SPARK-IGNITION ENGINE SYSTEM AND ASSOCIATED IMPLEMENTATION METHOD

Abstract

This ignition system (1) comprising an internal combustion engine (2), an electric water pump coupled to the engine (2) and driven by an electric motor, a computer configured to control the speed of the electric water pump to control the water flow by controlling the electric motor by a water flow setpoint, an air intake circuit (2) and an exhaust circuit (15) associated with the internal combustion engine (2), a fuel supply circuit of the internal combustion engine (2), the internal combustion engine (2) being equipped with at least one knock sensor (11), the air intake circuit (2) comprising an intake manifold (10) equipped with a temperature sensor (Tcol),the computer being configured to be able to apply a water pump control logic in which a preventive knock correction factor greater than or equal to one is applied to the water flow setpoint as a function of the cooling water temperature of the internal combustion engine (2) and the intake gas temperature (Tcol). Figure for the abstract: [Fig 1],

Description

Title of the invention: CONTROLLED IGNITION ENGINE SYSTEM AND ASSOCIATED IMPLEMENTATION METHOD Technical field

[0001] The present invention relates to vehicles equipped with spark-ignition internal combustion engines with an electric type cooling water pump.

[0002] This type of electric water pump is gradually replacing conventional mechanical water pumps in motor vehicles, in order to reduce the fuel consumption of engines and therefore carbon dioxide emissions.

[0003] On a conventional mechanical water pump, the pump wheel shaft is directly driven by the engine crankshaft via an accessory belt, so that the rotational speed of the pump, and therefore the pump flow rate, is only dependent on the engine speed.

[0004] In the case of an electric water pump, the shaft of the pump wheel is driven by an electric motor supplied with low voltage, typically twelve Volts or forty-eight Volts, depending on the type of battery available in the vehicle.

[0005] An engine control computer makes it possible to control the speed of the water pump and therefore the water flow rate, which is a parameter making it possible to reduce or eliminate the knocking phenomenon likely to appear on a spark-ignition engine.

[0006] The present invention aims to constitute a spark-ignition engine system which minimizes fuel consumption by taking into account the possible occurrence of knocking which degrades engine performance. It also relates to a method of implementing such a system. Previous techniques

[0007] Spark ignition engines are known, for example from document EP2140122B1 which discloses a variable compression ratio engine equipped with a knock sensor and an electric water pump. In the event of knocking, an engine computer increases the rotational speed of the pump in order to increase the flow rate of coolant which is supplied in an area close to the surface of the combustion chambers, and decreases the compression ratio of the engine.

[0008] This document therefore discloses the principle of increasing the flow rate of the water pump in a curative manner in response to knocking, but does not disclose any preventive treatment of the knocking phenomenon, nor the use of correction coefficients for the flow rate of the water pump. Statement of the invention

[0009] Known control logics intended to curatively increase the flow rate of the water pump in response to knocking are unsuitable for minimizing consumption and maximizing the performance of a spark-ignition engine system in all use cases, since it is necessary to take into account the possible occurrence of knocking which limits the performance of the internal combustion engine and degrades its consumption due to the fact that it is necessary to reduce the ignition advances to make this knocking disappear.

[0010] However, increasing the water flow rate beyond what is strictly necessary to avoid overheating increases the heat exchange coefficient and makes it possible to significantly reduce knocking thanks to more efficient cooling of the combustion chamber walls.

[0011] In view of the above, the invention aims to propose an electric water pump control logic which makes it possible to overcome at least some of the aforementioned drawbacks and to take into account this component of knocking, and of consumption and performance of the engine.

[0012] In view of the above, the subject of the invention is a spark-ignition engine system comprising an internal combustion engine, an electric water pump configured to be coupled to the internal combustion engine, an electric motor configured to be able to drive the electric water pump, a computer configured to be able to control the speed of the electric water pump to control the water flow rate of the electric water pump by controlling the electric motor by a water flow rate setpoint, an air intake circuit and an exhaust circuit associated with the internal combustion engine, a fuel supply circuit of the internal combustion engine, the internal combustion engine being equipped with at least one knock sensor in the internal combustion engine, the air intake circuit comprising an intake manifold equipped with a sensor for the temperature of the inlet gases,the computer being configured to be able to apply a water pump control logic in which a preventive knock correction factor greater than or equal to one is applied to the water flow setpoint as a function of the cooling water temperature of the internal combustion engine and the temperature of the inlet gases.

