ITBO20120489A1 - METHOD OF CONTROL OF AN INTERNAL COMBUSTION ENGINE - Google Patents

Description

DESCRIPTION

â € œMETHOD OF CONTROL OF AN INTERNAL COMBUSTION ENGINEâ €

TECHNIQUE SECTOR

The present invention relates to a control method for an internal combustion engine.

ANTERIOR ART

Internal combustion engines are typically equipped with a number of injectors that inject fuel for combustion into respective cylinders, each of said cylinders is connected to an intake manifold via at least one respective intake valve and to an exhaust manifold via at least one respective drain valve. The said exhaust manifold is connected to an exhaust duct which feeds the exhaust gases produced by combustion to an exhaust system, which emits the gases produced by combustion into the atmosphere and normally includes at least one catalyst (possibly equipped with an anti-particulate filter) and at least one silencer arranged downstream of the catalyst. Furthermore, most internal combustion engines are equipped with a mass flow meter (better known as Air Flow Meter) which is able to detect the flow of air sucked in by the internal combustion engine.

To optimize the management of a plurality of exhaust components, it is necessary to know precisely the flow rate of the exhaust gases.

Typically, this exhaust gas flow is calculated in an electronic control unit of the internal combustion engine through the sum between the flow of air drawn in by the internal combustion engine supplied by the mass flow meter and the flow of fuel used during the injection in the four cylinders; or alternatively, through a â € œSpeed Densityâ € law. In both cases, however, the determination of the exhaust gas flow rate presents some criticalities as it is not sufficiently precise and reliable.

DESCRIPTION OF THE INVENTION

The purpose of the present invention is to provide a method for controlling an internal combustion engine, which method is free from the drawbacks of the state of the art, is reliable and is easy and economical to implement.

According to the present invention there is provided a control method of an internal combustion engine according to what is stated in the attached claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described with reference to the attached drawings, which illustrate a non-limiting example of embodiment in which:

Figure 1 schematically illustrates a supercharged internal combustion engine provided with an electronic control unit which implements a control method implemented according to the present invention;

Figure 2 illustrates through a block diagram the control method implemented in the electronic control unit of the internal combustion engine of Figure 1.

PREFERRED FORMS OF IMPLEMENTATION OF THE INVENTION

In figure 1, the number 1 indicates as a whole an internal combustion engine supercharged by means of a turbocharging system.

The internal combustion engine 1 comprises four injectors 2 which inject fuel directly into four cylinders 3, each of which is connected to an intake manifold 4 via at least one respective intake valve (not shown) and to an exhaust manifold 5 through at least one respective drain valve (not shown). The intake manifold 4 receives fresh air (ie air from the external environment) through an intake duct 6, which is provided with an air filter 7 and is regulated by a butterfly valve 8. Along the intake duct 6 downstream of the air filter 7, there is also a mass flow meter 7 * (better known as Air Flow Meter) which is able to detect the flow rate á¹ AFMdâ € ™ air sucked by the internal combustion engine 1 .

An intercooler 9 is arranged along the intake duct 6 and has the function of cooling the intake air. Connected to the exhaust manifold 5 is an exhaust duct 10 which supplies the exhaust gases produced by combustion to an exhaust system, which emits the gases produced by combustion into the atmosphere and normally comprises at least one catalyst 11 (possibly provided of an anti-particulate filter) and at least one silencer (not shown) arranged downstream of the catalyst 11.

The supercharging system 2 of the internal combustion engine 1 comprises a turbocharger 12 provided with a turbine 13, which is arranged along the exhaust duct 10 to rotate at high speed under the action of the exhaust gases expelled from the cylinders 3, and a compressor 14, which is arranged along the intake duct 6 and is mechanically connected to the turbine 13 to be driven into rotation by the turbine 13 itself so as to increase the pressure of the air present in the supply duct 6.

Along the exhaust duct 10 there is a bypass duct 15, which is connected in parallel to the turbine 13 so as to have its ends connected upstream and downstream of the turbine 13 itself; a wastegate valve 16 is arranged along the bypass duct 15, which is adapted to regulate the flow of exhaust gases flowing through the bypass duct 15 and is piloted by a solenoid valve 17. Along the power supply a bypass duct 18 is provided, which is connected in parallel to the compressor 14 so as to have its ends connected upstream and downstream of the compressor 14 itself; a valve 19 Poff is arranged along the bypass duct 18, which is adapted to regulate the flow rate of the exhaust gases flowing through the bypass duct 18 and is piloted by an EGR solenoid valve 20.

