Method and control unit for setting a load point of an internal combustion engine in dynamic engine operation

Abstract

Method (200) for operating an internal combustion engine (103) of a vehicle (100) with an exhaust gas recirculation (EGR) system; wherein the EGR system has an EGR dead time for adjusting an amount of exhaust gas (122) in a working gas of the internal combustion engine (103), which depends on a space volume of the EGR system for receiving exhaust gas (122) between an EGR valve (102) and an inlet (131) of the internal combustion engine (103); wherein the method (200) comprises, in response to a change in a power demanded by the internal combustion engine (103) from an output power to a target power, - Actuating (201) the EGR valve (102) during the EGR dead time to modify the amount of recirculated exhaust gas (122) in preparation for the required target power output; and - Initiating (202) one or more load-controlling measures so that during the EGR dead time the internal combustion engine (103) delivers an intermediate power output that differs from the target power output; or Control (202) at least one electric machine (150) of the vehicle (100), so that during the EGR dead time the at least one electric machine (150) provides the target power and the internal combustion engine (103) is in overrun mode.

Description

[0001] The invention relates to a method and a corresponding control unit for setting or adjusting the load point of an internal combustion engine with exhaust gas recirculation (EGR) during dynamic operation of the internal combustion engine.

[0002] In a vehicle with an internal combustion engine, exhaust gas recirculation (EGR) is used to reduce fuel consumption, engine knocking, and / or exhaust gas temperature. Fuel consumption benefits in the partial load range result from reduced throttling, an increase in the isentropic exponent of the combustion gases, and improved gas properties. The increased heat capacity of the combustion gases leads to lower combustion temperatures, thus reducing the occurrence of auto-ignition (and therefore knocking). Furthermore, exhaust gas recirculation allows for the adjustment of fuel-efficient engine operating points.

[0003] External exhaust gas recirculation (EGR) can be implemented in various ways, particularly through high-pressure or low-pressure EGR. In the case of high-pressure EGR, the exhaust gas is typically extracted from the exhaust manifold of the combustion engine, or, in the case of turbocharged engines, before the turbocharger. It is then introduced either before or after the throttle valve and mixed with the intake air to form the working gas. The recirculated exhaust gas is usually cooled before being mixed with the intake air. An EGR control valve, which can be positioned before or after the EGR system's cooler, is used to regulate the amount of recirculated exhaust gas. In the case of low-pressure EGR, the exhaust gas is extracted after the turbocharger turbine, either before or after the catalytic converter, and fed back in before the turbocharger's compressor. As with high-pressure EGR, the exhaust gas is cooled before being introduced. The EGR rate (i.e., the amount of EGR) is controlled by a variable EGR valve.The reduction of the proportion of exhaust gases in the working gas) is carried out via an EGR control valve, which is positioned before or after the EGR cooler.

[0004] Exhaust gas recirculation (EGR) typically exhibits a relatively high inertia in the control of the recirculated exhaust gas mass. This inertia is caused by the volume of space between the EGR control valve and the intake valves of the combustion engine, and by the amount of exhaust gas contained within this space that the combustion engine must process before the EGR rate, as modified by the EGR control valve, can take effect in the combustion chamber or cylinder. The dead time of the EGR system increases with increasing volume. Particularly in the case of low-pressure EGR, the volume, and thus the EGR dead time or inertia, can be relatively large.

[0005] The inertia of exhaust gas recirculation (EGR) can cause problems during relatively rapid changes in operating point, especially during load reduction in an internal combustion engine. At relatively high loads, relatively high EGR rates are typically used, while at relatively low loads, relatively low EGR rates are typically used. However, due to the inertia of the EGR system, relatively high quantities of exhaust gases may still be present in the engine's air intake system immediately following a load reduction. This can lead to suboptimal engine operation and potentially to misfires.