[0013] Preferably, the computer is further configured to be able to apply a logic for controlling the water pump taking into account the knocking measured by the knock sensor by applying a curative correction factor greater than or equal to one applied to the water flow rate setpoint as a function of a knocking level calculated by the computer from the knock sensor positioned on the engine. internal combustion.

[0014] For example, the water flow rate setpoint is limited to a threshold value less than or equal to the maximum water flow rate achievable by the electric water pump.

[0015] Advantageously, the air intake circuit further comprises from upstream to downstream in the direction of air circulation towards the internal combustion engine: an air filter, a fresh air temperature sensor, a compressor, a supercharged air cooler supplied by said first compressor, an air intake valve in the intake manifold of the internal combustion engine.

[0016] According to one embodiment, the exhaust circuit comprises from upstream to downstream in the direction of circulation of the burnt gases from the internal combustion engine: an exhaust manifold, a turbine, a assembly for depolluting the combustion gases from the internal combustion engine.

[0017] In one embodiment, the assembly for depolluting combustion gases from the internal combustion engine comprises a three-way catalyst and / or a particulate filter.

[0018] Advantageously, the system comprises a turbocharger integrating both the compressor and the turbine, and the internal combustion engine is a three-cylinder in-line engine of the type supercharged by said turbocharger.

[0019] The invention also relates to a method for implementing a system as defined above, comprising a first step during which the computer applies a mapping of the water flow rate of the electric water pump as a function of the current speed and torque of the internal combustion engine to calibrate the water flow rate to just the amount necessary to satisfy the cooling needs of said internal combustion engine, a second step carried out in parallel with the first step and during which a modulation coefficient to be applied to the water flow rate is calculated as a function of the cooling water temperature of the internal combustion engine, a third step during which the modulation coefficient calculated during the second step is multiplied with the water flow rate calculated during the first step to obtain a water flow rate setpoint,a fourth step in which the computer configured to be able to control the speed of the electric water pump applies the water flow setpoint to the electric motor, the fourth step being followed by a fifth step in which the electric water pump is activated at said water flow setpoint, the method further comprising a sixth step in which the preventive correction factor for knocking greater than or equal to one is determined to be applied to said water flow setpoint as a function of the cooling water temperature of the internal combustion engine and the temperature of the inlet gases, the sixth step being followed by a ninth step in which said preventive correction factor is multiplied with the water flow setpoint calculated during the , third stage, said sixth stage continuing with the fourth stage.

[0020] Preferably, the method further comprises a seventh step during which a curative factor is determined as a function of the knocking level calculated by the computer from the knocking sensor, the seventh step being followed by an eighth step during which the preventive correction factor is multiplied with the curative correction factor, said eighth step continuing with the ninth step, and the ninth step comprising the additional multiplication of this result with the water flow rate setpoint.

[0021] The invention also relates to a method for implementing a system as defined above, further comprising a tenth step after the ninth step, during which the water flow rate setpoint calculated during the ninth step is compared with the threshold value, then either the method is stopped if said threshold value is exceeded by said water flow rate setpoint, or the method is continued to the fourth step if said water flow rate setpoint is lower than said threshold value. Brief description of the drawings

[0022] The invention will be better understood from a detailed study of an embodiment taken as a non-limiting example and illustrated by the appended drawings, in which:

[0023] [Fig.l] represents the general architecture of the spark-ignition engine system in terms of air intake and exhaust circuit.

[0024] [Fig.2] represents the engine cooling water circuit.

[0025] [Fig.3] represents the steps of a logic for controlling the engine cooling pump, according to the prior art.

[0026] [Fig.4] represents a mapping of the water flow rate of the electric water pump as a function of the current speed and torque of the internal combustion engine to calibrate the water flow rate.

[0027] [Fig.5] represents a modulation table applied to a water flow rate setpoint.

[0028] [Fig.6] represents the steps of a cooling pump control logic engine development, according to a method of the invention.

[0029] [Fig.7] represents a map of preventive correction factor applied to a water flow rate setpoint, according to the invention.

[0030] [Fig.8] represents a table of curative correction factor applied to a water flow rate setpoint, according to the invention. Detailed description

[0031] [Fig.l] illustrates a part of the spark-ignition engine system 1 according to the invention, more particularly the general architecture of the air intake and exhaust circuit of the spark-ignition engine system.

