Mass flow meter having an oscillation sensor and method for eliminating noise signals from the measurement signal

• US 20070255534A1
• Filed: 04/25/2007
• Published: 11/01/2007
• Est. Priority Date: 04/27/2006
• Status: Active Grant

• Current Assignee: ABB AG (ABB Limited)
• Original Assignee: ABB Patent GmbH (ABB Limited)
• Inventors: Keese, Dieter, Blume, Thomas
• Granted Patent: US 7,783,434 B2
• Time in Patent Office: Days
• US Class Current: 702/189
• CPC Class Codes: G01F 1/8422 exciters
• CPC Class Codes: G01F 1/8436 signal processing
• CPC Class Codes: G01F 1/8472 having curved measuring conduits, i.e. whereby the measuring conduits' curved center line lies within a plane G01F1/8481 takes precedence

Abstract

Mass flow meter having at least one measurement tube, through which mass flows, as an oscillation body which can be set in mechanical oscillation by means of an excitation unit, the oscillation behavior of which varying as a function of the mass flow can be recorded via at least one oscillation sensor in order to determine the mass flow, wherein in order to eliminate noise signals from the measurement voltage (se_n) recorded via the oscillation sensor computational technology means are provided for forming a complex conjugate spectrum (|sa_1j|) from the spectrum of the excitation voltage (se_D) as well as a vector product between this (|sa_1j|) and the measurement voltage (se_n) for the purpose of filtering, in order, by further computational technology means for inverse Fourier transformation, to obtain the signal relationship associated with the vector product between the excitation voltage (se_D) and the measurement voltage (se_n) so that the processed measurement voltage (sa_l) resulting therefrom then predominantly comprises a useful signal component.

Claims

1. A mass flow meter having at least one measurement tube, through which mass flows, as an oscillation body which can be set in mechanical oscillation by means of an excitation unit, the oscillation behavior of which varying as a function of the mass flow can be recorded via at least one oscillation sensor in order to determine the mass flow, wherein in order to eliminate noise signals from the measurement voltage (se_n) recorded via the oscillation sensor computational technology means are provided for forming a complex conjugate spectrum (|sa_1j|) from the spectrum of the excitation voltage (se_D) as well as a vector product between this (|sa_1j|) and the measurement voltage (se_n) for the purpose of filtering, in order, by further computational technology means for inverse Fourier transformation, to obtain the signal relationship associated with the vector product between the excitation voltage (se_D) and the measurement voltage (se_n) so that the processed measurement voltage (sa₁) resulting therefrom then predominantly comprises useful signal component.

2. The mass flow meter as claimed in claim 1, wherein the phase relation between the excitation voltage (se_D) and the filtered measurement voltage (se_n) is in terms of signal processing technology a measure of the flow value freed from the noise signal.

3. The mass flow meter as claimed in claim 1, wherein the frequency ratio between the excitation voltage (se_D) and the filtered measurement voltage (se_n) is a measure of the noise-free density of the medium to be measured.

4. The mass flow meter as claimed in claim 1, wherein computational technology means are provided for noise-free determination of the flow rate of the medium to be measured.

5. The mass flow meter as claimed in claim 1, wherein the excitation voltage (se_D) driving the excitation unit for oscillatory excitation of the measurement tube is sinusoidal.

6. The mass flow meter as claimed in claim 5, wherein the excitation voltage (se_D) driving the excitation unit has a frequency in the range of from 50 Hz to 200 Hz.

11. The mass flow meter as claimed in claim 3, wherein computational technology means are provided for noise-free determination of the flow rate of the medium to be measured.

12. The mass flow meter as claimed in claim 4, wherein the excitation voltage (se_D) driving the excitation unit for oscillatory excitation of the measurement tube is sinusoidal.

13. The mass flow meter as claimed in claim 6, wherein the excitation voltage (se_D) driving the excitation unit has a frequency of about 100 Hz.

7. A method for eliminating noise signals from the measurement voltage (se_n) of an oscillation sensor in flow meters, comprising the computation steps:

forming the complex conjugate spectrum (|sa_1j|) from the spectrum of the excitation voltage (se_D),

forming the vector product between the complex conjugate spectrum (|sa_1j|) and the measurement voltage (se_n) for the purpose of filtering,

carrying out an inverse Fourier transformation in order to evaluate the signal relationship, associated with the vector product, between the excitation voltage (se_D) and the measurement voltage (se_n), so that the processed measurement voltage (sa₁) resulting therefrom then comprises useful signal component.

8. An electronic computation unit for processing the measurement signal obtained via an oscillation sensor of a flow meter, having computational technology means for carrying out the method as claimed in claim 7.

9. The electronic computation unit as claimed in claim 8, wherein the computational technology means are designed in the form of at least one microcontroller having at least one assigned memory unit.

10. A computer program product for an electronic computation unit as claimed in claim 9, the method for eliminating the noise signals being implemented by corresponding control instructions contained in software.

14. A computer program product for an electronic computation unit, which can be operated according to a method as claimed in claim 7, the method for eliminating the noise signals being implemented by corresponding control instructions contained in software for execution by at least one microcontroller having at least one assigned memory unit.

15. A mass flow meter comprising:

at least one measurement tube, through which mass flows, as an oscillation body which can be set in mechanical oscillation by means of an excitation unit;

an excitation unit which can be set in mechanical oscillation to the mass flow as an oscillation body;

at least one oscillation sensor to record the oscillation behavior of the mass flow; and

computational technology means provided to eliminate noise signals from a measurement voltage (se_n) recorded via the oscillation sensor to form a complex conjugate spectrum (|sa_1j|) from a spectrum of an excitation voltage (se_D) as well as a vector product between this (|sa_ij|) and the measurement voltage (se_n) for the purpose of filtering to obtain the signal relationship associated with the vector product between the excitation voltage (se_D) and the measurement voltage (se_n) so that a processed measurement voltage (sa) results therefrom.