JP3614305B2 - Flow meter miscounting prevention device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
More specifically, the present invention relates to a flow meter miscounting prevention device, and more specifically, prevents simultaneous counting of a transmission pulse caused by a fluid fluctuation phenomenon caused by a change in supply pressure or the like during operation stop and a vibration of a pipe. In addition, the present invention relates to an erroneous counting prevention device for a flow meter that prevents the initial state from being returned to the initial state even if a temporary missing pulse occurs during measurement.
[0002]
[Prior art]
As an apparatus for preventing erroneous counting of a flow meter, there is an apparatus disclosed in Japanese Utility Model Publication No. 53-14199. For example, in a flow measurement device for compressible fluid, even if the shutoff valve provided on the downstream side of the flowmeter is closed, the gas is compressed and expanded in the pipeline closed by the compressible fluid such as gas. If the part moves and the flow meter detects this, the flow meter may be counted up and erroneous counting may occur. When the above movement is repeated, that is, when the gas fluctuates, this miscount is increased.
[0003]
In order to cope with such a case, the technique disclosed in the above publication is connected between a signal transmission unit that transmits a pulse signal by connecting to a flow rate detection unit installed in a pipeline and a counting mechanism that counts this signal. A timer and an accumulation counter are disposed in the counter, and when the accumulation counter count value is small within a set time set in the timer, a signal to the counting mechanism is blocked to prevent erroneous counting of the counting mechanism.
[0004]
[Problems to be solved by the invention]
In recent years, with the increase in sensitivity of flowmeters, A) Transmitting pulses due to fluctuations of fluid generated due to changes in supply pressure, etc. while the use of fluid (compressible gas) is stopped, B) Operation Several problems occur at the same time, such as counting the number of mispulses transmitted from the sensor during stoppage due to vibration of the pipe, etc., and C) returning to the initial state if a temporary missing pulse occurs during measurement. There was a problem that the flow measurement was not performed accurately.
[0005]
The present invention has been made in view of the above-described circumstances, and is transmitted from a sensor by a transmission pulse due to a fluctuation phenomenon of a gas generated by a change in supply pressure or the like during suspension of use of a compressible gas, vibration of a pipe, or the like. In addition, the counting of missed pulses is prevented at the same time, and even if a temporary missing pulse occurs during measurement, it will not return to the initial state, or even if it returns to the initial state, the erroneous counting of the flowmeter will be slight. A prevention device is provided.
[0006]
[Means for Solving the Problems]
The invention of claim 1 includes a timer and a first NAND element to which a pulse signal from a flow meter sensor is input, an accumulation counter that is reset by the timer and receives the output of the first NAND element, and A first erroneous counting prevention circuit having an inverting element that inverts an output of the accumulation counter and inputs the first NAND element and a second NAND element that inputs the pulse signal and the output of the accumulation counter; A second miscount prevention circuit having the same configuration as that of the first miscount prevention circuit is connected in cascade, and the reset time of the timer of the one miscount prevention circuit and the count set value of the accumulation counter are set to vibration of a pipe or the like. The reset time of the timer of the other erroneous counting prevention circuit and the count setting value of the accumulation counter are values corresponding to the fluctuation of the fluid. And then, with it, in which so as to prevent the counting of the outgoing pulse by swinging phenomenon of Misuparusu and gases due to vibration or the like of the pipe during the shutdown time.
[0007]
According to a second aspect of the present invention, in the flow counter erroneous counting prevention device according to the first aspect, the set time of one timer of the two erroneous count prevention circuits is set shorter than the set time of the other timer, The accumulation counter setting value of the erroneous counting prevention circuit having the short timer is set to be shorter than the setting value of the other accumulation counter. The transmission pulse due to the vibration of the fluid is prevented, and the transmission pulse due to the fluid oscillation phenomenon is prevented by the other erroneous counting prevention circuit.
[0008]
According to a third aspect of the present invention, in the flowmeter miscounting prevention device according to the second aspect, the set time of the short timer is set slightly longer than the cycle of the minimum flow rate of the flowmeter. Therefore, even if a temporary missing pulse occurs during measurement due to some cause, or even if the accumulation counter is reset beyond the set time of the timer, set the accumulation counter to a smaller value. In this way, pulse omission is minimized.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram showing the configuration of an erroneous counting prevention circuit that forms the basis of the present invention, in which 1 is an input terminal, 2 is a timer, 3 is an accumulation counter, 4 is a first NAND element, and 5 is inverted. An element, 6 is a second NAND element, and 7 is an output terminal.
