JP2003207378A - Vortex flowmeter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vortex flowmeter having an improved noise resistance. <P>SOLUTION: The vortex flowmeter detects the variation of an alternating pressure due to a Karman vortex generated from a vortex generation body for measuring the flow velocity/flow rate and comprises a pipeline where a measurement fluid flows, a container provided from the outside of the pipeline on the vortex generation body, a piezoelectric element provided in the container, and a rigidity reducing means provided in the container for reducing the rigidity of the container so that the rigidity in the reaction force direction becomes less than that in the lifted force direction. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vortex flowmeter having improved noise resistance.

[0002]

2. Description of the Related Art FIG. 8 is an explanatory view of a configuration of a conventional example which has been generally used in the past.
No. 8 (Japanese Patent Application No. 1-033256). 9 is a side view of FIG. 8, FIG. 10 is an electric circuit diagram of FIG. 8, and FIG.
13 to 13 are operation explanatory views of FIG.

In the figure, a conduit 10 is a conduit through which the measuring fluid FL flows. The nozzle 11 is provided at a right angle to the pipe line 10 and has a cylindrical shape. The vortex generator 12 is inserted into the conduit 10 at a right angle with a gap kept from the nozzle 11, and has a trapezoidal cross section and a column shape.

One end of the vortex generator 12 is supported by the pipe line 10, and the other end of the vortex generator 12 is fixed to the nozzle 11 at the flange portion 13 by screws or welding via the container 14. Container 14
Are provided on the flange portion 13 side of the vortex generator 12.

In this container 14, a common electrode 15, a piezoelectric element 16, an electrode plate 17, and an insulating plate 18 are arranged in a sandwich form in order from the bottom of the container 14, and the pressing rod 1 manufactured by all kinds is manufactured.
These are pressed and fixed by 9.

Further, from the electrode plate 17, a lead wire 21
Is drawn to the terminal A. The left side and the right side of the piezoelectric element 16 are polarized in opposite directions, respectively, and generate electric charges of opposite polarities in the upper and lower electrodes with respect to stress in the same direction.

The electric charge generated in the piezoelectric element 16 is applied to the electrode plate 1.
It is obtained between the terminal A connected to 7 and the conduit 10 connected via the common electrode 15. The charge generated in the piezoelectric element 16 is input to the charge amplifier 25 to obtain a flow rate signal, as shown in FIG.

The flow rate signal is converted into, for example, a current output and transmitted to the load via the two wires (not shown).
Next, the operation of the vortex flowmeter configured as above will be described with reference to FIGS. 11 to 13.

When the measuring fluid FL flows into the conduit 10,
Vibration due to the Karman vortex is generated in the vortex generator 12 in the direction indicated by the arrow F. This vibration causes the vortex generator 12 to repeat the stress distribution as shown in FIG. 11 and the reverse stress distribution.

In the piezoelectric element 16, charges Q and 1 Q corresponding to the signal stress having the vortex frequency shown in FIG. 11 are repeated. In FIG. 11, for convenience of explanation, the electrode 15 or 17 is divided into two parts on the left and right sides with respect to the paper surface.

On the other hand, in the pipe line 10, pipe line vibration that causes noise is also generated. This pipe vibration is divided into three directions: a drag force in the same direction as the fluid flow, a lift force in a direction perpendicular to the fluid flow, and a longitudinal direction of the vortex generator.

Of these, the stress distribution with respect to the vibration in the drag direction is as shown in FIG. 12, in which the positive and negative charges are canceled in the l electrodes, and noise charges are not generated. Also,
As shown in FIG. 13, the vibration in the longitudinal direction is canceled out in the electrode, and in principle, no noise charge is generated as in the drag direction.

[0013]

However, in such a device, if the polarization states in the two polarization areas are different or the fixed state of the piezoelectric element is not uniform, those noises are canceled by the piezoelectric element alone. It cannot be done and is output as vibration noise. That is, in FIG. 13, if QL ≠ QR, (QL-
QR) remains as noise.

As described above, the vibration noise in the drag direction is
Considering manufacturing variations, it cannot be completely eliminated. Therefore, a method of reducing the stress acting on the piezoelectric element in the drag force direction is adopted.

