Method and control system of a supercharged spark-ignition internal combustion engine configured to purge a charge air cooler

Abstract

A method (100) for controlling a supercharged, spark-ignition internal combustion engine comprising a heat exchanger mounted downstream of a compressor in a supercharging system and a control valve mounted between the compressor and the heat exchanger, wherein: - the mass (M_water) of liquid water stored in real time on the internal walls of the exchanger is estimated; - said estimated mass (M_water) is compared with a threshold value (S); and - the cooler purge is activated when the estimated mass of water (M_water) is greater than the threshold value (S), by generating oscillations in the intake air flow rate entering the exchanger between a nominal flow rate value and an increased flow rate value, and oscillations in the ignition timing between a nominal advance value and a degraded nominal advance value. Figure for the abstract: Fig 3

Description

Title of the invention: Method and system for controlling a supercharged spark-ignition internal combustion engine configured to purge a charge air cooler

[0001] The present invention relates to the field of spark-ignition internal combustion engines, in particular for motor vehicles, and more particularly supercharged internal combustion engines, running on petrol or alcohol or LPG, comprising a system for partial recirculation of exhaust gases at the engine intake.

[0002] More particularly, the invention relates to the reduction of condensation, or even purging in a charge air cooler.

[0003] As the pollutant emission standards for internal combustion engines such as diesel engines are becoming increasingly strict, these engines are generally designed with exhaust gas recirculation systems at the intake, known in English as "Exhaust Gas Recirculation" or "EGR". Such EGR systems generally comprise a recirculation circuit for the high-pressure duct sampling the exhaust gases upstream of the turbocharger turbine, a recirculation circuit for the low-pressure duct sampling the exhaust gases downstream of a pollution control member of the exhaust line, and a heat exchanger in order to cool the gases present in the low-pressure recirculation circuit and reintroduce them at the engine inlet. The low-pressure EGR circuit makes it possible to re-aspirate burnt gases from combustion at the intake and reintroduce them upstream of the supercharger.

[0004] These inert gases make it possible in particular to increase the total mass of gas admitted into the combustion chamber in a gasoline engine, which reduces the need to lower the pressure of the intake manifold to manage the air charge. This limits pumping losses and improves combustion. This results in a reduction in fuel consumption.

[0005] More particularly, the present invention relates to gas recirculation systems comprising a cold water charge air cooler, or Water Charge Air Cooler (W-CAC) in English terms, located downstream of the compressor of the turbocharger system and upstream of the intake manifold.

[0006] In order to meet pollution control standards, internal combustion engines may be forced to use the low-pressure gas recirculation circuit when cold. However, the low-pressure gas recirculation circuit contains burnt gases loaded with water. Thus, when the engine is cold, there is a risk of condensation of the water present in the gas recirculation system at the charge air cooler.

[0007] The use of a low-pressure EGR circuit therefore leads to problems of water condensation in the engine intake circuit. This water generally comes from the humidity of the fresh air arriving from the fresh air intake and / or from the water vapor contained in the exhaust gases recirculated by the low-pressure EGR circuit.

[0008] This condensed water can then lead to:

[0009] - to the projection of liquid water droplets upstream of the compressor, causing premature wear of the wheel of said compressor;

[0010] - to the storage of water in low points of the intake circuit causing problems corrosion problems, for example of the charge air cooler or the EGR cooler.

[0011] - to the formation of ice in the intake circuit under ambient conditions extremes, either during the running phase or when the engine is cooling down when stopped. Slow progressive storage concomitant with freezing can then lead to ice buildup. When the ambient temperature rises above 0°C, this ice turns into liquid, which in turn can cause corrosion or premature wear of the compressor wheel. This water can also be sucked into the engine, particularly during the engine start-up phase, and damage it.

[0012] Furthermore, during operating phases that promote water condensation, for example due to environmental conditions, such as high ambient humidity and / or low ambient temperature, or due to the operation of the engine, the water vapor contained in the mixture of fresh air and EGR gas is likely to condense in the intake circuit and in particular on the surface of the charge air cooler.

