SYSTEMS AND METHODS FOR LIQUID LEVEL DETECTION

• US 20170176235A1
• Filed: 12/17/2015
• Published: 06/22/2017
• Est. Priority Date: 12/17/2015
• Status: Active Grant

• Current Assignee: Simmonds Precision Products, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Simmonds Precision Products, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: CROWNE, DAVID H.
• Granted Patent: US 10,598,537 B2
• Time in Patent Office: Days
• CPC Class Codes: B64D 37/00 Arrangements in connection with fuel supply for power plant refuelling during flight B64D39/00
• CPC Class Codes: G01F 23/00 Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
• CPC Class Codes: G01F 23/0007 for discrete indicating and measuring G01F23/02 - G01F23/28 take precedence
• CPC Class Codes: G01F 23/241 for discrete levels
• CPC Class Codes: G01F 23/243 Schematic arrangements of probes combined with measuring circuits
• CPC Class Codes: G01F 23/246 thermal devices
• CPC Class Codes: G01F 23/80 Arrangements for signal processing

Abstract

A liquid level detection system for determining a liquid level includes a level sensor configured to be at least partially disposed in a liquid storage vessel and exposed to liquid. A first optoelectronic interface is operatively connected to the level sensor for providing power thereto. A second optoelectronic interface is operatively connected to the first optoelectronic interface. A fiber optic cable optically connects the first optoelectronic interface to the second optoelectronic interface to provide photonic power to the first optoelectronic interface and to transmit data from the first optoelectronic interface to the second optoelectronic interface.

Claims

1. A liquid level detection system comprising:

a level sensor configured to be at least partially disposed in a liquid storage vessel and exposed to liquid;

a first optoelectronic interface operatively connected to the level sensor for providing power thereto; and

a second optoelectronic interface operatively connected to the first optoelectronic interface; and

a fiber optic cable optically connecting the first optoelectronic interface to the second optoelectronic interface to provide photonic power to the first optoelectronic interface and to transmit data from the first optoelectronic interface to the second optoelectronic interface.

2. The liquid level detection system as recited in claim 1, wherein the level sensor includes a dual thermistor bead sensor.

3. The liquid level detection system as recited in claim 1, wherein the first optoelectronic interface includes a power converter in optical communication with the fiber optic cable to convert photonic power to electrical power, and an energy storage component in electrical communication with the power converter to store electrical energy converted by the power converter.

4. The liquid level detection system as recited in claim 3, wherein the first optoelectronic interface includes a signal conditioning circuit operatively connected to the energy storage component and the level sensor to provide electrical power to the level sensor and to receive voltage readings therefrom, wherein the voltage readings are indicative of a liquid level in a liquid storage vessel.

5. The liquid level detection system as recited in claim 4, wherein the first optoelectronic interface includes a pulse driver operatively connected to an output of the signal conditioning circuit to signal an optical transmitter to pulse based on electrical pulses received from the signal conditioning circuit.

6. The liquid level detection system as recited in claim 5, wherein the first optoelectronic interface includes an optical transmitter operatively connected to the pulse driver to generate photonic power pulses.

7. The liquid level detection system as recited in claim 6, wherein an output of the optical transmitter is coupled to the fiber optic cable to provide the photonic power pulses to the second optoelectronic interface indicative of a liquid level in a liquid storage vessel.

8. The liquid level detection system as recited in claim 1, wherein the fiber optic cable is a single fiber optic cable configured to transmit optical power from the second optoelectronic interface to the first optoelectronic interface and to a signal conditioning circuit of the first optoelectronic interface and to transmit data from the signal conditioning circuit of the first optoelectronic interface to the second optoelectronic interface.

9. The liquid level detection system as recited in claim 1, wherein the second optoelectronic interface includes a photodiode operatively connected to the fiber optic cable to receive photonic power pulses therefrom and to generate corresponding electrical pulses.

10. The liquid level detection system as recited in claim 9, further comprising a module electrically coupled to the photodiode of the second optoelectronic interface to determine a liquid level based on electrical pulses received from the photodiode.

11. A method for detecting a liquid level in a liquid storage vessel comprising:

providing photonic power to a first optoelectronic interface through a fiber optic cable;

converting the photonic power to electrical power using a power converter;

providing the electrical power to a signal conditioning circuit to apply a voltage across a level sensor during a measurement cycle;

generating an electrical pulse with the signal conditioning circuit based on at least one voltage reading from the level sensor during the measurement cycle;

determining a liquid level based on the electrical pulse using a module in a second optoelectronic interface, wherein the second optoelectronic interface is operatively connected to the first optoelectronic interface through the fiber optic cable.

12. The method as recited in claim 11, wherein the level sensor includes a thermistor bead, wherein generating the electrical pulse with the signal conditioning circuit includes generating a thermistor bead pulse by comparing an actual thermistor bead voltage to a ramp voltage.

13. The method as recited in claim 12, further comprising generating two additional electrical pulses with the signal conditioning circuit, wherein one of the two additional electrical pulses includes a start pulse generated at a start of the measurement cycle, and wherein the other of the two additional electrical pulses includes a framing pulse generated by comparing the ramp voltage to a reference voltage.

14. The method as recited in claim 13, wherein the start and framing pulses encode a full scale of possible thermistor bead voltages as delta time, and wherein the thermistor bead pulse defines a fractional thermistor bead voltage based on the actual thermistor bead voltage encoded as time relative to the full scale.

15. The method as recited in claim 14, wherein the actual thermistor bead voltage is a first actual thermistor bead voltage and wherein the fractional thermistor bead voltage is a first fractional thermistor bead voltage, wherein the level sensor includes a second thermistor bead wherein generating the electrical pulse with the signal conditioning circuit includes generating a second thermistor bead pulse by comparing a second actual thermistor bead voltage to the ramp voltage, wherein the second thermistor bead pulse defines a second fractional thermistor bead voltage based on the second actual thermistor bead voltage encoded as time relative to the full scale.

16. The method as recited in claim 15, wherein determining the liquid level based on the electrical pulse using the module includes comparing the difference between the first and second fractional thermistor bead voltages to a threshold value to determine whether the level sensor is wet or dry.