Electromagnetic flowmeter

Abstract

To measure a magnetic flux or the like leaking from the inside of a detector of an electromagnetic flowmeter, in order to correct a flow rate error, against the background that it is known that a magnetic flux leaks from the inside of a detector although an electromagnetic flowmeter is highly accurate, and techniques for preventing leakage of magnetic flux to the outside and techniques for correcting flow rate errors are therefore available, but nevertheless, leakage of magnetic flux is not still completely prevented although magnetic shields or the like are provided, and further, correction of flow rate errors is difficult to conduct accurately since a degree of magnetic flux leakage cannot be grasped, and thus, there is a need to measure a magnetic flux leaking from the inside of a detector of an electromagnetic flowmeter.SOLUTION: An electromagnetic flowmeter comprises at least one sensor for measuring at least one out of a magnetic flux leaking from the inside of an electromagnetic flowmeter to a pipeline, a magnetic flux density, and magnetic permeability, in between a pipeline and exciting coils that are connected to measure a flow rate.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an electromagnetic flowmeter. [Background technology]

[0002] Electromagnetic flowmeters generate a magnetic field inside a measuring tube by passing an electric current through an excitation coil, measure the electromotive force that is generated in proportion to the flow rate of the conductive fluid flowing inside the measuring tube, and use the measured electromotive force to determine the flow rate. Because they are robust and highly accurate, they are widely used in industrial applications.

[0003] Electromagnetic flowmeters are highly accurate, but it is known that magnetic flux leaks from inside the detector. This reduces the magnetic field in the flow path inside the measurement tube, which in turn reduces the electromotive force, resulting in a negative error in the flow rate.

[0004] Therefore, there are techniques to prevent magnetic flux leakage to the outside, for example, by providing a magnetic shield inside the detector or using a magnetic circuit with high shielding properties. There is also a technique to correct flow rate errors by allowing the user to set parameters that set the magnetic permeability of the pipe connected to measure the flow rate. [Prior art documents] [Non-patent literature]

[0005] [Patent Document 1] JP 2005-172645 A [Patent Document 2] Japanese Patent Application Publication No. 9-145435 [Patent Document 3] Japanese Patent Application Publication No. 5-256674 [Patent Document 4] Japanese Patent Application Publication No. 3-175320 Summary of the Invention [Problem to be solved by the invention]

[0006] However, even if a magnetic shield is provided, it is not possible to completely prevent magnetic flux leakage, and since the degree of magnetic flux leakage cannot be grasped, it is difficult to accurately correct the flow rate error. Therefore, in order to correct the flow rate error, it is necessary to measure the magnetic flux leaking from inside the detector of the electromagnetic flowmeter. Note that the information measured to correct the flow rate error may be magnetic flux density or magnetic permeability in addition to magnetic flux.

[0007] An object of the present invention is to measure magnetic flux leaking from inside a detector of an electromagnetic flowmeter in order to correct flow rate errors. [Means for solving the problem]

[0008] An electromagnetic flowmeter according to one aspect includes at least one sensor between a pipe connected to measure a flow rate and an excitation coil for measuring at least one of magnetic flux leaking from inside the electromagnetic flowmeter into the pipe, magnetic flux density, and magnetic permeability. Effect of the Invention

[0009] According to one embodiment, in order to correct flow rate errors, magnetic flux leaking from inside a detector of an electromagnetic flowmeter can be measured. [Brief description of the drawings]

[0010] [Figure 1] 1 is a diagram showing an example of the configuration of an electromagnetic flowmeter 100 including a magnetic sensor 8 according to the present embodiment. [Diagram 2] FIG. 1 is a diagram showing an example of an electromagnetic flowmeter 100 including a magnetic sensor 8 according to the present embodiment. [Diagram 3] 2 is a diagram showing an example of the inside 13 of a detector of the electromagnetic flowmeter 100 according to the present embodiment. FIG. [Figure 4] FIG. 1 is a diagram showing an example of a case where a magnetic sensor 8 is provided outside the electromagnetic flowmeter 100 according to the present embodiment. [Diagram 5] 4 is a flowchart showing a flow rate measurement process according to the present embodiment. [Figure 6]FIG. 1 is a diagram showing a first modified example of the electromagnetic flowmeter 100 according to the present embodiment. [Figure 7] 3 is a diagram showing an example of a return magnetic path cover 14 according to the present embodiment. FIG. [Figure 8] FIG. 11 is a diagram showing a second modified example of the electromagnetic flowmeter 100 according to the present embodiment. [Figure 9] 3 is a diagram showing an example of a feedback magnetic path sheet 15 according to the present embodiment. FIG. [Figure 10] 4 is a diagram showing a first modified example of the feedback magnetic path sheet 15 according to the present embodiment. FIG. [Figure 11] 5 is a diagram showing another example of the feedback magnetic path sheet 15 according to the present embodiment. FIG. [Figure 12] 1 is a diagram illustrating an example of a hardware configuration of an electromagnetic flowmeter 100 according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Examples of the electromagnetic flowmeter disclosed in the present application will be described in detail below with reference to the drawings. Note that the present invention is not limited to these examples. Also, the same elements are given the same reference numerals, duplicated descriptions are omitted as appropriate, and each embodiment can be appropriately combined within a range that does not cause inconsistency.

