Gas meter

Abstract

A gas meter according to the present invention comprises: a flow rate meter for measuring the flow rate of a gas flowing through a gas pipe; a pressure gauge for measuring the pressure of the gas in the gas pipe; and a control device. On the basis of a correlation coefficient between the flow rate of the gas as measured by the flow rate meter and the pressure of the gas as measured by the pressure gauge, the control device executes a water ingress determination operation for determining the ingress of water in which water enters the gas pipe, and / or a pulsation determination operation for determining a pulsation that causes the flow rate of gas in the gas pipe to fluctuate.

Description

Gas meter

[0001] The present disclosure relates to a gas meter that detects water intrusion into a gas pipe.

[0002] A known example of a conventional gas meter is the gas meter disclosed in Patent Document 1. This gas meter detects the pressure of gas flowing through a flow path, and if this pressure drops, it determines that water has accumulated in the gas pipe.

[0003] JP 2011-27712 A

[0004] Conventional gas meters detect water intrusion into gas pipes based on a drop in gas pressure. However, because gas pressure in gas pipes is affected by not only water intrusion but also other factors, there is a problem in that it is difficult to accurately detect water intrusion into gas pipes. In addition, gas pulsations can occur in gas pipes, and there are cases where it is necessary to accurately detect these pulsations.

[0005] The present disclosure has been made to solve such problems, and aims to provide a gas meter that can accurately determine at least one of water intrusion into gas piping and gas pulsation.

[0006] A gas meter according to one aspect of the present disclosure includes a flow meter that measures the flow rate of gas flowing through a gas pipe, a pressure meter that measures the pressure of the gas in the gas pipe, and a control device, and the control device performs at least one of a water flooding determination operation that determines water flooding, that is, water intrusion into the gas pipe, and a pulsation determination operation that determines pulsation, that is, fluctuations in the gas flow rate in the gas pipe, based on a correlation coefficient between the gas flow rate measured by the flow meter and the gas pressure measured by the pressure meter.

[0007] In such gas meters, a correlation coefficient between the gas flow rate and pressure is used to determine at least one of whether the gas pipe is flooded or whether the gas pulsation in the gas pipe is present. When such a correlation coefficient is used for the determination, the accuracy of the determination can be improved compared to when only the gas pressure is used for the determination.

[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] 1 is a functional block diagram schematically illustrating a configuration of a gas meter according to an embodiment 1 of the present disclosure. FIG. 2 is a flowchart illustrating an example of a process for detecting water ingress into a gas pipe of a gas meter according to a first modification of the present disclosure. FIG. 3 is a flowchart illustrating an example of a process for detecting water ingress into a gas pipe of a gas meter according to a first modification of the present disclosure. FIG. 4 is a flowchart illustrating an example of a process for detecting water ingress into a gas pipe of a gas meter according to a third modification of the present disclosure. FIG. 5 is a flowchart illustrating an example of a process for detecting water ingress into a gas pipe of a gas meter according to a fourth modification of the present disclosure. FIG. 6 is a flowchart illustrating an example of a process for detecting water ingress into a gas pipe of a gas meter according to a fifth modification of the present disclosure. FIG. 7 is a flowchart illustrating an example of a process for detecting gas pulsation in a gas pipe of a gas meter according to a sixth modification of the present disclosure. FIG. 8 is a flowchart illustrating an example of a process for detecting gas pulsation in a gas pipe of a gas meter according to a seventh modification of the present disclosure. FIG. 9 is a flowchart illustrating an example of a process for detecting gas pulsation in a gas pipe of a gas meter according to a ninth modification of the present disclosure. 20 is a flowchart showing an example of a process for detecting gas pulsation in a gas pipe of a gas meter according to a tenth modification of the present disclosure.

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

[0011] <Gas Meter> As shown in Fig. 1 , the gas meter 10 according to the present disclosure is provided on a gas pipe 20. The gas pipe 20 is a conduit connected between a gas supply source 21 and a gas appliance 22 of a gas consumer, and supplies gas from the gas supply source 21 to the gas appliance 22. The gas appliance 22 is a device that consumes gas, such as a gas stove, a water heater, or a heater.

[0012] The gas meter 10 includes a control device 11. The control device 11 is a computer that controls the electrical devices of the gas meter 10, 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 controls each part of the gas meter 10 by executing a program stored in the memory. In this way, the control device 11 executes various processes for the gas meter 10, such as a flow rate measurement process, a safety process, and a flood detection process. These processes will be described later.

[0013] Furthermore, the gas meter 10 is equipped with a shutoff valve 12. The shutoff valve 12 is provided in the gas pipe 20. The shutoff valve 12 is controlled by the control device 11 to open and close the gas pipe 20. In other words, 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 shut off to prevent gas from flowing through.

[0014] Furthermore, the gas meter 10 is equipped with a flow meter 13. The flow meter 13 is provided in the gas pipe 20, measures the volume or mass ((instantaneous) flow rate) of gas passing through the gas pipe 20 per unit time, and outputs the measured value to the control device 11.

[0015] Furthermore, the gas meter 10 is equipped with a pressure gauge 14. The pressure gauge 14 is provided in the gas pipe 20, measures the pressure of the gas in the gas pipe 20, and outputs the measured value to the control device 11. The gas pressure measured by this pressure gauge 14 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. Note that the gas pressure measured by the pressure gauge 14 may also be the absolute pressure of the gas.

[0016] The gas meter 10 further includes a display device 15 and a communication interface 16. The display device 15 is, for example, a liquid crystal display, and displays information under the control of the control device 11. The communication interface 16 transmits and receives information to and from an external device via wireless communication or wired communication. For example, the external device is a computer of a gas utility company that manages the gas pipe 20, a company that manages the gas meter 10, or the like.

[0017] Furthermore, the gas meter 10 is equipped with an input device 17. The input device 17 is, for example, a push button switch or the like, and is operated by a user to input information to the control device 11. User operations of the input device 17 and input information are associated in advance and stored in memory. If the input device 17 is a push button switch, a short press operation in which the user presses the push button switch for less than a predetermined time is associated in advance with a restoration instruction to open the gas pipe 20 from being shut off by the shutoff valve 12 and stored in memory. The input device 17 may include a communication interface 16. In this case, the communication interface 16 receives information from an external device and inputs the information to the control device 11.

[0018] <Flow rate measurement process> The control device 11 causes the flow meter 13 to measure the flow rate of gas flowing through the gas pipe 20 at a predetermined first flow rate measurement interval, for example, every two seconds. Then, the control device 11 integrates the gas flow rate measured by the flow meter 13 and outputs this integrated value as the gas consumption rate to the display device 15 or the communication interface 16. As a result, the gas consumption rate is displayed on the display device 15 to notify the user, or is transmitted to an external device via the communication interface 16 to notify the gas supplier or the like.

[0019] <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 14 to measure the gas pressure in the gas piping 20 at a predetermined first pressure measurement interval, for example, at 10-second intervals. 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 22, and the gas appliance 22 becomes unusable. The safety condition occurs, for example, when the gas flow rate increases to or exceeds a predetermined flow rate, and when the gas pressure decreases to or exceeds a predetermined pressure.

[0020] When the user briefly presses the push button switch, which is the input device 17, the control device 11 determines that a return instruction corresponding to the short press has been input. The control device 11 then executes valve opening control of the shutoff valve 12 in response to the return instruction, thereby opening the gas pipe 20. This allows gas to be supplied to the gas appliance 22, making the gas appliance 22 usable.

