Water leakage detection system

Abstract

This water leakage detection system comprises a plurality of flow meters, and a central device that manages each flow meter, wherein: each flow meter includes a flow rate measuring unit that measures the flow rate of water in a flow path of a water supply network, a pressure acquiring unit that acquires the water pressure in the flow path, a temperature acquiring unit that acquires the temperature of the water in the flow path, and a communication unit that communicates with the central device; and the central device comprises an integrated communication unit that communicates with the communication units, and a water leakage determining unit that calculates a determination pressure for determining the presence or absence of water leakage on the basis of the temperature and the water pressure acquired by each flow meter when the water flow rate from each of the plurality of flow meters in a target sector for water leakage inspection is equal to or less than a threshold and the flow rate flowing into the target sector is equal to or less than a threshold, and that determines the presence or absence of water leakage by comparing the calculated determination pressure with a reference pressure stored in advance.

Description

Water Leak Detection System

[0001] The present disclosure relates to a water leak detection system.

[0002] A water leak detection system has been known in the past that detects water leaks by linking a communication unit provided in each ultrasonic flowmeter with a centralized processing unit having a centralized communication unit (see Patent Document 1). In this water leak detection system, when all flow rates of the ultrasonic flowmeters in a target area and the flow rate upstream of the target area fall below a threshold, the propagation time of ultrasonic waves between two adjacent ultrasonic flowmeters is measured. The measured propagation time is then compared with the propagation time when there is no water leak to determine whether there is a water leak between the two adjacent ultrasonic flowmeters.

[0003] Japanese Patent Application Laid-Open No. 2022-169885

[0004] However, in the above-mentioned conventional water leak detection system, the water leak detection operation is performed separately from the normal flow rate measurement operation, so there is a risk that the occurrence of a water leak may be overlooked depending on the interval at which the water leak detection is performed, and there is also the problem that the current consumption increases due to the increased number of times ultrasonic waves are sent and received.

[0005] Therefore, an object of the present disclosure is to provide a water leakage detection system that can reduce current consumption and improve the reliability of water leakage detection.

[0006] The water leak detection system disclosed herein is a water leak detection system comprising a plurality of flow meters provided at each customer's home in a water supply network, and a central device that manages the plurality of flow meters, wherein the flow meters comprise a flow measurement unit that measures the flow rate of water in a flow path of the water supply network, a pressure acquisition unit that acquires the water pressure in the flow path, a temperature acquisition unit that acquires the temperature of water in the flow path, and a communication unit that communicates with the central device, and the central device comprises a central communication unit that communicates with the communication unit, and a water leak determination unit that calculates a judgment pressure for determining whether or not there is a leak based on the temperature and water pressure acquired by each of the flow meters when the water flow rate by each of the plurality of flow meters in a target area for water leak testing is below a threshold and the flow rate flowing into the target area is below a threshold, and compares the calculated judgment pressure with a pre-stored reference pressure to determine whether or not there is a leak in the flow path.

[0007] According to the present disclosure, the water leak determination unit calculates a determination pressure for determining the presence or absence of a water leak based on the temperature and water pressure acquired by each flow meter, and compares the calculated determination pressure with a pre-stored reference pressure to determine the presence or absence of a water leak. This eliminates the need to transmit and receive ultrasonic waves during water leak detection, as in the past, thereby reducing current consumption. Furthermore, unlike conventional water leak detection systems that perform water leak detection separately from normal flow measurement, this system can constantly determine a water leak when the flow rate meets a predetermined condition. This reduces the risk of overlooking the occurrence of a water leak. As described above, the water leak detection system of the present disclosure can reduce current consumption and improve the reliability of water leak detection.

[0008] In the above disclosure, the flow meter is an ultrasonic flow meter comprising a pair of ultrasonic transmitter / receivers arranged in a measurement flow path and a propagation time measuring unit that measures the propagation time of ultrasonic waves between one of the ultrasonic transmitter / receivers and the other of the ultrasonic transmitter / receivers, wherein the flow rate measuring unit measures the flow rate of water based on the propagation time measured by the propagation time measuring unit, the pressure acquiring unit acquires the water pressure in the flow path based on a waveform related to the ultrasonic signal received by the other ultrasonic transmitter / receiver, and the temperature acquiring unit acquires the temperature of water in the flow path based on the propagation time measured by the propagation time measuring unit.

