JP2013148416A - Vortex flowmeter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vortex flowmeter including means for removing a foreign matter stuck to a vortex generator.SOLUTION: A vortex flowmeter for measuring flow velocity/flow rate by detecting variation of alternate lifting force caused by Karman vortex generated by a vortex generator 12 includes a foreign matter removing member 49 having a hole 12a whose center part is formed similarly to a cross-sectional shape of the vortex generator 12 and foreign matter removing member driving means 45 for sliding the foreign matter removing member 49 into which the vortex generator 12 is inserted along the vortex generator.

Description

  The present invention relates to a vortex flowmeter provided with means for removing foreign substances adhering to a vortex generator.

  FIG. 3A is a diagram for explaining the configuration of a conventional vortex flowmeter that is generally used. FIG. 3B (A, B, C) and FIG. 3C (A, B) are FIG. FIG. 3A is an explanatory diagram of the operation, and FIG. 3C is an electric circuit diagram of FIG.

  In these drawings, reference numeral 10 denotes a conduit through which the measurement fluid FL flows. The cylindrical nozzle 11 is provided at a right angle to the pipe line 10. The vortex generator 12 is inserted into the pipe 10 at a right angle with a gap from the nozzle 11 and has a trapezoidal cross section.

  One end of the vortex generator 12 is supported on the pipe line 10 by a screw 13, and the other end is fixed to the nozzle 11 by a flange portion 14 by screws or welding. The concave portion 15 is provided on the flange portion 14 side of the vortex generator 12.

  In the recess 15, all the first common electrodes 16, the piezoelectric elements 17, the electrode plates 18, the insulating plates 19, the electrode plates 20, and the piezoelectric elements 21 made of all genera are arranged in a sandwich from the bottom. It is pressed and fixed by a press rod 22 made from all genera. Further, a lead wire 23 is drawn from the electrode plate 18 and a lead wire 24 is drawn from the electrode plate 20 to terminals A and B, respectively.

  The piezoelectric elements 17 and 21 are polarized in the opposite directions on the left and right sides of the piezoelectric elements 17 and 21 with respect to the paper surface, and generate charges having opposite polarities in the upper and lower electrodes with respect to the stress in the same direction. To do.

  The electric charge generated in the piezoelectric element 17 is obtained between the terminal A connected to the electrode plate 18 and the pipe line 10 connected via the first common electrode 16, and the electric charge generated in the piezoelectric element 21 is It is obtained between the terminal B connected to the electrode plate 20 and the pipe line 10 connected to the pressing rod 20.

The charges generated in the two electrode plates 18 and 20 are input to the 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 rate signal.

This flow rate signal is converted into a current output, for example, and transmitted to a 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 measurement fluid FL flows into the pipe 10, the vortex generator 12 is vibrated by the Karman vortex in the direction indicated by the arrow F. Due to this vibration, a stress distribution as shown in FIG. 3B (a) and a reverse stress distribution are repeated in the wrinkle generator 12.

  Each of the piezoelectric elements 17 and 21 has a charge of 10 Q and a repetition of Q corresponding to the signal stress having the vortex circumference shown in FIG. In FIGS. 3B and 3C, for convenience of explanation, the electrode plate 18 or 21 is divided into two left stones with respect to the paper surface, and one of the upper and lower electrodes is the first common. It corresponds to the electrode 16 or the pressing rod 22.

On the other hand, the pipe line 10 also generates pipe vibration that becomes noise.
This pipe vibration is
(1) Drag direction in the same direction as the fluid flow,
(2) Lift direction perpendicular to the fluid flow,
(3) Divided into three components in the longitudinal direction of the vortex generator.

  Among these, the stress distribution with respect to the vibration in the drag direction is as shown in (b) of FIG. 3b, and the positive and negative charges are canceled out within the l electrodes, and no noise charge is generated. Further, as shown in FIG. 3B (c), the vibration in the longitudinal direction is canceled out within the electrode, and no noise charge is generated as in the drag direction.

However, the vibration in the lift direction has the same stress distribution as the signal stress, and noise charges are generated.
Therefore, in order to eliminate this noise charge, the following calculation is executed.

  If the electric charges of the piezoelectric elements 17 and 21 are Q1 and Q2, the signal components are S1 and S2, the noise components in the lift direction are N1 and N2, and the polarization is reversed in the piezoelectric elements 17 and 21, Q1 and Q2 are as follows: Indicated.

Q1 = S1 + N1
-Q2 = -S2-N2
However, the vector directions of S1 and S2 and N1 and N2 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. 3C (this diagram shows the relationship between the noise in the lift direction and the bending moment of the vortex generator with respect to the signal). It has become.

