JPH01123113A - electromagnetic flow meter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electromagnetic flowmeter that electrically measures the flow M of a fluid to be measured flowing inside a measuring pipe.

[Conventional technology]

The 'iri magnetic flowmeter takes the fluid to be measured flowing in the measuring tube as a conductor, generates a voltage by applying a magnetic field to this flowing conductor, and detects this voltage with electrodes to measure temperature and temperature. , conventionally, for example, JP-A-56-1248
The device disclosed in Publication No. 23 is constructed as follows. That is, in the outer INJ recess of the ceramic measuring tube through which the fluid to be measured flows, a magnetic flux generating device consisting of an excitation coil or the like is housed with the direction of magnetic flux generation perpendicular to the axial direction of the electrode and the flow direction of the fluid. In addition, the grounding ring fixed to the open end faces of the measuring tube through gaskets keeps the inner hole in contact with the fluid, and the grounding ring and the flowmeter case are connected via embedded terminals. It is electrically connected by the lead wire. With this configuration, the excitation coil is excited,
When a conductive fluid flows in a measurement tube, an electromotive force proportional to the average flow rate is generated between the electrodes that are perpendicular to the magnetic field direction and the fluid flow direction, so this must be converted into an electrical signal and measured. The flow rate can be obtained by

In addition, because the fluid and the case are short-circuited via the ground ring, lead wire, and embedded terminal, the measured fluid and the entire instrument maintain the same reference potential, allowing the electrodes to extract the electromotive force with high precision. It will be done.

Furthermore, what is disclosed in Japanese Utility Model Application Publication No. 61-96320 is to bake a conductive material on both end faces of a ceramic measuring tube so that it comes in contact with the fluid, and to connect the conductive material and the case with a lead wire. This keeps the fluid and the entire instrument at the same potential.

[Problem that the invention seeks to solve]

However, in such conventional electromagnetic flowmeters, the earth ring, conductive material, and case are connected by soldering the lead wires, so vibrations in the piping may damage the connections between the lead wires and the case or embedded terminals. There was a problem that the wires could become loose or break, or the soldered parts could be damaged, resulting in a lack of axial stability.

[Means for solving problems]

In order to solve such problems, in the present invention,
Both metallized parts formed on both open end faces of the ceramic measuring tube by partially contacting the liquid are connected by a band-shaped metallized part formed in the direction of the outer periphery of the measuring tube in the direction of the ridgeline. The coil bobbin was screwed to the flowmeter case via the provided coil unit.

[For production]

The fluid to be measured and the entire flow meter are short-circuited by the metallized parts at both ends of the measuring tube, the band-shaped metallized part connecting these parts, and the coil bobbin, so that they maintain the same potential with each other.

〔Example〕

1 to 4 show an embodiment of the electromagnetic flowmeter according to the present invention, in which FIG. 1 is a longitudinal sectional view, FIG. 2 is a side sectional view, and FIG. 3 is a plan view of a measuring tube. Figure 4 is a side view of Figure 1, which shows the open end surfaces 1a on both sides that are joined to the pipes.
, lb is formed into a cylindrical shape from ceramic such as Alx(h), and a pair of rectangular electrode mounting surfaces facing each other are provided at positions dividing the outer circumferential surface into four equal parts in the circumferential direction. 1c and a pair of coil mounting recesses 1d facing each other are formed orthogonally to each other.

A pair of electrodes 2 are inserted and fixed into the electrode holes provided on the electrode mounting surfaces 1c on both sides, and the insertion ends are connected to the measurement tube l.
is in contact with a conductive fluid flowing through the inner hole of the Measuring tube l
is fitted and fixed at both ends of its outer periphery into a center hole 3a of a metal instrument case 3 supported on the process fixing part side, and an O-ring 4 as a sealing member is inserted into an O-ring groove on the fitting surface. The case 3, which is inserted in the inside of t r, has a pair of square cylindrical parts 3b corresponding to the concave surface 1d, and cylindrical parts 3c and 3d with flanges that follow the square cylindrical parts 3b. Cylinder part 3
In the inner hole b, there is a bobbin body 5 formed into a tubular shape with both flanges.
A coil unit 7 is housed, which is formed by a coil bobbin 5 consisting of a coil bobbin 5 and a disk 5b screwed onto the coil bobbin 5, and an excitation coil 6 wound around the coil bobbin 5. The coil unit 7 is fixed to the case 3 by screwing the coil bobbin 50 and disc 5b to the stepped portion of the case 3, and the measurement tube 1 is sandwiched between the upper and lower coil units 7 to be connected to the case 3 for measurement. The tube l is fixed. The lead wire 8 connected to the electrode 2 is led through the inner hole of the coil bobbin 5 to a terminal box or converter (not shown), and the lead wire 9 connected to the excitation coil 6 is led through the hole in the disc 5b. through which it is led to the power source.

