JPH07243882A - Vortex flowmeter - Google Patents

Abstract

PURPOSE:To intercept the ultrasonic waves propagating through a vortex generation body in a vortex flowmeter. CONSTITUTION:Columnar members 22 and 23 having paths 30 and 31 are mounted on a housing body 20 to form a vortex generation body 21 in a passage 20a and a measuring path 29 is formed with the paths 30 and 31 communicating with each other. A slight clearance C1 is provided between the columnar members 22 and 23, an ultrasonic transmitter 35 and an ultrasonic receiver 36 are mounted on the columnar members 22 and 23 and an amplifier circuit 37 is connected thereto. When a fluid in the passage 20a flows to generate a Karman's vortex at a downstream point of the vortex generation body 21, a pressure difference is caused between introduction holes 32 and 33 so that a flow is generated in a measuring path 29 at a cycle the same as that of a Karman's vortex. An ultrasonic signal transmitted with the ultrasonic wave transmitter 35 is modulated by the flow and received with an ultrasonic transmitter 36. The modulation of the ultrasonic signal is demodulated with the amplifier circuit 37 to compute a flow rate of the fluid. The noise propagated to the columnar member 22 from the ultrasonic transmitter 35 is intercepted by the gap C1 and none transmitted to the columnar member 23 thereby improving the S/N ratio of the received signal of the ultrasonic receiver 36.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vortex flowmeter for measuring the flow rate of a fluid in a flow channel by detecting the generation of Karman vortex using an ultrasonic sensor.

[0002]

2. Description of the Related Art A conventional vortex flowmeter using an ultrasonic sensor will be described with reference to FIGS. In the vortex flowmeter 1 shown in FIGS. 6 and 7, a vortex generator 3 is provided in a housing body 2 forming a flow path 2a, and an ultrasonic sensor is provided on a side wall of the housing body 2 on the downstream side of the vortex generator 3. The constituent ultrasonic transmitters 4 and ultrasonic receivers 5 are arranged to face each other. Then, the ultrasonic wave signal transmitted from the ultrasonic wave transmitter 4 and propagated in the fluid is received by the ultrasonic wave receiver 5,
The generation of the Karman vortex is detected by demodulating an ultrasonic signal directly modulated by the Karman vortex generated on the downstream side of the vortex generator 3 by the flow of the fluid in the flow path 2a by an amplifier circuit (not shown). The flow rate of the fluid to be measured in the flow path 2a is calculated. In addition, as shown in FIG.
Ultrasonic transmitter 4 and ultrasonic receiver 5 (ultrasonic transmitter 4
(Only shown) is attached to the housing body 2 via an O-ring 6 and a packing 7, which are elastic bodies,
The ultrasonic signal propagating to the housing body 2 is attenuated.

The vortex flowmeter 8 shown in FIGS. 9 to 11 is a flow channel.
A vortex generator 10 is provided in the housing body 9 that forms 9a, and a measurement passage 11 that penetrates the flow passage 9a is formed inside the vortex generator 10. Further, the vortex generator 10 is provided with introduction holes 12 and 13 for introducing the flow of the Karman vortex generated in the flow passage 9a on the downstream side thereof into the measurement passage 11. At both ends of the measurement passage 11, an ultrasonic transmitter 14 and an ultrasonic receiver 15 that form an ultrasonic sensor are provided. Then, the ultrasonic signal transmitted from the ultrasonic transmitter 14 is propagated through the fluid in the measurement passage 11 and received by the ultrasonic receiver 15, and the downstream side of the vortex generator 10 is caused by the flow of the fluid in the flow passage 9a. The generation of the Karman vortex is detected by demodulating the ultrasonic signal modulated by the flow in the measurement passage 11 generated in proportion to the Karman vortex generated in the The flow rate of the measurement fluid is calculated. As shown in FIG. 11, the vortex generator 10 is attached to the housing body 9 via an O-ring 16 which is an elastic body, and the ultrasonic transmitter 14 and the ultrasonic receiver 15 (only the ultrasonic receiver 14 is shown. Is attached to the vortex generator 10 via an O-ring 17 and a packing 18 which are elastic bodies,
The ultrasonic signal propagating to the housing body 9 and the vortex generator 10 is attenuated.

[0004]

However, the above conventional vortex flowmeter has the following problems.

