LIQUID METER WITH ALTERNATIVE POWER SUPPLY

Description

TECHNICAL FIELD

[0001] The invention belongs to the technical field of fluid meters. A fluid meter is a metrology device configured to perform metrological measurements in a fluid circulation pipeline. The fluid may be liquid, such as water or oil, or gaseous, such as a gaseous mixture of hydrocarbons consisting primarily of methane such as natural gas. The metrological measurements are generally a volume or flow rate relative to the fluid circulating in the pipeline. STATE OF THE ART

[0002] In order to know certain metrological data concerning the circulation of a fluid in a pipeline, a fluid meter is usually used to generate and make available metrological measurements. In order to record these metrological measurements, fluid meters equipped with means of communicating information relating to said metrological data have been developed. These means of communication can be adapted for remote communication, and for example allow wired or wireless transmission of this information. The means of communication can also present several pieces of information in a display, organized according to menus. In all cases, these metrological meters require a power supply.However, the meters may be located in locations that do not allow easy connection to the electricity network, so they must have an independent power supply, not connected to the electricity network.

[0003] The simplest way to power a fluid meter independently is to equip it with an electric battery, i.e. an energy storage element that cannot be recharged on-site. However, the energy storage capacity must be sufficient to provide a power supply for a long period (typically 20 years), which means using very large batteries. In addition, the battery life depends on the meter's power consumption, which can significantly reduce the battery life, which in any case eventually runs out and must be changed, a tedious operation requiring monitoring of the battery's condition.

[0004] State of the art document JP 2002 270908 A shows a fluid meter for performing metrological measurements with a control block for receiving the measurements and communicating the corresponding information and the meter comprises a thermoelectric generator and an energy storage unit.

[0005] In order to overcome these drawbacks, it has been proposed to replace the electric battery with a rechargeable battery, for example powered by an electric generator configured to be driven by the circulation of the fluid in the pipe and generate electricity to recharge the battery.

[0006] However, the potentially intermittent nature of fluid circulation requires a battery with significant electrical storage capacity, which results in high bulk and costs. In addition, the irregularity of fluid circulation episodes can increase the number of incomplete charge-discharge cycles of the battery, reducing its performance over time. STATEMENT OF THE INVENTION

[0007] The invention therefore aims to propose a fluid meter equipped with an electrical power supply with a long service life, less bulky and more reliable.

[0008] The subject of the invention is a fluid meter configured to carry out metrological measurements in a fluid circulation pipeline and to communicate information relating to said metrological data, comprising: a fluid pipeline, at least one metrological sensor configured to perform metrological measurements in the fluid pipeline, a control unit configured to receive the metrological measurements and to communicate information relating to said metrological data, a power supply unit configured to supply power to the control unit, the power supply unit comprising a first power supply path comprising at least one battery, and a second power supply path, the power supply unit further comprising a first switch configured to selectively couple the first power supply path or the second power supply path to the control unit.

[0009] The fluid meter includes a thermoelectric generator configured to produce electricity from a temperature difference between an exterior of the pipe and the fluid in the pipe, the second power path being connected to the thermoelectric generator.

[0010] This device is advantageously supplemented by the following characteristics taken alone or in all their technically possible combinations: the thermoelectric generator comprises one or more thermoelectric modules partially inserted into a wall of the pipe; a protrusion is formed on the fluid circulation pipe, the protrusion comprising at least one cavity, each cavity being configured to receive a thermoelectric module; the wall of the pipe has a first thickness outside the protrusion, each cavity comprising a protective portion and a receiving portion, the receiving portion being of a diameter smaller than the protective portion and being arranged in the wall of the pipe at a distance from the inside of the pipe less than the first thickness, each thermoelectric module comprising a first portion configured to be at the temperature of the outside of the pipe and a second portion configured to be at the temperature of the fluid, the second portion being inserted into the receiving portion;the thermoelectric generator comprises a first external connector in contact with the first portion of a first thermoelectric module arranged at the input of the thermoelectric generator and connecting said first portion to the power supply unit, the thermoelectric generator further comprising a second external connector in contact with the second portion of a last thermoelectric module arranged at the output of the thermoelectric generator and connecting said second portion to the power supply unit; a second portion of a thermoelectric module is connected by an internal connector to the first portion of another thermoelectric module;each thermoelectric module is composed of a first thermoelectric material having a first Seebeck coefficient, and a connector in contact with the first portion or the second portion of the thermoelectric module is composed of a second thermoelectric material having a second Seebeck coefficient different from the first Seebeck coefficient; the second power path comprises a capacitor and a second switch configured to selectively couple the capacitor and the thermoelectric generator according to a charge level of the capacitor; the charge level is determined by the control block according to a first look-up table and the temperature difference when the capacitor charges, and according to a second look-up table and functions implemented by the control block when the capacitor discharges;the control block is configured to, at least when the thermoelectric generator generates electricity: position the first switch on the second supply path when the charge level becomes greater than a high threshold; position the first switch on the first supply path when the charge level of the capacitor becomes less than a low threshold; the high threshold is greater than or equal to 80% of a maximum charge level, and the low threshold is less than or equal to 10% of the maximum charge level; the control block is configured to determine a temperature difference between the outside of the pipe and the fluid and to: open the second switch when the temperature difference is less than a minimum temperature difference threshold; close the second switch when the temperature difference is greater than or equal to a minimum temperature difference threshold;the minimum threshold of temperature difference is between 2°C and 5°C.;

