WO2019219622A1

WO2019219622A1 - Piezoelectric flow meter

Info

Publication number: WO2019219622A1
Application number: PCT/EP2019/062231
Authority: WO
Inventors: Jean-Paul Guillaume
Original assignee: Jp Guillaume Ingénieur Conseil
Priority date: 2018-05-14
Filing date: 2019-05-13
Publication date: 2019-11-21
Also published as: FR3081049A1

Abstract

Disclosed is a piezoelectric flow meter comprising a substantially cylindrical duct (4) inside which a fluid is able to circulate, a piezoelectric sensor (6) placed around the duct (4), and an adapter module (8) connected to the piezoelectric sensor (6). In said piezoelectric flow meter, the piezoelectric sensor (6) is arranged to deform when fluid travels through the duct (4), such that the electrical signal (110) output by the piezoelectric sensor (6) varies continuously with the flow rate of the fluid in the duct (4). The adapter module (8) is designed to amplify the electrical signal (110) produced by the piezoelectric sensor (6) in such a way that said electrical signal (112) can be used.

Description

PIEZOELECTRIC FLOWMETER

The invention relates to a piezoelectric effect flow meter. Complete mapping of current withdrawals from a water supply network (or hydraulic network) is a necessity for all operators of such networks. These operators are aware of user charges, by their meters. But they also need to have a quantified knowledge of the authorized and not counted withdrawals (for example the use of the mouths of washing (BL) by the services of the highways of the municipality), as well as the unauthorized and not counted withdrawals. (theft of water) and leaks in the network, in order to react as quickly and accurately as possible to apply countermeasures when it comes to theft or leakage, especially if it is a question of potable water. This is particularly important for networks in areas with high water stress, where each leak can result in dramatic water wastage and each flight a significant loss of income. Finally, these leaks can also lead to a poor assessment of the work done by the network operator, for example by lowering its performance indicators. The known measuring devices are unsatisfactory. Some give only binary information, for example an alarm trigger in the event of an undue opening of a fire / fire hydrant (PIBI). Others are imprecise and / or non-universal, for example a count of the number of operating turns of a PIBI valve (FR 2 889 871 A1), which must be calibrated and adapted to each PIBI to be able to go back up at the flow rate. Finally, it is known to use a Fourier transform on the signal produced by a piezoelectric band in order to detect leaks in a network (WO 1817/109425 A2) by measuring acoustic vibrations, but this type of device does not allow to measure fluid flow. The present invention improves the situation. For these purposes, the invention starts from a piezoelectric flowmeter, comprising in known manner a substantially cylindrical conduit, adapted to circulate a fluid in its interior, and a piezoelectric sensor, placed around the conduit, generating a piezoelectric effect a signal in response to a mechanical stress applied to it, and an adapter module connected to the piezoelectric sensor.

To perform a piezoelectric fluid flow measurement, the piezoelectric sensor is arranged to deform during the passage of the fluid in the conduit, so that the mechanical stress deforming the piezoelectric sensor varies continuously with the flow rate of the fluid in the conduit. . In addition, the adapter module is arranged to amplify the electrical signal produced by the piezoelectric sensor so that the electrical signal obtained can be used.

In other variants, the piezoelectric sensor can:

being a film or a wire, and in an implementation of this variant, the piezoelectric sensor can be wound along its length along the duct, on its periphery, along a winding line, so that the piezoelectric sensor substantially surrounds completely the conduit, without making a closed electric loop,

include polyvinylidene fluoride (PVDF), or

be attached to the duct by gluing.

In one application, the fluid may be water, in particular drinking water.

The adapter module may furthermore comprise an analog-to-digital converter, or ADC module, arranged to calculate a digital information rate from the electrical signal at the output of the amplification module.

This ADC module can also calculate fluid volume information and perform a timestamp. In a variant, the adapter module furthermore a temperature sensor communicating a temperature signal to the ADC module.

In one embodiment, the piezoelectric flowmeter is arranged to process fluid flow rates in the range 0-5000 m ³ / h, and / or the range 0-200 m ³ /, and / or the range 0-80 m ³ / h. Alternatively, the piezoelectric flow meter can process fluid flow rates (10) of at least 0.1m ³ / hr.

