GB2491375A

GB2491375A - Method of controlling an internal combustion engine equipped with a turbocharger having a variable geometry turbine

Info

Publication number: GB2491375A
Application number: GB1109163.4A
Authority: GB
Inventors: Fredrik Westin; Lydia Loudjertli; Riccardo Franz Riccardo Turcato
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2011-05-31
Filing date: 2011-05-31
Publication date: 2012-12-05
Also published as: GB201109163D0

Abstract

Disclosed is a method of controlling an internal combustion engine equipped with a turbocharger having a variable geometry turbine. The method comprises setting a desired boost pressure, measuring the current boost pressure and adjusting the current boost pressure as required to meet the set boost pressure based on the difference between the current detected boost pressure and the desired boost pressure. The boost pressure is limited if the pressure detected in the engine is at or above a maximum engine pressure. The method prevents damage to the engine by ensuring that the boost pressure supplied to the engine does not exceed a maximum in cylinder pressure. Also disclosed is a computer program for carrying out the method and an engine control unit (ECU) which uses the program to control an engine.

Description

METHOD FOR OPERATING A TURBODHARGER OF AN IWTERNATJ CCMBLJSTION ENGINE

TECflNICAL FIELD

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

internal combustion engines have an engine block defining at least one cylinder having a piston coupled to rotate a crankshaft.

cylinder head cooperates with the piston to define a combustion chanber.

internal combustion engines, in particular Diesel engines, may be equipped with a forced air system such as a turbocharger? the turbocharger being equipped with a compressor rotationally coupled to a turbine. Rotation of the compressor increases the pressure and the temperature of the air into the combustion chambers to increase power of the engine.

Recent turbochargers have turbines, also known as variable geometry turbines (VGi), that are equipped with a rack of trovable vanes which

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can direct exhaust gas flow onto the turbine blades. The rack position is adjusted via an actuator controlled by an Electronic Control Unit (ECU) *of the engine system. By adjusting the rack position, the vanes rotate in unison to vary the gas swirl thus adjusting the effective size and efficiency of the turbine. The rack position may be varied throughout the engIne Revolutions Per Minute (RPM) range to optimize turbine performance The angle of the vanes can be controlled by suitable control algorithms that use a Proportional Integral and Derivative (PID) controller to control bocst pressure, narrely the differential increase in the air pressure due to the compressor, by regulating the VGT-rack pcsition of the turbine.

The prior art PID operates by reducing the VGT-rack position of the turbine vanes with a constant rate n order to increase boost.

However, with this prior art strategy, a problem arises due to the fact that, beyond a certain level of the V&F-position, the boost increases while at the same tine engine torque decreases due to punping losses, namely due the fact that, in the exhaust stroke, the piston encounters a high resistance due to high pressure in the respective cylinder.

An object of an embodiment of the invention is to improve torque r buildup in turbocharged internal comtustion engines, especially during transients.

Another object of an embodiment of the invention is to improve engine efficiency that also results in irtç roved fuel consumption and better turbine protection against high inlet pressures.

Still another object is to obtain these beneficial effects without using canplex devices, no dedicated sensors, and by taking advantage from the computational capabilities of the Electronic Control Unit (ECU) of the vehicle.

These objects are achieved by a method, by an engine, by an autcwaotive system, by a computer program and 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. ThtRY

An embodiment. of the disclosure provides a method. for operating a turbocharger of an internal combustion engine system, the turbocharger being equipped with a variable geometry turbine VGT having a rack of angularly movable vanes, the method conprising the steps of -setting a desired boat pressure value for the turbocharger, measuring an actual boost pressure value of the turbocharger, -adjusting the boost pressure of the turbocharger on the basis of a boost pressure correction value, determined as a difference between the desired boost pressure value and the actual boost pressure value for the turbocharger, limiting the adjusted boost pressure of the turbocharger to a lower value thereof, if a parameter value indicative of a pressure value within the engine is equal, or higher than, a predetermined pressure parameter value of the engine.

An advantage of this embodiment is that it avoids overshoot of boost pressure and allows to reach the same torque value within a shorter time with respect to the prior art strategy. For example, the same.

torque value may be reached in 10% shorter tine with respect to prior art systenis According to a further erthxixmnt of the invention, the boost pressure of the turbocharger is adjusted regulating a rack position.

An advantage of this ernbodimnt is that it uses the actuation of the rack to adjust the boost pressure. Another advantage is that it allows to limit the turbine boost using a physical parameter and not a series of PID factors, a feature that sinplifies the engine calibration process According to another erthxthznt of the invention, the boost pressure of the turbocharger is limited by a limiting VGT rack position.