[0012] (Configuration of the electromagnetic flowmeter 100) Fig. 1 is a diagram showing a configuration example of an electromagnetic flowmeter 100 including a magnetic sensor 8 according to this embodiment. Fig. 1 shows a cross-sectional view of a piping section 1 of the electromagnetic flowmeter 100, various sensors, and a part of a circuit block connecting the piping section 1 and the various sensors.

[0013] An electromagnetic flowmeter 100 is used to measure the flow rate of a conductive fluid such as tap water. A piping section 1 of the electromagnetic flowmeter 100 shown in Fig. 1 is made of a corrosion-resistant non-magnetic metal such as austenitic stainless steel, and the inside of the piping section 1 is covered with an insulator 2 called a lining material.

[0014] 1, a pair of excitation coils 3a and 3b (hereinafter, sometimes collectively referred to as "excitation coil 3") are provided at the top and bottom of the piping section 1 at positions perpendicular to the pipe axis of the piping section 1, and the excitation coil 3 generates a magnetic field inside the piping section 1. Note that the excitation coil 3 is driven, for example, by an excitation current from an excitation circuit, but is omitted in FIG.

[0015] 1, for example, a pair of electrodes 5a and 5b (hereinafter, sometimes collectively referred to as "electrodes 5") are arranged at a position perpendicular to the axis of the piping section 1 and perpendicular to the installation position of the excitation coil 3. For example, according to Faraday's law of electromagnetic induction, when a flow velocity occurs in the conductive fluid 4 inside the piping section 1, an electromotive force is generated in a direction perpendicular to the magnetic field generated by the excitation coil 3 and perpendicular to the axis of the piping section 1. Therefore, for example, the electromagnetic flowmeter 100 picks up the generated electromotive force with the electrode 5, amplifies a voltage corresponding to the flow rate induced between the electrodes 5a-5b with the amplifier 6 connected to the electrode 5, and takes it into the calculation unit 7.

[0016] 1, the electromagnetic flowmeter 100 of the present embodiment includes a magnetic sensor 8 inside the detector. The magnetic sensor 8 measures, for example, magnetic flux leaking from inside the detector (hereinafter, sometimes referred to as "leakage magnetic flux"). The magnetic sensor 8 is connected to a transmission / reception circuit 9, for example, which controls the timing of transmission and reception from the calculation unit 7 to the magnetic sensor 8 and performs flow rate calculations. The electromagnetic flowmeter 100 of the present embodiment measures the magnetic flux leaking from the detector without providing, for example, a magnetic shield. The electromagnetic flowmeter 100 of the present embodiment corrects a negative error in the flow rate caused by the leakage magnetic flux based on, for example, the measured leakage magnetic flux.

