GB2498355A

GB2498355A - Controlling multiple fuel injections in an i.c. engine

Info

Publication number: GB2498355A
Application number: GB1200380.2A
Authority: GB
Inventors: Giovanni Avolio; Matteo Presot
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2012-01-10
Filing date: 2012-01-10
Publication date: 2013-07-17
Anticipated expiration: 2032-01-10
Also published as: GB201200380D0; GB2498355B

Abstract

An internal combustion engine, eg diesel engine, in which fuel is injected into each cylinder from a fuel rail is operated by determining a first energizing time (ETPil) and a second energizing time (ETMain) for a first (eg pilot) and a second (eg main) fuel injection in the same engine cycle and monitoring the dwell time (DT) between the first and second fuel injections. If the dwell time (DT) is smaller than a predefined critical dwell time (DTcrit) eg the pilot and main injection fuel quantities are hydraulically fused (injection quantity fusion (IQF) mode), the energizing time value (ETMain) of the second injection is corrected (reduced) using a correction factor (KET) which is determined as a function of the fuel quantity values (QMain,QPil) injected in the first and in the second injection, of a fuel rail pressure value (PRail) and of the dwell time (DT) between the first and second fuel injections. The second injection is then performed using the corrected energizing time (ETâ Main). The total quantity injected is thus made equal to the sum of the individual injections in non-IQF mode.

Description

GM Global Technology Operations LLC METHOD FOR OPEF?ATNG AN INTERNAL COMBUSTION ENGINE

TECHNICAL FIELD

The present disclosure relates to a method for operating an internal combustion engine.

BACKGROUND

It is known that an internal combustion engine for a motor vehicle generally comprises an engine block which defines at least one cylinder accommodating a reciprocating piston coupled to rotate a crankshaft. The cylinder is closed by a cylinder head that cooperates with the reciprocating piston to define a combustion chamber. A fuel and air mixture is cyclically disposed in the combustion chamber and ignited, thereby generating hot expanding exhaust gasses that cause the reciprocating movements of the piston. The fuel is injected into each cylinder by a respective fuel injector. The fuel is provided at high pressure to each fuel injector from a fuel rail in fluid communication with a high pressure fuel pump that increase the pressure of the fuel received from a fuel source.

In order to improve the characteristics of exhaust emissions and reduce combustion noise in engines, particularly in Diesel engines having a common-rail fuel injection system, so-called rnultiple fuel injection patterns are adopted.

In a multi-injection pattern the fuel quantity to be injected in each cylinder at each engine cycle is splitted into a plurality of injections.

More specifically, in a multi-injection pattern, for each engine cycle, a train of injections is performed by each injector typically, starting from a pilot injection and following with a main injection, which gives all or most of the torque in an engine cycle, eventually terminating with after and post injections.

In particular, fuel pilot injections are fuel injections in a cylinder of the engine that occur before the Top Dead Center (TDC) of the piston.

The number of injections of the train of injections and their timing is dependent on 1.

the combustion mode and is determined by an Electronic Control Unit of the engine.

The pilot injections have an effect both on the level of combustion noise and exhaust emissions, and their duration or energizing time (El), which is correlated to the fuel quantity injected, is generally mapped in memories of the Electronic Control Unit. The mapped values of the energizing time are predetermined with reference to an injection system having nominal characteristics, i.e. with components having no drifts.

In general, the opening of the injector is obtained by a current impulse and the Energizing Time (ET) is the time correlated to the duration of the impulse and is indicative of the fuel quantity injected.

Moreover, the Dwell Time (DT) between two consecutive fuel injections may be defined as the period between the end of the Energizing Time (ET) of the previous injection and the start of the Energizing Time (El) of the subsequent injection.

In a normal mode of operation known in the art, the Dwell Time may be greater than a critical Dwell Time DT (for example DI> DT,,1 =150 ps) as represented in Figure 3.

ri this case the total quantity injected into a cylinder in a combination of a pilot and a main injection is equal to the fuel quantities injected in the pilot injection and in the main injection, in symbols: OTOT = Q11(ET1) + QMaIJ,(ETMaiO).

Reducing the Dwell Time (DI) between two consecutive injections below a proper critical value (for example DT1 c 150 ps), causes the hydraulic fusion of the pilot and main injection, also referred to Injection Quantity Fusion (IQF). Due the changed dynamic of the needle of the injector, the main result of this operation is the increase of the total injected fuel quantity that depends from the Dwell Time (Dl), and from Rail pressure and Pilot quantity.

