JP2023149979A - 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: A gas cutoff device is configured so that a flow rate integration unit accumulates the flow rate value calculated by a flow rate calculation unit at predetermined intervals from the instantaneous flow rate measured by the flow rate measurement unit. When a flow rate appearance determination unit determines that the integrated flow rate value is greater than or equal to a predetermined flow rate, the flow rate is calculated from the integrated flow rate value accumulated up to the determination by the flow rate calculation unit and the time required up to that point. A spark flow rate registration/appearance determination unit determines whether the calculated flow rate is a registered pilot fire flow rate to determine accurately the flow rate.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 the presence or absence of a leak, it is necessary to reliably determine the presence or absence of a flow rate.

In addition, for 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. A long-term gas flow (hereinafter referred to as a breathing phenomenon) occurs due to pressure fluctuations in the gas piping due to the influence of gas. Therefore, it is considered to determine the presence or absence of a leak by taking these factors into consideration, or to register the pilot flame flow rate in advance when using a gas appliance with a pilot flame, and to compare the registered pilot flame flow rate with the actual flow rate. There is a system that takes into account a comparison with the gas flow rate in the determination of the presence or absence of a flow rate to avoid false detection of gas leakage.

For example, Patent Document 1 discloses that when the section average flow rate (for example, the average flow rate for 2 minutes) calculated from the measured instantaneous flow rate falls within the registered flow rate range (for example, 5.5 L/h to 51.82 L/h) If the difference between the maximum and minimum instantaneous flow rates from which the section average flow rate was calculated is less than a predetermined value (for example, 15 L/h), and the difference between the two consecutive section average flow rates is a predetermined value (for example, 1.5 L/h), /h), the average flow rate of the two section average flow rates is registered as the pilot flame registration flow rate.

If the difference between the measured section average flow rate and the registered pilot flow rate is within a predetermined ratio (for example, 5%) of the registered flow rate or the average judgment flow rate (for example, 1.5 L/h), it is determined that there is no flow rate. At the same time as the determination, a leakage determination timer is initialized, and otherwise it is determined that there is a flow rate. If the leakage determination timer continues for a predetermined period of time in a state where there is a flow rate, it is determined that there is a leakage, thereby preventing an erroneous determination of a leakage warning.

Japanese Patent Application Publication No. 2010-216724

However, in Patent Document 1, even if there is no gas leakage in the gas piping and the gas is unused, if large variations occur due to fluctuations in the instantaneous flow rate due to pulsation, the pilot flame flow rate cannot be registered, and the pilot flame flow rate cannot be registered. When using a certain gas appliance, it may be mistakenly determined that there is a leak. Alternatively, even if the pilot flame flow rate can be registered, a flow rate that is not the original pilot flame flow rate may be registered, and when the pulsation subsides, the pilot flame flow rate may be erroneously determined to be present, and a leakage warning may occur.

The present invention was 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 determination 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 flow rate integration unit that integrates the flow rate value of the flow rate calculation unit for a unit integration period; and a flow rate appearance determination unit that determines whether a flow rate has appeared based on the integrated flow rate value integrated by the flow rate integration unit. If it is determined that a flow rate has appeared based on the determination by the flow rate appearance determining unit, the flow rate is determined from the cumulative flow value integrated by the flow rate integrating unit and the time required until the cumulative flow value exceeds a predetermined cumulative determination value. a flow rate calculation unit that calculates the flow rate, and a pilot flame flow rate registration/appearance determination unit that determines that the pilot flame flow rate is registered or the pilot flame flow rate has appeared when the flow rate calculated by the flow rate calculation unit is within a predetermined flow rate range set in advance; , a leakage determination unit that determines whether gas is leaking based on the determination result of the flow rate appearance determination unit and the determination result of the pilot flame flow rate registration/appearance determination unit, and the leakage determination unit is configured to If it is not determined that a pilot flame flow rate has appeared during that period, it is determined that there is a leak.

As a result, even though no gas is actually used, the pulsation causes the gas in the piping to move forward or backward from the upstream side to the downstream side, 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 following can be done. In other words, 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 integrated as an integrated flow rate value by the flow rate integration unit. It becomes possible to grasp the volume of gas that has moved inside. In addition, by using the flow rate calculated based on the integrated flow rate value and the time required for integration, it becomes possible to more accurately register the pilot flame flow rate and determine the appearance of the pilot flame flow rate, and more accurately determine the presence or absence of the flow rate. becomes possible.

