Method for operating an internal combustion engine and internal combustion engine

Abstract

Method for operating an internal combustion engine with an internal combustion engine (10) and a fresh gas stream, wherein a compressor (22) is integrated into the fresh gas stream and wherein a trim control (44) is assigned to the compressor (22), by which a marginal section of the inlet cross-section of a compressor impeller (30) of the compressor (22) can be variably covered, wherein the marginal section of the inlet cross-section is in a release position (S T1 ) of the trim knob (44) relatively little and in a cover position (S T2 ) of the trim control (44) is relatively largely covered, characterized in that the trim control (44) is between the release position (S T1 ) and the cover position (S T2 ) is adjusted when the same compressor pressure ratio (π) is used in both operating positions V ) and the same fresh gas mass flow rate (ṁ) and essentially the same compressor efficiency (η) V) is achieved.

Description

[0001] The invention relates to a method for operating an internal combustion engine and to an internal combustion engine suitable for carrying out such a method. The invention also relates to a motor vehicle with such an internal combustion engine.

[0002] In the compressor of an internal combustion engine, the fresh gas supplied to the engine via a fresh gas stream is compressed. The increase in fresh gas pressure depends on the rotational speed of the compressor impeller and the mass flow rate of the fresh gas passing over it. Towards the so-called surge line of the compressor map, the flow towards the leading edges of the impeller blades becomes increasingly pressure-side due to the decreasing flow velocity relative to the circumferential speed; that is, the incidence of the flow increases steadily. Above an operating-point-dependent threshold for the incidence, the so-called surge line, the flow separates at the leading edges, and the flow within the compressor becomes unstable. In the surge line region, a backflow region of low-impulse fluid forms on the inlet-side contour of the compressor housing.This so-called backflow bubble leads to a decrease in compressor efficiency due to swirl and mixing losses. However, in the area of ​​the impeller hub contour, a high-impulse and low-loss core flow also runs through the compressor near the surge line, determining the mass flow rate and pressure build-up.

[0003] A trimmer, such as that known from DE 10 2010 026 176 A1, EP 3 018 355 A1, DE 10 2015 209 704 A1, DE 10 2014 225 716 A1, or WO 2014 / 131 790 A1, serves to shift the surge line of a compressor characteristic curve towards relatively low mass flow rates at high pressure ratios. Simultaneously, a trimmer can increase the compressor efficiency in the surge line region. For this purpose, a trimmer comprises a device by which the inflow cross-section through which the compressor impeller is exposed to the flow can be changed. Through the nozzle effect thus achieved by the trimmer, the gas flow can be more strongly focused on the hub-adjacent inlet cross-section of the compressor impeller with increasing control intervention (reduction of the inflow cross-section).This reduces the amount of gas flowing into the low-impulse, loss-prone area of ​​the backflow bubble, and accelerates and further stabilizes the core flow near the hub. The acceleration of the gas flow near the compressor impeller also shifts the flow direction towards the impeller, which can contribute to further stabilization of the gas flow. This stabilization of the core flow leads to the desired shift of the surge line in the compressor characteristic curve, resulting in lower mass flow rates. If control intervention is not desired (trim controller fully open), the entire cross-section of the fresh gas stream upstream of the compressor impeller is opened as much as possible, so that no additional friction or throttling losses occur in the resulting flow direction towards the impeller.Therefore, the compressor efficiency and the width of the compressor characteristic curve are not negatively affected to a relevant extent by a trimmer in the direction of the choking limit.

[0004] WO 2004 / 022 956 A1 discloses a method for preventing the operation of an internal combustion engine's compressor in the surge line. This method involves monitoring the compressor's behavior with an airflow sensor located in the engine's intake manifold to detect characteristic vibrations of the fresh gas flowing through the intake manifold. If an imminent approach to the surge line is detected, the target boost pressure is reduced. This is achieved by adjusting the flow pattern of a variable turbine geometry (VTG) device on the exhaust gas turbine driving the compressor.

