GB2520077A

GB2520077A - Method of controlling the temperature of a turbocharger

Info

Publication number: GB2520077A
Application number: GB1319835.3A
Authority: GB
Inventors: Fiorello Losano; Salvatore Mafrici
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2013-11-11
Filing date: 2013-11-11
Publication date: 2015-05-13
Also published as: GB201319835D0

Abstract

A method of controlling a temperature of a turbocharger for an internal combustion engine. The method comprises: (a) calculating a temperature parameter DT of the turbocharger, which is correlated to the temperature of the turbocharger, and which is a function of an exhaust gas mass flow, an exhaust gas temperature drop across the turbine, and an engine speed; (b) determining a time during which said temperature parameter is larger than a temperature parameter threshold; and (d) de-rating the internal combustion engine if said time is larger than a first time interval Ta, in order to lower the temperature of the turbocharger below the turbocharger temperature threshold. The method may further comprise: (c) sending a warning message if the time is smaller than the first time interval, and larger than a second time interval Tb. The de-rating may be performed stepwise.

Description

METHOD OF CONTROLLING THE TEMPERATURE OFA TURBOCHARGER

TECHNICAL FIELD

The present disclosure relates to a method of controlling the temperature of a turbocharger, in particular the oil temperature close to the bearings of the turbocharger shaft.

BACKGROUND

As known, the majority of internal combustion engines are turbocharged. A turbocharger, is a forced induction device used to allow more power to be produced for an engine of a given size. The benefit of a turbo is that it compresses a greater mass of intake air into the combustion chamber, thereby resulting in increased power and/or efficiency.

Turbochargers are commonly used on truck, car, train and construction equipment engines. They are popularly used with Otto cycle and Diesel cycle internal combustion engines and have also been found useful in automotive fuel cells.

In case of high performance engines, the turbocharger temperature, which normally is measured on the bearings of the turbocharger shaft, can overcome very high values, such as 250°C. In such condition the known phenomenon called "oil coking" can occur, that is to say, soot deposit due to high temperature around the bearings of the shaft and consequently sticking of the turbocharger shaft. When the engine is shut off after its usage under severe load conditions, the oil is not anymore circulating and it is exposed to the high temperatures of the turbocharger. In fact the temperatures of the center housing, oil seal, bearings and any oil remaining in the turbo are all elevated above the normal operating temperatures that occurred while the engine was running, since the oil flow is no longer available to carry heat away. The consequence is that, above 250°C, the oil changes its chemical composition.

To avoid oil coking, a known countermeasure is the turbocharger water cooling. This is an additional cooling circuit, which in its basic layout is composed of two pipes, one from the engine to the turbocharger, the other from the turbo to the engine (the return way). In terms of cost the impact of the turbo water cooling on the engine is very remarkable Furthermore, this additional cooling circuit is worsening both engine layout and weight.

Therefore a needexists for a method of controlling the turbocharger temperature, avoiding the use of the turbocharger water cooling.

An object of an embodiment of the invention is to provide a method of controlling a turbocharger temperature, which is effective and easy to be implemented, thus avoiding the use of the water cooling.

Another object is to provide an apparatus which allows to perform the above method.

These objects are achieved by a method, by an apparatus, by an engine, by a computer program and computer program product 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 a method of controlling a temperature of a turbocharger for an internal combustion engine, wherein the method comprises the following steps: a) calculating a temperature parameter of the turbocharger, which is correlated to the temperature of the turbocharger and which is a function of an exhaust gas mass flow, an exhaust gas temperature drop across a turbine and an engine speed, b) determining a time during which said temperature parameter is larger than a temperature parameter threshold, d) de-rating the internal combustion engine if said time is larger than a first time interval, in order to lower the temperature of the turbocharger below a turbocharger temperature threshold.

Consequently, an apparatus is disclosed for performing the method of controlling a temperature of a turbocharger for an internal combustion engine, the apparatus comprising: a) means for calculating a temperature parameter of the turbocharger, which is correlated to the temperature of the turbocharger and which is a function of an exhaust gas mass flow, an exhaust gas temperature drop across a turbine and an engine speed, b) means for determining a time during which said temperature parameter is larger than a temperature parameter threshold, d) means for de-rating the internal combustion engine if said time is larger than a first time interval, in order to lower the temperature of the turbocharger below a turbocharger temperature threshold.