[0013] This water is stored in the cooler and can be desorbed, which can disrupt the combustion of the engine, or even turn it off. Indeed, the storage of water in the charge air cooler can be followed by a sudden release phenomenon, in particular during a sharp increase in the flow rate of the mixture of air and EGR gas drawn in by the engine, for example, following a request for full load when the driver presses the accelerator pedal. This sudden release of liquid water into the combustion chamber can lead to combustion extinction, i.e. the absence of torque production or combustion misfires, known as "misfire" in English terms, which can, in the long term, damage the engine or some of its associated components such as a pollution control catalyst.

[0014] In order to avoid such a condensation phenomenon, the motor operates with the circuit high pressure exhaust gas recirculation while waiting for the intake line temperature to reach a threshold value to prevent condensation in the charge air cooler.

[0015] Document FR 3 064 678 - B1 is known, which proposes a solution for estimating the risk of condensation in the charge air cooler in order to control the exhaust gas recirculation system. Thus, in the event of water accumulation in the charge air cooler, the EGR valve is closed in order to wait for favorable conditions to evacuate the condensed water. However, such a solution is not satisfactory because it requires the EGR valve to be closed for a long time, which generates a deterioration in fuel consumption.

[0016] There is a need to improve the management of storage and desorption of liquid water in the intake circuit, and more particularly in the charge air cooler of a supercharged spark-ignition internal combustion engine.

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

[0018] The present invention relates to a method for controlling a spark-ignition internal combustion engine comprising at least one cylinder, a fresh air intake manifold supplied with fresh air via a pipe, a compressor of a turbocharger and a heat exchanger downstream of said compressor and upstream of the intake manifold, the engine further comprising an exhaust circuit comprising, from upstream to downstream in the direction of circulation of the burnt gases, an exhaust manifold, a turbine of the turbocharger and, for example, a system for depolluting the combustion gases of the engine.

[0019] The engine further comprises a circuit for partial recirculation of the exhaust gases to the intake originating at a point in the exhaust circuit, downstream of said turbine, and opening into the fresh air supply pipe, upstream of the turbocharger compressor, said intake circuit comprising a control valve or throttle body mounted between the compressor and the heat exchanger.

[0020] According to the method: - the mass of liquid water stored in real time on the internal walls of the exchanger is estimated; - the said estimated mass is compared with a threshold value; and - the cooler purge is activated when the water mass estimate is greater than the threshold value by generating oscillations of the intake air flow entering the exchanger between a nominal flow value and a flow value increased and oscillations of the ignition advance between a nominal advance value and a degraded advance value.

[0021] These variations in intake air flow make it possible to force the detachment of the water accumulated on the walls of the cooler, while maintaining a stable engine torque around the torque setpoint.

[0022] The heat exchanger may be a cold water charge air cooler, or Water Charge Air Cooler (W-CAC) in Anglo-Saxon terms, or an air-to-air cooler, called Charge Air Cooler (CAC) in Anglo-Saxon terms.

[0023] Advantageously, the oscillations of the intake air flow are achieved by controlling the opening of the control valve or throttle body by making slots between a nominal position of an engine operating point and an increased opening position, i.e. an additional opening, greater than the nominal position. In one possible embodiment, the increased opening position may be the maximum opening position, i.e. the fully open position, of the throttle body.

[0024] Advantageously, the generation of oscillations of the intake air flow entering the exchanger and the generation of oscillations of the ignition advance are carried out simultaneously.

[0025] For example, the oscillations or variations in the intake air flow rate form oscillating slots between the nominal flow rate value and the increased flow rate value and the generation of the oscillations in the ignition advance forms oscillating slots between the degraded advance value and the nominal advance value, the nominal value of the ignition advance corresponding to the nominal position of the intake air flow rate and in particular of the adjustment valve or throttle body. The degraded advance value corresponds to an advance value lower than that of the nominal advance value, which degrades the combustion efficiency.

