SU802792A1 - Ultrasonic flowmeter - Google Patents

Description

The invention relates to the field of measuring the flow and consumption of substances and can be used in the petrochemical, hydrometallurgical and other sectors of the industry. A single-channel ultrasonic flow meter is known, including two synchro rings, consisting of successively connected amplifiers, a for maker, a coincidence circuit, a generator and a common for two synchro rings of an acoustic transducer and a control unit and recording measurement results l. A disadvantage of the known flow meter is the lack of automatic start-up and restoration of its operation after temporary disruption of the electro-acoustic channel, which may occur due to scattering of the ultrasonic beam on gas bubbles and other irregularities in a controlled environment. The closest in technical essence to the proposed flow meter is an ultrasonic flow meter, which contains two synchrockets, consisting of series-connected prohibition schemes, a driver and common for a snoop acoustic transducer and receiver, two start-up units connected to the synchro rings, each of which consists of search and auto-tuning of the phase, the output of which is connected to the frequency divider through the auto-generator, and entered to one of the inputs. Mina element. : The ment is connected to the input of the circuit I, the output of which is connected to the second inputs of the imaging device and the prohibition circuit, the output connected to the second input of the storage element, and the measuring unit consisting of the mixer, the inputs of which are connected to the outputs of two autogenerators, and the output to the input of the indicator 2. The disadvantages of the known meter are due to the fact that two synchroables can work stably with one acoustic transducer only sequentially. This leads to a decrease in the accuracy of the flow velocity measurement due to a change in the physical properties of the medium between the switching cycles. In addition, it becomes necessary to memorize the frequency of the sync pulses of one synch {Rokoltsa during the operation of the other, which leads to an additional measurement error. The aim of the invention is to improve the measurement accuracy. This is achieved by the fact that the first synchronizer of the flow meter is equipped with a driver for working pulses, the input of which is connected to the output of the frequency divider, and output to the inputs of the AND circuit and a storage element, and the second synchronous ring is equipped with serially connected generator of the working pulses and an analysis device pulses are connected; 1nen with the output of the frequency divider, one output of the analysis device is connected to the inputs of the AND circuit and the storage element, the second output is connected to the third input of the driver, and the input the analysis device is connected to the output of the formaker of the working pulses of the first synchroable. FIG. 1 is a block diagram of an ultrasonic flow meter; Fig. 2 shows voltage diagrams for the operation of a single synchro-ring with a trigger unit; in fig. 3 voltage diagrams for simultaneous operation of two synchro rings with one acoustic transducer., Ultrasonic flowmeter contains acoustic transducer 1 with piezoelectric elements 2 and 3, autogenerators 4 and 5, frequency dividers b and 7, drivers 8 and 9, working pulses, circuits 10 and 11 search and auto-tuning phase, device 12 analysis of the circuit And 13 and 14, the storage elements 15 and 16, the prohibition scheme 17 and 18, shapers 19 and 20, the receiver 21, the mixer 22 and the indicator 23. The first synchro ring (which is leading) consists of a sequence connected to the sync ring of the receiver 21, the inhibit circuit 18, the imaging unit 20 and the synchroscopic acoustic transducer 1 common to the first synchrocord are connected to a starting block consisting of a search circuit 11 and an auto-tuning phase connected to the input of the autogenerator 5, the output of which is . Through the frequency divider 7 and the driver 9 working pulse is connected to the first inputs of the circuit 11 search and auto-tuning phase, circuit 14 and the storage element 16, BH circuit And 14 is connected to the second inputs of the driver 20 and the prohibition circuit 18, output for which it is connected to the second input of the storage element 16, the output of which is connected to the second inputs of the search circuit 11 and the phase-locked circuit and the AND circuit 14. The second synchro-holder (which is a slave) consists of a series-connected receiver 21, a prohibition circuit 17, a former 19 and an acoustic Converter 1, to the second synchro-ring is connected to the start-up block, consisting of a search and auto-tuning circuit 10, connected by an output to the input of the auto-oscillator 4, the output of which is through frequency divider 6, the driver 8 operating pulses, and The analysis device 12 is connected to the first inputs of the phase search and auto-tuning circuit 10, the AND 13 circuit and the storage element 15, the output of the AND circuit 13 is connected to the second inputs of the driver 19 and the inhibitory circuit 17, the output of which is connected to the second input of the storage element 15 whose output is connected with the second inputs of the search and auto-tuning circuit 10 and the circuit AND 13, the other input of the analysis device 12. is connected to the second output of the driver 9 of the working pulses of the first sync ring, and its second output is. with the third input of the imaging unit 19 of the first sync ring, the measuring unit consists of a mixer 22, the inputs of which are connected to the outputs of two autogenerators 4 and 5, and the output to the input of the indicator 23. The flow meter operates as follows. The voltage from the output of the search circuit 11 and the auto-tuning of the phase (Fig. 2e) is fed to the input of the controlled oscillator 5, rearranging its frequency. At the moment of supplying the supply voltages, the voltage at the output of the search circuit 11 and the automatic phase adjustment is zero. At the same time, the period of the following pulses of the controlled oscillator 5 is minimal (Fig. 2a). In addition, the condition must be fulfilled that the pulse period from the output of frequency divider 7 with the division factor K (K) is shorter than the minimum signal propagation time through the electroacoustic channel. The tuning of the period of the controlled oscillator 5 is chosen so that the maximum period of the pulses at the output of frequency divider 7 is greater than the maximum time of signal propagation through the electroacoustic channel. At the moment of supplying the supply voltage, there is no pulse at the output of the oscillator 5, therefore there are no pulses and at the outputs of frequency divider 7 and shaper 9 working pulses, while at the shaper output 9 working pulses a low level. This level is fixed by the memory element 16, for which an RS-trigger can be used, with a high level at its output. At the exit

