Control device for an internal combustion engine, internal combustion engine assembly including an internal combustion engine and a control device of this type, method for operating an internal combustion engine, and method for determining a component characteristic map

Abstract

A control device for an internal combustion engine includes: a flow path module which is configured for: receiving a specified value for a flow path parameter of a flow path of the internal combustion engine; and determining a control specification for a control element of the flow path depending on the specified value using at least one component characteristic map of at least one component of the flow path.

Claims

1. A control device for an internal combustion engine, the control device comprising: a flow path module which is configured for: receiving a specified value for a flow path parameter of a flow path of the internal combustion engine; and determining a control specification for a control element of the flow path, the control specification being determined depending on the specified value and being determined using at least one component characteristic map, the at least one component characteristic map being of at least one component of a bypass of the flow path, the bypass bypassing a high pressure turbine of an exhaust gas turbocharger upstream of a low pressure turbine of another exhaust gas turbocharger; and a higher-level control module that is configured for determining the specified value and for passing the specified value to the flow path module, the flow path module being further configured for delivering at least one feedback to the higher-level control module, wherein the at least one feedback is selected from at least one limiting value and at least one limiting curve.

2. The control device according to claim 1, wherein the control device is configured to control the control element using the control specification.

3. The control device according to claim 1, wherein the flow path module is configured for determining the control specification by way of a physical model of the flow path including the at least one component and the at least one component characteristic map subject to the specified value.

4. The control device according to claim 3, wherein the flow path module is configured for determining the control specification in that, along the flow path, a plurality of the flow path parameter are determined by way of the physical model and the at least one component characteristic map.

5. The control device according to claim 3, wherein the flow path module is configured for determining the control specification in that along the flow pathat least one of systematically against a flow direction and systematically with the flow direction of a medium flowing through the flow path during operation of the internal combustion enginea plurality of the flow path parameter are determined by way of the physical model and the at least one component characteristic map.

6. The control device according to claim 1, wherein the flow path module is configured for at least one of: receiving, as the specified value, a boost pressure value for a gas path as the flow path; and determining, as the control specification, a valve position for a flow valve in the flow path bypassing the high pressure turbine of the exhaust gas turbocharger.

7. The control device according to claim 1, wherein the flow path module is configured for at least one of: receiving, as the specified value, a boost pressure value for a gas path as the flow path; and determining, as the control specification, a valve position for a bypass valve in the bypass bypassing the high pressure turbine of the exhaust gas turbocharger.

8. The control device according to claim 1, wherein the at least one component characteristic map is a bypass valve characteristic map.

9. The control device according to claim 1, wherein the at least one component characteristic map: (a) is created from a plurality of measured values of the at least one component assigned to the at least one component characteristic map and is adapted to test bench data of the internal combustion engine including the at least one component; or (b) is obtained from a plurality of predetermined support points and test bench data of the internal combustion engine including the at least one component which is assigned to the at least one component characteristic map.

10. The control device according to claim 1, wherein the flow path module includes a controller which is configured for determining a regulating manipulated variable depending on the specified value, wherein the flow path module is configured for determining the control specification subject to the regulating manipulated variable.

11. The control device according to claim 1, wherein the flow path module is configured for: receiving at least one measured value that was measured in the flow path during operation of the internal combustion engine; and adapting the at least one component characteristic map depending on the at least one measured value.

12. An internal combustion engine arrangement, comprising: an internal combustion engine; and a control device, which includes: a flow path module which is configured for: receiving a specified value for a flow path parameter of a flow path of the internal combustion engine; and determining a control specification for a control element of the flow path, the control specification being determined depending on the specified value and being determined using at least one component characteristic map, the at least one component characteristic map being of at least one component of a bypass of the flow path, the bypass bypassing a high pressure turbine of an exhaust gas turbocharger upstream of a low pressure turbine of another exhaust gas turbocharger; and a higher-level control module that is configured for determining the specified value and for passing the specified value to the flow path module, the flow path module being further configured for delivering at least one feedback to the higher-level control module, wherein the at least one feedback is selected from at least one limiting value and at least one limiting curve.