[0010]
The input terminal 1 is connected to the input terminal of the timer 2 and one input terminal of each of the first NAND element 4 and the second NAND element 6, and the output terminal of the timer 2 is connected to the reset terminal of the accumulation counter 3. It is. The timer 2 is a restart type timer that restarts whenever a transmission pulse is input before the time is up. The output terminal of the accumulation counter 3 is connected to the input terminal of the inverting element 5 and the other input terminal of the second NAND element 6.
[0011]
The output terminal of the inverting element 5 is connected to the other input terminal of the first NAND element 4, and the output terminal of the first NAND element 4 is connected to the input terminal of the accumulation counter 3. The accumulation counter 3 can arbitrarily set the number of pulses to be counted.
[0012]
Hereinafter, the erroneous counting prevention circuit of FIG. 1 will be described with reference to the pulse waveform time charts of FIGS. 2, 3, and 4.
FIG. 2 is a time chart for preventing erroneous counting due to swing development. IN is a signal output from the flow meter and input to the input terminal 1, and OUT is a signal output from the output terminal 7.
The oscillation phenomenon is that a part of the gas moves due to the compression / expansion of the fluid in the pipe line closed by the compressive fluid such as gas, and this is detected by the sensor of the flow meter. In order to prevent the oscillation phenomenon, the accumulation counter 3 counts up when the n ₀ pulse signals are input, opens the second NAND gate 6 and outputs an input pulse. At this time, the first NAND gate 4 is closed and the counting is stopped. The timer 2 restarts whenever a transmission pulse is input as described above. However, when τo seconds elapse from the last transmission pulse to the next transmission pulse, the timer 2 outputs a time-up output. Output and reset the accumulation counter 3. The cycle of the input pulse is set to be shorter than the cycle τs of the pulse signal at the minimum flow rate of the flow meter.
[0013]
Now, when the pulse output from the flow meter is input to the input terminal 1, the timer 2 is restarted each time, and the output of the accumulation counter 3 remains at the Lo level until it reaches the set value of the accumulation counter 3. Therefore, the output of the inverting terminal 5 becomes Hi level, the first NAND element 4 is kept open, and the input pulse is accumulated in the accumulation counter 3. At this time, since the second NAND element 6 is closed, there is no output to the output terminal 7.
[0014]
For example, if the accumulation counter 3 counts no-1 pulses, and there is no pulse output from the flowmeter, and τo seconds have elapsed (IN in FIG. 2), the accumulation counter 3 outputs the accumulation counter by the time-up output of the timer 2. 3 is reset and the count n becomes zero (OUT in FIG. 2). When the measurement is started and the output from the flow meter continues to exceed no, the output of the accumulation counter 3 is converted to Hi when the number reaches no, and therefore the output of the inverting element 5 becomes Lo. Therefore, the first NAND element 4 is closed, the count value of the accumulation counter 3 is stopped, and the integrated value is held, but the second NAND element 6 is opened, so that the input terminal 1 is input to the output terminal 7. A pulse is output, and the flow rate measurement is started by a counting mechanism (not shown) from the number in which no pieces are excluded (OUT in FIG. 2).
[0015]
Here, since the set number no of the accumulation counter 3 and the elapsed time τo of the timer 2 can be set in accordance with the state of the transmission pulse due to the oscillation phenomenon, counting of the transmission pulse due to the oscillation phenomenon can be prevented. When the measurement is started, the set value no pulse of the accumulation counter 3 is not integrated. However, the value is such that the no pulse can be ignored with respect to the total integrated pulse during operation, and there is no problem.
