Method for increasing the torque of a heat engine, corresponding heat engine, and motor vehicle comprising such a heat engine

Abstract

This method for increasing the torque of a heat engine (4), comprising an air intake circuit (8) equipped with a compressor (14) configured to modify the mass flow rate of the heat engine's (4) intake air, includes at least the following steps: - a step (40) for determining a setpoint for increasing the downstream air pressure ( ) of the compressor; - a step (44) for decreasing the upstream air pressure ( ) of the compressor, performed independently of the compressor (14); and - a step (46) for increasing the compression ratio ( ) of the compressor (14) so ​​as to increase the downstream air pressure ( ) of the compressor according to said setpoint. Figure for the abbreviation: Fig 3

Description

Title of the invention: Method for increasing the torque of a heat engine, corresponding heat engine, and vehicle comprising such a heat engine technical field

[0001] The present invention relates technically to internal combustion engines, petrol or diesel, for motor vehicles.

[0002] In particular, the present invention relates to a method for increasing the torque of a heat engine, a heat engine comprising a computer configured to implement such a method, and a motor vehicle comprising such a heat engine. Previous techniques

[0003] A heat engine of a motor vehicle generally includes an air intake circuit, a fuel intake circuit, a plurality of combustion chambers and an exhaust circuit for the combustion gases of the heat engine.

[0004] Such a heat engine may include a turbocharger equipped with a compressor, a turbine, and a common shaft on which the compressor and turbine are mounted. The compressor is arranged in the air intake circuit so as to increase the mass flow rate of air admitted into the combustion chambers. The turbine is arranged in the exhaust gas circuit so as to expand the exhaust gases passing through it and to drive the compressor.

[0005] During sudden acceleration of the motor vehicle, a high torque is required from the internal combustion engine. To deliver such torque, the compressor must provide a high compression ratio.

[0006] In certain situations, particularly when the heat engine is operating at low speed, the high compression ratio required of the compressor may exceed the compressor's compression limit, and the compressor therefore cannot provide such a high compression ratio.

[0007] Moreover, when such a high compression ratio is demanded of the compressor, pressure oscillations may appear near the compressor and damage it. Description of the invention

[0008] The present invention therefore aims to overcome all or part of the aforementioned drawbacks, to increase the torque of a heat engine, to increase the compression ratio of a heat engine compressor, and to reduce pressure oscillations occurring near the engine compressor thermal.

[0009] The invention relates to a method for increasing the torque of a motor vehicle internal combustion engine, the internal combustion engine comprising an air intake circuit equipped with a compressor configured to modify the mass flow rate of the internal combustion engine's air intake, the method comprising at least the following steps:

[0010] - a step of determining a setpoint for increasing downstream air pressure of the compressor;

[0011] - a step of reducing the upstream air pressure of the compressor carried out independently during the compressor's operation; and

[0012] - a step of increasing a compressor compression ratio in such a way to increase the downstream air pressure of the compressor according to the aforementioned instruction.

[0013] The term "a step of reducing an upstream air pressure of the compressor carried out independently of the compressor" means that the reduction of the upstream air pressure of the compressor is not carried out by the compressor.

[0014] Decreasing the upstream air pressure of the compressor increases the compressor's compression ratio, defined as the value of the downstream air pressure of the compressor divided by the value of the upstream air pressure of the compressor, and also increases a corrected mass flow rate of air passing through the compressor.

[0015] Thus, an operating point of the compressor on a compressor field map is modified, the operating point being able to move away from a maximum compression curve of the compressor and allowing a greater increase in the downstream air pressure of the compressor, the maximum compression curve of the compressor being an intrinsic characteristic of the compressor.

[0016] Reducing the upstream air pressure of the compressor also modifies the pressure oscillations or pressure pulsations occurring upstream of the compressor and can modify the air spray conditions of a compressor wheel.

[0017] Advantageously, the step of determining a setpoint for increasing the downstream air pressure of the compressor includes a substep of determining a difference between an initial compression ratio of the compressor and a maximum compression ratio of the compressor, the step of decreasing an upstream air pressure of the compressor being carried out when said difference is insufficient to increase, at constant upstream air pressure of the compressor, the downstream air pressure of the compressor according to said setpoint.

[0018] Thus, the step of reducing the upstream air pressure of the compressor is implemented only when the compressor cannot, at constant upstream air pressure of the compressor, provide a compression ratio enabling the downstream air pressure of the compressor to be increased according to said increase instruction.