[0011] The invention also relates to a method for managing the power supply of a fluid meter as defined above, the fluid meter comprising a control unit and a power supply unit configured to supply energy to the control unit, the power supply unit comprising a first power supply path comprising at least one battery, and a second power supply path, the power supply unit further comprising a first switch configured to selectively couple the first power supply path or the second power supply path to the control unit, the second power supply path being connected to a thermoelectric generator configured to produce electricity from a temperature difference between an exterior of the pipe and the fluid in the pipe,the second power supply path further comprising a capacitor and a second switch configured to selectively couple the capacitor and the thermoelectric generator according to a charge level of the capacitor, the method being capable of being implemented by the control block and comprising the following steps:, Switching the first switch to the first supply path, Determining a temperature difference between an exterior of the pipe and the fluid and, when the determined temperature difference becomes greater than or equal to a minimum threshold, closing the second switch, Estimating a charging current from the temperature difference and a first correspondence table providing an estimate of the associated charging current for each value of the temperature difference, Determining a charging level of the capacitor under charge from the estimated charging current and, when the estimated charging level becomes greater than or equal to a predetermined high threshold, switching the first switch to the second supply path,Estimation of a discharge current carried out from functions implemented by the control block and a second correspondence table providing for each function implemented by the control block an estimate of the associated discharge current, Determination of a charge level of the capacitor in discharge as a function of the estimate of the discharge current and, when the estimated charge level becomes less than or equal to a predetermined low charge threshold, repetition of the previous steps.

[0012] The invention also relates to a computer program product capable of being implemented by a control block of a fluid meter as defined previously, comprising instructions which, when the program is executed by the control block, lead the control block to implement the method as defined above.

[0013] Finally, the invention also relates to a computer-readable memory storing instructions executable by the computer for executing the steps of the method as defined previously. DESCRIPTION OF FIGURES

[0014] Other characteristics, aims and advantages of the invention will emerge from the following description, which is purely illustrative and non-limiting, and which must be read in conjunction with the appended drawings in which: there Figure 1 is a schematic overview of a fluid meter according to a possible embodiment of the invention; Figure 2 is a top view of a first embodiment of the protrusion and cavities of the fluid meter pipe; Figure 3 is a top view of a second embodiment of the fluid meter pipe protrusion and cavities; and Figure 4is an implementation diagram of a fluid meter according to a possible embodiment of the invention.

[0015] Throughout the figures, similar elements have identical references. DETAILED DESCRIPTION OF THE INVENTION

[0016] There Figure 1shows a fluid meter configured to perform metrological measurements relating to a fluid circulating in a fluid circulation pipe 2 defined by a wall 3 separating an interior of the pipe 2 in which the fluid circulates, and an exterior to the pipe 2. The fluid meter is also configured to communicate information relating to said metrological data. Typically, the fluid circulation pipe 2 is part of the fluid meter in the sense that the fluid meter comprises a portion of pipe in which the fluid circulates, which is integrated into the fluid circulation network. To perform metrological measurements, the fluid meter comprises at least one metrological sensor 4 configured to perform metrological measurements in the fluid pipe 2. The metrological sensor 4 is preferably arranged in the fluid pipe 2.The type of metrological sensor 4 depends on the technology used to perform the measurements, which may be ultrasonic, electromagnetic, thermal or Coriolis technology. In the example illustrated, two ultrasonic transducers are arranged opposite each other in the pipeline in order to perform metrological measurements by ultrasound, in a known manner. The metrological measurements are generally a volume or a flow rate relative to the fluid flowing in the pipeline 2, derived from the data collected by the metrological sensor(s) 4.

[0017] The fluid meter comprises a control unit 6 comprising at least one processor and one memory, and which is configured to receive the metrological measurements from the metrological sensor 4, and to communicate the information relating to said metrological data. Typically, the metrological sensor 4 can be connected to the control unit 6, for example by a wired connection, and transmits the metrological measurements to the control unit 6.

[0018] The communication of the information relating to the metrological data is carried out by display on a screen and / or by transmission. The fluid meter may thus have a display screen 7 where the information relating to the metrological data can be displayed. The fluid meter may be provided with a human-machine interface such as a button making it possible to cause the display of this information relating to the metrological data, and possibly to vary this display, for example by making it possible to scroll through different types on the display screen 7. The information relating to the metrological data may be transmitted outside the fluid meter, preferably by a wireless link, in which case the fluid meter may comprise an antenna and any other known element making it possible to establish remote communication with the fluid meter.

[0019] Preferably, the fluid meter complies with the European Union Directive 2014 / 32 / EU on measuring instruments, better known by its acronym MID for "Measuring Instruments Directive". In particular, the fluid meter must be able to communicate information relating to metrological data at all times. Similarly, the fluid meter must be able to carry out metrological measurements at all times. Therefore, the fluid meter must have a permanent power supply.

[0020] For this purpose, the fluid meter comprises a power supply unit 10 configured to permanently supply electricity to the control unit 6, and a thermoelectric generator 30 configured to produce electricity from the temperatures of the fluid and the exterior of the pipe 2, the power supply unit 10 being coupled to the thermoelectric generator 30. The thermoelectric generator 30 is configured to produce electricity using the Seebeck effect, which is a thermoelectric effect, by which a potential difference appears at the junction of two materials subjected to a temperature difference.

