SU1024726A1 - Ultrasonic flowmeter - Google Patents

Abstract

ULTRASONIC FLOWMETER, containing two reversible electroacoustic transducers installed on opposite walls of the pipeline and connected through a switch to a pulse generator and a counter, as well as a driver of control pulses, the inputs of which are connected to the outputs of the counter, which is connected to the output of the counter. that, in order to increase the speed and reliability of the measurement, a two-channel gating scheme was introduced into it, each channel of which consists of a series-connected one-oscillator, forming a stbb pulse, a key and an amplifier, as well as a random access memory, a comparator, two AND circuits, a trigger and a pulse generator, the inputs of both channels of the gating circuit are connected to the output of the control driver, and the outputs to the first and second operational memories, the third and fourth inputs of which are connected to the outputs of the driver control pulses, and the OUTPUTS - to the inputs of the comparator and the first input of the first circuit And, the second input of which is connected to the output of the form The control pulses, jg, the comparator output is connected to the first trigger input, the second input of which is connected to the output of the first 1L circuit, to the fifth input of the random access memory, the trigger output is connected to the first input of the second I circuit, the second input of which is connected to the pulse generator, the second inputs of the keys of the two-channel gating circuit are connected to the outputs of the switch. IND 0

Description

The R & D device relates to measurement technology, in particular, to devices for measuring fluid flow by the ultrasonic method.

A ultrasonic flowmeter containing an acoustic transducer with two piezoelectric elements, two pulse generators, a trigger, a start generator, an OR circuit, a time interval meter and a delay line is known. The principle of measuring the flow rate of the difference D, pulse passing through the flow, and against him, increased n times due to n such measurements of l

The disadvantage of such flow meters is the low accuracy of the measurement due to the time shift or failure of the established autocirculation pulses in the flow and against it, introduced by interference received by the amplifiers and unprotected against random input signals.

The closest to the technical essence of the present invention is a single-channel ultrasonic flow meter containing two reversible electroacoustic transducers installed on opposite walls of the pipeline and connected through a switch to a pulse generator and a counter, a control pulse former connected to the counter, a computing and registering device 2J.

A disadvantage of the known device is the low accuracy of the measurement due to the fact that the computational circuit does not have protection from receiving interference for the entire duration of the auto-circulation periods, as well as insufficient measurement performance.

The aim of the invention is to increase the speed and reliability of measurements.

The goal is achieved by the fact that an ultrasonic flow meter containing two reversible electroacoustic transducers installed on opposite walls of the pipeline and connected via an ком switch to a pulse generator and a counter, as well as a driver of control pulses, whose inputs are connected to the outputs of the counter, are additionally equipped with a two-channel gating circuit. Each channel of which consists of a serially connected one-shot, a strobe pulse former, a key and an amplifier, as well as a random access memory, a comparator, two AND schemes, a trigger and a generator of filling pulses, the gates of both channels of the gating circuit are connected to the npia driver's output in pulse pulses, and the outputs to the first and second inputs of the random access memory, the third and fourth inputs of which connected to the outputs of the driver control pulses, and the outputs - to the inputs of the comparator and the first input of the first circuit And, the second input of which is connected to the output of the driver control pulses, output The comparator is connected to the first input of the trigger, the second input of which is connected to the output of the first I circuit, and the right input of the random access memory, the output of the trigger is connected to the first input. the second circuit And, the second input of which is connected to the generator of pulse filling, while the second inputs of the keys of the two-channel gateway cxeivu are connected to the outputs of the switch.

FIG. 1 is a block diagram of an ultrasonic flow meter; in fig. 2 shows time diagrams of accumulation by cells of an operative potential storage device in the absence of a flow (Fig. 2a) and in the presence of a flow (Fig. 26).