In fact, if the injector is energized before it is completely closed, no losses due to the separation from the nozzle seat are produced, so all energy is transformed in potential energy, namely into injector height.

In a IQF mode of operation known in the art, the situation may be represented as in Figure 4.

In this case the total quantity injected into a cylinder in a combination of pilot and main injection is greater than equal to the fuel quantities separately injected by the pilot injection and the main injection, in symbols: QTOT > Q11(ET1) + QMain(ETMaIn).

in Figure 4 the excess fuel quantity is represented by the dashed area 500.

In this case, in order to obtain the same fuel quantity of conventional conditions, on in other word in non-IQF conditions, the Energizing Time of the main injection must be ieduced accordingly.

in the prior art this operation is done by using a lookup table or map to determine a corrected value of the Energizing Time of the main injection.

However, this causes the problem that, in a calibration phase of the engine, a rot of time must be spent to create the lookup table to be used during normal engine operation.

This fact also leads to high calibration costs.

An object of an embodiment of the invention is to provide a reduction of time spent in a calibration phase of the engine and of the associated costs.

Another object is to provide a correction of the quantity of fuel injected in IQF conditions without using complex devices and by taking advantage from the computational capabilities of the Electronic Control Unit (ECU) of the vehicle.

Another object of the present disclosure is to meet these goals by means of a simple, rational and inexpensive solution.

These objects are achieved by a method, by an engine, by an apparatus, by an automotive system, by a computer program and a computer program product, and by an electromagnetic signal having the features recited in the independent claims.

The dependent claims delineate preferred and/or especially advantageous aspects.

SUMMARY

An embodiment of the disclosure provides for a method for operating an internal combustion engine, the engine including a block defining at least one cylinder, wherein a fuel injector is disposed to inject fuel into the cylinder, the fuel being provided to the fuel injector from a fuel rail, the method comprising the steps of: -determining a first Energizing Time value and a second Energizing Time value for performing a first and a second fuel injection into the cylinder in the same engine cycle: -monitoring a Dwell Time between the first and the second fuel injection; and -if the Dwell Time is smaller than a predefined critical Owell Time, correct the Energizing Time value of the second injection using a correction factor, wherein the correction factor is determined as a function of fuel quantity values injected in the first and in the second injection, of a fuel rail pressure value and of the Dwell Time between the first and the second fuel injection; -performing (he second injection using a corrected Energizing Time value.

An advantage of this embodiment is that it allows is to exploit a mathematical law or model that describes the relationship between Energizing Time in case of Injection Quantity Fusion (IQF), and the Energizing Time in a normal condition, in order to use the mathematical law to obtain the desired injected fuel quantity, reducing the time spent in a calibration phase of the engine and also the associate costs.

According to a further embodiment of the invention, the correction factor is calculated by means of a mathematical model, the mathematical model comprising, for each value of the fuel rail pressure and of the injected quantity in the first injection and of the Dwell Time between the first and the second fuel injection, a cubic function of the fuel quantity value injected in the main injection, the cubic function being expressed as: KEEl = a, * Q Main + b1 * Q,2Main + C, Qj,,,1,, + wherein the values of each 11h coefficient a, b, c, d of the cubic function are determined by corresponding functions f1 of the fuel rail pressure value, of the injected quantity in the first injection and of the Dwell Time.

An advantage of this embodiment is that it allows to calculate the contribution to the correction factor for each type of injector, not only for ideal ones, because the coefficient KET divided the Standard El (no IQF) after all compensations due for non ideality and real noise.

According to a further embodiment of the invention, each of the functions f1 determining the values of the cubic coefficients a1, b1, c, d of the cubic function of the fuel quantity value (Quan) can be expressed by a parabolic equation as: = * F, Rail + /9k * rRail + 7 where k, Pk, jk are coefficients determined experimentally as a function of the injected quantity in the first injection and of the Dwell Time between the first and the second fuel injection.

An advantage of this embodiment is that it allows to take into account the effects of different values of the fuel rail pressure, and of the injected quantity of the first injection and the dwell time on the correction factor.

According to still another embodiment of the invention, the first injection is a pilot injection and the second injection is a main injection.

An advantage of this embodiment is that it allows to apply the mathematical model to the most significant case of IQE in an engine cycle.

