Monitoring solenoid valve

Abstract

A method for monitoring an electromagnetic valve (22), the monitoring method comprising periodically repeated monitoring phases and each phase comprising the steps of: driving an electric motor (24) of the electromagnetic valve to modify a current position of a movable member (26) thereof; evaluating, during the driving step, a monitoring value representative of an inrush current of the electric motor; comparing the monitoring value with at least one first predetermined threshold value, and if the monitoring value is greater than said first predetermined threshold value, implementing at least one corrective action to avoid a blockage of the electromagnetic valve.

Description

TECHNICAL FIELD

[0001] The present invention relates to the field of electromagnetic valves for controlling the flow rate of any type of fluid flowing in a pipe. Such electromagnetic valves can but are not necessarily integrated in a fluid meter. BACKGROUND

[0002] An ultrasonic fluid meter most commonly comprises a pipe in which a fluid flows, and an ultrasonic measurement device comprising an upstream transducer (on the network side) and a downstream transducer (on the subscriber installation side). Each transducer successively acts as emitter and receiver of ultrasonic signals. Thus, the upstream transducer emits an ultrasonic signal into the pipe, which is received by the downstream transducer after having travelled in the fluid along a predefined path (of a precisely known length). Next, this downstream transducer in turn emits an ultrasonic signal, which is received by the upstream transducer after having travelled in the fluid along the predefined path (in the other direction). The ultrasonic measurement device then evaluates the flow rate of the fluid based on the time of flight of the ultrasonic signals between the transducers. Estimating the fluid flow rate makes it possible to evaluate the quantity of fluid consumed and to bill it.

[0003] In some countries, the meter must be able to limit, regulate and shut off the flow rate of the fluid. As an example, in some countries and in the case of unpaid water bills, the water distributor must provide a minimum flow rate to "bad payers" end customers for a certain number of days before completely cutting off access to water.

[0004] This minimum flow rate can vary according to the country and the customer, and it is therefore necessary to have the possibility of "on demand" regulation of the flow rate: the flow rate must be regulated according to a flow rate setpoint.

[0005] To regulate the flow rate, a proposal has been made to integrate an electromagnetic valve (for example a ball electromagnetic valve) into the meter pipe. The angular position of the ball can be controlled remotely in order to regulate the flow rate.

[0006] However, there is a non-negligible risk of blocking the ball of this electromagnetic valve, and in particular:

[0007] In the presence of impurities in the fluid, for example limestone or sand in water, or dust in air or gas;

[0008] When the ball remains in a stationary position for a long time, causing impurities to accumulate in the contact area between the ball and the seat.

[0009] This phenomenon also depends on the materials used to manufacture the ball and the seat. The seat is most commonly made of Teflon, and the friction of the ball on Teflon depends on the material used to manufacture the ball (stainless steel, brass, etc.).

[0010] To solve this problem of clogging of the ball, it has been proposed to integrate a piezoelectric power transducer into the pipe in close proximity to the electromagnetic valve. The transducer generates low-frequency waves resulting in the creation of low-pressure cavitation bubbles. The implosion of the cavitation bubbles makes it possible to eliminate the fouling.

[0011] However, this solution is complex and expensive to implement, since it not only requires the integration of said piezoelectric transducer into the meter in order to generate cavitation, but also a large energy source to excite said transducer. Furthermore, this solution is problematic, since the presence of cavitation bubbles around the ball often interferes with the measurement of the flow rate via ultrasound, in the case where the ball and the cavitation generator are located between two transducers dedicated to the measurement of the flow rate. SUMMARY

[0012] The object of the present invention is to detect a clogging or a future clogging of the mobile member of an electromagnetic valve in an efficient, simple, inexpensive manner and without interfering with the measurement of the flow rate, and to act against such a clogging or future clogging.

