Ultrasonic fuel level monitoring system incorporating an acoustic lens

• US 7,905,143 B2
• Filed: 07/23/2007
• Issued: 03/15/2011
• 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
• Primary Examiner(s): Williams; Hezron
• Assistant Examiner(s): KOLB, NATHANIEL J
• Application Number:
  US11/880,671
• Publication Number:
  US 20090025474A1
• Time in Patent Office: 1,331 Days
• Field of Search: 732/90.V
• US Class Current: 73/290.00V
• 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;

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;

wherein the acoustic lens includes a diameter greater than a diameter of the emitter; and

wherein the diameter of the acoustic lens is approximately one wavelength of the ultrasonic signal passing through the acoustic lens greater than the diameter of the emitter.

2. 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 diverge the ultrasonic beam and thereby compensate for a converging effect of the tank wall, such that the resulting wavefront of the ultrasonic beam is substantially parallel to the liquid surface.

3. The ultrasonic transducer unit of claim 2, wherein a wavefront that is substantially parallel to the liquid surface comprises a wavefront with a divergence of approximately zero to five degrees after the beam passes through a tank wall.

4. The ultrasonic transducer of claim 2, wherein the acoustic lens is concave.

5. The ultrasonic transducer of claim 2, wherein the acoustic lens is convex.

6. The ultrasonic transducer of claim 2, wherein the acoustic lens is coupled to the emitter with a bonding material.

7. The ultrasonic transducer of claim 2, 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.

8. The ultrasonic transducer of claim 2, wherein the emitter comprises a piezoelectric crystal transducer.

9. The ultrasonic transducer of claim 2, wherein the acoustic lens comprises metal.

10. The ultrasonic transducer of claim 2, wherein the acoustic lens comprises aluminum.

11. The ultrasonic transducer of claim 2, wherein the acoustic lens includes a diameter greater than a diameter of the emitter.

12. The ultrasonic transducer of claim 2, wherein the diameter of the acoustic lens is approximately one wavelength of the ultrasonic signal passing through the acoustic lens greater than the diameter of the emitter.