[0017] FIG. 2 is a diagram showing an example of an electromagnetic flowmeter 100 including a magnetic sensor 8 according to the present embodiment. As shown in FIG. 2, the magnetic sensor 8 is installed by welding or the like at a position where it can measure the magnetic flux leaking into a pipe (hereinafter, sometimes referred to as a "counter pipe") that is connected to measure the flow rate, avoiding the excitation coil 3. In the example of FIG. 2, the back side of the flange portion 10 is the connection surface with the counter pipe, and the counter pipe is connected to the connection surface. In order to measure the leakage magnetic flux more accurately, the magnetic sensor 8 is installed at a position close to the counter pipe, such as inside the converter of the flange portion 10. In order to measure the leakage magnetic flux more accurately, the magnetic sensor 8 is installed, for example, between the connection surface with the counter pipe and the excitation coil 3, and is installed at a position where the distance from the excitation coil 3 is the shortest. FIG. 2 shows an example where the magnetic sensor 8 is installed at a position where the distance from the excitation coil 3a is the shortest between the connection surface with the counter pipe and the excitation coil 3 (the 0 o'clock position when the vertical upper side of the flange portion 10 is 0 o'clock). Furthermore, the position where the distance between the exciting coil 3 and the connection surface with the mating pipe and the exciting coil 3 is shortest may be, for example, the position where the distance to the exciting coil 3b is shortest (the 6 o'clock position when the vertical upper side of the flange portion 10 is 0 o'clock). Generally, the flange portion 10 is made of the same non-magnetic metal as the piping portion 1, and does not affect the magnetic flux measured by the magnetic sensor 8.

[0018] The feedback magnetic path 11 is designed to be made of a ferromagnetic material such as iron, and is designed to concentrate the magnetic field generated by the excitation coil 3 in the flow path (inside the measurement tube) through which the conductive fluid 4 passes, as well as to have the effect of a magnetic shield that does not allow the magnetic field generated by the excitation coil 3 to escape to the outside, and is fixed by a fixing member 16. However, for example, when the mating pipe is made of a magnetic pipe material such as carbon steel, a part of the magnetic field concentrated in the flow path may leak to the mating pipe side. For this reason, for example, in order to reduce the magnetic flux leakage as much as possible, it has been common to install a magnetic shield at great cost, but since the magnetic field must pass to the flow path side due to the measurement principle, it is difficult to reduce the magnetic flux leakage to zero. Therefore, in this embodiment, for example, the magnetic sensor 8 is provided inside the detector of the electromagnetic flowmeter 100 to directly measure the magnetic flux leaking from the electromagnetic flowmeter 100, and the flow rate is corrected from the measured leakage magnetic flux. 2, the magnetic sensor 8 is located inside the detector of the electromagnetic flowmeter 100, but in order to show the portion where the magnetic sensor 8 and the exciting coil 3 are installed, a cover that covers this portion is omitted. Therefore, the inside of the detector of the electromagnetic flowmeter 100 will be described with reference to FIG.

[0019] Fig. 3 is a diagram showing an example of the inside 13 of the detector of the electromagnetic flowmeter 100 according to this embodiment. Fig. 3 is a cross-sectional view of an upper portion of the electromagnetic flowmeter 100 shown in Fig. 2, in which the magnetic sensor 8 is installed, viewed from the side with respect to the pipe axis of the piping section 1. As shown in Fig. 3, the inside 13 of the detector of the electromagnetic flowmeter 100 is actually covered with a flange section 10 and a cover 12. Then, for example, the magnetic sensor 8, the excitation coil 3, etc. are installed in the flange section 10 of the inside 13 of the detector.

[0020] The magnetic sensor 8 may be installed outside the electromagnetic flowmeter 100, instead of inside the detector 13 of the electromagnetic flowmeter 100. Fig. 4 is a diagram showing an example of a case where the magnetic sensor 8 is provided outside the electromagnetic flowmeter 100 according to this embodiment. As shown in Fig. 4, the magnetic sensor 8 may be installed outside the electromagnetic flowmeter 100, for example, on a flange portion of the counterpart pipe 200, in order to measure leakage magnetic flux from the electromagnetic flowmeter 100 to the counterpart pipe 200 side. In this case, the magnetic sensor 8 is connected to the converter and the transmission / reception circuit 9 of the electromagnetic flowmeter 100 so as to be able to communicate with each other, for example, by a cable or the like.

[0021] Furthermore, the magnetic sensor 8 may be, for example, a sensor that measures magnetic flux density, such as a gaussmeter, or a sensor that measures magnetic permeability.

[0022] (Processing flow) Next, a description will be given of the flow rate measurement process executed by the electromagnetic flowmeter 100. Fig. 5 is a flowchart showing the flow rate measurement process according to this embodiment.

[0023] First, as shown in Fig. 5, the magnetic sensor 8 connected to and controlled by the electromagnetic flowmeter 100 measures, for example, magnetic flux leaking near a mating pipe connected to measure the flow rate (step S10). The magnetic sensor 8 may be installed, for example, inside the detector 13 of the electromagnetic flowmeter 100 as shown in Fig. 3, or outside the electromagnetic flowmeter 100 as shown in Fig. 4. Also, in step S10, for example, the magnetic flux density or magnetic permeability of the leakage magnetic flux near the mating pipe may be measured using a sensor other than the magnetic sensor 8. In any case, in step S10, at least one of the magnetic flux, magnetic flux density, and magnetic permeability is measured to correct the flow rate.

