JPH0755521A - Ultrasonic flow rate measuring instrument - Google Patents

Abstract

PURPOSE:To dispense from fine adjustment of the fitting position of a pair of transducers to a conduit. CONSTITUTION:Each transducer 7 is composed of an ultrasonic sensor 1, angle variagle device 2, pedestal 4, and matching medium 5. The device 2 is formed by cutting a cylindrical member made of the same material as that of the pedestal 4 into halves along a plane containing its central axis and the sensor 1 is fitted to the central part of the flat section of the device 2. The pedestal 4 has such a concave surface that the outer peripheral surface of the device 2 can be brought into face-contact with and swung on the concave surface on its slope and the device 2 is put in the concave section with a matching medium 5 in between. Therefore, when the device 2 is rotationally adjusted, the direction of transmitting and receiving directions of a pair of transducers 7 can be accurately made coincident with each other even when the fitting positions of the transducers 7 are not finely adjusted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention eliminates the need for fine adjustment of the mounting positions of a pair of wave transmitters / receivers with respect to the conduit by using a wave transmitter / receiver whose wave transmission / reception direction is adjustable, and accurately measures the flow rate. The present invention relates to an ultrasonic flow rate measuring device.

[0002]

2. Description of the Related Art In a conventional general ultrasonic flow rate measuring device, a pair of ultrasonic wave transmitters / receivers are installed on the outer periphery of a conduit through which a fluid flows, and a forward direction having a component in the fluid flow direction and a component in the reverse direction have a component. The ultrasonic waves are propagated in both directions, i.e., in the opposite direction, and the flow velocity and flow rate of the fluid are measured based on the time difference between the propagation times. FIG. 4 is a side sectional view showing the operation of the conventional example. In the figure, when the conduit 6 is cut in a plane (paper surface) including its axis and the fluid flows in the direction of the arrow, one of the transducers is provided upstream of the flow on the outer periphery of the conduit 6 in the upstream direction.
The other transducer 10 is installed on the downstream side of the lower part of the outer circumference. Here, in each of the wave transmitters / receivers 10, an ultrasonic sensor (vibrator) 1 is attached to the slope of the pedestal 9. In addition, between the ultrasonic sensor 1 and the slope of the pedestal 9, and also between the bottom surface of the pedestal 9 and the conduit 9
A matching medium is inserted between the outer peripheral surface and the outer peripheral surface to improve the propagation efficiency of ultrasonic waves. Now, the upper transducer
When an ultrasonic wave is transmitted from 10 at an incident angle Φ o, it propagates while refracting at each refraction angle Φ 1, Φ 2 at each boundary between the conduit 6 and the fluid according to Snell's law, and then the opposite relationship. It is refracted by and is received by the lower wave transmitter / receiver 10. If the time difference between the forward propagation time at this time and the backward propagation time when the ultrasonic wave is propagated from the downstream side transducer 10 to the upstream side transducer 10 is ΔT, the flow velocity V = It is represented by ΔTc ² / 2L. Here, c is the speed of sound in the fluid, and L is the axial component of the ultrasonic wave propagation path length in the fluid. There is also a method in which a pair of wave transmitters / receivers are installed on the outer peripheral surface on the same side, and a wave transmitted from one is reflected on the inner surface of the conduit and then received by the other.
Since there is no essential difference, the method explained here will be considered.

[0003]

The conventional example has the following problems. The intervals at which each transducer 10 is installed in the conduit 6 are determined by the incident angle Φo related to the transmission of the transducer 10 and the conduit 6
It is designed based on the inner diameter of the tube and the tube thickness. If the actual inner diameter and thickness of the conduit 6 have errors with respect to the design values, it is necessary to adjust the installation interval according to the dimensional error. If this is not done, the transmission from one of the wave transmitters / receivers 10 cannot be accurately received by the other, which in turn makes accurate flow measurement impossible.
The adjustment of the installation intervals of the respective transducers 10 is very troublesome and requires skill. The less accurate this adjustment, the more inaccurate the flow measurement. Moreover, the error between the inner diameter and the pipe thickness of the actual conduit 6 and the design value is usually caused to some extent but usually to some extent. There has been a long-standing need for adjustment of this installation interval.

An object of the present invention is to solve the above-mentioned problems of the prior art, to eliminate the need for fine adjustment of the mounting positions of the pair of transducers with respect to the conduits, and to ultrasonically measure the flow rate accurately. It is to provide a flow rate measuring device.

