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JPS54154773

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DESCRIPTION JPS54154773
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view of the principle of an
electromagnetic ultrasonic transmitter-receiver, FIG. 2 is an explanatory view of the configuration
of a flow meter according to an embodiment of the present invention, and FIG. It is structure
explanatory drawing of the detection part of the flowmeter by the other Example of this. 1 ......
transceiver coil, 2 ...... permanent magnet, 3 ...... conductor, P1tP42P5 ...... electromagnetic
ultrasonic transmitter, P2, P3tPa иииии? Electromagnetic ultrasonic wave receiver, At ') A2 ..... Singaround circuit, B ..... Calculation circuit.
DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic
flowmeter currently used for industrial use in a flowmeter using electromagnetic ultrasonic
waves using Lorentz's force. Among the methods (time difference method), there are doppler one
side method and the like. The operating temperature limit of these flow meters is determined by
the temperature characteristics of the ultrasonic transducer. Practical use (1) ? ?-/ C? 773
ultrasonic transducers that have been made into 1 quartz oscillator and barium titanate-based
porcelain oscillator bowl, but it is excellent in all physical properties and cheap Absent. For
example, a crystal unit has excellent temperature characteristics (200 to 500 @ C can be used),
but has high impedance and high price. On the other hand, barium titanate ceramic vibrators are
low in impedance, so they are easy to handle, relatively inexpensive, and excellent in
processability, but can not be used at high temperatures (less than 80??C). Moreover, the
ultrasonic frequency which can be generated by each ultrasonic transducer is determined by the
frequency constant unique to each transducer. That is, when the thickness of the vibrator is
determined, the frequency that can be generated from the vibrator is determined. Therefore,
sensitivity adjustment can not be easily performed in a doppler one-type flow meter in which the
detection sensitivity of the flow rate signal is a function of the transmission frequency from the
ultrasonic transmitter. This invention is made in view of the above-mentioned point, The
objective is to provide the ultrasonic flowmeter which can measure to a high temperature area |
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1
region. Another object of the present invention is to provide an ultrasonic flowmeter (2) which
can be easily adjusted in sensitivity. The present invention, for this purpose, generates an eddy
current in a conductor or a conductive fluid under test by means of a coil, and applies an
ultrasonic wave to the conductive or conductive fluid under application by applying a magnetic
field perpendicular to the eddy current. It is characterized in that it is realized by including
means for generating electromagnetic ultrasonic waves. Hereinafter, the present invention will be
described in detail with reference to the drawings. FIG. 1 is a diagram for explaining the principle
of electromagnetic ultrasonic wave transmission and reception. It is well known that charged
particle KO-Lenz forces acting in a magnetic field act. The generation of electromagnetic
ultrasonic waves utilizes this Lorentz force. In FIG. 1, when an alternating current flows through
the transmitting and receiving coil 1, an eddy current 41.42 flows on the surface of the
conductor 5. When a magnetic field is applied by the permanent magnet 2 in a direction
perpendicular to the movement direction of the electrons forming the eddy current, Lorentz force
is generated in the thickness direction (vertical direction in the figure) of the conductor 3
through which the eddy currents 41 and 42 flow. The electromagnetic ultrasonic wave is
transmitted by this K.
