JP2023149994A - gas cutoff device - Google Patents

Abstract

To provide a gas cutoff device capable of preventing erroneous determination as a leakage due to fluctuations in instantaneous flow rate due to pulsation or breathing phenomena.SOLUTION: The gas cutoff device is configured so as to accumulate at predetermined intervals the flow rate values calculated by a flow rate calculation unit 3 from the instantaneous flow rate measured by a flow rate measurement unit 2, and a flow rate existence/absence determination section 6 determines whether the flow rate exists/absent based on the result of a first determination unit 4 that determines whether the integrated flow rate value is equal to or higher than a predetermined flow rate and the result of a second determining unit 5, which determines whether the continuous time in which the integrated flow rate value of the first determining unit 4 is less than the predetermined flow rate is longer than the unit integration period.SELECTED DRAWING: Figure 1

Description

The present invention relates to a gas cutoff device that detects the presence or absence of a leak.

Conventionally, gas shutoff devices have a function of detecting gas leakage and issuing an alarm or shutting off the gas.
For example, leakage detection involves monitoring the flow rate in gas piping, determining the presence or absence of gas flow based on predetermined conditions, clearing the leakage determination timer when determining that there is no flow rate, and determining a leak when determining that there is a flow rate. A common operation is to count a timer and determine that there is a leak when a predetermined period of time (for example, 30 days) has elapsed on the leak determination timer, and issue an alarm or shut off. Therefore, in determining whether there is a leak or not, it is necessary to reliably determine whether there is a flow rate or not.

In addition, with city gas, fluctuations in gas supply pressure, pressure fluctuations (hereinafter referred to as pulsations) due to the use of gas equipment such as gas engines, heat pumps, and air conditioners, and temperature changes (rises and falls) during the day, etc. Gas flow over a long period of time (hereinafter referred to as breathing phenomenon) occurs due to pressure fluctuations in the gas piping due to the influence of gas pipes. Therefore, by determining whether there is a flow rate or not, taking these factors into consideration, it is determined whether there is a leak or not. It is being considered.

For example, in Patent Document 1, a moving average flow rate within a predetermined section (for example, 20 minutes) is calculated from a section average flow rate (for example, an average flow rate for 2 minutes), and a maximum moving average flow rate and a minimum moving average flow rate within the predetermined section are calculated. If the difference between the two is within a predetermined range (for example, 0.5 L/h), the section average flow rate is within a predetermined range (for example, ±11 L/h), and the maximum value of the instantaneous flow rate from which the section average flow rate is calculated. The cumulative average flow rate obtained by accumulating and averaging M (for example, 30) area average flow rates included in the moving average flow rate for which the difference between (for example, 1.1 L/h), it is determined that there is no flow rate.

Japanese Patent Application Publication No. 2016-50906

However, in Patent Document 1, even if there is no gas leakage in the gas piping and no gas is used, if a large variation occurs due to fluctuations in the instantaneous flow rate due to pulsations, the instantaneous flow rate used to calculate the section average flow rate is The difference between the maximum and minimum flow rates may be outside the specified range, or the difference between the maximum moving average flow rate and the minimum moving average flow rate may be outside the specified range. Since the conditions for determination cannot be met and it is erroneously determined that there is a flow rate, there is a problem that a false leak alarm or a leak shut-off may occur erroneously.

The present invention has been made in order to solve such problems, and an object of the present invention is to provide a gas cutoff device that can suppress erroneous determinations of leakage detection.

The gas cutoff device according to the present invention includes a flow rate measuring section that is connected to a gas supply pipe and measures the instantaneous flow rate of the gas flow at predetermined intervals, and a flow rate calculation unit that calculates a flow rate value from the instantaneous flow rate measured by the flow rate measuring section. a first determination unit that integrates the flow rate value of the flow rate calculation unit at predetermined intervals and determines whether the accumulated flow rate value is equal to or greater than a predetermined flow rate; a second determination unit that determines whether a period in which the flow rate is less than a predetermined value is longer than or equal to a predetermined time period; and a flow rate determination unit that determines whether or not there is a flow rate based on the determination results of the first determination unit and the second determination unit. a determination unit; and a leakage determination unit that determines the presence or absence of a leak based on the determination result of the flow rate determination unit, and the flow rate determination unit determines, in the second determination unit, the integrated flow rate value of the first determination unit. The number of times that the period in which the flow rate is less than the predetermined flow rate is determined to be longer than the predetermined period is counted, and if the count value is greater than or equal to the predetermined value, it is determined that there is no flow rate, and otherwise, there is a flow rate. It is determined that

