JP4956392B2 - Gas leak detection system - Google Patents

Description

  The present invention relates to a gas leak detection system suitable for gas leak detection in a fuel gas supply system for various gas combustion devices, and more particularly to a gas leak detection system suitable for improving the function of a gas meter for measuring gas consumption.

  Conventionally, as a gas appliance discriminating device that can be used for gas leak detection, when a change occurs in the gas flow rate, the flow rate of each individual gas appliance is obtained based on the change flow rate, and the gas pressure is actively changed. Based on the change in the gas flow rate at the time, the ratio of the gas flow rate supplied to the gas appliance equipped with the gas governor (an example of the control means) out of the total gas flow rate is obtained, and based on the ratio and the total gas flow rate Obtain the gas flow rate supplied to the gas appliance equipped with the gas governor and the gas flow rate supplied to the gas appliance not equipped with the gas governor. By comparing the flow rate of the unit, it is possible to determine the presence or absence of gas governor equipment of the gas appliance being used, and to determine the type of gas appliance being used based on the determination result. It has been proposed (see paragraph patent document 1 [0009]).

  And as a gas safety shut-off device using this gas appliance discriminating device, if all the gas appliances used are gas appliances having a gas governor, it is clearly determined that there is no risk of gas leakage. Even if a minute flow rate is detected for a long time, if only a gas appliance having a gas governor (for example, a fan heater) is used, the gas is not shut off, and if an appliance having no gas governor is used, a gas leak will occur. It has been proposed that the gas is shut off by judging (see paragraph [0049] of Patent Document 1).

JP 7-151580 A

However, in the above configuration, both the case where an instrument that does not have a gas governor is used and the case where a gas leak truly occurs are judged to be gas leaks. Even when there is no need, there is a problem because the gas is shut off.
The reason why such a problem occurs is that the flow rate change caused by the application of pressure change does not change between when a device that does not have a gas governor is used and when there is a true gas leak, This is due to the fact that both cannot be identified.

  A main object of the present invention is to provide a gas leak detection system that can accurately perform a gas shut-off in a situation where a gas leak truly occurs.

In order to achieve the above object, a gas leakage detection system having the first characteristic configuration of the present application is as follows:
In a gas supply path in which one or a plurality of gas devices are connected to the downstream side, pressure change applying means for applying a pressure change to a gas flow in a steady flow rate flowing through the gas supply path;
A flow rate change detecting means for detecting a change in gas flow rate caused by a pressure change applied by the pressure change applying means;
A non-control flow rate determination means for determining the presence of a non-control flow rate other than the supply flow rate to the gas equipment in which the control means for reducing the pressure change is incorporated by the change in the gas flow rate detected by the flow rate change detection means,
Communication information generated from gas equipment that detects use communication information generated by the use of gas from uncontrolled gas equipment from non-controlled gas equipment that does not incorporate control means to reduce pressure changes Use communication information detecting means
Based on the non-control flow rate existence determination result by the non-control flow rate determination means and the use communication information detection result by the use communication information detection means,
When the use communication information is detected in a situation where it is determined that the uncontrolled flow rate exists, it is determined that the uncontrolled flow rate is not a leakage flow rate, and in a situation where it is determined that the uncontrolled flow rate exists, When the use communication information is not detected, it is determined that there is a high possibility that the uncontrolled flow rate is a leakage flow rate, and a system for detecting leakage on the downstream side is used.
In this gas leak detection system,
In the gas supply path in which one or more gas devices are connected to the downstream side, a pressure change is applied to the gas flow in a steady flow rate that flows through the gas supply path,
By examining the change in the gas flow rate caused by the application of this pressure change, it is possible to determine the presence of an uncontrolled flow rate other than the supply flow rate to the gas equipment incorporating the control means for reducing the pressure change,
Communication information generated from gas equipment that detects use communication information generated by the use of gas from uncontrolled gas equipment from non-controlled gas equipment that does not incorporate control means to reduce pressure changes And
Based on the result of determining the presence of the uncontrolled flow rate and the detection result of the used communication information, leakage on the downstream side is detected.
Here, the use communication information is gas use communication information that is continuously transmitted while the gas device is using gas, or gas use communication information that is transmitted only when use is started and when use is stopped.

  A supply flow rate (hereinafter sometimes abbreviated as a control flow rate) to a gas appliance incorporating a control means (for example, an automatic flow rate adjustment means such as a gas governor or a PID control type) for reducing the pressure change is provided in the gas supply path. In the state of occupying the total gas flow rate, the control means acts on all of the supply gas. Therefore, within the control range of a pressure control device such as a gas governor as the control means, the gas flow rate is controlled by applying the pressure change. Even if it is changed, the gas flow rate may remain a slight offset, but it returns to the flow rate before applying the pressure change through a temporary transient change immediately after applying the pressure change (see FIG. 9).

