Method and system for controlling supercharged internal combustion engine configured to manage storage and desorption of liquid water in charge air cooler

Abstract

A method (100) for controlling a supercharged internal combustion engine (10), in which: the mass (Meau) of liquid water stored in real time on an inner wall of an exchanger (30) receiving a mixture of fresh air and recirculated combustion gas is estimated; determining a water mass difference ([delta] Meau) between the mass (Meau) of the water and a predetermined critical mass (MC) of the liquid water; and managing the maximum water mass that the exchanger (30) can store by controlling an EGR control valve (38c) to reduce the EGR rate (TxEGR) and / or by controlling a pump configured to circulate the cooling fluid in the exchanger (30) to reduce the flow rate (QWCAC) of the cooling fluid through the exchanger (30) and / or by increasing the temperature (TWCAC) of the cooling fluid in the exchanger (30) when the absolute value of the difference (abs (Delta Meauu)) is less than a threshold (S).

Description

[0001] The present invention relates to the field of internal combustion engines, in particular supercharged internal combustion engines, whether gasoline or diesel.

[0002] More particularly, the present invention relates to reducing condensation in a charge air cooler.

[0003] Typically, a supercharged internal combustion engine includes a charge air cooler and a low-pressure exhaust gas recirculation (EGR) circuit. The low-pressure EGR circuit allows combustion gases produced by combustion to be drawn into the intake system and reintroduced upstream of the supercharger.

[0004] These inert gases can increase the total mass of gas entering the combustion chamber in gasoline engines, which reduces the need to reduce intake manifold pressure to manage the charge. This limits pumping losses and improves combustion. On the other hand, primarily in diesel engines, the partial re-entry of the burned gases cools combustion temperatures and substantially reduces nitrogen oxide emissions.

[0005] However, the use of a low-pressure EGR loop can lead to water condensation in the engine's air intake system. This water typically comes from the humidity of the fresh air from the fresh air intake and / or from water vapor contained in the exhaust gas recirculated by the low-pressure EGR loop.

[0006] This condensation can then lead to:

[0007] - The injection of liquid water droplets upstream of the compressor, causing premature wear of the compressor impeller;

[0008] - Storing water at low points in the intake circuit, leading to corrosion problems, for example in the charge air cooler or EGR cooler.

[0009] Ice can form in the intake system under extreme ambient conditions, both during driving and when the engine is stationary and cooling. Slow, progressive accumulation, combined with frost, can lead to ice accumulation. When the ambient temperature rises above 0°C, this ice transforms into liquid, which in turn can cause corrosion or premature wear of the compressor impeller. This water can also be drawn into the engine (particularly during startup) and damage it.

[0010] Furthermore, during operating phases that promote water condensation (e.g. due to ambient conditions such as high ambient humidity and / or low ambient temperature, or due to engine operation), water vapor contained in the fresh air and EGR gas mixture is likely to condense in the intake circuit, in particular on surfaces of the charge air cooler.

[0011] This water is stored in the cooler and can be desorbed, which can disrupt the engine's combustion or even cause it to stall.

[0012] US 20200182204 proposes a method for controlling an EGR loop valve using a humidity sensor to prevent condensation in the intake loop. According to this method, the intake air humidity is measured, the mole fraction of water vapor contained in the intake air is determined, the water vapor pressure in the EGR loop is determined, and the EGR valve is opened to allow EGR gas to flow when the water vapor in the EGR loop is less than the saturation water vapor pressure in the EGR loop. This document proposes a variant in which the flow rate of coolant in the EGR cooler is increased before opening the EGR valve.

[0013] US 20140102428 also proposes a method for increasing the EGR exhaust gas recirculation flow rate when an estimated amount of accumulated condensate in an EGR cooler exceeds a threshold. The estimated amount of accumulated condensate is estimated as a function of the amount of evaporated condensate using a condensation model. This document proposes a variant in which the flow rate of coolant in the EGR cooler is increased.

[0014] However, the effect of these solutions is to restrict the flow of liquid water entering the engine due to stable conditions, and even to restrict the flow of water stored in the EGR cooler.None of these solutions are suitable for unstable (ie transient) engine operation.

[0015] Therefore, these solutions are not effective in dealing with the problem of water accumulation in the charge air cooler, which can be followed by a sudden release of water (particularly when the flow rate of the air and EGR gas mixture being ingested by the engine increases dramatically, for example, after the driver presses the accelerator pedal to request full load). The sudden release of liquid water into the combustion chamber can lead to combustion quenching (i.e., no torque production or misfire), which can ultimately damage the engine or some of its associated components (such as the depollution catalyst).

[0016] There is a need for improved management of the storage and desorption of liquid water in an intake circuit, more specifically in a charge air cooler of a charge air internal combustion engine.

[0017] It is therefore an object of the present invention to provide a method and engine control system configured to manage storage and desorption of liquid water in a charge air cooler.

[0018] The object of the present invention is a method for controlling an internal combustion engine comprising: at least one cylinder; a fresh air intake manifold supplied with fresh air by a duct provided with a flow meter; a compressor; a turbocharger; and a heat exchanger or charge air cooler downstream of the compressor and upstream of the intake manifold.

[0019] The engine further comprises: an exhaust circuit comprising, from upstream to downstream in the flow direction of the combustion gases, an exhaust manifold, a turbine of a turbocharger and a system for depolluting the combustion gases of the engine; and a circuit for partially recirculating the exhaust gases to the air intake, the circuit starting from a point in the exhaust circuit downstream of the turbine (in particular downstream of the system or a part of the gas depollution system) and opening into the fresh air supply duct upstream of the turbocharger compressor, the partial EGR recirculation circuit comprising an EGR control valve.

[0020] In the process, the mass of liquid water stored on the inner wall of the exchanger in real time is estimated; the water mass difference between the mass of the water and a predetermined critical mass of liquid water is determined; and when the absolute value of the difference is less than a threshold value, the maximum mass of water that can be stored in the exchanger is managed by controlling the EGR control valve to reduce the EGR rate and / or by controlling a pump configured to circulate the cooling fluid in the exchanger to reduce the flow rate of the cooling fluid through the exchanger and / or by increasing the temperature of the cooling fluid in the exchanger.

[0021] In this way, the process solves the problem of gradual condensation of liquid water in the charge air cooler in order to avoid any risk of rapid desorption and extinguishing of the engine combustion.

[0022] Typically, control methods for supercharged internal combustion engines are configured to manage the storage and desorption of liquid water in a charge air cooler.