That is, in the vortex flowmeter 1 shown in FIGS. 6 to 8, as the diameter of the housing body 2 increases, the distance between the ultrasonic sensors increases, so that the reception voltage of the ultrasonic receiver 5 is attenuated by the attenuation in the fluid. Is significantly reduced. However,
Ultrasonic waves are hardly attenuated in a solid such as a metal as compared with a fluid, and are easily propagated in a metal nearly 1000 times as much as in a gas.
Since the ultrasonic signal (wraparound noise) propagated through the housing body 2 and received by the ultrasonic receiver 5 becomes relatively large, it becomes difficult to detect a stable Karman vortex.

On the other hand, in the vortex flowmeter 8 shown in FIGS. 9 to 11, by embedding the ultrasonic sensors inside the vortex generator 10, the distance between the ultrasonic sensors can be freely set. Even if the diameter of the housing body 9 is large, the distance between the ultrasonic sensors can be reduced to reduce the ultrasonic receiver.
It is possible to prevent the reception voltage of 15 from decreasing. However, in this case, the ultrasonic sensors are acoustically coupled to each other through the vortex generator 10 at a short distance.
Since the ultrasonic signal (wraparound noise) propagating through 10 and received by the ultrasonic receiver 15 becomes relatively large, it becomes difficult to detect a stable Karman vortex.

In particular, when the vortex flowmeter has a wide operating temperature range and an elastic body capable of sufficiently attenuating ultrasonic waves cannot be used as an O-ring and a packing interposed in the mounting portion of the ultrasonic sensor and the vortex generator, ultrasonic waves are generated. It easily propagates to the housing body and vortex generator, and wraparound noise tends to become a problem.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a vortex flowmeter which blocks ultrasonic waves propagating through a vortex generator.

[0009]

In order to solve the above-mentioned problems, a first aspect of the present invention is to provide a housing main body that forms a flow passage, and a vortex generator that generates a Karman vortex by the flow of fluid in the flow passage. , A measurement passage formed inside the vortex generator and communicating with the flow passage to generate a flow proportional to the generation of a Karman vortex, and an ultrasonic transmitter provided at one end side of the measurement passage and the other end side. The flow rate of the measurement fluid in the flow path is calculated based on an ultrasonic sensor including an ultrasonic receiver provided and an ultrasonic signal connected to the ultrasonic sensor and modulated by the flow in the measurement passage. In the vortex flowmeter, the vortex generator is formed of a transmission side member provided with the ultrasonic transmitter and a reception side member provided with the ultrasonic receiver. Acoustic between the member and the receiving member Wherein the gap is provided.

A second aspect of the invention is a housing main body forming a flow passage, a vortex generator for generating a Karman vortex due to a fluid flow in the flow passage, and a vortex generator formed inside the vortex generator and communicating with the flow passage. And an ultrasonic sensor including a measurement passage that produces a flow proportional to the generation of the Karman vortex and an ultrasonic transmitter provided at one end of the measurement passage and an ultrasonic receiver provided at the other end of the measurement passage, A vortex flowmeter comprising an amplifier circuit connected to the ultrasonic sensor for calculating the flow rate of the measurement fluid in the flow path based on an ultrasonic signal modulated by the flow in the measurement passage, The generator is formed of a transmission side member provided with the ultrasonic transmitter and a reception side member provided with the ultrasonic receiver, and the transmission side member and the reception side member are different from the vortex generator. Connected to each other via the connecting members of It is characterized in that is.

According to a third aspect of the present invention, a housing body forming a flow passage, a vortex generator for generating a Karman vortex by a fluid flow in the flow passage, and a vortex generator formed inside the vortex generator and communicating with the flow passage. And a measurement passage that produces a flow proportional to the generation of Karman vortices, ultrasonic sensors that are provided at both ends of the measurement passage for transmitting and receiving ultrasonic signals, and a flow in the measurement passage that is connected to the ultrasonic sensor. A vortex flowmeter comprising: an amplifier circuit that calculates a flow rate of a measurement fluid in the flow path based on a modulated ultrasonic wave signal, wherein one end side of the vortex generator accommodates one of the ultrasonic sensors. And is fixed to the housing main body, and the other end side is extended so as to face the other of the ultrasonic sensors fixed to the housing with a gap.

