WO2021217209A1

WO2021217209A1 - Digital water meter

Info

Publication number: WO2021217209A1
Application number: PCT/AU2021/050389
Authority: WO
Inventors: Virginia Collins Anderson; Ian Ridley; Tim Roney; Raghu Bharadwaj; Glen Wilson; Eng Yeap; Alan Jones; Kenneth Ng; Arjun Caprihan
Original assignee: Yarra Valley Water Corporation
Priority date: 2020-04-30
Filing date: 2021-04-29
Publication date: 2021-11-04

Abstract

The present invention relates to a digital water meter comprising: a processor, a power source in electronic communication with the processor, wireless communication means in electronic communication with the processor and the power source for wirelessly communicating with a network; and a housing within which the processor, power source and wireless communication means are housed. The processor operates the digital water meter in a lower power mode in which the power output of the power source is conserved and the digital water meter is awaken only for certain triggering events during which, the processor controls the wireless communication means to wirelessly communicate with the network.

Description

DIGITAL WATER METER

TECHNICAL FIELD

[01] The present invention relates generally to the field of digital water meters. In particular, the invention relates to a digital water meter having improved battery lifecycle management.

[02] This improved battery lifecycle management has been achieved through improved thermal management within the device, which regulates the temperature of the internal battery and serves to extend the longevity of the power source, as well as improved weatherproof performance minimising water ingress into the housing, and allowing for battery replacement if necessary.

BACKGROUND

[03] Digital water meters are well known in the art and are generally designed having electronics built into the unit (i.e. within a housing) and incorporate a display screen (often an LCD screen) as its display unit, and are often connected to the Internet or other network infrastructure to allow for remote measurement of water use. Because digital water meters can collect and relay information quickly, they have the potential to provide daily information about water use, enabling customers to be more aware of how much water is being used and importantly, digital water meters can provide early warnings of possible water leaks, so that action can be taken quickly if needed to save water.

[04] Obviously, in order for digital water meters to be effective, they need to be operational and connected to the network to share relevant information back to the central control centre over the network. This means it is important that the digital water meter has a long life power source (battery power), which requires minimal maintenance by the water utility company, and the digital water meter unit must also be tamper resistant to minimise potential damage when installed onsite. Further, the digital water meter unit must be suitably weatherproof such that it can withstand typical environmental conditions when installed onsite, most typically at residential and commercial properties. [05] From the perspective of the utility company, low maintenance costs and minimal servicing requirements are important aspects of a digital smart meter. Ideally, a ‘set and forget’ type of product is ideal, where the device requires very minimal maintenance and repair. Accordingly, it is important that the digital water meter incorporates features that reduce the need for regular ongoing maintenance and repair, and minimise the likelihood of permanent damage, theft or otherwise disablement of the device following installation at a residential or commercial property.

[06] One aspect of the digital meter being a ‘set and forget’ type of product, is that the digital water meter has a substantial battery life, which will reduce the need for replacing the battery following installation of the device at an onsite location. The battery is typically integrally formed within the water meter unit and the battery is installed at the time of manufacture. As such, it is important that the battery has a very long inherent service life (at least 15 years), and low power consumption. To achieve this, the digital water meter is typically placed in a low power mode following the manufacturing process, whereby in this low power mode (off state or idle state), the meter will only be ‘awoken’ for certain triggering events.

[07] One such prior art approach to providing a low power consumption digital water meter is disclosed in United States patent application no. US 2014/361908, which discloses a multifunction electronic device generally involving a processor, a power source in electronic communication with the processor, and wireless communicator, the wireless communicator in electronic communication with the processor and the power source. The processor controls the wireless communicator in a manner that minimizes power consumption by the multifunction electronic device, whereby the power source is conserved. The multifunction electronic device serves at least one function, such as a register device or a remote device. The multifunction electronic device wirelessly communicates with a remote server, such as a cloud based server, and performs metering measurements by way of a magnetic field sensor for enhancing accuracy of such measurements.

[08] Further aspects of the digital meter being a ‘set and forget’ type of product are that the digital water meter minimises the likelihood of permanent damage, theft or otherwise disablement of the device following installation at an onsite location. Accordingly, the digital water meter includes anti-theft or tamper resistant features, which minimise the likelihood of the meter being stolen or damaged to the point of requiring repair by the utility company technicians. [09] One such prior art approach to providing a water meter with a tamper proof lock or mechanism to reduce the possibility of the device or tampering with the device is disclosed in Chinese patent publication no. CN 103323069, which discloses a screwing nut sleeve for a water meter connector. Two semicircle sleeves which can be folded are hinged to each other; a fastening edge is formed on the side of each of the two sleeves; the inner ring sleeve of a screwing nut can be arranged in connection with each other on the two sleeves, and can serve as the corresponding ring of a lead sealing sleeve. The screwing nut sleeve can connect each of two ends of a water meter with a water pipe, the lead seal can prevent private dismounting, so that the phenomenon of stealing water through privately dismounting the water meter is effectively prevented; the screwing nut sleeve is simple, and can be used together with a water meter when a water supply company mounts the water meter.