[0021] The power supply unit 10 comprises two separate and independent paths: a first power supply path 11 comprising at least one battery 12 and a second power supply path 21 connected to the thermoelectric generator 30. A battery (or "primary cell" in English) is understood to mean an electrical energy storage element which cannot be recharged, or whose configuration in the power supply unit 10 makes charging within this power supply unit 10 impossible. Typically, the first power supply path 11 comprises only the battery 12. The battery 12 preferably has a maximum energy reserve of less than 100 Wh, such as for example 30.6 Wh (8.5 Ah on 3.6 V) or 68.4 Wh (19 Ah on 3.6 V).

[0022] The power supply 10 comprises a first switch S1 configured to selectively couple the first power supply path 11 or the second power supply path 21 to the control block 6, thereby selecting whether the control block 6 is electrically powered by the first power supply path 11 or the second power supply path 21.

[0023] The second power supply path 21 further comprises a capacitor C1 and a second switch S2 configured to selectively couple or decouple the capacitor C1 and the thermoelectric generator 30. The capacitor C1 preferably has a maximum energy reserve Emax greater than or equal to 0.5 Wh, and more preferably greater than or equal to 0.8 Wh. For example, the capacitor C1 can deliver an electrical charge of 0.222 Ah at 3.6 V. The capacitor C1 is preferably a supercapacitor. Typically, the capacitor C1 can be a hybrid layer supercapacitor, or HLC for the English “Hybrid Layer Capacitor”, but can also be any type of supercapacitor making it possible to offer a maximum energy reserve Emax greater than or equal to 0.5 Wh. Preferably, the maximum energy Emax of the capacitor C1 is at least 20 times lower than the maximum energy of the battery 12.

[0024] The second switch S2 is arranged between the capacitor C1 and the thermoelectric generator 30. The second switch S2 is controlled by the control block 6 for its opening and closing. The second switch S2 is preferably a relay, for example an electromechanical relay.

[0025] The second power supply path 21 may comprise, in series between the thermoelectric generator 30 and the second switch S2, different current shaping elements, and for example a rectifier 22 in series with a voltage regulator 24. In the example illustrated, a first terminal of the capacitor C1 is connected between the first switch S1 and the second switch S2, and a second terminal of the capacitor C1 is connected to a reference potential (example: ground).

[0026] The control block 6 is configured to determine a temperature difference ΔT between the outside of the pipe 2, the temperature of which is denoted T amb and the fluid, the temperature of which is denoted T fluid (ΔT = T amb -T fluid ). More precisely, the control block 6 determines the temperature difference ΔT from temperature measurements made by a first temperature sensor T1 configured to measure the temperature T amb of the outside of the pipe 2, typically the ambient air, and by a second temperature sensor T2 configured to measure the temperature T fluid of the fluid, the first and second temperature sensors T1 and T2 being connected to the control block 6 to transmit their respective measurements. The temperature sensors T1, T2 are for example thermocouples. The second sensor T2 is for example embedded in the wall of the pipe 2, and / or may be in contact with the fluid.

[0027] The thermoelectric generator 30 comprises one or more thermoelectric modules 13, preferably identical and connected together in series. In other words, the thermoelectric modules 13 form a chain of thermoelectric modules extending between a first thermoelectric module 14 and a last thermoelectric module 15.

[0028] In the case where the thermoelectric generator 30 comprises only one thermoelectric module 13, this module 13 is both the first module 14 and the last module 15 of the thermoelectric chain.

[0029] Each thermoelectric module 13, 14, 15 comprises a first portion 16 configured to be arranged at the outside of the pipe 2 and a second portion 17 configured to be arranged at and near the fluid. More precisely, the first portion 16, respectively the second portion 17, is configured to be at the temperature T amb of the outside of the pipe 2, respectively at the temperature T fluid of the fluid. In one embodiment, the first portion 16 comprises a first end of the module 13, 14, 15, and / or the second portion 17 comprises a second end of the module 13, 14, 15. Preferably, the thermoelectric modules 13, 14, 15 are cylindrical, and for example tubular of constant diameter, so as to facilitate their installation.

[0030] The thermoelectric generator 30 further comprises a first external connector 18a in contact with the first portion 16 of the first thermoelectric module 14 and connecting said first portion 16 of the first thermoelectric module 14 to the power supply unit 10.

[0031] The thermoelectric generator 30 also comprises a second external connector 18b in contact with the second portion 17 of the last thermoelectric module 15 and connecting this second portion 17 of the last thermoelectric module 15 to the power supply unit 10. Typically, the first external connector 18a and the second external connector 18b are wires fixed, for example by soldering, to a thermoelectric module 14, 15.

[0032] More specifically, in one embodiment, the first and second external connectors 18a, 18b respectively connect the first portion 16 of the first module 14 and the second portion 17 of the last module 15 to the rectifier 22.

[0033] In one embodiment, the external connectors 18a, 18b are connected to the power supply 10 via intermediate electrical connections. Alternatively, the external connectors 18a, 18b extend to the power supply 10.

[0034] Furthermore, the second portions 17 of each thermoelectric module 13, 14 except the last module 15, are connected by an internal connector 18c to the first portion 16 of another thermoelectric module 13, 15. The internal connector 18c is thus in contact with the first and second connected portions 16, 17.