[0024] Next, the calculation unit 7 of the electromagnetic flowmeter 100 calculates a coefficient (hereinafter referred to as a "correction coefficient") for correcting the flow rate using, for example, the leakage magnetic flux measured in step S10 (step S11). The correction coefficient is calculated, for example, using a relational expression between leakage magnetic flux and flow rate error, or a data table showing the relationship between leakage magnetic flux and correction coefficient, which is recorded in the calculation unit 7. The flow rate characteristic to be corrected may be at least one of, for example, a zero point error, a flow rate span error, and a flow rate non-linear characteristic.

[0025] Next, the calculation unit 7 of the electromagnetic flowmeter 100 detects the magnitude of the electromotive force generated in accordance with the flow velocity of the conductive fluid, for example, using the correction coefficient calculated in step S11 to correct the measured flow rate, and calculates a flow rate that takes into account leakage magnetic flux, etc. (step S12).

[0026] Next, the electromagnetic flowmeter 100 outputs, for example, the flow rate calculated in step S12 via an output unit such as a display (step S13). After execution of step S13, the flow rate measurement process shown in FIG.

[0027] Furthermore, the electromagnetic flowmeter 100 according to this embodiment may include, for example, a feedback magnetic path auxiliary member that assists the function of the feedback magnetic path 11. The feedback magnetic path auxiliary member may be, for example, a feedback magnetic path cover 14 or a feedback magnetic path sheet 15.

[0028] First, the return magnetic path cover 14 will be described. FIG. 6 is a diagram showing another example 1 of the electromagnetic flowmeter 100 according to the present embodiment. The electromagnetic flowmeter 100 shown in FIG. 6 is, for example, compared to the electromagnetic flowmeter 100 shown in FIG. 2, and further includes a return magnetic path cover 14. The return magnetic path cover 14 is, for example, installed on at least one of the outer diameter side and the inner diameter side in the tube axis perpendicular direction of the excitation coil 3, and is one of the return magnetic path auxiliary members that assist the function of the return magnetic path 11. The return magnetic path cover 14 is, for example, installed on the outer diameter side in the tube axis perpendicular direction of the excitation coil 3, and blocks the movement of the magnetic flux of the magnetic field to the outer diameter side. The return magnetic path cover 14 is, for example, installed on the outer diameter side in the tube axis perpendicular direction of the excitation coil 3 so as to be recessed into the gap of the excitation coil 3, and enhances the magnetic field generated by the excitation coil. The return magnetic path cover 14 is, for example, a plate of a ferromagnetic material. The return magnetic path cover 14 will be described more specifically with reference to FIG. 7.

[0029] FIG. 7 is a diagram showing an example of the feedback magnetic path cover 14 according to the present embodiment. As shown in FIG. 7, the feedback magnetic path cover 14 has a structure that is installed, for example, on the outer diameter side of the excitation coil 3 in the direction perpendicular to the tube axis so as to be embedded in the gap between the excitation coil 3. In the example of FIG. 7, the feedback magnetic path cover 14 has a separable structure that is installed so as to cover either one of the pair of excitation coils 3a and 3b. That is, the feedback magnetic path cover 14 shown in the example of FIG. 7 is installed so as to cover both of the pair of excitation coils 3a and 3b using two sets. In addition, the feedback magnetic path cover 14 shown in the example of FIG. 7 has a separable structure for easy installation, for example, but may be composed of one combined part. Note that the feedback magnetic path cover 14 may have a structure that is installed so as to cover both of the pair of excitation coils 3a and 3b with one part, for example.

[0030] In this way, the return magnetic path cover 14, for example, by being installed on a side surface in the circumferential direction of the tube axis, exhibits a first function of blocking the magnetic field generated by the excitation coil 3 from leaking to the outside. Also, the return magnetic path cover 14, for example, by having a shape that fits inside the gap of the excitation coil 3, exhibits a second function of enhancing the magnetic field generated by the excitation coil 3 as an electromagnet.

