Abnormality detection system

Abstract

This abnormality detection system comprises a flow meter including: a pair of ultrasonic transceivers provided to a measurement flow path; a high-frequency ultrasonic transceiver unit that causes one of the ultrasonic transceivers to transmit a high-frequency ultrasonic wave and receives a high-frequency ultrasonic signal based on the high-frequency ultrasonic wave received by the other ultrasonic transceiver; a low-frequency ultrasonic transceiver unit that causes one of the ultrasonic transceivers to transmit a low-frequency ultrasonic wave and receives a low-frequency ultrasonic signal based on the low-frequency ultrasonic wave received by the other ultrasonic transceiver; a flow rate measurement unit that measures the flow rate of water in the measurement flow path on the basis of the high-frequency ultrasonic signal; and an inter-meter propagation time measurement unit that measures the propagation time of the low-frequency ultrasonic wave in the flow path between one flow meter and another flow meter adjacent to each other in a water supply network on the basis of the low-frequency ultrasonic signal.

Description

Anomaly Detection System

[0001] The present disclosure relates to anomaly detection systems.

[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.

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

[0004] However, in the conventional water leak detection system, the ultrasonic waves for measuring flow rate are also used for water leak detection, which limits the range of ultrasonic waves propagating through the piping between adjacent ultrasonic flow meters, resulting in a problem of poor accuracy in water leak detection for the piping.

[0005] Therefore, an object of the present disclosure is to provide an anomaly detection system that can improve the accuracy of detecting an anomaly such as a water leak.

[0006] The anomaly detection system of the present disclosure is an anomaly detection system including a plurality of flow meters provided in a water supply network and a central device that manages the plurality of flow meters, wherein the flow meters include a pair of ultrasonic transmitters and receivers provided in a measurement flow path, a high-frequency ultrasonic transmitter and receiver unit that causes one of the ultrasonic transmitters and receivers to transmit high-frequency ultrasonic waves and receives a high-frequency ultrasonic signal based on the high-frequency ultrasonic waves received by the other ultrasonic transmitter and receiver, a low-frequency ultrasonic transmitter and receiver unit that causes one of the ultrasonic transmitter and receivers to transmit low-frequency ultrasonic waves and receives a low-frequency ultrasonic signal based on the low-frequency ultrasonic waves received by the other ultrasonic transmitter and receiver, a flow rate measurement unit that measures the flow rate of water in the measurement flow path based on the high-frequency ultrasonic signal, and a low-frequency ultrasonic transmitter and receiver unit that receives the low-frequency ultrasonic signal. Based on this, the water supply network is equipped with an inter-meter propagation time measuring unit that measures the propagation time of the low-frequency ultrasonic waves in the flow path between one adjacent flow meter and the other adjacent flow meter, and a communication unit that communicates with the center device, and the center device is equipped with a central communication unit that communicates with the communication unit, and the central processing unit, and the central processing unit performs a process of acquiring the propagation time via the central communication unit, and a process of determining whether or not there is an abnormality based on a comparison of the propagation time acquired via the central communication unit with the propagation time when there is no abnormality, when the water flow rate from each of the plurality of flow meters in the area subject to abnormality inspection is below a threshold and the flow rate flowing into the target area is below a threshold.

[0007] According to the present disclosure, the flow rate measurement unit measures the water flow rate in the measurement flow path based on a high-frequency ultrasonic signal. Because high-frequency ultrasonic waves are used during flow rate measurement, the short wavelength of the ultrasonic waves narrows the beam angle (the angle at which the ultrasonic waves spread), making it easier to capture the water flow using the ultrasonic waves. As a result, the accuracy of the propagation time is improved, thereby improving the accuracy of the flow rate measurement. Meanwhile, the inter-meter propagation time measurement unit measures the propagation time of ultrasonic waves in the flow path between adjacent flow meters in the water supply network based on a low-frequency ultrasonic signal. Thus, low-frequency ultrasonic waves are used during water leak detection. Low-frequency ultrasonic waves are less susceptible to attenuation than high-frequency ultrasonic waves and have a wider beam angle, so they easily propagate from one flow meter to the other flow meter through the flow path. Therefore, the propagation time of ultrasonic waves between one flow meter and the other flow meter can be obtained with high accuracy. This improves the accuracy of detecting abnormalities, such as water leaks, in the flow path between one flow meter and the other flow meter based on the propagation time.

[0008] The anomaly detection system of the present disclosure is an anomaly detection system including a plurality of flow meters provided in a water supply network and a central device that manages the plurality of flow meters, wherein the flow meters include a pair of ultrasonic transmitters and receivers provided in a measurement flow path, a high-frequency ultrasonic transmitter and receiver unit that causes one of the ultrasonic transmitters and receivers to transmit high-frequency ultrasonic waves and receives a high-frequency ultrasonic signal based on the high-frequency ultrasonic waves received by the other ultrasonic transmitter and receiver, a low-frequency ultrasonic transmitter and receiver unit that causes one of the ultrasonic transmitter and receivers to transmit low-frequency ultrasonic waves and receives a low-frequency ultrasonic signal based on the low-frequency ultrasonic waves received by the other ultrasonic transmitter and receiver, a flow rate measurement unit that measures the flow rate of water in the measurement flow path based on the high-frequency ultrasonic signal, and a low-frequency ultrasonic signal receiver unit that receives the low-frequency ultrasonic signal. The water supply network is equipped with an ultrasonic signal processing unit that acquires the propagation waveform of the low-frequency ultrasonic wave in the flow path between one of the flow meters and the other of the flow meters adjacent to each other in the water supply network based on a signal, and a communication unit that communicates with the center device, and the center device is equipped with a central communication unit that communicates with the communication unit, and the central processing unit, and the central processing unit executes a process of acquiring the propagation waveform via the central communication unit, and a process of determining whether or not there is an abnormality based on a comparison of the propagation waveform acquired via the central communication unit with the propagation waveform when there is no abnormality, when the water flow rate from each of the plurality of flow meters in the area subject to abnormality inspection is below a threshold and the flow rate flowing into the area subject to abnormality inspection is below a threshold.

