JP3550186B2 - Ultrasonic Doppler flow meter - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to improvements in ultrasonic Doppler flow meters.
[0002]
[Prior art]
Ultrasonic Doppler flow meters are used to measure sewage flow.
Ultrasonic flowmeters that use the Doppler effect, that is, ultrasonic Doppler flowmeters, emit ultrasonic waves toward solid suspended solids and bubbles in flowing water, and the frequency of the reflected wave shifts in proportion to the velocity of the fluid (Shift), the flow velocity and flow rate of the fluid are measured using the shift frequency.
[0003]
Such a measuring method is abbreviated as the Doppler method and is used for measuring sewage and drainage (see Nikkan Kogyo Shimbun, published in 1979, flow measurement handbook, pages 243 to 246, pages 260 to 263).
[0004]
[Problems to be solved by the invention]
When using an ultrasonic Doppler flow meter to measure the flow rate of sewage, if the flow rate is high, air bubbles and solid suspended solids are contained in the fluid, and these air bubbles and solid floating The ultrasonic wave is reflected well on the object, and a large Doppler signal is obtained.
[0005]
However, when the flow rate is reduced, the bubbles are removed and the solid suspended matter is also precipitated, so that the reflector that reflects the ultrasonic wave does not float in the fluid. For this reason, there has been a problem that the reflection of the ultrasonic wave is reduced, a good Doppler signal cannot be obtained, and a measurable flow rate range becomes narrow.
[0006]
Accordingly, an object of the present invention is to provide an ultrasonic Doppler flowmeter suitable for measuring the flow rate of sewage and drainage, which can reliably measure even a flow rate in a small flow rate area, by solving such a problem.
[0007]
The ultrasonic Doppler flow meter of the present invention can be used not only for measuring sewage and drainage, but also for measuring high-quality fluids such as clean water and medium water, as described later.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the ultrasonic Doppler flowmeter according to claim 1, which is disposed close to and immediately upstream of a position where the ultrasonic transceiver (3) is installed, and is open to the bottom of the pipeline. A nozzle (5) as generating means,
A pump (6) for pumping air to the nozzle (5) is communicated ,
An ultrasonic transmitter / receiver (3) and a nozzle (5) as a bubble generating means are integrally formed,
A signal transmitted from the ultrasonic transceiver (3) is emitted toward the downstream side of the fluid,
The measurement unit is installed at the bottom of the pipeline .
[0009]
A pump (6) pumps air to eject air bubbles into the fluid from the nozzle (5). Bubbles generated from the nozzle (5) opening at the bottom of the pipeline flow downstream while riding on the flow of fluid while rising. The ultrasonic waves emitted from the ultrasonic transmitter / receiver (3) are reflected by bubbles in the fluid and are reflected to generate a shift frequency proportional to the velocity of the fluid. Therefore, the flow velocity or the flow rate is measured based on the shift frequency.
[0010]
According to a second aspect of the present invention, the ultrasonic transceiver (3) and the bubble generating means ( 10 ) are integrally formed,
A bubble generating means ( 10 ) is disposed immediately upstream of the ultrasonic transceiver (3),
A signal transmitted from the ultrasonic transceiver (3) is emitted toward the downstream side of the fluid,
The bubble generating means is an ultrasonic vibrator (10),
An ultrasonic Doppler flowmeter, wherein a measuring unit is installed at the bottom of a pipeline.
[0012]
According to a third aspect of the present invention, in the ultrasonic Doppler flowmeter according to the second aspect, the bubble generating means is an ultrasonic vibrator (10), and the ultrasonic vibrator (10) measures a Doppler signal. (3) is excited at a frequency far from the frequency of the ultrasonic wave handled by the ultrasonic transceiver (3).
[0015]
Since the ultrasonic transmitter / receiver (3) and the bubble generating means (10) are integrally formed, they can be installed in a fluid at the same time.
[0020]
【Example】
Figure 1 is a first embodiment of the present invention.
Sewage (fluid) having a water surface 2 flows in the pipe 1 in the right direction in the figure. In the ultrasonic flowmeter 4 for measuring flow velocity, an ultrasonic transmitter / receiver 3 for emitting ultrasonic waves for measurement toward the downstream side and a nozzle 5 as bubble generating means are integrally formed.
[0021]
The nozzle 5 is disposed immediately upstream of the ultrasonic transceiver 3.
The air pumped by the pump 6 is jetted out of the nozzle 5 into the fluid to form a number of bubbles 7, and flows downstream (to the right in the drawing) along with the flow. Ultrasonic waves emitted from the ultrasonic transducer 3 with directivity as shown by reference numeral 8 are reflected by bubbles moving on the flow, and the flow velocity and flow rate are calculated and measured based on the shift frequency.
[0022]
Reference numeral 8 denotes the directivity of the ultrasonic wave emitted from the ultrasonic transceiver 3. 9 is an ultrasonic water level meter for measuring the water level. In addition, the ultrasonic transmitting / receiving element 3 is configured by juxtaposing a transmitting element and a receiving element.
Figure 2 is a second embodiment of the present invention.
In this embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.
[0023]
The second embodiment differs from the first embodiment in FIG. 1 in that the bubble generating means is an ultrasonic vibrator 10 instead of the nozzle 5, and the ultrasonic vibrator is handled by the ultrasonic transceiver 3. The bubbles 7 are generated in the fluid by exciting with strong ultrasonic power having a frequency that is far apart from the frequency of the sound signal.
[0024]
【The invention's effect】
Since the ultrasonic Doppler flow meter of the present invention is configured as described above, the flow rate is small in the measurement of sewage, and air bubbles and solid suspended matters are small even in the fluid due to the entrainment of air. As a result, a large amount of bubbles are forcibly generated, and ultrasonic waves are reflected on the bubbles, thereby obtaining a large Doppler signal.
[0025]
Therefore, the measurement range of sewage was extended to a small flow rate range, and it was practically used for sewage.
In addition, in the middle to large flow area, even when a large amount of rainwater flows into the sewage and the ratio of solid suspended matter decreases, the Doppler signal can be obtained effectively, so that the measurement of the flow velocity becomes unstable or difficult. Never be.
[0026]
Furthermore, it is also effective for measuring a fluid having good water quality such as medium water or clean water.
According to the invention of the present application, the deposit can be prevented from being deposited on the ultrasonic transmitter / receiver immediately downstream by blowing the precipitate by the air flow ejected from the nozzle or the bubble from the ultrasonic transducer (10). The reliability of the meter is improved.
[0027]
Injecting into the fluid is harmless by air or its own air bubbles, so that there is no safety problem.
Further, in the second and third aspects of the present invention, since there is no movable portion that affects the life like a pump, the reliability is improved in that aspect.
[0028]
Further, there is no possibility that the signal for exciting the ultrasonic transducer (10) for generating bubbles and the signal handled by the ultrasonic transceiver (3) may interfere with each other.
Furthermore, in the present invention, there is an advantage that it is easy to install the measuring unit at the bottom of the pipeline.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view of a first embodiment of the present invention.
FIG. 2 is a schematic longitudinal sectional view of a second embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pipeline 2 Water surface 3 Ultrasonic transceiver 5 Nozzle 6 as a bubble generating means Pump 7 Bubble 10 Ultrasonic vibrator as a bubble generating means