An advantage of this embodiment is that it allows to optimize the actuation of the rack of the VGF turbine in order to limit boost over time in such a way to avoid an excessive boost pressure leading to excessive exhaust manifold pressure and subsequently pumping work (PHEP), thus roving engine torque performance.

According to another embodiment of the invention, the predetermined value of the parameter indicative of a pressure value within the engine is chosen as a minimum value between a value that ensures a maximum torque output and a maximum allowed value that ensures turbine durability.

An advantage of this embodiment is that it provides a procedure to protect the turbine fran excessive stress that may compromise its durability.

According to a further embodimant of the invention, the paramater indicative of a pressure value within the engine is a Pump Mean Effective Pressure (PMEP) or an exhaust manifold pressure.

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An advantage of this embodiment is that it uses engine pressure parameters that can be readily calculated or estimated using existing sensors and electronic equiptent on the vehicle.

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According to still another embodiment of the invention, in order to determine an actual value of Pump Mean Effective Pressure (PMEP) an actual cylinder pressure is measured by a cylinder pressure sensor.

An advantage of this embodiment is that it uses a pressure sensor already present on the vehicle.

According to still another SbodLimant of the invention, an actual value of exhaust manifold pressure is estimated taking into account IS an exhaust manifold mass flows estimated temçratures upstream and downstream turbocharger, a map of the exhaust manifold pressure characteristics, a V rack position, and a map of the turbine.

An advantage of this embodiment s that this estimation can be perfond using existing sensors and electronic equipuent on the vehicle.

An embodiment of the invention provides an apparatus for operating a turbocharger of an internal cccnbustion engine system, the turbocharger being equipped with a variable geanetry turbine VGT having a rack of rinvable vanes), the apparatus corrrising: -means for setting a desIred bcost pressure value for the turbocharger, -means for measuring an actual boost pressure value for the turbocharger, means for adjusting the boost pressure of the turbocharger on the basis of a boost pressure correction value, determined as a difference between the desired boost pressure value and the actual boost pressure value for the turbocharger, -means for limiting the adjusted boost pressure of the turbocharger to a lower value thereof, if a parameter value indicative of a pressure value within the engine is equal, or higher than, a predetermined, pressure parameter value of the engine.

Still another extodirrent of *the invention provides an autcnttive system carprising: an internal ccmbustion engine (ICE) equipped with a turbocharger, the turbocharger being equipped with a variable geometry turbine VGT having a rack of movable vanes and an electronic control unit (ECU), wherein the ECU is configured to: -set a desired boost pressure value for the turbocharger, measure an actual boost pressure value for the turbocharger, -adjust the bocst pressure of the turbocharger on the basis of a boost pressure correction value, determined as a difference between the desired boost pressure value and the actual boost pressure value for the turbocharger, -limit the adjusted boost pressure of the turbocharger to a lower value thereof, if a paraneter value indIcative of a pressure value within the engine is equal, or higher than, a S predetermined pressure parameter value of the engine.

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

The computer program product can be entoied 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 electratagnetic signal, said signal being ndulated 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.

BRIE? DESCRIPTtC* OF THE DRAWINGS Figure I 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 sdhermatic illustration of a circuit that actuates the main steps of an embodiment of the method of the invention; FIgure 4 is a schematic illustration of another circuit that actuates the main steps of another embodiment of the method of the invention; Figure 5 is a schematic illustration of the main component of an exhaust manifold estimation; Figure 6 is a graph of boost pressure over time according to the prior art and according to an embodiment of the invention; Figure 7 is a graph of Pump Mean Effective Pressure (PMEP) according to the prior art and according to an enibodiment of the invention; and Figure 8 is a graph of torque over time according to the prior art and according to an embodiment of the invention.

DEIMIZ) DESC1CEFflQ OF ThE DIWIMGS Preferred embodiments will now be described with reference to the S enclosed drawings.

Some embodiments may include an automotive system 100, as shown in Figures 1 and 2, that includes an internal cant ustion engine (ICE) 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 cartnunicaton with a high pressure fuel pi.mp 180 that increase the pressure of the fuel received a fuel source 190. Each of the cylinders 125 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 pcrt 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 ant. ient environment to the intake manifold 200. In other errbodiments, a throttle body 330 may be provided to regulate the flow of air into the manifold 200. In this example, a forced air system such as a turbocharger 230, having a compressor 240 rotationally coupled to a turbine 250 is provided. Rotation of the compressor 240 increases the pressure and temperature of the air in the duct 205 and manifold 2.00.