[0026] The slots have, for example, an identical time period between the rising and falling phases, for example between 1s and 2s, for example equal to 1.5s.

[0027] Advantageously, the purge step has a duration necessary to evacuate the water from the cooler of between 8 s and 12 s, for example equal to 10 s.

[0028] According to a second aspect, the invention relates to an electronic control unit for a spark-ignition internal combustion engine comprising at least one cylinder, a fresh air intake manifold supplied with fresh air via a pipe, a compressor of a turbocharger and a heat exchanger downstream of said compressor and upstream of the intake manifold, the engine further comprising an exhaust circuit comprising, from upstream to downstream in the direction of circulation of the burnt gases, an exhaust manifold, a turbine of the turbocharger and, for example, a system for depolluting the combustion gases of the engine.

[0029] The engine further comprises a circuit for partial recirculation of the exhaust gases to the intake originating at a point in the exhaust circuit, downstream of said turbine, and opening into the fresh air supply pipe, upstream of the turbocharger compressor, said intake circuit comprising a control valve or throttle body mounted between the compressor and the heat exchanger.

[0030] The electronic control unit comprises an engine control system comprising: - a module for estimating the mass of liquid water stored in real time on the internal walls of the exchanger; - a module for comparing the water mass estimate with a threshold value; and - a module for activating the cooler purge when the estimate of the water mass is greater than the threshold value configured to generate oscillations of the intake air flow entering the exchanger between a nominal flow value and an increased flow value and oscillations of the ignition advance between a nominal advance value and a degraded advance value.

[0031] Advantageously, the cooler purge activation module comprises a module for controlling the adjustment valve or throttle body by performing slots between a nominal position of an engine operating point and an additional opening position.

[0032] Advantageously, the cooler purge activation module comprises an ignition advance modulation module configured to modulate the ignition advance between the nominal advance value and a degraded advance value.

[0033] According to another aspect, the invention relates to a motor vehicle comprising an electronic control unit as described above.

[0034] Other aims, characteristics and advantages of the invention will appear on reading the following description, given solely by way of non-limiting example, and made with reference to the appended drawings in which:

[0035] [Fig.l] represents, in a very schematic manner, an example of the structure of an internal combustion engine of a motor vehicle comprising a control unit comprising a control system according to the invention;

[0036] [Fig.2] illustrates square wave curves of the control signals from the control system according to [Fig.l]; and

[0037] [Fig.3] represents the block diagram of a control method according to the invention implemented by the control unit of [Fig.l].

[0038] In [Fig.l], the general structure of an internal combustion engine 10, of the spark-ignition type operating in particular on gasoline, of a motor vehicle is shown schematically. Alternatively, it may be an engine operating on alcohol or liquefied gas such as LPG.

[0039] These architectures are given by way of example and do not limit the invention to the sole configuration to which the control of the motor according to the invention can be applied.

[0040] In the illustrated example, the internal combustion engine 10 comprises, in a non-limiting manner, three cylinders 12 in line, a fresh air intake manifold 14, an exhaust manifold 16 and a turbo-compression system 18.

[0041] The cylinders 12 are supplied with air via the intake manifold 14, or intake distributor, itself supplied by a pipe 20 provided with an air filter 22 and the compressor 18b of the turbocharger 18 of the engine 10.

[0042] Each cylinder 12 is supplied with fuel, for example gasoline type.

[0043] In a known manner, the turbocharger 18 essentially comprises a turbine 18a driven by the exhaust gases and a compressor 18b mounted on the same axis or shaft as the turbine 18a and providing compression of the air distributed by the air filter 22, with the aim of increasing the quantity (mass flow rate) of air admitted into the cylinders 12 of the engine 10. The turbine 18a may be of the “variable geometry” type, that is to say that the turbine wheel is equipped with blades with variable inclination in order to modulate the quantity of energy taken from the exhaust gases, and thus the boost pressure.

