JPH10142018A - Vortex flow meter - Google Patents

Abstract

(57) [Summary] PROBLEM TO BE SOLVED: It has good sensitivity to lift, can detect a vortex signal stably and reliably even under high static pressure, has a good S / N ratio,
Provide an inexpensive vortex flowmeter. The vortex flowmeter includes a vortex generator inserted into a measurement pipe through which a measurement fluid flows, and measures a flow rate by detecting an alternating force acting on the power receiver by Karman vortex. A main body unit in which at least a joining portion of the measuring pipe to which the force receiving body is joined is integrally formed from the beginning, and the receiving force of at least one of two joining portions of the measuring pipe and the force receiving body. A thin annular pressure seal fulcrum formed around the body; and a pressure seal fulcrum attached to the force receiving member such that the pressure seal fulcrum can be prevented from being deformed by the static pressure of the measurement fluid. And a backup plate for backing up the pressure seal fulcrum body with one surface in contact with the surface of the thin annular ring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inexpensive vortex flow meter which has a good sensitivity to lift, can detect a vortex signal stably and reliably even under a high static pressure, has a good S / N ratio, and is inexpensive. .

[0002]

2. Description of the Related Art FIG. 16 is an explanatory view of the structure of a conventional example generally used in the prior art.
No. 18 (Japanese Patent Application No. 1-033256).
Reference numeral 10 denotes a pipe through which a fluid flows, and reference numeral 11 denotes a cylindrical nozzle provided at right angles to the pipe 10.

[0003] Reference numeral 12 denotes a pipe 1 at an interval from the nozzle 11.
It is a column-shaped vortex generator having a trapezoidal cross section inserted at a right angle to 0, one end of which is supported by a pipe 13 by a screw 13,
The other end is fixed to the nozzle 11 by a screw or welding at a flange portion 14. Reference numeral 15 denotes a concave portion provided on the flange portion 14 side of the vortex generator 12.

A first common electrode 16 made of metal, a piezoelectric element 17, and an electrode plate 1 are sequentially placed in the recess 15 from the bottom thereof.
8, an insulating plate 19, an electrode plate 20, and a piezoelectric element 21 are arranged in a sandwich shape, and these are pressed and fixed by a metal pressing rod 22. Further, the lead wire 2 is
3. A lead wire 24 is connected from the electrode plate 20 to the terminal A,
B has been drawn.

[0005] The piezoelectric elements 17 and 21 are
The left and right sides of the paper 21 are polarized in opposite directions, respectively, and generate opposite-polarity charges on the upper and lower electrodes with respect to the stress in the same direction.

The electric charge generated in the piezoelectric element 17 is applied to the electrode plate 1
The electric charge obtained between the terminal A connected to the terminal 8 and the conduit 10 connected via the pedestal 16 and generated in the piezoelectric element 21 is supplied to the terminal B connected to the electrode plate 20, the pressing rod 20, It is obtained between the connected pipeline 10.

The charges generated on the two electrode plates 18 and 20 are input to charge amplifiers 25 and 26 as shown in FIG. The output of the charge amplifier 25 and the output of the charge amplifier 26 via the volume 27 are added by an adder 28 to obtain a flow signal. This flow signal is converted, for example, into a current output and transmitted to the load via two wires (not shown). Next, the operation of the vortex flowmeter configured as described above will be described with reference to FIGS.

When the fluid flows through the conduit 10, vibrations are generated in the vortex generator 12 by Karman vortices in the direction indicated by the arrow F. Due to this vibration, the vortex generator 12 has the shape shown in FIG.
The stress distribution shown in FIG. 18 and the reverse stress distribution are repeated, and the piezoelectric elements 17 and 21 are repeatedly charged + Q and -Q corresponding to the signal stress having the vortex frequency shown in FIG. . In FIG. 18, for convenience of explanation, the electrode plate 18 or 21 is divided into two parts on the left and right with respect to the paper surface, and one of the upper and lower electrodes is mounted on the base 16 or the pressing rod 2.
It is equivalent to 2.