[0013] To achieve this object, a method for monitoring an electromagnetic valve is provided, the electromagnetic valve comprising:

[0014] a mobile member which extends in a pipe and whose current position can be adjusted in order to control the current flow rate of a fluid which can flow in the pipe;

[0015] an electric motor arranged to move the mobile member in order to impart to it its current position;

[0016] The monitoring method comprises a monitoring phase which is repeated periodically and each phase comprises the following steps:

[0017] driving the electric motor to modify the current position of the mobile member;

[0018] evaluating a monitoring value representative of the inrush current of the electric motor during the driving step;

[0019] comparing the monitoring value with at least one first predetermined threshold value, and if the monitoring value is greater than said first predetermined threshold value, implementing at least one corrective action to avoid clogging of the electromagnetic valve.

[0020] The movement of the mobile member of the electromagnetic valve by the electric motor requires a specific inrush current. This inrush current varies according to the level of fouling present at the interface between the mobile member and the stationary part of the electromagnetic valve. The monitoring method therefore evaluates the fouling according to the monitoring value and triggers the corrective action in advance before the level of fouling becomes problematic and there is a risk of clogging the electromagnetic valve. This monitoring method is very effective and its implementation is both simple and inexpensive, since it does not require dedicated components.

[0021] In the case where the solenoid valve is integrated in an instrument, it is possible to ensure that the flow rate measurement is not disturbed by the implementation of the monitoring method by implementing the monitoring phase only at zero flow rate.

[0022] There is also provided a monitoring method as described above, wherein the at least one corrective action comprises a first corrective action consisting in increasing the implementation frequency of the monitoring phases.

[0023] There is also provided a monitoring method as described above, wherein the at least one corrective action comprises a second corrective action consisting in increasing the implementation frequency of the monitoring phases.

[0024] There is also provided a monitoring method as described above, wherein each monitoring phase comprises the step of comparing the implementation frequency of the monitoring phases to a predetermined frequency threshold if the monitoring value is greater than said first predetermined threshold, and the step of implementing a first corrective action if said implementation frequency is lower than a predetermined frequency threshold; or

[0025] the step of implementing a second corrective action if said implementation frequency is higher than a predetermined frequency threshold.

[0026] There is also provided a monitoring method as described above, wherein each monitoring phase further comprises the step of comparing the monitoring value to a second predetermined threshold lower than the first predetermined threshold if the monitoring value is lower than said first predetermined threshold, and the step of decreasing the implementation frequency of the monitoring phases if the monitoring value is lower than said second predetermined threshold.

[0027] There is also provided a monitoring method as described above, further comprising the step of taking a measurement of the current flow rate of the fluid in the pipe, the monitoring steps being implemented only if the current flow rate is zero.

[0028] There is also provided a monitoring method as described above, wherein the monitoring value is equal to the ratio between the inrush current and the rated current of the electric motor during the driving step.

[0029] There is also provided a flow rate control system comprising: a solenoid valve; a current sensor arranged to measure the current supplied to the electric motor; and a processing circuit in which a monitoring method as described above is implemented.

[0030] There is also provided a flow rate control system as described above, further comprising a power supply assembly arranged to power the processing circuit of the solenoid valve and the electric motor, the current sensor being a shunt installed in parallel with the two outputs of the power supply assembly.

[0031] There is also provided a flow rate control system as described above, wherein the solenoid valve is a ball valve.

[0032] There is also provided a fluid meter comprising a flow rate measuring device and a flow rate control system as described above.

[0033] There is also provided a fluid meter as described above, the flow rate measuring device being an ultrasonic measuring device comprising two transducers arranged to emit and receive ultrasonic signals in the pipe, the ultrasonic measuring device being arranged to evaluate a current flow rate of the fluid from a time of flight of the ultrasonic signals between the transducers.

[0034] There is also provided a fluid meter as described above, the solenoid valve being positioned along the length of the pipe between the two transducers.

[0035] There is also provided a computer program comprising instructions for causing a processing circuitry of a system as described above to perform the steps of a monitoring method as described above.

[0036] There is also provided a computer readable storage medium storing the above computer program.

