RU2338207C1 - Velocity converter with electric jamming compensation - Google Patents

Abstract

FIELD: physics, measurement.

SUBSTANCE: case of the device holds magnet system of six permanent magnets oriented with one pole to work surface of the case, formed by dielectric coating. Between magnets four electrodes are placed and connected in couples to similar inputs of first and second differential amplifiers of electronic unit. Outputs of first and second differential amplifiers are connected to inputs of third differential amplifier, output of which serves as output of the device. Electrode positioning at rectangle apices allows maximum suppression of electric jamming present in electroconductive medium.

EFFECT: enhanced precision of measurement of electroconductive fluid flow velocity.

2 cl, 6 dwg

Description

The invention relates to measuring technique and is intended to measure the flow rate of an electrically conductive liquid, such as sea water.

The known Smith-Slepian speed meter [1, p.138, Fig. 47], containing an electromagnet formed by a core with a winding located on a solid surface, for example at the side of the ship, and two electrodes. An electromagnet creates a magnetic field in a fluid moving along a solid surface, which leads to the appearance of an emf in it, which is measured as the voltage between the electrodes.

There are various devices for measuring the pulsations of the flow velocity of an electrically conductive liquid, containing a magnetic system, electrodes connected to amplifiers (see, for example, [2] - [4].

There is also known a device for measuring pulsations of the fluid flow rate, which by technical essence is the closest to the proposed one, and is selected as a prototype [5]. The device contains a magnetic system with a working part, made in the form of a wedge, electrodes and a measuring unit, equipped with circuits of the sum and difference, to which the electrodes are connected.

The disadvantage of the prototype device, like all similar devices, is the low measurement accuracy in the presence of electrical noise in an electrically conductive liquid.

The objective of the invention is to provide a device that allows you to measure the flow rate of a conductive fluid under conditions of a high level of electrical noise in the fluid.

The essence of the invention lies in the fact that in a device for measuring the flow rate of a conductive fluid, the magnetic system contains six permanent magnets, the first of which faces one of its poles to the working surface of the housing formed by a coating of dielectric material, the second and third permanent magnets are identical in design, located on opposite sides of the first permanent magnet and facing the working surface of the housing with poles, the polarity of which is opposite to the polarity of the floor the first permanent magnet facing the working surface of the housing, the fourth, fifth and sixth permanent magnets located next to the first, second and third permanent magnets respectively and facing the working surface of the poles, the polarity of which is opposite to the polarities of the poles facing the working surface of the housing, respectively , the second and third permanent magnets, wherein the first electrode is located between the first and second permanent magnets, the second electrode is located between the first m and the third permanent magnets, the third electrode is located between the fourth and fifth permanent magnets, the fourth electrode is located between the fourth and sixth permanent magnets, the electronic unit contains the first and second differential amplifiers, the first inputs of the same name connected respectively to the first and third electrodes, the second inputs of the same name the first and second differential amplifiers are connected respectively to the second and fourth electrodes, the third differential amplifier, the first and second inputs which are connected to the outputs of the first and second differential amplifiers, respectively, and its output is the output of the device.

In the proposed device, the distance between the electrodes mainly satisfy the ratios:

where α ₁₂ , α ₃₄ , α ₁₃ , α ₂₄ are the distances respectively between the first and second, third and fourth, first and third, second and fourth electrodes.

The invention is illustrated by drawings, on which

figure 1 is a drawing of a magnetic system with electrodes;

figure 2 is a section along aa;

figure 3 is a diagram characterizing the relative position of the electrodes;

figure 4 - distribution of the lines of force in the region of the first and second electrodes (in section BB).

figure 5 - distribution of the lines of force in the region of the third and fourth electrodes (in section BB);

6 is an electrical diagram of the device.

Figure 1-6 indicated:

1, ..., 6 - permanent magnets;

7, ..., 10 - electrodes;

11 - case;

12 - working surface of the housing;

13 - coating of the body of a dielectric material;

14, 15 - power lines;

16 - electronic unit;

17, ..., 19 - differential amplifiers.