[0006] From DE 10 2014 109 805 A1, an exhaust gas recirculation system is known which has a bypass line parallel to the air supply line of the combustion engine, which is filled exclusively with fresh air. This bypass line branches off from the air supply line upstream of the EGR inlet point and rejoins the air supply line downstream of the engine throttle valve. Corresponding to the air supply, the bypass line can also be opened and closed by a control valve. In the event of a load reduction, the engine throttle valve of the air supply line can be closed and the control valve of the bypass line can be opened, thereby allowing fresh air to be supplied to the combustion engine relatively quickly via the bypass line and thus preventing engine misfires.However, the EGR system described in DE 10 2014 109 805 A1 requires additional hardware components such as a bypass line and a bypass valve, as well as increased control effort, and is therefore associated with additional costs.

[0007] German patent application DE 10 2013 223 723 A1 describes an EGR device for an engine. The EGR device has an EGR channel, an EGR valve, an accelerator sensor, and an ECU. The ECU compares the rate of change (accelerator actuation speed) per unit of time of an accelerator opening degree with a predetermined initial value. If it is determined that a demand for deceleration or acceleration operation has been created for the engine, the ECU issues a command to fully close the EGR valve. If it is determined that the deceleration or acceleration operation demand persists, the ECU continues to issue the command to fully close the valve.If the delay or acceleration operation request is eliminated and the acceleration device opening degree is greater or less than a predetermined second determination value, the ECU cancels the command to close completely.

[0008] US 2012 / 0097126A1 describes how, in a gasoline direct-injection engine during acceleration, the amount of internal exhaust gas recirculation is increased by advancing the exhaust valve closing time and also increasing the fuel injection pressure. In this case, the range of the increase in fuel injection pressure is determined based on the current exhaust valve closing time.

[0009] This document addresses the technical challenge of providing a method and control unit that enables a combustion engine with exhaust gas recirculation to operate reliably and with optimal fuel consumption, even under load changes. The aim is to avoid any structural modifications to the exhaust gas recirculation system.

[0010] The problem is solved by the independent claims. Advantageous embodiments are described, among other things, in the dependent claims.

[0011] According to one aspect, a method for operating a vehicle's internal combustion engine (e.g., a diesel or gasoline engine) with an exhaust gas recirculation (EGR) system is described. The EGR system has an EGR dead time to adjust the amount of exhaust gas in the combustion engine's working gas. This dead time depends on the volume of the EGR system for receiving exhaust gases between an EGR valve and an inlet of the combustion engine. For example, the vehicle may include a turbocharger driven by exhaust gases from the combustion engine. The EGR system can then be designed such that exhaust gases are recirculated downstream of the turbocharger via an EGR valve to the combustion engine's inlet. In such a case, the volume of the EGR valve, and thus the EGR dead time, can be relatively large.

[0012] The EGR system can be operated in such a way that the amount of exhaust gas in the combustion engine's working gas is adjusted depending on the power demanded by the engine. The amount of exhaust gas can increase with increasing power demand (and vice versa). Consequently, during load changes, the working gas at the combustion engine's inlet may contain an incorrect amount of exhaust gas.

[0013] It can be detected that a (sudden) change in the power demanded by the internal combustion engine (i.e., a load) occurs, from an initial power level to a target power level. This change in demanded power can depend on a change in the deflection of the vehicle's accelerator pedal. The change in demanded power can also include a change in the torque demanded by the internal combustion engine.

[0014] The process involves controlling the EGR valve during the EGR dead time after a change in the required power output to modify the amount of recirculated exhaust gas in preparation for the desired target power. The target power output may be lower than the output power output, and the EGR valve can be controlled to reduce the amount of recirculated exhaust gas. For example, the EGR valve can be closed during the EGR dead time. Alternatively, the EGR valve can be controlled during the EGR dead time to ensure a sufficient amount of recirculated exhaust gas is present in the combustion engine's working gas to achieve the target power output. Thus, the amount of recirculated exhaust gas during the EGR dead time can be optimized for the combustion engine to operate at the target power output.

[0015] Furthermore, the procedure involves initiating one or more load-modifying measures so that, during the (typically entire) EGR dead time, the combustion engine delivers an intermediate power output that differs from the target power output. In other words, the combustion engine can operate at an intermediate power output that deviates from the target power output throughout the entire EGR dead time. For example, the intermediate power output can lie between the output power and the target power output. In particular, the intermediate power output can be closer to the output power output than to the target power output. If the target power output is lower than the output power output, the intermediate power output can be higher than the target power output. This can result in an increase in the combustion engine's operating point. Conversely, the intermediate power output can be lower than the target power output if the target power output is higher than the output power output.This allows for a reduction in the load point of the combustion engine.

[0016] An internal combustion engine may have a load limit below which the tolerance of EGR decreases significantly (especially abruptly). This load limit can be relatively small. At the load limit, the EGR rate should be reduced (abruptly) for stable operation of the internal combustion engine. For target power outputs below the load limit, the intermediate power output can be set at the engine's load limit.

[0017] The one or more load-influencing measures can include, for example: increasing or reducing the load on a component mechanically driven by the internal combustion engine, in particular a pump and / or an electric machine operated as a generator; increasing or reducing the vehicle's driving resistance (e.g., by applying friction brakes); and / or increasing or reducing mechanical losses in the vehicle's drivetrain (e.g., by slipping a clutch). In particular, measures can be taken in this way to place an additional load on the internal combustion engine when the target power output is reduced, thereby raising the engine's operating point.

[0018] Alternatively, the method involves controlling at least one of the vehicle's electric motors, so that during the (typically entire) EGR dead time after a change in the required power, the electric motor delivers the target power and the combustion engine is in overrun mode. This allows the exhaust gases trapped in the volume of the EGR system to be efficiently routed out of the combustion engine's combustion chamber.

[0019] The process can further include operating the combustion engine after the EGR dead time has elapsed, so that the combustion engine delivers the target power output. In other words, the combustion engine can only be operated at the target power output after the EGR dead time has elapsed (starting from the point at which the required power output changes). Following the EGR dead time, the EGR valve can then be actuated to provide a quantity of recirculated exhaust gas in the combustion engine's working gas to achieve the target power output. This ensures fuel-efficient operation after the EGR dead time has elapsed.

[0020] The method enables fuel-efficient and reliable operation of an internal combustion engine with EGR even in the event of sudden load changes (without structural modifications to the EGR system).

[0021] The vehicle may include an electrical energy storage device (e.g., a battery) for storing electrical energy. The one or more load-controlling measures may include controlling the electric machine to provide or draw at least a portion of the residual power (where the residual power corresponds to the difference between the intermediate power and the target power). The electrical energy storage device may be configured to provide electrical energy for the operation of the electric machine and / or to store electrical energy generated by the electric machine. The method may then include determining state-of-charge data with respect to a state of charge of the electrical energy storage device. The electric machine can then be controlled based on the state-of-charge data to provide or draw the residual power (and, if applicable, to reduce the load).to charge the energy storage system) or to deliver the target power output (and discharge the energy storage system). This allows for fuel-optimized load point adjustment of the combustion engine.

[0022] According to another aspect, a control unit for a vehicle is described, which includes an internal combustion engine with an EGR system. The EGR system has an EGR dead time to adjust the amount of exhaust gas in the combustion engine's working gas, where the EGR dead time depends on the volume of the EGR system for absorbing exhaust gases between an EGR valve and an inlet of the internal combustion engine.

[0023] The control unit is configured, in response to a change in the power demanded by the internal combustion engine from an output power to a target power, to actuate the EGR valve during the EGR dead time in order to modify the amount of recirculated exhaust gas in preparation for the required target power. The control unit is further configured to initiate one or more load-controlling measures so that, during the EGR dead time, the internal combustion engine delivers an intermediate power output that differs from the target power (and is typically between the output power and the target power). For example, the intermediate power output may be equal to the output power output. Alternatively, at least one of the vehicle's electric motors can be actuated so that, during the EGR dead time, the electric motor delivers the target power output and the internal combustion engine is in overrun mode.

