Ultrasonic fuel level monitoring system incorporating an acoustic lens

• US 20090025474A1
• Filed: 07/23/2007
• Published: 01/29/2009
• Est. Priority Date: 07/23/2007
• Status: Active Grant

• Current Assignee: Schmitt Measurement Systems, Inc. (Schmitt Industries, Inc.)
• Original Assignee: Schmitt Measurement Systems, Inc. (Schmitt Industries, Inc.)
• Inventors: Lagergren, Peter
• Granted Patent: US 7,905,143 B2
• Time in Patent Office: Days
• US Class Current: 73/290.V
• CPC Class Codes: G01F 23/2962 Measuring transit time of reflected waves
• CPC Class Codes: G01F 23/2968 Transducers specially adapted for acoustic level indicators
• CPC Class Codes: G01F 23/802 Particular electronic circuits for digital processing equipment
• CPC Class Codes: G01F 23/804 containing circuits handling parameters other than liquid level

Abstract

An ultrasonic liquid level monitoring system includes an ultrasonic transducer unit that is mountable to a tank. The unit has an emitter to generate an ultrasonic beam passing through the wall of the tank. The emitter further receives an echo of the ultrasonic beam off a liquid surface. An acoustic lens is disposed between the emitter and the tank wall to receive and shape the ultrasonic beam to compensate for lensing effects of the tank wall.

Claims

1. An ultrasonic transducer unit mountable to a tank and to measure a liquid level in a tank, comprising:

an emitter to generate an ultrasonic beam to pass through a tank wall and to receive an echo of the ultrasonic beam off a liquid surface;

a transducer driver in electrical communication with the emitter; and

an acoustic lens coupled to the emitter and configured to shape the ultrasonic beam and configured to diverge the ultrasonic beam and thereby provide a divergent ultrasonic beam after the ultrasonic beam passes through a tank wall.

2. The ultrasonic transducer unit of claim 1, wherein the acoustic lens is configured to provide a divergent ultrasonic beam with a divergence having a range of approximately zero to five degrees after the beam passes through a tank wall.

3. The ultrasonic transducer of claim 1, wherein the acoustic lens is concave.

4. The ultrasonic transducer of claim 1, wherein the acoustic lens is convex.

5. The ultrasonic transducer of claim 1, wherein the acoustic lens is coupled to the emitter with a bonding material.

6. The ultrasonic transducer of claim 1, further comprising a plurality of mounting magnets rotatably threaded into the transducer and extending from the transducer, wherein rotation of the mounting magnets determines the extension from the transducer.

7. The ultrasonic transducer of claim 1, wherein the emitter comprises a piezoelectric crystal transducer.

8. The ultrasonic transducer of claim 1, wherein the acoustic lens comprises metal.

9. The ultrasonic transducer of claim 10, wherein the acoustic lens comprises aluminum.

10. The ultrasonic transducer of claim 1, wherein the acoustic lens includes a diameter greater than a diameter of the emitter.

11. The ultrasonic transducer of claim 10, wherein the diameter of the acoustic lens is approximately one ultrasonic beam wavelength greater than the diameter of the emitter.

12. An ultrasonic transducer unit mountable to a tank and to measure a liquid level in a tank, comprising:

an emitter to generate an ultrasonic beam to pass through a tank wall and to receive an echo of the ultrasonic beam off a liquid surface;

a transducer driver in electrical communication with the emitter; and

an acoustic lens coupled to the emitter and configured to shape the ultrasonic beam and configured to converge the ultrasonic beam and thereby provide a convergent ultrasonic beam after the ultrasonic beam passes through a tank wall, the convergent ultrasonic beam having an increased flux density over the ultrasonic beam.

13. The ultrasonic transducer of claim 12, wherein the acoustic lens is concave.

14. The ultrasonic transducer of claim 12, wherein the acoustic lens is convex.

15. The ultrasonic transducer of claim 12, wherein the acoustic lens is coupled to the emitter with a bonding material.

16. The ultrasonic transducer of claim 12, further comprising a plurality of mounting magnets rotatably threaded into the transducer and extending from the transducer, wherein rotation of the mounting magnets determines the extension from the transducer.

17. The ultrasonic transducer of claim 12, wherein the emitter comprises a piezoelectric crystal transducer.

18. The ultrasonic transducer of claim 12, wherein the acoustic lens comprises metal.

19. The ultrasonic transducer of claim 18, wherein the acoustic lens comprises aluminum.

20. The ultrasonic transducer of claim 12, wherein the acoustic lens includes a diameter greater than a diameter of the emitter.

21. The ultrasonic transducer of claim 20, wherein the diameter of the acoustic lens is approximately one ultrasonic beam wavelength greater than the diameter of the emitter.

