JP3139057B2 - Electromagnetic flow meter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to relates to an electromagnetic flow meter, about to <br/> the good electromagnetic flowmeter allowed to particularly improve the magnetic flux density efficiency.

[0002]

2. Description of the Related Art The structure of a conventional electromagnetic flowmeter is shown in FIGS. A plurality of ring-shaped floor plates 6 are welded to the inner surface of the pipe 1 at intervals in the pipe axis direction. The tubular plate 2 having a large number of holes is inserted into the inside of the ring-shaped base plate 6 and welded to the ring-shaped base plate 6. Then mall sul by injection molding plates 2 with the insulating resin 3. The insulating resin 3 enters many holes of the plate 2, penetrates to the inner wall surface of the pipe 1, and covers the plate 2 so as to wrap the plate 2. As a result, even when the inside of the measurement tube becomes negative pressure or becomes high temperature, the insulating resin 3 is reinforced by the plate 2 and therefore does not peel or deform.

[0003] Therefore, the inner diameter of the tube of the insulating resin 3 is always kept constant, and the flow rate can be measured with high accuracy.

On the other hand, on the outside of the pipe 1, a coil 5 and a core 4 are vertically attached to the center of the pipe 1 which is located perpendicular to the pipe axis direction. Pole tip 4a of the core 4, in order to increase the magnetic flux density efficiency, brought into close contact with the outer peripheral surface of the pipe 1 as possible, have a structure to bring the inter-pole distance L ₂ above and below the core 4.

[0005]

THE INVENTION Problems to be Solved] Contact <br/> Itewa the conventional electromagnetic flowmeter, the plate 2 of the tubular with a plurality of holes is essential in improving the stability of the insulating resin 3, Further, a ring-shaped floor plate 6 was required to provide this. Therefore, in the above structure, the tubular plate 2 and the ring-shaped
The outer diameter of the pipe 1 has been increased by the thickness of the pipe 1. This is because the inner diameter and wall thickness of the insulating resin 3 and the thickness of the pipe 1 are inevitably determined from their strength, performance, diameter of the pipe to be connected, measurement conditions, and the like. This is because it is not possible to reduce the inner diameter of the insulating resin 3 or to reduce the thickness of the insulating resin 3 and the pipe 1.

For this reason, as the outer diameter of the pipe 1 increases, the distance L between the magnetic poles of the core 4 in close contact with the outer peripheral surface of the pipe 1 increases.
₂ was far away, and the magnetic flux density had dropped. Because the magnetic flux density is inversely proportional to the magnetic pole distance L ₂ ,
The increase in the outer diameter of the pipe 1 due to the plate 2 and the ring-shaped floor plate 6 lowers the magnetic flux density and reduces the S
This is because the / N ratio decreases. In order to increase the magnetic flux density, the number of turns of the coil 5 may be increased, or the current supplied to the coil 5 may be increased. However, increasing the number of turns is contrary to the downsizing of the detector body,
Increasing the current has the problem of going against lower power consumption.

An object of the present invention, the ratio <br/> the conventional electromagnetic flow meter base, be provided with a plate 2 of a tubular having a plurality of holes, not away the inter-pole distance L ₂ of the core 4, the magnetic flux density An object of the present invention is to provide a structure of a measuring tube that does not lower the efficiency.

[0008]

In order to achieve the above object, a projection for holding the plate is formed on the inner surface of the pipe, and the formed portion improves the strength of the pipe. The thickness of the other pipes is reduced to reduce the outer diameter.

[0009]

The plate embedded in the insulating resin is held by a projection on the inner surface of the pipe, and the projection increases the strength of the pipe, thereby reducing the thickness of the pipe other than that part. Pipe external dimensions can be reduced.

As a result, the distance between the magnetic poles of the upper and lower cores attached to the pipe becomes shorter, and the magnetic flux density efficiency can be increased.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. A plurality of protrusions 1a are provided on the inner surface of the pipe 1 in a strip shape in the circumferential direction of the pipe 1 and at intervals in the axial direction of the pipe 1. A tubular plate 2 having a large number of holes is inserted into the pipe 1, and a portion in contact with the projection 1 a is welded to fix the plate 2. Next, the plate 2 is molded from the insulating resin 3 by injection molding. The insulating resin 3
The plate 2 is inserted into the pipe 1 from many holes to the inner wall surface of the pipe 1 and wraps the plate 2.