As a result, even though no gas is actually used, the gas in the piping moves upstream or downstream and returns due to pressure fluctuations caused by pulsations, and the flow rate is measured at predetermined intervals. Even if there is a positive or negative variation in the instantaneous flow rate measured by the flow rate measurement unit, the instantaneous flow rate (L/h) measured by the flow rate measurement unit is converted into a flow rate value (L) by the flow rate calculation unit, and the flow rate value is calculated. By integrating the amount into the integration buffer in the first determination section, it becomes possible to grasp the volume of gas that actually moved in the pipe, and it becomes possible to more accurately determine whether there is no flow rate. Since the presence or absence of leakage is determined based on the determination result that there is no flow rate, it is possible to prevent false alarms of leakage or false shutoffs.

By using the gas shutoff device of the present invention, gas in the piping moves upstream or downstream due to pressure fluctuations due to pulsation even though no gas is actually used. However, it becomes possible to grasp the volume of gas that actually moved inside the pipe, and it becomes possible to more accurately determine whether there is no flow. Since the presence or absence of leakage is determined based on the determination result that there is no flow rate, it is possible to prevent false alarms of leakage or false shutoffs.

1 is a block diagram of a gas meter in Embodiment 1 of the present invention. FIG. FIG. 3 is a diagram showing an operation procedure for determining the presence or absence of a flow rate in Embodiment 1 of the present invention. It is a block diagram of the gas meter in Embodiment 2 of this invention. FIG. 7 is a diagram showing an operation procedure for determining the presence or absence of a flow rate in Embodiment 2 of the present invention.

A first invention includes: a flow rate measuring section connected to a gas supply pipe and measuring instantaneous gas flow rate at predetermined intervals; and a flow rate calculation section calculating a flow rate value from the instantaneous flow rate measured by the flow rate measuring section; a first determination unit that integrates the flow rate value of the flow rate calculation unit at predetermined intervals and determines whether the accumulated flow rate value is a predetermined flow rate abnormality; a second determination unit that determines whether a period in which the state continues is equal to or longer than a predetermined period; and a flow rate presence/absence determination unit that determines the presence or absence of a flow rate based on the determination results of the first determination unit and the second determination unit. , a leakage determination unit that determines the presence or absence of a leak based on the determination result of the flow rate determination unit, and the flow rate determination unit is configured such that the integrated flow rate value of the first determination unit is equal to or less than the predetermined value in the second determination unit. The number of times that the continuous period of less than the flow rate is determined to be equal to or longer than the predetermined period is counted, and if the count value is equal to or greater than the predetermined value, it is determined that there is no flow rate, otherwise it is determined that there is a flow rate. It is something.

As a result, even though there is no actual flow rate, the gas in the pipe moves upstream or downstream and returns due to pressure fluctuations due to pulsations, and the flow rate measurement unit detects the flow rate at predetermined intervals. Even if there is a positive or negative variation in the measured instantaneous flow rate, the instantaneous flow rate (L/h) measured by the flow rate measurement unit is converted into a flow rate value (L) by the flow rate calculation unit, and that flow rate value is By integrating the gas in the integration buffer in one determination section, it becomes possible to grasp the volume of gas that actually moved in the pipe, and it becomes possible to more accurately determine whether there is a flow rate. Since the presence or absence of leakage is determined based on the determination result that there is no flow rate, it is possible to prevent false alarms of leakage or false shutoffs.

A second invention according to the first invention includes at least one flow rate presence/absence determination unit that determines the presence or absence of a flow rate using a determination method different from the flow rate determination unit, separately from the flow rate presence/absence determination unit; The leak determination unit determines the presence or absence of a leak using one or more determination results determined by the plurality of flow rate determination units, and determines the presence or absence of a leak by using the determination results of the plurality of flow rate determination units. By doing so, leakage determination can be optimized depending on the installation situation.

