SYSTEM AND METHOD FOR ACCURATELY MEASURING FLUID LEVEL IN A VESSEL

• US 20090235737A1
• Filed: 10/01/2008
• Published: 09/24/2009
• Est. Priority Date: 10/01/2007
• Status: Active Grant

• Current Assignee: Meggitt Safety Systems, Inc. (Meggitt PLC)
• Original Assignee: Vibro-Meter, Inc.
• Inventors: Carvalho, Carlos Eduardo, Rizzo, Vincent, Miskell, Thomas, Petriel, Kevin John, Lavon, Ronie
• Granted Patent: US 9,453,755 B2
• Time in Patent Office: Days
• US Class Current: 73/290.V
• CPC Class Codes: G01F 23/284 Electromagnetic waves
• CPC Class Codes: G01S 13/18 wherein range gates are used

Abstract

A system and method for accurately measuring fluid level in a vessel is provided. Generally, the system contains an elongated portion being a coaxial tube having a hollow center, an arm being coaxial in shape, and a sensor containing a transmitter capable of creating and transmitting an excitation electromagnetic pulse for traversing the elongated portion and the arm, and a receiver for receiving reflected pulses, wherein a proximate end of the elongated portion joins a distal end of the arm in a manner to create a waveguide for an electromagnetic pulse provided by the sensor.

Claims

1. A system for accurately measuring fluid level in a vessel, comprising:

an elongated portion being a coaxial tube having a hollow center;

an arm being coaxial in shape; and

a sensor comprising a transmitter capable of creating and transmitting an excitation electromagnetic pulse for traversing the elongated portion and the arm, and a receiver for receiving reflected pulses,

wherein a proximate end of the elongated portion joins a distal end of the arm in a manner to create a waveguide for an electromagnetic pulse provided by the sensor.

2. The system of claim 1, wherein the elongated portion and an outer shell of the arm are made of a conductive material having a known impedance

3. The system of claim 2, wherein the arm is filled with a dielectric having a known impedance.

4. The system of claim 3, wherein impedance of the dielectric is similar to an impedance of air or an impedance of the fluid being measured.

5. The system of claim 1, wherein the sensor further comprises power supply circuitry, digital logic, and analog circuitry.

6. The system of claim 5, wherein electrical components included within the power supply circuitry are designed to prevent high energy signals from propagating to the fluid being measured by the system.

7. The system of claim 5, wherein the analog circuitry further comprises the transmitter and the receiver.

8. The system of claim 5, wherein the digital logic further comprises a processor, wherein the processor further comprises:

logic configured to initiate the transmitter for sending the excitation electromagnetic pulse; and

logic configured to synchronize the receiver to the transmit pulse.

9. The system of claim 8, wherein initiating of the transmitter for sending the excitation electromagnetic pulse is performed by a clock signal from the processor, wherein the same clock signal is sent to the receiver.

10. The system of claim 8, wherein the processor further comprises logic configured to determine temperature of the fluid by measuring actual dielectric constant of the fluid and comparing the measured actual dielectric constant of the fluid to a list of fluids having known dielectric constant values.

11. The system of claim 8, further comprising a thermistor for determining temperature of the fluid, wherein the processor is capable of determining the dielectric constant of the fluid and correlating the dielectric constant to temperature of the fluid.

12. The system of claim 8, wherein the processor further comprises logic configured to determine level of the fluid via use of time of flight of the excitation electromagnetic pulse to the end of the elongated portion.

13. The system of claim 8, wherein the processor is capable of determining dielectric constant of the fluid, where temperature of the fluid is known, the processor further comprising:

logic configured to measure perceived length of the elongated portion immersed in the fluid; and

logic configured to calculate the dielectric constant of the fluid from a ratio of the perceived length and a real length of the elongated portion having the fluid therein.

14. The system of claim 8, wherein the processor further comprises:

logic configured to determine a current level of fluid; and

logic configured to track current fluid level by maintaining the current fluid level within a scan window, wherein timing of the scan window is adjusted to keep the current level of the fluid within the window.

15. The system of claim 1, further comprising a low pass filter and associated logic for varying amplitude of the excitation electromagnetic pulse to compensate for variation of signal due to diode variation.

16. The system of claim 1, wherein the arm is in the shape of an S.

17. The system of claim 1, wherein the arm is a coaxial cable.

18. The system of claim 1, wherein the system further comprises a connector for connecting the system to circuitry of an aircraft.

19. The system of claim 1, wherein the elongated portion, arm, and sensor comprise components that reduce radiation susceptibility or transmission.

20. A system for accurately measuring fluid level in a vessel, comprising:

an elongated portion being a coaxial tube having a hollow center; and

a sensor comprising a transmitter capable of creating and transmitting an excitation electromagnetic pulse for traversing the elongated portion, and a receiver for receiving reflected pulses,

wherein shape of the elongated portion created a waveguide for an electromagnetic pulse provided by the sensor.

21. A method of accurately measuring fluid level in a vessel via use of an apparatus with a transmission line and a sensor, wherein the sensor comprises a transmitter capable of creating and transmitting an excitation electromagnetic pulse for traversing the transmission line, and an aliasing sampling receiver for converting high speed reflected waveforms into a slower speed “

equal time”

waveform for processing by use of a method comprising the steps of;

scanning a length of the transmission line that is placed partially or fully in fluid to see where the fluid resides along the transmission line, also referred to as the current fluid level;

tracking the fluid level by identifying fluid level detection points within the slower speed “

equal time”

waveform output by a scan window of the aliasing sampling receiver; and

adjusting the aliasing sampling receiver scan window to track on the detection points within the equal time representation of the pulse reflection,

where the detection points in the reflection waveform represent position in the pulse reflection waveform representing a fluid level.

22. The method of claim 21, wherein the method of accurately measuring fluid level is instead used to detect an additional point of interest on the slower speed time waveform.

23. The method of claim 22, wherein the additional point of interest is an end portion of the transmission line.