The invention further provides a hydraulic network provided with an automated flow measurement, comprising piezoelectric flowmeters arranged on the hydraulic network, and a general controller connected to the piezoelectric flowmeters. Automated flow measurement is performed by receiving the flow information transmitted by the piezoelectric flow meters, and by mapping flow and volumes taken from the network.

The invention finally provides a method for installing and calibrating a piezoelectric flowmeter, which comprises the following operations:

a) fixing a piezoelectric sensor around a duct,

b) install an adapter module near the piezoelectric sensor and connect them electrically, and

c) circulating at different known flow rates a fluid in the conduit to establish a behavioral model, and

d) integrate the behavior model into the adapter module.

Other characteristics and advantages of the invention will become apparent on reading the following detailed description, relating to examples given for illustrative and non-limiting purposes, as well as to the examination of the appended drawings, in which:

Figure 1 is a cross-sectional view of the proposed piezoelectric flowmeter;

Figure 2 is a longitudinal sectional view of the piezoelectric flowmeter according to the plane II-II of Figure 1; Figure 3 is another side view, from the outside, of the piezoelectric flowmeter, according to the plane III-III of Figure 1;

Figure 4 is a detailed view of the architecture of the adapter module 8 of Figures 1 to 3;

FIG. 5 is a diagrammatic view of a water network on which the invention can be arranged, and

Figure 6 illustrates an example of a sensor model graph.

The attached drawings contain, for the most part, elements of a certain character. They can therefore not only serve to better understand the present description, but also contribute to the definition of the invention, if any.

In FIGS. 1 to 3, a piezoelectric flowmeter 2 comprises a substantially cylindrical duct 4, a piezoelectric sensor 6, an amplifier-converter module 8 (or adapter module). The piezoelectric sensor 6 may be made of polyvinylidene fluoride (PVDF), at least in part.

The conduit 4 is adapted for a circulation of water 10 in its interior. The piezoelectric sensor is in the form of wire or film. It can be wound along its large dimension (or one of them) around the duct, on its periphery, along a winding line 12, so that the sensor substantially completely surrounds the duct 4, without making a closed loop . The duct 4 also has a longitudinal direction 14 and a radial direction 16. The piezoelectric sensor 6 can be fixed by gluing on the duct 4. The gluing advantageously makes it possible to fix the piezoelectric sensor 6 to the duct 4 in a non-intrusive manner, which is both capital for sanitary reasons, and economic for its installation. When water passes through the duct 4, hydrodynamic effects induce a pressure that will tend to expand the duct 4 radially. Thus, mechanical stresses are exerted: on the duct 4, in the radial direction 16, and

on the piezoelectric sensor 6, in its longitudinal direction, which follows the winding line 12.

The piezoelectric sensor 6 is wound in order to maximize its sensitivity, that is to say the ratio between the electric current that the piezoelectric sensor will generate and the mechanical stress applied to it by deformation of the duct 4.

The piezoelectric sensor 6 may be arranged so that its main direction, that is to say the direction having the greatest sensitivity to the piezoelectric effect, is parallel to its large size. This advantageously makes it possible to increase the measurement sensitivity.

The thickness of the piezoelectric sensor may normally be between about 0.1 micrometer and about 5 millimeters, for PVDF. This thickness is exaggerated in the drawings, so as to facilitate reading.

By way of example, the Applicant has conducted experiments with a piezoelectric sensor in the form of a wire, of thickness 2 to 3 millimeters. Another type of piezoelectric sensor used by the Applicant included PVDF with a nominal thickness of 9 to 110 micrometers. Another type of piezoelectric sensor used by the Applicant had a nominal thickness in the range 9-50 microns for a strip, and in the range 0.5-1mm for a sheet ("mono-oriented sheet").

Alternatively, the PVDF may be replaced by a copolymer. Its thickness can then be between a few micrometers and 1.2 millimeters.

