RU2525862C2 - Method and device for evaluation of fresh air mass in combustion chamber, method of full filling evaluation, recording unit for these methods and vehicle equipped with evaluation unit - Google Patents

Abstract

FIELD: transport.

SUBSTANCE: invention relates to transport and can be used for evaluation fresh air mass Ma entering combustion chamber of engine cylinder. According to the invention, during engine cycle the evaluation (128) of total mass Mtot, of gas contained in combustion chamber is performed at the end of fresh air inflow, the evaluation (120, 124) of mass of burnt gases contained in combustion chamber is performed at the end of burnt gas outflow, and the evaluation (128) of fresh air mass Ma is performed from difference between evaluated total mass Mtot and burnt gas mass Mb.

EFFECT: higher accuracy of fresh air mass evaluation which air enters engine cylinder combustion chamber.

13 cl, 3 dwg

Description

The present invention claims the priority of French application 0951133, filed February 23, 2009, the contents of which (text, drawings and claims) are used in this case as a reference.

The invention relates to an evaluation method and a device for estimating the mass Ma of fresh air entering the combustion chamber of an engine cylinder during one engine cycle. The object of the invention is also a method for evaluating the full filling with fresh air, blown into the combustion chamber, and a car equipped with a device for evaluation.

The engine cycle includes sequentially releasing the burnt gases from the combustion chamber, supplying fresh air and fuel to the combustion chamber, and burning the mixture in this combustion chamber. In the case of a four-stroke engine, the engine cycle corresponds to two reciprocating movements of the piston in the cylinder between the two extreme positions of its stroke, i.e. top dead center (PMH) and bottom dead center (PMB).

The release of burnt gases lasts until one or more exhaust valves are open. Similarly, fresh air is supplied while one or more inlet valves are open.

As you know, the power developed by an internal combustion engine depends on the amount of air supplied to the combustion chamber of this engine. This amount of air is proportional to the density of this air. As a result of this, if it is necessary to obtain high power, it is envisaged to increase this amount of air by means of compressing this air before it is supplied to this combustion chamber. This operation is usually called boost and can be performed by a boost device, such as a turbocharger or a drive compressor, such as a screw compressor.

To further increase the amount of air supplied to the cylinder, a residual exhaust gas blow may be provided. This purge allows you to remove exhaust gases from the combustion chamber to replace them with pressurized air.

As indicated in US Pat. No. 4,217,866, this purge is provided by simultaneously opening the intake and exhaust valves of the same combustion chamber from several degrees to several tens of degrees of the crankshaft rotation angle. This usually occurs at the end of the exhaust and at the beginning of the fresh air intake. More precisely, since the air pressure at the level of the open intake valve is higher than the pressure at the level of the exhaust valve, an air stream is generated that flows directly from the inlet to the exhaust, entraining the residual exhaust gases present in the combustion chamber. The period during which the inlet and outlet valves are simultaneously open is called “valve bypass”.

In the case of engines operating in ambient air, that is, naturally aspirated engines, valve bypass can also be carried out. In this case, during the bypass of the valves, the exhaust gases are sucked into the combustion chamber. It is said that exhaust gases are absorbed again. Such a function is known by the acronym IGR (Internal Gaz Recirculation) or Internal Exhaust Gas Recirculation.

Known methods for evaluating the flow rate of fresh air entering the combustion chamber of the engine cylinder. However, these methods have low accuracy and do not really allow to estimate the amount of fresh air entering each combustion chamber. Therefore, this rating is important for precise engine control. For example, this estimate is useful for determining the amount of fuel injected and controlling the timing of the ignition.

The invention is aimed at eliminating these drawbacks and offers a more accurate way of estimating the mass of fresh air entering the combustion chamber.

в себя оценку общей массы Mtot газа, находящегося в камере сгорания, в конце впуска свежего воздуха, оценку массы Mb выхлопных газов, содержащихся в камере сгорания, в конце выпуска выхлопных газов и оценку массы Ма свежего воздуха исходя из разности между оцененными общей массой Mtot и массой Mb выхлопных газов.Thus, an object of the invention is a method for estimating the mass Ma of fresh air entering the combustion chamber of an engine cylinder during an engine cycle, which includes $$$$

includes an estimate of the total mass Mtot of the gas in the combustion chamber at the end of the fresh air inlet, an estimate of the mass Mb of exhaust gases contained in the combustion chamber at the end of the exhaust gas, and an estimate of the mass Ma of fresh air based on the difference between the estimated total mass Mtot and mass Mb of exhaust gases.