[0009] According to the above configuration, the pressure acquisition unit acquires the water pressure in the flow path based on the waveform of the ultrasonic signal received by the other ultrasonic transmitter / receiver, and the temperature acquisition unit acquires the water temperature in the flow path based on the propagation time measured by the propagation time measurement unit. Therefore, the water pressure and temperature can be acquired using parameters calculated in normal flow rate measurement (i.e., the waveform of the ultrasonic signal and the propagation time of the ultrasonic wave). This eliminates the need to separately provide a pressure sensor to detect water pressure and a temperature sensor to detect temperature.

[0010] FIG. 1 is a configuration diagram of a water supply network in one embodiment; FIG. 2 is a configuration diagram of an ultrasonic flow meter; FIG. 3 is a configuration diagram of a water leak detection system; FIG. 4 is a graph showing an example of the relationship between water pressure and water temperature; FIG. 5 is a diagram showing an example of an ultrasonic reception signal; and FIG. 6 is a flowchart showing the processing flow in the water leak detection system.

[0011] A water leak detection system according to an embodiment of the present disclosure will be described below with reference to the drawings. The water leak detection system described below is merely one embodiment of the present disclosure. Therefore, the present disclosure is not limited to the following embodiment, and additions, deletions, and modifications are possible within the scope of the present disclosure.

[0012] As shown in FIG. 1, the water leak detection system 100 of this embodiment includes a water supply station 51, a water supply network 60, one or more customer homes 56 included in a target area 57 for water leak inspection, and a center device 20.

[0013] The water supply network 60 is the area surrounded by a dashed line in Fig. 1 and is a network that supplies water from the water supply plant 51 to each customer's home 56 (identified as A to D in Fig. 1). In detail, the water supply network 60 includes a main pipe 52, a branch section 53, a common pipe 54, and a service pipe 55.

[0014] The water supply plant 51 and the branch section 53 are connected by a main pipe 52. A common pipe 54 branches off from the branch section 53. One of the common pipes 54 extends toward the target area 57, and multiple service pipes 55 branch off from the common pipe 54. The downstream ends of the multiple service pipes 55 are connected to each customer's home 56. In this configuration, water from the water supply plant 51 is supplied to each customer's home 56 via the main pipe 52, the branch section 53, the common pipe 54, and the service pipe 55. Each customer's home 56 is equipped with an ultrasonic flow meter 1 (Figure 2). The configuration of the ultrasonic flow meter 1 will be described in detail later.

[0015] The center device 20 communicates with each ultrasonic flowmeter 1 to receive meter reading data such as measured flow rates and to issue various instructions to each ultrasonic flowmeter 1. The communication method between the center device 20 and each ultrasonic flowmeter 1 is not particularly limited, and may be, for example, cellular communication, specified low-power wireless communication, or network communication via a relay station. The center device 20 includes a water leak determination unit 58 and a central communication unit 59. The central communication unit 59 communicates with a communication unit 9 (described below) included in each ultrasonic flowmeter 1. The water leak determination unit 58 determines whether or not there is a water leak in a flow path of the water supply network 60 based on the water temperature and water pressure in the flow path acquired by the ultrasonic flowmeter 1 in the consumer's home 56 via the central communication unit 59. The common pipe 54 and the service pipe 55 correspond to the flow path.

[0016] Next, the configuration of the ultrasonic flowmeter 1 will be described.

[0017] As shown in FIG. 2 , the ultrasonic flowmeter 1 includes a control unit 2, a flowmeter side unit 3, a propagation time measurement unit 4, a first ultrasonic transmitter / receiver 5, a second ultrasonic transmitter / receiver 6, a first reflecting unit 7, a second reflecting unit 8, a communication unit 9, a temperature acquisition unit 10, a pressure acquisition unit 11, and a memory unit 12.

[0018] The control unit 2 includes at least one of a processor such as a CPU and an integrated circuit such as an ASIC. The control unit 2 controls the operations of the first ultrasonic transmitter / receiver 5 and the second ultrasonic transmitter / receiver 6. The control unit 2 is electrically connected to a communication unit 9 and a storage unit 12. In this embodiment, the flowmeter unit 3, the propagation time measurement unit 4, the temperature acquisition unit 10, and the pressure acquisition unit 11 are functional components that are functionally realized when the control unit 2 executes a predetermined program.