The measuring pipe must withstand several tens kgf / cm ² of the pressure of the fluid flowing through the pipe. The pipe 1 holds this pressure, and the pressure is maintained by the strength of the pipe 1.
Normally, a straight iron pipe is used for the pipe 1. However, since the strength of the pipe 1 is reinforced by providing the projection 1a, a structure capable of withstanding a higher pressure as compared with the case without the projection 1a is obtained. Therefore, the size of the wall thickness t ₁ of the pipe 1 can be reduced by the amount by which the strength of the pipe 1 is reinforced by the projections.

For this reason, the outer diameter of the pipe 1 is reduced, and the distance L ₁ between the upper and lower ends of the core 4 attached to the outside of the pipe 1 is reduced.

Also, by reducing the thickness of the pipe, the eddy current flowing through the pipe 1 is reduced, and the eddy current loss is also reduced.

As described above, according to one embodiment of the present invention, even when the plate 2 for preventing the deformation of the insulating resin 3 is provided,
The distance between the magnetic poles can be reduced, and the magnetic flux density efficiency does not decrease. Further, since the wall thickness of the pipe is reduced, there is also an effect of reducing eddy current loss.

Another embodiment of the present invention will be described. FIG. 5 shows a case where a plurality of projections 1a on the inner surface of a pipe 1 are provided in a strip shape in the pipe axial direction and spaced apart in the circumferential direction. When the tightening force in the pipe 1 pipe axial direction is large, FIG.
A plurality of protruding portions 1a are provided in a strip shape in both the pipe 1 pipe axial direction and the pipe 1 circumferential direction. When both the internal pressure of the pipe 1 and the tightening force in the pipe 1 pipe axial direction are large, FIG. 7
Is provided with a plurality of projections 1a spirally and in a belt shape, and is effective when the pressure inside the pipe 1 is large, and has the same effect as the above-described embodiment of the present invention.

[0017]

According to the present invention, even in a measuring tube in which a tubular plate having a large number of holes is embedded in an insulating resin, the pipe wall thickness can be reduced, so that the distance between the magnetic poles of the measuring coil can be reduced. Has the effect of not lowering the magnetic flux density efficiency. Further, the eddy current flowing in the pipe is reduced, and there is also an effect of reducing the eddy current loss.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a detector structure for explaining an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line II of FIG. 1;

FIG. 3 is a longitudinal sectional view of a conventional detector structure.

FIG. 4 is a sectional view taken along the line II-II in FIG. 3;

FIG. 5 shows another embodiment of the present invention in which the projection is provided in the pipe axis direction of the pipe.

FIG. 6 shows another embodiment of the present invention in which protrusions are provided in the pipe axis direction and the circumferential direction of the pipe.

FIG. 7 shows another embodiment of the present invention in which the projections are spirally provided along the pipe axis direction of the pipe.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Pipe, 2 ... Tubular plate which has many holes, 3
... Insulating resin, 4 ... Core, 5 ... Coil, 6 ... Ring-shaped floor plate, 1a ... Protrusion, 4a ... Magnetic pole tip.

Claims (5)

(57) [Claims] A pair of cores and coils are provided on an outer peripheral surface of a pipe.
For example, and place the cylindrical plate having a large number of holes in the pipe inner peripheral surface side, the electromagnetic flow meter by molding the plate with an insulating resin, said pipe so as to have a protrusion on an inner peripheral surface Formed ,
The electromagnetic flowmeter, wherein the plate is joined to the protrusion. 2. The electromagnetic flowmeter according to claim 1, wherein the protrusion is provided in a belt shape in a circumferential direction of the pipe. 3. The electromagnetic flowmeter according to claim 1, wherein the protrusion is provided in a strip shape in a pipe axis direction of the pipe. 4. The electromagnetic flowmeter according to claim 1, wherein said projections are provided in a strip shape in both the circumferential direction of the pipe and the axial direction of the pipe. 5. The electromagnetic flow meter according to claim 1, wherein the protrusion is provided in a spiral shape.