Gas leak detection device and gas meter

Abstract

A gas leak detection device (10) is positioned on a gas pipe (20), which supplies gas to a gas appliance (21) and is provided with an opening / closing valve (24). The gas leak detection device comprises a pressure gauge (13) that measures the pressure of gas in the gas pipe downstream of the opening / closing valve, an output device that outputs information, and a control device (11). The control device performs a guidance output operation for outputting, to the output device, guidance information for closing the opening / closing valve, performs a pressure measurement operation for using the pressure gauge to measure the pressure after performing the guidance output operation, and performs a gas leak determination operation for determining the possibility of a gas leak on the basis of the pressure measured during the pressure measurement operation.

Description

Gas leak detectors and gas meters

[0001] The present disclosure relates to a gas leak detection device and a gas meter that determine the possibility of a gas leak in a gas pipe.

[0002] A known example of a conventional gas leak detection device is the gas leak detection device disclosed in Patent Document 1. This gas leak detection device closes a shutoff valve when the availability of gas is low, and determines that a gas leak has occurred when it detects that the gas pressure has dropped by a certain amount or more.

[0003] Japanese Patent Application Publication No. 8-5502

[0004] Conventional gas leak detection devices automatically close the shutoff valve during times of day when gas equipment is unlikely to be used, determining that the time period when gas availability is low. However, such times of low gas availability are not necessarily times when users do not use gas. Furthermore, there are cases where users want to detect gas leaks outside of times when gas availability is low. As such, conventional gas leak detection devices have had the problem of not being able to detect gas leaks in accordance with the user's intentions.

[0005] The present disclosure has been made to solve such problems, and aims to provide a gas leak detection device and a gas meter that can detect the possibility of a gas leak in accordance with the user's intentions.

[0006] A gas leak detection device according to one aspect of the present disclosure is a gas leak detection device that is placed in a gas pipe that supplies gas to a gas appliance and is provided with an on-off valve, and includes a pressure gauge that measures the gas pressure in the gas pipe downstream of the on-off valve, an output device that outputs information, and a control device, wherein the control device performs a guide output operation that outputs guide information to close the on-off valve to the output device, performs a pressure measurement operation that measures the pressure using the pressure gauge after performing the guide output operation, and performs a gas leak determination operation that determines the possibility of a gas leak based on the pressure measured in the pressure measurement operation.

[0007] In such a gas leak detection device, the user can close the on-off valve in accordance with the guidance information output to the output device by the guidance output operation. The gas pressure in the gas pipe is measured when the user shuts off the gas pipe with the on-off valve, and the possibility of a gas leak is determined based on the measured pressure. In this way, the possibility of a gas leak can be detected in accordance with the user's intention.

[0008] The above and other objects, features and advantages of the present disclosure will become apparent from the following detailed description of preferred embodiments, which proceeds with reference to the accompanying drawings.

[0009] 7A shows a display device displaying result information when there is a large change in atmospheric pressure. FIG. 7B shows a display device displaying result information when there is a large change in temperature. FIG. 7B shows a display device displaying result information when there is a large change in temperature. FIG. 7C shows a display device displaying result information when there is a large change in temperature. FIG. 7D shows a display device displaying result information when there is a large change in temperature. FIG. 7E shows a display device displaying result information when there is a large change in atmospheric pressure. FIG. 7F shows a display device displaying result information when there is a large change in temperature. FIG. 7G shows a display device displaying result information when there is a large change in temperature. FIG. 7H shows a display device displaying result information when there is a large change in atmospheric pressure. FIG. 7H shows a display device displaying result information when there is a large change in temperature. FIG. 7I shows a display device displaying result information when there is a large change in atmospheric pressure. FIG. 7I shows a display device displaying result information when there is a large change in temperature ... 10 is a flowchart showing an example of a gas detection process according to Modification 7 of the present disclosure; FIG. 11 is a flowchart showing an example of a gas detection process according to Modification 8 of the present disclosure; FIG. 12 is a flowchart showing an example of a gas detection process according to Modification 9 of the present disclosure;

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that, in the following, the same or corresponding elements will be designated by the same reference numerals throughout the drawings, and redundant description thereof will be omitted.

[0011] 1, a gas leak detection device 10 according to a first embodiment of the present disclosure is a device that detects the possibility of a gas leak in a gas pipe 20 and a gas appliance 21, and is provided, for example, in a gas meter 22 provided in the gas pipe 20. The gas pipe 20 is a conduit connected between a gas supply source 23 and a gas appliance 21 of a gas consumer, and supplies gas from the gas supply source 23 to the gas appliance 21. The gas appliance 21 is a device that consumes gas, and includes a gas stove, a water heater, a heater, etc.

[0012] The gas pipe 20 is provided with an on-off valve 24, a so-called main valve, that opens and closes the gas pipe 20. The on-off valve 24 is a manual valve operated by a user, and opens and closes the gas pipe 20 by user operation. In other words, when the on-off valve 24 is operated by a user to open the gas pipe 20, the gas pipe 20 is opened to allow gas to flow through. When the on-off valve 24 is operated by a user to close the gas pipe 20, the gas pipe 20 is shut off to prevent gas from flowing through.

[0013] The gas meter 22 is provided on the gas piping 20 between the on-off valve 24 and the gas appliance 21, and includes a flow meter 25 and a gas leak detection device 10. The gas leak detection device 10 includes a control device 11. The control device 11 of the gas leak detection device 10 is also used as the control device 11 of the gas meter 22. However, the control device of the gas leak detection device 10 and the control device of the gas meter 22 may be provided separately. In this case, these control devices may cooperate with each other to control the gas meter 22. The control device 11 will be described later.

[0014] The flow meter 25 is provided in the gas pipe 20 and measures the volume or mass ((instantaneous) flow rate) of gas passing through the gas pipe 20 per unit time, and outputs the result to the control device 11 .

[0015] The gas leak detection device 10 further includes a shutoff valve 12. The shutoff valve 12 is provided in the gas pipe 20 upstream of the flow meter 25. The shutoff valve 12 is controlled by the control device 11 to open and close the gas pipe 20. That is, when the control device 11 controls the shutoff valve 12 to open the gas pipe 20, the gas pipe 20 is opened to allow gas to flow through. When the control device 11 controls the shutoff valve 12 to close the gas pipe 20, the gas pipe 20 is closed to prevent gas from flowing through.

[0016] The gas leak detection device 10 further includes a pressure gauge 13. The pressure gauge 13 is provided in the gas pipe 20 downstream of the shut-off valve 12, and measures the gas pressure in the gas pipe 20 and outputs the measured value to the control device 11. The gas pressure measured by the pressure gauge 13 may be a relative pressure of the gas based on atmospheric pressure. The relative pressure is the difference between the absolute pressure of the gas and atmospheric pressure. The gas pressure measured by the pressure gauge 13 may also be an absolute pressure of the gas. The absolute pressure may be calculated from the atmospheric pressure measured by a barometer and the gas pressure measured by the pressure gauge 13.

[0017] The gas leak detection device 10 further includes a display device 14 and a communication interface 15. The display device 14 is, for example, a liquid crystal display, and displays information. The communication interface 15 transmits and receives information to and from an external device via wireless or wired communication. For example, the external device is a computer of a gas supplier or a company that manages the gas meter 22.

[0018] The gas leak detection device 10 further includes an input device 16. The input device 16 is, for example, a push button switch or the like, and is operated by a user to input information to the control device 11. For example, if the input device 16 is a push button switch, the user's operation of the push button switch is pre-associated with the input information. A short press operation in which the user presses the push button switch for less than a predetermined time is pre-associated with a restoration instruction to open the gas pipe 20 from being blocked by the shutoff valve 12. The input device 16 may also include a communication interface 15. In this case, the communication interface 15 receives information from an external device and inputs the information to the control device 11.

