Method for operating an internal combustion engine

Abstract

A method for operating an internal combustion engine (2), wherein a filling actuator (10; 16) is arranged between an exhaust gas recirculation (24) and a combustion chamber (4) of the internal combustion engine (2), characterized in that a control variable (m) for operating the filling actuator (10; 16) depends on a first actual filling (m fg ) from a fresh air path and depending on a second actual filling level (m agr ) is determined from the exhaust gas recirculation (24).

Description

State of the art

[0001] The invention relates to a method for operating an internal combustion engine according to the preamble of claim 1.

[0002] From DE 10 2012 207 266 A1, a control loop for regulating boost pressure in the exhaust system of an internal combustion engine is known. A valve designed as an actuator serves to bypass an exhaust turbine of a turbocharger.

[0003] From DE 10 2012 222 107 A1, a method for controlling the exhaust gas recirculation of an internal combustion engine is known. A target power output to be delivered by the internal combustion engine is determined. Based on this target power output, an exhaust gas flow to be routed through the exhaust gas recirculation system is determined.

[0004] WO 2007 / 107 865 A2 discloses an exhaust gas control system in which the mixing ratio of high-pressure and low-pressure exhaust gas recirculation is regulated in such a way as to minimize the engine's fuel consumption.

[0005] The JP H11 - 82 100 A discloses an engine control system that, based on a target engine torque, performs comprehensive control of fuel injection, air supply and exhaust gas recirculation (EGR), whereby the target values ​​for the air mass and the EGR rate are determined model-based on deviations between estimated and target partial pressures of the fresh air and EGR components in the intake tract in order to improve responsiveness and emissions.

[0006] Furthermore, it is known that various components are used to regulate the air mass flow in order to meet load demands. In turbocharged engines, these are essentially a throttle valve and a turbocharger. To achieve further reductions in fuel consumption and emissions, an EGR valve for external exhaust gas recirculation (EGR) is also used. In gasoline engines with low-pressure EGR (NDGR), the exhaust gas is extracted after exhaust aftertreatment and reintroduced before the turbocharger. A conflict of objectives exists in the control of the actuators involved, as both emission reduction via exhaust gas recirculation and the fastest possible implementation of the driver's request are desired. Disclosure of the invention

[0007] The problem underlying the invention is solved by a method according to claim 1. Advantageous embodiments are specified in the dependent claims. Further features important to the invention are found in the following description and in the drawings, whereby the features can be important to the invention both individually and in various combinations, without this being explicitly stated again.

[0008] By determining a control variable for the operation of an internal combustion engine, particularly a gasoline engine, in which a charge controller is arranged between an exhaust gas recirculation system and a combustion chamber, based on a first actual charge from a fresh air path and a second actual charge from the exhaust gas recirculation system, the control of the charge controller is advantageously simplified. This choice of control variable for the charge controller advantageously enables the decoupling of the charge and exhaust gas recirculation control systems. Furthermore, the first and second actual charge values ​​can thus be determined advantageously independently of each other. This principle can be applied to both turbocharged and naturally aspirated states of the internal combustion engine.In particular, a persistent deviation in the air charge is avoided, as the exhaust gas mass flow is taken into account in the charge control. Furthermore, no operating-point-dependent controller coefficients need to be determined, which significantly reduces application and data configuration effort. Moreover, separating the two actual charge values ​​with respect to the controlled variable allows the exhaust gas recirculation controller to be better adapted, both dynamically and in steady-state conditions, to the charge controller, which essentially implements the load requirement.

[0009] In an advantageous embodiment, a throttle device is operated as a filling controller with the controlled variable in an uncharged state of the internal combustion engine.

[0010] In an advantageous embodiment, an exhaust gas recirculation (EGR) actuator is operated in the uncharged state based on a setpoint for the mass flow rate from the exhaust gas recirculation. This setpoint is determined as a reference variable based on a first target EGR rate in a first feed section upstream of the throttle device. The first target EGR rate is determined as a reference variable based on a second target EGR rate in a second feed section downstream of the throttle device. Considering two volumes in the form of the two feed sections, separated by the throttle device, improves the accuracy of both the EGR control and the charge control.

[0011] In an advantageous embodiment, the first target exhaust gas recirculation rate in the uncharged state comprises a control component and a pilot component. The second target exhaust gas recirculation rate also comprises a control component and a pilot component. Providing both a control component and a pilot component advantageously allows the dynamics of the two target exhaust gas recirculation rates to be defined independently of the charge control. Inaccuracies in the pilot component are advantageously compensated for by the control component.