In the proposed device for measuring the flow rate of a conductive fluid, the magnetic system contains six permanent magnets 1, ..., 6, mounted in a housing 11 made of non-magnetic metal, such as titanium (see Fig.1, 2). The shape of the housing 11 can be very diverse depending on the design of the device. Figure 1-3 shows a device whose magnetic system with electrodes 7, ..., 10 is made in a cylindrical body. This form of the case is technologically advanced both from the point of view of its manufacture and from the point of view of the implementation of the installation site in the device. The working surface 12 of the housing is formed by a coating 13 of a dielectric material in which holes are made for the electrodes 7, ..., 10. An epoxy compound may be used as the dielectric material. Under the working surface 12 refers to the surface along which flows a stream of conductive fluid. The working surface 12 has a predominantly flat shape, but in the general case may also have a convex shape.

Permanent magnets 1, ..., 6 have a predominantly rectangular parallelepiped shape. They are made of hard magnetic material, for example Nd-Fe-B.

The first permanent magnet 1 faces one of its poles, in particular pole S, to the working surface 12 formed by a coating 13 of dielectric material. The second and third permanent magnets 2 and 3, identical in design and parameters, are located on opposite sides of the first permanent magnet 1 and face the working surface 12 with poles N, the polarity of which is opposite to the polarity of the pole S of the first permanent magnet 1 facing the working surface 12.

The fourth, fifth and sixth permanent magnets 4, 5 and 6 are located next to the first, second and third permanent magnets 1, 2 and 3, respectively, and face the working surface of the housing with poles N, S and S, the polarity of which is opposite to the polarities facing the working surface of the housing the poles S, N, and N, respectively, of the first, second, and third permanent magnets 1, 2, and 3. The designs of the permanent magnets 4, 5, and 6 are identical to those of the first, second, and third permanent magnets 1, 2, and 3, respectively.

The electrodes 7, ..., 10 are made primarily of round platinum wire and have a blackening of their end surfaces directly in contact with the electrically conductive liquid, in order to reduce the transition resistance of the electrode - liquid. The first electrode 7 is located between the first and second permanent magnets 1 and 2. The second electrode 8 is located between the first and third permanent magnets 1 and 3. The third electrode 9 is located between the fourth and fifth permanent magnets 4 and 5. The fourth electrode 10 is located between the fourth and sixth permanent magnets 4 and 6.

In the proposed device, the distance between the electrodes mainly satisfy the relations (1) and (2). In this case, the electrodes are at the vertices of the rectangle (see figure 3). In this case, maximum suppression of electrical noise is achieved. The distances α ₁₂ , α ₃₄ , α ₁₃ , α ₂₄ can be measured both between the centers of the electrodes and between their nearest points.

The electronic unit 16 (see Fig.6) contains the first and second differential amplifiers 17 and 18, the first homonymous inputs of which, in particular non-inverting inputs, are connected respectively to the first and third electrodes 7 and 9. The second homogeneous inputs, in particular the inverting inputs, the first and second differential amplifiers 17 and 18 are connected respectively to the second and fourth electrodes 8 and 10, as well as the third differential amplifier 19, the first and second inputs of which are connected to the outputs of the first and second differential amplifiers 17 and 18, and the output is the output of the device. Which of the specific inputs (inverting or non-inverting) of the amplifier 19 is connected to the outputs of the differential amplifiers 17 and 18, does not matter. Compensation of electrical noise occurs in any case. Only the sign of the output signal changes.

The proposed device operates as follows. The flow of an electrically conductive liquid, such as sea water, moves along surface 12. Under the influence of a magnetic field (see Figs. 4, 5), an electric field is created in a moving electrically conductive liquid, the intensity of which is proportional to the speed of the liquid and the magnetic field. At the electrodes 7 and 8 located on the surface 12, electric potentials are proportional to the speed of the fluid. The potential difference between the electrodes 7 and 8 is determined by the potential differences between the points lying on the normals to the surface 12 and passing through the point of contact of the electrodes 7 and 8 with the liquid. If there is electrical interference in the electrically conductive medium, then on electrodes 7 and 8 with a useful signal proportional to the fluid flow rate, the electrical noise signal is proportional to the electric field strength of the interference and the distance between electrodes 7 and 8. The voltage between the electrodes 7 and 8 is applied to the inputs differential amplifier 17, in which the signal is amplified and fed to one of the inputs of the amplifier 19.

