DE102021200599A1 - Supercharger pressure adjustment method, engine layout and vehicle - Google Patents

Abstract

Method for setting the charging pressure of an internal combustion engine with an exhaust gas turbocharger, a low-pressure exhaust gas recirculation and an electrically driven charging device to support the build-up of a charging pressure, comprising:- removing an exhaust gas flow from the internal combustion engine after a turbine of the exhaust gas turbocharger and mixing it with a fresh air flow before a compressor of the exhaust gas turbocharger; - Determination of a scavenging gradient based on a back pressure generated by a turbine of the exhaust gas turbocharger on the internal combustion engine and a boost pressure for the internal combustion engine; - Determining whether the scavenging gradient is in a predetermined pressure range; - Setting the boost pressure by the electrically driven charging device around the scavenging gradient in the predetermined maintain pressure range.

Description

The invention relates to a method for adjusting the charge pressure of an internal combustion engine with an exhaust gas turbocharger, low-pressure exhaust gas recirculation and an electrically driven charging device to support the build-up of charge pressure, an engine arrangement for carrying out the charge pressure control method and a vehicle which includes the engine arrangement.

The consumption of internal combustion engines can be reduced enormously by consistently increasing the compression ratio. Here, for example, combustion processes according to Miller or combustion processes with low-pressure exhaust gas recirculation are used. These combustion processes require a high degree of supercharging in order to meet today's driving performance requirements. To achieve this degree of supercharging, supercharging concepts such as electrically driven compressors (EAV) or electrically assisted exhaust gas turbochargers (euATL) can be used. These are mostly driven electrically and generate additional boost pressure to the conventional exhaust gas turbocharger (ATL). Nowadays they are mostly used to improve the response behavior of the internal combustion engine and thus the acceleration behavior of the vehicle.

EP 2 006 516 A1 discloses a charging system for an internal combustion engine with an exhaust gas turbocharger. The exhaust gas turbocharger is connected to an electric machine (motor/generator) - or more generally to a drive/output - and is equipped with an exhaust gas turbine with adjustable guiding geometry. The charging pressure and the scavenging gradient can be controlled or regulated via the VTG position and the electrical power of the electric machine.

DE 10 2012 009 288 A1 discloses an internal combustion engine with an exhaust gas turbocharger with variable turbine geometry and an electrically operated compressor. The compressor is only switched on in transient operation and switched off again immediately. In switched-off operation, the compressor is bypassed as soon as a sufficient scavenging gradient can be achieved by the exhaust gas turbocharger itself.

DE 10 2009 053 354 A1 discloses a method for operating an internal combustion engine with an exhaust system and with a turbocharger for charging the charge air, with exhaust gas being removed from the exhaust system and fed to the charge air via an exhaust gas recirculation system. An actual value of a scavenging gradient of the internal combustion engine is used to regulate the turbocharger, with the turbocharger being regulated in such a way that the scavenging gradient corresponds to a specified target value. By adjusting the scavenging gradient, the method can keep the compressor of the turbocharger in a favorable operating range, with control being carried out via the ATL actuator. However, the process is not suitable for ensuring an optimized gasoline engine combustion process via electrical boosting of the charging.

If the electrical support for charging is regulated independently of the scavenging gradient, there is a risk that the electrical support will be too low and that the scavenging gradient will be too small. Furthermore, there is also the risk that the electrical support is unnecessarily large. If the static scavenging gradient is too high, there are no longer any significant advantages for the combustion process. Electrical energy would thus be consumed without generating an efficiency advantage for the internal combustion engine. This can lead to an increase in fuel consumption.

The object is therefore to provide an improved method for operating an internal combustion engine with an exhaust gas turbocharger and an electrically driven charging device to support the build-up of charging pressure. In particular, there is the task of setting a scavenging gradient for sufficient scavenging of the combustion chamber and thus the best possible engine efficiency, but at the same time not scavenging more than necessary, since this wastes valuable electrical energy and reduces the efficiency of the overall system.

This object is achieved by the method according to claim 1, the engine control unit according to claim 9 and the vehicle according to claim 10. Further advantageous refinements of the invention result from the dependent claims and the following description of preferred exemplary embodiments of the present invention.