FIG. 14 is a diagram for explaining the structure of another conventional example which is generally used in the past. For example, US Pat. No. 5,396,81 is used.
No. 0 is shown. FIG. 7 is a structural diagram of a conventional example as an example of a method for reducing stress in the drag direction.

In this embodiment, the vortex signal is transmitted to the pivot member 3.
1 to the post 33 through the pin 32, and the post 3
3 is displaced in the direction of lift according to the vortex signal, and the displacement is detected by a sensor such as a piezoelectric element.

By arranging the pin 32 having rigidity in the drag force direction during the transmission of the signal, it is possible to realize a structure in which the pin 32 bends easily in the lift force direction and is hard to bend in the drag force direction. That is, the noise component in the drag direction is reduced.

In such a conventional example, since the structure is complicated, it is difficult to manufacture and the cost is high.
An object of the present invention is to solve the above problems, and to provide a vortex flowmeter with improved noise resistance.

[0019]

In order to achieve such an object, according to the present invention, in the vortex flowmeter of claim 1, an alternating pressure fluctuation based on a Karman vortex generated by a vortex generator is detected. In a vortex flowmeter for measuring a flow rate, a pipe through which a measurement fluid flows, a container provided on the vortex generator from outside the pipe, a piezoelectric element provided in the container, and a container provided in the container. The container is provided with a rigidity reducing means that reduces the rigidity of the container in the drag direction rather than in the lift direction.

According to a second aspect of the present invention, in the vortex flowmeter for measuring the flow velocity and flow rate by detecting the alternating pressure fluctuation based on the Karman vortex generated by the vortex generator, the pipe through which the measurement fluid flows and the vortex generation. A container provided on the force receiving body provided on the downstream side of the body from the outside of the conduit, a piezoelectric element provided in the container, and the rigidity of the container provided in the container in the drag force direction from the lift force direction. And a rigidity reducing means for reducing rigidity.

According to a third aspect of the present invention, in the Karman vortex flowmeter according to the first or second aspect, as the rigidity reducing means, a slit is used which is cut from both sides in the side surface of the container in the drag direction. The vortex flowmeter according to claim 1 or 2, characterized in that

According to a fourth aspect of the present invention, in the vortex flowmeter according to any one of the first to third aspects, as the rigidity reducing means, the side surface of the container is cut from both sides in a drag force direction to lift force. It is characterized in that a slit having a bottom parallel to the direction was used.

[0023]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below with reference to the drawings. FIG. 1 is an explanatory view of the main configuration of an embodiment of the present invention,
2 is a side view of FIG. 1, FIG. 3 is an explanatory view of parts of FIG. 1, FIG. 4 is a side view of FIG. 3, and FIG. 5 is a view taken along the line AA of FIG.

In the figure, the same symbols as those in FIG. 8 represent the same functions. Only the parts different from FIG. 8 will be described below. In the figure, 14 is a container provided in the vortex generator 12 from the outside of the conduit 10. The piezoelectric element 16 is provided in the container 14. Reference numeral 41 is a rigidity reducing means that is provided in the container 14 and reduces the rigidity of the container 14 in the drag direction rather than in the lift direction.

In this case, on the side surface of the container 14 from both sides,
A slit is used that has a bottom 411 cut from the drag direction and parallel to the lift direction. Center part 41 of container 41
In the state where 2 is connected, the rigidity can be changed by changing the width of the connecting portion.

As a result, the rigidity of the container 41 to which the piezoelectric element 16 is fixed is weakened in the drag direction, so that the stress component in the drag direction can be reduced, and as a result, the vibration resistance in the drag direction is improved. A vortex flowmeter capable of performing is obtained.

FIG. 6 is an explanatory view of the essential structure of another embodiment of the present invention, and FIG. 7 is a side view of FIG. In this embodiment,
Separately from the vortex generator 12, a vane 51, which is a force receiving member placed downstream of the vortex generator 12, detects alternating pressure fluctuations due to Karman vortices. The piezoelectric element 16 detects the force received by the vane 51 as bending stress. In the present embodiment, in addition to the vortex generator 12, a container 14 is provided on the vane 51, which is a force receiving member placed downstream of the vortex generator 12, from the outside of the conduit 10. A piezoelectric element 16 is provided in the container 14. Reference numeral 41 denotes a rigidity reducing means which is provided in the container 14 and reduces the rigidity of the container 14 in the drag direction rather than in the lift direction.