  On the other hand, there is no gas supply (control flow rate) to the gas equipment incorporating the control means for reducing the pressure change, and the supply flow rate to the gas equipment not incorporating the control means for reducing the pressure change or due to gas leakage In the state where any one of the generated flow rates or the total gas flow rate thereof (hereinafter sometimes referred to as uncontrolled flow rate) occupies the total gas flow rate of the gas supply path, there is no action of the control means. Therefore, even after the pressure change is applied, the gas flow rate does not return to the flow rate before the pressure change is applied.If the gas flow rate is changed by applying the pressure change, the flow rate change corresponding to the applied pressure change is based on the pressure. Unless it returns, it will remain continuously (see FIG. 10).

In this case, the relationship between the total gas flow rate Q0 and the pressure P0 before the pressure change is applied and the total gas flow rate Q1 and the pressure P1 after the pressure change is applied is expressed by the following (formula 1). It has been known.
Q1 / Q0 = √ (P1 / P0) (Equation 1)

  Further, in the state where the control flow rate and the non-control flow rate are mixed and the total flow rate thereof is the total gas flow rate of the gas supply path, if the gas flow rate is changed by applying the pressure change (this change is Within the control range in which the change can be absorbed by the above control means), the part of the change in flow rate that occurs with respect to the control flow rate disappears through the transient change immediately after the pressure change is applied by the action of the control means, and the other uncontrolled flow rate Unless the pressure is returned to the original state, the changed part is continuously left (see FIG. 11).

  In this case, the total gas flow rate Q0, the control flow rate Q0 ′, the non-control flow rate Q0 ″, the pressure P0, and the total gas flow rate Q1, the control flow rate Q1 ′, the non-control flow rate Q1 ″, the pressure after the pressure change are applied. The relationship of P1 is represented by the following (Expression 2) to (Expression 5).

Q1 ″ / Q0 ″ = √ (P1 / P0) (Equation 2)
Q0 = Q0 ′ + Q0 ″ (Equation 3)
Q1 = Q1 ′ + Q1 ″ (Formula 4)
Q0 '= Q1' (Equation 5)

  (Equation 2) shows the relationship between the uncontrolled flow rate and pressure before and after application of pressure change, and (Equation 3) and (Equation 4) show the total gas flow rate and control before and after application of pressure change, respectively. The relationship between the flow rate and the non-control flow rate is shown, and (Equation 5) indicates that the control flow rate after the transient change after the pressure change is applied returns to the control flow rate before the pressure change is applied.

Here, for example, Q0 ′ and Q1 ′ are eliminated by (Expression 3) to (Expression 5) to obtain the following (Expression 6):
Q0−Q0 ″ = Q1−Q1 ″ (Formula 6)

By sequentially modifying the equation so as to eliminate Q1 ″ by (Equation 6) and (Equation 2), the uncontrolled flow rate Q0 ″ can be made unknown (Equation 7).
Q0 ″ = (Q1−Q0 + Q0 ″) / √ (P1 / P0)
Q0 ″ = (Q1−Q0) / √ (P1 / P0) + Q0 ″ / √ (P1 / P0)
Q0 ″ = (Q1-Q0) / (√ (P1 / P0) −1) (Expression 7)

  As is clear from the above, if the relationship between the pressure before and after the pressure change is known and the change in the total gas flow rate caused by the pressure change is examined, the presence or absence of the uncontrolled flow rate Q0 ″ can be accurately determined. In addition, the flow rate value of the uncontrolled flow rate Q0 ″ (or Q1 ″) can be obtained.

  As described above, in the gas leakage detection system according to the present invention, by checking the change in the gas flow rate caused by the pressure change application, the uncontrolled flow rate (the supply flow rate to the gas equipment in which the control means for reducing the pressure change is not incorporated or Determine the flow rate generated by gas leakage). This uncontrolled flow rate can be considered as a leakage flow rate in the sense of a flow rate that may be generated due to gas leakage.

On the other hand, some recent gas appliances are in an operating state in which the gas appliance uses (consumes) gas and generates predetermined use communication information. As such a gas appliance, a so-called stove can be mentioned. In the case of a stove, use communication information is transmitted so that a ventilation fan provided in the range hood is operated in conjunction with its use. Therefore, in the gas leakage detection technique according to the present application, this use communication information is detected. This is because the uncontrolled flow rate described above may be transmitted from the gas device that is transmitting the use communication information.
Then, it is determined and detected whether there is a leak on the downstream side according to whether or not there is an uncontrolled flow rate and whether or not used communication information is detected. Therefore, in the detection system according to the present application, when the gas equipment that does not include the control means is normally used, it is confirmed from the use communication information side that two requirements (the presence / absence of the uncontrolled flow rate and the control means are provided). The leakage can be detected from the operating state of the gas equipment that has not been performed, and the leakage on the downstream side can be detected with higher reliability than before.