The internal combustion engine 1 is controlled by an electronic control unit 21, which supervises the operation of all the components of the internal combustion engine 1. The electronic control unit 21 is connected to a sensor 22 which measures the temperature Taircole the pressure Paircoldell the air present in the intake manifold 4, to a sensor 23 which measures the rotation speed of the internal combustion engine 1, and to a sensor 24 (typically a linear oxygen probe of the UHEGO or UEGO type - of a known type and not described in detail) which measures the air / fuel ratio of the exhaust gases upstream of the catalyst 11.

The method implemented by the electronic control unit 21 for estimating the exhaust gas flow rate is described below.

First of all, it is important to point out that in order to guarantee the reliability and correct operation of the sensor 24 (that is, for example, the UEGO-type oxygen linear probe) which measures the air / fuel ratio of the exhaust gases, the sensor 24 must keep the internal temperature as stable as possible.

To meet this need, the internal combustion engine 1 is therefore equipped with a CS controller which is designed to control the sensor 24, is connected to the electronic control unit 21 and to the sensor 24 and is arranged, according to a first variant, near the sensor 24 or, according to an alternative variant, directly inside the electronic control unit 21.

The CS controller is designed to ensure that the internal temperature of the sensor 24 is kept constant as the surrounding conditions vary, which are typically represented by the flow rate of the exhaust gases passing through the sensor 24 and the temperature of the exhaust gas flow which pass through sensor 24.

The CS controller is equipped with a heater, which is designed to supply electrical power P which, by the Joule effect, is transformed into thermal power, in order to keep the internal temperature of the sensor 24 constant.

In particular, the estimation method envisages determining, in a preliminary setting and fine-tuning phase, a reference temperature Tref value for sensor 24.

According to a first variant, this reference temperature Tref value is constant and, preferably, between 760 ° C and 850 ° C.

Furthermore, according to a preferred embodiment, the reference temperature value Tref is determined so that it is greater than the exhaust gas temperature Tg; this condition occurs particularly in the case of internal combustion engines 1 compression ignition engines, in which the average temperature Tg_avg of the exhaust gases is lower than in the case of internal combustion engines 1 with controlled ignition.

The CS controller is therefore set up to compare the reference temperature Tref value with an internal temperature of the sensor 24. The internal temperature of the sensor 24 is determined by the CS controller according to the resistance R (Tref) of the heater inside the sensor. 24 itself. Clearly depending on the outcome of the comparison between the reference temperature Tref value and the internal temperature of the sensor 24, the CS controller is set up to control the heater and vary the supplied electrical power P which, due to the Joule effect, is transformed into thermal power. , in order to keep the internal temperature of the sensor constant 24.

The internal temperature of the sensor 24 is variable according to a plurality of parameters such as the flow rate á¹ of the exhaust gases that hit the sensor 24 and the temperature Tg of the exhaust gases that hit the sensor 24.

In other words, the electronic control unit 21 is configured to determine the electrical power P to be supplied to the sensor 24 to keep the sensor 24 itself at a constant temperature and to estimate the flow rate á¹ of the exhaust gases as a function of the power P to be supplied to the sensor 24 to maintain the sensor 24 itself at a constant temperature.

Consequently, also the electrical power P to be supplied to the sensor 24 to keep the sensor 24 itself at a constant temperature is variable according to the pressure of the exhaust gases which strike the sensor 24, the flow rate á¹ of the exhaust gases which strike the sensor. sensor 24 and the temperature Tg of the exhaust gases which strike the sensor 24; and since the pressure value ps of the exhaust gases in the vicinity of the sensor 24 is estimated by the electronic control unit 21 and varies in a limited way during normal operation of the internal combustion engine 1 while the temperature Tg of the exhaust gases affecting the sensor 24 can be determined through the use of a sensor or estimated by the electronic control unit 21 (for example through the method described in the patent application EP-A1-2110535), knowing the electrical power P to be supplied to the sensor 24 for keeping the sensor 24 itself at a constant temperature it is possible to trace the flow rate á¹ of the exhaust gases that hit the sensor 24.