[0019] Said deviation can be determined based on a field mapping of the com pressurizer and an initial corrected mass flow rate of air from the compressor calculated as:

[0020] . me = mr——j= ' ref

[0021] mf being the actual mass flow rate of air of the compressor;

[0022] Pref being a reference pressure;

[0023] T upstream being the temperature of the air upstream of the compressor;

[0024] P upstream being the upstream air pressure of the compressor;

[0025] Pref being a reference temperature.

[0026] By determining the initial operating point of the compressor on the compressor field map from the initial compression ratio of the compressor and the initial corrected air mass flow rate mc of the compressor, said deviation is determined between the initial operating point of the compressor and the maximum compression ratio of the compressor belonging to the maximum compression curve of the compressor.

[0027] It is also noted that a variation in the temperature of the air upstream of the compressor modifies the value of the corrected mass flow rate of the compressor and therefore the operating point of the compressor on the compressor map.

[0028] The step of reducing an upstream air pressure of the compressor may include the partial closure of an air intake valve arranged upstream of the compressor.

[0029] Partial closure of the air inlet valve can be carried out incrementally, with an increase in the compressor compression ratio being calculated at each increment and then compared with a growth rate of a maximum compressor compression curve.

[0030] Thus, we ensure that closing the air intake valve allows the said gap to increase with each increment.

[0031] Alternatively, the partial closing position of the air intake valve is predetermined, during prior tests of the internal combustion engine, and recorded.

[0032] Advantageously, the step of reducing the upstream air pressure of the compressor is carried out so that the upstream air pressure of the compressor is between 0.95 bar and 1.00 bar, in particular between 0.97 bar and 1.00 bar, when the engine is operating at an altitude close to 0 m, corresponding to sea level where the outside pressure is slightly above 1 bar. More generally, the pressure reduction caused by the partial closure of the air intake valve is advantageously at most equal to 50 mbar, and preferably between 20 and 30 mbar.

[0033] The step of determining a setpoint for increasing the downstream air pressure of the compressor may include calculating said setpoint as a function of a setpoint acceleration of the motor vehicle and the speed of the internal combustion engine.

[0034] The acceleration command of the motor vehicle can be determined as a function of the depressment of an accelerator pedal of the motor vehicle or of a value of force exerted on the accelerator pedal of the motor vehicle or of an automaton controlling the motor vehicle.

[0035] The present invention also relates to a heat engine for a motor vehicle, the heat engine comprising an air intake circuit equipped with a compressor configured to modify a mass flow rate of air intake of the heat engine and an air intake valve arranged upstream of the compressor, the heat engine further comprising a computer configured to implement a method of increasing the torque of the heat engine as defined above.

[0036] The heat engine may further include an exhaust circuit for the combustion gases of the heat engine and an exhaust gas recirculation circuit from the exhaust circuit to the air intake circuit such that the recirculation circuit opens into the air intake circuit upstream of the compressor and downstream of the air intake valve.

[0037] The present invention also relates to a motor vehicle comprising a thermal engine as defined above. Brief description of the drawings

[0038] Other objects, features and advantages of the invention will become apparent from the following description, given solely by way of non-limiting example and made with reference to the accompanying drawings in which:

[0039] [Fig-1] schematically illustrates a motor vehicle according to the invention;

[0040] [Fig.2] schematically illustrates a heat engine according to a first example of realization of the invention;

[0041] [Fig.3] illustrates a field map of the compressor of the internal combustion engine of the [Fig.2];

[0042] [Fig.4] schematically illustrates a method for increasing the torque of the motor thermal of the [Fig.2] according to the invention;

[0043] [Fig. 5] illustrates measurements carried out on a heat engine during the commissioning work of the process of [Fig. 4]; and

[0044] [Fig.6] illustrates a heat engine according to a second embodiment of the invention. Detailed description

[0045] Figure 1 schematically represents a motor vehicle 2 comprising an internal combustion engine 4, in particular a gasoline engine 4 or diesel.

[0046] As schematically represented in [Fig. 2], the internal combustion engine 4 comprises a cylinder block 6, an air intake circuit 8 supplying air to the cylinder block 6, a fuel supply circuit (not shown) supplying fuel to the cylinder block 6, and an exhaust circuit 10 for the combustion gases of the cylinder block 6 of the internal combustion engine 4. The cylinder block 6 is here equipped with three cylinders in line. Optionally, the cylinder block 6 may include camshaft phasers on the intake and exhaust sides.

