RU2610912C1 - Device for measuring liquid flow rate - Google Patents

Abstract

FIELD: physics, measurement technology.

SUBSTANCE: invention relates to means of measuring flow rate of liquid media. The device for measuring liquid flow rate comprises an impeller with blades made of ferromagnetic material, placed in a pipe made of non-magnetic material, on the outer side of the pipe there is a signal pickup coil with a U-shaped core made of soft magnetic material, one lead of which is connected to the ground bus, and the other to a receiver, the output of which is connected to the input of a resolver, at the output of which is formed the output signal of the receiver, characterised by that a two-pole magnet is placed at the end of one of the knees of the U-shaped core made of soft magnetic material.

EFFECT: invention increases sensitivity, noise-immunity, accuracy and range of measured flow rates, provides simple and cheap implementation, as well as functional flexibility.

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Description

The device relates to the field of instrumentation, in particular - means for measuring fluid flow. It can be used, for example, to measure the flow rate and speed of a liquid in the fuel line of a power plant.

A number of similar devices for measuring fluid flow are known. For example, an analogue [1: RU No. 2481559 “Method for measuring fluid flow and a device for its implementation”], containing an impeller placed in a pipe made of non-magnetic material, a signal pickup coil with a core made of magnetically soft material, one output of which is connected to the ground bus, and the other is with the input of the receiver, the output of which is connected to the input of the decisive unit, at the output of which the output signal of the receiver is formed, which coincides with the essential features of the proposed one.

In addition, a generating unit has been introduced, the signal of which is fed to the coil, the signal amplitude of which changes as the impeller blades pass with permanent magnets fixed to them.

The disadvantage of this analogue, as shown by the estimates, is to reduce the sensitivity, accuracy and dynamic range.

An analogue is also known [2: US Pat No. 5199307 "Automatic power generation type flowmeter", containing an impeller, a signal pickup coil with a core made of soft magnetic material, one output of which is connected to the ground bus, and the other to the input of the receiver, the output of which is connected to the input a deciding unit, at the output of which the output signal of the receiver is formed, which coincides with the essential features of the proposed one.

In addition, the signal in the coil is formed by alternating the poles of permanent magnets associated with the impeller, inside the magnetic circuit, which leads the induced magnetic flux to the turns of the coil.

This method has the disadvantages of the above analogue [1].

Closest to the claimed is a device adopted as a prototype [3: US Pat. No. 4,404,860 “Flow rate sensor”], comprising an impeller placed in a pipe made of non-magnetic material, a signal pickup coil with a core of magnetically soft material, one terminal of which is connected to the ground bus, and the other with the input of the receiver, the output signal of which goes to the input of the deciding unit, the output of which is formed by the output signal of the receiver, which coincides with the essential features of the proposed.

In addition, a generating unit has been introduced, the signal of which passes through the capacitance to a coil, in which a signal is formed with the amplitude changing as the impeller blades pass.

The work of the prototype is based on the fact that the generator signal is fed to the L-C chain tuned to the frequency of the series resonance when the impeller blade is outside the zone between the ends of the U-shaped core made of soft magnetic material. When the impeller blade moves to the area between the ends of the core, the inductance L of the coil increases, the condition of the series resonance of the L-C chain is violated, and dips are formed on the envelope of the signal taken from the coil, according to the repetition rate of which determine the speed of rotation of the impeller and, accordingly, the measured fluid flow rate.

The disadvantage of the prototype is to lower sensitivity, accuracy and dynamic range.

In order to overcome these drawbacks, a device for measuring fluid flow is proposed, a block diagram of which is shown in FIG. 1, containing an impeller 1 with blades 2 of ferromagnetic material, placed in a pipe 3 of non-magnetic material, on the outside of the pipe 3 there is a signal pickup coil 4 with a U-shaped core 5 made of soft magnetic material, one terminal of which is connected to the earth bus, and the other - with the input of the receiver 6, the output of which is connected to the input of the decision block 7, the output of which is formed by the output signal of the device.

At the same time, at the end of one of the knees of the U-shaped core 5 made of soft magnetic material, a bipolar magnet 8 is placed.

In addition, the distance S _C between the ends of the U-shaped core 5 is less than the distance S _L between the blades 2 of the impeller 1 (Fig. 1).

In addition, the bipolar magnet 8 is made in the form of a permanent magnet.

In addition, the bipolar magnet 8 is made in the form of a solenoid placed on a U-shaped core 5.

In addition, the distance S _C between the ends of the U-shaped core 5 coincides with the distance S _L between the blades 2 of the impeller 1, the ends of the blades 2 of the impeller 1 and the knees of the U-shaped core 5 at the point of maximum convergence are parallel to each other and are limited by a common cylindrical surface, and between the blades 2 of the impeller 1 inserted insert 9 of ferromagnetic material (Fig. 2).

In addition, the bipolar magnet 8 is fixed on the axis of rotation 10, perpendicular to the magnetization vector of magnet 8 and the longitudinal axis of one of the elbows of the U-shaped core 5 (Fig. 3).

