US 2012/0059601 A1 · SIGNAL PROCESSING METHOD, SIGNAL PROCESSING APPARATUS, AND CORIOLIS FLOWMETER

Abstract

[Object] To provide a signal processing apparatus which may always perform measurement with constant precision and performs phase measurement with high filtering performance and a small amount of computation even when a temperature of a fluid to be measured changes, air bubbles are mixed into the fluid to be measured, or the fluid to be measured rapidly changes from a gas to a liquid. [Solving Means] In a Coriolis flowmeter in which at least one flow tube or a pair of flow tubes which is included in a measurement flow tube is operated by a driving device using a vibrator to alternately drive the at least one flow tube or the pair of flow tubes, and a phase difference and/or a vibration frequency proportional to a Coriolis force acting on the at least one flow tube or the pair of flow tubes are/is detected by a velocity sensor or an acceleration sensor which is a vibration detection sensor when the at least one flow tube or the pair of flow tubes is vibrated, to thereby obtain a mass flow rate and/or density of a fluid to be measured, the signal processing apparatus includes: a transmitter (90) for transmitting and outputting a modulatable frequency signal; a frequency conversion unit (85) for performing frequency conversion to add (or subtract) an output frequency (FX) of the transmitter (90) to (or from) an input frequency from input signals of the phase difference and/or the vibration frequency proportional to the Coriolis force acting on the pair of flow tubes, which is detected by an electromagnetic pick-off, and controlling the transmitter (90) so that frequency values after the frequency conversion are constant; and a phase difference measurement section (95) for measuring a phase difference between frequency signals converted by and output from the frequency conversion unit (85). [Selected Drawing] FIG. 1

Claims17

Dependent claims

A signal processing method for a Coriolis flowmeter in which at least one flow tube or a pair of flow tubes which is included in a measurement flow tube is operated by a driving device using a vibrator to alternately drive the at least one flow tube or the pair of flow tubes, and a phase difference and/or a vibration frequency proportional to a Coriolis force acting on the at least one flow tube or the pair of flow tubes are/is detected by two velocity sensors or two acceleration sensors which are vibration detection sensors when the at least one flow tube or the pair of flow tubes is vibrated, to thereby obtain a mass flow rate and/or density of a fluid to be measured,

the signal processing method being characterized by comprising:
performing frequency conversion to combine an arbitrary oscillation frequency to each of two flow rate signals obtained by A/D conversion on input signals of the phase difference and/or the vibration frequency proportional to the Coriolis force acting on the at least one flow tube or the pair of flow tubes, which are detected by the two velocity sensors or the two acceleration sensors;
measuring a frequency of a composite waveform associated with at least one of the vibration detection sensors;
transmitting a control signal based on the measured frequency;
controlling so that a sum frequency component or a difference frequency component of a composite component of a composite frequency signal is constant;
and
measuring phases from a sum signal or a difference signal of each of controlled converted composite frequencies, to thereby obtain a phase difference signal component.

4 more elements

A signal processing apparatus for a Coriolis flowmeter in which at least one flow tube or a pair of flow tubes which is included in a measurement flow tube is operated by a driving device using a vibrator to alternately drive the at least one flow tube or the pair of flow tubes, and a phase difference and/or a vibration frequency proportional to a Coriolis force acting on the at least one flow tube or the pair of flow tubes are/is detected by a velocity sensor or an acceleration sensor which is a vibration detection sensor when the at least one flow tube or the pair of flow tubes is vibrated, to thereby obtain a mass flow rate and/or density of a fluid to be measured,

the signal processing apparatus being characterized by comprising:
a transmitter for transmitting and outputting a modulatable frequency signal;
a frequency conversion section for performing frequency conversion to add (or subtract) an output frequency (FX) of the transmitter to (or from) an input frequency detected by the velocity sensor or the acceleration sensor and performing frequency shifting so that frequency values obtained by the frequency conversion are constant;
and
a phase difference measurement section for measuring a phase difference between frequency signals converted by and output from the frequency conversion unit.

2 more elements

A signal processing apparatus for a Coriolis flowmeter in which at least one flow tube or a pair of flow tubes which is included in a measurement flow tube is operated by a driving device using a vibrator to alternately drive the at least one flow tube or the pair of flow tubes, and a phase difference and/or a vibration frequency proportional to a Coriolis force acting on the at least one flow tube or the pair of flow tubes are/is detected by a pair of velocity sensors or a pair of acceleration sensors which are vibration detection sensors when the at least one flow tube or the pair of flow tubes is vibrated, to thereby obtain a mass flow rate and/or density of a fluid to be measured,

the signal processing apparatus being characterized by comprising:
a transmitter for transmitting and outputting a modulatable frequency signal;
a first frequency conversion section for performing frequency conversion to add (or subtract) an output frequency output from the transmitter to (or from) an input signal frequency obtained by converting a signal of one of the pair of vibration detection sensors into a digital signal by a first A/D converter;
a second frequency conversion section for performing frequency conversion to add (or subtract) the output frequency output from the transmitter to (or from) an input signal frequency obtained by converting a signal of another of the pair of vibration detection sensors into a digital signal by a second A/D converter;
and
a phase difference measurement section for measuring a phase difference between a first frequency signal converted by and output from the first frequency conversion section and a second frequency signal converted by and output from the second frequency conversion.