The ultrasonic flow meter contains an acoustic sensor 1 with two reversible electroacoustic transducers 2 and 3, a pulse generator 4, a simulator 5, a counter 6, a control pulse driver 7, a two-channel gating circuit 8 consisting of single vibrators 9 and 10, drivers 11 and 12 strobe pulses, keys 13 and 14, amplifiers 15 and 16, as well as random access memory 17, comparator 18, first AND 19 circuit, trigger 20, filling pulse generator 21 and second AND 22 circuit. The operational memory consists of four yoh cells 23 - 26 are included in pairs. ,

The ultrasonic flow meter works as follows.

In the mode of measurement from the output of the generator 4 through the switch 5

short pulses with a Sending Frequency f excite electroacoustic transducers 2 and 3, simultaneously transmitting ultrasonic (US) signals and simultaneously receiving them separately. With the help of a counter. A, 6 counts n counter-sent signals and impulses start sending ultrasonic waves and n-th eigenses of the end of each counting n counter-sent signals,

which are from the shaper 7 output

control pulses enter the

dual-channel circuit 8 strobirovi and RAM 17 (RAM). Always in the process of operating RAM 17, two cells in a given time interval defined between two n-pulses are in the mode of accumulation and storage of potentials, and two cells are in the mode of equalization of their previously accumulated potentials followed by c6piocoM last to the original level The reset is effected by a pulse from the output of the comparator 18. At the moment of receiving the measurement circuit, the pulse begins to send ultrasonic waves from the output of the forming body 7 control pulses to the third input of the RAM 17 and transfers two paired cells, for example 23 and 24, to the accumulation. by; potential. At the same time, it is fed to single-shot 9 and 10 dual-channel gating circuit b, at the outputs of which time intervals sin OS (c-Vn, a -cosot) 3 sin os (c-M-cosol) are formed, and tjtt ;, t, is the propagation time of the ultrasonic signal measurement base in the absence of flow; 2 the propagation time of the ultrasound signal of the measurement base at Vn x against the flow; - the propagation time of the ultrasonic signal by the measurement base at, downstream; - base of marinating; flt is the angle of the base line relative to the axis of the pipeline; C is the speed of propagation of signals in a liquid; maximum flow rate; During the time interval from the output of the gating pulse generator 11, the electronic key 13 is closed, and during the time interval t from the output of the gating pulse generator, the electronic key is closed, 14. After the time tj expires, which corresponds to the moment of a possible arrival of the ultrasonic signal on the electroacoustic A transducer 2 sent by an electro-acoustic transducer 3, e output, one-shot 9, followed by a number of delayed pulses, is triggered by a pulse generator 11, generating a strobe pulse by which the electronic key 13 is set to the conduction mode for transmitting the converted signal to the input of amplifier 15, and after a time tg corresponding to the moment of the possible arrival of the ultrasonic signal to the electroacoustic converter 3 sent by the electroacoustic converter 2, from the output of the one-oscillator. 10, the back edge of the impulse is triggered by the shaper pulse shaper 12, generating a strobe pulse with the duration of which the electronic key 14 is set to the conduction mode to transmit the converted signal to the amplifier 16 input. The pulse from the amplifier 16 output switches the cell 24 of the RAM 17 to the potential storage mode & 13, accumulated by the cell during the time interval, and the pulse from the output of the amplifier 15 is the cell 23 into the storage mode of the potential accumulated by the cell during the time interval 1, (fig. 26), where is the time hydrochloric interval passage ultrasonic signoshom base measurement for po.toku; and ti is the time interval for the passage of the UZ signal by the base of the intention against the flow. Always for a given pipe diameter, If and j are not outside the limits of the values of t, t .. +, .t t, i 4 i t2 t H-ut; tj t; This is a necessary and sufficient condition for receiving over the ultrasonic signal signals converted by the electroacoustic converter 3 at the moments of operation. At the first input of the electronic key 14 of the gate signal impulse duration ds, and against the flow - signals converted; electroacoustic transducer 2, at the moments of action at the first input of the electronic key 13 gating pulses of duration L tl. , - For the n time intervals t, io2g, which corresponds to the number of signals sent to the acoustic path and received by electroacoustic ultrasonic transducers in the interval between two nth end pulses under; cell 23, for example, accumulates potential U, and cell 24 the potential U2 (Fig. 26), with one potential applied to one and the other to the other inputs of the comparator, torus 18. If there is no flow in the pipeline, To i | . Respectively, for equal time intervals, cells 23 and 24 of RAM 17 accumulate equal DU2Potentials4 For n time intervals

 I, the potentials of the cells reach the level

uu, -.,

flU2n U2

with this and l 0 (Fig. 2a).