[0047] The air intake circuit 8 includes an air inlet, an air filter 12 suitable for filtering the air from the air inlet, a compressor 14 suitable for modifying, in particular increasing, the mass flow rate of the air from the air filter 12, an air re-cooler 16 suitable for reducing the temperature of the air from the compressor 14, a throttle body 18 suitable for regulating the air flow from the air cooler 16, and an intake manifold (not referenced) suitable for distributing the air from the throttle body 18 into the cylinders of the cylinder block 6.

[0048] The air intake circuit 8 further includes an air intake valve 20 arranged upstream of the compressor 14 and downstream of the air filter 12, an upstream pressure sensor 22 arranged upstream of the compressor 14 and downstream of the air intake valve 20, an upstream temperature sensor 24 arranged upstream of the compressor 14 and downstream of the air intake valve 20, a downstream pressure sensor 26 arranged downstream of the compressor 14 and upstream of the air cooler 16, and an upstream mass air flow sensor 28 arranged upstream of the compressor 14 and downstream of the air intake valve 20.

[0049] The air intake valve 20 is capable of closing to prevent air from circulating through the air intake circuit 8 and capable of opening at least partially to allow air to pass through the air intake circuit 8.

[0050] The exhaust gas circuit 10 includes an exhaust manifold (not referenced) suitable for collecting exhaust gases from the cylinder block 6, a turbine 30 suitable for expanding the exhaust gases from the exhaust manifold, and a catalyst 32 suitable for reducing polluting emissions from the exhaust gases from the turbine 30.

[0051] The internal combustion engine 4 includes a shaft 34 on which the compressor and turbine 30 are mounted to form a turbocharger. The turbocharger is capable of increasing the torque of the internal combustion engine 4 by increasing the mass flow rate of the air admitted into the cylinder block 6, the turbine 30 expanding the exhaust gases passing through it in order to transfer the energy extracted to the compressor 14 compressing the intake air.

[0052] Optionally, the turbine 30 can be variable geometry and thus be suitable for

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[0069] adjust the amount of energy taken from the exhaust gases passing through it. The internal combustion engine 4 further includes a computer 36 capable of communicating with the air intake valve 20, with the upstream and downstream pressure sensors 22, 26, with the upstream temperature sensor 24, and with the upstream mass air flow sensor 28. The calculator 36 is also capable of implementing a method for increasing the torque of the internal combustion engine 4, which will be detailed later. Figure 3 represents a field map of compressor 14 of internal combustion engine 4. The x-axis of the map corresponds to the corrected mass air flow rate "L" of compressor 14, calculated as: With : - Mr. the actual mass flow rate of the compressor 14, for example the mass flow rate of the air measured by the upstream mass flow rate sensor 28. - Prefer a reference pressure, for example 1.00 bar. - Upstream temperature of the air upstream of compressor 14, for example the temperature measured by the upstream temperature sensor 24. - upstream the upstream air pressure of the compressor, for example the pressure measured by the upstream pressure sensor 22. - Prefer a reference temperature, for example 20°C or 25°C. The y-axis of the map corresponds to the compression ratio F of compressor 14, calculated as: P €1 per 1 upstream With Pavai the downstream air pressure of the compressor, for example the pressure measured by the downstream pressure sensor 26. The thick line curve 38 of the map represents the maximum compression curve 38 of the compressor 14 which is an intrinsic characteristic of the compressor 14, the compressor 14 cannot operate in an operating mode located above the maximum compression curve 38 of the compressor 14. The closed curves in thin line of the map represent constant efficiency curves of compressor 14, the higher efficiency curves being the inner curves. The open curves shown in thick lines on the map represent constant-speed curves of compressor 14, the constant speed of compressor 14 being more high for the compression ratio curves rc of the compressor 14 higher.

[0070] Fig. 4 schematically represents the method of increasing the torque of the internal combustion engine 4 implemented by the computer 36.

[0071] We begin with a step 40 of determining a setpoint for increasing the downstream air pressure Pavai of the compressor. For example, the computer 36 performs a calculation based on an acceleration setpoint of the motor vehicle 2 and a speed of the internal combustion engine 4 in order to determine the downstream air pressure P downstream of the compressor required to allow the motor vehicle 2 to accelerate according to the acceleration setpoint.