According to a fourth aspect of the present invention, a housing main body forming a flow passage, a vortex generator for generating a Karman vortex by a fluid flow in the flow passage, and a vortex generator formed inside the vortex generator and communicating with the flow passage. And a measurement passage that produces a flow proportional to the generation of Karman vortices, ultrasonic sensors that are provided at both ends of the measurement passage for transmitting and receiving ultrasonic signals, and a flow in the measurement passage that is connected to the ultrasonic sensor. In the vortex flowmeter, which comprises an amplifier circuit for calculating the flow rate of the measurement fluid in the flow path based on the modulated ultrasonic signal, the vortex generator is made of a substance having a high ultrasonic attenuation rate. It is characterized by being

[0013]

With this configuration, according to the first aspect of the invention, the ultrasonic waves propagated from the ultrasonic transmitter to the transmitting side member of the vortex generator are blocked by the acoustic gap and are directly received. Since it is not transmitted to the ultrasonic wave, the wraparound noise can be reduced, and the ultrasonic receiver can receive a signal with a good S / N ratio.

According to the second aspect of the invention, the ultrasonic wave propagated from the ultrasonic transmitter to the transmitting side member of the vortex generator is sufficiently attenuated by the coupling member and is not directly transmitted to the receiving side member.
The wraparound noise can be reduced, and the ultrasonic receiver can receive a signal with a good S / N ratio. Further, since the receiving side member and the transmitting side member are connected by the connecting member, the strength of the vortex generator can be increased.

According to the third aspect of the invention, since the gap is provided between the ultrasonic sensor and the vortex generator, the ultrasonic wave transmitted from one ultrasonic sensor propagates through the vortex generator and is directly transmitted. Since it does not reach the other ultrasonic sensor, it is possible to reduce the wraparound noise and receive a signal with a good S / N ratio.

According to the fourth invention, since the vortex generator is made of a material having a high ultrasonic attenuation factor, the ultrasonic wave directly propagating from the transmitting side of the ultrasonic sensor to the receiving side through the vortex generator is generated. Since it is sufficiently attenuated, the wraparound noise can be reduced and a signal with a good S / N ratio can be received.

[0017]

Embodiments of the present invention will now be described in detail with reference to the drawings.

The first embodiment will be described with reference to FIGS. 1 and 2. As shown in FIGS. 1 and 2, the vortex flowmeter 19
Is a pair of columnar members 22 that form a vortex generator 21 in a substantially cylindrical housing body 20 that forms a flow passage 20a for a fluid to be measured along its radial direction, that is, a direction orthogonal to the flow passage 20a. , 23 are provided. The columnar members 22 and 23 are provided with mounting holes 24 and 25, which are provided in the side wall of the housing body 20, respectively.
The flange portions 22a, 23a on one end side are supported by the outer peripheral surface of the housing body 20, and the tip portions on the other end side are provided so as to face each other with a slight gap C ₁ .
It is attached to the housing body 20 via an O-ring 26 and a packing 27 which are elastic bodies. Here, the columnar member 22
The columnar member 23 and the columnar member 23 respectively form a transmitting side member facing the transmitter side of the ultrasonic sensor and a receiving side member facing the receiver side of the ultrasonic sensor, and of the contact portion with the fluid in the flow path 20a. The vortex generator 21 has the same sectional shape and is integrally arranged.
Are configured.

Passages 30 and 31 are formed inside the columnar members 22 and 23 to form a measurement passage 29 which communicates with each other and penetrates the passage 20a in the radial direction. The columnar members 22 and 23 are provided with introduction holes 32 and 33 for communicating the passages 30 and 31 with the flow passage 20a, respectively. The introduction hole 32 and the introduction hole 33 are opened on the opposite side to the downstream side of the flow path 20a so that the flow due to the Karman vortex generated on the downstream side of the vortex generator 21 is introduced into the measurement passage 29. It has become. The columnar member 2
The gap C ₁ between the 2 and 23 is an acoustic gap that blocks the ultrasonic signal propagating between the columnar members 22 and 23, and should not affect the generation of Karman vortices and the flow in the measurement passage 29. It is set small enough.

