System and method for a supercharged internal combustion engine with exhaust gas recirculation

Abstract

The present invention relates to a system and method for a supercharged internal combustion engine with exhaust gas recirculation. A method and system for a supercharged internal combustion engine with a staged boost device are provided. In one example, the system includes: an engine, which is connected to an intake system for receiving pressurized air and an exhaust system for discharging exhaust gas; an electrically driven compressor, which is arranged in the intake system upstream of a turbocharger compressor; a bypass line including a bypass valve, which is connected to both ends of the electrically driven compressor; a throttle, which is arranged at the inlet of the electrically driven compressor; and an exhaust gas recirculation system, which connects the exhaust system downstream of the exhaust turbine to the intake system upstream of the electrically driven compressor via a first recirculation branch and is connected between the electrically driven compressor and the turbocharger compressor via a second recirculation branch. In this way, the electrically driven compressor can be operated to reduce the formation of condensate at the inlet of the turbocharger compressor.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of German Patent Application No. 102017210962.9 filed on Jun. 28, 2017. The entire contents of the above-mentioned application are incorporated herein by reference in their entirety for all purposes. Technical Field

[0003] The present invention generally relates to methods and systems for a supercharged internal combustion engine having a staged boost arrangement. Background Art

[0004] The internal combustion engine can be used as a motor vehicle drive. The expression "internal combustion engine" covers diesel engines, Otto cycle (e.g. spark ignition) engines, but also hybrid internal combustion engines using a mixed combustion process, and hybrid drives including not only an internal combustion engine but also an electric machine. The electric machine can be connected to the internal combustion engine for drive and can receive power from the internal combustion engine or can additionally output power as a switchable auxiliary drive.

[0005] In recent years, there has been a trend towards supercharged engines, the economic importance of which for the motor vehicle construction industry is increasing. Supercharging is the main method for increasing the power to compress the air required for the combustion process in the engine, as a result of which a greater air mass can be fed to each cylinder in each working cycle. In this way, the fuel mass and therefore the average pressure can be increased.

[0006] Supercharging is a suitable way to increase the power of an internal combustion engine while maintaining the volume displacement constant or to reduce the volume displacement while maintaining the same power. In all cases, supercharging leads to an increase in volumetric power output and a more favorable power-to-weight ratio. If the volume displacement is reduced, it is therefore possible to shift the common load towards higher loads, when the specific fuel consumption is lower. Supercharging therefore contributes to the ongoing efforts in the development of internal combustion engines to minimize fuel consumption and increase the efficiency of internal combustion engines.

[0007] By means of a suitable transmission configuration, it is also possible to achieve so-called downshifting, thereby also achieving a lower specific fuel consumption. In the case of downshifting, use is made of the fact that the specific fuel consumption at low engine speeds is generally lower, particularly in the presence of relatively high loads.

[0008] For supercharging, an exhaust gas turbocharger is often used, in which the compressor and the turbine are arranged on the same shaft. The hot exhaust gas flow is fed to the turbine and expanded in the turbine with the release of energy, which causes the shaft to rotate. The energy released by the exhaust gas flow to the turbine and finally to the shaft is used to drive the compressor, which is arranged in the intake system of the engine. The compressor transfers and compresses the charge air fed to the compressor, resulting in supercharging of the engine. A charge air cooler is usually provided in the intake system downstream of the compressor, by means of which the compressed charge air is cooled before it enters the cylinders of the engine. The charge air cooler reduces the temperature of the charge air and thereby increases its density, so that the charge air cooler also contributes to the supercharging of the cylinders (e.g., with a larger air mass), for example by compression with cooling.

[0009] An advantage of an exhaust gas turbocharger over a supercharger that may be driven by means of an auxiliary drive is that an exhaust gas turbocharger utilizes the exhaust energy of the hot exhaust gas, whereas a supercharger draws the energy required to drive it directly or indirectly from the internal combustion engine and thus reduces the efficiency of the engine at least during the time when the driving energy does not originate from an energy recovery source. If the supercharger is not a supercharger that can be driven by means of an electric machine (e.g. electrically), a mechanical or kinematic connection for power transmission is generally required between the supercharger and the internal combustion engine, which also affects the packaging of the engine system.

[0010] The advantage of a supercharger over an exhaust-gas turbocharger is that, in particular, a supercharger can always generate the desired boost pressure and make it available regardless of the operating state of the internal combustion engine. This applies in particular to superchargers that can be driven electrically by means of an electric machine and are therefore independent of the rotational speed of the crankshaft.

[0011] In some internal combustion engine systems, one or more intake charging devices may be staged in series or parallel in what may be referred to as a compound boost configuration. For example, a fast auxiliary boost device (e.g., an electric supercharger or e-booster) may be utilized to increase the transient performance of a slower primary boost device (e.g., an exhaust turbocharger). Thus, power increases may be achieved across all engine speed ranges.

[0012] By targeted configuration of supercharging, it is possible not only to reduce fuel consumption and increase the efficiency of the internal combustion engine, but also to reduce exhaust emissions. However, in order to be able to comply with future limit values ​​for pollutant emissions, further measures in addition to supercharging systems are necessary. As an example, the reduction of nitrogen oxide emissions is of high relevance in particular in diesel engines. Since the formation of nitrogen oxides requires not only excess air but also high temperatures, one concept for reducing nitrogen oxide emissions consists in forming a combustion process with a low combustion temperature.

