RU154440U1 - VAN FLOW METER - Google Patents

Abstract

1. A vane flow meter comprising a housing formed of two sections interfaced with a bellows, a disk-shaped blade, a transducer mounted on a hinge with a two-arm lever, and a disk-shaped blade mounted on its shoulder in one section of the housing, and the transducer is kinematically connected to the second shoulder in another section of the housing, characterized in that the converter is made in the form of a self-oscillating balance-stretching system with a magnetoelectric drive with a bifilar electric coil and an electronic form circuit drive pulses, while one end of the brace is fixedly mounted on the housing, and its second end is mounted on a clutch mounted on a two-arm lever. 2. The vane flow meter according to claim 1, characterized in that the hinge of the two shoulders of the lever is made in the form of a separation membrane of low bending stiffness. 3. The vane flowmeter according to claim 1, characterized in that the coupling with the two-arm lever is formed to form a gap. 4. The vane flow meter according to claim 1, characterized in that the transducer is provided with a spring in the form of an elastic beam, one end of which is fixed in a swivel joint having a position lock, and the other is fixed to the coupling. The vane flowmeter according to claim 1, characterized in that the electronic drive pulse generation circuit is based on a bipolar transistor with a common emitter, while one section of the bifilar electric coil is connected to the base of the transistor and the common bus, and the second to the collector of the transistor and the power bus, the collector and base of the transistor are connected by a capacitor. 6. Vane flowmeter according to claim 1, characterized in that the casing section with

Description

The utility model relates to the field of instrumentation, namely to devices for measuring the flow of a continuous medium and can be used to measure the flow of liquid and gaseous media in highways.

Known flow meters with analog conversion of measurement information. A method of measuring the flow rate of the medium and a device for its implementation (IPC patent RU 2314496 C1 IPC G01F 1/20, 15/12, publ. 10.01.2008) involves the creation of a recess in the path of the flow with an asymmetric curved surface of double curvature with subsequent measurement of the difference between the pressure at the point on an initially smooth surface and at a point located on a concave curved surface. However, with the apparent simplicity of the design, the manufacturing technology of a curved surface of double curvature is complex. Low and operational manufacturability, since the resulting deposits change the original surface shape;

The flow meter (patent RU 2362123 C2 IPC G01F 1/20, 1/34, GO1N 9/22, published on July 20, 2009) also uses a differential pressure. The flow meter comprises a two-part housing, a supply nozzle and a nozzle for supplying the medium to be measured into the receiving opening of the housing, and an outlet pipe. The body chambers are separated by a partition and a membrane and are filled respectively with the measured medium and the test medium (liquid with a known density: water, alcohol, ether). Membranes with bodies of positive buoyancy fixed on them divide the corresponding chambers into the supmembrane cavities and the submembrane cavities. Sealing elements in the form of pistons rigidly fixed to bodies of positive buoyancy are introduced into the channels of the housing connecting the submembrane cavities and the cavity between the nozzles. The housing channels are combined with two differential transformer transducers of membrane movements. Signal processing of primary information is carried out by a microcontroller. As you can see, the design is complex, respectively, its production manufacturability is low.

Devices containing oscillatory links are of interest, since the frequency signal is quantized with high accuracy and reliability. They talk about metrological manufacturability, because in the general chain of signal transformations, some of the converters can be performed on typical elements of digital electronics.

The inkjet flow sensor (patent RU 2200302 C2 IPC G01F 1/20, published March 10, 2003) consists of an oscillation generator and a differential pressure transducer. The oscillation generator uses a discrete inkjet element with a power nozzle, a working chamber with inclined walls, a separator with a deflector, drainage channels, control nozzles, feedback channels and output channels. The hydraulic part of the sensor has a very complex shape, therefore, low productivity technology.

Known jet flow meter and method for its implementation (patent RU 2421690 C2 IPC G01F 1/20, 15/02, publ. 20.06.2011). The jet flow meter (CP) contains a flanged measuring pipe with a constricting device in the form of a diaphragm, the high and low pressure chambers of which are connected to the jet oscillator (SAG), a piezoelectric pressure transducer with three plates, two of which are facing the jet exiting the SAG, and the third lining is common, and the electronic unit, which includes interconnected jet oscillation indicator, which includes a differential amplifier, a signal conditioning unit, a secondary pre verters indicator signal and the volume flow. Sheet dampers are introduced in the respective CP nodes. The ratio of the thicknesses of the damper and each of the walls of the device is from 1 to 10. To protect against the penetration of common-mode electrical and electromagnetic interference, high-resistance input circuits with a differential amplifier are placed in an additional protective shield and isolated from local grounding. This complex design is also characterized by low production manufacturability.

