JPH11108713A - Electromagnetic flowmeter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify handling in attaching work and to maintain reliability and enhance durability in a severe environment in later stages. SOLUTION: A measuring tube 10 comprises an inner tube 11 made of a resin and an outer tube 12 made of a metal, and a space 13 between them houses exciting coils 18, 19 and lead wires from electrodes 14, 15 and from the exciting coils 18, 19 and then filled with a seal material 5. A plurality of leg parts of liquid-contacting rings 26, 27 are inserted and fixed in the space 13, and connected to an earth wire. Because the housing space is filled with the seal material, the lead wires are prevented from receiving an outer injury and coil insulation is prevented from deteriorating due to a bad environment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic flowmeter for electrically measuring a flow rate of a fluid to be measured flowing in a measurement pipe.

[0002]

2. Description of the Related Art As shown in FIG. 3, an electromagnetic flowmeter generates a magnetic field perpendicular to a flow direction F of a fluid, and generates an electromotive force generated by a conductive liquid moving in the magnetic field. The flow rate is measured by detecting at steps 14 and 15. Such a conventional electromagnetic flow meter 1 'is shown in FIG.
explain. Made of non-magnetic metal material such as stainless steel,
A measuring tube 10 'having an inner peripheral surface lined with an insulating material 35' made of Teflon, rubber or the like, and a flow direction of a fluid to be measured in the measuring tube which is disposed so as to sandwich the outer peripheral portion of the measuring tube from above and below. A pair of excitation coils 18 and 19 for applying a magnetic field in a direction orthogonal to F, and mounted and fixed opposite to a part of the side wall of the measurement tube so as to be orthogonal to the direction of the flow of the fluid to be measured and the direction of the magnetic field by the excitation coil. A pair of electrodes 14 and 15 having liquid contact ends facing each other are provided. The flange portion 10'A at the end of the measuring tube 10 'in the flow direction is provided between the upstream and downstream pipe lines 36, 37 and the flanges 38, 38 for pipe connection.
It is attached by bolts 39, 39 with the 5 'flange portion and the earth rings 26', 27 'interposed therebetween.

Next, the operation will be described. Excitation coil 1
When the conductive fluid to be measured flows through the measurement tube by exciting the electrodes 8 and 19, the electrode 14 and 15 whose axes are orthogonal to the direction of the magnetic flux of the exciting coil and the direction of the fluid flow are proportional to the average flow rate. An electromotive force is generated, which is converted into an electric signal and measured to obtain a flow rate.

[0004]

A conventional electromagnetic flowmeter is:
In many cases, electrical insulation deteriorates during use due to installation in humid places or splashing of corrosive fluids, causing failures.In such cases, it is necessary to repair the electromagnetic flow meter, There were problems such as requiring a lot of labor and time to update. In order to obtain electrical insulation and corrosion resistance, the inner surface of the metal measuring tube 10 'is lined with a resin material.
5 'was performed, but this lining requires special equipment and requires skill to achieve a uniform thickness, and it is easy to peel off during use as an electromagnetic flowmeter or during installation work. was there. Further, the earth rings 26 ', 27'
The measurement tube and the fluid to be measured are grounded to the same potential to eliminate noise generated due to the instability of the same fluid during measurement.Conventionally, this was supplied as a part of an electromagnetic flowmeter, Is applied to the flange 10′A at the end in the flow direction of the measuring pipe 10 ′ of the flowmeter via the flange of the lining 35 ′, and the flanges 38, 38 for connecting the pipes.
However, not only skill is required, but also an excessive force is applied, the measuring tube 10 'is deformed, the sealing portion is loosened, water leakage occurs, and electrical connection is not established. There was a problem that it became sufficient and noise was generated.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve such problems of the prior art. First, a first aspect of the present invention is a measurement tube through which a fluid to be measured flows, an excitation coil that applies a magnetic field in a direction perpendicular to the flow, and an excitation coil that is orthogonal to the flow direction and the direction of the magnetic field and faces the inside of the measurement tube. It has a pair of electrodes provided, a detector for detecting a flow signal from the electrodes, and a converter for amplifying and outputting the flow signal, wherein the measurement tube is a resin inner tube and a metal outer tube. The space between the inner tube and the outer tube is provided with the exciting coil, the electrode, and the lead wire from the exciting coil, and the space is filled with a sealing material to form a waterproof structure. .