[0013] As an example, exhaust gas recirculation (EGR) can be used to reduce combustion temperatures, where it is possible to significantly reduce nitrogen oxide emissions by increasing the exhaust gas recirculation rate. Here, the exhaust gas recirculation rate x EGR Determined as x EGR =m EGR / (m EGR +m air ), where m EGR represents the mass of the recirculated exhaust gas and m air represents the supplied air. In order to obtain a considerable reduction in nitrogen oxide emissions, a high exhaust gas recirculation rate can be used, which can be approximated by x EGR ≈60% to 70% or more. Such high recirculation rates generally require cooling of the exhaust gas used for recirculation.

[0014] For example, an internal combustion engine may include an exhaust gas recirculation system which recirculates exhaust gas from downstream of a turbocharger turbine to upstream of a turbocharger compressor via a recirculation line. The exhaust gas recirculation system is thus a low-pressure EGR system. In the recirculation line, a cooler and an EGR valve for setting the flow rate of the recirculated exhaust gas are generally provided.

[0015] The advantage of low-pressure EGR compared to high-pressure EGR, in which the exhaust gas for recirculation is extracted upstream of the turbine and is no longer available to drive the turbine, is that all exhaust gas from the internal combustion engine is available at the turbine, regardless of the current recirculation rate. The reduced exhaust gas mass flow through the turbine results in particular in a lower turbine pressure ratio and therefore a lower charging pressure ratio, which is equivalent to a smaller compressor mass flow. Therefore, the low-pressure EGR system avoids a smaller compressor mass flow.

[0016] The exhaust gas recirculated to the intake system via the low-pressure EGR system is mixed with fresh air upstream of the turbocharger compressor. The mixture of fresh air and recirculated exhaust gas produced in this way forms charge air that is supplied to the compressor and compressed, and the charge air can be cooled in a charge air cooler downstream of the compressor.

[0017] However, the inventors herein have recognized potential problems with such systems. As an example, when an exhaust gas recirculation system is in effect / active and exhaust gas is introduced into the intake system upstream of the compressor, condensate may form. For example, if the recirculated hot exhaust gas encounters and mixes with cold fresh air, condensate may form. The exhaust gas cools down, while the temperature of the fresh air increases. The temperature of the mixture of fresh air and recirculated exhaust gas, i.e., the charge air temperature, is lower than the exhaust gas temperature of the recirculated exhaust gas. During the cooling process of the exhaust gas, if the dew point temperature of the components of the gaseous charge air flow undercuts, components such as water that were previously contained in the exhaust gas and are still in gaseous form may condense. When condensate formation occurs in the charge air flow, pollutants in the charge air often form the starting point for the formation of condensate droplets. As another example, condensate may form when hot exhaust gas and / or charge air impinges on the inner wall of the intake system, because the wall temperature is generally lower than the dew point temperature of the relevant gaseous components.

[0018] The problem of condensate formation is exacerbated with increasing recirculation rates, since with increasing recirculated exhaust gas flow rate, the proportion of individual exhaust gas components in the charge air, in particular the proportion of water contained in the exhaust gas, necessarily increases. Therefore, in the prior art, the exhaust gas flow rate recirculated via a low-pressure EGR system is usually limited in order to prevent or reduce the occurrence of condensation. The required limitation of the low-pressure EGR on the one hand and the high exhaust gas recirculation rate required for a considerable reduction in nitrogen oxide emissions on the other hand conflict, resulting in a reduced reduction in nitrogen oxide emissions. The problem of condensate formation is also exacerbated with decreasing ambient temperature, since with decreasing ambient temperature the charge air temperature, that is to say the temperature of the mixture of fresh air and recirculated exhaust gas, decreases, so that the charge air can in particular absorb less gaseous water. Here, the recirculated exhaust gas is cooled more strongly.

[0019] Condensate and condensate droplets are undesirable and lead to increased noise emissions in the air intake system and may degrade the turbocharger compressor. The latter effect is associated with a reduction in the efficiency of the compressor. Summary of the invention

[0020] In one example, the problem described above can be solved by a system for a supercharged internal combustion engine, the supercharged internal combustion engine comprising: an intake system for supplying charge air; an exhaust gas discharge system for discharging exhaust gas; a turbocharger comprising a turbine arranged in the exhaust gas discharge system and a compressor arranged in the intake system; an electrically drivable compressor arranged in the intake system upstream of the compressor of the turbocharger; a compressor-specific throttle element (compressor-specific throttle element); element), which is arranged upstream of the electrically drivable compressor; a bypass line for bypassing the electrically drivable compressor, which branches out from the intake system upstream of the electrically drivable compressor to form a third junction, and opens to the intake system between the electrically drivable compressor and the compressor of the turbocharger to form a fourth junction; a cut-off element, which is arranged in the bypass line; and an exhaust gas recirculation system, which includes a recirculation line branching from the exhaust gas discharge system downstream of the turbine of the turbocharger, the recirculation line bifurcating into a first recirculation branch and a second recirculation branch, the first recirculation branch including a first EGR valve and opening to the intake system upstream of the third junction to form a first junction, and the second recirculation branch including a second EGR valve and opening to the intake system between the fourth junction and the compressor of the turbocharger to form a second junction. In this way, the electrically drivable compressor can be used to heat fresh air drawn in via the intake system in order to counteract the formation of condensate during the introduction of the recirculated exhaust gas.