[10] The other important aspect of a digital water meter is that the device housing effectively prevent water ingress into the housing, which is particularly important given that the meters are designed to be installed (most often outside) onsite at a residential or commercial premise, and then effectively left to the elements for up to 20+ years. Given the electronic components housed within a digital water meter, it is particularly important that the housing be weatherproof/waterproof.

[11] One prior art approach to provide a digital water meter with a weatherproof seal is disclosed in Chinese patent publication no. CN 202008380, which discloses a remote- transmission water meter which comprises a base meter component, wherein the base meter component comprises a meter case, a movement and a valve body. The movement and the valve body are fixedly arranged on the meter case. A case component with an inner cavity is also arranged on the base meter component, the case component comprises a bottom case and an upper cover that are fixedly connected with each other; an actuator component is fixedly arranged in the inner cavity and positioned above the valve body. A through hole is formed on the bottom case, the valve body penetrates the through hole. A first elastic sealing element is sleeved on the outer side of the valve body and arranged between the bottom case and the base meter component; and a second elastic sealing element is arranged between the bottom case and the upper cover. The remote- transmission water meter has good water-proof and moisture-proof effects (up to IP68 classification); and the product is stable in long-time use, simple in assembly, high in assembly efficiency, convenient in disassembly and convenient in after-sales maintenance.

[12] Whilst there have been efforts made in the prior art to provide suitable digital water meters, there is nevertheless a need to provide a digital water meter, that overcomes, or at least ameliorates, the deficiencies in the prior art, or provides an alternative approach thereto.

DISCLOSURE OF THE INVENTION

[13] In a first aspect, the present invention relates to a digital water meter comprising: a processor, a power source in electronic communication with the processor, wireless communication means in electronic communication with the processor and the power source for wirelessly communicating with a network; and a housing within which the processor, power source and wireless communication means are housed; whereby the processor operates the digital water meter in a lower power mode in which the power output of the power source is conserved and the digital water meter is awaken only for certain triggering events during which, the processor controls the wireless communication means to wirelessly communicate with the network.

[14] Preferably, the power source is a battery and the thermal design of the housing provides thermal stability by passive thermal management of the internal temperature within the housing, thereby improving battery performance and battery lifespan.

[15] Preferably, the housing includes an inlet on one side thereof into which cool air is drawn from the environment external to the housing, and a warm air exhaust on the opposite side of the housing out of which the heated air from within the housing escapes to the environment outside of the housing, such that the inlet and exhaust provide an airflow path through the housing that provides the passive thermal management.

[16] Preferably, the power source consists of a battery having primary cells and secondary cells.

[17] More preferably, the primary cells are non-rechargeable cells and the secondary cells are rechargeable cells.

[18] Preferably, the outer surface of the housing further includes one or more solar panels, and the secondary cells are recharged by the solar panels. [19] Preferably, the secondary cells act as a capacitor for large current drain events such as loT communications sent by the wireless communication means over the network, in order to smooth out the peak power drain from the primary cells.

[20] Preferably, the water volume and flow rate are determined with an ultrasonic measurement device.

[21] Preferably, the ultrasonic measurement device further includes an ultrasonic flow converter that controls ultrasonic pulses transmitted and received between two ultrasonic transducers.

[22] Preferably, the digital water meter of the present invention further includes a flow tube through which water flows in order to be measured by the ultrasonic measurement device, wherein the flow tube has three distinct zones where transition between two adjacent zones is bell shaped to minimize disturbances resulting from abrupt changes in flow area.

[23] Preferably, the digital water meter of the present invention further includes physical tamper detection means that prevent the water meter from being disconnected from a water pipe infrastructure following installation thereon.

[24] Preferably, the physical detection means includes the following: a locking collar surrounding an attachment nut used to install the water meter to a water pipe; plastic tamper evident plugs that secure the housing together; and tamper detection sensors including IR sensors and accelerometers that have a low power consumption.

[25] Preferably, the wireless communication means transmits information via network to a remote database, such information including a daily status report of a number of pre determined parameters.

[26] Preferably, the housing further includes a radial seal which provides an IP68 rating such that electronic components that are housed within the housing will not be affected by water ingress.