[0044] A heat exchanger 26 is placed after the outlet of the compressor 18b equipping the supply line 14a of the intake manifold 14 with fresh air.

[0045] The internal combustion engine 10 thus comprises an intake circuit Ca, an exhaust circuit Ce and a fuel injection circuit (not shown).

[0046] The intake circuit Ca comprises, from upstream to downstream in the direction of air circulation:

[0047] - the air filter 22 or air box;

[0048] - the compressor 18b of the turbocharger 18 configured to compress the bleed air in the external atmosphere and where appropriate low pressure recycled exhaust gases, as will be described later;

[0049] - a throttle body 24 or a gas intake valve in the engine;

[0050] - the heat exchanger 26 configured to cool the intake gases cor corresponding to a mixture of fresh air and recycled gases, after their compression in the compressor 18b; and

[0051] - the intake manifold 14.

[0052] The heat exchanger 26 is a cooler of the so-called intake gases "supercharged", corresponding, here, to an air-water exchanger, called "water charged air cooler" in Anglo-Saxon terms. The terms "heat exchanger 26" and “charge air cooler 26” hereinafter designates the same element. Alternatively, it may be an air-to-air cooler.

[0053] The intake circuit Ca may also comprise a flow meter (not shown) arranged in the intake duct 20 downstream of the air filter 22; the flow meter being configured to measure the actual value of the air flow entering the engine 10. The flow meter only measures the flow of fresh air alone.

[0054] The exhaust circuit Ce comprises, from upstream to downstream in the direction of circulation of the burnt gases:

[0055] - the exhaust manifold 16;

[0056] - the turbine 18a of the turbocharger 18 configured to take energy from the exhaust gases passing through it, said expansion energy being transmitted to the compressor 18b via the common shaft, for the compression of the intake gases;

[0057] - a system 40 for depolluting the combustion gases of the engine.

[0058] As regards the exhaust manifold 16, the latter recovers the exhaust gases resulting from the combustion and evacuates them to the outside, via a gas exhaust duct 28 opening onto the turbine 18a of the turbocharger 18 and via an exhaust line 30 mounted downstream of said turbine 18a.

[0059] By way of non-limiting example, the system 40 for depolluting the combustion gases of the engine comprises a first device 42 comprising a three-way catalyst.

[0060] The gas depollution system 40 further comprises a second device 55 which is here a fine particle filter, and an exhaust pipe 32 mounted at the outlet of the second depollution device 55 and opening outwards.

[0061] As illustrated, the engine 10 comprises a partial recirculation circuit 50 of the exhaust gases to the intake, called the “EGR” circuit (“exhaust gas recirculation” in English terms).

[0062] This circuit 50, here a low-pressure exhaust gas recirculation circuit, called “EGR BP”, originates at a point on the exhaust line 30, here, in the exhaust pipe 32, downstream of said turbine 18a, and in particular, in the case of [Fig.l], downstream of the gas depollution system 40 and returns the exhaust gases to a point on the fresh air supply pipe 20, upstream of the compressor 18b of the turbocharger 18, in particular downstream of the air filter 22.

[0063] In a variant not shown, the low-pressure exhaust gas recirculation circuit could originate at the outlet of the turbine 18a, or even in downstream of only part of the gas decontamination system 40, for example between the first and second decontamination devices 42,55.

[0064] As illustrated, this recirculation circuit 50 comprises, in the direction of circulation of the recycled gases, a “V EGR BP” adjustment valve 52 configured to regulate the flow rate of the low-pressure exhaust gases and a cooler 54 of the EGR gases. The “V EGR BP” valve 52 is arranged upstream of the cooler 54 and said cooler 54 is arranged upstream of the compressor 18b.

[0065] By way of non-limiting example, the engine is associated with a fuel circuit comprising, for example, fuel injectors (not referenced) injecting gasoline directly into each cylinder from a fuel tank (not shown).