[0032] The system 1 comprises an air intake 3 and a gas outlet 4, and a motor internal combustion engine 2, an electric water pump 20 configured to be coupled to the internal combustion engine 2, an electric motor 23 illustrated by [Fig.2] and configured to be able to drive the electric water pump 20.

[0033] The electric motor 23 is for example supplied with low voltage, typically twelve Volts or forty-eight Volts, depending on the type of battery available in the vehicle.

[0034] The system 1 further comprises a computer (not shown), of the engine control computer type, configured to be able to control the speed of the electric water pump 20 to control the water flow rate Qeau of the electric water pump 20 by controlling the electric motor 23 by a water flow rate setpoint Qeau_cons.

[0035] The system 1 further comprises an air intake circuit 3 and an exhaust circuit 15 associated with the internal combustion engine 2.

[0036] The system 1 further comprises a fuel supply circuit for the internal combustion engine 2 (not shown).

[0037] The internal combustion engine 2 is equipped with at least one knock sensor 11 on the internal combustion engine 2.

[0038] The knock sensor is for example positioned on the cylinder block of the internal combustion engine 2.

[0039] The air intake circuit 3 comprises an intake manifold 10 equipped with a sensor for the temperature of the inlet gases Tcol.

[0040] The computer is configured to be able to apply a logic for controlling the water pump 20 in which a preventive knock correction factor greater than or equal to one is applied to the water flow rate setpoint Qeau_cons as a function of the cooling water temperature of the internal combustion engine 2 Tco and the temperature of the inlet gases Tcol.

[0041] Thus, the spark-ignition engine system 1 allows for the application of electric water pump control that optimizes fuel consumption and maximizes engine performance in various usage scenarios, by mitigating or eliminating knocking without requiring reduction of ignition advances, by the possibility of targeted increase of the water flow rate for more efficient cooling of the combustion chamber walls.

[0042] Advantageously, the system 1 further comprises an air supply circuit for the internal combustion engine 2, which comprises from upstream to downstream, in the direction of air circulation towards the internal combustion engine 2: an air filter 12, a fresh air temperature sensor placed on the outlet 13 of the air filter 12, a compressor 5, a supercharged air cooler 8 supplied by said first compressor 5, an air intake valve 9, for example a butterfly valve, in the intake manifold 10 of the internal combustion engine 2.

[0043] The system 1 comprises a fuel supply to the internal combustion engine 2, which comprises, for example, fuel injectors for injecting fuel, for example, directly into the combustion chambers of the engine.

[0044] The internal combustion engine 2 is cooled by a cooling circuit 16 illustrated by [Fig.2], comprising a coolant temperature sensor Tco, an electric water pump 20 and a radiator 18 which is for example an air / water type exchanger.

[0045] The radiator 19 receives fresh air passing through it from an air inlet 17, as well as hot water arriving from the electric water pump 20 and from the internal combustion engine 2 according to the water flow rate Qwater at its inlet 21 and returns this water after having cooled it through its outlet 19 to the internal combustion engine 2.

[0046] The electric water pump 20 is capable of forcing the circulation of a flow of coolant from the internal combustion engine 2 to the pump and of discharging this flow to the radiator where the liquid is cooled.

[0047] In the present description, the term “water” is used indiscriminately to designate this coolant.

[0048] The liquid is then returned to the internal combustion engine 2.

[0049] In a manner known per se, the circuit is capable of regulating the temperature of the coolant Tco to a set value.

[0050] The assembly 24 for depolluting the combustion gases from the internal combustion engine 2 may comprise a particulate filter 6 and / or a three-way catalyst 7.

[0051] The internal combustion engine 2 further comprises an exhaust circuit 15.

[0052] The exhaust circuit 15 is illustrated more particularly in [Fig.2] and comprises from upstream to downstream in the direction of circulation of the burnt gases from the internal combustion engine 2: an exhaust manifold forming the exhaust circuit 15, a turbine 14, a depollution assembly 24 for the combustion gases from the internal combustion engine 2.

[0053] The turbine 14 is for example mounted on a shaft common to the compressor 5.

[0054] Advantageously, the system 1 comprises a turbocharger integrating both the compressor 5 and turbine 14, and the internal combustion engine 2 is a three-cylinder in-line engine of the type supercharged by said turbocharger.

