Method and system for verifying the conditions necessary for carrying out a diagnosis of an internal combustion engine of a motor vehicle with hybrid transmission

Abstract

Method (100) for verifying the conditions necessary for carrying out at least one diagnosis of the gas flow rates of an air circuit of an internal combustion engine (10) of a vehicle with hybrid transmission, in which the engine comprises at least three cylinders (12) in line, a fresh air intake manifold (14) supplied with fresh air by a pipe (20) provided with a flow meter (26) and an exhaust manifold (16), in which: - at least two conditions (C1, C2) necessary for carrying out a diagnosis of the gas flow rates of the air circuit of the heat engine (10) are observed by comparing each of said conditions (C1, C2) with a first threshold value (S1_C1, S1_C2) and with a second threshold value (S2_C1, S2_C2); and we check whether an engine intrusion is necessary to perform the diagnosis by comparing an average feasibility value (V_feasibility_avg) with a third threshold value (S3). Figure for the abstract: Fig 2

Description

Title of the invention: Method and system for verifying the conditions necessary for carrying out a diagnosis of an internal combustion engine of a motor vehicle with hybrid transmission

[0001] The present invention relates to the field of hybrid transmissions for motor vehicles, comprising on the one hand a thermal drive engine, and on the other hand at least one electric machine.

[0002] More particularly, the invention relates to carrying out diagnostics of the internal combustion engine of the motor vehicle with hybrid transmission.

[0003] Current standards require diagnostics to be carried out on internal combustion engines, and in particular diagnostics of different gas flow rates in the air circuit of the thermal engine.

[0004] Among the required diagnostics, we know the diagnosis of the flow rate of the exhaust gases recycled to the intake (EGR gas, from the English acronym for: Exhaust Gas Recirculation) which is carried out by comparison between the estimated EGR gas flow rate and the requested EGR gas flow rate (set flow rate).

[0005] The estimation of the EGR gas flow rate can be determined by calculating the difference between, on the one hand, the total flow rate sucked in by the engine, which is determined using a so-called "filling" model as a function of the pressure and temperature in the intake manifold, and the engine speed, and, on the other hand, the air flow rate plus fuel vapors determined using a Barré Saint-Venant equation at the terminals of the intake valve 28 using the differential pressure at the terminals of said valve and the temperature downstream of said valve.

[0006] Among the required diagnostics, we also know the diagnosis of the engine air flow meter, carried out by comparing the flow rate of the flow meter measured directly at the engine inlet with an air flow rate estimated by the so-called "filling" model with or without EGR.

[0007] Finally, among the required diagnostics, we also know the diagnosis of the fuel vapor purge flow rate carried out by comparing the difference between the flow rate estimated by the flow meter 26 and the so-called “filling” model. The difference is then compared to the fuel vapor purge flow rate determined by a map.

[0008] However, to carry out such diagnostics, the heat engine must operate for a relatively long period, without stopping, scanning several operating points and thus guaranteeing a certain robustness in detecting a failure of the heat engine.

[0009] However, the use of the thermal engine in hybrid transmission vehicles is different from that of the thermal engine in pure thermal transmission vehicles.

[0010] Indeed, in vehicles with hybrid transmission, the thermal engine is less used since the electric machine provides the vehicle's drive. Furthermore, the thermal engine is generally used at specific operating points and its use is generally jerky.

[0011] Such use of the thermal engine in vehicles with hybrid transmission does not make it easy to carry out the required diagnostics on the gas flow rates of the air circuit of the thermal engine.

[0012] It is known to intrusively force the operation of the thermal engine over a long period in order to carry out these diagnostics.

[0013] In other words, regardless of the driving carried out by the driver, the thermal engine is forced onto operating points on which diagnostics can be carried out.

[0014] Generally, the electric machine is used to compensate for the difference between the vehicle's drive torque setpoint which comes from a request from the driver via the pressing of the accelerator pedal and the torque already provided by the thermal engine and the speed of the thermal engine is forced, either by adjusting the drive ratio between the thermal engine and the wheels, or by disconnecting the thermal engine from the traction chain.

[0015] However, such use of the thermal engine is not optimized according to the vehicle's driving conditions and generates excess fuel consumption, going against environmental constraints.

