JP2004294176A - Electromagnetic flowmeter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic flowmeter that can be excited at a high frequency, can obtain high magnetic flux density, and has a magnetic circuit having improved efficiency. <P>SOLUTION: The electromagnetic flowmeter having a magnetic circuit having a columnar core has the columnar core comprising a cylindrical outer-periphery section that is a high volume resistivity material and is made of a low-permeability material; and a columnar inner-periphery section that is inserted into the outer-periphery section, is a low volume resistivity material, and is made of a high-permeability material. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electromagnetic flowmeter capable of high-frequency excitation, obtaining a high magnetic flux density, and having an efficient magnetic circuit.
[0002]
[Prior art]
FIG. 14 is an explanatory view of a configuration of a conventional example generally used in the past, and FIG. 15 is a side view of FIG. 14, which is shown in, for example, a doctoral dissertation "Research on High Performance of Electromagnetic Flowmeter" by Kenichi Kuromori. (For example, see Non-Patent Document 1.)
[0003]
In FIG. 14, two columnar cores 2 long in the radial direction of the measurement tube 1 are provided on the peripheral surface of the pipe-shaped measurement tube 1 with the measurement tube 1 interposed therebetween.
In this case, a silicon steel sheet having a thickness of about 0.3 mm is laminated.
A bobbin type coil 3 is attached to the peripheral surface of the core 2.
A return core 4 is attached outside the core 2 and the coil as a return path for the magnetic field.
[0004]
FIG. 16 is a diagram for explaining the configuration of another conventional example generally used in the past, which is shown in, for example, a doctoral dissertation “Research on High Performance of Electromagnetic Flowmeters” by Kenichi Kuromori (for example, Non-Patent Document 2). reference.).
[0005]
In FIG. 16, two columnar cores 5 long in the radial direction of the measurement tube 1 are provided on the peripheral surface of the pipe-shaped measurement tube 1 with the measurement tube 1 interposed therebetween.
In this case, carbon steel or ferritic stainless steel is used.
The bobbin type coil 3 is attached to the peripheral surface of the core 7.
A return core 4 is attached outside the core 7 and the coil 3 as a return path for the magnetic field.
[0006]
[Non-patent document 1]
Kenichi Kuromori, Ph.D. Dissertation "Study on High Performance of Electromagnetic Flowmeter", submitted to Waseda University, February 1995, p. 79
[Non-patent document 2]
Kenichi Kuromori, Ph.D. Dissertation "Study on High Performance of Electromagnetic Flowmeter", submitted to Waseda University, February 1995, p. 112
[0007]
[Problems to be solved by the invention]
However, such a device has the following problems.
In the case of the laminated core 2 made of a silicon steel sheet, although the frequency characteristics and the magnetic field characteristics are good, the laminated cores are scattered and easily distorted, so that it is very difficult to assemble them.
In addition, potting of epoxy resin or the like is required for fixing the magnetic circuit.
[0008]
In the case of the carbon steel core 5, since the volume resistivity is small, convergence of the eddy current generated upon excitation is slow, and it is impossible to excite at high frequency.
In the case of the ferritic stainless steel core 5, the volume resistivity is several times larger than that of carbon steel, so that high-frequency excitation is possible. However, since the magnetic permeability is lower than that of silicon steel sheet, the obtained magnetic flux density has a laminated core of silicon steel sheet. And the efficiency as a magnetic circuit is not good.
[0009]
An object of the present invention is to solve the above-mentioned problems and to provide an electromagnetic flowmeter having a highly efficient magnetic circuit capable of high-frequency excitation, obtaining a high magnetic flux density.
[0010]
[Means for Solving the Problems]
In order to achieve such an object, in the present invention, in the electromagnetic flowmeter according to claim 1,
In an electromagnetic flowmeter having a magnetic circuit having a columnar core,
It has a cylindrical outer peripheral portion made of a high volume resistivity material and a low magnetic permeability material, and a columnar inner peripheral portion inserted into the outer peripheral portion and made of a low volume resistivity material and a high magnetic permeability material. Characterized by having a columnar core that is
[0011]
In the electromagnetic flowmeter according to claim 2 of the present invention, in the electromagnetic flowmeter according to claim 1,
The material of the outer peripheral portion is made of a ferritic stainless steel.
