JP5704510B2 - Ultrasonic flow meter and flow measurement method - Google Patents

Description

The present invention relates to an ultrasonic flowmeter and a flow rate measuring method that are suitable for application to a flowmeter that can measure a large flow velocity of a fluid to be measured by using a directional displacement of ultrasonic waves.

2. Description of the Related Art Conventionally, an ultrasonic flowmeter that measures the velocity of a fluid flowing in a pipe and displays the flow rate is often used in plants such as electricity, machinery, and chemical factories. In such an ultrasonic flowmeter, transducers that also serve as ultrasonic receivers are attached to the upstream side and the downstream side of the pipe. According to the ultrasonic flowmeter, ultrasonic waves are alternately transmitted across the fluid from the upstream side to the downstream side and across the fluid from the downstream side to the upstream side. Desired.

FIG. 11 is an explanatory diagram showing an internal configuration example of the ultrasonic flowmeter 10 according to the conventional example. An ultrasonic flow meter 10 shown in FIG. 11 includes a pair of transducers (hereinafter referred to as ultrasonic transducers 1 and 2) that also serve as an ultrasonic receiver. The ultrasonic transducer 1 is a pedestal having a predetermined shape in order to maintain an inclined posture with respect to the measurement tube 3 on the upstream side of the measurement tube 3 and on one side of the outer peripheral portion of the measurement tube 3. 15 is attached in combination.
The ultrasonic transducer 2 is a pedestal having a predetermined shape in order to maintain an inclined posture with respect to the measurement tube 3 on the other side of the outer peripheral portion of the measurement tube 3 on the downstream side of the measurement tube 3. 1
9 is attached in combination.

According to the ultrasonic flow meter 10, the ultrasonic transducer 1 on the upstream side transmits ultrasonic waves toward the ultrasonic transducer 2 on the downstream side when measuring the flow velocity. The ultrasonic transducer 2 is
The ultrasonic wave from the ultrasonic transducer 1 is received. Further, the ultrasonic transducer 2 on the downstream side transmits ultrasonic waves toward the ultrasonic transducer 1 on the upstream side. The ultrasonic transducer 1 receives ultrasonic waves from the ultrasonic transducer 2.

These transmissions and receptions are alternately repeated, and the arrival time of the ultrasonic wave from the upstream ultrasonic transducer 1 to the downstream ultrasonic transducer 2 is T1, and the downstream ultrasonic transducer 2 goes to the upstream ultrasonic transducer 1. When the arrival time of the reaching ultrasonic wave is T2, since the ultrasonic wave from the ultrasonic transducer 1 to the ultrasonic transducer 2 is forward, that is, the ultrasonic wave is on the flow, the arrival time T1 is accelerated.

On the other hand, since the ultrasonic wave from the ultrasonic transducer 2 to the ultrasonic transducer 1 is in the reverse direction, that is, the ultrasonic wave is reverse to the flow, the arrival time T2 is delayed. Here, the distance between the ultrasonic transducer 1 and the ultrasonic transducer 2 in the tube axis direction of the measuring tube 3 is L, and the inclination angle between the ultrasonic transducer 1 (or 2) and the measuring tube 3 is φ. ,
When the flow velocity of the fluid to be measured is V, the following equation:
V = (L / 2cosφ) · {(1 / T1) − (1 / T2)}
Is calculated (passing time difference method).

Regarding this type of ultrasonic flow meter, Patent Document 1 discloses an ultrasonic flow meter that measures the flow rate of a fluid to be measured flowing in a measurement tube using ultrasonic waves. According to this ultrasonic flowmeter, the ultrasonic flowmeter includes a plurality of first and second transmission / reception ultrasonic transducers. The first transmitting / receiving ultrasonic transducer is disposed on the outer peripheral surface of the measurement tube at a predetermined interval in the tube axis direction of the measurement tube. The first transmission / reception ultrasonic transducer is formed of a pair of transducers, and these transducers are arranged so as to be able to emit ultrasonic waves toward the inside in the oblique direction of the tube axis.

The second transmitting / receiving ultrasonic transducer is disposed on the outer peripheral surface of the measurement tube at a position facing the measurement tube in the tube cross-sectional direction. The second transmitting / receiving ultrasonic transducer is formed of a pair of transducers,
These vibrators are arranged to face each other and emit ultrasonic waves in the tube cross-sectional direction. Based on this assumption, the flow rate component measured by the second transmission / reception ultrasonic transducer is removed from the flow rate component measured by the first transmission / reception ultrasonic transducer, and the flow rate of the fluid to be measured is calculated. When the ultrasonic flowmeter is configured in this way, only the flow velocity in the tube axis direction from which the flow velocity component such as the drift included in the flow velocity component of the fluid to be measured is removed can be measured.

Patent Document 2 discloses an ultrasonic flowmeter including first and second ultrasonic transducers, an ultrasonic reflector, a flow rate correction coefficient determining unit, and a flow rate calculating unit. The first ultrasonic transducer is attached to a tube outer peripheral portion on one side of the measurement tube and forms a certain angle with the tube axis direction of the measurement tube, and the tube outer peripheral portion on the other side of the measurement tube The ultrasonic wave is transmitted to the ultrasonic wave reflector disposed on the side, and the ultrasonic wave is alternately received from the ultrasonic wave reflector side.

The second ultrasonic transducer is attached to the outer periphery of the tube on the same side of the measurement tube at a predetermined distance in the tube axis direction of the measurement tube with respect to the first ultrasonic transducer. It is a direction that forms an angle with the axial direction, transmits ultrasonic waves to the ultrasonic reflector, and alternately receives ultrasonic waves from the side of the ultrasonic reflector.

According to the ultrasonic flowmeter of Patent Document 2, the first correlation value of the ultrasonic signal propagated through the fluid to be measured in the measurement tube from one ultrasonic transducer to the other ultrasonic transducer, or
Depending on the intensity of the propagated ultrasonic signal, the measurement of the first flow velocity of the fluid to be measured based on the first correlation value or the second flow velocity based on the second correlation value of the ultrasonic signal reflected by the ultrasonic reflector. One of the measurements is made.

The flow rate correction coefficient determining means obtains a flow rate correction coefficient from the surface roughness coefficient of the measuring tube based on the ratio between the measured first and second flow velocities. On the premise of this, the flow rate calculation means obtains the flow rate of the fluid to be measured using the flow rate correction coefficient of the flow rate correction coefficient determination means and the first flow velocity. When the ultrasonic flow meter is configured in this way, a more accurate flow rate correction coefficient corresponding to the surface roughness is obtained, and high-accuracy flow rate measurement using this can be performed.

Japanese Patent Laying-Open No. 2005-172547 (page 4 FIG. 1) Japanese Patent Laying-Open No. 2010-101767 (FIG. 1 on page 5)

Incidentally, the ultrasonic flowmeter according to the conventional example has the following problems.
i. According to the ultrasonic flowmeter 10 that injects sound waves obliquely as shown in FIG. 11, the pulse path of the ultrasonic waves can be accurately aligned between the two ultrasonic transducers 1 and 2. When the flow velocity V becomes a large flow velocity, the ultrasonic pulse path (directivity characteristic) between the ultrasonic transducers 1 and 2 changes, so that the signals received by the ultrasonic transducers 1 and 2 become smaller, and the flow velocity measurement is performed. It becomes difficult. Incidentally, it is known that a commercially available product has a limit of about 30 m / s for measurement of a large flow velocity, although it depends on the dimensions of the pipe and the ultrasonic transducers 1 and 2.

ii. According to the ultrasonic flow meter as found in Patent Document 1, a method of removing the flow velocity component measured by the second transmission / reception ultrasonic transducer from the flow velocity component measured by the first transmission / reception ultrasonic transducer is adopted. However, when the flow velocity V of the fluid to be measured becomes a large flow velocity, the ultrasonic pulse path (directional characteristic) between the first and second transmission / reception ultrasonic transducers changes. There is a problem in that the signal received at 1 becomes smaller and it becomes difficult to calculate the flow rate of the fluid to be measured more accurately.

iii. According to the ultrasonic flow meter as found in Patent Document 2, an angle is formed with the tube axis direction of the measurement tube from the first ultrasonic transducer attached to the outer periphery of the tube on one side of the measurement tube. Direction, the ultrasonic wave is transmitted to the ultrasonic reflector disposed on the outer circumference of the tube on the other side of the measurement tube, and the ultrasonic wave is alternately received from the ultrasonic reflector side. A predetermined distance is maintained in the tube axis direction of the measurement tube with respect to the ultrasonic transducer, and the second ultrasonic transducer attached to the outer periphery of the tube on the same side of the measurement tube A method is adopted in which an ultrasonic wave is transmitted to an ultrasonic reflector in a direction forming an angle, and an ultrasonic wave is alternately received from the ultrasonic reflector side. Even in this method, when the flow velocity V of the fluid to be measured becomes a large flow velocity, the ultrasonic pulse path (directional characteristic) between the ultrasonic transducers 1 and 2 changes. There is a problem in that the signal received at 1 becomes smaller and the flow velocity measurement becomes difficult.

