SU794532A1 - Ultrasonic liquid rate meter - Google Patents

Description

one

The invention relates to the field of ultrasound measurements and can be used in devices for measuring the velocity of a fluid, flow meters.

Ultrasonic liquid velocity meters are known, containing two piezoelectric transducers, a generator, amplifiers, plug filters, frequency dividers and a phase-measuring circuit 1.

A disadvantage of such devices is the complexity of the circuit due to the presence of dividers, selective and notch devices.

The closest technical solution to the invention is an ultrasonic fluid velocity meter containing a oscillating frequency generator, first and second electroacoustic transducers located in a controlled medium, an amplifier connected to the oscillating frequency generator, and a beat period generator connected to the input of the computing unit.

Its disadvantage is a large measurement error due to the fact that the high-frequency pulsations of the medium movement are not taken into account, as well as due to the increased sensitivity of the device to the presence of pickup propagating faster than the useful signal.

The purpose of the invention is to improve the measurement accuracy.

The goal is achieved by introducing a second amplifier connected to the output of the oscillating frequency generator and an additional beat period generator, the output of which is connected to the second input of the computing unit, with the inputs of the first and second beat period generators separately connected to common points of connection of the output of the corresponding amplifier and one of the electrodes of the electroacoustic converter.

The drawing shows the structural scheme of the proposed ultrasonic measuring device for the velocity of the fluid.

The fluid velocity meter contains a oscillating frequency generator 1, electroacoustic transducers 2 and 3 placed in a controlled environment, the first and second amplifiers 4 and 5, the formers 6 and 7 beat periods and the computing unit 8. The output of the oscillating frequency generator 1 has a linear law frequency change, connected to the inputs of the first and second amplifiers 4 and 5. The inputs of the first and second drivers 6 and 7 periods of the beating are separately connected to the connecting points of the output of the amplifier 4 and one of the electrodes ektroakusticheskogo converter 2, the output of the amplifier 5 and one of the electrodes of the electroacoustic transducer 3. Each of the formers 6 and 7 formed, for example, in the form of an amplitude detector and threshold circuit. The outputs of the drivers 6 and 7 are connected respectively to the first and second inputs of the computing unit 8, which produces a signal proportional to the difference between the periods of the beating.

The proposed ultrasonic fluid velocity meter works as follows.

The electroacoustic transducers 2 and 3 receive the generator voltage 1 kachaypdeys frequency through separate amplifiers 4 and 5. Emitted by each transducer in the direction of each other, the ultrasonic waves propagate in and against the direction of movement of the controlled medium and reach the other. :-to

V + C

I respectively, where / is the distance

V -C

between converters; V is the velocity of the medium; C is the ultrasound velocity in the medium.

The frequency of the ultrasound emitted at some point in time by the transducer 2, and the frequency of the waves emitted by the transducer 3 and reaching at that time the transducer 2, differ by

D / -J J -Q-V

where A is the rate of change of frequency. The waves coming from converter 3 are taken by converter 2 and converted into electrical oscillations, which, however, do not pass to the output of generator 1, since amplifier 4 has unidirectional energy transfer properties. With a small absorption of ultrasound in a liquid at the midpoint of the divider, composed of the output impedance of the amplifier 4 and the electrical impedance of the converter 2, beating signals of two frequencies: emitted and received. Beat period G; equals

T L J- -

  A /, to I

Similarly, at the midpoint of the divider, composed of the output impedance of the amplifier 5 and the electrical impedance of the converter 3, the beats of signals with a period of

„, 1 С 4- V - to ГС Signals from converters 2 and 3 are supplied to the inputs of shapers of 6 and 7 beating periods. At the output, signals with durations TI and T, respectively, are extracted. Computing unit 8 generates a signal

2K K1

T T -

at 21 -

that is, proportional to the measured value — the velocity of the fluid. This signal can be represented in a digital code or in any other form suitable for indication.

The proposed meter is characterized by ease of implementation as well as high measurement accuracy due to the fact that

the computing unit continuously receives information, based on which the speed is calculated. Processing and converting received signals, for example, into a digital code, outputting results and indication is carried out by any known means. In addition, the device is insensitive to interference propagating at a speed many times greater than the speed of ultrasound.

Claims (2)

1. Author's certificate USSR number 522469, cl. G 01 R 3/64, 1974. 2. USSR author's certificate number 494693, cl. G 01 P 5/00, 1973 (prototype).