[0009] According to the present disclosure, the flow rate measurement unit measures the water flow rate in the measurement flow path based on the high-frequency ultrasonic signal. Because high-frequency ultrasonic waves are used during flow rate measurement, the short wavelength of the ultrasonic waves narrows the beam angle (the angle at which the ultrasonic waves spread), making it easier to capture the water flow using the ultrasonic waves. As a result, the accuracy of the propagation time is improved, thereby improving the accuracy of the flow rate measurement. Meanwhile, the ultrasonic signal processing unit acquires the propagation waveform of low-frequency ultrasonic waves in the flow path between adjacent flow meters in the water supply network based on the low-frequency ultrasonic signal. Thus, low-frequency ultrasonic waves are used during water leak detection. Because low-frequency ultrasonic waves are less susceptible to attenuation than high-frequency ultrasonic waves and have a wider beam angle, they easily propagate from one flow meter to the other flow meter through the flow path. Therefore, the propagation waveform of ultrasonic waves between one flow meter and the other flow meter can be acquired with high accuracy. This improves the accuracy of detecting abnormalities, such as water leaks, in the flow path between one flow meter and the other flow meter based on the propagation waveform.

[0010] In the above disclosure, the flow path between the one flow meter and the other flow meter may be formed by a circular pipe, and the wavelength of the low-frequency ultrasonic wave may be longer than the diameter of the circular pipe.

[0011] According to the above configuration, low frequency ultrasonic waves are easily transmitted through the flow path.

[0012] In the above disclosure, the pair of ultrasonic transmitter-receivers may have a resonant frequency in a first frequency range including the frequency of the high frequency ultrasonic waves or a second frequency range including the frequency of the low frequency ultrasonic waves.

[0013] According to the above configuration, it is possible to improve the transmission and reception sensitivity of the ultrasonic transmitter and receiver for both high-frequency and low-frequency ultrasonic waves. Therefore, the use of high-frequency ultrasonic waves improves the accuracy of flow rate measurement, and the use of low-frequency ultrasonic waves improves the accuracy of water leak detection.

[0014] In the above disclosure, the low-frequency ultrasonic transmitter / receiver unit in one of the adjacent flow meters in the water supply network causes the one ultrasonic transmitter / receiver to transmit the low-frequency ultrasonic waves periodically and continuously for a predetermined period of time, and the ultrasonic signal processing unit in the other of the adjacent flow meters receives the propagation waveform of the low-frequency ultrasonic waves transmitted from the one ultrasonic transmitter / receiver in the one flow meter via a flow path in the water supply network, compares the received propagation waveform of the low-frequency ultrasonic waves with a predetermined propagation waveform, and determines that an abnormality has occurred if the propagation waveform of the low-frequency ultrasonic waves and the predetermined propagation waveform are not identical for a predetermined period of time.

[0015] According to the above configuration, the ultrasonic signal processing unit compares the propagation waveform of the low-frequency ultrasonic wave with a predetermined propagation waveform, and determines that an abnormality has occurred if the propagation waveform of the low-frequency ultrasonic wave does not match the predetermined propagation waveform for a predetermined period of time. This makes it possible to accurately determine the presence or absence of an abnormality such as a water leak on a flow meter-by-flow meter basis.

[0016] According to the present disclosure, it is possible to provide an anomaly detection system that can improve the accuracy of detecting an anomaly such as a water leak.

[0017] FIG. 6A is a configuration diagram of a water supply network in one embodiment. FIG. 6B is a diagram showing an example of the configuration of an ultrasonic flowmeter. FIG. 3A is a schematic diagram showing the propagation mode of high-frequency ultrasonic waves, and FIG. 3B is a schematic diagram showing the propagation mode of low-frequency ultrasonic waves. FIG. 6A is a diagram showing an example of the configuration of an ultrasonic flowmeter. FIG. 6B is a diagram showing an example of the transmission waveform and reception waveform of ultrasonic waves under normal conditions, and FIG. 6B is a diagram showing an example of the transmission waveform and reception waveform of ultrasonic waves under abnormal conditions.

[0018] An anomaly detection system according to an embodiment of the present disclosure will be described below with reference to the drawings. The anomaly 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.

[0019] (First embodiment) As shown in Figure 1, the anomaly detection system 100 of this embodiment includes a water supply plant 51, a water supply network 60, one or more customer homes 56 included in a target area 57 for anomaly inspection such as water leakage, and a center device 20.

[0020] 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). The water supply network 60 includes a main pipe 52, a branch section 53, a common pipe 54, and a service pipe 55.

[0021] A water supply plant 51 and a branching section 53 are connected by a main pipe 52. A common pipe 54 branches off from the branching section 53. One of the common pipes 54 extends toward a target area 57, and multiple inlet pipes 55 branch off from the common pipe 54. The downstream ends of the multiple inlet pipes 55 are connected to consumer homes 56. In this configuration, water from the water supply plant 51 is supplied to each consumer home 56 via the main pipe 52, the branching section 53, the common pipe 54, and the inlet pipe 55. Each consumer home 56 is equipped with an ultrasonic flowmeter 1 ( FIG. 2 ), which corresponds to a flow meter. FIG. 1 and FIG. 4 (described later) illustrate four consumer homes 56, namely, consumer homes 56A, 56B, 56C, and 56D, and in FIG. 4 , the ultrasonic flowmeters 1 for the consumer homes 56A, 56B, 56C, and 56D are identified as ultrasonic flowmeters 1A, 1B, 1C, and 1D, respectively. A detailed description will be given later of the configuration of the ultrasonic flowmeter 1. The common pipe 54 and the lead-in pipe 55 correspond to a flow path between one flowmeter and the other flowmeter.

[0022] The center device 20 manages a plurality of ultrasonic flowmeters 1. The center device 20 includes a central processing unit 58 and a central communication unit 59. The center device 20 receives meter reading data such as measured flow rates by communicating with each ultrasonic flowmeter 1, and has the function of issuing 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 central communication unit 59 communicates with a communication unit 9 (described later) included in each ultrasonic flowmeter 1. The central processing unit 58 determines the presence or absence of an abnormality such as a water leak (water leak, foreign matter contamination, etc.) based on the propagation time of ultrasonic waves obtained from the ultrasonic flowmeter 1 via the central communication unit 59. Details will be described later.