• - Entnehmen eines Abgasstroms aus der Verbrennungskraftmaschine nach einer Turbine des Abgasturboladers und Beimischen zu einem Frischluftstrom vor einem Verdichter des Abgasturboladers;
• - Ermitteln eines Spülgefälles anhand eines von einer Turbine des Abgasturboladers erzeugten Drucks und eines Ladedrucks für die Verbrennungskraftmaschine;
• - Ermitteln, ob das Spülgefälle in einem vorbestimmten Druckbereich liegt;
• - Einstellen des Ladedrucks durch die elektrisch angetriebene Ladeeinrichtung, um das Spülgefälle in dem vorbestimmten Druckbereich zu halten.

A first aspect of the present invention relates to a method for setting the charge pressure of an internal combustion engine with an exhaust gas turbocharger, low-pressure exhaust gas recirculation and an electrically driven charging device to support the build-up of a charge pressure, comprising:

• - Removing an exhaust gas flow from the internal combustion engine after a turbine of the exhaust gas turbocharger and mixing it with a fresh air flow before a compressor of the exhaust gas turbocharger;
• - Determination of a scavenging gradient based on one generated by a turbine of the exhaust gas turbocharger Pressure and a boost pressure for the internal combustion engine;
• - Determining whether the scavenging drop is within a predetermined pressure range;
• - Adjusting the charging pressure by the electrically driven charging device in order to keep the scavenging gradient in the predetermined pressure range.

The electrically powered supercharger supports the turbine at low speeds to compress the air supplied via the engine intake. In addition to the dynamic support of charging, an electrically driven charging device also supports stationary gas exchange to a certain extent. Tests on the engine test bench have shown that this stationary support when using low-pressure exhaust gas recirculation (LP-EGR) can lead to a significant increase in the efficiency of the combustion engine. The LP EGR is used to reduce the tendency to knock in the engine's knock-limited operating range. This leads to better combustion center positions and thus to lower fuel consumption. In the range of low engine speeds and medium to high engine loads, the use of LP EGR causes the operating point of the exhaust gas turbocharger turbine to shift towards lower efficiencies. In addition to the lower exhaust gas enthalpy available in front of the turbine due to lower exhaust gas temperatures, this can lead to an unfavorable scavenging gradient over the engine/cylinders. The worsening scavenging gradient can ensure higher proportions of internally recirculated exhaust gas and thus reduce the knock-reducing effect of the LP EGR. This can be prevented by electrically assisting the charging by the electrically driven charging device. The efficiency-increasing effect of the LP EGR can be significantly increased in this way. In other words, the boost pressure control process can optimally implement this increase in efficiency when using LP EGR, with the gas exchange being supported by the regulated, electrically driven charging device. The electrically driven charging device can be designed as an electric motor of an electrically driven compressor (EAV) or as an electrically assisted exhaust gas turbocharger (euATL) or can include such a component.

In some embodiments, the predetermined pressure range of the flushing gradient can be in a positive pressure range from +25 mbar up to +100 mbar inclusive, preferably from +40 mbar up to +60 mbar inclusive. Engine tests have shown that when using LP-EGR to improve the center of combustion, it is crucial to keep the stationary scavenging gradient at each operating point in a positive pressure range of +25 mbar to +100 mbar, despite the adjustment of the LP-EGR with the help of the electrical support of the charging mbar, preferably between +40 mbar and +60 mbar. For this purpose, the regulation of the EAV or the euATL can be integrated into the charging pressure regulation of the combustion engine in such a way that the electrical support is regulated in an operating state in such a way that the stationary scavenging gradient remains within the limits described above.

In some embodiments, the internal combustion engine may be an Otto engine.

In the Otto engine, an air-petrol mixture is sucked in, compressed in a piston and ignited by a spark plug. This creates a small explosion that pushes the piston back and causes movement. The petrol engine has the advantage that it is light and runs very smoothly.

In some embodiments, the exhaust gas turbocharger can be an electrically assisted exhaust gas turbocharger and can include an electric machine that corresponds to the electrically driven charging device. By supporting the electric machine of the exhaust gas turbocharger, an additional torque can be generated, as a result of which the scavenging gradient can be kept within the specified pressure range.

• - Einstellen eines Drehmoments der elektrischen Maschine anhand des Spülgefälles und eines gewünschten Spülgefälles;
• - Addieren des Drehmoments der elektrische Maschine zu einem Drehmoment des Abgasturboladers. Durch die Einstellung des Drehmoments der elektrischen Maschine in Abhängigkeit vom Spülgefälle kann die elektrische Unterstützung so bestimmt werden, dass das Spülgefälle nicht zu gering oder unnötig hoch wird. Durch das zusätzliche Drehmoment kann das Spülgefälle in dem vorgegebenen Druckbereich gehalten werden.