[0019] The control device 11 is a computer that controls the electrical devices of the gas meter 22, and is exemplified by a microcontroller, for example. The control device 11 includes, for example, a processor and a memory accessible to the processor. The processor executes programs stored in the memory to control each part of the gas meter 22. In this way, the control device 11 executes various processes for the gas meter 22, such as flow rate measurement process, safety process, and gas leak detection process.

[0020] Representative configurations of the control device 11 include, for example, a configuration in which a computing device such as a general-purpose processor, a dedicated processor, an integrated circuit, an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuits), or a GPU is used alone or in combination with two or more types, and operates to realize its control function in accordance with a program stored in a storage device.

[0021] Such a processor as an arithmetic device is a hardware circuit (or processing circuit) because it includes a circuit configured with a large number of transistors, memories, etc. Integrated circuits or ASICs are also hardware circuits because they include processors or processing blocks such as CPUs. FPGAs are hardware circuits because they include a large number of integrated logic circuits (functional blocks). GPUs are hardware circuits because they include a large number of arithmetic circuits (cores) mounted in parallel. Software such as programs stored in a storage device is used to configure hardware circuits (processors, integrated circuits, FPGAs, ASICs, GPUs, etc.). Alternatively, the arithmetic device may be configured as a logic circuit or the like using known switching elements, subtractors, comparators, etc.

[0022] The specific configuration of the storage device is not particularly limited. For example, it may be configured as an internal memory of a microcomputer or a microcontroller unit (MCU), or it may be configured as an independent memory. Furthermore, the storage device does not have to be a single device, and multiple devices may be used.

[0023] <Flow Rate Measurement Process> The control device 11 causes the flow meter 25 to measure the flow rate of gas flowing through the gas pipe 20 at predetermined time intervals, for example, every two seconds. The control device 11 then accumulates the gas flow rates measured by the flow meter 25 and outputs this accumulated value as the consumption rate to the display device 14 or the communication interface 15. As a result, the gas consumption rate is displayed on the display device 14 or transmitted via the communication interface 15 to an external device such as a gas supplier.

[0024] <Safety Processing> Normally, the shutoff valve 12 is in an open state, and the gas piping 20 is open to allow gas to flow. In this state, for example, the control device 11 causes the pressure gauge 13 to measure the gas pressure in the gas piping 20 at predetermined time intervals, for example, every 10 seconds. Then, when a predetermined safety condition occurs, the control device 11 executes valve closing control on the shutoff valve 12, and shuts off the gas piping 20 with the shutoff valve 12. As a result, gas is not supplied to the gas appliance 21, and the gas appliance 21 becomes unusable. The safety condition occurs, for example, when the gas flow rate is equal to or greater than a predetermined flow rate, and when the gas pressure drops below a predetermined pressure.

[0025] Furthermore, when a user briefly presses the push button switch, which is the input device 16, the control device 11 determines that a return command corresponding to the short press has been input, and executes valve opening control of the shutoff valve 12 to open the gas piping 20. This allows gas to be supplied to the gas appliance 21, making the gas appliance 21 usable. The control details such as the valve closing control and valve opening control of the shutoff valve 12 are stored in memory.

[0026] <Gas Leak Detection Process> The gas leak detection process is executed by the control device 11 according to the example flowchart of FIG. 2. First, the control device 11 executes a start determination operation to determine whether a command to start the gas leak detection process has been input via the input device 16 (step S10). This start command is pre-associated with a user operation of the input device 16. For example, a long press operation in which the user presses a push button switch, which is the input device 16, for a predetermined period of time or longer is pre-associated with a command to start the gas leak detection process. In this case, the control device 11 monitors the long press operation of the push button switch while it is not being performed (step S10: NO). On the other hand, when a long press operation is performed, the control device 11 determines that a start command has been input via the input device 16 (step S10: YES).

[0027] Next, the control device 11 determines whether the shutoff valve 12 is in an open state (step S11). This shutoff valve 12 is controlled to be closed or open by the control device 11 during safety processing, and the control content is stored in memory. Therefore, if the latest control content is valve close control, the control device 11 determines that the shutoff valve 12 is in a closed state (step S11: NO), and terminates the processing because the gas leak detection processing cannot be executed. On the other hand, if the control content of the shutoff valve 12 does not include valve close control and if the latest control content is valve open control, the control device 11 determines that the shutoff valve 12 is in an open state (step S11: YES).

[0028] Next, the control device 11 executes a guide display operation to display guide information for closing the on-off valve 24 on the display device 14 (step S12). For example, as shown in FIG. 3A, the control device 11 displays guide information such as "Please close the on-off valve" on the display device 14. The user sees the guide information and performs a valve closing operation on the on-off valve 24. As a result, the on-off valve 24 shuts off the gas piping 20, and gas is no longer supplied to the gas piping 20 and gas appliances 21 downstream of the on-off valve 24. Furthermore, because the gas appliances 21 are not in use, gas no longer flows in the gas piping 20 between the on-off valve 24 and the gas appliances 21.

[0029] The control device 11 also executes a first timing operation (step S13). In this first timing operation, the control device 11 measures the remaining time from a first predetermined time, for example, 5 seconds, and displays the remaining time on the display device 14 as shown in the example of FIG. 3A. This remaining time decreases as time passes from the time the guide information is displayed. The user views the remaining time and is prompted to close the on-off valve 24 within the remaining time.

[0030] Next, the control device 11 determines whether a first predetermined time has elapsed since the execution of the guide display operation (step S14). Here, the control device 11 measures the remaining time until the first predetermined time has elapsed (step S14: NO) and displays it on the display device 14. Then, when the first predetermined time has elapsed and the remaining time becomes 0 (step S14: YES), the control device 11 executes a second timing operation (step S15). In the second timing operation, the control device 11 measures the elapsed time since the end of the first timing operation.

[0031] Next, the control device 11 executes a pressure measurement operation to measure the pressure using the pressure gauge 13 (step S16). In the pressure measurement operation, the control device 11 measures the gas pressure in the gas pipe 20 using the pressure gauge 13 and stores the result in memory in a state in which gas is not supplied to the gas pipe 20 and gas appliances 21 downstream of the on-off valve 24. Here, the control device 11 displays "pressure measurement in progress" on the display device 14 as shown in FIG. 3B.

[0032] Next, the control device 11 executes a gas leak determination operation to determine the possibility of a gas leak based on the pressure measured in the pressure measurement operation (step S17). In this gas leak determination operation, the control device 11 calculates the difference by subtracting the gas pressure measured in the pressure measurement operation from a predetermined reference pressure, and determines whether this pressure difference is less than a predetermined pressure difference. This reference pressure is, for example, the gas pressure immediately after the on-off valve 24 is closed, and the gas pressure initially measured in the pressure measurement operation in step S16 is used.

[0033] The possibility of a gas leak is determined based on the gas pressure drop (pressure difference) when the gas pipe 20 is shut off by the on-off valve 24. Therefore, the reference pressure may be any pressure that can derive such a pressure drop. For example, the reference pressure may be the gas pressure immediately before the on-off valve 24 is closed. In this case, after determining in step S11 that the shut-off valve 12 is in the open state and before executing the guide display operation in step S12, the control device 11 may measure the gas pressure with the pressure gauge 13 and use the measured pressure as the reference pressure.

[0034] In step S17, if the control device 11 determines that the pressure difference is equal to or greater than the predetermined pressure difference (step S17: NO), the pressure difference from the reference pressure to the measured pressure is large, and therefore the control device 11 determines that there is a possibility of a gas leak in the gas piping 20 and the gas appliance 21 downstream of the on-off valve 24.

[0035] 3D, the control device 11 executes a result display operation to display the possibility of a gas leak based on the gas pressure measured in the pressure measurement operation. In this result display operation, the control device 11 displays the determination result of the possibility of a gas leak and the measured pressure measured in the pressure measurement operation of step S16 on the display device 14 (step S20). By viewing this display, the user can take measures to prevent the gas leak, such as contacting the gas company, or open the on-off valve 24.