[0023] Next, the configuration of the ultrasonic flowmeter 1 will be described. As shown in Fig. 2, the ultrasonic flowmeter 1 includes a control unit 2, a flowmeter unit 3, a meter-to-meter propagation time measurement unit 4, a first ultrasonic transceiver 5, a second ultrasonic transceiver 6, a first reflecting unit 7, a second reflecting unit 8, a communication unit 9, a memory unit 12, a low-frequency ultrasonic transceiver circuit 13, a high-frequency ultrasonic transceiver circuit 14, and a measurement flow path 40. In this embodiment, the low-frequency ultrasonic transceiver circuit 13 corresponds to the low-frequency ultrasonic transceiver unit, and the high-frequency ultrasonic transceiver circuit 14 corresponds to the high-frequency ultrasonic transceiver unit. In Fig. 2, the symbol FD indicates the direction of water flow, and the symbol PP indicates the propagation path of the ultrasonic waves.

[0024] 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 and the inter-meter propagation time measurement unit 4 are functional components that are functionally realized when the control unit 2 executes a predetermined program.

[0025] The measurement flow path 40 is a water flow path that is provided inside the ultrasonic flowmeter 1 and extends in one direction. The first ultrasonic transmitter / receiver 5 is disposed 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 while receiving ultrasonic waves similarly transmitted by the second ultrasonic transmitter / receiver 6. The second ultrasonic transmitter / receiver 6 is disposed 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 while receiving ultrasonic waves similarly transmitted by the first ultrasonic transmitter / receiver 5.

[0026] The low-frequency ultrasonic transmitter / receiver circuit 13 is electrically connected to the control unit 2, the first ultrasonic transmitter / receiver 5, and the second ultrasonic transmitter / receiver 6. When a water leak is detected in the common pipe 54 or the lead-in pipe 55 based on an instruction from the control unit 2, the low-frequency ultrasonic transmitter / receiver circuit 13 causes one of the first ultrasonic transmitter / receiver 5 and the second ultrasonic transmitter / receiver 6 to transmit a low-frequency ultrasonic wave. The low-frequency ultrasonic transmitter / receiver circuit 13 also receives a low-frequency ultrasonic signal based on the low-frequency ultrasonic wave received by the other of the first ultrasonic transmitter / receiver 5 and the second ultrasonic transmitter / receiver 6. The low-frequency ultrasonic wave may be, for example, an ultrasonic wave having a frequency of 200 kHz or less.

[0027] The high-frequency ultrasonic transmitter / receiver circuit 14 is electrically connected to the control unit 2, the first ultrasonic transmitter / receiver 5, and the second ultrasonic transmitter / receiver 6. Based on instructions from the control unit 2, the high-frequency ultrasonic transmitter / receiver circuit 14 causes one of the first ultrasonic transmitter / receiver 5 and the second ultrasonic transmitter / receiver 6 to transmit high-frequency ultrasonic waves when measuring the flow rate of water in the measurement flow path 40. The high-frequency ultrasonic transmitter / receiver circuit 14 also receives a high-frequency ultrasonic signal based on the high-frequency ultrasonic waves received by the other of the first ultrasonic transmitter / receiver 5 and the second ultrasonic transmitter / receiver 6. The high-frequency ultrasonic waves may be, for example, ultrasonic waves with a frequency of 1 MHz or higher.

[0028] The first ultrasonic transmitter / receiver 5 and the second ultrasonic transmitter / receiver 6 have resonant frequencies near the frequency of the high-frequency ultrasonic waves or near the frequency of the low-frequency ultrasonic waves. In this case, the first ultrasonic transmitter / receiver 5 and the second ultrasonic transmitter / receiver 6 have resonant frequencies in a first frequency range that includes the frequency of the high-frequency ultrasonic waves or a second frequency range that includes the frequency of the low-frequency ultrasonic waves. When detecting a water leak, the low-frequency ultrasonic transmitter / receiver circuit 13 applies an AC voltage having a frequency within the second frequency range to the not-shown piezoelectric element provided in the first ultrasonic transmitter / receiver 5 or the not-shown piezoelectric element provided in the second ultrasonic transmitter / receiver 6. On the other hand, when measuring a flow rate, the high-frequency ultrasonic transmitter / receiver circuit 14 applies an AC voltage having a frequency within the first frequency range to the not-shown piezoelectric element provided in the first ultrasonic transmitter / receiver 5 or the not-shown piezoelectric element provided in the second ultrasonic transmitter / receiver 6.

[0029] A first reflecting unit 7 and a second reflecting unit 8 are provided in the measurement flow path 40. The first reflecting unit 7 is disposed upstream in 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 downstream in 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.

[0030] The flow meter side section 3 measures the flow rate of water in the measurement flow path 40 based on the propagation time of high-frequency ultrasonic waves 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.

[0031] 2 and 3A, during flow rate measurement, high-frequency ultrasonic waves transmitted from the first ultrasonic transmitter / receiver 5 propagate through the measurement flow path 40 via the first reflecting portion 7 and the second reflecting portion 8 along the propagation path PP, and are then received by the second ultrasonic transmitter / receiver 6. Similarly, high-frequency ultrasonic waves transmitted from the second ultrasonic transmitter / receiver 6 propagate through the measurement flow path 40 via the second reflecting portion 8 and the first reflecting portion 7 along the propagation path PP, and are then received by the first ultrasonic transmitter / receiver 5. Note that high-frequency ultrasonic waves are easily attenuated. Therefore, as shown in FIG. 3A, high-frequency ultrasonic waves are unlikely to propagate through the common pipe 54 and the inlet pipe 55 between adjacent ultrasonic flow meters 1 in the water supply network 60.

[0032] The flowmeter unit 3 measures the propagation time from the time when high-frequency ultrasonic waves are transmitted from the first ultrasonic transmitter / receiver 5 to the time when the ultrasonic waves are received by the second ultrasonic transmitter / receiver 6. The flowmeter unit 3 also measures the propagation time from the time when high-frequency ultrasonic waves are transmitted from the second ultrasonic transmitter / receiver 6 to the time when the ultrasonic waves are received by the first ultrasonic transmitter / receiver 5.

[0033] Here, the flow velocity of water flowing in the direction FD within the measurement flow path 40 is denoted by V, and the speed of sound in water is denoted by C. The length of the straight portion of the propagation path PP of the ultrasonic waves propagating between the first ultrasonic transceiver 5 and the second ultrasonic transceiver 6 is denoted by L. In this case, the propagation time t1 during which the ultrasonic waves transmitted from the first ultrasonic transceiver 5 propagate a distance of length L until they reach the second ultrasonic transceiver 6 is expressed by the following mathematical formula 1.