[0023] Water in liquid form can be temporarily stored in the charge air cooler without risk to the engine, provided a balance is maintained between:

[0024] - The fresh air and EGR gas mixture condenses on the inner wall of the charge air cooler;

[0025] - evaporation of liquid water deposited on the inner walls of the charge air cooler; and

[0026] - Flow rate of fresh air and EGR gas mixture through the charge air cooler.

[0027] The process according to the invention makes it possible to establish a balance between these different points.

[0028] The step of estimating the mass of water makes it possible to determine the mass of water that the exchanger is able to temporarily store without desorbing it towards the combustion chamber.

[0029] Reducing the flow rate of cooling fluid through the exchanger has the effect of increasing the temperature of the inner walls of the exchanger, thereby promoting the evaporation of water stored on said inner walls, and increasing the temperature of the mixture of air and EGR gases passing through said exchanger, which increases the vaporization rate of the water stored in the exchanger.

[0030] The temperature of the cooling fluid flowing through the exchanger can be increased, in particular by means of a controlled thermostat that allows the liquid to circulate in the radiator or not, so as to increase the temperature of the walls of the exchanger.

[0031] Advantageously, the step of estimating the mass of liquid water stored in real time on the inner walls of the exchanger comprises:

[0032] - a step of estimating the mass flow of water vapor contained in the fresh air drawn in based on the temperature of the fresh air drawn in, the air flow rate and an estimate of the relative humidity of the environment, for example by means of a humidity rate sensor arranged in the air intake circuit (for example in a flow meter) or outside the vehicle, or by means of a meteorological service (in particular if the vehicle is a so-called “connected” vehicle);

[0033] - a step of estimating the mass flow of water vapor contained in the exhaust gas based on the fresh air flow, the injected fuel flow, the average composition of said fuel and the combustion richness;

[0034] - a step of estimating the mass flow rate of water vapor in the EGR partial recirculation pipe based on the mass flow rate of water vapor contained in the exhaust gas and the EGR rate;

[0035] - a step of estimating the mass flow rate of water vapor contained in the mixture of fresh air and EGR combustion gas upstream of the air compressor as equal to the sum of the mass flow rate of water vapor contained in the fresh intake air and the mass flow rate of water vapor in the EGR line;

[0036] - a step of estimating the mass flow of liquid water condensed on the inner wall of the exchanger as a function of the mass flow of water vapor contained in the mixture of fresh air and EGR combustion gases upstream of the air compressor, the temperature of said inner wall (for example by measuring the temperature of the coolant flowing through said exchanger via one or more sensors arranged upstream and / or downstream of said exchanger), and the value of the boost pressure; and

[0037] - a step of estimating the mass of liquid water stored on the inner wall surface of the exchanger based on the mass flow rate difference between the mass flow rate of liquid water condensed on the inner wall of the exchanger and the mass flow rate of water evaporated in the exchanger (which is determined based on the temperature of the gas passing through the exchanger and the mass flow rate of the engine).

[0038] For example, engine mass flow depends on air flow, fuel flow, and EGR rate.

[0039] For example, the step for estimating the mass of liquid water receives the time integral of the mass flow difference between the mass flow of liquid water condensed on the inner wall of the exchanger and the mass flow of water evaporated in the exchanger.

[0040] The time integral of the mass flow difference is permanently saturated by a predetermined maximum limit, which corresponds to the maximum mass of liquid water that can be stored in the exchanger given the current volume flow of gas through the exchanger.

[0041] Each value of the current (i.e. instantaneous) gas flow through the exchanger determines a maximum limit, i.e. the maximum mass of liquid water that can be stored in the exchanger, which is characterizable, depending on the exchanger's geometry, its inclination and the material constituting its gas-side exchange surface.

[0042] For example, to determine the maximum limit, a dry exchanger is weighed; the volume (usually covered by the flow of a mixture of air and EGR gases through the exchanger) is completely filled with water; and the exchanger is mounted on a test bench and purged with a constant air flow until the water it contains is mechanically evacuated without having to wait for it to evaporate. The exchanger is then weighed to estimate the mass of water it retains.

[0043] Advantageously, the step of estimating in real time the mass of stored liquid water comprises a step of estimating the volumetric flow of the engine as a function of the temperature of the gas passing through the exchanger, the maximum limit being determined as a function of said volumetric flow.

[0044] Advantageously, in the step of determining the water mass difference between the water mass and the critical liquid water mass, a critical water mass is determined, defined as the minimum water mass that would cause combustion to extinguish if it reaches the combustion chamber, and a subtraction is performed between the water mass and said critical water mass.

[0045] The critical water mass corresponds to the water mass that would lead to the risk of extinguishing the combustion if desorption phenomena occurred (for example in the case of a sharp increase in the air flow rate taken in by the engine after an acceleration request), which reduces the maximum limit (ie the maximum mass of liquid water that can be stored in the exchanger).

[0046] The critical water mass can be estimated by testing on a stationary engine test bench (by injecting increasing amounts of liquid water into the cylinder intake and measuring the engine pressure). The maximum permissible mass of liquid water per combustion cycle and per cylinder, as well as the maximum permissible mass of liquid water for the engine, can then be extrapolated, taking into account the engine's dynamics.

[0047] For example, the EGR rate setpoint reduction is applied continuously, i.e. as a maximum limit that must not be exceeded throughout the use of the engine, or applied once for a set time in order to reduce the mass of liquid water stored on the inner walls of the exchanger in real time.

[0048] For example, the reduction in the flow rate of cooling fluid through the exchanger is applied continuously, i.e. as a maximum limit that must not be exceeded throughout the use of the engine, or once for a specific time in order to reduce the mass of liquid water stored in real time on the inner walls of the exchanger.

[0049] For example, the increase in the flow temperature of the cooling fluid through the exchanger is applied continuously, i.e. as a maximum limit that must not be exceeded throughout the use of the engine, or it is applied once for a specific time in order to reduce the mass of liquid water stored in real time on the inner walls of the exchanger.

[0050] According to one embodiment, in which the motor vehicle is a hybrid vehicle comprising a heat engine and at least one electric motor, the step of managing the maximum mass of water that can be stored in the exchanger comprises the step of controlling the speed and torque of the electric motor in order to increase the flow rate sucked in by the heat engine in order to discharge the water film stored on the inner wall of the exchanger at a given point.

[0051] According to a second aspect, the invention relates to an electronic control unit for an internal combustion engine, comprising: at least one cylinder; a fresh air intake manifold supplied with fresh air by a duct provided with a flow meter; a compressor; a turbocharger; and a heat exchanger downstream of the compressor and upstream of the intake manifold.