Next, according to a second aspect of the present invention, the earth ring provided at the end of the measuring tube in the flow direction has a plurality of legs for guiding at the time of insertion and for subsequent positioning. (1) forms a ground wire connection portion.

According to a third aspect of the present invention, a reinforcing plate having bent portions at both ends is provided between flange portions at both ends of the inner pipe,
The strength of the measuring tube in the flow direction is improved.

[0008]

According to the first aspect of the present invention, the lead wire from the electrode and the exciting coil passes through the space between the inner tube and the outer tube of the measuring tube to the converter, and the space is filled with a sealing material. Therefore, the lead wire is not damaged, and the insulation is not deteriorated due to the bad surrounding environment. According to the second aspect of the present invention, since the grounding ring is attached and fixed at the factory, the grounding performance is always stable without depending on the skill of the worker in the conventional example. Next, according to the invention of claim 3, even if an excessive force is received during mounting work or the like, the reinforcing plate withstands the force and the measuring tube does not deform.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. In FIG. 1, (A) is a front view,
(A) is a partially cut left side view. FIG. 2 is a front view of the center section taken along line XX ′ of FIG. FIG. 3 is an explanatory diagram (a) and an electric circuit diagram (a) showing the principle. FIG.
1A is a central vertical sectional view of the detector taken along line YY ′ in FIG. 1A, and FIG. 1A is a bottom view in which the outer tube of FIG. 1A is cut and removed. In FIG. 5, FIG.
(A) is a left side view of the detector in which the outer tube is cut and removed as viewed in the direction of arrow Q, and (A) is a cross-sectional view taken along line BB 'of (A). FIG. 6 is an enlarged explanatory view of a section taken along line SS ′ of FIG. FIG. 7 shows a liquid contact ring, (a) is a left side view,
(A) is a front view. 8A and 8B show a reinforcing plate, FIG. 8A is a front view, and FIG. 8A is an explanatory cross-sectional view showing an assembled state.

The electromagnetic flow meter 1 according to the present embodiment includes a converter 2 and a detector 4. Converter 2 is housed in case 3 including upper case 3A and lower case 3B. Detector 4
Is a measuring tube 10, electrodes 14, 15 and an exciting coil 1
8, 19, etc. The measuring tube 10 of the detecting unit 4 includes, for example, a cylindrical inner tube 11 made of resin and an outer tube 12 made of metal. A space 13 is provided between the two tubes 11 and 12, and after storing each component described later, , Sealing material 5 such as urethane resin
(Potting) to form a waterproof structure. Reference numerals 14 and 15 denote the above-mentioned electrodes.
And fixed to the inner tube 11 of the measuring tube 10 so as to face each other. Reference numerals 18 and 19 denote the above-mentioned excitation coils, which are provided with lead wires 20, 20, 21 and 21, respectively, and are provided with holding plates 24 and 25 having a magnetic flux inducing function, and mounting plates 22 and 23 having the same magnetic flux inducing function. Inner tube 11
Fixed to That is, as shown in FIGS. 4 and 5, the iron cores 18A and 19A of the exciting coils 18 and 19 are fixed by the small screw r1. The mounting plates 22 and 23 are fixed to the step 11A of the inner tube 11 by small screws r2, are coupled to each other by small screws r3, and are held at predetermined positions on the inner periphery of the outer tube 12.