[0036] On the other hand, if the control device 11 determines in step S17 that the pressure difference is less than the predetermined pressure difference (step S17: YES), it determines whether the measurement time in the second measurement operation of step S15 has reached a predetermined time, for example, 3 minutes (step S18). If this measurement time has not reached the predetermined time (step S18: NO), the control device 11 returns to the process of step S16 and repeats the subsequent processes. As a result, the control device 11 measures the gas pressure at predetermined time intervals.

[0037] If the pressure difference is less than the predetermined pressure difference (step S17: YES) and the measurement time reaches the predetermined time (step S18: YES), the control device 11 determines that there is no possibility of gas leakage in the gas piping 20 and the gas appliance 21 downstream of the on-off valve 24 because the pressure difference from the reference pressure to the measured pressure is small.

[0038] 3C, the control device 11 then executes a result display operation. In this result display operation, the control device 11 displays on the display device 14 the determination result that there is no possibility of a gas leak and the measured pressure measured by the pressure measurement operation of step S16 (step S19). By viewing this display, the user can confirm that there is no possibility of a gas leak and open the on-off valve 24. This opens the gas pipe 20, allowing gas to pass through the gas pipe 20 and be supplied to the gas appliance 21, enabling the gas appliance 21 to be used.

[0039] According to this gas leak detection process, the control device 11 executes a guide display operation to display, on the display device 14, guide information for closing the on-off valve 24. The user looks at this guide display and operates the on-off valve 24 to shut off the gas piping 20. This makes it possible to detect a gas leak in the gas piping 20 or the like that has been shut off by the on-off valve 24, in line with the user's intention.

[0040] The control device 11 also executes a start determination operation to determine whether a start command has been input via the input device 16, and executes a guidance output operation if it determines in the start determination operation that a start command has been input. In this way, the user inputs a start command by operating the input device 16, and the guidance output operation is executed in response to this start command. This allows the on-off valve 24 to be closed in accordance with the user's intention, making it possible to detect gas leaks in the gas pipe 20 or the like that have been shut off by the on-off valve 24.

[0041] <Embodiment 2> In a gas leak detection device 10 according to embodiment 2 of the present disclosure, the control device 11 executes a gas leak detection process in accordance with the example flowchart shown in Fig. 4. In the flowchart of Fig. 4, control to close the shutoff valve 12 in step S30 is executed instead of the processes of steps S12 to S14 in the flowchart of Fig. 2. Also, in the flowchart of Fig. 4, control to open the shutoff valve 12 in step S31 is executed after the processes of steps S19 to S20 in the flowchart of Fig. 2.

[0042] Specifically, the control device 11 executes a start determination operation to determine whether or not a command to start the gas leak detection process has been input via the input device 16 (step S10). If a command to start the gas leak detection process has been input via the input device 16 (step S10: YES), the control device 11 determines whether or not the shutoff valve 12 is open (step S11). If the shutoff valve 12 is closed (step S11: NO), the control device 11 ends the gas leak detection process.

[0043] On the other hand, if the shutoff valve 12 is in an open state (step S11: YES), the control device 11 executes a shutoff operation to shut off the gas piping 20 using the shutoff valve 12 (step S30). In this shutoff operation, the control device 11 controls the shutoff valve 12 to close, shutting off the gas piping 20. As a result, gas is not supplied to the gas piping 20 and the gas appliance 21 downstream of the shutoff valve 12, and gas does not flow in the gas piping 20 between the shutoff valve 12 and the gas appliance 21.

[0044] Next, the control device 11 executes a pressure measurement operation to measure the pressure using the pressure gauge 13 (step S16). In the pressure measurement operation, the control device 11 measures the gas pressure in the gas pipe 20 using the pressure gauge 13 in a state where gas is not supplied to the gas pipe 20 and the gas appliances 21 downstream of the shut-off valve 12. Then, the control device 11 executes a gas leak determination operation (step S17). In this gas leak determination operation, the control device 11 calculates the difference by subtracting the measured pressure from the reference pressure, and determines whether this pressure difference is less than a predetermined pressure difference.

[0045] This reference pressure is, for example, the gas pressure immediately after the shutoff valve 12 is controlled to close, and is the gas pressure measured first in the pressure measurement operation of step S16. Note that the possibility of a gas leak is determined based on the gas pressure drop (pressure difference) when the gas piping 20 is shut off by the shutoff valve 12. Therefore, the reference pressure may be any pressure that can derive such a pressure drop. For example, the reference pressure may be the gas pressure immediately before the shutoff valve 12 is controlled to close. In this case, the control device 11 may measure the gas pressure with the pressure gauge 13 after determining that the shutoff valve 12 is in the open state in step S11 and before the shutoff valve 12 is controlled to close in step S30, and use the measured pressure as the reference pressure.

[0046] In the gas leak determination operation of step S17, if the control device 11 determines that the pressure difference is equal to or greater than the predetermined pressure difference (step S17: NO), it determines that there is a possibility of a gas leak in the gas piping 20 and the gas appliance 21 downstream of the shut-off valve 12. Then, as shown in Fig. 3D, the control device 11 displays the determination result of the possibility of a gas leak and the measured pressure measured by the pressure measurement operation of step S16 on the display device 14. Furthermore, the control device 11 executes valve opening control of the shut-off valve 12 (step S31), thereby opening the gas piping 20 and enabling the gas appliance 21 to be used.

[0047] On the other hand, if the pressure difference is less than the predetermined pressure difference (step S17: YES) and the measurement time reaches the predetermined time (step S18: YES), the control device 11 determines that there is no possibility of a gas leak in the gas piping 20 and the gas appliance 21 downstream of the shutoff valve 12. Then, as shown in Fig. 3C, the control device 11 executes a result display operation and displays the determination result of no possibility of a gas leak and the measured pressure measured by the pressure measurement operation of step S16 on the display device 14 (step S19). Furthermore, the control device 11 executes valve opening control of the shutoff valve 12 (step S31), thereby opening the gas piping 20 and enabling the gas appliance 21 to be used.

[0048] According to this gas leak detection process, the control device 11 executes a start determination operation to determine whether a start command has been input via the input device 16, and if it determines in the start determination operation that a start command has been input, executes valve closing control of the shutoff valve 12. In this way, when a user operates the input device 16 to input a start command, the gas pipe 20 is shut off by the shutoff valve 12 in accordance with the user's intention. Therefore, it is possible to detect a gas leak in the gas pipe 20, etc., shut off by the shutoff valve 12, in accordance with the user's intention.

[0049] <Third Embodiment> In a gas meter 22 according to a third embodiment of the present disclosure, the control device 11 executes a gas leak detection process in accordance with the flowchart shown in the example of Fig. 5. In the flowchart of Fig. 5, the flow rate measurement operation of step S40 is executed after the process of step S15 in the flowchart of Fig. 2, and the acquisition operation of step S41 is executed after the process of step S18 in the flowchart of Fig. 2. Note that, in the flowchart of Fig. 4 as well, the flow rate measurement operation of step S40 may be executed after the process of step S15, and the acquisition operation of step S41 may be executed after the process of step S18. In this case, the gas pipe 20 is shut off and opened by the shutoff valve 12 instead of the on-off valve 24.

[0050] That is, after executing the second timing operation (step S15), the control device 11 executes a flow rate measurement operation (step S40) to measure the flow rate using the flow meter 25. In the flow rate measurement operation, the control device 11 measures the flow rate of gas flowing through the gas piping 20 downstream of the on-off valve 24 using the flow meter 25 in a state where gas is not supplied to the gas piping 20 and gas appliances 21 downstream of the on-off valve 24, and stores the measured flow rate in memory.