By using the gas cutoff device of the present invention, even if gas in the piping moves in the forward or reverse direction from the upstream side to the downstream side due to pulsation even though no gas is actually used, It becomes possible to integrate the volume of gas that actually moved inside the pipe using the flow rate integration unit. The flow rate calculation unit calculates the flow rate based on the integrated flow rate value integrated by the flow rate integration unit and the time required until the integrated flow value integrated by the flow rate appearance determination unit exceeds a predetermined integration determination value, Based on the calculated flow rate, the pilot flame flow rate registration/appearance determination section registers the pilot flame flow rate and determines the appearance. This makes it possible to more accurately determine the pilot flame flow rate registration and appearance, and more accurately determine the presence or absence of the flow rate, thereby making it possible to prevent erroneous determination of leakage.

1 is a block diagram of a gas meter in Embodiment 1 of the present invention. FIG. FIG. 3 is a diagram illustrating an operation procedure for pilot flame flow rate registration and appearance determination 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 appearance of pilot flame 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 flow rate integration unit that integrates the flow rate value of the flow rate calculation unit for a unit integration period; a flow rate occurrence determination unit that determines whether a flow rate has appeared based on the integrated flow rate value integrated by the flow rate integration unit; If it is determined by the appearance determination unit that a flow rate has appeared, the flow rate is calculated from the integrated flow rate value integrated by the flow rate integration unit and the time required until the integrated flow value exceeds a predetermined integration determination value. a calculation unit; a pilot flame flow rate registration/appearance determination unit that determines that a pilot flame flow rate has been registered or a pilot flame flow rate has appeared when the flow rate calculated by the flow rate calculation unit is within a predetermined flow rate range; a leakage determination section that determines whether gas is leaking based on the determination result of the determination section and the determination result of the pilot flame flow rate registration/appearance determination section; If it is not determined that there is no leakage, it is determined that there is a leakage.

As a result, even if the gas in the piping moves in the forward or reverse direction from the upstream side to the downstream side due to pulsation even though no gas is actually used, the gas that actually moved inside the piping It becomes possible to integrate the volume amount of the flow rate in the flow rate integrating section. In addition, the flow rate calculation unit calculates the flow rate based on the time required for the buffer value accumulated by the flow rate appearance determination unit to exceed a predetermined accumulation determination value, and the pilot flame flow rate registration/appearance determination unit calculates the flow rate based on the calculated flow rate. Register the pilot flame flow rate and judge the appearance. This makes it possible to more accurately register the pilot flame flow rate and to determine the appearance of the pilot flame flow rate, to more accurately determine the presence or absence of a flow rate, and to prevent erroneous determination of leakage.

A second invention according to the first invention includes a flow rate output section having the flow rate calculation section and at least one flow rate output section having a flow rate calculation section that calculates the flow rate using a method different from that of the flow rate calculation section. The pilot flame flow rate registration/appearance determination unit is characterized in that it determines the registration of the pilot flame flow rate or the appearance of the pilot flame flow rate based on the flow rates obtained by the plurality of flow rate output units. This makes it possible to optimize the flow rate determination depending on the installation situation.

A third aspect of the present invention is the second aspect of the present invention, further comprising a determination method selection unit that sets execution of flow rate calculation by the plurality of flow rate output units to be switched under predetermined conditions or to be performed in parallel. shall be. This makes it possible to determine the appearance of multiple flow rates, switch the flow rate calculation method based on predetermined conditions, or set it to be processed in parallel, making it possible to select a determination method that suits the environment and situation in the market. becomes.

Hereinafter, embodiments will be described in detail using a gas meter as a specific example of a gas cutoff device with reference to the drawings. However, more detailed explanation than necessary 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 flow rate integration section 4, a flow rate appearance determination section 5, a flow rate calculation section 6, a pilot flame flow rate registration/appearance determination section 7, a leakage determination section 8, a control section 9, It is composed of an external communication section 10.

The flow rate measurement unit 2 is installed in the gas supply pipe a, 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 based on the propagation time difference. .

