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) provided with a compressor (14) configured to modify an air intake mass flow rate of the heat engine (4) comprises at least the following steps: - a step of determining (40) a setpoint for increasing the downstream air pressure () of the compressor; - a step of decreasing (44) an upstream air pressure () of the compressor carried out independently of the compressor (14); and - a step of increasing (46) a compression ratio () of the compressor (14) so ​​as to increase the downstream air pressure () of the compressor according to said setpoint. Figure for the abstract: Fig 3

Description

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

[0001] The technical field of the present invention is gasoline or diesel thermal engines 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 comprises 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 comprise a turbocharger provided with a compressor, a turbine and a common shaft on which the compressor and the 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 combustion gas exhaust 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 heat 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 be higher than the compression limit of the compressor, the compressor therefore not being able to provide such a high compression ratio.

[0007] Furthermore, when such a high compression ratio is required of the compressor, pressure oscillations may occur near the compressor and damage it. Statement of the invention

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

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

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

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

[0012] - a step of increasing a compression ratio of the compressor so as to to increase the downstream air pressure of the compressor according to said instruction.

[0013] By "a step of reducing an upstream air pressure of the compressor carried out independently of the compressor" is meant 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 compression ratio of the compressor, 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 through the compressor.

[0015] Thus an operating point of the compressor on a field map of the compressor 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 air pressure downstream of the compressor, the maximum compression curve of the compressor being an intrinsic characteristic of the compressor.

[0016] Decreasing the air pressure upstream of the compressor also modifies the pressure oscillations or pressure pulsations occurring upstream of the compressor and may modify the air flushing conditions of a compressor wheel.

[0017] Advantageously, the step of determining a setpoint for increasing the downstream air pressure of the compressor comprises a sub-step of determining a difference between an initial compression ratio of the compressor and a maximum compression ratio of the compressor, the step of reducing 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 an 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 making it possible to increase the downstream air pressure of the compressor according to said increase setpoint.

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

[0020] . me = mr——j= ' ref

[0021] mf being the actual air mass flow rate 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 difference between the initial operating point of the compressor and the maximum compression ratio of the compressor corresponding to the maximum compression curve of the compressor is determined.

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

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

[0029] Partial closing of the air intake valve may be performed incrementally, with an increase in the compressor compression ratio being calculated at each increment and then compared with a growth rate of a maximum compression curve of the compressor.

[0030] Thus, it is ensured that closing the air intake valve allows said gap to be increased at each increment.

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

[0032] Advantageously, the step of reducing an 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 operates at an altitude close to 0 m corresponding to sea level where the external pressure is slightly greater than 1 bar. More generally, the reduction in pressure caused by the partial closing 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 comprise calculating said setpoint as a function of a setpoint acceleration of the motor vehicle and a thermal engine speed.

[0034] The acceleration setpoint of the motor vehicle can be determined as a function of the depression of an accelerator pedal of the motor vehicle or of a force value 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 provided with a compressor configured to modify an air intake mass flow rate 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 for increasing the torque of the heat engine as defined previously.

[0036] The heat engine may further comprise an exhaust circuit for the combustion gases of the heat engine and a circuit for recirculating the exhaust gases 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 heat engine as defined above. Brief description of the drawings

[0038] 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:

[0039] [Fig-1] schematically illustrated 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 thermal engine of the [Fig.2] ;

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

[0043] [Fig.5] illustrates measurements taken on a heat engine during start-up implementation of the process of [Fig.4]; and

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

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

[0046] As shown schematically in [Fig.2], the heat 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 a combustion gas exhaust circuit 10 of the cylinder block 6 of the heat engine 4. The cylinder block 6 is here provided with three in-line cylinders. Optionally, the cylinder block 6 may comprise camshaft phase shifters at the intake and exhaust.

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

[0048] The air intake circuit 8 further comprises 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 air mass 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 the flow of air 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 combustion gas exhaust circuit 10 comprises an exhaust manifold (not referenced) capable of collecting the exhaust gases coming from the cylinder block 6, a turbine 30 capable of expanding the exhaust gases coming from the exhaust manifold, and a catalyst 32 capable of reducing the polluting emissions of the exhaust gases coming from the turbine 30.

[0051] The heat engine 4 comprises a shaft 34 on which the compressor and the turbine 30 are mounted so as to form a turbocharger. The turbocharger is capable of increasing the torque of the heat 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 restore the energy taken from the compressor 14 compressing the intake air.