Estimates of the total mass Mtot and mass Mb of the exhaust gases can be accurately determined without measuring pressure or temperature inside the combustion chamber. Therefore, this method of estimating the mass of Ma is more accurate.

Embodiments of this method of estimating the mass of Ma may include one or more characteristics corresponding to the examples described below.

In one embodiment, the exhaust mass estimate Mb comprises an estimate of the mass M_resi of the residual exhaust gases contained in the combustion chamber at the end of the exhaust and an estimate of the exhaust mass Mb_reasp re-sucked into the combustion chamber during valve bypass. This embodiment makes it possible to obtain a more accurate estimate of the mass Mb, since the residual mass of exhaust gases and re-sucked during exhaust gas bypass valves are taken into account simultaneously.

In the embodiment, the Mb_resi mass estimate is based on the pressure P of the _{UST of the} exhaust gases, the internal volume of the combustion chamber at the end of the exhaust, the temperature T of the _{UST of the} exhaust gas and the correction factor A of the _UST for the pressure of the _UST , the value of which is a function of the angle at the end of the exhaust and the engine mode . This option also allows you to get an accurate estimate of the mass of residual exhaust gases in the combustion chamber at the end of the exhaust without the need to measure pressure or temperature inside the combustion chamber.

In the embodiment, which allows to increase the accuracy of the assessment taking into account the bypass of the valves, the Mb_reasp mass estimate is obtained from the following expression:

,

,

Where:

- Mb _reasp is the consumption of re-sucked exhaust gases,

- R _ESN is the pressure of the exhaust gases,

-P _ADM is the incoming air pressure,

- T _ESN is the temperature of the exhaust gases,

- r is a constant equal to the following ratio R / M, where R is the universal constant of ideal gases and M is the molar mass in kg.mol ^{-1 of} exhaust gases,

- Sbase is a correction value, a function of the engine mode and the difference between the angles FE and OA, respectively, the termination of release and the beginning of the intake,

- Scor is a correction value, a function of the difference between the angles FE and OA and the engine mode,

- POND is a correction value, a function of engine mode and valve bypass position, given by the following ratio (FE + OA) / 2,

-G (P _ADM / P _ESN ) is determined from the following relationship:

,

,

where γ is the ratio of heat capacity at constant pressure of exhaust gases to heat capacity at a constant volume of exhaust gases,

- G₀(P_ADM/ P_Ech) determined from the following relationship:

.

.

In an embodiment, an estimate of the total mass Mtot is determined based on the inlet air pressure P _ADM , the volume of the combustion chamber at the end of the inlet, the temperature T _{melange of the} mixture of fresh air and exhaust gases contained in the combustion chamber, at the end of the fresh air intake and the correction factor A _ADM , the value of which obtained from pre-recorded cartography depending on the angle FA of the inlet end and the engine mode. This makes it possible to obtain an accurate estimate of this mass Mtot, since it takes into account mass transfer during valve bypass.

In an option that allows you to estimate the mass of Ma without data on temperature and pressure inside the combustion chamber, the estimate of the mass of Ma of fresh air is determined by solving the following system of equations:

,

,

Where

- A _ADM is a correction factor, the value of which is a function of the engine mode and the end angle of the intake,

- P _ADM is the air inlet pressure,

- V _{cyl_FA} is the calculated geometric volume of the chamber at the angle of the end of the intake,

- T _melange is the temperature of the mixture of fresh air and exhaust gases contained in the combustion chamber,

- r is a constant equal to the ratio R / M, where R is the universal constant of ideal gases, and M is the molar mass in kg.mol ^{-1 of the} gas mixture,

- cpa and cpb are the specific heat at constant pressure, respectively, of fresh air and exhaust gases, and

- Ta and Tb are the temperatures of fresh air and exhaust gases, respectively.

The object of the invention is also a method for evaluating the complete filling of rempl_tot with fresh air being blown into the combustion chamber of the engine cylinder during the engine cycle, the method including estimating the mass Ma of fresh air introduced into the combustion chamber using the aforementioned method, estimating the mass of Mbal_tot blown gas (air or exhaust gas) in the process of bypassing the valves and assessing the complete filling of rempl_tot with pressurized fresh air based on the estimated mass of fresh air Ma and the mass Mbal_tot of purged gases.

The above method is more accurate, since it takes into account the mass of gases blown to the exhaust during valve bypass.