[0051] Then, when the pressure difference of the gas during the execution of the flow rate measurement operation is less than the predetermined pressure difference (step S17: YES) and the measurement time reaches the predetermined time (step S18: YES), the control device 11 executes an acquisition operation to acquire a correction value of the flow rate based on the flow rate measured in the flow rate measurement operation (step S19). In this way, in a state where the pressure difference is less than the predetermined pressure difference, there is no possibility of gas leakage in the gas piping 20, and the gas piping 20 is shut off by the on-off valve 24, the control device 11 acquires the measured flow rate by the flow rate measurement operation as a correction value of the gas flow rate and stores it in memory.

[0052] When the gas flow rate is measured at predetermined time intervals during the flow rate measurement operation, the control device 11 acquires multiple measured flow rates. In this case, the control device 11 may acquire a representative value of the multiple measured flow rates as the correction value. This representative value may be the average, median, mode, etc. of the multiple measured flow rates.

[0053] In this way, the control device 11 can determine the possibility of a gas leak and obtain a correction value for the gas flow rate when the gas pipe 20 is shut off by the on-off valve 24. Furthermore, the control device 11 can obtain an accurate gas flow rate in the flow rate measurement process of the gas meter 22 by correcting the gas flow rate measured by the flow meter 25 using this correction value.

[0054] <Modification 1> In Modification 1 of the present disclosure, in addition to the first to third embodiments, the gas leak detection device 10 further includes a barometer 17 that measures atmospheric pressure, as shown in Fig. 1. The barometer 17 is disposed in the housing 22a of the gas meter 22 near the pressure gauge 13, measures the atmospheric pressure, and outputs the measured value to the control device 11.

[0055] In this case, the control device 11 executes the gas leak detection process according to the example flowchart shown in Fig. 6. In the flowchart of Fig. 6, the processes of steps S50 to S53 are executed after the process of step S16 in the flowchart of Fig. 2. Note that the processes of steps S50 to S53 may also be executed after the process of step S16 in the flowcharts of Fig. 4 and Fig. 5. In the case of Fig. 4, the gas pipe 20 is shut off and opened by the shutoff valve 12 instead of the on-off valve 24.

[0056] In step S16, the control device 11 executes a pressure measurement operation (step S16). In the pressure measurement operation, the control device 11 measures the gas pressure in the gas pipe 20 using the pressure gauge 13 while the gas pipe 20 is shut off by the on-off valve 24. However, if this measured pressure is a relative pressure, it may be affected by atmospheric pressure. For this reason, the control device 11 executes a pressure measurement operation to measure the relative pressure of the gas using the pressure gauge 13, and also an air pressure measurement operation to measure the atmospheric pressure using the barometer 17 (step S50). As a result, the atmospheric pressure is measured when the relative pressure of the gas is measured, and these are stored in correspondence in memory.

[0057] Next, the control device 11 calculates the absolute value of the difference between a predetermined reference pressure and the measured pressure as the pressure difference, and determines whether this pressure difference is less than the predetermined pressure difference (step S51). This reference pressure is the atmospheric pressure corresponding to the reference pressure of the gas, and is the atmospheric pressure measured by the barometer 17 when the reference pressure of the gas is measured by the pressure gauge 13. The measured pressure is the atmospheric pressure corresponding to the measured pressure in the pressure measurement operation of step S16, and is the atmospheric pressure measured in the pressure measurement operation of step S50 that was executed together with the pressure measurement operation when the gas pressure was measured in the pressure measurement operation.

[0058] Then, the control device 11 determines whether the pressure difference is less than a predetermined pressure difference (step S51). If the control device 11 determines that the pressure difference is less than the predetermined pressure difference (step S51: YES), the change in atmospheric pressure during the gas pressure measurement operation is small. Therefore, the control device 11 executes the processing from step S17 onwards. In this way, when the influence of the change in atmospheric pressure on the change in gas pressure is small, the control device 11 determines the possibility of a gas leak based on the gas pressure difference, and therefore can more accurately determine the possibility of a gas leak.

[0059] On the other hand, if the control device 11 determines that the pressure difference is equal to or greater than the predetermined pressure difference (step S51: NO), the change in atmospheric pressure during the gas pressure measurement operation is large. In this case, the change in atmospheric pressure has a large effect on the gas pressure change during the pressure measurement operation. Therefore, the control device 11 cannot determine the possibility of a gas leak based on the gas pressure difference during the pressure measurement operation. Therefore, the control device 11 determines whether the measurement time in the second measurement operation of step S15 has reached a predetermined time, for example, three minutes (step S52). If this measurement time has not reached the predetermined time (step S52: NO), the control device 11 returns to the processing of step S16 and repeats the subsequent processing. As a result, the control device 11 measures the gas pressure and atmospheric pressure at predetermined time intervals.

[0060] On the other hand, if the pressure difference is equal to or greater than the predetermined pressure difference (step S51: NO) and the measurement time reaches the predetermined time (step S52: YES), the control device 11 determines that the influence of changes in atmospheric pressure on the gas pressure difference is large and it is not possible to determine the possibility of a gas leak based on the gas pressure difference. Therefore, as shown in the example of Figure 7A, the control device 11 displays the determination result on the display device 14 as "The change in atmospheric pressure is large and gas leak detection is impossible."

[0061] <Modification 2> In the above-described modification 1, the control device 11 determines in the gas leak determination operation that there is a possibility of a gas leak if the pressure difference obtained by subtracting the pressure measured in the pressure measurement operation from a predetermined reference pressure is equal to or greater than the predetermined pressure difference, and if the pressure difference, which is the absolute value of the difference between the atmospheric pressure measured in the pressure measurement operation and the predetermined reference pressure, is less than the predetermined pressure difference. In contrast, in modification 2, the control device 11 may determine in the gas leak determination operation that there is a possibility of a gas leak if the difference obtained by subtracting the total pressure obtained by adding the pressure measured in the pressure measurement operation to the atmospheric pressure measured in the pressure measurement operation from the predetermined reference total pressure is equal to or greater than a first predetermined difference.

[0062] In this case, the control device 11 executes the gas leak detection process in accordance with the flowchart shown in Fig. 8. In the flowchart of Fig. 8, the process of step S54 is executed instead of steps S17 and S51 to S53 of Fig. 6.

[0063] In the pressure measurement operation in step S16 of Fig. 8, the control device 11 measures the gas pressure in the gas pipe 20 using the pressure gauge 13 while the gas pipe 20 is shut off by the on-off valve 24. In addition, in the air pressure measurement operation in step S50, the control device 11 measures the atmospheric pressure at the time of measuring the gas pressure using the barometer 17. Then, the control device 11 adds the gas pressure measured in the pressure measurement operation to the atmospheric pressure measured in the air pressure measurement operation to calculate the total pressure of these. If this gas pressure is a relative pressure based on atmospheric pressure, the total pressure corresponds to the absolute pressure of the gas.

[0064] Therefore, the control device 11 calculates the difference obtained by subtracting the calculated total pressure from a predetermined reference total pressure as a total pressure difference, and determines whether this total pressure difference is less than a first predetermined difference (step S54). Here, if the total pressure difference is less than the first predetermined difference (step S54: YES), the control device 11 determines that even if the gas pipe 20 is shut off by the on-off valve 24, the absolute pressure of the gas has not dropped or has hardly dropped from the reference total pressure. Therefore, the control device 11 determines that there is no possibility of gas leakage from the gas pipe 20 and the gas appliance 21.

[0065] On the other hand, if the total pressure difference is equal to or greater than the first predetermined difference (step S54: NO), the absolute pressure of the gas has dropped significantly from the reference total pressure due to the blocking of the gas pipe 20 by the on-off valve 24. Therefore, the control device 11 determines that there is a possibility of gas leakage in the gas pipe 20 and the gas appliance 21.

