JPS5866821A - Correcting device for flow rate - Google Patents

Abstract

PURPOSE:To permit responding to a wide range of input pulse rates by correcting flow rates in accordance with process variables. CONSTITUTION:Flow rate pulses are applied to a counter 8 and a gate 12. The counter 8 counts the pulses during a specified period T, and feeds the count value (n) thereof to an arithmetic part 9 for correction of flow rate at the end of the period T. The part 9 detects (n) pieces of the flow rate pulses and operates the corrected flow rate according to the value of separately applied process variable inputs. The coefft. S of flow rate correction which is the result of the operation is normallized to the value S' that makes 0<S'<1, and S'.n is operated and is applied to an adder-subtractor 10, by which the same is added to the decimal part of the result of the previous addition; thereafter the same is subtracted from the integer part of the result of the addition at every inputting of the flow rate pulse. The gate 12 is controlled by the output of a zero discriminator 11 for the integer part which outputs ''1'' as far as the integer part of the value which is the result of the addition is not ''0'' and the output thereof is the corrected flow rate pulse.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flow correction device for a flowmeter, and more particularly to a flow correction device having a means for improving the pulse rate tolerance range of input flow pulses being limited by the processing speed of the correction device. Regarding.

Generally, when measuring liquid with one flowmeter, the instrument error and diameter of the flow needle are corrected, and the flow rate is corrected for changes in temperature, pressure, viscosity, etc. at the time of measurement, and the flow rate is adjusted to a value at a constant standard temperature. To maintain measurement accuracy, it is necessary to convert the

Conventionally, the flow rate pulse 1 output from the flow meter is
Flow rate correction processing was performed for each individual.

Regarding flow rate correction, electronic calculation methods using microprocessors have recently been increasingly adopted, but their processing speed is relatively slow, so the pulse rate of flow rate pulses that can be processed is approximately 200. Hertz was on TB. On the other hand, the pulse rate of the output flow pulse of a flowmeter in actual use may range up to several kilohertz, and for this reason, conventionally, the input flow pulse is reduced by 1/
When the station was divided into 10 or #i1/100, K was trying to solve the problem.

FIG. 1 #: t% In FIG. 1, which is a block diagram showing the configuration of a conventional flow rate correction device, 1 is a flow rate correction device;
2 is a pulse shaping circuit, 3 is a branch circuit, 4tj A/D conversion circuit, 5acpU, 611 output circuit, 711t front plate switch and display section.

In operation, the flow rate pulse input is waveform-shaped by the pulse shaping circuit 2, divided into an appropriate value by the frequency dividing circuit 3 according to the magnitude of the pulse rate, and is applied to the CPo 5. The CPU 5#'i receives the temperature input through the A/D conversion circuit 4, and calculates the flow rate correction based on the temperature.
According to the calculation result, a corrected flow rate pulse is generated and outputted from the output circuit 6.

The present invention provides a flow rate correction device that can respond to a wide range of input pulse rates without requiring switching of the branch circuit according to the input pulse rate as in the conventional system described above.

The present invention will be described below with reference to Examples.

FIG. 2 is an explanatory diagram of one embodiment of the present invention.

In the figure, 8 I/i counter, 9 a flow rate correction calculation unit,
10Fi adder/subtractor, 11 integer part zero discriminator, 12 AN
D gate is shown.

A flow pulse input is applied to counter 8 and gate 12. The counter 8Fi counts the flow rate pulses during a counting period of a constant period 〒 in the frequency dividing circuit 30s in the conventional method shown in Fig. send. The clearing of the counter 8 and the transfer control of the counting results are performed based on commands from the flow rate correction calculation unit 9. After being cleared, the counter 8 counts the flow rate pulse input for a period T, and at the end of the period T. The counting result is transferred to the flow rate correction calculating section 9, where it is immediately cleared and the counting operation for the next period T is started. Therefore, the flow pulses during the measurement period are counted without much dropout.

The flow rate correction calculation section 9 detects ten input flow rate pulses during the counting period TK, and performs a correction flow rate calculation according to each separately given process variable input value, and sets the flow rate correction coefficient of the calculation result to 8. When, this sFi is further 0<8
0th order normalized to the value 8 where '<1', the value S' multiplied by the count value! is calculated.

The value 1 obtained here is output from the flow rate correction calculation section 9 to the adder/subtractor 10. The adder/subtractor 10 adds the value Z and the decimal part of the result of the previous addition. Next, every time a flow rate pulse is input from the integer part of this addition result, 1
is subtracted by

The flow pulse input for subtraction is applied to the subtraction input of adder/subtractor 100 via AND gate 12.