In an embodiment of the invention, the evaluation of the complete filling is carried out by solving the following system of equations:

,

,

Where

- Mtot is the total mass of gases contained in the combustion chamber at the end of the fresh air inlet as defined above,

- Mo is the reference mass of air under normal conditions of temperature and pressure,

- Mb is the mass of exhaust gases contained in the combustion chamber at the end of the exhaust,

- Mbal_tot is the total mass of purged gases (air or exhaust gases) during valve bypass,

- Mbal is the mass of purged gas (air) between the inlet and outlet in the process of bypass valves,

- Max (...) and Min (...) are respectively functions that give maximum and minimum,

- | ... | is an absolute value.

The solution of the above equation allows to increase the accuracy, since the fact that the mass of intake air fills the volume of the combustion chamber until there are no exhaust gases in it is taken into account.

The object of the invention is also a unit for recording information containing instructions for performing the above method, when these instructions are executed by a computer.

The invention also relates to a device for estimating the mass Ma of fresh air introduced into the combustion chamber of an engine cylinder during an engine cycle, which comprises a module for estimating the total mass Mtot of the gas contained in the combustion chamber at the end of the fresh air inlet, an module for estimating exhaust mass Mb and a module for estimating the mass of Ma of fresh air based on the difference between the estimated total mass Mtot and the mass Mb of exhaust gases.

Finally, an object of the invention is also an automobile comprising an evaluation device presented above.

The invention is further explained in the following description, which is not restrictive, with reference to the accompanying drawings, in which:

- figure 1 schematically depicts a car in which the mass Ma and the full filling rempl_tot are evaluated ;

- figure 2 is a graph schematically showing the movements of the intake and exhaust valves during an engine cycle,

- figure 3 depicts the architecture of the computer, which is a device for estimating the mass of Ma and full filling rempl_tot, and

- figure 4 is a flowchart of a method for estimating the mass of Ma and completely filling rempl_tot in the car of figure 1.

Figure 1 schematically depicts a car 2 containing an internal combustion engine. For example, car 2 is a passenger car.

The engine of the car 2 contains several cylinders. However, to simplify, figure 1 shows only one cylinder 6 of this internal combustion engine. Inside the cylinder 6 is a piston 8, mounted for translational movement between the top dead center (PMH) and the bottom dead center (PMB). This piston 8 drives the crank 10 of the crankshaft 12 by means of the connecting rod 14. The crankshaft 12 drives the wheels of the vehicle 2, such as the wheels 16, by means of a mechanism not shown.

The cylinder 6 forms a combustion chamber 18 defined by the upper part of the piston 8 and not shown by the cylinder head. The fresh air inlet pipe 20 opens into the chamber 18 through the inlet. The inlet valve 24 moves between the closed position in which it seals the fresh air inlet and the open position in which fresh air enters the chamber 18 through the inlet. Valve 24 is moved between the open position and the closed position by the intake valve actuator 26.

In the particular case considered here, a fuel injector 28 is installed in the intake pipe 20 to inject fuel into the fresh air entering the chamber 18. Thus, a mixture of fuel and fresh air begins to form inside the intake pipe.

The inlet pipe 20 is hermetically connected to the compressor 30 of the turbocharger 32, designed to compress the fresh air entering the chamber 18. Thus, the fresh air is compressed and is called fresh air with pressurization.

The candle 34, designed to ignite the air-fuel mixture, opens into the chamber 18. This candle is controlled by the ignition system 36.

The exhaust pipe 40 also opens into the chamber 18 through the outlet. This outlet is configured to overlap with a valve 44 moving between the closed position and the open position, in which exhaust gases contained within the chamber 18 can be removed through the exhaust pipe 40. This valve 44 is moved between its open and closed positions by means of a valve actuator 46 .

The actuators 26 and 46 of the valves may be mechanical valve actuators.

The end of the pipe 40, opposite the end that opens into the chamber 18, is connected to the turbine 48 of the turbocharger 32. This turbine 48 allows, in particular, to reduce the pressure of the exhaust gases before they enter the exhaust system 50.

Various controllable engine systems, such as drives, an ignition system, or also a fuel injector, are connected to an engine control unit 60, also known by the acronym ECU (Engine Control Unit). To simplify FIG. 1, connections between block 60 and various controllable devices are not shown.

Block 60 is also connected to several sensors, such as, for example, crankshaft position sensor 62 and engine mode sensor 64. In this case, the engine mode is defined as the number of revolutions per minute of the motor drive shaft.