  Therefore, as shown in FIG. 3c (d), when the output of the charge amplifier 25 on the piezoelectric element 17 side is added by the adder 28, the charge on the piezoelectric element 21 side is multiplied by N1 / N2 together with the volume 27. When summed with the output of the amplifier 26,

Q1-Q2 (N1 / N2)
= S1-S2 (N1 / N2)
Next, the pipe 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, if the temperature expansion of the vortex generator 12 and the first common electrode 16, the piezoelectric element 17, the electrode plate 18, the insulating plate 19, the electrode plate 20, the piezoelectric element 21, and the pressing rod 22 is equal, the measurement fluid Even if the temperature changes, the initial pressing force does not change, so there is no problem.

  The following patent documents are known as prior art of such vortex flowmeters.

JP 2002-214006 A JP 2003-322553 A

  By the way, in the above-described conventional example, there is a problem that a vortex waveform is disturbed due to foreign matters adhering to the vortex generator, resulting in a large measurement error.

  The present invention has been made in order to solve the above-described problem. By removing the foreign matter adhering to the vortex generator by sliding the foreign substance removal member along the vortex generator, the vortex flowmeter having no error is obtained. It is intended to be realized.

In the vortex flowmeter of the present invention, in claim 1,
In a vortex flowmeter that measures the flow velocity by detecting the variation of alternating lift due to Karman vortex generated by the vortex generator,
Comprising a foreign matter removing member having a hole having a hole formed in a central portion similar to the cross-sectional shape of the vortex generator;
Foreign matter removing member driving means is provided for sliding the foreign matter removing member into which the vortex generating body is inserted along the vortex generating body.

In claim 2, in the vortex flowmeter according to claim 1,
A hole formed similar to the cross-sectional shape of the vortex generator has a cross-section of the vortex generator to the extent that it can maintain a normal and error-free function as a vortex flowmeter when slid along the vortex generator. It is characterized by being formed slightly larger.

In claim 3, in the vortex flowmeter according to claim 1 or 2,
The foreign matter removing member is made of fluororubber, metal, or plastic resin.

In claim 4, in the vortex flowmeter according to any one of claims 1 to 3,
The foreign matter removing member driving means includes a rotating shaft having a screw formed on a main shaft of a motor, a screw formed at a central portion and engaged with a screw of the rotating shaft, and the rotation is constrained by rotation of the motor. It consists of a combination of blocks that move inside.

In claim 5, in the vortex flowmeter according to any one of claims 1 to 4,
The foreign matter removing member is configured to slide along the vortex generator every predetermined time or at an arbitrary time according to the occurrence state of the foreign matter.

  According to the vortex flowmeter of the present invention, the vortex flowmeter is provided with the foreign matter removal member driving means for sliding the foreign matter removal member into which the vortex generator is inserted along the vortex generator, so that the vortex flowmeter is normal and error free. Can be realized.

It is principal part sectional drawing which shows the structure of the vortex flowmeter of this invention. It is an expanded sectional view of the part enclosed with the dotted line of FIG. It is principal part sectional drawing and operation | movement explanatory drawing of a general vortex flowmeter.

  1A to 1D are explanatory views showing an embodiment of the vortex flowmeter of the present invention. FIG. 1A is a cross-sectional view of the main part, and FIG. 1B is a foreign object shown in FIG. Front view (b), plan view (b), bottom view (c), and FIG. 1 (c) of the removing member (rubber) are states when a vortex generator is inserted into the foreign matter removing means shown in FIG. 1 (a). FIG. FIG. 1D is a cross-sectional view of the main part showing a state in which the foreign substance removing member slides and is displaced by the foreign substance removing member driving means (motor).

The only difference from the conventional example is that a foreign matter removing member that slides the vortex generator and a drive means for the foreign matter removing member are provided.
In FIG. 1, the nozzle 11 is fabricated in the same configuration as in the conventional example. Reference numeral 10 is a pipe line, and 12 is a vortex generator. Reference numeral 44 denotes a support member having a cylindrical cavity 44 a fixed at one end to the pipe line 10 and closed at the other end, 45 is a driving means (motor) fixed to the bottom of the cavity 44 a, and 46 extends from the main shaft of the motor 45. The rotating shaft has a male screw formed on the outer periphery.

Reference numeral 47 denotes a block in which a female screw that engages with the rotation shaft 46 is formed at the center. The block 47 is formed so as to restrain the rotation in the cavity 44a and is slidable in the cavity.
1B is a front view (A), a plan view (B), and a bottom view (C) of the foreign matter removing member (rubber) shown in FIG.

