Modular ultrasonic consumption meter

Abstract

A consumption meter arranged to measure the flow rate of a fluid, comprising: a pipe for allowing the fluid to pass between an inlet and an outlet; a plurality of individual flow meters arranged at the pipe to measure the split flow rate of the fluid; a first control circuit and a communication interface arranged to receive the measured split flow rate from each of the plurality of flow meters and to generate a signal indicative of the flow rate of the fluid based on the received split flow rate, each of the plurality of individual flow meters comprising: a flow meter housing arranged at the pipe; first and second ultrasonic transducers arranged in the flow meter housing for transmitting and receiving ultrasonic signals propagating through the fluid; a second control circuit arranged to operate the first and second ultrasonic transducers and to generate a signal indicative of the split flow rate of the fluid accordingly; and a communication interface arranged to send the signal indicative of the split flow rate to the first control circuit.

Description

Technical Field

[0001] The present invention relates to the field of ultrasonic consumption meters. More specifically, the present invention relates to the field of ultrasonic consumption meters or utility meters, which utility meters include ultrasonic flow meters, such as ultrasonic consumption meters for measuring consumption data of supplied utilities (e.g., water, gas, heat, or cooling). Background Art

[0002] Ultrasonic consumption meters are used to accurately measure the fluid flow related to the consumption meter for measuring the consumption of supplied utilities (e.g., heat, cooling, or water). The ultrasonic consumption meter measures the transit time of ultrasonic signals in order to determine the flow velocity of the fluid flowing in the flow channel by using the operating principle of a known transit time flow meter.

[0003] The consumption meter can simply measure the consumption amount (e.g., water volume), and the utility company can bill consumers based on this amount. However, for heat meters and cooling meters, temperature sensors are used to measure the temperature of the fluid, and thus consumers can be billed based on the energy extracted from the supplied liquid. Such ultrasonic consumption meters can be used in combination with district heating, district cooling, and / or distributed water supply.

[0004] A typical ultrasonic flow meter used as part of a consumption meter has an instrument housing, inside which there is a control circuit that is electrically connected to two or more spaced-apart ultrasonic transducers, such as piezoelectric transducers. The ultrasonic transducers are mounted on the flow channel in such a way that ultrasonic signals can be introduced into the fluid in the flow channel through one of the ultrasonic transducers and travel along the measurement section to be detected by another ultrasonic transducer after passing through. The operation of the ultrasonic transducers is controlled by a control circuit that is electrically connected to the transducers.

[0005] Especially for larger flow meters, the flow profile of the fluid inside the flow channel may vary significantly depending on the pipes connected to the flow meter, the flow velocity, etc. Therefore, for large instruments that require high-precision flow measurement, multiple sets of ultrasonic transducers are often required. The multiple sets of ultrasonic transducers are distributed on the flow channel to cover different parts of the flow channel cavity. The ultrasonic transducers are usually electrically connected to the control circuit inside the instrument housing through multiple cables, and the lengths of these cables must be long enough to connect the transducers placed far from the measurement circuit. The signals propagating in the cables are analog signals, and these analog signals may be distorted in the cables due to the characteristics of the cables or due to noise electromagnetically coupled to the cables. The measurement circuit will determine the flow velocity based on the analog signals received from all ultrasonic transducers.

[0006] The instrument housing surrounding the measurement circuit is preferably waterproof to avoid any moisture causing damage to the measurement circuit inside the instrument housing. However, the cable connecting the ultrasonic transducer to the measurement circuit does provide a potential path for water to enter the instrument housing. In the case of only minor damage to the cable, such as the outer layer of the cable, the cable will provide a path allowing water to enter the instrument housing. In particular, water meters may be submerged or operate in a high humidity environment, but heat meters and cooling meters may also operate in a humid environment.

[0007] The flow channels of prior art instruments are typically specially manufactured components made of metals such as brass, stainless steel or cast iron. The flow channels usually have a mounting seat for the transducer housing. The mounting seat can be a flat surface inside or outside the flow channel, or a threaded element for fixing the transducer housing. To introduce ultrasonic signals into the metal flow channel, the transducer housing is mounted in an opening in the wall of the flow channel. The cable connecting the ultrasonic transducer to the control circuit leaves the transducer housing and enters the instrument housing. Additional mounting elements for mounting the instrument housing (including the control circuit for the instrument) are provided on the flow channel. The flow channel is usually a specially manufactured component for a flow meter, requiring different manufacturing processes such as molding and machining and molds for each size variation of the flow meter. Alternatively, the flow channel is made of a prefabricated pipe of a size sufficient for the flow meter to be manufactured. This is especially true for large-sized instruments. The prefabricated pipe is a standard component that only needs to be cut to the appropriate length, thus eliminating the need for expensive special tools and processes associated with manufacturing the flow channel. However, the standard pipe requires holes and mounting seats on the transducer housing and the instrument housing. To form the mounting seat, a section can be cut out from the pipe wall and a new section including a surface for receiving the transducer assembly is welded at the position of the cut-out section. Manufacturing the flow channel becomes an expensive process, thus significantly increasing the total cost of the instrument.