  From these things, according to the 1st characteristic structure of the gas leak detection system concerning the present invention, compared with the gas safety shut-off device of patent documents 1 mentioned above etc., it judges more precisely that there is a possibility of gas leak. Even if there is a possibility of gas leakage, it is not determined over a long period of time, and conversely, there is no risk of gas leakage. It can be effectively prevented that it is determined that there is a possibility of gas leakage. Further, in accordance with the magnitude of the leakage flow rate included in the uncontrolled flow rate, for example, by appropriately selecting a time limit that is a time until gas shut-off, gas leakage detection that is more excellent in terms of safety can be performed.

In the system for detecting gas leakage, it is determined that there is an uncontrolled flow rate, and when used communication information is detected, the uncontrolled flow rate is detected from the gas device that is transmitting the used communication information. As information, it is possible to avoid unnecessary blocking.
On the other hand, if the use communication information is not detected in a situation where it is determined that there is an uncontrolled flow rate, it is likely that the uncontrolled flow rate is the leakage flow rate described above, and true leakage detection is conventionally performed. Can be performed with higher accuracy.

The above gas leak detection system is suitably applied when the uncontrolled gas device is a gas combustion device and the use communication information is transmission information transmitted from the gas combustion device to operate a ventilation facility. it can.
That is, when the gas device is a gas combustion device and use communication information is transmitted from this device to operate the ventilation equipment, the use of the gas combustion device is used in accordance with the operation status of the gas combustion device. Therefore, it is possible to accurately detect whether an uncontrolled flow rate is generated or whether the uncontrolled flow rate is a true leakage flow rate.

Now, in the gas leak detection system described so far,
Use communication information generated from the uncontrolled gas equipment is infrared communication information communicated by infrared rays,
It is preferable that the use communication information is information obtained by intercepting the infrared communication information, converted into wired or wireless telecommunication information, and obtained via a repeater.
When communication is performed between an uncontrolled gas device and other equipment, a communication system using infrared rays is often employed because of merits such as communication costs. And in the gas leak detection system of this structure, the communicable range of the infrared communication information (use communication information) is limited to a relatively narrow range. Therefore, in the gas leakage detection system having this configuration, a repeater is provided, which is converted into wired or wireless telecommunication information via the repeater and sent to the used communication information detecting means. By doing in this way, a system can be satisfactorily constructed even when the position where the used communication information is acquired and the position where the used communication information detecting means is provided are different.
For example, when the used communication information detection means is a functional part of a gas meter (microcomputer gas meter) installed outdoors, communication using infrared rays limited to one-room communication is not possible. Therefore, by intercepting infrared communication by some method, converting it to a communication protocol for a gas meter, and further converting to wireless / wired electrical communication information and transmitting it, it is possible to reliably transmit and detect used communication information.

As a specific configuration in the case of configuring a repeater, the use communication information is preferably information obtained via a wired or wireless telecommunication function provided in the alarm device.
Recently, it is obliged to install fire alarms in places where gas is used. Further, a gas alarm is generally installed at a place where such gas is used. In some cases, a gas / fire alarm with both fire alarm and gas alarm functions is installed. Therefore, in this configuration, the gas leak detection system can be constructed without substantially increasing the number of facilities by providing the alarm device with the role as the repeater described above.
It is possible to adopt a configuration in which such a relay function is provided to an alarm device installed in the same room as the stove, but in this configuration, a recent gas alarm device is already equipped with a shut-off valve as an “alarm device interlocking shut-off”. Have been put into practical use. Therefore, this gas alarm is provided with a function for detecting use communication information, and a function for determining the presence of an uncontrolled flow rate is provided on the gas meter side, and the gas supply path is shut off based on information obtained from both functional parts. A configuration is also possible. In this case, the function of the gas alarm will be expanded. In the case of adopting this configuration, the communication of use communication information can be transmitted using an existing method such as communication at a voltage that does not result in valve shutoff, or communication at a higher speed than when the shutoff valve operates.

Furthermore, as a specific configuration in the case of configuring a repeater, it is preferable that the use communication information is information obtained by communication with a home security system that has received communication from the alarm device. In this configuration, a part of the role as the repeater described above is also assigned to the home security system, so that the gas leak detection system according to the present application can be constructed in a home equipped with the home security system.
In this case, the home security system can be provided with protocol conversion and communication functions. If the gas alarm device described above is battery-powered, it is necessary to reduce power consumption, and furthermore, it is necessary to reduce costs for the spread of alarm devices, so it is always preferable to add functions to gas alarm devices. However, in a home security system that can always be supplied with power from a commercial power supply, functions can be easily added without such problems.

Hereinafter, the gas leakage detection system S according to the present application will be described. FIG. 1 shows a gas leak detection system S according to the present application as a stove-equipped range s1 (hereinafter simply referred to as a range, which is an example of a gas combustion device), which is a gas device provided in the kitchen, and a gas provided in the kitchen. -The structure of the example constructed | assembled between the fire alarm device s2 (an example of a gas alarm device) and the gas meter s3 provided for measuring the gas consumption of the said household is shown.
FIGS. 1 and 3 show the relationship between these three parties s1, s2, and s3, and FIG. 3 shows the configuration of a gas meter s3 with a leak detection function that can perform gas leak detection as described in the present application.