[0021] As an example, the fresh air can be throttled using a throttling element upstream of the electrically drivable compressor. Here, the pressure of the fresh air drops, while the temperature of the fresh air remains virtually unchanged. During subsequent compression in the electrically drivable compressor arranged downstream of the throttling element, the pressure of the fresh air then increases again, and the temperature of the fresh air increases. Fresh air at an elevated temperature is then present downstream of the electrically drivable compressor. If the exhaust gas is now introduced into the heated or warmer fresh air, a higher charge air temperature is also necessarily obtained. For example, the temperature of the mixture of fresh air and recirculated exhaust gas is also higher, whereby the charge air can absorb more gaseous water. The recirculated exhaust gas is cooled less strongly, thereby counteracting the formation of condensate in the charge air flow. Condensate formation due to wall contact is also counteracted, because the heated fresh air heats up the walls of the intake system downstream of the electrically drivable compressor. As another example, the exhaust gas recirculation system according to the present disclosure can be used during conditions that would otherwise cause condensate formation, such as after a cold start or in the presence of low ambient temperatures. In this way, the exhaust gas recirculation system may be used over an extended temperature range, thereby increasing fuel economy and reducing vehicle emissions while preventing degradation of the turbocharger compressor.

[0022] As another example, if no relevant condensate formation is expected, the electrically drivable compressor can be actively operated and used to generate a boost pressure, for example in order to increase the transient operating characteristics of the internal combustion engine, by opening the throttle element. In this example, exhaust gas recirculation can be provided upstream of the electrically drivable compressor via the first recirculation branch.

[0023] The heating of the fresh air according to the present disclosure has further advantageous effects. The heated charge air or fresh air contributes to the warm-up process of the internal combustion engine, in particular after a cold start, for example by introducing heat into the walls of the intake system and the combustion chamber walls of the cylinders. Due to the higher temperature level, the untreated emissions of unburned hydrocarbons and carbon monoxide can be reduced.

[0024] According to the present disclosure, the electrically drivable compressor is designed as an activatable compressor, which is activated when needed. In addition to the use described above, the electrically drivable compressor can in principle also be used whenever there is a need, including, for example, the need to assist the exhaust gas turbocharger in compressing charge air. The electrically drivable compressor can also be used to generate boost pressure instead of the exhaust gas turbocharger, for example during low loads or during low charge air flow rates.

[0025] According to the disclosure, the electrically drivable compressor does not necessarily have to be switched off after the heating of the fresh air. The electrically drivable compressor can therefore continue to be operated even if no condensate formation is to be expected.

[0026] It should be understood that the above summary is provided to introduce a selection of concepts further described in the detailed description in a simplified form. It is not intended to identify key or essential features of the claimed subject matter, the scope of which is uniquely defined by the appended claims. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A first embodiment of an internal combustion engine is shown schematically.

[0028] Figure 2 A schematic drawing of an example vehicle system incorporating multiple stepped boost devices is shown.

[0029] Figure 3 is a flow chart for controlling an electrically drivable compressor and a low-pressure exhaust gas recirculation system.

[0030] Figure 4 is a prophetic example timeline for adjusting operation of an electrically-actuable compressor and a low-pressure exhaust gas recirculation system based on operating conditions. DETAILED DESCRIPTION

[0031] The following description generally relates to systems and methods for supercharging an internal combustion engine having a staged boost arrangement. A non-limiting example of such a supercharged engine system is Figure 1 and Figure 2 , wherein a turbocharger is staged downstream of an electrically drivable compressor (e.g., an electric booster or electric compressor). The electrically drivable compressor may be operated to provide heated intake air to the inlet of the compressor of the turbocharger, or, for example, according to Figure 3 The engine system further includes a low pressure exhaust gas recirculation (LP-EGR) system that can provide EGR upstream of the electrically drivable compressor, downstream of the electrically drivable compressor (and upstream of the compressor of the turbocharger), or both, where the location is selected based on operating conditions, as also shown in FIG. Figure 3 An example timeline for adjusting the operation of the electrically drivable compressor and the LP-EGR system based on operating conditions is shown in Figure 4 Shown in.

[0032] Figure 1 A first embodiment of a supercharged internal combustion engine 10 is schematically shown, which is equipped with an exhaust gas turbocharger 7, which comprises a turbine 7b arranged in the exhaust gas discharge system 2 and a compressor 7a arranged in the intake system 1. The components of the exhaust gas discharge system 2, the intake system 1 and the internal combustion engine 10 will be described below with reference to Figure 2Explanation. The hot exhaust gas expands in the turbine 7b with energy release and drives the compressor 7a. The compressor 7a compresses the charge air supplied to the cylinders of the internal combustion engine 10 via the intake system 1 and the charge air cooler 6 provided downstream, resulting in supercharging of the internal combustion engine 10. The internal combustion engine is a four-cylinder in-line engine 10, in which Figure 1 In the exemplary embodiment of the present invention, the four cylinders are arranged along the longitudinal axis of the cylinder head, that is, along a line.

[0033] An electrically drivable compressor 8 is arranged in the intake system 1 upstream of the compressor 7 a of the exhaust-gas turbocharger 7, said electrically drivable compressor 8 being activatable to assist the compressor 7 a of the exhaust-gas turbocharger 7 in order to supply the cylinders with sufficient charge air, as will be described below with regard to Figure 2 and Figure 3 Detailed description. A bypass line 9 is provided for bypassing the electrically drivable compressor 8, the bypass line branches from the intake system 1 upstream of the electrically drivable compressor 8 by forming a third joint 9a, and leads to the intake system 1 between the electrically drivable compressor 8 and the compressor 7a of the exhaust gas turbocharger 7 by forming a fourth joint 9b. In the bypass line 9, a shut-off element 9c for opening and blocking the bypass line 9 is provided.

