JP3053989B2 - Electromagnetic flow meter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic flowmeter used in various fields, and more particularly to an electromagnetic flowmeter provided with a clam-shaped exciting coil.

[0002]

2. Description of the Related Art From the standpoint of easiness of installation in a field, saving of piping space, and the like, an electromagnetic flowmeter having a shorter surface (a shorter length between end surfaces) has conventionally been required. Shortening means that the exciting coil arranged inside the electromagnetic flowmeter is made more compact, but in order to realize this, the efficiency of the magnetic flux excited in the measuring tube by the coil is required. Need to be improved. Various methods have been proposed so far as means for improving the magnetic flux efficiency. However, the magnetic flux efficiency of the magnetic circuit which also serves as a means for locating and fixing the excitation coil has not been taken into account.

[0003]

SUMMARY OF THE INVENTION In view of the above circumstances in an electromagnetic flowmeter provided with a clad excitation coil, the present invention
It is an object of the present invention to provide an electromagnetic flow meter having a magnetic circuit that has means for positioning and fixing a cladding excitation coil and that improves the efficiency of magnetic flux in a measurement tube.

[0004]

The electromagnetic flow meter according to the present invention comprises:
A measuring tube, a pair of excitation coils which are curved along the outer circumferential surface of the measuring tube and are arranged symmetrically with respect to the tube axis, and contact the outer circumferential surface of the measuring tube inside each of the exciting coils in the circumferential direction. A pair of extending and extending over the tube longitudinal direction portion of the exciting coil with a protrusion having a shape along its surface, extending for approximately half a circumference in the circumferential direction of the measuring tube, and being fixed to the measuring tube at an inner portion of each of the exciting coils. A magnetic circuit comprising a magnetic band-shaped plate of the shape described above, wherein the convex portion has substantially the thickness of the cladding excitation coil at the outer edge of the tube longitudinal portion of the cladding excitation coil.
It is characterized in that it is bent by 1/2 from the upper surface of the clad excitation coil toward the outer peripheral surface of the tube, and again bent in a direction parallel to the outer peripheral surface of the tube.

[0005] Further, the magnetic band-shaped plate is formed in such a manner that a terminal portion facing the outer peripheral surface of the measuring tube near a pair of electrodes mounted on the measuring tube is formed in a shape in which the dimension in the longitudinal direction of the tube is enlarged. Is what you do.

[0006]

[0007]

In the electromagnetic flowmeter according to the present invention, since the convex portion of the magnetic band-shaped plate fits in the tube longitudinal direction portion of the exciting coil,
By fixing the magnetic strip to the measuring tube, the positioning and fixing of the exciting coil are performed simultaneously. In addition, the efficiency of the magnetic flux in the measuring tube is improved because the convex portion of the magnetic band-shaped plate is formed at the outer edge of the exciting coil at the outer edge of the tube in the longitudinal direction of the exciting coil so as to drop by approximately １ ／ of the coil thickness.
Furthermore, if the end portion of the magnetic band-shaped plate is formed to have a shape whose size is enlarged in the longitudinal direction of the tube, the magnetic flux near the electrode can be increased, and the magnetic flux efficiency in the measuring tube can be further improved.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in the drawings.

FIGS. 1A and 1B show an electromagnetic flow meter according to an embodiment of the present invention. FIG. 1A is a perspective view showing a clad excitation coil attached to a measuring tube and a magnetic strip before attachment, and FIG. 1B is a sectional view showing an assembled state.

As shown in FIGS. 1 (a) and 1 (b), the cladding-shaped exciting coil 1 is formed to be curved along the outer peripheral surface of the measuring tube 3, and a pair is arranged symmetrically with respect to the tube axis.

The magnetic band-shaped plate 2 extends in the circumferential direction inside the excitation coil 1 in contact with the outer peripheral surface of the measuring tube 3, and forms the tube longitudinal portion 1a of the excitation coil 1 along the surface thereof. Of the excitation coil 1, the entire length of which extends over substantially half the circumference in the circumferential direction of the measurement tube 3, and is fixed at an inner portion of each excitation coil 1 by the fastening means 4 previously attached to the measurement tube 3. And constitute a magnetic circuit.

The protruding portion 2a of the magnetic band-shaped plate 2 bends from the upper surface of the coil toward the outer peripheral surface of the tube by approximately 1/2 of the coil thickness at the outer edge 1b of the tube longitudinal portion 1a of the clam-shaped excitation coil 1. It is again formed in a shape bent in a direction parallel to the outer peripheral surface of the tube.

In the electromagnetic flowmeter according to one embodiment of the present invention constructed as described above, since the convex portion 2a of the magnetic strip 2 fits into the tube longitudinal portion 1a of the exciting coil 1, the magnetic strip is formed. By fixing 2 to the measuring tube 3 by the fastening means 4, the positioning and fixing of the exciting coil 1 can be performed simultaneously.

Further, the convex portion 2a of the magnetic band-shaped plate 2 bends from the upper surface of the coil toward the outer peripheral surface of the tube by approximately 1/2 of the coil thickness at the outer edge 1b of the longitudinal portion 1a of the exciting coil 1 in the longitudinal direction of the tube. By forming the shape bent in a direction parallel to the outer peripheral surface, the efficiency of the magnetic flux in the measuring tube 3 is improved.