[0019] The flow meter side unit 3 measures the water flow rate based on the propagation time measured by the propagation time measuring unit 4 described below based on the ultrasonic signal transmitted from one of the first ultrasonic transmitter / receiver 5 and the second ultrasonic transmitter / receiver 6 and received by the other ultrasonic transmitter / receiver.

[0020] The propagation time measurement unit 4 measures the propagation time of ultrasonic waves between one of the first ultrasonic transmitter / receiver 5 and the second ultrasonic transmitter / receiver 6 and the other ultrasonic transmitter / receiver. In this case, the propagation time measurement unit 4 identifies the zero-crossing point (see FIG. 5 ) at which the voltage of the amplified signal of the received signal received by the receiving ultrasonic transmitter / receiver changes from positive to negative for the first time after the voltage of the amplified signal exceeds a reference voltage. This zero-crossing point indicates the time when the ultrasonic waves transmitted by the transmitting ultrasonic transmitter / receiver are received by the receiving ultrasonic transmitter / receiver. The propagation time measurement unit 4 then measures the elapsed time from the application of the pulse wave (described below) to the zero-crossing point (i.e., the propagation time of the ultrasonic waves).

[0021] The temperature acquisition unit 10 acquires the temperature of the water in the flow path based on the propagation time measured by the propagation time measurement unit 4. The pressure acquisition unit 11 acquires the water pressure in the flow path based on the waveform of the ultrasonic signal received by the other of the first ultrasonic transmitter / receiver 5 and the second ultrasonic transmitter / receiver 6.

[0022] The measurement flow path 40 is a water flow path that extends in one direction and is provided inside the ultrasonic flowmeter 1. The first ultrasonic transmitter / receiver 5 is arranged on the upstream side of the outer surface of the measurement flow path 40, and transmits ultrasonic waves in the radial direction of the measurement flow path 40 and receives ultrasonic waves transmitted by the second ultrasonic transmitter / receiver 6. The second ultrasonic transmitter / receiver 6 is arranged on the downstream side of the outer surface of the measurement flow path 40, and transmits ultrasonic waves in the radial direction of the measurement flow path 40 and receives ultrasonic waves transmitted by the first ultrasonic transmitter / receiver 5.

[0023] The first reflecting unit 7 is disposed on the upstream side within the measurement flow path 40, and deflects the ultrasonic waves transmitted from the first ultrasonic transmitter / receiver 5 by 90 degrees in their traveling direction and reflects them toward the second reflecting unit 8. The first reflecting unit 7 also deflects the ultrasonic waves from the second reflecting unit 8 by 90 degrees in their traveling direction and reflects them toward the first ultrasonic transmitter / receiver 5. Similarly, the second reflecting unit 8 is disposed on the downstream side within the measurement flow path 40, and deflects the ultrasonic waves from the first reflecting unit 7 by 90 degrees in their traveling direction and reflects them toward the second ultrasonic transmitter / receiver 6. The second reflecting unit 8 also deflects the ultrasonic waves transmitted from the second ultrasonic transmitter / receiver 6 by 90 degrees in their traveling direction and reflects them toward the first reflecting unit 7.

[0024] The communication unit 9 communicates with external devices, including the general communication unit 59, and transmits and receives various data. The storage unit 12 is made up of various types of memory, a hard disk, or the like. The storage unit 12 stores thresholds to be compared with the flow rates measured by the ultrasonic flowmeters 1A to 1D (described below), and thresholds to be compared with the flow rate of water flowing through the common pipe 54. The storage unit 12 also stores information (e.g., a calculation formula or table) indicating the relationship between the amplitude of the received ultrasonic signal and water pressure, and information (e.g., a calculation formula or table) indicating the relationship between the propagation time measured by the propagation time measurement unit 4 and water temperature. In FIG. 2, the symbol FD indicates the direction of water flow, and the symbol PP indicates the propagation path of the ultrasonic waves.

[0025] In the above configuration, when measuring the flow rate of water, the control unit 2 applies a pulse wave to the first ultrasonic transmitter / receiver 5, causing the first ultrasonic transmitter / receiver 5 to emit an ultrasonic wave. The emitted ultrasonic wave propagates through the measurement flow path 40 along the propagation path PP via the first reflecting unit 7 and the second reflecting unit 8, and is then received by the second ultrasonic transmitter / receiver 6. Similarly, the control unit 2 applies a pulse wave to the second ultrasonic transmitter / receiver 6, causing the second ultrasonic transmitter / receiver 6 to emit an ultrasonic wave. The emitted ultrasonic wave propagates through the measurement flow path 40 along the propagation path PP via the second reflecting unit 8 and the first reflecting unit 7, and is then received by the first ultrasonic transmitter / receiver 5.

