JP5630807B2 - Electromagnetic flow meter - Google Patents

Description

  The present invention relates to an electromagnetic flow meter for measuring the flow rate of a fluid flowing in an intermittent pulsating flow from a metering pump.

  As the name suggests, the metering pump has a certain amount of quantification, but in reality there are differences in the discharge rate for each product, and there is a change in the discharge rate over time, so the flow rate is measured. There was a request to do. On the other hand, the applicant of the present application has previously proposed an electromagnetic flow meter for measuring the flow rate of fluid flowing in an intermittent pulsating flow from a metering pump (see, for example, Patent Document 1).

JP 2008-286540 A (paragraph [0025], FIG. 2)

  By the way, the inventor of the present application has intensively studied to develop an electromagnetic flow meter for accurately measuring the flow rate of fluid flowing as an intermittent pulsating flow. When the fluid is discharged by a metering pump, A pulsation noise component is generated between a pair of detection electrodes regardless of the presence or absence of magnetic flux, and the pulsation noise component is superimposed on a true flow rate proportional to the fluid flow velocity and detected between the pair of detection electrodes. It was found that an error occurred in the actually measured flow rate (see FIG. 5).

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electromagnetic flow meter capable of accurately measuring the flow rate of fluid flowing as an intermittent pulsating flow by a metering pump. .

The electromagnetic flowmeter according to the invention of claim 1 made to achieve the above object has a pair of detection electrodes opposed to each other in a measurement flow channel in which a fluid flows as an intermittent pulsating flow from a metering pump. In addition, an electromagnetic flowmeter that applies magnetic flux to the fluid in the measurement flow path from the electromagnetic coil disposed on the side of the measurement flow path and detects the flow rate of the fluid based on the potential difference generated between the pair of detection electrodes. , A pulsating state discriminating means for discriminating between a residence period in which the fluid in the measuring channel does not flow and a flowing period in which one pulse of fluid flows in the measuring channel, and discrimination by the pulsating state discriminating unit based on the results, to reverse the direction of the magnetic flux in each dwell period, and a coil excitation control means for varying alternating the orientation of the magnetic flux for each flow period, and you calculating the flow rate sum of the multiple pulse component rollers It has the characteristics.
The electromagnetic flowmeter according to the invention of claim 2 is provided with a pair of detection electrodes opposed to each other in a measurement flow path in which fluid flows as an intermittent pulsating flow from a metering pump, and on the side of the measurement flow path. In an electromagnetic flowmeter that applies a magnetic flux to a fluid in a measurement channel from a disposed electromagnetic coil and detects a flow rate of the fluid based on a potential difference generated between a pair of detection electrodes, the fluid in the measurement channel is Based on the result of discrimination by the pulsating flow state discriminating means and the pulsating flow state discriminating means for discriminating between the non-flowing residence period and the flow period during which one pulse of fluid flows in the measurement channel, Coil excitation control means that reverses the direction of the magnetic flux and alternately changes the direction of the magnetic flux every flow period, calculates the arithmetic average of the flow rate for every even number of pulsating flow, and the arithmetic average It is characterized in that the flow rate of the fluid is calculated by integrating.
The electromagnetic flowmeter according to the invention of claim 3 is provided with a pair of detection electrodes opposed to each other in a measurement flow channel in which fluid flows as an intermittent pulsating flow from a metering pump, and on the side of the measurement flow channel. In an electromagnetic flowmeter that applies a magnetic flux to a fluid in a measurement channel from a disposed electromagnetic coil and detects a flow rate of the fluid based on a potential difference generated between a pair of detection electrodes, the fluid in the measurement channel is Based on the result of discrimination by the pulsating flow state discriminating means and the pulsating flow state discriminating means for discriminating between the non-flowing residence period and the flow period during which one pulse of fluid flows in the measurement channel, Coil excitation control means that reverses the direction of the magnetic flux and alternately changes the direction of the magnetic flux for each flow period, calculates the sum of the flow rate for every even number of pulsating flow, and sums the sum It is characterized by calculating the flow rate of fluid.