The flange portions 22a and 23a of the columnar members 22 and 23 have an ultrasonic transmitter 35 and an ultrasonic receiver 36, which constitute an ultrasonic sensor, with a packing 34 made of an elastic body interposed therebetween.
Are attached, and both ends of the measurement passage 29 are closed by these. Then, the ultrasonic signal transmitted from the ultrasonic transmitter 35 is propagated through the fluid in the measurement passage 29 and received by the ultrasonic receiver 36.
The ultrasonic transmitter 35 and the ultrasonic receiver 36 detect the generation frequency of the Karman vortex in the flow path 20a by demodulating the modulated component due to the fluid flow in the measurement passage 29 from the ultrasonic signals transmitted and received by these. , An amplifier circuit 37 that calculates and outputs a signal proportional to the flow rate of the fluid to be measured in the flow path 20a based on this frequency.
Are connected.

The operation of the first embodiment constructed as above will be described below.

When the fluid flows through the flow path 20a in the housing body 20, Karman vortices having a frequency proportional to the flow rate are generated alternately on both downstream sides of the vortex generator 21. Due to the generation of this Karman vortex, a pressure difference is generated between the introduction holes 32 and 33 provided in the vortex generator 21, and the measurement passage 29 is generated at the same cycle as the generation of the Karman vortex.
Flows in the opposite direction alternate inside. In addition, super sound transmitter 35
The ultrasonic signal emitted from the ultrasonic wave propagates through the fluid in the measurement passage 29 and is received by the ultrasonic receiver 36. At this time, since the ultrasonic signal is modulated by the flow in the measurement passage 29, this modulation is demodulated by the amplifier circuit 37 to detect the generation frequency of the Karman vortex, and based on this frequency, the fluid in the flow path 20a The flow rate of the fluid to be measured can be measured by calculating and outputting a signal proportional to the flow rate.

Here, as shown in FIG.
The ultrasonic wave transmitted from 35 is divided into an ultrasonic wave S ₁ propagating in the fluid in the measurement passage 29 and an ultrasonic wave S ₂ propagating to the columnar member 22 forming the vortex generator 21 via the packing 34. . From the ultrasonic wave S ₂ propagated to the columnar member 22, the O-ring 26
The ultrasonic wave S ₃ propagating to the housing main body 20 is branched via the packing 27 and the packing 27, 34 and the O-ring 26 between the ultrasonic wave S ₃ and the ultrasonic transmitter 35 of the signal source. Since it propagates through the boundary layer of, it is sufficiently attenuated. On the other hand, the ultrasonic wave S ₂ propagating through the columnar member 22
Is a columnar member on the receiving side that is blocked by the acoustic gap C ₁ .
No direct transmission to 23. In this way, the ultrasonic wave propagating through the housing body 20 and the vortex generator 21 can be sufficiently attenuated and cut off to reduce the wraparound noise, so that the ultrasonic receiver 36 receives a signal with a good S / N ratio. Therefore, stable Karman vortex detection can be performed.

Next, a second embodiment of the present invention will be described with reference to FIGS. 3 and 4. The second embodiment differs from the vortex flowmeter 19 of the first embodiment only in that the tip end portions of the pair of columnar members are joined by a joining member. The same members as those described above are denoted by the same reference numerals, and only different portions will be described in detail. Further, the amplifier circuit 37 is not shown.

As shown in FIGS. 3 and 4, the vortex flowmeter 38
Of the pair of columnar members 22 and 23 forming the vortex generator 21 are joined to each other via the joining member 39 at their end portions facing each other. The coupling member 39 is made of a material different from that of the columnar members 22 and 23, and is capable of sufficiently attenuating ultrasonic waves at the boundary surface with the columnar members 22 and 23, or capable of sufficiently attenuating ultrasonic waves by itself. .

With this configuration, the ultrasonic waves transmitted from the ultrasonic transmitter 35 and propagated to the columnar member 22 are sufficiently attenuated by the boundary surface between the columnar members 22 and 23 and the coupling member 39 and the coupling member 39, so that the receiving side is provided. Does not directly propagate to the columnar member 23. Therefore, as in the first embodiment, since the wraparound noise can be reduced, the ultrasonic receiver 36 can receive a signal with a good S / N ratio, and stable Karman vortex detection can be performed. it can. Furthermore, the vortex flowmeter of this embodiment
In FIG. 19, since the tip ends of the columnar members 22 and 23 are joined by the joining member 39 to be integrated, the strength of the vortex generator 21 can be increased. The flow in the generation and measurement passage 29 is not disturbed.

In this embodiment, the coupling member 39 is arranged at the center of the vortex generator 21, but the same effect can be obtained by arranging it at any position between the ultrasonic sensors. Can be obtained.