Claims (3)

A nozzle (5) as a bubble generating means, which is disposed immediately upstream of the position where the ultrasonic transmitter / receiver (3) is installed, and is open at the bottom of the pipeline;
A pump (6) for pumping air to the nozzle (5) is communicated ,
An ultrasonic transmitter / receiver (3) and a nozzle (5) as a bubble generating means are integrally formed,
A signal transmitted from the ultrasonic transceiver (3) is emitted toward the downstream side of the fluid,
An ultrasonic Doppler flow meter, wherein a measuring unit is installed at the bottom of a pipeline . The ultrasonic transceiver (3) and the bubble generating means ( 10 ) are integrally formed,
A bubble generating means ( 10 ) is disposed immediately upstream of the ultrasonic transceiver (3),
A signal transmitted from the ultrasonic transceiver (3) is emitted toward the downstream side of the fluid,
The bubble generating means is an ultrasonic vibrator (10),
An ultrasonic Doppler flow meter, wherein a measuring unit is installed at the bottom of a pipeline. The bubble generating means is an ultrasonic vibrator (10), and the ultrasonic vibrator (10) is far from the frequency of the ultrasonic wave handled by the ultrasonic transceiver (3) for measuring the Doppler signal. The ultrasonic Doppler flowmeter according to claim 2, wherein the ultrasonic Doppler flowmeter is excited at a frequency.

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