According to a fourth aspect of the present invention, in the electromagnetic flowmeter according to any one of the first to third aspects, the pulsating flow state determining means outputs the metering pump a predetermined time before the discharge operation. It is characterized in that it is configured to discriminate between a residence period and a flow period upon receiving a trigger signal.

The electromagnetic flowmeter according to the invention of claim 5 is provided with a pair of detection electrodes opposed to each other in a measurement flow channel in which fluid flows as an intermittent pulsating flow from a metering pump, and on the side of the measurement flow channel. A magnetic flux is applied to the fluid in the measurement channel from the arranged electromagnetic coil, and the number of pulsating flows of the fluid is counted in an electromagnetic flow meter that detects the flow rate of the fluid based on a potential difference generated between a pair of detection electrodes. and pulsating counting means for, based on the count result of the pulsating counting means, and a coil excitation control means for inverting the direction of the magnetic flux for each flow preset predetermined plurality pulsating number of times of the fluid, multiple pulse having said combined partial flow to the you calculation time.

[Inventions of Claims 1 to 3 ]
The electromagnetic flowmeter according to any one of claims 1 to 3, wherein the pulsating flow state determining means determines a residence period in which the fluid in the measurement channel does not flow and a flow period in which one pulse of fluid flows in the measurement channel, Based on the determination result by the pulsating flow state determination means, the coil excitation control means reverses the direction of the magnetic flux during each staying period, and alternately changes the direction of the magnetic flux for each flow period. Here, the noise component generated between the pair of detection electrodes regardless of the presence or absence of magnetic flux is a flow rate increasing noise component that increases the flow rate detected when the magnetic flux is directed in one direction, more than the true flow rate. On the other hand, it becomes a flow rate reduction noise component that reduces the flow rate detected when the magnetic flux is directed in the other direction than the true flow rate. The electromagnetic flow meter according to claim 1 is the sum of the flow rates for a plurality of pulses, that is, the flow rate for a predetermined pulse number detected when the magnetic flux is directed in one direction, and the magnetic flux is directed in the other direction. By calculating the sum of the flow rates for the same number of pulses detected at the same time, the flow rate increase noise component and the flow rate decrease noise component for the same number of pulses can be canceled. Further, the electromagnetic flow meter according to claim 2 calculates the arithmetic average of the flow rate for every continuous even number of pulsating flows, integrates the arithmetic average, and calculates the flow rate of the fluid, thereby obtaining the same pulse number. The flow rate increase noise component and the flow rate decrease noise component can be offset. In addition, the electromagnetic flow meter according to claim 3 calculates the sum of the flow rate for every continuous even number of pulsating flows, adds the sum and calculates the flow rate of the fluid, thereby increasing the flow rate by the same pulse number. The noise component and the flow rate reduction noise component can be offset. By these, it is possible to accurately measure the flow rate of a fluid flowing in a intermittent pulsating flow by a metering pump.

[Invention of claim 4 ]
According to the invention of claim 4 , even when the interval of the discharge operation of the metering pump changes irregularly, the direction of the magnetic flux can be reliably reversed during the staying period.

[Invention of claim 5 ]
The electromagnetic flow meter according to claim 5 counts the pulsating flow of the fluid with the pulsating flow counting means, and changes the direction of the magnetic flux every time a predetermined number of pulsating flows flow based on the count result. Invert. Here, the noise component generated between the pair of detection electrodes regardless of the presence or absence of magnetic flux is a flow rate increasing noise component that increases the flow rate detected when the magnetic flux is directed in one direction, more than the true flow rate. On the other hand, it becomes a flow rate reduction noise component that reduces the flow rate detected when the magnetic flux is directed in the other direction than the true flow rate. Then, the sum of the flow rate for the multiple pulsating flow times detected when the magnetic flux is directed in one direction and the flow rate for the same multiple pulsating flow times detected when the magnetic flux is directed in the other direction is calculated. By doing so, it is possible to cancel the flow rate increase noise component for the number of times of multiple pulsating flows and the flow rate decrease noise component for the same number of times of pulsating flows. This makes it possible to accurately measure the flow rate of the fluid that flows as an intermittent pulsating flow by the metering pump.