[0055] Preferably, the computer is further configured to be able to apply a logic for controlling the water pump 20 taking into account the knocking measured by the knock sensor 11 by applying a curative correction factor greater than or equal to one to the water flow rate setpoint Qeau_cons, as a function of a knocking level Knk calculated by the computer from the knock sensor 11 positioned on the internal combustion engine 2.

[0056] For example, the water flow rate instruction Qeau_cons is limited to a threshold value Qmax less than or equal to the maximum water flow rate Qeau achievable by the electric water pump 20.

[0057] For example, Qmax is of the order of five cubic meters per hour.

[0058] The invention also relates to a method for implementing a system 1 as described previously.

[0059] Like the prior art methods illustrated by [Fig.3], the method comprises the steps described below.

[0060] The method begins with a first step E1 during which the computer applies a mapping of the water flow rate of the electric water pump 20 as a function of the current speed and torque of the internal combustion engine 2 to calibrate the water flow rate Qwater to just the amount necessary to satisfy the cooling needs of said internal combustion engine 2.

[0061] The “basic” water flow rate setpoint Qeau is therefore defined by the two-dimensional mapping, as a function of the engine speed and torque, then is modulated by a factor depending on the cooling water temperature Tco measured by the water temperature sensor, to arrive at the final water flow rate setpoint Qeau_cons.

[0062] This water flow rate instruction Qeau_cons is then transformed into an electrical command to the electric water pump 20 via the pump control computer.

[0063] As in the methods according to the prior art, the method uses a mapping Tl such as that illustrated by [Fig.4], which maps the water flow rate Qwater of the electric water pump 20 as a function of the current speed and torque of the internal combustion engine to calibrate the water flow rate Qwater.

[0064] [Fig.4] shows the Tl mapping of the calibrations typically adopted for pump control.

[0065] The basic water flow mapping is calibrated to just the extent necessary so that under hot engine conditions, i.e. so that the temperature Tco reaches at least a given threshold, for example equal to ninety degrees Celsius, and there is no overheating of the internal combustion engine 2.

[0066] The water flow requirement Qeau increases all the more as the speed and torque are high, because the heat output introduced by the fuel increases.

[0067] According to the maps T1 and T2 illustrated by Figures 4 and 5, the maximum required is three and a half cubic meters per hour even if the electric water pump 20 is capable of providing up to five and a half cubic meters per hour, so as to limit the electrical consumption and therefore the fuel consumption, since the battery powering the electric water pump 20 is recharged by an alternator mechanically driven by the combustion engine 2.

[0068] The method comprises a second step E2 carried out in parallel with the first step E1 and during which calculation is made from a modulation table T2 such that that illustrated by [Fig.5], a modulation coefficient to be applied to the water flow rate Qwater as a function of the cooling water temperature of the internal combustion engine Tco, for example via a table T2 such as that illustrated by [Fig.5].

[0069] The modulation table T5 is calibrated in such a way that the water flow rate Qwater is very low, i.e. almost zero, as long as the combustion engine 2 has not exceeded, for example, fifty degrees Celsius of water temperature so that the combustion engine 2 heats up as quickly as possible, which is reflected in the modulation table T5 by a coefficient equal to one tenth.

[0070] Thus, the basic water flow rate Qwater is restricted to ten percent of its value, which makes it possible to reduce the consumption penalty linked to higher engine friction when the combustion engine 2 is not hot.

[0071] When the temperature of the combustion engine 2 reaches the threshold of ninety degrees, there is no more modulation, that is to say the modulation coefficient is equal to one.

[0072] Between the two, the coefficient must be an increasing function of temperature.

[0073] The method also comprises a third step E3 during which the modulation coefficient calculated during the second step E2 is multiplied with the water flow rate Qeau calculated during the first step E1 to obtain a water flow rate setpoint Qeau_cons.

[0074] The third step E3 continues with a fourth step E4 during which the computer, for example coupled to a pump control module 22 and configured to be able to control the speed of the electric water pump 20, applies the water flow rate setpoint Qeau_cons to the electric motor 23.

[0075] The fourth step is followed by a fifth step E5 during which the electric water pump 20 is activated at said water flow rate setpoint Qeau_cons using the electric motor 23.