[0034] (Math. 1) t1=L / (C+V)

[0035] 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.

[0036] (Math. 2) t2=L / (CV)

[0037] 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.

[0038] (Math. 3) V=L / 2((1 / t1)-(1 / t2))

[0039] 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. Note that k in the following formula 4 is a correction coefficient for correcting various errors that occur in the measurement.

[0040] (Equation 4) Q = k × (V × S)

[0041] By performing the calculations as described above, the flow meter unit 3 obtains the flow rate Q of water in the measurement flow path 40. 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. In this case, since the propagation time can basically be calculated independently of the flow velocity, the sum of the propagation time and the propagation time obtained by the above formula is set to be the propagation time of ultrasonic waves between the first ultrasonic transmitter / receiver 5 and the second ultrasonic transmitter / receiver 6.

[0042] The meter-to-meter propagation time measuring unit 4 in one of the adjacent ultrasonic flowmeters 1 in the water supply network 60 measures the propagation time of ultrasonic waves in the common piping 54 and inlet pipe 55 between the one ultrasonic flowmeter 1 and the other ultrasonic flowmeter 1 based on low-frequency ultrasonic waves emitted from the first ultrasonic transmitter / receiver 5 etc. in the other ultrasonic flowmeter 1 and received by the first ultrasonic transmitter / receiver 5 etc. in the one ultrasonic flowmeter 1.

[0043] In this case, low-frequency ultrasonic waves emitted from the first ultrasonic transmitter / receiver 5 of one of the ultrasonic flowmeters 1 adjacent to one another in the water supply network 60 are less likely to attenuate than high-frequency ultrasonic waves. As a result, as shown in Figures 2 and 3B, the low-frequency ultrasonic waves propagate from the measurement flow path 40 of one of the ultrasonic flowmeters 1 through the common pipe 54 and the inlet pipe 55 to the measurement flow path 40 of the other ultrasonic flowmeter 1, and are received by the second ultrasonic transmitter / receiver 6 of the other ultrasonic flowmeter 1. Similarly, low-frequency ultrasonic waves emitted from the second ultrasonic transmitter / receiver 6 of the other ultrasonic flowmeter 1 propagate from the measurement flow path 40 of the other ultrasonic flowmeter 1 through the common pipe 54 and the inlet pipe 55 to the measurement flow path 40 of one of the ultrasonic flowmeters 1. The low-frequency ultrasonic waves are then received by the first ultrasonic transmitter / receiver 5 of one of the ultrasonic flowmeters 1.

[0044] The communication unit 9 communicates with external devices such as the general communication unit 59, and transmits and receives various data. The storage unit 12 is composed of various memories or a hard disk, and stores threshold values ​​to be compared with the flow rates measured by the ultrasonic flowmeters 1A to 1D and threshold values ​​to be compared with the flow rate of water flowing through the common pipe 54.

[0045] Next, the abnormality determination by the abnormality detection system 100 in the target area 57 for abnormality inspection will be described with reference to the drawings.

[0046] In Figure 4, 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.

[0047] 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 as P1 to P3. The lead-in pipe 55D is connected to the downstream end P4 of the common pipe 54.

[0048] 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.

[0049] As described above, the inter-meter propagation time measuring unit 4 in one of the adjacent ultrasonic flowmeters 1 measures the propagation time of ultrasonic waves in the common pipe 54 and the inlet pipe 55 between the one ultrasonic flowmeter 1 and the other ultrasonic flowmeter 1. Specifically, in the example of Fig. 4, the inter-meter propagation time measuring unit 4 of the ultrasonic flowmeter 1A measures the propagation time of ultrasonic waves in the common pipe 54 and the inlet pipe 55 between the ultrasonic flowmeter 1A and the ultrasonic flowmeter 1B. Furthermore, the inter-meter propagation time measuring unit 4 of the ultrasonic flowmeter 1B measures the propagation time of ultrasonic waves in the common pipe 54 and the inlet pipe 55 between the ultrasonic flowmeter 1B and the ultrasonic flowmeter 1C. The inter-meter propagation time measuring unit 4 of the ultrasonic flowmeter 1B measures the propagation time of ultrasonic waves in the common pipe 54 and the inlet pipe 55 between the ultrasonic flowmeter 1B and the ultrasonic flowmeter 1A. Furthermore, the inter-meter propagation time measuring unit 4 of the ultrasonic flowmeter 1C measures the propagation time of ultrasonic waves in the common pipe 54 and the lead-in pipe 55 between the ultrasonic flowmeter 1C and the ultrasonic flowmeter 1D. The inter-meter propagation time measuring unit 4 of the ultrasonic flowmeter 1C measures the propagation time of ultrasonic waves in the common pipe 54 and the lead-in pipe 55 between the ultrasonic flowmeter 1C and the ultrasonic flowmeter 1B. Furthermore, the inter-meter propagation time measuring unit 4 of the ultrasonic flowmeter 1D measures the propagation time of ultrasonic waves in the common pipe 54 and the lead-in pipe 55 between the ultrasonic flowmeter 1D and the ultrasonic flowmeter 1C.

[0050] The central processing unit 58 of the center device 20 receives the flow rates q1 to q4 from the ultrasonic flow meters 1A to 1D via the central communication unit 59. The central processing unit 58 then determines whether the flow rates q1 to q4 measured by the ultrasonic flow meters 1A to 1D are equal to or less than a threshold value, and determines whether the flow rate flowing into the target district 57 (i.e., flow rate Q1) is equal to or less than a threshold value stored in the central communication unit 59. The central processing 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 a threshold value and are equal to or less than the flow rate Q1 threshold value.

[0051] The central device 20 is provided with a storage unit (not shown). The storage unit of the central device 20 stores threshold values ​​to be compared with the flow rates measured by the ultrasonic flowmeters 1A to 1D, and threshold values ​​to be compared with the flow rate of water flowing through the common pipe 54. The storage unit of the central device 20 also stores propagation times when there is no abnormality, which correspond to the propagation times measured by each inter-meter propagation time measuring unit 4. Specifically, the storage unit of the central device 20 stores, as propagation times when there is no abnormality, the propagation time of ultrasonic waves between the ultrasonic flowmeter 1A and the ultrasonic flowmeter 1B, the propagation time of ultrasonic waves between the ultrasonic flowmeter 1B and the ultrasonic flowmeter 1C, and the propagation time of ultrasonic waves between the ultrasonic flowmeter 1C and the ultrasonic flowmeter 1D, etc.