[0037] The application can be better understood from the following description of specific, non-limiting embodiments thereof. BRIEF DESCRIPTION OF DRAWINGS

[0038] Reference will be made to the drawings in which:

[0039] [ Figure 1 ] Figure 1 An instrument is shown comprising a pipe, a solenoid valve, an ultrasonic measuring device and a processing circuitry;

[0040] [ Figure 2 ] Figure 2 Various components of the instrument and processing circuitry of Figure 1 are shown schematically;

[0041] [ Figure 3 ] Figure 3 A graph is shown comprising a current curve to the motor of the solenoid valve;

[0042] [ Figure 4 ] Figure 4 A graph is shown comprising a current curve before fouling and a current curve after fouling;

[0043] [ Figure 5 ] Figure 5 A graph is shown comprising a current curve when the motor is powered at 3.6V and a current curve when the motor is powered at 5V;

[0044] [ Figure 6 ] Figure 6 Steps of a measuring method of the application are shown. DETAILED DESCRIPTION

[0045] Reference is made to Figure 1 and Figure 2 The application is embodied in an ultrasonic water meter 1. Here, the meter 1 is a water meter that is used to measure the water consumption of a subscriber's installation 2. Water is supplied to the subscriber's installation 2 by a water distribution network 3.

[0046] The meter 1 comprises a pipe 4 in which water supplied by the network 3 to the installation 2 flows. The water in the pipe 4 flows from upstream to downstream, as indicated by the direction of the arrow F. Here, the term "upstream" means on the side of the network 3, while the term "downstream" means on the side of the installation 2.

[0047] The meter 1 further comprises a processing circuit 5, which comprises a microcontroller 6, an application specific integrated circuit (ASIC) 7, and a power supply component 8.

[0048] The microcontroller 6 integrates a CPU 9 (for central processing unit), an SPI communication module 10 (for serial peripheral interface), an analog-to-digital converter 11 and a digital-to-analog converter 12. The processing circuit 5 further comprises one or more memories 14. At least one of these memories 14 forms a computer-readable storage support on which at least one computer program is stored, the at least one computer program comprising instructions for causing the microcontroller 6 to perform at least some steps of the monitoring method that will be described below.

[0049] The CPU 9 is connected to the SPI communication module 10, which itself is connected to the ASIC 7. The CPU 9 is also connected to the analog-to-digital converter 11 and the digital-to-analog converter 12. In this example, the power supply component 8 is an LDO (low dropout) voltage regulator. The power supply component 8 is connected to the microcontroller 6, and in particular to the analog-to-digital converter 11.

[0050] The meter 1 further comprises a battery 16, which has two terminals connected to the power supply component 8 of the processing circuit 5.

[0051] The meter 1 further comprises an ultrasonic measurement device 17, which is capable of measuring the flow rate of water supplied to the installation 2 by the network 3.

[0052] The ultrasonic measurement device 17 comprises an upstream transducer 18a and a downstream transducer 18b. The ultrasonic measurement device 17 further comprises a measurement module 19 connected to the upstream transducer 18a and the downstream transducer 18b. Here, the processing module 19 is implemented in the ASIC 7.

[0053] The upstream transducer 18a and the downstream transducer 18b are (but not necessarily) paired. Here, the upstream transducer 18a and the downstream transducer 18b are piezoelectric transducers.

[0054] Each transducer 18a, 18b successively acts as a transmitter and a receiver of ultrasonic signals.

[0055] The processing module 19 generates or controls the generation of an electrical excitation signal applied as input to the transmitter. The transmitter then generates an ultrasound signal. The receiver receives it after the ultrasound signal has travelled in the fluid along a predefined path 20, and the processing module 19 measures the time of flight.

[0056] The predefined path 20 is here a straight path (inclined with respect to the longitudinal axis of the pipe 4, as in the case of Figure 1 , or parallel to said axis, as in the case of Figure 2 ). The predefined path 10 has a very precisely known length d.