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, by means of a movable VGT rack 252, to alter the flow of the exhaust gases through the turbine 250.

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. Sate examples of aftertreatment devices 280 include, but are not limited to, catalytic converters (two and three way), oxidation catalysts, lean N0 traps, 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 sysem 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 automctive system 100 nay further include an electronic control unit (ECU) 450 in conmunication with one or more sensors and/or devices associated with the ICE 110. The ECU 450 nay receive input signals from various sensors configured to generate the signals in propcrtion to var±ous 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 or cylinder pressure sensor 360, coc..lant and oil temperature and level sensors 380, a fuel rail pressure sensor 400, a cain 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 nay 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 /GT actuator 290, and the cant phaser 155. Note, dashed lines are used to indicate coninunication between the ECU 450 and the various sensors and devices, but sate are omitted. for clarity.

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

The various embod.inent of the invention nay be actuated taking advantage of the properties and performance of the variable geanetry turbine (V&) 250 of the turbocharger 230. This turbine 250 is equipped with a rack 252 of movable vanes 254 which can direct exhaust flow onto the turbine blades. The position of the rack 252 is adjusted via an actuator 290 controlled by the Electronic Control Unit (ECU) 450 of the engine system. By adjusting the rack 252 position, the vanes 254 rotate in unison to vary the gas swirl angle.

The rack 252 position nay be varied throughout the engine Revolutions Per Minute (RPM) range to optimize turbine performance. 2.5

More specifically, Figure 3 shows a schematic illustration of a circuit that actuates the iiain steps of an embodiment of the method of the invention.

S The circuit of Figure 3 has an adder that receives a first sigral Bpdes that represents a desired boost pressure value Bpdes for the turbocharger 230, and a second signal Bpmeas that represents an actual boost pressure value Bpmeas of the turbocharger 230.

The actual boost pressure value Bpmeas can be measured (in block 32) by an intake manifold pressure sensor.

The adder determines a boost pressure correction value E as a difference between the desired boost pressure value Bpdes and the actual boost pressure value Bpmeas of the turbocharger 230 and the boost pressure correction value E is sent to a controller 10.

The controller 10 may be a Proportional integral and Derivative (PID) controller * Then the controller 10 calculates a VGP rack 252 position value Rpos that may be fed to the actuator 290 of the VGT turbine 250 to obtain the desired boost pressure value Bpdes.

To avoid an excessIve bst pressure especially in case of transients, namely the operation of the turbocharger 230 during acceleration of the vehicle, the rack position may be limited using a different VGT rack position value RposPMEP as a function of a pressure parameter representative of the pressure inside a cylinder 125 of the engine 110.

The limiting VGT rack position value RposPMEP may be determined by establishing a limiting condition.

First, an actual cylinder pressure value Ap is measured (in block 15) by a cylinder pressure sensor 360 and,. on the basis of such value Ap, an actual value of Pump Mean Effective Pressure value PMEPest is determined (in block 30).

The pressure value in each cylinder nay be measured by a respective pressure sensor 360 or, in sane autorrotive systems, a single pressure sensor 360 may be provided in one cylinder and the pressure in the other cylinders may be estimated on the basis of the measurement of the sensor 360.

The actual value of Pump Mean Effective Pressure PMEPe5t is compared (in block 20) wIth a predetermined Pump Mean Effective Pressure PtPnaxtq value.

The predetermined Pump Mean Effective Pressure PMEPmaxtq value stored in 40 is a napped value as a function of engine speed and torque and nay be calibrated for each engine system.

In case the actual PMEP value PMEPest is equal to, or higher than, the predetermined RICE' value PtlEPmaxtq, a limiting VGT rack position value RposPMEP is determined (in block 31) and is fed to the actuator 290 of the VGT turbine 250, instead of the VGT rack 252 position value Rpos calculated without applying the limiting condition.

The V rack position value Rpos ENEP may be chosen in such a way to maintain constant the predetermined PMEP value R'ThPest during the transient operation of the turbocharger 230.

In general therefore, the boost pressure of the turbocharger is adjusted. with a boost pressure correction value, determined as a difference between the desired boost pressure value and the actual boost pressure value for the turbocharger Moreover, the adjusted bocst pressure of the turbocharger nay be limited with a lower value thereof, if a pressure parameter value of the engine system is equal, or higher than., a predetermined pressure parameter of the engine system.

\j alternative embodiment of the invention, operating on the sane principle, is schematically shown with the aid of the circuit of figure 4.