[0034] The internal combustion engine 10 is also equipped with a low-pressure exhaust gas recirculation (LP-EGR) system 3. The low-pressure EGR system 3 comprises a recirculation line 4 which branches off from the exhaust gas discharge system 2 downstream of the turbine 7b of the exhaust gas turbocharger 7 via a formed junction 4' and by means of which the exhaust gas can be introduced into the intake system 1 upstream of the compressor 7a of the exhaust gas turbocharger 7.

[0035] The recirculation line 4 is bifurcated into: a first recirculation branch 4a, which leads to the intake system 1 upstream of the third junction 9a through the formation of a first junction 4a'; and a second recirculation branch 4b, which leads to the intake system 1 between the fourth junction 9b and the compressor 7a of the exhaust gas turbocharger 7 through the formation of a second junction 4b'. Each recirculation branch 4a and 4b is respectively equipped with a dedicated EGR valve 4a" and 4b" for setting the recirculated exhaust gas flow rate, and the EGR valve 4a" and 4b" are arranged according to Figure 1 are arranged at the associated junctions 4a' and 4b' respectively and thus downstream of the cooler 5 arranged in the recirculation line 4. The bypass line 5a serves to bypass the cooler 5. The shut-off element 5b arranged in the bypass line 5a serves to open and close the bypass line 5a.

[0036] Exhaust gas flowing through turbine 7b is subjected to exhaust aftertreatment in exhaust aftertreatment system 11 upstream of LP-EGR system 3 and downstream of turbine 7b. In the present example, exhaust aftertreatment system 11 is shown to include an aftertreatment particulate filter 11a.

[0037] The electrically drivable compressor 8 can be used to heat the fresh air present in the intake system 1 in order to counteract (or reduce) the formation of condensate during the introduction of the recirculated exhaust gas via the second recirculation branch 4 b, as will be described below with regard to Figure 3 Description. The throttle element 8a arranged upstream of the electrically driven compressor 8 serves to throttle the fresh air flow, for example to reduce the pressure in the fresh air flow. Here, the pressure of the fresh air is preferably reduced isothermally, so that the temperature of the fresh air remains practically constant. During the subsequent compression in the electrically driven compressor 8 arranged downstream, the pressure of the fresh air is then increased again, for example to the atmospheric pressure (p ) upstream of the throttle element 8a. atm During compression, the temperature of the fresh air also increases, so that fresh air at an elevated temperature is provided downstream of the electrically drivable compressor 8. Condensate formation during the introduction of exhaust gas into the heated fresh air via the second recirculation branch 4b is thus counteracted.

[0038] Figure 2 Aspects of an example engine system 100 coupled to a vehicle 102 are schematically shown, including Figure 1 The internal combustion engine 10 introduced in FIG. Figure 2 of and in Figure 1Components that are the same as those introduced in the embodiment of the present invention are numbered the same and may not be introduced again. In some examples, the vehicle 102 may be a hybrid vehicle having multiple torque sources that can be used for one or more vehicle wheels 47. In other examples, the vehicle 102 is a conventional vehicle with only an engine. In the illustrated example, the powertrain of the vehicle 102 includes an engine 10 and an electric machine 52. The electric machine 52 may be a motor or a motor / generator (M / G). The engine 10 and the electric machine 52 are connected to the vehicle wheels 47 via a transmission 48 when one or more clutches 53 are engaged. In the depicted example, a (first) clutch 53 is provided between the engine 10 and the electric machine 52, and a (second) clutch 53 is provided between the electric machine 52 and the transmission 48. The controller 12 may send a signal to the actuator of each clutch 53 to engage or disengage the clutch, thereby connecting or disconnecting the engine 10 with the electric machine 52 and the components connected thereto and / or connecting or disconnecting the electric machine 52 with the transmission 48 and the components connected thereto. For example, when clutch 53 is engaged, torque from engine 10 can be transmitted to vehicle wheels 47 via crankshaft 40, transmission 48, and powertrain shaft 84. Transmission 48 can be a gearbox, a planetary gear system, or another type of transmission. Transmission 48 can be a fixed ratio transmission that includes multiple gear ratios to allow engine 10 to rotate at a different speed than wheels 47. By varying the torque transfer capacity of first clutch 53 (e.g., the amount of clutch slip), the amount of engine torque transmitted to the wheels via powertrain shaft 84 can be modulated.

[0039] The powertrain can be configured in various ways, including as a parallel, series, or series-parallel hybrid vehicle. In an electric vehicle embodiment, the system battery 45 can be a traction battery that delivers power to the electric machine 52 to provide torque to the vehicle wheels 47. In some embodiments, the electric machine 52 can also operate as a generator to provide power to charge the system battery 45, for example, during braking operations. It will be appreciated that in other embodiments, including non-electric vehicle embodiments, the system battery 45 can be a typical starting, lighting, ignition (SLI) battery connected to an alternator 46. The alternator 46 can be configured to charge the system battery 45 using engine torque drawn from the crankshaft during engine operation. In addition, the alternator 46 can power one or more power systems of the engine based on their corresponding electrical requirements, such as one or more auxiliary systems, including heating, ventilation and air conditioning (HVAC) systems, vehicle lights, onboard entertainment systems, and other auxiliary systems. In one example, the current drawn on the alternator can be continuously varied based on each of the operator cabin cooling requirements, battery charging requirements, other auxiliary vehicle system requirements, and motor torque. A voltage regulator may be coupled to the alternator 46 to regulate the alternator's electrical output based on system usage requirements including auxiliary system demands.