[0016] There is a need to determine whether such diagnostics of the thermal engine can be carried out under the conditions required by the standards in force, without systematically forcing the operation of the thermal engine.

[0017] The subject of the present invention is a method for verifying the conditions necessary for carrying out at least one diagnosis of the gas flow rates of an air circuit of an internal combustion engine of a vehicle with hybrid transmission, in which the engine comprises at least three in-line cylinders, a fresh air intake manifold supplied with fresh air by a pipe provided with a flow meter and an exhaust manifold.

[0018] According to the method, at least two conditions are observed which are necessary for carrying out a diagnosis of the gas flow rates of the air circuit of the heat engine by comparing each of said conditions with a first threshold value and with a second threshold value.

[0019] According to the method, a feasibility value equal to one is then determined when the condition is greater than the first corresponding threshold value and a feasibility value equal to zero is determined when the condition is less than or equal to the second corresponding threshold value.

[0020] A feasibility value of 1 corresponds to the case where the condition to be met is close to the target value of said condition to carry out the diagnosis and a feasibility value of 0 corresponds to the case where the condition to be met is far from the target value of said condition to carry out the diagnosis.

[0021] According to the method, the concatenation of said determined feasibility values ​​is carried out to extract a minimum feasibility value therefrom and an average feasibility value is determined by calculating the sliding average of the minimum feasibility value.

[0022] It is then checked whether an intrusion of the engine is necessary to carry out the diagnosis by comparing the average feasibility value with a third threshold value and an intrusion instruction is transmitted to a thermal engine management system to carry out the diagnosis if the average feasibility value is lower than the third threshold value.

[0023] Thanks to the invention, it is possible to verify that all the required conditions are present to carry out the gas flow diagnostics of the heat engine by limiting the number of intrusions on the heat engine.

[0024] Advantageously, the two conditions observed include at least the stability of the air flow rate and the air flow rate level to ensure that the air flow rate is greater than a minimum value for a sufficient duration to ensure that all of the measured flow rates allow the diagnosis to be established.

[0025] For example, when the observed condition is lower than the first corresponding threshold value and higher than the second corresponding threshold value, a feasibility value is determined according to the following equation: [Math 1] V _feasibility = ( y-— )

[0026] For example, the moving average of the minimum feasibility value is calculated according to the following equation: [Math 2] V feasibility average = A Ï^VHiin, t ' N' number * of calculation On which the sliding average is carried out.

[0027] Advantageously, the third threshold value for triggering the emission of an intrusion instruction is a function of the speed of the vehicle in order to promote intrusions of the thermal engine when the vehicle is traveling at high speed and thus mask the ignition of the thermal engine by the nuisances linked to the air flow.

[0028] Advantageously, when determining an average feasibility value, the feasibility value is reset to 1 when the diagnosis is carried out by a diagnosis carrying out system.

[0029] According to one embodiment, the internal combustion engine comprises at least one circuit for partial recirculation of the exhaust gases to the intake, called the “EGR” circuit (“exhaust gas recirculation” in English terms). According to the method, when observing the two conditions necessary for carrying out a diagnosis of the gas flow rates of the air circuit of the thermal engine, the stability of the EGR flow rate and / or the EGR flow rate is also observed to ensure that the EGR flow rate is greater than a minimum value for a sufficient duration.

[0030] According to a second aspect, the invention relates to a system for verifying the conditions necessary for carrying out at least one diagnosis of the gas flow rates of an air circuit of an internal combustion engine of a vehicle with hybrid transmission, in which the engine comprises at least three in-line cylinders, a fresh air intake manifold supplied with fresh air by a pipe provided with a flow meter and an exhaust manifold.

[0031] The verification system comprises: - a module for observing at least two conditions necessary to carry out a diagnosis of the gas flow rates of the air circuit of the heat engine, configured to compare each of said conditions with a first threshold value and with a second threshold value. Said module is configured to determine a feasibility value equal to one when the condition is greater than the corresponding first threshold value and to determine a feasibility value equal to zero when the condition is less than or equal to the corresponding second threshold value.

[0032] The verification system further comprises a module configured to concatenate said determined feasibility values ​​to extract therefrom a minimum feasibility value, a module configured to determine an average feasibility value capable of calculating the sliding average of the minimum feasibility value and a module for verifying whether an intrusion of the engine is necessary to carry out the diagnosis configured to compare the average feasibility value with a third threshold value, and to transmit an intrusion instruction to a thermal engine management system to carry out the diagnosis when the average feasibility value is lower than the third threshold value.