[0016]
FIG. 3 is a time chart for preventing erroneous counting due to vibration of the piping. Misflow may be transmitted from the sensor of the flowmeter while the fluid is stopped due to vibration of the piping. In order to prevent this miss pulse, the accumulation counter 3 is set to n ₀ ′, and the timer 2 is set to τ ₀ ′ (τ ₀ ′ <τ ₀ ). If now Misuparusu in stop to the input terminal 1 is input, n 0 _'or less Misuparusu and tau _0' seconds took n _{0 'or} fewer Misuparusu in Misuparusu is pulse as described for FIG. 2 Not output. Operation starts, the output from the flow meter _'when it exceeds number of, n _0' n ₀ flow rate measurement is started from the number the number that has been eliminated. Here again, the set number n ₀ ′ of the accumulation counter 3 and the elapsed time τ ₀ ′ of the timer 2 can be set according to the appearance of the miss pulse, so that it is possible to prevent the miss pulse from being counted due to the vibration of the stopped pipe. it can.
However, when the set time τ ₀ ′ of the timer 2 is shortened in order to prevent the counting of miss pulses, there is a problem that the initial state is restored if a temporary pulse loss occurs due to some cause during operation.
[0017]
FIG. 4 is a pulse chart when the setting of the timer 2 is shortened.
For example, when the set time τ ₀ ′ of the timer 2 is set to a cycle near the minimum flow rate and one pulse is missing for some reason during the measurement, the set time τ ₀ ′ of the timer 2 is short, so Before the pulse is input, τ ₀ ′ or more elapses, and the accumulation counter 3 is reset by the time-up output of the timer 2 to return to the initial state at the beginning of fluid flow. Therefore, even if one missing pulse occurs, the actual output will be 1 + n ₀ 'missing pulses, and if the value of n ₀ ' is large, the total integrated value during operation may not be ignored. It was.
[0018]
FIG. 5 is a block diagram of an erroneous counting prevention device for a flowmeter according to the present invention in which the erroneous counting prevention circuit of FIG. 1 is cascade-connected. A circuit having the same structure as the erroneous counting prevention circuit (hereinafter referred to as a second erroneous counting prevention circuit) is added to the erroneous counting preventing circuit (hereinafter referred to as a first erroneous counting prevention circuit) that forms the basis of the present invention shown in FIG. In the figure, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.
The set time of the timer 2 of the first miscount prevention circuit is τ ₁₀ , the set number of the accumulation counter 3 of the first miscount prevention circuit is n ₁₀ , and the set time of the timer 2 of the second miscount prevention circuit is τ ₂₀ , the setting number of the accumulation counter 3 of the second erroneous counting prevention circuit is set to n _20, and τ ₁₀ <τ ₂₀ , n ₁₀ <n ₂₀ is set, and the setting time of the timer 2 of the first erroneous counting prevention circuit τ ₁₀ is set slightly longer than the cycle at the minimum flow rate of the flow meter. The effect is the same even if the first erroneous counting prevention circuit and the second erroneous counting prevention circuit are installed in reverse.
[0019]
FIG. 6 is a diagram illustrating a pulse state at each input terminal of FIG.
During the stop, the first count time τ ₁₀ of the timer 2 of the first miscount prevention circuit is shortened and the set number n ₁₀ (n ₁₀ = 1 in FIG. 6) of the accumulation counter 3 is reduced, so that the first of Misuparusu that in erroneous counting prevention circuit caused by vibration of the pipe, amount that exceeds the set number n ₁₀ of the storage counter 3 is output from the output terminal 7 of the first error counting prevention circuit. Next, since the set time τ ₂₀ of the timer 2 of the second miscount prevention circuit is lengthened and the set number n ₂₀ (n ₂₀ = 4 in FIG. 6) of the accumulation counter 3 is increased, the first miscount is calculated. Mispulses that could not be removed by the prevention circuit or pulses caused by a fluctuation phenomenon in which the number of pulses is relatively large are removed by the second miscounting prevention circuit, and the stopped output from the output terminal 8 disappears.
[0020]
When the operation is started, n ₁₀ pulses, which is the set number of the accumulation counter 3, are missed by the first erroneous counting prevention circuit and output from the output terminal 7 of the first erroneous counting preventing circuit. the by two erroneous counting prevention circuit, the first error n ₂₀ pulses is a set number of counts prevention n ₁₀ amino accumulated pulse counter 3 is exited in the circuit is added (n _{10) +} (n in ₂₀ ) The number of pulses is missing and output from the output terminal 8.