[27] Preferably, the radial seal ring is positioned within the housing such that the seal can be opened to replace the power source in order to extend the device life of the water meter, but at other times, the radial seal ring provides the IP68 rating to the housing. [28] Preferably, the housing further incorporates a hydrophobic vent located in a base portion of the housing, which equalises pressure between the internal pressure within the housing and the external air pressure outside of the housing, which results in minimising condensation forming within the housing during temperature cycling therein.

DESCRIPTION OF FIGURES

[29] Embodiments of the present invention will now be described in relation to figures, wherein:

FIGURE 1A shows the housing of a preferred embodiment of a digital water meter in accordance with an embodiment of the present invention;

FIGURE 1 B depicts the internal structure of a preferred embodiment of a digital water meter in accordance with the present invention;

FIGURE 2 depicts a cross-sectional view of one preferred embodiment of the water flow measuring component of the digital water meter shown in FIGURES 1 A and 1 B;

FIGURE 3 depicts a cross-sectional view of one aspect of the preferred embodiment of the water flow measuring component shown in FIGURE 2;

FIGURE 4 depicts a first aspect of one preferred embodiment of the tamper proof housing of the digital water meter shown in FIGURE 1 A;

FIGURE 5 depicts a second aspect of one preferred embodiment of the tamper proof housing of the digital water meter shown in FIGURE 1 A;

FIGURE 6 shows one preferred embodiment of the weatherproof seal of the digital water meter shown in FIGURE 1 A;

FIGURE 7 depicts a cross-sectional view of the digital water meter shown in FIGURE 1 A showing the airflow path there through for passive thermal management;

FIGURE 8 shows a schematic view of the system architecture of the digital water meter of the present invention; FIGURE 9 shows a schematic view of another aspect of the system architecture shown in FIGURE 5; and

FIGURE 10 shows a schematic view of the power consumption of the digital water meter of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[30] The present invention relates to a digital water meter (1 ).

[31] As is best shown in Figure 1A, the digital water meter (1) consists of a housing (2) having a water flow inlet (3) at one end, and a water flow outlet (4) at the opposite end. A number of electronic components and a power source (5) are housed within the housing (2), including a wireless communication means (6), which includes both a remote data interface

(7) for communication over a network (22) (such as the Internet), and a local data interface

(8) for communication with a handheld smart device via near field communication. The digital water meter (1) further includes a water flow measuring device (9).

[32] The size of the housing (2) has been optimised to take into account the length of the flow tube (10) (which is where the water flow is measured), in order to minimise sensor noise, which is influenced by separation distance of transducer mirrors (amongst other things) and to fit an efficient loT antenna for the B28 band (quarter wavelength size constraint) with omnidirectional coverage. Further, the enclosure design of the housing (2) facilitates convection airflow around the digital water meter, with a row of vents (11) at the top of the enclosure for heated air to escape. This is discussed in more detail below.

[33] As will be discussed further in more detail below, the digital water meter (1) itself produces an insignificant amount of heat due to the low power consumption design, and the air flow path that is designed within the housing (2). Further, this thermal design allows for heat removal to minimise the effects of solar radiation, and overall increases the efficiency and longevity of the battery lifespan.

[34] As best shown in Figures 1 B and 2, in a preferred embodiment, the digital water meter (1) uses ultrasonic measurement technology to determine water volume and flow rate. Specifically, the digital water meter utilizes an ultrasonic flow converter (13) that controls ultrasonic pulses transmitted and received between two ultrasonic transducers (14). Utilising known ultrasonic measurement technology in order to determine the water volume passing through the meter (1), and to measure the flow rate without requiring any moving parts, fits with the objective of the invention to provide a digital water meter (1) having improved battery lifecycle management.

[35] The water volume is subsequently calculated using the ultrasonic flow rate measurement integrated over time. Water volume is the legally accepted metric for billing of customer water consumption. The digital water meter (1) stores the total water volume calculated over time in an Accumulation Register, which represents the total water flow through the meter. The value of the Accumulation Register is output to the indicating device when activated by a user, for a visual display of water consumption. This may be by way of the value being displayed on an electronic digital display (23) incorporated into the housing (2), or it may be by way of the value being sent to separate hand held measuring device (such as a smart phone, PDA, tablet or laptop) via the wireless communication means (6).

[36] In the preferred embodiment of the invention, the ultrasonic flow measurement function is performed by an application specific chip (15) (manufactured and sold by AMS AG as the TDC-GP-30), in conjunction with two ultrasonic transducers. The GP-30 chip (15) controls the ultrasonic pulses transmitted and received between the two transducers (14), and performs the necessary sampling and processing of this data in order to determine the absolute Time of Flight (TOF) of the signal, and the differential TOF (dTOF). Since the speed of sound in water is a function of water temperature, the sum of upstream and downstream TOFs (SumToF) is used to calculate water temperature, and the processed dTOF is used to calculate water velocity and direction.

