JPH09138147A - Electromagnetic flowmeter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electromagnetic flowmeter wherein excellent workability of positioning/fixing of a lead wire is provided and the lead wire is fixed with sure, by providing a positioning recessed part and hole formed in a magnetic flux feeding-back outer core in parallel, in the circumferential direction of the outer core. SOLUTION: A coil 4 is energized by feeding from a power source, and a magnetic field is generated in the direction orthogonal to the axis of a measuring tube 1, and to-be-measured fluid 2 is moved into the measuring tube in the magnetic field, so that electromotive force is generated based on Faraday's law of electromagnetic induction. At this time, the magnetic field is generated at a right angle to the measuring tube electrically insulated, and, when conductivity of the flowing fluid is not too low, the electromotive force is measured between a pair of electrodes 5. Since the electromotive force is proportional to intensity of the magnetic field, average flow velocity of the fluid, and distance between the electrodes, flow rate can be measured by removing noise from the electromotive force, and converting into the signal corresponding to the fluid with a converter, for outputting.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generates a magnetic field in a direction intersecting with a fluid to be measured flowing in a measuring pipe, and an electromotive force generated according to a flow rate of the fluid traversing the magnetic field is measured as a diameter of the measuring pipe. The present invention relates to an electromagnetic flow meter that measures the flow rate by detecting it through at least a pair of electrodes provided facing each other.

[0002]

2. Description of the Related Art FIG. 6 is a block diagram showing the measuring principle of an electromagnetic flowmeter 50. In the figure, 51 is a measuring tube whose inner surface is lined with Teflon or the like, and 52 is a conductive liquid flowing in the measuring tube 1. Is the fluid to be measured, 53 is the measuring tube 5
1, 54 is a coil wound around the core 53 as a magnetic field generating means, and 55 is at least a pair of electrodes provided at positions facing each other on the diameter of the measuring tube 51 and intersecting the magnetic field. 56 are converters that remove noise and the like from the electromotive force detected by the electrode 55 and convert the electromotive force into a signal corresponding to the flow rate of the fluid 52 to be measured.

The lead wire 58 connected to the electrode 55 and taken out from the hole 57a of the magnetic flux feedback outer core 57 is
As shown in FIGS. 7 and 8, the magnetic flux feedback outer core 57.
A tin-plated wire 59 is positioned and fixed on the surface of the so as to avoid generation of 90 ° noise. Here, the 90 ° noise is caused by a curved wiring in which a lead wire crosses a magnetic flux as shown in FIG. 9 when an electromotive force generated by Fleming's right-hand rule is extracted, and this noise is an electromotive force. If it is superposed on, accurate electromotive force and hence accurate flow rate cannot be measured.

Next, the operation will be described. When the coil 54 is excited by power supply from a power source (not shown), a magnetic field is generated in a direction orthogonal to the axis of the measuring tube 51, and the measured fluid 52 is moved to the measuring tube in this magnetic field. An electromotive force is generated according to the law. In this case, the magnetic field is generated at right angles to the electrically insulated measuring tube, and the electromotive force can be measured between the pair of electrodes 55 unless the electric conductivity of the flowing measured fluid 52 is too low. Since this electromotive force is proportional to the strength of the magnetic field, the average flow velocity of the fluid to be measured 52, and the distance between the electrodes, noise is removed from this electromotive force, and this electromotive force is converted by the converter 56 into a signal corresponding to the fluid to be measured 52. Then, the flow rate can be measured.

That is, when the quantity symbol and the unit are as follows, quantity symbol physical quantity unit B magnetic flux density TD inner diameter of measuring tube m v average axial fluid velocity m / s E electromotive force V k constant-Q volume flow rate m According to Faraday's law of ³ / s, the magnitude of the electromotive force E is expressed by the following equation. E = kBDv (1) The volume flow rate is calculated by the following equation in the case of a circular pipe. ^{Q = (πD 2/4)} · v ··· (2) Because of this relationship, equation (1) is expressed by the equation (3). Q = (πD / 4kB) · E (3) Here, assuming that the magnetic flux density B is constant, the flow rate in the measuring tube is obtained by measuring the electromotive force E.

[0006]

Since the conventional electromagnetic flowmeter is constructed as described above, the lead wire 58 connected to the electrode 55 has a magnetic flux feedback outer core 57 for removing 90 ° noise. The tin-plated wire 59 is positioned and fixed on the surface of the. As a result, there is a problem that it is difficult to surely perform the attachment and the workability of positioning and fixing is poor.