In addition, between the end face of the U-shaped core 5 and the magnet 8 introduced an adjustable gap 11 (Fig. 4).

The proposed device provides increased sensitivity, noise immunity, accuracy and range of measured speeds, simplicity and cost-effectiveness of implementation, as well as functional flexibility.

List of Drawings

FIG. 1. The block diagram of the proposed device according to p. 1 of the formula.

FIG. 2. The embodiment of the node of the proposed device according to p. 5 formulas

FIG. 3. The schematic diagram of the proposed device according to p. 6 formulas.

FIG. 4. The embodiment of the node of the proposed device in paragraph 7 of the formula

In FIG. 1 - FIG. 4 the following notation is accepted:

1 - impeller,

2 - impeller blade 1,

3 - pipe made of non-magnetic material,

4 - signal pickup coil,

5 - U-shaped core of soft magnetic material,

6 - receiver

7 - a crucial unit,

8 - bipolar magnet,

9 - inserts of ferromagnetic material,

10 - axis of rotation of the magnet,

11 - adjustable clearance.

In FIG. 1 shows a block diagram of the proposed device according to p. 1.

In FIG. 2 shows an embodiment of the assembly of the proposed device according to claim 5, where it is shown that the distances S1 = S2 and the ends of the impeller blades and the U-shaped core of magnetically soft material simultaneously reach a minimum distance between them, are parallel to each other and are limited by a common cylindrical surface, and between the blades 2 of the impeller 1, inserts 9 of ferromagnetic material are introduced.

In FIG. 3 shows an embodiment of the assembly of the device according to claim 6, where it is shown that the magnet 8 is made in the form of a diametrically magnetized disk worn on the axis 9.

In FIG. 4 shows an embodiment of the assembly of the device according to claim 7, where it is shown that an adjustable gap 10 is introduced between the end face of the U-shaped core 5 and magnet 8.

The proposed device operates as follows.

The bipolar magnet 8 creates a magnetic flux in the U-shaped core 5, determined by the magnitude of the magnetic induction and the resistance of the magnetic core gap, depending on the distance between the ends of the U-shaped core 5. When passing the impeller blades 2 in the area of the scattering fields - between the ends of the U-shaped core 5, the magnetic resistance of the magnetic core gap decreases and the induction of the field in the core increases. Accordingly, induction EMF is formed in coil 4. The signal of the coil is amplified by the receiver 6, and the frequency of these pulses is analyzed by the decision unit 7, which (with appropriate calibration) determines the output parameter of the device - the flow rate of the liquid in the line - pipe 3, which is made of non-magnetic material, so as not to change the picture of the magnetic field lines than The sensitivity of the device and its dynamic range are increased.

The shape of the U-shaped core also provides increased sensitivity of the device, its dynamic range and noise immunity, since the working area of the space is limited by the interpolar region of the core. In addition, for external magnetic interference, the demagnetizing factor is twice as much as for a useful signal, which also positively affects the noise immunity of the device. In addition, signals induced by external interference will be subtracted at the knees of the core, which also increases the noise immunity of the device. And, accordingly, its sensitivity.

In this case, the distance between the ends of the U-shaped core is made smaller than the distance between the impeller blades in order to increase the clarity of the threshold of the receiver 6 and to avoid interference of signals from two adjacent blades.

A bipolar magnet is made, for example, in the form of a permanent magnet, which simplifies the device and improves its overall characteristics.

In one embodiment of the proposed bipolar magnet is made in the form of a solenoid located on one of the elbows of the U-shaped core and connected to an adjustable current source. This provides the possibility of electronic adjustment of the device parameters, optimization of its operating mode. For example, when working in the field of low flow rates, the sensitivity of the device can be increased by increasing the current supplying the solenoid. This extends the dynamic range of the device. In addition, the mode of fast core remagnetization with high-quality narrow-band filtering of the output signal of the coil and its detection can be used. This additionally increases the noise immunity and sensitivity of the device, expanding the range of measured fluid flow rates.

The maximum sensitivity of the device is realized when the distance between the ends of the U-shaped core coincides with the distance between the impeller blades, the ends of the impeller blades and the knees of the U-shaped core at the point of maximum convergence are parallel and conformal to each other, i.e. bounded by a common cylindrical surface, and inserts of ferromagnetic material are introduced between the impeller blades, as shown in FIG. 3. In this case, the maximum rate of change of flow in the core 5 is realized (for given and identical sections of the ends of the blades 2 and the ends of the core 5) and, accordingly, the maximum value of the induced EMF of induction in coil 4, because the magnetic gap is minimal and the generated EMF is obviously maximum. Indeed, the minimum gap in this case is comparable with the distance between the ends of the core and the blade, which can be made on the order of units of millimeters, and the maximum is determined by the spacing of the core knees from each other, i.e. the value is an order of magnitude larger. The well-known cubic dependence of the magnetic field of the dipole on distance confirms the validity of the statement about the obtained positive effect. This increases the noise immunity of the device.

It also seems appropriate to design a device in which a bipolar magnet is mounted on an axis of rotation perpendicular to the magnetization vector of the magnet and the longitudinal axis of one of the elbows of the U-shaped core. This provides the ability to smoothly adjust the magnetization of the core to bring it to the optimal operating mode.

