JPH0769342B2 - Current meter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a measurement fluid (hereinafter referred to as “fluid”) which is arranged in a pair of electrodes and passes through a magnetic gap formed by the electrodes. The present invention relates to a flow velocity meter using so-called electromagnetic induction, which is provided with a spherical electromagnetic sensor that detects the two components of the flow direction and the flow velocity of the fluid by synthesizing the induced voltage generated between the pair of electrodes in vector. ,
The present invention relates to a flow direction anemometer with improved linearity of a spherical electromagnetic sensor.

[Prior Art] Conventionally, as this kind of technology, a configuration diagram of a doorknob-type flow velocity meter using electromagnetic induction in Fig. 6 is known (for example, see Japanese Patent Publication No. 45-31827). Incidentally, FIG. 6 (A) is a front internal sectional view, and FIG. 6 (B) is a bottom view.

In FIGS. 6A and 6B, 1 is an electromagnet, which is composed of an annular magnetic pole 1a, an exciting coil 1b, a central magnetic pole 1c and the like. Reference numeral 2 is a housing made of an electromagnetic insulating material, and 3 is a fluid (flow is represented by F). Reference numeral 4 is an electrode in which a pair of measuring electrodes (hereinafter referred to as electrodes) 4a-4a 'and 4b-4b' are arranged in a magnetic gap between different poles of the electromagnet 1. 5 is an insulating material, 6 is an exciting coil
1b is a lead wire, 7 is a lead wire for the electrodes 4a and -4a ', 8 is a support rod, and 9 is a lead wire for the electrodes 4b-4b'. In such a configuration, when the fluid 3 passes through the magnetic gap formed by the electrode 4, the induced voltage generated between the pair of electrodes is combined in a vector manner, so that the flow direction (flow direction) of the fluid 3 is increased. ) F and flow velocity are detected. However, in this doorknob-type flow velocity meter, when the flow of the fluid 3 is an oblique flow as illustrated with respect to the sensor, an error occurs due to, for example, the electrode surface being shaded and the flow being disturbed depending on the inflow angle. There is a problem.

Therefore, as an improved electromagnetic sensor, a spherical shaped seventh
The structure of the spherical electrode sensor as shown in the figure has been used. FIG. 7 is a schematic external view of a spherical electromagnetic sensor in a conventional flow direction current meter.

In FIG. 7, (A) has a flange portion A attached to a fluid conduit (not shown) at the upper portion, and has an exciting coil 10b inside a casing 20 provided via a support rod 8. , Non-protruding electrodes 40a-40a ', 40b-40b' mounted on the housing 20
(However, the opposite side of each is omitted). FIG. 2B is a vertical cross section of FIG. 1A, and the broken lines in the drawing represent the lines of magnetic force.

[Problems to be Solved by the Invention] By the way, in the spherical electrode sensor having the non-projecting electrode in the conventional flow direction anemometer, the flow around the sphere is a laminar flow in the low flow velocity region because the sensor surface is smooth. The layers in
There is a point where the state of the flow becomes turbulent when it exceeds a certain flow velocity (assumed to be V _A ), and in the high flow velocity region, the layer in the turbulent flow is
There is a point where the state of the laminar flow transitions when the flow velocity becomes lower than a certain flow velocity (denoted as V _B ), at which time V _A ≠ V _B , and the measurement result is a discontinuous state. Therefore, there is a problem that the measurement range cannot be set large. This will be described with reference to FIGS. 8A, 8B and 9 for explaining the problems of the conventional technique. In the following, the fluid 3 will flow to the sensor in a flow direction of 45 ° (here, 0 ° is the upper direction shown in FIG. 8A, and 90 ° is the right lateral direction). And All of the following are shown in this case, but it goes without saying that the present invention is not limited to this.

In view of FIG. 8 (A) is when the fluid 3 has a low flow rate F _a, the fluid 3
Is a laminar flow, the figure (B) shows the high flow velocity of the fluid 3.
In the case of F _b , it represents the case where the fluid is turbulent.

FIG. 9 shows the angle (flow direction) between the fluid 3 and the electrode of the sensor when the velocity (m / s) is plotted on the horizontal axis and the electromotive force (μV) is plotted on the vertical axis. It is the relationship characteristic of the relationship between electromotive force and speed at 45 ° and 60 °. Here, when the place where the layer also changes is represented by α, when α _A is the laminar flow region when the fluid 3 has a low flow velocity F _a , and α _B is the turbulent flow region when the fluid 3 has a high flow velocity F _b , From this Fig. 9, the flow velocity at each angle is 1.0 to 1.8 m /
β with a transition point where V _A ≠ V _B near s occurs
It can be seen that the characteristics of the flow discontinuity (characteristics without linearity, poor linearity) in the region (discontinuous region). That is, during this period, accurate measurement cannot be performed, so that the measurement range is limited. The product specifications in the case of Fig. 9 are the measurement range flow rate 1.
It will be 0 to 1.8 m / s.

The present invention has been made in view of the above problems of the conventional technique, and an object thereof is to eliminate a discontinuous region of measurement, thereby improving linearity and widening a measurement range. The purpose of this is to provide such a flow velocity meter.