The invention also provides an apparatus for operating an Internal Combustion Engine1 the engine including a block defining at least one cylinder, wherein a fuel injector is disposed to inject fuel into the cylinder, the fuel being provided to the fuel injector from a fuel rail, the apparatus comprising: -means for determining a first Energizing Time and a second Energizing Time for performing a first and a second fuel injection into the cylinder in the same engine cycle; -means for monitoring a Dwell Time between the first and the second fuel injection; and -means for determining if the Dwell Time is smaller than a predefined critical Dwell Time, -means for correcting means for correcting the Energizing Time value of the second injection using a correction factor, wherein the correction factor is determined as a function of fuel quantity values injected in the first and in the second injection, of a fuel rail pressure value and of the Dwell Time between the first and the second fuel injection; -means for performing the second injection using a corrected Energizing Time.

The invention also provides an automotive system comprising an internal combustion engine, managed by an engine Electronic Control Unit, the engine including a block defining at least one cylinder, wherein a fuel injector is disposed to inject fuel into the cylinder, the fuel being provided to the fuel injector from a fuel rail, wherein the Electronic Control Unit is configured to: -determine a first Energizing Time and a second Energizing Time for performing a first and a second fuel injection into the cylinder in the same engine cycle; -monitor a Dwell Time between the first and the second fuel injection; and -determine if the Dwell Time is smaller than a predefined critical Dwell Time, -correct the Energizing Time value (ETM8th) of the second injection using a correction factor, wherein the correction factor is determined as a function as a function of fuel quantity values injected in the first and in the second injection, of a fuel rail pressure value arid of the Dwell Time between the first and the second fuel injection; -perform the second injection using a corrected Energizing Time.

Both these last two embodiments have the same advantage of the method disclosed above.

The method according to one of its aspects can be carried out with the help of a computer program comprising a program-code for carrying out all the steps of the method described above, and in the form of computer program product comprising the computer program.

The computer program product can be embodied as a control apparatus for an internal combustion engine, comprising an Electronic Control Unit (ECU), a data carrier associated to the ECU, and the computer program stored in a data carrier, so that the control apparatus defines the embodiments described in the same way as the method. In this case, when the control apparatus executes the computer program all the steps of the method described above are carried out.

The method according to a further aspect can be also embodied as an electromagnetic signal, said signal being modulated to carry a sequence of data bits which represents a computer program to carry out all steps of the method.

A still further aspect of the disclosure provides an internal combustion engine specially arranged for carrying out the method claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The various embodiments will now be described, by way of example, with reference to the accompanying drawings, wherein like numerals denote like elements, and in which: Figure 1 shows an automotive system Figure 2 is a cross-section of an internal combustion engine belonging to the automotive system of figure 1; Figure 3 is a diagram that represents a pilot and a main injection according to the

prior art in a non-IQF condition;

Figure 4 is a diagram that represents a pilot and a main injection according to the

prior art in a IQF condition;

Figure 5 is a diagram that represents a pilot and a main injection according to an embodiment of the invention in a IQF condition; Figure 6 is a diagram that represents the relationship between the fuel quantity and the Energizing Time for different pressures of the rail in a non-IOF mode; Figure 7 is a diagram that represents the relationship between the fuel quantity and the Energizing Time for different pressures of the rail in a IQF mode; Figure 8 represents experimental curves of a correction factor as a function of the quantity to be injected for different values of rail pressure, according to an embodiment of the invention; Figure 9 represents estimation curves used in for determining a series of coefficients employed in a mathematical model, according to an embodiment of the invention; and Figure 10 is a flowchart representing IQF managing strategy according to an embodiment of the invention.

DETAILED DESCRIPTION

Exemplary embodiments of the invention will now be described with reference to the enclosed drawings without intent to limit application and uses.

Some embodiments may include an automotive system 1001 as shown in Figures 1 and 2, that includes an internal combustion engine (ICE) 110 having an engine block 120 defining at least one cylinder 125 having a piston 140 coupled to rotate a crankshaft 145.

A cylinder head 130 cooperates with the piston 140 to define a combustion chamber 150.

A fuel and air mixture (not shown) is disposed in the combustion chamber 150 and ignited, resulting in hot expanding exhaust gasses causing reciprocal movement of the piston 140. The fuel is provided by at least one fuel injector 160 and the air through at least one intake port 210. The fuel is provided at high pressure to the fuel injector 160 from a fuel rail 170 in fluid communication with a high pressure fuel pump 180 that increase the pressure of the fuel received from a fuel source 190. Each of the cylinders has at least two valves 215, actuated by a camshaft 135 rotating in time with the crankshaft 145. The valves 215 selectively allow air into the combustion chamber 150 from the port 210 and alternately allow exhaust gases to exit through a port 220. In some examples, a cam phaser 155 may selectively vary the timing between the camshaft 135 and the crankshaft 145.