[0005] DE 10 2012 011 423 B3 discloses a compressor device for compressing intake air for an internal combustion engine of a vehicle. The intake air can be supplied to a compressor wheel via an intake duct of the compressor device. Means for changing the cross-sectional area through which the air flows in the intake duct comprise at least one movable element, which has a side facing a central axis of the intake duct. In a first position of the at least one movable element, this side is further away from the central axis (M) than in a second position of the at least one movable element, in which the cross-sectional area through which the air flows in the intake duct is reduced. The invention further relates to a method for compressing intake air for an internal combustion engine of a vehicle.

[0006] The invention was based on the objective of developing a turbocharged internal combustion engine that is characterized by the most optimal possible operating behavior.

[0007] This problem is solved by a method for operating an internal combustion engine according to claim 1. An internal combustion engine suitable for the automated execution of such a method is the subject of claim 6. Advantageous embodiments of the method according to the invention and preferred configurations of the internal combustion engine according to the invention are the subject of further claims and / or will become apparent from the following description of the invention.

[0008] According to the invention, a method for operating an internal combustion engine is provided, wherein the internal combustion engine comprises at least one combustion engine and a fresh gas train, wherein a compressor is integrated into the fresh gas train and wherein a trim control is associated with the compressor, by which a marginal section of the inlet cross-section of a compressor impeller of the compressor can be covered to a variable extent, wherein the marginal section of the inlet cross-section is covered relatively little (compared to a covering position) in a release position of the trim control, preferably as little as possible (i.e., as little as is possible by the design), and in the covering position of the trim control is covered relatively extensively (compared to the release position), preferably as much as possible (i.e.,as far as the design allows (this maximum position being determined to be optimal for the corresponding compressor operation). To achieve the most advantageous switching between these operating positions of the trimmer, it is provided that the trimmer is adjusted between the release position and the cover position, i.e., from the release position to the cover position or vice versa, when the same (within 1% deviation) compressor pressure ratio and the same (within 1% deviation) fresh gas mass flow rate through the compressor (in particular, essentially the same reduced fresh gas mass flow rate) as well as essentially the same (within 5%, preferably within 2% deviation) compressor efficiency are achieved in both operating positions. This allows adjustment of the trimmer without any effect on motor parameters, i.e.,without discontinuity in the course of the torque generated by the internal combustion engine and without the need for further engine interventions, such as adjusting a throttle valve, a camshaft adjuster and / or the ignition angle during operation of the internal combustion engine.

[0009] The compressor pressure ratio is defined as the ratio of the absolute pressure p2 of the fresh gas on the high-pressure side of the compressor to the absolute pressure p1 of the fresh gas on the low-pressure side of the compressor. The reduced fresh gas mass flow rate ṁ red is calculated from the actual mass flow rate ṁ, the temperature T vV of the fresh gas on the low-pressure side of the compressor, a reference temperature T ref (293.15 K), the absolute pressure p vV of the fresh gas on the low-pressure side of the compressor and a reference pressure p ref (1000 mbar) according to the following formula: m˙red=m˙⋅TvVTref⋅prefpvV

[0010] An internal combustion engine suitable for the automated execution of a method according to the invention comprises at least one combustion engine (in particular a (self-igniting and quality-controlled) diesel engine or a (spark-ignition and quantity-controlled) gasoline engine or a combination thereof, e.g., a combustion engine with homogeneous compression ignition) and a fresh gas train, wherein a compressor is integrated into the fresh gas train and wherein a trim control is associated with the compressor, by which a peripheral section of the inlet cross-section of a compressor impeller of the compressor can be covered to a variable extent. In an enabling position of the trim control, the peripheral section of the inlet cross-section is covered relatively little, preferably as little as possible, and in a covering position of the trim control, it is covered relatively extensively, preferably as much as possible.Furthermore, such an internal combustion engine comprises a control device which is set up for the automated execution of a method according to the invention.

[0011] According to the invention, the "entry plane" of the compressor impeller is understood to be the plane closest to the trimmer, oriented perpendicular to the axis of rotation of the compressor impeller, and defined by the impeller blades of the compressor impeller by having at least a point-like section of one, several, or all of the leading edges of these impeller blades arranged within this plane. The "entry cross-section" of the compressor impeller is then the opening cross-section of the flow space located in this entry plane.

