner cup fits on the probe shaft and the probe shaft moves up and down within the outer cup.

10. The fuel level probe of claim 2, further comprising a magnetostrictive wire positioned in the probe shaft, and wherein the magnetostrictive wire generates a reflection based on the reference magnet such that a time measurement of the reflection may be used to determine a length of the magnetostrictive wire positioned above the reference magnet.

11. The fuel level probe of claim 9, further comprising a probe reference magnet associated with the probe shaft and fixedly positioned relative to the probe shaft.

12. The fuel level probe of claim 8, wherein the inner cup and the outer cup delimit respective indentations and the spring is positioned at least partially within the respective indentations to restrict lateral movement of the spring.

13. The fuel level probe of claim 1,

wherein the probe shaft comprises a magnetostrictive wire positioned within the probe shaft;

wherein the fuel level probe generates a current on the magnetostrictive wire and detects torsional wave reflections in the magnetostrictive wire; and

wherein the spring-loaded foot comprises a reference magnet and the probe shaft moves relative to the reference magnet such that fuel density can be derived by measuring how much of the probe shaft is positioned above the reference magnet.

14. A method of detecting fuel density for fuel within a fuel storage tank, comprising:

measuring, with a magnetostrictive fuel probe having a probe shaft, a distance associated with an amount of the probe shaft positioned above a reference magnet;

calculating a buoyancy associated with the probe shaft;

calculating from the buoyancy of the probe shaft, the fuel density for fuel within the fuel storage tank; and

reporting the fuel density to a location removed from the magnetostrictive fuel probe.

15. The method of claim 14, wherein measuring the distance associated with the amount of the probe shaft positioned above the reference magnet comprises allowing the probe shaft to move up and down within a spring-loaded foot associated with the magnetostrictive fuel probe.

16. The method of claim 15, wherein the probe shaft moves up and down within the spring-loaded foot as a function of the buoyancy of the probe shaft.

17. The method of claim 16, wherein calculating according to the algorithm comprises calculating a force exerted by a spring on the probe shaft, namely F_s=K_s*(H_s0−

H_s), wherein F_s is the force exerted by the spring, K_s is a spring constant of the spring, H_s0 is an unloaded height of the spring, and H_s is a loaded height of the spring.

18. The method of claim 17, wherein calculating according to the algorithm comprises subtracting the force exerted by the spring on the probe shaft from the weight of the probe shaft, namely W_p−

K_s*(H_s0−

H_s), where W_p is the weight of the probe shaft.

19. The method of claim 18, wherein calculating according to the algorithm comprises dividing a quantity of the weight of the probe shaft minus the force exerted by the spring by a volume of the probe shaft within the fuel, namely

20. The method of claim 15, wherein measuring comprises, at least in part, measuring a time component associated with a torsional reflection.

21. The method of claim 15, wherein measuring comprises, at least in part, measuring a fuel depth with the magnetostrictive fuel probe.

22. The method of claim 15, wherein reporting the fuel density to a location removed from the magnetostrictive fuel probe comprises encrypting data from the magnetostrictive fuel probe such that it cannot be altered by a fueling site operator.

23. The method of claim 15, further comprising measuring a distance to a probe reference magnet associated with a terminal end of the probe shaft and comparing this distance to the distance associated with the amount of the probe shaft positioned above the reference magnet.

24. A system of measuring fuel density in a fuel storage tank, comprising:

a magnetostrictive fuel level probe adapted to determine a fuel level within the fuel storage tank, said magnetostrictive fuel level probe comprising a probe shaft adapted to extend into the fuel storage tank, the probe shaft having a weight (W_p);

a foot attached to the probe shaft, the foot comprising;

an outer cup adapted to receive a portion of the probe shaft and allowing the probe shaft to move up and down within the outer cup;

a reference magnet with respect to which the probe shaft moves up and down; and

a spring positioned inside the outer cup and on which the weight rests such that the spring is compressed; and

a control system adapted to determine the fuel density from measurements made by the magnetostrictive fuel level probe regarding a position of the probe shaft relative the reference magnet and the fuel level within the fuel storage tank.

25. The system of claim 24, wherein the foot further comprises an inner cup, wherein the spring is positioned between the inner cup and the outer cup.

26. The system of claim 25, wherein the inner cup and the outer cup both define respective indentations in which the spring rests such that lateral movement of the spring is restricted.

27. The system of claim 25, wherein the probe shaft further comprises a probe reference magnet and the control system knows a distance value for the probe reference magnet.

28. The system of claim 25, wherein the control system calculates the fuel density according to the following equation:

29. The system of claim 28, wherein the magnetostrictive fuel level probe is adapted to determine the fuel level within the fuel storage tank with a fuel level float and is further adapted to determine a water level within the fuel storage tank with a water level float.

30. The system of claim 24, wherein the control system is adapted to report the fuel density to an off-site location

31. The system of claim 30, wherein the control system is adapted to report the fuel density to the off-site location directly.

32. The system of claim 30, wherein the control system is adapted to report the fuel density to the off-site location indirectly through a site communicator.

33. The system of claim 24, further comprising a tank monitor and said control system is associated with the tank monitor.

34. The system of claim 30, wherein the control system is adapted to report the fuel density to the off-site location in an encrypted format.

35. The system of claim 27, wherein the control system calculates the fuel density (D_f) according to the following equation:

36. The system of claim 27, wherein torsional wave reflections generated by the reference magnet are compared to torsional wave reflections generated by the probe reference magnet.

37. A magnetostrictive liquid level probe, comprising:

a probe shaft adapted to be positioned in a liquid tank, said probe shaft enclosing a magnetostrictive element;

a canister secured to the probe shaft and including electronics adapted to generate a current on the magnetostrictive element within said probe shaft;

one or more magnets associated with the probe shaft, wherein said one or more magnets generate signals in the magnetostrictive element capable of being detected by the electronics; and

a spring-loaded foot positioned on a terminal end of the probe shaft;

wherein density of liquid within the liquid tank can be determined with the magnetostrictive liquid level probe.