Therefore, the present invention solves the above-described problem, devised the principle of measuring the flow velocity of the fluid to be measured, even if the flow of the fluid to be measured is fast and the pulse path of the ultrasonic wave changes, An object of the present invention is to provide an ultrasonic flowmeter and a flow rate measuring method capable of measuring a flow velocity.

In order to solve the above problem, an ultrasonic flowmeter according to claim 1 is an ultrasonic flowmeter that measures a flow rate of a fluid to be measured that flows through a straight portion of a measurement tube,
Wherein mounted on the pipe outer peripheral portion of one side of the measuring tube, first transceiver that transmits ultrasound in a direction substantially perpendicular to the tube axis direction of the measuring tube, receives the ultrasonic wave from the side of the other lateral An ultrasonic transducer,
A predetermined distance is maintained in the tube axis direction of the measurement tube with respect to the first transmission / reception ultrasonic transducer, and the tube is attached to the outer periphery of the tube on the other side of the measurement tube. transmitting ultrasonic waves in a direction substantially orthogonal, and the second transmitter ultrasonic transducer for receiving ultrasonic waves from the side of the other hand,
When the ultrasonic wave is transmitted from the first transmission / reception ultrasonic transducer, the intensity of the first ultrasonic detection signal received by the second transmission / reception ultrasonic transducer is measured, and the second transmission / reception ultrasonic transducer is measured. Measuring means for measuring the intensity of the second ultrasonic detection signal received by the first transmission / reception ultrasonic transducer when transmitting ultrasonic waves from the ultrasonic transducer;
Calculating means for calculating the flow velocity of the fluid under measurement from the intensity of the first ultrasonic detection signal and the intensity of the second ultrasonic detection signal measured by the measuring means ;
The computing means is
The mounting position of the first transmission / reception ultrasonic transducer is the upstream side of the mounting position of the second transmission / reception ultrasonic transducer, and the fluid to be measured flows in the measuring tube from the upstream side to the downstream side. ,
The distance between the first transmission / reception ultrasonic transducer and the second transmission / reception ultrasonic transducer in the tube axis direction of the measurement tube is L, the inner diameter of the measurement tube is D, and the flow velocity of the fluid to be measured The first transmitting / receiving ultrasonic transducer at the time of measurement of the flow velocity V, where θ is the directivity angle of the ultrasonic wave at “0”, C is the fluid sound velocity of the ultrasonic wave, and V is the flow velocity of the fluid to be measured. An angle indicating the radiation direction of the ultrasonic waves transmitted from the second transmitting / receiving ultrasonic transducer at the time of measuring an arbitrary flow velocity of the fluid to be measured is θ 2. (1) to (3), that is,
θ = tan ⁻¹ (L / D) (1)
θ1 = tan ⁻¹ ( LD / cos (θ) / C × V) / D (2)
θ2 = tan ⁻¹ (L + D / cos (θ) / C × V) / D (3)
And
The value of θ1 is determined based on a table in which the intensity of the first ultrasonic detection signal is associated with the value of θ1.
The value of θ2 is determined based on a table in which the intensity of the second ultrasonic detection signal is associated with the value of θ2 .

According to the ultrasonic flowmeter of the present invention, when measuring the flow rate of the fluid to be measured flowing in the straight portion of the measurement tube using the ultrasonic directional displacement, the first transmission / reception ultrasonic transducer includes: It is attached to the outer periphery of the tube on one side of the measurement tube, transmits ultrasonic waves in a direction substantially orthogonal to the tube axis direction of the measurement tube, and alternately receives ultrasonic waves from the other side. The second transmission / reception ultrasonic transducer is attached to the outer peripheral portion of the tube on the other side of the measurement tube while maintaining a predetermined distance in the tube axis direction of the measurement tube with respect to the first transmission / reception ultrasonic transducer. Send ultrasonic waves in a direction substantially perpendicular to the tube axis direction of the measurement tube,
The ultrasonic waves from the other side are received alternately. On the premise of this, the calculation means inputs an ultrasonic detection signal including a directional displacement component obtained alternately from the first and second transmission / reception ultrasonic transducers,
The flow velocity of the fluid to be measured is calculated from the received intensity of the ultrasonic detection signal.

By this calculation, the flow velocity of the fluid to be measured can be measured using the directional displacements of the ultrasonic waves transmitted from the first and second transmission / reception ultrasonic transducers. In addition, when the first and second transmission / reception ultrasonic transducers are installed, alignment of the ultrasonic pulse path between the two transmission / reception ultrasonic transducers can be omitted.

The ultrasonic flowmeter according to claim 2 is the ultrasonic flowmeter according to claim 1 , wherein the fluid sound velocity C or a distance L between the first transmission / reception ultrasonic transducer and the second transmission / reception ultrasonic transducer is used as a parameter. A storage unit that stores a relationship with the flow velocity V of the fluid to be measured corresponding to the intensity ratio between the first and second ultrasonic detection signals as a reference table;
The calculation means inputs a second ultrasonic detection signal including a directional displacement component of ultrasonic waves of the first transmission / reception ultrasonic transducer from the second transmission / reception ultrasonic transducer, and alternately performs the second transmission / reception ultrasonic transducer. A first ultrasonic detection signal including a directional displacement component of ultrasonic waves of the transmission / reception ultrasonic transducer is input from the first transmission / reception ultrasonic transducer, and between the first and second ultrasonic detection signals. Is calculated, and the flow velocity V of the fluid to be measured corresponding to the intensity ratio between the first and second ultrasonic detection signals is read out from the storage unit.

A flow rate measuring method according to claim 3 is a flow rate measuring method for measuring a flow rate of a fluid to be measured flowing in a straight portion of a measurement tube by using a directional displacement of an ultrasonic wave,
Wherein mounted on the pipe outer peripheral portion of one side of the measuring tube, first transceiver that transmits ultrasound in a direction substantially perpendicular to the tube axis direction of the measuring tube, receives the ultrasonic wave from the side of the other lateral The ultrasonic transducer and the first transmitting / receiving ultrasonic transducer are attached to a pipe outer peripheral portion on the other side of the measurement tube at a predetermined distance in the tube axis direction of the measurement tube , and the measurement A second transmitting / receiving ultrasonic transducer that transmits ultrasonic waves in a direction substantially orthogonal to the tube axis direction of the tube and receives ultrasonic waves from the other side ;
Use
When the ultrasonic wave is transmitted from the first transmission / reception ultrasonic transducer, the intensity of the first ultrasonic detection signal received by the second transmission / reception ultrasonic transducer is measured, and the second transmission / reception ultrasonic transducer is measured. A measurement step of measuring the intensity of a second ultrasonic detection signal received by the first transmitting / receiving ultrasonic transducer when transmitting ultrasonic waves from the ultrasonic transducer;
A calculation step of calculating the flow velocity of the fluid under measurement from the intensity of the first ultrasonic detection signal and the intensity of the second ultrasonic detection signal measured by the measurement step ;
In the calculation step,
The mounting position of the first transmission / reception ultrasonic transducer is the upstream side of the mounting position of the second transmission / reception ultrasonic transducer, and the fluid to be measured flows in the measuring tube from the upstream side to the downstream side. ,
The distance between the first transmission / reception ultrasonic transducer and the second transmission / reception ultrasonic transducer in the tube axis direction of the measurement tube is L, the inner diameter of the measurement tube is D, and the flow velocity of the fluid to be measured The first transmitting / receiving ultrasonic transducer at the time of measurement of the flow velocity V, where θ is the directivity angle of the ultrasonic wave at “0”, C is the fluid sound velocity of the ultrasonic wave, and V is the flow velocity of the fluid to be measured. An angle indicating the radiation direction of the ultrasonic waves transmitted from the second transmitting / receiving ultrasonic transducer at the time of measuring an arbitrary flow velocity of the fluid to be measured is θ 2. (1) to (3), that is,
θ = tan ⁻¹ (L / D) (1)
θ1 = tan ⁻¹ ( LD / cos (θ) / C × V) / D (2)
θ2 = tan ⁻¹ (L + D / cos (θ) / C × V) / D (3)
And
The value of θ1 is determined based on a table in which the intensity of the first ultrasonic detection signal is associated with the value of θ1.
The value of θ2 is determined based on a table in which the intensity of the second ultrasonic detection signal is associated with the value of θ2 .