[0012] The trim control of an internal combustion engine according to the invention can, in principle, be designed in any way, for example according to one of the embodiments disclosed in DE 10 2010 026 176 A1, EP 3 018 355 A1, DE 10 2015 209 704 A1, DE 10 2014 225 716 A1 or WO 2014 / 131790 A1.

[0013] According to a preferred embodiment, the trimmer of an internal combustion engine according to the invention comprises an annular aperture. The aperture can, for example, be in the form of an iris diaphragm, as is generally known from camera lenses. Alternatively, the aperture can also comprise a stator and a rotor, particularly annular, arranged side by side in the longitudinal axial direction, wherein both the stator and the rotor each form at least one through-opening. These through-openings can be moved into different relative positions by a rotation of the rotor relative to the stator, in which they are not, partially, or completely overlapping. A trimmer comprising only such an aperture can be characterized by a relatively simple design.

[0014] According to a preferred embodiment of such a trimmer with an annular orifice, it can be further provided that it additionally comprises a flow guidance device by which at least a section of the fresh gas stream is divided into a central flow region and a peripheral flow region, both of which transition into a flow chamber of the compressor that accommodates the compressor impeller in the region of the compressor impeller inlet plane, wherein the peripheral flow region can be closed off as required by means of the orifice. The orifice can preferably be arranged at the upstream end of the peripheral flow region. By means of such a combination of orifice and flow guidance device, the function of the trimmer can be improved, particularly with regard to its positive effect on the compressor performance map, compared to a trimmer comprising only an annular orifice.

[0015] The effect of such a trim control with orifice and flow guide device can be further improved if at least one end section of the flow guide device adjacent to the compressor impeller, or optionally the entire flow guide device, is designed to be longitudinally displaceable (i.e. along the axis of rotation of the compressor impeller), wherein the peripheral flow area in the region of the inlet plane of the compressor impeller is closed by this end section in a closed position of the flow guide device and released in an open position.

[0016] Since compressor efficiencies cannot be directly measured during the operation of the internal combustion engine, the exhaust gas pressure upstream of an exhaust gas turbine, which is connected to the compressor in a rotational driving manner, can be used for a given engine operating condition to determine the overall efficiency of the exhaust gas turbocharger. An internal combustion engine according to the invention can, for this purpose, include an exhaust gas pressure sensor integrated into the exhaust stream of the internal combustion engine upstream of the exhaust gas turbine.

[0017] Preferably, it can be provided that, during an application run of the internal combustion engine, the exhaust gas pressures upstream of the exhaust gas turbine are determined for a plurality of operating conditions for the compressor operating with the trim control in both the enable position and the cover position. Based on these determinations, an adjustment range for all operating conditions is derived and, in particular, interpolated. The determined adjustment range is then used for normal operation of the internal combustion engine. This makes it possible to derive an operating map for the internal combustion engine with an integrated adjustment range through relatively few measurements during an application run, which can be carried out, in particular, on a test bench. This adjustment range then provides the information required for adjusting the trim control for all operating conditions that can occur during normal operation of the internal combustion engine.

[0018] According to a further preferred embodiment of a method according to the invention, adjustment between the release position and the cover position can be made when, with identical compressor pressure conditions and fresh gas mass flow, the same compressor efficiency plus a hysteresis value, for example 2%, is achieved. The compressor efficiency in the operating position to which the trimmer is moved should thus be greater when adjusted by the hysteresis value than the compressor efficiency in the operating position from which the trimmer is moved. This avoids relatively frequent adjustment of the trimmer during continuous operation of the internal combustion engine within the trimmer's adjustment range and thus prevents potential mechanical overload of the trimmer.

[0019] An internal combustion engine according to the invention can, in particular, be part of a motor vehicle. The internal combustion engine of the internal combustion engine can, in particular, be intended for the direct or indirect provision of propulsion power to the motor vehicle. Such a motor vehicle can, in particular, be a wheeled and not rail-bound motor vehicle (preferably a passenger car or a truck).

[0020] The indefinite articles (“a”, “an”, “one”, and “ones”), particularly in the patent claims and in the description generally explaining the patent claims, are to be understood as such and not as numerals. Accordingly, components specified by these articles are to be understood as existing at least once and potentially existing multiple times.