[0021] <Water Flood Detection Process> In the gas meter 10 according to the first embodiment of the present disclosure, the water flood detection process is executed by the control device 11 according to the flowchart shown in Fig. 2. First, the control device 11 determines whether a predetermined condition is met (step S10). The predetermined condition is a condition for starting the water flood detection process, and is determined in advance and stored in memory.

[0022] As described above, except when the measurement operation of the water flood detection process is being performed, the gas flow rate is measured by the flow meter 13 at a first flow rate measurement interval (e.g., every 2 seconds), and the gas pressure is measured by the pressure meter 14 at a first pressure measurement interval (e.g., every 10 seconds). The control device 11 acquires the measured gas flow rate and measured pressure and stores them in memory. The predetermined condition may be determined based on at least one of the measured gas flow rate and measured pressure.

[0023] For example, the predetermined condition includes a drop in gas pressure at the start of gas use. In this case, the control device 11 determines that gas use has started when the measured gas flow rate increases and the difference between the measured flow rates is equal to or greater than a predetermined flow rate. At the start of use, the control device 11 determines that the predetermined condition is met when the measured gas pressure decreases and the difference between the measured pressures is equal to or greater than a predetermined pressure (step S10: YES).

[0024] The predetermined condition may include, for example, an increase in the amplitude of the gas flow rate. In this case, the control device 11 acquires the absolute value of the difference between the measured gas flow rates as the flow rate amplitude at the first flow rate measurement interval for a predetermined time (for example, one minute). The control device 11 then integrates the flow rate amplitudes, and if the integrated value of the amplitudes is equal to or greater than the predetermined amplitude, determines that the predetermined condition is met (step S10: YES).

[0025] The predetermined condition may include, for example, an increase in the amplitude of the gas pressure. In this case, the control device 11 acquires the absolute value of the difference between the measured gas pressures as the pressure amplitude at the first pressure measurement interval for a predetermined time (for example, one minute). The control device 11 then integrates these pressure amplitudes, and if the integrated value of the amplitude is equal to or greater than the predetermined amplitude, determines that the predetermined condition is met (step S10: YES).

[0026] The predetermined condition may include, for example, a decrease in the average pressure of the gas. In this case, the control device 11 acquires the measured gas pressure at a first pressure measurement interval for a predetermined time (for example, one minute). The control device 11 then calculates the average value of these measured pressures as the average pressure, and if the average gas pressure is less than the predetermined pressure, determines that the predetermined condition is met (step S10: YES).

[0027] The predetermined condition is not limited to the condition based on the measured gas flow rate and pressure as described above. For example, the predetermined condition may be a start instruction input via the communication interface 16. In this case, the gas supplier transmits the start instruction for the water inundation detection process using an external device. In response, the control device 11 receives the start instruction from the external device via the communication interface 16 and determines that the predetermined condition is met (step S10: YES).

[0028] The predetermined condition may also be a start instruction input via the input device 17. For example, the instruction to start the water submersion detection process may be associated with a long press operation in which the user presses a push button switch, which is the input device 17, for a predetermined period of time or longer. In this case, when the user performs a long press operation, the control device 11 determines that the predetermined condition is met (step S10: YES).

[0029] Next, the control device 11 determines whether the determination period is less than a predetermined period, for example, 10 minutes (step S11). The determination period is, for example, the time that has elapsed since it was determined that the predetermined condition was met. If the determination period is less than the predetermined period (step S11: YES), the control device 11 executes a flow rate measurement operation (step S12) and a pressure measurement operation (step S13).

[0030] In the flow rate measurement operation, the control device 11 measures the gas flow rate using the flow meter 13 at a predetermined second flow rate measurement interval (e.g., 1 second interval) that is shorter than the first flow rate measurement interval, and stores the measured flow rate in memory. In the pressure measurement operation, the control device 11 measures the gas pressure using the pressure meter 14 at a predetermined second pressure measurement interval (e.g., 1 second interval) that is shorter than the first pressure measurement interval, and stores the measured pressure in memory. The second flow rate measurement interval and the second pressure measurement interval are equal to each other.

[0031] Next, the control device 11 determines whether the measurement time has reached a predetermined time (step S14). The measurement time is equal to the time for which the gas flow rate is measured in the flow rate measurement operation and the time for which the gas pressure is measured in the pressure measurement operation. The predetermined time is shorter than the determination period, for example, one minute. Until the measurement time reaches the predetermined time (step S14: NO), the control device 11 measures the gas flow rate and pressure and stores them in memory in the order of measurement.

[0032] Then, when the measurement time reaches a predetermined time (step S14: YES), the control device 11 calculates a correlation coefficient between the gas flow rate and pressure measured during the measurement time and stores the calculated correlation coefficient in memory (step S15). The correlation coefficient between the gas flow rate and pressure is expressed by the following equation 1. In this equation, x is the gas flow rate measured in the flow rate measurement operation of S12, y is the gas pressure measured in the pressure measurement operation of S13, and n is the number of data points for x. xi is the gas flow rate measured in the i-th (i: natural number) flow rate measurement operation, and the overlined x is the average value of the n measured flow rates. yi is the gas pressure measured in the i-th pressure measurement operation, and the overlined y is the average value of the n measured pressures.

[0033] Next, the control device 11 adds the currently calculated correlation coefficient to the integrated value obtained by integrating the correlation coefficients calculated the first time through the correlation coefficients calculated the previous time, and stores the integrated value in memory (step S16).

[0034] Next, the control device 11 executes a flooding determination operation to determine whether water has infiltrated the gas pipe 20 based on the correlation coefficient between the measured gas flow rate and the measured gas pressure. In the flooding determination operation, the control device 11 determines whether the integrated value of the correlation coefficient is equal to or greater than a first predetermined integrated value (step S17). That is, the inventors have found through experiments that when a predetermined amount of water has infiltrated the gas pipe 20, there is a positive correlation between the gas flow rate and pressure in the gas pipe 20. Furthermore, the inventors have found through experiments that when a predetermined amount of water has infiltrated the gas pipe 20, a correlation coefficient appears that can be distinguished from when the predetermined amount of water has not infiltrated.

[0035] This predetermined amount is, for example, a ratio of the volume of water to the volume of the gas pipe of 50% or more. In a positive correlation, when the gas flow rate increases, the gas pressure also increases. When this correlation coefficient is a value between -1 and 1, the closer the correlation coefficient is to 1, the stronger the positive correlation. Therefore, the first predetermined integrated value is a positive number.

[0036] If the integrated value of the correlation coefficient is equal to or greater than the first predetermined integrated value (step S17: YES), the control device 11 determines that flooding into the gas pipe 20 has been detected (step S18). In this case, the control device 11 displays safety information indicating the detection of flooding, that is, the infiltration of a predetermined amount or more of water into the gas pipe 20, on the display device 15, and outputs this safety information to the gas company via the communication interface 16. This allows the user of the gas meter 10 or the gas company to take measures against flooding into the gas pipe 20, such as shutting off the gas pipe 20 with the shutoff valve 12.

[0037] On the other hand, in the determination operation of step S17, if the integrated value of the correlation coefficient is less than the first predetermined integrated value (step S17: NO), the control device 11 returns to the processing of step S11. While the determination period is less than the predetermined period in this step S11 (step S11: YES), the control device 11 executes the processing from step S12 onwards. As a result, the control device 11 calculates and integrates the correlation coefficient for each measurement time (for example, one minute) while executing the flow rate measurement operation and the pressure measurement operation until the determination period reaches the predetermined period.

[0038] Then, when the determination period reaches a predetermined period (step S11: NO), the control device 11 determines that intrusion of a predetermined amount or more of water into the gas pipe 20 has not been detected (step S19). In this case, the control device 11 displays safety information indicating that intrusion of a predetermined amount or more of water into the gas pipe 20 has not been detected on the display device 15, or outputs the information to the gas company via the communication interface 16. This allows the user of the gas meter 10, the gas company, etc. to understand the status of intrusion into the gas pipe 20.