13. A method for operating an internal combustion engine, the method comprising the steps of: receiving, by way of a flow path module of a control device of the internal combustion engine, a specified value for a flow path parameter of a flow path of the internal combustion engine; and determining, by way of the flow path module, a control specification for a control element of the flow path, the control specification being determined depending on the specified value and being determined using at least one component characteristic map, the at least one component characteristic map being of at least one component of a bypass of the flow path, the bypass bypassing a high pressure turbine of an exhaust gas turbocharger upstream of a low pressure turbine of another exhaust gas turbocharger, the control device including a higher-level control module that is configured for determining the specified value and for passing the specified value to the flow path module, the flow path module being configured for delivering at least one feedback to the higher-level control module, wherein the at least one feedback is selected from at least one limiting value and at least one limiting curve.

14. The method according to claim 13, wherein the at least one component characteristic map is: (a) created from a plurality of measured values of the at least one component assigned to the at least one component characteristic map and is adapted to test bench data of the internal combustion engine including the at least one component; or (b) established from a plurality of predetermined support points and test bench data of the internal combustion engine including the at least one component which is assigned to the at least one component characteristic map.

15. The method according to claim 13, wherein the control device is configured to control the control element using the control specification.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:

(2) FIG. 1 is a schematic representation of a design example of an internal combustion engine arrangement with an internal combustion engine and a design example of a control device;

(3) FIG. 2 is a schematic representation of a design example of the control device;

(4) FIG. 3 is a schematic representation of a first example of a method for operating the internal combustion engine;

(5) FIGS. 4A, 4B are a schematic representation of a second design example of a method for operating the internal combustion engine;

(6) FIG. 5 is a schematic representation of a third design example of a method for operating the internal combustion engine;

(7) FIG. 6 is a schematic representation of a first part of the method according to one of the FIG. 3, 4A, 4B, or 5; and

(8) FIGS. 7A, 7B are a schematic representation of a second part of the method according to one of the FIG. 3, 4A, 4B, or 5.

(9) Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate embodiments of the invention, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.

DETAILED DESCRIPTION OF THE INVENTION

(10) FIG. 1 provides a schematic representation of a design example of an internal combustion engine arrangement 1 with an internal combustion engine 3 and a design example of a control device 5. Control device 5 is operatively connected with internal combustion engine 3 in a manner not explicitly described here and is arranged to control internal combustion engine 3, in particular to regulate it.

(11) Internal combustion engine 3 has a flow path 7, in particular an air path 9 and an exhaust gas path 15 which is operatively connected with air path 9 via at least one exhaust gas turbocharger 11, 13. Air path 9 is arranged to supply combustion air to at least one combustion chamber 17 of internal combustion engine 3. Exhaust gas path 15 is arranged to remove exhaust gas from the at least one combustion chamber 17. Internal combustion engine 3 optionally has a plurality of combustion chambers 17, especially in the form of at least one cylinder bank. In particular, one design example of internal combustion engine 3 has a plurality of cylinder banks, in particular a first cylinder bank and a second cylinder bank. Internal combustion engine 3 is designed in particular, as a V-engine.

(12) In flow path 7, internal combustion engine 3 has, in particular, two low-pressure exhaust gas turbochargers 11, namely a first low-pressure exhaust gas turbocharger 11.1 and a second low-pressure exhaust gas turbocharger 11.2, which are arranged parallel to one another in terms of flow, and a high-pressure exhaust gas turbocharger 13, wherein, in particular, two partial air mass flows flowing parallel to one another through a low-pressure compressor 19 of low-pressure exhaust gas turbochargers 11, namely a first low-pressure compressor 19.1 and a second low-pressure compressor 19.2, are combined upstream of a high-pressure compressor 21 of high-pressure exhaust gas turbocharger 13, and wherein an exhaust gas mass flow passing through a high-pressure turbine 23 of the high-pressure exhaust gas turbocharger 13 branches downstream of high-pressure turbine 23 into two partial exhaust gas mass flows, passing through low-pressure turbines 25 of the low-pressure exhaust gas turbocharger 11, namely a first low-pressure turbine 25.1 and a second low-pressure turbine 25.2.