In some embodiments, the boost control method may further include:

• - Setting a torque of the electric machine based on the scavenging gradient and a desired scavenging gradient;
• - Adding the torque of the electric machine to a torque of the exhaust gas turbocharger. By adjusting the torque of the electrical machine as a function of the scavenging gradient, the electrical support can be determined in such a way that the scavenging gradient is not too low or unnecessarily high. Due to the additional torque, the scavenging gradient can be kept within the specified pressure range.

In some embodiments, the electrically powered charging device may be an electric machine of an electrically powered compressor. By controlling the electrical machine of the electrically driven compressor, an additional pressure build-up can be generated, as a result of which the scavenging gradient can be kept within the specified pressure range. The pressure build-up to be provided by the compressor of the turbocharger can thus be reduced and the turbine of the ATL thus relieved. In this way, the scavenging gradient can be kept within the specified pressure range.

• - Einstellen einer Drehzahl des elektrisch angetriebenen Verdichters anhand des Spülgefälles und eines gewünschten Spülgefälles. Durch die Einstellung der Drehzahl der elektrischen Maschine in Abhängigkeit vom Spülgefälle kann die elektrische Unterstützung so bestimmt werden, dass das Spülgefälle nicht zu gering oder unnötig hoch wird.

In some embodiments, the boost control method may further include:

• - Setting a speed of the electrically driven compressor based on the scavenging gradient and a desired scavenging gradient. By adjusting the speed of the electric machine as a function of the scavenging gradient, the electrical support can be determined in such a way that the scavenging gradient is not too low or unnecessarily high.

In some embodiments, the exhaust gas turbocharger can be a variable turbine geometry (VTG) charger. An exhaust gas turbocharger with variable turbine geometry has an adjustable turbine geometry. Movable guide vanes are arranged around the turbine wheel and can be adjusted via an adjusting ring in order to suitably change the flow cross-section of the turbine. The rotatable guide vanes change the inflow behavior and thus the performance of the turbine. In this way, the entire exhaust gas energy can be used and the flow cross section of the turbine can be optimally adjusted for each operating point.

A second aspect relates to an engine arrangement comprising an engine control unit which is set up to carry out a method according to one of the preceding embodiments. The engine control unit can receive requests from the internal combustion engine, process them and send corresponding signals to actuators. Actuators can be electric motors or electromagnetic valves that are responsible for converting the signals from the control unit into a specific action.

A third aspect relates to a vehicle having the foregoing engine arrangement. The engine arrangement can enable precise central control of the vehicle's functions relevant to engine operation.

• 1 als ein Ausführungsbeispiel ein Fahrzeug mit einer Verbrennungskraftmaschine und einem elektrisch unterstützten Abgasturbolader;
• 2 als ein Ausführungsbeispiel einen Regelkreis für die Ladedruckregelung und Regelung des elektrischen Maschinendrehmoments der elektrischen Maschine des elektrisch unterstützten Abgasturboladers;
• 3a einen beispielhaften zeitlichen Verlauf des Einregelns des Öffnungswinkels der Leitschaufeln der Turbine;
• 3b einen beispielhaften zeitlichen Verlauf des IST-Drehmomentes der Verbrennungskraftmaschine;
• 3c einen beispielhaften zeitlichen Verlauf des Spülgefälles;
• 3d einen beispielhaften zeitlichen Verlauf des Einregelns des IST-Drehmomentes (M_el,ist,euATL) der elektrischen Maschine;
• 4 als ein Ausführungsbeispiel ein Fahrzeug mit einer Verbrennungskraftmaschine und einem elektrisch angetriebene Verdichter (EAV);
• 5 als ein Ausführungsbeispiel einen Regelkreis für die Ladedruckregelung und Drehzahlregelung der elektrischen Maschine des elektrisch angetriebenen Verdichters (EAV);
• 6a einen beispielhaften zeitlichen Verlauf des Einregelns des Öffnungswinkels der Leitschaufeln der Turbine;
• 6b einen beispielhaften zeitlichen Verlauf des IST-Drehmomentes der Verbrennungskraftmaschine;
• 6c einen beispielhaften zeitlichen Verlauf des Spülgefälles;
• 6d einen beispielhaften zeitlichen Verlauf des Einregelns der Drehzahl der elektrischen Maschine des EAV; und
• 7 als ein Ausführungsbeispiel, ein Fahrzeug mit einer Motoranordnung.