[0076] Unlike the prior art, the method further comprises a sixth step E6 preceding the fourth step E4 and during which the preventive correction factor for knocking greater than or equal to one is determined to be applied to said water flow rate setpoint Qeau_cons as a function of the cooling water temperature of the internal combustion engine 2 Tco and the temperature of the inlet gases Tcol, the sixth step E6 being followed by a ninth step E9 during which said preventive correction factor is multiplied with the water flow rate setpoint Qeau_cons calculated during the third step E3, said sixth step E6 continuing with the fourth step E4.

[0077] This method makes it possible to reduce or even eliminate knocking when necessary, without significant additional cost, by increasing the water flow rate Qwater of the electric water pump 20, so that it is not necessary to reduce the ignition advances which degrade the efficiency and performance of the internal combustion engine 2.

[0078] This effect being very noticeable in low speeds, the increase in electrical consumption linked to the increased flow rate Qwater on the side of the electric water pump 20 is largely counterbalanced by the lower fuel consumption on the side of the internal combustion engine 2 due to the fact that it is not necessary to degrade the ignition advances to counter the knocking.

[0079] For example, the preventive knock correction factor is determined during step E6 by a calibration table T3 as illustrated by [Fig.7].

[0080] The knocking phenomenon is all the more present as the temperature in the combustion chamber of the internal combustion engine 2 is high, which is reflected by the cooling water temperature Tco and by the temperature of the inlet gases Tcol measured by a temperature sensor in the manifold 10.

[0081] The control logic of the water pump 20 managed by the computer takes into account the knocking phenomenon by integrating one or two corrections on the water flow, namely a preventive correction, and optionally a curative correction.

[0082] If the preventive correction is correctly calibrated, the curative correction is not necessary but can be advantageously applied to take into account other elements unfavorable to knocking such as fuel with an octane number too low to calibrate the engine to its nominal power.

[0083] The additional increase in the water flow rate Qeau thanks to the curative correction makes it possible to treat these cases generating knocking.

[0084] The preventive correction is made in the form of a factor greater than or equal to 1 as a function of the water temperatures Tco and admitted gas temperatures Tcol.

[0085] For hot water temperature Tco and / or gas temperature Tcol conditions, for example hot external conditions with an inlet gas temperature Tcol in the intake manifold of the order of eighty degrees Celsius, the knocking phenomenon is present, and requires increasing the water flow rate compared to the base flow rate to reduce or even eliminate the knocking.

[0086] This preventive correction occurs beyond the nominal calibration conditions of the internal combustion engine 2 on its engine test bench, namely a coolant temperature Tco of the order of ninety degrees and an inlet gas temperature Tcol of the order of forty degrees Celsius, with an inlet fresh air temperature of the order of twenty-five degrees Celsius.

[0087] The method may further comprise a seventh step E7 during which a curative factor is determined as a function of the knock level Knk calculated by the computer from the knock sensor 11. The seventh step E7 is followed by an eighth step E8 during which the preventive correction factor is multiplied with the curative correction factor.

[0088] During the following ninth step E9, the result of step E8 is multiplied by the water flow rate setpoint Qeau_cons.

[0089] The method then returns to the fourth step E4.

[0090] The method may further comprise a tenth step E10 subsequent to the ninth step E9, during which the water flow rate setpoint Qeau_cons calculated during the ninth step E9 is compared to the threshold value Qmax.

[0091] The process is stopped if said threshold value Qmax is exceeded by said water flow rate setpoint Qeau_cons.

[0092] The method continues with the fourth step E4 if said water flow rate setpoint Qeau_cons is lower than said threshold value Qm.ax.

Claims

Claims

1. A spark-ignition engine system (1), comprising an internal combustion engine (2), an electric water pump (20) configured to be coupled to the internal combustion engine (2), an electric motor (23) configured to be able to drive the electric water pump (20), a computer configured to be able to control the speed of the electric water pump (20) to control the water flow rate (Qeau) of the electric water pump (20) by controlling the electric motor (23) by a water flow rate setpoint (Qeau_cons), an air intake circuit (2) and an exhaust circuit (15) associated with the internal combustion engine (2), a fuel supply circuit of the internal combustion engine (2), the internal combustion engine (2) being equipped with at least one knock sensor (11) in the internal combustion engine (2), the air intake circuit (2) comprising an intake manifold (10) equipped with a temperature sensor admitted gases (Tcol),the system (1) being characterized in that the computer is configured to be able to apply a logic for controlling the water pump (20) in which a preventive knock correction factor greater than or equal to one is applied to the water flow rate setpoint (Qeau_cons) as a function of the cooling water temperature of the internal combustion engine (2) (Tco) and the temperature of the inlet gases (Tcol).,

2. System (1) according to claim 1, in which the computer is further configured to be able to apply a logic for controlling the water pump (20) taking into account the knocking measured by the knock sensor (11) by applying a curative correction factor greater than or equal to one applied to the water flow rate setpoint (Qeau_cons) as a function of a knocking level (Knk) calculated by the computer from the knock sensor (11) positioned on the internal combustion engine (2).

