Coriolis frequency tracking

Patent metadata

Field	Value
Publication number	US-9995613-B2
Application number	US-201414268802-A
Country	US
Kind code	B2
Filing date	May 2, 2014
Priority date	Mar 7, 2007
Publication date	Jun 12, 2018
Grant date	Jun 12, 2018

Abstract

Motion is induced in a conduit such that the conduit vibrates in a major mode of vibration having a major amplitude and a minor mode of vibration having a minor amplitude. The major amplitude is larger than the minor amplitude, the major mode of vibration has a first frequency of vibration and the minor mode of vibration has a second frequency of vibration, and the minor mode of vibration interferes with the major mode of vibration to cause a beat signal having a frequency related to the first frequency of vibration and the second frequency of vibration. The frequency of the beat signal is determined, and the second frequency of vibration is determined based on the determined frequency of the beat signal.

First claim

What is claimed is:

1. A Coriolis flowmeter comprising:
a conduit configured to receive a fluid flowing through the conduit;
a driver positioned to drive motion of the conduit, the motion of the conduit including a driven mode of vibration and a Coriolis mode of vibration when the fluid is flowing through the conduit, the driver driving the conduit in the driven mode of vibration and the Coriolis mode of vibration arising from forces associated with the fluid flowing through the conduit while the driver is driving the conduit in the driven mode of vibration;
a first sensor positioned to sense motion of the conduit at a first location and output a first sensor signal indicative of the motion of the conduit at the first location;
a second sensor positioned to sense motion of the conduit at a second location and output a second sensor signal indicative of the motion of the conduit at the second location, the second location being different from the first location; and
a controller configured to:
operate the driver;
determine a frequency of the Coriolis mode of vibration based on a beat frequency produced by interaction between the driven mode of vibration and the Coriolis mode of vibration while the driver is driving motion of the conduit and the fluid is flowing through the conduit; and
determine a mass flow rate of the fluid flowing through the conduit based on the determined frequency of the Coriolis mode of vibration.

2. A Coriolis flowmeter as set forth in claim 1 wherein said controller is further configured to determine a beat signal by analyzing amplitudes of the first and second sensor signals, the beat frequency being the frequency of the beat signal.

3. A Coriolis flowmeter as set forth in claim 2 wherein said controller is further configured to determine the beat frequency by: (i) determining a first time at which the amplitude of the beat signal has a predefined value and a second time at which the amplitude of the beat signal has the predefined value; (ii) determining a difference between the first and second times; and (3) determining the beat frequency based on said difference.

4. A Coriolis flowmeter as set forth in claim 3 wherein the predefined value is zero.

5. A Coriolis flowmeter as set forth in claim 4 wherein the first time is at first occurrence of the predefined value and the second time is at a second occurrence of the predefined value, and the first and second occurrences are nonconsecutive occurrences of the predefined value.

6. A Coriolis flowmeter as set forth in claim 1 wherein using the beat frequency to determine the frequency of the Coriolis mode comprises determining a difference between the beat frequency and a frequency of the driven mode.

7. A Coriolis flowmeter as set forth in claim 3 wherein using the beat frequency to determine the frequency of the Coriolis mode comprises determining a difference between the beat frequency and a frequency of the driven mode.

8. A Coriolis flowmeter as set forth in claim 7 wherein the first time is at first occurrence of the predefined value and the second time is at a second occurrence of the predefined value, and the first and second occurrences are nonconsecutive occurrences of the predefined value.

Assignees

• Invensys Sys Inc
• Schneider Electric Systems Usa Inc

Inventors

• Henry Manus P
• Duta Mihaela D
• Tombs Michael S

Classifications

• G01F1/8436

  signal processing · CPC title

• G01F15/024

  involving digital counting · CPC title

• G01F1/8486

  with multiple measuring conduits · CPC title

• G01F1/849 Primary

  having straight measuring conduits · CPC title

• G01N9/002

  using variation of the resonant frequency of an element vibrating in contact with the material submitted to analysis (G01N9/34 takes precedence) · CPC title