JP3043586B2 - Electromagnetic flow meter - Google Patents

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 measuring pipe.

[0002]

2. Description of the Related Art An electromagnetic flowmeter takes a fluid to be measured flowing in a measuring tube as a conductor, generates a voltage by applying a magnetic field to the flowing conductor, and detects the voltage with an electrode to measure a flow rate. It is. Such a conventional electromagnetic flow meter will be described with reference to the drawings. Here, FIG. 13 is a longitudinal sectional view showing a conventional electromagnetic flow meter. In the figure, the electromagnetic flow meter has gaskets 4 and 5 between flanges of an upstream pipeline 2 and a downstream pipeline 3. The fluid to be measured flows between the pipe 2 and the pipe 3 while being clamped and fixed by a plurality of bolts 6. The electromagnetic flow meter includes a stainless steel measuring tube 7 integrally formed with a tube portion 7a and flange portions 7b on both sides, and an outer peripheral surface of the tube portion 7a and the flange portion 7a.
b, a pair of exciting coils 8 for forming a magnetic field in a direction perpendicular to the flow direction of the fluid is provided in the annular recessed portion surrounded by the flange b.
Are connected to the power supply. Reference numeral 9 denotes a cylindrical case having a support portion 9a for supporting a converter (not shown), which is fitted on an outer peripheral surface of a flange portion 7b of the measurement tube 7 via an O-ring 10 as a sealing material. Is fixed to the process fixing portion separately from the measuring tube 7 side. A lining 11 made of Teflon resin as an insulating material composed of the tube portion 11a and the flange portions 11b at both ends is provided on the inner peripheral surface of the tube portion 7a and the end surface of the flange portion 7b of the measurement tube 7. And the fluid are electrically insulated. Between both flanges 11b of the lining 11 and the gaskets 4 and 5, a metal earth ring 12 having an annular shape and having an inner hole 12a is interposed adjacent to the end face of the flange 11b. I have. The outer periphery of the earth ring 12 and the case 9 are connected by an earth wire 13, so that the fluid and the case 9 are connected to each other by the earth ring 12.
And the ground wire 13 are electrically connected. 1
Reference numeral 4 denotes a pair of electrodes provided so as to face each other so as to penetrate the inner walls of the measurement tube 7 and the lining 11. , And is configured to detect an electromotive force generated at each point of the fluid and send a signal to a converter (not shown) at the tip of the support portion 9a. Earth ring 12
The relationship between the potential of the electrode 14 and the potential of the electrode 14 is such that the earth ring 12 has a positive potential and the electrode 14 has a negative potential by adding an empty detection function.

Next, the operation will be described. Excitation coil 8
When the conductive fluid to be measured flows through the measuring tube 7 when
An electromotive force proportional to the average flow rate is generated between the electrodes 14 whose axes are orthogonal to the magnetic flux generation direction of the excitation coil 8 and the flow direction of the fluid. The electromotive force is converted into an electric signal and measured. The flow rate is obtained.

[0004]

As described above, in the conventional electromagnetic flowmeter, the area of the portion where the fluid to be measured contacts the earth ring 12 (hereinafter referred to as the "wet area") is ground. Only an area corresponding to the surface area of the inner hole 12a of the ring 12 could be secured. Even in such a case, since the liquid contact area of the earth ring 12 is usually much larger than that of the electrode 14, the thickness of the oxide film formed on the earth ring 12 on the positive potential side is also small, making it difficult to achieve insulation. However, the inner hole 1 of the earth ring 12
The smaller the diameter and length of 2a, the more the earth ring 12
And the difference between the liquid contact area of the electrode 14 and the liquid contact area of the electrode 14 disappears. As a result, the thickness of the oxide film formed on the earth ring 12 increases, and the insulating ring tends to be in an insulated state. There was a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a large flow area of the earth ring is ensured to prevent the earth ring from being oxidized and to detect a stable flow signal. The purpose is to obtain an electromagnetic flowmeter that can be used.

[0006]

According to the electromagnetic flow meter of the present invention, the contact area with the fluid to be measured has a negative potential.
To make the earth ring bigger than the electrode,
A notch formed in at least one of between the earth ring and the pipe line or between the earth ring and the measurement pipe, the cut portion communicating with the flow path of the fluid to be measured, or the notch communicating with the inner hole in the earth ring; Is formed so that a large liquid contact area of the earth ring can be ensured.

[0007]

According to the electromagnetic flowmeter of the present invention, a concave portion communicating with a flow path of a fluid to be measured is formed in at least one of between an earth ring and a pipe line or between an earth ring and a measurement pipe. By forming a guide hole communicating with the inner hole in the ring, a large liquid contact area of the earth ring is ensured to prevent insulation due to oxidation of the earth ring and detect a stable flow signal.