[0040] In the depicted example, the engine 10 is a boost engine configured with a staged boost device. Specifically, the engine 10 includes a first boost device that is staged upstream of the second boost device. Here, the first boost device is an electric mechanical supercharger or electric booster 13, and the second boost device is a turbocharger 7, but other configurations are possible. As an example, the electric booster 13 may be an auxiliary boost device, and the turbocharger 7 may be a main boost device. The compressor 7a of the turbocharger 7 is shown as being coupled to the intake passage 42 and mechanically coupled to the turbine 7b via the shaft 19, and the turbine 7b is coupled to the exhaust passage 35 and driven by the expanded engine exhaust. In one example, the turbocharger may be a dual scroll device. In another example, the turbocharger may include a variable geometry turbine (VGT), wherein the turbine geometry actively changes with the engine operating conditions. The electric booster 13 includes an electric motor 108 for driving the electrically drivable compressor 8 via the shaft 80. The electric motor 108 may be powered by an onboard energy storage device, such as a system battery 45. The electric motor 108 may additionally or alternatively be powered by an alternator 46. The amount of power delivered to the electric motor 108 may be varied to adjust the duty cycle of the electric boost. In one example, the amount of power delivered to the electric motor 108 may be increased to increase the speed of the electrically drivable compressor 8, with a corresponding increase in the electrical load imposed on the alternator and a decrease in the alternator current. Due to the electrical assist, the electrically drivable compressor 8 may be spun up quickly, thereby providing fast acting or high frequency boost actuation and on-demand intake air heating.

[0041] However, other combinations and configurations of boost devices may be possible without departing from the scope of the present disclosure. For example, in alternative examples, the turbocharger 7 may be an electric turbocharger having an electric motor coupled to a compressor, a turbine, or a turbocharger shaft, or may be an electric or mechanical supercharger. In still other examples, there may be additional boost devices, such as two turbochargers staged in series, two turbochargers staged in parallel, or any combination of a turbocharger and a mechanical supercharger. In addition, in some examples, the compressor 7a may be a radial compressor. In other examples, the compressor 7a may be an axial compressor.

[0042] Fresh air is introduced into the intake system 1 along the intake passage 42 via the air box 112 and flows to the electrically drivable compressor 8 and / or the compressor 7a of the turbocharger 7. Figure 3 During selected conditions described in detail, the controller 12 can completely close the throttle element 8a and at the same time completely open the shut-off element 9c, so that fresh air flows via the bypass line 9 to the inlet of the compressor 7a without flowing through the electrically drivable compressor 8. Figure 3During other conditions described in detail, the controller 12 can completely close the cutoff element 9c and at least partially open the throttle element 8a so that fresh air flows through the electrically drivable compressor 8 and then reaches the inlet of the compressor 7a via the passage 70. As an example, when heating of the fresh air is indicated, the controller can deliver fresh air via the passage 70 and the electrically drivable compressor 8, such as to reduce condensate formation. As another example, the controller can deliver fresh air via the passage 70 and the electrically drivable compressor 8 to quickly increase the amount of boost provided to the internal combustion engine 10.

[0043] In some examples, compressor 7a is coupled to throttle 20 via charge air cooler (CAC) 6 (also referred to as an intercooler). Air flows from compressor 7a through CAC 6 and throttle 20 to intake manifold 22. CAC 6 may be, for example, an air-to-air or water-to-air heat exchanger. Intake manifold pressure (e.g., the pressure of the air charge within the intake manifold) may be determined using a manifold absolute pressure (MAP) sensor 124.

[0044] The intake manifold 22 is coupled to a series of combustion chambers (or cylinders) 30 through a series of intake valves (not shown). The combustion chambers are further coupled to an exhaust manifold 36 of the exhaust removal system 2 via a series of exhaust valves (not shown). In the depicted example, a single exhaust manifold 36 is shown. However, in other embodiments, the exhaust manifold may include multiple exhaust manifold sections. A configuration with multiple exhaust manifold sections may enable exhaust from different combustion chambers to be directed to different locations in the engine system.

[0045] In one example, each of the exhaust valve and the intake valve may be actuated or controlled electronically. In another example, each of the exhaust valve and the intake valve may be actuated or controlled by cams. Whether actuated electronically or by cams, the timing of the opening and closing of the exhaust and intake valves may be adjusted to obtain desired combustion and emission control performance. For example, the cam timing may be adjusted via a variable cam timing system to move the intake and exhaust cams to a position that provides the best volumetric efficiency for a given operating condition.

[0046] Combustion chamber 30 may be supplied with one or more fuels such as gasoline, an alcohol fuel blend, diesel, biodiesel, compressed natural gas, etc. Fuel may be supplied to the combustion chamber via direct injection, port injection, throttle body injection, or any combination thereof. In the depicted example, fuel is provided to each combustion chamber 30 via direct injection through fuel injector 66 (although Figure 2Only one fuel injector is shown, but each combustion chamber includes a fuel injector coupled thereto. Fuel may be delivered to fuel injector 66 by a fuel system (not shown) including a fuel tank, a fuel pump, and a fuel rail. Combustion may be initiated in the combustion chamber via spark ignition and / or compression ignition.

