JP2005061847A - Electromagnetic flowmeter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic flowmeter short in the time required for assembling with excellent stability of a characteristic. <P>SOLUTION: In this flowmeter, a magnetic pole 4a is constituted of two components of a core 41a having a core main body part 411 wound with an excitation coil, and a positioning protrusion part 412 fitted into a through hole 421 formed in a pedestal 42a, and the pedestal 42a for contacting with a tube wall of a measuring tube to stabilize the magnetic pole 4a and to optimize a magnetic field distribution, and having the through hole 421 fitted with the positioning protrusion part 412 of the core 41a. The magnetic pole 4a is integrated by welding both components in a welding part 45 under the condition where the positioning protrusion part 412 is fitted into the through hole 421, so as to constitute the magnetic pole 4a. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electromagnetic flowmeter that measures the flow rate of a conductive fluid using electromagnetic induction.
[0002]
[Prior art]
When the conductive fluid passes through the magnetic field, an electromotive force proportional to the flow velocity is generated according to Faraday's law of induction. An instrument that measures the flow rate of a conductive fluid flowing in a magnetic field by measuring this electromotive force is an electromagnetic flowmeter.
As shown in FIG. 2 and FIG. 3, the detector of the electromagnetic flowmeter generally includes a measuring tube 1 made of, for example, stainless steel, through which a fluid to be measured flows, and an electric fluid from the measuring fluid. In order to generate a magnetic field in the lining material 2 made of, for example, fluororesin, which is disposed on the inner surface and the side surface of the measuring tube 1 to insulate the measuring tube 1 and in which the measuring fluid flows, on the outer wall of the measuring tube 1 A pair of magnetic poles 4 arranged opposite to each other and wound with an exciting coil 3, a magnetic path 5 made of a silicon steel plate arranged in contact with the outside of the magnetic pole 4 to reduce leakage magnetic flux, and a pair The lining material 2 is provided through the tube wall of the measurement tube 1 at a position orthogonal to the direction of the magnetic field formed between the magnetic poles 4 and the axial direction of the measurement tube 1 so as to contact the measurement fluid. Is, for example stainless steel Become electrode 6, in being configured.
[0003]
The magnetic pole 4 is composed of a core having a high permeability, for example, a core made of carbon steel and a pedestal, in order to make the detector of the electromagnetic flowmeter small and light and to form a necessary magnetic field distribution in the measuring tube 1. ing.
In the prior art, as shown in FIG. 4, the magnetic pole 4 has a structure in which a base 42 is sandwiched between a core 41 and a stainless steel positioning member 43 and fastened with a stainless steel screw 44. The positioning member 43 facilitates the positioning of the magnetic pole 4 by being inserted into the recess 11 provided in the measurement tube 1 in advance when the magnetic pole 4 is attached to the measurement tube 1. In this conventional example, the positioning member 43 and the screw 44 are made of stainless steel, but can be changed to carbon steel.
In addition, as a structure of this kind of electromagnetic flowmeter, the thing of Unexamined-Japanese-Patent No. 11-118548 (refer patent document 1) is known, for example.
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-118548
[Problems to be solved by the invention]
As described above, the magnetic pole 4 according to the prior art has a structure in which the base 42 is sandwiched between the core 41 and the positioning member 43 and is tightened by the screw 44. For this reason, the time required for the assembly work is long, and if the screw 44 is not sufficiently tightened, the screw 44 may be loosened, and the characteristics of the electromagnetic flow meter may be changed. This is a factor that hinders characteristic stability.
An object of the present invention is to solve the above-described problems, and to provide an electromagnetic flow meter having a short time required for assembly and excellent characteristics stability.
[0006]
[Means for Solving the Problems]
According to the first aspect of the present invention, the flow velocity of the conductive fluid flowing in the measurement tube is determined by a magnetic field generated in the measurement tube by a pair of magnetic poles arranged opposite to the outer wall of the measurement tube and wound with an excitation coil respectively. An electromagnetic flow meter for measuring by an electromagnetic induction electromotive force, wherein the magnetic pole is a core having a core body portion around which an exciting coil is wound and a projecting portion fitted in a through hole formed in a pedestal, and a tube wall of the measurement tube And a pedestal having a through hole in which the magnetic pole is stabilized by optimizing the magnetic field, the magnetic field distribution is optimized, and the protruding portion of the core is fitted, and the protruding portion is fitted in the through hole. It has a magnetic pole of structure.
In this invention, the magnetic pole parts are reduced to two points: a core having a protrusion and a pedestal having a through hole into which the protrusion is fitted. Since the core and the pedestal are integrated with each other by welding, it seems that the screw is loose. The factor which disturbs characteristic stability is lost.
[0007]
In the invention of claim 2, the protruding length of the protruding portion of the core is larger than the plate thickness of the pedestal, and a concave portion for fitting the protruding portion protruding from the pedestal is provided at the magnetic pole arrangement position of the measuring tube. Is formed.
In this invention, the magnetic pole can be positioned by fitting the protruding portion of the core into the recess of the measuring tube, so that the magnetic pole can be accurately and easily positioned.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the electromagnetic flowmeter according to the present invention will be described with reference to examples.