The air may be distributed to the air intake port(s) 210 through an intake manifold 200. An air intake duct 205 may provide air from the ambient environment to the intake manifold 200. In other embodiments, a throttle body 330 may be provided to regulate the flow of air into the manifold 200. In still other embodiments, a forced air system such as a turbocharger 230, having a compressor 240 rotationally coupled to a turbine 250, may be provided. Rotation of the compressor 240 increases the pressure and temperature of the air in the duct 205 and manifold 200. An intercooler 260 disposed in the duct 205 may reduce the temperature of the air. The turbine 250 rotates by receiving exhaust gases from an exhaust manifold 225 that directs exhaust gases from the exhaust ports 220 and through a series of vanes prior to expansion through the turbine 250. The exhaust gases exit the turbine 250 and are directed into an exhaust system 270. This example shows a variable geometry turbine (VGT) with a VGT actuator 290 arranged to move the vanes to alter the flow of the exhaust gases through the turbine 250. In other embodiments, the turbocharger 230 may be fixed geometry and/or include a waste gate.

The exhaust system 270 may include an exhaust pipe 275 having one or more exhaust aftertreatment devices 280. The aftertreatment devices may be any device configured to change the composition of the exhaust gases. Some examples of aftertreatment devices 280 include, but are not limited to, catalytic converters (two and three way), oxidation catalysts, lean NO, traps 285, hydrocarbon adsorbers, selective catalytic reduction (SCR) systems, and particulate filters. Other embodiments may include an exhaust gas recirculation (EGR) system 300 coupled between the exhaust manifold 225 and the intake manifold 200. The EGR system 300 may include an EGR cooler 310 to reduce the temperature of the exhaust gases in the EGR system 300. An EGR valve 320 regulates a flow of exhaust gases in the EGR system 300.

The automotive system 100 may further include an electronic control unit (ECU) 450 in communication with one or more sensors and/or devices associated with the ICE 110.

The ECU 450 may receive input signals from various sensors configured to generate the signals in proportion to various physical parameters associated with the ICE 110. The sensors include, but are not limited to, a mass airflow and temperature sensor 340, a manifold pressure and temperature sensor 350, a combustion pressure sensor 360, coolant and oil temperature and level sensors 380, a fuel rail pressure sensor 400, a cam position sensor 410, a crank position sensor 420, exhaust pressure and temperature sensors 430, an EGR temperature sensor 440, and an accelerator pedal position sensor 445. Furthermore, the ECU 450 may generate output signals to various control devices that are arranged to control the operation of the ICE 110, including, but not limited to, the fuel injectors 160, the throttle body 330, the EGR Valve 320, the VOT actuator 290, and the cam phaser 155. Note, dashed lines are used to indicate communication between the ECU 450 and the various sensors and devices, but some are omitted for clarity.

Turning now to the ECU 450, this apparatus may include a digital central processing S unit (CPU) in communication with a memory system, or data carrier 460, and an interface bus. The CPU is configured to execute instructions stored as a program in the memory system, and send and receive signals to/from the interface bus. The memory system may include various storage types including optical storage, magnetic storage, solid state storage, and other non-volatile memory. The interface bus may be configured to send, receive, and modulate analog and/or digital signals to/from the various sensors and control devices. The program may embody the methods disclosed herein, allowing the Cpu to carryout out the steps of such methods and control the ICE 110.

More specifically, Figure 5 shows a diagram that represents a pilot and a main injection according to an embodiment of the invention in an IQF condition.

In this case the Energizing Time of the main injection is decreased by a value ET_Main_Decreased that is calculated in order to decrease the quantity of fuel injected in the main injection in such a way as to have a total quantity injected into a cylinder, by the combination of a pilot and of a main injection, substantially equal to the sum of the fuel quantities injected in the pilot injection and in the main injection, in symbols: 0TOT O11(ET1) + QMarn(ET'Main) where ET'Ma is the corrected Energizing Time for the main injection.

To determine the corrected Energizing Time for the main injection ET'Main it must be considered that, in both normal mode (or non-IQF mode) (Figure 6) and IQF mode (Figure 7), the curves that correlate fuel quantity injected in an injection and its Energizing Time for different pressures Praji of the fuel rail 170 are substantially linear.