[0033] According to another aspect, the invention relates to an electronic control unit for an internal combustion engine comprising at least three in-line cylinders, a fresh air intake manifold supplied with fresh air by a pipe provided with a flow meter and an exhaust manifold, the electronic control unit comprising a system for carrying out at least one diagnosis of the gas flow rates of the air circuit of the heat engine and a system for verifying the conditions necessary for carrying out at least one diagnosis of the gas flow rates of the air circuit of the heat engine as described previously.

[0034] According to another aspect, the invention relates to a motor vehicle comprising an electronic control unit as described above.

[0035] 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:

[0036] [Fig.l] represents, in a very schematic manner, an example of the structure of an internal combustion engine of a motor vehicle with hybrid transmission comprising a control unit comprising a system for verifying the conditions necessary for carrying out a diagnosis according to the invention; and

[0037] [Fig.2] represents the synopsis of a method for verifying the conditions necessary for carrying out a diagnosis 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, in particular of the spark-ignition type running on gasoline, of a motor vehicle is shown schematically.

[0039] These architectures are given by way of example and do not limit the invention to the sole configuration to which the detection of a fuel vapor leak 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 powered by fuel, of the 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 24 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 and an exhaust circuit Ce.

[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] - the heat exchanger 24 configured to cool the intake gases cor corresponding to a mixture of fresh air and recycled gases, after their compression in the compressor 18b;

[0050] - an adjustment valve 28 arranged in the supply line 14a of the manifold intake 14, downstream of the heat exchanger 24 and upstream of the intake manifold 14, said valve 28 being configured to adjust the flow rate of air and low-pressure recycled gases entering the cylinders 12; and

[0051] - the intake manifold 14.

[0052] The exhaust circuit Ce comprises, from upstream to downstream in the direction of circulation of the burnt gases:

[0053] - the exhaust manifold 16;

[0054] - 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;

[0055] - a system 40 for depolluting the combustion gases of the engine.

[0056] 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 30 opening onto the turbine 18a of the turbocharger 18 and via an exhaust line 32 mounted downstream of said turbine 18a.

[0057] In a non-limiting manner, the engine 10 comprises a partial recirculation circuit 38 of the exhaust gases at the intake, called the “EGR” circuit (“exhaust gas recirculation” in English terms).

[0058] This circuit 38, here a low-pressure exhaust gas recirculation circuit, called “EGR BP”, originates at a point on the exhaust line 36, downstream of said turbine 18a, and in particular 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 flow meter 26. The flow meter 26 only measures the flow of fresh air alone.

[0059] As illustrated, this recirculation circuit 38 comprises, in the direction of circulation of the recycled gases, a cooler 38a, a filter 38b, and a “V EGR BP” valve 38c configured to regulate the flow rate of the low-pressure exhaust gases. The “V EGR BP” valve 38c is arranged downstream of the cooler 38a and upstream of the compressor 18b.

[0060] By way of non-limiting example, the system 40 for depolluting the combustion gases of the engine comprises a first device 42 comprising two three-way catalysts 42a, 42b in series, electrically heated.

[0061] The gas depollution system 40 further comprises a second device 44 which is here a fine particle filter, and a third device 46 which is here a three-way catalyst. It may also comprise a third oxygen probe (not shown), for example of the binary type, mounted downstream of the second device 44, for example for diagnostic purposes.

[0062] 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 50.

[0063] The engine also comprises a fuel vapor purge circuit 60 comprising a canister 62 or fuel vapor reservoir 62 receiving fuel vapors from the fuel tank 50 via a first pipe 60a, an active pump 64 connected via a second pipe 60b downstream of the canister 62 and a purge solenoid valve 66 connected via a third pipe 60c downstream of the pump 64. The purge solenoid valve 66 is connected to the engine intake, downstream of the flow meter 26 via a fourth pipe 60d.

[0064] The engine comprises an electronic control unit 70 configured to control the various elements of the internal combustion engine and in particular the engine speed.

[0065] The electronic control unit 70 could receive other data, such as temperatures at different locations in the engine, or other pressures.