Simultaneously, at the electrodes 9 and 10 located on the surface 12, electric potentials are induced, which are proportional to the velocity of the fluid. The potential difference between the electrodes 9 and 10 is determined by the potential differences between the points lying on the normals to the surface 12, and passing through the point of contact of the electrodes 9 and 10 with the liquid. If the parameters of magnets 1 and 4, as well as magnets 2, 3, 5 and 6 are identical, the useful signal on the electrodes 9 and 10, proportional to the fluid flow rate, will be equal to the useful signal on the electrodes 7 and 8, but have the opposite sign, since the power lines 14 in the area of the location of the electrodes 7 and 8 and power lines 15 in the area of the location of the electrodes 9 and 10 have the opposite direction (see figure 4 and 5). If there is electrical interference in the electrically conductive medium, then on the electrodes 9 and 10 with a useful signal proportional to the fluid flow rate, the electrical noise signal is proportional to the electric field strength of the interference and the distance between the electrodes 9 and 10. Under conditions (1) and (2) ) the interference signal at the electrodes 9 and 10 will have the same polarity (the same phase) and approximately the same value as at the electrodes 7 and 8. The voltage between the electrodes 9 and 10 is applied to the inputs of the differential amplifier 18, in which the signal pours and goes to another input of the amplifier 19.

After the amplifier 19 amplifies the difference signal arriving at its inputs, the signal at its output is proportional only to the liquid flow rate, since when subtracting the useful antiphase signals arriving from the outputs of amplifiers 17 and 18, these signals are summed, and common-mode signals proportional to the level of electrical noise are deductible.

The signal at the output of the amplifier 19, proportional to the measured fluid flow rate, can be sent to an indicator or converted to digital form, transmitted via communication lines for processing and recording.

Thus, when using the present invention, a technical result is achieved, which consists in increasing the accuracy of measuring the flow rate of the electrically conductive liquid due to the reduced influence of electrical noise in the studied electrically conductive liquid on the measurement results.

The presented drawings and description make it possible to manufacture the device using known technologies using known materials and use it for measuring fluid flow rates, which characterizes the invention as industrially applicable.

Information sources

1. Sherklif J. Theory of electromagnetic flow measurement. M.: Mir, 1965.

2. A.S. USSR No. 775699, IPC G01P 5/08, publ. 10/30/1980.

3. A.S. USSR No. 1144057, IPC G01P 5/08, publ. 02/07/1985.

4. A.S. USSR No. 1239604, IPC G01P 5/08, publ. 06/23/1986.

5. A.S. USSR No. 679878, IPC G01P 5/08, publ. 08/15/1979 (prototype).

Claims (2)

1. A device for measuring the flow rate of an electrically conductive liquid, comprising a magnetic system located in the housing, electrodes and an electronic unit, characterized in that the magnetic system contains six permanent magnets, the first of which faces one of its poles to the working surface of the housing formed by a coating of dielectric material, second and third permanent magnets identical in design, located on opposite sides of the first permanent magnet and facing the working surface of the body whiskers with poles, the polarity of which is opposite to the pole of the first permanent magnet facing the working surface of the housing, the fourth, fifth and sixth permanent magnets located next to the first, second and third permanent magnets respectively and facing the working surface of the housing with poles whose polarity is opposite to the polarities of the inverted to the working surface of the pole housing, respectively, of the first, second and third permanent magnets, while the first electrode is located between the first and second m permanent magnets, the second electrode is located between the first and third permanent magnets, the third electrode is located between the fourth and fifth permanent magnets, the fourth electrode is located between the fourth and sixth permanent magnets, the electronic unit contains the first and second differential amplifiers, the first inputs of which are connected respectively to the first and third electrodes, the second inputs of the same name of the first and second differential amplifiers are connected respectively to the second and fourth electrodes rows, the third differential amplifier, first and second inputs connected to the outputs of the first and second differential amplifiers, and the output is an output device. 2. The device according to claim 1, characterized in that the distances between the electrodes satisfy the relations: a ₁₂ = a ₃₄ , a ₁₃ = a ₂₄ , where a ₁₂ , a ₃₄ , a ₁₃ , a ₂₄ - the distances respectively between the first and second, third and fourth, first and third, second and fourth electrodes.

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