[0066] The engine comprises an electronic control unit ECU 60 comprising a control system 70 configured to control the various elements of the internal combustion engine and in particular the throttle body 24 and the ignition advance.

[0067] The control system 70 receives data collected by sensors at different locations of the engine or estimated.

[0068] The control system 70 could receive other data, such as temperatures at different locations in the engine, or other pressures.

[0069] The control system 70 comprises a module 71 for estimating the mass M_eau of liquid water stored in real time on the internal walls of the exchanger 26.

[0070] The estimation of the mass M_water of liquid water stored in real time on the internal walls of the exchanger 26 can be carried out for example as a function of the temperature of the fresh air admitted, of the air flow rate obtained by the flow meter, and of an estimation of the ambient relative humidity, either through a hygrometry rate sensor arranged in the intake circuit Ca, for example in the flow meter, or outside the vehicle, or by a meteorological service in particular if the vehicle is a so-called “connected” vehicle, or by the method described in patent FR 3 064 678 - B1.

[0071] The control system 70 comprises a module 72 for comparing the estimate of the mass of water M_eau with a threshold value S.

[0072] The threshold value S may correspond to a maximum mass of liquid water storable in the exchanger 26.

[0073] In order to determine the threshold value S, it is possible, for example, to weigh the exchanger 26 in the dry state, to completely fill with water the volume usually traveled by the mixture of air and EGR gas, to install, on a test bench, said exchanger 26 and to blow through it with a constant air flow until the mechanical evacuation of the water it contains, without waiting for the evaporation of the water. Then, the exchanger is weighed 26 to estimate the mass of water it has retained. This mass corresponds to the threshold value S of storable liquid water, for the constant air flow considered.

[0074] Alternatively, the threshold value S could correspond to a critical mass of water corresponding to the mass of water which poses the risk of combustion extinction if a desorption phenomenon were to occur, for example in the event of a sharp increase in the air flow admitted by the engine, following an acceleration request, for example.

[0075] The critical mass of water can be estimated by testing, on a stationary engine test bench, by injecting an increasing mass of liquid water into the cylinder intake and by measuring the internal combustion pressure which makes it possible to estimate the indicated torque produced. Then, the maximum permissible mass of liquid water per combustion cycle and per cylinder, corresponding to a combustion defect, is deduced.

[0076] The critical water mass for the engine can then be deduced by knowing the dynamics of the engine, i.e. the duration, and therefore the number of combustion cycles which are necessary to reach a critical stage for the engine.

[0077] The control system 70 comprises a module 74 for activating the purge of the cooler 26 when the estimate of the mass of water M_water is greater than the threshold value S.

[0078] The purge activation module 74 comprises a module 76 for controlling the throttle body 24 configured to generate variations in the intake air flow rate between a nominal flow rate value Qaf_nom and an increased flow rate value Qaf_+. In one embodiment, said increased flow rate value may be equal to the maximum flow rate value of the engine corresponding to the fully open position of the throttle body. More generally, it is a flow rate value which is greater than the nominal flow rate value.

[0079] These variations in the intake air flow make it possible to force the detachment of the water accumulated on the walls of the cooler 26.

[0080] These variations in intake air flow are obtained by performing slots on the opening of the throttle body 24 between a nominal position %BP_nom of the engine operating point concerned and an additional opening position %BP_+.

[0081] The purge activation module 74 further comprises an ignition advance modulation module 78 configured to modulate the ignition advance between a nominal advance value AV_nom and a degraded advance value AV_-. By "degraded advance" is meant an advance value which is lower than the nominal advance value, and which results in a degradation of the combustion efficiency.

[0082] The values ​​of the air flow Qaf and the ignition advance AV come from an engine computer (not shown) integrated in PUCE comprising air flow / ignition advance pairs for a speed / load operating point of the engine.

[0083] Modulating the ignition advance makes it possible to maintain the engine torque at a constant level equal to the engine torque requested by the driver when pressing the accelerator pedal.