[37] The viscosity of water changes significantly over water temperature, and the water flow behaviour varies significantly with temperature. Essentially, the flow velocity profile across the cross-section of the metering tube is a function of both the flow rate and the fluid temperature. Therefore, conversion of measured dToF to a volumetric water flow rate must be processed using a complex, non-linear calibration factor for the assessed water temperature.

[38] The GP-30 chip (15) is configured to take ultrasonic ToF measurements up to 8 times / second. The actual sample rate is reduced to 2 samples / second under conditions of zero flow. Each pulse train comprises up to 25 ultrasonic pulses. The conversion of the dToF data to flow rate and subsequent accumulated volume is performed at a maximum of 1 Hz. [39] When water is detected to be flowing, the GP-30 chip (15) is interrogated every 5 seconds by the microcontroller to retrieve the current instantaneous flow rate measurement and accumulation register value. This interrogation rate is a trade-off of the following performance parameters:

• Detecting the maximum flow rate across the last reporting period;

• Outputting the current flow rate to the display (if activated); and

• Conserving battery power.

• Minimising loss of accumulation data if the GP-30 is reset during operation.

[40] The GP-30 chip (15) interrogation rate is increased when the digital water meter (1) electronic digital display (23) is active, to allow the microcontroller to update display data at a rate sufficient for human viewing and recognition of digits changing.

[41] The microcontroller stores the maximum instantaneous flow rate measured over the 24 hour reporting cycle, as this is part of the daily status. This flow rate value is stored in litres/second, with a resolution of 0.01 litres / sec.

[42] As best shown in Figure 3, the flow tube (10) has three distinct zones where transition between two adjacent zones is bell shaped to minimize disturbances due to abrupt changes in flow area. The inlet zone (16) (Zone 1) is sized to meet specific interface parameters and allows for the digital water meter to be connected to existing water infrastructure. This is the same for the outlet zone (18) (Zone 3). In the measurement zone (17) (Zone 2), the diameter of the tube decreases to maximise the flow velocity, which assists in measuring the water flow rate with the preferred embodiment of the ultrasonic transducers (14).

[43] The primary power source (5) of the digital water meter (1) is a non-replaceable battery (19), which must power the meter for the 15 year service life under bounded operating conditions. Every active component of the meter design is considerate of power consumption, and meter operation will be optimised to minimise power consumption.

[44] The battery (19) is integrated in the digital water meter and is installed at the time of manufacturing. The digital water meter (1) is placed in a lower power mode in order to achieve long service life of the battery (19). In a lower power mode, the digital water meter (1) is awaken only for certain triggering events.

[45] The battery (19) of the digital water meter (1) consists of primary cells (20) (i.e. non- rechargeable cells) and secondary cells (21) (i.e. rechargeable cells). The secondary cells (21) are recharged by the solar panels. The secondary cells (21) (i.e. rechargeable cells) act as a capacitor for large current drain events such as loT communications, in order to smooth out the peak power drain from the primary cells (20).

[46] The loT communications is a critical user of power in the digital water meter (1), especially when transmitting over the wireless communication means (6). loT communications is designed to minimise the time on air (time being required to stay on air based on mobile network protocols), and to minimise the time transmitting. Therefore, the message protocol is designed to limit the amount of data being sent to only that necessary for evaluation. To assist with determining the amount of power consumed during communications, the meter logs the communication activity time during any loT platform transactions.

[47] There is a period at the end of this transmission where the network (22) keeps the communications channel open for a set time before releasing the connection. A significant power saving for loT communications can be achieved when the network provider and modem vendor enable the Release Assistance Indicator (RAI) feature. This feature will enable the digital water meter (1) to control its release from the network connection, when no further loT platform communications are expected. This is anticipated to provide a significant power saving from the unnecessary network hold-up time that is currently incurred.

[48] The digital water meter (1) has been configured to have three main ‘modes’, which is a design primarily adopted in order to conserve power and increase the battery longevity and lifespan management.

• IDLE Mode - This mode maintains Real Time Clock (RTC) time, and operates the microcontroller in a power conservation mode that maintains volatile memory, while powering down all clock circuits apart from the RTC crystal. This microcontroller mode used is referred to as STOP mode.

