JPH0756457B2 - Flowmeter - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow meter, and more particularly to a flow meter capable of measuring the flow rate of gas flowing continuously.

BACKGROUND ART In order to measure the flow rate of a fluid that continuously flows through, such as city gas, the flow rate is calculated by counting the pulses generated by a Δ-type flow meter.
FIG. 7 is a sectional view showing the operating principle of the Δ type flow meter, and FIG. 8 is a partially enlarged sectional view thereof. As shown in FIG. 7, one plane of the triangular prism 22 is perpendicular to the flow direction of the fluid continuously flowing in the pipe line 21 in the direction indicated by the reference numeral a (from left to right in FIG. 7). It is known that when 22a is placed oppositely, Karman vortices are regularly generated on both sides of the triangular prism 22 as indicated by reference signs b and c, and the number of the vortices is proportional to the flow rate of the fluid. Therefore, the flow rate is to be measured by counting the number of the above-mentioned Karman vortices generated per fixed time, and as shown in FIG. 8, both ends in the width direction of the one plane 22a of the triangular prism 22 are measured. Temperature sensors 23a and 23b realized by a thermistor are arranged in the vicinity. Karman vortices 24a and 24b generated on both sides of the triangular prism 22
This causes a pressure difference in the vicinity of both sides of the triangular prism 22, and the temperature sensors 23a and 23b detect the temperature difference caused by the pressure difference, and derive an electric signal due to the resistance change as a pulse. The flow rate of the fluid is measured by counting these pulses.

Problems to be Solved by the Invention Since the temperature sensor is constantly exposed to the fluid, the dust contained in the fluid has the following adverse effects.

1. Dust collides with the temperature sensor, which causes cracks on the sensor surface, which may cause insulation failure and noise of the sensor, resulting in excessive measurement of the flow rate due to the noise signal. .

2. Due to the dust adhering to the sensor surface, the thermal conductivity of the sensor deteriorates, and the gain required for measurement decreases, resulting in the measurement of the flow rate lower than it actually is.

3. Therefore, in the flow rate measurement using such a Δ type flow meter, it is important to detect whether there is an abnormality in the detector such as the temperature sensor and to judge the quality. For this reason, the signal waveforms derived from the sensor are observed with an oscillograph, etc. every predetermined inspection date, and the quality is judged visually, but from one inspection day to the next inspection day Abnormalities that occur during the period cannot be captured, and if a wrong flow rate calculation is performed for a long time and the measurement target is transaction volume such as city gas, it becomes a serious problem. In addition, if the above-mentioned live line check occurs, an accident such as a short or electric shock may occur. For this reason, there has been a demand for a flow rate measurement system capable of continuously measuring the flow rate of a fluid, maintaining the accuracy of the measured value, and immediately detecting an abnormality in the sensor or a change in the flow rate. .

The object of the present invention is to solve the above-mentioned technical problems, to be able to continuously measure the flow rate of gas, to detect abnormalities in the sensor and fluctuations in the flow rate, and to obtain accurate measured values of the flow rate. Is to provide a flow meter capable of performing the above.

MEANS FOR SOLVING THE PROBLEMS The present invention includes (a) one plane 22 perpendicular to the flow direction in a pipe 21.
and a triangular prism 22 having a space between both ends of the plane 22a in the width direction and the inner surface of the conduit 21, and a pair of thermistors 23a, 23b arranged near both ends of the plane 22a in the width direction. And a Δ type flow meter for deriving a pulse having a cycle corresponding to the flow rate from the thermistors 23a and 23b, (b) setting means D1 for setting the allowable value α% and the number of times judgments are not established, and (c) Δ In response to the pulse from the flow meter, the pulse interval T _(n-1) of the adjacent pulse is read, this cycle T _(n-1) is used as the reference value TN, and the next read pulse interval T _n
Determines whether TN (1-α / 100) ≤ T _n ≤ TN (1 + α / 100) is satisfied.
Repeated the above judgment operation in response to the subsequent pulse without updating TN, and the number of consecutive times was not satisfied.
The flowmeter is characterized by further comprising: a judgment unit 5 which counts NG, and judges that an abnormality has occurred when the counted number of times NG reaches the judgment failure frequency.

