Method for operating a flowmeter and flowmeter

Patent metadata

Field	Value
Publication number	US-12196597-B2
Application number	US-202217804952-A
Country	US
Kind code	B2
Filing date	Jun 1, 2022
Priority date	Jun 2, 2021
Publication date	Jan 14, 2025
Grant date	Jan 14, 2025

Abstract

A method for operating a flowmeter is disclosed. The flowmeter has a sensor for capturing a measured variable indicating the flow, and for converting the measured variable into a signal. The flowmeter also has a control and evaluation unit that determines a flow measurement value for the flow from the signal and outputs an output value representing the flow measurement value. The method includes: determining flow measurement values; forming smoothed flow measurement values over a plurality of flow measurement values, respectively; and activating a low flow cut-off. When the low flow cut-off is activated, the output value is set to zero if: the current smoothed flow measurement value is below a first predetermined limit value; and a predetermined number of flow measurement values has been determined with deactivated low flow cut-off or a predetermined number of smoothed flow measurement values has been formed with deactivated low flow cut-off.

First claim

The invention claimed is:

1. A method for operating a flowmeter, comprising:
determining flow measurement values for a measured variable of a flow;
forming smoothed flow measurement values, each over a respective plurality of the flow measurement values;
outputting a respective output value for each of the flow measurement values;
setting each respective output value to a current value of the flow measurement values when a low flow cut-off is in a deactivated state;
transitioning the low flow cut-off from the deactivated state to an activated state only if both of the following conditions are met:
a current value of the smoothed flow measurement values is below a first predetermined limit value; and
a predetermined number of the flow measurement values has been determined while the low flow cut-off is in the deactivated state or a predetermined number of the smoothed flow measurement values has been formed while the low flow cut-off is in the deactivated state; and

setting each respective output value to zero when the low flow cut-off is in the activated state.

2. The method according to claim 1 , wherein each of the smoothed flow measurement values is formed by forming a mean value; and
wherein the mean value is a simple moving average, an exponential moving average, a weighted moving average, an arithmetic mean value, or a harmonic mean value.

3. The method according to claim 2 , wherein the predetermined number of the smoothed flow measurement values corresponds to a number of the flow measurement values included in the plurality of flow measurement values over which smoothing is performed.

4. The method according to claim 1 , wherein the first predetermined limit value is formed by a low flow limit value minus a first tolerance value.

5. The method according to claim 1 , wherein, in a correction step, a zero point correction of the flowmeter is carried out when the low flow cut-off is in the activated state.

6. The method according to claim 1 , wherein the following additional method steps are carried out:
determining or retrieving the reaction time of the low flow cut-off;
determining the flow rate after deactivation of the low flow cut-off over the period of the reaction time of the low flow cut-off; and
adding the flow rate determined over the period of the reaction time to an initial value.

7. The method according to claim 6 , wherein the flow rate determined over the period of the reaction time is divided into a plurality of flow rate subsets.

8. A method for operating a flowmeter, comprising:
determining flow measurement values for a measured variable of a flow;
forming smoothed flow measurement values, each over a respective plurality of the flow measurement values;
outputting a respective output value for each of the flow measurement values;
setting each respective output value to zero when a low flow cut-off is in an activated state;
transitioning the low flow cut-off from the activated state to a deactivated state when either of the following two conditions is satisfied:
a current value of the smoothed flow measurement values is above a second predetermined limit value; or
a current value of the flow measurement values is above a third predetermined limit value; and

setting each respective output value to a current value of the flow measurement values when the low flow cut-off is in the deactivated state.

9. The method according to claim 8 , wherein the second predetermined limit value is formed from a low flow limit value plus a first tolerance value.

10. The method according to claim 8 , wherein the third predetermined limit value is formed from a low flow limit value plus a second tolerance value.

11. A flowmeter for determining a flow rate of a medium, comprising:
a sensor for detecting a measured variable indicating the flow rate, wherein the sensor converts the measured variable into a sensor signal; and
a control and evaluation unit, wherein the control and evaluation unit determines a flow measurement value for the flow rate from the sensor signal and outputs an output value representing the flow measurement value;
wherein the control and evaluation unit is designed to carry out the following method steps in the operating state of the flowmeter:
determining flow measurement values;
forming smoothed flow measurement values, each over a respective plurality of the flow measurement values;
outputting a respective output value for each of the flow measurement values;
setting each respective output value to a current value of the flow measurement values when a low flow cut-off is in a deactivated state;
transitioning the low flow cut-off from the deactivated state to an activated state only if both of the following conditions are met:
a current value of the smoothed flow measurement values is below a first predetermined limit value; and
a predetermined number of the flow measurement values has been determined while the low flow cut-off is in the deactivated state or a predetermined number of the smoothed flow measurement values has been formed while the low flow cut-off is in the deactivated state; and

setting each respective output value to zero when the low flow cut-off is in the activated state.

12. The flowmeter according to claim 11 , wherein the control and evaluation unit is further designed to carry out at least one of the following method steps in the operating state of the flowmeter:
forming each of the smoothed flow measurement values by forming a simple moving average, an exponential moving average, a weighted moving average, an arithmetic mean value, or a harmonic mean value;
forming the first predetermined limit value by a low flow limit value minus a first tolerance value;
a correction step, in which a zero point correction of the flowmeter is carried out when the low flow cut-off is in the activated state;
determining or retrieving a reaction time of the low flow cut-off;
determining the flow rate after deactivation of the low flow cut-off over the period of the reaction time of the low flow cut-off; and
adding the flow rate determined over the period of the reaction time to the initial value.

13. A flowmeter for determining a flow rate of a medium, comprising:
a sensor for capturing a measured variable indicating the flow, wherein the sensor converts the measured variable into a sensor signal; and
a control and evaluation unit, wherein the control and evaluation unit determines a flow measurement value for the flow from the sensor signal and outputs an output value representing the flow measurement value;
wherein the control and evaluation unit is designed in such a way that, in the operating state of the flowmeter, the control and evaluation unit carries out the following method steps:
determining of flow measurement values for a measured variable of a flow;
forming smoothed flow measurement values, each over a respective plurality of flow measurement values;
outputting a respective output value for each of the flow measurement values;
setting each respective output value to zero when a low flow cut-off is in an activated state; transitioning the low flow cut-off from the activated state to a deactivated state when one of the following two conditions is met:
a current value of the smoothed flow measurement values is above a second predetermined limit value; or
a current value of the flow measurement values is above a third predetermined limit value; and

setting each respective output value to a current value of the flow measurement values when the low flow cut-off is in the deactivated state.

14. The flowmeter according to claim 1

Assignees

• Krohne Ag

Inventors

• Den Haan Arthur

Classifications

• G01F25/0092

  for metering by volume · CPC title

• G01F25/10

  of flowmeters · CPC title

• G01F25/14 Primary

  using a weighing apparatus · CPC title

• G01F1/00 Primary

  Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow (measuring a proportion of the volume flow G01F5/00) · CPC title

• G01F15/06 Primary

  Indicating or recording devices · CPC title