TRANSMIT Mode (loT Transmitting) - This mode has the microcontroller fully powered up, along with the modem and other microcontroller peripherals. This is the highest power functional mode, and so design has aimed to minimise time communicating over the loT interface. The selection of LWM2M helps to minimise network overhead when communicating, and the RAI feature will further reduce the communications time window when incorporated.

• FUNCTIONAL Mode (Ultrasonic Measurement) -This mode performs the primary function of the digital water meter which is to measure water flow and subsequently determine flow volume. The selected measurement device (GP-30) has an inherently low power design. The device automatically adjusts the flow sampling rate to further optimise power usage, with zero flow having a low sampling rate, and high flow having a proportionately higher sampling rate. The Microcontroller is only powered up when required to regularly read parameters from the GP-30, so is only powered for a fraction of the time the GP-30 is taking measurements.

[49] Further, the digital water meter (1) includes an electronic digital display (23), which will include relevant information relating to measurements taken by the device, and other data relating to the meter (1). The display (23) is normally OFF (not persistent) in order to conserve power. Therefore, it requires a method to activate ON for reading. A user input device is provided for this purpose. The display (23) activates when a user touches the sensor - i.e. places their finger (or similar object) within 5 cm of the IR sensor being used as the input device, and then removes their finger from the sensor. For power conservation, the display (23) preferably remains ON for only a short period of time (preferably 30 seconds), by default, after being triggered.

[50] A false activation of the input device sensor is possible across a number of operational scenarios, considering environmental factors such as leaves, dirt, and bird droppings. Any continual activation of the input device (defined to be greater than 30 seconds) will initially activate the display. The display will stay ON for 30 seconds and then turn OFF, and will not re-activate until a new “touch” is detected. This scenario also includes a user keeping their finger on the sensor for this false activation period.

[51] The thermal design of the digital water meter (1) provides thermal stability/passive thermal management of the battery(19) and housing (2) that provides improved battery performance and lifespan.

[52] The digital water meter (1) is designed to operate down to -10°C. The upper operating temperature will be certified to +55°C, with solar loading adding an additional internal heat rise estimated to be up to 25°C. Internal components are selected to operate up to 85°C. Due to the low power consumption of the digital water meter, there is negligible heat load added from internal heat dissipation.

[53] A temperature sensor is included on the sun Printed Circuit Board Assembly (PCBA) at the highest point in a horizontally mounted meter to enable temperature to be measured. An event will be triggered in the DWM if internal temperature exceeds a configurable threshold.

[54] The enclosure design of the housing (2) provides a solar shield (24), which is intended to minimise the heat-rise from direct solar radiation on the digital water meter (1). The design for the battery bracket (25) also doubles as a heatsink / heat source from the flow tube assembly (10), which provides thermal stability for the battery (19) against regular ambient temperature cycling. This utilises the property of relatively constant supply water temperature throughout the year. The attachment of the battery (19) to this bracket (25) is intended to keep the battery at a temperature closer to the flow tube (10) temperature, which in turn helps improve battery life by reducing self-discharge at low and high temperatures.

[55] The battery (19) and temperature sensitive electronics components (i.e. the modem) are mounted close to the base of the housing (2) (when the meter (1) is installed horizontally), which is the most stable temperature zone of the meter. Experimental data has provided initial evidence of the battery temperature rising only up to 8°C above the ambient temperature, which assists in overall battery performance, longevity and lifespan management.

[56] The digital water meter (1) includes physical tamper detection (26) such as a meter lock (27) (as is best shown in Figure 4) that prevents the device from being disconnected following installation onsite at a residential or commercial property.

[57] As shown in Figure 4, a flange (28) is provided on the inlet to the digital water meter (1) to facilitate connection of the meter lock (27), with security screws (29) used to fasten the lock (27) to the flange (28). The security lock (27) covers the locking nut (30), which would need to be loosened in order to remove the meter once installed. The security lock (27) consists of an upper and a lower housings (31), that open to allow access to the locking nut (30), and when closed prevent removal of the locking nut (30). The screws connecting the lower housing to upper housing are located underneath the digital water meter (as installed), with non-security screws used for these connections. Their location provides difficult physical access in order to open the housing (2) when installed, and because of the use of a meter lock (27), the meter (1) cannot be rotated to access the screws after being installed. The screws connecting the housings are deeply recessed into the lower housing (when looking from beneath), which provides further difficulty to allow removal on an installed meter.

[58] Further, as best shown in Figure 5, the digital water meter (1) also includes plastic tamper evident plugs (32) for the housing. The housing connection non-security screws are sealed with fitted plastic plugs at manufacture. These prevent water ingress to the screws to minimise rusting, but primarily serve as evidence of attempted tampering if found to be removed on a meter (1), whether or not it is installed. For authorised removal, these plugs (32) can be drilled out, and new plugs re-fitted. As the digital water meter (1) is not serviceable when installed onsite, the only scenarios envisaged for drilling out plugs (32) are when a unit needs to be disassembled to investigate a failure or other issue requiring internal inspection.