(13) Exhaust gas path 15 has a bypass path or bypass 27, bypassing high-pressure turbine 23, wherein a bypass path valve or bypass valve 29 is arranged in bypass 27. A position of bypass valve 29 can be used to adjust the proportion of exhaust gas mass flow passing through the bypass and at the same time, a boost pressure in air path 9.

(14) Throttle valve 31 is located in air path 9, downstream of high-pressure compressor 21.

(15) Moreover, located in air path 9, downstream of low-pressure compressor 19, is a low-pressure intercooler 33, in particular a first low-pressure intercooler 33.1 downstream of the first low-pressure compressor 19.1 and a second low-pressure intercooler 33.2 downstream of the second low-pressure compressor 19.2. Located downstream of high-pressure compressor 21, in particular downstream of throttle valve 31, is a high-pressure intercooler 35.

(16) In the context of the present technical teaching, a boost pressure is understood in particular to be the pressure that is present in air path 9 downstream of high-pressure intercooler 35 and upstream of combustion chamber 17, in particular upstream of an intake valve device 37.

(17) Control device 5 includes a flow path module 39 which is arranged to receive a specified value 41see in particular FIG. 2for a flow path parameter of flow path 7, in particular a boost pressure value for the boost pressure and a control specification 44 for a control element 40 of flow path 7, in particular bypass valve 29, depending on the specified value, using at least one component characteristic map of at least one component 42 of the flow path 7, in particular to adjust the flow path parameter to the specified value. Control device 5 is structured and arranged to control the control element 40 using the control specification 44.

(18) FIG. 2 shows a schematic representation of a design example of control device 5. In particular, control device 5 includes a higher-level control module 43, which is arranged to determine specified value 41 and deliver it to flow path module 39. Higher level control module 43 is arranged in particular to directly control internal combustion engine 3. Higher-level control module 43 is arranged in particular, for model-based predictive control of internal combustion engine 3. In particular, control module 43 calculates specified value 41, transfers it to flow path module 39, and receives control specification 44 from flow path module 39, which it then uses to control internal combustion engine 3.

(19) Flow path module 39 is optionally arranged to provide at least one feedback 45, selected from at least one limit value and at least one limiting curve, such as a pump characteristic curve or a valve limit stop, to the higher-level control module 43.

(20) FIG. 3 shows a schematic representation of a first design example of a method for operating internal combustion engine 3. Flow path module 39 is arranged in particular to calculate a high-pressure compressor target speed nHD_soll depending on a boost pressure value as the specified value 41 on the basis of at least one component characteristic map 46. Moreover, flow path module 39 is arranged to calculate a high-pressure compressor target capacity PHD_soll depending on the boost pressure value on the basis of at least one component characteristic map 46.

(21) Flow path module 39 is also arranged to calculate control specification 44, in particular as the valve position for bypass valve 29, depending on the high-pressure compressor target speed nHD_soll and/or the high-pressure compressor target capacity PHD_soll on the basis of at least one additional component characteristic map 48.

(22) In this first design example, the boost pressure value is used as specified value 41 for control of the boost pressure.

(23) FIGS. 4A, 4B show a schematic representation of a second design example of a method for operating internal combustion engine 3 by adjustment of the boost pressure in two designs.

(24) A first embodiment of the second design example is shown under FIG. 4A, in which a control deviation 47 of specified value 41which is set as the target boost pressurefrom an actual boost pressure 49 is input into a controller 51 which is designed as a boost pressure regulator, wherein a controller manipulated variable 53 calculated by controller 51 or boost pressure manipulated variable is used as a control manipulated variable for determining control specification 44. The boost pressure is thus adjusted directly to specified value 41.

