JPS6014175Y2 - electromagnetic flow meter - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an electromagnetic flowmeter, and in particular allows a small-diameter electromagnetic flowmeter to be easily miniaturized.

There is one that uses a C-shaped magnetic core as one of the excitation devices of an electromagnetic flowmeter.

This excitation device using a C-shaped magnetic core is superior in that it can be easily assembled because it can be attached to and detached from one side of the conduit, and that it can be made small and lightweight.

However, the excitation device using this C-shaped magnetic core has the drawback that the magnetic field is disturbed because the yoke that magnetically connects the magnetic poles is present on only one side.

This invention aims to eliminate this deficiency and provide an electromagnetic flowmeter using a C-shaped magnetic core with small measurement errors.

A conventional small-diameter electromagnetic flowmeter is configured as shown in FIG. 1, for example.

In FIG. 1, 1 is a conduit through which a fluid to be measured flows.

Electrodes 2-2 are attached to the conduit 1 at positions 180° apart from each other across the tube axis.

C-shaped magnetic core 3 in the direction perpendicular to the line connecting the electrodes 2-2.
magnetic pole surfaces 3a and 3b are provided, and an excitation coil 4-4 is wound around the conduit 1 to form a magnetic field in a direction perpendicular to the line connecting the electrodes 2-2.

In order to reduce the overall size of an electromagnetic flowmeter having this structure, it is conceivable to make the C-shaped core 2 so that the back surface 3c of the C-shaped core 3 is closer to the conduit 1.

However, when the back surface 3c of the C-shaped core 3 is brought closer to the conduit 1, the magnetic field that is supposed to be formed between the magnetic pole surfaces 3a and 3b as shown in FIG. 3c
It is also formed between the magnetic pole face 3b and the magnetic pole face 3b.

As a result, the magnetic field distribution inside the conduit 1 is
The side near c is disturbed.

This disturbance in the magnetic field distribution is greatest at the position of the electrode 2, and causes measurement errors for flows with a non-axially symmetric flow velocity distribution.

For this reason, conventionally, the back surface 3c of the C-shaped core 3 is kept sufficiently away from the conduit 1 so as not to disturb the magnetic field formed between the magnetic pole faces 3a and 3b.

Therefore, the overall shape is large.

The purpose of this invention is to provide a small-diameter electromagnetic flowmeter that is compact but highly accurate by bringing the back surface 3C of the C-shaped core 3 closer to the conduit 1 to achieve miniaturization and to reduce disturbances in the magnetic field distribution.

In this device, the magnetic pole surface of the magnetic core is formed asymmetrically with respect to a plane that includes the tube axis of the conduit 1 and is perpendicular to the line connecting the electrodes 2-2, and the asymmetry of the magnetic pole surface equalizes the magnetic field distribution within the conduit. It is configured as follows.

An embodiment of this invention will be described below in detail with reference to the drawings.

FIG. 3 shows an embodiment of this invention.

In the embodiment shown in FIG. 3, the magnetic pole surface 3a of the C-shaped magnetic core 3 is
.

A protrusion 5-5 made of a magnetic material having a trapezoidal cross-sectional shape is attached to the side near the back surface 3c of 3b, and by attaching the protrusion 5-5 made of the magnetic material, the magnetic pole faces 3a and 3b are It is asymmetrical with respect to a plane that includes the tube axis of the conduit 1 and is perpendicular to the plane that connects the electrodes 2-2.

Due to the asymmetry of this magnetic pole surface, the magnetic pole surface 3at3b and the back surface 3
The magnetic field formed by C was sufficiently reduced, and the magnetic field distribution as shown in FIG. 3 was achieved.

To show the actual dimensions of each part at this time, the inner diameter of conduit 1 =
10orIrI4, gap between magnetic pole faces 3a and 3b: 125
Cabinet, width W of magnetic pole surface: 95mm, depth of magnetic pole surface: 9
5mm.

Distance L1 from one end of the magnetic pole to the back part 3c: 313m
5° Distance L2 from the bent part of the C-shaped core to the pipe axis of the conduit 1: 100 mm.For the C-shaped core 3 having such dimensions, the dimensions of the magnetic protrusion 5-5 are as shown in FIG. Bottom surface L3: 187701. Height L4: 9 mm, length of upper side 'L5: 3 WAz overall length 95rIrI14.

The protrusion 5-5 that prevents the magnetic material as described above is attached to the magnetic pole surface 3a,
3b, the magnetic field distribution within the conduit 1 was made uniform and the accuracy of flow measurement could be improved.

In addition, the protrusions 5 that should be avoided from the magnetic material attached to the magnetic pole surfaces 3a and 3b
-5 can have various shapes as shown in FIGS. 5 to 11.

In addition, by adding the protrusions 5-5 cut out from the magnetic material in this way, not only the magnetic pole faces 3a and 3b are made asymmetrical, but also the pole faces 3a and 3b are furthest away from the back surface 3C of the magnetic pole faces 3a and 3b, as shown in FIG. A notch 6-6 may be formed on the side at the position where the cutout 6-6 is located.

As described above, according to this invention, even if the back surface 3c of the C-shaped core 3 is brought closer to the conduit 1, the magnetic field distribution within the conduit 1 can be made uniform with a simple configuration.

Therefore, it is possible to obtain a small-diameter electromagnetic flowmeter that is compact but has high measurement accuracy, and its effects are extremely large in practical use.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view to explain a conventional electromagnetic flowmeter, Fig. 2 is a cross-sectional view to explain the disadvantages of the conventional electromagnetic flowmeter, and Fig. 3 is a cross-sectional view showing an embodiment of this invention. , FIG. 4 is a side view illustrating one example of the actual dimensions of the main part of this invention, FIGS. 5 to 11 are side views showing other examples of the main part, and FIG. FIG. 1... Conduit, 2... Electrode, 3...
...C-shaped magnetic core, 3ay3b...magnetic pole surface,
3c... Back part, 4... Excitation coil.

Claims (1)

[Scope of utility model registration request] In an electromagnetic flowmeter in which magnetic pole surfaces are arranged at both ends of a C-shaped magnetic core having a back surface so as to sandwich a conduit, and an excitation coil is applied to the magnetic core, a C-shaped magnetic core including a tube axis of the conduit and perpendicular to both magnetic pole surfaces is provided. Either a protrusion of a magnetic material is formed on the magnetic pole face on the back side with respect to the cross section in the tube axis direction, or a notch is formed on the magnetic pole face opposite to the back side. , an electromagnetic flowmeter configured to equalize magnetic field distribution within the conduit.