[0008] Consumption meters typically require a large number of individual components, which complicates the assembly process. Therefore, prior art consumption meter housings involve complex connection structures (such as complex wiring structures and / or separate electrical connection elements) for electrically connecting the transducer to the measurement circuit of the consumption meter, which complicates the assembly process.

[0009] Therefore, an improved consumption meter would be advantageous, and in particular a more cost-effective modular consumption meter made of standard components would be advantageous. In addition, the consumption meter must be robust and suitable for operation in a high humidity environment. It would be advantageous to provide a consumption meter that allows for a simple and economical manufacturing method and allows pre-manufactured modular sub-assemblies to be put together in the final manufacturing step.

[0010] Object of the Invention

[0011] The object of the present invention is to provide an alternative to the prior art.

[0012] In particular, it can be seen that another object of the present invention is to provide a consumption meter that solves the above problems of the prior art and improves the known consumption meter in terms of manufacturing process, robustness, component cost, modularity and water resistance. Summary of the Invention

[0013] Therefore, in a first aspect of the present invention, it is aimed to achieve the above object and several other objects by providing a consumption meter arranged to measure the flow rate of a fluid, the consumption meter comprising: a pipe having a through opening for the fluid to pass between an inlet and an outlet; a plurality of individual flow meters arranged at the pipe to generate signals indicative of the sub-flow rate of the fluid; and a first control circuit including a communication interface arranged to receive signals indicative of the sub-flow rate from each of the plurality of flow meters and arranged to generate a signal indicative of the flow rate of the fluid based on the received sub-flow rate, each of the plurality of individual flow meters comprising: a flow meter housing arranged at the pipe; a first ultrasonic transducer and a second ultrasonic transducer arranged in the flow meter housing for transmitting and receiving ultrasonic signals propagating through the fluid; a second control circuit arranged to operate the first ultrasonic transducer and the second ultrasonic transducer and arranged to generate a signal indicative of the sub-flow rate of the fluid accordingly; and a communication interface arranged to send the signal indicative of the sub-flow rate to the first control circuit, wherein the flow meters are arranged on the same longitudinal section of the pipe or at least on overlapping longitudinal sections of the pipe.

[0014] The present invention is particularly but not exclusively advantageous in obtaining a robust modular consumption meter comprising a plurality of individual sealed and waterproof modules in the form of individual flow meters.

[0015] These individual flow meters (each individual flow meter including a second control circuit, a communication interface and ultrasonic transducers within the flow meter housing) have the following advantages: each flow meter is a single robust self-contained unit capable of measuring the sub-flow rate independently of any other element of the consumption meter. An instrument composed of such robust modules has the advantages of improved robustness and a simpler manufacturing process.

[0016] Each individual flow meter covers a different section of the tube, thereby forming multiple measurement paths, which has the advantage of improved measurement accuracy. Flow meters arranged in the same longitudinal section of the flow tube or in at least overlapping longitudinal sections of the flow tube have the advantage of improved measurement accuracy because the flow distribution can vary along the longitudinal direction of the flow tube.

[0017] An individual flow meter should be interpreted as a flow meter that is arranged to operate and measure the flow velocity independently of other flow meters. The split flow velocity is the flow velocity measured on the path of the ultrasonic signal propagating in the tube by a single independent flow meter. Thus, the split flow velocity is an independent measure of the flow velocity in the tube. The individual flow meter has a second control circuit that is arranged to operate the first ultrasonic transducer and the second ultrasonic transducer of the individual flow meter to transmit and receive ultrasonic signals of the fluid passing through the tube. The second control circuit is further arranged to generate a signal indicating the split flow velocity of the fluid based on the ultrasonic signals of the fluid passing through the tube that have been transmitted and received.

[0018] A consumption meter having a plurality of individual independent flow meters will be able to measure a plurality of split flow velocities. Doing so has the following advantages: The split flow velocity can be measured on multiple propagation paths, thereby generating a plurality of signals indicating the split flow velocity. These individual flow meters are preferably each arranged to transmit and receive ultrasonic signals propagating on paths different from those of the other individual flow meters. Each signal indicating the split flow velocity provides information about the flow velocity in the tube. The plurality of signals indicating the split flow velocity has the following advantage: The first control circuit can generate an improved signal indicating the flow velocity in the tube by combining the plurality of split flow velocities. In other words, the first control circuit is arranged to generate an improved or more accurate signal indicating the flow velocity of the fluid based on the received split flow velocities. In particular, in the case of stratified flow in the tube, the first control circuit will be able to generate a more precise signal indicating the flow velocity by combining the plurality of signals indicating the split flow velocities. A signal indicating any flow velocity can represent the flow velocity as a quantity per unit time or as a set of cumulative quantities.