An advantage of this embodiment is that the method provides an easy control of the turbochargertemperature which could cause oil coking, by using a temperature parameter, which is perfectly correlated to the turbocharger temperature and which is calculated on the basis of parameters easy to be measured. By using this method, any water cooling circuit can be avoided.

According to another embodiment, the method further comprises the following step: c) sending a warning message if the time is smaller than the first time interval and is larger than a second time interval.

Consequently, the apparatus also comprises means for sending a warning message if the time is smaller than the first time interval and is larger than a second time interval.

An advantage of this embodiment is that a warning message about the possible future engine de-rating is sent to the driver.

According to a still further embodiment, the engine de-rating is performed stepwise, N times, N being a natural number, each of the steps being proportional to: 1/N x(DT-Dlthr) Consequently, said means for de-rating the internal combustion engine are configured to perform the de-rating stepwise, N times, N being a natural number, each of the steps being proportional to: 1/Nx(DT-Dlthr) An advantage of this embodiment is that the engine de-rating is performed in a smooth and uniform way.

According to still another embodiment, a first portion and a second portion of the first time interval, during which the temperature parameter is larger than the temperature parameter threshold, are separated by a reset time interval, during which the temperature parameter is smaller than the temperature parameter threshold and the first time interval is the sum of the first portion and the second portion if said reset time interval is smaller than a reset time interval threshold.

Consequently, said means for de-rating the internal combustion engine are configured in a way that a first portion and a second portion of the first time interval, during which the temperature parameter is larger than the temperature parameter threshold, are separated by a reset time interval, during which the temperature parameter is smaller than the temperature parameter threshold and the first time interval is the sum of the first portion and the second portion if said reset time interval is smaller than a reset time interval threshold.

An advantage of this embodiment is that in case temperature parameter is overcome in two different and separated time intervals, the time interval for the engine de-rating to be activated will be restarted only if the reset time interval, during which the turbocharger temperature is under control, is sufficiently long.

According to another embodiment, the internal combustion engine also comprises a switchable oil pump and, when the engine is switched off, the switchable oil pump is switched on during a third time interval, if the temperature parameter is larger than the temperature parameter threshold.

Consequently, the apparatus also comprises means to switch on a switchable oil pump during a third time interval, if the temperature parameter is larger than the temperature parameter threshold.

An advantage of this embodiment, is that if the engine is switched off and the turbocharger temperature is still high, the oil will continue circulating, exchanging heat and reducing its temperature, thus avoiding the risk of coking.

According to a further embodiment the temperature parameter threshold ranges between 16 and 18 [kg/s °C/rpmj.

Consequently, said means for de-rating the internal combustion engine are configured to operate when the temperature parameter threshold ranges between 16 and 18 [kg/s °C/rpm].

According to another embodiment, the first time interval ranges between 1600 and 2000 [sL Consequently, said means for de-rating the internal combustion engine are configured to operate when the first time interval ranges between 1600 and 2000 [s].

According to a still further embodiment the reset time interval threshold ranges between and 400 [s].

Consequently, said means for de-rating the internal combustion engine are configured to operate when the reset time interval threshold ranges between 200 and 400 [s].

According to still another embodiment the third time interval ranges between 20 and 40 [SI.

Consequently, said means to switch on a switchable oil pump are configured to operate when the third time interval ranges between 20 and 40 [s].

An advantage of these embodiments is that the values of the temperature parameter threshold, the first time interval, the reset time interval threshold and the third time interval can be easily proved by means of an experimental campaign.

Another embodiment of the disclosure provides an internal combustion engine comprising a turbocharger, wherein a turbocharger temperature is controlled by a method according to any of the previous embodiments.

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 embedded in 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.

BRIEF DESCRIPTION OF TIlE DRAWINGS

The various embodiments will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows an automotive system.

Figure 2 is a section of an internal combustion engine belonging to the automotive system of figure 1.

Figure 3 is a simplified scheme of a turbocharger.

Figure 4 is a flowchart of the method according to an embodiment of the present invention.

Figure 5 is a graph showing the above method, according to another embodiment of the present invention.

B

Figure 6 is a graph showing the method of Fig. 4, according to a further embodiment of the present invention.