According to the ultrasonic flowmeter and the flow measurement method according to the present invention, the ultrasonic flowmeter and the flow measurement method include the first and second transmission / reception ultrasonic transducers that respectively transmit ultrasonic waves from directions substantially orthogonal to the tube axis direction of the measurement tube. The calculation means connected to the transmission / reception ultrasonic transducer inputs an ultrasonic detection signal including a directional displacement component obtained alternately from the transmission / reception ultrasonic transducer, and the flow velocity of the fluid to be measured is determined from the reception intensity of the ultrasonic detection signal. Is calculated.

With this configuration, it is possible to measure the large flow velocity of the fluid to be measured using the directional displacement of the ultrasonic waves transmitted from the first and second transmission / reception ultrasonic transducers. Incidentally, although depending on the dimensions of the pipe and the detector, it is possible to measure a large flow velocity about twice as large as that of a commercially available product (about 30 m / s). In addition, when the first and second transmission / reception ultrasonic transducers are installed, the alignment of the ultrasonic pulse path between the two transmission / reception ultrasonic transducers can be omitted. Also, compared to an ultrasonic flowmeter that makes sound waves enter obliquely, since ultrasonic waves are transmitted from directions substantially perpendicular to the tube axis direction of the measurement tube, they are not affected by the dimensions of the transmission / reception ultrasonic transducer. . As a result, it is possible to provide an ultrasonic flowmeter that can measure a large flow velocity of the fluid to be measured using the directional displacement of the ultrasonic wave.

It is explanatory drawing which shows the structural example of the ultrasonic flowmeter 100 as embodiment which concerns on this invention. (A) And (B) is explanatory drawing which shows the example of a measurement of radiation angle (theta) x and directivity (radiation intensity angle distribution). It is explanatory drawing which shows the operation example at the time of the large flow rate measurement in the ultrasonic flowmeter. It is a block diagram which shows the structural example of the control system of the ultrasonic flowmeter 100 as a 1st Example. 3 is a block diagram showing an example of the internal configuration of the control unit 36. FIG. 3 is a flowchart showing an operation example in the ultrasonic flowmeter 100. It is a block diagram which shows the example of an internal structure of the control part 36 'as a 2nd Example. It is a graph which shows the example of a relationship between I2 ((theta) 1) / I1 ((theta) 2) and the flow velocity V which made the parameter the sound velocity of the flow velocity in the directivity angle of 10 degrees. It is a graph which shows the example of a relationship between I2 ((theta) 1) / I1 ((theta) 2) and the flow velocity V which made the parameter the distance between detector # 1, # 2 in a directivity angle of 10 degrees. It is a flowchart which shows the operation example in the ultrasonic flowmeter 100 which concerns on a 2nd Example. It is explanatory drawing which shows the structural example of the ultrasonic flowmeter 10 which concerns on a prior art example.

Hereinafter, an ultrasonic flowmeter and a flow rate measuring method according to an embodiment of the present invention will be described with reference to the drawings. The ultrasonic flowmeter 100 shown in FIG. 1 calculates the flow rate of the fluid to be measured (liquid, gas, gas, etc.) flowing through the straight portion of the measurement tube and measures the flow rate. The ultrasonic flowmeter 100 includes a first transmission / reception ultrasonic transducer (hereinafter simply referred to as detector # 1), a second transmission / reception ultrasonic transducer (hereinafter simply referred to as detector # 2), and a calculation means 30. Composed.

In this example, when the fluid to be measured flows into the measurement tube is the upstream side, and the side from which the fluid to be measured flows out from the measurement tube is the downstream side, detector # 1 is the upstream side and one of the measurement tubes 3 It is attached to the outer periphery of the tube on the side.
The detector # 1 is fixed to the measurement tube 3 using a tube band (not shown), for example. The measuring tube 3 has a predetermined thickness and an inner diameter D.

Detector # 2 is downstream of detector # 1 and maintains a predetermined distance L in the tube axis direction of measurement tube 3 with respect to detector # 1 and on the other side of measurement tube 3. Attached to the outer periphery of the tube. The distance L is a distance between the arrangement of the detector # 1 and the detector # 2. For example, the distance from the center point of the ultrasonic transmission / reception window part of the detector # 1 to the center point of the ultrasonic transmission / reception window part of the detector # 2. Detector # 2 is also fixed to measuring tube 3 using a tube band.

In this example, an ultrasonic transducer having the transducer 11 and the acoustic matching material 12 is used for the detector # 1. For the detector # 2, an ultrasonic transducer having the vibrator 21 and the acoustic matching material 22 is used. Piezoelectric elements such as piezo elements (PZT) are used for the vibrators 11 and 21. The calculation means 30 is connected to the detector # 1 and the detector # 2.

According to this ultrasonic flowmeter 100, when measuring the flow rate of the fluid to be measured flowing in the straight portion of the measurement tube 3 using the directional displacement of the ultrasonic wave, the detector # 1 is the tube of the measurement tube 3. An ultrasonic wave is transmitted in the direction substantially perpendicular to the axial direction and is received downward, and ultrasonic waves from the other side are alternately received to generate an ultrasonic detection signal I1 (θ2).

Detector # 2 is a direction substantially orthogonal to the tube axis direction of measurement tube 3, transmits ultrasonic waves upward, and alternately receives ultrasonic waves from the other side to detect ultrasonic detection signals. I2 (θ1) is generated. The calculation means 30 receives ultrasonic detection signals I1 (θ2) and I2 (θ1) including directional displacement components obtained alternately from the detector # 1 and the detector # 2, and inputs the ultrasonic detection signal I1 (θ
2) The flow velocity V of the fluid to be measured is calculated from the received intensity of I2 (θ1). An example of the internal configuration of the computing means 30 will be described with reference to FIG.

In the figure, an ellipse Id indicated by a broken line is directional characteristics of the ultrasonic wave in the fluid by the detector # 1 when the flow rate of the fluid to be measured is “0”. In the same figure, an ellipse IId indicated by a broken line is the directivity characteristic in the ultrasonic fluid by the detector # 2 in the same manner. Directional characteristics detector #
1 and detector # 2 and the like, the length of the acoustic matching materials 12 and 22, and the oscillation frequency f0 of the vibrators 11 and 21 and the like. In the figure, a bidirectional arrow III shown by a solid line is a path in the ultrasonic fluid.

Further, θ shown in the figure is a directional angle. Here, the directivity angle θ is an angle determined by the arrangement of the detectors # 1 and # 2, and is an angle formed between the directivity center line L1 (or L2) and the shortest path line L12. The directional center line L1 is a line segment extending in the vertical (vertical) direction from the center point of the transducer 11 (oscillation source) of the detector # 1, and is an ultrasonic directional characteristic (directional characteristics) in the detector # 1. ) Is a line that bisects left and right.

