JP2000346684A - Vortex flowmeter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vortex flowmeter which is of a simple structure which is solid, whose costs can be reduced and in which an S/N ratio with reference to vibrations other than a vortex signal is enhanced. SOLUTION: In this vortex flowmeter, a vortex frequency which is generated by a vortex generating body 3 inserted into a measuring conduit 1 is detected by a force receiving body 11 which is installed on the downstream of the vortex generating body 3. As the force receiving body 11, a sheetlike force-receiving- body main body 111 which is arranged in parallel to the vortex generating body 3, one end of which is fixed to the measuring conduit 1 and whose length is half or lower of one wavelength in the flow direction of a fluid to be measured is provided, two insertion holes 112 which are symmetric with respect to the axis of the center of gravity of the force-receiving-body main body 111 are provided, and two bimorph-type piezoelectric elements 113 which are inserted respectively into the insertion holes 112 so as to be fixed and bonded and and which detect the vortex frequency generated by the vortex generating body 3 are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vortex flow meter which has a simple structure, is robust, can be reduced in cost, and has an improved S / N ratio with respect to vibration noise other than a vortex signal.

[0002]

2. Description of the Related Art FIG. 8 is an explanatory view of the structure of a conventional example generally used in the prior art.
No. 8 (Japanese Utility Model Application No. 63-127053).

In the figure, a measuring fluid 1 is connected to a measuring pipe 1.
Flows. The vortex generator 3 is inserted into the measuring pipe 1. The force receiving element 4 is inserted into the measurement pipe 1 downstream of the vortex generator 3. A hole 5 is provided in the force receiving body 4.

[0004] The piezoelectric element 6 is inserted into the hole 5 and is embedded and fixed in the hole 5 with a thermosetting elastic epoxy resin 7.
Note that the piezoelectric element 6 may be hermetically embedded at the same time as the formation of the force receiving body 4.

In the above configuration, when the measurement fluid 2 flows through the measurement pipe 1, a Karman vortex is generated by the vortex generator 3, and the alternating force acting on the force receiving member 4 is detected by the Karman vortex.

[0006]

However, in such an apparatus, mechanical cancellation of vibration noise other than the vortex signal, for example, vibration due to bending or shearing other than around the axis is considered. At least, the force receiving member 4 is made of plastic so as to reduce the weight of the force receiving member 4 so that it is hardly affected by vibration.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, to have a simple structure, to be robust and to reduce costs.
An object of the present invention is to provide a vortex flowmeter having an improved S / N ratio with respect to vibration noise other than a vortex signal.

[0008]

In order to achieve the above object, according to the present invention, in the vortex flowmeter according to the first aspect, the vortex frequency generated by the vortex generator inserted into the measurement pipe is determined by: In a vortex flowmeter for detecting by a force receiving member provided downstream of the vortex generator, the force receiving member is disposed in parallel with the vortex generator and one end is fixed to the measurement pipe, and the flow direction of the measurement fluid is A plate-shaped force receiving body having a length equal to or less than half the wavelength of the vortex, and two insertion holes provided in the force receiving body with the center of gravity axis of the force receiving body being symmetrical,
It is characterized by comprising two bimorph type piezoelectric elements which are respectively inserted and fixed in the insertion holes and detect a vortex frequency generated by the vortex generator.

As a result, a simple structure, robustness and cost reduction can be achieved.
A vortex flowmeter with an improved N ratio can be realized.

According to a second aspect of the present invention, in the vortex flowmeter according to the first aspect, a material having a small mass is used as the force receiving body.

As a result, a vortex flowmeter is obtained in which the force receiving body itself is less susceptible to vibration and the S / N ratio is further improved.

According to a third aspect of the present invention, in the vortex flowmeter according to the first or second aspect, a plastic is used as the force receiving body.

As a result, a vortex flowmeter having an improved S / N ratio and improved corrosion resistance can be obtained.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 is an explanatory diagram of a main part configuration of an embodiment of the present invention. In the figure, the configuration of the same symbol as in FIG. 8 represents the same function. Hereinafter, only differences from FIG. 8 will be described.

In FIG. 1, the force receiving member 11 includes a plate-shaped force receiving member main body 111, two insertion holes 112, and two bimorph type piezoelectric elements 113. Plate-shaped force receiving element main body 111
Is arranged parallel to the vortex generator 3, one end of which is fixed to the measurement pipe 1, and has a length of not more than half λ / 2 of one wavelength λ of the Karman vortex in the flow direction of the measurement fluid 2.

The two insertion holes 112 are provided in the force receiving body main body 111.
Are provided on the force receiving body 111 with the center of gravity axis 114 being symmetrical. The two bimorph type piezoelectric elements 113 are:
The vortex frequency generated by the vortex generator 3 is detected by being inserted into the insertion holes 112 and fixed.

