METHOD FOR OPERATING AN ENGINE WITH A TRIM CONTROL ASSOCIATED TO THE COMPRESSOR

Abstract

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 stream, and wherein a compressor is integrated into the fresh gas stream, to which a trim control is assigned. This trim control allows for variable coverage of a marginal portion of the inlet cross-section of a compressor impeller. In the enabled position (Sn) of the trim control, the marginal portion of the inlet cross-section is relatively little covered, and in the covered position (ST2) of the trim control, it is relatively extensively covered. The trim control is designed to be moved to the covered position (ST2) during the transition from acceleration (Sn) to deceleration (S2) of the combustion engine. This prevents or minimizes the so-called relief whine.

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 / 131790 A1, serves to shift the surge line of a compressor characteristic curve towards relatively low mass flow rates at relatively 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 results in a suction-side shift in the flow approaching 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 of the compressor characteristic curve to lower mass flow rates. If control intervention is not desired (trim control fully open), the entire flow approaching the compressor impeller is designed to be as free from additional friction or throttling losses as possible. Therefore, the compressor efficiency and the width of the compressor characteristic curve are not negatively affected to a significant degree by a trim control in the direction of the surge line.

[0004] The possibility of backflow of already compressed fresh gas due to the incomplete separation of the high-pressure and low-pressure sides by the compressor impeller—a consequence of the turbocharged compressor design commonly used in automotive engineering—can also prove problematic when a throttle valve integrated into the charge air system, which was previously wide open, is rapidly closed. This occurs during the transition from acceleration to deceleration of the internal combustion engine. The inertia of the internal combustion engine system can then cause the compressor to continue pumping gas, potentially at high compression power, into the charge air system already interrupted by the closed throttle valve. This results in a correspondingly high compressor pressure ratio coupled with a very low mass flow rate of fresh gas through the compressor.These conditions favor a backflow of compressed fresh gas over the compressor impeller, which is then not driven or only driven at a low speed.

[0005] Fresh gas flowing back in this way can propagate in a wave-like pattern, which can lead to corresponding vibration excitation of components of the fresh gas line upstream of the compressor impeller. The noise associated with this vibration excitation is often referred to as "relief hissing".

[0006] Such a hissing sound during pressure relief can be avoided by integrating a bypass air system into the compressor. This system consists of a bypass line that can be opened or closed as needed via a bypass air valve. It connects a section of the flow path in the compressor downstream of the compressor impeller with a section upstream of the impeller. A relatively high compressor pressure ratio across the impeller, which could lead to a hissing sound, can be reduced by appropriately opening the bypass air valve. However, the cost of such a bypass air system is relatively high.

[0007] Furthermore, sound-absorbing elements can be integrated into the section of the fresh gas line located upstream of the compressor inlet to minimize the effects of vibration excitation and thus reduce hissing noise. However, this is also associated with relatively high costs. Moreover, such a measure typically requires a relatively large installation space.

[0008] WO 2004 / 022956 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, for example, by adjusting the flow pattern to the exhaust turbine driving the compressor via a variable turbine geometry (VTG) device.

[0009] The invention was based on the objective of developing a compressor-charged internal combustion engine that is characterized by the most optimal possible operating behavior, especially with regard to acoustic behavior.

[0010] 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 and a motor vehicle with such an internal combustion engine are the subject matter of claims 5 and 10. Advantageous embodiments of the method according to the invention and preferred configurations of the internal combustion engine according to the invention, and thus of the motor vehicle according to the invention, are the subject matter of further claims and / or will become apparent from the following description of the invention.

[0011] The invention is based on the idea of ​​actively using a trimmer in a compressor-charged internal combustion engine, in which a trimmer is assigned to the compressor to improve its operating behavior, in order to avoid or at least minimize a relief hissing sound that can occur in turbocharged internal combustion engines when transitioning from traction to thrust operation.

[0012] Accordingly, 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, to which a trim control is assigned, 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 open position of the trim control, the peripheral section of the inlet cross-section is covered relatively little, preferably as little as possible (i.e., as little as is maximally possible by the design), and in a closed position of the trim control, it is covered relatively extensively, preferably as extensively as possible (i.e., as extensively as is maximally possible by the design).According to the invention, it is provided that the trim control is moved to the cover position during a transition from a pull operation of the internal combustion engine, in which the trim control is in the release position, to a push operation of the internal combustion engine.

[0013] In traction mode, the internal combustion engine is characterized by the fact that it operates under load and consequently generates drive power. In contrast, coasting mode is characterized by the fact that no load is demanded on the internal combustion engine and it is driven; in the preferred integration of an internal combustion engine according to the invention in a motor vehicle, such drive of the internal combustion engine is achieved in particular by the motor vehicle rolling with an uninterrupted drivetrain.

[0014] In an internal combustion engine according to the invention, such a transition from traction operation to overrun operation can be associated in particular with a complete or as far as possible closing of a throttle valve integrated into the charge air path (the section of the fresh gas line that connects the compressor to the internal combustion engine).

[0015] According to the invention, the adjustment of the trim control is performed as directly as possible with the removal of the load, which characterizes the transition from acceleration to deceleration, or with the commencement of an associated closing movement of the throttle valve. It is also possible to initiate the adjustment of the trim control with a command to remove the load, for example, by releasing the accelerator pedal of a motor vehicle comprising an internal combustion engine according to the invention. This may differ slightly in time from the actual removal of the load by a control device of the internal combustion engine and / or from the closing of a throttle valve. However, a slightly delayed adjustment of the trim control is also possible, for example, up to a maximum of 0.3 seconds after the transition from acceleration to deceleration.

[0016] According to the invention, the trimmer of an internal combustion engine is actively moved into the covering position when, as a result of a transition from traction to thrust operation, a backflow of already compressed fresh gas from the high-pressure side to the low-pressure side of the compressor can occur at the edge of the compressor. The trimmer, which then covers a relatively large portion of the edge of the compressor impeller's inlet cross-section, prevents or disrupts such backflow or its further propagation into the section of the fresh gas stream upstream of the trimmer, thereby preventing or minimizing vibration excitations that would lead to a hissing sound during pressure relief.

[0017] An internal combustion engine suitable for the automated execution of a method according to the invention comprises at least one internal combustion engine (in particular a spark-ignition engine or another externally spark-ignited and quantity-controlled internal combustion engine, at least intermittently) and a fresh gas stream, wherein a compressor is integrated into the fresh gas stream and wherein a trim control is associated with the compressor, by which a peripheral section of the inlet cross-section of a compressor impeller can be variably covered. In an open 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 closed 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 configured for the automated execution of a method according to the invention.

[0018] 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 arranging at least a point-like section of one, several, or all of the leading edges of these impeller blades 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.

[0019] 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.

[0020] 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 which 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.

[0021] According to a preferred embodiment of such a trim control with an annular orifice for an internal combustion engine according to the invention, it can be 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 in the region of the inlet plane of the compressor impeller, wherein the peripheral flow region is designed to be closable 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 in comparison to a trimmer which only includes an annular orifice, both with regard to the effects on the compressor characteristic map and with regard to the suppression of a relief hiss.

[0022] The function of such a trimmer with aperture 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.

[0023] According to a preferred embodiment of a method according to the invention, the trim control can be reset to the release position after a defined limit value has been reached during continued thrust operation. This can serve, in particular, to relieve the load on an actuator provided for actuating the trim control, or to avoid unnecessarily long periods of load on it. Such a procedure can be provided, in particular, in an embodiment of the trim control of an internal combustion engine according to the invention, which is configured such that, in the absence of actuation by the control device, the trim control is automatically returned to a release position by means of a return device, which can be designed, in particular, in the form of a spring element. In this position, the trim control covers the outermost section of the inlet cross-section as little as possible.Such a design of the trimmer allows in particular a so-called failsafe functionality to be realized, since the reset device moves the trimmer to the release position covering the smallest possible inlet cross-section in the event of a failure of the control device or the actuator operating the trimmer, thereby ensuring emergency operation of the compressor with the least possible loss of function.

[0024] The limit value, at the point at which the trimmer is preferably returned to the release position, is preferably defined such that upon reaching this value, there is no longer a risk of a hissing noise occurring. The limit value can, in particular, define a time interval, such that the trimmer is moved back to the release position a defined time after the transition from traction operation to (continued) thrust operation and the adjustment of the trimmer from the release position to the cover position as provided for in the invention, because sufficient equalization of the gas pressures on the high-pressure and low-pressure sides of the compressor can be assumed.Likewise, the limit value can advantageously define a gas pressure (as absolute pressure, relative pressure, or differential pressure) in the fresh gas line, so that adjusting the trim control (again) to the release position is carried out when sufficient equalization of the gas pressure on the high-pressure side and the low-pressure side of the compressor has been achieved.

[0025] The compressor of an internal combustion engine according to the invention can, in particular, be part of an exhaust gas turbocharger, which further comprises an exhaust gas turbine integrated into the exhaust stream, wherein the preferably provided exhaust gas recirculation line can then branch off from the exhaust stream, in particular downstream of the exhaust gas turbine. The compressor is then driven by means of the exhaust gas turbine using the exhaust gas enthalpy. Alternatively or additionally, the compressor can also be designed to be driven in another way, for example by the internal combustion engine, i.e., mechanically, or by means of an electric motor.

[0026] An internal combustion engine according to the invention can, in particular, be part of a (motor vehicle according to the invention). The internal combustion engine of the motor vehicle can, in particular, be provided for the direct or indirect provision of propulsion power for the motor vehicle.

[0027] Such a motor vehicle may in particular be a wheel-based and not rail-bound motor vehicle (preferably a car or a truck).

[0028] The indefinite articles ("ein", "eine", "einer" and "eines"), especially in the

[0029] The patent claims and the description generally explaining the patent claims are to be understood as such and not as numerical terms. Accordingly, components specified by these claims are to be understood as existing at least once and potentially multiple times.

[0030] 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 Fig. 1 with an associated trimmer in a position covering the inlet cross-section of a compressor impeller as little as possible; Fig. 3: the compressor according to Fig. 2 with the trimmer in a position covering the inlet cross-section of the compressor impeller as much as possible; and Fig. 4: in a total of four diagrams, the curves of various characteristic values ​​during a section of operation of an internal combustion engine according to the invention, which includes a transition from traction operation to thrust operation.

[0031] 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 driving the crankshaft in a rotating manner.

[0032] 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 Fig. 28) via a shaft 28 to prevent rotation.2 and 3) of the compressor 22. The rotating drive of the turbine impeller is thus transferred to the compressor impeller 30.

[0033] To achieve the most optimal use of the exhaust gas enthalpy for generating compression power via the exhaust gas turbocharger when the internal combustion engine 10 is operated with varying loads and speeds, the exhaust gas turbine 26 of the exhaust gas turbocharger can optionally have 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 collectively 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.

[0034] 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 the section of the fresh gas line located between the compressor 22 and the combustion engine 10.

[0035] 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.

[0036] 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 outlet downstream or in the area of ​​the trimmer 44 (and upstream of the compressor impeller 30) is also possible.

[0037] Figures 2 and 3 each show a longitudinal section of a possible embodiment of a compressor 22 according to the invention. This compressor 22 can, for example, be provided for an internal combustion engine according to Figure 1, in which case the trim control 44 and a connecting channel 46 for the exhaust gas recirculation line 36 are integral components of the compressor 22. This is indicated in Figure 1 by a dashed frame.

[0038] The compressor 22 according to Figures 2 and 3 comprises a housing 50, which can be a partial housing of a complete exhaust gas turbocharger housing. 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 outlet edges of impeller blades 60 of the compressor impeller 30. There, a diffuser chamber 62, also surrounding the exit edges of the impeller blades 60, is connected, and following this, which is no longer shown in Figs. 2 and 3, a compressor volute.A compressor outlet (also not shown) extends from the compressor volute.

[0039] Within the inlet channel 56, the trimmer 44 is arranged as close as possible to the inlet cross-section of the compressor impeller 30. The trimmer 44 comprises an iris diaphragm 48 with a design also known from camera lenses. In a covered position as shown in 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 an open position as shown in Fig. 2, 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 arranged completely in an annular recess 64 of the housing 50 in the release position.

[0040] According to the invention, when operating an internal combustion engine as shown in Fig. 1, the trim control 44 is always adjusted to a cover position as shown in Fig. 3 during a transition from traction operation of the internal combustion engine 10, in which the trim control 44 is in a release position as shown, for example, in Fig. 2, to overrun operation, in order to prevent or at least minimize a hissing sound during the relief phase. Fig. 4 illustrates this procedure with four diagrams that show exemplary simultaneous curves of various characteristic values ​​during a phase of operation of the internal combustion engine that includes such a transition from traction operation to overrun operation.

[0041] The uppermost diagram in Fig. 4 shows the percentage opening position SD of the throttle valve 34, with the throttle valve 34 being open more fully the higher the percentage opening position. During acceleration of the internal combustion engine 10, the throttle valve 34 is therefore at least partially open, while it is completely closed (opening position: 0%) during deceleration of the internal combustion engine 10. The curve in the uppermost diagram of Fig. 4 thus shows a transition from acceleration of the internal combustion engine 10 to deceleration, with this transition, characterized by a complete removal of the load under which the internal combustion engine 10 is operated, being indicated by a vertical, dashed line. From this transition onward, the throttle valve 34 is moved to the fully closed position as quickly as possible.