Schematic diagram of electromagnetic flow meter and metering pump according to first embodiment of the present invention Block diagram of metering pump and electromagnetic flow meter (A) Graph showing time change of magnetic flux, (B) Graph showing time change of flow velocity, (C) Graph showing time change of true flow rate, (D) Graph showing time change of pulsation noise component, (E ) Graph showing the time variation of magnetic flux (A) Graph showing time change of magnetic flux, (B) Graph showing time change of flow velocity, (C) Graph showing time change of true flow rate, (D) Graph showing time change of pulsation noise component. Conceptual diagram of a flow signal containing pulsation noise components

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, a metering pump 40 is provided in the middle of a pipeline 51 extending from the liquid tank 50. The metering pump 40 is, for example, a known diaphragm-type electromagnetic metering pump, and the liquid stored in the liquid tank 50 is discharged by a certain amount by the reciprocating motion of the diaphragm 44 (see FIG. 2).

  As shown in FIG. 2, the metering pump 40 includes a timing generation circuit 41 that outputs a trigger signal X1 that causes a discharge operation of the diaphragm 44, a diaphragm drive circuit 42 that drives the diaphragm 44 based on the trigger signal X1, and a timing generator. A delay circuit 43 is provided for inputting the trigger signal X1 output from the circuit 41 to the diaphragm drive circuit 42 after a predetermined time T10 (see FIG. 3) has been set. That is, the metering pump 40 outputs the trigger signal X1 only a predetermined time T10 before the diaphragm 44 starts the discharge operation. Then, each time the trigger signal X1 is output, the diaphragm 44 is discharged only once, and a constant amount of liquid is sent in an intermittent pulsating flow every time. The output interval of the trigger signal X1 (liquid discharge interval) can be arbitrarily set.

  In order to measure the flow rate of the liquid flowing in an intermittent pulsating flow from the metering pump 40, the electromagnetic flow meter 10 according to the present invention is provided on the downstream side of the metering pump 40 in the pipeline 51. . As shown in FIG. 2, the electromagnetic flow meter 10 includes a detector 20 and a converter 30.

  The detector 20 includes a measurement tube 21 through which the liquid discharged from the metering pump 40 flows, an electromagnetic coil 22 that applies magnetic flux across the measurement channel 21A in the measurement tube 21 from the side of the measurement tube 21, and a measurement. A pair of detection electrodes 23, 23 fixed to the tube 21 and disposed opposite to each other in a direction orthogonal to the direction of magnetic flux and liquid flow in the measurement channel 21 </ b> A are provided.

  On the other hand, the converter 30 includes a control circuit 31 (corresponding to the “pulsating flow state determination means” of the present invention) to which the trigger signal X1 from the metering pump 40 is input, and an excitation circuit that controls the excitation current Ie flowing through the electromagnetic coil 22. 32 (corresponding to the “coil excitation control means” of the present invention), a sampling circuit 33 for acquiring a potential difference generated between the pair of detection electrodes 23 and 23 as a flow signal, and a flow signal acquired by the sampling circuit 33 is acquired. A signal processing circuit 34 for performing arithmetic processing is provided.

  When an exciting current Ie is passed through the electromagnetic coil 22 and a liquid flows in a state perpendicular to the magnetic flux in a state where the magnetic flux is applied to the liquid in the measuring tube 21, the liquid flow velocity is increased between the pair of detection electrodes 23 and 23. A proportional potential difference occurs. Based on the potential difference, the signal processing circuit 34 calculates the flow velocity and flow rate.

  Here, an almost constant pulsation noise component is generated between the pair of detection electrodes 23 and 23 each time an ejection operation occurs regardless of the presence or absence of magnetic flux (see FIG. 3D). That is, the actual flow rate (potential difference) detected between the pair of detection electrodes 23 and 23 when the liquid flows in a pulsating manner in the measurement channel 21A is a true flow rate (true potential difference) proportional to the flow velocity. FIG. 3C) is a pulsation noise component superimposed. Note that the pulsation noise component is presumed to be generated because the potential balance between the pair of detection electrodes 23 and 23 changes due to a sudden change of the liquid from the stationary state to the flowing state.

