JPH02268232A - Detector of electromagnetic flowmeter - Google Patents

Abstract

PURPOSE:To decrease the amount of strain due to the fluid pressure in a measuring pipe and to make the thickness of the pipe thin by arranging a pair of supports wherein exciting coils are wound around magnetic poles having flanges at the center of a saddle shaped body so as to hold the measuring pipe, and tightening the supports with bands. CONSTITUTION:When fluid pressure is applied on a measuring pipe 11 made of ceramics, the maximum strain is generated at the central part in the longitudinal direction. Exciting coils 13 and 13' are wound around magnetic poles 12b. A pair of supports 12 and 12' have magnetic poles 12b having flanges 12c and said exciting coils 13 and 13'. The supports 12 and 12' are arranged so as to hold the measuring pipe 11 in a symmetrical pattern with respect to the axis of the pipe. The supports 12 and 12' are tightened with a pair of bands 15 and 15' made of magnetic bodies. A force which is reverse to the fluid pressure is applied on the measuring pipe 11 through a pair of the supports 12 and 12'. Initial strain which is opposite to the strain caused by the fluid pressure is generated. Therefore, the amount of the strain when the fluid pressure is applied can be made small. Thus, the thickness of the measuring pipe 11 made of ceramics can be made thin in comparison with the thickness when the single body of the ceramics pipe is used.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an electromagnetic flowmeter detector equipped with a measuring tube made of ceramics.

(Prior art) As shown in Figure 4, the basic configuration of an electromagnetic flowmeter detector is as follows:
An excitation coil (1) that applies a magnetic field to the fluid, a measuring tube (2) through which the fluid flows, and an electrode (3) attached to the measuring tube (2) at a position perpendicular to the direction of fluid flow and the direction of the magnetic field, respectively. , (3°), and a magnetic path (4) for efficiently generating a magnetic field. The measuring tube (2) receives the pressure of the fluid and must be able to withstand it, so a non-magnetic stainless steel tube or the like is used, and the electromotive force induced by the fluid flow and magnetic field is transferred to the electrode (3). (3°), the inner surface of the measuring tube (2) in contact with the fluid is
It has usually been electrically insulated with rubber or the like.

Recently, ceramics, which are electrical insulators, have mechanical strength, and are non-magnetic, have come to be widely used for measurement tubes.

(Problem to be solved by the invention) Ceramics have low fracture toughness and are brittle compared to metals.

Therefore, when used in measurement tubes, it is necessary to make the amount of distortion considerably smaller than that of metals with respect to the pressure received from the fluid.

This means that if a fluid pressure measurement tube with the same rating is manufactured,
Ceramic tubes require a thicker tube than metal tubes. For this reason, the outer diameter of the measuring tube becomes thicker, leading to an increase in the size of the detector. Furthermore, as the measurement tube becomes thicker, the excitation coils are spaced further apart, so unless the current flowing through the excitation coils is increased, the magnetic field will become weaker. Therefore, to compensate for this, increase the current.

This will lead to higher power consumption.

Therefore, an object of the present invention is to realize an electromagnetic flowmeter detector that uses a measuring tube made of ceramics and does not become large in size, and that is also an object of the present invention.

[Structure of the Invention] (Means for Solving the Problems) The electromagnetic flowmeter detector of the present invention has a pair of supports made of ceramic, each having a flanged magnetic pole in the center of a saddle-shaped body and an excitation coil wound around the flanged magnetic pole. The measuring tube is arranged so as to sandwich the measuring tube symmetrically with respect to the tube axis at the center in the longitudinal direction of the manufactured measuring tube, and the pair of supports are tightened with bands at two centrally symmetrical points of the flanges in the tube axis direction. Ru.

(Function) In the electromagnetic flowmeter detector of the present invention, the ceramic measuring tube is tightened through the pair of supports, so that a force opposite to the pressure of the fluid is applied in advance. , the amount of distortion when fluid pressure is applied becomes smaller. Therefore, the thickness of the measuring tube can be made thinner than when a ceramic measuring tube is used alone.

(Example) Hereinafter, the present invention will be described in detail based on the example shown in the drawings.

FIGS. 1(a) and 1(b) show an electromagnetic flowmeter detector according to an embodiment of the present invention. A pair of supports (12) and (12') are arranged in the longitudinal center of the ceramic measuring tube (1), symmetrically with respect to the tube axis, sandwiching the measuring tube (1).Supports (12) , (Ho) has a shape in which a magnetic pole (12b) with a flange (12c) is protruded from the center of a saddle-shaped body (12a) along the outer surface of a measuring tube (11) made of ceramics. Each support (12
).

(12°) magnetic pole (12b) has an excitation coil (
13).

(13°) is wrapped. Excitation coil (13),
(13°) and the axis of the magnetic field generated from the measuring tube (13°)
1) The measurement tube (
A pair of electrodes (14) and (14') are attached to the tube wall of 11).

and the pair of supports (12), (12')
is the center-symmetrical 2 of the flange (12c) in the tube axis direction.
It is tightened by a pair of magnetic bands (15), (15°) placed so as to hold each other at each location.

These bands (, 15) and (15') also serve as magnetic paths. In addition, each support (12), (12°) is connected to the band (
15) , (15°) tightening force by 411j fixed pipe (
11) and also serves to protect the excitation coils (13) and (13°) from the tightening force.

In the electromagnetic flowmeter detector of the embodiment of the present invention configured as described above, the magnetic field perpendicular to the fluid flow direction generated from the excitation coils (13), (13') and the fluid flow The electromotive force induced in the electrode (14)
, (14°), and is converted into a flow rate signal by a converter (not shown) and output.