[0057] Thus, first, the upstream transducer 18a emits an ultrasound signal received by the downstream transducer 18b. The processing module 19 measures the time of flight TOF UP from upstream to downstream.

[0058] Next, the downstream transducer 18b emits an ultrasound measurement signal received by the upstream transducer 18a. The processing module 19 measures the time of flight TOF DN from downstream to upstream.

[0059] The processing module 19 then calculates, in particular on the basis of the times of flight TOF UP and TOF DN , the speed of sound in water, the water flow speed, and the flow rate of water.

[0060] The meter 1 also comprises an electromagnetic valve 22 which makes it possible to regulate, limit or shut off the flow rate of water.

[0061] The electromagnetic valve 22 is positioned along the length of the pipe 4 between the two transducers 18a, 18b.

[0062] The electromagnetic valve 22 comprises a gear motor 23 which itself comprises an electric motor 24 and a reducer 25. The electromagnetic valve 12 comprises a movable member which extends in the pipe 4 and for which the current position can be adjusted in order to control the current flow rate of water. Here, the electromagnetic valve 22 is a ball valve and the movable member is therefore a ball 26; the current position of the ball 26 is an angular position. The gear motor 23 is used to control the electromagnetic valve 22.

[0063] The electromagnetic valve 22 also comprises a seat 27 for the ball 26. The seat 27 forms a sealing gasket between the ball 26 and the pipe 4.

[0064] The meter 1 also comprises a position sensor 28 (shown schematically in Figure 2 ) configured to measure the current angular position of the ball 26.

[0065] The instrument 1 also comprises communication means that can be used to implement any type of communication, for example communication via a 2G, 3G, 4G, Cat-M or NB-IOT cellular network, communication according to the LoRa protocol, radio communication according to the Wize standard operating at a frequency of 169 MHz, etc.

[0066] The monitoring method according to the application implemented by the microcontroller 6 of the processing circuit 5 comprises a monitoring phase that is repeated periodically.

[0067] During each monitoring phase, the microcontroller 6 first controls the electric motor 24 to modify the current angular position of the ball 26. The movement of the ball 26 makes it possible to limit the deposition of impurities and to clean the interface between the movable part and the stationary part of the solenoid valve 22, that is to say the interface between the ball 26 and the seat 27. The change in the current position of the ball 26 is for example a quarter-turn rotation.

[0068] Thereafter, the microcontroller 6 attempts to detect fouling. To this end, the microcontroller 6 evaluates a monitoring value of the inrush current of the electric motor 24 during the driving step just mentioned, that is to say when the electric motor 24 changes the current position of the ball 26. In this example, the monitoring value is equal to the ratio between the inrush current and the nominal current of the electric motor 24 during the driving step.

[0069] The movement of the ball 26 of the solenoid valve 22 indeed requires a certain inrush current (also called starting current or on current) to be supplied to the electric motor 24, which is generally 10 to 20 times greater than the nominal current.

[0070] Figure 3 The curve CI in the graph in FIG. 1 illustrates an example of the current supplied to the electric motor of a solenoid valve integrated in a domestic water meter. A distinction is made between the inrush current la and the nominal current In.

[0071] The term "inrush current" is used here to refer to the maximum value of the current at the peak present in the time interval Dl. The term "nominal current" is used to refer to the average value of the current, for example over the time interval D2.

[0072] As an example, the inrush current la is of the order of 330 mA. As an example, the duration of this peak is in the range from 20 ms to 30 ms. As an example, the nominal current In is stable and of the order of 20 mA.

[0073] However, the fouling will increase the friction force between the ball 26 and its mechanical support (the seat 27), such that the movement of the ball 26 requires a higher inrush current.

[0074] Figure 4The curve C2 shows the inrush current la1 of the solenoid valve just installed, and the curve C3 shows the inrush current la2 after 1 month of use of the solenoid valve in water filled with limestone.

[0075] It should be observed that the inrush current has increased from 330 mA to 420 mA. Once the fouling has been removed, the current rapidly converges to its nominal value (about 20 mA).

