Tap water meter

Abstract

This tap water meter comprises: a first ultrasonic transducer and a second ultrasonic transducer that are provided in a measurement flow path and transmit and receive ultrasonic signals; a flow rate measurement unit that measures the flow rate of a fluid in the measurement flow path on the basis of a reception signal from the first ultrasonic transducer or the second ultrasonic transducer; and a minute leak detection unit. When the flow rate measured by the flow rate measurement unit is equal to or less than a threshold value, the minute leak detection unit detects a minute leakage of the fluid in the measurement flow path on the basis of a flow rate obtained by continuously performing measurements a plurality of times, at a second interval shorter than a first interval, over the entire detection period.

Description

Water meter

[0001] The present disclosure relates to water meters.

[0002] Generally, homes are equipped with a water meter to measure the amount of water used. Water is taken in through an inlet pipe that branches off from the common water supply pipe, passes through the water meter, and then flows into the supply pipe that supplies water to toilets, washrooms, etc. Most water meters have a structure such as an impeller that measures the water flow rate and has the function of charging water fees. However, in recent years, the introduction of water meters that use electronic measurement systems has been progressing.

[0003] Japanese Patent Application Laid-Open No. 2003-139590

[0004] However, ultrasonic water meters have been increasingly adopted as water meters to detect minute leaks caused by aging water supply pipes or deteriorated joint packing. However, because the service pipes and service pipes at a customer's home are connected to the service pipes and service pipes of other customers' homes through common pipes, there has been a problem in that it is difficult to accurately detect minute water leaks due to acoustic noise generated when other customers are using the water.

[0005] Therefore, an object of the present disclosure is to provide a water meter that can detect minute water leaks with high accuracy.

[0006] The water meter of the present disclosure comprises a first ultrasonic transmitter / receiver and a second ultrasonic transmitter / receiver that are provided in a measurement flow path and transmit and receive ultrasonic signals, a flow rate measuring unit that measures the flow rate of fluid in the measurement flow path based on the signal received by the first ultrasonic transmitter / receiver or the second ultrasonic transmitter / receiver, and a micro-leak detection unit, and when the flow rate measured by the flow rate measuring unit is below a threshold value, the micro-leak detection unit detects micro-leakage of fluid in the measurement flow path based on the flow rate obtained by measuring at a second interval that is shorter than the first interval multiple times consecutively for a detection period.

[0007] According to the present disclosure, microleaks are detected based on the flow rate obtained by performing measurements at second intervals, which are shorter than the first intervals, multiple times during the detection period. For example, the amount of microleaks detected at each second interval during the detection period is averaged, and the presence or absence of a microleak can be determined based on this average amount. This reduces the influence of acoustic noise (e.g., acoustic noise caused by vibrations when water is used at other consumer homes) that may change periodically compared to when a microleak is detected at the first interval. Therefore, microleaks can be detected with high accuracy.

[0008] In the above disclosure, the water meter may include a noise detection unit that detects the output voltage of the first ultrasonic transmitter / receiver and the second ultrasonic transmitter / receiver and the period of the output voltage, and the micro leak detection unit may detect the micro leak by setting the detection period to be longer than the period.

[0009] According to the above configuration, the detection period is set to be equal to or longer than the cycle, so that the influence of acoustic noise can be further suppressed.

[0010] In the above disclosure, the noise detection unit may compare the output voltage with a predetermined value to determine whether or not acoustic noise is present when water is used at another consumer's home, and the micro-leak detection unit may detect the micro-leak when the noise detection unit determines that there is no acoustic noise.

[0011] According to the above configuration, a microleak is detected when no acoustic noise is detected, thereby improving the accuracy of detecting a microleak.

[0012] In the above disclosure, the water meter may be communicatively connected to a center device and may include a transmitter that issues an alarm to the center device and transmits information about the output voltage and the period if the acoustic noise continues for a predetermined period of time.

[0013] According to the above configuration, the transmitter sends the alarm to the central device and also transmits information on the output voltage and the period, allowing the central device to recognize that it is difficult to detect minute leaks in the water meter due to the influence of acoustic noise.