  The converter 30 includes an external output terminal (not shown), and the flow rate calculation result can be output to the outside by connecting a display 52 (see FIG. 1) and other external devices. Further, by connecting to the metering pump 40, the calculation result of the flow rate can be used for feedback control of the metering pump 40.

  The configuration of the electromagnetic flow meter 10 of the present embodiment is as described above. Next, the operation and effect of the present embodiment will be described with reference to FIG.

  When the metering pump 40 is activated, the timing generation circuit 41 outputs the trigger signal X1 before a predetermined time T10 before the discharge operation of the diaphragm 44 (see FIG. 3A). That is, the trigger signal X1 is input to the diaphragm drive circuit 42 via the delay circuit 43, and the diaphragm 44 performs the discharge operation only once after a predetermined time T10 from the output timing of the trigger signal X1. A fixed amount of liquid is discharged by this single discharge operation, and the liquid flows in the measurement flow path 21A over a predetermined flow period T11 (see FIG. 3B).

  On the other hand, the trigger signal X1 is also output to the control circuit 31 provided in the electromagnetic flow meter 10. The control circuit 31 outputs a drive command to the excitation circuit 32, the sampling circuit 33, and the signal processing circuit 34 immediately after receiving the trigger signal X1.

  As soon as the excitation circuit 32 receives the drive command from the control circuit 31, the excitation circuit 32 causes the excitation current Ie to flow in one direction with respect to the electromagnetic coil 22. Thereby, the magnetic flux which crosses the measurement flow path 21A in one direction is generated. As shown in FIG. 3A, the excitation current Ie is allowed to flow for a predetermined power supply period T12 starting from the output timing of the trigger signal X1. In addition, the power supply period T12 is longer than one flow period T11.

  Here, as shown in FIG. 3E, a predetermined period T14 (hereinafter referred to as “transient response period T14”) immediately after the start of supply of the excitation current Ie and immediately after the stop of supply (immediately after the start and end of the power supply period T12). The magnitude of the excitation current Ie, that is, the strength of the magnetic flux gradually changes due to the influence of the inductance and the like of the electromagnetic coil 22. Magnetic potential differential noise (so-called “90 degree noise”) proportional to a change in the magnitude (magnetic flux intensity) of the excitation current Ie can be superimposed on the potential difference generated between the detection electrodes 23 and 23 during the transient response period T14. .

  In order to eliminate the influence of magnetic flux differential noise, in the electromagnetic flow meter 10 of the present embodiment, a period excluding the transient response period T14 in the power feeding period T12, that is, the magnetic flux is held in a constant direction and a constant intensity. The length of the power supply period T12 and the predetermined time T10 per time are set in advance so that the flow period T11 for one pulse falls within the steady period T13 (see FIGS. 3A and 3B).

  The sampling circuit 33 has a potential difference (flow rate signal) generated between the pair of detection electrodes 23 and 23 when a predetermined time T10 has elapsed from the output timing of the trigger signal X1 (that is, simultaneously with the discharge operation of the diaphragm 44). And sampling is continued for the same period as the flow period T11.

  As shown in FIG. 3 (B), after the liquid for one pulse flows in the measurement tube 21, the residence time T15 during which the liquid does not flow in the measurement channel 21A is set for a while. During this dwell period T15, the electromagnetic flow meter 10 reverses the direction of the magnetic flux traversing the measurement flow path 21A.

  That is, when the dwell period T15 is reached, the changeover switch 35 (see FIG. 2) provided in the excitation circuit 32 is switched, and thereafter, when the next trigger signal X1 for causing the diaphragm 44 to perform the next discharge operation is input, the electromagnetic coil 22 is entered. On the other hand, the exciting current Ie flows in the direction opposite to the previous time. Thereby, the direction of the magnetic flux crossing the measurement flow path 21A is opposite to the previous direction. Then, starting from the output of the trigger signal X1, the diaphragm 44 performs the discharge operation at the timing described above, and the sampling circuit 33 samples the potential difference generated between the pair of detection electrodes 23 and 23. Hereinafter, every time the trigger signal X1 is received, that is, every flow period T11 for one pulse, the excitation circuit 32 alternately changes the direction of the magnetic flux, and the potential difference between the pair of detection electrodes 23, 23 is changed in each flow period T11. Sampling.