Comparatively higher adaptability are flow meters with a rotary blade. Their manufacturability (in the broad sense of the term) essentially depends on the form of signal processing (analog, frequency) and the arrangement of bearing assemblies. In the presence of constant (Coulomb) friction in the bearing unit there is a stagnation zone, determined by the coefficient of friction f _Tr. In angular terms, the stagnation zone is

If there is a stagnation zone in the kinematic chain, the blade will not come to its nominal position. As a result, in the case of decreasing costs, we obtain an overestimated value of the expense (non-income from above), and in the case of increasing expenses, an underestimated value (non-income from below).

As a prototype, a compensation flow meter with a rotary blade of the DRP-1 brand was adopted (Kremlevsky P.P. Flow meters and quantity counters: a reference book, 4th ed. Revised and additional - L .: Mashinostroenie, 1989. P. 258).

In one section of the housing in the flow of the measured medium is a disk-shaped blade. This blade is mounted on the first shoulder of the two shoulders of the lever, which is mounted on the hinge in the housing. The second shoulder of the two shoulders of the lever is located in another section of the housing and is kinematically connected with the transducer. The converter converts the hydrodynamic drag force developed by the blade and transmitted by the two-arm lever to the output signal. The housing sections are separated by a bellows, as a result, the section with the blade is under the pressure of the measured flow, and the section with the transducer is under atmospheric pressure.

The converter is organized on pneumatic elements. The kinematic connection with the two-arm lever is also pneumatic. A two-arm lever has a damper that interacts with the throttle nozzle. When the two-arm lever is turned, the throttle air pressure increases and, passing the pneumatic amplifier, acts on the feedback bellows. The force of the feedback bellows through the lever and traction creates a counteracting moment on the two-arm lever. Thus, the current angle of rotation of the two shoulders of the lever is small. The analog output is the air pressure in the feedback bellows.

The low production manufacturability of the flowmeter in question is due to the high requirements for the hinge of the two shoulders of the lever to minimize friction. The friction problem is compounded by the fact that the angle of rotation of the two shoulders of the lever is commensurate with the angle of stagnation. Operational adaptability is limited by the requirements for stability of air pressure in the supply line of the converter. The analog output waveform limits metrological manufacturability.

The technical result of the proposed solution is to increase the manufacturability of the flow meter.

This result is achieved by the fact that in a vane flow meter containing a housing formed of two sections interfaced with a bellows, a disk-shaped blade, a transducer mounted in the housing on a hinge is a two-arm lever, while a disk-shaped blade is mounted on its shoulder in one section of the housing, and the transducer kinematically connected with the second shoulder in another section of the housing, the transducer is made in the form of a self-oscillating balance-stretching system with a magnetoelectric drive with a bifilar electric wire and electric an electronic drive pulse generation circuit, with one end of the extension fixed to the housing, and the other end fixed to a clutch mounted on a two-arm lever. In paddle flow meter hinge

two shoulders of the lever is made in the form of a separation membrane of low rigidity, the coupling with the two shoulders of the lever is made with the formation of a gap. The converter is equipped with a spring in the form of an elastic beam, one end of which is clamped in a swivel joint having a position lock, and the other is fixed to the coupling. The electronic drive pulse generation circuit is based on a bipolar transistor with a common emitter, while one section of the bifilar electric coil is connected to the base of the transistor and a common bus, and the second to the collector of the transistor and the power bus, the collector and base of the transistor are connected by a capacitor. Section of the housing with the Converter is sealed.

In FIG. 1 shows an axial section through a flow meter; in FIG. 2 is a section AA in FIG. one; in FIG. 3 is a diagram of a drive pulse formation.

Accepted Designations

1. Case

2. Disk shaped blade

3. Thrust

4. Two shoulders lever

5. The separation membrane

6. The membrane ring

7. Ring screws

8. The membrane sleeve

9. Stretching

10. Balance

11. Magnetic balance sleeve

12. Flat magnetic circuits of balance

13. Permanent magnets

14. Counterweights

15. Bottom stretch pad

16. Screws

17. Bracket

18. Screws

19. Overlay

20. Screws

21. Coupling

22. Spring (elastic beam)

23. Swivel Joint

24. Electrical Insulation Rack

25. Hinge fixing screw 23.

26. Bifilar electric coil

27. SFIP

28. Overlay

29. Screws

30. Cable

31. Electrical connector

32. Bellows

33. Bellows threaded sleeve

34. Cap

35. Screws

The mounting base of the flowmeter is the housing 1, while one section of the housing is made in the form of a pipe, which has flanges at the ends for connection with a pipeline of flowing gas or liquid. On a part of the length, the pipe is reinforced over the cross section to form a flat surface B. To the left of surface B (see Fig. 1) there is another section of the housing in which the converter is located.