[0039] The control device 11 then returns the gas flow rate measurement interval from the second flow rate measurement interval to the first flow rate measurement interval, and returns the gas pressure measurement interval from the second pressure measurement interval to the first pressure measurement interval. By lengthening the measurement interval in this way, the power consumption of the gas meter 10 is reduced. Therefore, if dry batteries are used as the power source for the gas meter 10, the frequency of battery replacement can be reduced.

[0040] In the above description, the control device 11 performs a water inundation determination operation based on the integrated value of the correlation coefficient for each measurement time. However, the timing of performing this water inundation determination operation is not limited to this. For example, the control device 11 may calculate a correlation coefficient for each measurement time until the determination period reaches a predetermined period, and then, when the determination period reaches the predetermined period, perform a water inundation determination operation based on the integrated value of the correlation coefficient for the determination period.

[0041] <Variation 1> In the gas meter 10 of variation 1 of the present disclosure, the control device 11 acquires a correlation coefficient for each measurement time shorter than the judgment period during the judgment period of the flooding judgment operation, and determines that flooding in the gas piping 20 has been detected if the number of correlation coefficients equal to or greater than a first predetermined coefficient is equal to or greater than a first predetermined number.

[0042] In this case, the control device 11 executes a process for detecting water intrusion in the gas pipe 20 in accordance with the flowchart shown in Fig. 3. In the flowchart of Fig. 3, the processes of steps S20 to S22 are executed instead of the processes of steps S16 to S17 in Fig. 2.

[0043] Specifically, if the predetermined condition is met (step S10: YES) and the determination period is less than the predetermined period (step S11: YES), the control device 11 executes the flow rate measurement operation and the pressure measurement operation (steps S12 and S13). Then, when the measurement time reaches a predetermined time (e.g., one minute) (step S14: YES), the control device 11 calculates the correlation coefficient between the measured flow rate and the measured pressure of the gas (step S15).

[0044] Next, the control device 11 determines whether the correlation coefficient is equal to or greater than a first predetermined coefficient (step S20). As described above, when a predetermined amount of water has entered the gas pipe 20, there is a positive correlation between the gas flow rate and pressure in the pipe. Therefore, the first predetermined coefficient is a positive number. Then, if the correlation coefficient is equal to or greater than the first predetermined coefficient (step S20: YES), the control device 11 increments the number of correlation coefficients equal to or greater than the first predetermined coefficient by 1 and stores the increment in memory (step S21).

[0045] Next, the control device 11 executes a flooding determination operation to determine whether water has entered the gas pipe 20 based on the correlation coefficient between the measured gas flow rate and the measured gas pressure. In the flooding determination operation, the control device 11 determines whether the number of correlation coefficients equal to or greater than a first predetermined coefficient is equal to or greater than a first predetermined number (step S22). If the number of correlation coefficients is equal to or greater than the first predetermined number (step S22: YES), the control device 11 determines that flooding of the gas pipe 20 to a predetermined amount or greater has been detected (step S18). In this case, the control device 11 displays safety information indicating the detection of flooding in the gas pipe 20 on the display device 15 and outputs the information to the gas utility via the communication interface 16.

[0046] On the other hand, if the correlation coefficient is less than the first predetermined coefficient in the process of step S20 (step S20: NO), the control device 11 returns to the process of step S11. Furthermore, if the number of correlation coefficients equal to or greater than the first predetermined coefficient is less than the first predetermined number in the process of step S22 (step S22: NO), the control device 11 also returns to the process of step S11. While the determination period is less than the predetermined period in this step S11 (step S11: YES), the control device 11 executes the processes from step S12 onwards. As a result, the control device 11 calculates the correlation coefficient for each measurement time (e.g., one minute) while executing the flow rate measurement operation and the pressure measurement operation until the determination period reaches the predetermined period.

[0047] On the other hand, if the determination period has reached the predetermined period (step S11: NO), the control device 11 determines that intrusion of a predetermined amount or more of water into the gas pipe 20 has not been detected (step S19). In this case, the control device 11 displays safety information indicating that intrusion of water into the gas pipe 20 has not been detected on the display device 15, or outputs the information to the gas utility company via the communication interface 16.

[0048] In the above description, the control device 11 performs the flooding determination operation based on the number of correlation coefficients equal to or greater than the first predetermined coefficient for each measurement time. However, the timing of performing this flooding determination operation is not limited to this. For example, the control device 11 may calculate correlation coefficients for each measurement time until the determination period reaches a predetermined period, and then, when the determination period reaches the predetermined period, perform the flooding determination operation based on the number of correlation coefficients equal to or greater than the first predetermined coefficient.

[0049] <Variation 2> In the gas meter 10 of variation 2 of the present disclosure, during the judgment period of the flooding judgment operation, a correlation coefficient is acquired for each measurement time that is shorter than the judgment period, and if the value obtained by accumulating the acquired correlation coefficients and dividing the integrated value by the judgment period is equal to or greater than a first predetermined value, it is determined that flooding in the gas piping 20 has been detected.

[0050] In this case, the control device 11 executes a process for detecting flooding of the gas pipe 20 in accordance with the flowchart shown in Fig. 4. In the flowchart of Fig. 4, the process of step S11 in Fig. 2 is not executed, and the processes of steps S30 to S31 are executed instead of step S17 in Fig. 2.

[0051] Specifically, when a predetermined condition is met (step S10: YES), the control device 11 executes a flow rate measurement operation and a pressure measurement operation (steps S12 and S13). Then, when the measurement time reaches a predetermined time (e.g., one minute) (step S14: YES), the control device 11 calculates a correlation coefficient between the measured flow rate and the measured pressure of the gas (step S15), and calculates an integrated value of the correlation coefficient (step S16).

[0052] Then, while the determination period is less than the predetermined period (step S30: NO), the control device 11 returns to the process of step S12 and executes the subsequent processes. As a result, the control device 11 calculates the correlation coefficient for each measurement time (for example, one minute) while executing the flow rate measurement operation and the pressure measurement operation until the determination period reaches the predetermined period, and accumulates the correlation coefficient.

[0053] Then, when this determination period reaches a predetermined period (step S30: YES), the control device 11 executes a flood determination operation to determine flooding, that is, water intrusion into the gas pipe 20, based on the correlation coefficient between the measured gas flow rate and the measured gas pressure. In the flood determination operation, the control device 11 divides the integrated value of the correlation coefficient by the determination period to calculate the value of the correlation coefficient per unit time.

[0054] Because the flow rate measurement operation and the pressure measurement operation are performed during this determination period, the determination period is equal to the measurement time of the flow rate measurement operation and the measurement time of the pressure measurement operation, respectively. Then, the control device 11 determines whether the value per unit time of this correlation coefficient is equal to or greater than a first predetermined value (step S31). As described above, when a predetermined amount of water has entered the gas pipe 20, there is a positive correlation between the gas flow rate and pressure in the gas pipe 20. Therefore, the first predetermined value is a positive number.

[0055] If the value of the correlation coefficient per unit time is equal to or greater than the first predetermined value (step S31: YES), the control device 11 determines that flooding of the gas pipe 20 has been detected (step S18). In this case, the control device 11 displays safety information indicating flooding of the gas pipe 20 on the display device 15, or outputs the information to the gas utility via the communication interface 16.