On both open end surfaces 1a and lb of the measuring tube l, a metallized portion 10 consisting of an annular portion and a radius portion is formed by metallizing the ceramic surface, as shown in FIG. The metallized portion 10 is a similar band-shaped metallized portion 1 formed in the direction of the outer peripheral edge of the measuring tube l.
1 is connected. The material of the metallized part lo:tt is a metallized material for electrical parts such as Mo-Mn or W, which is coated with Nt plating or Au plating.If corrosion resistance is required, only the wetted part can be used. Pt metallization processing or Au metallization processing is performed.

By doing so, the fluid flowing through the inner hole of the measuring tube 1 and the case 3 are short-circuited by the metallized portions to, tt and the coil bobbin 5.

The operation of the electromagnetic flowmeter configured as above will be explained.

When the excitation coil 6 is excited and a conductive fluid flows in the measuring tube l, an electromotive force proportional to the average flow rate is generated between the electrodes 2 that are perpendicular to the magnetic field direction of the excitation coil 6 and the fluid flow direction. This is led to a terminal box or converter via lead wire 8, where it is converted into an electrical signal and the flow rate is measured.

In this case, the conductive fluid and the case 3 are connected to the metallized portion 10.
．． 11 and the coil bobbin 5, the entire flowmeter maintains the same reference potential as the fluid, and the electrode 2
The electromotive force is extracted with high precision.

Although this embodiment shows an example in which the band-shaped metallized portion 11 is provided on both sides of the circumferential surface of the measuring tube 1, it may be provided on only one side, and in this case, the radius portion of the metalized portion 10 may also be provided on only one side. , the metallized portion lO may be provided not only on a part of the end surfaces 1a and lb but also on the entire surface.If the metallized portion is also provided in the O-ring groove if, the band step will not be formed in the O-ring groove if. Good results are obtained for seals.

〔Effect of the invention〕

As is clear from the above explanation, in the electromagnetic flowmeter according to the present invention, both metallized portions formed on both open end faces of a ceramic measuring tube partially in contact with liquid are arranged in the direction of the outer peripheral ridgeline of the measuring tube. The coil bobbin is connected to the flow meter case via the formed band-shaped metallized part and screwed to the flow meter case via the coil unit disposed in contact with this band-shaped metallized part, so that the fluid to be measured and the entire flow meter are connected to each other at both ends of the measuring tube. Electrical conduction is established between the metallized portion, the band-shaped metallized portion that connects the metalized portion, and the coil bobbin, so there is no risk of disconnection as in the case of conduction caused by a lead wire, and stable conduction is obtained and reliability is improved.

In addition, the number of parts and assembly man-hours are small (it can be provided at low cost, and the measurement tube can be easily replaced, improving work efficiency).

[Brief explanation of the drawing]

1 to 4 show an embodiment of the electromagnetic flowmeter according to the present invention, in which FIG. 1 is a longitudinal sectional view, FIG. 2 is a side sectional view, and FIG. 3 is a plan view of a measuring tube. Figure 4 is also a side view. 1...Measuring tube, 1a, 1b...Opening end surface, 1d
... Recessed part for installing coil, 3 ... Instrument case,
4...0 ring, 5...coil bobbin, 6...
... Excitation coil, 7... Coil unit, 10.1
1...Metalization part. Patent applicant Yamatake Honeywell Co., Ltd. Agent
Masaki Yamakawa (and 2 others)

Claims (1)

[Claims] Metalized parts, some of which are in contact with the liquid, are formed on both open end surfaces of the ceramic measuring tube, and these two metalized parts are connected by a band-shaped metalized part formed in the direction of the outer periphery of the measuring tube. An electromagnetic flowmeter characterized in that a coil bobbin is screwed to a flowmeter case via a coil unit disposed in contact with the flowmeter.