[0072] The acceleration command of the motor vehicle 2 is, for example, determined as a function of the depressment of the accelerator pedal of the motor vehicle 2 or of a value of force exerted on the accelerator pedal of the motor vehicle 2 or of an automaton controlling the motor vehicle 2.

[0073] Optionally, a substep 42 is performed to determine the difference between the initial compression ratio of the compressor 14 and the maximum compression ratio of the compressor 14, the initial compression ratio of the compressor 14 being the compression ratio rc of the compressor 14 at the time of determining the setpoint for increasing the downstream air pressure Pavai of the compressor, the maximum compression ratio of the compressor 14 being taken from the maximum compression curve 38 of the compressor 14.

[0074] For example, the deviation on the field map of the compressor 14 is calculated from an initial operating point PI of the compressor 14 whose abscissa is the initial corrected mass flow of air of the compressor 14 and whose ordinate is the initial compression ratio of the compressor 14, the initial corrected mass flow of air of the compressor 14 being the corrected air flow of the compressor 14 at the time of determining the setpoint for increasing the downstream air pressure PaVal of the compressor.

[0075] The gap is, for example, calculated as the distance taken vertically or substantially vertically between the initial operating point PI of the compressor 14 and the maximum compression curve 38 of the compressor 14.

[0076] The initial operating point PI of the compressor 14 is shown here on the field map of [Fig.3] close to the maximum compression curve 38 of the compressor 14.

[0077] A strict reduction step 44 of the upstream air pressure Pmwmt of the compressor is then performed. Optionally, the strict reduction step 44 of the upstream air pressure Pamont of the compressor is performed only if the calculated difference between the initial compression ratio of the compressor 14 and the maximum compression ratio of the compressor 14 is insufficient to allow the compressor 14 to increase its compression ratio rc to comply with the downstream air pressure increase instruction Pavai of the compressor without decreasing the upstream air pressure P upstream of the compressor.

[0078] Advantageously, the air intake valve 20 arranged upstream of the compressor 14 is partially closed in order to reduce the air pressure upstream of the compressor 14. For example, the computer 36 communicates an opening position command to the air intake valve 20.

[0079] By decreasing the upstream air pressure Pcmwnt of the compressor, the corrected mass air flow rate of the compressor 14 and the compression ratio rc of the compressor 14 are simultaneously increased. The compressor 14 thus moves from the initial operating point PI to an operating point P2 illustrated in Figure 3. The operating point P2 is further from the maximum compression curve 38 of the compressor 14 than the initial operating point PI. The efficiency of the compressor 14 at the operating point P2 is also greater than the efficiency of the compressor 14 at the initial operating point PI. The compressor 14 is therefore now able to further increase its compression ratio E.

[0080] Finally, a step 46 is performed to increase the compression ratio of the compressor 14 so as to strictly increase the downstream air pressure Pdown of the compressor to comply with the setpoint for increasing the downstream air pressure PaVal of the compressor, thus increasing the torque of the internal combustion engine 4. The compressor 14 therefore moves from operating point P2 to an operating point P3 illustrated in Figure 3, approaching the maximum compression curve 38 of the compressor 14. For example, the control unit 36 ​​communicates a setpoint for the compression ratio rc of the compressor to the compressor 14.

[0081] For clarity, the operating points P1, P2, and P3 have been deliberately placed far apart on the compressor field map 14. Advantageously, the step 44 of reducing the upstream air pressure P of the compressor is carried out so that the upstream air pressure Pa of the compressor is between 0.95 bar and 1.00 bar, in particular between 0.97 bar and 1.00 bar when the engine is operating at an altitude close to 0 m, corresponding to sea level, where the outside pressure is slightly above 1 bar. More generally, the pressure reduction caused by the partial closure of the air inlet valve is advantageously at most 50 mbar, and preferably between 20 and 30 mbar.

[0082] Fig. 5 represents measurements taken on a heat engine 4 during the implementation of the process, the x-axis being a time scale.

[0083] Before time t0, the computer 36 implements the step 40 of determining the downstream air pressure increase setpoint P downstream of the compressor and communicates a torque setting for the internal combustion engine 4.

[0084] In the lower part of [Fig.5], the dark-lined curve 48 represents the torque setpoint of the heat engine 4, the light-lined curve 50 represents the actual measured torque of the heat engine 4, the torque being represented in newton meters.