[0052] The engine further comprises: an exhaust circuit comprising, from upstream to downstream in the flow direction of the combustion gases, an exhaust manifold, a turbine of a turbocharger, and a system for depolluting the combustion gases of the engine; and a circuit for partially recirculating the exhaust gases to the air intake, the circuit starting from a point in the exhaust circuit downstream of the turbine (in particular downstream of the gas depollution system or a portion of the gas depollution system) and leading to the fresh air supply duct upstream of the turbocharger compressor, the EGR partial recirculation circuit comprising an EGR control valve.

[0053] The electronic control unit includes an engine control system, which includes:

[0054] - A module for estimating in real time the mass of liquid water stored on the inner walls of the exchanger;

[0055] - means for determining a water mass difference between the water mass and a predetermined critical liquid water mass; and

[0056] - A module for managing the maximum water mass that can be stored in the exchanger, configured to reduce the EGR rate by controlling the EGR control valve and / or reduce the flow rate of the cooling fluid through the exchanger and / or increase the temperature of the cooling fluid in the exchanger by controlling a pump configured to circulate the cooling fluid in the exchanger when the absolute value of the water mass difference is less than a threshold value.

[0057] Generally speaking, a control system for a supercharged internal combustion engine is configured to manage the storage and desorption of liquid water in a charge air cooler.

[0058] Advantageously, the module for estimating the mass of liquid water stored in real time on the inner walls of the exchanger is configured to estimate the mass flow of water vapor contained in the fresh air drawn in as a function of the temperature of the fresh air drawn in, the air flow rate obtained by a flow meter and an estimate of the relative humidity of the environment (by means of a humidity rate sensor located in the air intake circuit (for example in the flow meter) or outside the vehicle, or by means of a meteorological service (in particular if the vehicle is a so-called “connected” vehicle)).

[0059] Advantageously, the module for estimating the mass of stored liquid water is further configured to estimate the mass flow of water vapor contained in the exhaust gas based on the fresh air flow, the injected fuel flow, the average composition of said fuel and the combustion richness, and thereby to infer the mass flow of water vapor in the EGR duct based on said mass flow of water vapor contained in the exhaust gas and the EGR rate.

[0060] Advantageously, the module for estimating the mass of stored liquid water is further configured to estimate the mass flow of water vapor contained in the mixture of fresh air and EGR combustion gases upstream of the air compressor by adding the mass flow of water vapor contained in the fresh intake air to the mass flow of water vapor in the EGR line.

[0061] Advantageously, the module for estimating the mass of stored liquid water is further configured to estimate the mass flow of liquid water condensed on the inner wall of the exchanger as a function of the mass flow of water vapor contained in the mixture of fresh air and combustion gases upstream of the air compressor, the temperature of said inner wall (for example by measuring the temperature of the coolant flowing through said exchanger via one or more sensors arranged upstream and / or downstream of said exchanger), and the value of the boost pressure.

[0062] Advantageously, the module for estimating the mass of stored liquid water is also configured to estimate the mass flow of the engine as a function of the air flow, the fuel flow and the EGR rate, and to deduce therefrom an estimate of the mass of water evaporated in the exchanger and an estimate of the volume flow of the engine as a function of the temperature of the gases passing through the exchanger.

[0063] For example, the module for estimating the mass of stored liquid water is further configured to estimate the mass of liquid water stored on the inner wall surface of the exchanger as the integral of the difference between the mass flow rate of liquid water condensed on the inner wall of the exchanger and the mass flow rate of water evaporated in the exchanger.

[0064] Advantageously, this integral is permanently saturated by a maximum limit corresponding to the maximum water volume that can be stored in the exchanger given the current volume flow of gas through the exchanger.

[0065] The water mass estimation module is used to determine the mass of liquid water that the exchanger can temporarily store without desorbing into the combustion chamber.

[0066] The quality of this stored liquid water is even more critical when the ambient humidity is high, the EGR rate is high, the boost pressure is high, the temperature of the cooling fluid flowing through the exchanger is low, and the flow rate of the mixture of air and EGR gases passing through the exchanger and entering the combustion chamber is low.

[0067] Advantageously, the management module is configured to control the various actuators of the internal combustion engine when the absolute value of said water mass difference is less than a threshold value (i.e. when the mass of the stored liquid water is too close to a critical water mass and risks causing a loss of combustion if a desorption phenomenon occurs (e.g. in the case of a sharp increase in the air flow rate sucked into the engine following an acceleration request)).

[0068] According to another aspect, the invention relates to a motor vehicle comprising an electronic control unit as described above.

[0069] Other objects, features and advantages of the present invention will become apparent from the following description, given by way of non-limiting example only, with reference to the accompanying drawings, in which:

[0070] Figure 1 An example of the construction of an internal combustion engine of a motor vehicle according to the invention is shown very schematically, the motor vehicle comprising a control unit containing a control system;

[0071] Figure 2 shows a curve illustrating the maximum mass of liquid water that can be stored in the heat exchanger as a function of the volume flow of the engine;

[0072] Figure 3 Indicated by Figure 1 An overview of the control process according to the present invention implemented by the control system; and

[0073] Figure 4 Explained in detail Figure 3 The quality estimation step of the process.

[0074] Figure 1 The overall structure of an internal combustion engine 10 of a motor vehicle, in particular a spark-ignition internal combustion engine running on gasoline, is shown schematically. Alternatively, the internal combustion engine may be a diesel engine.

[0075] These architectures are given by way of example and do not limit the invention to the only configurations to which the engine control according to the invention may be applied.

[0076] In the example shown, internal combustion engine 10 includes, in a non-limiting manner, three cylinders 12 connected in series, a fresh air intake manifold 14 , an exhaust manifold 16 , and a turbo compression system 18 .

[0077] The cylinders 12 are supplied with air via an intake manifold 14 or an intake distributor, which is itself supplied by a duct 20 provided with an air filter 22 and a compressor 18 b of a turbocharger 18 of the engine 10 .

[0078] Each cylinder 12 is supplied with fuel, such as gasoline.

[0079] In a known manner, the turbocharger 18 essentially comprises a turbine 18 a driven by the exhaust gases and a compressor 18 b mounted on the same axis or shaft as the turbine 18 a and compressing the air distributed by the air filter 22, in order to increase the amount of air (mass flow) entering the cylinders 12 of the engine 10. The turbine 18 a may be of the “variable geometry” type, i.e., the turbine wheel is equipped with blades of variable pitch in order to adjust the amount of energy extracted from the exhaust gases and, therefore, the boost pressure.

[0080] The heat exchanger 30 is placed after the outlet of the compressor 18 b fitted to the fresh air supply duct 14 a of the intake manifold 14 .

[0081] Therefore, the internal combustion engine 10 includes an intake circuit Ca, an exhaust circuit Ce, and a fuel injection circuit (not shown).