[Means for Solving the Problems] In order to achieve such an object, the present invention generates magnetic lines of force on the outer periphery of a spherical casing disposed in a fluid so as to intersect the flow of the fluid. At the same time, the induced voltage generated when the fluid passes through the magnetic lines of force is measured by a plurality of pairs of measurement electrodes embedded in the outer periphery of the casing at opposite positions, and the flow velocity and the flow direction of the fluid are measured. The anemometer has an uneven portion provided on the outer periphery of the housing excluding the portion where the measurement electrode is provided, and the uneven portion causes the fluid around the housing to be in a turbulent state. I am trying.

[Operation] In order to eliminate the boundary between laminar flow and turbulent flow, the surface of the spherical electrode sensor is made uneven so that the flow of the fluid becomes turbulent even at low flow velocity, and the discontinuity of measurement is eliminated. To do so.

[Examples] Examples will be described with reference to the drawings. In the following drawings, the same parts as those in FIGS. 6 to 9 are designated by the same reference numerals and the description thereof will be omitted.

FIG. 1 is a configuration diagram of a flow velocity meter showing a concrete embodiment of the present invention, FIG. 2 is a top view seen from the AA plane of FIG. 1, and FIGS. 3 and 4 are explanations of the present invention. FIG.

In FIG. 1 and FIG. 2, T is a housing 20 of the spherical electrode sensor so that the flow F of the fluid 3 is in a turbulent state even when the flow velocity is low.
The protrusions are formed on the entire surface of the surface in the form of strips having a width d and are arranged on the entire surface at a constant angle θ. By disposing the protrusions T in this manner, the entire surface shape is an uneven surface. For example, specifically, when the diameter of the surface 20 of the spherical electrode sensor is φ80 mm, the width d is 3 mm, and the intervals θ are arranged at equal intervals of 30 °. By setting the diameter formed by the portion to 82 mm, the shape of the top view as shown in FIG. 2 can be formed. At this time, the electrodes 40a, 40a ', 40b, 40b' are located on the concave surface.

By forming the surface of the spherical electrode sensor as an uneven surface over the entire surface in this manner, the fluid waveform at low flow velocity shown in FIG. 3 (A) changes to the fluid waveform at high flow velocity shown in FIG. 3 (B). As described above, since the fluid waveforms are in the same turbulent state from beginning to end (the flow features are the same), the turbulent flow boundaries shown in FIGS. 8A and 8B are eliminated. As a result, the measurement discontinuity region disappears as shown in FIG. Incidentally, this FIG. 4 corresponds to FIG. 9, and it can be seen that the dead zone region is eliminated in each measurement result.

By the way, the present invention is not limited to FIG. Since it is sufficient that the fluid waveform has the same turbulent state from the low flow velocity to the high flow velocity, the groove may be formed instead of providing the strip-shaped protrusion T, for example. Of course, as shown in FIG. 5A and FIG. 5B, the surface may have a mesh shape as shown in FIG. 5A, or a golf ball type uneven surface (protrusions may be formed as shown in FIG. 5B). It may be attached or each part of the surface may be gouged). The point is that the variation can be easily expanded by the designing method for each case.

[Effects of the Invention] As described above, in order to eliminate the boundary between the laminar flow and the turbulent flow, the present invention makes the surface of the spherical electrode sensor uneven so that the fluid flow becomes a turbulent state even when the flow velocity is low. As the surface is configured to eliminate the discontinuity of measurement, the turbulent flow condition occurs from the low flow velocity area around the sphere, and the flow velocity measurement range of the fluid, for example, 0 to 2.5 m in the case of FIG. At / s, discontinuity of the flow velocity is not observed (does not occur), and linearity can be improved. Therefore, the present invention has an effect that accurate measurement can be performed without being limited to a practical measurement range.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a flow velocity meter showing a concrete embodiment of the present invention, FIG. 2 is a top view seen from the AA plane of FIG. 1, and FIGS. 3 and 4 are explanations of the present invention. FIG. 5 is a view showing another embodiment, FIG. 5 is a diagram showing another embodiment, a configuration diagram of a doorknob type flow direction and current meter using electromagnetic induction in FIG. 6, and FIG. 7 is an outline of a spherical electromagnetic sensor in a conventional flow direction and current meter. External view, FIG. 8 (A),
(B) and FIG. 9 are diagrams for explaining the problems of the conventional technique. DESCRIPTION OF SYMBOLS 1 ... Electromagnet, 2 ... Electromagnetic insulating material housing, 3 ... Fluid, 4
... Electrodes, 5 ... Insulating material, 6,7,9 ... Lead wires, 8 ... Support rods, T ... Protrusions.

Claims (1)

[Claims] 1. A magnetic force line is generated on the outer periphery of a spherical casing disposed in a fluid so as to intersect the flow of the fluid, and an induced voltage generated when the fluid passes through the magnetic force line is generated in the casing. In a flow direction anemometer for measuring a flow velocity and a flow direction of the fluid, which is measured by a plurality of pairs of measurement electrodes embedded at opposite positions on the outer circumference of the body, the casing excluding a portion where the measurement electrode is provided. A flow velocity meter, comprising: a concavo-convex portion provided on the outer periphery of the body, wherein the concavo-convex portion causes the fluid around the housing to be in a turbulent state.