The frequency (3) of the electromagnetic ultrasonic waves is determined by the frequency of the
alternating current flowing through the transmitting and receiving coil 1, and there is no other
factor. Therefore, the transmission frequency of electromagnetic ultrasonic waves #! I can be
varied very easily. On the other hand, in the reception of the ultrasonic signal, the conductor 3
vibrates by delivering the ultrasonic wave to the conductor 3. Since this vibration can be
eliminated under the magnetic field by the permanent magnet 2, an eddy current flows in the
conductor 5 and induction of this causes an induced current in the transmitting and receiving
coil 1. This induced current is the reception signal of the ultrasonic signal. In the above
description, the generation of the eddy current is made of a conductor, but the same thing can be
said even if a conductive liquid is provided instead of the conductor. FIG. 2 is a schematic view of
an electromagnetic ultrasonic flowmeter according to an embodiment of the present invention. In
FIG. 2, P1P2. P3 and P4 are electromagnetic ultrasonic transmitter-receivers, the basic
configuration of which is the same as that of the first M, and P1, P4 Tri electromagnetic
ultrasonic transmitters, P2. P3 constitutes an electromagnetic ultrasonic wave receiver. The
ultrasonic ultrasonic transmitter P and the electromagnetic ultrasonic receiver P3 form a pair,
and are arranged in the same direction as the flow of the fluid to be measured in the pipe line (4)
for the transmission direction of the electromagnetic ultrasonic wave. There is. The
electromagnetic ultrasonic transmitter P4 and the electromagnetic ultrasonic receiver P2 form a
pair, and are disposed in the direction opposite to the flow of the fluid to be measured, in the
direction of transmission of the electromagnetic ultrasonic waves. A, A2 is a sing-around circuit.
Sing-around circuit A1 A closed loop is formed with electromagnetic ultrasonic transmitter /
receiver P1.degree. P, and sing-around circuit A2 is an electromagnetic ultrasonic transmitter /
receiver P4. It forms a closed loop with P2. B is a calculation circuit having a function of
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transmitting the beat frequency AI of the frequency signals f1 and f2. In the above-described
configuration, the following equation is obtained as follows: Sing-around frequency f, aI in the
system of the sing-around circuit A1; (+ V (1) fl и-1-2-1 (2) where C is the velocity of the fluid in
the fluid is the flow velocity of the fluid to be measured t distance between the transmitter and
the receiver (5) AI can be expressed by equation (3). ?f = f, ?f2 = ?i?? flow rate (5) That is, it
is possible to know the flow rate of the fluid to be measured flowing through the pipe line from
the beat frequency 4f. FIG. 3 is a configuration explanatory view of a detection unit of a doppler
one-piece flow meter according to another embodiment of the present invention. The doppler
one-piece flow meter is configured to measure a flow velocity at a predetermined point of a flow
path of the fluid to be measured, for a fluid to be measured including fine particles.
In FIG. 5, the electromagnetic ultrasonic transmitter P5 is disposed such that the ultrasonic beam
is at an angle ? with the flow direction of the fluid to be measured, and at a position where the
reflected ultrasonic beam by the particles can be received at the reflection angle. An
electromagnetic ultrasonic wave receiver P6 is provided. The electromagnetic ultrasonic wave
transmitter / receiver P5. The basic configuration of P6 is the same as in FIG. Now, if it is
assumed that the transmission signal frequency of the electromagnetic ultrasonic transmitter P5
is fo and the delivery signal frequency of the electromagnetic ultrasonic receiver P6 is fr, the
relationship of the equation (4) holds. (6) c + v cos ? ? ? ? ? ? c? vcostft ? ? where C is
the velocity of the velocity of sound velocity V in the fluid, and the beat frequency of the
frequency fr and f can be expressed by . That is, the beat frequency 6 f is proportional to the flow
velocity (proportional constant 2 cos +,,). Therefore, the transmission signal frequency ft can be
varied to adjust the detection sensitivity of the signal. As apparent from the description of the
above embodiment, the present invention is configured to include an electromagnetic ultrasonic
transmitter / receiver to transmit and receive ultrasonic signals. That is, the electrostrictive
element in the piezoelectric element is not used. Therefore, a flowmeter having the following
features could be realized. (I) Since it is not necessary to use a couplant (7) in the construction of
the ultrasonic wave transmitter / receiver which enables measurement of the high temperature
range of the fluid to be measured (7), even high temperature fluids of 1000 ░ C or higher can in
principle be measured It is possible. (The configuration of the IO ultrasonic transmitter / receiver
is simple and easy to maintain. (It's easy to change the frequency of the signal transmission @ il,
so it is easy to adjust the sensitivity of the doppler flow meter.
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