[0005]

An ultrasonic flow rate measuring apparatus according to a first aspect of the present invention has a pair of ultrasonic wave transmitters / receivers installed on the outer circumference of a conduit through which a fluid flows, and has a forward direction having a component in the fluid flow direction. , In a device that measures the flow velocity and flow rate of a fluid based on the time difference of each propagation time when ultrasonic waves are propagated bidirectionally with the opposite direction having a component in the opposite direction, each transducer is a cylinder An angle variator having a shape in which is cut by a plane passing through the axis; and a cylindrical concave surface that is in oscillating surface contact with a cylindrical outer peripheral surface of the angle variator through an acoustic matching medium, A pedestal made of the same material as the variator and installed on the outer circumference of the conduit; and an ultrasonic sensor provided at the central portion of the plane portion of the angle variator with its radial direction and the transmitting / receiving direction aligned.

An ultrasonic flow rate measuring device according to a second aspect is the device according to the first aspect, in which the rotational position of the angle varying device with respect to the pedestal is set so that the received signal has a maximum value before the flow rate measurement. The actuator is provided. In the ultrasonic flow rate measuring device according to claim 3, a pair of ultrasonic wave transmitters / receivers are installed on the outer circumference of a conduit through which a fluid flows, and a forward direction having a component in the fluid flow direction and a reverse direction having a component in the reverse direction. In a device that measures the flow velocity and flow rate of a fluid based on the time difference of each propagation time when ultrasonic waves are propagated bidirectionally, the transducer is cut in a plane through which a sphere passes An angle variator having a shape having a portion; and a spherical concave surface that is in surface contact with the spherical surface of the angle variator so as to freely swing through an acoustic matching medium, and is made of the same material as the angle variator,
A pedestal installed on the outer circumference of the conduit; and an ultrasonic sensor provided at the central portion of the plane portion of the angle varying device so that the radial direction and the transmitting / receiving direction coincide with each other.

[0007]

In the ultrasonic flow rate measuring device according to the first or second aspect, the ultrasonic sensor is provided at the central portion of the plane portion of the angle varying device, and the angle varying device is provided on the outer peripheral surface of the cylinder through the acoustic matching medium. The rocking displacement is possible while making surface contact with the cylindrical concave surface of the pedestal. Therefore, the transmitting / receiving direction of the ultrasonic sensor can be adjusted in a plane. By adjusting the transmission / reception direction, the transmission from one can be accurately received by the other.

Particularly, in the ultrasonic flow rate measuring device according to the second aspect, each transducer is rotationally positioned with respect to the pedestal by the actuator before the flow rate measurement so that the received signal becomes the maximum value. Thus, the transmission from one side can be accurately received by the other. In the ultrasonic flow rate measuring device according to claim 3, an ultrasonic sensor is provided at a central portion of a plane portion of the angle varying device, and the angle varying device serves as a spherical concave surface of the pedestal with a spherical surface thereof through an acoustic matching medium. It is possible to freely swing and displace while making surface contact. Therefore, the transmitting / receiving direction of the ultrasonic sensor can be freely adjusted. By adjusting the transmission / reception direction, the transmission from one can be accurately received by the other.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an ultrasonic flow rate measuring device according to the present invention will be described below with reference to the drawings. Figure 1
It is a side view of the wave transceiver in a 1st example. The transducer 7 according to the first embodiment mainly comprises an ultrasonic sensor 1, an angle varying device 2, a pedestal 4, and a matching medium 5. The angle varying device 2 has a shape in which a cylindrical member made of the same material as the pedestal 4 is cut in half in a plane including the axis, and the ultrasonic sensor 1 is attached to the central portion of the plane portion. Therefore, the ultrasonic sensor
The transmission and reception direction of 1 coincides with the radial direction of the angle variable device 2.
The pedestal 4 is a member directly installed on the outer peripheral surface of the conduit as in the conventional example, and has a cylindrical concave surface on which the outer peripheral surface of the angle varying device 2 is in surface contact with and can swing. This pedestal 4
The angle varying device 2 is fitted into the concave portion of the via the matching medium 5.
In the direction of transmission and reception of the ultrasonic sensor 1, the angle variable device 2 is mounted on the base 4
It is fitted into the concave portion of the angle varying device 2 and is guided so as to be swingable around an axis P which passes through the center of the plane of the angle varying device 2 and is perpendicular to the paper surface. Therefore, when the angle variable device 2 is in the solid line position, the solid arrow indicates the wave transmission / reception direction, and when the angle variable device 2 is in the two-dot chain line position, the two-dot chain line arrow indicates the wave transmission / reception direction.