In the presence of a stream in the received direction, always t2vL — Accordingly, the potential lU accumulated by cell 23 during the time interval 2 is greater than the potential uU accumulated by cell 24 during the time interval (Fig. 26) / t.

Then dU -4U / j 4U

For n time intervals tg, cell 23 accumulates potential AU ;, and a for n time internals t cell 24 accumulates potential

jiUjn Ui, if it is) n UU2 n

di n-uU2n uu-n

The nth pulse of the end of the counting of the counter 6 from the output of the control pulse generator 7 sets the fourth input of the RAM to its cell 23 to the potential reduction mode to Zfovn potential accumulated by the cell 24, cells 25, 26 to the potential accumulation mode, sets the leading edge, s exit RAM level 17

Resolution

at one of the entrances

the first element And 19, and through the other input of the last sets the trigger 20 in one state. From the output of the trigger 20, the Resolution level appears at one of the inputs of the element And 22, and the pulses of the filling generator 21 arrive at its output ,.

After the expiry of the time uf from the moment the 17 pth pulse of the counter 6 reaches the fourth input of the RAM and the cell 23 reaches the potential and cell 24, g the result of which the comparator 18 produces a pulse, which from its output sets

the fifth input of the RAM 17 at one of the inputs of the element And the 19 level Prohibition, sets the cells 23 and 24 to the mode of resetting the available potentials to the initial level, sets the trigger 20 to the zero state. From the single output of the trigger SO at ONE of the inputs of the second element I 22, the Prohibition level appears, as a result of which the flow of the pulses of the generator 21 to the information output of this element I stops.

The greater the flow rate, the greater the difference U -V -CiV-n and, accordingly, the longer the time interval 4 f proportional to the measured flow rate during which the pulses of the filling generator 21 are passed to the information output of the And 22 element.

This ultrasonic flow meter makes it possible to increase the reliability of the results of measuring the flow rate of a liquid medium, and has increased resistance to interference due to the temporary protection of the inputs of the receiving amplifiers from the effects of extraneous converted into electrical ultrasonic signals. In addition, the principle of simultaneous discrete accumulation of potentials in two paired cells in the flow meter between two n-pulses, followed by raising the accumulated potential of one cell to the potential level accumulated by another cell, for example, lowering one of them, allows to vary in wide the duration of the interval,

which is a measure of consumption. t,. .

For the manufacture of a flow meter, an elemental base of wide use is suitable, and the structure has a detachable block arrangement, which simplifies the manufacture and maintenance under production conditions.

X

Fi.2

Claims (1)

ULTRASONIC FLOW METER, containing two reversible electro-acoustic transducers mounted on opposite walls of the pipeline and connected through a switch to a pulse generator and counter, as well as a control pulse shaper, whose inputs are connected to the outputs of the meter, that, in order to increase the speed and reliability of measurement, a two-channel gating scheme is introduced into it, each channel of which consists of a sequentially connected single-vibrator, a shaper a pulse, a key and an amplifier, as well as random access memory, a comparator, two I circuits, a trigger and a pulse generator, the inputs of both channels of the gating circuit connected to the output of the control pulse generator, and the outputs to the first and second inputs of random access memory, the third and the fourth inputs of which are connected to the outputs of the driver of the control pulses, and the outputs' - to the inputs of the comparator and the first input of the first circuit AND, the second input of which is connected to the output of the driver their pulses. © the comparator output is connected to the first input of the trigger, the second input of which is connected to the output of the first AND circuit, and the fifth input of random access memory, the trigger output is connected to the First input of the second And circuit, the second input of which is connected to the fill pulse generator, while the second key inputs A two-channel gating circuit is connected to the outputs of the switch. SU „1024726