[0084] Indeed, starting from an optimal operation, corresponding to the nominal flow rate Qaf_nom and the nominal advance Av_nom (generally corresponding to the optimal advance or to a value close to the optimal advance), and by increasing the air flow rate while maintaining normal operation of the spark-ignition engine at richness equal to 1, an undesired surplus engine torque would be obtained if the advance were not degraded, because there would be a greater air-fuel mixture flow rate and an identical combustion efficiency. A controlled degradation of the advance here makes it possible to degrade the combustion efficiency in such a way that the same engine torque is obtained as that which was obtained with the nominal air flow rate and the nominal advance.

[0085] [Fig.2] represents notched curves respectively of the air flow Qaf passing through the cooler 26, of the ignition advance AV, of the engine torque C and of the percentage of opening of the throttle body %BP, as a function of time in seconds.

[0086] As can be seen in [Fig.2], the variations in intake air flow rate form oscillating slots between the nominal flow rate value Qaf_nom and the increased flow rate value Qaf_+ and the modulation of the ignition advance forms oscillating slots between the degraded advance value AV_- and the nominal advance value AV_nom, the nominal position of the ignition advance corresponding to the nominal position of the throttle body 24 and the intake air flow rate.

[0087] The slots preferably have an identical time period r between the rising and falling phases, for example between 1s and 2s, for example equal to 1.5s.

[0088] For example, the duration of the purge phase necessary to evacuate the water from the cooler 26 is between 8s and 12s, for example equal to 10s.

[0089] As illustrated in detail in [Fig.3], the method 100 for controlling the engine comprises a step 102 of estimating the mass M_eau of liquid water stored in real time on the internal walls of the exchanger 26.

[0090] The method 100 for controlling the engine further comprises a step 104 of comparing the estimate of the mass of water M_water with a threshold value S.

[0091] The engine control method 100 further comprises a step 110 of activating the purging of the cooler 26 when the estimation of the mass of water M_water is greater than the threshold value S.

[0092] Step 110 of activating the purge of the cooler 26 comprises a step 112 of controlling the throttle body 24 during which the opening of the throttle body is generated by performing slots between a nominal position %BP_nom of the point of engine operation concerned and an additional opening position %BP_+, in order to generate variations in the intake air flow between a nominal flow value Qaf_nom and an increased flow value Qaf_+.

[0093] Step 110 of activating the purge of the cooler 26 further comprises a step 114 of modulating the ignition advance configured to modulate the ignition advance between a nominal advance value AV_nom and a degraded advance value AV_-.

[0094] As explained previously, the modulation of the ignition advance makes it possible to maintain the engine torque at a constant level equal to the engine torque requested by the driver when pressing the accelerator pedal.

[0095] Step 112 of controlling the throttle body 24 and step 114 of modulating the ignition advance are carried out simultaneously.

[0096] Thanks to the invention, it is possible to purge the air cooler in order to avoid any risk of rapid desorption and extinction of the engine combustion, while maintaining a torque generated by the engine constant around a target value.

Claims

Claims

1. Method (100) for controlling a spark-ignition internal combustion engine (10) comprising at least one cylinder (12), a fresh air intake manifold (14) supplied with fresh air by a pipe (20), a compressor (18b), a turbocharger (18) and a heat exchanger (26) downstream of said compressor (18b) and upstream of the intake manifold (14), the engine further comprising an exhaust circuit (Ce) comprising, from upstream to downstream in the direction of circulation of the burnt gases, an exhaust manifold (16), a turbine (18a) of the turbocharger (18), and a partial recirculation circuit (50) of the exhaust gases at the intake originating at a point in the exhaust circuit (Ce), downstream of said turbine (18a), and opening into the fresh air supply pipe (20), upstream of the compressor (18b) of the turbocharger (18),said intake circuit (Ca) comprising a control valve (24) mounted between the compressor (18b) and the heat exchanger (26), in which: - the mass (M_eau) of liquid water stored in real time on internal walls of the exchanger (26) is estimated; - said estimated mass (M_eau) is compared with a threshold value (S); and - the purge of the cooler (26) is activated when the estimation of the mass of water (M_eau) is greater than the threshold value (S), by generating oscillations of the intake air flow rate (Qaf) entering the exchanger (26) between a nominal flow rate value (Qaf_nom) and an increased flow rate value (Qaf_+) and oscillations of the ignition advance (AV) between a nominal advance value (AV_nom) and a degraded advance value (AV_-).,