[0052] The overall processing unit 58 acquires the above-mentioned propagation times from the inter-meter propagation time measurement units 4 of the ultrasonic flowmeters 1A to 1D via the overall communication unit 59. The overall processing unit 58 determines the presence or absence of an abnormality (such as the presence or absence of a water leak) based on a comparison between the acquired propagation times and the propagation times when no abnormality exists. In this case, the overall processing unit 58 can determine that a water leak has occurred near the ultrasonic flowmeter 1 where the difference between the acquired propagation times and the propagation times when no abnormality exists is the largest. For example, if the difference between the propagation times measured by the inter-meter propagation time measurement unit 4 of the ultrasonic flowmeter 1A after ultrasonic waves are transmitted from the ultrasonic flowmeter 1B is the largest, it is estimated that there is a high possibility that a water leak has occurred in the piping path Lab. Alternatively, if the difference between the propagation times measured by the inter-meter propagation time measurement unit 4 of the ultrasonic flowmeter 1C after ultrasonic waves are transmitted from the ultrasonic flowmeter 1B is the largest, it is estimated that there is a high possibility that a water leak has occurred in the piping path Lbc.

[0053] As described above, according to the anomaly detection system 100 of this embodiment, the flow rate measurement unit 3 measures the water flow rate in the measurement flow path 40 based on the high-frequency ultrasonic signal. Because high-frequency ultrasonic waves are used during flow rate measurement, the short wavelength of the ultrasonic waves narrows the beam angle, making it easier to capture the water flow using ultrasonic waves. As a result, the accuracy of the propagation time is improved, thereby improving the accuracy of the flow rate measurement. Meanwhile, the inter-meter propagation time measurement unit 4 measures the propagation time of ultrasonic waves in the flow path between adjacent ultrasonic flow meters 1 in the water supply network 60 based on the low-frequency ultrasonic signal. Thus, low-frequency ultrasonic waves are used during water leak detection. Low-frequency ultrasonic waves are less susceptible to attenuation than high-frequency ultrasonic waves and have a wider beam angle, so they easily propagate from one ultrasonic flow meter 1 to the other ultrasonic flow meter 1 through the flow path. Therefore, the propagation time of ultrasonic waves between one ultrasonic flow meter 1 and the other ultrasonic flow meter 1 can be obtained with high accuracy. Therefore, the accuracy of detecting an abnormality such as a water leak in the flow path between one ultrasonic flowmeter 1 and the other ultrasonic flowmeter 1 based on the propagation time is improved.

[0054] In the above embodiment, the presence or absence of a water leak is determined by acquiring the propagation time of ultrasonic waves between adjacent ultrasonic flow meters 1, but this is not limited to this. As a modified example, for example, a configuration may be adopted in which the ultrasonic flow meters 1 are divided into groups based on the area in which they are installed, and the presence or absence of a water leak is determined between a parent meter that transmits ultrasonic waves and a child meter that receives ultrasonic waves transmitted from the parent meter within that group.

[0055] Second Embodiment Next, a second embodiment will be described. Fig. 5 is a diagram showing the configuration of an ultrasonic flowmeter 70 according to the second embodiment. As shown in Fig. 5, the configuration of the ultrasonic flowmeter 70 according to the second embodiment differs from the configuration of the ultrasonic flowmeter 1 according to the first embodiment in that an ultrasonic signal processing unit 41 is provided instead of the meter-to-meter propagation time measuring unit 4. In the second embodiment, components that are the same as or correspond to those in the first embodiment are given the same reference numerals, and duplicated descriptions will be omitted unless otherwise noted.

[0056] The ultrasonic signal processing unit 41 in one of the adjacent ultrasonic flowmeters 1 in the water supply network 60 acquires the propagation waveform of the ultrasonic waves in the common piping 54 and the inlet pipe 55 between the one ultrasonic flowmeter 1 and the other ultrasonic flowmeter 1 based on the low-frequency ultrasonic waves emitted from the first ultrasonic transmitter / receiver 5 etc. in the other ultrasonic flowmeter 1 and received by the first ultrasonic transmitter / receiver 5 etc. in the one ultrasonic flowmeter 1.

[0057] 4 , the ultrasonic signal processing unit 41 of the ultrasonic flowmeter 1A acquires the propagation waveform of the ultrasonic wave in the common pipe 54 and the inlet pipe 55 between the ultrasonic flowmeter 1A and the ultrasonic flowmeter 1B. Also, the ultrasonic signal processing unit 41 of the ultrasonic flowmeter 1B acquires the propagation waveform of the ultrasonic wave in the common pipe 54 and the inlet pipe 55 between the ultrasonic flowmeter 1B and the ultrasonic flowmeter 1C. Also, the ultrasonic signal processing unit 41 of the ultrasonic flowmeter 1B acquires the propagation waveform of the ultrasonic wave in the common pipe 54 and the inlet pipe 55 between the ultrasonic flowmeter 1B and the ultrasonic flowmeter 1A. Also, the ultrasonic signal processing unit 41 of the ultrasonic flowmeter 1C acquires the propagation waveform of the ultrasonic wave in the common pipe 54 and the inlet pipe 55 between the ultrasonic flowmeter 1C and the ultrasonic flowmeter 1D. Also, the ultrasonic signal processing unit 41 of the ultrasonic flowmeter 1C acquires the propagation waveform of the ultrasonic wave in the common pipe 54 and the inlet pipe 55 between the ultrasonic flowmeter 1C and the ultrasonic flowmeter 1B. Furthermore, the ultrasonic signal processing unit 41 of the ultrasonic flowmeter 1D acquires the waveform of the ultrasonic waves propagating in the common pipe 54 and the lead-in pipe 55 between the ultrasonic flowmeter 1D and the ultrasonic flowmeter 1C.