[0019] The flow meter housing can be a waterproof and / or sealed enclosure, which is advantageous because the consumption meter is thus suitable for operation in a humid environment or even for underwater operation. A plurality of individual waterproof and / or sealed flow meters are particularly advantageous because water penetrating into one flow meter cannot spread from that flow meter to other parts of the consumption meter through connections such as cables. If one flow meter is damaged due to moisture, the other flow meters can continue to operate. Moreover, the first control circuit can be arranged to generate an improved or more accurate signal indicating the flow velocity based on the split flow velocities received from the flow meters that are still operating.

[0020] Each of the plurality of individual flow meters can further include a battery, which has the advantage that the flow meter is a self - contained unit capable of operating independently of other devices. Further, modular flow meters have the advantage that they can be pre - produced according to customer requirements, stocked, and installed on the consumption meter. As an alternative to having a battery in each flow meter, energy can be coupled into the flow meter through an inductive coupling interface, in particular resonant inductive coupling.

[0021] The communication interface can be a non - current - coupled communication interface. A consumption meter having a plurality of individual flow meters with no cables or current connections entering the flow meter housing or the meter housing has the advantages that the consumption meter is robust and there is no risk of water entering any housing through the cables or cable openings. Further, if water enters one housing, the water will not travel from one housing to another through the cables, which means the consumption meter can continue to operate with a reduced number of flow meters. In other words, the flow meter is a self - contained, sealed, and / or waterproof unit with no cables or other current connection parts passing through the wall of the flow meter housing. Thus, the flow meter is arranged such that there is no current connection between the inside and the outside of the flow meter housing. Accordingly, the flow meter housing provides electrical insulation between the inside and the outside of the flow meter housing. That the flow meter housing is sealed and / or waterproof is to be understood as meaning that there are no openings in the flow meter housing that allow water to enter, and the mechanical connections between different parts of the flow meter housing are sealed by a sealing device or joined by gluing or welding to prevent water ingress. In other words, the flow meter housing is air - tight / sealed air - tight. Thus, the flow meter housing is a sealed and waterproof enclosure arranged to prevent water from entering the interior of the flow meter housing. A non - current - coupled interface is to be understood as and can be any wireless communication interface, in particular a communication interface using electromagnetic radiation or a communication field. As an alternative, the communication interface can use sound waves to transmit data, in particular ultrasonic transducers can be used to receive and send sound waves carrying data information between flow meters through the fluid in the pipe.

[0022] The communication interface can be a wireless communication interface such as an RF communication interface or an optical communication interface. The RF interface is particularly advantageous because RF signals can propagate through the air without the need for a special communication medium. Alternatively, an external antenna or cable or waveguide structure can be provided to direct or guide the RF signal between the communication interfaces.

[0023] The consumption meter may be provided with a communication interface, which is an inductive coupling or capacitive coupling type communication interface. Inductive or capacitive communication interfaces are advantageous because communication can be carried out on the interface without radiating any significant amount of energy (such as RF signals) to the surroundings. Coupling between an internal coil and an external coil can be provided, whereby electromagnetic signals can be transmitted through the inductive communication interface. This has the advantage of reducing or facilitating the authorization process. Capacitive coupling including a capacitive coupling plate element will have similar advantages. Further, inductive, capacitive, RF, and optical communication interfaces all have the advantage of non-current coupling, i.e., no electrical connections such as cables or connectors are required between the first control interface and the second control interface.

[0024] All of these communication interfaces can be connected through a single communication line forming a communication bus, which interconnects the communication interface of the first control circuit with a plurality of individual flow meters. The communication bus has the following advantages: all units of the consumption meter including the communication interfaces coupled to the bus can communicate with each other in a point-to-point communication session.

[0025] The consumption meter can be arranged such that the flow meters are distributed substantially uniformly around the circumference of the pipe. Alternatively, the flow meters can be distributed non-uniformly around the circumference of the pipe. The flow meters can be arranged on the same longitudinal section of the pipe so that the split flow velocities cover the same longitudinal section of the pipe. Covering the same longitudinal section has the following advantages: different propagation paths of the ultrasonic signals provide a measure of multiple split flow velocities within the same longitudinal section of the pipe, thus improving the accuracy of the signal indicating the flow velocity provided by the first control circuit. The longitudinal direction of the pipe is defined by a line extending between the center of the inlet and the center of the outlet of the pipe. Alternatively, the flow meters can be arranged on at least overlapping longitudinal sections of the pipe.

[0026] As an alternative, the flow meters can be arranged at different / non-overlapping longitudinal sections of the pipe.

[0027] The first control circuit can be embedded in one of the flow meter housings in the flow meter housing. This has the advantage of reducing the number of housings because the first control circuit does not require its own housing. A further advantage is that there is no need to install an additional housing on the consumption meter. The flow meter housing embedded with the first control circuit can have a different form factor from the housings of the remaining flow meters.

[0028] The first control circuit and the second control circuit of one of the plurality of independent flow meters can further share a common communication interface.