2. Method according to claim 1, in which the oscillations of the intake air flow (Qaf) are carried out by controlling the opening of the adjustment valve (24) by making slots between a nominal position (%BP_nom) of an engine operating point and an additional opening position (%BP_+).

3. Method according to claim 1 or 2, in which the generation of the oscillations of the intake air flow (Qaf) entering the exchanger (26) and the generation of the oscillations of the ignition advance (AV) are carried out simultaneously.

4. A method according to any preceding claim, in in which the intake air flow oscillations form oscillating slots between the nominal flow value (Qaf_nom) and the increased flow value (Qaf_+) and the generation of the ignition advance oscillations forms oscillating slots between the degraded advance value (AV_-) and the nominal advance value (AV_nom), the nominal value of the ignition advance corresponding to the nominal position of the intake air flow (Qaf_nom) and in particular of the adjustment valve or throttle body (24).

5. Method according to claim 4, in which the slots have an identical time period (r) between the rising and falling phases, for example between 1s and 2s, for example equal to 1.5s.

6. Method according to claim 4 or 5, in which the purging step has a duration (ø) necessary to evacuate the water from the cooler (26) of between 8s and 12s, preferably equal to 10s.

7. Electronic control unit (ECU) of a spark-ignition internal combustion engine (10) comprising at least one cylinder (12), a fresh air intake manifold (14) supplied with fresh air by a pipe (20), a compressor (18b), a turbocharger (18) and a heat exchanger (26) downstream of said compressor (18b) and upstream of the intake manifold (14), the engine further comprising an exhaust circuit (Ce) comprising, from upstream to downstream in the direction of circulation of the burnt gases, an exhaust manifold (16), a turbine (18a) of the turbocharger (18), and a partial recirculation circuit (50) of the exhaust gases at the intake originating at a point in the exhaust circuit (Ce), downstream of said turbine (18a), and opening into the fresh air supply pipe (20), upstream of the compressor (18b) of the turbocharger (18),said intake circuit (Ca) comprising a control valve (24) mounted between the compressor (18b) and the heat exchanger (26), the electronic control unit (ECU) comprising an engine control system (70) comprising: - a module (71) for estimating the mass (M_eau) of liquid water stored in real time on internal walls of the exchanger (26); - a module (72) for comparing the estimation of the mass of water (M_eau) with a threshold value (S); and - a module (74) for activating the purge of the cooler (26) when the estimation of the mass of water (M_eau) is greater than the threshold value (S) configured to generate oscillations of the air flow, intake (Qaf) entering the exchanger (26) between a nominal flow rate value (Qaf_nom) and an increased flow rate value (Qaf_+) and oscillations of the ignition advance (AV) between a nominal advance value (AV_nom) and a degraded advance value (AV_-).

8. Electronic control unit (ECU) according to claim 7, wherein the module (74) for activating the purge of the cooler (26) comprises a module (76) for controlling the adjustment valve (24) by performing slots between a nominal position (%BP_nom) of an engine operating point and an additional opening position (%BP_+).

9. Electronic control unit (ECU) according to claim 7 or 8, wherein the module (74) for activating the purge of the cooler (26) comprises an ignition advance modulation module (78) configured to modulate the ignition advance between the nominal advance value (AV_nom) and a degraded advance value (AV_-).

10. A motor vehicle comprising an electronic control unit according to any one of claims 7 to 9.

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