SU678304A2 - Flowmeter - Google Patents

Description

The invention relates to a measurement technique and can be used to measure the flow rate using volumetric flow sensors having a frequency output signal with simultaneous density correction. Known flowmeter, protected by the main author. St. USSR No. 426149, containing a flow sensor, a density sensor, a series-connected frequency crystal, a measurement time master, a control trigger, a coincidence circuit, an adder, a pulse counter, a register, and an indicator, the flow sensor connected to the coincidence circuit, and with the adder through a code converter, the output of which is connected to the input of the control trigger, the output of which is connected to the output of the crystal oscillator and to the input of the encoder. The disadvantage of this device is that the correction code corresponding to the offset of the sensor characteristic relative to the origin, which determines the hydraulic losses of the flow sensor, such as volumetric leaks, and embedded in the encoder, is entered into the counter during each measurement cycle, and the digital correction value is constant. It is also displayed on the indicator, including when the signal from the flow sensor stops flowing in the absence of flow. Such a phenomenon reduces the accuracy of the flow measurement, since a false reading of the non-existent flow rate is possible. The aim of the invention is to increase the reliability of flow measurement results by eliminating possible operator error. This goal is achieved by the fact that in the device by the author. St. No. 426149 a one-shot and an additional trigger are introduced, the second output of the pulse counter is connected to the first input of an additional trigger, the output of which is connected to the encoder's input through the one-shot and the second input to the output of the measurement time master. Diagram of the flow meter is shown in the drawing. The flow meter contains a series-connected crystal frequency generator 1, a measurement time processor 2, a control trigger 3, a matching circuit 4, an adder 5, a pulse counter 6, a memory register 7, and an indicator 8. The flow sensor 9 is connected to the second matching input, and the sensor 10 density - through the travel converter 11 with the adder 5. The second output of the code converter 11 is connected to the second control trigger 3 input, the output of which is connected to the input of the crystal oscillator 1. The second output of the counter 6, trigger 12, one-shot 13, cipher Op 14 and the second input of the pulse counter 6 are connected in series, and the second input of the trigger 12 is connected to the output of the measurement time setting unit 2 and the first input of the control trigger 3. . . ,

The flow meter implements the function of converting the frequency of the flow sensor in accordance with the algorithm

G f t - + b

where G is the measured mass flow rate; f is the frequency of the flow sensor signals; T - current measured values

density;

t is the measurement time interval; b is the correction determined by hydraulic leakage of the flow sensor.

Each cyclization begins with a density measurement (y). The signal from the density sensor 10 is fed to a code converter 11, which, after the density measurement is completed, outputs its code value to the input of the adder 5 and generates a command to start control trigger 3. The signal from trigger 3 triggers crystal oscillator 1 and simultaneously opens circuit 4 of coincidence. The quartz generator 1 outputs pulses to the input of the time setting 2, which forms a time interval, (t) equal to the measurement time. In the adder 5, the sum of the density values from the code converter 11 occurs as many times as the pulses (f) pass through the circuit 4 from the sensor 9 consumption for time from T 1yogoy, when the transfer signals are received in the counter b ({f-ft). With the arrival of the first several pulses (for example, ten) in the counter 6 with you678304

its progress (for example, from the youngest decade), a command is sent to trigger the trigger 12, which, tilting, triggers the one-shot 13. The single-vibrator 13 produces a pulse that goes to the encoder 14, which converts the positional code of the correction value (b) typed in it binary-decimal code, and gives it to the inputs of counter 6 (for example, 10 + b).

The duration of the pulse produced by the single vibrator 13 must be less than the half-period duration corresponding to the maximum value of the sensor frequency, i.e. f O / 5 / f so that the correction input in the pulse counter 6 is made between two adjacent pulses (for example, between the tenth and the eleventh).

At the end of the measurement time, on command from the latch 2, the measurement time triggers 3 and 12 are returned to the Home state and the circuit 4 is closed.

The measurement cycle ends, and the mass flow rate (tf + b) is recorded in memory register 7 and calculated on display 8,

Thus, the correction for leakage of the flow sensor is entered at the rate of flow measurement and only under the condition that there is a frequency at the output of the flow sensor.

The use of the proposed device ensures objectivity in the reading of the monitored parameters, since it eliminates the possibility of the operator being deceived about the presence of consumption.

Claims (1)

Invention Formula Flow meter auth. St. 426149, characterized in that, in order to increase the reliability of the flow measurement by eliminating a possible operator mistake, a one-shot and an additional trigger are added to it, the second pulse counter output connected to the first input prior to the trigger, whose output through the one-shot is connected to the encoder's input, and the second with the exit time measurement unit.