As said above, the piezoelectric sensor 6 does not form a loop, that is to say that its two ends 18 and 20 do not touch. Thus, the piezoelectric sensor 6 does not form a short circuit. The adapter module 8 is electrically connected (22) to both ends of the piezoelectric sensor 6. The adapter module 8 may be arranged, at least in part, on the duct 4. The adapter module 8 may be arranged on the duct 4, and offset in the longitudinal direction 14 of the duct 4 relative to the piezoelectric sensor 6. The adapter module 8 can also be disposed between the two ends 18 and 20 of the piezoelectric sensor 6, in order to optimize the overall size of the system. In another variant, the adapter module 8 may be disposed near the conduit 4 but not on the conduit 4 to facilitate its installation. For example, in the case of a buried duct 4, it may be deposited in a duct hole accommodating the duct 4, and in the case of a duct 4 in the open air be placed near the duct 4, either on the ground (if the conduit 4 is also placed on the ground) or on a fixation (if the conduit 4 is kept at a distance from the ground).

The positions of the adapter module 8 described above are not limiting, and in absolute terms the adapter module 8 can be arranged anywhere provided that it remains near the conduit 4 and the piezoelectric sensor 6, at least partially .

The piezoelectric sensor 6 and the adapter module 8 may be confronted with potentially very humid environments. Also the piezoelectric flowmeter can be protected by a sealing structure 24 which includes the adapter module 8, the piezoelectric sensor 6, and the conduit portion 4 to which they are attached. This sealing structure 24 is not shown in the figures.

Alternatively, the piezoelectric sensor may be inherently resistant to moisture. In a variant, the piezoelectric sensor 6 can make several turns around the duct 4, in order to increase the sensitivity of the piezoelectric sensor 6. In order to avoid a short circuit, the piezoelectric sensor 6 can then be covered at least partially with a electrical insulation, and then be wound on several turns. In the case of a piezoelectric sensor 6 in the form of a film, it is possible to provide a spiral winding, and the electrical insulator can then be arranged on one of the faces of the film. In the case of a piezoelectric sensor 6 in the form of a wire, it is also possible to provide a helical winding having as its axis the longitudinal axis 14 of the conduit 4, and then the electrical insulator can be a sheath around the wire.

FIG. 4 represents a detailed view of the architecture of the adapter module 8.

The adapter module 8 may comprise an amplification module 100, a temperature sensor 102, an internal clock 104, an analog-to-digital conversion module (or ADC module) 106 and a transmission module 108.

The amplification module 100 is connected to the piezoelectric sensor 6, and retrieves the electrical signal 110, called the raw signal, generated by the piezoelectric sensor 6 in order to produce an amplified version 112. This amplification operation is intended to render the raw signal 110 that can be used, manipulated and transmitted by the following modules. Indeed, the gross current induced by a piezoelectric sensor in the context of the invention is of the order of a few millivolts to a few volts, typically of the order of 10 to 100mV within a range of flow rates of 0 -40 m ³ / h in the context of experiments conducted by the Applicant. For such voltages, it may be necessary to be able to make these currents more easily exploitable.

It is known that a piezoelectric sensor 6 is a component that returns an electrical signal 110 (i.e. a voltage-current torque) as a function of a mechanical stress applied thereto. This electrical signal 110 thus generated can also vary according to the temperature of the piezoelectric sensor, its arrangement and its geometry. The function that takes the aforementioned parameters (mechanical stress, geometry, temperature, material used for the piezoelectric sensor) and sends an electrical signal 110 (in voltage and / or in ). This model 114 is obtained prior to operation in a network of the piezoelectric flow meter 2, by a calibration operation, as will be seen below.

The amplified signal 112 thus obtained can now be exploited. In particular, the amplified signal 112 at the output of the amplification module 100 can then be sent to the ADC module 106, which will convert this amplified signal 112 into a digital rate information 116 using the behavioral model 114.

The adapter module 8 can be provided with an internal clock 104 which transmits a clock signal 118. This clock signal 118 can be transmitted to the ADC module 106, which can thus time-stamp the digital rate information 116.

The temperature sensor 102 is disposed against the duct 4, close to or on the piezoelectric sensor 6. The advantage of such a temperature sensor 102 is that it can integrate the temperature into the model 114. The temperature sensor transmits a signal The temperature signal 120 may be analog or digital.

The ADC module 106 may also calculate a fluid volume information (10).

The digital rate information 116 can then be sent to the transmission module 108. The transmission module 108 can then transmit (122) this flowmeter flow rate information 116 to one or more controllers external to the piezoelectric flow meter 2, as it is will see below. This flow meter transmission 122 can be wired or wireless ("wireless"). The transmission module 108 can also transmit other information such as the temperature measured by the temperature sensor 102.