[0066] The electronic control unit 70 comprises a system 80 for verifying the conditions necessary for carrying out one or more diagnoses of the gas flow rates of the air circuit of the heat engine 10.

[0067] The electronic control unit 70 further comprises a system 90 for carrying out diagnostics of the gas flow rates of the air circuit of the heat engine 10 when the system 80 for verifying the necessary conditions transmits a setpoint of conditions met.

[0068] The system 90 for carrying out diagnostics of the gas flow rates of the air circuit of the heat engine 10 is known per se and will not be described further.

[0069] As illustrated, the system 80 for verifying the conditions necessary for the rea- The method for carrying out one or more diagnostics of the gas flow rates of the air circuit of the heat engine 10 comprises a module 82 for observing at least two conditions C1, C2 necessary for carrying out a diagnosis of the gas flow rates of the air circuit of the heat engine 10.

[0070] The module 82 for observing at least two conditions Cl, C2 compares each of the necessary conditions Cl, C2 respectively with a first threshold value S1_C1, S1_C2 and with a second threshold value S2_C1, S2_C2.

[0071] When the condition Cl, C2 is greater than the corresponding first threshold value S1_C1, S1_C2, the observation module 82 assigns a feasibility value V_feasibility of 1. Conversely, when the condition Cl, C2 is less than or equal to the corresponding second threshold value S2_C1, S2_C2, the observation module 82 assigns a feasibility value V_feasibility of 0.

[0072] A feasibility value of 1 corresponds to the case where the condition to be met is close to the target value of said condition to carry out the diagnosis.

[0073] A feasibility value of 0 corresponds to the case where the condition to be met is far from the target value of said condition to carry out the diagnosis.

[0074] When the condition Cl, C2 is lower than the corresponding first threshold value S1_C1, S1_C2 and higher than the corresponding second threshold value S2_C1, S2_C2, the observation module 82 determines a feasibility value V_feasibility according to the following equation:

[0075] [Math.l] V __ feasibility = (7^ )

[0076] With:

[0077] C, the observed condition.

[0078] The two conditions C1, C2 observed by the observation module 82 include at least the stability of the air flow rate and the air flow rate level to ensure that the air flow rate is greater than a minimum value for a sufficient duration to guarantee that all of the measured flow rates allow the diagnosis to be established.

[0079] The observation module 82 could also observe other conditions, such as the stability of the EGR flow rate and / or the EGR flow rate to ensure that the EGR flow rate is above a minimum value for a sufficient duration.

[0080] The system 80 for verifying the necessary conditions comprises a module 84 configured to concatenate all the feasibility values ​​and to extract therefrom a minimum feasibility value Vmin.

[0081] The system 80 for verifying the necessary conditions further comprises a module 86 for determining an average feasibility value V_feasibility_avg according to the following equation:

[0082] [Math.2] V_feasibility_avg = ^^Vminn^k

[0083] With:

[0084] N, the number of calculation steps over which the sliding average is carried out, or alternatively the number of kilometers traveled by the vehicle. In other words, it may be a time average over a given duration or alternatively a kilometer average over a given distance.

[0085] The system 80 for verifying the necessary conditions further comprises an intrusion management module 88 configured to compare the average feasibility value V_feasibility_moy with a third threshold value S3 and to transmit an intrusion instruction C_intr to the thermal engine management system to carry out the diagnosis if the average feasibility value V_feasibility_moy is lower than the third threshold value S3.

[0086] For example, the third threshold value S3 for triggering the emission of an intrusion instruction C_intr is a function of the speed of the vehicle, in order to promote intrusions of the thermal engine when the vehicle is traveling at high speed and thus mask the ignition of the thermal engine by the nuisances linked to the air flow.

[0087] For example, the module 86 for determining an average feasibility value V_feasibility_moy could receive a feasibility value equal to 1 when the diagnosis is carried out by the system 90 for carrying out diagnoses, in order to limit intrusions on the thermal engine.

[0088] As illustrated in [Fig.2], a method 100 for verifying the conditions necessary for carrying out one or more diagnoses of the gas flow rates of the air circuit of the heat engine 10 comprises a first step 101 of observing at least two conditions C1, C2 necessary for carrying out a diagnosis of the gas flow rates of the air circuit of the heat engine 10.