The flow rate calculation unit 3 calculates a gas flow rate value based on the instantaneous flow rate detected by the flow rate measurement unit 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 flow rate integration unit 4 integrates the flow rate value calculated by the flow rate calculation unit 3 into an integration buffer (not shown) that the flow rate integration unit 4 has to obtain an integrated flow rate value.

The flow rate appearance determination unit 5 determines whether the cumulative flow rate value integrated by the flow rate integration unit 4 is equal to or greater than a predetermined integration determination value, measures the time accumulated in the integration buffer, and calculates the unit of the accumulated time. It is determined whether a flow rate has appeared by determining whether or not the integration period has elapsed.

When the flow rate appearance determination unit 5 determines that a flow rate has appeared, the flow rate calculation unit 6 calculates the time required for the cumulative flow value of the flow rate integration unit 4 to exceed a predetermined cumulative determination value and the cumulative flow rate up to that point. The flow rate is calculated from the value.

The pilot flame flow rate registration/appearance determining unit 7 determines whether the flow rate that has appeared is the pilot flame registered flow rate by determining whether the flow rate calculated by the flow rate calculation unit 6 is within the pilot flame registered flow rate range. . Furthermore, based on this determination result, the presence or absence of a flow rate used by the leak determination section 8 is also determined.

The leak determination unit 8 determines that there is a leak if it is not determined that there is no flow rate within a predetermined period of time. Specifically, when the pilot flame flow rate registration/appearance determination section 7 determines that the flow rate calculated by the flow rate calculation section 6 is within a predetermined registered pilot flame flow rate range, the leakage determination section 8 performs the following process. That is, the leakage determination unit 8 determines that the integrated flow rate value obtained by the flow rate integration unit 4 is due to the pilot flow rate, and the leakage determination unit 8 determines whether or not there is a flow rate by assuming that there is no flow rate. Restart the leakage judgment timer. On the other hand, if it is determined that the flow rate calculated by the flow rate calculation unit 6 is not within the predetermined registered pilot flame flow rate range, the leakage determination unit 8 performs the following process. That is, the leakage determination unit 8 counts the leakage determination timer, assuming that there is a flow rate, and determines whether or not the predetermined time has elapsed as measured by the leakage determination timer. By doing this, it is possible to determine whether or not there is a leak. In this case, the leakage determination unit 8 determines that there is a leakage when the predetermined time period measured by the leakage determination timer has elapsed.

In addition to controlling the operation of each part in the gas meter 1, the control unit 9 issues a warning or shuts off the gas based on the determination result of the pilot flame flow rate by the pilot flame flow rate registration/appearance determination unit 7 and the confirmation of the leakage determination by the leakage determination unit 8. It performs security processing such as

The external communication unit 10 not only changes the settings of a predetermined integration judgment value and unit integration period in the flow rate appearance judgment unit 5, but also notifies the outside of a warning or cutoff information when a leakage judgment by the leakage judgment unit 8 is confirmed. It is.

FIG. 2 is a schematic flowchart of an operation procedure for determining the appearance of a pilot flame flow rate, which is performed by the gas meter 1 in the first embodiment. The pilot flame flow rate appearance 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. In addition, in the following explanation, a clock timer T1 (not shown) measures a unit integration period (for example, 60 minutes), and a leakage determination timer T2 (not shown) measures a predetermined period of time (for example, 30 days). It is used to measure time.

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 flow rate integration unit 4 has the above-mentioned integration buffer for integrating the flow rate value in a unit integration period (for example, 60 minutes) which is a predetermined period, and uses the flow rate value from the flow rate calculation unit 3 as described above. A cumulative flow value is obtained by integrating the flow rate in the cumulative buffer (step S3).

Next, the flow rate appearance determination unit 5 determines whether the cumulative flow value of the cumulative flow buffer is equal to or greater than a predetermined cumulative determination value (for example, 1.1 L) (step S4).

If the cumulative flow rate value of the cumulative flow rate value of the cumulative flow rate is less than the predetermined cumulative determination value (step S4: No), it is determined that no flow rate has appeared, and a timer T1 for unit cumulative period is counted (not shown); It is determined whether or not the unit integration period has elapsed as measured by the timer T1 (step S5). If the time measurement by the timer T1 has not passed the unit integration period (step S5: No), the timer T1 continues counting for the unit integration period (not shown), and returns to instantaneous flow rate measurement (step S1). . On the other hand, if the time measurement by the timer T1 has exceeded the unit integration period (step S5: Yes), the process proceeds to step S8, which will be described later.