prohibition scheme 18, in which the AND-NOT scheme can be used, in its initial state it is a high level.

Since the output of the storage element 16 is connected to the input of the AND 14 circuit, the very first positive pulse from the output of the imaging unit 9 of the working pulses (FIG. 26) through the AND circuit 14 (Fig. 2c) goes to the inhibit circuit 18, unloading it, and starting the imaging unit 20. The starting of the former 20 is performed by the falling edge of the positive pulse, i.e. by negative differential. A pulse from a driver 20 {(Fig. 2rJ) is fed to a piezoelectric element 3, converted into an ultrasonic signal, which passes through a controlled medium and is received by a piezoelectric element 2, which converts it into an electrical signal. This signal goes to a receiver 21, where a pulse is amplified and formed into a square pulse ( Fig. 2d), then enters the prohibition circuit 18. The pulse at the output of the receiver 21 is delayed relative to the pulse from the output of the imaging unit 20 for a time Since the period of the pulses from the output of the imaging unit 9 of the operating pulses is minimal and less than t , then the second pulse from the output of the circuit 14 will arrive at the input of the inhibit circuit 18 earlier than the pulse from the output of the receiver 21, and the inhibit circuit 18 will be closed by the time the pulse arrives from the receiver 21. However, the second pulse from the output of the circuit 14 is electroacoustic Gshadognch channel about the first, etc.

At the same time, the positive pulses from the output of the former 9 working pulleys 1 and 1 pulses are fed to the search and auto-tuning circuit 11, increasing the voltage at its output. At the same time, the period of the controlled autogenerator 5 is increased until by the moment of arrival of youuls from the receiver 21 to the inhibitor circuit 18 the inhibitor circuit 18 does not appear to be opened by the pulse from the output of the AND circuit 14. Then the pulse from the receiver 21 passes through the inhibit circuit 18 to the input Formulate 20 excitation pulses, triggering it with the leading edge of a negative pulse. The master flow meter sync ring is running. At the same time, a negative pulse from the output of the inhibitor circuit 18 is fed to the input of the storage element 16, and a low level is set at its output, so that a ban is applied to the AND 14 circuit, which limits the pulse duration at its output (point in time in Fig. 2c). In this case, the leading edge of the positive pulse at the output of the circuit And 14 will coincide

the leading edge of a negative pulse at the output of the prohibition scheme 18, i.e. Further operation of the controlled oscillator 7 does not affect the operation of the synchro-ring. Therefore, the controlled oscillator 5 is automatically switched off. In the future, the leading synchro-ring runs continuously.