[0089] As illustrated, the first observation step 101 compares, in step 102, a first condition Cl with a first threshold value S1_C1 and with a second threshold value S2_C1.

[0090] Simultaneously with step 102, the method 100 compares, in step 104, a second condition C2 with a first threshold value S1_C2 and with a second threshold value S2_C2.

[0091] When the condition Cl, C2 is greater than the first corresponding threshold value S1_C1, S1_C2, a feasibility value V_feasibility of 1 is assigned. Conversely, when the condition Cl, C2 is less than or equal to the second corresponding threshold value S2_C1, S2_C2, a feasibility value V_feasibility of 0 is assigned.

[0092] A feasibility value of 1 corresponds to the case where the condition to be met is close to the target value of said condition to carry out the diagnosis.

[0093] A feasibility value of 0 corresponds to the case where the condition to be met is far from the target value of said condition to carry out the diagnosis.

[0094] When the condition Cl, C2 is lower than the corresponding first threshold value S1_C1, S1_C2 and higher than the corresponding second threshold value S2_C1, S2_C2, a feasibility value V_feasibility is determined according to the following equation:

[0095] [Math.l] V -feasibility = ( )

[0096] With:

[0097] C, the observed condition.

[0098] The two conditions C1, C2 observed during the observation step 101 comprise at least the stability of the air flow rate and the air flow rate level to ensure that the air flow rate is greater than a minimum value for a sufficient duration to guarantee that all of the measured flow rates allow the diagnosis to be established.

[0099] During the observation step 101, other conditions could also be observed, such as the stability of the EGR flow rate and / or the EGR flow rate to ensure that the EGR flow rate is greater than a minimum value for a sufficient duration.

[0100] In a subsequent step 105, the concatenation of all the feasibility values ​​is carried out to extract a minimum feasibility value Vmin and, in step 106, an average feasibility value V_feasibility_moy is determined according to the following equation:

[0101] [Math.2] V-feasibility

[0102] With:

[0103] N, the number of calculation steps over which the sliding average (time or kilometer) is carried out.

[0104] It is then checked, in step 108, whether an intrusion of the engine is necessary to carry out the diagnosis. In step 108, the average feasibility value V_feasibility_moy is compared with a third threshold value S3 and an intrusion instruction C_intr is transmitted to the thermal engine management system to carry out the diagnosis if the average feasibility value V_feasibility_moy is lower than the third threshold value S3.

[0105] For example, the third threshold value S3 for triggering the emission of an intrusion instruction C_intr is a function of the speed of the vehicle, in order to promote the intrusions of the thermal engine when the vehicle is traveling at high speed and thus mask the ignition of the thermal engine by the nuisances linked to the air flow.

[0106] For example, when determining an average feasibility value V_feasibility_avg, the feasibility value could be reset to 1 when the diagnosis is performed by the diagnosis performance system 90.

[0107] Thanks to the invention, it is possible to verify that all the required conditions are present to carry out the gas flow diagnostics of the heat engine by limiting the number of intrusions on the heat engine.

Claims

Claims

1. Method (100) for verifying the conditions necessary for carrying out at least one diagnosis of the gas flow rates of an air circuit of an internal combustion engine (10) of a vehicle with hybrid transmission, in which the engine comprises at least three cylinders (12) in line, a fresh air intake manifold (14) supplied with fresh air by a pipe (20) provided with a flow meter (26) and an exhaust manifold (16), in which: - at least two conditions (Cl, C2) necessary for carrying out a diagnosis of the gas flow rates of the air circuit of the heat engine (10) are observed by comparing each of said conditions (Cl, C2) with a first threshold value (S1_C1, S1_C2) and with a second threshold value (S2_C1, S2_C2), said two conditions (Cl, C2) comprising at least the stability of the air flow rate and the level of air flow rate in the air circuit of the internal combustion engine (10); - a feasibility value (V_feasibility) equal to one is determined when the condition (Cl, C2) is greater than the corresponding first threshold value (S1_C1, S1_C2) and a feasibility value (V_feasibility) equal to zero is determined when the condition (Cl, C2) is less than or equal to the corresponding second threshold value (S2_C1, S2_C2), - the concatenation of said feasibility values ​​is carried out (V_feasibility) determined to extract a minimum feasibility value (Vmin), - an average feasibility value (V_feasibility_avg) is determined by calculating a moving average of the minimum feasibility value (Vmin), - we check whether an engine intrusion is necessary to carry out the diagnosis by comparing the average feasibility value (V_feasibility_average) with a third threshold value (S3) to trigger the emission of an intrusion instruction (C_intr) depending on the vehicle speed, and - an intrusion instruction (C_intr) is transmitted to a thermal engine management system (10) to carry out the diagnosis if the average feasibility value (V_feasibility_moy) is lower than the third threshold value (S3).

