JP2004069304A - Capacity type electromagnetic flowmeter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a capacity type electromagnetic flowmeter that can reduce influence due to electromagnetic coupling noise in a high frequency that directly couples with an electrode. <P>SOLUTION: In the capacity type electromagnetic flowmeter having a guard case being provided while a detection electrode is covered, a magnetic coating film made of ferrite is provided in the detection electrode or on the surface of the guard case. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a capacitive electromagnetic flowmeter capable of reducing the influence of high-frequency electromagnetic coupling noise directly coupled to an electrode.
[0002]
[Prior art]
FIG. 3 is an explanatory view of a configuration of a conventional example generally used conventionally, FIG. 4 is a side view of FIG. 3, FIG. 5 is an explanatory view of parts of FIG. 3, FIG. 6 is a side view of FIG. 6 is a plan view of FIG.
[0003]
In the figure, reference numeral 1 denotes a measuring tube, in which case ceramics is used.
Reference numeral 2 denotes a detection electrode provided on the measurement tube 2 and reference numeral 3 denotes a signal line taken out from the detection electrode 2.
[0004]
Reference numeral 4 denotes an exciting coil, and reference numeral 5 denotes a pole piece core.
Reference numeral 6 denotes a housing, in which a potting body 7 is provided.
The potting body 7 is a resin-filled space between the measurement tube 1 and the housing 6, and is intended to fix the magnetic circuit / signal line 3.
[0005]
Reference numeral 8 denotes a guard case provided to cover the detection electrode 2 as shown in FIGS.
Reference numeral 9 denotes a gel resin, which is provided in the guard case 8.
In this case, a silicone resin 9 is used as the gel resin.
[0006]
11 is a feedback magnetic path. The feedback magnetic path 11 is generally made of an iron-based material such as a silicon steel plate.
Ferrite magnetic materials with good high-frequency characteristics are also conceivable, but are not used due to problems such as cracking and low saturation magnetic flux density.
[0007]
In the above configuration, the excitation coil 4 and the detection electrode 2 are attached to the measurement tube 1, and the guard case 8 and the housing 6 are attached.
Thereafter, a resin such as silicone is potted and cured inside the detector.
[0008]
The purpose of this potting is to fix the signal line 3 and the excitation coil 4 so that the influence of electromagnetic coupling noise and electrostatic coupling noise generated in the detector is constant, and the signal per unit point per unit flow rate is stabilized over time. It is to obtain an electromotive force.
[0009]
[Problems to be solved by the invention]
However, such an apparatus has the following problems.
Electrodes are shielded but not magnetically shielded.
The capacitance type electromagnetic flowmeter has an electrode capacitance of several tens of pF, an excitation frequency of several to several hundred Hz, a signal source impedance of as large as several tens MΩ or more, and is influenced by high frequency electrostatic coupling noise or electromagnetic coupling noise. Very susceptible.
[0010]
The effect of the electrostatic shield can be reduced by shielding with a metal (copper or aluminum) that is a conductive material.
However, there is a problem that it is very susceptible to high-frequency electromagnetic coupling noise generated by mobile phones and control devices.
[0011]
A magnetic shield in the return magnetic path is also conceivable, but iron-based materials such as silicon steel sheets are mainly used, and the frequency characteristics are not good.
Therefore, there is a problem that the device is very susceptible to high-frequency electromagnetic coupling noise.
[0012]
An object of the present invention is to solve the above-mentioned problem and to provide a capacitive electromagnetic flowmeter capable of reducing the influence of high-frequency electromagnetic coupling noise directly coupled to an electrode.
That is, by providing a detection material or an inner wall of a guard case that shields the electrode or a magnetic paint mixed with ferrite powder on a housing, a capacitive electromagnetic flowmeter that can reduce the influence of high-frequency electromagnetic coupling noise is provided. Is to do.
[0013]
[Means for Solving the Problems]
In order to achieve such an object, according to the present invention, in the capacitive electromagnetic flow meter of claim 1,