[0058] The central device 20 is provided with a storage unit (not shown). The storage unit of the central device 20 stores thresholds to be compared with the flow rates measured by the ultrasonic flowmeters 1A to 1D, thresholds to be compared with the flow rate of water flowing through the common pipe 54, and the like. The storage unit of the central device 20 also stores propagation waveforms when there is no abnormality, which correspond to the propagation waveforms acquired by each ultrasonic signal processor 41. Specifically, the storage unit of the central device 20 stores, as propagation waveforms when there is no abnormality, the propagation waveform of ultrasonic waves between the ultrasonic flowmeter 1A and the ultrasonic flowmeter 1B, the propagation waveform of ultrasonic waves between the ultrasonic flowmeter 1B and the ultrasonic flowmeter 1C, and the propagation waveform of ultrasonic waves between the ultrasonic flowmeter 1C and the ultrasonic flowmeter 1D, and the like.

[0059] The integrated processing unit 58 acquires the above-mentioned propagation waveforms from the ultrasonic signal processors 41 of the ultrasonic flowmeters 1A to 1D via the integrated communication unit 59. The integrated processing unit 58 determines the presence or absence of an abnormality (such as the presence or absence of a water leak) based on a comparison between the acquired propagation waveform and a propagation waveform when no abnormality exists. In this case, the integrated processing unit 58 can determine that a water leak has occurred near the ultrasonic flowmeter 1 where the difference between the acquired propagation waveform and the propagation waveform when no abnormality exists is largest. For example, if the difference between the propagation waveform acquired by the ultrasonic signal processor 41 of the ultrasonic flowmeter 1A when ultrasonic waves are emitted from the ultrasonic flowmeter 1B is largest, it is estimated that there is a high possibility of a water leak in the piping path Lab. Alternatively, if the difference between the propagation waveform measured by the ultrasonic signal processor 41 of the ultrasonic flowmeter 1C when ultrasonic waves are emitted from the ultrasonic flowmeter 1B is largest, it is estimated that there is a high possibility of a water leak in the piping path Lbc. As a specific example of the determination method, the overall processing unit 58 compares the maximum amplitude (acquired maximum amplitude) in the propagation waveform (received waveform) shown in FIG. 6B with the maximum amplitude (reference maximum amplitude) in the propagation waveform (received waveform) when no abnormality is present, as shown in FIG. 6A, and determines that an abnormality has occurred if the acquired maximum amplitude is smaller than the reference maximum amplitude.

[0060] Alternatively, the following configuration may be adopted in this embodiment.

[0061] The low-frequency ultrasonic transmitter / receiver circuit 13 in one of the adjacent ultrasonic flowmeters 1 in the water supply network 60 causes the first ultrasonic transmitter / receiver 5 (or the second ultrasonic transmitter / receiver 6) in the adjacent ultrasonic flowmeter 1 to transmit low-frequency ultrasonic waves periodically and continuously for a predetermined period of time.

[0062] The ultrasonic signal processor 41 in the other ultrasonic flowmeter 1 of the first ultrasonic flowmeter 1 and the second ultrasonic flowmeter 1 receives the propagation waveform of the low-frequency ultrasonic waves transmitted from the first ultrasonic transmitter / receiver 5 (or the second ultrasonic transmitter / receiver 6) via the flow path of the water supply network 60. The ultrasonic signal processor 41 then compares the propagation waveform of the received low-frequency ultrasonic waves with a predetermined propagation waveform (a propagation waveform when no abnormality exists). If the propagation waveform of the low-frequency ultrasonic waves does not match the predetermined propagation waveform for a predetermined period of time, the ultrasonic signal processor 41 determines an abnormality. In this case, the ultrasonic signal processor 41 can use, for example, the magnitude relationship between the maximum amplitude of the predetermined propagation waveform and the maximum amplitude of the received propagation waveform as a method of determining the identity. The ultrasonic signal processor 41 determines a normal state if the maximum amplitude of the received propagation waveform is equal to or greater than the maximum amplitude of the predetermined propagation waveform, and determines an abnormality if the maximum amplitude of the received propagation waveform is smaller than the maximum amplitude of the predetermined propagation waveform. This configuration allows the presence or absence of an abnormality to be determined for each ultrasonic flowmeter.

[0063] As described above, according to the second embodiment, the flow rate measurement unit 3 measures the water flow rate in the measurement flow path 40 based on the high-frequency ultrasonic signal. Because high-frequency ultrasonic waves are used during flow rate measurement, the short wavelength of the ultrasonic waves narrows the beam angle, making it easier to capture the water flow using ultrasonic waves. As a result, the accuracy of the propagation time is improved, thereby improving the accuracy of the flow rate measurement. Meanwhile, the ultrasonic signal processing unit 41 acquires the propagation waveform of low-frequency ultrasonic waves in the flow path between adjacent ultrasonic flow meters 1 in the water supply network 60 based on the low-frequency ultrasonic signal. Thus, low-frequency ultrasonic waves are used during water leak detection. Low-frequency ultrasonic waves are less susceptible to attenuation than high-frequency ultrasonic waves and have a wider beam angle, so they easily propagate from one ultrasonic flow meter 1 to the other ultrasonic flow meter 1 through the flow path. Therefore, the propagation waveform of ultrasonic waves between one ultrasonic flow meter 1 and the other ultrasonic flow meter 1 can be acquired with high accuracy. Therefore, the accuracy of detecting an abnormality such as a water leak in the flow path between one ultrasonic flowmeter 1 and the other ultrasonic flowmeter 1 based on the propagation waveform is improved.

[0064] The present disclosure is not limited to the above-described embodiments, and various modifications are possible as described below without departing from the gist of the present disclosure.

[0065] In the above embodiment, the central device 20 is configured to have a central processing unit 58, but this is not limited to this, and the central processing unit 58 may also be provided in one of the multiple ultrasonic flow meters 1 installed in the target area 57.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] (Additional Notes) The following techniques are disclosed by the above description of the embodiments.