(25) In FIG. 4B, a second embodiment of the second design example is shown, in which a pilot control variable 55 is calculated depending on the boost pressure value as the preset value 41 on the basis of the at least one component characteristic map 46, 48, wherein at the same time control deviation 47 calculated from specified value 41 and actual boost pressure 49 is supplied to additionally provided controller 51, wherein a differential regulating manipulated variable 57 is calculated by controller 51 as the regulating manipulated variable, which is offset against pilot control variable 55 in order to obtain control specification 44. In this way, differential control of the boost pressure is realized.

(26) FIG. 5 shows a schematic representation of a third design example of a method for operating internal combustion engine 3.

(27) In this third design example, flow path module 39 is arranged to calculate control specification 44 depending on a speed manipulated variable 61, calculated from high-pressure compressor target speed nHD_soll by a speed regulator 59, and optionally the high-pressure compressor target capacity PHD_soll, using the at least one additional component characteristic map 48.

(28) In particular, the high-pressure compressor target speed nHD_soll is limited to a maximum target speed nHD_max by a limiting element 63, wherein a limited target speed of 65 is obtained; from limited target speed 65 and an actual speed 67, a speed control deviation 69 is calculated, which is used as input variable in speed regulator 59. In an optional design, high-pressure compressor target capacity PHD_soll is also calculated for the purpose of calculating the control specification 44 with actual speed 67 and speed manipulated variable 61 in a first calculation element 71, from which an equivalent high-pressure compressor target capacity 73 is obtained. A monitoring element 66 is provided to prevent division by zero in first calculation element 71.

(29) FIG. 6 shows a schematic representation of the first part of the method according to one of FIG. 3, 4A, 4B, or 5.

(30) By way of a plurality of component characteristic maps, FIG. 6 explains in particular the calculation of the high-pressure compressor target speed nHD_soll and the high-pressure compressor target capacity PHD_soll depending on the boost pressure value as a default value of 41.

(31) The process described here and in FIGS. 7A, 7B is designed for an internal combustion engine 3, including two low-pressure exhaust gas turbochargers 11, wherein the partial air paths and partial exhaust gas paths assigned to them are designated as A-side and B-side according to a common nomenclature. Insofar as the calculations for the A-side and the B-side are equivalent, they will be explained only for the A-side by way of example. For the sake of simplicity, the illustration for the B-side is either not explicitly shown, or provided with deleted reference markings, wherein reference is made respectively to the explanation for the A-side. In particular, internal combustion engine 3 has the structure shown in FIG. 1. For a better understanding, the pressures and temperatures mentioned below are shown at the corresponding locations in FIG. 1.

(32) First, an air mass flow {dot over (m)}.sub.L,A on the A-side, an ambient pressure p0, an ambient temperature T0 and a low-pressure compressor speed nNDA are included in a first low-pressure compressor characteristic map 75, wherein depending on these input variables, a first air pressure p1A for the A-side downstream of first low-pressure compressor 19.1 and upstream of first low-pressure intercooler 33.1 is determined by way of first low-pressure compressor characteristic map 75. First low-pressure compressor characteristic map 75 includes assigned values for mass flow {dot over (m)}.sub.L,A across first low-pressure compressor 19.1, the low-pressure compressor speed nNDA, and a pressure ratio across first low-pressure compressor 19.1. Incorporated into a second low-pressure compressor characteristic map 77 are air mass flow {dot over (m)}.sub.L,A, ambient pressure p0, ambient temperature T0, low-pressure compressor speed nNDA and first air pressure p1A, wherein, depending on these input variables, a first air temperature T1A is determined for the A-side downstream of the first low-pressure compressor 19.1 and upstream of the first low-pressure intercooler 33.1 by way of the second low-pressure compressor characteristic map 77. Second low-pressure compressor characteristic map 77 includes assigned values for a degree of efficiency of first low-pressure compressor 19.1, mass flow {dot over (m)}.sub.L,A across first low-pressure compressor 19.1 and the low-pressure compressor speed nNDA of the first low-pressure compressor 19.1.