In this case, on the side surface of the container 14 from both sides,
A slit is used that has a bottom 411 cut from the drag direction and parallel to the lift direction. Center part 41 of container 41
In the state where 2 is connected, the rigidity can be changed by changing the width of the connecting portion.

As a result, the rigidity of the container 41 to which the piezoelectric element 16 is fixed becomes weak in the drag direction, so that the stress component in the drag direction can be reduced, and as a result, the vibration resistance in the drag direction can be improved. A vortex flowmeter capable of performing is obtained.

In the embodiment described above, the container 14
It was explained that the slit 41 which was cut from both sides from the drag direction and has a bottom parallel to the lift direction was used on the side surface of the above. However, it goes without saying that it is not necessary to have the bottom parallel to the lift direction. .

The above description merely shows specific preferred embodiments for the purpose of explaining and exemplifying the present invention. Therefore, the present invention is not limited to the above-mentioned embodiment, and many modifications are made without departing from the essence thereof.
It also includes deformation.

[0032]

As described above, according to the first aspect of the present invention.
Alternatively, according to claim 2, there is the following effect. A pipe in which a measurement fluid flows, a container provided on the vortex generator or a force receiving member provided on the downstream side of the vortex generator from outside the pipe, and a piezoelectric element provided in the container. , The rigidity reducing means provided in this container reduces the rigidity of the container in the drag force direction rather than in the lift force direction.
Even if the polarization state is different in the two polarization areas or the fixed state of the piezoelectric element is not uniform, noise can be reduced and a vortex flowmeter with improved noise resistance can be obtained.

According to claim 3 or 4 of the present invention,
It has the following effects. Since a slit cut from both sides in the drag direction on the side surface of the container is used as the rigidity reducing means, the slit is easy to make and an inexpensive vortex flowmeter can be obtained.

Therefore, according to the present invention, it is possible to realize a vortex flowmeter having improved noise resistance.

[Brief description of drawings]

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

FIG. 2 is a side view of FIG.

FIG. 3 is an explanatory view of parts of FIG.

FIG. 4 is a side view of FIG.

5 is a view taken along the line AA of FIG.

FIG. 6 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

FIG. 7 is a side view of FIG.

FIG. 8 is an explanatory diagram of a main part configuration of a conventional example that is generally used in the past.

9 is a side view of FIG.

10 is an explanatory diagram of an electric circuit of FIG.

11 is an explanatory diagram of the operation of FIG.

12 is an explanatory diagram of the operation of FIG.

13 is an explanatory diagram of the operation of FIG.

FIG. 14 is an explanatory view of a main part configuration of another conventional example which is generally used conventionally.

[Explanation of symbols]

10 pipelines 11 nozzles 12 Vortex generator 13 Flange 14 containers 15 Common electrode 16 Piezoelectric element 17 electrode plate 18 Insulation plate 19 Push rod 21 lead wire 25 charge amplifier 31 Axis member 32 pins 33 post 41 slits 411 bottom 412 central part 51 vanes A terminal B terminal FL measuring fluid

Claims (4)

[Claims] 1. A vortex flowmeter for measuring a flow velocity flow rate by detecting an alternating pressure fluctuation based on a Karman vortex generated by a vortex generator, and a pipe in which a fluid to be measured flows, and a vortex generator from the outside of the pipe. A vortex characterized by comprising: a container provided; a piezoelectric element provided in the container; Flowmeter. 2. A vortex flowmeter for measuring a flow velocity flow rate by detecting an alternating pressure fluctuation based on a Karman vortex generated by a vortex generator, and a pipe in which a fluid to be measured flows and a downstream side of the vortex generator. A container provided on the force receiving body from the outside of the conduit, a piezoelectric element provided in the container, and a rigidity reducing means provided in the container in which the rigidity of the container is weaker in the drag direction than in the lift direction. A vortex flowmeter, comprising: 3. The vortex flowmeter according to claim 1, wherein as the rigidity reducing means, a slit is used which is cut into the side surface of the container from both sides in the direction of the resistance force. 4. The slit used as the rigidity reducing means is a slit which is cut into the side surface of the container from both sides from the drag direction and has a bottom parallel to the lift direction.
The vortex flowmeter according to any one of claims 1 to 3.