JP4671260B2 - Electromagnetic flow meter - Google Patents

Description

  The present invention relates to an electromagnetic flowmeter used for measuring the flow rate of a conductive fluid flowing in a measurement tube, and more particularly to a structure for attaching an earth ring to a measurement tube.

  There are two types of electromagnetic flowmeters: a flange type in which a measuring pipe made of a straight pipe is provided, and flanges for pipe connection are integrally provided at both ends thereof, and a wafer type in which no flange is provided. In the case of the flange type, the lining material is coated on the inner peripheral surface of the measurement tube and the pipe connection end surface (flange end surface). In the case of the wafer type, the lining material is also applied to the inner peripheral surface of the measurement tube and the pipe connection end surface. Coated. Further, a pair of saddle-shaped excitation coils are arranged on the outer peripheral surface of such a measurement tube so as to face each other with the measurement tube interposed therebetween, and a pair of electrodes orthogonal to the magnetic field of the excitation coil are disposed. Conductive fluid that flows through the measurement tube by passing through the tube wall, attaching an earth ring to the pipe connection end surface, and generating a magnetic field in the direction perpendicular to the fluid flow direction by the pair of excitation coils. An electromotive force proportional to the average flow velocity is generated therein, and the electromotive force is taken out by the pair of electrodes and processed to measure the flow rate or the average flow velocity of the fluid (for example, Patent Document 1). To 3).

Japanese Utility Model Publication No. 7-12927 Japanese Utility Model Publication No. 6-78820 JP 2002-277299 A (described in paragraph “0031”, FIG. 5)

  As the lining material coated on the measuring tube, fluororesin, neoprene or the like is used in order to ensure electrical insulation and corrosion resistance. The earth ring has the function of guiding the potential of the measurement fluid to the arithmetic processing circuit as a reference potential and the function of protecting the lining material. Normally, when the measurement tube is made of metal, it is fixed to the measurement tube and the measurement tube is not In the case of metal, it is fixed to a metal case covering the outer circumference of the measuring tube.

  When fixing the earth ring to the measuring tube, if the piping is made of synthetic resin, it is weak in strength, so the measuring tube cannot be flanged to the piping with a large tightening force. It may become impossible to seal the gap well. In such a case, a gasket made of an elastic material such as rubber is interposed between the lining material and the earth ring so as to ensure a seal. In addition, not only the piping material but also the hard lining material such as ceramic cannot be sealed well between the lining material and the earth ring, so a rubber gasket is interposed between them. Yes.

  However, the gasket is formed in a ring shape (ring shape smaller in diameter than the earth ring) according to the shape of the earth ring, and is inserted between the lining material and the earth ring until the electromagnetic flow meter is attached to the pipe. There was a problem that it was easy to fall.

  In order to avoid such a problem, there has been known one employing a gasket mounting structure as shown in FIGS. 11 to 13 or Japanese Patent Application Laid-Open No. 2002-277299 (FIG. 5). 11A and 11B are a cross-sectional view and a left side view showing a conventional example of a measuring tube of an electromagnetic flow meter. The measuring tube 1 is a wafer type measuring tube, and the lining material 2 is coated on the inner peripheral surface 1a of the tube wall and the pipe connection end surface 1b. Reference numeral 3 denotes an earth ring attached to each pipe connection end face 1b of the measuring pipe 1 via a gasket 4, and an annular groove 5 into which the gasket 4 is fitted is formed on the inner side face. In addition, two connection portions 6 are integrally extended on the outer periphery of the earth ring 3, and these connection portions 6 are fixed to the outer peripheral surface 1 c of the tube wall of the measurement tube 1 by a set screw 7 and are electrically connected. I try to let them. In addition, 8 is an exciting coil and 9 is an electrode.

  FIGS. 12A and 12B are a cross-sectional view and a left side view showing another conventional example of a wafer type measurement tube, on the surface of the lining material 2A coated on the pipe connection end surface 1b of the measurement tube 1. An annular groove 10 is formed, and the gasket 4 is fitted into the annular groove 10 to prevent the gasket 4 from falling off.

  FIGS. 13A and 13B are a cross-sectional view and a left side view showing still another conventional example of a wafer type measurement tube. The cylindrical portion 11 projects integrally with the outer periphery of the pipe connection end surface 1b of the measurement tube 1. The gasket 4 is fitted into the cylindrical portion 11 to prevent the gasket 4 from falling off.