[0052] Optionally, the turbine 30 can have variable geometry and thus be capable of

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[0069] adjust the amount of energy taken from the exhaust gases passing through it. The heat engine 4 further comprises 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 air mass flow sensor 28. The computer 36 is also capable of implementing a method for increasing the torque of the thermal engine 4 which will be detailed later. [Fig.3] represents a field map of the compressor 14 of the heat engine 4. The abscissa axis of the map corresponds to the corrected air mass flow rate "L" of compressor 14 calculated as: With : - mr the actual air mass flow rate of the compressor 14, for example the air mass flow rate measured by the upstream air mass flow sensor 28. - Pref a reference pressure, for example 1.00 bar. - T upstream the temperature of the air upstream of the 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 € p 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 not being able to operate in an operating mode located above the maximum compression curve 38 of the compressor 14. The thin closed curves in the map represent constant efficiency curves of compressor 14, with the higher efficiency curves being the inner curves. The open curves in thick line of the map represent curves at constant speed of compressor 14, the constant speed of compressor 14 being more high for the higher rc compression ratio curves of the 14 compressor.

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

[0071] We begin with a step 40 of determining a downstream air pressure increase setpoint Pavai of the compressor. For example, the computer 36 performs a calculation as a function of an acceleration setpoint of the motor vehicle 2 and a speed of the thermal engine 4 in order to determine the downstream air pressure P downstream of the compressor necessary to allow the motor vehicle 2 to accelerate according to the acceleration setpoint.

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

[0073] Optionally, a sub-step 42 is carried out for determining a 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 air mass flow rate of the compressor 14 and whose ordinate is the initial compression ratio of the compressor 14, the initial corrected air mass flow rate of the compressor 14 being the corrected air flow rate of the compressor 14 at the time of determining the setpoint for increasing the downstream air pressure PaVal of the compressor.

[0075] The deviation 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 here represented on the field map of [Fig.3] close to the maximum compression curve 38 of the compressor 14.

[0077] A step 44 of strict reduction of the upstream air pressure Pmwmt of the compressor is then carried out. Optionally, the step 44 of strict reduction of the upstream air pressure Pamont of the compressor is carried out 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 respect the set point for increasing the downstream air pressure Pavai of the compressor without reducing 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 instruction to the air intake valve 20.

[0079] By decreasing the upstream air pressure Pcmwnt of the compressor, the corrected air mass flow rate of the compressor 14 and the compression ratio rc of the compressor 14 are simultaneously increased. The compressor 14 therefore moves from the initial operating point PI to an operating point P2 illustrated in FIG. 3, the operating point P2 being further from the maximum compression curve 38 of the compressor 14 than the initial operating point PI is, the efficiency of the compressor 14 at the operating point P2 also being 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 carried out to increase the compression ratio of the compressor 14 so as to strictly increase the downstream air pressure P downstream of the compressor to comply with the setpoint for increasing the downstream air pressure PaVal of the compressor, thus making it possible to increase the torque of the heat engine 4. The compressor 14 therefore passes from the operating point P2 to an operating point P3 illustrated in FIG. 3 by approaching the maximum compression curve 38 of the compressor 14. For example, the computer 36 communicates a compression ratio setpoint rc of the compressor to the compressor 14.

[0081] For reasons of understanding, the operating points P1, P2 and P3 have been deliberately separated on the field map of the compressor 14. Advantageously, the step 44 of reducing the upstream air pressure P upstream of the compressor is carried out so that the upstream air pressure Pamont 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 operates at an altitude close to 0 m corresponding to sea level where the external pressure is slightly greater than 1 bar. More generally, the reduction in pressure caused by the partial closing of the air intake valve is advantageously at most equal to 50 mbar, and preferably between 20 and 30 mbar.

[0082] [Fig.5] represents measurements carried out on a heat engine 4 during the implementation of the method, the abscissa axis being a time scale.

[0083] Before time t0 the computer 36 implements the step 40 of determining the setpoint for increasing the downstream air pressure P downstream of the compressor and communicates a torque instruction to the thermal engine 4.

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

[0085] An abnormal operating deviation is present between the torque setpoint of the heat engine 4 and the actual measured torque of the heat engine 4 at time t0. In fact, the compressor 14 operates in a maximum compression state, that is to say that the operating point of the compressor 14 is on the maximum compression curve 38 of the compressor 14 and does not allow the compressor 14 to provide the downstream air pressure Pavai of the compressor necessary for the heat engine 4 to operate according to the torque setpoint of the heat engine 4.

[0086] In the upper part of Figure 5, the light-line curve 52 represents the downstream air pressure Pavai of the setpoint compressor, the dark-line curve 54 represents the measured downstream air pressure Paval of the compressor, the pressure being represented in kilopascals. The measured downstream air pressure P downstream of the compressor fluctuates strongly at time t0, pressure oscillations being present near the compressor 14.

[0087] In the central part of Figure 5, curve 56 represents the opening position of the air intake 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 t0 and the maximum compression ratio of the compressor 14.