[0066] <Modification 3> In Modification 3 of the present disclosure, in Embodiments 1 to 3 and Modification 1, the gas leak detection device 10 further includes a thermometer 18 that measures temperature, as shown in Fig. 1. The thermometer 18 is provided in the gas pipe 20, measures the temperature of the gas in the gas pipe 20, and outputs the measured temperature to the control device 11.

[0067] In this case, the control device 11 executes the gas leak detection process according to the example flowchart shown in Fig. 9. In the flowchart of Fig. 9, the processes of steps S60 to S63 are executed after the process of step S16 in the flowchart of Fig. 2. Note that the processes of steps S60 to S63 may also be executed after the process of step S16 in the flowcharts of Fig. 4 to Fig. 6. In the case of Fig. 4, the gas pipe 20 is shut off and opened by the shutoff valve 12 instead of the on-off valve 24.

[0068] 9, the control device 11 executes a pressure measurement operation (step S16), and measures the gas pressure in the gas pipe 20 with the pressure gauge 13 while the gas pipe 20 is shut off by the on-off valve 24. However, the gas pressure may be affected by the gas temperature. For this reason, the control device 11 executes a pressure measurement operation to measure the gas pressure with the pressure gauge 13 and a temperature measurement operation to measure the temperature with the thermometer 18 (step S60). As a result, the temperature at the time of measuring the gas pressure is measured, and these are stored in association with each other in memory.

[0069] Next, the control device 11 calculates the absolute value of the difference between the reference temperature and the measured temperature as the temperature difference, and determines whether this temperature difference is less than a predetermined temperature difference (step S61). This reference temperature is a temperature corresponding to the reference pressure of the gas, and is the temperature measured by the thermometer 18 when the reference pressure of the gas is measured by the pressure gauge 13. The measured temperature is a temperature corresponding to the measured pressure in the pressure measurement operation of step S16, and is the temperature measured in the temperature measurement operation of step S60, which was executed together with the pressure measurement operation when the gas pressure was measured in the pressure measurement operation.

[0070] Then, the control device 11 determines whether the temperature difference is less than a predetermined temperature difference (step S61). If the control device 11 determines that the temperature difference is less than the predetermined temperature difference (step S61: YES), the change in gas temperature during the gas pressure measurement operation is small. Therefore, the control device 11 executes the processes from step S17 onwards. In this way, when the effect of temperature change on gas pressure change is small, the possibility of a gas leak is determined based on the gas pressure difference, so the possibility of a gas leak can be determined more accurately.

[0071] On the other hand, if the control device 11 determines that the temperature difference is equal to or greater than the predetermined temperature difference (step S61: NO), the temperature change during the gas pressure measurement operation is large. In this case, the gas temperature change has a large effect on the gas pressure change during the pressure measurement operation. Therefore, the control device 11 cannot determine the possibility of a gas leak based on the gas pressure difference due to the pressure measurement operation. Therefore, the control device 11 determines whether the measurement time in the second measurement operation of step S15 has reached a predetermined time, for example, three minutes (step S62). If this measurement time has not reached the predetermined time (step S62: NO), the control device 11 returns to the processing of step S16 and repeats the subsequent processing. As a result, the control device 11 measures the gas pressure and temperature at predetermined time intervals.

[0072] On the other hand, if the temperature difference is equal to or greater than the predetermined temperature difference (step S61: NO) and the measurement time reaches the predetermined time (step S62: YES), the control device 11 determines that the influence of the gas temperature change on the gas pressure difference is large and it is not possible to determine the possibility of a gas leak based on the gas pressure difference. Therefore, as shown in the example of Figure 7A, the control device 11 displays the determination result on the display device 14 as "Temperature change is large, gas leak detection is impossible."

[0073] <Modification 4> In the above-described modification 3, the control device 11 determines in the gas leak determination operation that there is a possibility of a gas leak if the pressure difference obtained by subtracting the pressure measured in the pressure measurement operation from the predetermined reference pressure is equal to or greater than the predetermined pressure difference, and if the temperature difference, which is the absolute value of the difference between the temperature measured in the temperature measurement operation and the predetermined reference temperature, is less than the predetermined temperature difference. In contrast, in modification 4, the control device 11 may determine in the gas leak determination operation that there is a possibility of a gas leak if the difference obtained by subtracting the corrected pressure obtained by correcting the pressure measured in the pressure measurement operation by the temperature measured in the temperature measurement operation from the predetermined reference corrected pressure is equal to or greater than a second predetermined difference.

[0074] In this case, the control device 11 executes the gas leak detection process in accordance with the flowchart shown in Fig. 10. In the flowchart of Fig. 10, the process of step S64 is executed instead of steps S17 and S61 to S63 of Fig. 9.

[0075] 10 , the control device 11 measures the gas pressure in the gas pipe 20 using the pressure gauge 13 while the gas pipe 20 is shut off by the on-off valve 24. Furthermore, in the temperature measurement operation in step S60, the control device 11 measures the gas temperature using the thermometer 18 while measuring the gas pressure. The control device 11 then corrects the gas pressure measured in the pressure measurement operation by the temperature measured in the temperature measurement operation, and acquires the gas pressure at a predetermined temperature (e.g., 0 degrees) as the corrected pressure. The relationship between this corrected pressure, the gas pressure, and the gas temperature is predetermined and stored in memory.

[0076] Next, the control device 11 calculates the difference between the acquired corrected pressure and a predetermined reference corrected pressure, and determines whether this difference in corrected pressure is less than a second predetermined difference (step S64). This base corrected pressure is the gas pressure at a predetermined temperature (e.g., 0 degrees) and is predetermined and stored in memory. If the difference in corrected pressure is less than the second predetermined difference (step S64: YES), the control device 11 determines that even if the gas pipe 20 is shut off by the on-off valve 24, the corrected gas pressure has not dropped or has barely dropped from the reference corrected pressure. Therefore, the control device 11 determines that there is no possibility of gas leakage from the gas pipe 20 and the gas appliance 21.

[0077] On the other hand, if the difference obtained by subtracting the acquired corrected pressure from the reference corrected pressure is equal to or greater than the second predetermined difference (step S64: NO), the control device 11 determines that the corrected pressure of the gas has dropped significantly from the reference corrected pressure due to the blocking of the gas piping 20 by the on-off valve 24. Therefore, the control device 11 determines that there is a possibility of gas leakage in the gas piping 20 and the gas appliance 21.

[0078] <Modification 5> In all of the above-described embodiments and modifications, the gas leak detection device 10 is configured as a single unit, as shown in the example of Fig. 1. However, as shown in the example of Fig. 11, the gas leak detection device 10 may be configured with multiple devices (e.g., a first device 10a and a second device 10b).

[0079] The first device 10a is provided on the gas piping 20 between the on-off valve 24 and the gas appliance 21, and for example, a gas meter 22 is used as the first device 10a. The first device 10a includes a first control device 11a, a shutoff valve 12, a pressure gauge 13, a thermometer 18, a flow meter 25, and a first communication interface 15a, which are electrically connected to the first control device 11a. The first communication interface 15a transmits and receives information to and from an external device and the second device 10b via wireless communication or wired communication.

[0080] The second device 10b is capable of communicating with the first device 10a, is not provided on the gas pipe 20, and may be, for example, a user's mobile terminal. The second control device 11b includes the second control device 11b, as well as a barometer 17, a display device 14, an input device 16, and a second communication interface 15b, which are electrically connected to the second control device 11b. The second communication interface 15b transmits and receives information between an external device and the first communication interface 15a of the first device 10a via wireless communication or wired communication.

[0081] When a mobile terminal is used as the second device 10b, the second communication interface 15b may be used as the barometer 17. In this case, the second control device 11b may obtain information about atmospheric pressure, such as weather information, at the location of the first device 10a via the second communication interface 15b, and obtain the atmospheric pressure at the first device 10a based on this information about atmospheric pressure. The relationship between this information about atmospheric pressure and the atmospheric pressure is predetermined and stored in the memory of the second control device 11b.