The CS controller is therefore made in such a way as to work in closed loop, determining the internal temperature of the sensor 24 and modulating the electric heating power P which is supplied to the sensor 24 itself.

The electronic control unit 21 is also configured to estimate the flow rate á¹ of the exhaust gases as a function of the electrical power P to be supplied to the sensor 24 in order to keep the sensor 24 itself at a constant temperature.

The electric heating power P supplied to the sensor 24 must balance the thermal power that the sensor 24 transfers, when in use, to the exhaust gases. The thermal power that the sensor 24 transfers to the exhaust gases is a function of both the flow rate á¹ of the exhaust gases and the temperature Tg of the exhaust gases that strike the sensor 24. This balance between the electric heating power P supplied to the sensor 24 and the thermal power that the sensor 24 transfers to the exhaust gases can be expressed through the following equation:

εd * Ps -qtot = ∠† Ä– [1]

In which:

εd thermal power coefficient supplied to sensor 24;

Electric heating power P supplied to the sensor 24 and known by the electronic control unit 21;

qtotal power / total heat transferred from the sensor 24 to the exhaust gases; And

∠† Ä– increase of energy supplied to sensor 24 in the unit of time.

In which:

qtot = qconvqirr [2]

with:

qconv heat transferred by convection from the sensor 24 to the exhaust gases; And

qirrheat transferred by radiation from sensor 24 to the exhaust gases.

Substituting equation [2] into equation [1] it results that:

εd * Ps -qconv -qirr = ∠† Ä– [3]

It therefore appears that:

V 2 â € ¢

ε eff

<d> −hâ ‹... Asâ‹ ... <(> Tref âˆ'Tg <)> âˆ'Asâ ‹... q i <â € ²â € ²> rr = ∠† E

R (T) [4]

ref

In which:

The effective voltage supplied to the sensor 24 by the temperature controller CS and known by the electronic control unit 21;

R (Tref) heater resistance of sensor 24, function of the Tref value of reference temperature for sensor 24;

h heat exchange coefficient;

A heat exchange area between the sensor 24 and the exhaust gases;

Three reference temperature value for sensor 24; And

Tgtemperature of the exhaust gases hitting the sensor 24.

In stationary conditions, equation [4] can be simplified by assuming that:

- the increase ∠† Ä– of energy supplied to sensor 24 in the unit of time is negligible (i.e. considering that in stationary conditions the ratio between the electric heating power P supplied to the sensor 24 and the thermal power the sensor 24 yields to the exhaust gases); is that

- the heat transferred by radiation per unit of time from the sensor 24 to the exhaust gases is negligible or comparable to the heat transferred by convection per unit of time from the sensor 24 to the exhaust gases.

By simplifying equation [4] it is therefore possible to obtain the heat exchange coefficient h as follows: h = â ‹… ε â‹… P

Asâ ‹… (Tref − T g) d S

V 2

P = eff [5] s R (T ref)

As better illustrated in figure 2, the electronic control unit 21 is therefore configured to calculate the flow rate á¹ of the exhaust gases as follows:

- the Ï Model calculation block is designed to receive the exhaust gas temperature Tg and the exhaust gas pressure value ps in the vicinity of the sensor 24 and outputs the density value of the exhaust gases in the vicinity of the sensor 24 through the ideal gas equations;

- as described in the preceding discussion, the calculation block f1 is able to receive the exhaust gas temperature Tg), the reference temperature Tref value for the sensor 24 and the electric heating power value P supplied to the sensor 24 and to output the heat exchange coefficient h through the system of equations described above;

- the calculation block f2 is able to receive the heat exchange coefficient h at the input, calculate the speed of the gases in proximity to the sensor 24 and supply at the output the average speed Vp of the exhaust gases inside the duct 10 of discharge through, for example, King's law; And

- the Mass Flow Model calculation block is able to receive the average speed Vp of the exhaust gases in the vicinity of the sensor 24 and the density of the exhaust gases in the vicinity of the sensor 24 and to supply the gas flow rate at the outlet discharge through the flow equation in the hypothesis of one-dimensional flow.