[0021] The present invention is explained in more detail below with reference to embodiments and configurations illustrated in the drawings. The drawings show, in simplified form: Fig. 1: an internal combustion engine according to the invention; Fig. 2: a longitudinal section through a compressor for an internal combustion engine according to the invention with an associated trimming control in a position covering as little as possible an inlet cross-section of an impeller of the compressor; Fig. 3: the compressor according to the Fig. 2 with the trimmer in a position that covers the inlet cross-section of the compressor impeller as much as possible; Fig. 4: a characteristic curve of a compressor according to the Fig. 2 and Fig. 3; Fig. 5: the exhaust gas pressure profiles upstream of the exhaust gas turbine of a compressor according to the Fig. 2 and Fig. 3 exhaust gas turbochargers, each above the reduced mass flow of the fresh gas through the compressor, on the one hand with the compressor's trim control in the cover position and on the other hand with the trim control in the release position; Fig. 6: the Fig. 5 corresponding efficiency curves of the exhaust gas turbocharger; Fig. 7: the Fig. 5 corresponding efficiency curves of the exhaust gas turbine; Fig. 8: the Fig. 5 corresponding efficiency curves of the compressor; and Fig. 9: the Fig. 5 corresponding curves of the speeds of the exhaust gas turbocharger.

[0022] The Fig. Figure 1 shows a schematic representation of an internal combustion engine according to the invention, comprising a spark-ignition engine 10 with a plurality of cylinders 12. The cylinders 12, together with pistons moving up and down within them and a cylinder head (not shown), define combustion chambers in which fresh gas is combusted together with fuel. The fuel is injected directly into the combustion chambers by means of injectors 16, controlled by a control device 14 (engine control unit). The combustion of the fuel-fresh gas mixture results in cyclical up-and-down movements of the pistons, which are transmitted in a known manner via connecting rods (not shown) to a crankshaft (also not shown), thereby rotating the crankshaft.

[0023] The fresh gas is supplied to the combustion engine 10 via a fresh gas line and is drawn in from the environment through an intake opening 18, cleaned in an air filter 20, and then fed into a compressor 22, which is part of an exhaust gas turbocharger. The fresh gas is compressed by the compressor 22, then cooled in a charge air cooler 24, and then fed to the combustion chambers. The compressor 22 is driven by an exhaust gas turbine 26 of the exhaust gas turbocharger, which is integrated into an exhaust gas line of the combustion engine. Exhaust gas, which is produced during the combustion of the fuel-fresh gas mixture in the combustion chambers of the combustion engine 10, is discharged from the combustion engine 10 via the exhaust gas line and flows through the exhaust gas turbine 26. This results, in a known manner, in the rotating drive of a turbine impeller (not shown), which is connected to a compressor impeller 30 (see figure) via a shaft 28. Fig. 2 and Fig. 3) of the compressor 22. The rotating drive of the turbine impeller is thus transferred to the compressor impeller 30.

[0024] To achieve the most optimal use of the exhaust gas enthalpy for generating compression power via the exhaust gas turbocharger when operating the internal combustion engine 10 with varying loads and speeds, the exhaust gas turbine 26 of the exhaust gas turbocharger can optionally include a variable turbine flow (VTG) device 32, controllable by means of the control device 14. This VTG device can comprise a plurality of guide vanes (not shown) arranged in an inlet channel of the exhaust gas turbine 26, which are individually rotatable and can be adjusted together by means of an adjustment device (not shown). Depending on the rotational positions of the guide vanes, they narrow the free flow cross-section in the inlet channel of the exhaust gas turbine 26 to a greater or lesser extent and also influence the section of the primary flow to the turbine impeller and the direction of this flow.

[0025] Downstream of the compressor 22, a throttle valve 34, which can also be controlled by means of the control device 14, is integrated into the charge air path, i.e., into that section of the fresh gas line which is located between the compressor 22 and the combustion engine 10.