On the other hand, the pipe line 10 also generates pipe line vibrations that cause noise. The pipeline vibration is divided into a drag direction in the same direction as the fluid flow, a lift direction perpendicular to the fluid flow, and a longitudinal component of the vortex generator. this house,
The stress distribution for the vibration in the drag direction is as shown in FIG. 18 (b), and the positive and negative charges are canceled in one electrode and no noise charge is generated. Also, as shown in FIG. 18C, the vibration in the longitudinal direction is canceled in the electrode, and no noise charge is generated as in the case of the drag direction.

However, the vibration in the lift direction has the same stress distribution as the signal stress, and generates noise charges. Therefore, the following calculation is performed to eliminate this noise charge. The charges of the piezoelectric elements 17 and 21 are Q ₁ and Q ₂ , the signal components are S ₁ ,
S ₂ , the noise components in the lift direction are N ₁ and N _2, and when the polarization is reversed by the piezoelectric elements 17 and 21, Q ₁ and Q ₂ are expressed by the following equations. Q ₁ = S ₁ + N ₁ -Q ₂ = -S ₂ -N ₂

However, the vector directions of S ₁ and S ₂ and N ₁ and N ₂ are the same. Here, the relationship between the signal component and the noise component of the piezoelectric elements 17 and 21 is as shown in FIG. 19 (this diagram shows the relationship between the noise and the signal in the lift direction and the bending moment of the vortex generator). Therefore, the output of the charge amplifier 25 on the piezoelectric element 17 side is added to the adder 28 as shown in FIG.
In addition, when the sum is multiplied by N ₁ / N ₂ together with the volume 27 and added to the output of the charge amplifier 26 on the piezoelectric element 21 side, Q ₁ −Q ₂ (N ₁ / N ₂ ) = S ₁ −S ₂ (N ₁ / N ₂ ), and the line noise is removed.

The first common electrode 16, the piezoelectric element 17, the electrode plate 18, the insulating plate 19, the electrode plate 20, and the piezoelectric element 21 are pressed and fixed to the recess 15 by the pressing rod 22.
Here, the vortex generator 12, the first common electrode 16, the piezoelectric element 1
7, electrode plate 18, insulating plate 19, electrode plate 20, piezoelectric element 2
1. If the temperature expansion of the pressing rod 22 is made equal, even if the temperature of the measured fluid changes, the initial pressing force does not change, so that there is no problem.

[0013]

However, in such an apparatus, a high pressure-resistant mechanism is required so that the apparatus can be used for a high static pressure measurement fluid, and the structure becomes complicated and expensive. Become. Also, the measurement signal becomes smaller, and S
/ N ratio deteriorates. Further, when there is a gap between the pipe 10 and the vortex generator 12 and dust or the like is interposed, the magnitude of the measurement signal suddenly changes, and there is a problem in reliability.

The present invention solves this problem. An object of the present invention is to provide an inexpensive vortex flowmeter which has good sensitivity to lift, can detect vortex signals stably and reliably even under high static pressure, has a good S / N ratio, and is inexpensive.

[0015]

In order to achieve this object, the present invention provides: (1) a vortex generator inserted into a measurement pipe through which a measurement fluid flows, and the vortex generator acting on a force receiving body by Karman vortex; In a vortex flowmeter for measuring a flow rate by detecting an alternating force, a main body unit in which the force receiving element and at least a joint portion of the measurement pipe to which the force receiving element is joined is integrally formed from the beginning; A thin-walled annular pressure seal fulcrum body formed around at least one of the joints of the pipe and the force-receiving body, and a pressure seal fulcrum attached to the force-receiving body; And a backup plate for backing up the pressure seal fulcrum body by contacting one surface with a thin annular surface of the pressure seal fulcrum body so as to prevent the measurement fluid from being deformed by static pressure. Vortex flow meter. (2) A force bar having one end connected to one end of the force receiving member, and a piezoelectric element provided between the other end of the force bar and the measurement pipe. A vortex flowmeter according to claim 1. (3) The vortex according to claim 1, further comprising a strain plate connected to one end of the force receiving body and having both ends fixed to the measurement pipe, and a strain gauge provided on the strain plate. Flowmeter. (4) A main unit made of a high-grade material comprising only the force receiving member welded and fixed to the measurement pipe and the vicinity of the measurement pipe to be joined to the force receiving body. The vortex flowmeter according to claim 1 or claim 2 or claim 3. (5) A counterweight provided on the force receiving member outside the pressure seal fulcrum so as to prevent occurrence of an error due to vibration of the force receiving member itself. The vortex flowmeter according to claim 2, 3, or 4. It is what constituted.