The sensitive element of the flow meter is a blade 2 in the form of a disk. The blade using the rod 3 is connected to the end of the two shoulders of the lever 4 (input shoulder), while between the blade and the inner cylindrical surface of the housing an annular gap is formed. The lever hinge is made elastic in the form of a dividing membrane 5. The membrane is connected in a loop to the ring 6 (for example, by rolling), and the ring is fastened in the housing bore with screws 7. In the center of the membrane, a sleeve is fixed by rolling 8. The lever 4 is connected to the sleeve 8, for example, by brazing .

The execution of the hinge of the two shoulders of the lever in the form of a separation membrane minimizes its bending moment and reduces the stagnation zone to zero (Andreeva L.E. Elastic elements of devices. - M .: Mashgiz, 1962. - 465 s).

The transducer is a self-oscillating system composed of an oscillator (oscillating link) in the form of an elastic element - a stretch 9 and an inertial mass - balance 10. The balance is made by the magnetic core 11, at the ends of which are fixed magnetic circuits 12. At the ends of the flat magnetic circuits are counter-mounted (for example, glue) permanent magnets 13 axial magnetization with the formation of a magnetic gap with a uniform magnetic field. Counterweights are fixed at the other ends of the balance magnetic circuits 14. The balance assembly unit is fixed in the middle part of the extension 9 with the help of semicircular conical pins. This is the typical mount in FIG. 1 is not reflected. Stretching 9, of rectangular cross section, is fixed at one end (bottom) by a cover 15 with screws 16 in an arm 17, fixed by screws 18 on the plane B of the housing, and above - by a cover 19 by means of screws 20 is connected to the coupling 21. The coupling is a communication element between the lever 4 (output shoulder) and an adjustable elastic support for the upper fastener of the extension. The coupling with the lever 4 is carried out with some clearance. An adjustable elastic support is represented by a spring (elastic beam) 22, one end pinched in a sleeve and the other in a rotatable fixed hinge 23. The hinge is installed in an insulating post 24 and is represented by a screw 25 as a fixing element.

To ensure self-oscillating movement of the balance, a magnetoelectric drive is used, which includes, in addition to the magnetic balance system, where it is convenient to see the magnetic gap noted above, a bifilar (wound in two wires) frameless coil 26, controlled by the pulse formation circuit of the SIPIP drive 27. The coil 26 is mounted on a rack 23 using pads 28 and screws 29. The drive pulse formation circuit (Fig. 3) in the simplest case is an electronic key based on a VT transistor, in the base circuit of which it is connected with the projection W _{0 of the} bifilar coil, and in the collector coil, another W _u . To prevent the occurrence of high-frequency generation due to mutual induction, a negative feedback circuit is provided on the capacitor C. The SFIP elements are mounted by mounting on the side surface of the rack 23 and are connected by a cable 30 to an electrical connector 31. The connector is fixed on the plane B of the housing, and the cable in front of it is laid in groove of the body and filled with compound.

The stated design of the converter is an autonomous assembly unit, which ensures manufacturability. The assembly unit includes all the elements fixed on a mounting base bracket 17 - rack 24. The autonomy of the transducer allows you to set the symmetrical position of the coil 26 in the magnetic balance gap 10, and by turning the hinge 23 to implement the preliminary tension F _{0 of the} stretch 9 and check the operation of the drive with the SFIP circuit.

Given the excess pressure of the flow of the measured substance in order to reduce the additional deformation of the separation membrane, the proposed flowmeter provides pressure equalization on opposite sides of the membrane 5. This function is performed by a low-rigidity bellows 32. The bellows is mounted on the housing 1 using an intermediate threaded sleeve 33. Such a design equalizes the pressure in the section of the pipeline where the vane 2 is located, and in the converter section, the volume of the latter is sealed with a cap 34 using fixing screws 35.