The present invention also includes (a) a triangular prism 22 having one flat surface 22a perpendicular to the flow direction in the conduit 21 and having a space between both ends of the flat surface 22a in the width direction and the inner surface of the conduit 21. A Δ type flow meter having a pair of thermistors 23a and 23b arranged near both ends in the width direction of the plane 22a and deriving a pulse having a period corresponding to the flow rate from the thermistors 23a and 23b, (b) Setting means D1, D2, D3 for setting the allowable value β%, the sampling time Ts, and the number of times the judgment is not established, and (c) responding to the pulse from the Δ-type flow meter, the pulse included in the sampling time Ts. number
HZ _(n-1) is counted and read, and this count value HZ _(n-1) is used as a reference value.
HZN, it is determined whether the number HZ _{n of the} pulses included in the next sampling time Ts satisfies HZN (1-β / 100) ≤ HZ _n ≤ HZN (1 + β / 100), If not, the reference value
Subsequent sampling time Ts without updating HZN
Repeat the above-mentioned judgment operation of the count value HZ _(n-1) for each, count the number of consecutive MGs that are not satisfied, and judge that an abnormality has occurred when the counted number MG has reached the number of times the judgment has failed. And a means (5).

Operation According to the present invention, the Δ type flowmeter is provided in the pipe line 21 through which gas flows, and a pair of thermistors arranged near both ends in the width direction of the triangular prism 22 due to dust contained in the gas.
False detection due to 23a, 23b is likely to occur. In particular, the gas has a smaller specific heat than the liquid, and therefore the change in the output depending on the flow rate due to the thermistor is small, and therefore it is necessary to accurately detect the abnormality of the Δ type flow meter. It is possible to reliably detect such an abnormality of the Δ type flow meter.

Further in accordance with the present invention, the determination means uses the pulse interval T
_{With (n-1)} as the reference value TN, it is determined whether the next pulse interval T _n is within the allowable value α%, and such an allowable value α% is determined.
If it is not within the range, the number of consecutive times NG is counted, and it is determined that an abnormality has occurred when the counted number of times NG reaches a predetermined determination failure time.

According to the invention, the number HZ _(n-1) of pulses included in a predetermined sampling time Ts is counted and read as a reference value HZN, and the number of pulses included in the next sampling time Ts. It is determined whether or not HZ _n is within a predetermined allowable value β%, and it is determined that an abnormality has occurred when the number of consecutive times MG, which is not within the allowable value β%, reaches a predetermined determination failure frequency.

Embodiment 1 FIG. 1 is a block diagram showing the structure of a flowmeter 1 according to an embodiment of the present invention, and FIG. 2 is a front view thereof. The input section 2 is provided with a plurality (12 in this embodiment) of input connectors 2a to 2l, and a Δ type flow meter (see FIGS. 7 and 8 described above).
The flow signals from are individually connected. As is clearly shown in FIG. 7, there is a space between both ends of the one plane 22a of the triangular prism 22 in the width direction (vertical direction in FIG. 7) and the inner surface of the conduit 21, and the gas A fluid can flow. These flow rate signals are connected to the individual contacts 3a to 3l of the input selection switch 3 via the lines l1 to l12, the flow rate signals of the lines l1 to l12 are selected by the input selection switch 3, and the selected flow rate signal is selected. Is input to one input terminal 4a of the input circuit 4 via the line l13. The other input terminal 4b of the input circuit 4 has an allowable value α of the reference pulse number.
(%), The allowable value of flow rate fluctuation β (%) and the sampling time Ts (seconds), the numerical data of the digital switches D1, D2, D3 are input via the line l14, and the input selection switch 3 is input. The flow rate data included in the flow rate signal selected by the above and the set amount data from the digital switches D1 to D3 are input to the control / calculation unit 5 via the line l15. The control operation unit 5 is composed of a microcomputer, a read only memory, a random access memory, an input / output interface, etc., and performs reading, storage, operation and comparison of the flow rate data and the set value data, and the result is obtained. The line
It is led to the output circuit 6 via l16a.