Next, when the cumulative flow value of the cumulative buffer becomes equal to or higher than the predetermined cumulative determination value (step S4: Yes), the flow rate calculation unit 6 determines that a flow rate has appeared, and sets the cumulative flow value and the clock timer T1. The flow rate Qt is calculated from the elapsed time (step S6).

Next, the pilot flame flow rate registration/appearance determining unit 7 determines whether the flow rate Qt is within a predetermined registered pilot flame flow rate range (step S7). If the flow rate Qt is within the predetermined registered pilot flame flow rate range (step S7: Yes), the flow rate Qt is determined to be the registered pilot flame flow rate, and if the flow rate Qt is not within the predetermined registered pilot flame flow rate range (step S7: No) , it is determined that the flow rate Qt is not the registered pilot flame flow rate.

Then, if the time during which the cumulative flow value is less than a predetermined cumulative determination value in the flow rate appearance determining unit 5 has passed for a unit integration period (step S5: Yes), or the leak determining unit 8 determines whether the flow rate appearance determining unit 5 If it is determined that the flow rate Qt is the registered pilot flame flow rate (step S7: Yes), it is assumed that there is no flow rate, and the leakage determination timer T2 is restarted (step S8).

On the other hand, if the leak determination unit 8 determines that the flow rate Qt is not the registered pilot flame flow rate (step S7: No), it assumes that there is a flow rate and continues counting the leak determination timer T2 (not shown). , the leakage determination timer T2 determines whether a predetermined time (for example, 30 days) has elapsed (step S9).

If the predetermined time has not elapsed as measured by the leakage determination timer T2 (step S9: No), the process returns to instantaneous flow rate measurement (step S1). On the other hand, if the predetermined time period has elapsed as measured by the leakage determination timer T2 (step S9: Yes), the leakage determination unit 8 determines that there is a leakage (step S10).

Note that the unit integration period of the flow rate integration section 4 may be set to an optimal value here, or may be set from the outside using the external communication section 8.

As described above, in the first embodiment, gas in the pipe moves from the upstream side to the downstream side due to pulsation, either in the forward direction or in the reverse direction, even though no gas is actually used. Even if there is a positive or negative variation in the instantaneous flow rate measured by the flow rate measurement unit 2 at predetermined time intervals, the following can be done. That is, by converting the instantaneous flow rate (L/h) measured by the flow rate measurement unit 2 into a flow rate value (L) by the flow rate calculation unit 3, and integrating the flow rate value as an integrated flow rate value by the flow rate integration unit 4, It becomes possible to grasp the volume of gas that actually moved inside the pipe. Further, by using the flow rate based on the integrated flow rate value and the time required for the integration by the flow rate calculation unit 6 in the pilot flame flow rate registration/appearance determination unit 7, it is possible to more accurately determine the pilot flame flow rate registration and appearance. Therefore, the presence or absence of a flow rate can be determined more accurately, and erroneous determination of leakage can be prevented.

(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 further includes a first flow rate output section 11, a second flow rate output section 12, and a determination method selection section 13 in addition to the configuration shown in FIG. 1 described above.

The first flow rate output unit 11 includes a flow rate integration unit 4, a flow rate appearance determination unit 5, and a flow rate calculation unit 6, and operates as described in FIGS. 1 and 2 of the first embodiment. It is something to do.

On the other hand, the second flow rate output section 12 determines the appearance of the flow rate and calculates the flow rate using a method different from that of the first flow rate output section 11. Specifically, the second flow rate output section 12 includes, for example, as described in Patent Document 1, a section calculation means, a moving average flow rate calculation means, a flow rate determination means, a first determination means, a second determination means, a flow rate It is composed of presence/absence determining means (none of which are shown).

The first flow rate output section 11 and the second flow rate output section 12 are configured to transmit the flow rate when it is determined that the flow rate has appeared to the pilot flame flow rate registration/appearance determination section 7.