3. System (1) according to claim 2, in which the water flow rate setpoint (Qeau_cons) is limited to a threshold value (Qmax) less than or equal to the maximum water flow rate (Qeau) achievable by the electric water pump (20).

4. System according to any one of claims 1 to 3, in which the air intake circuit (3) further comprises from upstream to downstream in the direction of circulation of the air towards the internal combustion engine (2): an air filter (12), a fresh air temperature sensor, a compressor (5), a supercharged air cooler (8) powered by said first compressor (5), an air intake valve (9) in the intake manifold (10) of the internal combustion engine (2).

5. System (1) according to claim 4, in which the exhaust circuit (15) comprises from upstream to downstream in the direction of circulation of the burnt gases from the internal combustion engine (2): an exhaust manifold (15), a turbine (14), a depollution assembly (24) for the combustion gases from the internal combustion engine (2).

6. System (1) according to claim 5, in which the assembly (24) for depolluting the combustion gases from the internal combustion engine (2) comprises a particulate filter (6) and / or a three-way catalyst (7).

7. System (1) according to any one of claims 5 and 6, further comprising a turbocharger integrating both the compressor (5) and the turbine (14), and the internal combustion engine (2) is a three-cylinder in-line engine of the type supercharged by said turbocharger.

8. Method for implementing a system (1) according to any one of claims 1 to 7, comprising a first step (El) during which the computer applies a mapping (Tl) of the water flow rate of the electric water pump (20) as a function of the current speed and torque of the internal combustion engine (2) to calibrate the water flow rate (Qeau) to just the amount necessary to satisfy the cooling needs of said internal combustion engine (2), a second step (E2) carried out in parallel with the first step (El) and during which a modulation coefficient to be applied to the water flow rate (Qeau) is calculated from a modulation table (T2) as a function of the cooling water temperature of the internal combustion engine (Tco),a third step (E3) during which the modulation coefficient calculated during the second step (E2) is multiplied with the water flow rate (Qeau) calculated during the first step (El) to obtain a water flow rate setpoint (Qeau_cons), a fourth step (E4) during which the computer configured to be able to control the speed of the electric water pump (20) applies the water flow rate setpoint (Qeau_cons) to the electric motor (23), the fourth step being followed by a fifth step (E5) during which, the electric water pump (20) is activated at said water flow rate setpoint (Qeau_cons), the method further comprising a sixth step (E6) preceding the fourth step (E4) and during which the preventive correction factor for knocking greater than or equal to one is determined to be applied to said water flow rate setpoint (Qeau_cons) as a function of the cooling water temperature of the internal combustion engine (2) (Tco) and the temperature of the inlet gases (Tcol), the sixth step (E6) being followed by a ninth step (E9) during which said preventive correction factor is multiplied with the water flow rate setpoint (Qeau_cons) calculated during the third step (E3), said sixth step (E6) continuing with the fourth step (E4).

9. Method according to claim 8 for implementing a system (1) according to claim 2 and any one of claims 3 to 7, further comprising a seventh step (E7) during which a curative factor is determined as a function of the knocking level (Knk) calculated by the computer from the knocking sensor (11), the seventh step (E7) being followed by an eighth step (E8) during which the preventive correction factor is multiplied with the curative correction factor, the eighth step (E8) continuing with the ninth step (E9), and said ninth step (E9) comprising the additional multiplication of this result with the water flow rate setpoint (Qeau_cons).

10. Method according to any one of claims 8 and 9 for implementing a system (1) according to claim 3, further comprising a tenth step (E10) after the ninth step (E9), during which the water flow rate setpoint (Qeau_cons) calculated during the ninth step (E9) is compared with the threshold value (Qmax), then either the method is stopped if said threshold value (Qmax) is exceeded by said water flow rate setpoint (Qeau_cons), or the method is continued towards the fourth step (E4) if said water flow rate setpoint (Qeau_cons) is lower than said threshold value (Qmax).

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