[0082] The intake circuit Ca comprises, from upstream to downstream in the direction of air flow:

[0083] - Air filter 22 or air box;

[0084] - a flow meter 24 arranged in the intake duct 20 downstream of the air filter 22; the flow meter 24 is configured to measure the actual value of the air flow entering the engine 10. The flow meter 26 measures only the flow of fresh air;

[0085] - an intake valve 26 , for example including a position sensor (not shown);

[0086] - a compressor 18 b of the turbocharger 18 , which is configured to compress air drawn in from the external atmosphere and, if necessary, recirculated exhaust gases to a low pressure, as will be described later;

[0087] - a throttle box 28 or valve, which is used to allow gas to enter the engine;

[0088] a heat exchanger 30 configured to cool the intake air corresponding to the mixture of fresh air and recirculated gas after compression in the compressor 18 b ; and

[0089] -Intake manifold 14.

[0090] Heat exchanger 30 is a "charge" air cooler, corresponding here to a water-charged air cooler. Hereinafter, the terms "heat exchanger 30" and "charge air cooler 30" refer to the same element. Alternatively, it could be an air-to-air cooler.

[0091] The exhaust circuit Ce comprises, from upstream to downstream in the flow direction of the combustion gas:

[0092] - exhaust manifold 16;

[0093] a turbine 18 a of a turbocharger 18 configured to extract energy from the exhaust gases passing therethrough, said expansion energy being transferred via a common shaft to a compressor 18 b for compressing the intake air;

[0094] - A system 40 for decontaminating combustion gases from an engine.

[0095] The exhaust manifold 16 recovers exhaust gas generated by combustion and discharges it to the outside via an exhaust pipe 30 leading to a turbine 18 a of the turbocharger 18 and via an exhaust line 36 installed downstream of the turbine 18 a .

[0096] By way of non-limiting example, the engine combustion gas depollution system 40 comprises a first device 42 comprising a three-way catalytic converter 42a associated with a first oxygen sensor 43a of the proportional type mounted upstream of the first depollution device 42, ie upstream of said catalytic converter 42a.

[0097] In a manner known per se, the first upstream oxygen sensor 43 a is generally used to regulate the richness value of the air-fuel mixture in the engine in a closed loop around a set value (e.g., a value 1 corresponding to a stoichiometric air-fuel mixture). "Richness" here refers to the ratio between the fuel mass flow rate and the air mass flow rate divided by the ratio between the fuel mass flow rate and the air mass flow rate at stoichiometry.

[0098] Furthermore, a second oxygen sensor 43 b, for example of binary or proportional type, is most often installed downstream of the first decontamination device 42 in order to be able to calibrate the setpoint of the above-mentioned richness regulation circuit, in particular for regulating the amount of oxygen stored inside the first decontamination device 42. However, the presence of this second downstream sensor is not essential for the implementation of the invention.

[0099] The gas depollution system 40 further includes a second device 44 (in this case, a fine particle filter) and an exhaust pipe 45, which is installed at the outlet of the second pollution control device 44 and leads to the outside. The gas depollution system 40 may also include a third oxygen sensor 43c, for example of a binary type, which is installed downstream of the second device 44, for example for diagnostic purposes.

[0100] As shown, the engine 10 comprises a circuit 38 for partially recirculating the exhaust gases to the air intake (called “EGR” circuit).

[0101] This circuit 38 (here a low-pressure exhaust gas recirculation circuit), called "EGR BP", starts downstream of the turbine 18a (specifically at Figure 1 In the case of the exhaust gas, the exhaust gas is returned to a point in the exhaust line 36 (here in the exhaust pipe 45) downstream of the gas decontamination system 40 and to a point in the fresh air supply duct 20 upstream of the compressor 18b of the turbocharger 18 (in particular downstream of the intake valve 26).

[0102] Alternatively, not shown, the low-pressure exhaust gas recirculation loop may start at the outlet of the turbine 18 a or only downstream of the partial gas depollution system 40 (for example between the first depollution device 42 and the second depollution device 44 ).

[0103] As shown in the figure, the recirculation loop 38 includes an EGR gas cooler 38a, a filter 38b and a "VEGR BP" control valve 38c configured to regulate the flow of low-pressure exhaust gas. The "VEGR BP" control valve 38c is located downstream of the cooler 38a and upstream of the compressor 18b.

[0104] By way of non-limiting example, the engine is associated with a fuel circuit including fuel injectors (not shown) that inject gasoline from a fuel tank 50 directly into each cylinder, for example.

[0105] The engine may also include, but is not limited to, a fuel vapor purge circuit 60 comprising a canister 62 or fuel vapor tank 62 that receives fuel vapor from the fuel tank 50, an active pump 64 connected downstream of the canister 62, and a purge solenoid valve 66 connected downstream of the pump 64. The purge solenoid valve 66 is connected to the engine air intake downstream of the flow meter 24.

[0106] The engine comprises an electronic control unit ECU including a control system 70 configured to control various elements of the internal combustion engine, in particular the EGR rate Tx_EGR, the flow rate Q_WCAC of the cooling fluid (water, in the case of an air-water exchanger) passing through the exchanger 30 and the temperature T_WCAC of the cooling fluid of the exchanger 30 .

[0107] Control system 70 receives data or estimated data collected by sensors at various locations on the engine.

[0108] The control system 70 may receive other data, such as temperature or other pressures at various locations in the engine.

[0109] The control system 70 includes a module 72 for estimating the mass M_eau of liquid water stored on the inner wall of the heat exchanger 30 in real time.

[0110] The module 72 for estimating the mass M_eau of liquid water stored in real time on the inner walls of the exchanger 30 is configured to estimate the mass flow Q_M_vapeur_A of water vapor contained in the fresh air drawn in, as a function of the temperature T_air of the fresh air drawn in, the air flow Qair obtained by the flow meter 24 and the estimated value H of the relative humidity of the environment (by means of a humidity rate sensor arranged in the intake circuit Ca (for example in the flow meter) or outside the vehicle, or by means of a meteorological service (in particular if the vehicle is a so-called “connected” vehicle)).

[0111] The module 72 is also configured to estimate the mass flow rate Q_M_vapeur_E of water vapor contained in the exhaust gases, more precisely in the total flow rate of combustion gases exhausted by the engine before the extracted portion is recirculated to the air intake, as a function of the fresh air flow rate Qair, the injected fuel flow rate Qcarb, the average composition carb of said fuel and the combustion richness, and it is configured to deduce therefrom the mass flow rate Q_M_vapeur_EGR of water vapor contained in the exhaust gases and the EGR rate Tx_EGR.