The directivity center line L2 is a line segment extending in the vertical (vertical) direction from the center point of the transducer 21 of the detector # 2, and is a line that bisects the ultrasonic directivity characteristics in the detector # 2 to the left and right. It is. In this example, the shortest path line L12 is a line segment connecting the center point of the transducer 11 of the detector # 1 and the center point of the transducer 21 of the detector # 2, and constitutes the shortest path of ultrasonic waves. Minutes.

Here, with reference to FIGS. 2A and 2B, measurement examples of the radiation angle θx and the directivity (radiation intensity angle distribution) will be described. FIG. 2A is an example of the detector # 2, and the detector # 1 is similarly defined. In FIG. 2A, Lx is a line segment extending in an arbitrary direction from the center point of the detector # 2 described above, and is a line indicating the radiation direction of ultrasonic waves in the directional characteristic (hereinafter referred to as a radiation direction line). ). Here, an angle formed between the directional center line L1 and the radiation direction line Lx is defined as a radiation angle θx. In this example, the radiation angle θ at which the radial line Lx becomes equal to the shortest path line L12.
x = θ is particularly called a directional angle, and the directional angle θ is set to 10 ° (
(See FIG. 1).

In this example, the directivity angle θ is set to 10 ° when the directivity angle θ is large.
Since the received intensity of 1 (θ2) and I2 (θ1) is small, it is desirable that the distance L is smaller than the inner diameter D. However, when the directivity angle θ is close to 0 °, the ultrasonic detection signals I1 (θ2) and I
Since the value of 2 (θ1) is close, it is difficult to accurately obtain the ultrasonic radiation angle θx = angles θ1 and θ2. Therefore, the detector # 1 and the detector # 2 are installed so that the directivity angle θ is about 10 °.

Further, according to the measurement example of the radiation intensity angle distribution for obtaining the directivity characteristic shown in FIG. 2B, for example, an angle θs (= about 12) on the semicircular circumference of the radius R from the center point of the detector # 2. °)
A total of 15 acoustic receivers 24 are arranged. For the acoustic receiver 24, an acoustic emission sensor (AE sensor) or the like is used.

An ultrasonic wave is generated by the detector # 2, and angles 6 °, 18 °, 30 °, 4 corresponding to the radiation angle θx are generated.
2 °, 54 °, 66 °, 78 °, 90 °, 102 °, 114 °, 126 °, 138 °, 1
Ultrasonic waves are received at positions of 50 °, 162 °, and 174 °, and an ultrasonic detection signal I1 (θ2
). The 15 ultrasonic detection signals I1 (θ2) measured here indicate the reception intensity (radiation intensity) depending on the angle.

When the radiation intensity of the ultrasonic detection signal I1 (θ2) is plotted with respect to this angle with respect to the center point of the detector # 2, the directivity characteristic of the ultrasonic wave in the detector # 2 shown in FIG. 2A is obtained. The angle dependency of the radiation intensity does not depend on the medium fluid. The directivity is determined by the dimensions of the detector # 1, the detector # 2, etc., the lengths of the acoustic matching members 12, 22, and the oscillation frequencies f0 of the vibrators 11, 21, etc., but a specific fluid (for example, water ) Should be measured in advance.

The above measurement is performed in the same manner for the detector # 1. 15 angles from these measurements 6
°, 18 °, 30 °, 42 °, 54 °, 66 °, 78 °, 90 °, 102 °, 114 °,
Since 15 ultrasonic detection signals I1 (θ2) corresponding to 126 °, 138 °, 150 °, 162 °, and 174 °, 15 ultrasonic detection signals I2 (θ1) corresponding to each, etc. can be acquired. Based on the ultrasonic detection data DIN = I1 (θ2) and I2 (θ1) after A / D conversion of these, a reference (lookup) table of the ultrasonic detection data DIN versus the radiation angle θx can be created. .

Next, with reference to FIG. 3, a state example of directivity characteristics at the time of measuring a large flow rate in the ultrasonic flowmeter 100 will be described. The fluid to be measured flows from the left side to the right side of the page. Ultrasonic flow meter 10 shown in FIG.
According to the state example of the directivity characteristic at 0, it was confirmed that the directivity characteristic of the ultrasonic wave changes when the flow velocity V becomes larger than that at the time of the flow velocity = “0” shown in FIG. For example, the directivity characteristics of the detectors # 1 and # 2 at the time of measuring a large flow velocity are due to a phenomenon in which ultrasonic waves flow from the upstream side to the downstream side.
It was found that it slopes from the upstream side to the downstream side.

In this example, with respect to the directional center line L1 when the flow velocity at the detector # 1 is “0”, the directional characteristic of the detector # 1 is based on the center point when measuring a large flow velocity (100 m / s, etc.). It inclines so that it may shift to directional center line L1 '. The pointing center line L1 ′ falls from the upstream side to the downstream side. The angle formed between the directional center line L1 and the directional center line L1 ′ is θa.

Similarly, with respect to the directional center line L2 when the flow velocity at the detector # 2 is “0”, the directional characteristic of the detector # 2 is changed to the directional center line L2 ′ with reference to the center point when measuring a large flow velocity. Tilt to transition. The pointing center line L2 ′ also falls from the upstream side to the downstream side. The angle formed between the directional center line L2 and the directional center line L2 ′ is θb. Hereinafter, θa and θb are referred to as directional displacement angles.

On the other hand, the ultrasonic wave received by the detector # 1 is emitted from the detector # 2 at the radiation angle θx = angle θ shown in FIG.
2 (θ2> θ). The angle θ2 is the directivity angle θ + directive displacement angle θb. Further, the ultrasonic wave received by the detector # 2 disposed at a position (directivity angle θ) separated from the detector # 1 by the distance L is the radiation angle θx = angle θ1 (see FIG. 3) from the detector # 1. θ1 <θ
) Of the component emitted in the direction of The angle θ1 is a directivity angle θ−directive displacement angle θa.

Therefore, the ultrasonic detection signal I1 (θ2) output from the detector # 1 at the time of measuring the large flow velocity,
Between the ultrasonic detection signal I2 (θ1) output from the detector # 2, I2 (θ1)> I1
There is a relationship (θ2). The calculation means 30 receives ultrasonic detection signals I1 (θ2) and I2 (θ1) including directional displacement components obtained alternately from the detector # 1 and the detector # 2, and inputs the ultrasonic detection signal I1 (θ2 ), I2 (θ1), or the flow velocity V of the fluid to be measured can be calculated from the difference in the received intensity or the ratio thereof.

Next, an example of the internal configuration of the control system of the ultrasonic flowmeter 100 according to the first embodiment will be described with reference to FIGS. 4 and 5. In FIG. 4, the calculation means 30 includes an oscillator 31 and a transmission unit 3.
2, a transmission / reception switching unit 33, a reception unit 34, an analog / digital (hereinafter referred to as A / D) conversion unit 35, and a control unit 36. The transmission unit 32 has two inputs in1, in2 and one output out1. The output of the oscillator 31 is connected to the input in1 of the transmission unit 32. The control unit 36 has two inputs in1, in2 and three outputs O1-O3. The output O1 of the control unit 36 is connected to the input in2 of the transmission unit 32.

The transmission / reception switching unit 33 includes a set of switches SW1 and SW2 for selecting two circuits 1 and a control terminal Cin. The switches SW1 and SW2 are detector # 1, detector # 2, and transmission unit 32.
The receiver 34 and the controller 36 are connected. The switch SW1 has a contact point a1, a contact point b1, and a middle point c1, and the switch SW2 has a contact point a2, a contact b2, and a middle point c2. An output O2 of the control unit 36 is connected to the terminal Cin.

The contact a1 is connected to the contact a2 and connected to the detector # 1. The contact b1 is connected to the contact b2 and connected to the detector # 2. The midpoint c1 is connected to the output out1 of the transmission unit 32. The midpoint c2 is connected to the input in of the receiving unit 34. The output “out” of the receiver 34 is connected to the input “in” of the A / D converter 35. The output “out” of the A / D converter 35 is connected to the input “in1” of the controller 36.
In this example, the operation unit 14 is connected to the input in2 of the control unit 36, and the display unit 1 is connected to the output O3.
8 is connected.