(AND) 121t is gate-controlled by the integer part zero discriminator 11 which outputs y 11' unless the integer part of the addition result value of the adder/subtractor 1o is l □ l. Therefore, a number of flow pulses equal to the value of the integer part are applied to the AND gate 1
When input from 2 to adder/subtractor 1G, the value of the integer part is 1
01, AND gate 12 is closed. The output of the AND gate 12 obtained at this time is taken out as a corrected flow rate pulse.

By using the 10Kb adder/subtractor so that the decimal part is accumulated into the correction value S' for the next counting period, the error can be reduced to a negligible level over a long measurement period.

In the case of the embodiment described above, the correctable range is approximately a value of θ to 1.

In addition, the counting period T#-i only needs to be set to match the length of time required for the flow rate correction calculation section 9 to execute the correction calculation process, and the pulse rate of the flow rate pulse will not change significantly. However, highly accurate flow rate pulse correction can be performed without the need to change set values.

FIG. 3 is a block diagram of another embodiment of the present invention.

In the figure, 13Fi is a pulse shaping circuit, and 14 is a color.
15 is an arithmetic control clock, 16 is a flow rate correction calculation section, 17 is a process variable input section, 18 is a normalization section, 19 is an adder, 20 Fi differentiation circuit, 21 FiR8 flip-flop, and 22 Fi amplifier.

The input flow rate pulse is waveform-shaped by the pulse shaping circuit 13 and applied to the counter 14K.

The counter 14 has the same operational functions as the counter 8 described in the embodiment of FIG. The counter 14 is cleared after the flow rate pulse number counted during the period T is transferred to the flow rate correction calculation section 16 at the end of the period T.

The flow rate correction calculation section 16 operates according to the clock signal from the calculation control clock 15, generates transfer and clear signals to the counter 14, and performs flow rate correction calculation according to the count value read from the counter and the process variable input. Process. , the correction amount is double that for one flow rate pulse.

The arithmetic-processed nine result value S is processed by the normalization unit 18 as (
It is normalized to a value S' in the range 0<8' (1) and sent to the adder 19.

The adder 19 adds the data S/ and the decimal part of the previous addition result, and if there is a carry to the integer part, outputs it to the differentiating circuit 20.

The differentiating circuit 20 differentiates the integer part 1]1 pulse from the adder 19, extracts its leading edge pulse, adds it to the 8 inputs of the R8 flip-flop 21, and divides it. Therefore, the Q output of the flip-flop is "11", but
The flow rate pulse input immediately after is the R of the flip-flop.
When applied to the input, the flip-flop is reset and the Q output returns to the IO level.

The Q output change of the flip-flop 21 at this time is amplified by the amplifier 22 and output as a corrected rate pulse.

This corrected flow rate pulse output is used to drive a flow rate indicator such as an electromagnetic counter.

In this embodiment, the number of corrected flow rate pulse outputs generated in one counting period '1' is one or zero. Therefore, when the measurement time is sufficiently long, the ratio of the number of input flow rate pulses to the number of corrected output flow rate pulses, that is, the correction coefficient S
The allowable range is 0<S<1/%.

In the embodiment shown in FIG. 3, the integer part is taken out from the adder 19 by detecting the value of the integer part digit position of the addition result. If only the decimal part is used and the integer part is taken out as an overflow signal of the addition result, the contents of the arithmetic register can be used as is as the decimal part input in the next addition operation.

As described above, the present invention provides a highly accurate flow rate correction device that responds to flow rate pulse inputs with a wide range of pulse rates without switching.
Operation can be facilitated.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the configuration of a conventional flow rate correction device, FIG. 2 is a diagram showing the configuration of one embodiment of the present invention, and FIG. 3 is a diagram showing the configuration of another embodiment of the present invention. . In the figure, 8 is a counter, 9 is a flow rate correction calculating section, and 30 is a counter.
#-1 adder/subtractor, 11 is integer part zero discriminator, 12 is AND
Each gate is shown.

Claims (2)

[Claims] (1) A means for inputting flow rate pulses, a means for inputting process variables such as temperature and pressure necessary for flow rate correction, and a counter for repeatedly counting the input flow rate pulses at a constant cycle. , comprising means for reading out counting results for each foot cycle from the counter and calculating a corrected flow rate based on the input nine process variables, and means for outputting the calculated result in synchronization with the flow rate pulse. Flow rate correction device. (2) In the first item, the means for outputting the calculated result in synchronization with the flow rate pulse normalizes the calculated flow rate correction coefficient 8 to a value S' that satisfies 0<8'<i. Further, the normalized value S' is multiplied by the count result of the friend flow rate pulse counted at regular intervals to obtain nine values! has an adder/subtractor configured to perform addition with the decimal part of the previous addition result as one input and the decimal part of the previous addition result as the other input, and to subtract the flow rate pulse input from the integer part of the added result. A flow rate correction device characterized in that the flow rate pulses inputted until the value of the integer part becomes zero in the subtraction described above are simultaneously output as corrected flow rate pulses.