[0012] In an advantageous embodiment, the throttle device is operated in the uncharged state based on a setpoint value for the mass flow rate through the throttle device. This setpoint value depends on the total charge, which comprises the first charge from the fresh air path and the second charge from the exhaust gas recirculation, and is determined based on a control component and a feedforward component. Providing both a control component and a feedforward component advantageously allows the dynamics of the charge control to be defined independently of the exhaust gas control. Inaccuracies in the feedforward component are advantageously compensated for by the control component.

[0013] In an advantageous embodiment, in a charged state of the internal combustion engine, a charging device is operated as a filling controller with the controlled variable.

[0014] In an advantageous embodiment, an exhaust gas recirculation actuator is operated in the charged state depending on a setpoint value for the mass flow rate from the exhaust gas recirculation. The setpoint value for the mass flow rate from the exhaust gas recirculation is determined as a function of a target exhaust gas recirculation rate in a total volume as a control variable.

[0015] In an advantageous embodiment, the actual pressure in the total volume is determined in the charged state as a function of the controlled variable. A target pressure in the total volume is determined as a function of a reference variable for the charging device.

[0016] In an advantageous embodiment, the target value for the mass flow rate from the exhaust gas recirculation is determined in the charged state from a control component and a pilot component. Providing both a control component and a pilot component advantageously allows the dynamics of the exhaust gas control to be defined independently of the charge control. Inaccuracies in the pilot component are advantageously compensated for by the control component.

[0017] Further features, applications, and advantages of the invention will become apparent from the following description of exemplary embodiments of the invention, which are illustrated in the figures of the drawing. The same reference numerals are used in all figures for functionally equivalent quantities and features, even in different embodiments.

[0018] Exemplary embodiments of the invention are explained below with reference to the drawing. The drawing shows Fig. 1. A schematic representation of an internal combustion engine; Fig. 2 a schematic state transition diagram; and Fig. 3 and Fig. 4 each a schematic block diagram.

[0019] Fig. Figure 1 shows a schematic representation of an engine system 1 with an internal combustion engine 2, for example a gasoline engine, with four combustion chambers 4. A mass flow is supplied to the respective combustion chambers 4 via a first and second supply section 6, 8, between which a throttle device 10, which can also be called a throttle valve, is arranged. After combustion, the exhaust gas 13 from the respective combustion chamber 4 is supplied to a first exhaust gas discharge section 14. The throttle device 10 can also be called a charge controller. The second supply section 8 can also be called an intake manifold.

[0020] A charging device 16 is provided, which in the illustrated embodiment is designed as a turbocharger. The charging device 16 comprises a turbine 18, which is located between the first exhaust gas discharge section 14 and a second exhaust gas discharge section 20, and which is driven by the exhaust gas flow of the internal combustion engine 2. A compressor 22 is coupled to the turbine 18 to supply air at a boost pressure in the supply sections 6 and 8. The charging device 16 can also be referred to as a charge controller.

[0021] Exhaust gas from the second exhaust gas discharge section 20 can be introduced via an exhaust gas recirculation system 24, which can also be referred to as low-pressure exhaust gas recirculation, at an inlet point 28 between a fresh air section 30 and a third supply section 32, depending on the opening degree of an exhaust gas recirculation actuator 26. Alternatively, a multi-stage exhaust gas recirculation system or an additional high-pressure exhaust gas recirculation system can be provided. Both the throttle device 10 and the charging device 16 are arranged between the exhaust gas recirculation system 24 and the respective combustion chambers 4 of the internal combustion engine 2.

[0022] A control unit 25 sets the states of the exhaust gas recirculation actuator 26, the throttle device 10, and the charging device 16 via an actuator 36. Naturally, the control unit 25 can also make other settings, such as adjusting the fuel injection quantity for the combustion chambers 4. Sensor signals supplied to the control unit 25 are not shown.

[0023] Fig. Figure 2 shows a schematic state transition diagram 38 with an uncharged state 40 and a charged state 42. According to the state transitions 44 and 46, it is possible to switch between states 40 and 42.

[0024] In the uncharged state 40, the internal combustion engine 2 is not supercharged; that is, the pressure in the feed sections 6 and 8 is not increased by the charging device 16. In the uncharged state 40, the charge in the combustion chambers 4 is adjusted solely by the throttle device 10.

