Method for supercharging pressure regulation of an internal combustion engine

Abstract

A method for boost pressure regulation of an internal combustion engine (1), which is part of a drive train (2), wherein the drive train (2) has at least an internal combustion engine (1), an intake duct (3), an exhaust duct (4) and an exhaust turbocharger (5); wherein the internal combustion engine (1) has at least one intake valve (7) which fluidically connects the intake duct (3) with a combustion chamber (6) of the internal combustion engine (1) and at least one exhaust valve (9) which fluidically connects the combustion chamber (6) with a first section (8) of the exhaust duct (4); wherein the exhaust duct (4) has a first section (8) between the combustion chamber (6) and the exhaust turbocharger (5) and a second section (10) downstream of the exhaust turbocharger (5); wherein the exhaust turbocharger (5) and / or a bypass (33) around the exhaust turbocharger is adjustable; wherein the opening time (17) of the at least one intake valve (7) and the closing time (18) of the at least one exhaust valve (9) are taken into account in the method.

Description

TECHNICAL FIELD

[0001] The invention relates to a method for boost pressure regulation of an internal combustion engine. The internal combustion engine is in particular a component of a drive train, wherein the drive train has at least the internal combustion engine, an intake tract, an exhaust tract and an exhaust turbocharger. The exhaust turbocharger is in particular a VTG exhaust turbocharger (VTG: "Variable Turbine Geometry") with variable set turbine geometry. BACKGROUND

[0002] From the documents DE 10 2008 063 935 A1, DE 10 2013 223 900 A1 and DE 10 2015 216 261 A1, respectively, a method for controlling a VTG exhaust turbocharger is known by which the optimum position of the exhaust turbocharger should be determined depending on the operating point of the internal combustion engine. The optimum position of the exhaust turbocharger should allow the provision of the maximum possible turbine power of the exhaust turbocharger.

[0003] It has turned out that in modern internal combustion engines only a slow and / or disharmonically build-up of boost pressure or torque can be achieved at defined operating points. In addition, the internal combustion engine can also "stop" itself due to an excessively high set exhaust back pressure (when the exhaust turbocharger has only a small through-flow cross section) so that the required torque cannot be achieved.

[0004] For this reason, the maximum duty cycle of the exhaust turbocharger is limited (that is to say the through-flow cross section is not reduced to a minimum) so that at least an excessively high exhaust back pressure (in the exhaust tract section between the internal combustion engine and the exhaust turbocharger) is prevented.

[0005] However, the limitation of the duty cycle results in that the build-up of boost pressure and torque only takes place slowly or not optimally quickly. SUMMARY

[0006] The technical problem addressed by the invention is to at least partially solve the problems arising in the prior art. In particular, a method for boost pressure regulation of an internal combustion engine is proposed by which the boost pressure and / or the torque can be built up as quickly as possible.

[0007] The technical problem is solved according to the invention by a method for boost pressure regulation of an internal combustion engine and a motor vehicle.

[0008] A method for adjusting the boost pressure of an internal combustion engine is proposed, wherein the internal combustion engine is part of a drive train. The drive train has at least the internal combustion engine, an intake duct, an exhaust duct and a turbocharger. The internal combustion engine has at least one intake valve which fluidically connects the intake duct to at least one combustion chamber of the internal combustion engine and at least one exhaust valve which fluidically connects the combustion chamber to a first section of the exhaust duct. The exhaust duct has a first section between the combustion chamber and the turbocharger and a second section downstream of the turbocharger. The total cross-sectional area through which exhaust gas can flow between the first section and the second section can be adjusted. This adjustment can be achieved on the one hand by a bypass (wastegate) which connects the first section to the second section and which bypasses the turbocharger, the flow-through of which can be adjusted, and / or this adjustment can be achieved by an adjustable turbocharger which, like the bypass, is adjustable between a first position with a minimum flow-through cross-section for exhaust gas and a second position with a maximum flow-through cross-section for exhaust gas, for example steplessly or in specific steps. In combination with the bypass, in particular an inadjustable turbocharger can be used, so that the total flow-through cross-sectional area is then adjusted by the bypass. The method comprises at least the following steps:

[0009] a) detecting a load requirement for the drive train;

[0010] b) determining a position of the turbocharger and / or a position of a bypass for providing turbocharger power.