2. The method of claim 1, wherein when the condition (Cl, C2) is lower than the corresponding first threshold value (S1_C1, S1_C2) and higher than the corresponding second threshold value (S2_C1, S2_C2), a feasibility value (V_feasibility) is determined according to the following equation: [Math 1] V _ feasibility - )

3. Method according to any one of the preceding claims, in which the sliding average of the minimum feasibility value (Vmin) is calculated according to the following equation: [Math 2] V_feasibility_mean = £ Ë£vmin^ • with N-the ■x»*» of P“ of calculation on which the sliding average or the number of kilometers traveled by the vehicle is carried out.

4. Method according to any one of the preceding claims, wherein when determining an average feasibility value (V_feasibility_moy), the feasibility value is reset to 1 when the diagnosis is carried out by a system (90) for carrying out diagnoses.

5. Method according to any one of the preceding claims, in which the internal combustion engine (10) comprises at least one partial recirculation circuit (38) of the exhaust gases at the intake, and in which when observing the two conditions (Cl, C2) necessary to carry out a diagnosis of the gas flow rates of the air circuit of the thermal engine (10), the stability of the EGR flow rate and / or the EGR flow rate is also observed.

6. System (80) for verifying the conditions necessary for carrying out at least one diagnosis of the gas flow rates of an air circuit of an internal combustion engine (10) of a vehicle with hybrid transmission, in which the engine comprises at least three cylinders (12) in line, a fresh air intake manifold (14) supplied with fresh air by a pipe (20) provided with a flow meter (26) and an exhaust manifold (16), comprising: - a module (82) for observing at least two conditions (Cl, C2) necessary for carrying out a diagnosis of the gas flow rates of the air circuit of the heat engine (10) configured to compare each of said conditions (Cl, C2) with a first threshold value (S1_C1, S1_C2) and with a second threshold value (S2_C1, S2_C2); said two conditions (Cl, C2) comprising at least the stability of the air flow and the level of air flow in the air circuit of the internal combustion engine (10); said module (82) being configured to determine a feasibility value (V_feasibility) equal to one when the condition (Cl, C2) is greater than the corresponding first threshold value (S1_C1, S1_C2) and to determine a feasibility value (V_feasibility) equal to zero when the condition (Cl, C2) is less than or equal to the corresponding second threshold value (S2_C1, S2_C2), - a module (84) configured to concatenate said determined feasibility values ​​(V_feasibility) to extract therefrom a minimum feasibility value (Vmin), and - a module (86) configured to determine an average feasibility value (V_feasibility_moy) capable of calculating the sliding average of the minimum feasibility value (Vmin), and - a module (88) for checking whether an intrusion of the engine is necessary to carry out the diagnosis configured to compare the average feasibility value (V_feasibility_moy) with a third threshold value (S3) to trigger the emission of an intrusion instruction (C_intr) depending on the speed of the vehicle, and to transmit an intrusion instruction (C_intr) to a thermal engine management system (10) to carry out the diagnosis when the average feasibility value (V_feasibility_moy) is lower than the third threshold value (S3).

7. Electronic control unit (70) of an internal combustion engine (10) comprising at least three cylinders (12) in line, a fresh air intake manifold (14) supplied with fresh air by a pipe (20) provided with a flow meter (26) and an exhaust manifold (16, the electronic control unit (70) comprising a system (90) for carrying out at least one diagnosis of the gas flow rates of the air circuit of the heat engine (10) and a system (80) for verifying the conditions necessary for carrying out at least one diagnosis of the gas flow rates of the air circuit of the heat engine (10) according to claim 6.

8. Motor vehicle comprising an electronic control unit according to claim 7.

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