A third aspect of the present invention is based on the second aspect, wherein the leak determination section is a determination method selection section that sets execution of the determinations of the plurality of flow rate determination sections to be switched under a predetermined condition or to be performed in parallel. With this, it is possible to switch multiple flow rate determination units under predetermined conditions or set them to process in parallel, allowing the market to select a determination method according to the environment and situation. Become.

Hereinafter, embodiments will be described in detail with reference to the drawings. However, detailed explanation may be omitted. For example, detailed explanations of well-known matters or redundant explanations of substantially the same configurations may be omitted. This is to avoid making the following description unnecessarily redundant and to facilitate understanding by those skilled in the art.

The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter recited in the claims.

(Embodiment 1)
FIG. 1 shows a block diagram of a gas meter in Embodiment 1 of the present invention.
In FIG. 1, a gas meter 1 is installed in a gas supply pipe a, and one or more gas appliances installed in each user's home are connected to the downstream pipe (not shown). The gas meter 1 also includes a flow rate measurement section 2, a flow rate calculation section 3, a first determination section 4, a second determination section 5, a flow rate determination section 6, a leakage determination section 7, a control section 8, and an external communication section 9. ing.

The flow rate measurement unit 2 is installed in the gas supply pipe a, and uses ultrasonic signals to determine the propagation time difference caused by the gas flow rate in the gas supply pipe a, and detects the instantaneous flow rate of the gas.
The flow rate calculation section 3 calculates the gas flow rate based on the instantaneous flow rate detected by the flow rate measurement section 2 at regular time intervals. The flow rate measurement section 2 and flow rate calculation section 3 realize the function of flow rate measurement.

The first determination unit 4 integrates the flow rate value calculated by the flow rate calculation unit 3 into an integration buffer, and determines whether the integration buffer is larger or smaller than a predetermined integration determination value.
The second determining unit 5 determines the magnitude of the continuous time during which the cumulative flow value of the cumulative flow value of the cumulative buffer of the first determining unit 4 was less than a predetermined cumulative determination value and a predetermined period (hereinafter referred to as a unit cumulative period). It is something.

The flow rate presence/absence determining unit 6 counts the case where the cumulative flow value in the cumulative buffer of the second determining unit 5 is less than a predetermined cumulative determination value and the continuous time is longer than the unit cumulative period as being satisfied once, and calculates the count. The presence or absence of a flow rate is determined by determining the magnitude of and a predetermined number of times.

The leakage determination unit 7 restarts a leakage determination timer (not shown) when the flow rate determination unit 6 obtains a determination result that there is no flow rate, and restarts the leakage determination timer (not shown) when the determination result that there is a flow rate is obtained. The system measures the time, and when it is determined that the flow rate has continued for a predetermined period of time, the determination that there is a leak is confirmed.

In addition to controlling the operation of each part in the gas meter 1, the control unit 8 performs security processing such as warning and gas cutoff based on the flow rate determination result by the flow rate determination unit 6 and the confirmation of the leak determination by the leakage determination unit 7. It is.

The external communication section 9 changes the settings of the predetermined integration judgment value of the first judgment section 4, the unit integration period of the second judgment section 5, and the predetermined number of times of the flow rate judgment section 6, as well as the leakage judgment by the leakage judgment section 7. When a situation is determined, a warning or shutdown information is sent to the outside.

FIG. 2 is a schematic flowchart of the flow rate determination performed by the gas meter 1 in the first embodiment. The flow rate determination operation performed by the gas meter 1 will be described below with reference to FIGS. 1 and 2.
In FIGS. 1 and 2, the instantaneous flow rate measurement interval of the flow rate measurement unit 2 is assumed to be, for example, 2 seconds. Furthermore, in the following explanation, the counts of the clock timer T1 and the leakage determination timer T2 mean the counts of this measurement interval.

First, the instantaneous flow rate flowing into the gas supply pipe a is measured by the flow rate measuring section 2 (step S1).
Next, the flow rate calculation unit 3 calculates a flow rate value from the instantaneous flow rate measured by the flow rate measurement unit 2 (step S2).