The determination method selection unit 13 causes processing to be performed using either the first flow rate output unit 11 or the second flow rate output unit 12 based on predetermined conditions set from the outside by the external communication unit 10. This is to set whether to switch between the two or to use the first flow rate output section 11 and the second flow rate output section 12 in parallel for processing. Note that the predetermined conditions are defined, for example, by quantifying the likelihood of pulsation occurring in the installation environment of the gas meter 1 for each gas meter 1, and comparing the numerical value with a threshold value.

Hereinafter, the processing in the second flow rate output section 12 of this embodiment will be explained using FIG. 4.

In FIG. 4, the second flow rate output section 12 first accumulates the instantaneous flow rate measured by the flow rate measurement section 2 in a first predetermined section using the section calculation means to calculate the section average flow rate, and then calculates the section average flow rate. A moving average is calculated from N consecutive section average flow rates and is held for a second predetermined section.

Next, the corresponding flow rate determining 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 holds the section average flow rate determined to be less than the threshold value.

Next, the first determination means determines whether the section average flow rate held by the relevant flow rate determination means is within a first predetermined range. The second determining means determines whether the difference between the maximum value and the minimum value of the instantaneous flow rate obtained from the flow rate used to calculate the section average flow rate is within a second predetermined range. When the section average flow rate that is determined to be within the first predetermined range by the first determination means and within the second predetermined range by the second determination means is accumulated, and the M section average flow rates are accumulated by the flow rate presence/absence determination means, Calculate the accumulated average flow rate from the accumulated section average flow rate. The flow rate determination means determines that there is no flow rate when the accumulated average flow rate is less than the average determined flow rate, and determines that a flow rate has appeared when it is greater than or equal to the average determined flow rate.

FIG. 4 is a schematic flowchart of an operation procedure for determining the appearance of a pilot flame flow rate, which is performed by the gas meter 1 in the second embodiment. The pilot flame flow rate appearance 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 10, the determination method selection unit 13 determines whether or not to perform the processing of the first flow rate output unit 11 (step S11). When performing the process of the first flow rate output section 11 (step S11: Yes), the first flow rate output process is performed in the first flow rate output section 11 (step S12). On the other hand, if the process of the first flow rate output section 11 is not performed (step S11: No), the process proceeds to step S15, which will be described later.

Next, based on the result of the processing by the first flow rate output unit 11, the pilot flame flow rate registration/appearance determination unit 7 determines whether the flow rate is the registered pilot flame flow rate or not, thereby determining the presence or absence of the flow rate (step S13). If it is determined that there is no flow rate (step S13: Yes), the leak determination timer T2 of the leak determination unit 8 is restarted (step S14), and the determination method selection unit 13 determines whether or not to perform the process of the second flow rate output unit 12. A determination is made (step S15). On the other hand, if it is not determined that there is no flow rate (step S13: No), the process proceeds to step S15.

When performing the process of the second flow rate output unit 12 (step S15: Yes), the second flow rate output process is performed in the second flow rate output unit 12 (step S16), and from the result of the process of the second flow rate output unit 12, The presence or absence of a flow rate is determined by determining whether the flow rate is the registered pilot flame flow rate in the flow rate registration/appearance determination unit 7 (step S17). If it is determined that there is no flow rate (step S17: Yes), the leakage determination timer T2 of the leakage determination unit 8 is restarted (step S18). On the other hand, if the process of the second flow rate output section 12 is not performed (step S15: No), and if it is determined that there is no flow rate (step S17: No), the process proceeds to step S19 described later.

Then, the elapsed time of the leakage determination timer of the leakage determination unit 8 is determined (step S19), and when a predetermined time (for example, 30 days) has elapsed, the determination that there is a leakage is confirmed (step S20).