[0026] The internal combustion engine can include an exhaust gas recirculation line 36 for implementing (low-pressure) exhaust gas recirculation, in which exhaust gas from a section of the exhaust stream located downstream of the exhaust turbine 26 and, in particular, also downstream of an exhaust aftertreatment device 38, for example, a particulate filter, can be diverted and introduced into a section of the fresh gas stream upstream of the compressor impeller 30. The amount of exhaust gas to be recirculated via the exhaust gas recirculation line 36 can be controlled or regulated by means of a control valve 40, which can be actuated by the control device 14. Furthermore, an exhaust gas cooler 42 can be integrated into the exhaust gas recirculation line 36 for cooling the exhaust gas flowing through it.

[0027] A trimmer 44 is assigned to the compressor 22, by means of which the flow of fresh gas to the compressor impeller 30 can be influenced. For this purpose, the trimmer 44, or an associated actuator (not shown), can be controlled by the control device 14. The exhaust gas recirculation line 36 can open into the fresh gas stream upstream or on the side of the trimmer 44 facing away from the compressor impeller 30. An opening downstream or in the area of ​​the trimmer 44 (and upstream of the compressor impeller 30) is also possible.

[0028] The Fig. 2 and Fig. Figure 3 shows a longitudinal section of a possible embodiment for a compressor 22 of an internal combustion engine according to the invention. This compressor 22 can, for example, be used for an internal combustion engine according to the Fig. 1 is provided, in which the trimming control 44 and a connection channel 46 for the exhaust gas recirculation line 36 are integral components of the compressor 22. This is in the Fig. 1 indicated by a dashed frame.

[0029] The compressor 22 according to the Fig. 2 and Fig. 3 comprises a housing 50, which can be a partial housing of a complete housing of an exhaust gas turbocharger. The housing 50 of the compressor 22 forms a flow chamber 52, within which the compressor impeller 30 is rotatably mounted. On the inlet side, the flow chamber 52 has an inlet cross-section located in an inlet plane 54. Fresh gas can be supplied from a compressor inlet 58 to the compressor impeller 30 via an inlet channel 56, which is also formed by the housing 50 of the compressor 22. On the outlet side, the flow chamber 52 is bounded by an "outlet plane" that surrounds the exit edges of impeller blades 60 of the compressor impeller 30. A diffuser chamber 62, also surrounding the exit edges of the impeller blades 60, closes there, and adjoining this, what is described in the Fig. 2 and Fig. 3, which is no longer shown, is a compressor volute. A compressor outlet (also not shown) extends from the compressor volute.

[0030] Within the inlet channel 56, the trimmer 44 is arranged at the shortest possible distance to the inlet cross-section of the compressor impeller 30. The trimmer 44 includes an iris diaphragm 48 with a design also known from camera lenses. In a covering position S T2 according to the Fig. 3. The trimmer 44 prevents, as far as possible, the flow of fresh gas towards the compressor impeller 30 in an annular region of the inlet cross-section located at the edge. The trimmer 44 thus focuses this fresh gas flow onto a section of the compressor impeller 30 near the hub. In a release position S T1 according to the Fig. 2. In contrast, the fresh gas can flow into the compressor impeller 30 across the entire inlet cross-section. The aperture elements forming the iris diaphragm 48, which are each pivotably mounted within the housing 50 about an axis for opening or closing the iris diaphragm 48, are in the release position S. T1 completely arranged in an annular recess 64 of the housing 50.

[0031] According to the invention, it is provided that during the operation of an internal combustion engine in accordance with the Fig. 1 of the trim control 44 between the release position S T1 and the cover position S T2 The adjustment occurs when the same compressor pressure ratio π is used in both operating positions. V , the same (reduced) fresh gas mass flow (ṁ red ) and essentially the same compressor efficiency η V This is achieved by adjusting the trimmer 44 while maintaining only "essentially" the same compressor efficiency η. VThis occurs because the theoretical adjustment point is determined by the same values ​​for the compressor pressure ratio π. V and the reduced fresh gas mass flow ṁ red as well as by the same values ​​for compressor efficiency η V The adjustment is defined, but a hysteresis is provided for the actual adjustment, which is intended to prevent relatively frequent adjustment of the trim control 44 during prolonged operation of the internal combustion engine in the region of the theoretical adjustment point. The corresponding hysteresis value is 2% as an example.