The adapter module 8 can be self-powered, for example with a removable battery. It can also be connected to an electrical network. Remember that any signal that evolves over time is a unique sum of sinus and cosine functions, of frequency varying between 0 and infinity. This sum can be obtained by calculating the Fourier transform of the signal, and can be discrete (if the signal is periodic, it is called a Fourier series) or continuous (if the signal is not). The term of this sum which is of zero frequency is called continuous component of the signal.

In the context of the invention, the Applicant is thus interested in the overall deformation of the duct (expansion), and not in its small deformations (vibrations). Also, in a variant, the adapter module can retain the electrical signal from the piezoelectric sensor at least or only its DC component. This preservation can be achieved by the use of a filter, in particular a low-pass filter. This filter can be analog and / or digital.

FIG. 5 represents a schematic view of a water network 200 on which the invention can be arranged.

A water network 200 comprises one or more catchments 202 which supply one or more water tanks 204. These tanks 204 in turn feed one or more water outlets 206 arranged in a sub-network 208 downstream of a reservoir. 204. The network 200 further comprises one or more piezoelectric flowmeters 2 and at least one general controller 210, which can be implanted in a computer. Each channel of the network may be provided with a valve 212 (or more).

The piezoelectric flowmeters 2 are disposed downstream of the catchments 202, at regular intervals. The piezoelectric flowmeters 2 may be wired and / or wirelessly connected to the general controller 210 for flowmeter transmission 122. Thus, the general controller 210 can obtain a multitude of flow information at different locations of the network 200 and can map the network 200. This mapping can be: in real time, that is to say that at every moment, the controller has flow information at each point of the network 200 equipped with a piezoelectric flowmeter 2,

in deferred time, that is to say that the general controller can realize at any time a summary of average flows and total volumes taken from the network over a sliding time window, for example the last hour, the last day, the last week or month, or

periodic, that is to say that the general controller regularly reports the volumes of water taken since the last report, for example, on the last day or the last month.

This mapping can be used in particular to detect and locate in time and space any anomalies on the network 200, in particular a leak on the network 200 or a theft of water. Upon detection of an abnormality, the general controller 210 may send an alert message.

Optionally, the piezoelectric flowmeters 2 may be located near the outlets 206 or the valves 212 of the network. Alternatively, the piezoelectric flowmeters 2 may be disposed away from the outlets 206 and the valves 212.

In one implementation, the piezoelectric flowmeters 2 can be arranged on any individual pipe (that is to say a network pipe without bifurcation, between two branches) so as to be able to measure the distribution of the fluid flow at each branch. , throughout the network 200.

Fig. 6 shows an example of a sensor model graph 114.

The graph of the sensor model 114 results from experiments conducted by the Applicant. It has on the abscissa the measured flow and on the ordinate the measured mechanical stress (in Newton). The measured flow rate is commonly between 0 and 40 m ³ / h. We can go up to the beach 0-200 m ³ / h (on a GDPI), even to the beach 0- 5000 m ³ / h (for a device placed on a transport network, or "feeders"). For washing mouths (BL), it is possible to restrict between 0 and 5 m ³ / h.

The invention may, in a variant, not measure the low flow rates, and thus be limited to the measurement of flow rates of at least about 100 L / h (that is to say 0.1 m ³ / h). These are typical minimum flows in the case of a washing mouth. In a variant of the invention, the flow rates observed may be at least 0.5 m ³ / h.

The mechanical stress at rest corresponds to the stress along the large dimension of the piezoelectric sensor 6 at rest, when there is no flow of water 10 in the duct 4. It is non-zero because of the fact that the piezoelectric sensor 6 remains stretched, at rest. This mechanical stress at rest is about 10 to 15N in the case of experiments conducted by the Applicant.

The invention also relates to a method for installing and calibrating 300 of a piezoelectric flow meter 2. This installation and calibration method 300 can comprise the following operations:

a) fix a piezoelectric sensor 6 around a duct 4, possibly having previously disposed of an electrical insulator on the piezoelectric sensor 6, b) install the adapter module 8 near the piezoelectric sensor 6 and electrically connect them (22), and

c) circulating at different known flow rates (via an existing meter) water in the conduit 4 to establish a sensor model 114.