3 more elements

A signal processing apparatus for a Coriolis flowmeter in which at least one flow tube or a pair of flow tubes which is included in a measurement flow tube is operated by a driving device using a vibrator to alternately drive the at least one flow tube or the pair of flow tubes, and a phase difference and/or a vibration frequency proportional to a Coriolis force acting on the at least one flow tube or the pair of flow tubes are/is detected by a pair of vibration detection sensors which are vibration detection sensors when the at least one flow tube or the pair of flow tubes is vibrated, to thereby obtain a mass flow rate and/or density of a fluid to be measured,

the signal processing apparatus being characterized by comprising:
a transmitter for transmitting and outputting a modulatable frequency signal;
a first frequency conversion section for shifting in frequency, to a constant frequency signal, an input signal frequency obtained by converting a signal of one velocity sensor of the pair of vibration detection sensors into a digital signal by a first A/D converter and output from the first A/D converter, based on an output frequency output from the transmitter to move the input signal frequency to another frequency band;
a second frequency conversion section for shifting in frequency, to a constant frequency signal, an input signal frequency obtained by converting a signal of another velocity sensor of the pair of vibration detection sensors into a digital signal by a second A/D converter and output from the second A/D converter, based on the output frequency from the transmitter to move the input signal frequency to another frequency band;
a frequency measurement section for measuring a frequency of a first frequency signal which is obtained by conversion as the constant frequency signal and output from the first frequency conversion section, and outputting a measured frequency value of the first frequency signal to the transmitter to control output frequencies from the first frequency conversion section and the second frequency conversion section so that a frequency obtained by the frequency conversion section by frequency conversion on an input frequency obtained by converting, into a digital signal, by the first A/D converter, an input frequency of a velocity sensor signal from the one of the pair of vibration velocity sensors, is a desired frequency;
and
a phase difference measurement section for measuring a phase difference between the first frequency signal obtained by conversion as the constant frequency signal, which is output from the first frequency conversion section, and the second frequency signal obtained by conversion as the constant frequency signal, which is output from the second frequency conversion section.

4 more elements

A Coriolis flowmeter in which at least one flow tube or a pair of flow tubes which is included in a measurement flow tube is operated by a driving device using a vibrator to alternately drive the at least one flow tube or the pair of flow tubes, and a phase difference and/or a vibration frequency proportional to a Coriolis force acting on the at least one flow tube or the pair of flow tubes are/is detected by a pair of velocity sensors or a pair of acceleration sensors which are vibration detection sensors when the at least one flow tube or the pair of flow tubes is vibrated, to thereby obtain a mass flow rate and/or density of a fluid to be measured,

the Coriolis flowmeter being characterized by comprising a signal processing apparatus comprising:
a transmitter for transmitting and outputting a modulatable frequency signal;
a first frequency conversion section for shifting in frequency, to a specified constant frequency signal, an input signal frequency (θ) obtained by converting a signal of one velocity sensor of the pair of vibration detection sensors into a digital signal by a first A/D converter, based on an output frequency (θXn) output from the transmitter to move the input signal frequency (Aθ) to a desired frequency band;
a second frequency conversion section for shifting in frequency, to a specified constant frequency signal, an input signal frequency (θ) obtained by converting a signal of another velocity sensor of the pair of vibration detection sensors into a digital signal by a second A/D converter, based on the output frequency (θXn) output from the transmitter to move the input signal frequency (θ) to a desired frequency band;
a frequency measurement section for measuring a frequency of a first frequency signal which is obtained by conversion as the specified constant frequency signal and output from the first frequency conversion section, and outputting a measured frequency value of the first frequency signal to the transmitter to control output frequencies so that a frequency after frequency conversion by the frequency conversion section is always a constant frequency;
and
a phase difference measurement section for measuring a phase difference between the first frequency signal obtained by conversion as the specified constant frequency signal, which is output from the first frequency conversion section, and the second frequency signal obtained by conversion as the specified constant frequency signal, which is output from the second frequency conversion section,
the signal processing apparatus providing the phase difference between the first frequency signal obtained by conversion as the specified constant frequency signal, which is output from the first frequency conversion section, and the second frequency signal obtained by conversion as the specified constant frequency signal, which is output from the second frequency conversion section.

5 more elements

Dependencies are inferred from the claim text.

Signal processing method, signal processing apparatus, and coriolis flowmeter

Life of this patent

Signal processing method, signal processing apparatus, and coriolis flowmeter

Life of this patent

Abstract

Claims17