The two bimorph piezoelectric elements 113 are:
Each is inserted into the insertion hole 112, and in this case, it is fixed with resin. The bimorph type piezoelectric element 11
3 may be a parallel connection or a series connection.

In the above configuration, as shown in FIG. 3, when an external force N such as piping vibration is applied, the torque around the center of gravity axis 114 is not applied, and both the bimorph type piezoelectric elements 113 are provided as shown in FIG. Thus, bending force is applied.

For this reason, electric charges are generated in both bimorph type piezoelectric elements 113 in the same direction, and noise can be canceled by calculating the difference between the outputs of both bimorph type piezoelectric elements 113.

Next, when the fluid force due to the Karman vortex V is applied to the force receiving member 11, as shown in FIG. 5, due to the difference in the flow velocity distribution in the flow direction of the measurement fluid 2, as shown in FIGS. When charges are generated in the two piezoelectric elements 113 in opposite directions, and the difference between the charges output in the opposite directions is obtained, the vortex signal is added,
Double the output is obtained.

As described above, one end of the vortex generator is arranged in parallel with the vortex generator 3 and one end thereof is fixed to the measurement pipe 1. A plate-shaped force receiving body 111 having two insertion holes 112 provided in the force receiving body 111 with the center of gravity axis 114 of the force receiving body 111 being symmetrical, and inserted into the insertion holes 112, respectively. And two bimorph-type piezoelectric elements 113 for detecting a vortex frequency generated by the vortex generator 3.

As a result, the simple structure, the robustness, and the cost reduction can be attained.
A vortex flowmeter with an improved N ratio is obtained.

If a material having a small mass is used as the force receiving body 111, the force receiving body itself 111 is hardly affected by vibration, and a vortex flowmeter with an improved S / N ratio is provided. can get. Further, if plastic is used as the force receiving body 111, a vortex flowmeter with further improved S / N ratio and improved corrosion resistance can be obtained.

It should be noted that the foregoing description has been directed to specific preferred embodiments for the purpose of illustration and illustration of the invention. Therefore, the present invention is not limited to the above-described embodiments, and includes many more modifications without departing from the spirit thereof.
This includes deformation.

[0025]

As described above, according to the first aspect of the present invention,
According to the above, the following effects are obtained. A plate-shaped force receiving body having one end fixed to the measurement pipe line and parallel to the vortex generator and having a length of one half or less of one wavelength of the vortex in the flow direction of the measurement fluid; and a center of gravity of the force receiving body. Two insertion holes provided in the force receiving body with their axes symmetrical, and two bimorph type piezoelectric elements that are inserted and fixed in these insertion holes, respectively, and detect the vortex frequency generated by the vortex generator Was provided.

As a result, the simple structure, the robustness and the cost can be reduced, and the S / S against the vibration noise other than the vortex signal is reduced.
A vortex flowmeter with an improved N ratio can be realized.

According to the second aspect of the present invention, the following effects can be obtained. Since a material having a small mass is used as the force receiving body, the force receiving body itself is less likely to be affected by vibration, and a vortex flowmeter with an improved S / N ratio can be obtained.

According to the third aspect of the present invention, the following effects can be obtained. Since plastic is used as the force receiving body, a vortex flowmeter with further improved S / N ratio and improved corrosion resistance can be obtained.

Therefore, according to the present invention, with a simple structure,
In addition, it is possible to realize a vortex flowmeter which is robust, can reduce cost, and has an improved S / N ratio with respect to vibration noise other than the vortex signal.

[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 view of FIG.

FIG. 3 is an operation explanatory diagram of FIG. 1;

FIG. 4 is an operation explanatory diagram of FIG. 1;

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 explanatory view of a configuration of a main part of a conventional example generally used in the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Measurement pipeline 2 Measurement fluid 3 Vortex generator 11 Force receiving body 111 Force receiving body main body 112 Insertion hole 113 Piezoelectric element 114 Center of gravity axis λ One wavelength of Karman vortex N Noise S Vortex signal

Claims (3)

[Claims] 1. A vortex flowmeter for detecting a vortex frequency generated by a vortex generator inserted into a measurement pipe by a power receiver provided downstream of the vortex generator, wherein the force receiver includes: A plate-shaped force receiving body having one end fixed to the measurement pipe and arranged to be parallel to the vortex generator and having a length equal to or less than half of one wavelength of the vortex in the flow direction of the measurement fluid; Two insertion holes provided in the force receiving body with the center of gravity axis symmetrical, and two bimorph-type piezoelectric members respectively inserted into and fixed to the insertion holes and detecting a vortex frequency generated by the vortex generator. A vortex flowmeter comprising an element. 2. The vortex flowmeter according to claim 1, wherein a material having a small mass is used as the force receiving body. 3. The vortex flowmeter according to claim 1, wherein a plastic is used as the force receiving body.