  First, as shown in FIG. 1 and FIG. 2, the area around the range s <b> 1 provided in the home kitchen will be described. The range s <b> 1 as a gas combustion device is configured so that city gas is supplied via a gas supply path 2. Has been. Further, a gas / fire alarm device s2 is provided on the ceiling of the kitchen, and a gas meter s3 for measuring the amount of city gas consumed in the home is provided at the entrance of the home. The gas meter s3 is provided with a unique shut-off valve 5. The above is the general situation of the home where the gas leakage detection system S of the present application is provided.

Range / Range Hood As shown in FIG. 2, the range s1, which is a gas combustion device, includes a plurality of stoves 11 on its top surface and a grill 12 therein. Accordingly, it is possible to boil and receive fish from the gas supply path 2 and to bake fish and the like.
A range hood 13 is provided above the range s1. The range hood 13 is disposed so as to come to the lower end of the exhaust duct 15, and an exhaust fan 16 (an example of a ventilation facility) for exhaust is provided at a predetermined portion of the exhaust duct 15.
The range s1 is provided with a use communication information transmitter 17 that transmits use communication information in the gas use state. On the other hand, the ventilation fan 16 is provided with a receiving unit 18 that receives use communication information transmitted from the range s1, and the ventilation fan 16 automatically operates when the reception unit 18 receives (detects) use communication information. Is configured to do. This communication is configured to be performed by infrared rays, and is configured so that exhaust generated by the use of gas can be automatically discharged to the outdoors.

Gas / fire alarm s2
The gas / fire alarm device s2 as an example of an alarm device has a gas detection function for detecting gas by the gas detection sensor 21 and a fire detection function for detecting the occurrence of a fire by the temperature sensor 22. A power source 23 for the sensors 21 and 22 and an alarm output unit 26c that outputs an alarm according to the output from the sensors 21 and 22 are provided in common. The gas / fire alarm device s2 includes an alarm device body 25 including the gas detection sensor 21, the power source 23, and the alarm output unit 26c, and is separate from the alarm device body 25. A temperature sensor 22 is provided so that the temperature sensor 22 can be disposed at a position that can be moved toward and away from the main body 25. In this example, the temperature sensor and the alarm main body are separated from each other, but may be integrated depending on the installation location of the alarm main body. That is, the installation position of the temperature sensor 22 is configured to be freely selectable with respect to the alarm device body 25, and includes a transmission means 22a for transmitting the temperature output from the temperature sensor 22 to the alarm device body 25 side. Yes. The alarm device body 25 is installed on the ceiling of the kitchen, and the temperature sensor 22 is constituted by a so-called thermistor, which is arranged at the lower end portion of the range hood 13. The transmission means 22a is configured as a cable line that can transmit a voltage output between both terminals of the thermistor to the side of the alarm device so that a change in resistance value generated in the thermistor can be detected.

  The alarm device body 25 is provided with a combustible gas detection sensor 21a for detecting a combustible gas (for example, methane), a power source 23 for supplying power to the entire alarm device, a temperature sensor 22, and a combustible gas. An arithmetic processing unit 26 is provided for processing the output from the property gas detection sensor 21a (the former output is described as a temperature output and the latter output as a gas-related output in FIG. 1). In the arithmetic processing unit 26, analog outputs from the sensors 21 and 22 are A / D converted and processed by digital signals.

  As shown in FIG. 1, the combustible gas sensor 21a includes a combustible gas detection element 21b (such as a combustible gas detection element made of a tin oxide semiconductor) made of a material sensitive to a combustible gas, and a temperature compensation element 21c. As a result of being assembled into a bridge together with predetermined resistors R1 and R2, applying a voltage between the predetermined terminals 21d and obtaining an output (voltage output) between the output terminals 21e, the combustible gas detecting element 21b By contact, the change in resistance value can be taken out in the form of voltage output as gas-related output.

  The arithmetic processing unit 26 is configured to execute predetermined threshold processing on the outputs from the sensors 21 and 22 and to output a gas alarm signal and a fire alarm signal, respectively. That is, as shown in FIG. 1, the arithmetic processing unit 26 is provided with a gas detection signal processing unit 26a, a fire detection signal processing unit 26b, and an alarm output unit 26c.

  The gas detection signal processing unit 26a stores a threshold value for outputting a gas alarm signal. At this part, the threshold value is compared with a gas-related output. The gas detection signal processing unit 26a is configured to output a gas alarm signal to the alarm output unit 26c.

The fire detection signal processing unit 26b stores a threshold value for outputting a fire alarm signal. At this part, the threshold value is compared with the temperature output, and this output is compared with the threshold value by the alarm issuing side. The fire detection signal processing unit 26b is configured to output a fire alarm signal to the alarm output unit 26c.
The alarm output unit 26c is a part that performs an alarm output process. Hereinafter, output forms corresponding to the respective alarm signals will be described.