[0082] The control device 11 of the gas leak detection device 10 has a first control device 11a of the first device 10a and a second control device 11b of the second device 10b. The first control device 11a is a computer that controls the electrical equipment of the first device 10a, and is exemplified by a microcontroller, for example. The second control device 11b is a computer that controls the electrical equipment of the second device 10b, and is exemplified by a microcontroller, for example. The first control device 11a and the second control device 11b cooperate to execute the gas leak detection process.

[0083] <Gas Leak Detection Process> The second control device 11b executes the gas leak detection process in accordance with the flowchart shown in Fig. 12. In the flowchart of Fig. 12, step S11' is executed instead of step S11 in Fig. 2, and a pressure acquisition operation of step S16' is executed instead of the pressure measurement operation of step S16 in Fig. 2.

[0084] Specifically, the second control device 11b receives an instruction to start the gas leak detection process via the input device 16 (step S10: YES) and determines whether the shutoff valve 12 is in an open state (step S11′). The shutoff valve 12 is controlled to close and open by the first control device 11a, and the control details are stored in memory. Therefore, the second control device 11b transmits an instruction to acquire the control details of the shutoff valve 12 to the first device 10a via the second communication interface 15b. In response to the acquisition instruction, the first control device 11a transmits the control details to the second device 10b via the first communication interface 15a. The second control device 11b determines whether the shutoff valve 12 is in an open state based on the control details. Here, if the shutoff valve 12 is in a closed state (step S11′: NO), the second control device 11b terminates the gas leak detection process.

[0085] On the other hand, if the shutoff valve 12 is in an open state (step S11': YES), a guide display operation is executed to display guide information for closing the on-off valve 24 on the display device 14 (step S12). Based on this guide information, the user closes the on-off valve 24, and the on-off valve 24 shuts off the gas pipe 20. Furthermore, the second control device 11b executes a first timing operation (step S13), and when a first predetermined time has elapsed (step S14: YES), executes a second timing operation (step S15).

[0086] Next, the second control device 11b executes a pressure acquisition operation to acquire the gas pressure measured by the pressure gauge 13 from the first device 10a (step S16'). Here, to acquire the gas pressure from the first device 10a, the second control device 11b transmits a pressure acquisition instruction to the first device 10a via the second communication interface 15b. In response, the first control device 11a receives the pressure acquisition instruction via the first communication interface 15a and executes the pressure measurement operation in accordance with the pressure acquisition instruction. Then, the first control device 11a measures the gas pressure using the pressure gauge 13 in the pressure measurement operation and transmits the measured pressure signal to the second device 10b via the first communication interface 15a. In this way, the second control device 11b acquires the gas pressure measured in the pressure measurement operation from the second device 10b.

[0087] Next, the second control device 11b executes a gas leak determination operation to determine the possibility of a gas leak based on the gas pressure measured in the pressure measurement operation (step S17). Here, the second control device 11b calculates the difference by subtracting the gas pressure measured in the pressure measurement operation from a predetermined reference pressure, and if this pressure difference is equal to or greater than the predetermined pressure difference (step S17: NO), it determines that there is a possibility of a gas leak. On the other hand, if the pressure difference is less than the predetermined pressure difference (step S17: YES) and the measurement time reaches a predetermined time (step S18: YES), the second control device 11b determines that there is no possibility of a gas leak.

[0088] <Modification 6> When the gas leak detection process is performed by the gas leak detection device 10 including the first device 10a and the second device 10b in the second embodiment, the second device 10b performs the process according to the flowchart shown in Fig. 13. In the flowchart of Fig. 13, steps S11', S16', S30', and S31' are performed instead of steps S11, S16, S30, and S31 in Fig. 4.

[0089] As described above, the shutoff valve 12 is controlled to be closed or opened by the first control device 11a. Therefore, in step S30', the second control device 11b transmits a valve closing instruction for the shutoff valve 12 to the first device 10a. In response to this, the first control device 11a executes valve closing control for the shutoff valve 12 in accordance with the valve closing instruction, and shuts off the gas pipe 20 with the shutoff valve 12. The first control device 11a then transmits a response indicating that it has performed valve closing control for the shutoff valve 12 to the second device 10b. The second control device 11b executes the processing from step S15 onwards based on this response.

[0090] Also, in the processing of step S31', similar to the processing of step S30', the second control device 11b transmits an instruction to open the shutoff valve 12 to the first device 10a. In response to this, the first control device 11a executes valve opening control of the shutoff valve 12 in accordance with the valve opening instruction, and opens the gas piping 20. Then, the first control device 11a transmits a response to the execution of valve opening control of the shutoff valve 12 to the second device 10b. The second control device 11b ends the gas leak detection processing based on this response.

[0091] <Variation 7> When the gas leak detection process is performed by the gas leak detection device 10 including the first device 10a and the second device 10b in the third embodiment, the second device 10b performs the process according to the flowchart shown in the example of Fig. 14. In the flowchart of Fig. 14, steps S11', S16', and S40' are performed instead of steps S11, S16, and S40 of Fig. 5.

[0092] In step S40', the second control device 11b executes a flow rate acquisition operation to acquire from the first device 10a the gas flow rate measured by the flowmeter 25 in the flow rate measurement operation. Here, the second control device 11b transmits a flow rate acquisition instruction to the first device 10a to acquire the gas flow rate from the first device 10a. In response, the first control device 11a receives the flow rate acquisition instruction and executes the flow rate measurement operation in accordance with the flow rate acquisition instruction. Then, the first control device 11a measures the gas flow rate using the flowmeter 25 in the flow rate measurement operation and transmits the measured value to the second device 10b. In this way, the second control device 11b acquires the gas flow rate measured in the flow rate measurement operation from the second device 10b.

[0093] <Modification 8> When the gas leak detection process is performed by the gas leak detection device 10 including the first device 10a and the second device 10b in Modification 1, the second device 10b performs the process according to the flowchart shown in the example of Fig. 15. In the flowchart of Fig. 15, steps S11' and S16' are performed instead of steps S11 and S16 of Fig. 6. Note that when the barometer 17 is controlled by the second control device 11b, the second control device 11b performs a barometric pressure measurement operation to measure atmospheric pressure with the barometer 17 (step S50).

[0094] In addition, when the gas leak detection process is performed by the gas leak detection device 10 including the first device 10a and the second device 10b in Modification 2, the second device 10b performs the process according to the flowchart shown in the example of Fig. 8. However, steps S11' and S16' are performed instead of steps S11 and S16 in Fig. 8.

[0095] <Modification 9> When the gas leak detection process is performed by the gas leak detection device 10 including the first device 10a and the second device 10b in Modification 3, the second device 10b performs the process according to the flowchart shown in the example of Fig. 16. In the flowchart of Fig. 16, steps S11', S16', and S60' are performed instead of steps S11, S16, and S60 in Fig. 9.

[0096] In step S60', the second control device 11b executes a temperature acquisition operation to acquire from the first device 10a the gas temperature measured by the thermometer 18 in the temperature measurement operation. Here, the second control device 11b transmits a temperature acquisition instruction to the first device 10a to acquire the gas temperature from the first device 10a. In response, the first control device 11a receives the temperature acquisition instruction and executes the temperature measurement operation in accordance with the temperature acquisition instruction. Then, the first control device 11a measures the gas temperature using the thermometer 18 in the temperature measurement operation and transmits the measured gas temperature to the second device 10b. In this way, the second control device 11b acquires the gas temperature measured in the temperature measurement operation from the second device 10b.

[0097] In addition, when the gas leak detection process is performed by the gas leak detection device 10 including the first device 10a and the second device 10b in Modification 4, the second device 10b performs the process according to the flowchart shown in the example of Fig. 10. However, steps S11', S16', and S60' are executed instead of steps S11, S16, and S60 in Fig. 10, respectively.