As described above, in the second embodiment, two flow rate output sections, the first flow rate output section 11 and the second flow rate output section 12, are provided. As a result, if the appearance determination of these two flow rates and the flow rate calculation method are switched under predetermined conditions or are processed in parallel, and it is determined that there is no flow rate in either one, the leak determination timer of the leak determination unit 8 is activated. Restart T2. Furthermore, when both the first flow rate output section 11 and the second flow rate output section 12 determine that there is a flow rate, the leak determination timer T2 of the leak determination section 8 continues counting, and the leak determination timer T2 elapses for a predetermined period of time. By doing so, leakage can be detected more accurately, and false alarms of leakage or false shutoffs can be prevented. 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, there will be large variations in instantaneous flow rate, so in the processing of the second flow rate output section 12, the difference between the maximum and minimum values of instantaneous flow rate will likely be outside the predetermined range, and it will be determined that there is no flow rate. Otherwise, there is a possibility that it will be erroneously determined that there is a flow rate, or that it may not be possible to accurately determine whether or not the calculated flow rate is within the pilot flow rate range. Therefore, by setting the first flow rate output unit 11 to be processed by the determination method selection unit 12, it becomes possible to convert the variation in positive and negative instantaneous flow rates into a flow rate value and integrate it. By integrating in this way, it is possible to cancel out positive or negative variations, and it is possible to more accurately determine the appearance of the flow rate and whether or not it is the pilot flow rate, thereby preventing false leakage alarms or false shutoffs. It becomes possible to prevent it.

In addition, in the case of a breathing phenomenon in which a gas flow occurs for a long period of time, the second flow rate output section 12 is selected because processing by the second flow rate output section 12, which can monitor a stable flow rate for a long period of time, is superior. By doing so, it becomes possible to more accurately determine the presence or absence of a flow rate and whether or not the flow rate is a pilot flame flow.

Furthermore, when the first flow rate output section 11 and the second flow rate output section 12 are executed in parallel, if either one of them is incorrectly determined to have a flow rate, or the flow rate that is determined to be a flow rate is within the registered pilot flow rate range. Even if it is determined that the flow rate is outside, the other determination determines that there is no flow rate or that the flow rate is within the registered pilot flame flow rate range. As a result, the leakage determination timer is restarted, leakage can be detected more accurately, and false leakage alarms or false shutoffs can be prevented.

Although the present embodiment has been described using two flow rate output units, the first flow rate output unit 11 and the second flow rate output unit 12, other flow rate output units that differ from these two determination methods are added, and the determination method is The selection unit 13 may be configured to select or combine these plurality of flow rate output units.

As described above, the gas cutoff device according to the present invention is capable of determining the appearance of a flow rate and determining whether or not it is a pilot flow rate even in an environment where pulsation occurs. The object of the invention is not limited to this, but also includes other flammable gases, non-flammable gases, etc., and can also be applied to systems for detecting leaks of water or gas.

1 Gas meter 2 Flow rate measurement unit 3 Flow rate calculation unit 4 Flow rate integration unit 5 Flow rate appearance determination unit 6 Flow rate calculation unit 7 Spark flow rate registration/appearance determination unit 8 Leakage determination unit 9 Control unit 10 External communication unit 11 First flow rate output unit 12 Two flow rate output section 13 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 flow rate integration unit that integrates the flow rate value of the flow rate calculation unit for a unit integration period;
a flow rate appearance determination unit that determines whether a flow rate has appeared based on the integrated flow rate value integrated by the flow rate integration unit;
When it is determined that a flow rate has appeared in the judgment of the flow rate appearance determination unit, the flow rate is calculated from the cumulative flow value integrated by the flow rate integration unit and the time required until the cumulative flow value exceeds a predetermined cumulative determination value. a flow rate calculation unit that calculates;
a pilot flame flow rate registration/appearance determination unit that determines that the pilot flame flow rate is registered or the pilot flame flow rate has appeared when the flow rate calculated by the flow rate calculation unit is within a predetermined flow rate range set in advance;
a leakage determination unit that determines whether gas is leaking from the determination result of the flow rate appearance determination unit and the determination result of the pilot flame flow rate registration/appearance determination unit;
The gas cutoff device is characterized in that the leakage determining unit determines that there is a leak if it is not determined that a pilot flame flow rate has appeared within a predetermined period of time. a flow rate output unit having the flow rate calculation unit; and at least one flow rate output unit having a flow rate calculation unit that calculates the flow rate using a method different from that of the flow rate calculation unit;
1 . The pilot flame flow rate registration/appearance determination unit determines whether the pilot flame flow rate is registered or the pilot flame flow rate has appeared based on the flow rates obtained by the flow rate output unit and the at least one flow output unit. The gas cutoff device described in . 3. The gas cutoff device according to claim 2, further comprising a determination method selection section that sets execution of flow rate calculations by the plurality of flow rate output sections to be switched under predetermined conditions or to be performed in parallel.

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