This allows to find a correction factor to correct the Energizing Time ETM3In in normal mode in order to obtain a corrected Energizing Time ET'M210 to be used in an (OF mode; this allows to inject the same total quantity in a combination of pilot and main injection.

The correction factor KETI may be defined as: El Main nET -ET1 where ETIM0I,, is the Energizing Time for a specific main injection in a non-IQF mode and ET!'MaIn is the Energizing Time for a specific main injection in a IOF mode.

In general, from the curves of Figures 6 and 7 it can be seen that KEr,is a function of the fuel quantity injected in a specific main injection Q,Ma,n, of the fuel quantity injected in a specific pilot injection Qipi,Qt, of the Dwell Time, and of the fuel rail 170 pressure PiRail, fl symbols: KFJ.j = F(Q,M111,, , Qepu 1RuiI) If Paji, pilot injection and Dwell Time are considered fixed for a certain main injection, experimental activity shows that KET may be approximated by a cubic function of the fuel quantity injected in the main injection QMajn, in symbols: (1) = a, * 121 Main + b, * Q12ucnn + Cj * Q1,, + d, Examples of these experimental curves, for different values of Rat, are represented in figure 8.

In order to estimate the values of the cubic coefficients a', b', &, d' of Equation (1), a parabolic estimation can be employed as in Figure 9 varying PR8,,. Therefore for each of the coefficients, a different function V can be written, in symbols: a = = .fji(ag) = f,,, = Each of these functions can be estimated by the following parabolic equation: fI =a *//f +13k *P., -I where k are indexes from Ito IV and 0k, Ph, Yk are coefficients determined experimentally as a function of the injected quantity in the first injection and of the Dwell Time between the first and the second fuel injection.

Figure 10 shows a flowchart of an QF managing strategy according to an embodiment of the invention.

At the start of the procedure, a Dwell Time DT between a pilot and a main injection is evaluated and is compared (black 510) with a Dwell Time critical value DTcr; if Di is greater than DT,1 there is no need to activate an IQF procedure and the Energizing Time for the Main injection can be obtained from calibrated lookup tables in the data carrier 460 associated to the ECU 450 (block 520).

However, if DT < DTc;it then an IQF condition is detected (block 530). In this case a check (block 540) is made to verify if a strategy based on the correction factor KEY according to the various embodiments of the invention is available. If the answer is affirmative, the correction factor is estimated by means of the polynomial estimation above described (block 550); if the answer is negative the Energizing Time for the Main injection in a IQF mode can be obtained from calibrated lookup tables in the data carrier 460 associated to the ECU 450 (block 560).

While at least one exemplary embodiment has been presented in the foregoing summary and detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary and detailed description will provide those skilled in the art with a convenient road map for implementing at least one exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents.

REFERENCE NUMBERS

automotive system 110 internal combustion engine (ICE) engine block cylinder cylinder head camshaft 140 piston crankshaft combustion chamber cam phaser fuel injector l7Ofuel rail fuel pump fuel source intake manifold 205 air intake duct 210 intake air port 215 valves of the cylinder 220 exhaust gas port 225 exhaust manifold 230 turbocharger 240 compressor 244 exhaust line portion 250 turbine 260 intercooler 270 exhaust system 27sexhaust line 280 exhaust aftertreatment device 285 [NT trap 290 VGT actuator 300 EGR system 310 EGR cooler 320 EGR valve 330 throttle body 340 mass airflow and temperature sensor 350 manifold pressure and temperature sensor 360 combustion pressure sensor 380 coolant and oil temperature and level sensors 400 fuel rail pressure sensor 410 cam position sensor 420 crank position sensor 430 exhaust pressure sensor 445 accelerator pedal position sensor 450 electronic control unit (ECU) 460 data carrier 500 excess fuel area 510 block 520 block 530 block 540 block 550 block 560 block