[0025] In the charged state 42, however, the throttle device 10 is fully opened, so that the feed sections 6 and 8 become one section. In the charged state 42, a boost pressure is generated, which results in an increase in pressure from section 32 to section 6.

[0026] Of course, an embodiment of the method is also possible in which the system 1 does not have a charging device 16 and the system 1 is therefore always in the uncharged state 40.

[0027] Fig. Figure 3 shows a schematic block diagram for the uncharged state 40. In the uncharged state 40, the required charge is provided by the throttle device 10 as the charge controller. The required EGR rate is provided by the exhaust gas recirculation valve 26. Due to the throttle device 10 not being fully open, two partial volume elements result according to the two feed sections 6 and 8.

[0028] A mass flow balance for the first feed section 6 can be calculated using Equation 1. A mass flow balance for the second feed section 8 can be calculated using Equation 2. Here, V vdk the volume in the area before the throttling device 10 and thus the volume in the first feed section 6, where the first feed section 6 can also be referred to as the pre-volume, R is the universal gas constant, T vdk is a temperature in the volume V vdk , ṗ vdis the temporal derivative of a pressure in the feed section 6, ṁ agrv is an actual mass flow via the exhaust gas recirculation actuator 26, ṁ hfm is an actual mass flow in the fresh air section 30, for example via an air mass sensor not shown, ṁ dk is an actual mass flow through the throttle device 10, V sr is a volume of the feed section 8, where the feed section 8 can also be called the suction pipe section, ṗ sr is the time derivative of the pressure in the feed section 8, m fg is an air mass from the fresh air section 30, m agr is an exhaust gas mass from the exhaust gas recirculation 24, and k ms is a conversion factor from a filling volume to a mass flow rate. VvdkR⋅Tvdk⋅p˙vd=m˙agrv+m˙hfm−m˙dk VsrR⋅Tsr⋅p˙sr=m˙dk−(mfg−magr)⋅kms

[0029] A dynamic of an actual exhaust gas recirculation rate x vdkIn the feed section 6, the following equation 3 results. A dynamic of an actual exhaust gas recirculation rate x sr In the feed section 8, the following equation 4 results. Here, p vd an actual boost pressure in the supply section 6, λ is a stoichiometric ratio of combustion air to fuel, (m˙agrv+m˙hfm)⋅xvdk+pvdVvdkR⋅Tvdk⋅dxvdkdt=m˙agrv⋅1λ m˙dk⋅xsr+psrVsrR⋅Tsr⋅dxsrdt=m˙dk⋅xvdk

[0030] From the ideal gas law, for a combustion chamber 4 at a time when an inlet valve associated with combustion chamber 4 closes, equation 5 results, where p sr an actual pressure in the second feed section 8 is, where k pm is a conversion factor from a pressure to a filling, and where p brint A partial pressure in combustion chamber 4 is determined by internal exhaust gas recirculation. Equation 5 establishes a relationship between the actual pressure p. sr and the actual filling mfg fresh air 31 supplied externally via fresh air path 30 and the actual filling level m agr from exhaust gases recirculated via the exhaust gas recirculation system. psr=(mfg+magr) / kpm+pbrint

[0031] Depending on the rotational speed n of the internal combustion engine 2 and depending on a target engine torque M, which corresponds to the driver's torque request, a first target filling m is achieved by means of a block 48. fg,soll for externally supplied fresh air, a second target filling is achieved by means of a block 50. agr,soll for recirculated exhaust gas, and by means of a block 52 a target rate x cb,soll for external inert gas from the exhaust gas recirculation 24 in the combustion chamber 4, for example, via a correspondingly datable characteristic map.

[0032] In Fig. Figure 3 shows a filling control 54, an exhaust gas recirculation control 56, and the engine system 1, with the engine system 1 being represented as the control loop. The target fillings m fg,soll and m agr,soll At one point, 58 are added together, resulting in a target fill level m. soll The target filling level m soll is supplied to both a feedforward control unit 60 and a position 62. The target fill level m soll is also referred to as a leading indicator.

[0033] An initial actual fill m fg The amount of fresh air is determined using block 64. A second actual filling m agr The exhaust gas is determined using block 66. The actual filling levels m fg and m agr The values ​​are added at point 68 and fed back to point 62 in the form of an actual fill level m. A control deviation Δm results from subtracting the actual fill level m from the target fill level m. sollThe control error Δm is fed to a controller 70. The actual fill level m is also referred to as the controlled variable.