The present invention has been made in order to solve the above problems, and an object thereof is to obtain an electromagnetic flow meter which has good workability in positioning and fixing lead wires and which can securely fix the lead wires. And

[0008]

According to a first aspect of the present invention, there is provided an electromagnetic flowmeter which comprises a magnetic field generating means for generating a magnetic field orthogonal to a fluid to be measured in a measuring pipe, and an action of the magnetic field in the fluid to be measured. At least a pair of electrodes provided to face each other on the diameter of the measuring tube so as to measure the electromotive force generated in the magnetic flux feedback outer core fixed to the measuring tube to cover the magnetic field generating means. The positioning recess formed in the hole edge of the first hole for assembling the electrode and the lead wire connected to the electrode are introduced into the inside of the magnetic flux feedback outer core from the recess and then the magnetic flux is taken out again. A second hole is formed in the return outer core, and the positioning recess and the second hole are arranged side by side in the circumferential direction of the magnetic flux return outer core.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. 1 is a partially cutaway front view showing an electromagnetic flowmeter according to Embodiment 1 of the present invention, FIG. 2 is a partially cutaway side view thereof, and FIG. 3 is a front view of an electrode mounting portion. Reference numeral 1 is a measuring tube, 2 is a fluid to be measured which is a conductive liquid flowing in the measuring tube 1, 3 is a core provided on the outer circumference of the measuring tube 1, and 4 is a magnetic field generating means wound around the core 3. Coil 5 is at least a pair of electrodes provided at positions facing each other on the diameter of measuring tube 1 and intersecting the magnetic field,
Reference numeral 6 is a lead wire connected to the electrode 5, 7 is an outer core for magnetic flux feedback which covers the coil 4 and is fixed to the measuring tube 1, and 8 is a coil 4 for generating a magnetic field in parallel in the diameter range of the measuring tube 1. An inner core interposed between the measuring tube 1 and 9 is a case that covers the coil 4, the magnetic flux feedback outer core 7 and the inner core 8 and is fixed to the measuring tube 1 by welding. Hole 9-1, electrode storage chamber 9
-2 and so on.

The measuring pipe 1 has corrosion resistance on the inner surface and the end surface,
A lining treatment 11 for abrasion resistance is applied, and a liquid contact ring 12 that makes the detection portion in the case 9 and the measurement fluid have the same potential is attached to the end surface thereof. As a material for the lining treatment 11, for example, fluorine resin, chloroprene rubber, polyurethane rubber, ceramics or the like is used. Further, as the material of the liquid contact ring 12, for example, stainless steel, platinum / indium, tantalum, titanium, Hastelloy B, Hastelloy C, Monel, conductive fluororesin or the like is used.

The electrode 5 is inserted through the electrode assembling hole of the magnetic flux feedback outer core, and the collar seat 5b of the electrode rod 5a is brought into contact with the receiving seat 11a formed by the running process. The cap 14 is screwed and fixed in the electrode mounting hole 1b of the measuring tube 1 while pressing the coil spring 13 that is brought into contact with the surface. 15 is an electrode rod 3
Reference numeral 16 is a screw for attaching the lead wire 6 to a, and 16 is a lid body screwed into the inlet of the electrode housing chamber 4c of the measuring tube 1.

FIG. 4 is a front view of the magnetic flux feedback outer core 7, and FIG. 5 is a vertical sectional view taken along the line VV of FIG. 4, which is formed at the edge of the first hole 7-1 for electrode assembly. A second hole 7-2 is formed so that the positioning recess 7-1a and the lead wire 6 connected to the electrode 5 are introduced from the recess 7-1a to the inside of the magnetic flux feedback outer core 7 and then taken out again. The positioning recess 7-1a and the second hole 7-2 are arranged side by side in the circumferential direction of the magnetic flux feedback outer core 7.

Next, a method of assembling the electromagnetic flowmeter composed of the above-mentioned components will be described. First, a coil 4 having an axially symmetrical core 3 is provided on the outer peripheral surface of the measuring tube 1, and the lead wire 6 of the electrode 5 is placed from the positioning recess 7-1a of the magnetic flux feedback outer core 7 to the inside of the magnetic flux feedback outer core. After being introduced, the magnetic flux feedback outer core 7 is attached to the measuring tube 1 so that the coil 4 is pressed and fixed to the outer surface of the measuring tube 1 after being taken out from the hole 7-2. After that, the measuring tube 1 is inserted into the case 9 from the accommodation hole 9-1 and the case 9 and the measuring tube 1 are inserted.
Weld the joints (both ends). Then, in the electrode accommodating chamber 9-2 of the case 9, the electrode 5 is attached to the measuring tube 1 and the lead wire 6 is connected, and the lead wire 4a of the coil 4 and the lead wire 6 of the electrode 5 are connected to the take-out chamber 9 of the case 9. −
Take out from 3.