Here, although the measuring tube 1 of the wafer-type without a flange also Re not a 11 to 13 cups, it may be employed a structure similar to the case of the measuring pipe flange type. For example, the mounting structure of the earth ring shown in FIG. 5 of the Japanese Patent Application Laid-Open No. 2002-277299 is formed with an annular groove for accommodating the gasket 4 on the inner surface of the earth ring 3 in the same manner as the structure shown in FIG. It is what.

  However, the conventional structure shown in FIG. 11 and the ground ring mounting structure shown in FIG. 5 of the Japanese Patent Application Laid-Open No. 2002-277299 need to form the annular groove 5 on the inner surface of the ground ring 3. In addition to the increase in the number of processing steps and the manufacturing cost, there is a problem that the number of types of the earth ring 3 increases, and it cannot be commonly used for a measuring tube that does not require the gasket 4. Further, when the annular groove 5 is shallow, the gasket 4 is likely to drop off, so that there is a problem that it must be fixed by an adhesive or the like.

  In the conventional structure shown in FIG. 12, since the annular groove 10 must be formed on the surface of the lining material 2A coated on the pipe connection end face 1b of the measurement pipe 1, the types of the measurement pipe 1 are increased, and the gasket 4 is provided. There was a problem that it could not be used in common for measurement tubes that were not required. In addition, the thickness of the lining material 2A at the portion where the annular groove 10 is formed is thinner than the other portions, and there is a problem that the strength is weakened.

  In the conventional structure shown in FIG. 13, since it is necessary to integrally project the cylindrical portion 11 on the pipe connection end face 1b of the measurement tube 1, not only the types of the measurement tube 1 are increased, but the length of the measurement tube 1 itself is increased. There is a problem that the material cost becomes high and the material cost becomes high. In addition, if the depth of the cylindrical portion 11 is shallow, the gasket 4 is likely to drop off, and there is a problem that it must be fixed with an adhesive or the like.

  The present invention has been made in order to solve the above-described conventional problems. The object of the present invention is to have a simple structure, and it is not necessary to perform special processing on the measuring tube and the lining material, so that parts can be shared. It is possible to provide an electromagnetic flow meter that enables the gasket to be surely prevented from falling off.

In order to achieve the above object, the present invention provides an electromagnetic flowmeter in which an earth ring is attached to a pipe connection end face of a measurement pipe via a gasket, and the measurement pipe is covered with a case, and a plurality of connections are made to the outer peripheral face of the earth ring. A portion projecting in the axial direction of the measuring tube, and the grounding ring is located on the piping side of the gasket, and the gasket is interposed between the grounding ring and the pipe connection end surface of the measuring tube. than said ground ring on the pipe side is formed in a ring shape does not project, and a plurality of projecting portions having an insertion hole which issued outside Zhang on the outer peripheral surface thereof corresponding to the plurality of connection portions of the ground ring by collision And connecting each of the connection parts of the earth ring to the corresponding insertion hole of each overhanging part of the gasket, and fixing the tip part to the measuring tube or the case.

In the present invention, since the earth ring and the gasket are coupled to each other by inserting the connecting portion of the earth ring through the insertion hole of the overhanging portion of the gasket, the gasket is interposed between the pipe connection end face of the measuring tube and the earth ring. Can be prevented from falling off. In addition, since it is only necessary to integrally extend the overhanging part with an insertion hole in the gasket, there is no need to perform special processing on the measuring tube or grounding ring, and it is common to electromagnetic flowmeters that do not require a gasket. Can be used as a part .

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.
1 is a front view showing an embodiment of an electromagnetic flow meter according to the present invention, FIG. 2 is a side view of the electromagnetic flow meter, FIG. 3 is a cross-sectional view of the electromagnetic flow meter, and FIG. 5 is an exploded perspective view of the measuring tube, the earth ring, and the gasket, and FIG. 6 is a front view of the gasket. In the figure, the same components and parts as those shown in the prior art column are indicated by the same reference numerals, and the description thereof will be omitted as appropriate. In these drawings, the present embodiment shows an example applied to an electromagnetic flow meter 20 provided with a wafer type measuring tube 1.

  The electromagnetic flow meter 20 includes a measuring tube 1, a metal case 21 made of a cylindrical body with both ends open covering the outer periphery of the measuring tube 1, and a conversion unit provided at the upper end of the neck portion 21 </ b> A of the case 21. 22 etc.