[0072] (Technology 1) An anomaly detection system comprising a plurality of flow meters provided in a water supply network and a central device that manages the plurality of flow meters, wherein the flow meters comprise a pair of ultrasonic transmitters and receivers provided in a measurement flow path, a high-frequency ultrasonic transmitter and receiver unit that causes one of the ultrasonic transmitters and receivers to transmit high-frequency ultrasonic waves and receives a high-frequency ultrasonic signal based on the high-frequency ultrasonic waves received by the other ultrasonic transmitter and receiver, a low-frequency ultrasonic transmitter and receiver unit that causes one of the ultrasonic transmitter and receivers to transmit low-frequency ultrasonic waves and receives a low-frequency ultrasonic signal based on the low-frequency ultrasonic waves received by the other ultrasonic transmitter and receiver, a flow rate measurement unit that measures the flow rate of water in the measurement flow path based on the high-frequency ultrasonic signal, and a low-frequency ultrasonic transmitter and receiver unit that measures the flow rate of water in the measurement flow path based on the low-frequency ultrasonic signal. An anomaly detection system comprising: an inter-meter propagation time measurement unit that measures the propagation time of the low-frequency ultrasonic wave in a flow path between one adjacent flow meter and the other adjacent flow meter in a water supply network; and a communication unit that communicates with the center device, wherein the center device comprises a central communication unit that communicates with the communication unit; and the central processing unit, wherein the central processing unit performs the following processes: acquiring the propagation time via the central communication unit; and, when the water flow rate from each of the plurality of flow meters in a target area for anomaly inspection is below a threshold and the flow rate flowing into the target area is below a threshold, determining whether or not an anomaly exists based on a comparison of the propagation time acquired via the central communication unit with the propagation time when no anomaly exists.

[0073] With this configuration, the flow rate measurement unit measures the water flow rate in the measurement flow path based on the high-frequency ultrasonic signal. Because high-frequency ultrasonic waves are used during flow rate measurement, the short wavelength of the ultrasonic waves narrows the beam angle (the angle at which the ultrasonic waves spread), making it easier to capture the water flow using ultrasonic waves. As a result, the accuracy of the propagation time is improved, thereby improving the accuracy of the flow rate measurement. Meanwhile, the inter-meter propagation time measurement unit measures the propagation time of ultrasonic waves in the flow path between adjacent flow meters in the water supply network based on the low-frequency ultrasonic signal. Thus, low-frequency ultrasonic waves are used during water leak detection. Because low-frequency ultrasonic waves are less susceptible to attenuation than high-frequency ultrasonic waves and have a wider beam angle, they easily propagate from one flow meter to the other through the flow path. Therefore, the propagation time of ultrasonic waves between one flow meter and the other flow meter can be obtained with high accuracy. This improves the accuracy of detecting abnormalities, such as water leaks, in the flow path between one flow meter and the other flow meter based on the propagation time.

[0074] (Technology 2) An anomaly detection system comprising a plurality of flow meters provided in a water supply network and a central device that manages the plurality of flow meters, wherein the flow meters comprise a pair of ultrasonic transmitters and receivers provided in a measurement flow path, a high-frequency ultrasonic transmitter and receiver unit that causes one of the ultrasonic transmitters and receivers to transmit high-frequency ultrasonic waves and receives a high-frequency ultrasonic signal based on the high-frequency ultrasonic waves received by the other ultrasonic transmitter and receiver, a low-frequency ultrasonic transmitter and receiver unit that causes one of the ultrasonic transmitter and receivers to transmit low-frequency ultrasonic waves and receives a low-frequency ultrasonic signal based on the low-frequency ultrasonic waves received by the other ultrasonic transmitter and receiver, a flow rate measuring unit that measures the flow rate of water in the measurement flow path based on the high-frequency ultrasonic signal, and a low-frequency ultrasonic transmitter and receiver unit that measures the flow rate of water in the measurement flow path based on the low-frequency ultrasonic signal. an ultrasonic signal processing unit that acquires the propagation waveform of the low-frequency ultrasonic wave in the flow path between one of the flow meters and the other of the adjacent flow meters in the water supply network, and a communication unit that communicates with the center device, wherein the center device comprises a central communication unit that communicates with the communication unit, and the central processing unit, wherein the central processing unit performs the following processes: acquiring the propagation waveform via the central communication unit; and, when the water flow rate from each of the plurality of flow meters in the area subject to abnormality inspection is below a threshold and the flow rate flowing into the target area is below a threshold, determining whether or not an abnormality exists based on a comparison of the propagation waveform acquired via the central communication unit with the propagation waveform when no abnormality exists.

[0075] With this configuration, the flow rate measurement unit measures the water flow rate in the measurement flow path based on the high-frequency ultrasonic signal. Because high-frequency ultrasonic waves are used during flow rate measurement, the short wavelength of the ultrasonic waves narrows the beam angle (the angle at which the ultrasonic waves spread), making it easier to capture the water flow using ultrasonic waves. As a result, the accuracy of the propagation time is improved, thereby improving the accuracy of the flow rate measurement. Meanwhile, the ultrasonic signal processing unit acquires the propagation waveform of low-frequency ultrasonic waves in the flow path between adjacent flow meters in the water supply network based on the low-frequency ultrasonic signal. Thus, low-frequency ultrasonic waves are used during water leak detection. Because low-frequency ultrasonic waves are less susceptible to attenuation than high-frequency ultrasonic waves and have a wider beam angle, they easily propagate from one flow meter to the other flow meter through the flow path. Therefore, the propagation waveform of ultrasonic waves between one flow meter and the other flow meter can be acquired with high accuracy. This improves the accuracy of detecting abnormalities, such as water leaks, in the flow path between one flow meter and the other flow meter based on the propagation waveform.

[0076] (Technology 3) An anomaly detection system described in Technology 1 or 2, wherein the flow path between the one flow meter and the other flow meter is formed by a circular pipe, and the wavelength of the low-frequency ultrasonic wave is longer than the diameter of the circular pipe.

[0077] This configuration allows low frequency ultrasonic waves to easily propagate through the flow path.

[0078] (Technology 4) An anomaly detection system described in any one of Technologies 1 to 3, wherein the pair of ultrasonic transmitters and receivers have a resonant frequency in a first frequency range including the frequency of the high-frequency ultrasonic waves or a second frequency range including the frequency of the low-frequency ultrasonic waves.

[0079] This configuration makes it possible to improve the transmission and reception sensitivity of the ultrasonic transmitter and receiver for both high-frequency and low-frequency ultrasonic waves. As a result, the use of high-frequency ultrasonic waves improves the accuracy of flow rate measurement, and the use of low-frequency ultrasonic waves improves the accuracy of water leak detection.