[0032] In order to determine a switching range for the compressor 22 that takes this hysteresis value into account, the two compressor characteristic curves for operation of the compressor 22 with the trimmer 44 in the enable position S are determined in a known manner during an application operation of the internal combustion engine. T1 and on the other hand, the cover position ST2 identified and related to each other, as exemplified in the Fig. Figure 4 shows the compressor characteristic curve, which is drawn with solid lines. This curve represents the operation of the compressor 22 with the trimmer 44 in the release position S. T1 describes, while the compressor characteristic curve, which is drawn with dotted lines, describes the operation of the compressor 22 with the trimmer 44 in the cover position S T2 characterized.

[0033] Furthermore, for a plurality of defined compressor pressure ratios π V the compressor efficiency η in each case V in an operation with, on the one hand, the trimmer 44 in the release position S T1 and on the other hand with the trimmer 44 in the cover position S T2 The compressor efficiency η is determined. VEach value is determined as a function of a measurement of the exhaust gas pressure in the exhaust stream of the internal combustion engine upstream of the exhaust turbine 26. The two corresponding curves (versus the reduced fresh gas mass flow), one for the trim control 44 in the enable position S. T1 (solid line) as well as for the trimmer 44 in the cover position S T2 (dotted line) are in the Fig. 5 for an exemplary compressor pressure ratio π V , which is based on a boost pressure p2 of 1600 mbar. The corresponding efficiency curves η ATL of the exhaust gas turbocharger overall ( Fig. 6) and for which these efficiencies η ATL efficiencies influencing the exhaust gas turbocharger η T , η V the exhaust turbine 26 ( Fig. 7) and of the compressor 22 ( Fig. 8) are shown in further diagrams. The diagram of Fig. Figure 9 additionally shows the curves for the rotational speeds nATL of the exhaust gas turbocharger during the corresponding measurements.

[0034] Into the (double) map according to the Fig. 1 will be used for the area in which the two compressor characteristic curves overlap and in which, consequently, operation of the compressor 22 with the trimmer 44 in either the cover position S is generally possible. T2 or the release position S T1 It is possible to plot curves that correspond to the different efficiency differences between the two operating positions of the trimmer 44. Positive percentage values ​​indicate an efficiency advantage for operating the compressor 22 with the trimmer 44 in the cover position S. T2 , while negative percentage values ​​indicate an efficiency advantage for operating the compressor 22 with the trimmer 44 in the release position S T1The dotted line indicates the (equality) curve on which the compressor efficiencies η are plotted. V identical, or rather, the efficiency differences are zero. A theoretical adjustment point for adjusting the trimmer 44 between the release position S T1 and the cover position S T2 for a defined compressor pressure ratio π V and a defined reduced fresh gas mass flow rate ṁ red It therefore lies on this curve, whereby a hysteresis value of 2% is taken into account for actual adjustment. Thus, for example, if the compressor 22 is set to the enable position S with the trimmer 44... T1 at a specific compressor pressure ratio π V and a specific reduced fresh gas mass flow ṁr ed operated, in which an efficiency advantage is achieved compared to a corresponding operation with the trimmer 44 in the cover position ST2 sets (i.e., the location of such an operating point would be in the characteristic map of the Fig. 4 to the right of the dashed curve), and the compressor pressure ratio π changes during further operation. V and / or the reduced fresh gas mass flow ṁr ed In such a way that this operating point shifts in the direction of the dashed equality curve, the trimmer is not adjusted as soon as the dashed equality curve is reached, but only when (and provided that) the operating point follows the curve for the two percent efficiency advantage (hysteresis value) of operating the compressor 22 with the trimmer 44 in the cover position S. T2 achieved. In the Fig. Figure 4 illustrates this for the example full-load curve using a cross to mark the theoretical adjustment point and a circle to mark the actual adjustment point. Similarly, an adjustment from the cover position S would be represented. T2 into release position S T1 only when a corresponding efficiency advantage of 2% is achieved, as is the case in the Fig. 4 is shown using the adjustment point marked by a rectangle on the full load curve. Reference symbol list 10 Internal combustion engine 12 cylinders 14 Control device 16 injectors 18 Intake nozzle 20 air filters 22 compressors 24 Intercoolers 26 Exhaust turbine 28 wave 30 compressor impeller 32 Device for variable turbine flow 34 Throttle valve 36 Exhaust gas recirculation line 38 Exhaust aftertreatment device 40 Control valve 42 Exhaust gas coolers 44 trimmers 46 connection channel 48 Iris diaphragm 50 Compressor housing 52 Flow chamber 54 Inlet level of the compressor impeller 56 Inlet channel 58 Compressor inlet 60 wheel blade 62 Diffuser space 64 Recess of the housing π V compressor pressure ratio p2 Pressure in the charge air system η ATL Efficiency of the exhaust gas turbocharger η T Efficiency of the exhaust gas turbine η V Compressor efficiency n ATL Turbocharger speed ṁr ed reduced fresh gas mass flow