In addition, the same code | symbol is attached | subjected to the part of the same function as a prior art.
The present invention relates to the structure of the magnetic pole of the electromagnetic flow meter, and since the entire configuration of the electromagnetic flow meter is the same as that of the prior art, the description of the entire configuration is omitted, and the structure of the magnetic pole and its related parts are limited. To explain.
FIG. 1 shows the structure of a magnetic pole 4a of an embodiment of an electromagnetic flow meter according to the present invention, where (a) is an overall sectional view, (b) is an outline view of a core 41a, and (c) is a sectional view of a pedestal 42a. is there.
The magnetic pole 4a of this embodiment is composed of two parts: a core 41a made of a ferromagnetic material with high permeability such as carbon steel and pure iron, and a pedestal 42a made of a ferromagnetic material with high permeability such as carbon steel. In addition to the core main body 411 around which the exciting coil is wound, the core 41a is formed with a positioning protrusion 412 having a diameter Φd that is slightly smaller than the core main body 411. On the other hand, a through hole 421 having a diameter ΦD into which the positioning protrusion 412 is fitted is formed at the center of the base 42a. The core 41a and the pedestal 42a are welded along the outer periphery of the contact portion between the core main body 411 and the pedestal 42a (formation of the welded portion 45) in a state where the positioning protrusion 412 is fitted in the through hole 421. Has been.
[0009]
The diameters of the positioning protrusions 412 and the through holes 421 are manufactured with a clearance fit tolerance. That is, Φd and ΦD have a gap fitting tolerance. The length L of the positioning protrusion 412 is larger than the thickness T of the pedestal 42a, and the portion protruding to the lower part of the pedestal 42a is used to position the magnetic pole 4a at a predetermined position of the measuring tube. That is, as described in the section of the prior art, this protruding portion is fitted into a recess formed in the measurement tube, and the magnetic pole 4a is positioned at a predetermined position of the measurement tube.
According to this embodiment, the magnetic pole 4a is composed of two parts, and the two parts are integrated by welding, so that the time required for manufacturing the magnetic pole 4a is shortened. Further, since the magnetic pole 4a is integrated by welding, there is no instability factor such as loosening of screws, and the characteristics of the electromagnetic flow meter are stabilized.
[0010]
【The invention's effect】
According to the first aspect of the present invention, the magnetic pole is stabilized by contacting the core body portion around which the exciting coil is wound and the projecting portion fitted into the through hole formed in the pedestal, and the wall of the measuring tube as the magnetic pole. A magnetic pole having a structure in which the magnetic field distribution is optimized and a base having a through hole into which the protruding portion of the core is fitted is integrated by welding. In addition, the number of the pedestal having the through hole into which the protruding portion is fitted is reduced, and in addition, there is no factor that hinders characteristic stability such as loosening of the screw.
Therefore, according to the present invention, it is possible to provide an electromagnetic flowmeter having a short time required for assembly and excellent characteristic stability.
[0011]
In the invention of claim 2, the magnetic pole can be positioned by fitting the protruding portion of the core into the concave portion of the measuring tube, so that the magnetic pole can be accurately and easily positioned.
[Brief description of the drawings]
1A and 1B show the structure of a magnetic pole 4a of an embodiment of an electromagnetic flowmeter according to the present invention, where FIG. 1A is an overall cross-sectional view, FIG. 1B is an external view of a core 41a, and FIG. 1C is a cross-sectional view of a pedestal 42a; 2 is a cross-sectional view in the direction parallel to the fluid flow showing the structure of an example 100 of a conventional electromagnetic flowmeter detector. FIG. 3 is a cross-sectional view in the direction perpendicular to the fluid flow showing the structure of the conventional example 100 . 4 is a sectional view showing the structure of the magnetic pole 4 of the conventional example 100 .
DESCRIPTION OF SYMBOLS 1 Measurement tube 11 Recessed part 2 Lining material 3 Excitation coil 4, 4a Magnetic pole 41, 41a Core 411 Core main-body part 412 Positioning protrusion part 42, 42a Base 421 Through-hole 43 Positioning member 44 Screw 45 Welding part 5 Magnetic path 6 Electrode
100 electromagnetic flow meter

Claims (2)

The flow velocity of the conductive fluid flowing in the measuring tube is measured by electromagnetic induction electromotive force generated by a magnetic field generated in the measuring tube by a pair of magnetic poles arranged opposite to the outer wall of the measuring tube and wound with an excitation coil. An electromagnetic flowmeter, wherein the magnetic pole is stabilized by contacting the core body portion around which the exciting coil is wound and the projecting portion fitted into the through hole formed in the pedestal, and the wall of the measuring tube as the magnetic pole. And a pedestal having a through hole in which the magnetic field distribution is optimized and the protruding portion of the core is fitted, and a magnetic pole having an integral structure welded in a state where the protruding portion is fitted in the through hole. An electromagnetic flow meter characterized by that. The protruding length of the protruding portion of the core is larger than the plate thickness of the pedestal,
The electromagnetic flowmeter according to claim 1, wherein a concave portion for fitting a protruding portion protruding from the pedestal is formed at a magnetic pole arrangement position of the measuring tube.

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