Also in this case, a desired boost pressure value Bpdes is set for the turbocharger 230 and an actual boost pressure value Bpmeas is measured for the turbocharger 230 and the boost pressure required from the turbocharger 230 is adjusted by regulating the VGT rack position, using a boost pressure correction value E determined as a difference between the desired boost pressure value Bpdes and the actual bocst pressure value Bpmeas of the turbocharger 230.

The boost pressure correction value E is sent to controller 10 that determines a VGT rack position value Rpos to be used for obtaining the desired boost pressure value Bpdes In this case, a limiting VGT rack position value RposEp to be applied to the position of the vanes 254 of the turbine 250, in order to avoid an excessive boost pressure, nay be determined in the following way.

Eirst, an actual exhaust manifold pressure value EPest is estimated in block 50 and the estimated exhaust manifold pressure value EPest is compared with a predetermined exhaust manifold pressure value Epnaxtq for maximum torque.

The predetermined exhaust manifold pressure value Epnaxtq value stored in 60 is a mapped value as a function of engine speed and torque and may be calibrated for each engine system.

In case the estiiiated exhaust manifold pressure value EFest is equal, or higher than, the predetermined exhaust manifold pressure value Epmaxtq (block 25), the limiting GT rack position value RposEp is fed to the actuator 290 of the VGT turbine 250 The VGT rack position value RposEp is chosen in such a way to maintain the predetermined exhaust manifold pressure value Epmaxtq during the transient operation of the turbocharger.

In this case a safety condition can be employed, namely choosing as a predetermined exhaust manifold pressure value the minimum value between the predetermined exhaust manifold pressure value Epntaxtq that ensures a maximum torque output and a maximum allowed value that ensures turbine durability.

As visible in figure 5, the actual value Epest of exhaust manifold pressure is estimated (in block 50), taking into account an exhaust manifold air mass flow in, an estiixated temperatures upstream T and downstream the turbocharger, a map of the exhaust system pressure characteristics, a VGT rack 252 position, and a map of the turbine.

The turbine map describes turbine pressure ratio as function of air mass flow or, more specifically, it is canpc.sed by a lookup table of pressure ratio as a function of air mass flow, reduced with inlet pressure and tenwrature.

Figure 6 is a graph of boost pressure over time according to the prior art (curve 74) and according to an emt:thment of the invention (curve 76).

Curve 74 results from prior art VGT actuation strategy, depicted as dotted curve 70, which leads to overshoot of the boost pressure curve 74, while curve 76 results fran the v&r actuation strategy according to an embodiment of the invention that reduces boost demand.

The prior art strategy leads to a subS-optimal R4EP curve 80, depicted in fig 7, while the VGr actuation strategy according to an embodiment of the invention leads to an improved E'MEP curve 82 that leads to a sensible torque increase.

in fact in figure 8 torque increase curve 92 is represented, compared

to prior art strategy torque curve 90.

While at least one exemplary enbdixrent has been presented in the foregoing samtary and detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary entodiment or exemplary ertodinents are only e:anples, and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing surttrry and detailed description will provide those skilled in the art with a convenient S 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 R urn PID controller measure of cylinder pressure minimum rack position for maximum torque calculation 25 minimum rack position for maximum torque calculation actual PMEP calculation 31 determination of limiting VGT rack positionS 32 measuring boost pressure PMEP for maximum torque 50 exhaust pressure estimator exhaust manifold pressure value for maximum torque

prior art VGT actuation strategy cune

72 VGT actuation strategy curve

74 prior art boost pressure curve

76 optimized. boost pressure curve

prior art PMEP curve

82 optimized PMEP curve

prior art torque curve

92 optimIzed torque curve 100 autcinotive system internal combustion engine (ICE) engine block cylinder cylinder head 135 camshaft piston crankshaft combustion chamber cain phaser 160 fuel injector fuel 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 250 turbine 252 movable VGr rack 254 vanes 260 intercooler 270 exhaust system.