Figure 2 depicts a graph of the movement of the valves 24 and 44 in relation to the movements of the piston 8 during one engine cycle. In this graph, the abscissa axis 70 shows the movement of the piston 8 between its top dead center and its bottom dead center, indicated on this graph respectively by the PMN and the PMB. The ordinate axis shows the amplitude of movement of the intake and exhaust valves. This amplitude is zero when the intake valve or exhaust valve is closed. It is maximum when the same valves are fully open. In this case, the movement of the valve 44 is shown by a curve 72, and the movement of the valve 24 is represented by a curve 74.

Axis 70 is calibrated in degrees angles of rotation of the crankshaft. The beginning of this axis is aligned with the top dead center of the fresh air inlet.

As shown in this figure 2, the exhaust valve begins to open at an angle OE, located essentially near the bottom dead point of expansion, and closes at an angle FE. In the particular case shown in figure 2, the angle FE is located behind the top dead center of the inlet.

The inlet valve begins to open at angle OA and closes at angle FA.

In this case, the graph represents a special case in which there is a bypass of the valves. Indeed, the angle OA precedes the angle FE, which means that during a period of several degrees the inlet and outlet valves are open at the same time.

Figure 3 depicts in more detail the possible structure of the block 60 estimating the mass of Ma and full filling rempl_tot.

To this end, block 60 comprises a block 80 for estimating the temperature T of the _{ESN of the} exhaust gases, a block 82 for estimating the pressure P of the _{ESN of} gases, a block 84 for estimating the temperature of T _{ADM of} fresh air entering the chamber 18 through the pipe 20, and a block for estimating the pressure P _{ADM of} fresh air entering inside the chamber 18.

These blocks 80, 82, 84 and 86 are connected to the mass estimation unit 88 Ma and the complete rempl_tot. This evaluation unit 88 is also connected to the engine control unit 90. This unit 90 allows, in particular, to control various drives, injectors and engine ignition systems, depending on the estimates of the mass Ma and complete filling rempl_tot. For example, block 90 can control the amount of injected fuel and set the ignition timing of the air-fuel mixture in the chamber 18 or regulate the opening of the throttle valve, which allows to determine the amount of fresh air entering the chamber 18.

The evaluation unit 88 comprises a module 92 for estimating the mass Mb of exhaust gases contained in the combustion chamber 18 at the end of the exhaust gas outlet, a unit 94 for estimating the mass of Mbal gases purged from the inlet to the exhaust during valve bypass, the unit 96 for evaluating the temperature Tb of the exhaust gases, unit 98 estimates the mass Ma of fresh air entering the chamber 18, and the block 100 estimates the full filling rempl_tot.

Module 92 comprises a sub-module 102 for estimating the mass Mb_resi of residual exhaust gases contained in the chamber 18 at the end of the outlet and a sub-module 104 for estimating the mass Mb_resi of exhaust gases re-sucked when the valves are bypassed inside the chamber 18.

Modules 92-100 will be described in more detail with reference to FIG. 4.

Block 60 is usually made in the form of a programmable computer capable of executing instructions recorded in the information storage unit. In this case, for this, block 60 is connected to memory block 106 containing various instructions and necessary data for implementing the method of FIG. In particular, various cartographies are recorded in this memory 106 for implementing the method of FIG. 4. These cartographies are carried out, for example, experimentally to minimize errors between the estimated values and the actual values.

The operation of block 60 of automobile 2 will be described below in more detail by the method of FIG. 4 in the case of an engine described with reference to FIG.

Before a method for estimating the mass of Ma and completely filling rempl_tot is described in detail, the general principle of this method will be presented.

The general principle is based on the mass balance of gases entering and leaving the chamber 18 during one engine cycle. This mass balance is divided into several calculations that are carried out throughout the entire engine cycle.

First, at the end of the outlet, the mass Mb of exhaust gases in the chamber 18 is estimated. Then, at the end of the inlet, the total mass Mtot of the gases contained inside the chamber 18 is estimated.

Given these two estimates and the fact that the total mass of gases is retained in the engine cycle, the mass Ma of air contained inside the chamber 18 during the engine cycle can be obtained by subtracting the mass Mb from the mass Mtot.

More precisely, based on the mass balance of the gases received and removed during the engine cycle, the mass Ma is given by the following expression:

Ma = Mtot-Mb,

where Mtot is the total mass of exhaust gases in the chamber 18 at the end of the inlet, and Mb is the total mass of exhaust gases in the chamber 18 at the end of the outlet.