[0085] An abnormal operating discrepancy exists between the torque setpoint of the internal combustion engine 4 and the actual torque measured by the internal combustion engine 4 at time t0. This is because the compressor 14 is operating in a state of maximum compression; that is, the operating point of the compressor 14 is on the maximum compression curve 38 of the compressor 14, and this does not allow the compressor 14 to supply the downstream air pressure Pavai of the compressor necessary for the internal combustion engine 4 to operate according to the torque setpoint of the internal combustion engine 4.

[0086] In the upper part of Figure 5, the light-lined curve 52 represents the downstream air pressure Pavai of the setpoint compressor, and the dark-lined curve 54 represents the measured downstream air pressure Paval of the compressor, with the pressure shown in kilopascals. The measured downstream air pressure Paval of the compressor fluctuates significantly at time t0, with pressure oscillations occurring in the vicinity of compressor 14.

[0087] In the central part of Figure 5, curve 56 represents the opening position of the air inlet valve 20 as a percentage of opening, curve 58 representing the upstream air pressure P upstream of the compressor measured.

[0088] The computer 36 then determines the difference between the compression ratio rc of the compressor 14 at time tO and the maximum compression ratio of the compressor 14.

[0089] Then, between times t1 and t2, the computer 36 implements the step 44 of reducing the upstream air pressure PanK,nt of the compressor. The air inlet valve 20, initially fully open, gradually closes until it is at least half closed, the air inlet valve 20 being only 40% open at time t2. The closing of the air inlet valve 20 is done incrementally, in particular in 5% increments from the open position.

[0090] During the progressive closing of the air inlet valve 20, the upstream air pressure PamOnt of the compressor measured gradually decreases independently of the operation of the compressor 14, passing here from an upstream air pressure Panwnt substantially equal to 1 bar to an upstream air pressure P amont substantially equal to 0.98 bar.

[0091] The measured downstream air pressure Paval of the compressor gradually stabilizes between times t1 and t2, with the pressure oscillations present near the compressor 14 decreasing between times t1 and t2.

[0092] At time t2, the computer 36 implements the step 46 of increasing the compression ratio % of the compressor 14 so as to increase the downstream air pressure Pavai of the compressor according to the setpoint. At time t2, the compressor 14 no longer operates in the state of maximum compression, the operating point of the compressor 14 on the field map of the compressor 14 having been modified following the decrease in the upstream air pressure Pamfmt of the compressor 14.

[0093] Between times t2 and t3, the compression ratio rc of the compressor 14 gradually increases. Before time t3, the difference between the curves 48, 50 of the setpoint torque of the heat engine 4 and the actual measured torque of the heat engine 4 is less than the abnormal operating deviation, the difference between the curves 52, 54 of the setpoint downstream air pressure of the compressor and the measured downstream air pressure of the compressor is also less than the abnormal operating deviation.

[0094] At time t3, the torque setpoint of the heat engine 4 is increased again. The difference between the compression ratio P of the compressor 14 at time t3 and the maximum compression ratio of the compressor 14 is determined. The difference being sufficient to increase the compression ratio P of the compressor 14, the compression ratio r< of the compressor 14 is increased without changing the opening of the air intake valve 20.

[0095] Between times t3 and t4, the upstream air pressure PanWnt of the compressor decreases and the downstream air pressure P downstream of the compressor increases, these two pressure variations depending on the increase in the compression ratio rc of the compressor 14.

[0096] At time t4, the actual measured torque of the heat engine 4 is stabilized on the setpoint value of the heat engine 4's torque, the measured downstream air pressure of the compressor is also stabilized on the setpoint value of the downstream air pressure of the compressor.

[0097] Optionally, during the step of decreasing the upstream air pressure Pam»nt of the compressor, the calculator 36 performs the calculation of the increase in the compression ratio rc of the compressor 14, then a comparison of this increase with a growth rate of the maximum compression curve 38 of the compressor 14.

[0098] For example, at each increment of the position of the air inlet valve 20, the computer 36 performs the calculation of a slope of evolution of the operating point of the compressor 14 and compares this slope of evolution with the slope of the maximum compression curve 38 of the compressor 14 in order to ensure that the closing of the air inlet valve 20 moves the operating point of the compressor 14 away from the maximum compression curve 38 of the compressor 14.

[0099] Fig. 6, on which the identical elements bear the same references, represents another heat engine 4 comprising a computer 36 capable of implementing the torque increase process.

