JPH0428063Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an electromagnetic current meter probe for measuring the flow velocity of a conductive fluid, and can be used in liquid metal current meters, tidal flow current meters, and the like.

Prior Art To measure the velocity of a conductive fluid flow,
An electromagnetic current meter is used.

Fig. 3 is an example showing the state of measurement of the flow velocity of a fluid in an open side, where reference numeral 1 indicates the open side, 2 indicates the fluid, 3 indicates the cladding tube of the electromagnetic current meter probe, 5a and 5b.
indicates an electromagnetic field that extracts the output signal of the probe. FIG. 4 shows the xx section of FIG. 3.
A permanent magnet 4 is incorporated inside the cladding tube 3 of the probe, and electrodes 5a and 5b are welded to the inner wall of the cladding tube 3.

The output of this electromagnetic current meter probe is expressed by the following equation, in which a voltage proportional to the velocity of the flow that cuts the magnetic field is induced between the electrodes 5a and 5b according to Fleming's right-hand rule.

E=K _v B where E is the output voltage, B is the magnetic flux density, v is the velocity of the flow, is the distance between the electrodes, and K is a coefficient determined by the shape of the probe, etc.

Problems to be Solved by the Invention FIG. 5 is an example showing the distribution of the velocity v of the flow within the aperture in the depth direction of the aperture 1. In this way, when there is a velocity difference in the depth direction, when measured with a probe of a certain size, it will show the average flow velocity in the depth region corresponding to the size of the probe, and the local This will not indicate the lower speed correctly. For this reason, it is necessary to make the diameter of the probe of the flowmeter as small as possible, but there are limitations such as the reduction in manufacturability due to miniaturization and the reduction in output due to the shortening of the distance between the electrodes.

The present invention has been made based on the above circumstances, and it is an object of the present invention to provide an electromagnetic current velocity probe that can more accurately measure local velocity even when there is a steep velocity gradient in the flow of liquid. With the goal.

Means for Solving the Problems According to the present invention, a flat tube, a plate-shaped permanent magnet inserted into the tube and having different polarities on the front and back sides, and a permanent magnet inside the tube are provided. Provided is an electromagnetic current meter probe characterized in that it has a pair of electrodes disposed opposite to each other on both sides and has a reduced thickness in the direction in which the flow velocity changes.

Embodiment FIG. 1 is an external view of a probe for an electromagnetic current meter according to the present invention, and FIG. 2 is an enlarged sectional view of a portion into which a tape-shaped magnet 4 having an N or S polarity on the upper or lower surface is inserted. The portion of the cladding tube 3 into which the magnet 4 is inserted is flat. Describing the manufacturing procedure,
First, the circular cladding tube 3 is bent into an L-shape, and then the electrodes 5a and 5b are welded into the circular tube. Next, press the part to be flattened to uniformly compress and deform it. A flat magnet 4 is inserted, the gap is filled with an electrical insulating material (for example, alumina), a cap is welded to the tip, and the whole is finished smoothly.

Operation When the electromagnetic current meter probe configured as described above is inserted into the flow of the fluid 2, an induced electromotive force corresponding to the flow velocity can be obtained at the electrodes 5a and 5b according to Faraday's law of electromagnetic induction. .

Effects of the invention According to the invention, by flattening the probe, the thickness of the probe in the direction in which a fluid flow velocity gradient is generated becomes thinner, making it possible to detect a more local flow velocity of the fluid. Ta.

Additionally, the distance between the electrodes was increased and the width of the magnetic flux was also increased due to the flat magnets, resulting in larger output and higher sensitivity.

[Brief explanation of the drawing]

Figure 1 is an external view showing the electromagnetic current meter probe according to the present invention in a measurement state, and Figure 2 is y-y of Figure 1.
FIG. 3 is a diagram showing a cross section, FIG. 3 is an outline diagram showing a conventional probe, FIG. 4 is a diagram showing a cross section taken along line xx in FIG. 3, and FIG. 5 is a diagram showing a velocity gradient of fluid flow. 1... Open, 2... Fluid, 3... Electromagnetic current meter probe cladding tube, 4... Magnet, 5a, 5b...
…electrode.

Claims (1)

[Scope of utility model registration request] It has a flat tube, a plate-shaped permanent magnet inserted into the tube and having different polarities on the front and back surfaces, and a pair of electrodes arranged inside the tube and facing each other on both sides of the permanent magnet. An electromagnetic current meter probe characterized by: