Method for controlling internal combustion engine, control device, internal combustion engine and motor vehicle

Abstract

The invention relates to a method and a control device for controlling an internal combustion engine. The invention also relates to an internal combustion engine unit having an internal combustion engine and a control device and to a motor vehicle having an internal combustion engine unit. According to the method, the internal combustion engine is operated in a first operating mode (B1) when a first operating criterion is met, the closing of the intake valve ends at a first crankshaft angle (KW1) at a bottom dead center of the crankshaft (1); switching from the first operating mode to a second operating mode (B2) when a second operating criterion is met, the closing of the intake valve ending at a second crankshaft angle (KW2lt; and switching from the second operating mode to a third operating mode (B3) when a third operating criterion is met, the closing of the intake valve ending at a third crankshaft angle (KW3lt, KW2lt, KW1).

Description

Technical Field

[0001] The present invention relates to a method for controlling an internal combustion engine, a control device which is configured to carry out the method or to control an internal combustion engine, an internal combustion engine having the control device, and a motor vehicle having such an internal combustion engine. Background Art

[0002] There is a general need to keep pollutant emissions as low as possible throughout the entire operation of an internal combustion engine, that is, in all operating states, and to implement measures to enable increasingly low-emission operation of the engine. To this end, the goal is currently to ensure that the combustion process in the combustion chamber of the corresponding internal combustion engine always operates at a stoichiometric fuel-air ratio λ=1. Furthermore, it is known, for example, from DE 4480333 T1, DE 60301093 T2, or EP 3620635 A1, to control the intake valve mechanism so that the corresponding intake valve is fully closed already during the intake stroke (that is, well before the associated connecting rod journal of the crankshaft of the internal combustion engine reaches its bottom dead center). This reduces the filling level of the corresponding combustion chamber for a given structural compression ratio. The advantages of this are improved utilization of the expansion energy during the power stroke and, therefore, increased thermodynamic efficiency, reduced knock tendency, the ability to advance the ignition timing at full load, and reduced exhaust gas temperatures. In order to compensate for the performance disadvantages that arise when using this principle (known to those skilled in the art of internal combustion engines as the Miller cycle), an intake compressor (e.g. an exhaust gas turbocharger, a compressor, etc.) is used, whereby a higher intake pressure is provided than in a conventionally operated internal combustion engine with intake charging.

[0003] In modern internal combustion engines, the Miller cycle is used if the engine speed, load, and intake pressure permit or are not opposed to it. This results in early and effective cooling of the exhaust gas, preventing predefined temperature limits of engine components that come into contact with the exhaust gas or peripheral components and / or subassemblies of the engine from being exceeded. However, this early adoption of the Miller cycle also results in increased component loads on engine components, particularly the intake compressor, even when exhaust gas temperatures would be uncritical without the Miller exhaust gas cooling effect. Consequently, there is a conflict between the desire to realize the advantages of the Miller principle and the increased component loads on engine components, particularly the intake compressor, when the Miller principle is employed. Summary of the Invention

[0004] The object of the present invention is to operate an internal combustion engine particularly efficiently and with low emissions.

[0005] The object is achieved by the subject matter of the independent claims. Further possible embodiments of the invention are disclosed in the dependent claims, the description, and the drawings. The features, advantages, and possible embodiments described within the description for one of the subject matter of the independent claims are to be regarded as at least similarly, across categories and across embodiments, as the features, advantages, and possible embodiments of the corresponding subject matter of the other independent claims, as well as any possible combination of the subject matter of the independent claims (possibly in combination with one or more dependent claims).

[0006] During combustion operation of an internal combustion engine, the engine emits exhaust gas. For component protection of components of the internal combustion engine that come into contact with the exhaust gas, or for component protection of peripheral components and / or structural groups of the internal combustion engine, temperature limits are predetermined. The present invention is based on the recognition that, in average overall use of an internal combustion engine, for example, when a motor vehicle having an internal combustion engine is used by an end user, temperatures exceeding or approaching the predetermined temperature limits can be expected only very rarely. In order to at least mitigate the conflicting objectives described at the outset between the desire to effectively utilize the advantages of the Miller principle and the increased component loads on components of the internal combustion engine, in particular the intake compressor, a method for controlling an internal combustion engine according to the present invention is proposed.

[0007] The present invention also proposes a control device for an internal combustion engine, such as an engine controller, wherein the control device is configured to implement the method or to control the internal combustion engine according to the method. The present invention further proposes an internal combustion engine unit comprising the internal combustion engine and the control device. The control device and the internal combustion engine are coupled or can be coupled to each other so that a control signal provided by the control device causes an operation of the internal combustion engine. The present invention further proposes a motor vehicle comprising the internal combustion engine of the internal combustion engine unit as an engine. In a proper installation state of the internal combustion engine, the internal combustion engine forms a component of the vehicle, and the crankshaft of the internal combustion engine and the wheels of the vehicle are mechanically coupled or can be coupled to each other via one or more transmissions for power / torque transmission. Alternatively or additionally, the internal combustion engine forms a drive element for a generator, which is coupled or can be coupled to an electric drive motor, wherein the rotor of the electric drive motor is coupled or can be coupled to the wheels directly or via one or more transmissions for power / torque transmission. Accordingly, the motor vehicle can be a motor vehicle that can be propelled purely by an internal combustion engine or a motor vehicle that can be propelled hybridly by electric power.

[0008] The method for controlling an internal combustion engine according to the present invention may be a computer-implemented method. In this case, the control device is configured to implement the method. Furthermore, the present invention proposes a computer program that, when the control device executes its program instructions, causes the control device to implement the method and thereby provide control signals for the internal combustion engine. Furthermore, the present invention proposes a computer-readable storage medium on which the computer program is stored.

[0009] The internal combustion engine is designed as a four-stroke reciprocating piston internal combustion engine and comprises a crankshaft, combustion chambers, and intake valves associated with the combustion chambers. Furthermore, the internal combustion engine comprises an intake compressor for pre-compressing intake air for the internal combustion engine. The intake compressor comprises an intake compressor unit. The intake compressor unit is, in particular, an exhaust gas turbocharger or a compressor that can be driven mechanically and / or electrically by means of the crankshaft. Combinations of two or more intake compressors, in particular combinations of two or more intake compressors of different types, are conceivable. Other components required for a properly functioning internal combustion engine and possible configurations (in particular, having two or more combustion chambers, two or more intake valves per combustion chamber, etc.) are familiar to those skilled in the art, and therefore, only those necessary for the description will be discussed here. For simplicity of explanation, reference is made here to a single combustion chamber with an associated intake valve. When the intake valve is described as fully closed, this should be understood to mean that the intake valve seat of the combustion chamber is completely blocked by the intake valve body of the intake valve, thereby preventing the flow of a fluid (e.g., air, etc.). In the case where each combustion chamber has two or more intake valves, the expression “intake valves fully closed” may be understood to mean that all intake valves of the combustion chamber are completely blocked to prevent fluid from flowing through.

[0010] In the method, an intake valve train of an internal combustion engine is controlled such that, during an intake stroke following every two full revolutions of the crankshaft, the intake valve is fully moved into its closed position at various crankshaft angles, depending on the currently active operating mode of the internal combustion engine, as the crankshaft passes through it in a predetermined operating direction of rotation. In other words, during the respective intake stroke, movement of the intake valve body toward the closed position becomes impossible sooner or later, depending on the operating mode, because the intake valve body is fully seated on the intake valve seat at the respective crankshaft angle, completely blocking the seat and preventing flow. The intake valve train may, for example, include a camshaft- and / or valve-specific linear drive. In each case, the intake valve train is designed to adapt the control timing of the intake valve, i.e., to set the intake valve opening angle (here, the intake valve opening angle is specified relative to top dead center of the crankshaft).

[0011] In a first of the operating modes, the intake valve is actuated by the intake valve train such that during the intake stroke of the internal combustion engine, closing of the intake valve is completely completed at bottom dead center of the crankshaft at a first crankshaft angle KW1 (measured from top dead center of the crankshaft in the operating direction of rotation). In the first operating mode, adjustment of the intake valve to its closed position is completely completed at bottom dead center, i.e., closer to bottom dead center than in the other two operating modes. In a second of the operating modes, the intake valve is actuated by the intake valve train such that during the intake stroke, closing of the intake valve is completely completed at a second crankshaft angle KW2 (measured from top dead center of the crankshaft in the operating direction of rotation). Here, the second crankshaft angle KW2 is smaller than the first crankshaft angle KW1; adjustment of the intake valve to its closed position is completely completed closer to top dead center (i.e., earlier) than in the first operating mode. In the third of the operating modes, the intake valve is actuated by means of the intake valve train in such a way that closing of the intake valve during the intake stroke is completely completed at a third crankshaft angle KW3 (measured from top dead center of the crankshaft in the operating direction of rotation). The third crankshaft angle KW3 is smaller than the second crankshaft angle KW2; therefore, adjustment of the intake valve to its closed position is completely completed even closer to top dead center (i.e., even earlier) than in the second operating mode.

[0012] The respective crankshaft angles KW1, KW2, KW3 are derived in particular from the angle values ​​of the crankshaft angle ranges [KW1], [KW2], [KW3] assigned to the respective operating mode. All angle values ​​of the first crankshaft angle range [KW1] are greater than all angle values ​​of the second and third crankshaft angle ranges [KW2], [KW3], and all angle values ​​of the second crankshaft angle range [KW2] are greater than all angle values ​​of the third crankshaft angle range [KW3]. The following applies:

[0013] KW1 > KW2 > KW3 or [KW1] > [KW2] > [KW3].

[0014] Therefore, the closing of the intake valve is completely completed at a first crankshaft angle KW1 from the first crankshaft angle range [KW1] in the first operating mode, completely completed at a second crankshaft angle KW2 from the second crankshaft angle range [KW2] in the second operating mode, and completely completed at a third crankshaft angle KW3 from the third crankshaft angle range [KW3] in the third operating mode.

[0015] Furthermore, in the method, the internal combustion engine is controlled such that the engine is operated in a first operating mode if or as long as a first operating criterion is met. The first operating criterion may be met, for example, when the value of the intake pressure of the intake air flowing into the combustion chamber during the intake stroke lies within a predetermined first intake pressure value range, which includes values ​​from zero up to, and including, a predetermined first limit intake pressure value. Accordingly, the internal combustion engine is operated in the first operating mode if or as long as the intake air is compressed to the maximum predetermined first limit intake pressure by means of the intake compressor. The current intake pressure is thus determined, and if the value of this intake pressure lies within the predetermined first intake pressure value range, the internal combustion engine continues to operate in the first operating mode because the first sub-criterion related to the intake pressure is met. The predetermined first limit intake pressure, for example, represents an intake pressure at which the maximum possible torque of the internal combustion engine is achieved, for which the internal combustion engine is designed. This means that according to the method, the internal combustion engine is operated in a first operating mode, in which the intake valve is fully set to the closed position at a first crankshaft angle KW1 until the internal combustion engine provides the maximum possible torque. As a result, full torque can be provided to the vehicle particularly quickly. This is because the lower the intake pressure, the better the response behavior, i.e., the more dynamic the driving operation of the vehicle appears to the user or driver.

[0016] Furthermore, the first operating criterion may be satisfied, for example, when the current crankshaft speed value lies within a predetermined first speed value range, which includes values ​​from zero, in particular from an idling speed value, up to and including a predetermined first speed limit value. This determines the speed at which the crankshaft of the internal combustion engine is currently rotating. If the corresponding speed value lies within the predetermined first speed value range, the internal combustion engine continues to operate in the first operating mode because the first sub-criterion related to the crankshaft speed is satisfied.

[0017] Furthermore, the first operating criterion may be satisfied if the current load value of the internal combustion engine falls within a predetermined first load value range, which includes values ​​from zero up to, and including, a predetermined first limit load value. Therefore, if the load-related sub-criterion is satisfied, the internal combustion engine continues to operate in the first operating mode. To this end, the current load is determined. If the corresponding load value falls within the predetermined first load value range, the first load-related sub-criterion is satisfied.

[0018] Furthermore, the first operating criterion may be satisfied when the value of the current gear stage of the manual transmission coupled to the internal combustion engine is within a predetermined first gear stage value range, which includes values ​​from zero up to, and including, a predetermined first limiting gear stage value. The currently engaged and / or coupled gear stage is thus ascertained, and if the corresponding gear stage value is within the predetermined first gear stage value range, the first gear stage-related subcriterion is satisfied, and the internal combustion engine continues to operate in the first operating mode.

[0019] Furthermore, the first operating criterion may be satisfied when the value of the current driving speed of a motor vehicle having an internal combustion engine as an engine lies within a predetermined first speed value range, which includes values ​​from zero up to, and including, a predetermined first limit speed value. This determines how fast the motor vehicle is currently traveling. If the corresponding speed value lies within the predetermined first speed value range, the internal combustion engine continues to operate in the first operating mode because the first subcriterion related to the driving speed is satisfied.

[0020] Furthermore, the first operating criterion may be satisfied if the current operating duration value falls within a predetermined first time value range, during which the internal combustion engine last operated uninterrupted in the first operating mode, the first time value range including values ​​from zero up to (inclusive of) a predetermined first limiting operating time value. In other words, the duration for which the internal combustion engine last operated uninterrupted in the first operating mode is determined. If this time falls within the predetermined first time value range, the first sub-criterion related to the operating duration is satisfied, and the internal combustion engine continues to operate in the first operating mode.

[0021] Furthermore, the first operating criterion may be satisfied when the exhaust gas temperature value ascertained at a location in the exhaust duct of the internal combustion engine falls within a predetermined first exhaust gas temperature value range, wherein the first exhaust gas temperature value range includes values ​​from zero up to, and including, a predetermined first limit exhaust gas temperature value. Therefore, if the first exhaust gas temperature-related subcriterion is satisfied, the internal combustion engine continues to operate in the first operating mode. To this end, the current exhaust gas temperature at the corresponding exhaust duct location is ascertained. If the corresponding exhaust gas temperature value falls within the predetermined first exhaust gas temperature value range, the first exhaust gas temperature-related subcriterion is satisfied.

[0022] One, some, or all of the values ​​described herein may, in particular, be modeled, for example, by means of a control unit for the internal combustion engine and / or by means of other control units (e.g., a transmission control unit, etc.). Alternatively or additionally, one, some, or all of the values ​​described may be measured, for example, by means of appropriately configured and arranged sensors. Thus, for example, an exhaust gas temperature value may be ascertained by modeling the exhaust gas temperature present at a location in the exhaust duct, or a corresponding exhaust gas temperature value, for example, by means of a control unit for the internal combustion engine. Alternatively or additionally, an exhaust gas temperature value may be ascertained by measuring the exhaust gas temperature directly at a corresponding location in the exhaust duct, for example, by means of a temperature sensor. This applies similarly to other values ​​ascertained for the method or for its embodiments. Measuring and modeling the same values ​​to be ascertained may be possible, for example, for redundancy reasons or operational safety reasons, for plausibility checks, etc.

[0023] In particular, two or more of the aforementioned first partial criteria must be present, so that the first operating criterion is deemed to be satisfied and the internal combustion engine is operated in the first operating mode.

[0024] If, or as long as, another second operating criterion is satisfied, the internal combustion engine switches from the first operating mode to the second operating mode, in which the intake valve is fully set to the closed position at the second crankshaft angle KW2. The second operating criterion can be satisfied, for example, if the value of the intake pressure of the intake air lies within a predetermined second intake pressure value range, which includes values ​​from a predetermined first limit intake pressure (exclusive) to a predetermined second limit intake pressure (inclusive). Therefore, the current intake pressure is determined, and if this intake pressure value lies within the predetermined second intake pressure value range and therefore outside the predetermined first intake pressure value range, the internal combustion engine is switched to the second operating mode because the second partial criterion related to the intake pressure is satisfied.

[0025] Furthermore, the second operating criterion may be satisfied when the value of the current crankshaft speed of the internal combustion engine lies within a predetermined second speed value range, which includes values ​​from (excluding) a predetermined first speed limit value to (including) a predetermined second speed limit value. Thus, it is determined at what speed the crankshaft of the internal combustion engine is currently rotating. If the corresponding speed value lies within the predetermined second speed value range and therefore outside the predetermined first speed value range, the internal combustion engine is switched to the second operating mode because the second sub-criterion related to the crankshaft speed is satisfied.

[0026] Furthermore, the second operating criterion may be satisfied when the current load value of the internal combustion engine lies within a predetermined second load value range, which includes values ​​from (excluding) a predetermined first limit load value to (including) a predetermined second limit load value. Therefore, the internal combustion engine switches to the second operating mode when the second load-related subcriterion is satisfied. To this end, the current load is ascertained. The second load-related subcriterion is satisfied when the corresponding load value lies within the predetermined second load value range and, therefore, outside the predetermined first load value range.

[0027] Furthermore, the second operating criterion may be satisfied when the current transmission gear ratio value of the manual transmission is from a predetermined second transmission ratio value range, which includes values ​​from a predetermined first limiting transmission ratio value (exclusive) up to a predetermined second transmission ratio value (inclusive). The currently engaged and / or coupled transmission gear ratio is thus ascertained, and if the corresponding transmission ratio value is within the predetermined second transmission ratio value range and therefore outside the predetermined first transmission ratio value range, the second transmission ratio-related subcriterion is satisfied, and the internal combustion engine is switched to the second operating mode.

[0028] It is also conceivable that the second operating criterion is satisfied when the value of the current driving speed of the motor vehicle falls within a predetermined second speed value range, which includes values ​​from (excluding) a predetermined first limit speed value to (including) a predetermined second limit speed value. This determines how fast the motor vehicle is currently traveling. If the corresponding speed value lies within the predetermined second speed value range and therefore outside the predetermined first speed value range, the internal combustion engine switches to the second operating mode because the second subcriterion related to the driving speed is satisfied.

[0029] Furthermore, the second operating criterion may be satisfied when the current operating duration value falls within a predetermined second time value range, during which the internal combustion engine ultimately operated uninterrupted in the first operating mode, the second time value range encompassing values ​​from (excluding) a predetermined first limit operating time value to (including) a predetermined second limit operating time value. In other words, the duration for which the internal combustion engine ultimately operated uninterrupted in the first operating mode is determined. If this time falls within the predetermined second time value range, i.e., falls outside the predetermined first time value range, the second sub-criterion related to the operating duration is satisfied, and the internal combustion engine switches to the second operating mode.

[0030] Furthermore, the second operating criterion may be satisfied when the exhaust gas temperature value ascertained at a location in the exhaust duct of the internal combustion engine falls within a predetermined second exhaust gas temperature value range, which includes values ​​from (excluding) a predetermined first limit exhaust gas temperature value to (including) a predetermined second limit exhaust gas temperature value. Accordingly, the internal combustion engine switches to the second operating mode when the second exhaust gas temperature-related subcriterion is satisfied. To this end, the current exhaust gas temperature is ascertained at the corresponding exhaust duct location. The second exhaust gas temperature-related subcriterion is satisfied if the corresponding exhaust gas temperature value falls within the predetermined second exhaust gas temperature value range and therefore falls outside the predetermined first exhaust gas temperature value range.

[0031] In particular, two or more of the aforementioned second subcriteria must be present, so that the second operating criterion is deemed to be fulfilled and the internal combustion engine is switched to or operated in the second operating mode.

[0032] The method specifically provides for switching the internal combustion engine to a second operating mode as early as possible, in which the engine operates according to the Miller cycle with a first Miller intensity. This advantageously reduces the exhaust gas temperature particularly early. This is because the Miller combustion method reduces the effective compression ratio, or charge ratio, by initially expanding a portion of the intake air in the combustion chamber due to premature closing of the intake valve and then compressing it again. The resulting reduced effective compression ratio leads to a lower knock tilt, allowing for an earlier ignition angle to be set. The earlier the fuel-air mixture in the combustion chamber ignites, the earlier combustion starts, and the further the combustion propagates at the moment the exhaust valve opens. This results in lower exhaust gas temperatures. Components interacting with the exhaust gas, such as the intake compressor, can thus come into contact with particularly cool exhaust gas via the exhaust-driven turbine, exhaust aftertreatment devices, and the like, effectively preventing undesirably high temperatures, in particular, reaching predetermined temperature limits. Furthermore, the transition from the first to the second operating mode is achieved in a torque-neutral manner. That is, the intake valve opening angle and intake pressure are set while maintaining the current torque. Therefore, the occupants of the motor vehicle do not feel the change in operating mode.

[0033] The internal combustion engine switches from the second operating mode to the third operating mode only when a third operating criterion is satisfied. The third operating criterion is provided, in particular, for component protection of components of the internal combustion engine that come into contact with the exhaust gas and / or intake air, or peripheral components and / or subassemblies of the internal combustion engine. In the third operating mode, the intake valve is fully set to the closed position at the third crankshaft angle KW3. In particular, the internal combustion engine is operated in the third operating mode only when the third operating criterion is satisfied. The third operating criterion can be satisfied, for example, when the value of the intake pressure of the intake air falls within a predetermined third intake pressure value range, which includes values ​​starting from (but not including) a predetermined second limit intake pressure value and above. Therefore, the current intake pressure is determined, and if the value of the intake pressure falls within the predetermined third intake pressure value range and therefore falls neither within the predetermined first nor second intake pressure value ranges, the internal combustion engine switches to the third operating mode because the third subcriterion related to the intake pressure is satisfied.

[0034] Furthermore, the third operating criterion may be satisfied when the value of the current crankshaft speed of the internal combustion engine is within a predetermined third speed value range, which includes values ​​starting at (but not including) a predetermined second speed limit value and higher. This determines the speed at which the crankshaft of the internal combustion engine is currently rotating. If the corresponding speed value is within the predetermined third speed value range and therefore neither within the predetermined first speed value range nor within the predetermined second speed value range, the internal combustion engine is switched to the third operating mode because the third sub-criterion related to the crankshaft speed is satisfied.

[0035] Furthermore, the third operating criterion may be satisfied if the current load value of the internal combustion engine falls within a predetermined third load value range, which includes load values ​​starting from (but not including) a predetermined second limit load value and higher. Therefore, if the third load-related sub-criterion is satisfied, the internal combustion engine switches to the third operating mode. To this end, the current load is determined. The third load-related sub-criterion is satisfied if the corresponding load value falls within the predetermined third load value range, and therefore falls neither within the predetermined first load value range nor within the predetermined second load value range.

[0036] Furthermore, the third operating criterion may be satisfied when the current transmission gear ratio value of the manual transmission is within a predetermined third transmission ratio value range, which includes values ​​from (but not including) the predetermined second transmission ratio value range up to and including higher transmission ratio values. The currently engaged and / or coupled transmission gear ratio is thus ascertained, and if the corresponding transmission gear ratio value is within the predetermined third transmission ratio value range and outside the predetermined first and second transmission ratio value ranges, the third transmission ratio-related subcriterion is satisfied, and the internal combustion engine is switched to the third operating mode.

[0037] Furthermore, it is conceivable that the third operating criterion is satisfied when the value of the current driving speed of the motor vehicle is within a predetermined third speed value range, which includes speed values ​​starting from (but not including) a predetermined second limit speed value and higher. This allows for determining how fast the motor vehicle is currently traveling. If the corresponding speed value is within the predetermined third speed value range, and therefore neither within the predetermined first speed value range nor within the predetermined second speed value range, the internal combustion engine is switched to the third operating mode because the third sub-criterion related to driving speed is satisfied.

[0038] Furthermore, the third operating criterion may be satisfied when the value of the current uninterrupted operating duration falls within a predetermined third time value range, during which the internal combustion engine ultimately operated uninterrupted in the second operating mode, the third time value range including values ​​starting from (but not including) a predetermined second limit operating time value and higher. In other words, it is determined how long the internal combustion engine ultimately operated uninterrupted in the second operating mode. If this time falls within the predetermined third time value range, i.e., outside the predetermined first time value range, the second sub-criterion related to the operating duration is satisfied, and the internal combustion engine switches to the second operating mode.

[0039] Furthermore, a third operating criterion may be satisfied when the exhaust gas temperature value ascertained at a location in the exhaust duct of the internal combustion engine falls within a predetermined third exhaust gas temperature value range, which includes exhaust gas temperature values ​​starting from (but not including) a predetermined second limit exhaust gas temperature value and exceeding it. Accordingly, the internal combustion engine switches to the third operating mode when the third exhaust gas temperature-related subcriterion is satisfied. To this end, the current exhaust gas temperature is ascertained at the corresponding exhaust duct location. If the corresponding exhaust gas temperature value is within the predetermined third exhaust gas temperature value range and therefore outside both the predetermined first exhaust gas temperature value range and the predetermined second exhaust gas temperature value range, the third exhaust gas temperature-related subcriterion is satisfied.

[0040] In particular, two or more of the aforementioned third sub-criteria must be present, so that the third operating criterion is deemed to be met and the internal combustion engine is switched to the third operating mode or operated in the third operating mode. In addition, it can be provided that the internal combustion engine is operated in the second operating mode as long as the third operating criterion is met.

[0041] In particular, it is provided that the values ​​of the predetermined second intake pressure value range are all greater than the maximum value of the predetermined first intake pressure value range, the values ​​of the predetermined second speed value range are all greater than the maximum value of the predetermined first speed value range, the values ​​of the predetermined second load value range are all greater than the maximum value of the predetermined first load value range, the values ​​of the predetermined second transmission level value range are all greater than the maximum value of the predetermined first transmission level value range, the values ​​of the predetermined second speed value range are all greater than the maximum value of the predetermined first speed value range, the values ​​of the predetermined second time value range are all greater than the maximum value of the predetermined first time value range, and / or the values ​​of the predetermined second exhaust gas temperature value range are all greater than the maximum value of the predetermined first exhaust gas temperature value range.

[0042] In the third operating mode, the internal combustion engine operates according to the Miller cycle with a second Miller intensity, wherein the first Miller intensity of the second operating mode is lower than the second Miller intensity of the third operating mode. In the third operating mode, the intake compressor must provide a higher intake pressure than in the second operating mode, and is therefore more heavily loaded than in the second operating mode. However, this is necessary to sufficiently reduce the exhaust gas temperature in the third operating mode to maintain or not exceed the maximum permissible exhaust gas temperature while still ensuring proper functioning of the corresponding components. This means that the maximum permissible exhaust gas temperature must be maintained during engine operation for component protection reasons to prevent damage to the corresponding components.

[0043] In particular, the individual subcriteria are mutually exclusive. In other words, either the corresponding first subcriteria, the corresponding second subcriteria, or the corresponding third subcriteria must exist, since the specified value ranges do not overlap.

[0044] The method specifically provides that the operating modes do not overlap. In other words, the first operating mode is active when neither the second nor the third operating mode is active. The second operating mode is active when neither the first nor the third operating mode is active. The third operating mode is active when neither the first nor the second operating mode is active. Furthermore, the method specifically provides that, when the third operating mode is active, a switchover from the third operating mode to the second operating mode occurs whenever possible. In other words, the third operating mode is intended only to reduce the exhaust gas temperature until the exhaust gas temperature again falls below a limit exhaust gas temperature. In other words, a switchover from the third operating mode to the second operating mode occurs when the exhaust gas temperature again falls below the limit exhaust gas temperature or falls below the limit exhaust gas temperature. In particular, a switchback limit temperature is specified for switching from the third operating mode to the second operating mode, which is lower than the limit exhaust gas temperature, and is used instead of the limit exhaust gas temperature when switching from the third operating mode to the second operating mode. Thus, bouncing back and forth between the second and third operating modes is prohibited. The internal combustion engine is switched to the first operating mode according to the method only if the prerequisites for operating the internal combustion engine in the second operating mode do not yet exist or no longer exist. For example, when the intake pressure drops below a limit intake pressure and / or the crankshaft speed and / or load of the internal combustion engine hinder the adoption of the Miller cycle, the internal combustion engine is switched to the first operating mode according to the method.

[0045] In particular, at least one intermediate operating mode for operating the internal combustion engine is conceivable. For example, the closing of the intake valve can be carried out later in a first intermediate operating mode than in a second operating mode, but earlier than in the first operating mode. In addition, a second intermediate operating mode is conceivable, in which the closing of the intake valve is carried out later than in a third operating mode, but earlier than in the second operating mode. Two or more different first or second intermediate operating modes (each with a different Miller intensity) can be provided between the first operating mode and the second operating mode and / or between the second operating mode and the third operating mode. This allows for a particularly finely graded setting of the Miller intensity. The method can be applied to one or more intermediate operating modes. When a first operating criterion (or other / further first operating criterion, possibly including other and / or other first sub-criterion) is present, it is possible to switch from the first operating mode to one of the first intermediate operating modes. When a second operating criterion (or another / further second operating criterion, possibly including another and / or another second subcriterion) is present, it is possible to switch from the first intermediate operating mode to another intermediate operating level (of the first or second intermediate operating level) or to a third operating mode.

[0046] The method allows the internal combustion engine to operate particularly efficiently and with low emissions, with the exhaust gas temperature remaining below a limit exhaust gas temperature at a constant stoichiometric fuel ratio or fuel-air ratio λ=1. In this case, enrichment of the fuel-air mixture (λ<1) for exhaust gas cooling is particularly unnecessary, as this results in increased pollutant emissions from the internal combustion engine and a lower conversion rate for the catalytic converter connected to the internal combustion engine on the exhaust side. Furthermore, it is ensured that the thermal load on components interacting with the exhaust gas due to the third operating state does not exceed the permitted limit load. Current legal requirements for low limit values ​​for pollutant emissions across the entire operating range of the internal combustion engine are met. Furthermore, a motor vehicle having this internal combustion engine as its engine enables higher driving performance. By means of a variably controllable intake opening, higher power can be achieved in the first and second operating modes compared to the third operating mode.

[0047] According to another possible embodiment, the first crankshaft angle KW1 or the first crankshaft angle range [KW1] and the second crankshaft angle KW2 or the second crankshaft angle range [KW2] are spaced apart from one another at a first angular spacing, which is in particular greater than 10° or greater than 30°. Alternatively or in addition, the second crankshaft angle KW2 and the third crankshaft angle KW3 or the second crankshaft angle range [KW2] and the third crankshaft angle range [KW3] are spaced apart from one another at a second angular spacing, which is in particular greater than 5°. In particular, the first angular spacing with which the crankshaft angles KW1, KW2 or the crankshaft angle ranges [KW1], [KW2] are spaced apart from one another is greater than the second angular spacing with which the crankshaft angles KW2, KW3 or the crankshaft angle ranges [KW2], [KW3] are spaced apart from one another.

[0048] In one possible further development, provision is made for the switch between the first and second operating modes and / or the switch between the second and third operating modes to be performed steplessly. This ensures a particularly smooth switchover of the operating modes of the internal combustion engine. Alternatively or additionally, the switch between the first and second operating modes and / or the switch between the second and third operating modes can be performed in a plurality of discrete steps.

[0049] In another possible embodiment of the method, determining the exhaust gas temperature includes determining a first exhaust gas temperature at a first exhaust duct location. The first exhaust duct location is assigned to a turbine of an exhaust gas turbocharger of an internal combustion engine and is particularly located in or at an inflow region of the turbine through which exhaust gas from the internal combustion engine flows during operation to drive a turbine wheel of the turbine. Alternatively or additionally, determining the exhaust gas temperature includes determining a second exhaust gas temperature at a second exhaust duct location assigned to an exhaust gas aftertreatment device of the internal combustion engine, such as a catalytic converter, on the inflow side. The second exhaust duct location is particularly located in or at an inflow duct section of the exhaust gas aftertreatment device through which exhaust gas from the internal combustion engine flows during operation. Alternatively or additionally to determining the first and / or second exhaust gas temperature at the first or second exhaust duct location, it is further provided that determining the exhaust gas temperature includes determining a third exhaust gas temperature at a third exhaust duct location. The third exhaust duct section is assigned to an aftertreatment chamber of the exhaust gas aftertreatment device, through which the exhaust gas flows, such as a converter chamber of a catalytic converter, and is, for example, arranged in the aftertreatment chamber. The corresponding exhaust gas temperature can be measured, for example, using a correspondingly designed temperature sensor. Alternatively or additionally, one or more of the exhaust gas temperatures can be modeled, for example, using a control device.

[0050] A first exhaust gas temperature-related subcriterion is deemed to be satisfied if: the value of the first exhaust gas temperature lies within a first exhaust gas temperature value range, and / or the value of the second exhaust gas temperature lies within a first exhaust gas temperature value range, and / or the value of the third exhaust gas temperature lies within a first exhaust gas temperature value range. For the respective exhaust duct section, a specific first exhaust gas temperature value range is in particular prescribed. This means, for example, that the first exhaust gas temperature value range assigned to the first exhaust gas duct section may include different exhaust gas temperature values ​​than the first exhaust gas temperature value range assigned to the second exhaust gas duct section. A second exhaust gas temperature-related subcriterion is deemed to be satisfied if: the value of the first exhaust gas temperature lies within a second exhaust gas temperature value range, and / or the value of the second exhaust gas temperature lies within a second exhaust gas temperature value range, and / or the value of the third exhaust gas temperature lies within a second exhaust gas temperature value range. For the respective exhaust duct section, a specific first exhaust gas temperature value range and / or a specific second exhaust gas temperature value range are in particular prescribed. This means, for example, that the first / second exhaust gas temperature value range assigned to the first exhaust gas duct portion can contain different exhaust gas temperature values ​​than the first / second exhaust gas temperature value range assigned to the second exhaust gas duct portion. This applies analogously to other exhaust gas duct portions. The third sub-criterion relating to the exhaust gas temperature is deemed to be satisfied if: the value of the first exhaust gas temperature comes from the third exhaust gas temperature value range, and / or the value of the second exhaust gas temperature comes from the third exhaust gas temperature value range, and / or the value of the third exhaust gas temperature comes from the third exhaust gas temperature value range. For the respective exhaust gas duct portion, in particular, a specific third exhaust gas temperature value range is prescribed. This means, for example, that the third exhaust gas temperature value range assigned to the first exhaust gas duct portion can contain different exhaust gas temperature values ​​than the third exhaust gas temperature value range assigned to the second exhaust gas duct portion. This applies analogously to other exhaust gas duct portions.

[0051] Thus, the exhaust gas temperatures at different locations of the internal combustion engine are taken into account particularly accurately. Furthermore, a plausibility check can be provided. For example, if an unrealistically high exhaust gas temperature exceeding a first limit exhaust gas temperature is measured at a first exhaust duct location, the switch from the second operating mode to the third operating mode can be disregarded if a plausible exhaust gas temperature below a second limit exhaust gas temperature is measured at a second exhaust duct location. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Further features of the invention can be gathered from the claims, the drawings and the description of the drawings. The features and feature combinations mentioned above in the description and the features and feature combinations shown individually in the following description of the drawings and / or in the drawings can be used not only in the respectively specified combination but also in other combinations or individually without departing from the scope of the invention.

[0053] The attached pictures are as follows:

[0054] Figure 1 : acceleration of combustion of an internal combustion engine having a crankshaft for approximately 20 seconds on a common time axis, the internal combustion engine being controlled by means of a method for controlling an internal combustion engine;

[0055] a) a crankshaft speed curve of the internal combustion engine and a gear ratio curve of a manual transmission coupled to the crankshaft;

[0056] b) Effective state curves of the three operating modes of the internal combustion engine;

[0057] c) a curve of the intake valve opening angle, which indicates at which angular position of the crankshaft relative to top dead center of the crankshaft the intake valve is open with maximum stroke;

[0058] d) inlet pressure curve; and

[0059] e) Inlet air temperature curve;

[0060] Figure 2 : In order to describe the various operating modes and the associated intake valve opening angles, a schematic depiction of the crankshaft is provided.

[0061] a) at top dead center;

[0062] b) at a first angular position that is a first crankshaft angle away from the first dead center;

[0063] c) at a second angular position that is a second crankshaft angle away from the first dead center;

[0064] d) At a third angular position that is a third crankshaft angle away from the first dead center. DETAILED DESCRIPTION

[0065] Below, a general description of a method for controlling an internal combustion engine, a control device configured to implement the method, an internal combustion engine unit having an internal combustion engine and a control device, and a motor vehicle having an internal combustion engine unit is explained. In the figures, identical and functionally identical elements are provided with the same reference numerals.

[0066] A motor vehicle includes an internal combustion engine unit, such that the internal combustion engine of the internal combustion engine unit forms the engine of the motor vehicle. In addition to the internal combustion engine, the internal combustion engine unit includes a control device having means for implementing a method for controlling the internal combustion engine. The control device provides control signals to the internal combustion engine, in particular to an intake valve train of the internal combustion engine. The internal combustion engine is configured to receive the control signals provided by the control device as input control signals. Accordingly, the internal combustion engine and the control device are coupled to each other or can be coupled to each other for transmitting the control signals.

[0067] The internal combustion engine is currently designed as a four-stroke reciprocating piston internal combustion engine and has, in addition to an intake valve mechanism, a crankshaft 1 as well as a combustion chamber and intake valves assigned to the combustion chamber. In addition, the internal combustion engine has an intake compressor, for example an exhaust gas turbocharger, for pre-compressing the intake air to be supplied to the combustion chamber. During combustion operation of the internal combustion engine, in order to load the combustion chamber with intake air or a fuel-air mixture during the intake stroke, the exhaust side of the combustion chamber is sealed by means of an exhaust valve, and conversely, the intake side of the combustion chamber is released by means of an intake valve that is at least partially set to an open position in order to allow fluid to flow into the combustion chamber. In this case, in order to move the reciprocating piston that is supported in a translationally movable manner in the combustion chamber, the crankshaft 1 is moved from its top dead center OT (at Figure 2 0° in the figure) and in the prescribed working direction of rotation 2 (see Figure 2 a) Towards the bottom dead center UT of the crankshaft 1 (at Figure 2 The intake stroke is followed by a compression stroke, or compaction stroke, wherein the crankshaft 1 rotates in the working direction of rotation from bottom dead center UT (180°) toward top dead center OT (360°). Following the compression stroke, the four-stroke cycle begins again within a complete revolution of the crankshaft 1 , followed by an expansion stroke (from 360° to 540°) and an exhaust stroke (from 540° to 720° = 0°).

[0068] Figure 1 a) shows the curve of the crankshaft speed n and the curve of the transmission stage N of the manual transmission coupled to the internal combustion engine over time t, wherein the combustion of the internal combustion engine is accelerated. In this case, the internal combustion engine is controlled according to the method described.

[0069] exist Figure 1 b) describes the time periods during the acceleration process during which the internal combustion engine operates in the first operating mode B1, the second operating mode B2, and the third operating mode B3. It can be seen that operating modes B1, B2, and B3 do not overlap. That is, the first operating mode B1 is active only when both the second operating mode B2 and the third operating mode B3 are inactive. The second operating mode B2 is active only when both the first operating mode B1 and the third operating mode B3 are inactive. Therefore, the third operating mode B3 is active only when both the first operating mode B1 and the second operating mode B2 are inactive.

[0070] The operating modes B1, B2, B3 differ from one another in particular by the respectively assigned intake valve opening angle ES, the curve of which over time t is shown in FIG. Figure 1 According to different operating modes B1, B2, and B3, the intake valve is maximally opened at different intake valve opening angles ES1, ES2, and ES3, that is, it is fully set to the open position.

[0071] The intake valve opening angle ES is the crankshaft angle measured in the working rotational direction 2 of the crankshaft 1 and starting from the top dead center OT of the crankshaft 1. This shows that, depending on the operating modes B1, B2, B3, the intake valve is completely set to the closed position at different crankshaft angles KW1, KW2, KW3 for the respective intake stroke.

[0072] exist Figure 2 Intake valve opening angles ES1, ES2, and ES3 are visualized in sections 2b), 2c), and 2d), at which the intake valve is opened to its maximum stroke. It can be seen that in the first operating mode B1, the intake valve is maximally open at the first intake valve opening angle ES1. Therefore, the intake valve is fully in the closed position at a first crankshaft angle KW1 of approximately 180°, i.e., approximately at bottom dead center UT. In other words, in the first operating mode B1, the closing movement of the intake valve is fully completed at bottom dead center UT, or when the crankshaft assumes the first crankshaft angle KW1. The flow of intake air into the combustion chamber is completely shut off at the first crankshaft angle KW1. It is known that the closing of the intake valve can be fully completed shortly before or shortly after bottom dead center (due to tolerances such as valve clearance and / or to exploit favorable thermodynamic or fluid dynamic effects), but in any case in the vicinity of bottom dead center UT, for example, within a range of ±10° around bottom dead center UT. Therefore, the first intake valve opening angle ES1 comes in particular from the first intake valve opening angle range [ES1], and thus the first crankshaft angle KW1 comes in particular from the first crankshaft angle range [KW1].

[0073] In the second operating mode B2, the intake valve is fully open at the second intake valve opening angle ES2. Therefore, the closing of the intake valve ends earlier than in the first operating mode B1, namely at the second crankshaft angle KW2 and in any case before the crankshaft 1 reaches the first crankshaft angle KW1. Consequently, the inflow of intake air into the combustion chamber is completely blocked even during the intake stroke. The internal combustion engine thus operates in the Miller cycle with the first Miller intensity.

[0074] The second intake valve opening angle ES2 can come from the second intake valve opening angle range [ES2], which means that the second crankshaft angle KW2 can come from the second crankshaft angle range [KW2]. The first crankshaft angle KW1 or the first crankshaft angle angular range [KW1] and the second crankshaft angle KW2 or the second crankshaft angle angular range [KW2] are currently spaced apart from each other at a first angular interval. In other words, the first intake valve opening angle ES1 or the first intake valve opening angle angular range [ES1] and the second intake valve opening angle ES2 or the second intake valve opening angle angular range [ES2] can be spaced apart from each other at a first angular interval. The first angular interval is greater than 10°, in particular greater than 30°. Closing of the intake valve in the first Miller cycle or in the second operating mode B2 ends, for example, 40° earlier than in the first operating mode B1.

[0075] In the third operating mode B3, the intake valve is fully open at the third intake valve opening angle ES3. Therefore, the closing of the intake valve ends even earlier than in the second operating mode B2, namely at the third crankshaft angle KW3. The internal combustion engine thus operates in a Miller cycle of the second Miller intensity. The third crankshaft angle KW3 can come from a third crankshaft angle range [KW3], and the third intake valve opening angle ES3 can come from a third intake valve opening angle range [ES3]. The second crankshaft angle KW2 or the second crankshaft angle range [KW2] and the third crankshaft angle KW3 or the third crankshaft angle range [KW3] are currently spaced apart from each other at a second angular spacing, which is greater than 5°. In this regard, the intake valve opening angle ranges [ES2], [ES3] can be spaced apart from each other at a second angular spacing. In the Miller cycle of the second Miller intensity, or in the third operating mode B3, the closing of the intake valve is completed earlier than in the first operating mode B1 and earlier still than in the second operating mode B2. Therefore, the effect of the Miller cycle is stronger in the Miller cycle of the second intensity, or in the third operating mode B3, than in the second operating mode B2; the second operating mode B2 has a weak first Miller intensity, and the third operating mode B3 has a strong second Miller intensity.

[0076] In the method, it is determined what intake pressure the intake air has. L The curve during the combustion acceleration period considered here is Figure 1d) is described with respect to time t. In particular, the crankshaft speed and load at which the internal combustion engine is operating are determined. Furthermore, the current transmission stage of the manual transmission coupled to the internal combustion engine and the current driving speed of the motor vehicle are determined. Furthermore, the current operating duration of the internal combustion engine and the exhaust gas temperature at the exhaust duct are determined. One, some, or all of the values ​​determined here—here, the intake pressure value, crankshaft speed value (short for short), load value, transmission stage value, driving speed value (short for short), operating duration value, and exhaust gas temperature value—can be modeled, for example, using a control device for the internal combustion engine. Alternatively or additionally, one, some, or all of the values ​​described can be measured, for example, using appropriately configured and arranged sensors. Thus, in the present case, the exhaust gas temperature value is determined, for example, by modeling the exhaust gas temperature present at the exhaust duct or the corresponding exhaust gas temperature value using the control device.

[0077] If or as long as the first operating criterion is satisfied, the internal combustion engine is operated in the first operating mode B1. In the present example, the first operating criterion is considered satisfied if one of the first sub-criterions is satisfied or if two or more of the first sub-criterions are satisfied. The first sub-criterions are currently:

[0078] - The intake air currently has an intake pressure p L The intake pressure value is from a predetermined first intake pressure value range, and the first intake pressure value range includes from zero to a predetermined first limit intake pressure value Gp L (inclusive) value.

[0079] The value of the current crankshaft speed n comes from a predetermined first speed value range, which has values ​​from zero, in particular from an idling speed value, up to a predetermined first speed limit value inclusive.

[0080] The current load value is from a predetermined first load value range, which includes values ​​from zero up to a predetermined first limit load value (inclusive).

[0081] The value of the current transmission step N of the manual transmission comes from a predetermined first transmission step value range, which includes values ​​from zero up to a predetermined first limiting transmission step value (inclusive).

[0082] The value of the current driving speed comes from a predetermined first speed value range, which includes values ​​from zero up to a predetermined first limit speed value (inclusive).

[0083] The value of the current operating duration, during which the internal combustion engine was ultimately operated without interruption in the first operating mode, comes from a predetermined first time value range which includes values ​​from zero up to a predetermined first limiting operating duration value inclusive.

[0084] The value of the exhaust gas temperature ascertained at the exhaust duct region of the internal combustion engine comes from a predetermined first exhaust gas temperature value range, which comprises values ​​from zero up to a predetermined first limit exhaust gas temperature value inclusive.

[0085] In the method, the internal combustion engine switches from the first operating mode B1 to the second operating mode B2 when another second operating criterion is met. In the present example, the second operating criterion is considered met if one of the second sub-criterions is met or if two or more of the second sub-criterions are met. The second sub-criterions are currently:

[0086] - The intake air currently has an intake pressure p L The intake pressure value is from a predetermined second intake pressure value range, and the second intake pressure value range includes a predetermined first limit intake pressure value Gp L (excluding) up to a predetermined second limit intake pressure value (inclusive).

[0087] The value of the current crankshaft speed comes from a predetermined second speed value range, which includes values ​​from a predetermined first speed limit value (exclusive) to a predetermined second speed limit value (inclusive).

[0088] The current load value is from a predetermined second load value range, which includes values ​​from a predetermined first limit load value (exclusive) to a predetermined second limit load value (inclusive).

[0089] The current transmission step value of the manual transmission comes from a predetermined second transmission step value range, which includes values ​​from a predetermined first limiting transmission step value (exclusive) up to a predetermined second limiting transmission step value (inclusive).

[0090] The current driving speed value is from a predetermined second speed value range, which includes values ​​from a predetermined first limit speed value (excluding) to a predetermined second limit speed value (inclusive).

[0091] The value of the current operating duration, during which the internal combustion engine was ultimately operated in the first operating mode without interruption, comes from a predetermined second time value range, which includes values ​​from a predetermined first limit operating duration value (exclusive) to a predetermined second limit operating time value (inclusive).

[0092] The exhaust gas temperature value ascertained at the exhaust duct region of the internal combustion engine is from a predetermined second exhaust gas temperature value range, which includes values ​​from a predetermined first limit exhaust gas temperature value (exclusive) to a predetermined second limit exhaust gas temperature value (inclusive).

[0093] As long as one or more of the second sub-criteria are not satisfied, for example, as long as the intake pressure p L Less than the limit intake pressure Gp L , the internal combustion engine is running in the first operating mode B1. It is stipulated that the internal combustion engine is switched to the second operating mode B2 as early as possible and the internal combustion engine is running in the second operating mode B2 as long as possible. Figure 1 d) As can be seen, in the second operating mode B2, the intake air compressor provides a higher intake air pressure than in the first operating mode B1. The switch from the first operating mode B1 to the second operating mode B2, or vice versa, is currently performed steplessly. Alternatively, it is conceivable to perform the switch from the first operating mode B1 to the second operating mode B2, or vice versa, in a plurality of discrete steps.

[0094] According to the method, the internal combustion engine switches from the second operating mode B2 to the third operating mode B3 only when necessary for component protection reasons. To this end, a third operating criterion is defined, and when the third operating criterion is met, the internal combustion engine switches from the second operating mode B2 to the third operating mode B3 or operates in the third operating mode B3. In the present example, the third operating criterion is considered to be met when one of the third sub-criteria is met or when two or more of the third sub-criteria are met. The third sub-criteria are currently:

[0095] - The intake air currently has an intake pressure p L The intake pressure value is from a predetermined third intake pressure value range, and the third intake pressure value range includes a predetermined second limit intake pressure value Gp L (excluding) and higher values.

[0096] The value of the current crankshaft speed comes from a predetermined third speed value range, which includes values ​​starting from (excluding) a predetermined second speed limit value and higher.

[0097] The current load value is from a predetermined third load value range, which includes values ​​starting from (excluding) a predetermined second limit load value and higher.

[0098] The current transmission step value of the manual transmission comes from a predetermined third transmission step value range, which includes values ​​starting from (excluding) a predetermined second limiting transmission step value and higher.

[0099] The value of the current driving speed is from a predetermined third speed value range, which includes values ​​starting from (excluding) a predetermined second limit speed value and higher.

[0100] The value of the current operating duration, during which the internal combustion engine is ultimately operated without interruption in the second operating mode, comes from a predetermined third time value range, which includes values ​​starting from (excluding) a predetermined second limiting operating duration value and above.

[0101] The value of the exhaust gas temperature ascertained at the exhaust duct region comes from a predetermined third exhaust gas temperature value range, which includes values ​​starting from (excluding) a predetermined second limit exhaust gas temperature value and higher.

[0102] If, for example, the detected exhaust gas temperature exceeds a predetermined limit temperature, the internal combustion engine switches to the third operating mode B3. In particular, as soon as the temperature again permits this, that is, as soon as the detected exhaust gas temperature at the corresponding exhaust duct region again drops below the predetermined limit exhaust gas temperature, the internal combustion engine switches back to the second operating mode B2. Currently, a switchback limit temperature, which is less than the limit exhaust gas temperature, is specified for switching from the third operating mode B3 to the second operating mode B2. This switchback limit temperature is used instead of the limit exhaust gas temperature when switching from the third operating mode B3 to the second operating mode B2. Currently, the switch from the second operating mode B2 to the third operating mode B3, or vice versa, is performed steplessly. Alternatively, it is conceivable to switch from the second operating mode B2 to the third operating mode B3, or vice versa, in a plurality of discrete steps.

[0103] Furthermore, the internal combustion engine can be operated in a first intermediate operating mode, characterized by an intake valve opening angle ES that is less than the first intake valve opening angle ES1 but greater than the second intake valve opening angle ES2. Consequently, in the first intermediate operating mode, closing of the intake valve ends at a crankshaft angle that is less than the first crankshaft angle KW1 and greater than the second crankshaft angle KW2. Furthermore, the internal combustion engine can be operated in a second intermediate operating mode, characterized in particular by an intake valve opening angle ES that is less than the second intake valve opening angle ES2 and greater than the third intake valve opening angle ES3. Consequently, in the respective second intermediate operating mode, closing of the intake valve ends at a crankshaft angle that is less than the second crankshaft angle KW2 but greater than the third crankshaft angle KW3. Two or more first intermediate operating modes or two or more second intermediate operating modes are possible. By switching to one or more of the intermediate operating modes (e.g. first operating mode B1 - first intermediate operating mode - one or more further first intermediate operating modes - second operating mode B2 - second intermediate operating mode - one or more further second intermediate operating modes - third operating mode B3), the Mueller intensity can be set particularly precisely as required.

[0104] Currently, a first exhaust gas temperature is determined at a first exhaust duct portion, a second exhaust gas temperature is determined at a second exhaust duct portion, and a third exhaust gas temperature is determined at a third exhaust duct portion. The first exhaust duct portion is assigned to the turbine of the exhaust gas turbocharger, for example, is arranged in or on the inlet region of the turbine, and is provided for component protection of the turbine. The second exhaust duct portion is assigned to the inlet side of an exhaust gas aftertreatment device (for example, a catalytic converter) of an internal combustion engine, and is particularly arranged in or on the inlet channel section of the exhaust gas aftertreatment device. For component protection of the exhaust gas aftertreatment device, a second limit exhaust gas temperature is specified. The third exhaust duct portion is assigned to an aftertreatment chamber of the exhaust gas aftertreatment device, through which the exhaust gas flows, for example, a conversion chamber of a catalytic converter, and is, for example, arranged in the aftertreatment chamber. For component protection of the aftertreatment chamber, a third limit exhaust gas temperature is specified.

[0105] A specific first, specific second, and specific third exhaust gas temperature value range is currently assigned to the corresponding exhaust gas duct location. A first exhaust gas temperature-related sub-criterion is currently considered satisfied if the value of the first exhaust gas temperature and / or the value of the second exhaust gas temperature and / or the value of the third exhaust gas temperature are from the respectively assigned first exhaust gas temperature value range within the respective specific first exhaust gas temperature value range. A second exhaust gas temperature-related sub-criterion is currently considered satisfied if the value of the first exhaust gas temperature and / or the value of the specific second exhaust gas temperature and / or the value of the third exhaust gas temperature are from the respectively assigned second exhaust gas temperature value range within the respective second exhaust gas temperature value range. A third exhaust gas temperature-related sub-criterion is currently considered satisfied if the value of the first exhaust gas temperature and / or the value of the second exhaust gas temperature and / or the value of the third exhaust gas temperature are from the respectively assigned third exhaust gas temperature value range within the respective specific third exhaust gas temperature value range.

[0106] exist Figure 1 e) describes the intake air temperature T L Curve over time t. It can be seen that in the second operating mode B2 there is a higher intake air temperature T than in the first operating mode B1. L If necessary, measures for cooling the intake air can be provided, such as a particularly effective intake air cooler or the like.

[0107] From common observation Figure 1As can be seen in d) and 1e), components of the internal combustion engine that come into contact with or interact with the intake and / or exhaust gases, as well as peripheral components, are subject to higher loads in the second operating mode B2 than in the first operating mode B1. However, this is desirable in order to switch to the second operating mode as early as possible during combustion operation of the internal combustion engine and to operate the internal combustion engine in the second operating mode for as long as possible. This is because the second operating mode, i.e., the Miller cycle of first or weak Miller intensity, offers advantages in terms of exhaust gas temperature compared to the first operating mode B1. Consequently, components or peripheral components that interact with the exhaust gas—such as the turbine of the intake compressor, the exhaust gas aftertreatment device, in particular the aftertreatment chamber of the exhaust gas aftertreatment device, etc.—are exposed to advantageously cool exhaust gas. This effectively prevents undesirably high temperatures, in particular, the reaching of one or more predetermined limit temperatures. Using the described method, the internal combustion engine is operated with a combustion-stoichiometric fuel-to-air ratio λ=1, intentionally avoiding enrichment of the fuel-air mixture (λ<1) for exhaust gas cooling. If one or more exhaust gas temperatures, which are higher than one or more limit exhaust gas temperatures, occur during operation of the internal combustion engine, enrichment of the fuel-air mixture for cooling the exhaust gases (λ<1) is still omitted, and the engine is instead switched to the third operating mode, namely to the Miller cycle with a second or high Miller intensity. Thus, even at high loads, in particular at a fixed full load, the internal combustion engine is operated with a fuel-air ratio λ=1, wherein the exhaust gas temperature or temperatures do not exceed a predetermined limit exhaust gas temperature or temperatures. This satisfies current legal requirements, which in particular stipulate particularly low limit values ​​for pollutant emissions across the entire operating range of the internal combustion engine.

[0108] A method for controlling an internal combustion engine, a control device designed to implement the method, an internal combustion engine, and a motor vehicle having an internal combustion engine provide corresponding possibilities for operating an internal combustion engine particularly efficiently and with low emissions.

[0109] Reference Signs List

[0110] 1 crankshaft

[0111] 2 Working rotation direction

[0112] KW1 first crankshaft angle

[0113] [KW1] First crankshaft angle range

[0114] KW2 second crankshaft angle

[0115] [KW2] Second crankshaft angle range

[0116] KW3 third crankshaft angle

[0117] [KW3] Third crankshaft angle range

[0118] OT crankshaft top dead center

[0119] UT bottom dead center of crankshaft

[0120] B1 first operating mode

[0121] B2 second operating mode or first Miller cycle

[0122] B3 third operating mode or second Miller cycle

[0123] ES1 first intake valve opening angle

[0124] ES2 second intake valve opening angle

[0125] ES3 third intake valve opening angle

[0126] p L Inlet pressure

[0127] Gp L Ultimate intake pressure

[0128] T L Intake air temperature

Claims

1. A method for controlling an internal combustion engine having a crankshaft (1), an intake valve and an intake compressor for precompressing intake air, wherein: The closing of the intake valve during the intake stroke is measured starting from the top dead center (OT, 0°) of the crankshaft (1) and in the working direction of rotation (2) of the crankshaft (1), - in the first operating mode (B1), the rotation is completely completed at the bottom dead center (UT, 180°) of the crankshaft (1) at the first crankshaft angle (KW1); or - in the second operating mode (B2), the rotation is completed completely before the bottom dead center (UT, 180°) at a second crankshaft angle (KW2), which is smaller than the first crankshaft angle (KW1); or - in the third operating mode (B3), the operation is completed completely before the bottom dead center (UT, 180°) at a third crankshaft angle (KW3), which is smaller than the second crankshaft angle (KW2); Wherein, the internal combustion engine: - operating in the first operating mode (B1) when the first operating criterion is met, - switching from the first operating mode (B1) to the second operating mode (B2) when a second operating criterion is met, - Switching from the second operating mode (B2) to the third operating mode (B3) when a third operating criterion is met.

2. The method according to claim 1, characterized in that The first operating criterion is satisfied when one or more of the following first sub-criteria are satisfied: - Current intake air pressure (p L ) is from a predetermined first intake pressure value range, which includes a range from zero to a predetermined first limit intake pressure value (Gp L ) (inclusive); the value of the current crankshaft speed comes from a predetermined first speed value range, which has values ​​from zero, in particular from an idling speed value, up to a predetermined first speed limit value inclusive; - the value of the current load of the internal combustion engine comes from a predetermined first load value range, the first load value range comprising values ​​from zero up to a predetermined first limit load value (inclusive); The current transmission step value of the manual transmission coupled to the internal combustion engine comes from a predetermined first transmission step value range, which includes values ​​from zero up to a predetermined first limiting transmission step value, inclusive; - the value of the current driving speed of the motor vehicle having an internal combustion engine as the engine comes from a predetermined first speed value range, which includes values ​​from zero up to a predetermined first limit speed value, inclusive; - the value of the current operating time during which the internal combustion engine has finally been operated without interruption in the first operating mode comes from a predetermined first time value range, which includes values ​​from zero up to a predetermined first limiting operating time value, inclusive; The value of the exhaust gas temperature ascertained at the exhaust duct region of the internal combustion engine comes from a predetermined first exhaust gas temperature value range, which comprises values ​​from zero up to a predetermined first limit exhaust gas temperature value inclusive.

3. The method according to claim 1 or 2, characterized in that The second operating criterion is satisfied when one or more of the following second sub-criteria are satisfied: - Current intake air pressure (p L ) is from a predetermined second intake pressure value range, the second intake pressure value range including a predetermined first limit intake pressure value (Gp L ) (excluding) up to a predetermined second limit intake pressure value (inclusive); The current crankshaft speed value is from a predetermined second speed value range, the second speed value range including values ​​from a predetermined first speed limit value (exclusive) to a predetermined second speed limit value (inclusive); - the value of the current load of the internal combustion engine comes from a predetermined second load value range, which second load value range includes values ​​from a predetermined first limit load value (exclusive) to a predetermined second limit load value (inclusive); the current transmission step value of the manual transmission coupled to the internal combustion engine comes from a predetermined second transmission step value range, which includes values ​​from a predetermined first limiting transmission step value (exclusive) up to a predetermined second limiting transmission step value (inclusive); - the value of the current driving speed of the motor vehicle having an internal combustion engine as the engine comes from a predetermined second speed value range, which includes values ​​from a predetermined first limit speed value (exclusive) to a predetermined second limit speed value (inclusive); - the value of the current operating time during which the internal combustion engine has been operated in the first operating mode without interruption comes from a predetermined second time value range, which includes values ​​from a predetermined first limit operating time value (exclusive) to a predetermined second limit operating time value (inclusive); The exhaust gas temperature value ascertained at the exhaust duct region of the internal combustion engine is from a predetermined second exhaust gas temperature value range, which includes values ​​from a predetermined first limit exhaust gas temperature value (exclusive) to a predetermined second limit exhaust gas temperature value (inclusive).

4. The method according to any one of the preceding claims, characterized in that The third operating criterion is satisfied when one or more of the following third sub-criteria are satisfied: - Current intake air pressure (p L ) is from a predetermined third intake pressure value range, the third intake pressure value range including a predetermined second limit intake pressure value (Gp L ) (excluding) and higher values; The value of the current crankshaft speed comes from a predetermined third speed value range, which includes values ​​starting from (excluding) a predetermined second speed limit value and higher. The value of the current load of the internal combustion engine comes from a predetermined third load value range, which includes values ​​starting from (excluding) a predetermined second limit load value and higher. The current transmission step value of the manual transmission coupled to the internal combustion engine comes from a predetermined third transmission step value range, which includes values ​​starting from (excluding) a predetermined second limiting transmission step value and higher; The value of the current driving speed of the motor vehicle having an internal combustion engine as the engine comes from a predetermined third speed value range, which includes values ​​starting from (excluding) a predetermined second limit speed value and higher; - the value of the current operating duration, during which the internal combustion engine has finally been operated without interruption in the second operating mode, comes from a predetermined third time value range, which includes values ​​starting from (excluding) a predetermined second limiting operating duration value and above; The value of the exhaust gas temperature ascertained at the exhaust duct region of the internal combustion engine comes from a predetermined third exhaust gas temperature value range, which includes values ​​starting from (excluding) a predetermined second limit exhaust gas temperature value and higher.

5. The method according to any one of the preceding claims, characterized in that The first crankshaft angle (KW1) and the second crankshaft angle (KW2) are spaced apart from one another by a first angular distance, which is in particular greater than 10° or greater than 30°; and / or The second crankshaft angle ( KW2 ) and the third crankshaft angle ( KW3 ) are spaced apart from one another by a second angular spacing, which is in particular greater than 5°.

6. The method according to any one of claims 2 to 5, characterized in that The ascertaining of the exhaust gas temperature includes ascertaining a first exhaust gas temperature at a first exhaust duct portion that is associated with a turbine of an exhaust gas turbocharger of the internal combustion engine.

7. The method according to any one of claims 2 to 6, characterized in that The ascertaining of the exhaust gas temperature includes ascertaining a second exhaust gas temperature at a second exhaust duct portion which is associated with an inlet side of an exhaust gas aftertreatment device of the internal combustion engine.

8. The method according to any one of claims 2 to 7, characterized in that Measuring the exhaust gas temperature includes measuring a third exhaust gas temperature at a third exhaust gas duct portion that is associated with an aftertreatment chamber of the exhaust gas aftertreatment device through which the exhaust gas flows.

9. A control device for an internal combustion engine, the control device being configured to carry out the method according to any of the preceding claims. 10 . An internal combustion engine unit comprising an internal combustion engine and a control device according to claim 9 , which is coupled or can be coupled to the internal combustion engine for controlling the internal combustion engine.

11. A motor vehicle comprising an internal combustion engine unit according to claim 10.

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