[0056] On the other hand, if the value of the correlation coefficient per unit time is less than the first predetermined value (step S31: NO), the control device 11 determines that intrusion of a predetermined amount or more of water into the gas pipe 20 has not been detected (step S19). In this case, the control device 11 displays safety information indicating that intrusion of water into the gas pipe 20 has not been detected on the display device 15, or outputs it to the gas utility via the communication interface 16.

[0057] In this way, in the flooding determination operation, flooding of the gas pipe 20 is determined using the value of the correlation coefficient per unit time, which is obtained by dividing the integrated value of the correlation coefficient by the determination period. Therefore, even if the determination period is changed, the flooding determination operation, which compares the value of the correlation coefficient per unit time with the first predetermined value, can be performed without changing the first predetermined value. Therefore, the determination period can be easily changed depending on the purpose of the determination. For example, if the purpose is to achieve high accuracy, the determination period can be extended to improve the accuracy of the flooding determination based on a larger number of correlation coefficients. Furthermore, if the purpose is to achieve a simplified determination, the determination period can be shortened to shorten the time for the flow rate measurement operation and the pressure measurement operation, thereby shortening the time for the flooding detection process.

[0058] <Modification 3> In a gas meter 10 according to Modification 3 of the present disclosure, in the first embodiment, the control device 11 executes an extension determination operation that determines whether or not to extend the determination period in the flooding determination operation based on a correlation coefficient.

[0059] In this case, the control device 11 executes a process for detecting water intrusion in the gas pipe 20 in accordance with the flowchart shown in the example of Fig. 5. In the flowchart of Fig. 5, the processes of steps S40 to S41 are executed after determining NO in step S11 of Fig. 2.

[0060] Specifically, when a predetermined condition is met (step S10: YES), the control device 11 calculates a correlation coefficient for each measurement time (e.g., one minute) until the determination period reaches a predetermined period (step S11: YES) and calculates an integrated value of the correlation coefficient (steps S12 to S16). Next, the control device 11 determines whether the integrated value of the correlation coefficient is equal to or greater than a first predetermined integrated value (step S17). Here, if the integrated value of the correlation coefficient is equal to or greater than the first predetermined integrated value (step S17: YES), the control device 11 determines that flooding of the gas pipe 20 has been detected (step S18).

[0061] On the other hand, if the integrated value of the correlation coefficient is less than the first predetermined integrated value (step S17: NO), the control device 11 returns to the process of step S11 and executes subsequent processes. If the determination period reaches the predetermined period in step S11 (step S11: NO), the control device 11 executes an extension determination operation. In the extension determination operation, the control device 11 determines whether the integrated value of the correlation coefficient is less than a third predetermined integrated value (step S40). The third predetermined integrated value is a positive number that is smaller than the first predetermined integrated value.

[0062] That is, if the first predetermined integrated value is too small, there is a risk that detection of flooding into the gas pipe 20 may be judged unnecessary. Therefore, the control device 11 compares a third predetermined integrated value, which is smaller than the first predetermined integrated value, with the integrated value of the correlation coefficient. Here, if the integrated value of the correlation coefficient is equal to or greater than the third predetermined integrated value (step S40: NO), there is a possibility of flooding into the gas pipe 20. Therefore, the control device 11 extends the predetermined period by adding a predetermined extension period to the predetermined period (step S41). This extends the determination period. Note that the number of times the predetermined period is extended in step S41 may be limited to a predetermined number of times.

[0063] The control device 11 then returns to the process of step S11 and executes the subsequent processes. When the determination period reaches the extended predetermined period (step S11: NO), the control device 11 executes the process of step S40. In the process of step S40, if the integrated value of the correlation coefficient is less than the third predetermined integrated value (step S40: YES), the control device 11 determines that intrusion of water equal to or greater than a predetermined amount into the gas pipe 20 has not been detected (step S19).

[0064] In this way, by setting the first predetermined integrated value larger than the third predetermined integrated value, it is possible to reduce unnecessary detection of flooding into the gas pipe 20. Furthermore, by setting the third predetermined integrated value smaller than the first predetermined integrated value, if there is a risk of flooding into the gas pipe 20, it is possible to accurately determine whether flooding into the gas pipe 20 has occurred by extending the period for determining whether flooding into the gas pipe 20 has occurred.

[0065] <Modification 4> In the water submersion detection process for the gas meter 10 according to Modification 1, the determination period may also be extended, as in Modification 3. In this case, as shown in the example flowchart in Figure 6, after determining NO in step S11 in Figure 3, the processes of steps S41 and S42 are executed.

[0066] In this case, when a predetermined condition is met (step S10: YES), the control device 11 calculates a correlation coefficient for each measurement time (e.g., 1 minute) and stores the calculated correlation coefficient in memory (steps S12 to S15) until the determination period reaches a predetermined period (step S11: YES). Subsequently, the control device 11 determines whether the correlation coefficient is equal to or greater than a first predetermined coefficient (step S20), and determines whether the number of correlation coefficients equal to or greater than the first predetermined coefficient is equal to or greater than a first predetermined number (steps S21 and S22).

[0067] When the determination period reaches the predetermined period (step S11: NO), the control device 11 executes an extension determination operation. In this extension determination operation, the control device 11 determines whether the number of correlation coefficients equal to or greater than the first predetermined coefficient is less than a third predetermined number (step S42). The third predetermined number is a positive number that is smaller than the first predetermined number.

[0068] Here, if the number of correlation coefficients equal to or greater than the first predetermined coefficient is equal to or greater than a third predetermined number (step S42: NO), the control device 11 determines that there is a possibility of water flooding into the gas pipe 20. Therefore, the control device 11 extends the predetermined period by adding a predetermined extension period to the predetermined period (step S41). This extends the determination period. The control device 11 then returns to the processing of step S11. As a result, the control device 11 executes subsequent processing while the determination period is less than the extended predetermined period (step S11: YES). Then, when the determination period reaches the extended predetermined period (step S11: NO), the control device 11 executes the processing of step S42.

[0069] In the processing of step S42, if the number of correlation coefficients equal to or greater than the first predetermined coefficient is less than the third predetermined number (step S42: YES), the control device 11 determines that no intrusion of water greater than a predetermined amount into the gas piping 20 has been detected (step S19).

[0070] In this way, by setting the first predetermined number larger than the third predetermined number, it is possible to reduce unnecessary detection of flooding into the gas pipe 20. Furthermore, by setting the third predetermined number smaller than the first predetermined number, if there is a risk of flooding into the gas pipe 20, it is possible to accurately determine whether flooding into the gas pipe 20 has occurred by extending the period for determining whether flooding into the gas pipe 20 has occurred.

[0071] <Modification 5> In the water submersion detection process for the gas meter 10 according to Modification 2, the determination period may also be extended, as in Modification 3. In this case, as shown in the example flowchart in Figure 7, after determining NO in step S31 in Figure 4, the processes of steps S41 and S43 are executed.

[0072] In this case, when a predetermined condition is met (step S10: YES), the control device 11 calculates a correlation coefficient for each measurement time (e.g., 1 minute) until the judgment period reaches a predetermined period (step S30: NO), and calculates an integrated value of the correlation coefficient (steps S12 to S16). Subsequently, when the judgment period reaches the predetermined period (step S30: YES), the control device 11 determines whether the value (value per unit time) obtained by dividing the integrated value of the correlation coefficient by the judgment period is equal to or greater than a first predetermined value (step S31).

[0073] If the value of the correlation coefficient per unit time is less than the first predetermined value (step S31: NO), the control device 11 executes an extension determination operation. In this extension determination operation, the control device 11 determines whether the value of the correlation coefficient per unit time is less than a third predetermined value (step S43). The third predetermined value is a positive number that is smaller than the first predetermined value.

