BULK ACOUSTIC WAVE (BAW) SENSORS FOR LIQUID LEVEL MEASUREMENTS

• US 20150177045A1
• Filed: 12/19/2014
• Published: 06/25/2015
• Est. Priority Date: 12/24/2013
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: COBIANU, CORNEL, GEORGESCU, ION, BOSTAN, CAZIMIR GABRIEL
• Granted Patent: US 10,168,198 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01F 23/296 Acoustic waves
• CPC Class Codes: G01F 23/2966 making use of acoustical resonance or standing waves
• CPC Class Codes: G01F 23/2968 Transducers specially adapted for acoustic level indicators
• CPC Class Codes: G01N 2291/02818 Density, viscosity
• CPC Class Codes: G01N 2291/02836 Flow rate, liquid level
• CPC Class Codes: G01N 2291/0422 Shear waves, transverse waves, horizontally polarised waves
• CPC Class Codes: G01N 2291/0427 Flexural waves, plate waves, e.g. Lamb waves, tuning fork, cantilever
• CPC Class Codes: G01N 29/036 by measuring frequency or resonance of acoustic waves
• CPC Class Codes: G01N 29/222 Constructional or flow details for analysing fluids optoacoustic fluid cells G01N29/2425
• CPC Class Codes: G01N 29/4427 with stored values, e.g. threshold values

Abstract

A method for sensing at least one level parameter of at least one liquid in a tank. At least one bulk acoustic wave (BAW) sensor is positioned inside the tank. Electrodes of the BAW sensor are at least switchably connected to a positive feedback loop across an amplifier to provide an electronic oscillator. At least one acoustic viscosity measurement is determined from an output of the electronic oscillator, wherein the output of the electronic oscillator is different when the BAW sensor contacts the liquid as compared to when the BAW sensor contacts air. The level parameter is determined from the acoustic viscosity measurement.

Claims

1. A method for sensing at least one level parameter of at least one liquid in a tank, comprising:

providing at least one bulk acoustic wave (BAW) sensor positioned inside said tank, wherein electrodes of said BAW sensor are at least switchably connected to a positive feedback loop across an amplifier to provide an electronic oscillator;

determining at least one acoustic viscosity measurement from an output of said electronic oscillator, wherein said output of said electronic oscillator is different when said BAW sensor contacts said liquid as compared to when said BAW sensor contacts air, and

determining said level parameter from said acoustic viscosity measurement.

2. The method of claim 1, wherein said BAW sensor comprises a shear horizontal acoustic plate mode (SHAPM) device.

3. The method of claim 1, wherein said BAW sensor comprises a plurality of BAW sensors stacked vertically along a vertical wall of said tank, said plurality of BAW sensors each for obtaining an acoustic viscosity measurement at different positions along a height of said tank.

4. The method of claim 3, wherein said level parameter comprises a point level.

5. The method of claim 3, wherein said liquid forms an interface with said air above, further comprising determining a presence of foam at said interface from a plurality of said acoustic viscosity measurements obtained using said plurality of BAW sensors.

6. The method of claim 3, wherein said liquid comprises a plurality of immiscible liquids, and wherein said determining said level parameter comprises determining a quasi-continuous level and a position of one or more liquid interfaces.

7. The method of claim 3, wherein said plurality of BAW sensors each have a unique digital address stored in a memory associated with a control unit that provides sensor select signals to a multiplexer (MUX), said MUX individually interrogating said plurality of BAW sensors.

8. The method of claim 3, wherein a vertical spacing between said plurality of BAW sensors is a constant.

9. The method of claim 1, wherein said level parameter is determined from said acoustic viscosity measurement by first utilizing a calibration curve relating a change in resonant frequency for said electronic oscillator to acoustic viscosity.

10. A system for sensing at least one level parameter of at least one liquid in a tank, comprising:

at least one bulk acoustic wave (BAW) sensor positioned inside said tank, wherein electrodes of said BAW sensor are at least switchably connected to a positive feedback loop across an amplifier to provide an electronic oscillator, and

a control unit including a processor and memory coupled to an output of said electronic oscillator, said control unit determining at least one acoustic viscosity measurement from said output of said electronic oscillator, wherein said output of said electronic oscillator is different when said BAW sensor contacts said liquid as compared to when said BAW sensor contacts air,

wherein said control unit determines said level parameter from said acoustic viscosity measurement.

11. The system of claim 10, wherein said BAW sensor comprises a shear horizontal acoustic plate mode (SHAPM) device.

12. The system of claim 10, wherein said BAW sensor comprises a plurality of BAW sensors stacked vertically along a vertical wall of said tank, said plurality of BAW sensors each for obtaining an acoustic viscosity measurement at different positions along a height of said tank.

13. The system of claim 12, further comprising:

a multiplexer (MUX) between said plurality of BAW sensors and said amplifier, wherein said electrodes of each of said plurality of BAW sensors are coupled to inputs of said MUX;

wherein said memory stores a unique digital address for each of said plurality of BAW sensors;

wherein said control unit is coupled to said MUX by a plurality of address lines for providing a selected digital address at any given time to said MUX, and wherein said selected address corresponds to said digital address of a selected one of said plurality of BAW sensors which when selected becomes connected across said positive feedback loop of said amplifier.

14. The system of claim 10, wherein said memory includes a stored calibration curve relating a change in resonant frequency versus acoustic viscosity.

15. The system of claim 12, wherein said liquid forms an interface with said air above, wherein said control unit determines a presence of foam at said interface from a plurality of said acoustic viscosity measurements obtained using said plurality of BAW sensors.

16. The system of claim 10, wherein said liquid comprises a plurality of immiscible liquids, and wherein said control unit determining said level parameter determines a quasi-continuous level and a position of one or more liquid interfaces.

17. The system of claim 10, wherein said level parameter is determined from said acoustic viscosity measurement by said control unit by first utilizing a calibration curve relating a change in resonant frequency for said electronic oscillator to acoustic viscosity.