Gas alarm signal When this alarm signal is received, it is expected that a gas leak has occurred. Therefore, a voice alarm such as “Is gas leaking?” Turn on 28 to output the possibility of gas leakage.

Fire alarm signal If any one or both of these alarm signals are received, a fire is expected to occur in response to the state where the temperature rise has been confirmed at the range hood location, and the speaker 27 is connected. Then, a sound alarm such as “fire is occurring” is issued, and the lighting lamp 28 is turned on to output a possibility of fire. In such an alarm issuing state, an alarm issuing maintaining function for maintaining the alarm issuing state is provided, and the alarm issuing state can be maintained and released by a predetermined reset switch 29. Yes. The above is the basic output form of the alarm in the main body of the alarm device when each alarm signal is received.

  Furthermore, the alarm device body 25 is provided with a use communication information intercepting unit 30 for intercepting the use communication information. And when use communication information is intercepted in this use communication information interception part 30, the above-mentioned use communication information is transmitted from this alarm machine body 25 to gas meter s3 with an electric communication form. Therefore, the gas meter s3 detects that the gas is being used in the range s1 by receiving this use communication information.

Gas meter (Gas meter with leak detection function)
FIG. 3 shows a schematic configuration of a gas meter s3 that mainly executes the gas leakage detection method according to the present invention. The gas meter s3 includes a flow meter 3 that can measure an instantaneous flow rate Q of the fuel gas flow G in the gas supply path 2, an adjustment valve 4 that applies a pressure change to the fuel gas flow G, a cutoff valve 5 that blocks the fuel gas flow G, A pressure gauge 6 for measuring the pressure P of the fuel gas flow G, a memory calculation control unit 7 for integrating the gas flow rate, and the like, a communication unit 8 for communicating with an external device, and a display unit 9 for displaying the integrated gas flow rate, etc. It has. In the present application, the gas / fire alarm s2 described above corresponds to an external device.

  The storage calculation control unit 7 performs a flow rate integration unit 7a that integrates the gas flow rate Q, a leak monitoring unit 7b that performs gas leak detection, a storage unit 7c that stores measurement results, calculation results, and the like, and inputs and outputs signals. An input / output unit 7d is provided, and the integrated gas flow rate integrated by the flow rate integrating unit 7a and the monitoring result of the gas leakage monitoring by the leakage monitoring unit 7b are output via the input / output unit 7d and displayed on the display unit 9. It is transmitted from the communication unit 8 to an external device.

  The leakage monitoring unit 7b operates the adjustment valve 4 when the gas flow rate Q measured by the flow meter 3 is in a steady state, thereby applying a pressure change applying means X1 that applies a pressure change to the gas flow G in the gas supply path 2. In this example, the pressure change applying means X1 performs, as one operation thereof, the pressure P of the gas flow G from the pressure P0 before the pressure change is applied, as indicated by a one-dot chain line in FIGS. First pressure change applied to pressure P1 (= P0 + ΔPa) changed by one set change amount ΔPa, and then, after a predetermined time, change from the pressure P1 after the first pressure change is applied by a second set change amount ΔPb. The pressure change is applied twice with the second pressure change applied to the pressure P2 (= P1 + ΔPb), and then the pressure P of the gas flow G after the second time pressure change is applied after a predetermined time. Pressure change from P2 It is the configuration back to the given front pressure P0 (= P2-ΔPa-ΔPb). The process of applying the pressure change and returning the pressure change to the original is sequentially performed based on the generated start command.

  Each of the predetermined times described above is a time required for the gas flow rate Q to be stabilized in a steady state of the flow rate through a transient change for each time the pressure change is applied.

  In addition, the leakage monitoring unit 7b detects a change in the gas flow rate Q caused by the pressure change applied each time by the flow measurement by the flow meter 3 for each of the two pressure changes applied by the pressure change applying means X1. X2 and the supply flow rate Q0 ′ to the gas appliance in which the control means for reducing the pressure change is incorporated in the total gas flow rate Q0 based on the detection result of the flow rate change detection means X2 and the measurement result of the pressure gauge 6. Computation means X3 for computing a flow rate Q0 ″ (non-control flow rate) other than (control flow rate) is provided.

  Furthermore, the leakage monitoring unit 7b is provided with usage communication information detection means X4 that receives the usage communication information transmitted from the range s1 as the external device via the gas / fire alarm s2. The use communication information detecting means X4 receives (detects) this use communication information to detect that the use communication information is transmitted and the transmission source (range s1) is in a state of using gas. It is configured as follows. When the use communication information is detected in this way, the use communication information detection means X4 is configured to output the use communication information to the output means X5.

  Then, the leakage monitoring unit 7b determines and confirms the presence of the uncontrolled flow rate Q0 ″ (which may be a leakage flow rate) obtained by the calculation by the calculation means X3, and the use communication information is not detected. Is continued for the set time limit Ts, it is determined that there is a possibility of gas leakage, and leakage information indicating the possibility of gas leakage is output, and the gas supply path 2 is shut off by the shutoff valve 5 Output means X5 is provided.

