SU708228A1 - Flowrate meter - Google Patents

Description

(54) FLOW SPEED METER

I

The invention relates to the field of Electroacoustics and ultrasound technology and can be used, in particular, to measure the flow rate of liquid and gaseous media, as well as to measure the speed of movement of bodies in these media.

Devices for measuring the flow rate of flowing media are known, based on the single-channel phase method C by alternating switching of the heterojuncture.

The disadvantage of these devices is that under the influence of the flow components caused by the temperature and concentration changes of the ultrasound speed, the (working) points of the phase-measuring devices drift continuously, which leads to a decrease in the sensitivity of the device.

Closest to the invention in its technical essence is a device comprising a generator connected via a first modulator to a first electroacoustic converter.

And to the selection input of the second phase-measuring device, through the second modulator to the second electro-acoustic converter and to the selection Input of the first phase-measuring device, through an adjustable phase shifter to the inputs of the reference signal of both phase-measuring devices, and through the switching unit to the control inputs of the first and second modulators and phase-measuring devices L2J.

The drawbacks of the device are insufficient accuracy and linearity of measurements due to a change in the slope of 1 converting the flow rate into an electrical signal (as a result of interference effects in the acoustic path) under the influence of destabilizing factors in the form of temperature and co-dyon changes in the ultrasound velocity electroacoustic transducers, oscillator frequency oscillations. In addition, the method of automatically phasing out the signals at the inputs of phase-measuring devices, applied in the known device, leads to an additional error due to the fact that the tracking error of the closed automation system is fully present at the output of the main phase-measuring device.

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

This goal is achieved by introducing a control unit and a differential element and an adder connected in parallel, the inputs of which are connected to the outputs of phase-measuring devices, and the output of the adder is connected to the control input of the generator through the control unit.

The essence of the invention is that in the proposed device, the device; Automatic maintenance of the constancy of the average wave difference in the acoustic path is achieved, which ensures the constancy and linearity of the steepness of conversion of the flow velocity into the output voltage, since the latter is uniquely related to the average value of the wave difference in the acoustic path

The drawing shows a diagram of the proposed device.

The device consists of a sinusoidal oscillation generator 1, first and second modulators 2 and 3 of the first and second electroacoustic transducers 4 and 5, switching unit 6, first and second phase-measuring devices 7 and 9, adjustable phase shifter 8, difference element 10, adder 11, unit 12 controls.

The device works as follows. Generator 1 generates a sinusoidal voltage of high frequency, which. through the modulators 2 and 3 alternately enters the electroacoustic transducers 4 and 5 and directly to the switching unit 6, which forms a pulsed low-frequency control signal, which is transversely. opens the modulators,

In one of the switching cycles, the modulator 2 is open, and the electroacoustic transducer 4 radiates a stream of acoustic oscillations. The electroacoustic transducer 5 at this time accepts acoustic oscillations and converts them into electric SI1;

Device 7. The phase-measuring device 7 is openly open by the same switching impulse as the modulator 2. The phase-measuring device 7 also receives the reference voltage of the generator 1 through the adjustable phase shifter 8.

In another cycle of the commutation modulator 2, the modulator 3 is closed and open, through which the electro-acoustic transducer 5 receives the high-frequency signal of the generator 1. The electro-acoustic transducer 5 emits up-side acoustic oscillations, which are received by the electro-acoustic transducer 4 and fed to the phase-measuring device 9 open with the same low frequency impulse as the modulator 3. To the second input of phase-measuring device 9 through the adjustable phase shifter-8 receives a reference high-frequency voltage generator 1.

Thus, at the outputs of phase-measuring devices 7, 9, equal in magnitude but opposite in sign to voltage, proportional to the flow velocity, are formed. By entering the difference element 10, the voltage from the phase outputs of the measuring devices 7, 9 is subtracted, and as a result, a signal is obtained that is proportional to the flow rate of the medium under study.

Claims (2)

When exposed to destabilizing factors in the form of temperature and concentration measurements of the ultrasound velocity, changes in the distance between the electroacoustic transducers 4, 5, the average wave difference in the acoustic path changes, and the zero (operating) points of the phase measuring devices 7, 9 are shifted in one direction (positive or negative). At the output of the adder, a signal appears that is proportional to the change in the mean value of the wave difference and is not independent of the flow velocity. The voltage from the output of the adder 11 goes through the control unit 12 to the control input of the generator 1 and changes its frequency until the original average wave difference in the acoustic path is restored. The control unit 12 generates the required dynamic characteristics of the oscillator 1 frequency generator autotune system. By adjusting the phase rotator 8, the average value of the wave difference monitored by the automation system changes and, accordingly, a mode is reached in which the wave difference is a multiple of the integer half of the acoustic waves, which corresponds to the best linearity of the conversion flow rate of the test medium into an electrical signal. The formula of the image and the Flow Meter containing a generator connected through the first modulator to the first electroacoustic converter and to the selection input (BTopoJX) of the phase measuring device, through the second module to the second electroacoustic presetter and to the selection input of the first phase-measuring device adjustable phase shifter to the inputs of the reference signal of both phase-measuring devices, and through a switching unit to the control inputs of the first and second modulators and phases measuring devices, characterized in that, in order to increase the measuring accuracy, it is entered in the control unit and connected in parallel razgyustny element and an adder, which are connected to outputs PHASE MEASUREMENT devices, and the adder output through the control unit connected to the generator upravl5poschemu entry. Sources of information taken into account in the examination of 1. Brazhnikov N. I. Ultrasonic Phasometry. Energy, M., 1968, p. 181-248. 2. USSR author's certificate number 148253, cl. Gi-01 P 5/00, 1961, (prototype).