[0026] The propagation time measurement unit 4 measures the propagation time from the time when an ultrasonic wave is transmitted from the first ultrasonic transmitter / receiver 5 to the time when the ultrasonic wave is received by the second ultrasonic transmitter / receiver 6. The propagation time measurement unit 4 also measures the propagation time from the time when an ultrasonic wave is transmitted from the second ultrasonic transmitter / receiver 6 to the time when the ultrasonic wave is received by the first ultrasonic transmitter / receiver 5.

[0027] The flow velocity of the fluid (water) flowing in the direction FD within the measurement flow path 40 is defined as V, and the speed of sound in the fluid is defined as C. The length of the straight portion of the propagation path PP of the ultrasonic waves propagating between the first ultrasonic transmitter / receiver 5 and the second ultrasonic transmitter / receiver 6 is defined as L. In this case, the propagation time t1 during which the ultrasonic waves transmitted from the first ultrasonic transmitter / receiver 5 propagate a distance of length L within the propagation time until they reach the second ultrasonic transmitter / receiver 6 is expressed by the following mathematical formula 1.

[0028] (Math. 1) t1=L / (C+V)

[0029] Next, the propagation time t2 for the ultrasonic wave transmitted from the second ultrasonic transmitter / receiver 6 to reach the first ultrasonic transmitter / receiver 5 over a distance of length L is expressed by the following equation 2.

[0030] (Math. 2) t2=L / (CV)

[0031] By eliminating the sound velocity C of the fluid from the above formulas 1 and 2, the following formula 3 is obtained. As can be seen from the following formula 3, if L is known, the flow velocity V can be obtained using the measured propagation times t1 and t2.

[0032] (Math. 3) V=L / 2((1 / t1)-(1 / t2))

[0033] Next, as shown in the following formula 4, the flow rate Q can be obtained by multiplying the flow velocity V by the cross-sectional area S of the measurement flow path 40. In this way, the flow rate Q can be calculated. Note that k in the following formula 4 is a correction coefficient for correcting various errors that occur in the measurement.

[0034] (Equation 4) Q = k × (V × S)

[0035] The propagation time of ultrasonic waves between the first ultrasonic transmitter / receiver 5 and the second ultrasonic transmitter / receiver 6 includes the propagation time between the first ultrasonic transmitter / receiver 5 and the first reflecting unit 7 and the propagation time between the second ultrasonic transmitter / receiver 6 and the second reflecting unit 8, but these propagation times can basically be calculated independently of the flow velocity, so it is possible to determine only the propagation time of the portion of the propagation path PP with length L. In the following, unless otherwise specified, a case will be described in which ultrasonic waves transmitted from the first ultrasonic transmitter / receiver 5 are received by the second ultrasonic transmitter / receiver 6.

[0036] Next, the water leakage determination by the water leakage detection system 100 in the area 57 subject to water leakage inspection will be described with reference to the drawings.

[0037] In Figure 3, ultrasonic flowmeter 1A is an ultrasonic flowmeter corresponding to customer home A in target area 57 in Figure 1, ultrasonic flowmeter 1B is an ultrasonic flowmeter corresponding to customer home B, ultrasonic flowmeter 1C is an ultrasonic flowmeter corresponding to customer home C, and ultrasonic flowmeter 1D is an ultrasonic flowmeter corresponding to customer home D.

[0038] The ultrasonic flowmeter 1A is connected to the common pipe 54 by a lead-in pipe 55A, and the ultrasonic flowmeter 1B is connected to the common pipe 54 by a lead-in pipe 55B. The ultrasonic flowmeter 1C is connected to the common pipe 54 by a lead-in pipe 55C, and the ultrasonic flowmeter 1D is connected to the common pipe 54 by a lead-in pipe 55D. Branch points of the lead-in pipes 55A to 55C to the common pipe 54 are designated P1 to P3. The lead-in pipe 55D is connected to the downstream end P4 of the common pipe 54.