[0011] In step b) the opening time of the at least one intake valve and the closing time of the at least one exhaust valve are taken into account.

[0012] Modern internal combustion engines are loaded more and more while at the same time being reduced in size (so-called "downsizing"). The build-up of torque during dynamic changes in the operating point of the internal combustion engine is in particular related to the interaction adjustment of throttle valve, camshaft and boost pressure. More and more of the current gasoline engine manufacturers are developing internal combustion engines with VTG turbochargers, which are operated with the so-called Miller combustion method mainly for the reduction of harmful substances, such as nitrogen oxides. In this combustion method, the intake valve of the combustion chamber is closed, for example, during the intake stroke, so that the charge of the cylinder is reduced. The temperature and pressure at the end of the compression stroke are thereby reduced. By means of the turbocharger, the mixture can also be introduced into the combustion chamber, so that the losses can be compensated and the power can be smaller compared to conventional internal combustion engines. Furthermore, an overlap occurs in the valve control, i.e. the intake valve and the exhaust valve of the combustion chamber are at least temporarily open at the same time at least partially, so that the intake duct is fluidically connected to the exhaust duct via the combustion chamber.

[0013] In the combustion method with such or other operations by means of the intake valve or the exhaust valve, the fresh air charge present in the cylinder fills both the third pressure in the intake tract and the first pressure in the first section of the exhaust tract due to a large valve overlap, that is to say a time overlap of the opening time of the intake valve and the closing time of the exhaust valve of the combustion chamber; that is to say, the intake tract is in overlap with the exhaust tract via the combustion chamber - first section - in fluid communication. By using a VTG exhaust turbocharger, further possible variations of the pressure are increased. In particular, the exhaust turbocharger influences both the third pressure in the intake tract and the first pressure in the first section.

[0014] Furthermore, in modern internal combustion engines, camshaft adjusters are expediently used for reducing fuel consumption and for adjusting the fresh air charge of the combustion chamber. Here, the sensitivity of the cylinder charge, that is to say the charge of the combustion chamber, is influenced by the third pressure in the intake tract and the first pressure in the first section of the exhaust tract due to different camshaft positions (and associated changes in the operation of the intake valve and the exhaust valve).

[0015] It has now been determined that the current boost pressure regulation function cannot take into account or cannot take into account sufficiently the different sensitivities of the cylinder charge, so that only a still slow and / or disharmonic build-up of the boost pressure and the torque can be achieved. In particular, the camshaft position, that is to say the opening time of the intake valve and the closing time of the exhaust valve (and the resulting time overlap, in which both valves are arranged in the open position and the intake tract is in fluid communication with the first section of the exhaust tract via the combustion chamber), is not taken into account.

[0016] It is now proposed in particular that the camshaft position or the position of at least one intake valve and at least one exhaust valve of the (common) combustion chamber is taken into account in the method for regulating the boost pressure.

[0017] The internal combustion engine is in particular a gasoline engine, alternatively a diesel engine. At least fresh air can be fed to the combustion chamber by means of the intake tract. The intake tract can be in fluid communication with the combustion chamber or disconnected therefrom by means of at least one intake valve. The exhaust tract can be in fluid communication with the combustion chamber or disconnected therefrom by means of at least one exhaust valve.

[0018] The exhaust turbocharger is in particular adjustable between a first position and a second position, for example steplessly or in specific steps, via a plurality of (intermediate) positions, the first position having a minimum flow cross section for the exhaust gas, the second position having a maximum flow cross section for the exhaust gas. In the first position, a higher pressure ratio between the first pressure (upstream of the exhaust turbocharger in the exhaust tract) and the second pressure (downstream of the exhaust turbocharger in the exhaust tract) can be achieved, in the second position, only a smaller pressure ratio can be achieved accordingly.