Define the conversion function of the flowmeter. Under the action of the flow of the measured substance from top to bottom (drawing orientation), the force R arising under the action of the hydrodynamic pressure of the flow forms the rotation moment M of the lever 4

where l ₁ - shoulder strength R is the distance from the point of suspension of the blade to the point of rotation of the center of the membrane;

here φ _l is the coefficient of resistance of the blade;

ρ is the density of the substance of the stream;

V is the flow rate;

f _l - the area of the blade;

Q ₀ - volumetric flow rate;

S is the area of the pipeline.

The torque M is converted into a frequency electrical signal by a converter.

After preliminary adjustment of the assembled transducer, the circular (cyclic) balance oscillation frequency is

where in the numerator under the radical is the torsional tension stiffness, and in the denominator the moment of inertia of the balance relative to the central axis is I _b . It is indicated in the formula (4):

b, s, l - respectively, the width, thickness of the cross section of the stretch of rectangular section and its length;

G is the shear modulus of the stretch material;

F ₀ is the tensile pre-tension force.

Accordingly, the natural frequency is

After attaching the transducer to the housing, in which the lever 4 enters the hole of the coupling 21, a measuring circuit is formed. In this chain, the hydrodynamic pressure force of the flow R (3) is converted to the frequency of the balance oscillations.

In the presence of flow rate Q ₀ , a force R appears - the formula (3) of the hydrodynamic resistance of the blade 2, due to this force, the tension of the stretch 9 increases by the value of F _ISM .

Leverage 4 Equilibrium Condition

where F = F ₀ + F _ISM

l ₂ is the shoulder of the lever 4 from the point of rotation of the membrane 5 to the sleeve 21. Obviously by the condition of balance of the lever 4

Given the formulas (2-5), we obtain the current value of the frequency f depending on the flow rate Q ₀

We introduce the notation through the primary parameters

;

;

;

;

.

.

Then formula (8) takes the form

Formula (9) is a conversion function, i.e., it establishes a relationship between the measured parameter Q ₀ and the output parameter f.

The proposed paddle flow meter is used either as part of a measuring and computing complex, or as a stand-alone device. In the second case, it is advisable to supplement the flowmeter with an electronic unit, for example, based on a microcontroller, into the flash memory of which the conversion function is "sewn up" (9).

The flow meter operates as follows. When flow rate Q ₀ appears, the hydrodynamic pressure force R (formula 3) acts on the blade 2. This force by lever 4 changes the tensile preload F ₀ by the value of F _ISM (formula 7), which leads to a change in the frequency of the output signal of the SIPP converter. This frequency change is processed by the electronic block of the flowmeter according to the formula (9).

Note that the condition

and the upper boundary is determined by mechanical stresses in the elements of kinematics, especially in stretching.

Thus, the proposed design of the blade flowmeter is high-tech at all stages of the life cycle. The block design allows the design and processing of a range of flow meters in parallel. Manufacturing manufacturability is realized by the simple form of parts, the widespread use of standard elements - components, rolled products. In operation, there is no need to maintain kinematic friction pairs. The value of the frequency of the output signal in the absence of a measured flow serves as a criterion for the next metrological verification. The frequency output signal is quantized with high accuracy and reliability, which simplifies the subsequent use of information. Power stability requirements are minimal.

Claims (6)

1. A vane flow meter comprising a housing formed of two sections interfaced with a bellows, a disk-shaped blade, a transducer mounted on a hinge with a two-arm lever, and a disk-shaped blade mounted on its shoulder in one section of the housing, and the transducer is kinematically connected to the second shoulder in another section of the housing, characterized in that the converter is made in the form of a self-oscillating balance-stretching system with a magnetoelectric drive with a bifilar electric coil and an electronic form circuit drive pulses, while one end of the brace is fixedly mounted on the housing, and its second end is mounted on a clutch mounted on a two-arm lever. 2. The vane flowmeter according to claim 1, characterized in that the hinge of the two shoulders of the lever is made in the form of a dividing membrane of low bending stiffness. 3. The vane flowmeter according to claim 1, characterized in that the coupling with the two-arm lever is formed to form a gap. 4. The vane flowmeter according to claim 1, characterized in that the transducer is provided with a spring in the form of an elastic beam, one end of which is fixed in a swivel joint having a position lock, and the other is fixed to the coupling. 5. The vane flow meter according to claim 1, characterized in that the electronic drive pulse generation circuit is based on a bipolar transistor with a common emitter, while one section of the bifilar electric coil is connected to the base of the transistor and the common bus, and the second to the collector of the transistor and the bus The power supply, collector and base of the transistor are connected by a capacitor. 6. The vane flowmeter according to claim 1, characterized in that the section of the housing with the transducer is sealed.

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