After this, circuit 11 of the search and auto-tuning of the phase from the search mode

0 enters the auto-tuning mode of the phase of the controlled auto-oscillator 5 with impulse 1 of the autocirculation of the synchro-ring. The high level at the output of the storage element 16 is re-established

5 on the trailing edge of the positive impulse from the output of the former 9 working impulses. The pulses from the output of the imaging unit 9 working pulses are fed to the input of the search circuit 11 and auto-adjusting the phase, and its other input receives pulses from the output of the memory of the 16, the leading edge of which coincides with the leading edge of the pulse of the synchrole, passed the prohibition 18. Search circuit 11

5 and the phase locked loop allocates a time error between the pulse from the output of the driver 9 working pulses and the leading edge of the autocirculation pulse of the sync ring, converts the error into a control signal with which it controls the frequency and phase of the autogenerator 5. Moreover, the adjustment is performed in this way so that the front of the synchro-autocirculation pulse front is located within the pulse from the output of the imaging unit 9 working pulses, preferably in its middle. Then

0 the prohibition scheme 18 and, therefore, the leading synchro-ring will open on the leading edge of the pulse from the output of the driver 9 operating points, and close on the leading edge of the sync ring pulse,

$ ie open synchroclock time will be half the length of the pulse from the output of the imager 9 working pulses. From the point of view of the repeatability

0 KMfiynbca from the output of the imager 9 working pulses is chosen equal to 1-2% of the period of the autocirculation pulses.

In case of violation of the electro-acoustic channel, the pulses from the output of the imaging unit 9 of the working pulses will continue to flow to the input of circuit 11 of the search and auto-tuning of the phase, increasing the voltage at its output. In this period of impulses

0 at the output of the imaging unit 9 operating pulses will increase. With a voltage at the output of the search circuit 11 and phase self-tuning, this period will be maximum.

Claims (2)