The electromagnetic flowmeter having the above-described structure is connected and fixed to the left and right sides of the measuring pipe 1 so as to match the pipes 18a and 18b. The connection method is a flange connection method, a flange sandwiching method, a sanitary connection method, There are various types of screw connection methods.

Next, the operation will be described. When the coil 4 is excited by power supply from a power source (not shown), a magnetic field is generated in a direction orthogonal to the axis of the measuring tube 1, and the fluid to be measured 2 is moved to the measuring tube in this magnetic field. An electromotive force is generated according to the law. In this case, a magnetic field is generated at right angles to the electrically insulated measuring tube, and if the conductivity of the flowing liquid is not too low, the electromotive force can be measured between the pair of electrodes 5. Since this electromotive force is proportional to the strength of the magnetic field, the average flow velocity of the fluid, and the distance between the electrodes, noise is removed from this electromotive force, and this electromotive force is converted into a signal corresponding to the fluid by the converter 56 as shown in FIG. The flow rate can be measured by converting and outputting.

As described above, according to the first embodiment, the magnetic flux is generated from the positioning recess 7-1a formed at the edge of the first hole 7-1 for assembling the electrode with the lead wire 6 connected to the electrode 5. After being introduced inside the return outer core 7, it is taken out again from the second hole 7-2, and the positioning recess 7-1a and the second hole 7-2 are the same as those of the magnetic flux return outer core. By being arranged side by side in the circumferential direction,
The fixing and positioning of the lead wire 6 are performed at the same time, and the work is simple and easy, and further, the lead wire 6 is reliably fixed.

[0017]

As described above, according to the first aspect of the present invention, the lead wire connected to the electrode is used as the first electrode for assembling the electrode.
After being introduced into the inside of the magnetic flux feedback outer core from the positioning recess formed in the hole edge of the hole, the positioning recess and the second hole are taken out again from the second hole, and the positioning recess and the second hole are circles of the magnetic flux feedback outer core. Since they are arranged side by side in the circumferential direction, the fixing and positioning of the lead wire can be performed at the same time, the work is easy and easy, and the lead wire is arranged in parallel with the magnetic flux, so that 90 ° noise is surely generated. It can be prevented and the fixing is surely performed. Further, since the breakage of the lead wire is limited to the edge portion of the recess due to the vibration caused by the pulsation of the measured fluid due to the long-term use of the electromagnetic flow meter, it is easy to confirm the breakage of the lead wire during maintenance.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view showing an electromagnetic flowmeter according to an embodiment of the present invention.

FIG. 2 is a right side view in which a part of the electromagnetic flow meter is cut away.

FIG. 3 is a front view of an electrode mounting portion.

FIG. 4 is a front view of a magnetic flux feedback outer core to which a lead wire is attached.

FIG. 5 is a longitudinal sectional view taken along the line VV of FIG. 4;

FIG. 6 is a schematic configuration diagram illustrating a measurement principle of an electromagnetic flow meter.

FIG. 7 is a front view of a magnetic flux feedback outer core to which a lead wire is attached in a conventional electromagnetic flowmeter.

8 is a vertical cross-sectional view taken along the line XIII-XIII in FIG.

FIG. 9 is an explanatory diagram of 90 ° noise.

[Explanation of symbols]

 1 Measuring Tube 2 Fluid to be Measured 4 Coil (Magnetic Field Generating Means) 5 Electrode 6 Lead Wire 7 Outer Core for Flux Return 7-1 First Hole 7-1a Recess 7-2 Second Hole

Claims (1)

[Claims] 1. A measuring pipe through which a fluid to be measured is passed, a magnetic field generating means for generating a magnetic field perpendicular to the fluid to be measured in the measuring pipe, and an electromotive force generated in the fluid to be measured by the magnetic field action is measured. As described above, at least a pair of electrodes provided to face each other on the diameter of the measurement tube, a magnetic flux feedback outer core that covers the magnetic field generating means and is fixed to the measurement tube, and a magnetic flux feedback outer core are provided. The positioning recess formed in the hole edge of the first hole for assembling the electrode and the lead wire connected to the electrode are introduced from the recess to the inside of the magnetic flux feedback outer core and then taken out again to the outside. An electromagnetic flowmeter, comprising: a second hole formed in the magnetic flux returning outer core, wherein the positioning recess and the second hole are arranged side by side in the circumferential direction of the magnetic flux returning outer core.