Embodiments of the invention will now be described by way of example and with reference to the accompanying drawings. It shows:

• 1 as an exemplary embodiment, a vehicle with an internal combustion engine and an electrically assisted exhaust gas turbocharger;
• 2 as an exemplary embodiment, a control loop for charge pressure control and control of the electric machine torque of the electric machine of the electrically assisted exhaust gas turbocharger;
• 3a an exemplary time profile of the adjustment of the opening angle of the guide vanes of the turbine;
• 3b an exemplary time profile of the actual torque of the internal combustion engine;
• 3c an example of the scavenging gradient over time;
• 3d an exemplary time profile of the adjustment of the ACTUAL torque (M _{el,actual,euATL} ) of the electrical machine;
• 4 as one embodiment, a vehicle having an internal combustion engine and an electrically powered compressor (EAV);
• 5 as an exemplary embodiment, a control loop for the boost pressure control and speed control of the electrical machine of the electrically driven compressor (EAV);
• 6a an exemplary time profile of the adjustment of the opening angle of the guide vanes of the turbine;
• 6b an exemplary time profile of the actual torque of the internal combustion engine;
• 6c an example of the scavenging gradient over time;
• 6d an exemplary time course of adjusting the speed of the electrical machine of the EPC; and
• 7 as one embodiment, a vehicle having an engine assembly.

1 shows a vehicle with an internal combustion engine and an electrically assisted exhaust gas turbocharger (euATL) as an exemplary embodiment. Vehicle 100 includes an internal combustion engine 101, an electrically assisted exhaust gas turbocharger (euATL) 102, an intercooler 103, a throttle valve 104 and a low-pressure exhaust gas recirculation system 105.

Internal combustion engine 101 can be a spark-ignition engine, in which case the spark-ignition engine can be used in partially electrified vehicles. The internal combustion engine 101 is driven by the combustion of a fuel-air mixture. The internal combustion engine 101 includes a piston, a cylinder, an intake valve, an exhaust valve, a fuel injector, and a spark plug. The energy conversion takes place here according to the four-stroke principle.

The electrically assisted exhaust gas turbocharger (euATL) 102 includes a turbine 102-1 and a compressor 102-3. The turbine 102-1 uses the energy (thermal energy, ie heat energy, sometimes also kinetic energy, ie kinetic energy) of the exiting exhaust gases of the internal combustion engine 101 and is connected to the compressor 102-3. The compressor 102-3 is driven by the turbine 102-1 101, which increases the air throughput and reduces the suction work of the pistons. The electrically assisted exhaust gas turbocharger (euATL) 102 may further include a bypass valve (wastegate) in the exhaust flow to regulate boost pressure. Further, the turbine 102-1 may include variable vanes. Due to the adjustable guide vanes, the inflowing gas can be given a higher angular momentum (in the form of a higher tangential velocity) at low flow velocities. The opening angle of the guide vanes can be regulated in such a way that, when the gas throughput is low, the exhaust gas is accelerated tangentially through reduced flow cross-sections and directed onto the adjustable guide vanes, which increases the speed of the turbine and thus the output of the compressor. Conversely, with a high gas throughput, the flow velocity can be reduced by large flow cross sections. Furthermore, the electrically assisted exhaust gas turbocharger (euATL) 102 includes an electric machine 102-2. The electrically assisted exhaust gas turbocharger (euATL) 102 can additionally be accelerated with regulated torque by the electric machine 102-2. In the case of stationary support, an additional torque can also be applied permanently. The electrical machine 102-2 can be arranged on the drive shaft 102-4 between the turbine 102-1 and the compressor 102-3 or also at a shaft end following the turbine 102-1 or the compressor 102-3. By means of the supplied electrical energy, additional charge pressure can be made available to increase the charge pressure of the conventional exhaust gas turbocharger.

The intercooler 103 serves as a heat exchanger that reduces the temperature of the combustion air fed into the intake tract of a supercharged internal combustion engine 101 . It can be installed in the intake tract between the compressor 102-3 and the intake valve of the internal combustion engine 101 and dissipates some of the heat that is generated during the compression of the air in the euATL 102. This increases the power and efficiency of the internal combustion engine 101. By lowering the temperature of the air supplied, a larger air mass is produced in the same volume, so that proportionally more fuel can be burned.