[0029] The consumption meter can be arranged such that the flow meter housing has a portion extending into the transducer bore in the wall of the pipe. This has the advantage that a direct interface is formed between the flow meter housing including the ultrasonic transducer and the fluid in the pipe, whereby ultrasonic signals can be directly coupled between the transducer and the fluid in the pipe. The wall of the flow meter housing can provide a resonance window or membrane between the transducer and the fluid.

[0030] The consumption meter can have a flow meter housing that includes a main housing and a transducer housing, wherein the transducer housing is mounted on the inner wall of the pipe and has a portion extending into the transducer bore in the wall of the pipe, and the main housing is mounted on the portion extending into the transducer bore to form a waterproof and / or sealed enclosure. The transducer housing is fixed to the wall of the pipe and can include an inner transducer housing element and an inner transducer housing element that are arranged to engage through the transducer bore in the wall of the pipe, whereby the transducer housing is fixed to the pipe. This arrangement has the advantage that the flow meter housing can be mounted on standard prefabricated pipes such as seamless pipes or welded pipes. The standard pipe only needs to cut a transducer bore in the wall and form a flange suitable for this purpose at the end of the pipe.

[0031] The first control circuit can further be arranged to allocate measurement time slots for each of the flow meters by transmitting at least one measurement time slot to each flow meter through the communication interface, setting the measurement time slots for each flow meter so as to perform measurements at different time points, whereby none of the flow meters perform flow measurements simultaneously.

[0032] In other words, the first control circuit can be arranged to control the measurement timing of each of the flow meters via the communication interface and / or communication bus such that the flow meters do not perform split flow rate measurements simultaneously.

[0033] In this way, the flow meters can be synchronized by the first control circuit and controlled to avoid simultaneous split flow rate measurements.

[0034] This has the effect that ultrasonic signals from one flow meter performing split flow rate measurements do not interfere with the ultrasonic measurements of another flow meter performing split flow rate measurements simultaneously.

[0035] As an alternative, the flow meter can be arranged to measure the flow rate at random time points. Further, the flow meter can be arranged to detect ultrasonic measurement signals from other flow meters and discard flow measurement values that conflict in time with the flow measurements performed by other flow meters. This has the advantage that the consumption meter does not require a synchronization mechanism between the flow meters.

[0036] Further, the consumption meter may include a sleeve disposed inside the pipe. The sleeve is arranged to reduce the diameter of the pipe. This means that the diameter of the cavity of the flow pipe is reduced, thereby increasing the flow velocity. Further, the sleeve can be made with a lower inner diameter tolerance than the pipe, thereby improving the measurement accuracy. This is particularly advantageous when the pipe is made of standard prefabricated pipes, because the diameter of the pipe may vary slightly between the pipes. The effect of this is that prefabricated standard pipes with poor pipe diameter accuracy can be used.

[0037] The consumption meter may further include a display, which is controlled by the first control circuit to display consumption data. The display can be embedded in one of the flow meter housings in the flow meter housing. Description of the Drawings

[0038] The consumption meter according to the present invention will now be described in more detail with reference to the accompanying drawings. One way of implementing the present invention is shown in the drawings and should not be construed as being limited to other possible embodiments falling within the scope of the appended claims.

[0039] Figure 1 A consumption meter having three individual flow meters is shown;

[0040] Figure 2a and Figure 2b Individual flow meter housings in closed and cut-away forms are shown;

[0041] Figure 3 A consumption meter with a cut-away cross-section is shown, showing the flow meter mounted on the pipe. Detailed Description of the Invention

[0042] Now referring to Figure 1 , a modular consumption meter 100 is described, including three individual ultrasonic flow meters 200, a first control circuit, and a communication line 302.

[0043] The consumption meter further includes a pipe 101 having an inlet 102 and an outlet 103, a cavity for guiding fluid, and flanges 104 disposed at each end of the pipe for connecting the consumption meter to the pipeline at the installation site.

[0044] Each individual flow meter includes a sealed and waterproof flow meter housing 201, a set of ultrasonic transducers 204, a second control circuit, a battery, and an inductive communication interface, wherein the sealed and waterproof flow meter housing 201 is arranged to enclose the other components. The flow meter is arranged to be inductively coupled to a communication line 302 disposed on the outer surface of the pipe 101. The flow meter is a self-contained sealed and waterproof unit without cables or connections passing through the flow meter housing, thereby achieving a robust modular structure.

[0045] The first control circuit of the consumption meter is arranged in the meter housing 105, which is embedded in or integrated with one of the flow meters in the flow meter 200. The ultrasonic flow meter is arranged to measure the flow velocity of the fluid flowing through the cavity of the pipe, and generate a signal indicating the flow velocity and transmit the signal to the first control circuit. The first control circuit is arranged to receive the signal indicating the flow velocity and generate a signal indicating the flow velocity of the fluid in the pipe according to the received flow velocity.

[0046] A single flow meter 200 is arranged at the pipe and distributed on the circumference of the pipe, whereby different segments of the cavity of the pipe are covered by different flow meters. Since the flow rates in different segments of the pipe may be different, more accurate flow rate measurements can be obtained by combining the sub-flow rate measurements covering different segments of the pipe.

