JPH0351707Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an electromagnetic flowmeter that electrically measures the flow rate of a fluid to be measured flowing within a measuring pipe.

[Prior art]

In general, an electromagnetic flowmeter converts the flow rate of a conductive fluid flowing in a measurement pipe into an electrical signal using Faraday's electromagnetic induction phenomenon to measure the flow rate, and has conventionally been configured as shown in Figure 1. There is. That is, the measuring tube designated by the reference numeral 1 has flanges 1a and 1b for connection piping at both ends, and a lining 2 made of an insulating material such as Teflon or neoprene is provided on the inner wall. A pair of excitation coils (not shown) are attached to the outside of the measurement tube 1 to face each other and to form a magnetic field perpendicular to the flow direction of the fluid to be measured inside the tube. Further, a pair of electrodes 3 and 4 are provided on the wall of the measuring tube 1 so as to face each other via a magnetic field at right angles to the flow direction of the fluid to be measured in the measuring tube 1 . These electrodes 3 and 4 have signal lead wires 6 and 7 for electrically connecting them to the terminals on the connection terminal board 5, respectively, extending about 1/4 of the way around the outside of the measuring tube 1 in the same direction. installed.

However, in the conventional electromagnetic flowmeter described above, the signal lead wires 6 and 7 are often attached to the magnetic field formed by the excitation coil at an angle when viewed from the side of the measuring tube 1. ,4
There is an inconvenience that a noise electromotive force is generated due to a 90° phase shift that is quadratically proportional to the area S formed by the line A connecting the signal leads 6 and 7, and is sent as noise to the transmitter side. be.

Therefore, in order to solve this problem, a groove (not shown) extending in the circumferential direction is provided on the outer peripheral surface of the measuring tube 1, and the signal lead wires 6 and 7 are inserted into the groove using tape or adhesive. Fixed electromagnetic flowmeters have been proposed.

However, in this case, there is a drawback that the installation work of the signal lead wires 6, 7 is complicated and the number of processing steps is increased.

[Summary of the idea]

The present invention was developed in view of these circumstances, and uses an extremely simple structure in which the signal lead wire of the electrode is formed from an elastic band-shaped metal plate, thereby minimizing the noise caused by a 90° phase shift. The purpose of the present invention is to provide an electromagnetic flowmeter that not only allows reliable operation but also facilitates the installation work of signal lead wires. Hereinafter, the configuration and the like will be explained in detail by referring to embodiments shown in the drawings.

〔Example〕

2 and 3 are a schematic perspective view and a sectional view showing an embodiment of the electromagnetic flowmeter according to the present invention, and FIG. 4 is a side view showing a signal lead wire used in the electromagnetic flowmeter. In these figures, 11 is a measurement tube through which the fluid to be measured flows, and a lining 12 made of an insulating material is provided on the inner wall.
A pair of excitation coils 13 are provided on the outside facing each other to form a magnetic field perpendicular to the flow direction of the fluid to be measured inside the tube. Further, a pair of electrodes 14 are provided on the wall of the measurement tube 11 so as to face each other via the magnetic field, and are configured to detect the electromotive force generated at each point of the fluid to be measured. Reference numeral 15 denotes a terminal board having terminals 16, which is fixed to the case 18 with mounting screws 17, and is configured to send the value of the electromotive force detected by the electrode 14 to a control section (not shown). 19 is a signal lead wire of the electrode, for example, a phosphor bronze plate,
Pressing or etching an elastic metal plate such as SUS304 with a thickness of about 0.1 to 0.2 mm to create a width of 2 mm.
It is formed into a band shape of about 5 mm, extends in the outer circumferential direction of the measuring tube 11 and is attached to the measuring tube 11, and both ends are connected to the electrode 14 and the terminal 16, respectively. This signal lead wire 19 is covered with a heat-shrinkable tube or vinyl tube 20 as shown by the chain line in the figure for electrical insulation. In addition, the signal lead wire 19 has a long hole 21 bored at one end on the electrode side as a mounting hole, which makes it possible to adjust the length in the circumferential direction and absorb dimensional tolerances and variations during assembly. I can do it.

In the electromagnetic flowmeter configured in this way,
Since a band-shaped metal plate is used as the signal lead wire 19, there is no bending in the width direction of the metal plate, and the signal lead wire 19 is connected to the measuring tube 1 as shown by the chain line in FIG.
1 will not be installed misaligned in the axial direction.
In other words, the signal lead wire 19 is not attached obliquely to the magnetic field formed by the excitation coil 13 when viewed from the side of the measurement tube 11.

Further, since the signal lead wire 19 is formed of an elastic metal plate, the signal lead wire 19 can be reliably attached to the measurement tube 11 by utilizing its elasticity.

Furthermore, since the signal lead wire 19 is a thin metal plate of 0.1 to 0.2 mm, the excitation coil 13 and core (not shown) can be installed close to the measurement tube 11, improving its efficiency. can.

Note that when attaching the signal lead wire 19 of the electromagnetic flowmeter according to the present invention, the external terminal block 22 and the relay terminal block 23 may be used as shown in FIGS. 6 and 7, and the signal lead wire 19 is One end is attached to the terminals of the external terminal block 22 and relay terminal block 23 by soldering or screws, and the other end is attached to the electrode 14 by screws. In the former case, the signal lead wire 19 is connected to the measuring tube 11 compared to the latter case.
However, if the signal lead wire 19 is formed in a shape with a curvature slightly smaller than the curvature of the outer circumferential surface of the measuring tube 11, the signal lead wire 19 can be separated from the outer circumferential surface of the measuring tube 11. Can be mounted closely to the surface. In this case, if a circumferentially extending groove 24 is provided on the outer peripheral surface of the measuring tube 11 as shown in FIG. 8, the signal lead wire 19 can be attached more easily. However, the depth of this groove 24 may be small because the thickness of the signal lead wire 19 is thin, and therefore there is no need to make the measurement tube 11 particularly thick.

[Effect of idea]

As explained above, according to the present invention, since the signal lead wire is formed of a band-shaped metal plate, the signal lead wire can be reliably positioned in a position parallel to the magnetic field formed by the excitation coil when viewed from the side of the measurement tube. This makes it possible to reliably reduce noise due to a 90° phase shift as much as possible. Further, since the signal lead wire can be attached by utilizing its elasticity, there is no need to use tape adhesive as in the conventional case, and the attachment work can be performed extremely easily. moreover,
Since there is no need to provide a groove on the outer peripheral surface of the measuring tube, there is also the effect that the number of processing steps can be reduced.

[Brief explanation of drawings]

Figure 1 is a schematic perspective view showing a conventional electromagnetic flowmeter.
2 and 3 are a schematic perspective view and a sectional view showing an embodiment of an electromagnetic flowmeter according to the present invention, FIG. 4 is a side view showing a signal lead wire used in the electromagnetic flowmeter, and FIG. The figure is a side view showing how the signal lead wire is attached to the electrode, and FIGS. 6, 7, and 8 are sectional views showing how the signal lead wire is attached. 11...Measuring tube, 13...Exciting coil, 14...
...Electrode, 19...Signal lead wire.

Claims (1)

[Scope of utility model registration request] A pair of excitation coils are provided outside the measurement tube and form a magnetic field perpendicular to the flow direction of the fluid to be measured in the tube, and a pair of electrodes are provided on the tube wall so as to face each other across the magnetic field. An electromagnetic flowmeter characterized in that the signal lead wire of the electrode is formed of an elastic band-shaped metal plate, and the metal plate extends in the outer circumferential direction of the measurement tube.