[0047] like Figure 2 As shown, the exhaust gas from the exhaust manifold 36 is directed to the turbine 7b to drive the turbine. When a reduced turbine torque is desired, in an example in which the turbine 7b is a variable geometry turbine, the turbine blades can be changed to reduce the exhaust pressure upstream of the turbine 7b, thereby reducing the speed of the turbine 7b. When an increased turbine torque is required, the turbine blades can be changed to increase the exhaust pressure upstream of the turbine 7b, thereby increasing the speed of the turbine 7b. As an example, the turbine blades can be coupled to an annulus, and the annulus can be rotated to adjust the position of the turbine blades. In another example, one or more of the turbine blades can be pivoted individually or multiple together. Adjusting the position of the turbine blades can adjust the cross-sectional opening (or area) of the turbine 7b. As another example, the turbine 7b can include a wastegate, and a portion of the exhaust gas can be directed through the wastegate instead, bypassing the turbine to reduce the turbine speed. For example, a wastegate actuator (eg, a wastegate valve) may be actuated open to relieve at least some exhaust pressure via the wastegate from a location upstream of turbine 7b to a location downstream of turbine 7b to reduce turbine speed.

[0048] The exhaust gas flow from the turbine 7b flows through the exhaust gas aftertreatment system 11. Generally speaking, the exhaust gas aftertreatment system 11 can include one or more exhaust gas aftertreatment components configured to reduce the amount of one or more substances in the exhaust gas flow. For example, one exhaust gas aftertreatment component can be configured to capture NO from the exhaust gas flow when the exhaust gas flow is lean. x And when the exhaust flow is rich, the trapped NO is reduced x In other examples, the exhaust aftertreatment component may be configured to cause NO x Disproportionate or selective reduction of NO with the aid of a reducing agent x In yet other examples, the exhaust aftertreatment system 11 includes a system configured to oxidize residual hydrocarbons and carbon monoxide while reducing NO in the exhaust gas flow. x A three-way catalyst. Different exhaust aftertreatment catalysts having any such functionality may be arranged individually or together in the washcoat or elsewhere in the exhaust aftertreatment system 11. In addition, the exhaust aftertreatment system 11 is shown as including a particulate filter 11a for removing particulate matter from the exhaust. As an example, the particulate filter 11a may be a regenerable soot filter configured to capture and oxidize soot particles in the exhaust gas flow.

[0049] All or a portion of the treated exhaust gas from the exhaust aftertreatment system 11 can be released into the atmosphere via the exhaust passage 35. However, depending on operating conditions, some of the exhaust gas may actually be diverted to the intake passage 42 via the LP-EGR system 3. In other examples, a high-pressure (HP) EGR system may be included in addition or alternatively. The exhaust gas is directed from downstream of the turbine 7b (via the junction 4') to upstream of the compressor 7a via the recirculation line 4. The exhaust gas delivered to the upstream of the compressor 7a can be delivered upstream of the electrically-actuated compressor 8 (e.g., via the first recirculation branch 4a and the first junction 4a') and / or downstream of the electrically-actuated compressor 8 (e.g., via the second recirculation branch 4b and the second junction 4b'), where the position is selected based on the operating conditions (as described below with respect to Figure 3 Detailed description further). The amount of EGR provided to intake passage 42 upstream of compressor 7a may be varied by controller 12 via EGR valve 4a" and / or EGR valve 4b". In some examples, cooler 5 may reject heat from the EGR gases to, for example, engine coolant.

[0050] Under some conditions, the EGR system may be used to regulate the temperature of the air and fuel mixture within the combustion chamber 30. Therefore, it may be desirable to measure or estimate the EGR mass flow rate. An EGR sensor may be disposed within the recirculation line 4 and may provide, for example, an indication of one or more of the mass flow, pressure, humidity, and temperature of the exhaust gas.

[0051] One or more sensors may be coupled to the intake passage 42 upstream of the compressor 7a for determining the composition and condition of the boost air entering the compressor. For example, an ambient pressure sensor 56 may be coupled to the intake passage 42 upstream of the compressor 7a and the electrically drivable compressor 8 for estimating the pressure of the air entering the compressor. Other sensors may include, for example, an air-fuel ratio sensor, a humidity sensor 58, etc. The sensor may estimate the condition of the intake air received from the intake passage at the compressor inlet. Although the humidity sensor 58 is shown as being positioned to measure the humidity of the fresh intake air, in other examples, the humidity sensor 58 may be additionally or alternatively positioned to measure the humidity of the recirculated exhaust gas. In addition, a throttle inlet pressure (TIP) sensor 59 may be coupled downstream of the CAC 6 and upstream of the throttle 20 for estimating the boost pressure delivered to the engine.