In addition, a ceramic measuring tube (1
In the case of the present invention, the band (15) generates the maximum strain in the central part of the band (1).

(15') tightens the pair of supports (15').
2), (12°)
1) Since a force opposite to the fluid pressure is applied to generate an initial strain that is opposite to the strain caused by the fluid pressure, the amount of strain when the fluid pressure is applied can be reduced.

Therefore, the thickness of the ceramic measurement tube (11) can be made thinner than when the ceramic tube is used alone.

This leads to the fact that the outer diameter of the ceramic measuring tube (11) does not become large, and also prevents the support (12) from becoming large.
) and (12°) also have a small increase in the space of the excitation coils (13) and (13°), so they do not become a factor in increasing the size of the detector. In addition, an excitation coil (13),
(13°) interval is a ceramic measuring tube (11)
Supported by the decrease in the outer diameter of (12), (12°)
Since the thickness of the saddle-like body (12a) is offset, it will not expand. Therefore, it is possible to avoid an increase in the excitation current and increase in power consumption.

Note that the present invention is not limited to the embodiments described above, and can be implemented with the following modifications.

[a] Supports (12) and (12') are shown in Figure 2 (a)
, (b), the magnetic pole (12b) may be made of a ferromagnetic material, and the portion surrounding it, the flange (12c) and the saddle (12a) may be made of a non-magnetic material, such as stainless steel. . With this configuration, it becomes possible to adjust the distribution of the magnetic field within the measurement tube to a desired one.

[b] In the modification shown in FIG. 3, a flange is attached to the support for connection with the piping. The pair of supports (22), (22°) have an inner diameter at both ends into which the ceramic measurement tube (11) fits, and an outer diameter of the saddle-shaped body (22) of the support (22), (22°). 22a) with a curvature equal to the curvature of the outer surface of the ring (
23) and (24) are combined and integrated. A female thread (25) is cut on the inner diameter surface of each ring (23), (24) by a required length from the free end.

On the other hand, the flange (2B) is provided with a male threaded portion (27) that is screwed into the female thread 25 through a stepped portion on the surface opposite to the joint surface with the mating flange.
) An O-ring groove is formed on the tip surface of the O-ring (28).
is installed.

After inserting the ceramic Mj constant tube (11) into the integrated support (22) (22°), the ring (
23).

(24) by screwing the flanges (26) into each, and attaching the O-ring (28) to the ceramic measuring tube (
11) Perform sealing between the ends and assemble. Thereafter, by tightening with a pair of bands (15) and (15'), the saddle-shaped body (22a) of the support is deformed and the ceramic measuring tube (11) can be tightened.

This flanged support (22), <22')
When used, no force from the fluid is applied to the envelope, increasing the degree of freedom in design, and mechanically eliminating the need for an envelope.

〔Effect of the invention〕

As detailed above, according to the present invention, in an electromagnetic flowmeter detector equipped with a measuring tube made of ceramics, a pair of flanged magnetic poles are provided at the center of the saddle-shaped body and an excitation coil is wound around the flanged magnetic poles. By arranging the supports at the longitudinal center of the ceramic measuring tube so as to sandwich the measuring tube symmetrically along the tube's axis, and tightening the pair of supports with bands at two centrally symmetrical points along the tube's axis. , a force opposite to the fluid pressure is applied to the ceramic measurement tube via a pair of supports, creating an initial strain opposite to the strain caused by the fluid pressure. The amount of distortion can be reduced.

Therefore, the thickness of the ceramic measurement tube can be made thinner than when the ceramic tube is used alone. This leads to the fact that the outer diameter of the ceramic measuring tube does not become large, and since the support also adds only a small amount to the space of the excitation coil, it does not become a factor in increasing the size of the detector. Also, the distance between the pair of excitation coils is
Since the thickness of the support saddle is offset by the reduction in the outer diameter of the ceramic measuring tube, it does not expand. Therefore, it is possible to avoid an increase in the excitation current and increase in power consumption.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) show an electromagnetic flowmeter detector according to an embodiment of the present invention, FIG. 1(a) is a front view, and FIG. 1(b) is a front view.
2(a) and 2(b) show modified examples of the support, FIG. 2(a) is a side view, FIG. 2(b) is a front view, and FIG. 3 is an electromagnetic structure of the present invention. FIG. 4 is a partially cutaway side view showing a modified example of the flowmeter detector, and FIG. 4 is a schematic diagram showing the basic configuration of the electromagnetic flowmeter detector. 11...Measuring tube made of ceramics 12.12°...Support 12a...Saddle-shaped body 12b
...Flanged magnetic pole 12c...Flange 13.
13-...Exciting coil 14.14'...Electrode 15,15°...
・Band agent and patent attorney Norio Ogo

Claims (1)

[Claims] A ceramic measuring tube and a pair of supports that have a flanged magnetic pole protruding from the center of a saddle-shaped body that is arranged symmetrically with the tube axis at the center of the measuring tube and in contact with the outer surface of the measuring tube. and an excitation coil wound around the flanged magnetic pole of this support, and an excitation coil mounted on the measurement tube located in a straight line perpendicular to both the axis of the magnetic field generated from this excitation coil and the tube axis of the measurement tube. a magnetic material which is arranged to hold at least one pair of electrodes and the pair of supports at two centrally symmetrical locations in the tube axis direction of the flange, and which tightens the ceramic measuring tube via the supports; An electromagnetic flowmeter detector comprising a pair of bands.