[0100] The internal combustion engine 4 comprises a cylinder block 6, an air intake circuit 8, a combustion gas exhaust circuit 10 and a recirculation circuit exhaust gas 60.

[0101] The air intake circuit 8 includes an air inlet, an air filter 12 suitable for filtering the air from the air inlet, a compressor 14 suitable for increasing the mass flow rate of the air from the air filter 12, a throttle body 18 suitable for regulating the air flow from the compressor 14, an air cooler 16 suitable for reducing the temperature of the air from the throttle body 18, an intake manifold suitable for distributing the air from the throttle body 18 into the cylinders of the cylinder block 6, and an air intake valve 20 arranged downstream of the air filter 12 and upstream of the compressor 14.

[0102] The exhaust gas circuit 10 includes an exhaust manifold suitable for collecting exhaust gases from the cylinder block 6, a turbine 30 suitable for expanding the exhaust gases from the exhaust manifold, a catalyst 32 suitable for reducing pollutant emissions from the exhaust gases from the turbine 30 and a particulate filter 62 suitable for filtering the exhaust gases from the catalyst 32.

[0103] Optionally, the particulate filter 62 may include a differential pressure sensor (not shown), and thus be able to determine the mass of particles stored in the particulate filter 62, and be able to purge the particulate filter 62 when the mass of particles stored in the particulate filter 62 reaches a predetermined threshold.

[0104] The exhaust gas recirculation circuit 60 is suitable for taking exhaust gases from the particulate filter 62 and distributing the taken exhaust gases to the air intake circuit 8, the exhaust gas recirculation circuit 60 opening into the air intake circuit 8 downstream of the air intake valve 20 and upstream of the compressor 14.

[0105] The exhaust gas recirculation circuit 60 further includes an additional air cooler 64 suitable for reducing the temperature of the exhaust gases from the exhaust gas combustion circuit 10, an additional filter 65 suitable for filtering the exhaust gases from the additional air cooler 64, and an exhaust gas recirculation valve 66 suitable for closing to prevent the circulation of exhaust gases through the exhaust gas recirculation circuit 60 and suitable for opening at least partially to allow the circulation of exhaust gases through the exhaust gas recirculation circuit 60.

[0106] The internal combustion engine 4 further comprises a bypass circuit 68 of the compressor 14 opening on the one hand into the air intake circuit 8 downstream of the air intake valve 20 and upstream of the compressor 14, and opening on the other hand into the air intake circuit 8 downstream of the compressor 14 and upstream of the housing butterfly 18.

[0107] The bypass circuit 68 of the compressor 14 includes a bypass valve 70 of the compressor 14 capable of closing to prevent air circulation through the bypass circuit 68 and capable of opening at least partially to allow air circulation through the bypass circuit 68 in particular to prevent air from being blown back from the throttle body 18 to the compressor 14 which could damage the compressor 14.

[0108] The heat engine 4 also includes an upstream pressure sensor 22 arranged upstream of the compressor 14 and downstream of the air intake valve 20, a first upstream temperature sensor 71 arranged in the air intake circuit 8 upstream of the air intake valve 20 and downstream of the air filter 12, a second upstream temperature sensor 72 arranged in the exhaust gas recirculation circuit 60 downstream of the exhaust gas recirculation valve 66, an upstream mass air flow sensor 74 arranged in the air intake circuit 8 upstream of the air intake valve 20 and downstream of the air filter 12, a downstream pressure sensor 26 arranged in the air intake circuit 8 downstream of the compressor 14 and upstream of the throttle body 18.

[0109] Optionally, the internal combustion engine 4 includes an additional upstream mass air flow sensor (not shown) arranged in the exhaust gas recirculation circuit 60 downstream of the exhaust gas recirculation valve 66 and capable of measuring the mass flow of the exhaust gases recirculated into the air intake circuit 8. Alternatively, the control unit 36 ​​is capable of estimating the mass flow of the exhaust gases recirculated into the air intake circuit 8 from the temperature measured by the second upstream temperature sensor 72 and the opening position of the exhaust gas recirculation valve 66.

[0110] The actual mass flow rate of air tflr of the compressor 14 is calculated as the sum of the mass flow rate of air from the air intake circuit 8 and the mass flow rate of the exhaust gases recirculated in the air intake circuit 8. Optionally, the exhaust gas recirculation valve 66 can be closed during the implementation of the torque increase method.