The control unit 36 includes, for example, a signal angle conversion unit 61, a calculation unit 62, and a memory unit 63 illustrated in FIG.
It is comprised. The signal angle conversion unit 61 is connected to the calculation unit 62. Signal angle converter 6
For example, a read-only memory (ROM) in which the ultrasonic detection data DIN vs. the radiation angle θx is converted into a reference table is used for 1. The arithmetic unit 62 includes a CPU (Central Processing Unit).
Alternatively, a DSP (Digital Signal Processor) or the like is used. The output of the calculation unit 62 is connected to the memory unit 63. For the memory unit 63, a general-purpose memory for work such as RAM (Random Access Memory) is used. The signal angle converter 61 is connected to the A / D converter 35 shown in FIG. These constitute the ultrasonic flowmeter 100.

Next, with reference to FIG. 6, an example of operation at the time of measuring a large flow velocity in the ultrasonic flowmeter 100 will be described with respect to the flow rate measuring method according to the present invention. In this example, the fluid to be measured flows in the measurement tube 3 from the upstream side to the downstream side, and the detector # 1 is attached to the outer periphery of the tube on one side of the measurement tube 3, and the detector # 1 A detector # 2 is attached to the outer peripheral portion of the pipe on the other side of the measurement tube 3 at a downstream side, maintaining a predetermined distance L in the tube axis direction of the measurement tube 3 with respect to the detector # 1. (Directivity angle θ = 10 °).

It is assumed that the ultrasonic flowmeter 100 measures the flow rate of the fluid to be measured flowing in the measuring tube 3 by using the ultrasonic directional displacement. With this as an operating condition, the ultrasonic flowmeter 100 is shown in FIG.
In step ST1 shown in FIG. 2, the control unit 36 waits for a measurement command. The measurement command is issued by, for example, outputting operation data D14 instructing start of measurement from the operation unit 14 to the control unit 36.

The control unit 36 transmits the transmission permission signal S32 and the transmission / reception switching signal S based on the operation data D14.
33 etc. are generated. If there is no measurement command, the operation data D14 is awaited. When there is a measurement command, transmission / reception of ultrasonic waves is started. At this time, the oscillator 31 oscillates an original signal Sf having a predetermined frequency. Based on the transmission permission signal S32, the transmission unit 32 amplifies the original signal Sf and outputs an ultrasonic signal SOUT. The transmission permission signal S32 is output from the control unit 36 to the transmission unit 32.

In step ST2, the control unit 36 performs transmission / reception switching control of the detectors # 1 and # 2. At this time, the control unit 36 supplies a transmission / reception switching signal S33 for operating the transmission / reception switching unit 33. The transmission / reception switching unit 33 switches the switches SW1 and SW2 based on the transmission / reception switching signal S33.
The switching control at is executed.

In this switching control, detector # 1 is first set for transmission and detector # 2 is set for reception, or detector # 2 is first set for transmission and detector # 1 is set for reception. Is set by the transmission / reception switching signal S33. The switch SW1 alternately selects the contact a1 or the contact b1 based on the transmission / reception switching signal S33, and connects to the midpoint c1. The switch SW2 alternately selects the contact point a2 or the contact point b2 based on the transmission / reception switching signal S33 and connects to the midpoint c2.

In the transmission / reception switching unit 33, for example, the control unit 36 is initially set so that the detector # 1 functions as an ultrasonic transducer for transmission and the detector # 2 functions as an ultrasonic transducer for reception. Control the switch SW1 to connect the contact point a1 and the midpoint c1, and
The switch SW2 is controlled so as to connect the contact point b2 and the midpoint c2. By this control, the ultrasonic signal SOUT is output to the detector # 1.

In step ST3, the detector # 1 transmits ultrasonic waves in a direction substantially orthogonal to the tube axis direction of the measurement tube 3. At this time, in the detector # 1, the transducer 11 oscillates ultrasonic waves from the vertical direction with respect to the measurement tube 3 based on the ultrasonic signal SOUT. The ultrasonic wave propagates into the measurement tube 3 through the acoustic matching material 12. As a result, ultrasonic waves can be vertically incident from the detector # 1 into the measuring tube 3.

In step ST4, the detector # 2 receives the ultrasonic wave from the other side. At this time, in the detector # 2, the ultrasonic wave propagating through the measurement tube 3 is picked up via the acoustic matching material 22, the ultrasonic wave is received via the vibrator 21, and the ultrasonic detection signal SIN is generated. Is output. Thereby, for example, the ultrasonic detection signal SIN = I2 (θ1) is obtained from the detector # 2.

In step ST5, the control unit 36 executes transmission / reception switching control. At this time, the control unit 36 supplies the transmission / reception switching signal S33 to the transmission / reception switching unit 33 to execute switching control in the switches SW1 and SW2. In this example, the function of the detector # 1 is switched from transmission to reception, and the function of the detector # 2 is switched from reception to transmission. At this time, the switch SW1 connects the contact b1 and the midpoint c1 based on the transmission / reception switching signal S33. Switch S
W2 connects the contact point a2 and the midpoint c2. Thereby, the ultrasonic signal SOUT is output to the detector # 2.

In step ST6, the detector # 2 transmits an ultrasonic wave in a direction substantially orthogonal to the tube axis direction of the measurement tube 3. At this time, in the detector # 2, the transducer 21 is connected to the measuring tube 3 based on the ultrasonic signal SOUT.
The ultrasonic wave is oscillated from the vertical direction. The ultrasonic wave propagates into the measurement tube 3 through the acoustic matching material 22. As a result, ultrasonic waves can be vertically incident from the detector # 2 into the measuring tube 3.

In step ST7, the detector # 1 receives the ultrasonic wave from the other side. At this time, in the detector # 1, the ultrasonic wave propagating through the measurement tube 3 is picked up via the acoustic matching material 12, the ultrasonic wave is received via the vibrator 11, and the ultrasonic detection signal SIN is generated. Is output. Thereby, for example, the ultrasonic detection signal SIN = I1 (θ2) is obtained from the detector # 1. When the flow velocity V of the fluid to be measured is “0”, there is no difference between the ultrasonic detection signals I1 (θ2) and I2 (θ1).
When the flow velocity V becomes a large flow velocity, a difference occurs between the ultrasonic detection signals I1 (θ2) and I2 (θ1).

In this example, in step ST13, the control unit 36 branches control depending on whether or not there is a measurement end command. However, if there is no measurement end command, the control unit 36 returns to step ST2 and the control unit 36 detects the detector #. The transmission / reception switching control of 1 and # 2 is executed. For example, the function of the detector # 1 is switched from reception to transmission, and the function of the detector # 2 is switched from transmission to reception. In this way, the detectors # 1 and # 2 alternately transmit ultrasonic waves in a direction substantially perpendicular to the tube axis direction of the measurement tube 3, and the detectors # 1 and # 2 alternately transmit from the other side. Receive ultrasound.

In this example, the flow velocity calculation operation is executed below in parallel with the above transmission / reception operation. That is, in step ST8, the receiving unit 34 inputs the ultrasonic detection signal SIN including the directional displacement component obtained alternately from the detector # 1 and the detector # 2, amplifies the ultrasonic detection signal SIN, and performs A / The data is output to the D converter 35.

In step ST9, the A / D conversion unit 35 performs analog / digital conversion on the amplified ultrasonic detection signal SIN, and outputs the ultrasonic detection data DIN after A / D conversion to the signal angle conversion unit 61.
In step ST10, the signal angle conversion unit 61 receives the ultrasonic detection data DIN from the A / D conversion unit 35.
= I2 (θ1) and ultrasonic detection data DIN = I1 (θ2) are alternately input.

In the signal angle conversion unit 61, for example, referring to a lookup table, the ultrasonic detection data DIN = I2 (θ1) is converted into a radiation angle θx = θ1 indicating the ultrasonic radiation direction of the detector # 1, The ultrasonic detection data DIN = I1 (θ2) is alternately converted into a radiation angle θx = θ2 indicating the radiation direction of the ultrasonic wave of the detector # 2.