[0024] According to another aspect, a vehicle (in particular a road vehicle, e.g. a passenger car, a truck or a motorcycle) is described that includes the control unit and / or the EGR system described in this document.

[0025] Another aspect described is a software (SW) program. The SW program can be configured to run on a processor (e.g., on a vehicle's control unit) and thereby execute the procedure described in this document.

[0026] Another aspect describes a storage medium. This storage medium can include a software program configured to run on a processor and thereby execute the procedure described in this document.

[0027] It should be noted that the methods, devices, and systems described in this document can be used both alone and in combination with other methods, devices, and systems described in this document. Furthermore, any aspect of the methods, devices, and systems described in this document can be combined with one another in a variety of ways. In particular, the features of the claims can be combined with one another in a variety of ways.

[0028] The invention will now be described in more detail using exemplary embodiments. Fig. 1 an exemplary EGR system of a vehicle; and Fig. 2 a flowchart of an exemplary procedure for controlling an internal combustion engine with exhaust gas recirculation.

[0029] As stated at the beginning, this document deals with the cost-efficient, reliable and fuel-optimized operation of an internal combustion engine with exhaust gas recirculation during a load change.

[0030] Fig. Figure 1 shows exemplary components of a vehicle 100. In particular, it shows Fig. 1 an internal combustion engine 103, wherein exhaust gases 122 from the combustion exit a combustion chamber of the internal combustion engine 103 via an outlet 132. In the figures, the arrows with solid lines represent the exhaust gases 122. A portion of the exhaust gases 122 can be recirculated via an EGR (exhaust gas recirculation) cooler 104 to an inlet 131 of the internal combustion engine 103. The amount of recirculated exhaust gases (i.e., the EGR rate) can be adjusted via an EGR valve 102. The EGR valve 102 can be controlled by a control unit 101 of the vehicle 100 by means of one or more control signals 121. Control signals 121 are shown in the figures as arrows with dashed-dotted lines. Exhaust gas recirculation can be advantageous in both diesel and gasoline engines to reduce emissions and / or fuel consumption.

[0031] The non-recirculated portion of the exhaust gases 122 can be used to drive an exhaust gas turbocharger 105. The turbocharger 105 draws in air 123, which is cooled in an intercooler 107 and supplied to the internal combustion engine 103. The intake air 123 is represented in the figures by arrows with dotted lines.

[0032] The exhaust gases 122 from the combustion engine 103 can be routed through a catalyst 106 and discharged from the vehicle 100. Typically, a lambda sensor 113 is located directly upstream of the catalyst 106. This sensor is designed to determine the oxygen content of the exhaust gases 122 flowing into the catalyst 106. The catalyst 106 can then be controlled based on the sensor data from the lambda sensor 113.

[0033] As in Fig. As shown in Figure 1, the coolant 124 heated by the EGR cooler 104 can be used to heat the internal combustion engine 103, e.g. to reduce the warm-up phase of the internal combustion engine 103. Fig. Figure 1 further shows a cooling water circuit of vehicle 100. The cooling water 124 (represented in the figures as arrows with dashed lines) is heated in the EGR cooler 104. The cooling water 124 is then routed past the internal combustion engine 103 to cool it or, during a warm-up phase, to heat it. The excess heat from the cooling water 124 can be dissipated to the surroundings of vehicle 100 via a coolant radiator 108. Alternatively or additionally, the heat from the cooling water 124 can be transferred to the interior or passenger compartment of vehicle 109 via a heater core 109. The supply of cooling water to the coolant radiator 108 and / or the heater core 109 and / or the internal combustion engine 103 can be controlled by a thermostat and a coolant valve 112. A flow of cooling water 124 through the cooling water circuit of the vehicle 100 can be effected by one or more water pumps 110, 111.

[0034] The in Fig. The EGR system shown is a high-pressure exhaust gas recirculation system in which exhaust gases 122 are recirculated at a relatively high pressure. Alternatively, low-pressure exhaust gas recirculation can be used, in which the exhaust gas 122 is taken upstream (see variant 151 shown with dashed lines) or downstream (see variant 152 shown with dashed lines) of the catalyst 106 and then mixed back into the fresh air upstream of the compressor (of the turbocharger 150). In a low-pressure EGR system, the exhaust gas 122 can also be cooled by a cooler 104 and / or metered via an EGR valve 102. The measures described in this document are applicable to both high-pressure and low-pressure EGR systems.

[0035] A collector can be arranged at the inlet 131 of the internal combustion engine 103, in which a gas mixture or working gas is produced from recirculated exhaust gases 122 and intake air 123. The working gas is supplied to the internal combustion engine 103 to provide a fuel-gas mixture for a combustion process in a combustion chamber of the internal combustion engine 103. The amount of fuel supplied is adjusted via injection nozzles of the internal combustion engine 103.

[0036] A fuel-efficient combustion process requires a precise proportion of exhaust gas 122 in the working gas, which can be adjusted via the position of the EGR valve 102 and thus via the EGR rate. As explained above, the required amount of exhaust gas 122 depends on the operating point of the internal combustion engine 103. Typically, the required amount of exhaust gas 122 increases with the mechanical power to be delivered by the internal combustion engine 103, i.e., with the load of the internal combustion engine 103. Consequently, a change in the load of the internal combustion engine 103 typically requires a change in the EGR rate. However, due to the mass of exhaust gas 122 trapped between the EGR valve 102 and the manifold, the exhaust gas proportion in the working gas at the inlet 131 of the internal combustion engine 103 can typically only be changed after a certain delay, i.e., after an EGR dead time.In other words, a change in the setting of the EGR valve 102 typically only affects the composition of the working gas at the inlet 131 of the internal combustion engine 103 (to a certain predefined degree) after an EGR dead time. As a consequence, after an (abrupt) change in load, the internal combustion engine 103 typically cannot be operated with an optimally composed working gas until the EGR dead time has elapsed, which can lead to increased fuel consumption and / or misfires in the internal combustion engine 103.

[0037] The control unit 101 can be configured to detect a (sudden) change in the power required to propel the vehicle 100 from the internal combustion engine 103. In particular, it can detect that the required drive power changes (suddenly) from an output power to a target power. The output power can correspond to an initial operating point and the target power to a target operating point of the internal combustion engine 103.

[0038] In response to a load change, the EGR valve 102 can be actuated to adjust the EGR rate for the target power output. Since the internal combustion engine 103 is still exposed to the EGR rate for the output power output for the duration of the EGR dead time, the control unit 101 can be further configured to actuate one or more load-influencing components 150 of the vehicle 100 to at least partially compensate for the load change of the internal combustion engine 103 for the duration of the EGR dead time. In particular, the one or more load-influencing components 150 of the vehicle 100 can be actuated to at least partially compensate for the difference between the target power output and the output power output, so that the internal combustion engine 103 can continue to operate at (or near) the output operating point for the duration of the EGR dead time. Only after the EGR dead time has elapsed can the combustion engine 103 be brought into the target operating point.In this way, fuel-efficient and reliable operation of an internal combustion engine 103 during load changes can be ensured in an efficient manner and without structural changes to the EGR system.

[0039] The combustion engine 103 can thus, for example, be maintained at a higher torque during a load shedding event than is required to fulfill a driver request (i.e., to meet a requested drive torque). The magnitude of this load point shift of the combustion engine 103 can be selected such that the combustion engine 103 is temporarily operated in torque ranges where high EGR compatibility is ensured (i.e., where working gases with a relatively high proportion of exhaust gases 122 can be reliably processed by the combustion engine 103). During this load point shift following a load shedding event, the EGR valve 102 can be closed. As soon as the air ducts are filled exclusively with fresh air, the load point shift can be terminated and the engine torque reduced to the driver-requested level.

[0040] The torque difference resulting from this load point shift between the driver's desired torque (i.e., the target torque) and the torque required for the load point shift (e.g., the output torque) must be compensated within the vehicle's powertrain 100. For example, the excess torque can be converted into electrical energy by engaging a generator 150. The generated electrical energy can be used, for example, to charge a battery and / or utilized in the vehicle's electrical system 100. Alternatively or additionally, mechanically driven, load-controlled components 150 can be used to impose an additional load on the internal combustion engine 103. Examples of such components 150 are: a mechanically driven, load-controlled refrigerant compressor; a mechanically driven, load-controlled engine oil pump; a mechanically driven, load-controlled transmission oil pump (e.g.,for a manual transmission or transfer case); a mechanically driven load-controlled fuel pump (e.g., a high-pressure pump); a mechanically driven load-controlled water pump; a mechanically driven load-controlled vacuum pump; and / or one or more other mechanically driven load-controlled units connected to the drivetrain.

[0041] Alternatively or additionally, measures can be initiated that increase driving resistance or drivetrain resistance, thus requiring higher engine torque. Examples of such measures include: brake intervention; extending a spoiler; opening the switchable air flap system in front of the vehicle's radiator; enabling slip operation of an electrically actuated clutch in a manual transmission (eClutch); enabling slip operation of the torque converter lock-up clutch; enabling slip operation of a shift clutch in an automatic transmission; actuating a hydrodynamic torque converter; enabling slip operation of a transfer case clutch; etc.

[0042] The load point or operating point of the internal combustion engine 103 can be shifted such that the internal combustion engine 103 is towed with deactivated injection during the EGR dead time (and the exhaust gas 122 passes through the combustion chamber of the internal combustion engine 103 from the EGR system). The torque required to deliver the target power can then be provided by an (electric) generator of the vehicle 100 (e.g., a low-voltage (e.g., 48V) generator) (using electrical energy from the vehicle's electrical system / from an electrical energy storage device (e.g., a battery) of the vehicle 100). The EGR valve 102 can also be closed during such a load shift. As soon as the path between the EGR inlet and the cylinder of the internal combustion engine 103 is free of residual exhaust gases 122, or...Until a tolerable level of residual exhaust gases has been reached, the combustion engine 103 can be put back into firing operation and the load point shift can be ended.

[0043] Fig. Figure 2 shows a flowchart of an exemplary procedure 200 for operating an internal combustion engine 103 of a vehicle 100 with an exhaust gas recirculation (EGR) system. This can be, in particular, a low-pressure EGR system. Within the framework of the control or regulation of the EGR system, the quantity of recirculated exhaust gases 122 is typically adapted to the power output or torque of the internal combustion engine 103 in order to ensure the most fuel-efficient operation of the internal combustion engine 103. In particular, the quantity of recirculated exhaust gases 122 or the quantity of exhaust gases 122 in the working gas of the internal combustion engine 103 can be increased with increasing power output or increasing torque.

[0044] The EGR system has an EGR dead time to adjust the amount of exhaust gas 122 in the working gas of the internal combustion engine 103. The EGR dead time depends on the volume of the EGR system for receiving exhaust gases 122, which extends from the EGR valve 102 to the inlet 131 of the internal combustion engine 103. This volume can be relatively large, especially in low-pressure EGR systems. Since the EGR dead time typically increases with increasing volume, it can be particularly long in low-pressure EGR systems.

[0045] Due to the adjustment of the amount of recirculated exhaust gas 122, during power jumps of the combustion engine 103 from an output power to a target power (or during torque jumps from an output torque to a target torque), the amount of recirculated exhaust gas 122 may be too high at a target power that is lower than the output power, or too low at a target power that is higher than the output power. Due to the EGR dead time, this situation with increased or reduced exhaust gas quantities in the combustion engine 103 can persist for a certain period, thus affecting the operation and / or fuel consumption of the combustion engine 103.

[0046] Method 200 comprises, in response to a change in the power demanded by the combustion engine 103 from the initial power to the target power (or in response to a torque jump), actuating 201 the EGR valve 102 during the EGR dead time to change the quantity of recirculated exhaust gas 122 in preparation for the required target power. In particular, the EGR valve 102 can be actuated during the EGR dead time after a change in the required power to reduce the quantity of recirculated exhaust gas 122 if the required power is reduced, or to increase the quantity of recirculated exhaust gas 122 if the required power is increased. In this way, the aforementioned volume of the EGR system can be prepared for the change in power of the combustion engine 103 (and is typically ready for the power change after the EGR dead time has elapsed).

[0047] Furthermore, the procedure 200 includes initiating 202 one or more load-controlling measures so that, during the EGR dead time, the internal combustion engine 103 delivers an intermediate power output that deviates from the target power output (e.g., higher than the target power output if the target power output is lower than the output power output). In particular, the intermediate power output can correspond to the EGR power limit of the internal combustion engine 103. If necessary, the internal combustion engine 103 can continue to operate at the output power output (and thus in a fuel-optimized manner) during the EGR dead time after the required power output has been changed. For this purpose, load-controlling measures can be implemented that either load the internal combustion engine 103 (if the target power output is lower than the output power output) or relieve it (if the target power output is higher than the output power output).

[0048] Alternatively, the procedure 200 can include controlling 202 at least one electric machine 150 (e.g., a low-voltage (possibly 48V) electric motor) of the vehicle 100, so that during the EGR dead time, the at least one electric machine 150 provides the target power and the internal combustion engine 103 is in overrun mode. In other words, the internal combustion engine 103 can be operated in overrun mode for the EGR dead time after changing the required power, in order to direct an exhaust gas quantity corresponding to the aforementioned volume through the combustion chamber of the internal combustion engine 103. The target power to be provided can then be supplied by one or more electric machines 150 of the vehicle 100.

[0049] After the EGR dead time has elapsed (directly following the change in the required power), the combustion engine 103 can then be operated in a fuel consumption-optimized manner to achieve the target power output.

[0050] The load point shifts of an internal combustion engine 103 described in this document prevent engine misfires during load reduction. This allows for the use of relatively high EGR rates, particularly in relatively high load ranges of the internal combustion engine 103, to further reduce its fuel consumption. This eliminates the need for design modifications (e.g., providing a bypass line). The described load point shift can be implemented cost-effectively using existing components of a vehicle 100.

[0051] When a generator or electric motor is used, the load point shift of the internal combustion engine 103 can be adjusted depending on the state of charge of the vehicle's electrical energy storage device 100. At relatively low states of charge, the electric motor, operating as a generator, can shift the load point to higher load ranges to generate electrical energy for charging the energy storage device. Conversely, at relatively high states of charge, the electric motor can cause a negative load point shift of the internal combustion engine 103, in which case electrical energy is drawn from the energy storage device to drive the electric motor and thus the internal combustion engine 103. This reduces the fuel consumption of the internal combustion engine 103 to zero.

[0052] The present invention is not limited to the embodiments shown. In particular, it should be noted that the description and the figures are intended only to illustrate the principle of the proposed methods, devices, and systems.