[0019] Alternatively, the exhaust-gas turbocharger is designed to be non-adjustable. In this embodiment, an adjustable bypass is provided, through which exhaust gas can be conducted from the first section to the second section, bypassing the exhaust-gas turbocharger. The turbine power of the exhaust-gas turbocharger can be adjusted by varying the cross-sectional area of the flowable bypass. The bypass, like the adjustable exhaust-gas turbocharger, is adjustable, in particular between a first position having a minimum flow cross section for exhaust gas and a second position having a maximum flow cross section for exhaust gas, by way of a plurality of (intermediate) positions, for example steplessly or in specific steps. In the first position, a pressure ratio between a first pressure (upstream of the exhaust-gas turbocharger in the exhaust tract) and a second pressure (downstream of the exhaust-gas turbocharger in the exhaust tract) can be achieved, in the second position a correspondingly only smaller pressure ratio can be achieved.

[0020] According to a further design, a bypass is provided and the exhaust-gas turbocharger is adjustable in the manner described.

[0021] In each of the embodiments described, the total flowable cross section (of the bypass and / or of the exhaust-gas turbocharger) is adjusted.

[0022] In particular, a time overlap of the opening times and the closing times occurs when the internal combustion engine is running, so that at least temporarily the first section is in fluid communication with the intake tract via the combustion chamber.

[0023] The time overlap can in particular also be described by an angular range between the positions of the crankshaft or of at least one camshaft, in which the intake valves and the exhaust valves are operated.

[0024] The cylinder charge, that is to say the cylinder air mass, can be determined more precisely, taking into account the operation of the intake valves and the exhaust valves.

[0025] The air mass flow or the exhaust gas mass flow can thus be determined, in particular by the rotational speed of the internal combustion engine.

[0026] The turbine power of the exhaust-gas turbocharger is in particular proportional to the product of the exhaust gas mass flow and the pressure ratio (that is to say the ratio of the first pressure and the second pressure) over the exhaust-gas turbocharger.

[0027] In particular in step a), it is detected whether a load requirement on the drive train is present or planned. This can be determined, for example, by means of at least one sensor measurement or by means of a calculation model. The load requirement (change) can cause the triggering of step b) of the method.

[0028] In step b) at least one of the following parameters is also taken into account, preferably at least two or even all: cylinder air mass, rotational speed of the internal combustion engine, air mass flow (in the intake tract), exhaust gas mass flow (in the exhaust tract), first pressure in the first section of the exhaust tract, second pressure in the second section of the exhaust tract, third pressure in the intake tract, temperature of the exhaust gas.

[0029] The position of the exhaust-gas turbocharger determined in step b) is determined repeatedly, in particular.

[0030] In the course of repeatedly implementing the method, a change curve of the turbine power is determined, preferably, on the basis of the first pressure in the first section.

[0031] The determined first pressure at which the turbine power is greatest is determined repeatedly, in particular, on the basis of the change curve.

[0032] The change curve is obtained repeatedly, in particular, starting from a first position (minimum throughflow cross section, that is to say the greatest producible pressure difference between the first pressure and the second pressure) and stepwise towards a second position.

[0033] The step variable in the repeated implementation is preferably selected on the basis of the available computing power of the control unit.

[0034] The step variable is preferably changed during the repeated implementation of the method. The step variable is in particular greater when the available computing power of the control unit is smaller and vice versa when the available computing power of the control unit is greater.

[0035] For example, starting from the first pressure determined in the course of the repeated implementation at which the turbine power is greatest, the position of the exhaust-gas turbocharger or the adjustment of the total cross section area through which the exhaust-gas turbocharger can be passed and the bypass can then be determined, wherein the previously determined maximum turbine power can be achieved on the basis of the parameters present at the time.

[0036] Further repetitions are not carried out, in particular, on the basis of the repeatedly determined values of the first pressure in order to determine the position of the exhaust-gas turbocharger or the adjustment of the total cross section area through which the exhaust-gas turbocharger can be passed and the bypass, wherein the previously determined maximum turbine power can be achieved on the basis of the parameters present at the time.

[0037] The method is carried out, in particular, only when there is a load step. The method is carried out, in particular, only when the load step is positive, that is to say when the requested torque is higher than the current torque.

[0038] Only a part of the method is preferably recalculated, for which part the parameters considered change.

[0039] In particular, in the method (only or at least) two different cases are considered. The cases can be determined, for example, by predicting the cases or by repeatedly obtaining a curve of the turbine power as a function of the first pressure in the first section of the exhaust duct.

[0040] In a first case, the turbine power continuously increases from the second position and towards the first position (of the exhaust turbocharger or the bypass), so that the position of the exhaust turbocharger or the bypass can be shifted into the first position.

[0041] In a second case, there is (only) one maximum of the turbine power as a function of the first pressure. Here, the maximum of the turbine power is determined (repeatedly, for example, starting from the first position), so that the first pressure present at the maximum can be used to determine the position to be adjusted of the adjustable exhaust turbocharger.

[0042] The method, in particular the (repeated) determination of the value of the first pressure at which the maximum of the turbine power is present, is implemented in particular only computationally in the control unit. In particular, no parameters are applied to the drive train. In particular, the resulting position of the exhaust turbocharger is adjusted as quickly as possible only after the calculation is completed, so that the boost pressure and / or the torque can be built up as quickly as possible with this achievable maximum turbine power.

[0043] Furthermore, a motor vehicle is proposed, which has a drive train and an internal combustion engine, wherein the internal combustion engine is a component of the drive train. The drive train has at least the internal combustion engine, an intake duct, an exhaust duct and an exhaust turbocharger. The internal combustion engine has at least one intake valve which fluidically connects the intake duct to at least one combustion chamber of the internal combustion engine and at least one exhaust valve which fluidically connects the combustion chamber to a first section of the exhaust duct. The exhaust duct has a first section between the combustion chamber and the exhaust turbocharger and has a second section downstream of the exhaust turbocharger. The total cross-sectional area through which exhaust gases can flow between the first section and the second section is adjustable. This can be achieved, on the one hand, by a bypass (wastegate) which connects the first section to the second section and bypasses the exhaust turbocharger, the flow through said bypass being adjustable and / or by an adjustable exhaust turbocharger which, like the bypass, is adjustable (for example steplessly or in specific steps) between a first position having a minimum flow cross-section for the exhaust gases and a second position having a maximum flow cross-section for the exhaust gases. A control unit is also provided, which is designed or set up for implementing the method described and / or which can carry out the method.

[0044] The control unit makes use of at least one model stored in the control unit, in particular. The at least one model is, for example, a first model by means of which the cylinder charge can be determined as a function of the parameters, a second model by means of which the exhaust gas mass flow can be determined as a function of the parameters, and / or a third model by means of which the turbine power of the exhaust gas turbocharger can be determined as a function of the parameters.

[0045] The control unit makes use of two of the models mentioned, in particular, wherein one model is designed for adjusting the internal combustion engine (for example for adjusting the intake valves, the exhaust valves, the ignition point, the formation of the mixture) and the other model is designed for adjusting the exhaust gas turbocharger (for example for changing the turbine geometry or the bypass, that is to say for adjusting the position).

[0046] The method can also be executed further by a computer or by a processor of the control unit.

[0047] A system for data processing is therefore also proposed, which comprises a processor which is adapted / configured to execute a part of the steps of the method or of the proposed method.

[0048] A computer-readable storage medium can be provided, which comprises instructions which, when executed by a computer / processor, cause it to execute at least a part of the steps of the method or of the proposed method.

[0049] Embodiments of the method can be transferred to motor vehicles, systems, storage media or computer-implemented methods, and vice versa, in particular.

[0050] For the avoidance of doubt, it should be noted that the ordinal numbers used here ("first", "second",...) are used primarily (only) to distinguish between a plurality of objects, variables or processes of the same kind, that is to say in particular do not necessarily specify a relationship and an order of these objects, variables or processes. If a relationship and / or an order is necessary, this is expressly stated here or is apparent to the person skilled in the art when studying the specific described design. BRIEF DESCRIPTION OF DRAWINGS

[0051] The application and the technical background are explained further below on the basis of the drawings. It should be noted that the application should not be restricted to the embodiments listed. In particular, parts of the facts stated in the description of the drawings can be extracted and combined with other components and recognitions from the present description. In particular, it should be noted that the drawings and in particular the size proportions shown are merely schematic. In the drawings:

[0052] Figure 1 A motor vehicle 2 is shown having a drive train 1 ;

[0053] Figure 2 A first flow chart is shown;

[0054] Figure 3 A first curve diagram is shown;

[0055] Figure 4 A second flow chart with a second curve diagram is shown;