[0014] According to the present disclosure, it is possible to provide a water meter that is capable of detecting minute water leaks with high accuracy.

[0015] 1 is a diagram showing the configuration of a water leak detection system; 2 is a diagram showing the configuration of a water meter; 3 (a) is a diagram showing the measurement interval in normal flow rate measurement by the flow meter side section, and 4 (b) is a diagram showing the detection interval during the detection period by the micro leak detection section; 5 (a) is a diagram showing the change over time in the voltage between the terminals of the ultrasonic transmitter / receiver when there is no water usage at other customer homes, 6 (b) is a diagram showing the change over time in the voltage between the terminals of the ultrasonic transmitter / receiver when there is water usage at other customer homes, and 7 (c) is an explanatory diagram of the detection period.

[0016] A water meter according to an embodiment of the present disclosure will be described below with reference to the drawings. The water meter 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 can be made without departing from the spirit of the present disclosure.

[0017] As shown in FIG. 1, the water leakage detection system 100 of this embodiment includes one or more customer homes 56 and a center device 20 included in a target area 57 for water leakage inspection.

[0018] In the water leak detection system 100, one end of a main pipe (not shown) is connected to a water supply plant, and the other end is connected to a common pipe 54. The common pipe 54 extends toward a target area 57, and multiple inlet pipes 55 branch off from the common pipe 54 to correspond to multiple consumer homes 56. The downstream ends of the multiple inlet pipes 55 are each connected to a consumer home 56. In this configuration, water from the water supply plant is supplied to each consumer home 56 via the main pipe, the common pipe 54, and the inlet pipes 55. Each consumer home 56 is equipped with a water meter 1 consisting of an ultrasonic flowmeter. In FIG. 1, consumer homes 56A, 56B, 56C, and 56D are illustrated as four consumer homes 56, and the water meters 1 for consumer homes 56A, 56B, 56C, and 56D are identified and illustrated as water meters 1A, 1B, 1C, and 1D, respectively. The configuration of the water meter 1 will be described in detail later.

[0019] The center device 20 has the function of receiving meter reading data such as measured flow rate by communicating with each water meter 1 and issuing various instructions to each water meter 1. The method of communication between the center device 20 and each water meter 1 is not particularly limited, and may be, for example, cellular communication, specified low-power wireless communication, or network communication via a relay station. Such a center device 20 includes a central processing unit 58 and a central communication unit 59. The central communication unit 59 communicates with the communication unit 9 (described below) included in each water meter 1. The central processing unit 58 determines the presence or absence of 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 water meter 1 in the consumer's home 56 via the central communication unit 59.

[0020] Next, the water leakage determination by the water leakage detection system 100 in the area 57 subject to water leakage inspection will be described.

[0021] Water meter 1A is connected to common pipe 54 by inlet pipe 55A, and water meter 1B is connected to common pipe 54 by inlet pipe 55B. Water meter 1C is connected to common pipe 54 by inlet pipe 55C, and water meter 1D is connected to common pipe 54 by inlet pipe 55D. Branch points of inlet pipes 55A to 55C with respect to common pipe 54 are designated P1 to P3. Inlet pipe 55D is connected to downstream end P4 of common pipe 54.

[0022] The piping path from water meter 1A to water meter 1B is designated as Lab, the piping path from water meter 1B to water meter 1C is designated as Lbc, and the piping path from water meter 1C to water meter 1D is designated as Lcd. Furthermore, the flow rates through lead-in pipes 55A to 55D measured by flow rate measuring units 3 (described later) of water meters 1A to 1D are designated as q1 to q4, respectively. Furthermore, the flow rate at branch point P1 of common pipe 54 is designated as Q1. Note that flow rate Q1 is the sum of flow rates q1 to q4.

[0023] The central processing unit 58 of the center device 20 receives the flow rates q1 to q4 from the water meters 1A to 1D via the central communication unit 59. The central processing unit 58 then determines whether the flow rates q1 to q4 from the water 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.