FIG. 2 is a side sectional view showing the operation of the wave transceiver in the first embodiment. One of the transducers 7 is installed on the upper left side of the outer peripheral surface of the conduit 6, and the other is installed on the lower right side of the same. If the inner diameter and tube thickness of the conduit 6 are as designed, the pair of transducers 7 are installed at the positions indicated by the solid lines in the figure, and the flat surface of the angle variable device 2 is aligned with the slope of the pedestal 4. At this time, the waves are transmitted and received accurately. If conduit 6
If the actual values of the inner diameter and tube thickness of the tube have some errors with respect to the design values, in order to transmit and receive accurately with each pair of transducers 7 as they are, the transducer 7 on the lower right side Must be installed in position. That is, it becomes necessary to finely adjust the mounting position. At this time, if each angle variable device 2 is slightly rotated clockwise with respect to the corresponding pedestal 4 and positioned as shown by the solid line, the pair of transducers 7 can be connected to each other without fine adjustment of the mounting position. It will be transmitted and received accurately.

Although not shown in the drawings, the second embodiment uses a hemispherical angle changer that is cut in half in a plane passing through the center, unlike the angle changer 2 in the first embodiment. In addition, a pedestal corresponding to this is engraved with a hemispherical recess. The ultrasonic sensor 1 is attached to the center of the plane of the angle varying device, and changes the direction of the transmitted and received waves in three dimensions as the angle varying device freely swings with respect to the pedestal. Adjustable. That is,
In the first embodiment, the direction of the transmitted / received wave is only changed within the plane, whereas in the second example, the direction of the transmitted / received wave can be deviated from the plane and changed three-dimensionally. This means that the mounting positions of the pair of transducers can be adjusted not only in the axial direction of the conduit in the first embodiment but also in the axial direction of the conduit in the second embodiment and at a right angle thereto. Therefore, the adjustable range is expanded, and the adjustment work on site becomes appropriate and easy. The second
In the embodiment, unlike the first embodiment, the automatic rotation adjustment by the actuator is very difficult, and at least the cost does not match, so it is practical to stick to the manual adjustment method.

FIG. 3 is a block diagram of the first embodiment. In the first embodiment, before the actual flow rate measurement, the propagating of the transmitted and received waves between the respective transducers 7 is optimized by the automatic positioning adjustment of the angle variable device 2 of the pair of the respective transducers 7. . In the figure, a pair of transducers 7 are provided on the outer peripheral surface of the conduit 6.
Is installed, and the actuator 18 is
Are connected. This actuator 18 is an angle variable device 2
Is driven by a control signal for optimizing the rotational position of the. By the way, at the time of normal flow rate measurement, each transmitter / receiver 7 is operated by the transmitting / receiving circuit 11 while exchanging the roles of the transmitting side and the receiving side. That is, the propagation direction of the ultrasonic wave from each transducer 7 is alternately switched between the forward direction and the reverse direction.
The received signals in the forward and backward directions are received wave amplification circuits.
Amplified by 12. This amplified signal is input to the time measuring circuit 13 based on the switching to one side of the switch 15, and the forward and backward propagation times are measured here.
After the difference between the respective propagation times is obtained by the next flow rate calculation circuit 14, the flow rate (to be exact, the flow velocity flow rate) is calculated using the above-described calculation formula. Now, when adjusting the rotational positioning of the angle varying device 2, the switching device 15 is switched to the side opposite to that at the time of measurement, and the output signal of the received wave amplifying circuit 12 is input to the differentiator 16. In this case, since the purpose is to adjust only the proper direction of the transmitted / received wave, only the ultrasonic wave whose propagation direction is either the forward direction or the reverse direction via the transmission / reception circuit 11 is the received wave amplification circuit. Entered in 12. The output signal of the received wave amplifying circuit 12 has a temporal change rate obtained by a differentiator 16, and the next control circuit 17 controls the actuator so that the temporal change rate becomes zero, that is, the output signal value becomes maximum. A drive command is issued to 18. The maximum output signal value of the reception wave amplification circuit 12 means that the transmission and reception directions of the respective wave transceivers 7 are proper.