The same goal is achieved in the design of the device, in which an adjustable clearance is introduced between the end face of the U-shaped core and the magnetic element.

Moreover, as follows from the foregoing, the disadvantages of the prototype, indeed, are overcome - in the proposed device provides:

- increased dynamic range of the measured flow rate,

- ease of implementation, which also provides increased reliability and economic efficiency of the device, as well as functional flexibility.

- high noise immunity of the device to impulse noise, along with its high sensitivity.

As follows from the above analysis, the required technical result is achieved due to significant differences of the proposed.

The experiments showed the feasibility of the proposed object of the invention. As follows from the obtained experimental data, the sensitivity threshold of the proposed device lies in the range of fluid flow rates from 0.01 to 10 m / s.

Next, we show that the technical result and the positive effect provided by it is provided due to the significant differences of the proposed.

The fact that the device contains an impeller with blades of ferromagnetic material placed in a pipe of non-magnetic material, a signal pickup coil with a U-shaped core of magnetically soft material is placed on the outside of the pipe, one output of which is connected to the ground bus and the other to the receiver input the output of which is connected to the input of the deciding unit, the output of which is the output signal of the receiver, and at the end of one of the elbows of the U-shaped core made of soft magnetic material, bipolar magnesium is placed t, provides the claimed technical result: increased sensitivity, noise immunity, accuracy and range of measured speeds. Indeed, an impeller with blades of ferromagnetic material, placed in a pipe of non-magnetic material, provides a change in the magnetic flux through the coil, forming an induction emf, and the U-shape of the core compensates for the external common-mode noise, and reduces its effect also due to an increase in the demagnetizing factor. In addition, the U-shape of the core doubles the number of samples. In addition, the compactness of the scattering fields also contributes to the achievement of the claimed positive effect.

The fact that the distance between the ends of the U-shaped core is not greater than the distance between the impeller blades, contributes to the compactness of the scattering fields and the achievement of the claimed positive effect.

The fact that the bipolar magnet is made in the form of a permanent magnet, provides simplicity and cost-effectiveness of implementation.

The fact that the bipolar magnet is made in the form of a solenoid placed on one of the legs of the U-shaped core and connected to an adjustable current source allows you to adapt the magnetization mode to the range of measured speeds, in addition, it allows verification of suitability without disconnecting the cable network, which ensures functional flexibility devices.

The fact that the distance between the ends of the U-shaped core coincides with the distance between the impeller blades, the ends of the impeller blades and the knees of the U-shaped core at the point of maximum convergence are parallel to each other and are limited by a common cylindrical surface, and inserts of ferromagnetic material are introduced between the impeller blades change the core magnetization as sharply as possible with a corresponding increase in the amplitude of the output signal.

The fact that the bipolar magnet is mounted on the axis of rotation perpendicular to the magnetization vector of the magnet and the longitudinal axis of one of the elbows of the U-shaped core also increases the functional flexibility of the device, providing a smooth adjustment of the magnetization of the core.

The fact that an adjustable gap is introduced between the end face of the U-shaped core and the magnetic element, as in the previous case, increases the functional flexibility of the device, providing smooth adjustment of the core magnetization.

Thus, it is shown that the claimed positive effect and technical result are achieved due to significant differences of the proposed device, given in the claims.

Modeling showed the possibility of achieving the stated positive result in the proposed.

Claims (7)

1. A device for measuring fluid flow, containing an impeller with blades of ferromagnetic material, placed in a pipe of non-magnetic material, on the outside of the pipe there is a signal pickup coil with a U-shaped core of magnetically soft material, one output of which is connected to the ground bus, and the other - with the input of the receiver, the output of which is connected to the input of the crucial unit, the output of which is the output signal of the receiver, characterized in that at the end of one of the knees of a U-shaped core made of magnesium omyagkogo material disposed pole magnet. 2. A device for measuring fluid flow according to claim 1, characterized in that the distance between the ends of the U-shaped core is less than the distance between the impeller blades. 3. A device for measuring fluid flow according to claim 1, characterized in that the bipolar magnet is made in the form of a permanent magnet. 4. A device for measuring fluid flow according to claim 1, characterized in that the bipolar magnet is made in the form of a solenoid placed on one of the elbows of the U-shaped core and connected to an adjustable current source. 5. A device for measuring fluid flow according to claim 1, characterized in that the distance between the ends of the U-shaped core coincides with the distance between the impeller blades, the ends of the impeller blades and the knees of the U-shaped core at the point of maximum convergence are parallel to each other and are limited to a common cylindrical surface, and between the impeller blades introduced inserts of ferromagnetic material. 6. A device for measuring fluid flow according to claim 1, characterized in that the bipolar magnet is mounted on a rotation axis perpendicular to the magnetization vector of the magnet and the longitudinal axis of one of the elbows of the U-shaped core. 7. A device for measuring fluid flow according to claim 1, characterized in that an adjustable clearance is introduced between the end face of the U-shaped core and the magnetic element.

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