[0031] Next, the feedback magnetic path sheet 15 will be described. FIG. 8 is a diagram showing another example 2 of the electromagnetic flowmeter 100 according to the present embodiment. The electromagnetic flowmeter 100 shown in FIG. 8 further includes a feedback magnetic path sheet 15, as compared with the electromagnetic flowmeter 100 shown in FIG. 2, for example. The feedback magnetic path sheet 15 is, for example, installed on at least one of the outer diameter side and the inner diameter side in the tube axis perpendicular direction of the excitation coil 3, and is one of the feedback magnetic path auxiliary members that assist the function of the feedback magnetic path 11. The feedback magnetic path sheet 15 is, for example, installed on the inner diameter side in the tube axis perpendicular direction of the excitation coil 3, and absorbs the magnetic flux of the magnetic field toward the outer diameter side in the tube axis perpendicular direction of the excitation coil 3. The feedback magnetic path sheet 15 is, for example, installed on the inner diameter side in the tube axis perpendicular direction of the excitation coil 3, except for the part where the excitation coil 3 is installed in the measurement tube, and transmits the magnetic flux of the magnetic field toward the inner diameter side and enhances the magnetic field generated by the excitation coil 3. The feedback magnetic path sheet 15 is, for example, a ferromagnetic plate. The feedback magnetic path sheet 15 will be described in more detail with reference to FIGS.

[0032] Fig. 9 is a diagram showing an example of the feedback magnetic path sheet 15 according to this embodiment. For example, as shown in Fig. 9, the feedback magnetic path sheet 15 has a structure in which it is installed on the inner diameter side in the direction perpendicular to the tube axis of the excitation coil 3. In this case, the feedback magnetic path sheet 15 may have a structure that does not interfere with the magnetic field generated by the excitation coil 3 flowing into the flow path of the measurement tube, and the other parts, that is, the inner gap part at the bottom surface of the excitation coil 3 and the peripheral part at the bottom surface of the excitation coil 3, are filled with a ferromagnetic material.

[0033] In the example of Figure 9, the feedback magnetic path sheet 15 has a structure separated into three parts, is shaped to avoid being installed directly below the excitation coil 3, and covers the inner gap and surrounding areas on the bottom surface of the excitation coil 3.

[0034] Fig. 10 is a diagram showing another example 1 of the feedback magnetic path sheet 15 according to the present embodiment. In the example of Fig. 10, the feedback magnetic path sheet 15 has a structure in which four slits are formed, and is shaped to avoid being placed directly below the excitation coil 3 and to cover the inner gap portion and the peripheral portion on the bottom surface of the excitation coil 3.

[0035] Fig. 11 is a diagram showing another example 2 of the feedback magnetic path sheet 15 according to the present embodiment. In the example of Fig. 11, the feedback magnetic path sheet 15 has a structure in which two cavities are formed, and is shaped to avoid being placed directly below the excitation coil 3 and to cover the inner gap part and the peripheral part on the bottom surface of the excitation coil 3.

[0036] In this way, the feedback magnetic path sheet 15 exhibits a first function of absorbing the magnetic flux of the magnetic field generated by the excitation coil 3, for example, by being placed in the peripheral portion of the bottom surface of the excitation coil 3. Also, the feedback magnetic path sheet 15 exhibits a second function of enhancing the magnetic field generated by the excitation coil 3 as an electromagnet, for example, by being placed in the inner gap portion of the bottom surface of the excitation coil 3.

[0037] (effect) As described above, the electromagnetic flowmeter 100 of this embodiment is provided with at least one sensor (such as magnetic sensor 8) between the opposing piping 200 connected to measure the flow rate and the excitation coil 3, for measuring at least one of the magnetic flux, magnetic flux density, and magnetic permeability leaking from the detector inside 13 of the electromagnetic flowmeter 100 to the opposing piping 200.

[0038] As a result, in order to correct flow rate errors, the electromagnetic flowmeter 100 can measure magnetic flux leaking from inside the detector 13 of the electromagnetic flowmeter 100. In particular, since the electromagnetic flowmeter 100 of this embodiment can directly measure magnetic flux leakage using the built-in magnetic sensor 8, for example, not only does it eliminate the need for a costly and rigorous magnetic shield structure, but it can also appropriately correct flow rate errors caused by magnetic flux leakage.

[0039] Moreover, a sensor such as a magnetic sensor 8 is provided inside the detector 13 .

[0040] As a result, the electromagnetic flowmeter 100 can measure magnetic flux leaking from the inside 13 of the detector of the electromagnetic flowmeter 100 in order to correct flow rate errors.