[0076] The ratio between the inrush current and the nominal current is therefore a good indicator of the level of fouling. It is therefore possible to measure it and monitor its evolution with respect to a reference value.

[0077] To evaluate the monitoring value, i.e. here the ratio between the inrush current and the nominal current, the processing circuit 5 uses the measurements produced by the current sensor.

[0078] The current sensor is here a shunt 29, i.e. a precision resistor of low value (a few milliohms or fractions of milliohms). In this example, the shunt 29 is connected in parallel with the two outputs 30 of the power supply assembly 8, i.e. the shunt 29 comprises one terminal connected to one of the outputs 30 and the other terminal connected to the other of the outputs 30. These two outputs 30 are themselves connected to two inputs 31 of an analog-to-digital converter 11 of the microcontroller 6. The analog-to-digital converter 11 makes it possible to convert the analog signal produced by the power supply assembly 8 into a digital value processed by the CPU 9.

[0079] The shunt 29 produces a voltage proportional to the current flowing through it.

[0080] The equation describing this relationship is as follows:

[0081] I = V / R,

[0082] where I represents the current in amperes, V represents the potential difference between the terminals of the shunt 29 in volts, and R is the resistance value of the shunt 29 in ohms.

[0083] Here, the battery 16 powers the processing circuit 5 and the ultrasonic measurement device 17 via the power supply assembly 8. The digital-to-analog converter 12 makes it possible to convert the drive setpoint of the ball 26 produced by the algorithm implemented by the CPU 9 into an analog signal for controlling the solenoid valve 22. The battery 16 thus also powers the solenoid valve 22 (i.e. the electric motor 24) via the power supply assembly 8.

[0084] The current measurement produced by the shunt 29 thus makes it possible to evaluate the current supplied to the electric motor 24 by subtracting the current consumed by the processing circuit 5 and the ultrasonic measurement device 17, and thus to evaluate the inrush current and the nominal current.

[0085] If the monitoring value becomes too large, the microcontroller 6 implements at least one corrective action to avoid (future) obstruction of the electromagnetic valve 22.

[0086] The first corrective action consists in increasing the implementation frequency of these monitoring phases (i.e. reducing the duration between two successive monitoring phases). By increasing the activation frequency of the electromagnetic valve 22, it becomes possible to more efficiently eliminate the incrustation.

[0087] The second corrective action consists in increasing the supply voltage of the motor 24 of the electromagnetic valve 22.

[0088] Figure 5 The effect of the supply voltage of the motor 24 on the inrush current and on the rated current of the electromagnetic valve is illustrated: the curve C4 corresponds to a voltage of 3.6 V and the curve C5 corresponds to a voltage of 5 V. The increase of the supply voltage leads to a greater power which will have the result of increasing the rotation speed of the ball 26 and the torque of the motor 24, which will help to remove the incrustation layer.

[0089] The third corrective action consists in generating an alert message and transmitting it to the information system (IS) of the distributor using the communication means described above. The alert can also be transmitted to the subscribers.

[0090] Reference Figure 6 The specific embodiments of the monitoring method of the application are described below.

[0091] These monitoring phases are implemented only when the current flow rate of water is zero. This makes it possible to avoid perturbing the measurement of the flow rate and thus the billing of the customer, but also to avoid penalizing the customer in the case where the ball 26 is driven to a position which reduces the current flow rate for the purpose of the monitoring method.

[0092] The microcontroller 6 acquires the flow rate measurement produced by the ultrasonic measurement device 17 (step El), then compares the current flow rate to the zero flow rate (step E2).

[0093] If the current flow rate is not zero, the method returns to step El. Otherwise, the algorithm moves to step E3.

[0094] A monitoring phase is then implemented. As an example, the initial implementation frequency of the monitoring phase is equal to three times a week, i.e. the monitoring phase is initially triggered three times a week.

[0095] In step E3, the microcontroller 6 drives the motor 24 to modify the current position of the ball 26.