[0034] The input control 60 determines an input control component ṁ according to equation 6. dk,ff for a target mass flow rate ṁ dk,soll via the throttle device 10, wherein (m fg + m agr ) soll the target filling m soll corresponds, and where τ msr The actual time constant of a fill in feed section 8 is τ. msr This results according to equation 7, where k ms is a conversion factor of a filling into a mass flow, and where T sr a temperature in the second feed section 8 is. m˙dk,ff=kms⋅((mfg+magr)set+τmsrd(mfg+magr)setpoint) τms=1kms1kpmVsrR⋅Tsr

[0035] The controller 70, which is designed as an example proportional controller, in particular for a desired PT1 behavior, determines a control component ṁ according to equation 8. dk,fb for the one target mass flow rate ṁ dk,soll via the throttle device 10 as a function of the control error Δm = ((m fg + m agr ) soll - (m fg + m agr )), where the dynamics of the filling build-up vary over a time constant τ msr,soll can be adjusted. Of course, the controller 70 can also be designed differently and exhibit a different desired dynamic than that specified by equation 8. m˙dk,fb=kms⋅(τmsrτmsr,set−1)⋅((mfg+magr)set−(mfg+magr))

[0036] The input tax share ṁ dk,ff and the rule component ṁ dk,fb The values ​​72 are added at one point and used as a target mass flow rate ṁ dk,sollThe setpoint value is fed to the throttle device 10 via the throttle device 10. Naturally, the target mass flow rate ṁ can also be fed to a further subordinate control loop (not shown). dk,soll a signal is supplied, which then transmits a corresponding control variable to the throttle device 10.

[0037] For the exhaust gas recirculation control 56, a block 74 determines a target exhaust gas recirculation rate x sr,soll in the second feed section 8 depending on the target filling m soll and depending on the target rate x cb,soll for example, by means of a datable characteristic map.

[0038] A controller 76 determines a control component x vdk,fb a target exhaust gas recirculation rate x vdk,soll in the first feed section 8 depending on a control deviation Δx sr , which according to point 77 results from a subtraction of the actual exhaust gas recirculation rate x srin the feed section 8, which is determined by means of a block 78, from the target exhaust gas recirculation rate x sr,soll in the second feed section 8 is determined.

[0039] A pre-tax controller 80 determines a pre-tax share x vdk,ff the target exhaust gas recirculation rate x vdk,soll depending on the target exhaust gas recirculation rate x sr,soll in the second feed section 8 and according to equations 9 and 10, where the actual mass flow rate ṁ dk is determined via the throttle device 10 by means of a block 82, and wherein the actual pressure p sr in the second feed section 8 is determined by means of a block 84. xvdk,ff=xsr,set+τxsrdxsr,setpoint τxsr=1m˙dkpsrVsrR⋅Tsr

[0040] The sum resulting at point 86 from the input tax share x vdk,ff and the regular share x vdk,fb is defined as the target exhaust gas recirculation rate x vdk,sollin the first feed section 6 to a point 88 and to a further feed control 90.

[0041] A controller 92 determines a control component ṁ agrv,fb a target exhaust gas mass flow ṁ agrv,soll , which is also referred to as the setpoint, via the exhaust gas recirculation actuator 26 as a function of a control deviation Δx vdk , which according to point 88 results from a subtraction of the actual exhaust gas recirculation rate x vdk in the first feed section 6, which is determined by means of a block 94, from the target exhaust gas recirculation rate x vdk,soll is determined in the first feed section 6.

[0042] The respective actual values ​​determined by blocks 64, 66, 78 and 94 can be adjusted depending on measured values ​​and / or depending on values ​​determined in the control unit 25.

[0043] The input tax 90 determines an input tax share ṁ agrv,ff of the target exhaust gas mass flow ṁ agrv,sollvia the exhaust gas recirculation actuator 26 according to equations 11 and 12. The actual mass flow rate ṁ hfm The pressure in the fresh air section 30 is determined by a block 98. The pressure p vd In the first feed section 6, 100 is determined from a block. m˙agrv,ff=m˙hfm1λ−xsr,soll⋅(xsr,soll+τxsrdxsr,solldt) τxsr=1m˙hfmpvdVgesR⋅Tges

[0044] At position 96, the sum is obtained from the rule component ṁ agrv,fb and the input tax share ṁ agrv,ff to the target exhaust gas mass flow ṁ agrv,soll via the exhaust gas recirculation actuator 26. The target exhaust gas mass flow ṁ agrv,soll The exhaust gas recirculation actuator 26 is fed to the exhaust gas recirculation system 24. Naturally, the target exhaust gas mass flow ṁ can be fed to a further subordinate control loop not shown. agrv,soll a corresponding control variable is supplied, which then passes on to the exhaust gas recirculation actuator 26 of the exhaust gas recirculation 24.