Next, the first determination unit 4 has an integration buffer (not shown) for integrating the flow rate value in a unit integration period (for example, 60 minutes) that is a predetermined period, and the first determination unit 4 The flow rate value is integrated into the integration buffer (step S3), and the magnitude relationship between the integration value of the integration buffer and a predetermined integration determination value (for example, 1.1 L) is determined (step S4).

When the cumulative flow rate value of the cumulative flow rate in the cumulative buffer exceeds the predetermined cumulative determination value (step S4: Yes), the cumulative buffer is cleared to zero (step S41), and the timer T1 for the unit cumulative period is restarted ( Step S42).

Next, when the cumulative flow value of the cumulative flow rate of the cumulative buffer is less than the predetermined cumulative determination value (step S4: No), the second determination unit counts the timer T1 for the unit cumulative period (step S43), and It is determined whether or not the unit integration period timer T1 has passed the unit integration period (step S5).

If the timer T1 for the unit integration period has exceeded the unit integration period (step S5: Yes), the integration buffer is cleared to zero (step S51), and the timer T1 for the unit integration period is restarted (step S51). Step S52).

Next, the flow rate presence/absence determination unit 6 determines that the first determination unit 4 determines that the cumulative flow value of the cumulative buffer is less than the predetermined cumulative determination value (step S4: No), and the second determination unit determines that When it is determined that the unit accumulation period has passed (step S5: Yes), it is counted as one time (step S53), and the magnitude relationship between this count value and a predetermined number of times determination value (for example, 2 times) is compared. (Step S6).

When the count value reaches the predetermined number of times determination value (step S6: Yes), it is determined that there is no flow rate, the count value is cleared to zero (step S61), and the leakage determination timer T2 of the leakage determination section 7 is restarted (step S9).

Then, when the first determination unit 4 determines that the cumulative flow value of the cumulative buffer is equal to or greater than the predetermined cumulative determination value (step S4: Yes), the leakage determining unit 7 determines that the gas is clearly flowing. If it is determined that there is a flow rate, or if the second determination unit 5 determines that the unit integration period is less than the unit integration period (step S5: No), that is, the unit integration period has not been reached, so there is a flow rate. If it cannot be determined that there is no flow rate, or if the flow rate determination unit 6 determines that the count value is less than the predetermined number of times determination value (step S6: No), that is, if it cannot be determined that there is no flow rate, the leakage determination timer T2 is counted (step S62), and it is determined whether the leakage determination timer T2 has elapsed for a predetermined time (for example, 30 days) (step S7).

The leakage determination timer T2 is a timer that measures a period in which it cannot be clearly determined that there is no flow rate, and when the leakage determination timer T2 has elapsed for a predetermined period of time (step S7: Yes), that is, the flow rate determination unit 6 determines that there is no flow rate for the predetermined period of time. If it cannot be determined that there is a leak, the determination that there is a leak is confirmed (step S8). If the predetermined period has not elapsed (step S7: No), the process returns to flow rate measurement (step S1).

Note that the unit integration period of the first determination section 4 and the predetermined number of times of the second determination section 5 may be set to optimal values, and may be set from the outside using the external communication section 9. Good too.

As described above, in the first embodiment, even though there is no actual flow rate, due to pressure fluctuations due to pulsations, the gas in the pipe moves upstream or downstream and returns. , Even if there is a positive or negative variation in the instantaneous flow rate measured by the flow rate measurement unit at predetermined intervals, the instantaneous flow rate (L/h) measured by the flow rate measurement unit is converted into a flow rate value (L) by the flow rate calculation unit. By converting the flow rate into It becomes possible. Since the presence or absence of leakage is determined based on the determination result that there is no flow rate, it is possible to prevent false alarms of leakage or false shutoffs.

(Embodiment 2)
FIG. 3 shows a block diagram of a gas meter in Embodiment 2 of the present invention.
In FIG. 3, the gas meter 1 includes, in addition to the configuration shown in FIG. 1, a first flow rate determination section 10, a second flow rate determination section 11, and a determination method selection section 12.