[0016]

In the above arrangement, a vortex having a frequency proportional to the flow velocity is generated downstream of the vortex generator placed perpendicular to the flow of the measurement fluid. The generation of the vortex induces a vortex pressure, and the force receiver receives an alternating lift in a direction perpendicular to the flow. By measuring the frequency of the alternating lift, the flow rate of the measurement fluid, and thus the flow rate of the measurement fluid, can be measured. Hereinafter, a detailed description will be given based on embodiments.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view of a main part of an embodiment of the present invention, FIG. 2 is a sectional side view of FIG. 1, and FIG.
FIG. 4 is a sectional view taken along line BB of FIG.

Reference numeral 31 denotes a main body unit in which a force receiving body 32 and at least a joint portion of a measuring pipe 33 to which the force receiving body 32 is joined are integrally formed from the beginning. in this case,
Not only the joint of the measurement pipe 33 but also the measurement pipe 33
The whole and the force receiving body 32 are integrally formed.

Reference numeral 34 denotes a second connection between the measurement pipe 33 and the force receiving body 32.
It is a thin annular pressure seal fulcrum provided around at least one of the force receiving members 32 at a joint portion at a location. In this case, a pressure seal fulcrum body 34 is provided at two joints. The pressure seal fulcrum body 34 can be easily formed by, for example, cutting from an integral casting of the measuring pipe 33 and the force receiving body 32.

Reference numeral 35 is attached to the force receiving body 32, and is provided on one surface of the thin annular surface of the pressure seal fulcrum 34 so as to prevent the pressure seal fulcrum 34 from being deformed by the static pressure of the measurement fluid F _Lo. Is a backup plate that contacts and backs up the pressure seal fulcrum body 34.

Reference numeral 36 denotes a force bar having one end connected to the backup plate 35. In this case, the backup plate 35 and the force bar 36 are integrally formed.

Reference numeral 37 denotes a piezoelectric element provided between the other end of the force bar 36 and the measurement pipe 33. In this case, it is connected to the measurement pipe 33 via the piezoelectric element base 38. An electronic circuit 39 processes a signal of the piezoelectric element 37.

In the above configuration, the flow of the measurement fluid F _LO
A vortex having a frequency proportional to the flow velocity is generated downstream of the vortex generator placed at right angles to. Due to the generation of the vortex, a vortex pressure is induced, and the force receiving body 32 alternately lifts F _{a in a} direction perpendicular to the flow.
Receive.

The force receiving body 32 is supported by a pressure seal fulcrum body 34. FIG. 5 shows this in terms of material dynamics. The force receiving body 32 is a support beam at both ends supported by a pressure seal fulcrum body 34.

[0025] Beams that have undergone alternating lift F _a is deformed as shown in FIG. When the displacement of the tip of the force bar 36 is received by the piezoelectric element 37, an alternating force is generated in the piezoelectric element 37,
A signal equal to the vortex frequency is obtained.

As shown in FIG. 7, the pressure seal fulcrum body 34 has a central portion rigidly connected to the force receiving body 32, and a force に applied to the pressure seal fulcrum body 34 by the static pressure p.
p is the force F ₁ generated in the force receiving body 32 and the pressure seal fulcrum 3
4 is supported by a force f generated on the outer peripheral portion. That is, F
₁ + f = Σp.

Since the force receiving member 32 supports the force generated by the pressure seal fulcrum member 34 due to the internal pressure p, as shown in FIG. 8, the strength of the pressure seal fulcrum member 34 has a width b and a thickness t.
The strength of a thin plate subjected to a distributed load of By fixing both ends of the force receiving body 32 to the pressure seal fulcrum body 34, the force receiving body 32 can be used as a member for supporting the force received by the pressure seal fulcrum body 34.

Here, in order to form a fulcrum having a small rotational rigidity, the pressure seal fulcrum body 34 must be formed as a thin circular ring. However, when the internal pressure is high and the static pressure is too small, it is broken. In the present invention, as shown in FIG.
4 was realized.