[0074] Here, if the value of the correlation coefficient per unit time is equal to or greater than the third predetermined value (step S43: NO), the control device 11 determines that there is a possibility of water flooding into the gas pipe 20. Therefore, the control device 11 extends the predetermined period by adding a predetermined extension period to the predetermined period (step S41). This extends the determination period. The control device 11 then returns to the processing of step S12 and executes subsequent processing. As a result, the control device 11 calculates an integrated value of the correlation coefficient for each measurement time (e.g., 1 minute) and stores the calculated value in memory (steps S12 to S16) while the determination period is less than the extended predetermined period (step S31: NO).

[0075] When the determination period reaches the extended predetermined period (step S30: NO), the control device 11 divides the integrated value of the correlation coefficient accumulated during the extended determination period by the extended determination period to calculate the value of the correlation coefficient per unit time. If the value of this correlation coefficient per unit time is equal to or greater than a first predetermined value (step S31: YES), the control device 11 determines that flooding of the gas pipe 20 has been detected (step S18). On the other hand, if the value of this correlation coefficient per unit time is less than the first predetermined value (step S31: NO), the control device 11 executes the process of step S43.

[0076] Here, if the value of the correlation coefficient per unit time is less than the third predetermined value (step S43: YES), the control device 11 determines that no intrusion of water greater than a predetermined amount into the gas piping 20 has been detected (step S19).

[0077] In this way, by setting the first predetermined value larger than the third predetermined value, it is possible to reduce unnecessary detection of flooding into the gas pipe 20. Furthermore, by setting the third predetermined value smaller than the first predetermined value, when there is a risk of flooding into the gas pipe 20, the period for determining flooding into the gas pipe 20 can be extended, thereby making it possible to accurately determine whether flooding into the gas pipe 20 has occurred.

[0078] <Embodiment 2> In the gas meter 10 according to embodiment 1, the control device 11 executes a water flood determination operation based on the correlation coefficient between the gas flow rate and pressure in the gas pipe 20. In contrast, in the gas meter 10 according to embodiment 2, the control device 11 executes a pulsation determination operation to determine pulsation, which is fluctuation in the gas flow rate in the gas pipe 20, based on the correlation coefficient between the gas flow rate and pressure in the gas pipe 20. Note that in the gas meter 10, the control device 11 may execute both the water flood determination operation and the pulsation determination operation based on the correlation coefficient between the gas flow rate and pressure in the gas pipe 20.

[0079] The process of detecting gas pulsation in the gas pipe 20 of the gas meter 10 is executed by the control device 11 according to the example flowchart of Fig. 8. In the flowchart of Fig. 8, the processes of steps S50 to S52 are executed instead of the processes of steps S17 to S19 of Fig. 2.

[0080] Specifically, if the predetermined conditions are met (step S10: YES) and the judgment period is less than the predetermined period (step S11: YES), the control device 11 calculates the integrated value of the correlation coefficient between the measured flow rate and the measured pressure of the gas (steps S12 to S16).

[0081] Next, the control device 11 executes a pulsation determination operation for determining pulsation, which is a periodic fluctuation of gas in the gas pipe 20, based on the correlation coefficient between the measured gas flow rate and the measured gas pressure. In the pulsation determination operation, the control device 11 determines whether the integrated value of the correlation coefficient is less than a second predetermined integrated value (step S50). That is, the inventors have found through experiments that when gas pulsation occurs in the gas pipe 20, there is a negative correlation between the gas flow rate and pressure in the gas pipe 20. Furthermore, the inventors have found through experiments that when gas pulsation occurs in the gas pipe 20, a correlation coefficient appears that can be distinguished from when gas pulsation does not occur.

[0082] In a negative correlation, when the gas flow rate increases, the gas pressure decreases. When this correlation coefficient is a value between -1 and 1, the closer the correlation coefficient is to -1, the stronger the negative correlation. Therefore, the second predetermined integrated value is a negative number.

[0083] Then, if the integrated value of this correlation coefficient is less than the second predetermined integrated value (step S50: YES), the control device 11 determines that gas pulsation has been detected in the gas pipe 20 (step S51). In this case, the control device 11 displays safety information indicating the gas pulsation in the gas pipe 20 on the display device 15 or outputs it to the gas company via the communication interface 16. This allows the user of the gas meter 10 or the gas company to take measures against gas pulsation in the gas pipe 20. For example, in the safety processing, parameters such as the flow rate and pressure used as criteria for shutting off the gas pipe 20 by the shutoff valve 12 are changed. This makes it possible to prevent the gas pipe 20 from being unnecessarily shut off due to pulsation.

[0084] On the other hand, in the pulsation determination operation of step S50, if the integrated value of the correlation coefficient is equal to or greater than the second predetermined integrated value (step S50: NO), the control device 11 returns to the processing of step S11. While the determination period is less than the predetermined period in step S11 (step S11: YES), the control device 11 executes the processing of step S12 and subsequent steps. As a result, the control device 11 calculates and integrates the correlation coefficient for each measurement time (e.g., one minute) while performing the flow rate measurement operation and the pressure measurement operation until the determination period reaches the predetermined period.

[0085] Then, when the determination period reaches a predetermined period (step S11: NO), the control device 11 determines that gas pulsation has not been detected in the gas pipe 20 (step S52). In this case, the control device 11 displays safety information indicating that gas pulsation has not been detected in the gas pipe 20 on the display device 15, or outputs the information to the gas company via the communication interface 16. This allows the user of the gas meter 10 and the gas company to understand the gas pulsation status in the gas pipe 20.

[0086] In the above description, the control device 11 executes the pulsation determination operation based on the integrated value of the correlation coefficient for each measurement time. However, the execution timing of this pulsation determination operation is not limited to this. For example, the control device 11 may calculate the correlation coefficient for each measurement time until the determination period reaches a predetermined period, and then execute the pulsation determination operation based on the integrated value of the correlation coefficient for the determination period when the determination period reaches the predetermined period.

[0087] <Variation 6> In the gas meter 10 of Variation 6 of the present disclosure, the control device 11 acquires a correlation coefficient for each measurement time shorter than the judgment period during the judgment period of the flood judgment operation, and if the number of correlation coefficients less than the first predetermined coefficient is equal to or greater than a second predetermined number, determines that gas pulsation has been detected in the gas piping 20.

[0088] In this case, the control device 11 executes a pulsation detection process in the gas pipe 20 in accordance with the flowchart shown in Fig. 9. In the flowchart of Fig. 9, steps S53 to S55 are executed instead of steps S20 to S22 in Fig. 3, and steps S51 to S52 are executed instead of steps S18 to S19 in Fig. 3.

[0089] Specifically, when a predetermined condition is met (step S10: YES), the control device 11 calculates the correlation coefficient between the measured flow rate and the measured pressure of the gas (steps S12 to S15) while the judgment period is less than the predetermined period (step S11: YES).

[0090] Next, the control device 11 determines whether the correlation coefficient is equal to or greater than a second predetermined coefficient (step S53). As described above, when gas pulsation occurs in the gas pipe 20, there is a negative correlation between the gas flow rate and pressure in the gas pipe 20. Therefore, the second predetermined coefficient is a negative number. Here, if the correlation coefficient is less than the second predetermined coefficient (step S53: YES), the control device 11 increments the number of correlation coefficients less than the second predetermined coefficient by 1 and stores the increment in memory (step S54).

[0091] Next, the control device 11 executes a pulsation determination operation for determining gas pulsation in the gas pipe 20 based on the correlation coefficient between the measured gas flow rate and the measured gas pressure. In the pulsation determination operation, the control device 11 determines whether the number of correlation coefficients less than the second predetermined coefficient is equal to or greater than a second predetermined number (step S55). Here, if the number of correlation coefficients less than the second predetermined coefficient is equal to or greater than the second predetermined number (step S55: YES), the control device 11 determines that gas pulsation in the gas pipe 20 has been detected (step S51).

[0092] Furthermore, if the correlation coefficient is equal to or greater than the second predetermined coefficient (step S53: NO) or if the number of correlation coefficients less than the second predetermined coefficient is less than the second predetermined number (step S55: NO), the control device 11 returns to the process of step S11. While the determination period is less than the predetermined period in step S11 (step S11: YES), the control device 11 executes the processes of step S12 and subsequent steps. As a result, the control device 11 calculates the correlation coefficient every measurement time (e.g., one minute) while performing the flow rate measurement operation and the pressure measurement operation until the determination period reaches the predetermined period. Then, if the determination period reaches the predetermined period (step S11: NO), the control device 11 determines that gas pulsation in the gas pipe 20 has not been detected (step S52).

[0093] In the above example, the control device 11 executes the pulsation determination operation based on the number of correlation coefficients less than the second predetermined coefficient. However, the execution timing of this pulsation determination operation is not limited to this. For example, the control device 11 may calculate a correlation coefficient for each measurement time until the determination period reaches the predetermined period, and then, when the determination period reaches the predetermined period, execute the pulsation determination operation based on the number of correlation coefficients less than the second predetermined coefficient among these correlation coefficients.

[0094] <Variation 7> In the gas meter 10 of variation 7 of the present disclosure, the control device 11 acquires a correlation coefficient for each measurement time shorter than the judgment period during the judgment period of the flooding judgment operation, and if the value obtained by accumulating the acquired correlation coefficients and dividing the integrated value by the judgment period is less than a second predetermined value, the control device 11 determines that gas pulsation has been detected in the gas piping 20.

[0095] In this case, the control device 11 executes a pulsation detection process in the gas pipe 20 in accordance with the flowchart shown in Fig. 10. In the flowchart of Fig. 10, the process of step S56 is executed instead of the process of step S31 in Fig. 4, and the processes of steps S51 and S52 are executed instead of the processes of steps S18 and S19 in Fig. 3.

[0096] Specifically, when a predetermined condition is met (step S10: YES), the control device 11 calculates an integrated value of the correlation coefficient between the measured flow rate and the measured pressure of the gas (steps S12 to S16). Then, while the determination period is less than the predetermined period (step S30: NO), the control device 11 returns to the process of step S12 and executes subsequent processes. As a result, the control device 11 calculates and integrates the correlation coefficient for each measurement time (e.g., one minute) while performing the flow rate measurement operation and the pressure measurement operation until the determination period reaches the predetermined period.

[0097] Next, if the determination period reaches a predetermined period (step S30: YES), the control device 11 executes a pulsation determination operation to determine gas pulsation in the gas pipe 20 based on the correlation coefficient between the measured gas flow rate and the measured gas pressure. In the pulsation determination operation, the control device 11 divides the integrated value of the correlation coefficient by the determination period to calculate the value of the correlation coefficient per unit time. Then, the control device 11 determines whether the value of the correlation coefficient per unit time is less than a second predetermined value (step S56). As described above, when gas pulsation occurs in the gas pipe 20, the gas flow rate and pressure in the gas pipe 20 have a negative correlation. Therefore, the second predetermined value is a negative number.

[0098] Here, if the value of the correlation coefficient per unit time is less than the second predetermined value (step S56: YES), the control device 11 determines that gas pulsation has been detected in the gas piping 20 (step S51). On the other hand, if the value of the correlation coefficient per unit time is equal to or greater than the second predetermined value (step S56: NO), the control device 11 determines that gas pulsation has not been detected in the gas piping 20 (step S52).

[0099] In this way, in the pulsation determination operation, the gas pulsation in the gas pipe 20 is determined using the value of the correlation coefficient per unit time, which is obtained by dividing the integrated value of the correlation coefficient by the determination period. Therefore, even if the determination period is changed, the pulsation determination operation in which the value of the correlation coefficient per unit time and the second predetermined value are compared can be executed without changing the second predetermined value. Therefore, the determination period can be easily changed depending on the purpose of the determination. For example, when high-precision determination is the objective, the accuracy of pulsation determination can be improved based on a larger number of correlation coefficients by extending the determination period. Furthermore, when simple determination is the objective, the determination period can be shortened to shorten the time for the flow rate measurement operation and the pressure measurement operation, thereby shortening the time for the pulsation detection process.

[0100] <Modification 8> In a gas meter 10 according to Modification 8 of the present disclosure, in the second embodiment, the control device 11 executes an extension determination operation that determines whether or not to extend the determination period in the pulsation determination operation based on a correlation coefficient.

[0101] In this case, the control device 11 executes a pulsation detection process in the gas pipe 20 in accordance with the flowchart shown in Fig. 11. In the flowchart of Fig. 11, the processes of steps S60 to S61 are executed after the determination of NO in step S11 of Fig. 8.

[0102] Specifically, when a predetermined condition is met (step S10: YES), the control device 11 further executes operations such as a flow rate measurement operation, a pressure measurement operation, and a pulsation determination operation (steps S12 to S16, S50) until the determination period reaches a predetermined period (step S11: NO). Subsequently, if the integrated value of the correlation coefficient is equal to or greater than a second predetermined integrated value (step S50: NO), the control device 11 returns to the processing of step S11 and executes subsequent processing. As a result, the control device 11 calculates and integrates a correlation coefficient for each measurement time (e.g., one minute) while executing the flow rate measurement operation and the pressure measurement operation until the determination period reaches the predetermined period.

[0103] If the determination period reaches the predetermined period in step S11 (step S11: NO), the control device 11 executes an extension determination operation. In the extension determination operation, the control device 11 determines whether the integrated value of the correlation coefficient is equal to or greater than a fourth predetermined integrated value (step S60). The fourth predetermined integrated value is a negative number and is greater than the second predetermined integrated value.

[0104] That is, if the second predetermined integrated value is too large, there is a risk that the detection of gas pulsation in the gas pipe 20 will be determined to be unnecessary. Therefore, the control device 11 compares the integrated value of the correlation coefficient with a fourth predetermined integrated value that is larger than the second predetermined integrated value. Here, if the integrated value of the correlation coefficient is less than the fourth predetermined integrated value (step S60: NO), there is a possibility of gas pulsation in the gas pipe 20. Therefore, the control device 11 extends the predetermined period by adding a predetermined extension period to the predetermined period (step S61). This extends the determination period. Note that the number of times the predetermined period is extended in step S61 may be limited to a predetermined number of times.

[0105] The control device 11 then returns to the process of step S11 and executes the subsequent processes. When the determination period reaches the extended predetermined period (step S11: NO), the control device 11 executes the process of step S60. In the process of step S60, if the integrated value of the correlation coefficient is equal to or greater than a fourth predetermined integrated value (step S60: YES), the control device 11 determines that gas pulsation in the gas pipe 20 has not been detected (step S52).

[0106] In this way, by setting the second predetermined integrated value smaller than the fourth predetermined integrated value, it is possible to reduce unnecessary detection of gas pulsation in the gas pipe 20. Furthermore, by setting the fourth predetermined integrated value larger than the second predetermined integrated value, if there is a risk of gas pulsation, the period for determining whether water has entered the gas pipe 20 can be extended, thereby making it possible to accurately determine gas pulsation.

[0107] <Modification 9> In the pulsation detection process of the gas meter 10 according to Modification 6, the determination period may also be extended as in Modification 8. In this case, as shown in the example flowchart in Fig. 12 , the processes of steps S61 and S62 are executed after the determination of NO in step S11 in Fig. 9 .

[0108] In this case, when a predetermined condition is met (step S10: YES), the control device 11 calculates a correlation coefficient for each measurement time and stores the calculated correlation coefficient in memory (steps S12 to S15) until the determination period reaches the predetermined period (step S11: YES). Subsequently, the control device 11 determines whether the correlation coefficient is less than a second predetermined coefficient (step S53), and determines whether the number of correlation coefficients less than the second predetermined coefficient is equal to or greater than the second predetermined number (steps S54 and S55).

[0109] If the number of correlation coefficients less than the second predetermined coefficient is less than the second predetermined number (step S55: NO) and the determination period reaches the predetermined period (step S11: NO), the control device 11 executes an extension determination operation. In this extension determination operation, the control device 11 determines whether the number of correlation coefficients less than the second predetermined coefficient is less than a fourth predetermined number (step S62). The fourth predetermined number is a value smaller than the second predetermined number.

[0110] If the number of correlation coefficients less than the second predetermined coefficient is equal to or greater than the fourth predetermined number (step S62: NO), the control device 11 determines that there is a possibility of gas pulsation. Therefore, the control device 11 extends the predetermined period by adding a predetermined extension period (step S61). This extends the determination period. The number of times the predetermined period is extended in step S41 may be limited to a predetermined number.

[0111] The control device 11 then returns to the process of step S11 and executes the subsequent processes. When the determination period reaches the extended predetermined period (step S11: NO), the control device 11 executes the process of step S62. In the process of step S62, if the number of correlation coefficients less than the second predetermined coefficient is less than the fourth predetermined number (step S62: YES), the control device 11 determines that gas pulsation in the gas pipe 20 has not been detected (step S52).

[0112] In this way, by setting the second predetermined number larger than the fourth predetermined number, it is possible to reduce unnecessary detection of gas pulsation in the gas piping 20. Furthermore, by setting the fourth predetermined number smaller than the second predetermined number, if there is a risk of gas pulsation, the period for determining whether water has entered the gas piping 20 can be extended, thereby making it possible to accurately determine the gas pulsation.

[0113] <Modification 10> In addition, in the pulsation detection process of the gas meter 10 according to Modification 7, the determination period may be extended as in Modification 8. In this case, as shown in the example flowchart of Fig. 13 , the processes of steps S61 and S63 are executed after the determination of NO in step S56 of Fig. 10 .

[0114] In this case, when a predetermined condition is met (step S10: YES), the control device 11 calculates a correlation coefficient for each measurement time and calculates an integrated value of the correlation coefficient (steps S12 to S16) until the determination period reaches a predetermined period (step S30: NO). Subsequently, when the determination period reaches a predetermined period (step S30: YES), the control device 11 determines whether the value of the correlation coefficient per unit time is equal to or greater than a first predetermined value (step S56).

[0115] If the value of the correlation coefficient per unit time is equal to or greater than the second predetermined value (step S56: NO), the control device 11 executes an extension determination operation. In this extension determination operation, the control device 11 determines whether the value of the correlation coefficient per unit time is equal to or greater than a fourth predetermined value (step S63). The fourth predetermined value is a negative number that is greater than the second predetermined value.

[0116] Here, if the value of the correlation coefficient per unit time is less than the fourth predetermined value (step S63: NO), the control device 11 determines that there is a possibility of gas pulsation in the gas pipe 20. Therefore, the control device 11 extends the predetermined period by adding a predetermined extension period to the predetermined period (step S61). This extends the determination period. The control device 11 then returns to the processing of step S12 and executes subsequent processing. As a result, the control device 11 calculates an integrated value of the correlation coefficient for each measurement time and stores it in memory (steps S12 to S16) while the determination period is less than the extended predetermined period (step S31: NO).

[0117] When the determination period reaches the extended predetermined period (step S30: NO), the control device 11 divides the integrated value of the correlation coefficient accumulated during the extended determination period by the extended determination period to calculate the value of the correlation coefficient per unit time. If the value of this correlation coefficient per unit time is less than a second predetermined value (step S56: YES), the control device 11 determines that gas pulsation has been detected in the gas pipe 20 (step S51). On the other hand, if the value of this correlation coefficient per unit time is equal to or greater than the second predetermined value (step S56: NO), the control device 11 executes the process of step S63.

[0118] Here, if the value of the correlation coefficient per unit time is equal to or greater than the fourth predetermined value (step S63: YES), the control device 11 determines that gas pulsation in the gas piping 20 has not been detected (step S52).

[0119] In this way, by setting the second predetermined value smaller than the fourth predetermined value, it is possible to reduce unnecessary detection of gas pulsation in the gas piping 20. Furthermore, by setting the fourth predetermined value larger than the second predetermined value, if there is a risk of gas pulsation, the period for determining whether water has entered the gas piping 20 can be extended, thereby making it possible to accurately determine the gas pulsation.

[0120] 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.

[0121] <Additional Notes> The above description of the embodiments discloses the following technologies: A first technology is a gas meter including a flow meter that measures the flow rate of gas flowing through a gas pipe, a pressure meter that measures the pressure of the gas in the gas pipe, and a control device, wherein the control device performs at least one of a flood determination operation that determines flooding, in which water has entered the gas pipe, and a pulsation determination operation that determines pulsation, in which the gas flow rate in the gas pipe fluctuates, based on a correlation coefficient between the gas flow rate measured by the flow meter and the gas pressure measured by the pressure meter.

[0122] With this configuration, at least one of the determination of water intrusion into the gas pipe or the determination of gas pulsation in the gas pipe is performed based on the correlation between the gas flow rate and pressure. Even if some influence is applied to the gas flow rate and pressure in the gas pipe, the magnitude of the influence on the correlation coefficient using both the flow rate and pressure is kept smaller than when only pressure is used. Therefore, the determination based on the correlation coefficient can improve the accuracy of the determination compared to a determination based only on the gas pressure.

[0123] The second technology is the gas meter described in Technology 1, in which the control device acquires the correlation coefficient for each measurement time shorter than the judgment period during the judgment period of the flooding judgment operation, and if the integrated value obtained by accumulating the acquired correlation coefficients is equal to or greater than a first predetermined integrated value, it determines that flooding in the gas piping has been detected.

[0124] According to this configuration, the correlation coefficient between the gas flow rate and pressure is calculated multiple times during the determination period, and the integrated value of these multiple correlation coefficients is used to determine whether the gas pipe is flooded. By determining whether the gas pipe is flooded based on multiple correlation coefficients in this way, it is possible to accurately determine whether the gas pipe is flooded based on the trend of changes, such as increases, in the multiple correlation coefficients.

[0125] A third technology is the gas meter described in Technology 1, in which the control device acquires the correlation coefficient for each measurement time shorter than the judgment period during the judgment period of the flooding judgment operation, and if the number of the correlation coefficients equal to or greater than a first predetermined coefficient is equal to or greater than a first predetermined number, it determines that flooding in the gas piping has been detected.

[0126] According to this configuration, the correlation coefficient between the gas flow rate and pressure is compared with the first predetermined coefficient multiple times, and the number of correlation coefficients equal to or greater than the first predetermined coefficient is used to determine whether the gas pipe is flooded. By determining whether the gas pipe is flooded based on multiple correlation coefficients in this way, it is possible to accurately determine whether the gas pipe is flooded based on the trend of changes, such as an increase in the multiple correlation coefficients.