[0112] The module 72 is further configured to estimate the mass flow Q_M_vapeur_Ca of water vapor contained in the mixture of fresh air and EGR combustion gases upstream of the air compressor 18 b as equal to the sum ΣQ_M of the mass flow Q_M_vapeur_A of water vapor contained in the fresh intake air and the mass flow Q_M_vapeur_EGR of water vapor in the EGR duct 38 .

[0113] The module 72 is also configured to estimate the mass flow rate Q_M_WCAC of liquid water condensed on the inner wall of the exchanger 30 as a function of the mass flow rate Q_M_vapeur_Ca of water vapor contained in the mixture of fresh air and EGR combustion gases upstream of the air compressor 18 b, the temperature T_WCAC of said inner wall (for example, by measuring the temperature of the coolant flowing through said exchanger 30 via one or more sensors arranged upstream and / or downstream of said exchanger 30 ), and the boost pressure value Psuralim.

[0114] The module 72 is also configured to estimate the mass flow Q_M of the engine as a function of the air flow Qair, the fuel flow Qcarb and the EGR rate Tx_EGR, and from this to deduce an estimate of the mass flow Q_M_eau_evap of the water evaporated in the exchanger 30 and an estimate of the volumetric flow Q_V of the engine as a function of the temperature T_gaz_WCAC of the gases passing through the exchanger 30 .

[0115] The module 72 is also configured to estimate the mass M_eau of liquid water stored on the inner wall surface of the exchanger 30 as a time integral ∫ΔQ_M of the difference between the mass flow Q_M_WCAC of liquid water condensing on the inner wall of the exchanger 30 and the mass flow Q_M_eau_evap of water evaporated in the exchanger 30 .

[0116] The time integral ∫ΔQ_M is permanently saturated by a maximum limit M_eau_max, which corresponds to the maximum mass of liquid water that can be stored in the exchanger 30 given the volume flow of gases (air and EGR gas) passing through the exchanger 30 .

[0117] Depending on the geometry of the exchanger 30, its inclination and the material forming its gas-side exchange surface, the maximum mass of liquid water that said exchanger 30 can store can be characterized as a curve that decreases as a function of the volume flow of gas passing through the exchanger 30. In the normal case, the entire intake volume flow compressed in the compressor 18b is subsequently cooled, this passing volume flow being combined with the engine volume flow Q_V.

[0118] To determine the maximum mass of liquid water that can be stored in the exchanger, M_eau_max, the exchanger 30 is weighed in a dry state. The volume (typically filled with a mixture of air and EGR gases) is completely filled with water. The exchanger 30 is then mounted on a test bench and purged with a constant air flow until the water is mechanically evacuated without waiting for it to evaporate. The exchanger 30 is then weighed to estimate the mass of water it retains. This mass of water corresponds to the maximum mass of liquid water that can be stored, M_eau_max, for the constant air flow considered.

[0119] From this, we can infer that something like Figure 2 The curve shown here shows the volume flow Q_V through the exchanger on the abscissa and the maximum mass M_eau_max of liquid water that can be stored in the exchanger on the ordinate.

[0120] Note that since this is a strictly decreasing curve, whenever the volume flow Q_V through increases, for example from Figure 2 The value Q_V(A) corresponding to the abscissa of the midpoint A (where the mass of stored liquid water M_eau is not necessarily saturated with the maximum mass of storable liquid water M_eau_max) increases to Figure 2 The value Q_V(B) corresponding to the abscissa of point B in the figure is the mass of water released downstream of the exchanger, which corresponds to the difference between the mass of liquid water M_eau stored in real time corresponding to point A and the maximum mass of liquid water M_eau_max(B) corresponding to the volume flow rate at point B. In particular, when the flow rate suddenly increases to the maximum engine flow rate Q_V(Pmax) at the full load point at the maximum power of the engine, as shown in FIG. Figure 2 As shown at point Pmax in the graph, the maximum mass M_liquidwater stored in the exchanger decreases dramatically to the maximum mass of liquid water that can be stored, M_eau_max(Pmax), at the point of maximum power Pmax. If the amount released is greater than or too close to the critical mass of liquid water that could extinguish combustion, the release of liquid water becomes dangerous.

[0121] The module 72 for estimating the mass of liquid water M_eau is used to determine the mass of water that the heat exchanger 30 is able to temporarily store without desorbing towards the combustion chamber.

[0122] The quality of this stored liquid water is even more critical when the ambient humidity is high, the EGR rate is high, the boost pressure is high, the temperature of the cooling fluid passing through the exchanger 30 is low, and the flow rate of the mixture of air and EGR gases passing through said exchanger 30 and entering the combustion chamber is low.

[0123] In fact, the mass of the liquid water stored on the inner wall of the heat exchanger 30 is not a problem as long as it remains stored, but it becomes the case that after a strong and rapid increase in the flow of the mixture of air and EGR gases passing through the exchanger 30 (for example associated with a high load demand, associated with a downshift resulting in an increase in torque and speed, pressing the accelerator pedal, etc.), the stored liquid water will then suddenly be desorbed from the wall of the heat exchanger 30 and introduced into the combustion chamber of the engine.

[0124] The control system 70 further comprises a module 74 for determining a water mass difference ΔM_eau between the mass M_eau of the liquid water and a critical mass MC of the liquid water, which corresponds to a minimum water mass that would cause combustion to extinguish if liquid water quickly reaches the combustion chamber.

[0125] The critical water mass MC corresponds to the water mass that would lead to a risk of extinguishing combustion if a desorption phenomenon were to occur (for example, in the case of a sharp increase in the air flow rate taken in by the engine after a request for acceleration).

[0126] The critical water mass MC can be estimated by testing on a fixed engine test bench by injecting increasing masses of liquid water into the cylinders and measuring the engine pressure, which allows an estimate of the indicated torque produced. The maximum permissible mass of liquid water per combustion cycle and per cylinder corresponding to a combustion fault can then be deduced.

[0127] Then, by knowing the dynamics of the engine (ie the duration required to reach the point of maximum power and therefore the number of combustion cycles), the critical water mass MC of the engine can be deduced.

[0128] Control system 70 also includes a module 76 for managing the maximum mass of liquid water that can be stored by heat exchanger 30. Management module 76 is configured to control various actuators of the internal combustion engine when the absolute value abs(ΔM_eau) of the difference ΔM_eau is less than a calibratable threshold value S. This corresponds to the fact that the mass of liquid water that can be released, corresponding to the difference between the mass M_eau of liquid water stored in real time and the maximum mass M_eau_max (Pmax) of liquid water that can be stored at the maximum power point, becomes equal to or too close to the critical water mass MC, taking into account a safety margin, and risks causing combustion to extinguish if desorption occurs (for example, when the air flow rate of the engine intake increases sharply after a request to accelerate to maximum engine power).