[0039] The piping path from ultrasonic flowmeter 1A to ultrasonic flowmeter 1B is designated as Lab, the piping path from ultrasonic flowmeter 1B to ultrasonic flowmeter 1C is designated as Lbc, and the piping path from ultrasonic flowmeter 1C to ultrasonic flowmeter 1D is designated as Lcd. Furthermore, the flow rates through the lead-in pipes 55A to 55D measured by the flow rate measuring units 3 of the ultrasonic flowmeters 1A to 1D are designated as q1 to q4, respectively. Furthermore, the flow rate at branch point P1 of the common pipe 54 is designated as Q1. The flow rate Q1 is the sum of the flow rates q1 to q4.

[0040] The water leakage determination unit 58 of the center device 20 receives the flow rates q1 to q4 from the ultrasonic flow meters 1A to 1D via the integrated communication unit 59. The water leakage determination unit 58 then determines whether the flow rates q1 to q4 from the ultrasonic flow meters 1A to 1D are equal to or less than the thresholds stored in the storage unit 12, and determines whether the flow rate flowing into the target district 57 (i.e., flow rate Q1) is equal to or less than the thresholds stored in the integrated communication unit 59. The water leakage determination unit 58 executes a process for determining whether or not there is a water leak when the flow rates q1 to q4 are equal to or less than the thresholds and equal to or less than the flow rate Q1 threshold.

[0041] In the process of determining whether or not there is a water leak, first, the pressure acquisition unit 11 of each of the ultrasonic flowmeters 1A to 1D acquires the water pressure in the inlet pipe 55 based on the waveform of the ultrasonic signal received by the second ultrasonic transmitter / receiver 6. In this case, the waveform of the ultrasonic signal is, for example, as shown in Figure 5, and the pressure acquisition unit 11 acquires the amplitude (for example, the maximum amplitude) from the waveform. Then, the pressure acquisition unit 11 acquires the water pressure corresponding to the amplitude based on information stored in advance in the storage unit 12.

[0042] Next, the temperature acquisition unit 10 of each of the ultrasonic flowmeters 1A to 1D acquires the water temperature in the lead-in pipe 55 based on the propagation time measured by the propagation time measurement unit 4. The temperature acquisition unit 10 acquires the water temperature corresponding to the propagation time based on information previously stored in the memory unit 12.

[0043] The water leakage determination unit 58 receives the water pressure and the water temperature from the ultrasonic flowmeters 1A to 1D via the integrated communication unit 59. Then, the water leakage determination unit 58 calculates a determination pressure for determining the presence or absence of a water leakage based on the temperature and water pressure acquired by the ultrasonic flowmeters 1A to 1D, and determines the presence or absence of a water leakage by comparing the calculated determination pressure with a pre-stored reference pressure.

[0044] Specifically, in FIG. 4, for example, the water pressure and water temperature at the time of installation of the ultrasonic flowmeter will be referred to as P0 and T0, respectively, and the acquired water pressure and water temperature will be referred to as P1 and T1, respectively. Hereinafter, the water pressure P0 at the time of installation will be referred to as the reference pressure, and the water temperature T0 at the time of installation will be referred to as the reference temperature. The water leak determination unit 58 corrects the water pressure P1 at the acquired water temperature T1 to the pressure at the reference temperature T0 based on Boyle's law. The pressure calculated by the correction is Pj in FIG. 4, which corresponds to the determination pressure. The water leak determination unit 58 determines that a water leak has occurred when the determination pressure Pj is lower than the reference pressure P0. The water leak determination unit 58 performs the above determination for each of the ultrasonic flowmeters 1A to 1D.

[0045] The water leak determination unit 58 calculates the difference between the determination pressure Pj and the reference pressure P0 for each of the ultrasonic flowmeters 1A to 1D, and determines that a water leak is occurring near the ultrasonic flowmeter with the largest difference. For example, if the difference related to the ultrasonic flowmeter 1A is the largest, it can be estimated that there is a high possibility that a water leak is occurring in the piping path Lab. If the difference related to the ultrasonic flowmeter 1B or the ultrasonic flowmeter 1C is the largest, it can be estimated that there is a high possibility that a water leak is occurring in the piping path Lbc. Furthermore, if the difference related to the ultrasonic flowmeter 1D is the largest, it can be estimated that there is a high possibility that a water leak is occurring in the piping path Lcd.

[0046] Next, a description will be given with reference to a flowchart of the processing flow in the water leak detection system 100. The water leak determination unit 58 exchanges information with each of the communication units 9 of the ultrasonic flowmeters 1A, 1B, 1C, and 1D via the general communication unit 59, thereby transmitting and receiving various instructions and various information.