5 Diagram 11 of the search and auto-tuning phase will perform the discharge of this direc- tion to zero, after which the setgioSfceiBo will work in the same way as © vyshaashomu-. Thus, in a veduh sync-ring, the pulses from the VSS of ajtogeerator 5 are due to frequency and phase of the pulses of the eHiad-} 2 of the ring, but the frequency of these mmp.u. is K times higher than the frequency of LI-QB - coaf nzme-i yut no more than the duration of the pulse with in the code of the driver. About the start and playback of the slave syncro-olyusha operation, the simultaneous operation of two synchro-rings of the voltage across the codes of the individual blocks looked like this: In Fig. Following tiM pulses at the output of the divider 7, the pulses of the pulses 75 are shown in Fig. Zv - gave Fiyjfb © i3 / 9 working impulses coming from the imager to the circuit 14, in Fig. 3g - the signals of the lead snohlider received by the receiver; in Fig. Rd - the impulses emitted by the worldviewer 20. As can be seen from Fig. 3g and Rd the leading synchro-ring runs continuously and its period is equal to T c ushego. The division factor of the frequency divider b is chosen so that the frequency of the pulses at its output is an integer number of times higher than the frequency of the pulses of the slave sync ring (in Fig. Ze - twice) .. Shapes 8 and 9 of the working pulses from the outputs of frequency dividers b and 7 impulses of a ban (fig. Зж and 36). Since the oscillators 4 and 5 are rigidly connected in frequency and phase with the pulse sequences of the corresponding synchro rings, it is easy to fulfill the requirement that the inhibit signals cover signals received by piezo sensors. The presence of impulse pulses is necessary to ensure the elimination of moments of coincidence of impulses of a siih-ring. In addition, a hard coupling in frequency and phase of the oscillator 4 with the pulses of the driven sync ring allows the former 8 working pulses to form pulses (Fig. 3e), the fronts of which coincide with the fronts of the pulses emitted by the imaging unit 19 (Fig. 4n ). These pulses (Fig. 3) will in the following be called the stored phase pulses. Since the frequency of the pulses from the output of the frequency 6 bodies is an integer number of times higher than the frequency of the slave sync ring, the driver 8 of the working pulses generates sequences of inhibit pulses (Fig. Зж), memorized phase pulses (Fig. Зи) and pulses that must flow to the circuit I 13, the storage element 15 and the phase searching and auto-tuning circuit 10 (FIG. Za) with a frequency are also an integer number of times higher than the frequency of the synchro-slave (in the case under consideration two times). Therefore, each of the generated sequences. can be considered as the result of the imposition of two sequences of pulses (even and odd) with a frequency equal to the frequency of the driven synchroable, but shifted from each other in phase by half the period of the driven synchromagnetic. In this case, due to the phase self-tuning of the fronts of the pulses of the filled phase, for example, an even sequence, coincide with the phases of the pulses emitted by the shaper 19, i.e. synchronous with the pulses of the slave synchro. The impulse ban of the even sequence covers the received signal {FIG. 3 m) and the pulses of an even-numbered sequence come through the analysis device 12 to the AND 13 circuit, the storage element 15 and the phase search and auto-tuning circuit 10. Since the master and slave of the synchrohold have a frequency difference, their signals inevitably gradually approach each other. In order to exclude the moment of coincidence of these signals, they provide the priority synchro-ring — it operates continuously. In addition, the device 12 analysis controls the coincidence of the pulses of the prohibition of an even sequence with the driver 8 working pulses and the prohibition pulses from the driver 9 working pulses. After a match has occurred, the analysis device 12 provides a phase shift in the autocirculation pulses of the slave sync ring by half a period. This is achieved by the fact that the analysis device ceases to transmit to the AND 13 circuit the pulses of an even sequence and begins to pass pulses of an odd sequence that is shifted by half a period relative to the even one. In this case, the inhibit circuit 17 is closed for the sync-ring pulses corresponding to the even-numbered sequences, and open for the pulses corresponding to the odd-numbered. At the same time, the analysis device transmits a single pulse of the stored phase from the odd sequence (Fig. 3L) to the start of the imaging unit 19, which restores the work of the driven synchro-ring with a half-period shift. Further phase-to-self auto-tuning occurs on odd pulses. After this, the ANESHNS device 12 begins to control the coincidence of the prohibition pulses of the master clock of the ring and the pulses of the prohibition of the slave synchronous ring of an odd sequence (Fig. GC). With a new approximation of synchrocall signals, the phase shift of the autocirculation pulses in the slave sync ring by a half-period, etc., occurs again. The pulses from the outputs of the autogenerators 4 and 5 are fed to the mixer 22, which absorbs the difference frequency K times higher than the frequency difference of the sync ring, which is proportional to the flow velocity. To ensure the normal operation of the ability of the duration of the pulses. the prohibition T is chosen from the condition 2tr where T is the minimum period of the synchro-ring N is the ratio of the frequency of the pulses at the output of the frequency divider b to the frequency of the driven synchrokold. For the case in question, C is selected from the condition of 2tr. Invention Ultrasonic flowmeter comprising two synchroables consisting of successively connected prohibition scheme, former and common for the synchro-ring of the acoustic transmitter and receiver connected to the synchro-rings two triggering units each of which from the search and auto-tuning scheme of the phase, the output of which is connected to the frequency divider via an auto-oscillator, and the input to one of the inputs of the storage element and the AND circuit, and the output is the downstream element is connected to the input of the AND circuit, the output of which is connected to the second inputs of the imaging device and the prohibition circuit, the output connected to the second input of the storage element, and the measuring unit consisting of the mixer, whose inputs are connected to the outputs of two autogenerators, and the output to the indicator input , in order to improve measurement accuracy, the first synchro-ring is equipped with a driver for working pulses, the input of which is connected to the output of the frequency divider, and the output - to the inputs of the AND circuit and the storage element, the second synchro-ring is equipped with a serially connected working pulse generator and an analysis device, the input of the working pulse generator is connected to the output of a frequency divider, one output of the analysis device is connected to the inputs of the AND circuit and the memory element / second output - to the third input of the imaging unit and the input of the analysis device is connected to output shaper working pulses of the first sync ring. Sources of information taken into account in the examination 1. The author's certificate of the USSR 531029, cl. G 01 F 1/66, 1972. 2. USSR author's certificate. According to application no. 2585951 / 18-10, cl. G 01 F 1/66, 03/03/78 (prototype ;. T / iifffff V