In the particular case when a part of the exhaust gas is re-sucked during the valve bypass, the Mb mass estimate is divided by the estimate of the Mb_resi mass of residual exhaust gases not removed through pipe 40 at the end of the exhaust and the exhaust mass Mb_reasp re-sucked during the valve bypass.

The exhaust gas mass Mb is thus determined from the following relation:

Mb = Mb_resi + Mb_reasp,

Where

- Mb_resi is the mass of residual exhaust gases that could not be removed during the release process, and

- Mb_reasp is the mass of exhaust gas recirculated during the bypass process.

In a special case of a supercharged engine when overflowing the valves, they also try to evaluate the full filling of the rempl_tot with fresh pressurized air. The full filling rempl_tot is the total amount of fresh air entering through the intake port during the engine cycle. In the case of a supercharged engine, when the valves are bypassed, part of the fresh air entering through the inlet is immediately removed at the outlet (Mbal). Thus, the full filling of rempl_tot in the first approximation is given by the following relation:

,

,

Where

rempl_tot - full filling with common fresh air,

rempl_cyl - filling the chamber 18 with fresh air,

Mbal is the mass of purged gases from the inlet to the outlet when the valves are bypassed, and

Mo is the reference mass of air under normal conditions of temperature and pressure.

Rempl_cyl fresh air filling is defined by the following expression:

,

,

Ma is the mass of air contained in the chamber 18 at the end of the inlet, and

Mo is the reference mass.

In this case, the normal temperature and pressure conditions correspond to a temperature of 298.15 K, a pressure of 1013 mbar and a volume equal to the volume of a single cylinder.

The values rempl_tot, rempl_cyl and the ratio Mbal / Mo are dimensionless quantities.

Typically, the Mbal mass exists only in supercharged engines. However, the following description of the method is performed for the most complete case, that is, the case when both Mb_reasp and Mbal estimates are performed. Indeed, a person skilled in the art can easily simplify the method described below for adapting it only for the case of engines operating in atmospheric air or supercharged engines.

The method begins with step 120 of estimating the mass Mb_resi of the exhaust gases contained in chamber 18 at the end of the release.

In step 120, the submodule 102 estimates the mass of Mb_resi from the following relationship:

,

,

Where

- P _{cyl_FE} is the pressure inside the chamber 18,

- P _UST is the exhaust gas pressure,

- T _ESN is the temperature of the exhaust gases leaving the pipe 40,

- r is a constant equal to the following ratio R / M, where R is the universal constant of ideal gases, and M is the molar mass in kg.mol ^{-1 of} exhaust gases,

- A _UST is a correction factor that allows you to adjust the pressure P of the _UST to obtain a pressure close to P _{cyl_FE, the} value of which is given by mapping depending on the angle FE of the engine mode, and

- V _{cyl_FE} is the geometric volume of the chamber 18 at the end of the outlet, that is, for the angle FE.

The volume V _{cyl_FE is} given by the following relation:

,

,

where λ is the connecting rod / crank ratio, Cu is the unit volume of cylinder 6 and ε is the compression ratio of the engine.

The ratio λ and the coefficient ε are known characteristics of the engine. Recall that the ratio λ is the ratio between the length of the connecting rod 14 divided by half the length of the crank 18.

In the above expression and in the relationships presented below, pressures P _ESN and P _ADM and temperatures T _ESN and T _ADM are pressures and temperatures estimated by evaluation units 80, 82, 84 and 86 based on physical quantities measured in the engine.

Then, at step 122, the submodule 104 estimates the mass Mb_reasp of the exhaust gases re-sucked during the valve bypass, in this case, this estimate is determined by the following expression:

,

,

where Mb_reasp is the rate of re-sucked exhaust gases, expressed in kg / h, and K is a coefficient that allows you to switch from the flow rate to the mass entering the chamber 18 in the engine cycle.

For example, the coefficient K is given by the following relation:

,

,

where N is the engine mode, "Nbre_cylindre" is the number of engine cylinders, "Nbre_revolutioncycle" is the number of revolutions of the crankshaft during one engine cycle, and "60" allows you to convert the engine mode N, given in revolutions per minute, to the number of revolutions per hour.

For example, for a four-stroke engine containing four cylinders, the coefficient K is K = N × 2 × 60.

The re-sucked exhaust gas flow rate Mb_reasp is calculated according to the Barre Saint-Venant law, adjusted as follows for valve bypass:

,

,

Where

- R _ESN is the exhaust pressure of the exhaust gases,

- P _ADM is the inlet pressure of the air entering the pipe 20,

- T _ESN is the temperature of the exhaust gases,

- Sbase is a predefined mapping, which gives the first correction value depending on the difference between the angles FE and OA and the engine mode,

- Scor is a predefined mapping, which gives a second correction value depending on the difference between the angles FE and OA and the engine mode,

- POND is a predefined mapping that gives a third correction value depending on the position of the bypass valves and the engine mode.

The valve bypass position is given by the following ratio (FE + OA) / 2.

G (P _ADM / P _ECH ) is determined from the following expression:

if

, if

,

where γ is the ratio of heat capacity at constant pressure of exhaust gases to heat capacity at a constant volume of exhaust gases. For example, this ratio is 1.4.

The above equation distinguishes the case of subsonic flow from sound flow.

G ₀ (P _ADM / P _ECH ) is determined from the following relationship:

.

.

Then, in step 124, module 94 estimates the total mass Mbal_tot of the gases purged between the inlet and the outlet during the valve bypass.

The mass of Mbal_tot is obtained from the following expression:

,

,

Where

- Mbal_tot is the flow rate of the purged gases from the inlet to the outlet during valve bypass, expressed in kg / h, and

- K is the same previously determined coefficient for the transition from the flow rate to the mass entering the chamber 18 in the engine cycle.

The Mbal_tot flow rate is estimated based on the Barre Saint-Venant Act, adjusted as follows to account for valve bypass:

,

,

Where

- P _ESN and P _ADM have already been identified,

- T _ADM is the temperature of the air entering the chamber 18,

- S is a predetermined mapping, allowing to obtain a correction value depending on the difference between the angles FE and OA and the engine mode, and

- POND is a predetermined mapping that allows you to get a correction value depending on the position of the bypass valves and engine mode.

The ratio G (P _ECN / P _ADM ) has already been determined above.

The valve bypass position is equal to the following value: (FE + OA) / 2.

, Then, in step 126, module 96 estimates the temperature Tb of the exhaust gases. For this, the temperature Tb is obtained by calculating a heat-containing mixture of residual gases and re-sucked exhaust gases. For example, the temperature Tb is obtained from the following expression:

,

Where

- Mb_resi is the previously estimated mass of residual exhaust gases,

- Mb_reasp is the mass of re-sucked exhaust gases in the process of bypass valves,

- cpb_resi is the specific heat at constant pressure of the residual exhaust gas,

- cpb_reasp is the specific heat at constant pressure of the re-sucked exhaust gas,

- Tb_reasp is the temperature of the exhaust gases re-sucked in bypass valves, and

- Tb_resi is the temperature of the residual exhaust gas obtained from the calculation of adiabatic expansion.

To simplify, for example, the specific heat cpb_resi and cpb_reasp are taken equal.

The temperature Tb_reasp is taken equal to the temperature TECN.

The temperature Tb_resi is calculated from the following expression:

,

,

where all variables have already been defined.

Then, in step 128, module 98 estimates the mass Ma by solving the following system of equations:

,

,

Where

- P _ADM , Mb, Ma have already been defined,

- V _{cyl_FA} is the geometric volume of the chamber 18, calculated at an angle FA,

- A _ADM is a correction factor,

- r is a constant equal to the ratio R / M, where R is the universal constant of ideal gases, and M is the molar mass in kg.mol ^{-1 of the} gas mixture,

- T _melange is the temperature of the mixture of fresh air and exhaust gases contained in the chamber 18,

- cpa and cpb are the specific heat at constant pressure, respectively, of fresh air and exhaust gases, and

- Ta and Tb are the temperatures of fresh air and exhaust gases, respectively.

The volume V _{cyl_FA is} calculated from the following expression:

.

.

, The _ADM correction factor A is obtained from the following expression:

,

Where

- A _{ADM_ATMO} is a correction value obtained from a predetermined mapping depending on the angle FA and engine mode,

- A _{ADM_TURBO} is a correction value obtained from a predetermined mapping depending on the angle FA and engine mode,

- coefficient k _{ATMO_TURBO} is a correction coefficient given by the following expression:

,

,

Where

- P _ATMO is atmospheric pressure,

- Po is the reference pressure, in this case equal to 1013 mbar,

- f _A (N, FA) is a correction value obtained from a predetermined mapping depending on the engine mode and angle FA, and

f _B (N) is a correction value obtained from a predetermined mapping depending on the engine mode.

