Internal combustion engine, method for operating the same and control device for carrying out the method
An internal combustion engine includes: plural cylinders, a first exhaust gas turbocharger having a high-pressure turbine and a high-pressure compressor, a second exhaust gas turbocharger having a low-pressure turbine and a low-pressure compressor, and an SCR catalytic converter positioned between the high-pressure turbine and the low-pressure turbine, via which exhaust gas leaving the high-pressure turbine is conducted upstream of the low-pressure turbine. The low-pressure compressor is assigned a power take-in, via which the low-pressure compressor can be driven when as a consequence of a relatively large exhaust gas temperature drop at the SCR catalytic converter via the low-pressure turbine an adequate amount of energy required to supply the cylinders of the internal combustion engine with a desired quantity of charge air can no longer be provided.
1. An internal combustion engine ( 10 ) comprising:
a plurality of cylinders ( 11 ), the cylinders producing exhaust gas ( 12 );
a first exhaust gas turbocharger ( 14 a ) including a high-pressure turbine ( 13 a ) and a high-pressure compressor ( 16 a );
a second exhaust gas turbocharger ( 14 b ) including a low-pressure turbine ( 13 b ) and a low-pressure compressor ( 16 b );
at least one exhaust gas aftertreatment device positioned between the high-pressure turbine ( 13 a ) and the low-pressure turbine ( 13 b ), the at least one exhaust gas aftertreatment device being at least one selected from the group of: a particle filter, a CO oxidation catalytic converter, CH 2 O oxidation catalytic converter, a CH 4 oxidation catalytic converter, and an SCR catalytic converter ( 17 ), the at least one exhaust gas aftertreatment device conducting all of the exhaust gas ( 12 ) produced by the cylinders ( 11 ), including any exhaust gas ( 12 ) leaving the high-pressure turbine ( 13 a ), downstream to the low-pressure turbine ( 13 b );
a first temperature sensor ( 18 ) arranged downstream of the high-pressure turbine ( 13 a ) and upstream of the at least one exhaust gas aftertreatment device;
a second temperature sensor ( 19 ) arranged downstream of the at least one exhaust gas aftertreatment device and upstream of the low-pressure turbine ( 13 a );
a power take-in ( 21 ) coupled to the low-pressure compressor ( 16 b ), the power take-in ( 21 ) being configured to provide extra energy to the low-pressure compressor ( 16 b ) in a case in which an exhaust gas temperature drop greater than a threshold amount occurs at the at least one exhaust gas aftertreatment device; and
a control device ( 20 ) configured to automatically determine and automatically adjust, based on a temperature difference between the temperature of the exhaust gas ( 12 ) measured at the first temperature sensor ( 18 ) and the temperature of the exhaust gas ( 12 ) measured at the second temperature sensor ( 19 ), the amount of extra energy provided at the power take-in ( 21 ) for driving the low-pressure compressor ( 16 b ), such that the greater the temperature drop and thus the energy loss along the at least one exhaust gas aftertreatment device, the more energy is fed to the power take-in ( 21 ) and thus to the low-pressure compressor ( 16 b ), so as to supply the cylinders ( 11 ) of the internal combustion engine ( 10 ) with an adequate amount of charge air.
2. The internal combustion engine according to claim 1 , further comprising a power take-out, coupled to the high-pressure turbine ( 13 a ), the power take-out ( 24 ) being configured to extract energy at the high-pressure turbine ( 13 a ) for driving the low-pressure compressor ( 16 b ).
3. The internal combustion engine according to claim 1 , wherein the power take-in ( 21 ) comprises an electric motor.
4. The internal combustion engine according to claim 2 , wherein the power take-out ( 24 ) comprises an electric machine having a generator that is configured to, when the high-pressure turbine ( 13 a ) provides more than a threshold amount of energy to the high-pressure compressor ( 16 a ), convert the excess energy into electric energy, wherein the electric energy is directly utilizable for driving the power take-in ( 21 ) and the low-pressure compressor ( 16 b ), and wherein the electric energy is utilizable to charge an electric energy storage unit.
5. The internal combustion engine according to claim 2 , wherein the power take-out ( 24 ) is mechanically coupled to the power take-in ( 21 ).
6. A method for operating an internal combustion engine ( 10 ) having a plurality of cylinders ( 11 ), the cylinders producing exhaust gas ( 12 ), a first exhaust gas turbocharger ( 14 a ) including a high-pressure turbine ( 13 a ) and a high-pressure compressor ( 16 a ), a second exhaust gas turbocharger ( 14 b ) including a low-pressure turbine ( 13 b ) and a low-pressure compressor ( 16 b ), at least one exhaust gas aftertreatment device positioned between the high-pressure turbine ( 13 a ) and the low-pressure turbine ( 13 b ), the at least one exhaust gas aftertreatment device being at least one selected from the group of: a particle filter, a CO oxidation catalytic converter, CH 2 O oxidation catalytic converter, a CH 4 oxidation catalytic converter, and an SCR catalytic converter ( 17 ), the at least one exhaust gas aftertreatment device conducting all of the exhaust gas ( 12 ), produced by the cylinders ( 11 ), including any exhaust gas ( 12 ) leaving the high-pressure turbine ( 13 a ), downstream to the low-pressure turbine ( 13 b ), and a power take-in ( 21 ) coupled to the low-pressure compressor ( 16 b ), the method comprising:
driving, with the power take-in ( 21 ), by providing extra energy to the low-pressure compressor ( 16 b ) in a case in which and exhaust gas temperature drop greater than a threshold amount occurs at the at least one exhaust gas aftertreatment device;
determining exhaust gas temperatures with a first temperature sensor ( 18 ) positioned downstream of the high-pressure turbine ( 13 a ) and upstream of the at least one exhaust gas aftertreatment device and with a second temperature sensor ( 19 ) positioned downstream of the at least one exhaust gas aftertreatment device and upstream of the low-pressure turbine ( 13 a ); and
depending upon a temperature difference between the temperature of the exhaust gas ( 12 ) at the first temperature sensor ( 18 ) and the temperature of the exhaust gas ( 12 ) at the second temperature sensor ( 19 ), automatically determining and automatically adjusting the amount of extra energy to be provided at the power take-in ( 21 ) for driving the low-pressure compressor ( 16 b ), such that the greater the temperature drop and thus the energy loss along the at least one exhaust gas aftertreatment device, the more energy is fed to the power take-in ( 21 ) and thus to the low-pressure compressor ( 16 b ), so as to supply the cylinders ( 11 ) of the internal combustion engine ( 10 ) with an adequate amount of charge air.
7. The method according to claim 6 , wherein at the high-pressure turbine ( 13 a ) energy for driving the power take-in ( 21 ) is extracted via a power take-out ( 24 ).
8. A control device ( 20 ) of an internal combustion engine ( 10 ), the control device ( 20 ) being configured to carry out the method according to claim 6 .