[0056] Figure 5 A further motor vehicle with a drive train is shown. DETAILED DESCRIPTION

[0057] Figure 1 A motor vehicle 32 with a drive train 2 is shown. The drive train 2 has an internal combustion engine 1, an intake duct 3, an exhaust duct 4 and a waste gas turbocharger 5. The internal combustion engine 1 has an intake valve 7 which fluidically connects the intake duct 3 with a combustion chamber 6 of the internal combustion engine 1 and an exhaust valve 9 which fluidically connects the combustion chamber 6 with a first section 8 of the exhaust duct 4. The exhaust duct 4 has the first section 8 between the combustion chamber 6 and the waste gas turbocharger 5 and has a second section 10 downstream of the waste gas turbocharger 5. The waste gas turbocharger 5 is adjustable between a first position 1 1 with a minimum throughflow cross section for the waste gas 12 and a second position 13 with a maximum throughflow cross section for the waste gas 12, for example steplessly or in specific steps. A control unit 28 is additionally provided which is suitably designed for carrying out the method or can carry out the method.

[0058] The control unit 28 utilizes models 29, 30, 31 stored in the control unit 28. The models 29, 30, 31 comprise a first model 29 by means of which the cylinder charge (that is to say the cylinder air mass 19) can be determined as a function of parameters, a second model 30 by means of which the waste gas mass flow 22 can be determined as a function of parameters and a third model 31 by means of which the turbine power 16 of the waste gas turbocharger 5 can be determined as a function of parameters.

[0059] The first model 29 is designed for adjusting the internal combustion engine 1 (for example for adjusting the intake valve 7, the exhaust valve 9, the ignition point, the mixture composition). The third model 31 is designed for adjusting the waste gas turbocharger 5 (for example for changing the turbine geometry, that is to say for adjusting the position 15).

[0060] Within the scope of step a) the presence of a load requirement 14 for the drive train 2 is identified or the load requirement 14 is present in step a) is implemented by the control unit. In step b) the position 15 of the waste gas turbocharger 5 for providing as high a turbine power as possible, that is to say the maximum turbine power 16, of the waste gas turbocharger 5 is determined. Here the opening time 17 of the intake valve 7 and the closing time 18 of the exhaust valve 9 are taken into account in step b).

[0061] In the method, the following parameters are also taken into account: the cylinder air mass 19, the rotational speed 20 of the internal combustion engine 1, the air mass flow 21 (in the intake tract 3), the exhaust gas mass flow 22 (in the exhaust tract 4), the first pressure 23 in the first section 8 of the exhaust tract 4, the second pressure 24 in the second section 10 of the exhaust tract 4, the third pressure 25 in the intake tract 3, the temperature 26 of the exhaust gas 12.

[0062] Figure 2 A first flow chart is shown. In it, the relationships of the individual parameters utilized by the application are shown. As input variables, the first pressure 23 (exhaust gas back pressure in the first section 8), the third pressure 25 in the intake tract 3, the opening time 17 of the intake valve 7, the closing time 18 of the exhaust valve 9, the rotational speed 20 of the internal combustion engine 1, the second pressure 24 in the second section 10 and the temperature 26 of the exhaust gas 12 are used.

[0063] In the course of the repeated implementation, different values of the first pressure 23 are used as input variables.

[0064] The parameters, i.e. the first pressure 23, the third pressure 25, the opening time 17 of the intake valve 7, the closing time 18 of the exhaust valve 9, the rotational speed 20 of the internal combustion engine 1, are used as input variables for a first model 29 to determine the cylinder air mass 19 resulting therefrom.

[0065] The cylinder air mass 19 determined in the respective repeated implementation and the rotational speed 20 are jointly used as input variables for a second model 30 to determine the exhaust gas mass flow 22 (or the air mass flow 21 corresponding thereto) resulting therefrom.

[0066] The exhaust gas mass flow 22 determined in the respective repeated implementation and the respective value of the first pressure 23 used for the repetition, the second pressure 24 and the temperature 26 of the exhaust gas 12 are jointly used as input variables for a third model 31 to determine the turbine power 16 resulting therefrom.

[0067] On the basis of the repeated implementation, a curve 27 of the turbine power 16 (see Fig. 2) can be determined (computationally) with respect to different values of the first pressure 23. Figure 3 ).