[0047] 6, first, a start command is issued by the control unit 2 in each ultrasonic flowmeter 1 (step S1). Specifically, the control unit 2 applies a pulse wave to the first ultrasonic transmitter / receiver 5.

[0048] Next, a flow rate measurement subroutine is executed in each ultrasonic flowmeter 1 (step S2), thereby measuring the flow rate by each ultrasonic flowmeter 1. Next, the water leakage determination unit 58 of the center device 20 acquires the flow rate data from each ultrasonic flowmeter 1 via the integrated communication unit 59 (step S3).

[0049] Next, the water leakage determination unit 58 calculates the flow rate Q1 at the branch point P1 of the common pipe 54 based on the flow rate data from each ultrasonic flowmeter 1 (step S4). Then, the water leakage determination unit 58 determines whether the flow rates measured by each ultrasonic flowmeter 1 are equal to or less than the respective thresholds and whether the flow rate Q1 is equal to or less than the respective thresholds (step S5). If the conditions that the flow rates measured by each ultrasonic flowmeter 1 are equal to or less than the respective thresholds and the flow rate Q1 is equal to or less than the respective thresholds are not met (No in step S5), an interval setting command is issued (step S12), and then the processing from step S1 onwards is repeated.

[0050] On the other hand, if the flow rates measured by each ultrasonic flowmeter 1 are equal to or less than the threshold and the flow rate Q1 is equal to or less than the threshold (Yes in step S5), the pressure acquisition unit 11 of each ultrasonic flowmeter 1 calculates the water pressure in the inlet pipe 55 based on the waveform of the ultrasonic signal (step S6). Then, the temperature acquisition unit 10 of each ultrasonic flowmeter 1 calculates the water temperature in the inlet pipe 55 based on the propagation time measured by the propagation time measurement unit 4 (step S7).

[0051] Next, the water leak determination unit 58 acquires the water pressure data obtained by the pressure acquisition unit 11 and the water temperature data obtained by the temperature acquisition unit 10 of each ultrasonic flowmeter 1 via the integrated communication unit 59 in order to execute the process of determining whether or not there is a water leak (step S8). Then, the water leak determination unit 58 calculates the difference between the determination pressure Pj and the reference pressure P0 using the method described above in FIG. 4 (step S9). If it is determined as a result of the process in step S9 that there is a possibility of a water leak (Yes in step S10), the water leak determination unit 58 outputs an alarm command (step S11) and ends the process. On the other hand, if it is determined that there is no possibility of a water leak (No in step S10), after issuing an interval setting command (step S13), the process from step S1 onwards is repeated.

[0052] As described above, in the water leak detection system 100 of this embodiment, the water leak determination unit 58 calculates a determination pressure for determining the presence or absence of a water leak based on the temperature and water pressure acquired by each ultrasonic flowmeter, and compares the calculated determination pressure with a pre-stored reference pressure to determine the presence or absence of a water leak. Therefore, unlike conventional water leak detection systems that perform water leak detection operations separately from normal flow measurement operations, the water leak detection system 100 can constantly determine a water leak when the flow rate satisfies a predetermined condition. This reduces the risk of overlooking the occurrence of a water leak. As described above, the water leak detection system 100 can reduce current consumption and improve the reliability of water leak detection.

[0053] In this embodiment, the pressure acquisition unit 11 acquires the water pressure based on the waveform of the ultrasonic signal received by the receiving ultrasonic transmitter / receiver of the first ultrasonic transmitter / receiver 5 and the second ultrasonic transmitter / receiver 6, and the temperature acquisition unit 10 acquires the water temperature based on the propagation time measured by the propagation time measurement unit 4. Therefore, the water pressure and water temperature can be acquired using parameters calculated in normal flow rate measurement (i.e., the waveform of the ultrasonic signal and the propagation time of the ultrasonic waves). This eliminates the need to separately provide a pressure sensor for detecting the water pressure and a temperature sensor for detecting the water temperature.

[0054] (Modifications) The present disclosure is not limited to the above-described embodiment, and various modifications are possible without departing from the gist of the present disclosure. For example, the following modifications are possible.