[0098] <Other Modifications> In all the above embodiments and modifications, the shutoff valve 12 was provided in the gas piping 20 upstream of the pressure gauge 13. However, if the gas piping 20 is shut off and opened by the on-off valve 24, the shutoff valve 12 may be provided in the gas piping 20 downstream of the pressure gauge 13. Even in such a case, the pressure gauge 13 is provided in the gas piping 20 between the on-off valve 24 and the gas appliance 21. As a result, the control device 11 can measure the gas pressure in the gas piping 20 using the pressure gauge 13 when gas is not being supplied to the gas piping 20 and the gas appliance 21 downstream of the on-off valve 24, and determine the possibility of a gas leak based on this pressure.

[0099] In all of the above-described embodiments and modifications, the gas leak detection device 10 includes the display device 14 as an output device. However, the output device is not limited to this. For example, the gas leak detection device 10 may include a speaker that emits sound and a light source that emits light, such as an LED, as output devices. The driving of these is controlled by the control device 11. Such sound and light can be used to output guide information and determination results for the guide output operation in the gas leak detection process.

[0100] It should be noted that all of the above embodiments may be combined with each other as long as they do not exclude each other. From the above description, many improvements and other embodiments of the present disclosure will be apparent to those skilled in the art. Therefore, the above description should be construed as merely illustrative and is provided for the purpose of teaching those skilled in the art the best mode for carrying out the present disclosure. Details of the structure and / or function thereof may be substantially changed without departing from the spirit of the present disclosure.

[0101] <Addendum> The above description of the embodiments discloses the following technologies: A first technology is a gas leak detection device that is arranged in a gas pipe that supplies gas to a gas appliance and is provided with an on-off valve, the gas leak detection device comprising: a pressure gauge that measures the pressure of the gas in the gas pipe downstream of the on-off valve, an output device that outputs information, and a control device, wherein the control device executes a guide output operation that outputs guide information to close the on-off valve to the output device, executes a pressure measurement operation that measures the pressure using the pressure gauge after executing the guide output operation, and executes a gas leak determination operation that determines the possibility of a gas leak based on the pressure measured in the pressure measurement operation.

[0102] According to this configuration, the user closes the on-off valve in accordance with the guide information output to the output device, thereby shutting off the gas piping with the on-off valve in accordance with the user's intention, and the possibility of a gas leak can be determined based on the gas pressure in the gas piping.

[0103] A second technology is the gas leak detection device described in Technology 1, which further includes an input device for inputting information, and the control device executes the guidance output operation when a start instruction is input by the input device.

[0104] According to this configuration, when a user operates the input device to input a start command to the control device, a guide output is output in response to the start command. In response to the guide output in line with the user's intention, the gas piping is shut off by the on-off valve, and the possibility of a gas leak can be determined based on the gas pressure in the gas piping.

[0105] A third technology is a gas leak detection device according to technology 1 or 2, which includes a barometer that measures atmospheric pressure, and the pressure gauge measures a relative pressure, which is the pressure of the gas with atmospheric pressure as a predetermined reference pressure. After the guide output operation is performed, the control device performs the pressure measurement operation and a barometric pressure measurement operation that measures the atmospheric pressure using the barometer. If the pressure difference obtained by subtracting the pressure measured in the pressure measurement operation from the predetermined reference pressure is equal to or greater than the predetermined pressure difference and the barometric pressure difference, which is the absolute value of the difference between the atmospheric pressure measured in the barometric pressure measurement operation and the predetermined reference barometric pressure, is less than the predetermined barometric pressure difference, or if the difference obtained by subtracting the total pressure obtained by adding the pressure measured in the pressure measurement operation to the atmospheric pressure measured in the barometric pressure measurement operation from a predetermined reference total pressure is equal to or greater than a first predetermined difference, the gas leak detection device determines that there is a possibility of a gas leak in the gas leak determination operation.

[0106] According to this configuration, when the pressure difference with the atmospheric pressure is small, the influence of the pressure difference with the atmospheric pressure on the gas pressure difference is small. In such a case, the possibility of a gas leak can be determined more accurately based on the gas pressure. Furthermore, the sum of the pressure measured in the pressure measurement operation and the atmospheric pressure measured in the air pressure measurement operation corresponds to the absolute pressure of the gas. The possibility of a gas leak can be determined more accurately based on this absolute pressure.

[0107] A fourth technology is a gas leak detection device according to any one of technologies 1 to 3, which includes a thermometer that measures temperature, and the control device executes the pressure measurement operation and a temperature measurement operation that measures the temperature using the thermometer after executing the guide output operation, and determines that there is a possibility of a gas leak in the gas leak determination operation if the pressure difference obtained by subtracting the pressure measured in the pressure measurement operation from a predetermined reference pressure is equal to or greater than the predetermined pressure difference, and if the temperature difference, which is the absolute value of the difference between the temperature measured in the temperature measurement operation and the predetermined reference temperature, is less than the predetermined temperature difference, or if the difference obtained by subtracting the corrected pressure obtained by correcting the pressure measured in the pressure measurement operation by the temperature measured in the temperature measurement operation from a predetermined reference corrected pressure is equal to or greater than a second predetermined difference.

[0108] According to this configuration, when the gas temperature difference is small, the influence of the gas temperature difference on the gas pressure difference is small. In such a case, the possibility of a gas leak can be determined more accurately based on the gas pressure. Furthermore, by correcting the gas pressure based on the temperature, the influence of temperature can be suppressed, and the possibility of a gas leak can be determined more accurately based on the corrected gas pressure.

[0109] The fifth technology is a gas leak detection device that is placed in a gas pipe that supplies gas to a gas appliance, and that includes a shut-off valve that shuts off the gas pipe, a pressure gauge that measures the gas pressure in the gas pipe downstream of the shut-off valve, an output device that outputs information, an input device that inputs information, and a control device, wherein when a start instruction is input by the input device, the control device performs a shut-off operation to shut off the gas pipe using the shut-off valve, performs a pressure measurement operation to measure the pressure using the pressure gauge after the shut-off operation has been performed, and performs a gas leak determination operation to determine the possibility of a gas leak based on the pressure measured in the pressure measurement operation.

[0110] According to this configuration, when a user operates the input device to input a start command to the control device, the shutoff valve is controlled to close in accordance with the start command. In response to such a start command that is in line with the user's intention, the shutoff valve shuts off the gas piping, and the possibility of a gas leak can be determined based on the gas pressure in the gas piping.

[0111] A sixth technology is a gas leak detection device according to technology 5, which includes a barometer that measures atmospheric pressure, and the pressure gauge measures relative pressure, which is the pressure of the gas with atmospheric pressure as a predetermined reference pressure; after the shut-off operation is performed, the control device performs the pressure measurement operation and an air pressure measurement operation that measures atmospheric pressure using the barometer; and if the pressure difference obtained by subtracting the pressure measured in the pressure measurement operation from the predetermined reference pressure is equal to or greater than the predetermined pressure difference, and if the air pressure difference, which is the absolute value of the difference between the atmospheric pressure measured in the air pressure measurement operation and the predetermined reference air pressure, is less than the predetermined air pressure difference, the gas leak detection operation determines that there is a possibility of a gas leak.

[0112] According to this configuration, when the pressure difference with respect to the atmosphere is small, the influence of the pressure difference with respect to the gas pressure is small, and in such a case, the possibility of a gas leak can be determined more accurately based on the gas pressure.

[0113] A seventh technology is a gas leak detection device according to Technology 5 or 6, which includes a thermometer that measures temperature, and the control device executes the pressure measurement operation and a temperature measurement operation that measures temperature using the thermometer after executing the shut-off operation, and if the pressure difference obtained by subtracting the pressure measured in the pressure measurement operation from a predetermined reference pressure is equal to or greater than the predetermined pressure difference, and if the temperature difference, which is the absolute value of the difference between the temperature measured in the temperature measurement operation and the predetermined reference temperature, is less than the predetermined temperature difference, determines that there is a possibility of a gas leak in the gas leak determination operation.