It has been experimentally verified that the average percentage error in estimating the flow rate á¹ of the exhaust gases with the estimation method described up to now is less than 5%.

It is also important to remember that, in stationary conditions, it occurs that:

á¹ AFMá¹ EGR = á¹ Cyl [6]

in which:

á¹ AFM flow rate of air sucked in by the internal combustion engine 1 and measured by the mass air flow meter 7 *;

á¹ EGR Air flow from the recirculation of flue gases; And

á¹ Cylinders of air inlet to cylinders 3.

Typically, the estimate of the flow rate á¹ Cyldâ € ™ air entering the cylinders 3 is carried out using the â € œSpeed Densityâ € model and is adequately robust and precise.

Under certain conditions, in particular with the EGR solenoid valve 20 closed and therefore the flow rate á¹ EGRdâ € ™ air coming from the recirculation of the flue gases zero, it occurs that the flow rate á¹ AFMdâ € ™ air sucked in by the internal combustion engine 1 is detected from the flow meter 7 * coincides with the flow rate á¹ Cyldâ € ™ air entering the cylinders, that is:

á¹ AFM = á¹ Cyl [7]

Furthermore, always in the case of stationary conditions, it occurs that:

á¹ AFMá¹ FUEL = á¹ [8]

in which:

á¹ AFM flow rate of air sucked in by the internal combustion engine 1 and measured by the mass air flow meter 7 *;

á¹ FUEL Flow of fuel entering the cylinders 3 (the value is known and supplied by the electronic control unit 21); And

á¹ flow rate of the exhaust gases.

Substituting equation [7] into equation [8], it is immediate that:

á¹ Cylá¹ FUEL = á¹ e

á¹ Cyl = á¹ - á¹ FUEL [9]

As previously mentioned, the estimate of the flow rate á¹ Cyldâ € ™ air inlet to cylinders 3 is made using the â € œSpeed Densityâ € model with the following formula:

á¹ SD = Î · V * Vcyl * Ï * n / 2 [10]

in which

á¹ SD air inlet flow calculated with the Speed Density model;

Î · Volumetric filling coefficient;

Vcylvolume of cylinders 3 / displacement of internal combustion engine 1 [m <3>];

Ï density of gases entering internal combustion engine 1; And

n number of engine revolutions per unit of time.

Under these conditions it is possible to correct the estimate of the exhaust gas flow rate á¹, in particular by correcting the calculation of the heat exchange coefficient h.

In fact, under these conditions it is valid that:

Î · V * Vcyl * Ï * n / 2 = á¹ - á¹ FUELe

á¹ = Î · V * Vcyl * Ï * n / 2 á¹ FUEL [11]

The formula [11] therefore allows to calculate the flow rate á¹ of the exhaust gases by means of the â € œSpeed Densityâ € model less than the fuel flow á¹ FUEL entering the cylinders 3. Clearly, the flow rate value á¹ of the exhaust gases calculated by the â € œSpeed Densityâ € model can be compared with the exhaust gas flow rate á¹ calculated using the estimation method shown in Figure 2 and the exhaust gas flow rate á¹ calculated using the â € œSpeed Densityâ € model can be used to update the calculation block f1 which outputs the heat exchange coefficient h in order to strengthen the estimation method described above.

The estimate of the exhaust gas flow rate can be used by the electronic control unit 21 for various purposes, some of which will be described below.

According to a first embodiment, it is possible to express the balance in scope as illustrated in equation [8], from which it derives that:

á¹ AFM = á¹ - á¹ FUEL [12]

in which:

á¹ FUEL Flow of fuel entering the cylinders 3 (the value is known and supplied by the electronic control unit 21);

á¹ exhaust gas flow rate estimated using the estimation method described above; And

á¹ AFM Air flow intake by internal combustion engine 1.

The flow rate á¹ AFMdâ € ™ air sucked in by the internal combustion engine 1 can therefore alternatively be detected by the flow meter 7 * or calculated by means of the difference in equation [12].

The implementation of the previously described estimation method for the flow rate á¹ of the exhaust gases can therefore make it possible to eliminate the mass flow meter 7 * since the flow rate á¹ AFMdâ € ™ air sucked in by the internal combustion engine 1 is therefore calculated by means of the difference of equation [12].