Throttle valve 104 is located in the intake tract of internal combustion engine 101. Throttle valve 104 regulates the air supply for internal combustion engine 101.

The exhaust gas of the internal combustion engine 101 is expanded via the turbine 102-1 of the euATL 102 and the compressor 102-3 of the euATL 102 is driven via the common shaft 102-4. The electric machine 102-2 is located on the shaft 102-4 of the euATL 102 and can electrically support the generation of the charging pressure. After compression in the compressor 102 - 3 of the euATL 102 , the fresh air is supplied to the internal combustion engine 101 via the intercooler 103 and the throttle valve 104 .

The low-pressure EGR 105 includes an EGR valve 105-1 and an EGR cooler 105-2. The low-pressure exhaust gas recirculation (LP-EGR) 105 serves to reduce the tendency to knock in the knock-limited operating range of the internal combustion engine 101. This leads to better combustion center positions and thus to lower fuel consumption. In the range of low engine speeds and medium to high engine loads, the use of LP EGR results in the operating point of the exhaust gas turbocharger turbine being shifted to lower levels of efficiency. In addition to the lower available exhaust gas enthalpy upstream of turbine 102-1 due to lower exhaust gas temperatures, this leads to a worsening scavenging gradient over internal combustion engine 101. The worsening scavenging gradient ensures higher proportions of internally recirculated exhaust gas and thus reduces the knock-reducing effect of the LP EGR 105. This can be prevented by electrically assisting charging with an euATL 102. The efficiency-increasing effect of the LP EGR can be significantly increased in this way. In order to ideally implement this increase in efficiency, in 2 a method for controlling the gas exchange support when using LP-EGR 104 by an euATL 102 is described.

2 shows, as an exemplary embodiment, a control circuit for controlling the boost pressure and controlling the electric machine torque of the electric machine (102-2 in 1 ) of the electrically assisted exhaust gas turbocharger (102 in 1 ). The control circuit 200 includes a boost pressure controller 210, a euATL 220 speed controller, variable turbine geometry supercharger (VTG) controller 230, a euATL turbine 240 (102-1 in 1 ), a euATL shaft 250 (102-4 in 1 ), a euATL compressor 260 (102-3 in 1 ), an internal combustion engine 270 (101 in 1 ), an electric machine 280 (102-2 in 1 ) and an electric machine controller 290.

The wastegate 210 determines the euATL compressor (102-3 in 2 ) target boost pressure Π _{to be} provided based on the pressure P _1, act before the euATL compressor (102-3 in 2 ) and the difference between the internal combustion engine setpoint torque M _VKM,soll and the internal combustion engine actual torque M _VKM, actual. The speed controller of the euATL 220 _sets the target speed n set _{, euATL} of the euATL on the basis of the target boost pressure Π target _, taking into account the actual boost pressure Π actual . From the relation between the actual speed n _ist,euATL and the target speed n _soll , _euATL of the euATL, the VTG controller 230 determines how the position of the variable guide vanes in front of the turbine VTG adjust , of the _euATL (102 in 1 ) is to be set. Depending on the position of the guide vanes VTG adjust , the turbine 240 of the _euATL generates a specific torque M _th,euATL on the shaft 250 of the euATL, which drives the compressor 260 of the euATL. Depending on the friction and the gas forces in the compressor 260, this torque M _th,euATL results in an actual speed nactual, _euATL of the compressor 260 and thus a specific compressor pressure ratio _Πactual . Depending on the set position of the guide vanes of the turbine VTG _adjust and thus the build-up behavior of the euATL turbine 240, a counter-pressure P _3, actual now occurs on the internal combustion engine 270. The scavenging gradient (ΔP _{rinsing,actual} = P _2, actual - P _{3,actual ) is} calculated from the back pressure P _3, actual and the charging pressure P _2, actual . The controller 290 of the electrical machine of the euATL determines the electric setpoint torque M _{el,soll,euATL to be} applied to the shaft of the euATL from the difference between the actual scavenging gradient ΔP _{spül,act and} the desired setpoint scavenging gradient ΔP _spül, setpoint. The electrical setpoint torque M _el,sol,euATL is compared to the actual electrical torque M _{el,actual,euATL} . Within the e-machine of the euATL 280, the actual torque M el,actual, _{euATL is} regulated to the target torque M _{el,soll,euATL} . If the scavenging gradient ΔP _{spül,ist is} too low, the electric setpoint torque M _{el,soll,euATL} is increased and if the scavenging gradient ΔP _{spül,ist is} too high, the setpoint torque M _{el,soll,euATL is} reduced. An increased torque M _th,euATL on the shaft now leads to an increased shaft speed n _ist,euATL , which, however, is detected by the speed controller 220 of the euATL and is compensated by opening the guide vanes of the turbine, i.e. an increase in the position value VTG _stell . With a large opening angle of the guide vanes of the turbine, the back pressure P _3, actual on the internal combustion engine 270 is lowered, which leads to a desired increase in the scavenging gradient ΔP _spül,actual .