[0047] Especially for large-sized consumption meters, the flow velocity in the cavity of the pipe may change significantly between different segments of the cavity. It is usually described as flow distribution. The flow distribution is dynamic and depends on other parameters such as flow velocity, pressure and temperature.

[0048] For large-sized flow meters, especially at low flow velocities, stratified flow may occur, in which the fluid may be stratified due to temperature differences in the fluid, resulting in different flow velocities between segments of the cavity. Layers with different temperatures will have different flow velocities.

[0049] The pipeline of the equipment to which the consumption meter is connected may affect the flow rate in the pipe and lead to unpredictable flow distribution.

[0050] The ultrasonic flow meter measures the flow velocity in the propagation path of the ultrasonic signal through the fluid from one ultrasonic transducer to another ultrasonic transducer. This means that only the flow velocity of the fluid in the segment of the cavity covered by the propagation path is included in the measurement. To ensure sufficient accuracy of the flow rate measurement, multiple sub-flow rate measurements with different propagation paths are performed. The sub-flow rate measurements are performed by individual flow meters distributed on the circumference of the pipe to cover different segments of the cavity.

[0051] The use of multiple flow meters is especially relevant to larger flow meters. The diameter of the pipe can be in the range of 4 - 48 inches and is arranged to measure flow velocities up to 1200 M3 / h.

[0052] The flow meters can be evenly distributed on the circumference of the pipe, or they can have another distribution to optimize the flow rate measurement.

[0053] The number of flow meters depends on the size of the pipe as well as the required accuracy and flow distribution. A typical consumption meter may include up to 5 flow meters, but for large-sized high-precision consumption meters, up to 10 flow meters may be required to achieve the desired accuracy.

[0054] The flow meter is an ultrasonic flow meter of the transit-time flow meter type, which is arranged to measure the flow velocity of a fluid flowing in a pipe by utilizing the operating principle of a known transit-time flow meter, where an ultrasonic signal is transmitted at one ultrasonic transducer and received at another ultrasonic transducer, and where the time difference of arrival between the oppositely propagating signals is measured and converted into a flow velocity. Ultrasonic flow meters using the transit-time or time-of-flight principle are well known in the art.

[0055] The flow meters 200 each include two ultrasonic transducers 204, such as piezoelectric transducers, which are operated by a second control circuit also included in the flow meter. Based on the signals involved, the second control circuit generates a signal or value indicative of the flow velocity of the fluid within the pipe.

[0056] The flow meter also includes a battery enclosed by the flow meter housing and is self-contained, without the need for electrical connection to other components or an external power source. The flow meter is enclosed within a waterproof flow meter housing 201. All components of the flow meter (including the ultrasonic transducers 204) are enclosed by the flow meter housing 201. The flow meter housing does not include openings that allow water to enter, and the mechanical connections between the parts of the flow meter housing are sealed by a sealing means (such as an O-ring, gasket, or other sealing means). Alternatively, the parts of the flow meter housing can be mechanically connected by using gluing, welding, brazing, or other suitable techniques to prevent water entry.

[0057] The flow meter housing 201 includes a main housing 202 and a transducer housing 203. The two parts of the housing are connected / joined by a sealed waterproof connection. The flow meter 200 is arranged at the pipe 101. The pipe has a transducer bore 106, which is arranged to receive the flow meter housing such that the transducer housing extends into the transducer bore, thereby forming contact with the fluid in the pipe. The transducer housing 203 includes an internal transducer housing element 207 arranged at the inner surface of the pipe 101 and an external transducer housing element 208 arranged at the outer surface of the pipe. The internal transducer housing element 207 and the external transducer housing element 208 are arranged to be joined through the transducer bore 106 in the wall of the pipe 101 such that the transducer housing 203 is fixed to the pipe. The two elements of the transducer housing are connected / joined by a sealed waterproof connection. The main housing 202 is arranged to engage with the external transducer housing element to form a closed and sealed waterproof flow meter housing 201.

[0058] All components of the flow meter housing 201 are connected or joined using a sealing means such as an O-ring or gasket. The sealing means can be made of rubber or fibrous material. In addition, a sealing means is provided between the internal transducer housing element and the inner surface of the pipe to prevent fluid from flowing through the transducer bore. The sealing means is not shown in these figures.

[0059] The ultrasonic transducer 204 is excited by a second control circuit to generate an ultrasonic signal that penetrates the internal transducer housing element 207 and propagates into the fluid within the tube. The internal transducer housing element 207 forms a resonant window 209 between the ultrasonic transducer and the fluid in the tube. The resonant window ensures acoustic impedance matching between the ultrasonic transducer and the fluid within the tube. As an alternative to the resonant window, the internal transducer housing may include a membrane such as a metal film to separate the ultrasonic transducer from the fluid within the tube.

