RU2086924C1 - Vibration flow rate converter - Google Patents

Abstract

FIELD: instrumentation engineering, measurement of mass flow rates of substances. SUBSTANCE: vibration flow rate converter incorporates primary converter 1, stabilizer 5 of oscillation amplitude, two pulse formers 6 and 7, two flip-flops 8, 13, high-frequency generator 9, two frequency dividers 10, 16, three pulse counters 11, 12 and 17, AND gates 14 and 15, register 18 and output bus 19. EFFECT: enhanced functional stability and accuracy. 2 dwg

Description

 The invention relates to instrumentation and can be used to measure the mass flow rate of the substance flows in the oil, chemical, metallurgical and other industries.

 Known vibrational flow transducer, containing an elastic nozzle pinched in the housing, communicating at a pinch point with a controlled medium, an adapter connected via a frequency converter to the input of the frequency voltage converter, with the input of the AGC block, with the first input of the ratiometric voltage to frequency converter and with the first input of the amplifier and the input of the current-voltage converter, the AGC block connected to the output of the setup master and the second input of the amplifier, and additionally a divider and a subtraction block, is connected nny first input to the output of current voltage converter, a second input to the output of the divider through the adapter and to the ratiometric converter output voltage-to-frequency (1).

 The closest analogue of the invention is a vibration transducer made on two pipelines mounted in the housing with the possibility of vibrations with an oscillation excitation unit and first and second signal pickup units placed thereon, an ambiguity element, a first counter, a high-frequency generator connected in series, dividers and a second counter, a trigger and an output converter, the first signal pick-up unit through a series connection of the first pulse shaper and the oscillation stabilization unit connected to the oscillation excitation unit, the output of the second signal pickup unit through the second driver with the control unit, the output of the galvanic isolation unit is connected to the input of the output converter, the first input of the connection trigger with the first output of the control unit and the preset input of the second counter connected by the overflow output to the second input the trigger, and the reset input with an inverse output of the trigger connected by a direct output to the input of the galvanic separation unit, the outputs of the first and second form s pulses are connected to respective inputs nonequivalence element connected to the enable input of the first counter, counting input connected with the output of the high frequency oscillator, a reset input to the second output of the control unit, and outputs to the inputs of presetting the second counter (2).

 The disadvantage of the analogue is the low accuracy of the measurements.

 This drawback is due to the fact that the pulse width is used as the value by which the flow is judged, proportional to the time shift between the pickup signals. However, this time shift is the algebraic sum of the initial time shift due to the unequal amplitude of the oscillations of the sides of the pipelines and the difference in the shape of the signals from the signal pick-up nodes, depending on the material and the structural dimensions of the sensor, and the time shift proportional to the mass flow rate of the medium measurements. There is no compensation for the initial time shift, and moreover, there is a digital multiplication of the time shift by a factor of about 40 or more, which leads to a corresponding decrease in the measurement accuracy. In addition, in the prototype it is impossible to isolate or the measuring range without reducing accuracy, since there is no possibility of compensating for the time shift corresponding to the beginning of the measuring range.

 The technical result of the invention is to improve the accuracy of flow measurement.

 This is achieved by the fact that a second trigger, a first AND element, a second frequency divider, a third pulse counter, a register and an output bus are introduced into the device, the first input of the second trigger connected to the output of the second pulse generator and the second input of the first trigger, the second output of which is connected to the recording synchronization input of the second pulse counter, the first output of the first trigger is connected to the second input of the second element And, the first input of which is connected to the output of the high-frequency generator and the first input of the first element the second input of which is connected to the output of the second trigger, the second input of which is connected to the output of the first pulse shaper and the zero input of the first pulse, the summing input of which is connected to the output of the first element And, the output of the second element And is connected to the input of the first frequency divider and the input of the second a frequency divider whose output is connected to the subtracting input of the third pulse counter, the recording synchronization input of which is connected to the reverse transfer output of the second pulse counter and the synchronization input and the register records having inputs connected to third outputs of the pulse counter and the register outputs are connected to the output bus.

 In FIG. 1 provides a functional electrical diagram of a vibratory flow transducer; in FIG. 2 timing diagrams explaining the operation of the converter.

 The vibrational flow transducer comprises a primary transducer 1, including an oscillation excitation unit 2 and signal pickup units 3 and 4, an oscillation amplitude stabilization unit 5, a first 6 and a second 7 pulse shapers, a first trigger 8, a high-frequency generator 9, a frequency divider 10, a first 11 and the second 12 pulse counters, the second trigger 13, the first 14 and second 15 elements And, the second frequency divider 16, the third pulse counter 17, the register 18, the output bus 19.

 In FIG. 2 shows the following diagrams 20 and 21 signals at the output of the nodes 3 and 4 of the detachment 22 and 23 signals at the output of the drivers 6 and 7, 24 - the signal at the output of the trigger 13, 25 the signal at the output of the counter 11, 26 the signal at the output of the trigger 8, 27 and 28 signals at the outputs of the counters 12 and 17, 29 is a signal at the output of the register 18 and the output bus 19.

 The converter operates as follows.