22. An ultrasonic transducer unit mountable to a tank and to measure a liquid level in the tank, comprising:

an emitter to generate an ultrasonic beam to pass through a tank wall and to receive an echo of the ultrasonic beam off a liquid surface;

a transducer driver in electrical communication with the emitter; and

an acoustic lens coupled to the emitter to receive the ultrasonic beam and configured to shape the ultrasonic beam and compensate for lensing effects of the ultrasonic beam passing through a tank wall.

23. The ultrasonic transducer of claim 22, wherein the acoustic lens is further configured to shape the ultrasonic beam to provide a substantially flat wavefront.

24. The ultrasonic transducer of claim 22, wherein the acoustic lens is further configured to align the ultrasonic beam.

25. The ultrasonic transducer of claim 22, wherein the acoustic lens is further configured to diverge the ultrasonic beam and thereby provide a divergent ultrasonic beam after the ultrasonic beam passes through a tank wall.

26. The ultrasonic transducer unit of claim 25, wherein the acoustic lens is configured to provide a divergent ultrasonic beam with a divergence having a range of approximately zero to five degrees after the beam passes through a tank wall.

27. The ultrasonic transducer of claim 22, wherein the acoustic lens is further configured to converge the ultrasonic beam to provide a convergent ultrasonic beam after the ultrasonic beam passes through a tank wall.

28. The ultrasonic transducer of claim 22, wherein the acoustic lens is concave.

29. The ultrasonic transducer of claim 22, wherein the acoustic lens is convex.

30. The ultrasonic transducer of claim 22, wherein the acoustic lens is coupled to the emitter with a bonding material.

31. The ultrasonic transducer of claim 22, further comprising a plurality of mounting magnets rotatably threaded into the transducer and extending from the transducer, wherein rotation of the mounting magnets determines the extension from the transducer.

32. The ultrasonic transducer of claim 22, wherein the emitter comprises a piezoelectric crystal transducer.

33. The ultrasonic transducer of claim 22, wherein the acoustic lens comprises metal.

34. The ultrasonic transducer of claim 22, wherein the acoustic lens comprises aluminum.

35. The ultrasonic transducer of claim 22, wherein the acoustic lens includes a diameter greater than a diameter of the emitter.

36. The ultrasonic transducer of claim 22, wherein the diameter of the acoustic lens is approximately one ultrasonic beam wavelength greater than the diameter of the emitter.

37. A method of generating an ultrasonic beam to measure a liquid level in a tank, comprising:

providing an emitter to generate an ultrasonic beam to pass through a tank wall and to receive an echo of the ultrasonic beam off a liquid surface;

configuring an acoustic lens to shape the ultrasonic beam and compensate for lensing effects of the ultrasonic beam passing through a tank wall;

coupling the acoustic lens to the emitter to receive the ultrasonic beam;

placing the emitter in electrical communication with a transducer driver; and

mounting the emitter and acoustic lens to a tank wall such that the acoustic lens is disposed between the emitter and the tank wall.

38. The method of claim 37, wherein configuring the acoustic lens includes configuring the acoustic lens to shape an ultrasonic beam to provide a substantially flat wavefront.

39. The method of claim 37, wherein configuring the acoustic lens includes configuring the acoustic lens to align the ultrasonic beam.

40. The method of claim 37, wherein configuring the acoustic lens includes configuring the acoustic lens to diverge the ultrasonic beam and thereby provide a divergent ultrasonic beam after the ultrasonic beam passes through a tank wall.

41. The method of claim 37, wherein configuring the acoustic lens includes configuring the acoustic lens to diverge the ultrasonic beam with a divergence having a range of approximately zero to five degrees after the beam passes through a tank wall.

42. The method of claim 37, wherein configuring the acoustic lens includes configuring the acoustic lens to converge the ultrasonic beam to provide a convergent ultrasonic beam after the ultrasonic beam passes through a tank wall.

43. The method of claim 37, wherein configuring the acoustic lens includes configuring the acoustic lens with a concave shape.

44. The method of claim 37, wherein configuring the acoustic lens includes configuring the acoustic lens with a convex shape.

45. The method of claim 37 wherein coupling the acoustic lens to the emitter includes applying a bonding material between the acoustic lens and the emitter.

46. The method of claim 37, further comprising:

providing a housing at least partially encompassing the emitter;

providing a plurality of mounting magnets extending from the housing; and

extending the mounting magnets to provide a desired distance of the emitter from the tank wall.

47. The method of claim 37, wherein the emitter comprises a piezoelectric crystal transducer.

48. The method of claim 37, wherein the acoustic lens comprises metal.

49. The method of claim 48, wherein the acoustic lens comprises aluminum.

50. The method of claim 37, wherein mounting the emitter and acoustic lens to a tank wall includes applying a bonding material between the acoustic lens and the tank wall.

51. The method of claim 37, wherein the acoustic lens includes a diameter greater than a diameter of the emitter.

52. The method of claim 51, wherein the diameter of the acoustic lens is approximately one ultrasonic beam wavelength greater than the diameter of the emitter.