JP2008107171A - Vortex flowmeter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vortex flowmeter improved in measuring precision and capable of reducing the manufacturing cost. <P>SOLUTION: The vortex flow meter for measuring the flow speed and flow rate by detecting the variation of the alternative pressure caused by the Karman vortex is characteristically provided with the downstream side measuring conduit connected with the upstream side measuring conduit of specific length, the vortex generator integrally formed from the first, and the vortex detector provided down stream of the vortex generator. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vortex flowmeter with improved measurement accuracy and reduced manufacturing costs.

  Prior art documents related to vortex flowmeters include the following.

JP 2002-048610 A

  FIG. 4 is an explanatory diagram of a cross-sectional configuration of a conventional example that is generally used conventionally. FIG. 5 is a cross-sectional view showing a state cut along the line II-II shown in FIG. FIG. 6 is a cross-sectional view in which a part of the state cut along line III-III shown in FIG. 4 is omitted. FIG. 7 is an enlarged cross-sectional view of the IV portion shown in FIG. FIG. 8 is an enlarged cross-sectional view of a V portion shown in FIG.

The vortex flowmeter 1 is a device that measures the flow rate of the fluid F by generating a vortex in the measurement tube 2 through which the fluid F flows.
As shown in FIGS. 4 and 5, the vortex flowmeter 1 includes a measurement tube 2, a vortex generator 3, a lift detection unit 4, a circuit board 5, and a cover 6.

The measuring tube 2 is a conduit through which the fluid F flows.
For example, a fluid F such as gas, liquid, or vapor passes through the measurement tube 2 in the direction of the arrow in the figure.
The measuring tube 2 is integrally formed of synthetic resin and is manufactured by an injection molding machine or the like.
The measuring tube 2 is preferably integrally formed of a fluororesin such as a tetrafluoroethylene resin (trade name Teflon) so that the flow rate of pure water, chemical solution, or the like can be measured.
The measuring tube 2 has an inner diameter of about 6 mm or 12 mm. A throat portion 2 a is formed on the inner peripheral portion of the measurement tube 2.

The throat portion 2a is a portion formed in a venturi shape so that a minute flow rate near zero flow rate can be detected with high accuracy.
As shown in FIG. 5, the cross-sectional shape of the throat portion 2 a is formed in a horizontally long shape with a width dimension longer than a height dimension in order to prevent a decrease in the flow rate and ensure a uniform flow rate.
As shown in FIG. 8, the throat portion 2a is formed with two plane portions 2b and 2c which are parallel to each other and arcuate curved surface portions 2d and 2e for increasing the lift acting on the vortex generator 3. ing.

The vortex generator 3 is a columnar object that generates a vortex in the measurement tube 2.
As shown in FIGS. 4 to 8, the vortex generator 3 is formed integrally with the measurement tube 2 in the throat portion 2a, and the upper end portion is the inner periphery of the measurement tube 2 so that the detection sensitivity of the vortex signal is increased. It is a cantilever beam structure that is cantilevered by the part.
The vortex generator 3 is integrally formed of the same material as that of the measurement tube 2 and is manufactured by an injection molding machine or the like, similar to the measurement tube 2.

The vortex generator 3 preferably has a constant position (peeling point) where Karman vortices are alternately peeled and flowed, stably generate vortices in a wide range of flow rates, and have a constant Strouhal number. Thus, a shape having a sharp edge (prism) is preferable.
The cross-sectional shape of the vortex generator 3 is preferably a trapezoid as shown in FIG. 8, and may be a triangle, a quadrangle, or a T-shape that is a modification thereof.

Lift force (alternating force) acts on the vortex generator 3 by the generation and release of vortices in a direction perpendicular to the flow.
As shown in FIGS. 7 and 8, the vortex generator 3 is formed with a storage portion 3 a and an insertion port 3 b.

The storage unit 3 a is a recess that stores the lift detection unit 4 inside the vortex generator 3.
The insertion port 3 b is an opening for inserting and storing the lift detection unit 4 in the storage unit 3 a, and is formed on the outer peripheral side of the measurement tube 2.
The storage portion 3 a and the insertion port 3 b are integrally formed with the vortex generator 3.

The lift detection unit 4 is a device that detects the lift acting on the vortex generator 3.
As shown in FIGS. 4 to 7, the lift detection unit 4 is housed inside the vortex generator 3.
The lift detection unit 4 is a vortex detection sensor that detects lift acting on the vortex generator 3 as a pressure change.