[0060] The ultrasonic transducers 204 of a flow meter are all arranged on the same side of the tube 101. The transducers do not directly face each other, and the propagation of the ultrasonic signal within the tube is reflection-based. The signal is reflected by reflectors arranged within the tube. Additionally, the transducers are tilted at a non-vertical angle with respect to the centerline of the tube. As an alternative to the reflector, the inner wall of the tube may be used to reflect the ultrasonic signal. As an alternative to the non-vertical angle of the ultrasonic transducers, the reflector may be tilted. The use of reflectors within the tube and the tilting of the ultrasonic transducers and reflectors are well known in the art.

[0061] The flow meter housing element is made of a polymer material or alternatively of a composite material. As an alternative, the flow meter housing or parts of the housing may be made of metal (e.g., stainless steel, brass, or other suitable metals).

[0062] The flow meter housing element may be made of a polymer material selected from, but not limited to, the group including: polyphenylene sulfide (PPS), polyethersulfone (PES), and polysulfone (PSU).

[0063] It should be noted that the properties of the polymer material can be customized by adding certain additives prior to the molding process, thereby affecting material properties such as stiffness, density, or acoustic impedance. Examples of potential additives include reinforcing materials such as glass fibers, density-increasing fillers such as chalk (calcium carbonate, CaCO3), or powdered stainless steel that increases the acoustic impedance of the material.

[0064] The flow meter further includes a communication interface for sending a measurement signal indicative of the flow rate to the first control circuit. The communication interface is an inductively coupled communication interface that does not require an electrical connection, and thus, no wires need to enter the flow meter housing to support the communication interface. The communication interface includes an internal coil 210 within the flow meter housing 201, which is arranged to be inductively coupled to an external coil 301 of a communication line 302 that interconnects the flow meter 200 with the first control circuit.

[0065] The communication interface is a bidirectional communication interface and can be used to transmit other data than the shunt flow rate, such as configuration data and synchronization data for controlling the measurement of the shunt flow rate. Further SW updates and general configurations of the flow meter can be transmitted via the communication interface. In a simplified form, the communication interface can be a unidirectional communication interface, where the flow meter only sends data to the first control circuit.

[0066] When the flow meter sends data, the communication interface modulates the data (such as data related to the shunt flow rate) on a carrier signal to form a modulated signal. The modulated signal is inductively coupled from the internal coil 210 of the communication line 302 to the external coil 301. The signal propagates through the communication line to another external coil 301, which is inductively coupled to the internal coil of the communication interface of another flow meter and / or the first control circuit. The communication interface receives the signal inductively coupled from the external coil to the internal coil and demodulates the signal to extract the data content.

[0067] The frequency of the carrier signal is 200 kHz. Any suitable carrier frequency can be selected. In particular, carrier frequencies in the range of 32 kHz to 500 KHz have the following advantages: the signal can be modulated by a standard microcontroller unit, while the coils used for inductive coupling remain relatively small, and the current consumption of the microcontroller remains low at the same time. The modulation used is on-off keying (OOK), but any modulation scheme such as frequency shift keying (FSK), phase shift keying (PSK), amplitude shift keying (ASK), etc., as well as analog modulation schemes can also be used. The signal is modulated at a data rate of 1200 baud, but alternative baud rates from 110 baud to 19200 baud or even up to 100000 baud can be used, depending on the carrier frequency, modulation scheme, and inductive coupling circuit.

[0068] Simple asynchronous communication using start bits and stop bits can be used at the physical layer. A link layer protocol including data integrity checks is included to ensure data integrity. A transport layer protocol can be included to prevent data loss on the communication link. Other protocol layers can be added to ensure data authenticity and confidentiality. Further, the first control circuit can perform a discovery process to identify all flow meters connected to the communication line, or alternatively, configure the identification of the flow meters to the first control circuit. Data communication protocols are well known to those skilled in the art, and it is routine work to select those protocols that provide sufficient quality of service.

[0069] The (modulated) and detected (demodulated) modulated signal is generated by a standard microcontroller that docks directly with the coil or docks through one or more amplifier circuits and filter circuits. Alternatively, a dedicated communication circuit or chip can be used.

[0070] The coil is matched with the carrier frequency to generate a resonant coupling between the coil of the inductive communication interface and the communication line. The internal coil 210 of the flow meter is implemented in the conductive layer of the printed circuit board (PCB) of the second control circuit. Alternatively, the coil can be a wound coil that is installed inside the flow meter housing, directly mounted on the PCB, or connected to the PCB.

[0071] The communication line 302 includes a plurality of external coils 301 that are arranged for coupling with the internal coil 210 of the flow meter and / or the first control circuit.

[0072] Inductive communication interfaces are well known to those skilled in the art, and several types of near-field magnetic induction (NFMI) communication systems can be used for the inductive communication interface. Examples of such technologies include standardized technologies such as NFC, RFID, IO-Link, or proprietary technologies disclosed in EP1866605, EP 1393281, EP 0131732.