[0012]
In the electromagnetic flowmeter according to claim 3 of the present invention, in the electromagnetic flowmeter according to claim 1 or 2,
The material of the inner peripheral portion is made of an electromagnetic pure iron material.
[0013]
In the electromagnetic flow meter according to the fourth aspect of the present invention, in the first to third aspects,
The outer peripheral portion has a cylindrical shape having a bottom portion, and the inner peripheral portion is inserted and fixed in the cylindrical portion.
[0014]
In the electromagnetic flowmeter according to claim 5 of the present invention, in the electromagnetic flowmeter according to any one of claims 1 to 4,
The inner peripheral portion has a flange at one end, and the outer peripheral portion is inserted and fixed to the inner peripheral portion.
[0015]
In the electromagnetic flowmeter according to claim 6 of the present invention, in the electromagnetic flowmeter according to any one of claims 1 to 5,
A locking means is provided at the end of the core opposite to the side to which the measuring tube is attached, and is provided with locking means for locking the return core.
[0016]
In the electromagnetic flow meter according to claim 7 of the present invention, in the electromagnetic flow meter according to claim 6,
The locking means locks the return core with an opening end portion of the outer peripheral portion and a flange portion provided on an opening end portion side of the outer peripheral portion of the inner peripheral portion.
[0017]
In the electromagnetic flow meter according to claim 8 of the present invention, in the electromagnetic flow meter according to claim 7,
The outer peripheral portion and the inner peripheral portion are screwed and fixed.
[0018]
In the electromagnetic flowmeter according to claim 9 of the present invention, in the electromagnetic flowmeter according to claim 6,
The locking means includes an opening end portion of the outer peripheral portion, a projecting portion provided on the opening end portion side of the outer peripheral portion of the inner peripheral portion, and the return core fixed to the projecting portion and connecting the return core to the outer peripheral portion. And a ring-shaped locking ring that is pressed and locked to the open end portion.
[0019]
In the electromagnetic flowmeter according to claim 10 of the present invention, in the electromagnetic flowmeter according to claim 9,
The protrusion and the locking ring are screwed and fixed.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is an explanatory view of a main part of an embodiment of the present invention, FIG. 2 is a side view of FIG. 1, and FIG. 3 is a plan view of FIG.
In the figure, the configuration of the same symbol as in FIG. 14 represents the same function.
Hereinafter, only differences from FIG. 14 will be described.
[0021]
The cylindrical outer peripheral portion 11 is made of a material having a high volume resistivity and a low magnetic permeability.
In this case, for example, a ferritic stainless steel material is used.
The thickness is about 1/3 of the radius.
[0022]
The columnar inner peripheral portion 12 is inserted into the outer peripheral portion 11 and is made of a material having a low volume resistivity and a high magnetic permeability.
In this case, for example, an electromagnetic pure iron material is used.
[0023]
As a result, a material having a high volume resistivity and a low magnetic permeability is used for the outer peripheral portion 11 where the eddy current is strongly generated, so that the influence of the eddy current can be reduced and the frequency characteristics are improved. Therefore, an electromagnetic flowmeter capable of high-frequency excitation can be obtained.
[0024]
In addition, since a material having a low volume resistivity and a high magnetic permeability is used for the inner peripheral portion 12, a high magnetic flux density can be obtained and an electromagnetic flowmeter capable of forming an efficient magnetic circuit can be obtained. Is obtained.
[0025]
FIG. 4 is an explanatory view of a main part of another embodiment of the present invention, and FIG. 5 is a plan view of FIG.
In the present embodiment, the outer peripheral portion 21 has a tubular shape having a bottom portion 211, and the inner peripheral portion 22 is inserted and fixed in the tubular portion.
[0026]
As a result, it is possible to obtain an electromagnetic flowmeter in which the amount of the high volume resistivity material used in the outer peripheral portion 21 is increased and the excitation characteristics at high frequencies are improved.