[0052] During an operator tip-in event, or when changing from engine operation without boost to engine operation with boost in response to an increase in operator torque demand, turbo lag may occur. This is due to the delay in the rotational acceleration of the turbine 7b due to the turbocharger being a slower-acting compression device, and the transient reduction in flow through the compressor 7a when the throttle 20 is opened when the accelerator pedal is pressed. The same situation also occurs when the engine is in boost operation and there is a transient increase in boost demand due to an increase in the accelerator pedal application by the vehicle operator. Specifically, in response to the tip-in, additional air flow may be briefly provided via the electric booster 13, such as by fully closing the cutoff element 9c in the bypass line 9, fully opening the throttle element 8a, and supplying power to activate the electric motor 108 and accelerate the rotation of the electrically drivable compressor 8. The additional compressed air provided to the compressor 7a via the passage 70 and the fourth junction 9b increases the amount of boost provided to the internal combustion engine 10. When the turbine has been sufficiently spun up and the turbocharger 7 is able to provide the requested amount of boost, the cut-off element 9c can be fully opened, the throttle element 8a can be fully closed, and the electric power 108 can be deactivated (eg, not supplied) so that additional compressed air is no longer provided by the electric booster 13.

[0053] The controller 12 may be included in the control system 14. The controller 12 is shown as receiving information from a plurality of sensors 16 (various examples of which are described herein) and sending control signals to a plurality of actuators 81 (various examples of which are described herein). As an example, the sensors 16 may include an exhaust gas sensor 126 located upstream of the turbine 7b, a MAP sensor 124, an exhaust temperature sensor 128, an exhaust pressure sensor 129, an ambient pressure sensor 56, an ambient temperature sensor 57, and a TIP sensor 59. Other sensors, such as additional pressure, temperature, air / fuel ratio, and composition sensors, may be coupled to various locations in the engine system 100. The actuators 81 may include, for example, a throttle 20, a shutoff element 9c, an EGR valve 4a", an EGR valve 4b", a throttle element 8a, an electric motor 108, and a fuel injector 66. The controller 12 may receive input data from the various sensors, process the input data, and employ various actuators to adjust engine operation based on received signals and instructions stored on a memory of the controller. The controller may employ the actuators in response to the processed input data based on instructions or code programmed therein corresponding to one or more routines, such as those described herein with respect to Figure 3 As an example, the controller 12 may actuate the cutoff element 9c to a fully closed position and adjust the position of the throttling element 8a in response to the ambient temperature measured by the ambient temperature sensor 57 and the humidity measured by the humidity sensor 58, while actuating the electric motor 108 to operate the electric booster 13.

[0054] therefore, Figure 1 and Figure 2 The system provides an embodiment of a supercharged internal combustion engine, in which a compressor-specific throttle element is arranged between a first junction and an electrically drivable compressor. In this way, if the compressor-specific throttle element is used to dissipate pressure, the electrically drivable compressor is used to heat the fresh air and the exhaust gas is recirculated into the intake system via the second recirculation branch. It is therefore not disadvantageous that the compressor-specific throttle element is arranged downstream of the first junction and thus increases the pressure in the intake system upstream (and therefore also at the first junction).

[0055] In an alternative embodiment, a compressor-specific throttling element may be arranged upstream of the first junction. In this example, a pressure gradient between the exhaust gas discharge system and the intake system may be generated, which may be used to increase or set a driving pressure gradient for the exhaust gas recirculation system via the first recirculation branch. In another alternative embodiment of a supercharged internal combustion engine, a compressor-specific throttling element may be arranged between the third junction and the electrically drivable compressor.

[0056] An embodiment of a supercharged internal combustion engine is provided in which the compressor-specific throttle element is a pivotable flap. As the throttle element, a commercially available throttle valve, which is already available on the market, can be utilized, for example.

[0057] An embodiment of a supercharged internal combustion engine is provided in which at least one cooler is provided in the recirculation line. In order to achieve a considerable reduction in nitrogen oxide emissions, high exhaust gas recirculation rates can be used and cooling of the exhaust gas recirculation may be required in order to reduce the charge air temperature. During the cooling process that takes place in the cooler, components such as water contained in the exhaust gas in gaseous form may have condensed and collected as liquid in the cooler. Condensate separated in the cooler may a priori no longer condense downstream and lead to potential turbocharger compressor degradation. By using the cooler, the temperature of the exhaust gas for recirculation is reduced, whereby the temperature difference between the exhaust gas for recirculation and the fresh air is reduced. In this way, the formation of condensate during the mixing of fresh air and the recirculated exhaust gas is reduced, because the charge air temperature of the mixture is only not significantly lower than the exhaust gas temperature of the recirculated exhaust gas (if any). Subsequently, significantly less water or no water condenses during the cooling of the exhaust gas in the intake system.

[0058] In this context, an embodiment of a supercharged internal combustion engine is provided in which an EGR valve is arranged downstream of at least one cooler. Subsequently, when the exhaust gas recirculation system is inactive, no fresh air from the intake system can be delivered to the cooler, which in this example can remain filled with hot exhaust gas. The closed EGR valve acts as a barrier to the entry of fresh air, wherein due to the system of the EGR valve downstream of the cooler, the cooler remains connected to the exhaust gas discharge system even when the exhaust gas is no longer circulated to the intake system. The fact that the recirculation line upstream of the cooler and the EGR valve remains filled with hot exhaust gas causes the part of the exhaust gas recirculation system to heat up, thereby counteracting the formation of condensate caused by wall contact. In addition, the evaporation of previously formed condensate can be promoted due to the hot LP-EGR system. For this reason, in this context, an embodiment of a supercharged internal combustion engine in which an EGR valve is arranged at an associated junction is also provided. Subsequently, the entire recirculation line together with the recirculation branch until the intake side junction remains filled with hot exhaust gas and heated by the exhaust gas.