The outer diameter of the thin annular ring of the pressure seal fulcrum body 34 is D ₁ , the inner diameter is d, and the outer diameter of the backup plate 35 is D ₂
And Pressure applied to a circular ring formed by D ₂ and d, since the backup plate 35 is subjected, the pressure related to the bending applied to the pressure seal fulcrum member 34, (D ₁ -D ₂₎ /
2 = C is the pressure applied to the ring formed.

If C is reduced, the breakdown voltage increases. When an alternating lift F _a is applied, the pressure seal fulcrum 34, as shown in FIG. 10, but must rotate, the length of the thin involved in rotation (width) rather than C, (D ₁ -d) / 2 = e
Therefore, the rotational rigidity can be reduced. Therefore, it is possible to increase the sensitivity to the lift while securing the pressure resistance.

The rotation of the force receiving body 32 and the backup plate 35 with respect to the pressure seal fulcrum 34 is performed by the piezoelectric element 37.
Therefore, there is no need to make a large rotation, and the backup mechanism can function effectively.

The displacement of the tip of the force bar 36 is stopped by a rigid piezoelectric element 37, and the force receiving body 32 is not substantially displaced. Therefore, almost no stress is generated in the pressure seal fulcrum body 34 due to the displacement.

As a result, (1) Since the pressure seal fulcrum member 34 integrally formed is provided in the gap between the peripheral surface of the columnar force receiving member 32 and the measurement pipe 33, the measurement fluid F having a high static pressure is provided. from during _LO, stable alternating lift F _a that occurs force receiving member 32, reliably, measuring tubes 3
(3) A vortex flowmeter which can be taken out is obtained.

[0034] (2) pressure seal fulcrum member 34, the central portion is supported by the force receiving member 32 of the rigid body, because it is supported around the measuring tube 33, the measuring fluid F _LO of the high static pressure Also,
It can be a thin fulcrum.

Accordingly, since the rotation spring constant of the pressure seal fulcrum body 34 can be reduced, a signal which can be taken out through the force receiving body 32 can be increased, and a vortex flowmeter which can increase the S / N ratio can be obtained.

(3) When the diameter of the measuring pipe 33 is increased, the force applied to the thin circular ring of the pressure seal fulcrum body 34 is increased by the static pressure, and the thickness of the thin circular ring must be increased. When the wall thickness is increased, the pressure seal fulcrum body 34
Has a large rotation spring constant, and the sensitivity to lift decreases.

In the present invention, since the pressure seal fulcrum body 34 is backed up by the backup plate 35, it is possible to cope without increasing the thickness of the thin circular ring. Therefore, the rotation spring constant of the pressure seal fulcrum body 34 can be kept small, and a vortex flowmeter having high sensitivity to the lifting force can be obtained.

(4) Since the pressure seal fulcrum body 34 is formed on the inner wall surface of the measurement pipe 33, the measurement pipe 33 has no gaps, holes, etc., and there is a possibility that solid matter is deposited or clogged. And a highly reliable vortex flowmeter can be obtained. In particular, a vortex flowmeter suitable for a sanitary plant is obtained.

(5) Since the pressure seal fulcrum body 34 can be easily formed by cutting or the like from an integral casting of the measuring pipe 33 and the force receiving body 32, pressure sealing means such as welding, an O-ring seal, etc. Processing is not required, and a vortex flowmeter capable of realizing an inexpensive and reliable pressure sealing mechanism can be obtained.

If the piezoelectric element 36 is used as the detection sensor, the piezoelectric element 36 does not require a power source, and energy can be saved.

FIG. 11 is an explanatory diagram of a main part configuration of another embodiment of the present invention. In this embodiment, the pressure seal fulcrum 3
Reference numeral 4 denotes a vortex flowmeter provided in a single unit. Although it can be made cheaply, the output signal is small.

FIG. 12 is an explanatory view of a main part of another embodiment of the present invention, and FIG. 13 is a plan view of FIG. In the figure, 4
Reference numeral 1 denotes a strain plate connected to the other end of the force bar 36 and having both ends fixed to the measurement pipeline 33. In this case, it is fixed via the strain plate base 42. Reference numeral 43 denotes a strain gauge provided on the strain plate 41.