[0055] In the above embodiment, the ultrasonic flowmeter 1 is used as the flowmeter, but any flowmeter capable of measuring the flow rate of water is usable as long as it is capable of measuring the flow rate of water. In this case, a temperature sensor that detects water temperature may be provided in place of the temperature acquisition unit 10 in the ultrasonic flowmeter 1, and a pressure sensor that detects water pressure may be provided in place of the pressure acquisition unit 11 in the ultrasonic flowmeter 1.

[0056] Furthermore, in the above embodiment, the water leakage determination unit 58 determines the presence or absence of a water leakage based on the water temperature acquired by the temperature acquisition unit 10 and the water pressure acquired by the pressure acquisition unit 11, but this is not limited to this. The water leakage determination unit 58 can also determine the presence or absence of a water leakage based on information correlating with the water temperature (for example, the propagation time of ultrasonic waves) and information correlating with the water pressure (for example, the amplitude of the ultrasonic reception signal) instead of the water temperature and the water pressure.

[0057] In addition, in the above embodiment, the water leakage determination unit 58 is provided in the center device 20, but this is not limited to this, and the water leakage determination unit 58 may also be provided in one of the multiple ultrasonic flow meters 1 installed in the target area 57.

[0058] The installation location of the center device 20 is not particularly limited, and it may be installed next to the water supply station 51, for example.

[0059] In the above embodiment, the cross-sectional area of ​​the common pipe 54 is generally constant, and the flow rate decreases toward the downstream side. Therefore, the flow rate at the branch point P1 may be used as the flow rate of the common pipe 54.

[0060] In addition, in the above embodiment, four ultrasonic flow meters 1 are connected to the common pipe 54, but this is not limited to this, and the number of ultrasonic flow meters 1 connected to the common pipe 54 may be, for example, three or less, or five or more.

[0061] In addition, in the above embodiment, the ultrasonic flowmeter 1 is provided with two reflecting sections, the first reflecting section 7 and the second reflecting section 8, but this is not limited to this, and the number of reflecting sections may be, for example, one or three or more.

[0062] Furthermore, although the above embodiment has been described taking a water leak as an example, factors that affect the propagation time, such as the inclusion of air bubbles or foreign matter, can also be detected in the same way.

[0063] DESCRIPTION OF SYMBOLS 1, 1A, 1B, 1C, 1D Ultrasonic flowmeter 2 Control unit 3 Flowmeter side unit 4 Propagation time measurement unit 5 First ultrasonic transmitter / receiver 6 Second ultrasonic transmitter / receiver 7 First reflection unit 8 Second reflection unit 9 Communication unit 10 Temperature acquisition unit 11 Pressure acquisition unit 12 Memory unit 20 Center device 40 Measurement flow path 54 Common piping 55 Intake pipe 56 Customer's house 57 Target area 58 Water leak determination unit 59 Integrated communication unit 60 Water supply network 100 Water leak detection system

Claims

1. A water leak detection system comprising a plurality of flow meters provided at each consumer's residence in a water supply network, and a central device that manages the plurality of flow meters, wherein the flow meters comprise: a flow measurement unit that measures the flow rate of water in a flow path of the water supply network, a pressure acquisition unit that acquires the water pressure in the flow path, a temperature acquisition unit that acquires the temperature of water in the flow path, and a communication unit that communicates with the central device, wherein the central device comprises: a central communication unit that communicates with the communication unit, and a leakage determination unit that calculates a determination pressure for determining the presence or absence of a leakage based on the temperature and the water pressure acquired by each of the flow meters when the water flow rates by each of the plurality of flow meters in a target area for leakage inspection are each below a threshold value and the flow rate flowing into the target area is below a threshold value, and compares the calculated determination pressure with a pre-stored reference pressure to determine the presence or absence of a leakage in the flow path.

2. The flow meter is an ultrasonic flow meter comprising a pair of ultrasonic transmitters and receivers arranged in a measurement flow path and a propagation time measuring unit that measures the propagation time of ultrasonic waves between one of the ultrasonic transmitters and the other of the ultrasonic transmitters, wherein the flow rate measuring unit measures the flow rate of water based on the propagation time measured by the propagation time measuring unit, the pressure acquiring unit acquires the water pressure in the flow path based on a waveform related to an ultrasonic signal received by the other ultrasonic transmitter and receiver, and the temperature acquiring unit acquires the temperature of water in the flow path based on the propagation time measured by the propagation time measuring unit. The water leak detection system described in claim 1.

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