[0041] Further, a sensor such as the magnetic sensor 8 is provided between the mating pipe 200 and the exciting coil 3, where the distance between the exciting coil 3 and the inside 13 of the detector is the shortest.

[0042] As a result, the electromagnetic flowmeter 100 can more accurately measure the magnetic flux leaking from the inside 13 of the detector of the electromagnetic flowmeter 100 in order to correct flow rate errors.

[0043] Furthermore, a sensor such as the magnetic sensor 8 is provided outside the electromagnetic flowmeter 100 and is connected to a converter of the electromagnetic flowmeter 100 .

[0044] As a result, the electromagnetic flowmeter 100 can measure magnetic flux leaking from the inside 13 of the detector of the electromagnetic flowmeter 100 in order to correct flow rate errors.

[0045] Moreover, a sensor such as a magnetic sensor 8 is provided on a flange portion 10 inside the detector 13 .

[0046] As a result, the electromagnetic flowmeter 100 can more accurately measure the magnetic flux leaking from the inside 13 of the detector of the electromagnetic flowmeter 100 in order to correct flow rate errors.

[0047] Moreover, the electromagnetic flowmeter 100 includes a calculation unit 7 that performs a correction calculation for the flow rate based on the measured magnetic flux or magnetic flux density.

[0048] As a result, the electromagnetic flowmeter 100 can appropriately correct flow rate errors caused by magnetic flux leakage.

[0049] Moreover, the electromagnetic flowmeter 100 includes a calculation unit 7 that performs a correction calculation for the flow rate based on the measured magnetic permeability.

[0050] As a result, the electromagnetic flowmeter 100 can appropriately correct flow rate errors caused by magnetic flux leakage.

[0051] The flow rate characteristics corrected in the correction calculation are at least one of a zero flow rate, a flow rate span, and a non-linear flow rate characteristic.

[0052] As a result, the electromagnetic flowmeter 100 can appropriately correct flow rate errors caused by magnetic flux leakage.

[0053] Moreover, the electromagnetic flowmeter 100 includes a feedback magnetic path 11 that concentrates the magnetic field generated by the exciting coil 3 inside the measurement tube, and a feedback magnetic path auxiliary member that assists the function of the feedback magnetic path 11.

[0054] As a result, the electromagnetic flowmeter 100 can appropriately correct flow rate errors caused by magnetic flux leakage while suppressing magnetic flux leakage.

[0055] Moreover, the return magnetic path auxiliary member is disposed on the outer diameter side in the direction perpendicular to the tube axis of the exciting coil 3, and blocks the movement of the magnetic flux of the magnetic field to the outer diameter side.

[0056] As a result, the electromagnetic flowmeter 100 can appropriately correct flow rate errors caused by magnetic flux leakage while suppressing magnetic flux leakage.

[0057] Moreover, in the electromagnetic flowmeter 100, the return magnetic path auxiliary member is disposed so as to enter the gap of the exciting coil 3, and strengthens the magnetic field generated by the exciting coil 3.

[0058] As a result, the electromagnetic flowmeter 100 can appropriately correct flow rate errors caused by magnetic flux leakage while suppressing magnetic flux leakage.

[0059] Moreover, in the electromagnetic flowmeter 100, the return magnetic path auxiliary member is disposed on the inner diameter side in the direction perpendicular to the tube axis of the exciting coil 3, and blocks the movement of the magnetic flux of the magnetic field to the inner diameter side.

[0060] As a result, the electromagnetic flowmeter 100 can appropriately correct flow rate errors caused by magnetic flux leakage while suppressing magnetic flux leakage.

[0061] In addition, in the electromagnetic flowmeter 100, the return magnetic path auxiliary member is installed on the inner diameter side except for the portion where the excitation coil 3 is installed in the measuring tube, and allows the magnetic flux of the magnetic field to pass through to the inner diameter side and enhances the magnetic field generated by the excitation coil 3.

[0062] As a result, the electromagnetic flowmeter 100 can appropriately correct flow rate errors caused by magnetic flux leakage while suppressing magnetic flux leakage.

[0063] In addition, in the electromagnetic flowmeter 100, the return magnetic path auxiliary member is a ferromagnetic plate.

[0064] As a result, the electromagnetic flowmeter 100 can appropriately correct flow rate errors caused by magnetic flux leakage while suppressing magnetic flux leakage.