  The signal processing circuit 34 integrates the measured potential difference of each flow period T11 sampled by the sampling circuit 33, calculates the flow rate for one measured pulse in each flow period T11, and outputs a plurality of flows in the plurality of flow periods T11. The integrated flow rate is calculated by integrating the flow rate of the pulse.

  Specifically, the direction of the magnetic flux is opposite to each other and the sum of the actually measured flow rates detected in two continuous flow periods T11 and T11 is calculated, and the combination of the two flow periods T11 and T11 for calculating the sum Are sequentially shifted one by one to calculate the arithmetic mean, and the average value is added to the previous integrated flow rate. More specifically, after starting the metering pump 40, the sum of the flow rates detected in the first and second flow periods T11 and T11 is calculated to obtain an integrated flow rate, and then the second and third flow periods. The average of the flow rates detected at T11 and T11 is calculated and added to the previous integrated flow rate, and then the average of the flow rates detected during the third and fourth flow periods T11 and T11 is calculated and the previous integrated flow rate is calculated. The calculation process is repeated every time a pulsating flow is generated.

  By the way, when the sum of the flow rates of the two pulses detected in the two flow periods T11 and T11 in which the directions of the magnetic fluxes are opposite to each other as described above is calculated, as a result, in each of the flow periods T11 and T11. Thus, the pulsation noise components N1 and N1 included in each detected flow rate can be canceled out. The reason will be described below.

  FIG. 3B is a conceptual diagram showing the change over time of the actual flow velocity in the measurement flow path 21A, and FIG. 3C shows noise between the pair of detection electrodes 23 and 23 with respect to the actual flow velocity. FIG. 4D is a conceptual diagram of the time change of the true flow rate (true potential difference) detected when it is assumed that no occurrence occurs. FIG. 4D shows the time of the pulsation noise component generated between the pair of detection electrodes 23, 23. It is a conceptual diagram which shows a change.

  As shown in FIG. 3C, when it is assumed that no noise occurs in the pair of detection electrodes 23, 23, the true flow rate detected between the pair of detection electrodes 23, 23 in each flow period T11 ( The potential difference is proportional to the flow velocity (see FIG. 5B) during each flow period T11. In the electromagnetic flow meter 10 of the present embodiment, the direction of the magnetic flux crossing the measurement flow path 21A is alternately reversed between one direction and the other direction for each flow period T11. , 23, the sign of the potential difference between them is alternately inverted every flow period T11.

  By the way, the flow rate (potential difference) actually detected by the pair of detection electrodes 23, 23 is not simply a value proportional to the flow rate as shown in FIG. A pulsation noise component (see FIG. 4D) is superimposed on the flow rate (true potential difference).

  Here, the true flow rate proportional to the flow velocity shown in FIG. 3C is set to “R1”, “R2”, “R3”, “R4” in order from the oldest flow period T11, and FIG. As shown in the figure, assuming that a pulsation noise component that is almost constant every time generated in each flow period T11 is “N1”, in the first flow period T11 in which the magnetic flux is directed in one direction, the pulsation noise with respect to the true flow rate R1. Since the component N1 has the same sign, the detected flow rate can be expressed as “R1 + N1”. On the other hand, in the second flow period T11 in which the magnetic flux is directed in the other direction, since the pulsation noise component N1 has an opposite sign with respect to the true flow rate R2, the detected flow rate can be expressed as “R2-N1”.

  That is, the flow rate detected in the first flow period T11 in which the magnetic flux is directed in one direction is a value larger by the pulsation noise component N1 than the true flow rate R1, and the second flow period in which the magnetic flux is directed in the other direction. The flow rate detected at T11 is smaller by a pulsation noise component N1 than the true flow rate R2. Here, the pulsation noise component N1 generated when the magnetic flux is directed in one direction is the “flow rate increasing noise” of the present invention, which increases the flow rate detected between the pair of detection electrodes 23, 23 from the true flow rate. The pulsation noise component N1 generated when the magnetic flux is directed in the other direction corresponds to the “component” and reduces the flow rate detected between the pair of detection electrodes 23, 23 from the true flow rate. Corresponds to the “flow reduction noise component”.