The ultrasonic detection data DIN = I2 (θ1) includes the ultrasonic directional displacement component of the detector # 1, and the ultrasonic detection data DIN = I1 (θ2) includes the ultrasonic directivity of the detector # 2. Sex displacement component is included. The look-up table includes a radiation angle θx = θ1 and ultrasonic detection data DIN = I.
2 (θ1), radiation angle θx = θ2 and ultrasonic detection data DIN = I1 (θ2)
The relationship between and is previously determined and created.

In step ST11, the calculation unit 62 alternately outputs the detector # 1 from the signal angle conversion unit 61.
The radiation angle θx = θ1 indicating the radiation direction of the ultrasonic wave and the radiation angle θx = θ2 indicating the radiation direction of the ultrasonic wave of the detector # 2 are input, and the radiation angle θx = indicating the reception intensity of the ultrasonic detection signal SIN θ1, θ
2. Calculate (reverse calculation) the flow velocity of the fluid to be measured from 2.

For example, the calculation unit 62 is a case where the fluid to be measured flows in the measurement tube 3 from the upstream side to the downstream side, and calculates the distance between the detector # 1 and the detector # 2 in the tube axis direction of the measurement tube 3 And measuring tube 3
Is defined as D, the directivity angle of the ultrasonic wave at the flow velocity “0” of the fluid to be measured is θ, the sound velocity in the ultrasonic fluid (hereinafter referred to as fluid sound velocity) is C, and the flow velocity of the fluid to be measured is V. The radiation angle indicating the radiation direction of the ultrasonic wave transmitted from the detector # 1 when measuring the flow velocity V is θ1, and the ultrasonic wave transmitted from the detector # 2 when measuring the arbitrary flow velocity of the fluid to be measured When the radiation angle indicating the radiation direction is θ2, the equations (1) to (3), that is,
θ = tan ⁻¹ (L / D) (1)
θ1 = tan ⁻¹ (LD / cos (θ) / C × V) / D (2)
θ2 = tan ⁻¹ (L + D / cos (θ) / C × V) / D (3)
Is calculated. The distance L, the inner diameter D, the directivity angle θ, and the fluid sound velocity C are known, and the triangular ratio of tan 10 ° is 0.176≈0.18. The calculator 62 is configured to back-calculate the flow velocity V from the radiation angles θx = θ1 and θ2 (measurement principle). By this calculation, detector # 1 and detector # 1
The flow velocity of the fluid to be measured can be measured using the directional displacements of the ultrasonic waves transmitted from 2 respectively. In addition, when the detector # 1 and the detector # 2 are installed, the alignment of the ultrasonic pulse path between the two transmission / reception ultrasonic transducers can be omitted.

In step ST12, the display unit 18 displays the flow velocity V, the flow rate Q, and the like based on the display data D18. The flow rate Q is calculated as Q = A · V, where A is the cross-sectional area of the measuring tube 3. The display data D18 is data for displaying the flow velocity V, the flow rate Q, and the like, and is output from the control unit 36 to the display unit 18. Thereafter, in step ST13, when there is a measurement end command, the control unit 36 ends the ultrasonic flow rate measurement.

Thus, according to the ultrasonic flowmeter 100 and the flow rate measuring method as the first embodiment, the detector # 1 that alternately transmits ultrasonic waves from the vertical direction substantially orthogonal to the tube axis direction of the measurement tube 3. , #
2 and an operation means 30 connected to the detectors # 1 and # 2 inputs an ultrasonic detection signal SIN including a directional displacement component obtained alternately from the detectors # 1 and # 2, and detects ultrasonic waves. The flow velocity V of the fluid to be measured is calculated (back calculated) from the received intensity of the signal SIN.

By this calculation, the flow velocity V and the flow rate Q of the fluid to be measured can be measured using the directional displacement of the ultrasonic waves transmitted alternately from the detectors # 1 and # 2. In addition, when the detectors # 1 and # 2 are installed, the alignment of the ultrasonic pulse path between the two detectors # 1 and # 2 can be omitted. In addition, compared with an ultrasonic flowmeter that injects sound waves obliquely, since the ultrasonic waves are transmitted from the vertical direction substantially orthogonal to the tube axis direction of the measurement tube 3, the influence of the dimensions of the detectors # 1 and # 2 is reduced. You will not receive it.

The pulse path of the ultrasonic wave changes at a high flow velocity, and the change amount of the ultrasonic wave path is reflected in the reception intensity of the ultrasonic wave detection signal SIN as a directional displacement parameter. For this reason, when the flow velocity is large, the large flow velocity can be calculated from the directional displacement reflected in the reception intensity of the ultrasonic detection signal SIN. Although it depends on the dimensions of the piping and detectors # 1 and # 2, it is a commercially available product (30 m / s
A large flow velocity about twice as large as that). Accordingly, it is possible to provide the ultrasonic flowmeter 100 that measures the flow velocity V and the flow rate Q of the fluid to be measured using the directional displacement of the ultrasonic waves.

The calculating means 30 is not limited to the control unit 36 having the function of calculating the flow velocity V from the radiation angles θx = θ1 and θ2 described above, and an ultrasonic detection signal as shown in the second embodiment. The control unit 36 may be configured to calculate the flow velocity V of the fluid to be measured in accordance with the ratio of the received intensity between I2 (θ1) and the ultrasonic detection signal I1 (θ2).

Next, an example of the internal configuration of the control unit 36 ′ according to the second embodiment will be described with reference to FIGS. In this example, in the calculation means 30 shown in FIG. 4, the control unit 36 is applied in place of the control unit 36 ′.

The control unit 36 ′ illustrated in FIG. 7 includes an arithmetic unit 64 and a memory unit 65. The memory unit 65 (storage unit) is connected to the calculation unit 64. For the calculation unit 64, a CPU, a DSP, or the like is used. In the memory unit 65, the intensity ratio between the ultrasonic detection signal I2θ1) and the ultrasonic detection signal I1 (θ2) using the fluid sound velocity C or the distance L between the detector # 1 and the detector # 2 as a parameter. The relationship with the flow velocity V of the fluid to be measured corresponding to is stored as a reference table. For example, a read-only memory (ROM) or the like is used for the memory unit 65.

Here, referring to FIG. 8, ultrasonic detection signals I2 (θ1) and I1 (
An example of the relationship between the received intensity ratio I2 (θ1) / I1 (θ2) of θ2) and the flow velocity V will be described.
In FIG. 8, the vertical axis represents the flow velocity V [m / s] of the fluid to be measured. The flow velocity V is shown on a semi-log scale. The horizontal axis represents the reception intensity ratio I2 (θ1) of the ultrasonic detection signals I2 (θ1) and I1 (θ2).
) / I1 (θ2). The received intensity ratio I2 (θ1) / I1 (θ2) is shown on an equally divided scale.

The solid rhombus mark on the solid line is the directivity angle 10 °, the inner diameter D = 1 [m], the distance L = 0.18 [m], and the flow velocity V vs. received intensity ratio when the fluid sound velocity is 500 [m / s]. I2 (θ1) / I1 (θ2)
It is a relationship curve. The solid squares with black squares indicate a directivity angle of 10 °, an inner diameter D = 1 [m], and a distance L =
This is a relationship curve of the flow velocity V to the received intensity ratio I2 (θ1) / I1 (θ2) when the fluid sound velocity is 1480 [m / s] in the case of 0.18 [m]. When the temperature changes, the fluid sound speed C changes. In water 0 ° C. to 100 ° C., the fluid sound velocity C changes by about 7%. Fluid sound velocity C due to temperature rise
Becomes faster. Oil differs by an order of magnitude.

In this example, the flow velocity V to the reception intensity ratio I2 (θ1) / I1 when the fluid sound velocity is 500 [m / s].
According to the relationship curve of (θ2), the flow velocity V changes greatly when the reception intensity ratio I2 (θ1) / I1 (θ2) is in the range of 1 to 5. According to the graph, I2 (θ1) / I1 (θ2) is “
1 ”and the flow velocity V is 2 [m / s], and I2 (θ1) / I1 (θ2) is“ 1.2 ”and the flow velocity V.
Is 10 [m / s], I2 (θ1) / I1 (θ2) is “1.4”, and the flow velocity V is 20 [m
/ S], I2 (θ1) / I1 (θ2) is “2.05”, the flow velocity V is 50 [m / s], and I2 (θ1) / I1 (θ2) is “4.8”. The flow velocity V is 100 [m / s].