[0008]

【Example】

Embodiment 1 FIG. Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a plan view showing an earth ring according to an embodiment of the present invention, FIG. 2 is a sectional view taken along line AA of FIG. 1, and FIG. 3 is a longitudinal sectional view showing an electromagnetic flow meter according to an embodiment of the present invention. Corresponding portions shown in FIG. 13 which are prior art are denoted by the same reference numerals, and description thereof will be omitted. In the drawing, reference numeral 12 denotes a metal earth ring having an inner hole 12a formed in an annular shape and having a convex portion 12b formed concentrically with the inner hole 12a to ensure the sealing property of the flow path. The part 12b is interposed so as to be adjacent to the end faces of the conduits 2 and 3 and the end face of the flange part 11b of the measuring pipe 7. By providing the earth ring 12 in this manner, the flow path of the fluid to be measured is provided between the earth ring 12 and the end faces of the pipes 2 and 3 and between the earth ring 12 and the end face of the flange portion 11b of the measurement pipe 7. A concave portion 15 is formed which communicates with the recess. 12c is
It is a liquid contact surface portion which is located between the convex portion 12b and the inner hole 12a to form a concave portion 15 and comes into contact with the fluid to be measured. The convex portion 12b may be formed only on one surface on the upstream side or the downstream side of the earth ring 12.

Next, an operation example will be described. The operation principle of the flow rate measurement is the same as that of the prior art, so that the description will be omitted, and the points different from the prior art will be described. The fluid to be measured flowing from the upstream pipe 2 is supplied to the earth ring 12.
Flows through the inner hole 12a and the measurement pipe 7 to the downstream conduit 3, but since the concave portion 15 is formed in the flow path of the fluid to be measured, the concave portion 15 is also filled with the fluid to be measured. And is in contact with the liquid contact surface portion 12c. That is, according to the configuration of the first embodiment, since the concave portion 15 is formed, the liquid contact surface portion 12c can be formed on the earth ring 12, so that the liquid contact area of the earth ring 12 is larger than that of the conventional electromagnetic flowmeter. As a result, insulation due to oxidation of the earth ring can be prevented, and a stable flow signal can be detected. Further, according to the configuration of the first embodiment, since the convex portion 12b is formed on the earth ring 12, the flow can be performed without providing a gasket between the earth ring 12 and the conduits 2, 3 or the measuring tube 7. Road sealability can be ensured.

Embodiment 2 FIG. Another embodiment of the present invention will be described with reference to the drawings. 4 is a plan view showing an earth ring according to another embodiment of the present invention, FIG. 5 is a sectional view taken along line BB of FIG. 4, and FIG. 6 is a longitudinal sectional view showing an electromagnetic flow meter according to another embodiment of the present invention. is there. In the drawing, reference numeral 12 denotes a metal earth ring having an inner hole 12a, formed in an annular shape, and having a corner 12d bent so as to have a substantially wavy cross section. It is interposed in. This corner 1
2d is formed to secure the sealing property of the flow path. The corner 12d may be formed only on one surface on the upstream side or the downstream side of the earth ring 12.

An example of the operation is the same as that of the first embodiment, and a description thereof will be omitted. Further, according to the configuration of the present embodiment,
Even when it is necessary to reduce the thickness of the earth ring 12 and the projection 12b in the first embodiment cannot be formed,
The corners 12d having the same role as the protrusions 12b can be easily bent and formed, and the same effects as those of the first embodiment can be obtained.

Embodiment 3 FIG. Another embodiment of the present invention will be described with reference to the drawings. 7 is a plan view showing an earth ring according to another embodiment of the present invention, FIG. 8 is a cross-sectional view taken along the line CC of FIG. 7, and FIG. 8 is a longitudinal sectional view showing an electromagnetic flow meter according to another embodiment of the present invention. is there. In the figure, reference numerals 4 and 5 denote annular gaskets having an inner diameter larger than the inner diameters of the conduits 2 and 3. Reference numeral 12 denotes an O-ring groove 1 for forming an annular shape having an inner hole 12a and for providing an O-ring 16.
2f are provided on the front and back, and a large number of through holes 12 are formed between the O-ring groove 12f and the inner hole 12a as a liquid contact surface portion 12c.
e is a metal grounding ring provided with e. The earth ring 12 is interposed at the same position as in the first embodiment via the gaskets 4 and 5. That is, the gaskets 4 and 5 and the earth ring 12 serve as the first embodiment.
A recess 15 similar to the above is formed.

Next, an operation example different from the first embodiment will be described. According to the present embodiment, since the liquid contacting surface portion 12c of the earth ring 12 is provided with a large number of through holes 12e, the fluid to be measured contacts not only the inner hole 12a but also the through hole 12e. Therefore, according to the present embodiment, a larger liquid contact area can be secured than in the case of the first embodiment, insulation due to oxidation of the earth ring can be prevented, and a stable flow signal can be detected.