[0045] Similar to the regularity factor ṁ dk,fb For external filling, the control components of the cascaded control structure in the exhaust gas recirculation control 56 result from the required behavior of the target / actual deviation of the EGR rate according to the control differences Δx sr and Δx vdk in the individual sub-volume elements according to the feed sections 6 and 8. Via the control components x vdk,fb and ṁ agrv,fbThe desired dynamics of the EGR rates are defined using target time constants, and these are advantageously set separately, independent of the cylinder filling. A first target time constant is provided for defining the dynamics of the exhaust gas recirculation rate in the upstream volume. A second target time constant is provided for defining the dynamics of the exhaust gas recirculation rate in the intake manifold. The parameters provided by blocks 82, 84, 98, and 100 are each measured as actual values ​​or determined using a model and can be described as feedforward variables from a control engineering perspective.

[0046] Due to the long runtime in the feed sections 6 and 8, a dead time behavior in the respective EGR rates x sr and x vdk to be taken into account. For example, a Smith predictor can be used to achieve stable control of the EGR rates x. sr and x vdkDespite the existing dead time, stable control of the EGR rates x can of course also be achieved using other control engineering measures. sr and x vdk can be achieved.

[0047] Therefore, in Fig. 3 showed that by means of the filling control 54 the controlled variable m for the operation of the throttling device 10 as a function of the first actual filling m fg from fresh air from the fresh air path and depending on the second actual filling level m agr which is determined from the exhaust gas recirculation 24.

[0048] Fig. Figure 4 shows a schematic block diagram for the charged state 42. In the charged state 42, the required air charge is provided by the charging device 16. The throttle device 10 is fully open, resulting in a total volume 102 that combines the supply sections 6 and 8. The required EGR rate is provided by the exhaust gas recirculation actuator 26. In contrast to the one in Fig. 3 depicted uncharged states 40 are in Fig. 4 another filling control 154 and another exhaust gas recirculation control 156 are shown.

[0049] In further filling regulation 154, the target filling m soll by means of a block 104, for example by means of a characteristic curve or a factor, into a target pressure p soll converted in the range of 102, where the target pressure p sollas shown in equation 13. A control deviation Δp is fed to a boost pressure regulator 106 and results from the subtraction of an actual pressure p in area 102, which is determined from the actual fill m by means of a block 108, from the target fill m soll The boost pressure regulator 106 generates a manipulated variable p. act , which is supplied to the charging device 16. psoll=(mfg+magr)soll / kpm+pbrint

[0050] In the further exhaust gas recirculation control 156, a target exhaust gas recirculation rate x is set by means of a block 110. soll in the total volume 102 depending on the target rate x cb,soll for external inert gas from exhaust gas recirculation 24 and depending on the target filling m soll determined.

[0051] A controller 112 determines a control component ṁ agrv,fb of the target exhaust gas mass flow ṁ agrv,sollvia the exhaust gas recirculation actuator 24 depending on a control difference Δx, which results from the subtraction of an actual exhaust gas recirculation rate x in the total volume 102, which is determined by a block 114, from the target exhaust gas recirculation rate x soll in the total volume 102 at one point results in 116.

[0052] A pre-taxation 120 determines a pre-tax share ṁ agrv,ff of the target exhaust gas mass flow ṁ agrv,soll via the exhaust gas recirculation actuator 26 according to equations 14 and 15, where T ges the mean temperature in the total volume is 102, and where V ges The volume of the total volume is 102. The actual mass flow rate ṁ hfm The pressure in the fresh air section 30 is determined by block 98. The pressure p vd The total volume of 102 is determined by block 100. The target exhaust gas mass flow rate ṁ agrv,soll is fed to the exhaust gas recirculation actuator 26 of the exhaust gas recirculation system 24. m˙agrv,ff=m˙hfm1λ−xsoll⋅(xsoll+τxsrdxsolldt) τxsr=1m˙hfmpvdVgesR⋅Tges

[0053] Due to the long runtime in the feed sections, dead time in the EGR rate x must be taken into account. A Smith predictor, for example, ensures stable control of the EGR rate x despite the existing dead time. Of course, stable control of the EGR rate x can also be achieved using other control engineering measures. The values ​​provided by blocks 98 and 100 are either measured as actual values ​​or determined using a model and can be described as feedforward variables from a control engineering perspective.