[0035] For example, the contact of the external connectors 18a, 18b and the internal connectors 18c to their respective thermoelectric modules 13, 14, 15 is made by soldering. The internal connectors 18c are for example metal wires.

[0036] In one embodiment, the external connectors 18a, 18b and internal connectors 18c are identical.

[0037] The thermoelectric modules 13, 14, 15 are composed of a first conductive thermoelectric material having a given first Seebeck coefficient SA. In addition, the external connectors 18a, 18b and internal connectors 18c are composed of a second conductive thermoelectric material having a given second Seebeck coefficient SB different from the first Seebeck coefficient SA.

[0038] In the case where the fluid meter is intended to be arranged in an environment in which the temperature T amb of the outside of the pipe is generally higher than the temperature of the fluid T fluid , (by generally is meant at least 50% of the time), that is to say for example in the case of a cold water meter arranged inside a building, the first and second thermoelectric materials are chosen so that the second Seebeck coefficient SB is higher than the first Seebeck coefficient SA , and preferably higher by at least 2 or 4 µV / K. Thus in such a case, the first Seebeck coefficient SA is preferably relatively low, for example negative, while the second Seebeck coefficient SB is preferably relatively high, for example positive.For example in such a case, the first thermoelectric material is aluminum, iron, or molybdenum oxide, and the second thermoelectric material is copper, nickel, strontium titanate or is a solid polyelectrolyte.

[0039] On the contrary, in the case where the fluid meter intended to be arranged in an environment in which the temperature T amb of the outside of the pipe is generally lower than the temperature of the fluid T fluid (by generally is meant at least 50% of the time), that is to say for example in the case of a hot water meter, the first and second thermoelectric materials are chosen so that the second Seebeck coefficient SB is lower than the first Seebeck coefficient SA , and preferably lower by at least 2 or 4 µV / K. Thus, for example in such a case, the first thermoelectric material forming the thermoelectric modules 13, 14, 15 is copper, nickel, strontium titanate or is a solid polyelectrolyte, and for example, the second thermoelectric material forming the external connectors 18a, 18b and internal connectors 18c is aluminum, iron, or a molybdenum oxide.

[0040] In any event, in all cases, the second Seebeck coefficient SB is different from the first Seebeck coefficient SA, and preferably different by at least 2 or 4 µV / K at least, so that a potential difference ΔV is generated within each module 13, 14, 15 between the first portion 16 and the second portion 17 due to the contact between said portions 16, 17 and the connectors 18a, 18b, 18c when there is a temperature difference ΔT between the temperature T amb of the outside of the pipe 2 and the temperature of the fluid T fluid (ΔT = T amb -T fluid). The potential difference between the two contact points between a thermoelectric module 13, 14, 15 and connectors 18a, 18b, 18c, i.e. between the first and second portions 16 and 17, is defined by the following relationship: ΔV = S B − S A × ΔT

[0041] Thus, in all the cases described above, the thermodynamic materials are chosen so that the potential difference between the two contact points between a thermoelectric module 13, 14, 15 and connectors 18a, 18b, 18c generally remains positive (at least 50% of the time, as long as the temperature difference ΔT between the temperature T amb of the outside of the pipe 2 and the temperature of the fluid T fluid , is of the same sign as the difference between the second Seebeck coefficient SB and the first Seebeck coefficient SA ).

[0042] Furthermore, the thermoelectric modules 13, 14, 15 being assembled in series, the potential differences ΔV add to each other, so that at the terminals of the rectifier 22, the external connectors 18a and 18b produce a potential difference equal to ΔV multiplied by the number of thermoelectric modules assembled in series in the thermoelectric generator 30. Thus, the interest is to assemble a large number of modules 13, 14, 15 in order to proportionally increase the production of electricity.

[0043] For example, the thermoelectric generator 30 comprises a number N equal to 14 or 27 of thermoelectric modules 13, 14, 15, as shown in examples illustrated in the figures 2 And 3 . However, the number N can take any other value depending on the constraints or needs of the user.

[0044] In order to house the thermoelectric modules 13, 14, 15 and more generally the thermoelectric generator 30, the pipe 2 comprises a protrusion 19 formed on an external surface (i.e. in contact with the exterior) of the pipe 2. More precisely, the protrusion 19 extends radially outwards (i.e. in a direction opposite to the position of the fluid) from the pipe 2 relative to a flow axis of the fluid in the pipe 2 represented by an arrow in the embodiment of which an example is illustrated in the Figure 1 .

[0045] The protrusion 19 comprises one or more cavities 20 forming housings configured to receive the thermoelectric modules 13, 14, 15. In particular, each cavity 20 is configured to receive a thermoelectric module 13, 14, 15. In one embodiment, the protrusion 19 comprises as many cavities 20 as the thermoelectric generator 30 has thermoelectric modules 13, 14, 15.

[0046] The cavities 20 can be made in the protrusion 19 so as to be aligned, as in the example illustrated in the Figure 2 , or staggered, as in the example illustrated on the Figure 3 , in order to be able to accommodate more modules 13, 14, 15 in a reduced space. These examples are not limiting.