[59] In addition to the external physical tamper detection components (26), the digital water meter (1) also includes internally located tamper detection sensors (33) within the housing (2) e.g. an IR sensor and an accelerometer that have a low power consumption.

[60] As best shown in Figure 6, the digital water meter (1) housing (2) also includes a radial seal (34) which provides an IP68 rating. The radial seal (34) is important as it ensures the housing (2) is sufficiently weatherproof so that the internal electronic components will not be affected by water ingress. The positioning of the radial seal (34) ring within the meter enables the digital water meter (1) to achieve an IP68 rating, but also allows for the seal (34) to be opened in order to replace the battery (to extend device life) and still retain IP68 rating.

[61] Whilst the housing (2) has been designed to minimise water ingress, it also preferably incorporates a hydrophobic vent (35) fitted in the lower housing base. This is designed to equalise pressure between the meter internal pressure and external air pressure. This method minimises the likelihood of condensation forming within the housing (2) with temperature cycling, but does not completely eliminate the likelihood of condensation. To protect against potential condensation and the chance of resultant short circuit conditions, the PCBAs are conformally coated and the battery terminals are heat shrink protected.

[62] As is best shown in Figure 7, the digital water meter (1) housing (2) is designed to provide an airflow path within the housing that provides passive thermal management. It is known electronics do not perform optimally when the thermal environmental conditions are not within the preferred operating temperature ranges. Accordingly, it is an important aspect of the present invention to provide passive thermal management to conserve battery drain, and extend the operational life of the water meter (1), and longevity of the battery (19). As shown in Figure 7, there is an inlet (12) on one side of the water meter (1) housing (2) into which cool air is drawn, and on the opposite side of the housing there is a warm air exhaust (11) , out of which the air heated within the housing escapes to the wider environment.

[63] As detailed above, the digital water meter (1) utilises ultrasonic measurement technology to determine the water volume passing through the meter, without requiring any moving parts. The water volume is displayed on the Indicating Device when requested, and is also made available over a Local Interface using Near Field Communication (NFC) technology if interrogated, and over a Remote Interface using loT technology as part of the daily status report.

[64] The digital water meter is designed to log a number of different events that can be detected, with any of these events being configurable as an alarm. If an alarm is configured to be “real-time”, it will trigger an alarm message over the Remote Interface when the alarm is activated. Logged event data is accessible over the Local Interface.

[65] Any event can be configured as an alarm, and any alarm can be configured for real time reporting. Further, any alarm can be configured for output to the Display. When an alarm has been triggered, it will remain triggered until cleared. There are different mechanisms available for clearing (or resetting) an alarm, depending on the type of alarm, including:

• Self-cleared - if the condition that originally triggered the Alarm is no longer set;

• Remote cleared - via the response to the daily status report from the loT Platform;

• Locally cleared - over the NFC interface using the NFC Application.

[66] A Real Time configured alarm will send an loT message as soon as it is triggered, subject to other constraints (e.g. network connectivity).

[67] The types of alerts/alarms that can be detected and monitored by the digital water meter of the present invention are set out below. [68] Continuous Low Flow Detection - A basic detection criterion will be used for determining a continuous low flow condition. This function is intended to detect a leak condition in the customer side water distribution that is not considered a normal usage scenario.

[69] Continuous High Flow Detection - This function is intended to detect a burst pipe or open valve condition in the customer side water distribution over an extended time period that is not considered a normal usage scenario.

[70] Reverse Flow Detection - In its preferred design, the digital water meter of the present invention is not designed to measure reverse flow. The meter has an integral dual check valve to prevent reverse flow from occurring. Nevertheless, despite having a redundant check valve, any water flow back into the utility supply could cause a contamination of the supply, so the consequences of such an event are considered catastrophic. For this reason, the meter is designed to detect a reverse flow condition. In addition to the detection of a reverse flow condition, it may also be useful data for the utility company to know the extent of a contamination event. Accordingly, the meter will measure any reverse flow rate to provide an order of magnitude contamination volume to the utility.

[71] Daily Peak Instantaneous Flow Rate - The meter constantly collects data from the GP-30 during water flow conditions, one parameter of which is the current flow rate. The meter maintains a register for the highest flow rate for the last detection period, the highest of which becomes the daily peak instantaneous flow rate.

