JPS5833536Y2 - electromagnetic flow meter - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an electromagnetic flowmeter in which component parts such as an excitation coil can be easily attached.

One of the conventional electromagnetic flowmeters is that an outer casing that also serves as an iron core is placed over the outside of a conduit through which the fluid to be measured flows, and a coil storage recess is formed inside the outer casing, and an excitation coil is stored in this recess. The magnetic flux generated by the device and the outer casing constitute a magnetic flux generating device, and the magnetic flux obtained by this device is applied to the fluid inside the conduit, and the electromotive force induced thereby is extracted as a flow rate signal by a pair of electrodes provided in the conduit. There is.

By the way, in an electromagnetic flowmeter with the above structure, the conduit and the outer casing are sufficiently spaced apart, which increases the overall size of the flowmeter, and the excitation coil is mounted in the coil storage recess inside the outer casing. This makes the assembly work complicated, and the excitation coil tends to move relatively easily after being installed in the storage section, so it is necessary to take measures to restrict the movement of the excitation coil.

This invention was developed in view of the above circumstances, and it facilitates the installation, maintenance and inspection of excitation coils and electrodes, etc.
Moreover, the present invention provides an electromagnetic flowmeter that can be made smaller overall and that can easily achieve dimensional accuracy during assembly.

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 10 is a non-magnetic metal pipe, and a magnetic outer casing 11 which also serves as an iron core is provided on the outer periphery of the pipe.

The outer casing 11 is in close contact with the metal pipe 10 except for the housing portion 11a of the excitation coil 12, and the outer casing 11 is provided at both ends, for example.
7 langes Ilb and 11b made of the same material are integrally attached.

Moreover, the excitation coil housing portion 11 is formed by the outer casing 11 itself.
In a, an opening 11c is provided on the upper side of the storage portion 11a so that the excitation coil 12 can be attached from the outside of the outer casing 11, and a magnetic lid 11a serving as a return magnetic path for the magnetic flux is closed in the opening 11c. It has become.

This magnetic lid 11a has a recess formed in its center, and the side walls of this recess and the magnetic outer casing 11 provide a space for accommodating the excitation coil 12.

When installing the excitation coil 12, after fitting the excitation coil 12 to the outer periphery of the four parts of the magnetic lid 11a, the magnetic lid 11a is closed in the excitation coil storage portion 11a of the outer casing 11, and the flowmeter body is closed. This completes the attachment of the excitation coil 12 to the excitation coil 12.

Note that, when the lid body 11d is closed, an O-ring gasket 13 is interposed between the excitation coil housing portion 11a and the excitation coil storage portion 11a to maintain airtightness.

On the other hand, a lining 14 is applied to the inside of the metal pipe 10 using an electrical insulator, and the metal pipe 10 and the lining 1
A pair of electrodes 15 and 15 are disposed opposite each other so as to be inserted through the lining 14 and expose the electrode heads inside the lining 14.

Thereby, the induced electromotive force obtained when the magnetic flux generated by the excitation coil 12 acts perpendicularly on the fluid to be measured can be extracted as a flow rate signal of the fluid to be measured by the pair of electrodes 15, 15.

Furthermore, openings 11e are provided on both sides of the outer casing 11, that is, on the sides of the outer casing 11 located on the axes of the pair of electrodes.

11e is provided to make it convenient for the device of the electrodes 15, 15, maintenance and inspection, etc.

This opening 11e. 11e is closed by an electrode portion lid 11f.

In this case as well, the O-ring packing 16 maintains airtightness.

Note that after the lids 11d and 11f are closed, they may be welded or screwed to the outer casing 11.

Furthermore, the lid body may be provided with introduction and extraction holes for an excitation power supply line and a signal output line.

Further, the excitation coil 12 may be directly stored in the storage part 11a, or it can be fixed to the lid 11d and stored in the storage part 11c when the lid 11d is closed.

Next, FIG. 2 shows another embodiment of the electromagnetic flowmeter of the present invention, which shows that when the outer casing 11 is made of sheet metal, the outer casing body and the flange 11b can be welded to the metal pipe 10. good.

Further, as shown in FIG. 3, when the outer casing 11 is made of cast metal, it is convenient to cast the metal pipe 10 in advance so as to bite into the outer casing 11 side.

That is, it is sufficient to make the flange 11b protrude in advance by a distance t from the surface thereof to the inner side of the outer casing when casting.

Although the excitation coil 12 is not present in the substantially central portion of the lid 11d, forming a space 1γ, it is convenient to accommodate the terminal box in this portion 17.

Furthermore, it is also possible to use a rectangular wave, a trapezoidal wave, etc. as the excitation signal.

As detailed above, according to the present invention, since the outer casing is provided closely around the outer periphery of the metal pipe, the relative positional relationship is less likely to be distorted even during vibrations or plant piping, and the dimensional accuracy during installation is maintained. It's easy to get out.

Further, the structure allows the outer casing to be easily welded to the metal piezo, and therefore, the structure that does not cause any deviation in positional relationship as described above contributes to improving electrical accuracy.

After manufacturing the electromagnetic flowmeter main body, the excitation coil 12 is fitted into the outer periphery of the recess of the magnetic lid 11d, and the magnetic lid 11d is closed in the magnetic outer casing 11 to complete the installation of the excitation coil 12, making assembly easy. Moreover, maintenance inspection and replacement can be easily performed, the excitation coil 12 can be accurately positioned with respect to the metal pipe 10, the coil is difficult to move after being attached, and it has excellent electrical characteristics.

Furthermore, the airtightness between the outer casing and the lid body can be achieved by using a simple O-ring seal, which can increase the reliability of the airtightness by half.

In addition, since the conventional excitation method uses a sine wave for excitation, it is necessary to place the highest importance on the symmetry of this structure, but when using an excitation method such as a rectangular wave or trapezoidal wave, even if the structure is somewhat asymmetric, noise components Since the excitation coil will not appear, the excitation coil should be
There is no need to provide a pair (but the structure can be further simplified by providing one on either side).

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the structure of the electromagnetic flowmeter of the present invention,
Figure A is a partially sectional front view, Figure B is a partially sectional side view, and Figures 2 and 3 are partially modified sectional views of the electromagnetic flowmeter of the present invention. 10...Metal pipe, 11...Outer casing, lla...
Coil storage section, 11c...opening, 11d...lid, 11f...electrode portion lid, 12...excitation coil, 1
3...O-ring packing, 15...electrode.

Claims (2)

[Scope of utility model registration request] (1) A non-magnetic metal tube in which a pair of electrodes are installed facing each other and through which a fluid to be measured flows; A magnetic outer casing body has a coil accommodating opening in a direction perpendicular to the line connecting the electrodes, and the magnetic outer casing body forms a space for a coil accommodating part, and a recessed part in the center that is in close contact with the metal tube body. a magnetic lid hermetically sealed to the magnetic outer casing body forming a return magnetic path for magnetic flux; An electromagnetic flowmeter characterized by comprising: and an excitation coil constituting a magnetic flux generator. (2) The electromagnetic flowmeter according to claim 1, wherein the magnetic outer casing body and the magnetic lid are airtightly connected using an O-ring packing.