Next, a third embodiment of the present invention will be described with reference to FIG. The third embodiment is different from the vortex flowmeter 19 of the first embodiment only in the mounting structure of the vortex generator and the ultrasonic receiver. The same numbers are given to the members, and only different portions will be described in detail. Further, the amplifier circuit 37 is not shown.

As shown in FIG. 5, in the vortex flowmeter 40, the vortex generator 41 is arranged in the flow path 20a as in the first embodiment. The vortex generator 41 is inserted into the mounting hole 24 of the housing body 20, the flange portion 41a on one end side is supported by the outer peripheral surface of the housing body 20, and the tip end on the other end side extends to the mounting hole 25 on the opposite side. It is attached to the housing body 20 via the housing 27 via the O-ring 26 and the packing 27. That is, one end side is fixed to the housing main body 20, and the other end side is extended so as to face an ultrasonic receiver 36 (described later) fixed across the flow path 20a and fixed in the mounting hole 25 with a gap. Further, the vortex generator 41 is provided with the measurement passage 42 and the introduction holes 43 and 44, as in the first embodiment.

An ultrasonic transmitter 35 is attached to the flange portion 41a of the vortex generator 41 via a packing 34. Further, an ultrasonic receiver 36 is attached to the attachment hole 25 of the housing body 20 via a packing 34 so as to face the measurement passage 42 that opens at the end of the vortex generator 41. A slight gap C ₂ is provided between the tip of the vortex generator 41 and the ultrasonic receiver 36 and the housing body 20 so as not to contact them. Then, the ultrasonic signal transmitted from the ultrasonic transmitter 35 is propagated in the fluid in the measurement passage 42 and received by the ultrasonic receiver 36.

With this configuration, as in the first embodiment, based on the modulation of the ultrasonic signal by the flow in the measurement passage 42,
The flow rate of the fluid to be measured can be measured. At this time,
The ultrasonic waves transmitted from the ultrasonic transmitter 35 and propagated to the vortex generator 41 are blocked by the gap C ₂ and do not directly propagate to the ultrasonic receiver 36. Therefore, as in the first embodiment, the wraparound noise can be reduced, so that the ultrasonic receiver
The 36 can receive a signal with a good S / N ratio, and can stably detect the Karman vortex.

Further, as a fourth embodiment, in the vortex flowmeter shown in the first to third embodiments and FIGS. 9 to 11, the vortex generator is made of a material having high ultrasonic attenuation rate (resin, ceramics, etc.). With this configuration, the ultrasonic waves propagating through the vortex generator can be sufficiently attenuated. Therefore, as in the first to third embodiments, the wraparound noise is reduced and the ultrasonic receiver has an S / N ratio. A good signal can be received, and stable Karman vortex detection can be performed.

[0033]

As described above in detail, according to the vortex flowmeter of the present invention, the ultrasonic wave directly propagating from the transmitting side of the ultrasonic sensor to the receiving side via the vortex generator can be sufficiently attenuated and blocked. You can As a result, the wraparound noise can be reduced and the receiver side of the ultrasonic sensor can receive a signal with a good S / N ratio, so that there is an excellent effect that a stable Karman vortex can be detected.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a first embodiment of the present invention.

FIG. 2 is a diagram showing a propagation path of ultrasonic waves propagating from the ultrasonic transmitter to the housing body and the vortex generator in the apparatus of FIG.

FIG. 3 is a vertical sectional view of a second embodiment of the present invention.

4 is a vertical cross-sectional view taken along the line AA of the vortex generator of the apparatus shown in FIG.

FIG. 5 is a vertical sectional view of a third embodiment of the present invention.

FIG. 6 is a vertical sectional view of a front surface of a conventional vortex flowmeter using an ultrasonic sensor.

7 is a side elevational cross-sectional view of the device of FIG.

8 is a diagram showing a propagation path of ultrasonic waves propagating from the ultrasonic transmitter to the housing main body in the apparatus of FIG.

FIG. 9 is a front vertical sectional view of a conventional vortex flowmeter using an ultrasonic sensor having a measurement passage inside a vortex generator.

10 is a vertical cross-sectional side view of the device of FIG.

11 is a diagram showing a propagation path of ultrasonic waves propagating from the ultrasonic transmitter to the housing body and the vortex generator in the apparatus of FIG.