[0068] The repeated implementation is carried out, in particular, only computationally, i.e. the parameters used in the course of the repeated implementation are not actually set in the drive train 2.

[0069] Figure 3 A first graph is shown, in which the first pressure 23 is plotted on the horizontal axis and the turbine power on the vertical axis. Figure 3A curve 27 of the turbine power 16 is shown, which is determined in the course of the method or the repeated implementation, with respect to different values of the first pressure 23. There is a maximum in the curve 27 here, so that the second case mentioned is clearly present.

[0070] For the case Figure 2 The described repeatedly starting from the first position 11 of the exhaust-gas turbocharger 5, i.e. the minimum throughflow cross section, i.e. the maximum pressure difference that can be produced between the first pressure 23 and the second pressure 24, and repeatedly extending stepwise towards the second position 12.

[0071] Figure 4 A second flow diagram is shown with a second graph. For the second flow diagram, the value of the first pressure 23 is used as an input variable for which the maximum turbine power 16 is determined by means of a first model 29 according to Figure 1 There is a maximum turbine power 16 for the first flow diagram according to

[0072] The first pressure 23, i.e. the exhaust-gas back pressure in the first section 8, for which the maximum turbine power 16 is determined in the present operating point, the third pressure 25 in the intake tract 3, the opening time 17 of the intake valve 7, the closing time 18 of the exhaust valve 9, the rotational speed 20 of the internal combustion engine 1 and the second pressure 24 in the second section 10 are thus used as input variables for a first model 29 in order to determine the cylinder air mass 19 resulting therefrom.

[0073] The parameters, i.e. the first pressure 23, the third pressure 25, the opening time 17 of the intake valve 7, the closing time 18 of the exhaust valve 9, the rotational speed 20 of the internal combustion engine 1, for which the maximum turbine power 16 is determined in the present operating point, are used as input variables for a first model 29 in order to determine the cylinder air mass 19 resulting therefrom.

[0074] The cylinder air mass 19 thus determined is used jointly with the rotational speed 20 as an input variable for a second model 30 in order to determine the exhaust-gas mass flow 22 resulting therefrom (or the air mass flow 21 corresponding thereto).

[0075] The exhaust-gas mass flow 22 thus determined is used jointly with the value of the first pressure 23 and the second pressure 24, which are utilized here, as an input variable for a third model 31 in order to determine the position 15 of the exhaust-gas turbocharger 5 required for producing the maximum turbine power 16.

[0076] Figure 5 A motor vehicle 2 with a drive train 1 is shown. Reference is made to Figure 1In an embodiment, the drive train 2 has a bypass 33 which bypasses the exhaust gas turbocharger 5 and which adjustably connects the first section 8 with the second section 10. The bypass 33 (or the flow-through cross section of the bypass 33 and / or the total cross-sectional area of the bypass 33 and the exhaust gas turbocharger 5) is adjustable between a first position 11 having a minimum flow-through cross section for the exhaust gas 12 and a second position 13 having a maximum flow-through cross section for the exhaust gas 12 (e.g. steplessly or in specific steps).

[0077] List of reference signs

[0078] 1 internal combustion engine

[0079] 2 drive train

[0080] 3 intake duct

[0081] 4 exhaust duct

[0082] 5 exhaust gas turbocharger

[0083] 6 combustion chamber

[0084] 7 intake valve

[0085] 8 first section

[0086] 9 exhaust valve

[0087] 10 second section

[0088] 11 first position

[0089] 12 exhaust gas

[0090] 13 second position

[0091] 14 load request

[0092] 15 position

[0093] 16 turbine power

[0094] 17 opening time

[0095] 18 closing time

[0096] 19 cylinder air mass

[0097] 20 rotational speed

[0098] 21 air mass flow

[0099] 22 exhaust gas mass flow

[0100] 23 first pressure (exhaust gas back pressure)

[0101] 24 second pressure (downstream turbine)

[0102] 25 third pressure

[0103] 26 temperature

[0104] 27 change profile

[0105] 28 control unit

[0106] 29 first model (cylinder charge)

[0107] 30 second model (exhaust gas mass flow)

[0108] 31 third model (turbine power)