  When the sum of the flow rates of two pulses detected in the first and second flow periods T11 and T11 “(R1 + N1) + (R2−N1)” is calculated, the first and second flows are obtained. The pulsation noise components N1 and N1 (that is, the flow increase noise component and the flow decrease noise component) included in the flow rates detected in the first flow periods T11 and T11 are canceled out, and the first and second flow periods. A sum “R1 + R2” of true flow rates at T11 and T11, that is, an integrated flow rate is calculated.

  Similarly to the first flow period T11, the flow rate detected in the third flow period T11 in which the magnetic flux is directed in one direction can be expressed as “R3 + N1”. That is, the flow rate detected in the third flow period T11 includes the pulsation noise component N1 as the flow rate increase noise component, and is a value larger than the true flow rate R3 by the pulsation noise component N1. When the sum of the flow rates of the two pulses detected in the second and third flow periods T11 and T11 “(R2−N1) + (R3 + N1)” is calculated, the second and third times are obtained as a result. The pulsation noise components N1 and N1 (flow rate increase noise component and flow rate decrease noise component) included in each flow rate detected in each flow period T11 and T11 are canceled out, and true in each flow period T11 and T11 for the second time and the third time. The sum of the flow rates of “R2 + R3” is calculated. The average value “(R2 + R3) / 2” obtained by dividing the sum of the true flow rates (that is, the sum of the flow rates detected between the pair of detection electrodes 23 and 23) by 2 was flown in the third flow period T11. By adding to the previous integrated flow rate “R1 + R2” as the flow rate, the integrated flow rate at the end of the third flow period T11 is calculated.

  Further, the flow rate detected in the fourth flow period T11 in which the magnetic flux is directed in the other direction as in the second flow period T11 can be expressed as “R4-N1”. That is, the flow rate detected in the fourth flow period T11 includes the pulsation noise component N1 as the flow rate reduction noise component, and is a value smaller than the true flow rate R4 by the pulsation noise component N1. Then, by calculating the sum “(R3 + N1) + (R4−N1)” of the flow rates of the two pulses detected in the third and fourth flow periods T11 and T11, the third and fourth times are obtained. The pulsation noise components N1 and N1 (flow rate increase noise component and flow rate decrease noise component) included in each flow rate detected in the respective flow periods T11 and T11 are canceled, and the third and fourth flow periods T11 and T11 are canceled out. The sum of the true flow rates at “R3 + R4” is calculated. The average value “(R2 + R3) / 2” obtained by dividing the sum of the true flow rates (that is, the sum of the flow rates detected between the pair of detection electrodes 23 and 23) by 2 was flown in the fourth flow period T11. As the flow rate, by adding to the previous integrated flow rate, the integrated flow rate at the end of the fourth flow period T11 is calculated.

  Similarly, every time a new flow period T11 (pulsating flow) occurs, the sum of the flow rates for the two pulses detected in the latest flow period T11 and the previous flow period T11 is calculated, and the flow rate in the combination is calculated. Is added to the integrated flow rate at the end of the previous flow period T11 (pulsating flow). That is, the integrated flow rate is added for each pulse.

  As described above, the electromagnetic flow meter 10 of the present embodiment quantifies the residence period T15 in which the liquid in the measurement channel 21A does not flow and the flow period T11 in which one pulse of liquid flows in the measurement channel 21A. The pump 40 determines by receiving a trigger signal X1 that is output only a predetermined time T10 before the discharge operation, and the excitation circuit 32 reverses the direction of the magnetic flux during each stay period T15, and the direction of the magnetic flux. Are alternately changed for each flow period T11. Here, regardless of the presence or absence of magnetic flux, the pulsation noise component N1 generated between the pair of detection electrodes 23 and 23 has a flow rate detected when the magnetic flux is directed in one direction from the true flow rates R1 and R3. The flow rate increase noise component is also increased, while the flow rate detected when the magnetic flux is directed in the other direction is a flow rate decrease noise component that decreases the true flow rates R2 and R4. The sum of the flow rates of a plurality of pulses (in this embodiment, 2 pulses), that is, the flow rate of a predetermined number of pulses (one pulse) detected when the magnetic flux is directed in one direction, and the magnetic flux The flow increase noise component and the flow decrease noise component for the same number of pulses are canceled out by calculating the sum of the flow rate for the same number of pulses (one pulse) that is detected when the head is directed in the other direction. be able to. This makes it possible to accurately measure the flow rate of the fluid that flows as an intermittent pulsating flow by the metering pump 40.