  The measuring tube 1 is a wafer-type straight tube formed of a nonmagnetic material such as SUS and open at both ends, and the inner peripheral surface 1 a of the tube wall and the pipe connection end surface 1 b are covered with the lining material 3. In addition, the measuring tube 1 is attached with a 180 ° phase shift in the circumferential direction so that a pair of exciting coils 8, 8 formed in a bowl shape on the outer peripheral surface 1 c of the tube wall face each other in the vertical direction, and a pair of electrodes 9. , 9 are also provided with a 180 ° phase shift in the circumferential direction so that they face each other in the left-right direction. For this reason, the exciting coil 8 and the electrode 9 are alternately arranged with a 90 ° phase shift in the circumferential direction of the measuring tube 1. Further, the axis of the electrode 9 is orthogonal to the axis of the measuring tube 1, in other words, the flow direction of the conductive fluid 23 flowing in the measuring tube 1, and the magnetic flux Φ of the excitation coil 8 in the center of the measuring tube 1 is It is orthogonal to the axis.

Further, an earth ring 3 is attached to each pipe connection end face 1 b of the measurement pipe 1 via a gasket 4. The earth ring 3 is formed in a disc shape whose outer diameter is substantially equal to or slightly larger than the outer diameter of the measuring tube 1 by SUS, platinum, titanium, monel, Hastelloy, etc., and the inner circumference of the tube wall of the measuring tube 1 at the center. It has a center hole 24 substantially equal to the inner diameter of the lining material 2B lined on the surface 1a, and a pair of connecting portions 6 and 6 are integrally extended on the outer periphery with a 180 ° phase shift in the circumferential direction. . These connecting portions 6 have screw attachment holes 25 and are bent by approximately 90 ° on the back surface side.

  The gasket 4 is formed in a disk shape having substantially the same size as the earth ring 3 by an elastic material such as rubber, and an insertion hole 27 having the same size as the center hole 24 of the earth ring 3 is formed at the center. A pair of overhanging portions 28, 28 are integrally projected on the outer periphery with a 180 ° separation in the circumferential direction. The overhanging portion 28 is provided corresponding to the connecting portion 6 of the earth ring 3 and has a slit-like insertion hole 29 through which the connecting portion 6 passes.

When attaching the earth ring 3 to the pipe connection end face 1 b of the measuring pipe 1, the pair of connection parts 6, 6 of the earth ring 3 are inserted into the insertion holes 29 of the overhanging parts 28, 28 of the gasket 4. The ring 3 is brought into close contact with the surface of the gasket 4. In this state, the gasket 4 is brought into close contact with the surface of the lining material 2A coated on the pipe connection end face 1b of the measurement pipe 1. Then, each connection portion 6 is brought into close contact with the outer peripheral surface 1c of the tube 1 of the measuring tube 1, and the set screw 7 is inserted into the screw mounting hole 25 to form the screw hole 30 formed in the outer peripheral surface 1c of the measuring tube 1. When screwed in, the earth ring 3 can be fixed to the pipe connection end face 1b of the measuring tube 1 via the gasket 4, and thereby the potentials of the measuring tube 1 and the fluid 23 flowing in the measuring tube 1 are made equal. Further, the earth ring 3 is electrically connected to the arithmetic processing circuit in the conversion unit 22 to guide the potential of the fluid 23 as a reference potential.

In the electromagnetic flow meter 20 having such a structure, the connecting portion 6 of the earth ring 3 is inserted into the insertion hole 29 of the overhanging portion 28 provided in the gasket 4 so that the earth ring 3 and the gasket 4 are coupled. The gasket 4 can be reliably prevented from falling off between the measuring tube 1 and the earth ring 3 before connecting the measuring tube 1 to the piping.
Further, since it is not necessary to provide a special annular groove for the gasket in the lining 2 or the earth ring 3, the measuring tube 1 and the earth ring 3 can be used as a common part in an electromagnetic flow meter that does not require the gasket 4. And the number of parts can be reduced.

  7 is a cross-sectional view of a measurement tube showing another embodiment of the present invention, FIG. 8 is a side view of the measurement tube, FIG. 9 is a perspective view of an earth ring, and FIG. 10 is a front view of a gasket. This embodiment shows an example applied to a flange type measuring tube. For this reason, disc-shaped flanges 40 and 41 are integrally provided at both ends of the outer peripheral surface of the measuring tube 1. Further, the lining material 2 is coated on the inner peripheral surface 1a of the measuring tube 1 and the end faces (piping connection end faces) 42 of the flanges 40 and 41.