[72] Low Battery Detection - The meter will monitor the battery to determine when the impedance of the battery increases to a defined level. This detection provides a 180 day notification window, within which the meter will continue to operate normally. This battery low detection event will be logged by the meter, and sent to the loT platform as part of the daily status.

[73] High Internal Temperature Detection - A temperature sensor is used on the Sun PCBA to detect internal temperature within the housing of the digital water meter. When this temperature becomes excessive, it could lead to a failure of the meter. It is preferred that even if the high internal temperature event is not triggered, the meter will still maintain a register for the maximum daily temperature. [74] Low Water Temperature Detection - A water temperature approaching 0°C in the meter will be approaching freezing point, and must be detected in order to raise an alarm to the loT Platform. This scenario is caused by cold environmental conditions on the exposed connected pipe and meter, in conjunction with a lack of water flow through the meter. Any water flowing through the meter will serve to raise the water temperature inside the meter, and avoid a freezing water condition.

[75] High Water Temperature Detection - A high water temperature inside the meter will most likely be caused by local heating of the exposed connected pipe and meter by hot environmental conditions. The meter trigger for this event is preferably configurable, but noting any water temperature above 30°C may impact the measurement accuracy of the digital water meter, and measurements not being possible at all at temperatures in excess of 80°C.

[76] Empty Pipe Detection - The meter is capable of detecting air in the water flow passing through it. The flow measurement device (GP-30) can be configured to detect air bubbles as well as the “no water” condition which is the extreme case of air bubbles. Air bubbles detected in the flow tube will not trigger an alarm as these are occasionally expected in normal operation. Any quantity of air bubbles will form some distortion of the measured flow rate. The GP-30 determines if measurements are corrupted (e.g. from air bubbles), and will not add to the accumulator value if measurement integrity is questionable.

[77] Internal Temperature - The modem regulates RF output power to maintain a die temperature that does not damage the device, and automatically backs off RF power at ambient temperatures above 65°C. As detailed above, it is expected that in direct sun exposure, the DWM will have a temperature rise of at most 25°C above ambient as measured on the Sun PCBA, noting this is even higher under the LCD.

[78] Time Drift Detected - The digital water meter operates with network time as its time source. If the meter resynchronises with network time and is detected to be > X3 seconds out from network time, this triggers a time drift event.

[79] Water Temperature - The daily extremes of water temperature (high and low) are maintained by the meter and reported out in the daily status report, with corresponding timestamps. [80] Daily Communications Power Usage - loT communications is a large power consumer, and can greatly affect the DWM service life. This metric is therefore monitored by the meter, in order to characterise the communications usage profiles and in order to optimise battery lifespan and performance. During loT Communications, the meter monitors the communications uptime, and also measures the average energy used over the communications period. The meter utilises a power monitoring device to determine the average energy used. This information is communicated out in the daily status report.

[81] Daily Communications Activity Time - This parameter is the aggregate of all loT communications time for a meter over the last 24 hour reporting period.

[82] As detailed above, to achieve the very long inherent service life (at least 15 years), of the battery and low power consumption, the digital water meter is typically placed in a low power mode following the manufacturing process, whereby in this low power mode (off state or idle state), the meter will only be ‘awoken’ for certain triggering events.

[83] Figure 8 shows the various ‘states’ of the digital water meter, which fall into three categories being an ‘off state’, a ‘non-operational state’ and an ‘operational state’.

[84] As detailed above, the digital water meter (1) is automatically placed into the OFF state post manufacture, and can only be awoken when the NFC interface is activated. The OFF state can be entered in multiple ways:

• Automatically after programming of the microcontroller (at PCBA manufacture).

• From Production Mode, automatically after DWM manufacture. This will be the end state after the EOL test is executed;

• From Production Mode, automatically after National Instrument Test Procedures (NITP) testing.

• From Functional Mode, after being commanded over the NFC interface.

[85] All transitions to the OFF state from Production Mode can be automated by virtue of air being detected in the flow tube as well as movement of the device (accelerometer detected changes). The meter can also be forced into the OFF State using an NFC command from Functional Mode. [86] However, an NFC power trigger is needed to transition the meter (1) from the OFF State. This is considered to be the safest method as there is a low risk this can be inadvertently set (falsely triggered) while the meter is not in service.

[87] To conserve power and improve battery lifespan, the digital water meter will spend the majority of its operational life in the idle mode. This is a low power mode that keeps basic functions operating such as RTC, with key components such as Modem and NFC being in a low power state. The microcontroller itself will be in the lowest power mode possible to retain volatile memory contents and to operate the RTC, while awaiting interrupts that provide a transition out of Idle Mode to Functional Mode.