[0096] The microcontroller 6 acquires the current measurement produced by the shunt 29 and evaluates the inrush current Ia (step E4), the rated current In (step E5) and the monitoring value Ia / In.

[0097] The microcontroller 6 then compares the monitoring value Ia / In with a first predetermined threshold S1 (step E6). As an example, the first predetermined threshold S1 is equal to 15.

[0098] If the monitoring value is greater than said first predetermined threshold (here greater than or equal to), the microcontroller 6 compares the implementation frequency Fm of the monitoring phases with a predetermined frequency threshold Sf (step E7). As an example, the predetermined frequency threshold Sf is equal to seven times per week.

[0099] If said implementation frequency Fm is lower than this predetermined frequency threshold (here strictly lower), the microcontroller 6 implements a third corrective action which consists in generating and transmitting an alert message (step E8), then this first corrective action which consists in increasing the implementation frequency of the monitoring phases (step E9). The frequency Fm is increased by one implementation per week. The method then proceeds to step E3.

[0100] In step E7, if the implementation frequency Fm of the monitoring phases is greater than the predetermined frequency threshold Sf (here greater than or equal to), the microcontroller 6 performs a second corrective action which consists in increasing the supply voltage of the electric motor 24 (step E10). The method then proceeds to step E3.

[0101] In step E6, if the monitoring value Ia / In is less than the first predetermined threshold S1 (here strictly less than), the microcontroller 6 compares the monitoring value with a second predetermined threshold S2 which is less than the first predetermined threshold S1 (step E11). As an example, the first predetermined threshold S2 is equal to 10.

[0102] If the monitoring value is greater than the second predetermined threshold (here greater than or equal to), the monitoring method proceeds to step E3. On the other hand, if this monitoring value is lower than this second predetermined threshold (here strictly lower), the microcontroller 6 decreases the implementation frequency Fm of the monitoring phases. Since the fouling is very low, it is possible to decrease the frequency of the monitoring phases (which makes it possible to decrease the power consumption).

[0103] The frequency Fm is decreased by one implementation per week (step E12). The method then proceeds to step E3.

[0104] Naturally, the application is not limited to the embodiments described, but covers any variants falling within the scope of the application as defined by the claims.

[0105] It is clear that the application is applicable regardless of the positioning and configuration of the upstream transducer and of the downstream transducer. The ultrasonic signal can be emitted at any angle of orientation with respect to the longitudinal axis of the pipe.

[0106] The predefined path between the transducers does not necessarily need to be a straight path. The predefined path can comprise a reflector, for example a mirror oriented at 45°.

[0107] The flow rate measurement device does not have to be an ultrasonic measurement device; for example, an electromagnetic measurement device can be used.

[0108] The valve does not necessarily have to be a ball valve. Any type of valve can be used to regulate the flow rate, for example a slide valve, a butterfly valve, etc. The position of the movable member that can regulate the flow rate does not necessarily have to be an angular position, but can be an axial position.

[0109] The architecture of the meter can be different from that described in this case. The communication module between the microcontroller and the ASIC does not have to be an SPI module. For example, the processing circuit can not comprise an ASIC and a microcontroller, but a single processing component (ASIC, microcontroller, processor, field programmable gate array (FPGA), etc.). The monitoring method does not have to be implemented in the microcontroller, or even in a single processing component. Some steps of the monitoring process can be performed remotely (for example, on a cloud server or in the cloud).

[0110] The current sensor does not have to be a shunt, and can be positioned differently, for example by being connected directly to the input of the motor.

[0111] Obviously, the present application is not only applicable to water meters, but to any meter of any fluid: gas, oil, oil, pharmaceuticals, etc.

[0112] The present application does not necessarily have to be implemented in a meter, but is applied to any flow rate control system arranged to control the flow rate of a fluid flowing in a pipe, and comprising an electromagnetic valve, a current sensor arranged to measure the current supplied to the motor, and a processing circuit in which a monitoring method is implemented.

[0113] The monitored value can be different from that described in this case. As an example, the monitored value can be the inrush current itself.