[0129] The management module 76 is particularly configured to control the various actuators of the internal combustion engine in order to limit the mass of water stored in the heat exchanger 30 .

[0130] Thus, the management module 76 is specifically configured to reduce the EGR rate setpoint Tx_EGR in order to bring less humidity (and therefore less liquid water) to the inlet of the heat exchanger 38. This reduction in the EGR rate setpoint can be continuous, i.e. applied as a maximum limit that must not be exceeded throughout the use of the engine, or applied once for a set time in order to reduce the mass M_eau of liquid water stored in real time on the inner walls of the heat exchanger 38.

[0131] The management module 76 is also configured to reduce the flow rate of cooling fluid passing through the exchanger 30 by controlling the pump that supplies said cooling fluid. This has the effect of increasing the temperature T_WCAC of the inner walls of the exchanger 30, thus promoting the evaporation of the water stored on said inner walls, and increasing the temperature T_WCAC of the mixture of air and EGR gases passing through said exchanger 30, which increases the evaporation rate of the water stored in the exchanger 30.

[0132] The reduction in the flow of cooling fluid through the exchanger 30 can be continuous, i.e. applied as a maximum limit that must not be exceeded throughout the use of the engine, or applied once for a specific time in order to reduce the mass M_eau of liquid water stored in real time on the inner wall of the exchanger 30.

[0133] Finally, the management module 76 is also configured to increase the temperature of the cooling fluid flowing through the exchanger 30 , in particular by means of a controlled thermostat that allows the liquid to circulate in the radiator or not, so as to increase the temperature T_WCAC of the internal walls of the exchanger 30 .

[0134] If the motor vehicle is a hybrid vehicle comprising an internal combustion engine and at least one electric motor, the management module 76 is configured to control the speed N and torque C of the electric motor to increase the flow rate sucked by the internal combustion engine in order to remove the water film stored on the inner wall of the heat exchanger 30 .

[0135] Therefore, the management module 76 is configured to select one of the solutions capable of limiting the mass of water stored in the heat exchanger 30 , depending on the conditions and the operating point of the engine.

[0136] Thus, if intervention is required at low loads to contain the mass of water stored in real time, and if there is no need to contain the intake air temperature to limit knock or improve performance, priority can be given to, for example, increasing the temperature of the cooling fluid flowing through heat exchanger 30. On the other hand, at high loads, to contain the intake air temperature to limit knock or improve performance, it is preferable to reduce the EGR rate setpoint Tx_EGR. At low ambient temperatures, and in situations where there are no risks to the cooling circuit, for example, it is preferable to increase the temperature of the cooling fluid passing through heat exchanger 30, while at warm ambient temperatures (or engine temperatures), this solution is excluded. It should be noted that each of these solutions can be used individually or simultaneously.

[0137] Figure 3 The engine control process 100 shown in detail in FIG. 1 includes a step 102 of initializing the mass of water stored in the exchanger 30 .

[0138] The engine control method 100 further includes a step 110 of estimating the mass M_eau of liquid water stored on the inner wall of the heat exchanger 30 in real time, a step 125 of determining a water mass difference ΔM_eau between the water mass M_eau and a critical liquid water mass MC (corresponding to a minimum water mass that would cause combustion to extinguish if it rapidly reaches the combustion chamber), and a step 130 of managing the maximum water mass that can be stored in the heat exchanger 30 when the absolute value abs(ΔM_eau) of the difference ΔM_eau is less than a threshold value S. In the step 130 of managing the maximum water mass that can be stored in the heat exchanger 30, various actuators of the internal combustion engine are controlled to limit the water mass stored in the heat exchanger 30, as will be described later.

[0139] Figure 4 The step 110 of estimating the quality M_eau is described in detail.

[0140] The step 110 of estimating the mass M_eau of liquid water stored in real time on the inner walls of the exchanger 30 comprises a step 111 of estimating the mass flow Q_M_vapeur_a of water vapor contained in the incoming fresh air as a function of the incoming fresh air temperature T_air, the air flow Qair obtained by the flow meter 24 and an estimate of the relative humidity H of the environment (by means of a humidity rate sensor arranged in the intake circuit Ca (for example in the flow meter 24) or outside the vehicle, or by means of a meteorological service, in particular if the vehicle is a “connected” vehicle).

[0141] The step 110 of estimating the mass M_eau further comprises a step 112 of estimating the mass flow rate Q_M_vapeur_E of water vapor contained in the exhaust gas based on the fresh air flow rate Qair, the injected fuel flow rate Qcarb, the average composition carb of said fuel and the combustion richness, taking into account the total flow rate of combustion gases leaving the engine, and a step 113 of estimating the mass flow rate Q_M_EGR of water vapor in the EGR duct 38 based on the mass flow rate Q_M_E of water vapor contained in the exhaust gas and the EGR rate Tx_EGR.

[0142] The step 110 of estimating the mass M_eau also comprises a step 114 of estimating the mass flow Q_M_vapeur_Ca of the mixture of fresh air and EGR combustion gases upstream of the air compressor 18 b as being equal to the sum ΣQ_M of the mass flow Q_M_vapeur_A of the water vapor contained in the fresh air intake and the mass flow Q_M_vapeur_EGR of the water vapor in the EGR duct 38 , calculated in step 115 .

[0143] The step 110 of estimating the mass M_eau also comprises a step 116 of estimating the mass flow Q_M_WCAC of liquid water condensed on the inner wall of the exchanger 30 as a function of the mass flow Q_M_vapeur_Ca of the mixture of fresh air and combustion gases EGR upstream of the air compressor 18 b, the temperature T_WCAC of the inner wall (for example by measuring the temperature of the coolant flowing through the exchanger 30 via one or more sensors arranged upstream and / or downstream of the exchanger 30 ) and the value of the boost pressure Psuralim.

[0144] Step 110 for estimating the mass M_eau also includes a step 117 for estimating the mass flow Q_M of the engine based on the air flow Qair, the fuel flow Qcarb and the EGR rate Tx_EGR, a step 118 for estimating the mass flow Q_M_eau_evap of water evaporated in the exchanger 30 based on the mass flow Q_M of the engine and the temperature T_gaz_WCAC of the gas passing through the exchanger 30, and a step 119 for estimating the volume flow Q_V of the engine based on the mass flow Q_M of the engine and the temperature T_gaz_WCAC of the gas passing through the exchanger 30.