[0024] The overall processing unit 58 receives the water flow rates detected by the water meters 1A-1D via the overall communication unit 59. The overall processing unit 58 then determines whether or not a water leak is occurring by comparing the flow rates measured by the water meters 1A-1D with a threshold value. In this case, the overall processing unit 58 determines, for example, that a water leak is occurring near the water meter 1 where the difference between the flow rate and the threshold value is the largest. For example, if the difference related to water meter 1A is the largest, it is estimated that there is a high possibility that a water leak is occurring in piping path Lab. If the difference related to water meter 1B or the difference related to water meter 1C is the largest, it is estimated that there is a high possibility that a water leak is occurring in piping path Lbc. Furthermore, if the difference related to water meter 1D is the largest, it is estimated that there is a high possibility that a water leak is occurring in piping path Lcd.

[0025] Next, a detailed description will be given of the configuration of the water meter 1. FIG.

[0026] 2 , the water meter 1 includes a control unit 2, 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 noise detection circuit 10, a transmitting unit 11, a display unit 12, and a measurement flow path 40. Although not shown, the water meter 1 may further include a memory unit. Furthermore, the control unit 2 includes, as functional components, a flow meter unit 3, a microleak detection unit 4, and a transmitting unit 11. In this embodiment, the noise detection circuit 10 corresponds to the noise detection unit.

[0027] 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, a noise detection circuit 10, and a display unit 12. The flowmeter side unit 3, the microleak detection unit 4, and the transmission unit 11 are functionally realized by the control unit 2 executing a predetermined program.

[0028] The flow meter side section 3 measures the water flow rate based on the propagation time measured 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.

[0029] The flowmeter unit 3 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 flowmeter unit 3 identifies the zero-crossing point at which the voltage of the amplified 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. The 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 flowmeter unit 3 then measures the elapsed time from the application of pulse waves to the transmitting ultrasonic transmitter / receiver to the zero-crossing point (i.e., the propagation time of the ultrasonic waves).

[0030] Measurement flow path 40 is a water flow path that extends in one direction and is provided inside water meter 1. First ultrasonic transmitter / receiver 5 is disposed on the upstream side of the outer surface of measurement flow path 40, and transmits ultrasonic waves in the radial direction of measurement flow path 40 while receiving ultrasonic waves transmitted by second ultrasonic transmitter / receiver 6. Second ultrasonic transmitter / receiver 6 is disposed on the downstream side of the outer surface of measurement flow path 40, and transmits ultrasonic waves in the radial direction of measurement flow path 40 while receiving ultrasonic waves transmitted by first ultrasonic transmitter / receiver 5.

[0031] 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.

[0032] The communication unit 9 communicates with external devices, including the general communication unit 59, and transmits and receives various data. The display unit 12 displays various information, including meter readings. In Fig. 2, the symbol FD indicates the direction of water flow, and the symbol PP indicates the propagation path of ultrasonic waves.

[0033] 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.

[0034] The flowmeter unit 3 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 flowmeter unit 3 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.

[0035] Here, the flow velocity of the fluid (water) flowing in the measurement flow path 40 along the direction FD 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 during the propagation time until they reach the second ultrasonic transmitter / receiver 6 is expressed by the following mathematical formula 1.

[0036] (Math. 1) t1=L / (C+V)

[0037] Next, the propagation time t2 for the ultrasonic waves 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.

[0038] (Math. 2) t2=L / (CV)

[0039] 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.

[0040] (Math. 3) V=L / 2((1 / t1)-(1 / t2))

[0041] 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 the coefficient k in the following formula 4 is a correction coefficient for correcting various errors that occur in the measurement.

[0042] (Equation 4) Q = k × (V × S)

[0043] 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 section 7, and the propagation time between the second ultrasonic transmitter / receiver 6 and the second reflecting section 8. However, since these propagation times can basically be calculated independently of the flow velocity, only the propagation time of the portion of the propagation path PP with length L can be determined.

[0044] The microleak detection unit 4 periodically (for example, but not limited to, every hour or every three hours) detects microleakage of water in the measurement flow path 40 when the flow rate measured by the flow rate measurement unit 3 is equal to or lower than a threshold value. As will be described later, the microleak detection unit 4 detects microleakage of fluid in the measurement flow path 40 based on the flow rate obtained by performing measurements at second intervals K2, which are shorter than the first intervals K1, multiple times consecutively for a detection period DP. In this case, the microleak detection unit 4 measures the flow rate using a method similar to the above-mentioned flow rate measurement method used by the flowmeter unit 3.