The control circuit 200 with an euATL enables the conversion of the flushing gradient ΔP _{flush, is} in the positive range of +25 mbar to +100 mbar, preferably between +40 mbar and +60 mbar.

3 shows an example of how the opening angle (VTG _adjust ) of the guide vanes of the turbine (102-1 in 1 ), the ACTUAL torque (M _VKM, actual ) of the internal combustion engine (101 in 1 ), the scavenging gradient (ΔP _spül,ist ) and the adjustment of the ACTUAL torque (M _el,ist,euATL ) of the electrical machine (102-2 in 1 ).

The x-axis of 3a corresponds to the time axis, and the y-axis of 3a corresponds to the opening angle (VTG _stell ) of the adjustable guide vanes of the turbine. The x-axis of 3b corresponds to the time axis, and the y-axis of 3b corresponds to the actual torque (M _{el,actual,euATL} ) of the internal combustion engine. The x-axis of 3c corresponds to the time axis, and the y-axis of 3c corresponds to the flushing gradient (ΔP _{flush, actual} ). The x-axis of 3d corresponds to the time axis, and the y-axis of 3d corresponds to the setpoint torque (M _{el,soll,euATL} ) of the electrical machine.

First, by closing the VTG, the ACTUAL torque (solid line in 3b) to the target torque (dashed line in 3b) the internal combustion engine is set or regulated. The ACTUAL flushing gradient (solid line in 3c ) below the target flushing gradient (dashed line in 3c ). At time T1, the electric machine of the euATL provides a support torque (solid line in 3d ) on the wave of the euATL. The turbine's adjustable guide vanes are opened further until the target scavenging gradient is reached. Time T1 can be determined when a differential value between the ACTUAL scavenging gradient and the target scavenging gradient is less than a predetermined value. In other words, the support torque can be applied to the euATL shaft when a difference between the actual scavenging gradient and the target scavenging gradient is less than a predetermined value.

4 FIG. 1 shows a vehicle with an internal combustion engine and an electrically driven compressor (EAV) as an exemplary embodiment. The same components of the vehicle 400 and the vehicle in 1 have been denoted by the same reference numerals. In order to avoid redundant information and to improve readability, the explanations for components with the same reference numbers in 1 and 4 omitted.

The vehicle 400 includes an exhaust gas turbocharger (ATL) 410, wherein the exhaust gas turbocharger 410 includes a turbine 102-1 and a compressor 102-3. The vehicle 400 also includes an EAV 420 and a bypass flap 430. The EAV 420 includes an EAV compressor 420-1 and an electric machine 420-2, the speed of the EAV compressor 420-1 being controlled by the electric machine 420-2. The EAV 420 can be arranged in the charge air path of the internal combustion engine 101 and can act either before or after the compressor 102 - 3 of the exhaust gas turbocharger 410 as seen in the direction of flow. The EAV 420 is used to provide dynamic support and/or stationary support when building up the boost pressure - especially in the low engine speed ranges (E-Boost mode).

The exhaust gas of internal combustion engine 101 is expanded via turbine 102-1 of turbocharger 410 and compressor 102-3 of turbocharger 410 is driven via the common shaft. After compression in compressor 102 - 3 of ETC 410 , the fresh air is supplied to EAV 420 . After the additional compression by EAV 420 , the fresh air is supplied to internal combustion engine 101 via intercooler 103 and throttle valve 104 . The EAV 420 can be bypassed via the bypass flap 430 if no additional boost pressure build-up by the EAV 420 is necessary.

5 shows, as an exemplary embodiment, a control circuit for charge pressure control and speed control of the electric machine (420-2 in 4 ) of the electrically driven compressor (EAV) (420 in 4 ). Control loop 500 includes boost pressure controller 510, EPC speed controller 520, variable turbine geometry charger (VTG) controller 530, turbocharger 540 (410in 4 ), an internal combustion engine 550 (101 in 4 ), an EAV 560 (420 in 4 ).