In a capacitive electromagnetic flowmeter having a guard case provided to cover the detection electrode,
A ferrite magnetic paint film is provided on the surface of the detection electrode or the guard case.
[0014]
In claim 2 of the present invention,
In a capacitive electromagnetic flow meter having a housing,
A ferrite magnetic paint film provided on a surface of the housing is provided.
[0015]
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 diagram of a main part configuration of an embodiment of the present invention.
In the figure, the configuration of the same symbol as FIG. 3 represents the same function.
Hereinafter, only differences from FIG. 3 will be described.
[0016]
Reference numeral 21 denotes a ferrite magnetic paint film provided on the surface of the detection electrode 2.
Reference numeral 31 denotes a ferrite magnetic paint film provided on the surface of the guard case 8.
[0017]
In the above configuration, the magnetic paint films 21 and 31 mixed with ferrite powder are applied to the surface of the detection electrode 2 or the surface of the guard case 8.
By mixing ferrite coating, but the saturation magnetic flux density becomes small, the magnetic field 200MH _Z or more electromagnetic noise generated from the mobile phone and the control device is generated is very small, the saturation magnetic flux from the surface of the magnetic shield Density does not matter.
[0018]
As a result, by performing magnetic shielding with a ferrite film having no conductivity, it is possible to obtain a capacitive electromagnetic flowmeter capable of reducing the influence of high-frequency electromagnetic coupling noise that is directly coupled to the electrode with respect to high-frequency electromagnetic coupling noise.
[0019]
According to the evaluation experiment, the noise reduction effect was confirmed by, for example, electromagnetic noise (EMS test) of 200 to 1000 MHz, and it was confirmed that the noise reduction effect was 30% to 50%.
[0020]
FIG. 2 is an explanatory diagram of a main part configuration of another embodiment of the present invention.
In this embodiment, reference numeral 41 denotes a ferrite magnetic paint film provided on the surface of the housing 6.
[0021]
As a result, a capacitive electromagnetic flowmeter that can reduce noise coupled to not only the electrodes but also signal lines and the like can be obtained.
[0022]
It should be noted that the foregoing description has shown only 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.
[0023]
【The invention's effect】
As described above, according to the first aspect of the present invention, the following effects can be obtained.
By performing magnetic shielding with a ferrite film having no conductivity, a capacitive electromagnetic flowmeter capable of reducing the influence of high-frequency electromagnetic coupling noise directly coupled to the electrode with respect to high-frequency electromagnetic coupling noise is obtained.
[0024]
According to the second aspect of the present invention, the following effects are obtained.
A capacitance type electromagnetic flow meter that can reduce noise coupled to not only electrodes but also signal lines and the like is obtained.
[0025]
Therefore, according to the present invention, it is possible to realize a capacitive electromagnetic flowmeter capable of reducing the influence of high-frequency electromagnetic coupling noise directly coupled to an electrode.
[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 an explanatory view of a main part configuration of another embodiment of the present invention.
FIG. 3 is an explanatory diagram of a configuration of a main part of a conventional example generally used in the related art.
FIG. 4 is a side view of FIG. 3;
FIG. 5 is an explanatory view of the parts in FIG. 3;
FIG. 6 is a side view of FIG. 5;
FIG. 7 is a plan view of FIG. 3;
[Explanation of symbols]
REFERENCE SIGNS LIST 1 measuring tube 2 detection electrode 3 signal wire 4 excitation coil 5 pole piece core 6 housing 7 potting body 8 guard case 9 gel resin 11 return magnetic path 21 magnetic paint film 31 magnetic paint film 41 magnetic paint film FL

Claims (2)

In a capacitive electromagnetic flowmeter having a guard case provided to cover the detection electrode,
A capacitive electromagnetic flowmeter comprising a ferrite magnetic paint film provided on a surface of the detection electrode or the guard case. In a capacitive electromagnetic flow meter having a housing,
A capacitive electromagnetic flowmeter comprising a ferrite magnetic paint film provided on a surface of the housing.

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