The ratio determining the temperature T _melange is obtained by calculating the heat-containing mixture from the mass of exhaust gases and the mass of fresh air contained in the chamber 18.

The system of equations presented above is a system of equations with three unknowns. The solution of this system allows one to obtain estimates of the mass of Ma, temperature T _melange, and total mass of Mtot.

More precisely, the mass estimate of Ma is given by the following expression for a particular case when cpb and cp are equal:

.

.

If necessary, in step 128, the estimate of the mass of Ma obtained after solving the system of equations is adjusted depending on the reciprocal temperature of fresh air. For example, the mass of Ma is adjusted using the following expression:

,

,

where f (1 / Ta) is a correction coefficient, the value of which is obtained from a predetermined mapping that gives the value of this correction coefficient depending on the inverse temperature Ta.

Finally, in step 130, module 100 evaluates the complete filling of the rempl_tot with fresh air. This full rempl_tot filling is obtained, for example, from the following relationship:

,

,

where the set of variables of this relation was previously determined, Max (...) and Min (...) are respectively functions that give maximum and minimum, and | ... | is an absolute value.

To obtain the last expression, it is assumed that the gases purged from the inlet to the outlet during the bypass of the valves first completely fill the volume of the chamber 18 before the subsequent passage directly from the inlet to the outlet. Thus, since the mass Mbal_tot of the purged gases is lower than the mass Mb of the exhaust gases, it is believed that there is no purge. On the contrary, since the mass Mbal_tot exceeds the mass Mb of the exhaust gases, it is believed that only a purge exists between the inlet and the outlet. The mass Mbal defined at the beginning of this description corresponds only to the last term of the above relationship.

Numerous other numerous embodiments are possible. For example, if the engine does not have a boost, but only feeds on atmospheric air, then the above formulas can be simplified, since there is no purge from the inlet to the outlet. In other words, the mass of Mbal_tot is zero.

The above can also be applied to an engine in which a camshaft phase regulator is not provided for inlet or outlet.

Finally, what is described above can be used in the absence of bypass valves. In this case, the mass Mb_reasp and the mass Mbal_tot are zero, which simplifies the previous relationship.

Claims (13)

1. The method of estimating the mass Ma of fresh air admitted into the combustion chamber of the engine cylinder during the engine cycle, characterized in that it comprises the steps of evaluating (128) the total mass Mtot of the gas contained in the combustion chamber at the end of the fresh air inlet, evaluating (120, 124) the mass Mb of exhaust gases contained in the combustion chamber at the end of the exhaust gas emission and estimate (128) the mass Ma of fresh air based on the difference between the total mass Mtot and the mass Mb of the estimated exhaust gases. 2. The method according to claim 1, in which the step of evaluating the mass Mb of exhaust gases includes evaluating (120) the mass Mb_resi of the residual exhaust gases contained in the combustion chamber at the end of the exhaust gas and evaluating (122) the mass Mb_reasp of the exhaust gases, repeatedly sucked into the combustion chamber during bypass valves. 3. The method according to claim 2, in which the estimate (120) of the mass Mb_resi is obtained on the basis of the pressure P _{ESN of the} exhaust gases, the internal volume of the combustion chamber at the end of the exhaust gas, the temperature T _{ESN of the} exhaust gases and the correction factor A _{ESN of the} pressure P _ESN , the value which is a function of the angle of the end of the exhaust and the engine mode. 4. The method according to one of the preceding paragraphs, in which the estimate (128) of the total mass Mtot is obtained based on the inlet pressure P _{ADM of the} air, the volume of the combustion chamber at the end of the inlet, the temperature T _{melange of the} mixture of fresh air and exhaust gases contained in the combustion chamber, in the end of the fresh air inlet and the correction factor A _ADM , the value of which is obtained from the cartography predefined depending on the angle FA of the inlet end and the engine mode. 5. The method according to claim 1, in which the mass estimation of Ma of fresh air is carried out by solving the following system of equations:

,
Where
- A _ADM is a correction factor, the value of which is a function of the engine mode and the angle of the end of the intake,
- P _ADM is the air inlet pressure,
- V _{cyl_FA} is the geometric volume of the combustion chamber, calculated from the angle of the end of the inlet,
- T _melange is the temperature of the mixture of fresh air and exhaust gases contained in the combustion chamber,
- r is a constant equal to the ratio R / M, where R is the universal constant of ideal gases, and M is the molar mass in kg.mol ^-1 of the gas mixture,
- cpa and cpb are the specific heat at constant pressure, respectively, of fresh air and exhaust gases, and
- Ta and Tb are the temperatures of fresh air and exhaust gases, respectively. 6. The method according to claim 2, in which the mass estimation Ma of fresh air is carried out by solving the following system of equations:

,
Where
- A _ADM is a correction factor, the value of which is a function of the engine mode and the angle of the end of the intake,
- P _ADM is the air inlet pressure,
- V _{cyl_FA} is the geometric volume of the combustion chamber, calculated from the angle of the end of the inlet,
- T _melange is the temperature of the mixture of fresh air and exhaust gases contained in the combustion chamber,
- r is a constant equal to the ratio R / M, where R is the universal constant of ideal gases, and M is the molar mass in kg.mol ^-1 of the gas mixture,
- cpa and cpb are the specific heat at constant pressure, respectively, of fresh air and exhaust gases, and
- Ta and Tb are the temperatures of fresh air and exhaust gases, respectively. 7. The method according to claim 3, in which the mass estimation Ma of fresh air is carried out by solving the following system of equations:

,
Where
- A _ADM is a correction factor, the value of which is a function of the engine mode and the angle of the end of the intake,
- P _ADM is the air inlet pressure,
- V _{cyl_FA} is the geometric volume of the combustion chamber, calculated from the angle of the end of the inlet,
- T _melange is the temperature of the mixture of fresh air and exhaust gases contained in the combustion chamber,
- r is a constant equal to the ratio R / M, where R is the universal constant of ideal gases, and M is the molar mass in kg.mol ^-1 of the gas mixture,
- cpa and cpb are the specific heat at constant pressure, respectively, of fresh air and exhaust gases, and
- Ta and Tb are the temperatures of fresh air and exhaust gases, respectively. 8. The method according to claim 4, in which the mass estimation Ma of fresh air is carried out by solving the following system of equations:

,
Where
- A _ADM is a correction factor, the value of which is a function of the engine mode and the angle of the end of the intake,
- P _ADM is the air inlet pressure,
- V _{cyl_FA} is the geometric volume of the combustion chamber, calculated from the angle of the end of the inlet,
- T _melange is the temperature of the mixture of fresh air and exhaust gases contained in the combustion chamber,
- r is a constant equal to the ratio R / M, where R is the universal constant of ideal gases, and M is the molar mass in kg.mol ^-1 of the gas mixture,
- cpa and cpb are the specific heat at constant pressure, respectively, of fresh air and exhaust gases, and
- Ta and Tb are the temperatures of fresh air and exhaust gases, respectively. 9. A method for evaluating the complete filling of rempl_tot with fresh air blown into the combustion chamber of the engine cylinder during the engine cycle, characterized in that it comprises the steps of evaluating (128) the mass Ma of fresh air introduced into the combustion chamber using the method of one of the previous points, evaluate (124) the mass of Mbal_tot gases blown from the inlet to the exhaust during valve bypass, and evaluate (130) the complete filling of rempl_tot with fresh pressurized air, the vector control method of the speed of a three-phase machine based on the estimate the mass of fresh air Ma and the mass of Mbal_tot purged gases. 10. The method according to claim 9, in which the assessment (130) of the complete filling is carried out by solving the following system of equations:

,
Where
- Mtot is the total mass of gases contained in the combustion chamber at the end of the fresh air inlet defined above,
- Mo is the reference mass of air under normal conditions of temperature and pressure,
- Mb is the mass of exhaust gases contained in the combustion chamber at the end of the exhaust,
- Mbal_tot is the total mass of purged gases (air and exhaust gases) during valve bypass,
- Mbal is the mass of purged gas (air) between the inlet and outlet during valve bypass,
- Max (...) and Min (...) are respectively functions that give maximum and minimum, and
- | ... | is an absolute value. 11. Block (106) recording information, characterized in that it contains instructions for performing the method according to one of the preceding paragraphs, when these instructions are executed by the computer. 12. A device for estimating the mass Ma of fresh air entering the combustion chamber of the engine cylinder during the engine cycle, characterized in that it contains a module (98) for estimating the total mass Mtot of the gas contained in the combustion chamber at the end of the fresh air intake, module (92 ) estimates of the mass Mb of exhaust gases contained in the combustion chamber at the end of the exhaust gas emission and the module (98) for estimating the mass Ma of fresh air based on the difference between the estimated total mass Mtot and the mass Mb of exhaust gases. 13. A car, characterized in that it contains a device (88) for evaluation according to item 12.

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