The node 2 of the excitation of oscillations, the node 3 of the signal pickup, block 5 and the driver 6 form a positive feedback loop, exciting oscillations of the pipelines of the primary Converter 1. In this case, block 5 stabilizes the amplitude of the oscillations. The output signals of nodes 3 and 4 (respectively, diagrams 20 and 21 in Fig. 2) are fed to the inputs of the shapers 6 and 7, where they are compared with the reference voltage U _op. , and as a result of the comparison, rectangular signals are formed (diagrams 22 and 23, respectively), and the time shift between the signals in diagrams 22 and 23 represents the time shift between the fluctuations of the pipelines, proportional to the measured flow rate. The signals from the outputs of the shapers 6 and 7 are fed to a trigger 13, at the output of which a pulse signal T _i is generated in each measurement cycle (diagram 24). The value of T _{i is} proportional to the time shift between the input signals. From the output of the trigger 13, the signal is fed to the second input of the first element And 14, allowing the passage of pulses from the output of the high-frequency generator 9 through the first input of the element And 14 to the summing input of the first counter II of pulses during the time T _i (chart 25). After the time T _i at the output of the counter 11 is fixed code N _i
N _i T _i • f _o
where f _{o the} frequency of the generator 9.

зафиксированного на счетчике 17 по истечении времени τ_i-1 и равного

в регистр 19 (диаграмма 29), а задним фронтом производит запись кода N_i из счетчика 11 в счетчик 12 и установочного кода C в счетчик 17, подготавливая следующий цикл измерения.This code N _i is stored in the counter 11 until the start of the next measurement cycle. Simultaneously with the expiration of time T _i (on the trailing edge of the pulse from the driver 7), the trigger 8 is set to a single state (diagram 26), thereby allowing the passage of pulses from the output of the generator 9 through the first input of the second element And 15 to the first and second parts 10 and 16 frequencies at which the coefficients are set frequency f _a
f _a = f _o • A,
begin to arrive at the subtracting input of the second counter 12 pulses, in which the code N _i -1 is written from the outputs of the counter 11, which is the result of the previous measurement cycle (chart 27). Simultaneously with the output of the frequency divider 16, the pulses with a frequency f _b
f _b = f _o • B
begin to arrive at the subtracting input of the third pulse counter 17, in which the code C is written (diagram 28). These pulses will be supplied to the counter 17 during the time τ _{i-1 of the} determined value of the code N _i-1 and frequency f _a
τ _i-1 = N _i-1 : f _a ,
after which a pulse appears at the output of the counter-transfer of the counter 11, which sets the trigger 8 to the zero state by the leading edge, thereby blocking the passage of the pulse from the generator 9 through the second element And 16 and frequency dividers 10 and 16 to the subtracting inputs of the counters 12 and 17, and record code

fixed on the counter 17 after a time τ _i-1 and equal

in register 19 (chart 29), and trailing edge writes the code N _i from the counter 11 to the counter 12 and the setting code C in the counter 17, preparing the next measurement cycle.

где T_i-1 величина временного сдвига между выходными сигналами в предыдущем цикле измерения.Thus, after each measurement cycle at the output of the register 18 (the inverted output of the register is used in the invention) and on the output bus 19, the code Y _{i-1 is set} (diagram 29)

where T _{i-1 is the} amount of time shift between the output signals in the previous measurement cycle.

The indicated time shift is the algebraic sum of the initial time shift due to the unequal amplitude of the oscillations and the difference in the shape of the signals from the signal pickup nodes 3 and 4 and the time shift proportional to the mass flow rate of the medium being measured. The selection of the coefficients A, B and C and the frequency f _o compensate for the initial shift. Thus, the output code Y _i will be directly proportional to the mass flow rate. In addition, by selecting the indicated coefficients and frequencies, it is possible to change the beginning of the measurement range and the width of the range, thereby increasing the accuracy of the measurement without carrying out structural changes to the converter.

 As the results of calculations showed when using a flow transducer, it is possible to achieve an increase in the accuracy of the consumption of substances up to 0.25%

Claims (1)

 A vibratory flow transducer comprising a primary transducer made of two pipelines fixed in the housing with the possibility of vibrations, with an oscillation excitation unit and first and second signal pickup units placed thereon, an oscillation amplitude stabilization unit, a first and second pulse shaper, a first trigger, a high-frequency generator , the first frequency divider, the first and second pulse counters, the first signal pick-up unit through the first pulse shaper and the block the tabulation of the amplitude of the oscillations is connected to the node of the excitation of oscillations, the output of the second node of the signal pickup is connected to the second pulse generator, the output of the first frequency divider is connected to the subtracting input of the second pulse counter, the preset inputs of which are connected to the outputs of the first pulse counter, and the reverse transfer output of the second pulse counter connected to the first input of the first trigger, characterized in that the second trigger, the first and second elements And, the second frequency divider, the third count are introduced into it a pulse meter, a register and an output bus, the first input of the second trigger connected to the output of the second pulse shaper and the second input of the first trigger, the second output of which connected to the recording synchronization input of the second pulse counter, the first output of the first trigger connected to the second input of the second element And, the first the input of which is connected to the output of the high-frequency generator and the first input of the first element And, the second input of which is connected to the output of the second trigger, the second input of which is connected to the output of the first form pulse counter and the zero input of the first pulse counter, the summing input of which is connected to the output of the first element And, the output of the second element And is connected to the input of the first frequency divider and the input of the second frequency divider, the output of which is connected to the subtracting input of the third pulse counter, recording synchronization input which is connected to the output of the reverse transfer of the second pulse counter and the synchronization input of the register record, the inputs of which are connected to the outputs of the third pulse counter, and the outputs of the register with connected to the output bus.

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