Further, when the fluid sound velocity = 1480 [m / s], the flow velocity V vs. received intensity ratio I2 (θ1) / I1 (θ
According to the relationship curve of 2), the received intensity ratio I2 (θ1) / I1 (θ2) is in the range of 1 to 2,
The flow velocity V has changed greatly. According to the graph, I2 (θ1) / I1 (θ2) is “1”.
The flow velocity V is 1 to 10 [m / s], I2 (θ1) / I1 (θ2) is “1.08”, the flow velocity V is 20 [m / s], and I2 (θ1) / I1 ( θ2) is “1.6” and the flow velocity V is 50.
[M / s], I2 (θ1) / I1 (θ2) is “7.1”, and the flow velocity V is 100 [m / s].
]. Thus, if the flow velocity V increases, the received intensity ratio I2 (θ1) / I1 (θ2)
The flow velocity V is obtained from the received intensity ratio I2 (θ1) / I1 (θ2) using the characteristic that becomes larger.

Next, an example of the relationship between I (θ1) / I (θ2) and the flow velocity using the distance L between the detectors # 1 and # 2 at a directivity angle of 10 ° as a parameter will be described with reference to FIG. . In FIG. 9, the vertical axis represents the flow velocity V [m / s] of the fluid to be measured. The flow velocity V is shown on a semi-log scale.
The horizontal axis represents the received intensity ratio I2 (θ1) / I1 (I2 (θ1), I1 (θ2).
θ2). The received intensity ratio I2 (θ1) / I1 (θ2) is shown on an equally divided scale. The solid rhombus marks on the solid line indicate a directivity angle of 10 °, an inner diameter D = 1 [m], a fluid sound velocity = 1480 [m / s],
It is a relationship curve of the flow velocity V versus the reception intensity ratio I2 (θ1) / I1 (θ2) when the distance L = 0.18 [m]. The solid squares on the solid line indicate a directivity angle of 10 °, an inner diameter D = 1 [m], and a fluid sound velocity = 1480.
[M / s], distance L = 0.36 [m] Flow velocity V vs. received intensity ratio I2 (θ1) / I1 (θ2)
). A solid triangle indicates a solid angle with a directivity angle of 10 °, an inner diameter D = 1 [m], a fluid sound velocity = 1480 [m / s], a distance L = 0.58 [m], and a flow velocity V to reception intensity ratio I2 ( θ1)
It is a relationship curve of / I1 (θ2).

In this example, the flow velocity V vs. received intensity ratio I2 (θ1) / I1 (θ2) when the distance L = 0.18 [m].
According to the relationship curve), the flow velocity V changes greatly when the received intensity ratio I2 (θ1) / I1 (θ2) is in the range of 1 to 2. According to the graph, I2 (θ1) / I1 (θ2) is “1”, the flow velocity V is 1 to 10 [m / s], and I2 (θ1) / I1 (θ2) is “1.08”. The flow velocity V is 20 [m / s], I2 (θ1) / I1 (θ2) is “2.8”, and the flow velocity V is 50 [
m / s], I2 (θ1) / I1 (θ2) is “6.6”, and the flow velocity V is 100 [m / s].
It is.

Further, according to the relationship curve of the flow velocity V to the reception intensity ratio I2 (θ1) / I1 (θ2) at the distance L = 0.36 [m], the reception intensity ratio I2 (θ1) / I1 (θ2) is 1 to 1. Within the range of 3, the flow velocity V
Has changed significantly. According to the graph, I2 (θ1) / I1 (θ2) is “1”, the flow velocity V is 1 to 2 [m / s], and I2 (θ1) / I1 (θ2) is “1.08”. Flow velocity V is 5
[M / s], I2 (θ1) / I1 (θ2) is “1.5”, and the flow velocity V is 10 [m / s].
I2 (θ1) / I1 (θ2) is “2.8” and the flow velocity V is 20 [m / s].
2 (θ1) / I1 (θ2) is “3” and the flow velocity V is 100 [m / s].

Further, according to the relationship curve of the flow velocity V to the reception intensity ratio I2 (θ1) / I1 (θ2) when the distance L = 0.58 [m], the reception intensity ratio I2 (θ1) / I1 (θ2) is 1 to 1. Within the range of 5, the flow velocity V
Has changed significantly. According to the graph, I2 (θ1) / I1 (θ2) is “1”, the flow velocity V is 1 to 2 [m / s], and I2 (θ1) / I1 (θ2) is “1.08”. Flow velocity V is 5
[M / s], I2 (θ1) / I1 (θ2) is “1.5”, and the flow velocity V is 10 [m / s].
I2 (θ1) / I1 (θ2) is “2.8” and the flow velocity V is 20 [m / s].
2 (θ1) / I1 (θ2) is “3” and the flow velocity V is 100 [m / s].

Further, according to the relationship curve of the flow velocity V to the reception intensity ratio I2 (θ1) / I1 (θ2) when the distance L = 0.58 [m], the reception intensity ratio I2 (θ1) / I1 (θ2) is 1 to 1. Within the range of 5, the flow velocity V
Has changed significantly. According to the graph, I2 (θ1) / I1 (θ2) is “1” and the flow velocity V is 1 [m / s], and I2 (θ1) / I1 (θ2) is “1.5” and the flow velocity V. Is 5 [m /
s], I2 (θ1) / I1 (θ2) is “2.8”, the flow velocity V is 10 [m / s], and I2 (θ1) / I1 (θ2) is “4.8”. V is 20 [m / s] and I2 (θ
1) / I1 (θ2) is “2.2”, the flow velocity V is 50 [m / s], and I2 (θ1) / I1
(Θ2) is “5” and the flow velocity V is 100 [m / s].

When the flow velocity V increases in this way, the flow velocity V is obtained from the reception intensity ratio I2 (θ1) / I1 (θ2) using the characteristic that the reception intensity ratio I2 (θ1) / I1 (θ2) also increases. Made.

Subsequently, an operation example of the ultrasonic flowmeter 100 according to the second embodiment will be described with reference to FIG. In this example, steps ST10 ′ and S in the flowchart shown in FIG.
Refer to T11 ′ by replacing it with steps ST10 and ST11 in the flowchart shown in FIG. Since other operations are the same as those of the first embodiment, description thereof is omitted.

In this example, in step ST9 described in the first embodiment, the A / D converter 35 performs analog / digital conversion on the amplified ultrasonic detection signal SIN, and the ultrasonic detection data D after A / D conversion.
IN is output to the calculation unit 64 shown in FIG.

Thereafter, in step ST10 ′, the calculation unit 64 inputs ultrasonic detection data DIN = I2 (θ1) including the ultrasonic directional displacement component of the detector # 1 from the A / D conversion unit 35, and alternately detects the detectors. The ultrasonic detection data DIN = I1 (θ2) including the directional displacement component of the ultrasonic wave # 2 is input from the A / D converter 35, and the ultrasonic detection data DIN = I2 (θ1) and the ultrasonic detection data DIN = I
The reception intensity ratio I2 (θ1) / I1 (θ2) between 1 (θ2) is calculated.

In step ST11 ′, the calculation unit 64 uses the intensity ratio between the ultrasonic detection data DIN = I (θ1) and the ultrasonic detection data DIN = I (θ2) as an address, and detects the ultrasonic detection data D.
Received intensity ratio I2 (θ1) between IN = I2 (θ1) and ultrasonic detection data DIN = I1 (θ2)
) / I1 (θ2), the flow velocity V of the fluid to be measured is read from the memory unit 65. The memory unit 65 stores a look-up table obtained by converting the relation curve shown in FIG. 8 or FIG. 9 into a reference table. Thereafter, in step ST12 described in the first embodiment,
The display unit 18 displays the flow velocity V, the flow rate Q, and the like based on the display data D18.