Embodiment 4 FIG. Another embodiment of the present invention will be described with reference to the drawings. FIG. 9 is a longitudinal sectional view showing an electromagnetic flow meter according to another embodiment of the present invention,
FIG. 10 is a plan view showing an earth ring according to another embodiment of the present invention, FIG. 11 is a sectional view taken along line DD of FIG. 10, and FIG. 12 is a longitudinal sectional view showing an electromagnetic flow meter according to still another embodiment of the present invention. It is. In the drawing, reference numeral 12 denotes an O-ring groove 12f for forming an O-ring 16 on the front and back sides and having an inner hole 12a formed in an annular shape.
A plurality of guide bore (cut communicating with the inner hole 12a and wetted surface 12c to the liquid contact surface 12c between the 2f and the inner hole 12a
(Missing portion) It is a metal earth ring provided with 12 g.
This earth ring 12 is interposed similarly to the first embodiment.

Next, an operation example will be described. According to the present embodiment, since the plurality of guide holes 12g communicating with the inner holes 12a are formed in the earth ring 12, the fluid to be measured comes into contact with the inner surfaces of the guide holes 12g as well as the inner holes 12a. Therefore, according to the present embodiment, it is possible to secure a large liquid contact area, prevent insulation due to oxidation of the earth ring,
A stable flow signal can be detected. Further, by forming the guide hole 12g, a large liquid contact area can be secured without forming the concave portion 15 as formed in the first embodiment and the like.

[0016]

As described above, according to the present invention, the measured
The contact area with the constant fluid is smaller than that of the electrode with negative potential.
Forming a concave portion communicating with the flow path of the fluid to be measured in at least one of between the earth ring and the pipe line or between the earth ring and the measurement tube so that the sling is sufficiently large ; Communicate with the inner hole in the ring
The notch is formed so that the large contact area of the earth ring prevents the insulation of the earth ring from being oxidized and the effect of obtaining an electromagnetic flow meter that can detect a stable flow signal can be obtained. is there.

[Brief description of the drawings]

FIG. 1 is a plan view showing an earth ring according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a longitudinal sectional view showing an electromagnetic flow meter according to one embodiment of the present invention.

FIG. 4 is a plan view showing an earth ring according to another embodiment of the present invention.

FIG. 5 is a sectional view taken along line BB of FIG. 4;

FIG. 6 is a longitudinal sectional view showing an electromagnetic flow meter according to another embodiment of the present invention.

FIG. 7 is a plan view showing an earth ring according to another embodiment of the present invention.

8 is a sectional view taken along the line CC of FIG. 7;

FIG. 9 is a longitudinal sectional view showing an electromagnetic flow meter according to another embodiment of the present invention.

FIG. 10 is a plan view showing an earth ring according to another embodiment of the present invention.

FIG. 11 is a sectional view taken along line DD of FIG. 10;

FIG. 12 is a longitudinal sectional view showing an electromagnetic flow meter according to another embodiment of the present invention.

FIG. 13 is a longitudinal sectional view showing a conventional electromagnetic flow meter.

[Description of Signs] 2, 3 Pipeline 7 Measurement Tube 8 Excitation Coil (Magnetic Flux Generator) 11 Lining 12 Earth Ring 12a Inner Hole 12g Induction Hole(Notch)  14 electrode 15 recess

────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Shin Suzuki 4-1-1, Omagari, Samukawa-cho, Koza-gun, Kanagawa Prefecture Inside the Shonan Plant of Yamatake Honeywell Co., Ltd. (72) Inventor Junichi Tsuboi 4-28, Nishirokugo, Ota-ku, Tokyo No. 1 Yamatake Honeywell Co., Ltd. Kamata Factory (56) References Hira 4-49821 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) G01F 1/58

Claims (1)

(57) [Claims] 1. A measurement pipe provided between an upstream pipe and a downstream pipe serving as a flow path of a fluid to be measured, a lining stretched on an inner surface of the measurement pipe, and provided in the measurement pipe. A magnetic flux generator for generating a magnetic flux at the electrode, and an earth ring provided between the upstream pipe and the downstream pipe and the measurement pipe and having an inner hole serving as a flow path of a fluid to be measured. The contact area with the fluid to be measured is
The earth ring is closer than the electrode having the negative potential.
Is sufficiently large, at least one of between the earth ring and the pipe line or between the earth ring and the measurement tube is formed with a concave portion communicating with the flow path of the fluid to be measured, or An electromagnetic flowmeter, wherein a notch communicating with the inner hole is formed in an earth ring.