The lift detection unit 4 is, for example, a piezoelectric element that outputs an electric signal corresponding to a pressure change acting on the vortex generator 3, or a strain that outputs an electric signal corresponding to a strain caused by a pressure change acting on the vortex generator 3. It is an electromechanical transducer such as a gauge.
The lift detection unit 4 is a piezoelectric transducer composed of two thin piezoelectric elements that expand when one contracts, and is a piezoelectric bimorph type that can reduce the influence of vibrations acting on the measuring tube 2. A sensor is particularly preferred.

The circuit board 5 shown in FIG.4 and FIG.5 is a board | substrate comprised by the processing circuit etc. which process the electric signal which the lift detection part 4 outputs.
The circuit board 5 includes a linearize circuit that corrects a non-linear error in a region where the Reynolds number is small and the Strouhal number is not constant.
The cover 6 is a member that protects the circuit board 5. The cover 6 is attached and fixed to the upper part of the measuring tube 2 so as to cover the circuit board 5.

Next, the operation of the conventional vortex flowmeter of FIG. 4 will be described.
When the fluid F flows in the measurement tube 2, the vortex generator 3 releases the vortex, and a force perpendicular to the flow of the fluid F acts on the vortex generator 3 alternately.
When the vortex generator 3 is bent left and right by this force, bending stress acts on the lift detection unit 4, and compressive stress and tensile stress act on the lift detection unit 4.
Since the direction of the stress is reversed every time a vortex is generated, the frequency of the vortex (vortex signal) is detected and the flow rate of the fluid F is measured by counting the direction of the stress.

FIG. 9 is a diagram illustrating the configuration of another conventional example that is generally used.
In this conventional example, a vortex flow meter is formed by connecting a tube 12 for connection from both sides to a vortex flow meter main body 11 made of a pipe-shaped resin material by a resin welding portion 13.

Reference numeral 14 is an upper cover, 15 is a lower cover, 16 is a side cover, and is fixed to the vortex flowmeter main body 11 with screws or the like.
A circuit cover 17 covers the arithmetic circuit 18 fixed to the upper cover 14.
The vortex detector 4 is fixed to the vortex flowmeter main body 11 by resin welding 19.

The conventional apparatus shown in FIG. 9 has the following problems.
The resin tube 12 is welded to both ends of the vortex flow meter main body 11, but when the resin tube 12 is welded to the resin main body 11, the welding performance can be biased by the operator, and the tube 12 is poorly welded. For this reason, the product may become defective.
Moreover, although the jig which fixes the tube 12 is used, there exists a high possibility that the inside of the tube 12 may be damaged at that time, and the product may be defective due to the internal damage of the tube 12.
Therefore, if possible, we want to reduce the number of welds.

  An object of the present invention is to solve the above-described problems, and to provide a vortex flowmeter capable of improving measurement accuracy and reducing manufacturing costs.

In order to achieve such a problem, in the present invention, in the vortex flowmeter of claim 1,
In a vortex flowmeter that detects a change in alternating pressure due to a Karman vortex to measure a flow velocity and a flow rate, a downstream measurement line connected to an upstream measurement line having a predetermined length, and first the upstream measurement line And a vortex detector provided downstream of the vortex generator in the upstream measurement pipe.

In the vortex flow meter according to claim 2 of the present invention, in the vortex flow meter according to claim 1,
The upstream measurement pipe and the downstream measurement pipe are formed of a synthetic resin.

In the vortex flow meter according to claim 3 of the present invention, in the vortex flow meter according to claim 1 or 2,
The upstream measurement pipe and the downstream measurement pipe are formed by injection molding.

In the vortex flowmeter according to claim 4 of the present invention, in the vortex flowmeter according to any one of claims 1 to 3,
The upstream measurement pipe and the downstream measurement pipe are welded by resin welding.

In the vortex flow meter according to claim 5 of the present invention, in the vortex flow meter according to any one of claims 1 to 3,
The upstream measurement pipe and the downstream measurement pipe are welded by butt welding.

In the vortex flow meter according to claim 6 of the present invention, in the vortex flow meter according to any one of claims 1 to 5,
The vortex detector is fixed to the upstream measurement pipe line by resin welding.

In the vortex flowmeter according to claim 7 of the present invention, in the vortex flowmeter according to any one of claims 1 to 6,
The upstream measurement pipe and the downstream measurement pipe are formed of a fluorine resin.