[0065] (Further Other Embodiments) Although the embodiment of the present invention has been described above, the present invention may be embodied in various different forms other than the above-described embodiment.

[0066] (system) The information including the processing procedures, control procedures, specific names, various data and parameters shown in the above documents and drawings can be changed arbitrarily unless otherwise specified.

[0067] In addition, each component of each device shown in the figure is a functional concept, and does not necessarily have to be physically configured as shown in the figure. In other words, the specific form of distribution and integration of each device is not limited to that shown in the figure. In other words, all or part of them can be functionally or physically distributed and integrated in any unit according to various loads, usage conditions, etc.

[0068] Furthermore, each processing function performed by each device may be realized, in whole or in part, by a CPU (Central Processing Unit) and a program analyzed and executed by the CPU, or may be realized as hardware using wired logic.

[0069] (Hardware) Fig. 12 is a diagram showing an example of a hardware configuration of an electromagnetic flowmeter 100 according to this embodiment. As shown in Fig. 12, the electromagnetic flowmeter 100 may include, for example, a communication terminal 100a, a non-volatile memory 100b, a RAM (Random-Access Memory) 100c, and a processor 100d. The components shown in Fig. 12 are connected to each other via a bus or the like.

[0070] The communication terminal 100a is an Ethernet (registered trademark) port or the like, and communicates with other information processing devices such as the administrator device 60, the operator device 70, and the DCS control device. The non-volatile memory 100b is a flash memory or the like, and stores programs and data for operating the functions shown in FIG.

[0071] The processor 100d is a CPU, a micro processing unit (MPU), a graphics processing unit (GPU), or the like. The processor 100d may be realized by an integrated circuit such as an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA). The processor 100d reads out a program that executes the same processes as the processing units such as the calculation unit 7 shown in FIG. 1 from the non-volatile memory 100b, and loads it in the RAM 100c, thereby operating a thread that executes each function described in FIG. 1, etc. For example, this thread executes a function similar to that of each processing unit of the electromagnetic flowmeter 100.

[0072] In this way, the electromagnetic flowmeter 100 operates as an information processing device that executes various processing methods by reading and executing the program. The program may be distributed via a network such as the Internet. The program may be recorded on a computer-readable storage medium such as a hard disk, a flexible disk (FD), a CD-ROM, a magneto-optical disk (MO), or a digital versatile disk (DVD). The program may be executed by being read from the computer-readable storage medium by the electromagnetic flowmeter 100 or the like.

[0073] (others) Some examples of combinations of the disclosed technical features are set out below.

[0074] (1) An electromagnetic flowmeter having at least one sensor between a pipe connected to measure a flow rate and an excitation coil, for measuring at least one of magnetic flux, magnetic flux density, and magnetic permeability leaking from inside the electromagnetic flowmeter to the pipe.

[0075] (2) The electromagnetic flowmeter according to (1), wherein the sensor is provided inside the flowmeter.

[0076] (3) The electromagnetic flowmeter according to (1) or (2), wherein the sensor is provided between the piping and the excitation coil, where the distance between the sensor and the excitation coil inside the piping is the shortest.

[0077] (4) The electromagnetic flowmeter according to any one of (1) to (3), wherein the sensor is provided outside the electromagnetic flowmeter and connected to a converter of the electromagnetic flowmeter.

[0078] (5) The electromagnetic flowmeter according to any one of (1) to (4), wherein the sensor is provided on the internal flange portion.

[0079] (6) The electromagnetic flowmeter according to any one of (1) to (5), further comprising a calculation unit that performs a correction calculation for the flow rate based on the measured magnetic flux or magnetic flux density.

[0080] (7) The electromagnetic flowmeter according to any one of (1) to (6), further comprising a calculation unit that performs a correction calculation for the flow rate based on the measured magnetic permeability.

[0081] (8) The electromagnetic flowmeter according to any one of (1) to (7), wherein the flow characteristic corrected in the correction calculation is at least one of a zero flow characteristic, a flow span characteristic, and a non-linear flow characteristic.

[0082] (9) a feedback magnetic path that concentrates the magnetic field generated by the excitation coil inside the measuring tube; A feedback magnetic path auxiliary member that assists the function of the feedback magnetic path; The electromagnetic flowmeter according to any one of (1) to (8), comprising:

[0083] (10) An electromagnetic flowmeter according to any one of (1) to (9), wherein the return magnetic path auxiliary member is disposed on an outer diameter side in a direction perpendicular to a tube axis of the excitation coil and blocks movement of magnetic flux of the magnetic field toward the outer diameter side.