A timer circuit 7 for recording / displaying time is provided in parallel with the input of the above-mentioned data, and the time data is derived through a line l16b and is given to the time display unit 8 through a line l17. The time display unit 8 displays the time accordingly. The time display unit 8 digitally displays the month, the day, the hour, and the minute, and is composed of a light emitting element for displaying numbers.

The output circuit 6 is composed of a display drive circuit, a printer drive circuit, an alarm output circuit, etc. which are realized by a relay or the like, and the display drive output is led to the data display unit 9 via the line l18. . The data display section digitally displays the input channel selected by the selection switch 3, the number of input pulses being measured, the sampling time and the allowable value. The printer drive output is led to the printer 10 via line l19. The printer 10 prints the data during measurement and the data when an abnormality occurs. The alarm output is led to the alarm device 11 via the line 120. The alarm device 11 is provided to issue an alarm and notify when abnormal data occurs.

The power supply unit 12 is constantly supplied with electric power from a commercial power supply via a line l18, and transforms and rectifies the electric power to energize the respective circuits constituting the present embodiment via the line l19. Power supply unit 1
2 is provided with a backup power supply 13 which is realized by a battery or the like for backup power at the time of power failure, and the backup power supply 13 is always charged by a part of the output of the power supply unit 12.

FIG. 3 is a diagram showing the input pulse and the pulse interval which are the flow rate data from the flow meter, and FIG. 4 is a diagram showing the relationship between the input pulse and the sampling time. The relationship shown in FIG. 3 is the temperature sensors 23a, 23 which are the thermistors described above.
This is for detecting the occurrence of an abnormality in b, and the relationship shown in FIG. 4 is for detecting the flow rate fluctuation of the fluid to be measured. Hereinafter, FIG. 1, FIG. 3 and FIG.
The operation of this embodiment will be described with reference to the drawings.

First, referring to FIG. 3, an operation of determining the presence / absence of a sensor abnormality will be described. As described above, P1, P2, ..., _Pn are input pulses sent from the flow meter, and the number of input pulses and the flow rate are in a proportional relationship. This input pulse P1, P2,
..., the pulse interval of P _n T1, T2, ..., and T _n. On the other hand, the allowable range α (%) of the pulse interval is previously set to the digital switch.
It is set by D1 and is stored in the control calculation unit 5 via the input circuit 4. When the measurement is started, first, the input pulse interval T1 which is the first measurement data is read and this T1
Is stored as a reference value TN. Next, the second measurement data T2 is read and the determination formula TN (1−α / 100) ≦ T2 ≦ TN (1 + α / 100) (1) given to the control calculation unit 5 in advance is used. The measured reference value T1 and the value T2 measured this time are compared and calculated, and when the first expression is satisfied, T2 is set to the reference value TN.
Is stored and updated, and the updated reference value TN and the next measured value T3 are calculated in the same manner as in the above-mentioned formula 1 TN (1-α / 100) ≦ T3 ≦ TN (1 + α / 100) (2) Then, when the second expression is satisfied, the value is updated and stored with T3 as a reference value, and the same operation is repeated thereafter. Thus, in the process of continuously measuring the input pulse intervals T1, T2, ..., T _(n-1) , T _n , the judgment formula TN (1-α / 100) ≤ T _n ≦ TN (1 + α / 100) (3) If the judgment is not satisfied, the reference value is not updated, and the number of times of failure is set in advance by D1 including this time (this embodiment). Then, the above determination is repeated up to 4 times.
If the judgment is still unsuccessful even if the specified number of times is reached, it is judged to be abnormal, the subsequent measurement is stopped, an error display is output and displayed on the data display unit 9 and printed by the printer 10 (Alarm) is issued to announce. At the same time, the time data at this time is given from the timer 7 to the printer 10 via the control calculation unit 5, and the time when the abnormality occurred is recorded.