[0021]
Further, even if a pulse drop occurs for some reason during operation, the set time τ ₁₀ of the timer 2 of the first miscount prevention circuit is set slightly longer than the minimum flow time period of the flow meter. The time-up output is not output and is output from the output terminal 7 of the first erroneous counting prevention circuit without returning to the initial state. Even if there is a missing pulse and the timer 2 times out, since the set value of the accumulation counter 3 is set to be small, the influence is minimal. Next, in the second miscounting prevention circuit, since the set time τ ₂₀ of the timer 2 is set to be long, similarly, it is output from the second output terminal 8 without returning to the initial state.
[0022]
【The invention's effect】
According to the first aspect of the present invention, the timer and the first NAND element to which the pulse signal from the flow meter sensor is input, respectively, and the accumulation counter that is reset by the timer and receives the output of the first NAND element. And an inverting element that inverts the output of the accumulation counter and inputs it to the first NAND element, and a second NAND element that inputs the pulse signal and the output of the accumulation counter. In addition, a second miscount prevention circuit having the same configuration as the first miscount prevention circuit is cascade-connected, and the reset time of the timer of the one miscount prevention circuit and the count setting value of the accumulation counter are connected to the pipe. The value corresponding to the vibration, etc., and the reset time of the timer of the other miscounting prevention circuit and the count setting value of the accumulation counter were values corresponding to the fluctuation of the fluid , It is possible to prevent counting of outgoing pulses arising under rocking phenomenon of vibration and fluid piping caused by changes in supply pressure such as during the stop of the supply of fluid, such as at the same time.
[0023]
According to a second aspect of the present invention, an accumulation of the miscount prevention circuit having the timer set shorter than the set time of the other timer among the two miscount prevention circuits is set. Since the setting value of the counter is set to be shorter than the setting value of the other accumulation counter, the same effect as in the first aspect can be obtained.
[0024]
According to the invention of claim 3, since the set time of the timer set short is set slightly longer than the cycle at the minimum flow rate of the flow meter, in addition to the effect of claim 2, a temporary pulse is generated during measurement. Even if the omission occurs and the state returns to the initial state, the influence can be minimized by setting the set value of the connected accumulation counter to a small value.
[Brief description of the drawings]
FIG. 1 is a block diagram showing the configuration of an erroneous counting prevention circuit that forms the basis of the present invention.
FIG. 2 is a time chart for preventing erroneous counting due to a swing phenomenon.
FIG. 3 is a time chart for preventing erroneous counting due to vibration of piping and the like.
FIG. 4 is a time chart when the timer setting is shortened.
5 is a block diagram of an erroneous counting prevention device for a flowmeter according to the present invention in which the erroneous counting prevention circuit of FIG. 1 is cascade-connected. FIG.
6 is a diagram showing each pulse state at each input / output terminal of FIG. 5. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Input terminal, 2 ... Timer, 3 ... Accumulation counter, 4 ... 1st NAND element, 5 ... Inversion element, 6 ... 2nd NAND element, 7 ... Output (input) terminal, 8 ... Output terminal.

Claims (3)

A timer and a first NAND element each receiving a pulse signal from a flow meter sensor, an accumulation counter reset by the timer and receiving the output of the first NAND element, and an output of the accumulation counter are inverted The first erroneous counting prevention circuit has a first erroneous counting preventing circuit having an inverting element that inputs to the first NAND element and a second NAND element that inputs the pulse signal and the output of the accumulation counter. Cascade connection of the second erroneous counting prevention circuit having the same configuration as the circuit, the reset time of the timer of the one erroneous counting prevention circuit and the count setting value of the accumulation counter is a value corresponding to vibration of the pipe, etc. The error of the flowmeter is characterized in that the reset time of the timer of the other erroneous counting prevention circuit and the count set value of the accumulation counter are values corresponding to the fluid fluctuation. Number prevention device. Of the two erroneous counting prevention circuits, the setting time of one timer is set shorter than the setting time of the other timer, and the setting value of the accumulation counter of the erroneous counting prevention circuit having the shorter timer is stored in the other 2. The erroneous counting prevention device for a flow meter according to claim 1, wherein the counter is set to be shorter than a set value of the counter. 3. An erroneous counting prevention apparatus for a flow meter according to claim 2, wherein the set time of the short timer is set slightly longer than the cycle of the flow meter at the minimum flow rate.

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