[0114] Naturally, Figure 6 The monitoring method described in this case is not limiting. For example, the three correction actions (and even other correction actions) can be implemented as soon as the monitored value becomes greater than a predetermined threshold.

Claims

1. A method for monitoring an electromagnetic valve (22), said electromagnetic valve comprising: a movable member (26) extending in a pipe (4) and whose current position is adjustable for controlling a current flow rate of a fluid that can flow in said pipe; an electric motor (24) arranged to move said movable member so as to impart to it its current position; said method comprising periodically repeated monitoring phases and each phase comprising the steps of: driving said electric motor to modify the current position of said movable member; evaluating, during the driving step, a monitoring value representative of an inrush current (la) of said electric motor; comparing said monitoring value with at least one first predetermined threshold (SI) and, if said monitoring value is greater than said first predetermined threshold, implementing at least one corrective action to avoid a blockage of said electromagnetic valve (22), characterized in that said at least one corrective action comprises a corrective action consisting in increasing the supply voltage of said electric motor (24) of said electromagnetic valve (22).

2. The method of claim 1, wherein, said at least one corrective action further comprising a corrective action consisting in increasing the implementation frequency of said monitoring phase.

3. The method of claim 2, wherein, each monitoring phase comprising the steps of comparing, if said monitoring value is greater than said first predetermined threshold, the implementation frequency of said monitoring phase with a predetermined frequency threshold (Sf) and the steps of: if said implementation frequency is lower than said predetermined frequency threshold, implementing a corrective action consisting in increasing said implementation frequency of said monitoring phase, or if said implementation frequency is higher than said predetermined frequency threshold, implementing a corrective action consisting in increasing the supply voltage of said electric motor (24) of said electromagnetic valve (22).

4. The method of any one of claims 1-3, wherein, each monitoring phase further comprising the steps of comparing, if said monitoring value is lower than said first predetermined threshold, said monitoring value with a second predetermined threshold lower than said first predetermined threshold and, if said monitoring value is lower than said second predetermined threshold, decreasing said implementation frequency of said monitoring phase.

5. The method of any one of claims 1-3, wherein, further comprising the steps of: acquiring a measured value of the current flow rate of said fluid in said pipe (4), said monitoring step being implemented only if said current flow rate is zero.

6. The method of any one of claims 1-3, wherein, said monitoring value being equal to the ratio between said inrush current and the rated current of said electric motor (24) during said driving step.

7. A flow rate control system, comprising: an electromagnetic valve (22); a current sensor (29) arranged to measure the current supplied to an electric motor (24); and a processing circuit (5) in which the method as claimed in any one of claims 1-6 is implemented.

8. The flow rate control system of claim 7, wherein, further comprising a power supply assembly (8) arranged to supply power to said processing circuit (5) and to said electric motor (24) of said electromagnetic valve, said current sensor being a shunt installed in parallel with two outputs of said power supply assembly.

9. The flow rate control system of claim 7 or 8, wherein, said electromagnetic valve is a ball valve.

10. A fluid table comprising a flow rate measurement device (17) and a flow rate control system as claimed in any one of claims 7 to 9.

11. The fluid table of claim 10, wherein, The flow rate measuring device (17) is an ultrasonic measuring device comprising two transducers (18a, 18b) arranged to emit and receive ultrasonic signals in the pipe, the ultrasonic measuring device being arranged to evaluate a current flow rate of the fluid from a time of flight of the ultrasonic signals between the transducers.

12. Fluid table according to claim 10 or 11, characterized in that The solenoid valve (22) is positioned along a length of the pipe between the two transducers.

13. A computer program product comprising instructions for causing the processing circuitry of the flow rate control system of any one of claims 7 to 9 to perform the steps of the method of any one of claims 1 to 6.

14. A storage medium, readable by a computer, on which are stored instructions for causing the processing circuitry of the flow rate control system of any one of claims 7 to 9 to perform the steps of the method of any one of claims 1 to 6.

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