Next, the determination operation of the fluid flow rate fluctuation will be described with reference to FIG. P1, P2, ..., _Pm are the input pulses sent from the flowmeter. The allowable range β (%) of the flow rate fluctuation and the sampling time Ts are set in advance by the digital switches D2 and D3, and are stored in the control calculation unit 5 via the input circuit 4. When measurement starts, sampling time Ts
The pulse number HZ ₁ of the input pulses P ₁ to P _n included in the interval is counted and read, and this pulse number HZ ₁ is stored as the reference value HZ _N. Next, the number HZ ₂ of pulses of the input pulses P _{(n + 1)} , ..., P _m included in the sampling time Ts is again counted and read, and the determination formula HZN (1-β is given to the control calculation unit 5 in advance. / 100) ≤ HZ ₂ ≤ HZN (1 + β / 100) ... (4), the previously measured reference value HZN and the presently measured value HZ ₂
Is calculated and when the fourth expression is satisfied, HZ ₂ is set to the reference value H
Update and record as ZN, and this updated reference value HZN,
The next measured value HZ ₃ is compared and calculated according to HZN (1-β / 100) ≤ HZ ₃ ≤ HZN (1 + β / 100) (5) in the same manner as in the above equation 4, and the equation 5 is satisfied. When you do HZ ₃
Is updated and recorded as the reference value HZN, and the same operation is repeated thereafter. In this way, the number of input pulses during the sampling time Ts is continuously counted, and the flow rate fluctuation due to the temperature sensor failure causes the number of input pulses HZ _{n for} each sampling time Ts.
For the judgment formula HZN (1-β / 100) ≤ HZ _n ≤ HZN (1 + β / 100) (6) and the judgment is not satisfied, the reference value is not updated and After that, the measurement data is printed on the printer 10 every predetermined number of times (four times in this embodiment) determined in advance, and the above determination is repeated. If the judgment is still unsuccessful even after the specified number of times is reached, it is judged to be abnormal, the subsequent measurement is stopped, an abnormal display is output and the data display unit 9
Is displayed and is printed by the printer 10, and an alarm is issued from the alarm device 11 to notify. It should be noted that the time data at this time is given from the timer 7 to the printer 10 via the control calculation unit 5, and the time of occurrence of the abnormality is recorded.

Figure 5 is a pulse interval T1, T2 from the flow meter, ..., by measuring the T _n is a flow chart showing an operation for detecting an abnormality of the sensor. In the measurement, the channels to be measured (1 to 12 channels in this embodiment), the measurement time and the allowable value α of the pulse interval are set in advance. Counter count value NG
Reset to zero. After the start, at step n1, the interval T1 between the first pulse P1 and the second pulse P2 is read. The value of T1 is used as a reference value TN and stored in the control calculation unit 5 at step n2. At step n3, the interval T2 between the second pulse P2 and the third pulse P3 is read and the step T3 is read.
Moving to n4, the reference values TN and T2 are compared by the judgment formula shown in the first formula, and if the judgment conditions are satisfied, the step proceeds.
Moving to n5, the reference value is updated and T2 measured this time is stored as the reference value TN. Next, in step n6, the interval T3 between the input pulses P3 and P4 is read, the judgment is made in step n7, and if the judgment condition is satisfied, the step moves to the next step, and the same operation is repeated. As described above, in this embodiment, the pulse interval T _n of the previous measurement is set as the reference value TN, and the reference value TN and the pulse interval T _{(n + 1) of the} current measurement are determined by the preset determination condition. If the determination condition is satisfied, the pulse interval T _{(n + 1)} measured this time is updated as the reference value TN, and the values are sequentially updated and compared. If the determination condition is not satisfied in any of the determination steps and the determination is not satisfied, for example, the determination is not satisfied in step n4 shown in FIG. 5, steps n4 to m1 are performed.
After storing the judgment failure count NG = 1, move to step m2 and print the failure data including the occurrence time,
Return to step n6. Therefore, at this time, the reference value TN is not updated and the previously stored reference value is taken over next time. If the judgment is not satisfied in the same manner in the next step n7, the process moves from step n7 to step m3, increments the judgment failure frequency NG by 1, stores NG = 2, and prints the failure data at this time. Rear step n9
Return to. At this time, the reference value TN is not updated, and the previous reference value is inherited as it is. In this way, if the judgment is not satisfied four times in succession, for example, if the judgment is not satisfied also in step n13, the number of failures is NG in step m7.
Is 4, the data that is not satisfied this time is printed in step m8, and it is determined that there is a sensor error in step n15 because it has failed 4 times. In step m9, the data including the time is printed, and then in step m10, the display 9 Is displayed, an alarm is issued by the alarm device 11, and the subsequent measurement is stopped.