Claims

[1] Method (200) for operating an internal combustion engine (103) of a vehicle (100) with an exhaust gas recirculation (EGR) system; wherein the EGR system has an EGR dead time for adjusting an amount of exhaust gas (122) in a working gas of the internal combustion engine (103), which depends on a space volume of the EGR system for receiving exhaust gas (122) between an EGR valve (102) and an inlet (131) of the internal combustion engine (103); wherein the method (200) comprises, in response to a change in a power demanded by the internal combustion engine (103) from an output power to a target power, - Actuating (201) the EGR valve (102) during the EGR dead time to modify the amount of recirculated exhaust gas (122) in preparation for the required target power output; and - Initiating (202) one or more load-controlling measures so that during the EGR dead time the internal combustion engine (103) delivers an intermediate power output that differs from the target power output; or Control (202) at least one electric machine (150) of the vehicle (100), so that during the EGR dead time the at least one electric machine (150) provides the target power and the internal combustion engine (103) is in overrun mode. [2] Method (200) according to claim 1, wherein - the target output is lower than the output output; and - the EGR valve (102) is controlled to reduce the amount of recirculated exhaust gases (122). [3] Method (200) according to claim 2, wherein the EGR valve (102) - is closed during the EGR dead time; and - is controlled following the EGR dead time to provide a quantity of recirculated exhaust gases (122) in the working gas of the combustion engine (103) to deliver the target power. [4] Method (200) according to one of the preceding claims, wherein the method (200) comprises, after the EGR dead time has elapsed, operating the internal combustion engine (103) so that the internal combustion engine (103) delivers the target power. [5] Method (200) according to any one of the preceding claims, wherein - the vehicle (100) includes an electrical energy storage device for storing electrical energy; - a residual performance corresponds to the difference between intermediate performance and target performance; - the one or more load-controlling measures include controlling the electric machine (150) to provide or absorb at least part of the residual power; - the electrical energy storage device is set up to provide electrical energy for the operation of the electrical machine (150) and / or to store electrical energy generated by the electrical machine (150); and - the procedure (200) includes, - Determining state-of-charge data in relation to the state of charge of the electrical energy storage device; and - depending on the charge status data, control of the electric machine (150) to - to provide or accept the residual service; or - to achieve the target performance. [6] Method (200) according to any one of the preceding claims, wherein the one or more load-controlling measures comprise one or more of: - Increasing or reducing the load of a component (150) mechanically driven by the internal combustion engine (103), in particular a pump and / or an electric machine (150) operated as a generator, of the vehicle (100); - Increasing or reducing the vehicle's driving resistance (100); and / or - Increasing or reducing mechanical losses in a vehicle's drivetrain (100). [7] Method (200) according to any one of the preceding claims, wherein - the change in the required power depends on a change in the deflection of an accelerator pedal of the vehicle (100); and / or - the change in the required power includes a change in the torque required by the internal combustion engine (103). [8] Method (200) according to one of the preceding claims, wherein the EGR system is operated such that the quantity of exhaust gases (122) in the working gas of the internal combustion engine (103) - is adapted depending on the power required by the internal combustion engine (103); and - especially as the required performance increases. [9] Method (200) according to any one of the preceding claims, wherein - the vehicle (100) includes a turbocharger (105) which is driven by exhaust gases (122) from the internal combustion engine (103); and - the EGR system is designed such that exhaust gases (122) are recirculated downstream from the turbocharger (105) to the inlet (131) of the internal combustion engine (103). [10] Control unit (101) for a vehicle (100) comprising an internal combustion engine (103) with an exhaust gas recirculation (EGR) system; wherein the EGR system has an EGR dead time for adjusting the quantity of exhaust gases (122) in a working gas of the internal combustion engine (103); wherein the EGR dead time depends on a space volume of the EGR system for receiving exhaust gases (122) between an EGR valve (102) and an inlet (131) of the internal combustion engine (103); wherein the control unit (101) is configured to respond to a change in the power demanded by the internal combustion engine (103) from an output power to a target power, - to actuate the EGR valve (102) during the EGR dead time to modify the amount of recirculated exhaust gas (122) in preparation for the required target power output; and - to initiate one or more load-controlling measures so that during the EGR dead time the internal combustion engine (103) delivers an intermediate power output that differs from the target power output; or at least to control an electric machine (150) of the vehicle (100) so that during the EGR dead time the electric machine (150) delivers the target power output and the internal combustion engine (103) is in overrun mode.

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