[0047] Each cavity 20 is blind and extends in the protrusion 19 radially relative to the flow axis of the fluid. More precisely, each cavity 20 opens onto the outside of the pipe 2, and extends in the protrusion 19 to an interior point of the wall 3 of the pipe 2 sufficiently close to the fluid so that the bottom of the cavity 20 is substantially at the temperature of the fluid flowing in the pipe 2.

[0048] In one embodiment, each of the cavities 20 comprises a protective portion 20a and a receiving portion 20b superimposed radially, the receiving portion 20b constituting the portion of the cavity 20 that is deepest in the wall 3 of the pipe 2 comprising the protrusion 19 and therefore closest to the fluid. In other words, the protective portion 20a extends between the emerging end of the cavity 20 on the outside of the pipe 2 and the receiving portion 20b.

[0049] More precisely, the wall 3 of the pipe 2 has a first constant thickness E1 outside the protrusion 19. The protrusion 19 has a second thickness E2, such that the wall 3 has at the level of the protrusion 19 a thickness equal to the sum of the first and second thicknesses E1 and E2. The protective part 20b is more precisely arranged in the wall of the pipe 2 comprising the protrusion 19 at a distance E3 from the inside of the pipe 2 less than the first thickness E1. In other words, the wall 3 locally comprises a third thickness E3 at the level of each cavity 20, this third thickness being less than the first thickness E1.

[0050] For example, the first thickness E1 is between 2 and 5 millimeters, and is typically 3 millimeters, the second thickness E2 is between 8 and 12 millimeters, and is typically 10 millimeters, and the distance E3, or third thickness E3, is between 0.3 and 1.7 millimeters, and is typically 1 millimeter.

[0051] In one embodiment, the protective portion 20a has a diameter D1 larger than the diameter D2 of the receiving portion 20b. More specifically, the receiving portion 20b of each cavity 20 is configured to enclose the second portion 17 of the module 13, 14, 15 inserted into said cavity 20, so as to maintain and immobilize the module 13, 14, 15 in said cavity 20. Thus, the diameter D2 of the receiving portion 20b is substantially close, for example half a millimeter greater, to the diameter of the second portion 17 of the thermoelectric modules 13, 14, 15. For example, the diameter D2 is between 1 and 3 millimeters, and is typically 2 millimeters.

[0052] The diameter of the protective part 20a is, on the other hand, wider, and configured so that no contact takes place between the module 13, 14, 15 and the protective part 20a, so as to electrically and thermally insulate the module 13, 14, 15 apart from its second portion 17. For example, the diameter of the protective part 20a is between 3 and 6 millimeters, and is typically 4 millimeters.

[0053] The radial thickness E2 of the protrusion 19 is configured so that the first portion 16 of the modules 13, 14, 15 inserted in the plurality of cavities 20 is exposed to the outside of the pipe 2, that is to say outside of the protective part 20a. In this way, the first portion 16 is well maintained at temperature T amb of the outside of the pipe 2.

[0054] The second portion 17 of each of the thermoelectric modules 13, 14, 15 is thus maintained in contact with the receiving part 20b, located closest to the fluid flowing in the pipe 2, so that the second portion 17 is indeed at the fluid temperature T of the fluid. Optionally, an electrically insulating thermal gel is applied to the second portion 17, so that the heat conduction from the fluid to the second portion 17 is improved while avoiding electrical losses in contact with the pipe 2, which may comprise brass. Finally, the free space between the protective part 20a and the thermoelectric module 13, 14, 15 housed in said protective part 20a may be filled with air or a thermal insulator. The first switch S1 and the second switch S2 are controlled by the control block 6 for their state: open or closed for the second switch S2, selection of the power supply path for the first switch S1.When the second switch S2 is closed and the first switch S1 connects the control block 6 to the battery 12, which then powers the control block 6, the capacitor C1 is coupled to the thermoelectric generator 30 and recharges, storing electrical energy produced by the thermoelectric generator 30. When the second switch S2 is open and the first switch S1 connects the control block 6 to the capacitor C1 of the second power supply path 21, the control block 6 is powered by the capacitor C1, the battery 12 not being used.

[0055] The second switch S2 is configured to be controlled by the control block 6 as a function of the temperature difference ΔT determined by the control block 6 on the one hand when the capacitor C1 is in a charging state, and as a function of a charging state of the capacitor C1 determined by the control block 6 on the other hand when the capacitor C1 is in a discharging state.

[0056] The first switch S1 is configured to be controlled by the control block 6 as a function of a state of charge of the capacitor C1 determined by the control block 6. A state of charge or discharge of the capacitor C1 is determined by the control block 6 from an estimate of the current I representative of an intensity of the charge or discharge current of the capacitor C1, or estimate of the charge or discharge current I.

[0057] More particularly, on the one hand, the estimation of the load current I is carried out by the control block 6 and based on a correspondence between the temperature difference ΔT between the outside of the pipe 2 and the fluid determined by the control block 6 and a first correspondence table (determined experimentally, and stored for example in the memory of the control block 6) providing for each value of ΔT an estimation of the current I.

[0058] On the other hand, the estimation of the discharge current I is carried out by the control block 6 and based on a correspondence between functions implemented by the control block 6 and a second correspondence table (determined experimentally, and stored for example in the memory of the control block 6) providing for each function implemented an estimation of the current I.