In this case, the strain plate 41 is provided with a thin-walled strain-generating portion 45 by a slit 44 in a slightly thick plate.
A strain gauge 43 deposited on the strain generating section 45 is formed. Since strain gauges are generally easy to form, an inexpensive vortex flowmeter can be obtained.

FIG. 14 is an explanatory view of a main part configuration of another embodiment of the present invention. In this embodiment, 51 is a force receiving body 54.
And a main unit consisting only of a joint 55 in the vicinity of the measuring pipe 52 to which the force-receiving body 54 is joined. The main unit 51 is made of a high-grade material, and is fixed to the measuring pipe 52 by welding 53.

For example, a corrosion-resistant material,
When a high-grade material such as a high-strength material or a heat-resistant material is required, only a necessary minimum portion can be made of the high-grade material, so that an inexpensive vortex flowmeter can be obtained.

FIG. 15 is an explanatory diagram of a main part configuration of another embodiment of the present invention. In the figure, reference numerals 61 and 62 denote counterweights provided on the force receiving member 32 outside the pressure seal fulcrum member 34 so as to prevent an error due to vibration of the force receiving member 32 itself.

When the pipeline vibration or the like is applied in the same direction as the alternating lift due to the vortex, the mass M ₁ of the force receiving body 63 generates a force of M ₁ a. Here, a represents acceleration. This force is indistinguishable from lift, and therefore results in an error in the measured value.

Therefore, by attaching the masses M ₂ and M ₃ of the counterweights 61 and 62 to the outside of the pressure seal fulcrum member 34, a force that cancels out the force generated by the mass M ₁ of the force receiving member 32 is generated. Can be done. Therefore, a vortex flowmeter having improved vibration noise resistance can be obtained. In addition,
In the embodiment of FIG. 15, the counter weights 61 and 62 are
Although it is arranged at both ends of the force receiving body 32, it goes without saying that it may be arranged at one side.

In the above-described embodiment, the vortex flowmeter which is formed separately from the vortex generator and the power receiving bodies 32 and 54 has been described. However, the vortex generator and the power receiving bodies 32 and 54 are described. Needless to say, the present invention is also applied to a vortex flow meter having an integral type.

[0050]

As described in detail above, according to the first aspect of the present invention, (1) the pressure integrally formed from the beginning between the peripheral surface of the columnar force receiving member and the measuring pipe. Since the seal fulcrum body was provided,
A vortex flowmeter capable of stably and reliably taking out the alternating lift generated in the force receiving member from the measurement fluid of high static pressure out of the measurement pipe can be obtained.

(2) The pressure seal fulcrum body is supported at its center by a rigid force receiving member and at its periphery by a measurement pipe, so that it has a thin fulcrum even for a high static pressure measurement fluid. It can be.

Accordingly, since the rotation spring constant of the pressure seal fulcrum can be reduced, a signal which can be taken out via the force receiving member can be increased, and a vortex flowmeter which can increase the S / N ratio can be obtained.

(3) When the diameter of the measuring pipe becomes large, the force applied to the thin circular ring of the pressure seal fulcrum body increases due to the static pressure, and the thickness of the thin circular ring must be increased. When the wall thickness is increased, the rotation spring constant of the pressure seal fulcrum body is increased, and the sensitivity to lift is reduced.

In the first aspect, the pressure seal fulcrum body is backed up by the backup plate, so that it is possible to cope without increasing the thickness of the thin circular ring. Therefore, the rotary spring constant of the pressure seal fulcrum body can be kept small, and a vortex flowmeter having high sensitivity to the lifting force can be obtained.

(4) Since the pressure seal fulcrum body is formed on the inner wall surface of the measuring pipe, there is no gap, hole, etc. in the measuring pipe, and there is no danger of solids accumulating and clogging. A highly reliable vortex flowmeter can be obtained. In particular, a vortex flowmeter suitable for a sanitary plant is obtained.

(5) Since the pressure seal fulcrum can be easily formed by cutting or the like from an integral casting of the measuring pipe and the force receiving member, welding, pressure sealing means such as an O-ring seal, and processing are unnecessary. As a result, a vortex flowmeter capable of realizing an inexpensive and reliable pressure sealing mechanism can be obtained.