[0042] The complete removal of the load for the operation of the internal combustion engine 10, which marks the transition from traction to overrun operation, leads to a relatively rapid decrease in the drive power of the exhaust gas turbine 26 and thus in the compression power of the compressor 22. The relatively high pressure p2 in the charge air section of the fresh gas stream, previously caused by the relatively high compression power during traction operation, does not decrease correspondingly rapidly, since the compressed fresh gas cannot flow back into the internal combustion engine 10 due to the closed throttle valve 34. Therefore, a reduction in the pressure difference between the high-pressure side and the low-pressure side of the compressor occurs through a backflow of compressed fresh gas via the compressor impeller 30, which rotates at only a relatively low speed. The upper of the two middle diagrams in Fig.Figure 4 illustrates this relatively slow pressure loss in the charge air path (until almost the ambient air pressure pu is reached) after a transition from traction operation to thrust operation.

[0043] The backflow of compressed fresh gas from the high-pressure side to the low-pressure side of the compressor 22, which causes this pressure loss in the charge air path, can lead to a relief hissing sound, since pressure oscillations can superimpose on the mean charge pressure shown in the upper of the middle diagrams of Fig. 4 and these pressure oscillations can lead to vibration excitations of components of the fresh gas path located upstream of the compressor impeller.

[0044] The bottom diagram in Fig. 4 illustrates this effect using curves for the sound pressure level LP (in dB), which was measured at a point outside the fresh gas stream near the compressor inlet 58. The first diagram, shown with a dashed line, depicts the sound pressure level LP that occurs when, during a transition from pull operation to push operation as shown in Fig. 4, the trim control 44, which was set to a (minimal coverage) release position as shown in Fig. 2 during pull operation, is left in this release position. A significantly higher sound pressure level Lp is evident shortly after the transition from pull operation to push operation compared to a procedure according to the invention (see the curve in the bottom diagram of Fig. 4 with solid lines), where, according to the lower of the two middle diagrams in Fig. 4, the sound pressure level LP is set to a significantly higher level shortly after the transition from pull operation to push operation.4 the trim control 44, which was previously in the release position Sn, is simultaneously moved to the (most comprehensive) cover position ST2 according to Fig. 3 during the transition from train operation to push operation. REFERENCE MARK LIST

[0045] 10 Internal combustion engine 12 Cylinder 14 Control device 16 Injector 18 Intake port 20 Air filter 22 Compressor 24 Charge air cooler 26 Exhaust turbine 28 Shaft 30 Compressor impeller 32 Variable turbine flow device 34 Throttle valve 36 Exhaust gas recirculation line 38 Exhaust aftertreatment device 40 Control valve 42 Exhaust gas cooler 44 Trim control 46 Connection channel 48 Iris diaphragm 50 Compressor housing 52 Flow chamber 54 Compressor impeller inlet plane 56 Inlet channel 58 Compressor inlet 60 Impeller blade 62 Diffuser chamber 64 Housing recess SD Throttle valve opening position p2 Charge air pressure pU Ambient air pressure ST Trimmer actuator position ST1 Trimmer actuator release position ST2 Trimmer actuator cover position LP Sound pressure level t Time

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 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 covered to a variable extent, wherein the marginal section of the inlet cross-section is covered relatively little in a release position (Sn) of the trim control (44) and relatively extensively in a covering position (S T2) of the trim control (44), characterized in that the trim control (44) is adjusted to the covering position (S T2) during a transition from a traction operation of the internal combustion engine (12), in which the trim control (44) is in the release position (S T1), to a push-pull operation of the internal combustion engine (10).

2. Method according to claim 1, characterized in that the trimmer (44) covers the edge section of the inlet cross-section as far as possible in the covering position (S T2).

3. Method according to claim 1 or 2, characterized in that the trimmer (44) is reset to the release position (S T1) after reaching a defined limit value.

4. Method according to claim 3, characterized in that the limit value defines a time sequence or a gas pressure in the fresh gas stream.

5. 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 covered to a variable extent, wherein the marginal section of the inlet cross-section is covered relatively little in a release position (Sn) of the trim control (44) and relatively extensively in a covering position (S T2) of the trim control (44), characterized by a control device (14) which is configured for the automated execution of a method according to one of the preceding claims.

6. Internal combustion engine according to claim 5, characterized in that the trim control (44) comprises an annular aperture (48).

7. Internal combustion engine according to claim 6, characterized in that the trim control (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).

8. Internal combustion engine according to claim 7, characterized in that at least one end section of the flow guidance device located adjacent to the compressor impeller (30) is designed to be longitudinally axially 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.

9. Internal combustion engine according to one of claims 5 to 7, characterized in that the trimming device (44) is actuated by means of a reset element into a release position (Sn) in which the trimming device (44) covers the edge section of the inlet cross-section as little as possible.

10. Motor vehicle with an internal combustion engine according to any one of claims 5 to 9.