Alternatively, the implementation of the estimation method described above for the flow rate á¹ of the exhaust gases can make it possible to carry out checks on consistency with the flow rate value á¹ AFMdâ € ™ of the intake air detected by the flow meter 7 *.

Furthermore, the flow rate value á¹ AFMdâ € ™ air detected by the flow meter 7 * becomes less reliable with the passage of time as the flow meter 7 * considerably degrades its performance (for example, it is possible to consider passing from a dispersion initial measurement of 4% at a measurement dispersion of 15%) and the implementation of the estimation method described above allows to obtain a very precise estimate of the flow rate á¹ of the exhaust gases which can be used to correct the flow rate á¹ AFM of air sucked in by combustion engine 1 detected by mass flow meter 7 *. In other words, the electronic control unit 21 is configured to detect through the mass flow meter 7 * the flow rate á¹ AFMdâ € ™ air sucked in by the internal combustion engine 1; compare the flow rate value á¹ AFMdâ € ™ air sucked in by the internal combustion engine 1 detected by the flow meter 7 * with the flow rate value á¹ AFMdâ € ™ air sucked in by the internal combustion engine 1 determined as a function of the flow rate á¹ FUEL of fuel entering the cylinders 3 and the flow rate á¹ of the exhaust gases produced by the combustion of the internal combustion engine 1 estimated with the method described above; and update the flow meter 7 * according to the comparison between the flow rate value á¹ AFMdâ € ™ of the air sucked in by the internal combustion engine 1 detected by the flow meter 7 * and the flow rate value á¹ AFMdâ € ™ of the air taken in by the internal combustion engine 1 determined as a function of the flow rate á¹ FUEL of fuel entering the cylinders 3 and of the flow rate á¹ of the exhaust gases produced by the combustion of the internal combustion engine 1 estimated with the method described above.

According to a further embodiment (not shown in detail), the internal combustion engine 1 comprises an EGR gas recirculation circuit divided into a low pressure branch and a high pressure branch, in addition to a mass flow meter 7 * and a sensor 24 located immediately downstream of the turbine 13 of the turbocharger 12 and upstream of the catalyst 11.

In other words, the electronic control unit 21 is configured to estimate the flow rate á¹ of the exhaust gases produced by the combustion of the internal combustion engine 1 to be emitted into the atmosphere according to the method described in the preceding discussion; determine both the exhaust gas flow á¹ EGR_LP recirculated through the low pressure LP branch of the EGR circuit of the internal combustion engine 1 and the exhaust gas flow á¹ EGR_HP recirculated through the high pressure HP branch of the EGR circuit of the combustion engine 1 internal according to the flow rate á¹ of the exhaust gases produced by the combustion of the internal combustion engine 1; and controlling the internal combustion engine 1 according to the exhaust gas flow á¹ EGR_LP recirculated through the low pressure LP branch of the EGR circuit of the internal combustion engine 1 and the exhaust gas flow á¹ EGR_HP recirculated through the high pressure HP branch of the EGR circuit of the internal combustion engine 1.

In this case, the balance of the flow rates can be expressed through the system of two equations in two unknowns that follows:

á¹ AFMá¹ EGR_LPá¹ EGR_HP = á¹ SD

á¹ AFMá¹ FUEL = á¹ S -á¹ EGR_LP [13]

in which:

á¹ AFM flow rate of air sucked in by the internal combustion engine 1 and measured by the mass air flow meter 7 *;

á¹ FUEL Flow of fuel entering the cylinders 3 (the value is known and supplied by the electronic control unit 21);

á¹ EGR_LP Exhaust gas flow recirculated through the low pressure branch of the EGR circuit of the internal combustion engine 1;

á¹ EGR_HP Exhaust gas flow recirculated through the high pressure branch of the EGR circuit of the internal combustion engine 1;

á¹ SD air flow in entry to cylinders 3 calculated with the Speed Density model; And

á¹ Exhaust gas flow through sensor 24 and obtained through the estimation method described above.

In the system of two equations [13], the unknowns are represented by the exhaust gas flow á¹ EGR_LP recirculated through the low pressure branch of the EGR circuit of the internal combustion engine 1 and by the exhaust gas flow á¹ EGR_HP recirculated through the high branch internal combustion engine 1 EGR circuit pressure. The system of two equations [13] is therefore easily solved and allows you to establish how the flow rate is divided in an EGR gas recirculation circuit divided into a low pressure branch and a high pressure branch.