[0084] (11) The electromagnetic flowmeter according to any one of (1) to (10), wherein the return magnetic path auxiliary member is disposed so as to enter a gap of the excitation coil and enhances the magnetic field generated by the excitation coil.

[0085] (12) An electromagnetic flowmeter according to any one of (1) to (11), wherein the return magnetic path auxiliary member is disposed on an inner diameter side in a direction perpendicular to a tube axis of the excitation coil and blocks movement of magnetic flux of the magnetic field toward the inner diameter side.

[0086] (13) An electromagnetic flowmeter according to any one of (1) to (12), wherein the feedback magnetic path auxiliary member is installed on the inner diameter side excluding a portion where the excitation coil is installed on the measuring tube, and transmits magnetic flux of the magnetic field to the inner diameter side and enhances the magnetic field generated by the excitation coil.

[0087] (14) The electromagnetic flowmeter according to any one of (1) to (13), wherein the feedback magnetic path auxiliary member is a ferromagnetic plate. [Explanation of symbols]

[0088] 1 Piping section 2. Insulator 3 Excitation coil 4 Conductive fluid 5 electrodes 6 Amplifier 7 Arithmetic section 8 Magnetic Sensors 9 Transmitting and receiving circuits 10 Flange 11 Feedback magnetic circuit 12 Cover 13 Inside the detector 14 Return magnetic path cover 15 Feedback magnetic circuit sheet 16 Fixing member 100 electromagnetic flowmeter 200 Mating piping

Claims

1. An electromagnetic flowmeter comprising at least one sensor disposed between a pipe connected to measure a flow rate and an excitation coil for measuring at least one of magnetic flux, magnetic flux density, and magnetic permeability leaking from inside the electromagnetic flowmeter into the pipe.

2. The electromagnetic flowmeter of claim 1 , wherein the sensor is provided within the interior.

3. The electromagnetic flowmeter according to claim 2 , wherein the sensor is provided between the pipe and the excitation coil, where the distance between the sensor and the excitation coil inside the pipe is the shortest.

4. 2. The electromagnetic flowmeter according to claim 1, wherein the sensor is provided outside the electromagnetic flowmeter and connected to a converter of the electromagnetic flowmeter.

5. The electromagnetic flowmeter according to claim 2 , wherein the sensor is provided on the internal flange portion.

6. The electromagnetic flowmeter according to claim 1 , further comprising a calculation unit that performs a correction calculation for the flow rate based on the measured magnetic flux or the measured magnetic flux density.

7. The electromagnetic flowmeter according to claim 1 , further comprising a calculation unit that performs a correction calculation for the flow rate based on the measured magnetic permeability.

8. 7. The electromagnetic flowmeter according to claim 6, wherein the flow characteristic corrected by the correction calculation is at least one of a zero flow characteristic, a flow span characteristic, and a non-linear flow characteristic.

9. a feedback magnetic path that concentrates the magnetic field generated by the excitation coil inside a measurement tube; A feedback magnetic path auxiliary member that assists the function of the feedback magnetic path; The magnetic flow meter of claim 1 .

10. The electromagnetic flowmeter according to claim 9 , wherein the return magnetic path auxiliary member is disposed on an outer diameter side in a direction perpendicular to a tube axis of the exciting coil, and blocks movement of magnetic flux of the magnetic field to the outer diameter side.

11. The electromagnetic flowmeter according to claim 10 , wherein the feedback magnetic path auxiliary member is disposed so as to be embedded in a gap of the excitation coil and enhances the magnetic field generated by the excitation coil.

12. The electromagnetic flowmeter according to claim 9 , wherein the return magnetic path auxiliary member is disposed on an inner diameter side in a direction perpendicular to a tube axis of the exciting coil, and blocks movement of magnetic flux of the magnetic field toward the inner diameter side.

13. 13. The electromagnetic flowmeter according to claim 12, wherein the return magnetic path auxiliary member is installed on the inner diameter side excluding a portion where the excitation coil is installed on the measurement tube, transmits magnetic flux of the magnetic field to the inner diameter side, and enhances the magnetic field generated by the excitation coil.

14. The electromagnetic flowmeter according to claim 9 , wherein the feedback magnetic path auxiliary member is a plate made of a ferromagnetic material.

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