[Second Embodiment]
In the first embodiment, the direction of the magnetic flux is reversed every time the liquid for one pulse flows. However, in this embodiment, a predetermined number of pulsations (for example, three pulses in the present embodiment). Minute), the magnetic flux is reversed. The other configuration is the same as that of the first embodiment, and a duplicate description is omitted.

  The control circuit 31 provided in the electromagnetic flow meter 10 is configured to output a drive command to the excitation circuit 32 once every time the trigger signal X1 is input a predetermined predetermined number of times (three times). 32 switches the changeover switch 35 every time a drive command is input. Here, the control circuit 31 corresponds to the “pulsating flow counting means” of the present invention.

  When the magnetic flux is directed in the other direction, the flow rate corresponding to a plurality of pulsating flows (three pulses) including the pulsation noise component N1 as the flow increase noise component detected when the magnetic flux is directed in one direction, and the magnetic flux is directed in the other direction. By calculating the sum of the flow rate for a total of 6 pulses including the same multiple pulsation frequency count (3 pulsations) including the pulsation noise component N1 as the flow rate reduction noise component detected in (3), the multiple pulsation frequency count (3 It is possible to cancel out the flow rate increase noise component (pulse amount) and the flow rate decrease noise component corresponding to the same plural number of pulsating flows (for three pulses). The configuration of this embodiment also has the same effect as the first embodiment. Note that the predetermined number of pulsating flows is not limited to three.

[Other Embodiments]
The present invention is not limited to the above-described embodiment. For example, the embodiments described below are also included in the technical scope of the present invention, and various other than the following can be made without departing from the scope of the invention. It can be changed and implemented.

  (1) In the first embodiment, the sum of the flow rate for one pulse including the pulsation noise component N1 as the flow rate increase noise component and the flow rate for one pulse including the pulsation noise component N1 as the flow rate decrease noise component is calculated. The pulsation noise components N1 and N1 included in the respective flow rates are canceled out, and the flow rate for the plurality of pulses including the flow rate increase noise component and the flow rate for the same plurality of pulses including the flow rate decrease noise component are calculated. May be calculated to cancel the pulsating noise components N1 and N1.

  (2) In the first embodiment, the sum of the flow rates of two consecutive pulses with reversed magnetic flux is calculated, and the combination of the two pulsating flows for calculating the sum is sequentially shifted one by one. The integrated flow rate is added for each pulse. For example, the sum of the flow rates in the 11th to 20th flow periods T11 is added to the sum of the flow rates in the 1st to 10th flow periods T11, and the 21st to 30th times. The sum of the flow rates in each flow period T11 is integrated, the sum of the flow rates in the 31st to 40th flow periods T11 is integrated, and so on. The integrated flow rate may be added for each pulse.

  (3) In the first embodiment, the electromagnetic flow meter 10 is configured to start excitation in response to the trigger signal X1 from the metering pump 40. However, the potential difference between the pair of detection electrodes 23 and 23 is determined in advance. It may be determined that the flow period T11 has shifted to the dwell period T15 when the value is equal to or less than the set predetermined value, and excitation may be started during the dwell period T15.

  (4) In addition, if the metering pump 40 discharges liquid at a constant cycle, the electromagnetic flow meter 10 is provided with a time measuring means, and the magnetic flux is generated at a predetermined time interval based on the discharge cycle of the metering pump 40. The direction may be reversed.

  (5) In the first and second embodiments, the non-excitation period is provided before and after the direction of the magnetic flux is reversed. However, the direction of the magnetic flux may be reversed without providing the non-excitation period.