According to a further embodiment (not shown in detail), the internal combustion engine 1 comprises an EGR gas recirculation circuit divided into a low pressure branch and a high pressure branch, in addition to a mass flow meter 7 * and a sensor 24â € ™ placed immediately downstream of the catalyst 11.

In this case, the balance of the flow rates can be expressed through the following equation:

á¹ AFMá¹ FUEL = á¹ â € ™ S [14]

in which:

á¹ AFM flow rate of air sucked in by internal combustion engine 1 and measured by mass flow meter 7 *;

á¹ FUEL Flow of fuel entering the cylinders 3 (the value is known and supplied by the electronic control unit 21); and

á¹ â € ™ Discharge of the exhaust gases through the sensor 24â € ™ located immediately downstream of the catalyst 11 and obtained through the estimation method described above.

Knowing the flow rate á¹â € ™ S of the exhaust gases through the sensor 24â € ™ placed immediately downstream of the catalyst 11 allows to optimize the management of the downstream devices (for example of the SCR - selective catalytic reduction system).

According to a further embodiment (not shown in detail), the internal combustion engine 1 comprises a number of NOx sensors typically placed downstream of the catalyst 11 and / or downstream of the SCR system - selective catalytic reduction (if present) and , consequently, downstream of the sensor 24. Estimating the flow rate á¹ of the exhaust gases by means of the method described above allows to know with considerable precision also the flow rate of exhaust gases that hits the other NOx sensors with evident advantages both in terms precision and in terms of response dynamics.

Finally, the estimate of the exhaust gas flow rate á¹ can be used to estimate a further quantity of the exhaust system, namely the exhaust pressure P3.

In fact, the manufacturers of turbines 13 typically provide the characteristic curves of the turbines 13 themselves which are represented by a bundle of curves (in the case of a variable geometry turbine 13 - also known as VGT) or by a single curve (in the case of a turbine 13 with fixed geometry) in the flow plane á¹ of the exhaust gases / ratio P3 / P4.

Therefore the relationship between the exhaust pressure P3 and the exhaust gas flow rate á¹ can be expressed as follows:

P3 / P4 = f (á¹, posvgt)

In which:

P4 pressure downstream of the turbine 13; the value of the pressure P4 downstream of the turbine 13 can be estimated by means of the updating method described in patent application BO2011A000213; And

P3 discharge pressure upstream of the turbine 13;

á¹ flow rate of the exhaust gases through the sensor 24 estimated with the method described above; And

control position of turbine 13 in the case of variable geometry turbine 13 - also known as VGT.

Knowing the flow rate á¹ of the exhaust gases through the sensor 24 which is estimated with the method described above, the position of the control of the turbine 13 in the case of turbine 13 with variable geometry and having the characteristic curve of the turbine 13 available, it is immediate to obtain the ratio between the discharge pressure P3 upstream of the turbine 13 and P4 pressure downstream of the turbine 13. Knowing this ratio and having obtained the pressure P4 downstream of the turbine 13 (for example through the updating method described in patent application BO2011A000213) , the discharge pressure P3 upstream of the turbine 13 is also obtained.

The estimate of the discharge pressure P3 just described can also be made in the transient where it is decidedly more reliable than the traditional estimates which are characterized by a high degree of uncertainty, especially in the transient.

In the above discussion, reference was made to the use of a UEGO (Universal Exhaust Gas Oxygen) or UHEGO (Universal Heated Exhaust Gas Oxygen) type linear oxygen sensor 24 which measures the air / fuel ratio of the exhaust for the implementation of the method of estimating the exhaust gas flow rate; it is clear that this method of estimating the flow rate of the exhaust gases can find an advantageous implementation also through the use of other similar heated sensors, such as for example a non-linear sensor (also known as an ON / OFF oxygen sensor that measures the air / fuel ratio of the exhaust gases, a sensor suitable for detecting the concentration of NH3 or NOx, etc.).

The estimation method described up to now has numerous advantages.