[Explanation of symbols]

19,38,40 Vortex flowmeter 20 Housing body 20a Flow path 21,41 Vortex generator 22 Columnar member (transmitting side member) 23 Columnar member (receiving side member) 29 Measuring passage 35 Ultrasonic transmitter (ultrasonic sensor) 36 Ultrasonic receiver (ultrasonic sensor) 37 Amplifier circuit 39 Coupling member C ₁ , C ₂ Gap

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Atsuro Sensen 4-1-2, Hirano-cho, Chuo-ku, Osaka, Osaka Gas Co., Ltd. (72) Inventor Hiroshi Yoshikura 1-3-6 Fujimi, Kawasaki-ku, Kawasaki-shi, Kanagawa No. Tokiko Co., Ltd. (72) Inventor Yutaka Inada 1-6-3 Fujimi, Kawasaki-ku, Kawasaki-shi, Kanagawa Tokiko Co., Ltd. (72) Kazumasa Kawasaki 1-6-3, Fujimi, Kawasaki-ku, Kanagawa Prefecture Tokico Co., Ltd.

Claims (4)

[Claims] 1. A housing main body that forms a flow passage, a vortex generator that generates a Karman vortex by the flow of fluid in the flow passage, and a Karman vortex that is formed inside the vortex generator and communicates with the flow passage. An ultrasonic sensor including a measurement passage that produces a flow proportional to the generation of an ultrasonic wave, an ultrasonic transmitter provided at one end of the measurement passage, and an ultrasonic receiver provided at the other end of the measurement passage, and the ultrasonic sensor In the vortex flowmeter, which is connected to the vortex flowmeter and which calculates the flow rate of the measurement fluid in the flow path based on the ultrasonic signal modulated by the flow in the measurement passage, the vortex generator, It is formed of a transmission side member provided with the ultrasonic transmitter and a reception side member provided with the ultrasonic receiver, and an acoustic gap is provided between the transmission side member and the reception side member. Vortex flowmeter characterized by. 2. A housing main body that forms a flow passage, a vortex generator that generates a Karman vortex by the flow of fluid in the flow passage, and a Karman vortex that is formed inside the vortex generator and communicates with the flow passage. An ultrasonic sensor including a measurement passage that produces a flow proportional to the generation of an ultrasonic wave, an ultrasonic transmitter provided at one end of the measurement passage, and an ultrasonic receiver provided at the other end of the measurement passage, and the ultrasonic sensor In the vortex flowmeter, which is connected to the vortex flowmeter and which calculates the flow rate of the measurement fluid in the flow path based on the ultrasonic signal modulated by the flow in the measurement passage, the vortex generator, The transmitting side member provided with the ultrasonic transmitter and the receiving side member provided with the ultrasonic receiver are formed of a coupling member made of a material different from that of the vortex generator. Be connected to each other via Vortex flowmeter characterized by. 3. A Karman vortex that is formed inside the vortex generator and communicates with the flow passage, a vortex generator that generates a Karman vortex by the flow of a fluid in the flow passage, and a Karman vortex that is formed inside the vortex generator. Of a measurement passage that generates a flow proportional to the generation of ultrasonic waves, ultrasonic sensors that are provided at both ends of the measurement passage for transmitting and receiving ultrasonic signals, and that are connected to the ultrasonic sensor and are modulated by the flow in the measurement passage. In the vortex flowmeter, which comprises an amplifier circuit that calculates the flow rate of the measurement fluid in the flow path based on an ultrasonic signal, the vortex generator has one end side that accommodates one of the ultrasonic sensors and the housing. A vortex flowmeter fixed to the main body, the other end extending so as to face the other of the ultrasonic sensors fixed to the housing with a gap. 4. A Karman vortex that is formed inside the vortex generator and communicates with the flow passage, a vortex generator that generates a Karman vortex by the flow of a fluid in the flow passage, and a Karman vortex that is formed inside the vortex generator. Of a measurement passage that generates a flow proportional to the generation of ultrasonic waves, ultrasonic sensors that are provided at both ends of the measurement passage for transmitting and receiving ultrasonic signals, and that are connected to the ultrasonic sensor and are modulated by the flow in the measurement passage. In a vortex flowmeter including an amplifier circuit that calculates a flow rate of a measurement fluid in the flow path based on an ultrasonic signal, the vortex generator is made of a substance having a high ultrasonic attenuation rate. And vortex flowmeter.