The first flow rate determination unit 10 includes a first determination unit 4, a second determination unit 5, and a flow rate determination unit 6, and is explained in FIGS. 1 and 2 of the first embodiment. It performs the following actions.
On the other hand, the second flow rate determination unit 11 determines the presence or absence of a flow rate using a method different from that of the first flow rate determination unit 10. It is composed of a flow rate calculation means, a flow rate determination means, a first determination means, a second determination means, and a flow rate determination means (all not shown).
Both the first flow rate determination section 10 and the second flow rate determination section 11 are configured to transmit the flow rate determination result to the leakage determination section 7 .

The determination method selection unit 12 determines which of the first flow rate determination unit 10 and the second flow rate determination unit 11 is used for processing based on predetermined conditions set from the outside by the external communication unit 9. This is to set whether to switch whether to perform the process or to use the first flow rate presence/absence determination section 10 and the second flow rate presence/absence determination section 11 in parallel.

The second flow rate determination unit 11 of this embodiment will be described below with reference to FIG. 3.
In FIG. 3, the second flow rate determination unit 11 first accumulates the instantaneous flow rate measured by the flow rate measurement unit 2 in a first predetermined interval using the interval calculation means to calculate the interval average flow rate, and calculates the interval average flow rate using the moving average flow rate calculation means. A moving average is calculated from N consecutive section average flow rates and held for a second predetermined section.
Next, the corresponding flow rate determination means determines whether the difference between the maximum value and the minimum value of the moving average flow rate in the second predetermined section is less than a threshold value, and the section average flow rate determined to be less than the threshold value is held.

Next, the first determination means determines whether the section average flow rate held by the relevant flow rate determination means is within the first predetermined range, and the second determination means determines whether the flow rate value used to calculate the section average flow rate is determined. It is determined whether the difference between the maximum value and the minimum value of the obtained instantaneous flow rate is within a second predetermined range. When the M section average flow rates are accumulated by the flow rate determination means, the accumulated average flow rate is calculated from the accumulated area average flow rates, and if this accumulated average flow rate is less than the average judgment flow rate. If the flow rate is equal to or higher than the average determination flow rate, it is determined that there is a flow rate.

FIG. 4 is a schematic flowchart of the flow rate determination performed by the gas meter 1 in the second embodiment. The flow rate determination operation performed by the gas meter 1 will be described below with reference to FIGS. 3 and 4.

First, based on predetermined conditions set from the outside by the external communication unit 9, the determination method selection unit 12 determines whether or not to perform the process of the first flow rate determination unit 10 (step S10). If the first flow rate determination unit 10 performs the process (step S10: Yes), the first flow rate determination unit 10 performs a first flow rate determination (step S11).

Next, the result of the flow rate presence/absence in the process of the first flow rate presence/absence determination unit is determined (step S12), and if it is determined that there is no flow rate (step S12: Yes), the leakage determination timer T2 of the leakage determination unit 7 is restarted. (Step S13), and the determination method selection unit 12 determines whether or not to perform the process of the second flow rate determination unit 11 (Step S14).

When performing the process of the second flow rate presence/absence determination section 11 (step S14: Yes), the second flow rate presence/absence determination section 11 performs a second flow rate presence/absence determination (step S15), determines the presence or absence of a flow rate (step S16), If it is determined that there is no flow rate (step S16: Yes), the leak determination timer T2 of the leak determination section 7 is restarted (step S17).

Then, the elapsed time of the leakage determination timer of the leakage determination unit 7 is determined (step S18), and when a predetermined time (for example, 30 days) has elapsed, the determination that there is a leakage is confirmed (step S19). Note that if YES in step S10 and NO in step S14, the flow rate determination unit 10 alone determines the flow rate, and if NO in step S10 and YES in step S14, the second flow rate determination unit 11 alone determines the flow rate. A flow rate determination is performed, and if YES in both step S10 and step S14, a flow rate determination is performed using both the first flow rate determination unit 10 and the second flow rate determination unit 11.