[0013]

In the ultrasonic flow rate measuring device according to the first or second aspect of the invention, the ultrasonic sensor is provided at the central portion of the plane portion of the angle varying device, and the angle varying device has an acoustic matching medium on the outer peripheral surface of the cylinder. It is possible to oscillate and displace while making surface contact with the cylindrical concave surface of the pedestal. Therefore, the transmitting / receiving direction of the ultrasonic sensor can be adjusted in a plane. By adjusting the transmission / reception direction, the transmission from one can be accurately received by the other. As a result, it is not necessary to finely adjust the mounting position of each transducer to the conduit due to the fact that the actual inner diameter and thickness of the conduit have errors with respect to the design values. Since the adjustment of each direction of the received wave is sufficient, the number of preparation steps for measuring the flow rate is reduced, and the flow rate measurement becomes accurate by the good adjustment.

Particularly, in the ultrasonic flow rate measuring device according to the second aspect of the present invention, each transducer is rotationally positioned with respect to the pedestal by the actuator before the flow rate measurement so that the received signal becomes the maximum value. Thus, the transmission from one side can be accurately received by the other. Therefore, proper rotational positioning can be performed automatically and quickly. In the ultrasonic flow rate measuring device according to claim 3, an ultrasonic sensor is provided at a central portion of a plane portion of the angle varying device, and the angle varying device serves as a spherical concave surface of the pedestal with a spherical surface thereof through an acoustic matching medium. It is possible to freely swing and displace while making surface contact. Therefore, the transmitting / receiving direction of the ultrasonic sensor can be freely adjusted. By adjusting the transmission / reception direction, the transmission from one can be accurately received by the other. As a result, because the actual inner diameter and thickness of the conduit have errors with respect to the design values, it becomes unnecessary to finely adjust the mounting position of each transducer to the conduit, and a much simpler transmission / reception is performed. Since the adjustment of the direction is sufficient, the number of preparation steps for the flow rate measurement is reduced, and since the adjustment is particularly three-dimensional, the flow rate can be measured accurately by performing the adjustment properly and satisfactorily.

[Brief description of drawings]

FIG. 1 is a side view of a transceiver according to a first embodiment of the present invention.

FIG. 2 is a side sectional view showing the operation of the wave transceiver in the first embodiment.

FIG. 3 is a configuration diagram of the first embodiment.

FIG. 4 is a side sectional view showing an operation of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ultrasonic sensor 2 Angle variable device 4 Pedestal 5 Matching medium 6 Conduit 7 Transducer 11 Transmitter / receiver circuit 12 Received wave amplifier circuit 13 Time measurement circuit 14 Flow rate calculation circuit 15 Switcher 16 Differentiator 17 Control circuit 18 Actuator

Claims (3)

[Claims] 1. A pair of ultrasonic wave transmitters / receivers are installed on the outer circumference of a conduit through which a fluid flows, and the ultrasonic wave is transmitted in both directions, a forward direction having a component in the fluid flow direction and a reverse direction having a component in the reverse direction. In a device that measures the flow velocity and flow rate of a fluid based on the time difference of each propagation time when ultrasonic waves are propagated, each transducer is an angle of a shape having a part formed by cutting a cylinder in a plane passing through the axis. A variator; a pedestal made of the same material as the angle variator, which has a cylindrical concave surface that oscillates in plane contact with the outer circumferential surface of the angle variator through an acoustic matching medium, An ultrasonic flow rate measuring device, comprising: an ultrasonic sensor provided at the center of a plane portion of the angle varying device so that the radial direction thereof matches the transmitting and receiving directions. 2. The ultrasonic device according to claim 1, further comprising an actuator for rotationally positioning the angle varying device with respect to the pedestal so that the received signal has a maximum value before measuring the flow rate. Flow rate measuring device. 3. A pair of ultrasonic wave transmitters / receivers are installed on the outer circumference of a conduit through which a fluid flows, and the ultrasonic wave is transmitted in both directions, a forward direction having a component in the fluid flow direction and a reverse direction having a component in the reverse direction. In a device that measures the flow velocity and flow rate of a fluid based on the time difference of each propagation time when ultrasonic waves are propagated, each transducer has an angle of a shape with a part cut by a plane through which a sphere passes A variator; a pedestal that is made of the same material as the angle variator and has a spherical concave surface that is in surface contact with the sphere of the angle variator so that it can freely swing through an acoustic matching medium, ; At the center of the plane of the angle changer,
An ultrasonic flow rate measuring device, comprising: an ultrasonic sensor provided in such a manner that the radial direction and the transmitting / receiving direction are matched.