[0080] (Technology 5) An anomaly detection system described in any one of Technologies 2 to 4, wherein the low-frequency ultrasonic transmitter / receiver unit in one of the adjacent flow meters in the water supply network causes the one ultrasonic transmitter / receiver to transmit the low-frequency ultrasonic waves periodically and continuously for a predetermined period of time, and the ultrasonic signal processing unit in the other of the adjacent flow meters receives the propagation waveform of the low-frequency ultrasonic waves transmitted from the one ultrasonic transmitter / receiver in the one flow meter via the flow path of the water supply network, compares the propagation waveform of the received low-frequency ultrasonic waves with a predetermined propagation waveform, and determines that an anomaly has occurred if the propagation waveform of the low-frequency ultrasonic waves and the predetermined propagation waveform are not identical for a predetermined period of time.

[0081] With this configuration, the ultrasonic signal processing unit compares the propagation waveform of the low-frequency ultrasonic wave with a predetermined propagation waveform, and if the propagation waveform of the low-frequency ultrasonic wave does not match the predetermined propagation waveform for a predetermined period of time, it determines that an abnormality has occurred. This makes it possible to accurately determine the presence or absence of an abnormality such as a water leak on a flow meter-by-flow meter basis.

[0082] DESCRIPTION OF SYMBOLS 1, 1A, 1B, 1C, 1D, 70 Ultrasonic flowmeter 2 Control unit 3 Flowmeter side unit 4 Meter-to-meter propagation time measuring unit 5 First ultrasonic transmitter / receiver 6 Second ultrasonic transmitter / receiver 9 Communication unit 12 Memory unit 13 Low-frequency ultrasonic transmitter / receiver circuit 14 High-frequency ultrasonic transmitter / receiver circuit 20 Center device 40 Measurement flow path 41 Ultrasonic signal processing unit 54 Common piping 55 Intake pipe 56 Customer's home 57 Target area 58 Overall processing unit 59 Overall communication unit 60 Water supply network 100 Abnormality detection system

Claims

1. An anomaly detection system comprising a plurality of flow meters provided in a water supply network and a central device that manages the plurality of flow meters, wherein the flow meters comprise: a pair of ultrasonic transmitters and receivers provided in a measurement flow path; a high-frequency ultrasonic transmitter and receiver unit that causes one of the ultrasonic transmitters and receivers to transmit high-frequency ultrasonic waves and receives a high-frequency ultrasonic signal based on the high-frequency ultrasonic waves received by the other ultrasonic transmitter and receiver; a low-frequency ultrasonic transmitter and receiver unit that causes one of the ultrasonic transmitter and receivers to transmit low-frequency ultrasonic waves and receives a low-frequency ultrasonic signal based on the low-frequency ultrasonic waves received by the other ultrasonic transmitter and receiver; a flow rate measurement unit that measures the flow rate of water in the measurement flow path based on the high-frequency ultrasonic signal; an inter-meter propagation time measurement unit that measures the propagation time of the low-frequency ultrasonic waves in a flow path between one of the flow meters and the other of the flow meters adjacent to each other in the water supply network based on the low-frequency ultrasonic signal; 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 the central processing unit, wherein the central processing unit An anomaly detection system that performs the following processes: acquiring the propagation time via the central communication unit; and, when the water flow rate measured by each of the plurality of flow meters in an area subject to an abnormality inspection is below a threshold and the flow rate flowing into the area subject to an abnormality inspection is below a threshold, determining whether or not there is an abnormality based on a comparison of the propagation time acquired via the central communication unit with the propagation time when there is no abnormality.

2. An abnormality detection system comprising a plurality of flow meters provided in a water supply network and a central device that manages the plurality of flow meters, wherein the flow meters comprise: a pair of ultrasonic transmitters and receivers provided in a measurement flow path; a high-frequency ultrasonic transmitter and receiver unit that causes one of the ultrasonic transmitters and receivers to transmit high-frequency ultrasonic waves and receives a high-frequency ultrasonic signal based on the high-frequency ultrasonic waves received by the other ultrasonic transmitter and receiver; a low-frequency ultrasonic transmitter and receiver unit that causes one of the ultrasonic transmitter and receivers to transmit low-frequency ultrasonic waves and receives a low-frequency ultrasonic signal based on the low-frequency ultrasonic waves received by the other ultrasonic transmitter and receiver; a flow measurement unit that measures the flow rate of water in the measurement flow path based on the high-frequency ultrasonic signal; an ultrasonic signal processing unit that acquires the propagation waveform of the low-frequency ultrasonic waves in the flow path between one of the flow meters and the other of the flow meters adjacent to each other in the water supply network based on the low-frequency ultrasonic signal; 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 the central processing unit, wherein the central processing unit An anomaly detection system that performs the following processes: acquiring the propagation waveform via the central communication unit; and, when the water flow rate from each of the plurality of flow meters in the area being inspected for anomalies is below a threshold and the flow rate flowing into the area is below a threshold, determining whether or not an anomaly exists based on a comparison of the propagation waveform acquired via the central communication unit with the propagation waveform when no anomaly exists.

3. An anomaly detection system according to claim 1 or 2, wherein the flow path between the one flow meter and the other flow meter is formed by a circular pipe, and the wavelength of the low-frequency ultrasonic wave is longer than the diameter of the circular pipe.

4. An anomaly detection system as described in claim 1 or 2, wherein the pair of ultrasonic transmitters and receivers have a resonant frequency in a first frequency range including the frequency of the high-frequency ultrasonic waves or a second frequency range including the frequency of the low-frequency ultrasonic waves.

5. The anomaly detection system described in claim 2, wherein the low-frequency ultrasonic transmitter / receiver unit in one of the adjacent flow meters in the water supply network causes the one ultrasonic transmitter / receiver to transmit the low-frequency ultrasonic waves periodically and continuously for a predetermined period of time, and the ultrasonic signal processing unit in the other of the adjacent flow meters receives the propagation waveform of the low-frequency ultrasonic waves transmitted from the one ultrasonic transmitter / receiver in the one flow meter via the flow path of the water supply network, compares the propagation waveform of the received low-frequency ultrasonic waves with a predetermined propagation waveform, and determines that an anomaly has occurred if the propagation waveform of the low-frequency ultrasonic waves and the predetermined propagation waveform are not identical for a predetermined period of time.

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