The boost pressure controller 510 determines the total pressure ratio Π _{tot to be} provided, set on the basis of the pressure P _1, act upstream of the compressor (102-3 in 4 ) and the difference between the internal combustion engine setpoint torque M _VKM,soll and the internal combustion engine actual torque M _VKM, actual. Taking into account the actual pressure ratio Π _tot, actual, the VTG controller 530 now sets the position VTG _adjust of the adjustable guide vanes of the turbine. Depending on the position of the vanes of the turbine VTG _adjust , the turbine of the ATL 540 generates mechanical power, with which the compressor of the ATL 540 is driven via the common shaft and the boost pressure Π _ATL for the internal combustion engine 550 is generated. Depending on the set position of the guide vanes of the turbine VTG _adjust and thus the damming behavior of the turbine of the ATL 540, a back pressure P _3, actual arises on the internal combustion engine. The scavenging gradient (ΔP _{rinsing,actual} = P _2, actual - P _{3,actual ) is} calculated from the back pressure P _3, actual and the charging pressure P _2, actual . The speed controller 520 of the EAV determines the required speed n _EAV of the EAV 560 from the difference between the actual scavenging gradient ΔP _spül,ist and the desired setpoint scavenging gradient ΔP _spül,ist. If the scavenging gradient ΔP _spül,is too low, the speed n _EAV of the EAV is increased and the flushing gradient ΔP _{flush is} too high, the speed of the EAV n _EAV is reduced. An increased speed n _EAV of the EAV now leads to an increased total pressure ratio Π _tot,actual , which, however, is detected by the VTG controller 530 of the turbocharger and is compensated for by a greater opening of the guide vanes of the turbine, i.e. a larger value of the manipulated variable VTG _adjust . By opening the guide vanes of the turbine, the back pressure P _3, actual on the internal combustion engine 550 is lowered, which leads to a desired increase in the scavenging gradient ΔP _spül,actual .

The control circuit 500 with an EAV enables the conversion of the flushing gradient ΔP _{flushing, is} in the positive pressure range from +25 mbar to +100 mbar, preferably between +40 mbar and +60 mbar.

6 shows an example of how the opening angle (VTG _adjust ) of the guide vanes of the turbine (102-1 in 4 ), the ACTUAL torque (M _VKM, actual ) of the internal combustion engine (101 in 4 ), the scavenging gradient (ΔP _spül,ist ) and the adjustment of the speed (n _EAV ) of the electrical machine of the EAV (420-2 in 4 ).

The x-axis of 6a corresponds to the time axis, and the y-axis of 6a corresponds to the opening angle (VTG _stell ) of the adjustable guide vanes of the turbine. The x-axis of 6b corresponds to the time axis, and the y-axis of 6b corresponds to the ACTUAL torque (M _VKM, actual) of the internal combustion engine. The x-axis of 6c corresponds to the time axis, and the y-axis of 6c corresponds to the flushing gradient (ΔP _{flush, actual} ). The x-axis of 6d corresponds to the time axis, and the y-axis of 6d corresponds to the speed of the EAV (n _EAV )) of the electrical machine of the EAV.

First, by closing the VTG, the ACTUAL torque (solid line in 6b) to the target torque (dashed line in 6b) the internal combustion engine is set or regulated. The ACTUAL flushing gradient (solid line in 6c ) below the target flushing gradient (dashed line in 6c ). At time T1, the speed of the EAV is increased. The compressor's adjustable guide vanes are opened further in order to reduce the charge pressure increased by the EPC. In this way, the target scavenging gradient is regulated via the EAV speed. Time T1 can be determined when a difference between the actual scavenging gradient and the target scavenging gradient is less than a predetermined value is. In other words, the speed of the EAV can be increased if a difference between the actual scavenging gradient and the target scavenging gradient is less than a predetermined value.

7 12 shows, as one embodiment, a vehicle having an engine assembly. The engine assembly 710 includes an engine controller 720, an internal combustion engine (101 in 1 or 4 ). The engine control unit 720 is designed to follow the control loop for the boost pressure control 2 or 5 to perform.