As described above, according to the ultrasonic flowmeter 100 as the second embodiment, the calculation unit 30 includes the control unit 36 ', and reception between the ultrasonic detection data DIN = I2 (θ1) and I1 (θ2). The intensity ratio I2 (θ1) / I1 (θ2) is calculated, and the memory unit 65 is controlled so as to read the flow velocity V from the relationship curves shown in FIGS.

By this control, the flow velocity V and the flow rate Q of the fluid to be measured can be measured using the directional displacement of the ultrasonic waves transmitted alternately from the detectors # 1 and # 2. In addition to the same effects as those of the first embodiment, the calculation of the radiation angles θx = θ1 and θ2 can be omitted.

When the flow velocity V is small (for example, less than 30 m / s), switch to the passing time difference method as in the prior art and use the input waveform of the ultrasonic detection data DIN = I2 (θ1), I1 (θ2) as they are. Then, the flow velocity V may be obtained by looking at the time difference.

The present invention is extremely suitable when applied to a flow meter that can measure a large flow velocity of a fluid to be measured by utilizing a directional displacement of ultrasonic waves.

# 1 detector (first transmitting / receiving ultrasonic transducer)
# 2 Detector (second transmitting / receiving ultrasonic transducer)
DESCRIPTION OF SYMBOLS 3 Measuring tube 11, 21 Vibrator 12,22 Acoustic matching material 14 Operation part 18 Display part 30 Calculation means 31 Oscillator 32 Transmission part 33 Transmission / reception switching part 34 Reception part 35 A / D conversion part 36, 36 'Control part 61 Signal angle Conversion unit 62, 64 Calculation unit 63, 65 Memory unit (storage unit)
100 Ultrasonic flow meter

Claims (3)

An ultrasonic flowmeter that measures the flow rate of a fluid to be measured flowing through a straight portion of a measurement tube,
Wherein mounted on the pipe outer peripheral portion of one side of the measuring tube, first transceiver that transmits ultrasound in a direction substantially perpendicular to the tube axis direction of the measuring tube, receives the ultrasonic wave from the side of the other lateral An ultrasonic transducer,
A predetermined distance is maintained in the tube axis direction of the measurement tube with respect to the first transmission / reception ultrasonic transducer, and the tube is attached to the outer periphery of the tube on the other side of the measurement tube. transmitting ultrasonic waves in a direction substantially orthogonal, and the second transmitter ultrasonic transducer for receiving ultrasonic waves from the side of the other hand,
When the ultrasonic wave is transmitted from the first transmission / reception ultrasonic transducer, the intensity of the first ultrasonic detection signal received by the second transmission / reception ultrasonic transducer is measured, and the second transmission / reception ultrasonic transducer is measured. Measuring means for measuring the intensity of the second ultrasonic detection signal received by the first transmission / reception ultrasonic transducer when transmitting ultrasonic waves from the ultrasonic transducer;
Calculating means for calculating the flow velocity of the fluid under measurement from the intensity of the first ultrasonic detection signal and the intensity of the second ultrasonic detection signal measured by the measuring means ;
The computing means is
The mounting position of the first transmission / reception ultrasonic transducer is the upstream side of the mounting position of the second transmission / reception ultrasonic transducer, and the fluid to be measured flows in the measuring tube from the upstream side to the downstream side. ,
The distance between the first transmission / reception ultrasonic transducer and the second transmission / reception ultrasonic transducer in the tube axis direction of the measurement tube is L, the inner diameter of the measurement tube is D, and the flow velocity of the fluid to be measured The first transmitting / receiving ultrasonic transducer at the time of measurement of the flow velocity V, where θ is the directivity angle of the ultrasonic wave at “0”, C is the fluid sound velocity of the ultrasonic wave, and V is the flow velocity of the fluid to be measured. An angle indicating the radiation direction of the ultrasonic waves transmitted from the second transmitting / receiving ultrasonic transducer at the time of measuring an arbitrary flow velocity of the fluid to be measured is θ 2. (1) to (3), that is,
θ = tan ⁻¹ (L / D) (1)
θ1 = tan ⁻¹ ( LD / cos (θ) / C × V) / D (2)
θ2 = tan ⁻¹ (L + D / cos (θ) / C × V) / D (3)
And
The value of θ1 is determined based on a table in which the intensity of the first ultrasonic detection signal is associated with the value of θ1.
The value of θ2 is determined based on a table in which the intensity of the second ultrasonic detection signal and the value of θ2 are associated with each other. Corresponding to the intensity ratio between the first and second ultrasonic detection signals with the fluid sound velocity C or the distance L between the first transmission / reception ultrasonic transducer and the second transmission / reception ultrasonic transducer as a parameter. A storage unit for storing a relationship with the flow velocity V of the fluid to be measured as a reference table;
The calculation means inputs a second ultrasonic detection signal including a directional displacement component of ultrasonic waves of the first transmission / reception ultrasonic transducer from the second transmission / reception ultrasonic transducer, and alternately performs the second transmission / reception ultrasonic transducer. A first ultrasonic detection signal including a directional displacement component of ultrasonic waves of the transmission / reception ultrasonic transducer is input from the first transmission / reception ultrasonic transducer, and between the first and second ultrasonic detection signals. of the intensity ratios calculated, according to the flow velocity V of the fluid to be measured that corresponds to the intensity ratio between the first and second ultrasonic detection signals to claim 1, characterized in that read from the storage unit Ultrasonic flow meter. A flow rate measuring method for measuring a flow rate of a fluid to be measured flowing in a straight portion of a measurement tube using a directional displacement of an ultrasonic wave,
Wherein mounted on the pipe outer peripheral portion of one side of the measuring tube, first transceiver that transmits ultrasound in a direction substantially perpendicular to the tube axis direction of the measuring tube, receives the ultrasonic wave from the side of the other lateral The ultrasonic transducer and the first transmitting / receiving ultrasonic transducer are attached to a pipe outer peripheral portion on the other side of the measurement tube at a predetermined distance in the tube axis direction of the measurement tube , and the measurement A second transmitting / receiving ultrasonic transducer that transmits ultrasonic waves in a direction substantially orthogonal to the tube axis direction of the tube and receives ultrasonic waves from the other side ;
Use
When the ultrasonic wave is transmitted from the first transmission / reception ultrasonic transducer, the intensity of the first ultrasonic detection signal received by the second transmission / reception ultrasonic transducer is measured, and the second transmission / reception ultrasonic transducer is measured. A measurement step of measuring the intensity of a second ultrasonic detection signal received by the first transmitting / receiving ultrasonic transducer when transmitting ultrasonic waves from the ultrasonic transducer;
A calculation step of calculating the flow velocity of the fluid under measurement from the intensity of the first ultrasonic detection signal and the intensity of the second ultrasonic detection signal measured by the measurement step ;
In the calculation step,
The mounting position of the first transmission / reception ultrasonic transducer is the upstream side of the mounting position of the second transmission / reception ultrasonic transducer, and the fluid to be measured flows in the measuring tube from the upstream side to the downstream side. ,
The distance between the first transmission / reception ultrasonic transducer and the second transmission / reception ultrasonic transducer in the tube axis direction of the measurement tube is L, the inner diameter of the measurement tube is D, and the flow velocity of the fluid to be measured The first transmitting / receiving ultrasonic transducer at the time of measurement of the flow velocity V, where θ is the directivity angle of the ultrasonic wave at “0”, C is the fluid sound velocity of the ultrasonic wave, and V is the flow velocity of the fluid to be measured. An angle indicating the radiation direction of the ultrasonic waves transmitted from the second transmitting / receiving ultrasonic transducer at the time of measuring an arbitrary flow velocity of the fluid to be measured is θ 2. (1) to (3), that is,
θ = tan ⁻¹ (L / D) (1)
θ1 = tan ⁻¹ ( LD / cos (θ) / C × V) / D (2)
θ2 = tan ⁻¹ (L + D / cos (θ) / C × V) / D (3)
And
The value of θ1 is determined based on a table in which the intensity of the first ultrasonic detection signal is associated with the value of θ1.
The value of θ2 is determined based on a table in which the intensity of the second ultrasonic detection signal and the value of θ2 are associated with each other.

Images