[0073] As an alternative to the inductive communication interface between the flow meter and the first control circuit, a wireless communication interface using radio frequency communication can be used. RF communication can be based on communication standards or proprietary communication protocols such as the wireless MBus standard (EN13757-4 2013), Zigbee, KNX, or Bluetooth. As yet another alternative, the communication interface can be a capacitive coupling type or an optical communication interface. The essential feature of the communication interface is that there is no need to have a wire (i.e., current) connected to the flow meter housing.

[0074] The communication link can further be used to transfer energy between flow meters or between a flow meter and the first control circuit to eliminate the need for batteries in all parts. Energy transfer through the inductive interface is also well known and has been described in the context of the above inductive communication interface.

[0075] The first control circuit is arranged to receive all signals from the flow meter indicating the split flow rate and to generate a signal indicating the flow rate of the fluid in the pipe based on the received split flow rate. The signal indicating the flow rate is based on a calculation performed on the received split flow rate. The flow rate is calculated as the average of all split flow rates such that the flow rate is equal to the average flow rate. Alternative calculations of the flow rate can be performed using more advanced methods or statistical methods. In particular, split flow rates that deviate significantly from the previous or subsequent split flow rates or the average flow rate can be discarded to reduce the impact of measured incorrect split flow rates.

[0076] The first control circuit is arranged to continue with the flow calculation as long as at least one shunt flow rate is received, even if no shunt flow rate is received from one or more flow meters. The consumption meter can be approved by the relevant national or regional authority to measure the consumption and / or flow rate based on the number of active flow meters, according to different criteria, permissions or accuracy requirements.

[0077] The flow measurement performed by a single flow meter can be carried out in its simplest form at random time points. However, measurement time conflicts can occur between measurements made by different flow meters, which can interfere with the measured values. As described above, such interfering measured values can be detected and discarded.

[0078] Optionally, to avoid conflicts, the flow meters can be synchronized to prevent two flow meters from making measurements at the same time point. The first control circuit controls the timing of the consumption meter and includes a timer unit with a continuously running timer. The first control circuit sends a time synchronization signal to each flow meter, where the second control circuit receives the time synchronization signal, and the second control circuit also includes a timer unit and a continuously running timer. Further, the first control circuit assigns measurement time slots to each flow meter. The measurement time slots are also transmitted to each meter via a communication interface. The time slots for each flow meter are set such that measurements are performed at different time points, i.e., no two flow meters will perform flow measurements at the same time.

[0079] In an alternative and simpler method, measurement conflicts are avoided because the first control circuit is arranged to send a request for a measurement signal on the communication interface. The request for the measurement signal is made separately for each flow meter, and when received by the proposed flow meter, the flow measurement is started, and subsequently, the resulting signal indicating the shunt flow rate is sent to the first control circuit.

[0080] As Figure 1 shown, the first control circuit of the consumption meter is arranged in the meter housing 105, which is embedded or integrated in one of the flow meter housings of these flow meter housings to form a combined housing. In this way, the first control circuit and the flow meter become a combined unit. The first control circuit shares the communication interface, battery and other common parts with the flow meter, and is integrated with the flow meter to form a combined unit. The communication between the first control circuit and the second control circuit of the combined unit does not need to be coupled to a communication line that can pass through the inside of the combined housing. The combined unit can share additional components such as a printed circuit board, a microcontroller, a power supply unit, etc. In this way, the first control circuit and the second control circuit of the combined unit can become a combined circuit.

[0081] As an alternative, the meter housing can be a separate housing arranged on the consumption meter or an external element arranged remotely from the consumption meter. However, it is required that the first control circuit arranged in the meter housing has access to the communication link.

[0082] The consumption meter can further include a display controlled by the first control circuit. The display can be integrated in the meter housing or be an external display.

[0083] The tube is made of a standard prefabricated tube such as seamless / extruded tube or welded tube. A flange 104 is welded at the end of the tube, and transducer holes are cut in the tube wall, for example, by laser cutting. Alternatively or additionally, the end of the tube can be shaped / machined or milled to form a flange end.

[0084] The standard tube can be, but is not limited to, a standard tube designed and manufactured according to EN ISO 1127:1997 or ANSI / ASME B 36.19:2004 or ASTM A 530:2018 or ASTM B677:2016.

[0085] The tube is made of a metal alloy such as brass, red brass, stainless steel, cast iron or other suitable alloy.

[0086] In an alternative embodiment, the tube can be made of a polymer.

[0087] A sleeve 107 is arranged inside the tube. The sleeve reduces the inner diameter 101 of the tube. The sleeve has holes arranged to match the transducer holes in the tube. The transducer housings 207, 208 extend into the holes in the sleeve. The sleeve fixes the inner transducer housing element 207 to prevent rotation about the center point of the transducer hole. A sealing device is arranged between the outer surface of the sleeve and the inner surface of the tube to minimize the flow in the space between the sleeve and the tube. Reflectors for reflecting ultrasonic signals are arranged on the inner surface of the sleeve. As an alternative, the sleeve can only extend in the section between the transducer holes, in which case holes for the transducer housings are not required.