[0027]
FIG. 6 is an explanatory view of a main part of another embodiment of the present invention, and FIG. 7 is a plan view of FIG.
In this embodiment, the inner peripheral portion 31 has a flange 311 at one end, and the outer peripheral portion 32 is inserted and fixed to the inner peripheral portion 31.
[0028]
As a result, the high volume resistivity material is used only in the portion 32 that contacts the bobbin coil where the eddy current is generated particularly strongly, and the portion 311 using the material having high magnetic permeability is increased, and the magnetic efficiency of the core is further improved. An electromagnetic flowmeter is obtained.
[0029]
FIG. 8 is an explanatory view of a main part of another embodiment of the present invention, FIG. 9 is a side view of FIG. 8, and FIG. 10 is a plan view of FIG.
In this embodiment, the locking means 40 is provided at the end of the core opposite to the side on which the measuring tube 1 is mounted, and locks the return core 4.
[0030]
In this case, the locking means 40 locks the return core 4 with the open end portion 411 of the outer peripheral portion 41 and the flange portion 421 provided on the open end portion 411 side of the outer peripheral portion of the inner peripheral portion 42. .
In this case, the outer peripheral portion 41 and the inner peripheral portion 42 are screwed and fixed.
[0031]
As a result,
Since the magnetic circuit is formed by combining the core and the return core 4, the return core 4 can be locked by the core itself, so that an electromagnetic flowmeter with improved performance and reduced cost can be obtained.
[0032]
The locking means 40 locks the return core 4 with the open end portion 411 of the outer peripheral portion and the flange portion 421 provided at one end of the inner peripheral portion. The outer peripheral portion 41 and the inner peripheral portion 42 are also connected to each other, and an electromagnetic flowmeter with further improved assemblability is obtained.
[0033]
The outer peripheral portion 41 and the inner peripheral portion 42 are screwed together and fixed, so that the screw connection does not come out completely, and the fixing is reliable. A detachable electromagnetic flowmeter can be obtained.
[0034]
Since the return core 4 is fixed at the same time, an electromagnetic flowmeter having the reliability of fixing the return core 4 and the freedom of attachment and detachment can be obtained.
[0035]
FIG. 11 is an explanatory diagram of a main part of another embodiment of the present invention, FIG. 12 is a side view of FIG. 11, and FIG. 13 is a plan view of FIG.
In the present embodiment, the locking means 50 is fixed to the opening end portion 511 of the outer peripheral portion 51, the protruding portion 521 provided on the outer peripheral portion of the inner peripheral portion 52 on the opening end portion 511 side, and the protruding portion 521. And a ring-shaped locking ring 53 for pressing and locking the return core 4 to the open end portion 511 of the outer peripheral portion.
[0037]
In this case, the protrusion 521 and the locking ring 53 are screwed and fixed.
As a result,
Since the protruding portion 521 is protruded from the inner peripheral portion 52, the return core 4 can be easily positioned, and an electromagnetic flowmeter with improved assemblability can be obtained.
[0038]
Further, since the outer peripheral portion 51 is sandwiched between the flange portion 522 of the inner peripheral portion 52 and the return core 4, the outer peripheral portion 51 can also be fixed by attaching the return core 4 and the locking ring 53. An electromagnetic flowmeter with improved assemblability can be obtained.
[0039]
Since the protrusion 521 and the locking ring 53 are screwed and fixed, the screw connection does not come off completely, and the fixing is reliable. A free electromagnetic flow meter is obtained.
[0040]
In addition, the length of the threaded portion may be only the protruding portion 521, so that an electromagnetic flowmeter with reduced threading time and improved assemblability can be obtained.
Since the return core 4 is fixed at the same time, an electromagnetic flowmeter having the reliability of fixing the return core 4 and the freedom of attachment and detachment can be obtained.
[0041]
It should be noted that the foregoing description has been directed to specific preferred embodiments for the purpose of explanation and illustration of the present invention. Therefore, the present invention is not limited to the above-described embodiment, but includes many more changes and modifications without departing from the spirit thereof.
[0042]
【The invention's effect】
As described above, according to the first aspect of the present invention, the following effects can be obtained.