[0059] The control block 6 is in fact configured to determine the charge level (SoC) of the capacitor C1 from this estimate of the charge or discharge current I. More precisely, the charge level is updated at each time step thanks to the estimate of the charge or discharge current I.

[0060] For example, when charging capacitor C1, the charge level (SoC) at the previous instant is incremented by a multiple of the intensity of the charging current I. Preferably, the charge level is expressed as a proportion of a maximum energy reserve Emax of capacitor C1. It follows that the expression of the energy, namely VI, is divided by Emax, with V the value of the voltage across the terminals of the rectifier 22 delivered by the thermoelectric generator 30 (V being equal to ΔV multiplied by the number N of modules 13, 14, 15 assembled in series in the thermoelectric generator 30) and I the intensity of the charging current estimated by the control block 6 using the temperature difference ΔT and the first correspondence table, and therefore that SoC(t+T)= SoC(t)+TVI / Emax.

[0061] Conversely, when the capacitor C1 is discharged, the charge level (SoC) at the previous instant is decremented by a multiple of the intensity of the discharge current I, hence SoC(t+T)= SoC(t)-TVI / Emax, , with V the value of the voltage across the terminals of the rectifier 22 delivered by the thermoelectric generator 30 (V being equal to ΔV multiplied by the number N of modules 13, 14, 15 assembled in series in the thermoelectric generator 30) and I the intensity of the discharge current estimated by the control block 6 using the functions implemented by the control block 6 and the second correspondence table.

[0062] Preferably, the time step T is less than 10 seconds. The time step T is preferably greater than 0.1 seconds. For reasons of simplicity, the time step here is 1 second, which simplifies the determination of the charge level: in charge: SoC(t+T)= SoC(t)+VI / Emax, in discharge: SoC(t+T)= SoC(t)-VI / Emax.

[0063] If the state of charge is sufficiently high, the first switch S1 connects the second power supply path 21 to enable the power supply of the control unit 6 by the capacitor C1 of the second power supply path 21. Otherwise, the first switch S1 connects the first power supply path 11 to enable the recharging of the capacitor C1 while it is the battery 12 of the first power supply path 11 which powers the control unit 6. The control unit 6 is configured to, at least when the thermoelectric generator 30 generates electricity: positioning the first switch S1 on the second power supply channel 21 when the charge level becomes greater than or equal to a high threshold, positioning the first switch S1 on the first power supply channel 11 when the charge level of the capacitor C1 becomes less than or equal to a low threshold.

[0064] Similarly, when the first switch S1 is connected to the battery 12, and therefore the capacitor C1 is in the charging phase, the control block 6 is configured to: opening the second switch S2 when the temperature difference ΔT is less in absolute value than a minimum temperature difference threshold, closing the second switch S2 when the temperature difference ΔT is greater than or equal in absolute value to a minimum temperature difference threshold and the temperature difference ΔT has the same sign as the difference defined by the second Seebeck coefficient SB minus the first Seebeck coefficient SA.

[0065] The same minimum temperature threshold can be used, but different thresholds can be used.

[0066] There Figure 4shows an example of an operating diagram of the fluid meter showing the variations of the states of the first switch S1 and the second switch S2, with different steps implemented by the control block 6. In a default state (S00), for example before the fluid meter is set up, the first switch S1 is on battery 12, i.e. connects the control block 6 to the first power supply channel 11. The second switch S2 is preferably closed. The charge of the capacitor C1 can be zero (in which case the charge level is initialized to 0) or very low (in which case the charge level is initialized according to the non-zero initial charge value). In a first step (S01), the second switch S2 is closed, connecting the capacitor C1 to the thermoelectric generator 30. The first switch S1 is on battery 12. The capacitor C1 can then charge with electrical energy.In a second step (S02), the temperature difference ΔT between the outside of the pipe 2 and the fluid is measured by the control block 6 receiving the measurements of T amb and T fluid made by the temperature sensors T1 and T2. The temperature difference ΔT is compared to a minimum temperature difference threshold, in order to determine whether electricity is produced by the thermoelectric generator 30 in sufficient quantity to charge the capacitor C1. Depending on the result of the comparison of the second step (S02), the second switch S2 is open or closed (step S03). Thus, if the temperature difference ΔT is lower in absolute value than the minimum threshold, then the second switch S2 is open.Conversely, if the temperature difference ΔT is greater than or equal in absolute value to a minimum threshold (the same or different) and the temperature difference ΔT has the same sign as the difference between the second Seebeck coefficient SB and the first Seebeck coefficient SA, then the second switch S2 is closed, allowing the capacitor C1 to charge. For example, the minimum temperature difference threshold is between 2°C and 5°C, and typically 3°C.

[0067] When the second switch S2 is closed, a fourth step (S04) is implemented, in which the control block 6 estimates the charging current I as a function of the temperature difference ΔT and the first look-up table, and updates the charging level as a function of the determined charging current I estimate. More precisely, as explained above, the state of charge is incremented by a multiple of the charging current I estimate. Then, a test (S05) is performed to check whether the charging level is greater than or equal to a high threshold, by means of a comparison between the current charging level and this high threshold. The high threshold is used to check that the capacitor C1 is sufficiently charged, and therefore corresponds to a charging level close to the maximum energy E max that the capacitor can store. Typically, the high threshold is at least 80% of the maximum energy E max , and preferably at least 90% of the maximum energy E max .

