US 3,943,765 AGranted

Electromagnetic flow meter

AssigneeTokyo Shibaura Electric Co., Ltd.

InventorsKeisuke Takada, Ryouji Gamo, Ikuo Sato

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Abstract

An electromagnetic flow meter comprising a circuit for generating signals proportional to the intensity of an A.C. magnetic field impressed on a fluid running through a pipe; a first switch rendered conducting for a prescribed period simultaneously with an A.C. voltage obtained in proportional to the period of the A.C. magnetic field; a second switch actuated after the conduction of the first switch; a circuit for integrating outputs corresponding to the flow rate of a fluid obtained through the first switch and further integrating said outputs with an opposite polarity; a circuit for rendering the second switch nonconducting when an output from said integration circuit reaches a referential level; and a circuit for generating an output corresponding to the period in which said outputs are integrated, for each operating cycle of said integration circuit.

Claims13

Dependent claims

An electromagnetic flow meter comprising a pipe for conducting a fluid;

a magnetic flux generator for applying an A.C. magnetic flux to a fluid traveling through the pipe;
a detection circuit fitted to the pipe so as to generate a detection signal proportional to a product arrived at by multiplying together the inner diameter of the pipe, the density of the A.C. magnetic flux and the running speed of the fluid;
a device for generating an A.C. voltage proportional to the A.C. magnetic flux;
a first switch supplied with the detection signal;
a first switch-controlling circuit for closing the first switch for at least a positive or negative half period of the generated A.C. voltage;
an A.C.-D.C. converting circuit for converting said A.C. voltage to a D.C. voltage;
a second switch to which an output from said A.C.-D.C. converting circuit is supplied with an opposite polarity to the detection signal;
an integration circuit for integrating outputs from the first switch and thereafter integrating outputs from the second switch;
a second switch-controlling circuit for closing the second switch after said positive or negative half period and opening the second switch when an output from the integration circuit reaches a referential level;
and an output device for producing an output indicating the flow rate of the fluid corresponding to the period in which outputs from the A.C.-D.C. converting circuit are integrated, for each operating cycle of said integration circuit.

7 more elements

An electromagnetic flow meter comprising a pipe for conducting a fluid;

an A.C. source;
a magnetic flux generator connected to the A.C. source to apply an A.C. magnetic flux to a fluid traveling through the pipe;
a detection circuit fitted to the pipe to generate a detection signal proportional to a product arrived at by multiplying together the inner diameter of the pipe, the density of the A.C. magnetic flux and the running speed of the fluid;
a transformer connected to the A.C. source;
a device connected to the secondary winding of the transformer to generate an A.C. voltage in proportional to the A.C. magnetic flux;
a first switch supplied with the detection signal;
a second switch connected to the secondary winding of the transformer;
a first integration circuit connected to the first switch;
a second integration circuit connected to the second switch;
a third switch supplied with an output signal from the second integration circuit;
means for connecting the output terminal of the third switch to the input terminal of the first integration circuit;
a first switch-controlling circuit for closing the first switch for half the period of the A.C. voltage generated;
a second switch-controlling circuit for closing the third switch immediately after said half period in which the first switch is closed;
gate-signal generating means for giving forth a gate signal for the period in which an output signal from the first integration circuit reaches a prescribed level after the closing of the third switch;
a second gate circuit opened upon receipt of the gate signal;
a clock pulse generator for supplying clock pulses to the first gate circuit;
means for impressing a D.C. voltage on the second gate circuit;
and an output device supplied with digital and analogue output signals denoting the flow rate of a liquid from the output terminals of the first and second gate circuits.

15 more elements

An electromagnetic flow meter comprising a pipe for conducting a fluid;

a magnetic flux generator for applying an A.C. magnetic flux to a fluid traveling through a pipe;
a detection circuit fitted to the pipe so as to generate a detection signal proportional to a product arrived at by multiplying together the inner diameter of the pipe, the density of the A.C. magnetic flux and the velocity of the fluid running through the pipe;
an A.C. voltage generator for generating an A.C. voltage in synchronization with the A.C. magnetic flux;
a first switch supplied with the detection signal;
a second switch supplied with the A.C. voltage;
a first switch-controlling circuit for closing the first and second switches for at least a positive or negative half period of the generated A.C. voltage;
first and second integration circuits for integrating outputs from the first and second switches respectively;
an inverter connected to the output terminal of the first switch-controlling circuit;
a delay circuit connected to the output terminal of the inverter;
an integration-controlling circuit for zeroing integrated outputs from the first and second integration circuits;
a multiplier-divider supplied with outputs x and y from the first and second integration circuits and an output z from a power source for generating an output having a referential voltage and designed to carry out the arithmetic operation of said three outputs by the formula of x.sup.. z/y;
and an output device for producing an output indicating the flow rate of the fluid passing through the pipe from an output from the multiplier-divider.

9 more elements

Dependencies are inferred from the claim text.