In the first place, by simply using the information concerning the sensor 24 and which are already known to the electronic control unit 21, it is possible to obtain a precise and reliable estimate of the exhaust gas flow rate. Furthermore, it is not necessary to insert additional components (sensor 24 is already provided for measuring the air / fuel ratio of the exhaust gases). Finally, the estimation method described above can be easily implemented and does not involve an excessive additional computational burden for the electronic control unit 21.

Claims (1)

CLAIMS 1.- Control method of an internal combustion engine (1) comprising an EGR gas recirculation circuit divided into a low pressure (LP) branch and a high pressure (HP) branch and equipped with an exhaust system for emit the exhaust gases produced by combustion into the atmosphere; the control method includes the phases of: estimate the flow rate (á¹) of the exhaust gases produced by the combustion of the internal combustion engine (1) to be emitted into the atmosphere; determine both the flow rate (á¹ EGR_LP) of the exhaust gas recirculated through the low pressure (LP) branch of the EGR circuit of the internal combustion engine (1) and the flow rate (á¹ EGR_HP) of the exhaust gases recirculated through the branch (HP ) high pressure of the EGR circuit of the internal combustion engine (1) as a function of the flow rate (á¹) of the exhaust gases produced by the combustion of the internal combustion engine (1); And control the internal combustion engine (1) according to the flow rate (á¹ EGR_LP) of the exhaust gases recirculated through the low pressure branch (LP) of the EGR circuit of the internal combustion engine (1) and the flow rate (á¹ EGR_HP) of the exhaust gas recirculated through the high pressure branch (HP) of the EGR circuit of the internal combustion engine (1). 2.- Control method according to claim 1, in which the step of determining both the flow rate (á¹ EGR_LP) of the exhaust gases recirculated through the low pressure branch (LP) of the EGR circuit of the internal combustion engine (1) is the flow rate (á¹ EGR_HP) of the exhaust gas recirculated through the high pressure branch (HP) of the EGR circuit of the internal combustion engine (1) as a function of the flow rate (á¹) of the exhaust gases produced by the combustion of the engine (1) Internal combustion is achieved by means of the following system of equations: á¹ AFMá¹ EGR_LPá¹ EGR_HP = á¹ SD á¹ AFMá¹ FUEL = á¹ S -á¹ EGR_LP in which: á¹ AFM Air flow intake by the internal combustion engine (1); á¹ FUEL Flow of fuel entering the cylinders (3) of the internal combustion engine (1); á¹ EGR_LP Exhaust gas flow recirculated through the low pressure branch (LP) of the EGR circuit of the internal combustion engine (1); á¹ EGR_HP Exhaust gas flow recirculated through the high pressure branch (HP) of the EGR circuit of the internal combustion engine (1); á¹ SDflow of air entering the cylinders (3) of the internal combustion engine (1) calculated with the â € œSpeed Densityâ € model; And á¹ Exhaust gas flow through sensor (24). 3. A control method according to Claim 1 or 2, wherein the exhaust system comprises an exhaust gas collection manifold (5); an exhaust duct (10) connected to the exhaust manifold (5); and at least one sensor (24) housed along the exhaust duct (10) in such a way as to be hit, when in use, by the exhaust gases; the phase of estimating the flow rate (á¹) of the exhaust gases produced by the combustion of the internal combustion engine (1) to be emitted into the atmosphere includes the sub-phases of: - determining the electrical power (P) to be supplied to the sensor (24) to maintain the sensor (24) itself at a constant temperature; And - estimate the flow rate (á¹) of the exhaust gases as a function of the electrical power (P) to be supplied to the sensor (24) to keep the sensor (24) at a constant temperature. 4.- Control method according to Claim 3, wherein the sensor (24) is any one of the following heated sensors (24) housed along the exhaust duct (10) in such a way as to be hit, when in use, from exhaust gases: UEGO (Universal Exhaust Gas Oxygen) or UHEGO (Universal Heated Exhaust Gas Oxygen) linear oxygen sensor (24) designed to measure the air / fuel ratio of exhaust gases, non-linear oxygen sensor (known also as an ON / OFF oxygen sensor) designed to measure the air / fuel ratio of the exhaust gases, a sensor suitable for detecting the concentration of NH3 or NOx, etc. 5.- Electronic control unit (21) for the automotive sector configured to implement, when in use, the control method of a supercharged internal combustion engine (1) according to any one of claims 1 to 4.