Figure 7 is a graph showing the method of Fig. 4, according to a still further embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

Some embodiments may include an automotive system 100, 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 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 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 dud 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 fixed geometry turbine 250 including a waste gate 290. In other embodiments, the turbocharger 230 may be a variable geometry turbine (VGT) with a VGT actuator arranged to move the vanes to alter the flow of the exhaust gases through the turbine.

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 NOx traps, hydrocarbon adsorbers, selective catalytic reduction (SCR) systems. 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 andlor devices associated with the ICE 110 and equipped with a data carrier 40. 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, pressure, 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 waste gate 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 unit (CPU) in communication with a memory system 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.

The program stored in the memory system is transmitted from outside via a cable or in a wireless fashion. Outside the automotive system 100 it is normally visible as a computer program product, which is also called computer readable medium or machine readable medium in the art, and which should be understood to be a computer program code residing on a carrier, said carrier being transitory or non-transitory in nature with the consequence that the computer program product can be regarded to be transitory or non-transitory in nature.

An example of a transitory computer program product is a signal, e.g. an electromagnetic signal such as an optical signal, which is a transitory carrier for the computer program code. Carrying such computer program code can be achieved by modulating the signal by a conventional modulated technique such as QPSK for digital data, such that binary data representing said computer program code is impressed on the transitory electromagnetic signal. Such signals are e.g. made use of when transmitting computer program code in a wireless fashion via a WiFi connection to a laptop.

In case of a non-transitory computer program product the computer program code is embodied in a tangible storage medium. The storage medium is then the non-transitory carrier mentioned above, such that the computer program code is permanently or non-permanently stored in a retrievable way in or on this storage medium. The storage medium can be of conventional type known in computer technology such as a flash memory, an Asic, a CD or the like.

Instead of an ECU 450 the automotive system 100 may have a different type of processor to provide the electronic logic, e.g. an embedded controller, an onboard computer, or any processing module that might be deployed in the vehicle.

Figure 3 is a Simplified scheme of a turbocharger 230 of an internal combustion engine. In the Figure, the turbine 250, the compressor 240 and the turbocharger shaft 245 are shown.

As said, the critical temperature for the oil coking is the turbocharger temperature AT localized in the shaft bearings. To avoid oil coking this temperature must be kept under control and has to be lower than a turbocharger temperature threshold AT thr, which can be fixed at about 250°C. This temperature is almost determined by the heat exchange between exhaust gas and oil.

Since the turbocharger temperature is not easy to be measured, a model to estimate a temperature parameter DT, which can be considered in a direct proportion with the oil temperature increase across the turbine due to the exhaust gas action, has been defined.

In fact the energy balance between exhaust gas and oil in the turbocharger is: DT = Mg x Cpg x (Tgin-Tgout)/(Mo x Cpo) where: DI = temperature parameter, corresponding to the oil temperature increase across the turbine Mg = exhaust gas mass flow Mo = oil mass flow Cpg = exhaust gas specific heat Gpo = oil specific heat Tgin= exhaust gas inlet temperature Tgout= exhaust gas outlet temperature In other words, since the oil mass flow Mo is in direct proportion with the engine speed RPM, the above equation can be written: DT MgxTg/RPM where: Tg = Tgin -Igout = exhaust gas temperature drop (across the turbne) The turbocharger temperature AT along the shaft bearings can be expressed by the following equation: AT=Mg*Tg/Mo Therefore, the temperature parameter Di is proportional to the turbocharger temperature AT in the turbocharger shaft axis bearings.

The temperature parameter Di has been validated by means of a correlation with turbocharger temperature AT, which has been measured on turbocharger bearings. This means that, if the temperature parameter is above a certain threshold DT thr, the turbocharger temperature AT (i.e. the bearing temperature) is above the threshold AT thr, for example, 250°C. Appropriate measurements indicate that the temperature parameter Di is related to the real increase in oil temperature on the bearings: the turbocharger temperature AT is higher than the threshold of 250°C if the temperature parameter Di ranges between 16 and 18.

With reference to Fig. 4, which shows a flowchart according to an embodiment of the present invention, having defined the above model and temperature parameter DI, the method calculates S410 said temperature parameter DT of the turbocharger, which is correlated to the temperature AT of the turbocharger and is a function of an exhaust gas mass flow Mg, an exhaust gas temperature drop Tg across the turbine and an engine speed RPM. Then, a time t is determined S430 during which said temperature parameter DI is larger than S420 a temperature parameter thr!shold DT thr. Finally, as soon as the time t is larger than S440 a first time interval Ta, the engine will be de-rated S450 in order to lower the temperature of the turbocharger below a turbocharger temperature threshold.