  More specifically, the supply flow rate (control flow rate Q0 ′) to the gas equipment incorporating the control means for reducing the pressure change (for example, automatic flow rate adjustment means such as a gas governor or PID control type) is In the state of occupying the gas flow rate Q0, even if the gas flow rate Q is changed by applying the pressure change twice by the pressure change applying means X1 (this change is assumed to be within a controllable range by the control means), FIG. As shown in the figure, for each of the first and second pressure changes, the gas flow rate Q returns to the flow rate Q0 before the pressure change through a temporary transient immediately after the pressure change is applied.

  On the other hand, there is no gas supply (control flow rate Q0 ′) to the gas equipment in which the control means for reducing the pressure change is incorporated, and the supply flow rate to the gas equipment in which the control means for reducing the pressure change is not incorporated, or the gas In the state where any of the generated flow rates due to leakage or the total gas flow rate (uncontrolled flow rate Q0 ″) occupies the total gas flow rate Q0 of the gas supply path 2, the pressure change applying means X1 performs two times. When the gas flow rate Q is changed by applying a pressure change, as shown in FIG. 5, the flow rate change corresponding to the applied pressure changes ΔPa and ΔPb does not restore the pressure for each of the first and second pressure changes. As long as it remains continuously.

In this case, the relationship between the flow rate and pressure before and after the application of the pressure change at each time is expressed by the following (Equation 8) and (Equation 9).
Q1 / Q0 = √ (P1 / P0) (Equation 8)
Q2 / Q1 = √ (P2 / P1) (Equation 9)

  Further, when the control flow rate Q0 ′ and the non-control flow rate Q0 ″ are mixed and the total flow rate (Q0 ′ + Q0 ″) is the total gas flow rate Q0 of the gas supply path 2, the pressure change applying means is provided. When the gas flow rate Q is changed by applying the pressure change twice by X1, as shown in FIG. 6, the part of the change in flow rate that has occurred with respect to the control flow rate Q0 ′ is shown for each of the first and second pressure changes. It disappears through a transient change immediately after the pressure change is applied, and the changed portion generated for the other uncontrolled flow rate Q0 ″ remains continuously unless the pressure is restored.

  In this case, the relationship between the flow rate and pressure before and after the application of the pressure change is expressed by the following (Expression 10) to (Expression 13) and (Expression 14) to (Expression 17).

Q1 ″ / Q0 ″ = √ (P1 / P0) (Equation 10)
Q0 = Q0 ′ + Q0 ″ (Equation 11)
Q1 = Q1 ′ + Q1 ″ (Equation 12)
Q0 ′ = Q1 ′ (Equation 13)

Q2 ″ / Q1 ″ = √ (P2 / P1) (Equation 14)
Q1 = Q1 ′ + Q1 ″ (Equation 15)
Q2 = Q2 ′ + Q2 ″ (Equation 16)
Q1 ′ = Q2 ′ (Equation 17)

  That is, (Equation 10) to (Equation 13) are the relationships among all gas flow rates Q0, Q1, control flow rates Q0 ', Q1', uncontrolled flow rates Q0 ", Q1", and pressures P0, P1 before and after the first pressure change. (Equation 14) to (Equation 17) are the total gas flow rates Q1, Q2, control flow rates Q1 ′, Q2 ′, uncontrolled flow rates Q1 ″, Q2 ″, and pressures P1, P2 before and after the second pressure change application. Show the relationship.

  Here, (Equation 9) is an equation equivalent to (Equation 14) under the condition of Q1 = Q1 ″ and Q2 = Q2 ″, and therefore, (Equation 14) is represented by each equation on behalf of both equations. Based on the following modification, the following (Equation 18) is obtained.

(Q2−Q2 ′) / (Q1−Q1 ′) = √ (P2 / P1)
(Q2−Q1 ′) / (Q1−Q1 ′) = √ (P2 / P1)
(Q2-Q0 ') / (Q1-Q0') = √ (P2 / P1)
(Q2−Q0 + Q0 ″) / (Q1−Q0 + Q0 ″) = √ (P2 / P1) (Equation 18)

  If the reference pressure is atmospheric pressure and the pressures P1 and P2 of each stage are differential pressures from the atmospheric pressure, the uncontrolled flow rate Q0 ″ (typically the flow rate due to gas leakage) becomes 0 at atmospheric pressure. Therefore, the above (formula 18) is expressed by the following (formula 19),

  (Q2-Q0) / (Q1-Q0) = √ (P2 / P1) (Equation 19)

In other words, the calculation means X3 is based on the detection result of the flow rate change detection means X2 and the measurement result of the pressure gauge 6 and incorporates a non-control flow rate Q0 ″ (control means for reducing the pressure change from the relationship shown in the above equations. Therefore, the calculation means X3 is calculated by the flow rate change detection means X2 with the meaning of the flow rate that may be the flow rate caused by gas leakage. It functions as a non-control flow rate discriminating means for discriminating the presence of a non-control flow rate other than the supply flow rate to the gas equipment in which the control means for reducing the pressure change is incorporated according to the detected gas flow rate change.
On the other hand, the used communication information detecting means X4 provided in the leakage monitoring unit 7b constantly monitors whether used communication information is detected. That is, in the gas / fire alarm device s2, it is monitored whether or not the use communication information transmitted from the range s1 is intercepted. Information is detected.