[0145] The step 110 of estimating the mass M_eau further includes a step 120 of estimating the mass M_eau of the liquid water stored on the inner wall surface of the exchanger 30 as the time integral ∫ΔQ_M of the difference ΔQ_M between the mass flow rate Q_M_WCAC of the liquid water condensed on the inner wall of the exchanger 30 and the mass flow rate Q_M_eau_evap of the water evaporated in the exchanger 30. This difference ΔQ_M is calculated in step 121.

[0146] The time integral ∫ΔQ_M is saturated by the maximum limit M_eau_max calculated in step 122. The maximum limit M_eau_Max corresponds to the maximum mass of liquid water that can be stored in the exchanger 30 given the volume flow Q_V of gas passing through the exchanger 30.

[0147] Depending on the geometry, the inclination and the material forming the gas-side exchange surface of the exchanger 30 , the mass of water that the exchanger 30 can store can be characterized as a function of the gas flow Q_V through the exchanger 30 .

[0148] The determination of the maximum limit M_eau_Max is as described above and will not be repeated in the remaining description.

[0149] Step 110 for estimating the current mass M_eau of liquid water makes it possible to determine the mass of water that the heat exchanger 30 is able to temporarily store without desorbing towards the combustion chamber.

[0150] The step 125 of determining the difference ΔM_eau between the mass of water M_eau and the mass MC of critical liquid water comprises a step 126 of determining a critical water mass MC corresponding to a minimum water mass that would lead to extinction of the combustion if water rapidly reaches the combustion chamber.

[0151] The critical water mass MC corresponds to the water mass which would lead to a risk of extinguishing the combustion if a desorption phenomenon were to occur (e.g. in the event of a sharp increase in the air flow ingested by the engine, e.g. following an acceleration demand, which would lead to a sudden increase in the engine volume flow Q_V to a volume flow value at the full load point at maximum engine power).

[0152] The critical water mass MC is determined as described above.

[0153] The step 125 of determining the difference ΔM_eau comprises a step 127 of subtracting the water mass M_eau from the critical liquid water mass MC.

[0154] The step 130 for managing the maximum mass of water that the exchanger 30 can store comprises a step 131 of determining one of the subsequent options capable of limiting the mass of water stored in the exchanger 30 as a function of the engine's conditions and operating point.

[0155] Therefore, if intervention is required at low loads to limit the amount of water stored in real time, and if intake air temperature does not need to be limited to limit knock or improve performance, priority may be given to, for example, increasing the temperature of the cooling fluid flowing through heat exchanger 30. On the other hand, at high loads, to control intake air temperature to limit knock or improve performance, it may be preferable to reduce the EGR rate setpoint Tx_EGR. At low ambient temperatures, and without any risk to the cooling circuit, for example, increasing the temperature of the cooling fluid flowing through heat exchanger 30 may be preferable, while at warm ambient temperatures (or engine temperatures), this solution would be excluded. It should be noted that each of these solutions can be used individually or simultaneously.

[0156] The step 130 for managing the maximum mass of water that can be stored in the exchanger 30 comprises a step 132 of reducing the EGR rate setpoint Tx_EGR so as to bring less humidity (and therefore less liquid water) to the inlet of the exchanger 38. This reduction in the EGR rate setpoint can be continuous, i.e. applied as a maximum limit that must not be exceeded throughout the use of the engine, or applied once for a set time in order to reduce the mass M_eau of liquid water stored in real time on the inner walls of the exchanger 30.

[0157] The step 130 for managing the maximum mass of water that the exchanger 30 can store comprises a step 133 of reducing the flow rate of cooling fluid flowing through the exchanger 30 by controlling the pump that supplies said cooling fluid. This has the effect of increasing the temperature T_WCAC of the internal walls of the exchanger 30, thereby promoting the evaporation of the water stored on said walls, and increasing the temperature T_WCAC of the mixture of air and EGR gases that passes through said exchanger 30, which increases the evaporation rate of the water stored in the exchanger 30.

[0158] The reduction in the flow of cooling fluid through the exchanger 30 can be continuous, i.e. applied as a maximum limit that must not be exceeded throughout the use of the engine, or applied once for a specific time in order to reduce the mass M_eau of liquid water stored in real time on the inner wall of the exchanger 30.

[0159] Finally, the step 130 of managing the maximum mass of water that the exchanger 30 can store comprises a step 134 of increasing the temperature of the cooling fluid flowing through the exchanger 30 , in particular using a controlled thermostat capable of circulating the liquid in the radiator or not, so as to increase the temperature T_WCAC of the internal walls of the exchanger 30 .

[0160] If the motor vehicle is a hybrid vehicle comprising a heat engine and at least one electric motor, the step 130 for managing the maximum mass of water that the heat exchanger 30 can store comprises a step 135 for controlling the speed N and the torque C of the electric motor in order to increase the flow rate sucked in by the heat engine in order to remove the water film stored on the inner wall of the heat exchanger 30 .

[0161] Steps 132, 133 and 134 may be activated individually or simultaneously.

[0162] During step 130 for managing the maximum mass of water that the heat exchanger 30 can store, the EGR rate Tx_EGR and / or the flow rate Q_WCAC of the cooling fluid through the heat exchanger 30 and / or the temperature T_WCAC of the cooling fluid in the heat exchanger 30 can be controlled, and / or in the case of a hybrid vehicle, the speed N and the torque C of the electric motor can be controlled, these actions being cumulative.

[0163] Thanks to the invention, it is possible to solve the problem of gradual condensation of liquid water in the charge air cooler, so as to avoid any risk of rapid desorption and extinguishing of the engine combustion.

Claims

1. A method (100) for controlling an internal combustion engine (10), the internal combustion engine (10) comprising: at least one cylinder (12); a fresh air intake manifold (14) supplied with fresh air from a pipe (20) provided with a flow meter (24); A compressor (18b); a turbocharger (18); and a heat exchanger (30) downstream of the compressor (18b) and upstream of the intake manifold (14), the engine further comprising an exhaust circuit (Ce) and a partial recirculation circuit (38) for inhaled exhaust gas, the exhaust circuit (Ce) comprising, from upstream to downstream in the flow direction of the combustion gas, an exhaust manifold (16), a turbine (18a) of the turbocharger (18) and a depollution system (40) for the combustion gas of the engine, the partial recirculation circuit (38) starting from a point of the exhaust circuit (Ce) downstream of the turbine (18a) and leading to a fresh air supply duct (20) upstream of the compressor (18b) of the turbocharger (18), the partial EGR recirculation circuit (38) comprising an EGR control valve (38c), wherein: - Estimation of the mass of liquid water (M_eau) stored in real time on the inner wall of said exchanger (30); - determining the water mass difference (ΔM_eau) between the mass of the water (M_eau) and a predetermined critical mass (MC) of liquid water; and - when the absolute value of the difference (abs(ΔM_eau)) is less than a threshold value (S), managing the maximum mass of water that the exchanger (30) can store by controlling the EGR control valve (38c) to reduce the EGR rate (Tx_EGR) and / or by controlling a pump configured to circulate the cooling fluid in the exchanger (30) to reduce the flow rate (Q_WCAC) of the cooling fluid through the exchanger (30) and / or by increasing the temperature (T_WCAC) of the cooling fluid in the exchanger (30).