The eddy current generated in the core by the magnetic flux passing through the core impedes the rise of the magnetic field and lowers the frequency characteristics of the magnetic circuit. The eddy current is strongly generated at the outer periphery of the core.
[0043]
For this reason, an electromagnetic flowmeter that rapidly attenuates eddy currents on the outer periphery of the core, uses high volume resistivity material with good frequency characteristics, improves the frequency characteristics of the magnetic circuit, and enables excitation at high frequencies is obtained. .
[0044]
In addition, a material with high magnetic permeability is used for the inner circumference, which is less affected by eddy currents, even with a low volume resistivity material, so a high magnetic flux density can be obtained and an efficient magnetic circuit can be obtained. The following electromagnetic flow meter is obtained.
In addition, since the outer peripheral portion and the inner peripheral portion use columnar metal materials, an electromagnetic flowmeter excellent in availability and processability can be obtained.
[0045]
According to the second aspect of the present invention, the following effects are obtained.
Since the material of the outer periphery is made of ferritic stainless steel, in general, ferrite stainless steel is a material with high volume resistivity and low magnetic permeability. Is obtained.
[0046]
According to the third aspect of the present invention, the following effects are obtained.
Since the material of the inner peripheral part is made of electromagnetic pure iron material, electromagnetic pure iron material is generally a low volume resistivity material and a high magnetic permeability material. Is obtained.
[0047]
According to claim 4 of the present invention, the following effects are obtained.
The outer peripheral part has a cylindrical shape with a bottom, and the inner peripheral part is inserted and fixed in the cylindrical part, so the amount of high volume resistivity material used on the outer peripheral part is increased, and the excitation characteristics at high frequencies are further improved. An improved electromagnetic flow meter is obtained.
[0048]
According to claim 5 of the present invention, the following effects are obtained.
The inner peripheral portion has a flange at one end, and the outer peripheral portion is fixed to the inner peripheral portion, so that a high volume resistivity material is used only in a portion particularly in contact with a bobbin coil in which eddy current is generated. An electromagnetic flowmeter in which the magnetic permeability of the core is further improved by increasing the number of sites where the material having the magnetic permeability is used.
[0049]
According to claim 6 of the present invention, the following effects are obtained.
Since the locking means for locking the return core is provided at the end of the core opposite to the measurement tube mounting side, the magnetic circuit is configured by combining the core and the return core. If the return core can be locked by itself, an electromagnetic flowmeter with improved performance and reduced cost can be obtained.
[0050]
According to claim 7 of the present invention, the following effects are obtained.
The locking means locks the return core with the opening end portion of the outer peripheral portion and the flange provided at one end of the inner peripheral portion. The joining of the peripheral portions is also performed, and an electromagnetic flowmeter with further improved assemblability is obtained.
[0051]
According to claim 8 of the present invention, the following effects are obtained.
Since the outer peripheral part and the inner peripheral part are screwed together and fixed, the screw connection does not come off completely, and the fixation is reliable. An electromagnetic flow meter is obtained.
Since the return core is fixed at the same time, an electromagnetic flowmeter having the reliability of fixing the return core and the freedom of attachment and detachment can be obtained.
[0052]
According to claim 9 of the present invention, the following effects are obtained.
The locking means has an open end portion of the outer peripheral portion, a protruding portion provided at one end of the inner peripheral portion, and a ring-shaped portion fixed to the protruding portion to press and lock the return core to the open end portion of the outer peripheral portion. Because of the presence of the locking ring, the protrusion is protruded from the inner peripheral portion, so that the return core can be easily positioned and an electromagnetic flowmeter with improved assemblability can be obtained.
[0053]
In addition, since the outer peripheral portion is sandwiched between the inner peripheral flange portion and the return core, the outer peripheral portion can be fixed by attaching the return core and the locking ring, and the assemblability for fixing the outer peripheral portion is improved. A flow meter is obtained.
[0054]
According to the tenth aspect of the present invention, the following effects can be obtained.
Since the protrusion and the locking ring are screwed together and fixed, the screw connection does not come off completely, and the fixation is reliable. An electromagnetic flow meter is obtained.