[88] The functional mode provides the primary functionality for the digital water meter, including the following services, each of which will have a different power profile:

• Ultrasonic measurement (for water flow) & any associated computations;

• Display control & activation;

• Event (& Alarm) Management;

• loT Communications; and

• NFC Communications.

[89] While the invention has been described with reference to preferred embodiments above, it will be appreciated by those skilled in the art that it is not limited to those embodiments, but may be embodied in many other forms, variations and modifications other than those specifically described. The invention includes all such variation and modifications. The invention also includes all of the steps, features, components and/or devices referred to or indicated in the specification, individually or collectively and any and all combinations or any two or more of the steps or features.

[90] In this specification, unless the context clearly indicates otherwise, the word “comprising” is not intended to have the exclusive meaning of the word such as “consisting only of”, but rather has the non-exclusive meaning, in the sense of “including at least”. The same applies, with corresponding grammatical changes, to other forms of the word such as “comprise”, etc.

[91] Other definitions for selected terms used herein may be found within the detailed description of the invention and apply throughout. Unless otherwise defined, all other scientific and technical terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which the invention belongs.

[92] Any promises made in the present document should be understood to relate to some embodiments of the invention, and are not intended to be promises made about the invention in all embodiments. Where there are promises that are deemed to apply to all embodiments of the invention, the applicant/patentee reserves the right to later delete them from the description and they do not rely on these promises for the acceptance or subsequent grant of a patent in any country.

Claims

1. A digital water meter comprising: a processor, a power source in electronic communication with the processor, wireless communication means in electronic communication with the processor and the power source for wirelessly communicating with a network; and a housing within which the processor, power source and wireless communication means are housed; whereby the processor operates the digital water meter in a lower power mode in which the power output of the power source is conserved and the digital water meter is awaken only for certain triggering events during which, the processor controls the wireless communication means to wirelessly communicate with the network.

2. A digital water meter of claim 1 wherein the power source is a battery and the thermal design of the housing provides thermal stability by passive thermal management of the internal temperature within the housing, thereby improving battery performance and battery lifespan.

3. A digital water meter of claim 2 wherein the housing includes an inlet on one side thereof into which cool air is drawn from the environment external to the housing, and a warm air exhaust on the opposite side of the housing out of which the heated air from within the housing escapes to the environment outside of the housing, such that the inlet and exhaust provide an airflow path through the housing that provides the passive thermal management.

4. A digital water meter of claim 2 wherein the power source consists of a battery having primary cells and secondary cells.

5. A digital water meter of claim 4 wherein the primary cells are non-rechargeable cells and the secondary cells are rechargeable cells.

6. A digital water meter of claim 5 wherein the outer surface of the housing further includes one or more solar panels, and the secondary cells are recharged by the solar panels.

7. A digital water meter of claim 5 wherein the secondary cells act as a capacitor for large current drain events such as loT communications sent by the wireless communication means over the network, in order to smooth out the peak power drain from the primary cells.

8. A digital water meter of claim 1 wherein the water volume and flow rate are determined with an ultrasonic measurement device.

9. A digital water meter of claim 8 wherein the ultrasonic measurement device further includes an ultrasonic flow converter that controls ultrasonic pulses transmitted and received between two ultrasonic transducers.

10. A digital water meter of claim 8 further including a flow tube through which water flows in order to be measured by the ultrasonic measurement device, wherein the flow tube has three distinct zones where transition between two adjacent zones is bell shaped to minimize disturbances resulting from abrupt changes in flow area.

11. A digital water meter of claim 1 further including physical tamper detection means that prevent the water meter from being disconnected from a water pipe infrastructure following installation thereon.

12. A digital water meter of claim 11 wherein the physical detection means includes the following: a locking collar surrounding an attachment nut used to install the water meter to a water pipe; plastic tamper evident plugs that secure the housing together; and tamper detection sensors including IR sensors and accelerometers that have a low power consumption.

13. A digital water meter of claim 1 wherein the wireless communication means transmits information via network to a remote database, such information including a daily status report of a number of pre-determined parameters.

14. A digital water meter of claim 1 wherein the housing further includes a radial seal which provides an IP68 rating such that electronic components that are housed within the housing will not be affected by water ingress.

15. A digital water meter of claim 14 wherein the radial seal ring is positioned within the housing such that the seal can be opened to replace the power source in order to extend the device life of the water meter, but at other times, the radial seal ring provides the IP68 rating to the housing.

16. A digital water meter of claim 14 wherein the housing further incorporates a hydrophobic vent located in a base portion of the housing, which equalises pressure between the internal pressure within the housing and the external air pressure outside of the housing, which results in minimising condensation forming within the housing during temperature cycling therein.