2. The method according to claim 1, wherein The step (110) of estimating the mass (M_eau) of liquid water stored in real time on the inner wall of the exchanger (30) comprises: - step (111), estimating the mass flow rate of water vapor contained in the inhaled fresh air (Q_M_vapeur_A) based on the estimated values ​​of the inhaled fresh air temperature (T_air), the air flow rate (Qair) and the relative humidity of the environment (H); - step (112), estimating the mass flow of water vapor contained in the exhaust gas (Q_M_vapeur_E) based on the fresh air flow (Qair), the injected fuel flow (Qcarb), the average composition of said fuel (carb) and the combustion richness; - Step (113), estimating the mass flow rate (Q_M_vapeur_EGR) of water vapor in the partial EGR recirculation line (38) based on the flow rate (Q_M_vapeur_E) of water vapor contained in the exhaust gas and the EGR rate (Tx_EGR); - step (114), estimating the mass flow rate (Q_M_vapeur_Ca) contained in the mixture of fresh air and EGR combustion gases upstream of the air compressor (18b) as being equal to the sum (∑Q_M) of the mass flow rate of water vapor contained in the inhaled fresh air (Q_M_vapeur_A) and the mass flow rate of water vapor in the EGR line (38) (Q_M_vapeur_EGR); - a step (116) of estimating the mass flow rate (Q_M_WCAC) of liquid water condensed on the inner wall of the exchanger (30) as a function of the mass flow rate (Q_M_vapeur_Ca) of the mixture of fresh air and EGR combustion gases upstream of the air compressor (18b), the temperature (T_WCAC) of the inner wall and the boost pressure value (Psuralim); and - Step (120) of estimating the mass (M_eau) of liquid water stored on the inner wall surface of the exchanger (30) based on the mass flow difference (ΔQ_M) between the mass flow of liquid water condensed on the inner wall of the exchanger (30) (Q_M_WCAC) and the mass flow of water evaporated in the exchanger (30) (Q_M_eau_evap), the mass flow difference (ΔQ_M) being determined based on the temperature (T_gaz_WCAC) of the gas passing through the exchanger (30) and the mass flow (Q_M) of the engine.

3. The method according to claim 2, wherein: The step (120) of estimating the mass of liquid water (M_eau) receives the time integral (∫ΔQ_M) of the mass flow difference (ΔQ_M) between the mass flow of liquid water condensed on the inner wall of the exchanger (30) (Q_M_WCAC) and the mass flow of water evaporated in the exchanger (30) (Q_M_eau_evap).

4. The method according to claim 3, wherein: The time integral (∫ΔQ_M) of the mass flow difference (ΔQ_M) is permanently saturated by a predetermined maximum limit (M_eau_max), which corresponds to the maximum mass of liquid water that can be stored in the exchanger (30) given the current volume flow of gas through the exchanger (30).

5. The method according to claim 4, wherein Said step (110) of estimating the mass of liquid water stored in real time (M_eau) comprises a step (119) of estimating the volumetric flow (Q_V) of said engine as a function of the temperature (T_gas_WCAC) of the gas passing through said exchanger (30), and wherein said maximum limit (M_eau_max) is determined as a function of said volumetric flow (Q_V).

6. A method according to any one of the preceding claims, wherein In step (125) of determining a water mass difference (ΔM_eau) between the water mass (M_eau) and a critical liquid water mass (MC), in step (126) the critical water mass (MC) is determined, the critical water mass (MC) corresponding to the minimum liquid water mass that will cause combustion to extinguish if liquid water reaches the combustion chamber, and a subtraction is performed between the water mass (M_eau) and the critical water mass (MC).

7. A method according to any one of the preceding claims, wherein The reduction in the EGR rate set point (Tx_EGR) may be continuous or applied in a one-time manner over a determined period of time.

8. A method according to any one of the preceding claims, wherein The reduction in the flow of cooling fluid through the exchanger (30) is applied continuously or in a one-time manner over a determined period of time.

9. A method according to any one of the preceding claims, wherein The motor vehicle is a hybrid vehicle comprising a heat engine and at least one electric motor, and wherein the step (130) of managing the maximum mass of water that the exchanger (30) can store comprises a step (135) of controlling the speed (N) and the torque (C) of the electric motor in order to increase the flow rate sucked in by the heat engine.

10. An electronic control unit (ECU) for an internal combustion engine (10), the internal combustion engine (10) comprising: at least one cylinder (12); a fresh air intake manifold (14) supplied with fresh air from a pipe (20) provided with a flow meter (24); A compressor (18b); a turbocharger (18); and a heat exchanger (30) downstream of the compressor (18b) and upstream of the intake manifold (14), the engine further comprising an exhaust circuit (Ce) and a partial recirculation circuit (38) for inhaled exhaust gas, the exhaust circuit (Ce) comprising, from upstream to downstream in the flow direction of the combustion gas, an exhaust manifold (16), a turbine (18a) of the turbocharger (18), and a depollution system (40) for the combustion gas of the engine, the partial recirculation circuit (38) starting from a point of the exhaust circuit (Ce) downstream of the turbine (18a) and leading to a fresh air supply duct (20) upstream of the compressor (18b) of the turbocharger (18), the EGR partial recirculation circuit (38) comprising an EGR control valve (38c), the electronic control unit (ECU) comprising an engine control system (70), the engine control system (70) comprising: - a module (72) for estimating in real time the mass (M_eau) of liquid water stored on the inner wall of said exchanger (30); - a module (74) for determining the difference in mass of water (ΔM_eau) between the mass of water (M_eau) and a predetermined critical mass of liquid water (MC); and - a module (76) for managing the maximum water mass that the exchanger (30) can store, the module (76) being configured to reduce the EGR rate (Tx_EGR) by controlling the EGR control valve (38c) and / or reduce the flow rate (Q_WCAC) of the cooling fluid flowing through the exchanger (30) and / or increase the temperature (T_WCAC) of the cooling fluid in the exchanger (30) by controlling a pump configured to circulate the cooling fluid in the exchanger (30) when the absolute value of the difference (abs(ΔM_eau)) is less than a threshold (S).

11. A motor vehicle comprising an electronic control unit according to claim 10.

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