275 exhaust pipe 280 exhaust aftertreatrtnt device 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 cylinder pressure sensor 38.0 coolant and oil temperature and level sensors 400 fuel rail pressure sensor 410 cam position sensor 420 crank position sensor 430 exhaust pressure and temperature sensor 445 accelerator pedal position sensor 450 electronic control unit (ECU) 460 data carrier aanc

Claims

1. A method for operating a turbocharger (230) of an internal combustion engine system, the turbocharger (230) being equipped with a variable geometry turbine VGT (250) having a rack (252) of angularly movable vanes (254), the method comprising the steps of: -setting a desired boost pressure value (Bpdes) for the turbocharger (230), -measuring an actual boost pressure value (Bpmeas) of the turbocharger (230), -adjusting the boost pressure of the turbocharger (230) on the basis of a boost pressure correction value (E), determined as a difference between the desired boost pressure value (Spdes) and the actual boost pressure value (B.pmeas) for the. turbocharger (230), -limiting the adjusted boost pressure of the turbocharger (230) to a lower value thereof, if a parameter value (Pt4EPest,EPest) indicative of a pressure value within the engIne (110) is equal, or higher than, a predetermined pressure parameter value (PMEPmaxtq, Eprraxtq) of the engine (110).

2. A method according to claim 1, wherein the boost pressure of the turbocharger (230) s adjusted regulating a rack position value (Rpos).

3. A method according to claim 2, wherein the adjusted boost pressure of the turbocharger (230) is limited by limiting a VGT rack position.

4. A method according to claim L wherein the predetermined value of the parameter indicative of a pressure value within the engine (110) is chosen as a minimum value between a value that ensures a maximum. torque output and a maximum allowed value that ensures turbine, durability.

5. A method according to claim 1, wherein the parameter indicative of a pressure value within the engine (110) is a Pump Mean Effective Pressure (PMEP) or an exhaust manifold pressure.

6. A method according to claim 5, wherein to determine an actual value of Pump Mean Effective Pressure (RMEPe5t), an actual cylinder pressure value (Ap) s measured by a cylinder pressure sensor (360).

7. A method according to claim 5, wherein an actual value of exhaust manifold pressure (EPest) is estimated taking into account an exhaust manifold mass flow value On), estimated temperatures upstream (Tb) and downstream (Ta) of the turbocharger, a VGT rack (252) position and a map of the turbine.

8. An apparatus for operating a turbocharger (230) of an internal combustion engine system, the turbocharger (230) being equipped with a variable geattetry turbine V (250) having a rack (252) of movable vanes (254), the apparatus comprising: means for setting a desired boost pressure value (Bpdes) for the turbocharger (230), -means for measuring an actual boost pressure value (Bpmeas) for the turbocharger (230), -neans for adjusting the boost pressure of the turbocharger (230) on the basis of a boost pressure correction value (E), determined as a difference between the desired boost pressure value (Bpdes) and the actual boost pressure value (Bpmeas) for the turbocharger (230), means for limiting the adjusted boost pressure of the turbocharger (230) to a lower value thereof, if a parameter value (PMEPest,EPest) indicative of a pressure value within the engine (110) is equal, or higher than, a predetermined pressure parameter value (PMEPrtaxtq,Epmaxtq) of the engine (110).

9. An automotive system (100) comprising: an internal combustion engine (ICE) (110) equipped with a turbocharger (230), the turbocharger (230) being equipped with a variable geometry turbine VG (250) having a rack (252) of movable vanes (254) and an electronic control unit (ECU) (450), wherein the ECU (450) is configured to: -. set a desired boost pressure value (Bpes) for the turbocharger (230), -measure an actual boost pressure value (Bpmeas) for the turbocharger (230), -adjust the boost pressure of the turbocharger (230) on the 26.basis of a boost pressure correction value (E), determined as a difference between the desired boost pressure value (Bpdes) and the actual boost pressure value (Bpneas) for the turbocharger (230), -limit the adjusted boost pressure of the turbocharger (230) to a lower value thereof, if a paramster value (PMEPest,EPest) indicative of a pressure value within the engine (110) is equal, or higher than, a predetermined pressure parameter value (PMEPmaxtq,Epmaxtq) of the engine (110).

10. internal combustion engine (110), in particular Diesel engine, the combustion engine (110) being equippe. with a turbocharger (230) and having associated sensors for the measurenent of combustion paramters, the engine canpri sing an Electronic Control Unit (ECU) (450) having a data carrier (460) and an interface bus for connection to sensors measuring parameters of the engine (110), the Electronic Control Unit (450) being configured to execute instructions stored in the data carrier (460) for the actuation of the method according to claims 1-7.

11. A computer program coripri sing a computer-code suItable for performing the method accordIng to any of the claims 1-7.

12. Computer program product on which the computer program according to claim 11 is stored.

13. Control apparatus for an internal combustion engine (110), comprising an Electronic Control Unit (450), a data carrier (460) associated to the Electronic Control Unit (450) and a computer program according to claim ii stored in the data carrier (460).

14. An electrorragnetic signal trodulated as a carrier for a sequence of data bits representIng the computer program according to claim 11.