According to claim 1 of the present invention, there are the following effects.
Since there is no pipe joint near the upstream of the vortex generator and the vortex detector of the pipe, the measurement accuracy is improved, the number of connection points is reduced, and manufacturing defects due to defective connection points occur. Since the probability can be reduced, a vortex flowmeter that can reduce the manufacturing cost can be obtained.

According to claim 2 of the present invention, there are the following effects.
Since the upstream side measurement pipe and the downstream side measurement pipe are made of synthetic resin, it is easy to form by synthetic resin molding, and a small and inexpensive vortex flowmeter can be obtained.

According to claim 3 of the present invention, there are the following effects.
Since the upstream measurement pipeline and the downstream measurement pipeline are formed by injection molding, a mass-produced and inexpensive vortex flowmeter can be obtained.

According to claim 4 of the present invention, there are the following effects.
Since the upstream measurement pipeline and the downstream measurement pipeline were welded by resin welding, the probability of manufacturing defects due to resin welding was reduced by reducing the number of resin welding locations compared to the prior art. A vortex flowmeter is obtained.

According to claim 5 of the present invention, there are the following effects.
Since the upstream measurement pipe and the downstream measurement pipe are welded by butt welding, a vortex flowmeter can be obtained in which the welding of the measurement pipe is poor or the risk of product failure due to scratches is further reduced. .

According to claim 6 of the present invention, there are the following effects.
Since the vortex detector is fixed to the upstream measurement pipe line by resin welding, the number of parts can be reduced such that the number of screws for fixing the vortex detector is reduced, so that an inexpensive vortex flowmeter can be obtained.

According to claim 7 of the present invention, there are the following effects.
Since the upstream side measurement line and the downstream side measurement line are made of fluorine resin, a vortex flowmeter having good corrosion resistance and less risk of depositing the measurement fluid is obtained.

Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is an explanatory diagram of the main part configuration of one embodiment of the present invention, FIG. 2 is an explanatory diagram of the main part configuration of FIG. 1, and FIG. 3 is an explanatory diagram of the main part configuration of FIG.
In the figure, configurations with the same symbols as in FIGS. 4 and 9 represent the same functions.
Only the differences from FIGS. 4 and 9 will be described below.

In the figure, the downstream measurement pipeline 22 is connected to an upstream measurement pipeline 21 having a predetermined length.
In this case, the upstream side measurement pipeline 21 and the downstream side measurement pipeline 22 are formed of synthetic resin.
Further, the upstream side measurement pipeline 21 and the downstream side measurement pipeline 22 are formed by injection molding.

Further, the upstream side measurement pipe line 21 and the downstream side measurement pipe line 22 are welded by resin welding at the resin welded portion 23.
Further, the upstream side measurement pipe line 21 and the downstream side measurement pipe line 22 are formed of a fluorine resin.
The vortex generator 24 is formed integrally with the upstream measurement pipe 21 from the beginning.
The vortex detector 25 is provided on the downstream side of the vortex generator 24 in the upstream measurement pipe 21.

In the above configuration, as shown in FIG. 2, the upstream measurement pipe 21 provided with the vortex detector fixing hole 211 and the downstream measurement pipe fixing hole 212 and the upstream measurement pipe 21 are integrated from the beginning. In the injection-molded part of the vortex generator 24 configured as described above, the resin flows at two locations of the gate 213.
In this case, considering the limit of injection molding, the total length is set to 100 mm or less.

As shown in FIG. 3, the vortex detector 25 is inserted into the vortex detector fixing hole 211 of the upstream measurement pipe 21 and fixed by the all-around resin weld 26.
The downstream measurement pipeline 22 is inserted into the downstream measurement pipeline fixing hole 212 of the upstream measurement pipeline and fixed by the entire circumference resin weld 23.
As shown in FIG. 1, the upper cover 14, the lower cover 15, the side cover 16, the circuit cover 17, and the arithmetic circuit 18 are fixed to the assembly parts of the upstream measurement pipeline 21 and the downstream measurement pipeline 22.

As a result,
Since there is no pipe joint near the upstream of the vortex generator 24 and the vortex detector 25 in the pipe, the measurement accuracy is improved, the number of welds on the pipe is reduced by one, and the connection part is defective. Therefore, the probability of occurrence of a manufacturing failure can be reduced, so that a vortex flowmeter capable of reducing manufacturing costs can be obtained.

  Since the upstream side measurement line 21 and the downstream side measurement line 22 are made of synthetic resin, it is easy to form by synthetic resin molding, and a small and inexpensive vortex flowmeter can be obtained.