As described above, in the second embodiment, since two flow rate determination sections are provided, which are the first flow rate determination section 10 and the second flow rate determination section 11, these two flow rate determination methods are Switching depending on the conditions or processing in parallel, if it is determined that there is no flow rate in either one, the leak determination timer T2 of the leak determination section 7 is restarted, and the first flow rate determination section 10 and the second flow rate determination section 10 restart the leak determination timer T2 of the leak determination section 7. When the determination unit 11 determines that both flow rates are present, the leakage determination timer T2 of the leakage determination unit 7 continues counting, and when the leakage determination timer T2 elapses for a predetermined period of time, leakage can be detected more accurately. This makes it possible to prevent false alarms and shutdowns of leaks. Furthermore, since the determination methods can be switched or set in parallel, it becomes possible to select a determination method according to the environment and situation in the market.

For example, in an environment where pulsation is likely to occur, large variations in instantaneous flow rate occur, so in the process of the second flow rate determination unit 11, the difference between the maximum value and the minimum value of instantaneous flow rate is likely to be outside the predetermined range, and it is determined that there is no flow rate. Therefore, by setting the determination method selection unit 12 to process the first flow rate determination unit 10, variations in positive and negative instantaneous flow rates can be converted into flow values. It becomes possible to convert and integrate, and by integrating, it becomes possible to offset positive and negative variations, and it becomes possible to more accurately determine that there is no flow rate, and prevent false alarms of leakage or false shutoffs.

In addition, in a breathing phenomenon where a gas flow occurs over a long period of time, processing by the second flow rate determination unit 11 that can monitor a stable flow rate for a long time is more advantageous. By selecting , it becomes possible to more accurately determine whether there is a flow rate or not.

Furthermore, when the first flow rate determination unit 10 and the second flow rate determination unit 11 are executed in parallel, even if one of the determination units erroneously determines that there is a flow rate, the other determination will determine that there is no flow rate. By doing so, the leakage determination timer is restarted, leakage can be detected more accurately, and false alarms and shutdowns of leakage can be prevented.

Although this embodiment has been described using two flow rate determination units, the first flow rate determination unit 10 and the second flow rate determination unit 11, other flow rate determination units that differ from these two determination methods may be added. The determination method selection section 12 may be configured to select or combine these plurality of flow rate presence/absence determination sections.

As described above, the gas cutoff device according to the present invention is capable of determining leakage even in an environment where pulsation or breathing motion is occurring. It includes flammable gases, non-flammable gases, etc., and can also be applied to methods for detecting water and gas leaks.

1 Gas meter 2 Flow rate measurement unit 3 Flow rate calculation unit 4 First determination unit 5 Second determination unit 6 Flow rate determination unit 7 Leakage determination unit 8 Control unit 9 External communication unit 10 First flow rate determination unit 11 Second flow rate determination unit 12 Judgment method selection section

Claims (3)

a flow rate measuring unit connected to the gas supply pipe and measuring instantaneous gas flow rate at predetermined intervals;
a flow rate calculation unit that calculates a flow rate value from the instantaneous flow rate measured by the flow rate measurement unit;
a first determination unit that integrates the flow rate value of the flow rate calculation unit at predetermined intervals and determines whether the integrated flow rate value is equal to or greater than a predetermined flow rate;
a second determination unit that determines whether a continuous period in which the integrated flow rate value of the first determination unit is less than a predetermined flow rate is equal to or longer than a predetermined period;
a flow rate presence/absence determination unit that determines the presence or absence of a flow rate based on the determination results of the first determination unit and the second determination unit;
a leak determination unit that determines the presence or absence of a leak based on the determination result of the flow rate determination unit;
Equipped with
The flow rate presence/absence determination unit includes:
The second determination unit counts the number of times the cumulative flow rate value of the first determination unit is determined to be less than the predetermined flow rate for a continuous period of time equal to or longer than the predetermined period, and the count value is equal to or greater than the predetermined value. A gas cutoff device characterized in that it determines that there is no flow rate if the case occurs, and determines that there is a flow rate in other cases. Separately from the flow rate presence/absence determination unit, it has at least one flow rate presence/absence determination unit that determines the presence or absence of a flow rate using a determination method different from that of the flow rate presence/absence determination unit;
The gas cutoff device according to claim 1, wherein the leakage determination unit determines whether or not there is a leak using one or more determination results determined by the plurality of flow rate determination units. 3. The leakage determination unit includes a determination method selection unit that sets the execution of the determination by the plurality of flow rate determination units to be switched under a predetermined condition or to be performed in parallel. gas cutoff device.

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