[0045] 3(a) is a diagram showing the measurement intervals in normal flow rate measurement by the flowmeter section 3, and FIG. 3(b) is a diagram showing the detection intervals during the detection period DP by the microleak detection section 4. As shown in FIG. 3(a), normal flow rate measurement by the flowmeter section 3 is performed, for example, at first intervals K1. In this case, the control section 2 applies pulse waves to the first ultrasonic transmitter / receiver 5 or the second ultrasonic transmitter / receiver 6 at first intervals K1. The first intervals K1 are, for example, 1 to 2 seconds. Note that one first interval K1 of the multiple first intervals K1 may be different from the other first intervals K1.

[0046] In contrast, as shown in FIG. 3B, the microleak detection unit 4 detects the microleak during a detection period DP, which is a period during which the second intervals K2 are consecutive, and which is shorter than the first interval K1, which is the measurement interval of the flow rate by the flow rate measurement unit 3. That is, the microleak detection unit 4 performs the detection using the period during which the second intervals K2 are consecutive as the detection period DP. The second interval K2 is, for example, 0.5 seconds. Note that, among the multiple second intervals K2, one second interval K2 may be different from the other second intervals K2 as long as it is shorter than the first interval K1. That is, the maximum value of the second interval K2 is smaller than the minimum value of the first interval K1.

[0047] Fig. 4(a) is a diagram showing the change over time in the voltage (output voltage) between the terminals of the first ultrasonic transmitter / receiver 5 or the second ultrasonic transmitter / receiver 6 when there is no water usage at another customer's home 56. Fig. 4(b) is a diagram showing the change over time in the voltage between the terminals of the first ultrasonic transmitter / receiver 5 or the second ultrasonic transmitter / receiver 6 when there is water usage at another customer's home 56. Fig. 4(c) is an explanatory diagram of the detection period DP.

[0048] As shown in Figure 4 (a), when no water is being used at other customer homes 56, the voltage between the terminals of the first ultrasonic transmitter / receiver 5 or the second ultrasonic transmitter / receiver 6 at a certain customer home 56 does not change over time and is almost constant.

[0049] On the other hand, as shown in Figure 4 (b), when water is being used at another customer's home 56, the voltage between the terminals of the first ultrasonic transmitter / receiver 5 or the second ultrasonic transmitter / receiver 6 at a certain customer's home 56 changes over time and is not constant due to acoustic noise caused by the vibrations of the water usage.

[0050] The noise detection circuit 10 detects the output voltage of the first ultrasonic transmitter / receiver 5 or the second ultrasonic transmitter / receiver 6, and also detects the period T of the output voltage as shown in Fig. 4(c). The microleak detection unit 4 detects a microleak by determining that the detection period DP is equal to or longer than the period T detected by the noise detection circuit 10. In Fig. 4(c), the period T is the elapsed time from the peak of one adjacent mountain to the peak of the other mountain in the signal waveform.

[0051] The noise detection circuit 10 compares the output voltage of the first ultrasonic transmitter / receiver 5 or the second ultrasonic transmitter / receiver 6 with a predetermined value to determine whether or not acoustic noise is present when water is used at another consumer's home 56. In this case, the noise detection circuit 10 may determine that acoustic noise is present when multiple peaks in the signal waveform of Figure 4(b) are equal to or greater than a predetermined value. The microleak detection unit 4 may then detect a microleak when the noise detection circuit 10 determines that there is no acoustic noise.

[0052] If the acoustic noise continues for a predetermined period of time, the transmitter 11 issues an alarm to the integrated processor 58 via the communication unit 9 and transmits information on the output voltage and the period T. The predetermined period of time is, for example, a period of several hours to several days.