Claims

<claim-text>CLAIMS1. A method for operating an internal combustion engine (110), the engine (110) including a block (120) defining at least one cylinder (125), wherein a fuel injector (160) is disposed to inject fuel into the cylinder (125), the fuel being provided to the fuel injector (160) from a fuel rail (170), the method comprising the steps of: -determining a first Energizing Time value (EL11) and a second Energizing Time value (ETMBIfl) for performing a first and a second fuel injection into the cylinder (125) in the same engine cycle; -monitoring a Dwell Time (DT) between the first and the second fuel injection; and -if the Dwell Time (DT) is smaller than a predefined critical Dwell Time (DTGrIf), correct the Energizing Time value (ETwain) of the second injection using a correction factor (KED), wherein the correction factor (KETI) is determined as a function of fuel quantity values (QMan,QpiI) injected in the first and in the second injection, of a fuel rail (170) pressure value (PRaII) and of the Dwell Time (DT) between the first and the second fuel injection; -performing the second injection using a corrected Energizing Time value (ET'Main).</claim-text> <claim-text>2. A method as in claim 1, in which the correction factor (I<ElI) is calculated by means of a mathematical model, the mathematical model comprising, for each value of the fuel rail (170) pressure (P) and of the injected quantity (Qmajn) in the first injection arid of the Dwell Time (DT) between the first and the second fuel injection, a cubic function of the fuel quantity value (QM9Ifl) injected in the main injection, the cubic function being expressed as: K17, = a, * Q1 Main + b1 * Q12 Main + Cj * Q,M0h, + wherein the values of each i coefficient a1, b, c1, d of the cubic function are determined by corresponding functions f1 of the fuel rail pressure value, of the injected quantity in the first injection and of the Dwell Time.</claim-text> <claim-text>3. A method as in claim 2, in which each of the functions f determining the values of the cubic coefficients a, b', C', d' of the cubic function of the fuel quantity value (QM3In) can be expressed by a parabolic equation as: = * I2w,ii + * Ra)I + 7k wherein 0k pk are parabolic coefficients determined experimentally as a function of the injected quantity (Qmairi) in the first injection and of the Dwell Time (DT) between the first and the second fuel injection.</claim-text> <claim-text>4. A method as in any of the preceding claims, in which the first injection is a pilot injection and the second injection is a main injection.</claim-text> <claim-text>5. An apparatus for operating an Internal Combustion Engine (110), the engine (110) including a block (120) defining at least one cylinder (125), wherein a fuel injector (160) is disposed to inject fuel into the cylinder (125), the fuel being provided to the fuel injector (160) from a fuel rail (170), the apparatus comprising: -means for determining a first Energizing Time value (ET11) and a second Energizing Time value (ET) for a first and a second fuel injection into the cylinder (125) in the same engine cycle; -means for monitoring a Dwell Time (DT) between the first and the second fuel injection; and -means for determining if the Dwell Time (DT) is smaller than a predefined critical Dwell Time (Dicrit), -means for correcting the Energizing Time value (ETM3in) of the second injection using a correction factor (KETi), wherein the correction factor (KETi) is determined as a function of fuel quantity values (QMan,Qpii) injected in the first and in the second injection, of a fuel rail (170) pressure value (PRtI) and of the Dwell Time (OT) between the first and the second fuel injection; -means for performing the second injection using a corrected Energizing Time value (ET'Maifl).</claim-text> <claim-text>6. An automotive system comprising an internal combustion engine (110), managed by an engine Electronic Control Unit (450), the engine (110) including a block (120) defining at least one cylinder (125), wherein a fuel injector (160) is disposed to inject fuel into the cylinder (125), the fuel being provided to the fuel injector (160) from a fuel rail (170), wherein the Electronic Control Unit (450) is configured to: -determine a first Energizing Time value (ET) and a second Energizing Time value (ETMaIn) for a first and a second fuel injection into the cylinder (125) in the same engine cycle; -monitor a Dwell Time (DT) between the first and the second fuel injection; and -determine if the Dwell Time (DI) is smaller than a predefined critical Dwell Time -correct the Energizing Time value (ETM3u,) of the second injection using a correction factor (KET), wherein the correction factor (KETI) is determined as a function as a function of fuel quantity values (QMain,Qp) injected in the first and in the second injection, of a fuel rail (170) pressure value (PR3J) and of the Dwell Time (DT) between the first and the second fuel injection; -perform the second injection using a corrected Energizing Time value (ET'Meifl).</claim-text> <claim-text>7. An internal combustion engine (110) including a block (120) defining at least one cylinder (125), wherein a fuel injector (160) is disposed to inject fuel into the cylinder (125), the fuel being provided to the fuel injector (160) from a fuel rail (170), the engine (110) being controlled by an Electronic Control Unit (450) configured for carrying out the method according to any of the claims 1-4.</claim-text> <claim-text>8. A computer program comprising a computer-code suitable far performing the method according to any of the claims 1-k 9. Computer program product on which the computer program according to claim 8 is stored.10. Control apparatus for an internal combustion engine, comprising an Electronic Control Unit, a data carrier associated to the Electronic Control Unit and a computer program according to claim 8 stored in the data carrier.</claim-text>