  Since the upstream side measurement line 21 and the downstream side measurement line 22 are formed by injection molding, a mass-produced and inexpensive vortex flowmeter can be obtained.

  Since the upstream side measurement pipeline 21 and the downstream side measurement pipeline 22 are welded by resin welding, the probability of manufacturing defects due to resin welding is reduced by reducing the number of resin welding locations compared to the prior art. A vortex flowmeter is obtained.

  Since the vortex detector 25 is fixed to the upstream measurement pipe 21 by the resin welding 26, the number of parts can be reduced such that the number of screws for fixing the vortex detector 25 is reduced, so that an inexpensive vortex flowmeter can be obtained. It is done.

  Since the upstream side measurement pipe line 21 and the downstream side measurement pipe line 22 are made of fluorine resin, a vortex flowmeter having good corrosion resistance and a low risk of depositing the measurement fluid is obtained.

  By providing two injection molded product gates 213 in the upstream measurement pipe 21, there is no detachment of the inside of the upstream measurement pipe 21 even in molding with a long overall length, and a vortex flowmeter that can be manufactured stably is obtained. It is done.

  In the above-described embodiment, it has been described that the downstream measurement pipe 22 is inserted into the downstream measurement pipe fixing hole 212 of the upstream measurement pipe and is fixed by the entire circumference resin welding 23. For example, the welding may be performed by butt welding. In short, it is only necessary that the downstream measurement pipeline 22 is fixed to the upstream measurement pipeline 21.

  If the upstream measurement pipe 21 and the downstream measurement pipe 22 are welded by butt welding, there is a vortex flowmeter that further reduces the possibility of poor measurement pipe welding or product failure due to scratches. can get.

The above description merely shows a specific preferred embodiment for the purpose of explanation and illustration of the present invention.
Therefore, the present invention is not limited to the above-described embodiments, and includes many changes and modifications without departing from the essence thereof.

It is principal part structure explanatory drawing of one Example of this invention. It is principal part structure explanatory drawing of FIG. It is principal part structure explanatory drawing of FIG. It is sectional drawing explanatory drawing of the prior art example generally used conventionally. It is sectional drawing which shows the state cut | disconnected by the II-II line | wire shown in FIG. It is sectional drawing which abbreviate | omits and shows the state cut | disconnected by the III-III line | wire shown in FIG. It is sectional drawing which expands and shows the IV part shown in FIG. It is sectional drawing which expands and shows the V section shown in FIG. It is composition explanatory drawing of the other conventional example generally used conventionally.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vortex flowmeter 2 Measuring tube 2a Throat part 2b Plane part 2c Plane part 2d Curved part 2e Curved part 3 Vortex generator 3a Storage part 3b Insertion port 4 Lift detection part 5 Circuit board 6 Cover 7 Vortex flowmeter 8 Lifting action part 9 Lift detection unit 11 Vortex flow meter main body 12 Connecting tube 13 Resin welded part 14 Upper cover 15 Lower cover 16 Side cover 17 Circuit cover 18 Arithmetic circuit 19 Resin welding 21 Upstream measurement pipe 211 Vortex detector fixing hole 212 Downstream Side measurement pipe fixing hole 213 Gate 22 Downstream measurement pipe 23 Resin welded portion 24 Vortex generator 25 Vortex detector 26 Resin weld F Fluid

Claims (7)

In vortex flowmeters that measure the flow velocity flow by detecting the variation of alternating pressure due to Karman vortex,
A downstream measurement line connected to an upstream measurement line having a predetermined length; and
A vortex generator integrally formed from the beginning in the upstream measurement pipeline;
A vortex flowmeter comprising: a vortex detector provided downstream of the vortex generator of the upstream measurement pipe line. The vortex flowmeter according to claim 1, wherein the upstream measurement pipe and the downstream measurement pipe are made of a synthetic resin. The vortex flowmeter according to claim 1 or 2, wherein the upstream measurement pipe and the downstream measurement pipe are formed by injection molding. The vortex flowmeter according to any one of claims 1 to 3, wherein the upstream measurement pipe and the downstream measurement pipe are welded by resin welding. The vortex flowmeter according to any one of claims 1 to 3, wherein the upstream measurement pipe and the downstream measurement pipe are welded by butt welding. The vortex flowmeter according to any one of claims 1 to 5, wherein the vortex detector is fixed to the upstream measurement pipe line by resin welding. The vortex flowmeter according to any one of claims 1 to 6, wherein the upstream measurement pipe and the downstream measurement pipe are formed of a fluorine resin.

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