In fact, the temperature parameter DT is strictly related with performance, and therefore, in order to have lower DI, it is necessary to lower performances: indeed, DT depends on the temperature drop of exhaust gases in the turbocharger and from the exhaust gases mass flow, that are directly related to the engine performances.

With such temperature control, it would be possible to avoid, during the vehicle driving, that the turbocharger temperature lays too long over the limit and that, when the engine is switched off and the oil does not circulate anymore (reducing its capacity to exchange heat), the risk to overcome the turbo temperature threshold of about 250°C and to have oil coking. By using this method, any water cooling circuit can be avoided.

Benchmarking investigation is a strong confirmation of the validity of the method: almost all engines with a temperature parameter DT above 18 (high risk of oil coking) are adopting turbocharger water cooling. For this reason, a reasonable value for the temperature parameter threshold is confirmed to be in the range 16-18 (kg/s °CIrpmj preferably about 16.

Also as an example, a possible range of the first time interval Ta for the engine de-rating to be activated can be fixed between 1600 and 2000s, preferably 1 BOOs, that is to say half a hour.

Fig. 5 illustrates an alternative embodiment of the present invention. In the graph the temperature parameter DI is plotted along the time. The functioning mode shows that the DT value is over the temperature parameter threshold OT thr. After a second time interval Tb, the engine de-rating can be anticipated by a warning message. The warning message, therefore, can be sent if the time is smaller than the first time interval Ta and is larger than the second time interval Tb. The driver will be notified by the warning message and will be prepared to a future engine de-rating or he will decide to go slower, to avoid the forced limitation.

In Fig. 5 is also shown a possible strategy of engine de-rating. Of course, the engine should loss power until the temperature parameter will reach the threshold value, 16 as in the plot.

In order to minimize the discomfort, the de-rating can be performed stepwise, N times, where N is a natural number, each of the steps being proportional to: 1/Nx(DT-DTthr) In this way, the de-rating can be smoothed as desired.

Figure 6 is another plot showing still another embodiment of the invention. As in Fig. 4, In the temperature parameter DT is plotted along the time. In the graph is shown that the temperature parameter for a first portion Tal of the first time interval is over the threshold (always 16, also in this example); then the temperature parameter DT goes down under the threshold value for a reset time interval Tr; finally the temperature parameter once more overcomes the limit for a second portion Ta2 of the first time interval Ta. In this case the first time interval Ta will be exactly the sum: Ta=Tal+Ta2 if the reset time interval Tr is lower than a reset time intervai threshold Ir thr.

An appropriate range of the reset time interval threshold can be between 200 and 400 s.

In case the reset time interval will be higher than the relative threshold Tr thr, the time t will be restarted. In other words, the time interval, for the engine de-rating to be activated, will be restarted only if the reset time interval, during which the turbocharger temperature is under control, is sufficiently long.

In case the internal combustion engine also comprises a switchable oil pump 500 (see Fig. 2) another embodiment of the present invention can be defined. In Figure 7, again a plot of the temperature parameter DT versus the time, is shown the following case: at first the engine is on and the temperature parameter DT is over the limit. Suddenly, the engine is switched off, before the engine de-rating strategy has occurred (for example, the time interval Ta has not overcome its threshold). This means that the risk of oil coking still exists.

Therefore, in case the switchable oil pump is adopted, in addition to above mentioned strategy, when the driver shut off the engine and the temperature parameter OT is above the temperature parameter threshold UT thr, the oil pump can still work. So acting, the oil is flowing across the turbocharger for a third time interval Tc (which can be fixed, for example, at 30 s or anyway in a range between 20 and 40s), further reducing the risk of coking, as turbocharger bearings are cooled by the oil.

Summarizing the present method has a strong impact in controlling the turbocharger temperature. The proposed strategy is easy to be implemented, takes into account physical parameters which can be easily available, reduces the risks of oil coking and finally does not require anymore the water cooling circuit dedicated to the turbocharger.

This is a strong advantage in terms of costs, layout and weight.