Thus, the output of the adapter module (8) represents the flow rate in the conduit.

This calibration process can be factored to save water during calibration. For this purpose, the steps a) and b) can be carried out several times at several locations of the network 200, and then step c) once to establish all the sensor models 114. In the context of branches in the part of the network 200 which is being equipped, it is possible to use the distribution (known) flow rates between different branches to establish the sensor models 114 belonging to different branches.

The detailed description above relates to examples given for illustrative and not limiting.

Thus, a piezoelectric sensor has been described. In vain, strain gauges are conceivable.

Claims

A piezoelectric flowmeter (2), comprising:

a duct (4), substantially cylindrical, adapted to circulate a fluid (10) in its interior,

a piezoelectric sensor (6) placed around the duct (4),

an adapter module (8) connected to the piezoelectric sensor (6),

characterized in that

the piezoelectric sensor (6) is arranged to deform during the passage of the fluid (10) in the conduit (4), so that the electrical signal (110) from the piezoelectric sensor (6) varies continuously with the flow rate of the fluid (10) in the conduit (4), and

the adapter module (8) is arranged to amplify the electrical signal (110) produced by the piezoelectric sensor (6) so that the obtained electrical signal (112) can be operated.

2. piezoelectric flow (2) according to claim 1, wherein the adapter module is arranged to keep the electrical signal from the piezoelectric sensor at least its DC component.

3. Piezoelectric flowmeter (2) according to one of the preceding claims, wherein the piezoelectric sensor (6) is a film or a wire.

4. Piezoelectric flowmeter (2) according to claim 3, wherein the piezoelectric sensor (6) is wound along its length along the duct (4), on its periphery, along a winding line (12), so that the piezoelectric sensor (6) substantially completely surrounds the conduit (4) without making a closed electrical loop.

5. Piezoelectric flowmeter (2) according to one of the preceding claims, wherein the piezoelectric sensor (6) comprises polyvinylidene fluoride (PVDF).

6. Piezoelectric flowmeter (2) according to one of the preceding claims, characterized in that the piezoelectric sensor (6) is fixed to the duct (4) by gluing.

7. Piezoelectric flowmeter (2) according to one of the preceding claims, wherein the fluid (10) is water, in particular drinking water.

The piezoelectric flowmeter (2) according to one of the preceding claims, wherein the adapter module (8) further comprises an ADC module (106) arranged to compute a digital rate information (116) from the electrical signal ( 112) at the output of the amplification module (100).

The piezoelectric flowmeter (2) according to one of the preceding claims, wherein the ADC module (106) also calculates a fluid volume information (10) and a time stamp.

The piezoelectric flowmeter (2) according to one of the preceding claims, further comprising a temperature sensor (102) communicating a temperature signal (120) to the ADC module (106).

11. Piezoelectric flowmeter (2) according to one of the preceding claims, characterized in that it is arranged to treat fluid flow rates (10) between 0 and 5000m ³ / h, preferably between 0 and 200m ³ / h and even more preferably between 0 and 80m ³ / h.

12. Piezoelectric flowmeter (2) according to one of the preceding claims, characterized in that it is arranged to treat fluid flow rates (10) of at least 0, lm ³ / h.

13. Hydraulic network (200), characterized in that it comprises:

piezoelectric flowmeters (2) according to one of claims 1 to 11, arranged on the hydraulic network (200),

a general controller (210) connected to the piezoelectric flowmeters (2), characterized in that the general controller is arranged for:

receiving the transmitted rate information (116) (122) from the piezoelectric flow meters (2), and

map the flows and volumes taken from the network (200).

14. A method for measuring flow on a conduit, characterized in that it comprises the following operations:

a) fixing a piezoelectric sensor (6) according to one of claims 1 to 12 around a conduit (4),

b) installing an adapter module (8) near the piezoelectric sensor (6) and electrically connecting them (22), and

c) circulating at different known flow rates a fluid (10) in the conduit (4) to establish a behavioral model (114), and d) integrating the behavioral model (114) into the adapter module (8), so that the output of the adapter module (8) represents the flow in the conduit.