Reference List

100

vehicle

101

internal combustion engine

102

electrically assisted exhaust gas turbocharger

102-1

turbine

102-2

electric machine

102-3

compressor

102-4

euATL wave

103

intercooler

104

throttle

105

Low-pressure exhaust gas recirculation

200

control loop

210

boost pressure regulator

220

euATL speed controller

230

Variable Turbine Geometry Supercharger (VTG) governor

240

euATL turbine

250

euATL wave

260

euATL compressor

270

internal combustion engine

280

electric machine

290

electric-machine controller

400

vehicle

410

exhaust gas turbocharger

420

electrically driven compressors

420-1

EAV compressor

420-2

electric machine

430

bypass damper

500

control loop

510

boost pressure regulator

520

Speed controller of the EAV

530

VTG controller

540

ATL turbine

550

internal combustion engine

560

EAV

700

vehicle

710

engine arrangement

720

engine control unit

Πshould

Target boost pressure

Πis

Actual boost pressure

Πtot

overall pressure ratio

Πtot,is

actual pressure ratio

P1,is

Pressure before the euATL compressor

P2,is

boost pressure

P3,is

back pressure

ΔPrinse,is

actual flushing gradient

ΔPrinse,set

Target flush gradient

MVKM, target

Internal combustion engine target torque

MVKM,is

Internal combustion engine actual torque

Mel,sol,euATL

Target torque of the electric machine

Mel,ist,euATL

ACTUAL torque of the electrical machine

Mth,euATL

torque of the euATL

nsoll,euATL

Target speed of the euATL

nist, euATL

Actual speed of the euATL/compressor pressure ratio

nist,euATL

Actual speed of the euATL compressor

nEAV

speed of the EAV

VTG deputy

Variable Turbine Geometry

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• EP 2006516 A1 [0003]
• DE 102012009288 A1 [0004]
• DE 102009053354 A1 [0005]

Claims (10)

Method for setting the charging pressure of an internal combustion engine (101) with an exhaust gas turbocharger (102; 410), a low-pressure exhaust gas recirculation (105) and an electrically driven charging device (102-2; 420-2) to support the build-up of a charging pressure (P _2, actual ) , comprising: - removing an exhaust gas flow from the internal combustion engine (101) after a turbine (102-1) of the exhaust gas turbocharger (102; 410) and mixing it into a fresh air flow before a compressor (102-3) of the exhaust gas turbocharger (102; 410); - Determining a scavenging gradient (ΔP _{rinsing, actual} ) based on a back pressure (P _3, actual ) generated by a turbine of the exhaust gas turbocharger on the internal combustion engine (101) and a boost pressure (P _2, actual ) for the internal combustion engine (101); - Determining whether the flushing gradient (ΔP _{flush,actual) is} in a predetermined pressure range; - Adjusting the charging pressure (P _2, actual) by the electrically driven charging device (102-2; 420-2) in order to keep the scavenging drop (ΔP _spül,actual ) in the predetermined pressure range. Boost pressure control procedure claim 1 , wherein the predetermined pressure range is in a positive pressure range from +25 mbar up to +100 mbar inclusive, preferably from +40 mbar up to +60 mbar inclusive. Boost pressure control procedure claim 1 or 2 , wherein the internal combustion engine (101) is an Otto engine. Boost pressure control method according to one of Claims 1 until 3 , wherein the exhaust gas turbocharger (102) is an electrically assisted exhaust gas turbocharger (euATL) and comprises an electric machine (102-2) which corresponds to the electrically driven charging device (102-2; 420-2). Boost pressure control procedure claim 4 , further comprising: - setting a torque (M _{el,actual,euATL} ) of the electric machine (102-2) based on the scavenging gradient (ΔP _{rinsing,actual} ) and a desired scavenging gradient (ΔP _{rinsing,setpoint} ); - Adding the torque (M _{el, ist, euATL} ) of the electric machine (102-2) to a torque (M _{th, euATL} ) of the exhaust gas turbocharger (102). Boost pressure control method according to one of Claims 1 until 3 , wherein the electrically driven charging device (102-2; 420-2) is an electric machine (420-2) of an electrically driven compressor (420). Boost pressure control procedure claim 6 , further comprising: - setting a speed (n _EAV ) of the electrically driven compressor (420) based on the scavenging gradient (ΔP _{rinsing, actual} ) and a desired scavenging gradient (ΔP _{rinsing, target} ). Boost pressure control method according to one of Claims 1 until 7 , wherein the exhaust gas turbocharger (102; 410) is a variable turbine geometry charger. Engine assembly comprising an engine control unit (720), which is adapted to a method according to one of Claims 1 until 8th to perform. Vehicle (100; 400; 700) having an engine assembly according to claim 9 .

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