  Then, as shown in FIG. 8, the output means X5 determines that there is a possibility of gas leakage when the presence of the leakage flow rate Q0 ″ continues for a predetermined time limit Ts in a state where the use communication information is not detected. However, when the leakage flow rate Q0 ″ is a flow rate generated by gas leakage, the greater the leakage flow rate Q0 ″, the higher the degree of danger. Therefore, the leakage flow rate Q0 stored in the storage unit 7c as shown in FIG. According to the setting relationship L between ″ and the limit time Ts, a shorter limit time Ts is selected as the leakage flow rate Q0 is larger, and when the leakage flow rate Q0 ″ continues for the set limit time Ts, there is a possibility of gas leakage. It is determined that the leak information is output and the gas supply path 2 is shut off. Here, the relationship between the leakage flow rate Q0 ″ and the time limit Ts is, for example, when a gas leak occurs at a predetermined speed corresponding to the previous leakage flow rate Q0 ″ in a room of a predetermined volume, for example, the air in the room. When the gas concentration is changed once every two hours, it is required as a limit time in which the gas concentration in the room is kept below the limit concentration.

  Further, as shown in FIG. 8, when there is another gas flow rate change more than a predetermined change amount not due to pressure change application during the set limit time Ts as shown in FIG. In the closest flow steady state, the second pressure change is applied again. On the other hand, the output means X5 changes the leakage flow Q0 ″ (uncontrolled flow) by applying the second pressure change again. Yes, when the used communication information is not detected, the measurement of the set time limit Ts up to that point is terminated halfway, and the measurement of the set time limit Ts newly selected for the changed leakage flow rate Q0 ″ is started. It is configured.

  That is, (see FIG. 8), the change in the gas flow rate Q due to the re-applying of the pressure change is examined, and when there is no change in the leakage flow rate Q0 ″, the set time limit Ts for the leakage flow rate Q0 ″ (the time measurement is started first). If the leakage flow rate Q0 ″ continues to be unchanged over the setting time limit Ts, it is determined that there is a possibility of gas leakage, and the leakage information output and the gas supply path 2 is cut off.

  On the other hand, when the change in the gas flow rate Q due to the re-applying of the pressure change is examined and the leakage flow rate Q0 ″ has changed and no communication information has been detected, the previous leakage flow rate Q0 ″ (uncontrolled flow rate) Assuming that there is a high possibility that there was a new start of the use of gas equipment that does not incorporate a control means to reduce the pressure change with respect to the existence, the set time limit Ts until that time was stopped halfway, and the leakage flow rate after the change The continuation of the set time limit Ts newly selected for Q0 ″ is started.

After that, when the changed leakage flow rate Q0 ″ continues without changing again over the new set time limit Ts, it is determined that there is a possibility of gas leakage, and leakage information is output and gas is supplied. The road 2 is blocked.
With the above configuration, it is possible to satisfactorily manage the state where the uncontrolled flow rate is generated.

In addition, each formula demonstrated so far in this invention is a formula formed about the gas flow rate and gas pressure in the location immediately before the gas equipment in a gas supply path. Therefore, for the gas flow rate and gas pressure at a location where the distance to the gas device is large and the pressure loss in the gas supply path to the gas device is large, an error occurs in the calculation according to the above formulas. Since the distance between the gas meter and the gas equipment is practically limited in the facility, the error is not particularly problematic.
[Another embodiment]
In the above-described embodiment, the case where the gas device is a range with a stove has been shown. However, as such an uncontrolled gas device, there are a conventional simple-type stove, a table stove, a built-in stove, and the like.

In the above-described embodiment, the configuration in which the use communication information transmitted from the uncontrolled gas device is intercepted by the gas / fire alarm is shown, but a dedicated receiving device for receiving the use communication information may be provided, As long as the usage communication information received by the gas device can be received in relation to the gas device targeted by the present application, the reception function may be provided in any device.
In the above-described embodiment, as a gas alarm, leakage gas detection for detecting leakage of methane gas or the like, incomplete combustion detection for detecting incomplete combustion by detection of carbon monoxide gas or the like (methane gas detection and carbon monoxide gas detection is (Although it is possible to use the tin oxide semiconductor described above), the alarm device that can detect a fire has been explained, but the gas alarm device that can be used as a relay device does not have to be able to detect all of them. Any one or more of these may be detected.

  The home where the gas leak detection system according to the present application is constructed is a home security system (such as home safety, gas, fire, invasion of a third party other than the householder, the householder does not move for a long period of time, etc. If you have a system that monitors from the viewpoint and if there is a possibility that an abnormality has occurred, send a security guard etc. to the home and notify the police, fire department, etc.), this home security system will be explained first Then, it may be configured to suck up the used communication information and send it to the used communication information detecting means side through this home security system.