[0068] If this is not the case, the control block 6 returns to the fourth step (S04) to continue charging the capacitor C1. If the charge level is greater than or equal to the high threshold, then the control block 6 commands the opening of the second switch S2 and the passage of the first switch S1 on the capacitor C1, thus coupling the control block 6 and the second power supply channel 21 (step S06). The control block 6 is now powered by the capacitor C1 which is discharging, and no longer by the battery 12. The opening of the first switch S2 makes it possible to decouple the capacitor C1 and the thermoelectric generator 30, thus avoiding possible electrical disturbances. During the discharge of the capacitor C1, at each time step T, a step (S07) of estimating the discharge current I and an update of the charge level by the control block 6 is carried out.More particularly, this estimation of the discharge current I is determined by the control block 6 differently than in step S03. Indeed, the estimation of the current I is determined from the active functions in the time step of step S05 and from the second correspondence table. More precisely, active functions are understood to mean the functions implemented by the control block 6 (such as the activation of the control block 6, the sending of a frame, the carrying out of a measurement burst, etc.). Furthermore, as explained above, the charge level is decremented by a multiple of the estimation of the discharge current I. Then, a test (S08) is carried out to check whether the charge level is less than or equal to a low threshold, by means of a comparison between the current charge level and this low threshold. The low threshold is used to check that the capacitor C1 has been sufficiently discharged, and therefore corresponds to a charge level close to the minimum.Typically, the low threshold is less than 10% of the maximum energy E max , and is for example less than or equal to 5% of E max .

[0069] If the charge level is greater than the low threshold, the discharge of the capacitor C1 continues and a new step (S07) of estimating the discharge current I and updating the charge level is carried out. Conversely, if the charge level is less than or equal to the low threshold, this means that the capacitor C1 has been sufficiently discharged, and that it must now be recharged. Consequently, the control block 6 then returns to step (S01), closes the second switch S2 and switches the first switch S1 to the first power supply channel 11, on the battery 12.

[0070] Finally, the control block 6 is configured to implement a computer program product comprising instructions which, when executed by the control block 6, lead to the implementation of the method described above.

[0071] The computer program product takes the form of a non-volatile medium, typically a computer-readable memory storing instructions which, when executed by a computer, cause the computer to implement the method described above.

[0072] As can be seen in this method, the control unit 6 is configured to maximize the use of the capacitor C1 and save the battery 12. The battery 12 is then only used to allow the capacitor C1 to be recharged. Thanks to the permanence of the power supply, the fluid meter is able to communicate information relating to the metrological data, for example by displaying them, even in the absence of fluid circulation. It should be noted that the charging time of the capacitor C1 is inversely proportional to the temperature difference ΔT between the outside and the fluid, so that the invention is particularly suitable for a hot water meter. It is easy to ensure, given the low energy requirements of the control unit 6, that the recharge time of the capacitor C1 is much shorter than the discharge time of the capacitor C1. The capacitor C1 can provide a significant portion of the power supply to the control unit 6.The less stressed 12 battery can be chosen with a lower energy storage capacity, therefore with reduced size and lower cost, while preserving or increasing its lifespan.

[0073] The thermoelectric generator 30 used in the present invention has the advantage of not being intrusive in the fluid, and thus of not risking disturbing the accuracy of the metrology. Also, such a thermoelectric generator 30 eliminates any risk of breakage or fouling compared to another intrusive electric generator.

[0074] Also, the solution presented in this presentation is economical, the additional cost linked to the manufacture of the protrusion and the drilling of the cavities being very limited.

[0075] The invention is not limited to the embodiment described and shown in the attached figures. Modifications remain possible, in particular from the point of view of the constitution of the various technical characteristics or by substitution of technical equivalents, without departing from the scope of protection of the invention.

Claims

1. A fluid meter configured to perform metrological measurements in a fluid circulation pipe and to communicate information relating to said metrological data, comprising: - a fluid pipe (2), - at least one metrological sensor (4) configured to perform metrological measurements in the fluid pipe (2), - a control block (6) configured to receive the metrological measurements and to communicate information relating to said metrological data, - a power supply block (10) configured to supply energy to the control block (6), the power supply block (10) comprising a first supply path (11) comprising at least one primary cell (12), and a second supply path (21), the power supply block (10) further comprising a first switch (S1) configured to selectively couple the first supply path (11) or the second supply path (21) to the control block (6), characterized in that the fluid meter comprises a thermoelectric generator (30) configured to produce electricity from a temperature difference (ΔT) between an exterior of the pipe (2) and the fluid in the pipe (2), the second supply path (21) being connected to the thermoelectric generator (30).

2. The fluid meter according to claim 1, wherein the thermoelectric generator (30) includes one or more thermoelectric modules (13, 14, 15) partially inserted into a wall (3) of the pipe (2).

3. The fluid meter according to claim 2, wherein a protrusion (19) is formed on the fluid circulation pipe (2), the protrusion (19) comprising at least one cavity (20), each cavity (20) being configured to receive a thermoelectric module (13, 14, 15).