Next, reference numerals 26 and 27 denote liquid contact rings made of a metal plate as guides for inserting into the space 13 between the inner tube 11 and the outer tube 12 of the measuring tube 10 and for positioning thereafter. A plurality of legs 26A and 27A serving as One of the legs 26A1 is a connection portion of the ground wire 28, and is connected by an appropriate method such as spot welding, soldering, or screwing with a small hole. The liquid contact rings 26 and 27 are used for sealing members 2 such as O-rings.
9 and is inserted into the space 13 and is fixed to the flange portion 11B of the inner tube 11 with a small screw r4. Further, reference numeral 30 denotes a plurality of metal reinforcing plates having bent portions 30A at both ends. Then, as shown in FIG. 7A, concave portions 11D are provided in the flange portions 11B at both ends in the flow direction of the inner pipe 11, and the concave portions 11D are provided.
The reinforcing plate 30 is attached by fitting the bent portion 30A into D. Therefore, when an excessive force is applied to the measuring pipe in the installation work of the electromagnetic flow meter or the like, the bent portions 30A at both ends of the reinforcing plate 30 are opposed to each other to prevent deformation and distortion of the measuring pipe. And FIG.
As shown in the figure, the lower case 3B
And fix it with small screws r5. In addition,
After the lower case 3B is fixed, the sealing material 5 is removed as shown in FIG.
Is filled up to the level of the line LL ', the case 3 and the respective components are hermetically sealed, and the respective portions are surely kept connected.

[0012]

According to the electromagnetic flowmeter of the present invention, the excitation coil, the electrodes and the lead wires from the excitation coil pass through the space between the inner tube and the outer tube of the measurement tube to reach the conversion section, and furthermore, Since the space is filled with the sealing material, the lead wire is not damaged and the coil insulation is not deteriorated due to a bad surrounding environment. In addition, since the liquid contact ring is attached and fixed at the factory, it always has a stable grounding performance without depending on the skill of the worker in the conventional example. Next, even if an excessive force is applied in the mounting work, the reinforcing plate withstands this, and the measuring tube does not deform, etc. Does not require

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention. FIG. 1A is a front view, and FIG. 1A is a partially cut left side view.

FIG. 2 is a central sectional front view taken along line XX ′ of FIG.

3A is an explanatory diagram showing the principle, and FIG. 3A is an electric circuit diagram.

4 (A) is a central longitudinal sectional view of the detector taken along the line YY ′ of FIG. 1 (A), and FIG. 4 (A) is a cutaway of the outer tube of FIG. 4 (A). Bottom view.

5 (A) is a left side view of the detector in which the outer tube is cut and removed as viewed in the direction of arrow Q in FIG. 1 (A), and FIG. 5 (A) is FIG.
FIG. 3A is a sectional view taken along line BB ′ of FIG.

FIG. 6 is an enlarged explanatory view of a section taken along line S-S ′ of FIG.

7 (a) is a left side view, and FIG. 7 (a) is a front view showing a liquid contact ring.

FIG. 8 shows a reinforcing plate, and FIG.
(A) is a partially cutaway view similar to FIG. 4 (A) showing the assembled state.

FIG. 9 is a central sectional view of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electromagnetic flowmeter 2 Conversion part 3 Case 3A Upper case 3B Lower case 3C Leg 4 Detector 5 Sealing material 10 Measurement tube 11 Inner tube 11A Step 11B Flange 11C Convex 12 Outer tube 13 Space 14,15 Electrode 16, 17 Lead wire 18, 19 Excitation coil 18A, 19A Iron core 20, 20; 21, 21 Lead wire 22, 23 Mounting plate 24, 25 Retaining plate 26, 27 Wetted ring 26A, 27A Leg 26A1 Ground wire connection 28 Ground wire 29 O-ring 30 Reinforcement plate

Claims (3)

[Claims] 1. A measuring tube through which a fluid to be measured flows, an exciting coil for applying a magnetic field in a direction orthogonal to the flow, and a pair of coils provided orthogonal to the direction of the flow and the direction of the magnetic field and opposed to each other in the measuring tube. Having an electrode, a detector for detecting a flow signal from the electrode, and a converter for amplifying and outputting the flow signal, wherein the measurement tube is formed of an inner tube made of resin and an outer tube made of metal. The space between the inner tube and the outer tube is provided with the exciting coil and the lead wire from the electrode and the exciting coil, and the space is filled with a sealing material to form a waterproof structure. Total. 2. An earthing ring provided at an end of the measuring tube in the flow direction has a plurality of legs for guiding during insertion and subsequent positioning, and one of the legs serves as an earth wire connecting portion. The electromagnetic flowmeter according to claim 1, wherein 3. A method according to claim 1, wherein a reinforcing plate having bent portions at both ends is provided between the flange portions at both ends of the inner tube to improve the strength of the measuring tube in the flow direction. Item 3. The electromagnetic flowmeter according to Item 2.