FIG. 6 is a flow chart showing the operation of measuring the number of pulses of the flow meter within a predetermined sampling time to detect the flow rate fluctuation. In the measurement, the channel to be measured, the sampling time Ts, and the allowable range β of the pulse number HZ are set in advance. The counter count value MG is reset to zero. After the start, the first pulse number HZ ₁ is read in step p1, and this pulse number HZ ₁ is stored in the control calculation unit 5 in step p2 as the reference value HZN. At step p3, the second pulse number HZ ₂ is read, and at step p4
Then, the reference values HZN and HZ ₂ are compared by the judgment formula shown in the fourth formula, and if the judgment conditions are satisfied, the step proceeds.
Move to p5, the reference value is updated and the number of pulses measured this time HZ ₂
Is stored as the reference value HZN. Next, in step p6, the next pulse number HZ ₃ is read, the judgment is made in step p9, and if the judgment condition is satisfied, the step moves to the next step,
The same operation is repeated thereafter. Thus, in this embodiment, the pulse number HZ _n of the previous measurement is set as the reference value HZN, and the reference value HZ _n
N and the number of pulses HZ _{(n + 1)} measured this time are judged according to the preset judgment conditions, and if the judgment conditions are satisfied, the number of pulses HZ _{(n + 1)} measured this time is set to the reference value HZN. It will be compared with the following. If the judgment condition is not satisfied in any of the judgment steps and the judgment is not satisfied, for example, step p4 shown in FIG.
If the determination fails in step S4, the process shifts from step p4 to step q1, the determination failure count 1 is stored, the data of the failure is printed including the occurrence time, and the process returns to step p6. Therefore, in this case, the reference value
The HZN will not be updated and the previously stored reference value will be carried over to the next time. If the judgment is not satisfied in the same manner at the next step p7, the process moves from step p7 to step q3, the judgment failure number MG is incremented by 1 and MG = 2.
Is stored, the data that does not hold at this time is printed, and the process returns to step p9. At this time as well, the reference value HZN is not updated, and the previous reference value is inherited as it is. In this way, if the judgment is not satisfied four times in succession, for example, if the judgment is not satisfied also in step p13, the number of failures is 4 in step q7.
Is printed, the flow rate fluctuation is judged to have occurred 4 times in step p15, the data including the time is printed in step q9, and then the data display section 9 is displayed in step q10.
Is displayed on the screen and an alarm is issued by the alarm device 11.
Is issued and the subsequent measurements are stopped.

In this embodiment, the selection of the measurement channel, the setting of the allowable amount, the setting of the sampling time, etc. are made by manual selection. However, a certain program is stored in the control calculation unit in advance as software and Then, the procedure described above may be performed, and the next channel may be automatically selected when one measurement is completed, or if the measurement of that channel is stopped by the determination failure four times as described above. It may be possible to automatically switch to another channel. In this way, it is possible to make continuous measurements of the input from the flow meter over multiple channels. It is needless to say that the determination conditions and the number of times of failure in the present embodiment should be appropriately set depending on the fluid to be measured and the environmental conditions, and the number of times of failure to determine the pulse interval used in step n15 of FIG. Is set by the digital switch D1 as described above, and the step of FIG.
The number of times the flow rate fluctuation determination fails to be used in p15 is also set by the digital switch D1.

Effects As described above, according to the present invention, the Δ type flowmeter is provided in the pipe 21 through which the gas flows, and each Δ type flowmeter has the triangular prism 22 and the pair of thermistors 23a and 23b. In the Δ type flowmeter having the configuration, in view of the fact that the specific heat of gas is generally small, when an abnormality occurs, it is necessary to detect accurately and quickly, and in the present invention, the pulse of the pulse from the thermistor 23a, 23b. Since it was made to check for anomalies regarding the number of pulses included in the interval or sampling time Ts,
Anomalies can be detected quickly and accurately.