[0054] Therefore, in Fig. 4 shows that the control variable m for the operation of the charging device 16 can be determined by means of the filling control 154 as a function of the first actual filling m. fg from the fresh air path and depending on the second actual filling level m agr is determined from the exhaust gas recirculation 24.

Claims

[1] A method for operating an internal combustion engine (2) wherein a filling actuator (10; 16) is arranged between an exhaust gas recirculation (24) and a combustion chamber (4) of the internal combustion engine (2), characterized by , that a control variable (m) for the operation of the filling device (10; 16) depending on a first actual filling (m fg ) from a fresh air path and depending on a second actual filling level (m agr ) is determined from the exhaust gas recirculation (24). [2] The method according to claim 1, wherein the controlled variable (m) is derived from the sum of the first actual filling (m fg ) and the second actual filling (m agr ). [3] The method according to claim 1 or 2, wherein a guide variable (m soll ) for the filling plate (10; 16) depending on a first target filling (m fg,soll ) of fresh air (31) and depending on a second target filling (m agr,soll ) is determined from the exhaust gas recirculation (24). [4] The method according to claim 3, wherein the guide variable (m soll ) from the sum of the first target filling (m fg,soll ) and the second target filling (m agr,soll ). [5] The method according to one of the preceding claims, wherein in an uncharged state (40) of the internal combustion engine (2) a throttle device (10) is operated as a filling controller with the control variable (m). [6] The method according to claim 5, wherein in the uncharged state (40) an exhaust gas recirculation actuator (26) depending on a preset value (ṁ agrv,soll ) for a mass flow from the exhaust gas recirculation (24), wherein the target value (ṁ agrv,soll ) for the mass flow from the exhaust gas recirculation (24) as a function of a first target exhaust gas recirculation rate (x vdk,soll ) is determined as a guide variable in a first feed section (6) before the throttle device (10), and wherein the first target exhaust gas recirculation rate (x vdk,soll) depending on a second target exhaust gas recirculation rate (x sr,soll ) is determined as a guide variable in a second feed section (8) after the throttle device (10). [7] The method according to claim 6, wherein in the uncharged state (40) the first target exhaust gas recirculation rate (x vdk,soll ) consisting of a rule component (x vdk,fb ) and an input tax component (X vdk,ff ) is composed, and where the second target exhaust gas recirculation rate (x sr,soll ) consisting of a rule component (x sr,fb ) and an input tax share (x sr,ff ) is composed of. [8] The method according to any one of claims 3 to 7, wherein in the uncharged state (40) the throttle device (10) depending on a preset value (ṁ dk,soll ) for the mass flow via the throttle device (10), wherein the setpoint value (ṁ dk,soll ) for the mass flow through the throttle device (10) as a function of a control component (ṁ dk,fb) and depending on an input tax share (m dk,ff ) is determined. [9] The method according to one of the preceding claims, wherein in a charged state (42) of the internal combustion engine (2) a charging device (16) is operated as a filling controller with the control variable (m). [10] The method according to claim 9, wherein in the charged state (42) an exhaust gas recirculation actuator (26) depending on a preset value (ṁ agrv,soll ) for the mass flow from the exhaust gas recirculation (24), and wherein the target value (ṁ agrv,soll ) for the mass flow from the exhaust gas recirculation (24) as a function of a target exhaust gas recirculation rate (x soll ) is determined as a key variable in a total volume (102). [11] The method according to claim 9 or 10, wherein in the charged state (42) an actual pressure (p) in the total volume (102) is determined as a function of the controlled variable (m), and wherein a target pressure (p) soll) in the total volume (102) depending on a reference variable (m soll ) for the charging device (16) is determined. [12] The method according to claim 10 or 11, wherein the default value (ṁ agfv,soll ) for the mass flow from the exhaust gas recirculation (24) consists of a control component (ṁ agrv,fb ) and an input tax component (ṁ agrv,ff ) is composed of. [13] A computer program for a digital computing device configured to perform a method according to any of the preceding claims. [14] A control unit (25) for operating an internal combustion engine (2) in particular a motor vehicle, which is equipped with a digital computing device in particular a microprocessor on which the computer program according to claim 13 is executable. [15] A storage medium for the control unit (25) according to claim 14, on which the computer program according to claim 13 is stored.

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