[0111] The corrected mass flow rate of the compressor 14 is calculated using an estimated air temperature upstream of the compressor Tamont and the upstream air pressure Pamont of the compressor measured by the upstream pressure sensor 22. The air temperature upstream of the compressor Tamon1 is, for example, estimated from the mass flow rate of the air coming from the air intake circuit 8, the temperature measured by the first upstream temperature sensor 71, the mass flow rate of the exhaust gases recirculated in the air intake circuit 8, and the second upstream temperature sensor 72. Alternatively, the internal combustion engine 4 includes a sensor upstream mass flow of air arranged in the exhaust gas recirculation circuit 60 downstream of the exhaust gas recirculation valve 66, downstream of the exhaust gas recirculation circuit 60 and upstream of the compressor 14.

[0112] The compression ratio rc of the compressor 14 is calculated with the downstream air pressure ^avai of the compressor measured by the downstream pressure sensor 26, and with the upstream air pressure P amont of the compressor measured by the upstream pressure sensor 22.

Claims

Demands

1. A method for increasing the torque of a motor vehicle (2) internal combustion engine (4), the internal combustion engine (4) comprising an air intake circuit (8) equipped with a compressor (14) configured to modify a mass flow rate of the internal combustion engine (4) air intake, characterized in that it comprises at least the following steps: - a step of determining (40) a setpoint for increasing the downstream air pressure (P downstream) of the compressor; - a step of decreasing (44) an upstream air pressure (Pa upstream) of the compressor carried out independently of the compressor (14); and - a step of increasing (46) a compression ratio (re) of the compressor (14) so ​​as to increase the downstream air pressure (Pa upstream) of the compressor according to said setpoint.

2. A method according to claim 1, wherein the step of determining (40) a setpoint for increasing the downstream air pressure of the compressor includes a substep of determining (42) a difference between an initial compression ratio of the compressor (14) and a maximum compression ratio of the compressor (14), the step of decreasing (44) an upstream air pressure (Pamom) of the compressor being carried out when said difference is insufficient to increase, at constant upstream air pressure (Patmmt) of the compressor, the downstream air pressure (PaVai) of the compressor according to said setpoint.

3. Method according to claim 2, wherein said deviation is determined as a function of a field map of the compressor (14) and an initial corrected air mass flow rate nîo of the compressor calculated as: mc = mr--"--== P amom^P ref being the actual air mass flow rate of the compressor (14); Pref being a reference pressure; Pamont being the air temperature upstream of the compressor (14); Pamont being the air pressure upstream of the compressor; Tre f being a reference temperature.

4. A method according to any one of the preceding claims, wherein the step of reducing an upstream air pressure (Pamont) of the compressor comprises the partial closure of a supply valve air (20) arranged upstream of the compressor (14).

5. A method according to claim 4, wherein the partial closure of the air inlet valve (20) is carried out incrementally, an increase in the compression ratio (r< ) of the compressor (14) being calculated at each increment and then compared with a growth rate of a maximum compression curve (38) of the compressor (14).

6. A method according to any one of the preceding claims, wherein the step of reducing an upstream air pressure (Pamont) of the compressor is carried out so that the reduction of the upstream air pressure (Pamtmt) of the compressor is at most equal to 50 mbar, and preferably between 20 and 30 mbar.

7. A method according to any one of the preceding claims, wherein the step of determining (40) a downstream air pressure increase setpoint (downstream P) of the compressor includes calculating said setpoint as a function of an acceleration setpoint of the motor vehicle (2) and a speed of the internal combustion engine (4).

8. Internal combustion engine (4) for motor vehicle (2), the internal combustion engine (4) comprising an air intake circuit (8) equipped with a compressor (14) configured to modify a mass flow rate of air intake of the internal combustion engine (4) and an air intake valve (20) arranged upstream of the compressor (14), the internal combustion engine (4) further comprising a computer (36) configured to implement a method according to any one of claims 1 to 7.

9. Heat engine (4) according to claim 8, further comprising a combustion gas exhaust circuit (10) of the heat engine (4) and an exhaust gas recirculation circuit (60) from the exhaust circuit (10) to the air intake circuit (8) such that the recirculation circuit (60) opens into the air intake circuit (8) upstream of the compressor (14) and downstream of the air intake valve (20).

10. Motor vehicle (2) comprising a heat engine (4) according to one of claims 8 and 9.

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