[0053] As described above, according to the water meter 1 of this embodiment, a microleak is detected at the second interval K2, which is shorter than the first interval K1, during the detection period DP, during which the second intervals K2 are consecutive. For example, the amount of microleak detected at each second interval K2 during the detection period DP is averaged, and the presence or absence of a microleak can be determined based on this average amount. This reduces the influence of acoustic noise (e.g., acoustic noise caused by vibrations when water is used at other consumer homes 56) that may change periodically, compared to when a microleak is detected at the first interval K1. Therefore, microleak detection can be performed with high accuracy.

[0054] Furthermore, in this embodiment, the microleak detector 4 may detect microleakage by setting the detection period DP to a length equal to or greater than the above-mentioned cycle T. By setting the detection period DP to a length equal to or greater than the above-mentioned cycle T, the influence of acoustic noise can be further suppressed.

[0055] In this embodiment, the noise detection circuit 10 may compare the output voltage with a predetermined value to determine whether or not acoustic noise is present when water is used at another consumer's home 56, and the micro leak detection unit 4 may detect a micro leak if it is determined that no acoustic noise is present. This improves the accuracy of micro leak detection by detecting a micro leak when no acoustic noise is detected.

[0056] Furthermore, in this embodiment, if the acoustic noise continues for a predetermined period of time, the transmitter 11 issues an alarm to the center device 20 and transmits information on the output voltage and the period T. This enables the center device 20 to recognize that it is difficult to detect a minute leak in the water meter 1 due to the influence of the acoustic noise.

[0057] The present disclosure is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present disclosure. For example, the following modifications are possible.

[0058] In the above embodiment, the central device 20 is configured to have a comprehensive processing unit 58, but this is not limited to this, and the comprehensive processing unit 58 may also be provided in one of the multiple water meters 1 installed in the target area 57.

[0059] The installation location of the center device 20 is not particularly limited, and it may be installed next to a water supply station, for example.

[0060] 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.

[0061] In addition, in the above embodiment, four water meters 1 are connected to the common pipe 54, but this is not limited to this, and the number of water meters 1 connected to the common pipe 54 may be, for example, three or less, or five or more.

[0062] In addition, in the above embodiment, the water meter 1 is provided with two reflective sections, the first reflective section 7 and the second reflective section 8, but this is not limited to this, and the number of reflective sections may be, for example, one or three or more.

[0063] 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.

[0064] DESCRIPTION OF SYMBOLS 1, 1A, 1B, 1C, 1D Water meter 2 Control unit 3 Flow meter side unit 5 First ultrasonic transmitter / receiver 6 Second ultrasonic transmitter / receiver 7 First reflecting unit 8 Second reflecting unit 9 Communication unit 10 Noise detection circuit 11 Transmitting unit 12 Display unit 20 Central device 40 Measurement flow path 54 Common piping 55 Lead-in pipe 56 Customer's house 57 Target area 58 General processing unit 59 General communication unit 100 Water leak detection system

Claims

1. A water meter comprising a first ultrasonic transceiver and a second ultrasonic transceiver provided in a measurement flow path for transmitting and receiving ultrasonic signals, a flow rate measurement unit for measuring the flow rate of fluid in the measurement flow path at a first interval based on a reception signal from the first ultrasonic transceiver or the second ultrasonic transceiver, and a minute leak detection unit, wherein the minute leak detection unit detects minute leakage of fluid in the measurement flow path based on the flow rate obtained by continuously performing measurement at a second interval shorter than the first interval a plurality of times for a detection period when the flow rate measured by the flow rate measurement unit is equal to or less than a threshold value.

2. The water meter according to claim 1, further comprising a noise detection unit for detecting the output voltage and the period of the output voltage of the first ultrasonic transceiver and the second ultrasonic transceiver, wherein the minute leak detection unit detects the minute leak with the detection period being longer than or equal to the period.

3. The noise detection unit compares the output voltage with a predetermined value to determine the presence or absence of acoustic noise when water is used in other consumer houses, and the minute leak detection unit detects the minute leak when the noise detection unit determines that there is no acoustic noise. The water meter according to claim 2.

4. The water meter according to claim 3, further comprising a transmission unit communicably connected to a center device, for transmitting an alarm to the center device and transmitting information on the output voltage and the period when the acoustic noise continues for a predetermined period.

Images