Assuming that the relative value of the magnetic flux density at the center of the measuring tube 3 is 1 when the outer core 10 is disposed outside the cladding-shaped exciting coil 1 as shown in FIG. 3, as shown in FIG. In the case where the band 2 does not bend downward while straddling the coil 1, the relative value of the magnetic flux density is 1.27, and the coil outer edge 1b of the projection 2a of the magnetic band 2 as shown in FIG. In the case where the bending in the above is performed until the outer peripheral surface of the tube comes into contact, the relative value of the magnetic flux density is 1.48, and as shown in FIG. 6, the bending at the coil outer edge 1b of the convex portion 2a of the magnetic band-shaped plate 2 is reduced. 1 of coil thickness
A simulation result that the relative value of the magnetic flux density is 1.58 is obtained in the case where the shape is bent downward by / 2.
Downward bending at about 1/2 of the coil thickness
It has been concluded that the magnetic band-shaped plate 2 having the convex portion 2a having the following shape is most effective for improving the magnetic flux efficiency in the measuring tube 3.

Next, as a modified example of the present invention, FIG. 2 shows a case where the shape of the end portion of the magnetic strip is changed. As shown in FIG. 2, the magnetic strip 2 is formed with a terminal portion 2b facing the outer peripheral surface of the measuring tube near the pair of electrodes 5 attached to the measuring tube 3 in a shape in which the dimension in the tube longitudinal direction is enlarged. That
There is an effect of increasing the magnetic flux near the electrode 5, and the magnetic flux efficiency in the measuring tube 3 can be further improved.

[0017]

As described above in detail, according to the present invention, a pair of clad excitation coils arranged symmetrically with respect to the tube in the measuring tube respectively contact the outer peripheral surface of the measuring tube inside the coils. A pair of magnetic strips extending in the direction of the tube and extending over the tube longitudinal direction portion by a convex portion having a shape along the surface thereof, extending for substantially half a circumference of the measuring tube, and fixed to the measuring tube at an inner portion of the coil. To form a magnetic circuit, and the convex portion bends from the coil upper surface toward the outer peripheral surface of the coil by approximately の of the coil thickness at the outer edge of the coil in the longitudinal direction of the tube, and is again parallel to the outer peripheral surface of the tube. Since the electromagnetic flowmeter has a bent shape in various directions, the protrusion of the magnetic strip fits into the tube in the longitudinal direction of the exciting coil. The position of the excitation coil And it can be carried out fixing at the same time. Further, the magnetic flux efficiency in the measuring tube can be improved by forming the convex portion of the magnetic band-shaped plate at the outer edge of the coil in the longitudinal direction of the coil so as to be lowered by almost の of the coil thickness. Furthermore, if the end portion of the magnetic strip-shaped plate facing the outer peripheral surface of the measuring tube near the electrode is formed into a shape in which the dimension in the longitudinal direction of the tube is enlarged, there is an effect of increasing the magnetic flux near the electrode, and the magnetic flux efficiency in the measuring tube is reduced. Can be further improved.

[Brief description of the drawings]

FIGS. 1 (a) and 1 (b) show an electromagnetic flowmeter according to an embodiment of the present invention, and FIG. 1 (a) shows a magnet-shaped exciting coil attached to a measuring tube and a magnetic strip before attachment. FIG. 1B is a sectional view showing an assembled state.

FIG. 2 is a perspective view showing a main part of an electromagnetic flowmeter according to a modified example of the present invention, in which a terminal portion of a magnetic band-shaped plate is enlarged in a longitudinal direction of a pipe.

FIG. 3 is an explanatory diagram showing a case where an outer peripheral core is arranged outside a clad excitation coil.

FIG. 4 is an explanatory view showing a case where a magnetic band-shaped plate disposed outside a clam-shaped excitation coil does not bend downward while straddling the coil.

FIG. 5 is an explanatory view showing a case where a magnetic band-shaped plate disposed outside a clad excitation coil crosses over the coil and then bends downward until it comes into contact with the outer peripheral surface of the measurement tube.

FIG. 6 is an explanatory view showing a case where a magnetic band-shaped plate arranged outside a clad excitation coil straddles the coil and then bends downward by half the thickness of the coil.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Kura-shaped excitation coil 1a ... Tube longitudinal direction part of coil 1b ... Outer edge 2 ... Magnetic strip 2a ... Convex part 2b ... Terminal part 3 ... Measuring tube 4 ... Fastening means 5 ... Electrode

Claims (2)

(57) [Claims] 1. A measuring tube, a pair of excitation coils which are curved along the outer peripheral surface of the measuring tube and are arranged symmetrically with respect to the tube axis, and contact the outer peripheral surface of the measuring tube inside each of the exciting coils. And extending in the circumferential direction, and extending the tube longitudinal direction portion of the exciting coil by a convex portion having a shape along the surface thereof, extending substantially half a circumference in the circumferential direction of the measuring tube, and measuring the measuring tube at an inner portion of each of the exciting coils. A magnetic circuit consisting of a pair of magnetic strips fixed to the outer periphery of the tube-shaped exciting coil at the outer edge of the tube-shaped exciting coil at approximately half the thickness of the clad-shaped exciting coil. An electromagnetic flowmeter characterized in that it is bent from the upper surface of the cladding-shaped exciting coil toward the outer peripheral surface of the tube and then again in a direction parallel to the outer peripheral surface of the tube. 2. The method according to claim 1, wherein the magnetic band-shaped plate is formed such that a terminal portion facing the outer peripheral surface of the measurement tube near a pair of electrodes attached to the measurement tube has a shape in which the dimension in the tube longitudinal direction is enlarged. The electromagnetic flow meter according to claim 1, wherein