[0055]
In addition, since only the length of the threaded portion is sufficient for the protrusion, an electromagnetic flowmeter with reduced threading time and improved assemblability can be obtained.
Since the return core is fixed at the same time, an electromagnetic flowmeter having the reliability of fixing the return core and the freedom of attachment and detachment can be obtained.
[0056]
Therefore, according to the present invention, it is possible to realize an electromagnetic flowmeter capable of high-frequency excitation, obtaining a high magnetic flux density, and having an efficient magnetic circuit.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a main configuration of an embodiment of the present invention.
FIG. 2 is a side view of FIG.
FIG. 3 is a plan view of FIG. 1;
FIG. 4 is an explanatory diagram of a main part configuration of another embodiment of the present invention.
FIG. 5 is a plan view of FIG. 4;
FIG. 6 is an explanatory diagram of a main part configuration of another embodiment of the present invention.
FIG. 7 is a plan view of FIG. 6;
FIG. 8 is an explanatory diagram of a main part configuration of another embodiment of the present invention.
FIG. 9 is a side view of FIG.
FIG. 10 is a plan view of FIG. 8;
FIG. 11 is an explanatory diagram of a main part configuration of another embodiment of the present invention.
FIG. 12 is a side view of FIG. 11;
FIG. 13 is a plan view of FIG. 11;
FIG. 14 is an explanatory view of a configuration of a main part of a conventional example generally used in the related art.
FIG. 15 is a side view of FIG.
FIG. 16 is an explanatory diagram of a main part configuration of another conventional example generally used in the related art.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 measuring tube 2 core 3 coil 4 return core 5 core 11 outer peripheral portion 12 inner peripheral portion 21 outer peripheral portion 211 bottom portion 22 inner peripheral portion 31 inner peripheral portion 311 flange portion 32 outer peripheral portion 40 locking means 41 outer peripheral portion 411 open end portion 42 Inner circumference 421 Flange 50 Locking means 51 Outer circumference 511 Open end portion 52 Inner circumference 521 Projection 53 Lock ring

Claims (10)

In an electromagnetic flowmeter having a magnetic circuit having a columnar core,
It has a cylindrical outer peripheral portion made of a high volume resistivity material and a low magnetic permeability material, and a columnar inner peripheral portion inserted into the outer peripheral portion and made of a low volume resistivity material and a high magnetic permeability material. An electromagnetic flowmeter, comprising: a columnar core. 2. The electromagnetic flowmeter according to claim 1, wherein the outer peripheral portion is made of a ferritic stainless steel. 3. The electromagnetic flowmeter according to claim 1, wherein the inner peripheral portion is made of an electromagnetic pure iron material. The electromagnetic flowmeter according to any one of claims 1 to 3, wherein the outer peripheral portion has a cylindrical shape having a bottom portion, and the inner peripheral portion is inserted and fixed in the cylindrical portion. The electromagnetic flowmeter according to any one of claims 1 to 4, wherein the inner peripheral portion has a flange portion at one end, and the outer peripheral portion is inserted and fixed to the inner peripheral portion. . The electromagnetic flowmeter according to any one of claims 1 to 5, wherein a locking means is provided at an end of the core opposite to a side on which the measurement pipe is mounted to lock a return core. . The locking means,
An open end portion of the outer peripheral portion,
7. The electromagnetic flow meter according to claim 6, wherein the return core is locked by a flange provided on an opening end portion side of the outer peripheral portion of the inner peripheral portion. The electromagnetic flowmeter according to claim 7, wherein the outer peripheral portion and the inner peripheral portion are screwed and fixed. The locking means,
An open end portion of the outer peripheral portion,
A protruding portion provided on the opening end portion side of the outer peripheral portion of the inner peripheral portion,
7. The electromagnetic flowmeter according to claim 6, further comprising a ring-shaped locking ring fixed to the protruding portion and pressing and locking the return core to an opening end portion of the outer peripheral portion. The electromagnetic flowmeter according to claim 9, wherein the protrusion and the locking ring are screwed and fixed.

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