4. The fluid meter according to claim 3, wherein the wall (3) of the pipe (2) has a first thickness (E1) out of the protrusion (19), each cavity (20) comprising a protection part (20a) and a receiving part (20b), the receiving part (20b) being of a diameter smaller than the protection part (20a) and being arranged in the wall (3) of the pipe (2) at a distance (E3) from the interior of the pipe (2) smaller than the first thickness (E1), each thermoelectric module (13, 14, 15) comprising a first portion (16) configured to be at the temperature of the exterior of the pipe (Tamb) and a second portion (17) configured to be at the temperature of the fluid (Tfluid), the second portion (17) being inserted into the receiving part (20b).

5. The fluid meter according to claim 4, wherein the thermoelectric generator (30) includes a first external connector (18a) in contact with the first portion (16) of a first thermoelectric module (14) disposed at the input of the thermoelectric generator (30) and connecting said first portion (16) to the power supply block (10), the thermoelectric generator (30) further comprising a second external connector (18b) in contact with the second portion (17) of a last thermoelectric module (15) disposed at the output of the thermoelectric generator (30) and connecting said second portion (17) to the power supply block (10).

6. The fluid meter according to claim 4 or 5, wherein a second portion (17) of a thermoelectric module (13, 14) is connected by an internal connector (18c) to the first portion (16) of another thermoelectric module (13, 15).

7. The fluid meter according to claim 5 or 6, wherein each thermoelectric module (13, 14, 15) is composed of a first thermoelectric material having a first Seebeck coefficient (SA), and a connector (18a, 18b, 18c) in contact with the first portion (16) or the second portion (17) of the thermoelectric module is composed of a second thermoelectric material having a second Seebeck coefficient (SB) different from the first Seebeck coefficient (SA).

8. The fluid meter according to any one of claims 1 to 7, wherein the second supply path (21) comprises a capacitor (C1) and a second switch (S2) configured to selectively couple the capacitor (C1) and the thermoelectric generator (30) according to a level of charge (SoC) of the capacitor (C1),9. The fluid meter according to claim 8, wherein the level of charge (SoC) is determined by the control block (6) according to a first correspondence table and to the temperature difference (ΔT) when the capacitor (C1) is charging, and according to a second correspondence table and to functions implemented by the control block (6) when the capacitor (C1) is discharging.

10. The fluid meter according to claim 8 or 9, wherein the control block (6) is configured, at least when the thermoelectric generator (30) generates electricity: - to position the first switch (S1) on the second supply path (21) when the level of charge (SoC) becomes greater than a high threshold, - to position the first switch (S1) on the first supply path (11) when the level of charge (SoC) of the capacitor (C1) becomes smaller than a low threshold.

11. The fluid meter according to claim 10, wherein the high threshold is greater than or equal to 80% of a maximum level of charge (Emax), and the low threshold is less than or equal to 10% of a maximum level of charge (Emax).

12. The fluid meter according to any one of the preceding claims, wherein the control block (6) is configured to determine a temperature difference (ΔT) between the exterior of the pipe (2) and the fluid and: - to open the second switch (S2) when the temperature difference (ΔT) is smaller than a minimum temperature difference threshold, - to close the second switch (S2) when the temperature difference (ΔT) is greater than or equal to a minimum temperature difference threshold.

13. The fluid meter according to claim 12, wherein the minimum temperature difference threshold is comprised between 2°C and 5°C.

14. A method for managing the supply of a fluid meter according to any one of claims 1 to 13, the fluid meter comprising a control block (6) and a power supply block (10) configured to supply energy to the control block (6), the power supply block (10) comprising a first supply path (11) comprising at least one primary cell (12), and a second supply path (21), the power supply block (10) further comprising a first switch (S1) configured to selectively couple the first supply path (11) or the second supply path (21) to the control block (6), the second supply path (21) being connected to a thermoelectric generator (30) configured to produce electricity from a temperature difference (ΔT) between an exterior of the pipe (2) and the fluid in the pipe (2), the second supply path (21) further comprising a capacitor (C1) and a second switch (S2) configured to selectively couple the capacitor (C1) and the thermoelectric generator (30) according to a level of charge of the capacitor (C1), the method being able to be implemented by the control block (6) and including the following steps: - Switching the first switch (S01) on the first supply path (11), - Determining (S02) a temperature difference (ΔT) between an exterior of the pipe (2) and the fluid and, when the determined temperature difference (ΔT) becomes greater than or equal to a minimum threshold, closing (S03) the second switch (S2), - Estimating (S04) a charge current (I) from the temperature difference (ΔT) and a first correspondence table providing an estimation of the associated charge current for each value of the temperature difference (ΔT), - Determining (S04) a level of charge (SoC) of the capacitor (C1) in charge from the estimated charge current (I) and, when the estimated level of charge (SoC) becomes greater than or equal to a predetermined high threshold, switching (S06) the first switch (S1) on the second supply path (21), - Estimating (S07) a discharge current (I) from functions implemented by the control block (6) and a second correspondence table providing for each function implemented by the control block (6) an estimation of the associated discharge current (I), - Determining (S07) a level of charge (SoC) of the capacitor (C1) in discharge according to the estimation of the discharge current (I) and, when the estimated level of charge (SoC) becomes smaller than or equal to a predetermined low charge threshold, repeating the previous steps.

15. A computer program product able to be implemented by a control block (6) of a fluid meter according to any one of claims 1 to 13, comprising instructions which, when the program is executed by the control block (6), cause the control block (6) to implement the method according to claim 14.

16. A computer-readable memory storing instructions executable by the computer for the execution of the steps of the method according to claim 14.