[0088] The consumption meter can be any type of utility meter such as a water meter for cold and / or hot water, a gas meter, a heat meter, a cooling meter, an energy meter or a smart meter. The consumption meter can be used in combination with district heating, district cooling and / or distributed water supply. The energy meter can include one or more temperature sensors to calculate the thermal energy in the fluid flowing into and / or out of the consumption site through the tube, whereby the energy consumption can be calculated.

[0089] The consumption meter can be a legal meter, i.e., a meter subject to regulatory requirements. Such regulatory requirements may be requirements for measurement accuracy.

[0090] Although the present invention has been described in connection with specific embodiments, it should not be construed as being limited in any way to the examples given. The scope of the present invention is set forth by the appended claims. In the context of the claims, the term "comprising" or "comprises" does not exclude other possible elements or steps. Furthermore, references to, for example, "a" or "an" should not be construed as excluding a plurality. The reference signs used in the claims with respect to elements indicated in the drawings should also not be construed as limiting the scope of the present invention. In addition, the various features mentioned in different claims may possibly be advantageously combined, and the mention of these features in different claims does not exclude the combination of the features from being impossible and advantageous.

Claims

1. A consumption meter arranged to measure the flow rate of a fluid, the consumption meter comprising: - a pipe (101) having a through opening for allowing the fluid to pass between an inlet (102) and an outlet (103); - a plurality of individual flow meters (200) arranged at the pipe (101) to generate signals indicative of the split flow rate of the fluid; and - a first control circuit including a communication interface arranged to receive from each of the plurality of flow meters (200) a signal indicative of the split flow rate and arranged to generate a signal indicative of the flow rate of the fluid based on the received split flow rate, each of the plurality of individual flow meters comprising: - a flow meter housing (201) arranged at the pipe (101); - a first ultrasonic transducer and a second ultrasonic transducer (204) arranged in the flow meter housing (201) for transmitting and receiving ultrasonic signals propagating through the fluid; - a second control circuit arranged to operate the first ultrasonic transducer and the second ultrasonic transducer (204) and arranged to generate accordingly a signal indicative of the split flow rate of the fluid; and - a communication interface arranged to send the signal indicative of the split flow rate to the first control circuit, wherein the flow meters are arranged on the same longitudinal section of the pipe or on at least overlapping longitudinal sections of the pipe.

2. The consumption meter according to claim 1, wherein the flow meter housing (201) is a waterproof enclosure.

3. The consumption meter according to claim 1, wherein the flow meter housing (201) is a sealed enclosure.

4. The consumption meter according to claim 1, wherein each of the plurality of individual flow meters (200) further comprises a battery.

5. The consumption meter according to claim 1, wherein the communication interface is a non-current-coupled communication interface.

6. The consumption meter according to claim 1, wherein the communication interface is a wireless communication interface.

7. The consumption meter according to claim 6, wherein the wireless communication interface is an RF communication interface or an optical communication interface.

8. The consumption meter according to claim 1, wherein the communication interface is an inductively coupled or capacitively coupled communication interface.

9. The consumption meter according to claim 1, further comprising a communication bus interconnecting the communication interface of the first control circuit with the plurality of individual flow meters (200).

10. The consumption meter according to claim 1, wherein the flow meters (200) are substantially evenly distributed on the circumference of the pipe (101).

11. The consumption meter according to claim 1, wherein the first control circuit is embedded in one of the flow meter housings (201).

12. The consumption meter according to claim 1, wherein the first control circuit and the second control circuit of one of the plurality of individual flow meters (200) share a common communication interface.

13. The consumption meter according to claim 1, wherein The flow meter housing (201) has a portion extending into the transducer hole in the wall of the pipe (101).

14. The consumption meter according to claim 1, wherein, the flow meter housing (201) includes a main housing (202) and a transducer housing (203), wherein the transducer housing is mounted on the inner wall of the pipe and has a portion extending into the transducer hole in the wall of the pipe, and the main housing (202) is mounted on the portion extending into the transducer hole to form a waterproof enclosure.

15. The consumption meter according to claim 1, wherein, the flow meter housing (201) includes a main housing (202) and a transducer housing (203), wherein the transducer housing is mounted on the inner wall of the pipe and has a portion extending into the transducer hole in the wall of the pipe, and the main housing (202) is mounted on the portion extending into the transducer hole to form a sealed enclosure.

16. The consumption meter according to claim 9, wherein, the first control circuit is arranged to control the measurement timing of each of these flow meters via the communication interface and / or the communication bus such that these flow meters do not perform measurements simultaneously.

17. The consumption meter according to claim 1, wherein, the first control circuit is arranged to allocate measurement time slots for each of these flow meters by transmitting at least one measurement time slot to each flow meter via the communication interface, setting the measurement time slots for each flow meter such that measurements are made at different points in time, thereby ensuring that these flow meters do not all perform flow measurements simultaneously.

18. The consumption meter according to claim 1, further comprising a display, the display being controlled by the first control circuit to display consumption data.

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