Coriolis mass flow meter and method for determining variables influencing the total zero point error of the meter, method for determining the total zero point error and operating method for same

Patent metadata

Field	Value
Publication number	US-12449292-B2
Application number	US-202118258921-A
Country	US
Kind code	B2
Filing date	Nov 26, 2021
Priority date	Dec 22, 2020
Publication date	Oct 21, 2025
Grant date	Oct 21, 2025

Abstract

A method for determining variables influencing a total zero point error of a Coriolis mass flow meter comprises: exciting a vibration of a bending vibration mode; measuring a first total zero point error T at a flow of zero; ascertaining a first damping value D of the vibration of the bending vibration mode; measuring an exciter-independent zero point error I during a decaying vibration of the bending vibration mode at a flow of zero; ascertaining a first exciter-dependent contribution E to the first total zero point error T based on the first total zero point error T and based on the exciter-independent zero point error I; and ascertaining a sensitivity factor S for the bending vibration mode based on the first exciter-dependent contribution E to the total zero point error T and based on the first damping value D.

First claim

The invention claimed is:

1. A method for determining variables influencing a total zero point error of a Coriolis mass flow meter comprising: at least one measuring tube mounted so as to be able to vibrate, for conducting a medium; an exciter for exciting a bending vibration mode; at least two vibration sensors for detecting vibrations of the measuring tube; and at least one measuring and operating circuit for driving the exciter, for detecting sensor signals of the vibration sensors and for ascertaining a mass flow measurement value as a function of the sensor signals, wherein the method comprises:
exciting a vibration of a bending vibration mode of the measuring tube;
measuring a first total zero point error with a first medium in the measuring tube at a flow of zero;
ascertaining a first damping value of the vibration of the bending vibration mode with the first medium in the measuring tube;
measuring an exciter-independent zero point error during a decaying vibration of the bending vibration mode with the first medium in the measuring tube at a flow of zero;
ascertaining a first exciter-dependent contribution to the first total zero point error based on the first total zero point error and based on the exciter-independent zero point error; and
ascertaining a sensitivity factor for the bending vibration mode based on the first exciter-dependent contribution to the total zero point error and based on the first damping value.

2. The method of claim 1 , wherein ascertaining the first damping value comprises forming a quotient of an excitation current for exciting the vibration and the vibration amplitude achieved therewith.

3. The method of claim 1 , wherein ascertaining the first damping value comprises ascertaining a time constant of the decaying vibration of the bending vibration mode.

4. The method of claim 1 , wherein ascertaining the first exciter-dependent contribution to the first total zero point error comprises forming a difference between the first total zero point error and the exciter-independent zero point error.

5. The method of claim 1 , wherein ascertaining the sensitivity factor comprises dividing the first exciter-dependent contribution to the first total zero point error by the first damping value.

6. The method of claim 1 , further comprising ascertaining an updated exciter-independent zero point error, comprising:
exciting a vibration of a bending vibration mode with a second medium in the measuring tube;
measuring a second total zero point error with the second medium in the measuring tube at a flow of zero;
ascertaining a second damping value with the second medium in the measuring tube;
ascertaining the updated exciter-independent zero point error on the basis of the second total zero point error, the second damping value and the sensitivity factor.

7. The method of claim 6 , further comprising determining a third total zero point error of the Coriolis mass flow meter, wherein the method comprises:
ascertaining a third damping value for a vibration of the bending vibration mode with a third medium in the measuring tube; and
calculating the third total zero point error on the basis of the third damping value and the sensitivity factor for the bending vibration mode and the exciter-independent zero point error.

8. The method of claim 7 , wherein the third total zero point error comprises the sum of the exciter-independent zero point error and a third exciter-dependent contribution to the total zero point error.

9. The method of claim 8 , wherein the third exciter-dependent contribution to the total zero point error comprises a product of the sensitivity factor and the third damping value.

10. A Coriolis mass flow meter comprising: at least one measuring tube mounted so as to be able to vibrate, for conducting a medium; an exciter for exciting a bending vibration mode; at least two vibration sensors for detecting vibrations of the measuring tube; and at least one measuring and operating circuit for driving the exciter, for detecting sensor signals of the vibration sensors and for ascertaining a mass flow measurement value as a function of the sensor signals, wherein the measuring and operating circuit is configured to perform the method of claim 1 .

11. A method for operating a modular Coriolis mass flow meter comprising: at least one measuring tube mounted so as to be able to vibrate, for conducting a medium; an exciter for exciting a bending vibration mode; at least two vibration sensors for detecting vibrations of the measuring tube; and at least one measuring and operating circuit for driving the exciter, for detecting sensor signals of the vibration sensors and for ascertaining a mass flow measurement value as a function of the sensor signals, wherein the Coriolis mass flow meter comprises a base module and a replaceable measuring tube module, wherein the measuring tube module comprises the measuring tube and a first component each of the exciter and of the two vibration sensors, wherein the base module comprises the measuring and operating circuit, a housing with a receptacle for the measuring tube module, and a second component each of the exciter and of the two vibration sensors, wherein the method comprises:
connecting the measuring tube module to the base module so that the first and second components of the exciter and of the two sensors are in each case in an operative position to one another; and
ascertaining a sensitivity factor and an exciter-independent zero point error using a method according to the following method:
exciting a vibration of a bending vibration mode of the measuring tube;
measuring a first total zero point error with a first medium in the measuring tube at a flow of zero;
ascertaining a first damping value of the vibration of the bending vibration mode with the first medium in the measuring tube;
measuring an exciter-independent zero point error during a decaying vibration of the bending vibration mode with the first medium in the measuring tube at a flow of zero;
ascertaining a first exciter-dependent contribution to the first total zero point error based on the first total zero point error and based on the exciter-independent zero point error; and
ascertaining a sensitivity factor for the bending vibration mode based on the first exciter-dependent contribution to the total zero point error and based on the first damping value.

12. The method of claim 11 , further comprising: determining a zero point error by: ascertaining a second damping value for a vibration of the bending vibration mode with a second medium in the measuring tube; and calculating the second total zero point error on the basis of the second damping value and the sensitivity factor for the bending vibration mode and the exciter-independent zero point error.

Assignees

• Flowtec Ag

Inventors

• Zhu Hao
• Bitto Ennio

Classifications

• G01F1/8422

  exciters · CPC title

• G01F25/10

  of flowmeters · CPC title

• G01F1/8436 Primary

  signal processing · CPC title