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

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

[0091] The measured downstream air pressure Paval of the compressor gradually stabilizes between times t1 and t2, 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 is no longer operating in the maximum compression state, 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 increases progressively. Before time t3, the difference between the curves 48, 50 of the torque setpoint of the heat engine 4 and the actual measured torque of the heat engine 4 is less than the abnormal operating difference, the difference between the curves 52, 54 of the compressor downstream air pressure setpoint and the measured compressor downstream air pressure also being less than the abnormal operating difference.

[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 modifying 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 torque setpoint value of the heat engine 4, the measured downstream air pressure of the compressor also being stabilized on the downstream air pressure setpoint value of the compressor.

[0097] Optionally, during the step 44 of decreasing the upstream air pressure Pam»nt of the compressor, the computer 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 intake valve 20, the computer 36 calculates 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 intake valve 20 moves the operating point of the compressor 14 away from the maximum compression curve 38 of the compressor 14.

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

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

[0101] The air intake circuit 8 comprises an air inlet, an air filter 12 capable of filtering the air coming from the air inlet, a compressor 14 capable of increasing the mass flow rate of the air coming from the air filter 12, a throttle body 18 capable of adjusting the flow rate of air coming from the compressor 14, an air cooler 16 capable of reducing the temperature of the air coming from the throttle body 18, an intake manifold capable of distributing the air coming 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 combustion gas exhaust circuit 10 comprises an exhaust manifold capable of collecting the exhaust gases coming from the cylinder block 6, a turbine 30 capable of expanding the exhaust gases coming from the exhaust manifold, a catalyst 32 capable of reducing the polluting emissions of the exhaust gases coming from the turbine 30 and a particulate filter 62 capable of filtering the exhaust gases coming from the catalyst 32.

[0103] Optionally, the particulate filter 62 may comprise 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 capable of taking exhaust gases from the particle 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 comprises an additional air cooler 64 adapted to decrease the temperature of the exhaust gases coming from the combustion gas exhaust circuit 10, an additional filter 65 adapted to filter the exhaust gases coming from the additional air cooler 64, and an exhaust gas recirculation valve 66 adapted to close to prevent the circulation of exhaust gases through the exhaust gas recirculation circuit 60 and adapted to open at least partially to allow the circulation of exhaust gases through the exhaust gas recirculation circuit 60.

[0106] The heat 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 comprises a bypass valve 70 of the compressor 14 capable of closing to prevent the circulation of air through the bypass circuit 68 and capable of opening at least in part to allow the circulation of air through the bypass circuit 68 in particular to prevent a backflow of air from the throttle body 18 towards the compressor 14 which risks damaging the compressor 14.

[0108] The heat engine 4 also comprises 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 air mass 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 heat engine 4 comprises an additional upstream air mass 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 rate of the exhaust gases recirculated in the air intake circuit 8. Alternatively, the computer 36 is capable of estimating the mass flow rate of the exhaust gases recirculated in 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 air mass flow rate tflr of the compressor 14 is calculated as the sum of the air mass flow rate 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 may be closed when implementing the torque increase method.

[0111] The corrected air mass flow rate of the compressor 14 is calculated with an estimated air temperature upstream of the compressor Tamont and with 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 air mass flow rate 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 heat engine 4 comprises a sensor upstream air mass flow rate 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 upstream of the compressor measured by the upstream pressure sensor 22.

Claims

Claims

1. Method for increasing the torque of a heat engine (4) of a motor vehicle (2), the heat engine (4) comprising an air intake circuit (8) provided with a compressor (14) configured to modify an air intake mass flow rate of the heat engine (4), 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 (Pamont) 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 (Pavai) of the compressor according to said setpoint.

2. Method according to claim 1, in which the step of determining (40) a setpoint for increasing the downstream air pressure of the compressor comprises a sub-step 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 preceding claim, wherein the step of decreasing (44) an upstream air pressure (Pamont) of the compressor comprises partially closing an inlet valve air (20) arranged upstream of the compressor (14).

5. A method according to claim 4, wherein the partial closing of the air intake 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. Method according to any one of the preceding claims, in which the step of decreasing (44) an upstream air pressure (Pamont) of the compressor is carried out so that the decrease in the upstream air pressure (Pamtmt) of the compressor is at most equal to 50 mbar, and preferably between 20 and 30 mbar.

7. Method according to any one of the preceding claims, in which the step of determining (40) a setpoint for increasing the downstream air pressure (P downstream) of the compressor comprises calculating said setpoint as a function of an acceleration setpoint of the motor vehicle (2) and a speed of the thermal engine (4).

8. Heat engine (4) for a motor vehicle (2), the heat engine (4) comprising an air intake circuit (8) provided with a compressor (14) configured to modify an air intake mass flow rate of the heat engine (4) and an air intake valve (20) arranged upstream of the compressor (14), the heat 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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