  In communication of used communication information, it is preferable to use infrared rays as shown in the previous embodiment, but any communication medium can be used as the communication medium.

  In the above-described embodiment, the pressure change amount ΔPa, ΔPb each time is made different to apply the pressure change a plurality of times, and the change in the gas flow rate Q generated in each of the plurality of times the pressure change is applied is examined, thereby leaking the flow rate Q0 ″. Although an example of obtaining (non-control flow rate) has been shown, only one pressure change is applied as one operation of the pressure change applying means X1, and a change in the gas flow rate Q caused by this one pressure change is examined. The leakage flow rate Q0 ″ (uncontrolled flow rate) may be obtained.

  In the above-described embodiment, an example in which the pressure change is applied by the operation of the adjustment valve 4 by the pressure change application unit X1 has been described. Instead of the application of the pressure change by the operation of the adjustment valve, a turbine, a windmill, or the like is used. The pressure change on the pressure reduction side may be applied by an expander, or the pressure change on the pressure increase side may be applied by a pressurizing means such as a pump or a fan.

  Furthermore, in order to apply a pressure change to the gas flow G in the steady flow rate state, depending on the gas flow rate Q in the steady flow rate state, the degree of the pressure change to be applied is different, the pressure changing device is used properly, The number of devices to be changed may be varied, or the pressure change application on the pressure increase side and the pressure change application on the pressure reduction side may be used properly.

  It is possible to accurately determine the possibility of gas leakage when there is a high possibility that gas leakage has occurred on the downstream side, and it is possible to obtain a gas leakage detection system that can effectively improve safety, It is particularly suitable for improving the function of gas meters.

Schematic configuration diagram of a gas leak detection system according to the present application The figure which shows the general view of the kitchen which employ | adopted the gas leak detection system which concerns on this application Schematic configuration diagram of gas meter A graph showing the flow rate change when the total gas flow rate is the control flow rate with two pressure changes applied Graph showing the flow rate change when the total gas flow rate is an uncontrolled flow rate with two pressure changes Graph showing flow rate change when control flow rate and non-control flow rate coexist by applying pressure change twice Graph showing the setting relationship between leakage flow rate (uncontrolled flow rate) and time limit Gas leakage detection control flowchart A graph showing the flow rate change when the total gas flow rate is the control flow rate with one pressure change applied A graph showing the flow rate change when the total gas flow rate is an uncontrolled flow rate with a single pressure change. Graph showing flow rate change when control flow rate and non-control flow rate coexist with one pressure change

Explanation of symbols

2 Gas supply path G Gas flow P Pressure Q Gas flow Q0 ″ Leakage flow S Gas leak detection system s1 Range with stove (gas equipment / gas combustion equipment)
s2 Gas / fire alarm (gas alarm)
s3 gas meter Ts time limit X1 pressure change applying means X2 flow rate change detecting means X3 computing means (uncontrolled flow rate determining means)
X4 used communication information detection means X5 output means

Claims (5)

In a gas supply path in which one or a plurality of gas devices are connected to the downstream side, pressure change applying means for applying a pressure change to a gas flow in a steady flow rate flowing through the gas supply path;
A flow rate change detecting means for detecting a change in gas flow rate caused by a pressure change applied by the pressure change applying means;
A non-control flow rate determination means for determining the presence of a non-control flow rate other than the supply flow rate to the gas equipment in which the control means for reducing the pressure change is incorporated by the change in the gas flow rate detected by the flow rate change detection means,
Communication information generated from gas equipment that detects use communication information generated by the use of gas from uncontrolled gas equipment from non-controlled gas equipment that does not incorporate control means to reduce pressure changes Use communication information detecting means
Based on the non-control flow rate existence determination result by the non-control flow rate determination means and the use communication information detection result by the use communication information detection means,
When the use communication information is detected in a situation where it is determined that the uncontrolled flow rate exists, it is determined that the uncontrolled flow rate is not a leakage flow rate, and in a situation where it is determined that the uncontrolled flow rate exists, When the use communication information is not detected, a gas leak detection system that determines that the uncontrolled flow rate is likely to be a leak flow rate and detects a leak on the downstream side. The gas leakage detection system according to claim 1, wherein the uncontrolled gas device is a gas combustion device, and the use communication information is transmission information transmitted from the gas combustion device to operate a ventilation facility. Use communication information generated from the uncontrolled gas equipment is infrared communication information communicated by infrared rays,
The gas leak detection system according to claim 1 or 2, wherein the use communication information is information obtained by intercepting the infrared communication information, converted into wired or wireless telecommunication information, and obtained via a repeater. The gas leak detection system according to any one of claims 1 to 3, wherein the use communication information is information obtained via a wired or wireless telecommunication function provided in an alarm device. The gas leak detection system according to claim 4 , wherein the use communication information is information obtained by communication with a home security system that has received communication from the alarm device.

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