Claims

[1] Method for operating an internal combustion engine with an internal combustion engine (10) and a fresh gas stream, wherein a compressor (22) is integrated into the fresh gas stream and wherein a trim control (44) is associated with the compressor (22), by which a marginal section of the inlet cross-section of a compressor impeller (30) of the compressor (22) can be variably covered, wherein the marginal section of the inlet cross-section is in a release position (S T1 ) of the trim knob (44) relatively little and in a cover position (S T2 ) of the trimmer (44) is relatively largely covered, characterized by , that the trim control (44) is between the release position (S T1 ) and the cover position (S T2 ) is adjusted when the same compressor pressure ratio (π) is used in both operating positions V ) and the same fresh gas mass flow rate (ṁ) and essentially the same compressor efficiency (η) V ) is achieved. [2] Method according to claim 1, characterized by , that the trimmer (44) closes the edge section of the inlet cross-section in the release position (S T1 ) covers as little as possible and / or in the covering position (S T2 ) covers as much as possible. [3] Method according to claim 1 or 2, characterized by , that the compressor efficiency (n V ) is determined based on a measured value for the pressure of the exhaust gas in an exhaust gas stream of the internal combustion engine upstream of an exhaust gas turbine (26) which is connected to the compressor (22) in a rotationally driving manner. [4] Method according to any one of the preceding claims, characterized by , that in an application operation of the internal combustion engine for a plurality of operating conditions the exhaust gas pressures upstream of the exhaust gas turbine (26) are controlled by the trim control (44) in the release position on the one hand and in the cover position on the other hand (S T2) is determined and, based on this, an adjustment range for all operating conditions is derived, whereby the determined adjustment range is used for normal operation of the internal combustion engine. [5] Method according to any one of the preceding claims, characterized by , that the trim control (44) is between the release position (S T1 ) and the cover position (S T2 ) is adjusted when the same compressor efficiency (n) V ) plus a hysteresis value. [6] Internal combustion engine with an internal combustion engine (10) and a fresh gas stream, wherein a compressor (22) is integrated into the fresh gas stream and wherein a trim control (44) is associated with the compressor (22), by which a marginal section of the inlet cross-section of a compressor impeller (30) of the compressor (22) can be variably covered, wherein the marginal section of the inlet cross-section is in a release position (S T1) of the trim knob (44) relatively little and in a cover position (S T2 ) of the trimmer (44) is relatively largely covered, characterized by a control device (14) which is configured for the automated execution of a method according to one of the preceding claims. [7] Internal combustion engine according to claim 6, characterized by , that the trim control (44) includes an annular aperture (48). [8] Internal combustion engine according to claim 7, characterized by , that the trimming device (44) additionally comprises a flow guidance device by which at least one section of the fresh gas stream is divided into a central flow region and a peripheral flow region, both of which transition into a flow chamber (52) of the compressor (22) in the area of ​​the inlet plane (54) of the compressor impeller (30), wherein the peripheral flow region is designed to be closable by means of the orifice (48). [9] Internal combustion engine according to claim 8, characterized by , that at least one end section of the flow guidance device located adjacent to the compressor impeller (30) is designed to be longitudinally displaceable, wherein the peripheral flow area in the area of ​​the inlet plane (54) of the compressor impeller (30) is closed by this end section in a closed position of the flow guidance device and released in an open position. [10] Internal combustion engine according to any one of claims 6 to 9, characterized by , that an exhaust pressure sensor is integrated into an exhaust stream of the internal combustion engine upstream of an exhaust turbine (26).

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