US 10,295,386 B2Granted

Electromagnetic flow meter

AssigneeAzbil Corporation

InventorsVince Dooley, Yoshihiko Okayama, Shinsuke Matsunaga, Ichiro Mitsutake

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Abstract

An electromagnetic flow meter includes a measurement tube, an excitation coil, an excitation current supplying unit supplying an excitation current with an excitation frequency fex to the excitation coil, a pair of electrodes disposed inside the measurement tube, a measuring unit measuring a flow based on an emf that arises between the electrodes, a first A/D converting unit that converts the emf to a digital signal, a sampling unit sampling the digital signal, a noise evaluation value calculating unit, based on at least the sample data sampled by the sampling unit, calculating as a noise evaluation value the magnitude of the impact of a noise component owing to adherence of foreign matter to the electrodes upon the measurement of the flow, and an electrode scaling diagnosing unit determining an electrode foreign matter adherence state by comparing the noise evaluation value and a predetermined diagnostic threshold value.

Claims12

Dependent claims

An electromagnetic flow meter, comprising:

a measurement tube comprising a flowing fluid;
an excitation coil;
an excitation current supply supplying an excitation current with an excitation frequency fex to the excitation coil;
a pair of electrodes disposed inside the measurement tube;
a flow meter based on an emf that arises between the electrodes;
a first A/D converter converting the emf to a digital signal;
a sampler sampling the digital signal within a prescribed period;
a first integrating calculator calculating as a first integrated value a value calculated by integrating the absolute values of all frequency components of the sample data sampled by the sampler for a prescribed interval;
a high frequency components filter extracting frequency components of the frequency components of the sample data sampled by the sampler for the prescribed interval that are greater than or equal to a prescribed frequency, which is higher than the excitation frequency fex;
a second integrating calculator calculating as a second integrated value a value calculated by integrating the absolute values of the extracted frequency components that are greater than or equal to the prescribed frequency;
a noise evaluation value calculator calculating, based on at least the sample data sampled by the sampler, as a noise evaluation value, the magnitude of the impact of a noise component owing to adherence of foreign matter to the electrodes upon the measurement of the flow, and calculating as a high frequency ratio (HR) the ratio of the second integrated value, which is calculated by the second integrating calculator, to the first integrated value, which is calculated by the first integrating calculator;
an electrode scaling diagnostic determining an electrode foreign matter adherence state by comparing the noise evaluation value and a predetermined diagnostic threshold value;
and
a scaling diagnosis output outputting the determined electrode foreign matter adherence state.

11 more elements

An electromagnetic flow meter, comprising:

a measurement tube comprising a flowing fluid;
an excitation coil;
an excitation current supply supplying an excitation current with an excitation frequency fex to the excitation coil;
a pair of electrodes disposed inside the measurement tube;
a flow meter based on an emf that arises between the electrodes;
a first A/D converter converting the emf to a digital signal;
a sampler sampling the digital signal within a prescribed period;
a first integrating calculator calculating as a first integrated value a value calculated by integrating the absolute values of all frequency components of the sample data sampled by the sampler for a prescribed interval;
a high frequency components filter extracting frequency components of the frequency components of the sample data sampled by the sampler for the prescribed interval that are greater than or equal to a prescribed frequency, which is higher than the excitation frequency fex;
a second integrating calculator calculating as a second integrated value a value calculated by integrating the absolute values of the extracted frequency components that are greater than or equal to the prescribed frequency;
a noise evaluation value calculator calculating, based on at least the sample data sampled by the sampler, as a noise evaluation value, the magnitude of the impact of a noise component owing to adherence of foreign matter to the electrodes upon the measurement of the flow, and calculating as a high frequency ratio (HR) the ratio of the second integrated value, which is calculated by the second integrating calculator, to the first integrated value, which is calculated by the first integrating calculator;
an electrode scaling diagnostic determining an electrode foreign matter adherence state by comparing the noise evaluation value and a predetermined diagnostic threshold value using the high frequency ratio (HR) as the noise evaluation value;
and
a scaling diagnosis output outputting the determined electrode foreign matter adherence state.

11 more elements

Dependencies are inferred from the claim text.