  (6) The length of the sampling period by the sampling circuit 33 and the flow period T11 do not have to be the same, and the length of the sampling period may be not less than the length of the flow period T11 and not more than the length of the steady period T13. .

DESCRIPTION OF SYMBOLS 10 Electromagnetic flowmeter 21A Measurement flow path 22 Electromagnetic coil 23, 23 Detection electrode 31 Control circuit 32 Excitation circuit 40 Metering pump T11 Flow period T15 Residence period X1 Trigger signal

Claims (5)

A pair of detection electrodes are arranged opposite to each other in a measurement flow path in which a fluid flows as an intermittent pulsating flow from a metering pump, and an electromagnetic coil disposed on the side of the measurement flow path allows the measurement flow path to enter the measurement flow path. In an electromagnetic flowmeter that applies a magnetic flux to the fluid of the fluid and detects the flow rate of the fluid based on a potential difference generated between the pair of sensing electrodes.
A pulsating flow state discriminating means for discriminating a residence period in which the fluid in the measurement channel does not flow and a flow period in which one pulse of fluid flows in the measurement channel;
Coil excitation control means for reversing the direction of the magnetic flux during each stay period based on the determination result by the pulsating flow state determination means, and alternately changing the direction of the magnetic flux for each flow period,
Electromagnetic flow meter, wherein the benzalkonium to calculating the flow rate sum of the multiple pulse min. A pair of detection electrodes are arranged opposite to each other in a measurement flow path in which a fluid flows as an intermittent pulsating flow from a metering pump, and an electromagnetic coil disposed on the side of the measurement flow path allows the measurement flow path to enter the measurement flow path. In an electromagnetic flowmeter that applies a magnetic flux to the fluid of the fluid and detects the flow rate of the fluid based on a potential difference generated between the pair of sensing electrodes.
A pulsating flow state discriminating means for discriminating a residence period in which the fluid in the measurement channel does not flow and a flow period in which one pulse of fluid flows in the measurement channel;
Coil excitation control means for reversing the direction of the magnetic flux during each stay period based on the determination result by the pulsating flow state determination means, and alternately changing the direction of the magnetic flux for each flow period,
An electromagnetic flow meter that calculates an arithmetic average of flow rates for every even number of continuous pulsating flows, and calculates the flow rate of the fluid by integrating the arithmetic averages. A pair of detection electrodes are arranged opposite to each other in a measurement flow path in which a fluid flows as an intermittent pulsating flow from a metering pump, and an electromagnetic coil disposed on the side of the measurement flow path allows the measurement flow path to enter the measurement flow path. In an electromagnetic flowmeter that applies a magnetic flux to the fluid of the fluid and detects the flow rate of the fluid based on a potential difference generated between the pair of sensing electrodes.
A pulsating flow state discriminating means for discriminating a residence period in which the fluid in the measurement channel does not flow and a flow period in which one pulse of fluid flows in the measurement channel;
Coil excitation control means for reversing the direction of the magnetic flux during each stay period based on the determination result by the pulsating flow state determination means, and alternately changing the direction of the magnetic flux for each flow period,
An electromagnetic flowmeter that calculates a sum of flow rates for every even number of continuous pulsating flows, and calculates the flow rate of the fluid by adding the sums. The pulsating flow state determining means is configured to receive the trigger signal output by the metering pump a predetermined time before the discharge operation and determine the staying period and the flow period. The electromagnetic flow meter according to any one of claims 1 to 3, wherein the electromagnetic flow meter is characterized in that A pair of detection electrodes are arranged opposite to each other in a measurement flow path in which a fluid flows as an intermittent pulsating flow from a metering pump, and an electromagnetic coil disposed on the side of the measurement flow path allows the measurement flow path to enter the measurement flow path. In an electromagnetic flowmeter that applies a magnetic flux to the fluid of the fluid and detects the flow rate of the fluid based on a potential difference generated between the pair of sensing electrodes.
Pulsating flow counting means for counting the number of pulsating flows of the fluid;
Coil excitation control means for reversing the direction of the magnetic flux every time a predetermined number of pulsating flow times flows based on the counting result by the pulsating flow counting means,
  An electromagnetic flowmeter that calculates the sum of the flow rates of multiple pulses.