  An earth ring 3 is attached to each pipe connection end face 42 of the measuring pipe 1 via a gasket 4. In FIG. 7, only the earth ring 3 and gasket 4 attached to the left side surface of the measuring tube 1 are shown, and the illustration of the earth ring and gasket attached to the right side surface is omitted.

The earth ring 3 has a center hole 24 formed at the center and a pair of connecting portions 6 integrally extending on the outer periphery. The connecting portion 6 has a U-shape when the distal end portion is folded back, and insertion holes 25 and 44 are formed at the base end portion and the distal end portion so that the axes coincide with each other. The insertion hole 25 on the proximal end side is formed in a hole larger than the outer diameter of the head of the set screw 7 that fixes the connection portion 6 to the measuring tube 1, and the insertion hole 44 on the distal end side is formed from the outer diameter of the screw portion of the set screw 7. The hole is larger and smaller than the outer diameter of the head.

  The gasket 4 is formed in a thin disk shape by an elastic material such as rubber, and a pair of overhang portions 28 having insertion holes 29 are integrally projected on the outer periphery. The insertion hole 29 is formed as a rectangular hole having a size that allows the connection portion 6 of the earth ring 3 to be inserted.

In order to attach the earth ring 3 to the measuring tube 1, the earth ring 3 is brought into close contact with the surface of the gasket 4, and the connecting portion 6 is aligned with the insertion hole 29 of the overhanging portion 28 of the gasket 4. Thereby, the front-end | tip part of the connection part 6 is inserted in the insertion hole 29, and protrudes in the back surface side of the gasket 4. FIG. In this state, when the gasket 4 is brought into close contact with the surface of the lining material 2 </ b> A covering the flange surface, the tip of the connecting portion 6 comes into close contact with the surface of the flange 40. Then, the set screw 7 is inserted into the screw mounting holes 25 and 44 of the connection portion 6 and screwed into the screw holes provided in the flange end face, and the connection portion 6 is fixed to the flange 40 of the measuring tube 1.

  It will be clear that even in such a structure, the gasket 4 can be reliably prevented from falling off as in the above-described embodiment.

In the above-described embodiment, the example in which the pair of connection portions 6 protrudes from the earth ring 3 is shown. However, the present invention is not limited to this, and the number of the connection portions 6 can be appropriately increased. The same number of overhanging portions 28 as the number of the connecting portions 6 may be extended to the gasket 4.

It is a front view which shows one Embodiment of the electromagnetic flowmeter which concerns on this invention. It is a side view of the same electromagnetic flowmeter. It is sectional drawing of the same electromagnetic flowmeter. It is a left view of a measurement tube. It is a disassembled perspective view of a measurement tube, an earth ring, and a gasket. It is a front view of a gasket. It is sectional drawing of the measurement pipe | tube which shows other embodiment of this invention. It is a side view of the measuring tube. It is a perspective view of an earth ring. It is a front view of a gasket. (A), (b) is sectional drawing and the left view which show the prior art example of the measuring tube of an electromagnetic flowmeter. (A), (b) is sectional drawing and the left view which show the prior art example of the other measurement pipe | tube of an electromagnetic flowmeter. (A), (b) is sectional drawing and the left view which show the other conventional example of the measuring tube of an electromagnetic flowmeter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Measuring tube, 2 ... Lining material, 3 ... Earth ring, 4 ... Gasket, 6 ... Connection part, 20 ... Electromagnetic flowmeter, 21 ... Case, 22 ... Conversion part, 28 ... Overhang | projection part, 29 ... Insertion hole.

Claims (1)

In an electromagnetic flowmeter in which a ground ring is attached to a pipe connection end face of a measurement pipe via a gasket, and the measurement pipe is covered with a case,
A plurality of connecting portions projecting in the axial direction of the measuring pipe on the outer peripheral surface of the earth ring, and the earth ring is located on the pipe side from the gasket;
The gasket is said by being interposed between the pipe connection end face of the grounding ring and the measuring pipe to the pipe side of the earth ring are formed in a ring shape not protruding, and insertion hole overhanging outward on the outer circumferential surface thereof A plurality of projecting portions having projections corresponding to the plurality of connecting portions of the earth ring, and the respective connecting portions of the earth ring are inserted into the insertion holes of the corresponding projecting portions of the gasket, and the tips thereof An electromagnetic flowmeter characterized in that a portion is fixed to the measuring tube or the case.

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