Further, according to the present invention, the pulse interval T _(n-1) is read as the reference value TN, and when the next read pulse interval T _n is not within the predetermined allowable value α%, the consecutive number NG is set. Since it is determined that an abnormal inspection has occurred when the number of times NG has been counted and the number of times NG has been counted reaches a predetermined number of times of determination failure, it becomes possible to reliably prevent erroneous detection of fluid flow rate measurement. Further, it is possible to prevent frequent abnormality detection due to mixing of noise.

In the present invention, the number HZ _(n-1) of pulses included during the sampling time Ts is read as the reference value HZN, and the number HZ _{n of} pulses included during the next sampling time Ts is a predetermined tolerance. The number of consecutive MGs when it is not within the value β% is counted, and when the counted number NG reaches the predetermined number of judgment failure times, it is determined that an abnormality has occurred, so that the abnormality of the thermistors 23a, 23b is surely performed. Therefore, it is possible to prevent frequent erroneous detection due to the mixing of noise.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of one embodiment of the present invention, FIG. 2 is a front view of one embodiment of the present invention, FIG. 3 is a diagram showing the pulse intervals of input pulses from a flow meter, and FIG. The figure shows the relationship between the input pulse and the sampling time, FIGS. 5 and 6 are flow charts, FIG. 7 is a sectional view showing the operating principle of a prior art Δ type flow meter, and FIG. 8 is FIG. It is a partially expanded sectional view of a figure. 1 ... Flowmeter, 2 ... Input section, 3 ... Input selection switch, 5 ... Control calculation section, 10 ... Printer, 22 ... Triangular prism, 23a, 23b ... Temperature sensor, 24a, 24b ... Karman Vortex,
D1 to D3 ...... Digital switch, P1 to P _m ...... Input pulse

Front Page Continuation (72) Inventor Kunihiko Takano 5-1, Hirano-cho, Higashi-ku, Osaka-shi, Osaka (Osaka Gas Co., Ltd.) (56) Reference JP 58-173429 (JP, A) JP 59-148819 (JP, A) JP 58-14015 (JP, A) JP 50-46153 (JP, A)

Claims (2)

[Claims] 1. A plane which is perpendicular to a flow direction in a pipe line (a).
22a, a triangular prism 22 having a space between both ends of the plane 22a in the width direction and the inner surface of the conduit 21, and a pair of thermistors 23a, 23b arranged near both ends of the plane 22a in the width direction. And a Δ type flow meter for deriving a pulse having a cycle corresponding to the flow rate from the thermistors 23a and 23b, (b) setting means D1 for setting the allowable value α% and the number of times judgments are not established, and (c) Δ In response to the pulse from the flow meter, the pulse interval T _(n-1) of the adjacent pulse is read, this cycle T _(n-1) is used as the reference value TN, and the next read pulse interval T _n
Determines whether TN (1-α / 100) ≤ T _n ≤ TN (1 + α / 100) is satisfied.
Repeated the above judgment operation in response to the subsequent pulse without updating TN, and the number of consecutive times was not satisfied.
A flow meter, comprising: a judgment unit 5 which counts NG, and judges that an abnormality has occurred when the counted number of times NG reaches the number of times of judgment failure. 2. (a) One plane perpendicular to the flow direction in the pipe line 21.
22a, a triangular prism 22 having a space between both ends of the plane 22a in the width direction and the inner surface of the conduit 21, and a pair of thermistors 23a, 23b arranged near both ends of the plane 22a in the width direction. And a Δ type flow meter for deriving a pulse having a period corresponding to the flow rate from the thermistors 23a and 23b, and (b) setting means D1 and D2 for setting the allowable value β%, the sampling time Ts and the number of times judgments are not established. , D3, and (c) the number of the pulses contained in the sampling time Ts in response to the pulses from the Δ type flow meter.
HZ _(n-1) is counted and read, and this count value HZ _(n-1) is used as a reference value.
HZN, it is determined whether the number HZ _{n of the} pulses included in the next sampling time Ts satisfies HZN (1-β / 100) ≤ HZ _n ≤ HZN (1 + β / 100), If not, the reference value
Subsequent sampling time Ts without updating HZN
Repeat the above-mentioned judgment operation of the count value HZ _(n-1) for each, count the number of consecutive MGs that are not satisfied, and judge that an abnormality has occurred when the counted number MG has reached the number of times the judgment has failed. A flow meter comprising means 5.