[0109] 32 motor vehicle

[0110] 33 bypass

Claims

1. A method for boost pressure regulation of an internal combustion engine (1) which is a component of a drive train (2), wherein The drive train (2) has at least an internal combustion engine (1), an intake duct (3), an exhaust duct (4) and a waste-gas turbocharger (5); wherein the internal combustion engine (1) has at least one intake valve (7) which fluidically connects the intake duct (3) to a combustion chamber (6) of the internal combustion engine (1) and at least one exhaust valve (9) which fluidically connects the combustion chamber (6) to a first section (8) of the exhaust duct (4); wherein the exhaust duct (4) has the first section (8) between the combustion chamber (6) and the waste-gas turbocharger (5) and has a second section (10) downstream of the waste-gas turbocharger (5); wherein the total cross-sectional area through which the exhaust gas (12) can flow between the first section (8) and the second section (10) can be adjusted between a first position (11) and a second position (13) by means of an adjustable bypass (33) and / or an adjustable waste-gas turbocharger (5), the first position (11) having a minimum flow-through cross-section for the exhaust gas (12) and the second position (13) having a maximum flow-through cross-section for the exhaust gas (12); wherein the method comprises at least the following steps: a) detecting a load requirement (14) for the drive train (2); b) determining a position (15) of the waste-gas turbocharger (5) and / or of a bypass (33) for providing a turbine power (16) of the waste-gas turbocharger (5); characterized in that, during operation of the internal combustion engine (1), an overlap in time occurs between an opening time (17) of the at least one intake valve (7) and a closing time (18) of the at least one exhaust valve (9) such that the first section (8) is at least temporarily fluidically connected to the intake duct (3) via the combustion chamber (6), for which in step b) the opening time (17) and the closing time (18) and at least one of the following parameters are taken into account: cylinder air mass (19), rotational speed (20) of the internal combustion engine (1), air mass flow (21), exhaust gas mass flow (22), first pressure (23) in the first section (8), second pressure (24) in the second section (10), third pressure (25) in the intake duct (3), temperature (26) of the exhaust gas (12), wherein the position (15) determined in step b) is repeatedly determined, wherein during repeated implementation of the method a profile (27) of the turbine power (16) is determined at least as a function of the first pressure (23) in the first section (8), wherein different values of the first pressure (23) are used as input variables during repeated implementation of the method, wherein starting from the first pressure (23) repeatedly determined during repeated implementation of the method, at which the turbine power (16) is greatest, it is possible to determine an adjustment of the total flow-through cross-sectional area of the bypass (33) and the waste-gas turbocharger (5), wherein the previously determined maximum turbine power (16) can be achieved as a function of the parameters prevailing at the time.

2. The method of claim 1, wherein, The change curve (27) is obtained starting from a first position (11) and repeatedly stepwise towards a second position (13).

3. The method of claim 1, wherein, The step variable in the repeated implementation is selected depending on the available computing power of the control unit (28).

4. The method of claim 3, wherein, The step variable is changed while the method is being implemented.

5. The method of claim 1, wherein, The method is only implemented when there is a load step.

6. Motor vehicle (32) with a drive train (2) having at least one internal combustion engine (1), an intake tract (3), an exhaust tract (4) and a waste-gas turbocharger (5), wherein The internal combustion engine (1) also has at least one intake valve (7) which puts the intake tract (3) into fluid communication with at least one combustion chamber (6) of the internal combustion engine (1) and at least one exhaust valve (9) which puts the combustion chamber (6) into fluid communication with a first section (8) of the exhaust tract (4); and the exhaust tract (4) forms the first section (8) between the combustion chamber (6) and the exhaust turbocharger (5) and forms a second section (10) downstream of the exhaust turbocharger (5); wherein the total cross-sectional area through which exhaust gas (12) can flow between the first section (8) and the second section (10) can be adjusted between a first position (11) and a second position (13) by means of an adjustable bypass (33) and / or an adjustable exhaust turbocharger (5), the first position (11) providing a minimum flow cross section for the exhaust gas (12) and the second position (13) providing a maximum flow cross section for the exhaust gas (12), wherein at least one control unit (28) is also provided, which is set up to implement the method according to one of claims 1 to 5.

Images