[0114] According to this configuration, when the gas temperature difference is small, the effect of the gas temperature difference on the gas pressure is small, and in such a case, the possibility of a gas leak can be determined more accurately based on the gas pressure.

[0115] The eighth technology is a gas meter comprising a gas leak detection device according to any one of technologies 1 to 7 and a flow meter that measures the flow rate of gas in the gas pipe, wherein the control device, when performing the pressure measurement operation, performs a flow rate measurement operation to measure the flow rate using the flow meter, and, when the pressure difference obtained by subtracting the pressure measured in the pressure measurement operation from a predetermined reference pressure is less than a predetermined pressure difference, performs an acquisition operation to acquire a correction value of the flow rate based on the flow rate measured in the flow rate measurement operation.

[0116] According to this configuration, when the gas piping is blocked by an on-off valve or a shut-off valve, the possibility of a gas leak can be determined based on the gas pressure, and a flow rate correction value can be obtained based on the gas flow rate.

[0117] A ninth technology is a gas leak detection device according to any one of technologies 1 to 8, which includes a first device that supplies gas to a gas appliance and is arranged in a gas pipe that is provided with an on-off valve and has the pressure gauge, and a second device that is capable of communicating with the first device and has the output device, wherein the control device has a first control device of the first device and a second control device of the second device, the first control device performs the pressure measurement operation, and the second control device performs the pressure acquisition operation that acquires the pressure measured by the pressure measurement operation, the guide output operation, and the gas leak determination operation.

[0118] According to this configuration, a user can determine the possibility of a gas leak using the second device at a location separate from the first device. Furthermore, if a gas meter with a pressure gauge is used as the first device, the pressure measurement operation can be performed using the pressure gauge of the gas meter without the cost of providing a separate pressure gauge. Furthermore, if a user's mobile device is used as the second device, the guidance output operation can be performed using the output device of the mobile device without the cost of providing a separate output device.

[0119] 10: Gas leak detection device 11: Control device 12: Shutoff valve 13: Pressure gauge 14: Display device (output device) 16: Input device 17: Barometer 18: Thermometer 20: Gas pipe 21: Gas appliance 22: Gas meter 24: On-off valve 25: Flow meter

Claims

1. A gas leak detection device that is placed in a gas pipe that supplies gas to a gas appliance and is equipped with an on-off valve, comprising: a pressure gauge that measures the gas pressure in the gas pipe downstream of the on-off valve; an output device that outputs information; and a control device, wherein the control device performs a guide output operation that outputs guide information to the output device to close the on-off valve, performs a pressure measurement operation that measures the pressure using the pressure gauge after performing the guide output operation, and performs a gas leak determination operation that determines the possibility of a gas leak based on the pressure measured in the pressure measurement operation.

2. A gas leak detection device according to claim 1, further comprising an input device for inputting information, wherein the control device executes the guidance output operation when a start instruction is input via the input device.

3. A gas leak detection device according to claim 1, comprising a barometer that measures atmospheric pressure, wherein the pressure gauge measures relative pressure, which is the pressure of the gas based on atmospheric pressure, and wherein the control device, after executing the guide output operation, executes the pressure measurement operation and an air pressure measurement operation that measures the atmospheric pressure using the barometer, and determines in the gas leak determination operation that there is a possibility of a gas leak if the pressure difference obtained by subtracting the pressure measured in the pressure measurement operation from a predetermined reference pressure is equal to or greater than the predetermined pressure difference and the air pressure difference, which is the absolute value of the difference between the atmospheric pressure measured in the air pressure measurement operation and the predetermined reference air pressure, is less than the predetermined air pressure difference, or if the difference obtained by subtracting the total pressure obtained by adding the pressure measured in the pressure measurement operation to the atmospheric pressure measured in the air pressure measurement operation, from a predetermined reference total pressure is equal to or greater than a first predetermined difference.

4. A gas leak detection device as described in claim 1, comprising a thermometer for measuring temperature, wherein the control device executes the pressure measurement operation and a temperature measurement operation for measuring temperature using the thermometer after executing the guide output operation, and determines in the gas leak determination operation that there is a possibility of a gas leak if the pressure difference obtained by subtracting the pressure measured in the pressure measurement operation from a predetermined reference pressure is equal to or greater than the predetermined pressure difference and the temperature difference, which is the absolute value of the difference between the temperature measured in the temperature measurement operation and the predetermined reference temperature, is less than the predetermined temperature difference, or if the difference obtained by subtracting the corrected pressure obtained by correcting the pressure measured in the pressure measurement operation by the temperature measured in the temperature measurement operation from a predetermined reference corrected pressure is equal to or greater than a second predetermined difference.

5. A gas leak detection device to be placed in a gas pipe that supplies gas to a gas appliance, comprising: a shutoff valve that shuts off the gas pipe; a pressure gauge that measures the pressure of gas in the gas pipe downstream of the shutoff valve; an output device that outputs information; an input device that inputs information; and a control device, wherein when a start command is input by the input device, the control device performs a shutoff operation to shut off the gas pipe by the shutoff valve, performs a pressure measurement operation to measure the pressure by the pressure gauge after the shutoff operation has been performed, and performs a gas leak determination operation to determine the possibility of a gas leak based on the pressure measured in the pressure measurement operation.

6. A gas leak detection device according to claim 5, comprising a barometer that measures atmospheric pressure, wherein the pressure gauge measures a relative pressure that is the pressure of the gas based on atmospheric pressure, and wherein the control device, after performing the shut-off operation, performs the pressure measurement operation and a barometric pressure measurement operation that measures the atmospheric pressure using the barometer, and determines that there is a possibility of a gas leak in the gas leak determination operation if the pressure difference obtained by subtracting the pressure measured in the pressure measurement operation from a predetermined reference pressure is equal to or greater than the predetermined pressure difference, and if the pressure difference, which is the absolute value of the difference between the atmospheric pressure measured in the barometric pressure measurement operation and the predetermined reference pressure, is less than the predetermined pressure difference.

7. A gas leak detection device as described in claim 5, further comprising a thermometer for measuring temperature, wherein the control device, after performing the shut-off operation, performs the pressure measurement operation and a temperature measurement operation for measuring temperature using the thermometer, and determines that there is a possibility of a gas leak in the gas leak determination operation if the pressure difference obtained by subtracting the pressure measured in the pressure measurement operation from a predetermined reference pressure is equal to or greater than the predetermined pressure difference, and if the temperature difference, which is the absolute value of the difference between the temperature measured in the temperature measurement operation and the predetermined reference temperature, is less than the predetermined temperature difference.

8. A gas meter comprising: a gas leak detection device according to any one of claims 1 to 7; and a flow meter that measures the flow rate of gas in the gas piping, wherein the control device, when performing the pressure measurement operation, performs a flow rate measurement operation that measures the flow rate using the flow meter; and, when the pressure difference obtained by subtracting the pressure measured in the pressure measurement operation from a predetermined reference pressure is less than the predetermined pressure difference, performs an acquisition operation that acquires a correction value for the flow rate based on the flow rate measured in the flow rate measurement operation.

9. A gas leak detection device as described in claim 1, comprising: a first device that supplies gas to a gas appliance and is arranged in a gas pipe that is provided with an on-off valve and that has the pressure gauge; and a second device that is capable of communicating with the first device and that has the output device, wherein the control devices include a first control device for the first device and a second control device for the second device, wherein the first control device performs the pressure measurement operation, and the second control device performs a pressure acquisition operation that acquires the pressure measured by the pressure measurement operation, the guide output operation, and the gas leak determination operation.

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