[0127] A fourth technology is the gas meter described in Technology 1, in which the control device acquires the correlation coefficient for each measurement time shorter than the judgment period during the judgment period of the flooding judgment operation, and if the value obtained by dividing the integrated value of the acquired correlation coefficients by the judgment period is equal to or greater than a first predetermined value, it determines that flooding in the gas piping has been detected.

[0128] According to this configuration, the correlation coefficient between the gas flow rate and pressure is calculated multiple times during the determination period, and the values ​​per unit time of these multiple correlation coefficients are used to determine whether the gas pipe is flooded. By determining whether the gas pipe is flooded based on multiple correlation coefficients in this way, it is possible to accurately determine whether the gas pipe is flooded based on the trend of changes, such as increases, in the multiple correlation coefficients.

[0129] Furthermore, for example, the value obtained by dividing the integrated value of the multiple correlation coefficients by the determination period is used as the value of the correlation coefficient per unit time. This makes it possible to change the determination period without changing the first predetermined value and determine whether or not the gas pipe is flooded using the value of the correlation coefficient per unit time.

[0130] A fifth technique is a gas meter described in any of techniques 2 to 4, in which the control device performs an extension determination operation to determine whether or not to extend the determination period in the flood determination operation based on the correlation coefficient.

[0131] According to this configuration, even if the correlation coefficient does not indicate that the gas pipe is flooded, if there is a possibility of flooding, the flooding determination period is extended. This extension allows more correlation coefficients to be obtained, and flooding of the gas pipe can be determined with high accuracy based on these correlation coefficients. In addition, the criteria for determining flooding of the gas pipe can be set stricter than the extension criteria, thereby reducing unnecessary detection of flooding of the gas pipe.

[0132] A sixth technology is the gas meter described in Technology 1, in which the control device acquires the correlation coefficient for each measurement time shorter than the judgment period during the judgment period of the pulsation judgment operation, and if the integrated value obtained by accumulating the acquired correlation coefficients is less than a second predetermined integrated value, it determines that gas pulsation has been detected in the gas piping.

[0133] According to this configuration, the correlation coefficient between the gas flow rate and pressure is calculated multiple times during the determination period, and the integrated value of these multiple correlation coefficients is used to determine the gas pulsation in the gas pipe. By determining the gas pulsation based on multiple correlation coefficients in this way, the gas pulsation can be determined with high accuracy according to the tendency of change, such as an increase, of the multiple correlation coefficients.

[0134] The seventh technology is a gas meter described in Technology 1, in which, during the judgment period of the flood judgment operation, the correlation coefficient is acquired for each measurement time shorter than the judgment period, and if the number of correlation coefficients less than a first predetermined coefficient is equal to or greater than a second predetermined number, it is determined that gas pulsation has been detected in the gas piping.

[0135] According to this configuration, the correlation coefficient between the gas flow rate and pressure is compared with the second predetermined coefficient multiple times, and the number of correlation coefficients less than the second predetermined coefficient is used to determine the gas pulsation in the gas piping. By determining the gas pulsation based on the multiple correlation coefficients in this manner, the gas pulsation can be determined with high accuracy according to the tendency of change, such as an increase, of the multiple correlation coefficients.

[0136] The eighth technology is a gas meter described in Technology 1, in which, during the judgment period of the flood judgment operation, the correlation coefficient is acquired for each measurement time shorter than the judgment period, and if the value obtained by accumulating the acquired correlation coefficients and dividing the integrated value by the judgment period is less than a second predetermined value, it is determined that gas pulsation has been detected in the gas piping.

[0137] According to this configuration, the correlation coefficient between the gas flow rate and pressure is calculated multiple times during the determination period, and the values ​​per unit time of these multiple correlation coefficients are used to determine gas pulsation in the gas piping. By determining gas pulsation based on multiple correlation coefficients in this manner, gas pulsation can be determined with high accuracy according to the tendency of change, such as an increase, of the multiple correlation coefficients.

[0138] Furthermore, for example, the value obtained by dividing the integrated value of the multiple correlation coefficients by the determination period is used as the value of the correlation coefficient per unit time, and thus the determination period can be changed without changing the second predetermined value, and the gas pulsation in the gas pipe can be determined using the value of the correlation coefficient per unit time.

[0139] A ninth technique is a gas meter described in any of techniques 6 to 8, in which the control device performs an extension determination operation to determine whether to extend the determination period in the pulsation determination operation based on the correlation coefficient.

[0140] According to this configuration, even if the correlation coefficient does not indicate gas pulsation in the gas pipe, if there is a possibility of gas pulsation, the gas pulsation determination period is extended. This extension allows more correlation coefficients to be obtained, and gas pulsation can be determined with high accuracy based on these correlation coefficients. Furthermore, by setting the criteria for determining gas pulsation in the gas pipe stricter than the extension criteria, it is possible to reduce unnecessary determinations of gas pulsation detection.

[0141] 10: Gas meter 11: Control device 13: Flow meter 14: Pressure gauge 20: Gas pipe

Claims

1. A gas meter comprising: a flow meter that measures the flow rate of gas flowing through a gas pipe; a pressure meter that measures the pressure of the gas in the gas pipe; and a control device, wherein the control device performs at least one of a flooding determination operation that determines whether water has entered the gas pipe, based on a correlation coefficient between the gas flow rate measured by the flow meter and the gas pressure measured by the pressure meter, and a pulsation determination operation that determines whether there is pulsation in the gas flow rate in the gas pipe that fluctuates.

2. The gas meter of claim 1, wherein the control device acquires the correlation coefficient for each measurement time shorter than the judgment period during the judgment period of the flooding judgment operation, and if the integrated value obtained by accumulating the acquired correlation coefficients is equal to or greater than a first predetermined integrated value, determines that flooding in the gas piping has been detected.

3. The gas meter according to claim 1, wherein the control device acquires the correlation coefficient for each measurement time shorter than the judgment period during the judgment period of the flooding judgment operation, and determines that flooding in the gas pipe has been detected if the number of correlation coefficients equal to or greater than a first predetermined coefficient is equal to or greater than a first predetermined number.

4. The gas meter of claim 1, wherein the control device acquires the correlation coefficient for each measurement time shorter than the judgment period during the judgment period of the flooding judgment operation, and determines that flooding in the gas pipe has been detected if the value obtained by dividing the integrated value of the acquired correlation coefficients by the judgment period is equal to or greater than a first predetermined value.

5. The gas meter according to any one of claims 2 to 4, wherein the control device executes an extension determination operation that determines whether or not to extend the determination period in the flooding determination operation based on the correlation coefficient.

6. The gas meter according to claim 1, wherein the control device acquires the correlation coefficient for each measurement time shorter than the judgment period during the judgment period of the pulsation judgment operation, and if the integrated value obtained by accumulating the acquired correlation coefficients is less than a second predetermined integrated value, determines that gas pulsation has been detected in the gas piping.

7. The gas meter according to claim 1, wherein the control device acquires the correlation coefficient for each measurement time shorter than the judgment period during the judgment period of the flooding judgment operation, and determines that gas pulsation has been detected in the gas pipe if the number of correlation coefficients less than a first predetermined coefficient is equal to or greater than a second predetermined number.

8. The gas meter according to claim 1, wherein the control device acquires the correlation coefficient for each measurement time shorter than the judgment period during the judgment period of the flood judgment operation, and if the value obtained by accumulating the acquired correlation coefficients and dividing the accumulated value by the judgment period is less than a second predetermined value, determines that gas pulsation has been detected in the gas piping.

9. The gas meter according to any one of claims 6 to 8, wherein the control device executes an extension determination operation for determining whether or not to extend the determination period in the pulsation determination operation based on the correlation coefficient.

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