(33) First air pressure p1A and first air temperature T1A, together with air mass flow {dot over (m)}.sub.L,A, are incorporated into a first low-pressure intercooler characteristic map 79, from which a second air pressure p2A is determined on the A-side downstream of low-pressure intercooler 33.1. First air temperature TIA, air mass flow {dot over (m)}.sub.L,A and a temperature TK of a cooling circuit upstream of first low-pressure intercooler 33.1 are incorporated into a second low-pressure intercooler characteristic map 81, from which a second air temperature T2A is determined on the A-side downstream of low-pressure intercooler 33.1.

(34) In the context of the present technical teaching, the fact that a variable is determined from a characteristic map is understood in particular to mean that the corresponding variable is either read from the characteristic map or calculated depending on a value selected from the characteristic map.

(35) Similarly, a second air pressure p2B and a second air temperature T2B are calculated for the B-side. The same component characteristic maps can thereby be used that are used on the A-side, in particular if identical components are used. If, in particular with regard to their type, manufacturer or design, different components are used on the A-side on the one hand and the B-side on the other, different component characteristic maps respectively assigned to each component can also be used accordingly.

(36) In a second calculation element 83, second air pressure p2A on the A-side and second air pressure p2B on the B-side are calculated into a third air pressure p3 downstream of a union of the parallel air paths of the A-side and the B-side upstream of high-pressure compressor 21, in particular as an arithmetic mean value according to the following equation:

(37) $\begin{array}{cc}p3=\frac{1}{2}\left(p2A+p2B\right).& \left(1\right)\end{array}$

(38) In a third calculation element 85, second air temperature T2A on the A-side and second air temperature T2B on the B-side are calculated with the air mass flow {dot over (m)}.sub.L,A on the A-side and an air mass flow {dot over (m)}.sub.L,B on the B-side to a third air temperature T3 downstream of the union of the parallel air paths of the A-side and the B-side upstream of high-pressure compressor 21, in particular according to the following equation:

(39) $\begin{array}{cc}T3=\frac{1}{{\stackrel{.}{m}}_{L,A}+{\stackrel{.}{m}}_{L,B}}\left(T2A.Math.{\stackrel{}{m}}_{L,A}+T2B.Math.{\stackrel{}{m}}_{L,B}\right).& \left(2\right)\end{array}$

(40) To this point, the calculation is carried out systematically along the flow direction of the charge air.

(41) Another part of the calculation occurs systematically against the direction of flow of the charge air: a total air mass flow {dot over (m)}.sub.L, which results as the sum of the air mass flow {dot over (m)}.sub.L,A on the A-side and the air mass flow {dot over (m)}.sub.L,B on the B-side, as well as the boost pressure value as the default value 41, are incorporated into a high-pressure intercooler characteristic map 87, from which a fourth air pressure p4 downstream of throttle valve 31 and upstream of high-pressure intercooler 35 is determined. Fourth air pressure p4, together with the total air mass flow {dot over (m)}.sub.L are incorporated into a throttle valve characteristic map 89, from which a fifth air pressure p5 is determinednot to be confused with the boost pressure often referred to in the same way according to a convention; in the context of the present teaching, the designation only serves to ensure consistency in the numbering of the various pressure valuesdownstream of high-pressure compressor 21 and upstream of throttle valve 31. In the simplest case, however, it is also possible that fourth air pressure p4 and fifth air pressure p5 are equated if it is assumed that throttle valve 31 is always completely open during normal operation of internal combustion engine 3.

(42) Third air pressure p3, third air temperature T3, fifth air pressure p5 and total mass flow {dot over (m)}.sub.L are now incorporated in a first high-pressure compressor characteristic map 91, from which the high-pressure compressor target speed nHD_soll is determined. First high-pressure compressor characteristic map 91 includes assigned values for total mass flow {dot over (m)}.sub.L across high-pressure compressor 21, the speed of high-pressure compressor 21, and a pressure ratio across high-pressure compressor 21.

(43) Total air mass flow {dot over (m)}.sub.L, third air pressure p3, third air temperature T3, fifth air pressure p5 and actual speed 67 of high-pressure compressor 21 are incorporated into a second high-pressure compressor characteristic map 93, from which a fifth air temperature T5also designated as such for consistency reasonsis determined downstream of high-pressure compressor 21 and upstream of throttle valve 31. Second high-pressure compressor characteristic map 93 includes assigned values for a degree of efficiency of high-pressure compressor 21, total air mass flow {dot over (m)}.sub.L across high-pressure compressor 21 and the speed of high-pressure compressor 21.

(44) Third air temperature T3, fifth air temperature T5 and total air mass flow {dot over (m)}.sub.L are offset in a fourth calculation element 95 to high-pressure compressor target capacity PHD_soll, in particular according to the following equation:

(45) $\begin{array}{cc}\mathrm{PHD\_soll}={\stackrel{}{m}}_L\left(T_5-T_3\right)K_l\left(\frac{T_3+T_5}{2}\right),& \left(3\right)\end{array}$
with a characteristic curve K.sub.1 as a function of the mean value of T.sub.3 and T.sub.5.

(46) FIG. 7A, 7B show a schematic representation of a second part of the method according to one of FIG. 3, 4A, 4B, or 5.

(47) FIGS. 7A, 7B illustrate in particular the calculation of control specification 44 on the basis of high-pressure compressor target capacity PHD_soll and high-pressure compressor target speed nHD_soll obtained according to FIG. 6 with the help of a plurality of component characteristic maps.

(48) As shown in (a), a first exhaust gas temperature T6A and a first exhaust gas pressure p6A downstream of first low-pressure turbine 25.1, a second exhaust gas temperature T7A upstream of first low-pressure turbine 25.1, an exhaust gas mass flow {dot over (m)}.sub.g,A (always on the A-side), the low-pressure compressor speed nNDA, which is also the speed of first low-pressure turbine 25.1 of first exhaust gas turbocharger 11.1, and a first value of a second exhaust gas pressure p8 upstream of a branching into two partial exhaust gas paths of the A-side and the B-side, and downstream of a union of the partial exhaust gas flows on the one hand through bypass 27 and on the other hand through high-pressure turbine 23, are incorporated into a first low-pressure turbine characteristic map 97, from which a second value for second exhaust gas pressure p8 is determined. During the calculation, that is, during operation of the method, the second value for second exhaust gas pressure p8 is returned to first low-pressure turbine characteristic map 97 as the new first value; the calculation of the second exhaust gas pressure p8 is thus done iteratively.

(49) Second exhaust gas temperature T7A is calculated from a second low-pressure turbine characteristic map 99, into which first exhaust gas temperature T6A, first exhaust gas pressure p6A, second exhaust pressure p8 and low-pressure compressor speed nNDA are incorporated. Second exhaust gas temperature T7A is also calculated iteratively, since second exhaust gas pressure p8 is incorporated in its calculation, which in turn requires second exhaust gas temperature T7A for its calculation. In an analogous manner, a second exhaust gas temperature T7B is calculated for the B-side, optionally by way of the same second low-pressure turbine characteristic map 99.

(50) Second exhaust gas pressure p8, second exhaust gas temperature T7B for the B-side, a first exhaust gas pressure p6B for the B-side and low-pressure compressor speed nNDB of second exhaust gas turbocharger 11.2, which is also the speed of second low-pressure turbine 25.2, are incorporated into a third low-pressure turbine characteristic map 101, from which an exhaust mass flow {dot over (m)}.sub.g,B for the B-side is determined. Exhaust gas mass flow {dot over (m)}.sub.g,A for the A-side is calculated in a fifth calculation element 103 from a total exhaust mass flow {dot over (m)}.sub.g and the exhaust mass flow {dot over (m)}.sub.g,B for the B-side, in particular according to the following equation:

(51) $\begin{array}{cc}{\stackrel{}{m}}_{g,A}={\stackrel{}{m}}_g-{\stackrel{}{m}}_{g,B}.& \left(4\right)\end{array}$