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

data carrier automotive system 110 internal combustion engine engine block cylinder cylinder head camshaft 140 piston crankshaft combustion chamber cam phaser fuel injector 165 fuel injection system fuel rail fuel pump fuel source intake manifold 205 air intake duct 210 intake port 215 valves 220 port 225 exhaust manifold 230 turbocharger 240 compressor 245 turbocharger shaft 250 turbine 260 intercooler 270 exhaust system 275 exhaust pipe 280 aftertreatment devices 290 waste gate valve 295 waste gate actuator or electric pressure valve or boost pressure control valve 300 exhaust gas recirculation system 310 EGR cooler 320 EGR valve 330 throttle body 340 mass airflow, pressure, temperature and humidity sensor 350 manifold pressure and temperature sensor 360 combustion pressure sensor 380 coolant temperature and level sensors 385 lubricating oil temperature and level sensor 390 metal temperature sensor 400 fuel rail digital pressure sensor 410 cam position sensor 420 crank position sensor 430 exhaust pressure and temperature sensors 440 EGR temperature sensor 445 accelerator position sensor 446 accelerator pedal 450 ECU 500 switchable oil pump S410 step S420 step S430 step S440 step S450 step Tg exhaust gas temperature drop (across the turbine) Mg exhaust gas mass flow Mo oil mass flow DI temperature parameter DI thr temperature parameter threshold RPM engine speed AT turbocharger temperature Al thr turbocharger temperature threshold t time Ta first time interval Tb second time interval Tal first portion of the first time interval Ta2 second portion of the first time interval Tr reset time interval Tr thr reset time threshold third time interval Cpg exhaust gas specific heat Cpa oil specific heat Tgin exhaust gas inlet temperature Tgout exhaust gas outlet temperature

Claims

CLAIMS1. Method of controlling a temperature (AT) of a turbocharger (230) for an internal combustion engine (110), wherein the method comprises the following steps: a) calculating a temperature parameter (DT) of the turbocharger, which is correlated to the temperature (AT) of the turbocharger and which is a function of an exhaust gas mass flow (Mg), an exhaust gas temperature drop (Tg) across a turbine (250) and an engine speed (RPM), b) determining a time (t) during which said temperature parameter (DI) is larger than a temperature parameter threshold (DT thr), d) de-rating the internal combustion engine if said time (t) is larger than a first time interval (Ta), in order to lower the temperature (AT) of the turbocharger below a turbocharger temperature threshold (AT thr).
2. Method according to claim 1, wherein the method further comprises the following step: c) sending a warning message if the time (t) is smaller than the first time interval (Ta) and is larger than a second time interval (Tb).
3. Method according to claim I or 2, wherein the engine de-rating is performed stepwise, N times, N being a natural number, each of the steps being proportional to: 1/Nx(DT-DTthr)
4. Method according any of the preceding claims, wherein a first portion (Tal) and a second portion (Ta2) of the first time interval (Ta), during which the temperature parameter (DI) is larger than the temperature parameter threshold (DT thr), are separated by a reset time interval (Tr), during which the temperature parameter (DT) is smaller than the temperature parameter threshold (DT thr) and the first time interval (Ta) is the sum of the first portion (Tal) and the second portion (Ta2) if said reset time interval is smaller than a reset time interval threshold (Tr thr).
5. Method according to any of the preceding claims, wherein the internal combustion engine (110) also comprises a switchable oil pump (500) and wherein, when the engine is switched off, the switchable oil pump is switched on during a third time interval (Ic), if the temperature parameter (DT) is larger than the temperature parameter threshold (UT thr).
6. Method according to any of the preceding claims, wherein the temperature parameter threshold (UT thr) ranges between 16 and 18 f kg/s °C/rpmj.
7. Method according to any of the preceding claims, wherein the first time interval (Ta) ranges between 1600 and 2000 [sI.
8. Method according to claim 4, wherein the reset time interval threshold (Ir thr) ranges between 200 and 400 [s].
9. Method according to claim 5, wherein the third time interval (Tc) ranges between 20 and4o[sI.
10. Internal combustion engine (110) comprising a turbocharger (230), wherein a turbocharger temperature (AT) is controlled by a method according to any of the preceding claims.
11. A non-transitory computer program comprising a computer-code suitable for performing the method according to any of the claims 1-9.
12. Computer program product on which the non-transitory computer program according to claim 11 is stored.
13. Control apparatus for an internal combustion engine, comprising an Electronic Control Unit (450), a data carrier (40) associated to the Electronic Control Unit (450) and a non-transitory computer program according to claim 11 stored in a memory system (460).