  FIG. 1C is a cross-sectional view showing a state when the vortex generator 12 is inserted into the vortex generator insertion hole 49a formed in the foreign matter removing member (rubber) 49 shown in FIG. Is slightly larger than the cross-section of the vortex generator 12 (for example, 0.01 to 0.00) to such an extent that a normal and error-free function as a vortex flowmeter can be maintained when sliding along the vortex generator 49 to remove foreign matter. 1 mm).

  Reference numeral 48 denotes a pair of support shafts having one end fixed to the block 47, and the other end fixed to the foreign matter removing member 49, and the other end side fixed to the foreign matter removing member 49 prevents intrusion of fluid flowing through the conduit. Therefore, it is sealed by an O-ring 50. Reference numeral 41 denotes a disk for pressing the O-ring with a predetermined pressure. One end of the rotating shaft 46 is inserted into a bearing 43 disposed in a fixing hole 42 (see FIG. 2) formed on the outer periphery of the pipe line 10 so that it can rotate smoothly.

Next, the operation of the vortex flowmeter of the present invention will be described.
FIG. 1A shows a state in which the foreign matter removing member 49 is located on the support member 44 side (downward in the drawing).
FIG. 1D shows a state in which the rotating shaft 46 rotates simultaneously with the rotation of the motor 45 and the block 47 moves upward with the rotation restricted, and at the same time the foreign matter removing member 49 moves upward along the vortex generator 12. Is shown. By this movement, the foreign matter attached to the vortex generator 12 is removed.

  The driving means 45 is controlled to rotate in the forward and reverse directions by a control means (not shown), and is driven according to a predetermined time depending on the state of adhesion of foreign matter contained in the fluid to the vortex generator. The movement of the foreign matter removing member 49 up and down may be performed a plurality of times.

Here, the adhesion state of the vortex generator is diagnosed from a change or abnormality of the vortex generation frequency by a diagnostic means (not shown). Then, the foreign matter removing member is driven when it can be estimated from the diagnosis result that there is a certain level of contamination. In this case, it is assumed that the vortex flowmeter holds the state before entering the drive operation of the foreign matter removing member. While the foreign matter removal driving is being performed, a message indicating the working state is transmitted to the upper level by communication means (not shown).
Note that the rotation of the motor 45 may be manually driven by an operator without depending on the control means.

  As described above, according to the vortex flowmeter of the present invention, the vortex flowmeter is driven according to a predetermined time depending on the state of adhesion of the foreign matter contained in the fluid to the vortex generator, so that the foreign matter attached to the vortex generator is removed. Therefore, a normal and error-free vortex flowmeter can be realized.

The above description merely shows a specific preferred embodiment for the purpose of explanation and illustration of the present invention. In the present invention, the rubber is used as the foreign matter removing member. However, other members such as metal or plastic resin may be used.
Therefore, the present invention is not limited to the above-described embodiments, and includes many changes and modifications without departing from the essence thereof.

DESCRIPTION OF SYMBOLS 10 Pipe line 11 Nozzle 12 Vortex generator 12a Vortex generator insertion hole 13 Screw 14 Flange part 15 Recess 16 First common electrode 17, 21 Piezoelectric element 18 Electrode plate 19 Insulating plate 20 Electrode plate 22 Press plate 23, 24 Lead wire 25 , 26 Charge amplifier 27 Volume 28 Adder 41 Disc 43 Bearing 44 Support member 44a Cavity 45 Drive means (motor)
46 Rotating shaft 47 Block 48 Support shaft 48a Support shaft insertion hole 49 Foreign matter removing means (rubber)
50 O-ring

Claims (5)

In a vortex flowmeter that measures the flow velocity by detecting the variation of alternating lift due to Karman vortex generated by the vortex generator,
Comprising a foreign matter removing member having a hole having a hole formed in a central portion similar to the cross-sectional shape of the vortex generator;
A vortex flowmeter comprising: a foreign substance removing member driving unit that slides the foreign substance removing member into which the vortex generator is inserted along the vortex generator.   A hole formed similar to the cross-sectional shape of the vortex generator has a cross-section of the vortex generator to the extent that it can maintain a normal and error-free function as a vortex flowmeter when slid along the vortex generator. The vortex flowmeter according to claim 1, wherein the vortex flowmeter is slightly larger.   3. The vortex flowmeter according to claim 1, wherein the foreign matter removing member is made of fluororubber, metal, or plastic resin.   The foreign matter removing member driving means includes a rotating shaft having a screw formed on a main shaft of a motor, a screw formed at a central portion and engaged with a screw of the rotating shaft, and the rotation is constrained by rotation of the motor. The vortex flowmeter according to claim 1, comprising a combination of blocks that move inside.   5. The foreign matter removing member is configured to slide along the vortex generator at a predetermined time or at an arbitrary time according to the occurrence state of the foreign matter. Vortex flowmeter.

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