(52) A third exhaust gas temperature T8 upstream of the branching into the two partial exhaust gas paths of the A-side and the B-side and downstream of the union of the partial exhaust gas flows on the one hand by way of bypass 27 and on the other hand by way of high-pressure turbine 23 is calculated in a sixth calculation element 105 depending on second exhaust gas temperature T7A for the A-side, second exhaust gas temperature T7B for the B-side, exhaust mass flow {dot over (m)}.sub.g,A for the A-side and the exhaust mass flow {dot over (m)}.sub.g,B for the B-side, in particular according to the following equation:

(53) $\begin{array}{cc}T8=\frac{1}{{\stackrel{.}{m}}_{g,A}+{\stackrel{.}{m}}_{g,B}}\left(T7A.Math.{\stackrel{}{m}}_{g,A}+T7B.Math.{\stackrel{}{m}}_{g,B}\right).& \left(5\right)\end{array}$

(54) As shown in (b), third exhaust pressure p8, a fourth exhaust pressure p9 and a measured fourth exhaust gas temperature T9 upstream of the branching into the partial exhaust gas flows on the one hand through bypass 27 and on the other hand through high-pressure turbine 23, and high-pressure compressor target speed nHD_soll are now input into a first high-pressure turbine characteristic map 107, from which an exhaust mass flow {dot over (m)}.sub.g,T is determined via high-pressure turbine 23. Exhaust gas mass flow {dot over (m)}.sub.g,T via high-pressure turbine 23 and total exhaust mass flow {dot over (m)}.sub.g are incorporated into a seventh calculation element 109, in which they are calculated to form an exhaust mass flow {dot over (m)}.sub.g,U through bypass 27, in particular according to the following equation:

(55) $\begin{array}{cc}{\stackrel{}{m}}_{g,U}={\stackrel{}{m}}_g-{\stackrel{}{m}}_{g,T}.& \left(6\right)\end{array}$

(56) Fourth exhaust gas pressure p9 is determined in an eighth calculation element 111 in a bisection method by comparing a high-pressure compressor actual capacity PHD_ist with the high-pressure compressor target capacity PHD_soll.

(57) Exhaust gas mass flow {dot over (m)}.sub.g,U through bypass 27, exhaust gas mass flow {dot over (m)}.sub.g,T through high-pressure turbine 23, third exhaust gas temperature T8 and fourth exhaust gas temperature T9 are incorporated into a ninth calculation element 113, in which a fifth exhaust gas temperature T10 is calculated immediately downstream of high-pressure turbine 23 and upstream of the union of the partial exhaust gas flows on the one hand through bypass 27 and on the other hand through high-pressure turbine 23, in particular according to the following equation:

(58) $\begin{array}{cc}T10=\frac{{\stackrel{.}{m}}_{g,T}}{{\stackrel{.}{m}}_{g,U}}\left(T8-T9\right)+T8.& \left(7\right)\end{array}$

(59) Fifth exhaust gas temperature T10, fourth exhaust gas temperature T9 and exhaust gas mass flow {dot over (m)}.sub.g,T through high-pressure turbine 23 are incorporated into a second high-pressure compressor characteristic map 115, from which the actual high-pressure compressor capacity is determined PHD_ist.

(60) From the eighth calculation element 111, a target mass flow {dot over (m)}.sub.g,U,soll is also obtained through bypass 27, which, together with fourth exhaust pressure p9, fourth exhaust gas temperature T9, and third exhaust pressure p8, is incorporated into a third high-pressure compressor characteristic map 117, from which control specification 44 is ultimately obtained.

(61) Insofar as the variables mentioned in particular in connection with FIGS. 6 and 7 are not determined from a characteristic map, calculated by way of a calculation element or otherwise explicitly determined, they are optionally specified by the higher-level control module 43, in particular as measured variables or as variables obtained from a model or a simulation.

(62) Insofar as variables are determined iteratively, a predetermined starting value is optionally specified for them at the beginning of the procedure, in particular by the higher-level control module 43. In particular, the corresponding variables are initialized with the respective predetermined starting value.

(63) While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.