According to the second aspect of the present invention, the piezoelectric element does not require a power source and can save energy.

According to the third aspect of the present invention, the strain gauge comprises:
Generally, it is easy to form, so that an inexpensive vortex flowmeter can be obtained.

According to the fourth aspect of the present invention, when a high-grade material such as a corrosion-resistant material, a high-strength material, or a heat-resistant material is required for the force receiving member, only the necessary minimum portion is made of the high-grade material. Since it can be configured, an inexpensive vortex flowmeter can be obtained.

According to the fifth aspect of the present invention, the counterweight can generate a force that cancels the force based on the vibration noise, so that a vortex flowmeter with improved vibration noise resistance can be obtained.

Therefore, according to the present invention, it is possible to realize an inexpensive vortex flowmeter which has good sensitivity to lift, can stably and reliably detect a vortex signal even under a high static pressure, has a good S / N ratio, and has a low S / N ratio. Can be done.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a main part configuration of an embodiment of the present invention.

FIG. 2 is a side sectional view of FIG.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a sectional view taken along line BB of FIG. 2;

FIG. 5 is an operation explanatory diagram of FIG. 1;

FIG. 6 is an operation explanatory diagram of FIG. 1;

FIG. 7 is an operation explanatory diagram of FIG. 1;

FIG. 8 is an operation explanatory diagram of FIG. 1;

FIG. 9 is an operation explanatory diagram of FIG. 1;

FIG. 10 is an operation explanatory diagram of FIG. 1;

FIG. 11 is an explanatory view of a main part configuration of another embodiment of the present invention.

FIG. 12 is an explanatory view of a main part configuration of another embodiment of the present invention.

FIG. 13 is a plan view of FIG.

FIG. 14 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

FIG. 15 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

FIG. 16 is an explanatory diagram of a configuration of a conventional example generally used in the related art.

17 is an explanatory diagram of a main part configuration of a conversion unit in FIG. 16;

FIG. 18 is an operation explanatory diagram of FIG. 16;

FIG. 19 is an operation explanatory diagram of FIG. 16;

[Explanation of symbols]

 Reference Signs List 31 main unit 32 force receiving body 33 measuring pipe line 34 pressure seal fulcrum body 35 backup plate 36 force bar 37 piezoelectric element 38 piezoelectric element base 41 strain plate 42 strain plate base 43 strain gauge 44 slit 45 strain generating part 51 body unit 52 measurement Pipe line 53 Welding 54 Passive element 55 Nearby joint 61 Counterweight 62 Counterweight

Claims (5)

[Claims] 1. A vortex flowmeter, comprising: a vortex generator inserted into a measurement pipe through which a measurement fluid flows; And a main body unit in which at least a joint portion of the measurement pipe to which the force receiving body is joined is integrally formed from the beginning; and at least one of the two joining portions of the measurement pipe and the force receiving body. A thin annular pressure seal fulcrum formed around a force element; and a pressure seal fulcrum attached to the force receiving element such that the pressure seal fulcrum can be prevented from being deformed by the static pressure of the measurement fluid. A vortex flowmeter, comprising: a backup plate for backing up the pressure seal fulcrum body, one surface of which is in contact with the surface of the thin annular body. 2. A force bar having one end connected to the other surface of the backup plate, and a piezoelectric element provided between the other end of the force bar and the measurement pipe. The vortex flowmeter according to claim 1, wherein 3. A force bar having one end connected to the other surface of the backup plate, a strain plate connected to the other end of the force bar and both ends fixed to the measurement pipe, and provided on the strain plate. The vortex flowmeter according to claim 1, further comprising a strain gauge provided. 4. A main unit made of a high-grade material, comprising only a force receiving member fixedly welded to the measuring pipe and a joining portion near the measuring pipe to be joined to the force receiving body. The vortex flowmeter according to claim 1, 2 or 3, wherein 5. The apparatus according to claim 1, further comprising a counter weight provided on the force receiving member outside the pressure seal fulcrum so as to prevent occurrence of an error due to vibration of the force receiving member itself. A vortex flowmeter according to claim 2 or claim 3 or claim 4.