[0059] An embodiment of a supercharged internal combustion engine is provided in which a bypass line for at least one cooler is included. In various situations, it may not be necessary to cool the recirculated exhaust gas, for example after a cold start of the internal combustion engine or during engine braking operation, wherein preferably hot exhaust gas is supplied to the cylinders. Therefore, the exhaust gas for recirculation can bypass the cooler via the bypass line and an open shut-off element in the bypass line.

[0060] In some embodiments, at least one of the EGR valves is a pivotable flap. If the flap is arranged in a suitable manner, it can be used, possibly in interaction with other components, to set the exhaust gas flow rate recirculated via the exhaust gas recirculation system and to set the fresh air flow rate supplied via the intake system. For example, the flap can be pivoted around a main axis running transversely relative to the fresh air flow in such a way that: in a first end position, the front side of the flap blocks the intake system and at the same time the recirculation line is open; and in a second end position, the rear side of the flap covers the recirculation line and at the same time the intake system is open. In the above context, "blocking" and "covering" also do not necessarily mean "closing" or completely blocking and covering.

[0061] An embodiment of a supercharged internal combustion engine is provided in which at least one exhaust gas aftertreatment system is arranged in the exhaust gas discharge system between the turbine and the joint of at least one exhaust gas turbocharger. For example, the exhaust gas for recirculation can be subjected to exhaust gas aftertreatment, in particular a particle filter, and then recirculated to the compressor of at least one exhaust gas turbocharger. In this way, deposits in the compressor can be reduced, which deposits change the geometry of the compressor, in particular the flow cross section, and deteriorate the efficiency of the compressor. In this context, an embodiment of a supercharged internal combustion engine is provided in which a particle filter as an exhaust gas aftertreatment system is arranged in the exhaust gas discharge system between the turbine and the joint of at least one exhaust gas turbocharger.

[0062] Embodiments of a supercharged internal combustion engine are provided in which a charge air cooler is arranged in an intake system downstream of a compressor of at least one exhaust gas turbocharger. The charge air cooler reduces the temperature of the charge air and thereby increases the density of the charge air so that an increased charge pressure of the cylinders is achieved (e.g., a greater air mass is supplied) than when a charge air cooler is not used to reduce the temperature of the charge air.

[0063] Next, Figure 3 Shown for use when the EGR system is active (e.g. Figure 1 and Figure 2 An example method 300 for operating an electrically drivable compressor of a supercharged internal combustion engine while operating the LP-EGR system 3) shown in FIG. Figure 1 and Figure 2 1. The electrically drivable compressor 8 of the internal combustion engine 10 shown in FIG. The electrically drivable compressor and the electric motor (eg, Figure 2 The electric motor 108 shown in FIG. 1 may be collectively referred to as an electric booster (eg, Figure 2 The electric boost 13 is an electric booster. For example, under selected conditions, the electric boost can be used to heat incoming (e.g., intake) air to reduce condensate formation, and under other conditions, the electric boost can be used to provide boost pressure (e.g., additional boost pressure) to the engine. In addition, the position of EGR delivered by the LP-EGR system can be adjusted based on whether the electric boost is activated and used for incoming air heating, activated and used to supply boost pressure, or deactivated and not used for incoming air heating or supplying boost pressure. Instructions for carrying out method 300 and the remainder of the methods included herein can be issued by a controller (e.g., Figure 2 The controller 12 is executed based on instructions stored in the memory of the controller and in combination with signals received from sensors of the engine system, such as those described above with reference to Figure 2The controller may use the actuators of the engine system (e.g., Figure 2 The cut-off element 9c, the throttle element 8a, the EGR valve 4a″ and the EGR valve 4b″) are used to adjust the engine operation according to the method described below.

[0064] Method 300 begins at 302 and includes estimating and / or measuring operating conditions. Operating conditions may include engine speed, engine load, torque demand (e.g., as inferred from the position of an accelerator pedal), engine temperature (e.g., as inferred from the engine coolant temperature measured by an engine coolant temperature sensor), intake manifold pressure (e.g., as inferred from, for example, a temperature sensor, etc.), and / or a pressure sensor. Figure 2 MAP sensor 124, etc.), ambient temperature (e.g., as measured by Figure 2 of the temperature sensor 57), ambient pressure (e.g., as measured by Figure 2 pressure sensor 56), ambient humidity (e.g., as measured by Figure 2 humidity sensor 58 measurements), requested (eg, desired) engine dilution (or EGR flow rate), requested boost amount, etc. Operating conditions may be measured or inferred based on available data.

[0065] At 304, method 300 includes determining whether condensate formation is expected. As an example, expected condensate formation may be at a turbocharger compressor (eg, Figure 1 and Figure 27a) of the compressor 7a). For example, the controller may make a determination whether condensate formation is expected at the turbocharger compressor inlet based on ambient temperature, ambient humidity, and requested engine dilution. It may be expected that condensate forms at the turbocharger compressor inlet, for example, when fresh (cold) intake air mixes with moist EGR gas upstream of the turbocharger compressor. Thus, the controller may input ambient temperature, ambient humidity, and requested engine dilution into one or more lookup tables, algorithms, or maps and output a determination (e.g., yes or no) of whether condensate formation is expected for the input conditions. As another example, the controller may make a logical determination of whether condensate formation is expected using a logic rule that varies with ambient temperature, ambient humidity, and desired engine dilution. As another example, condensate formation may be expected when LP-EGR is requested and the ambient temperature is less than a threshold temperature. The threshold temperature may be a pre-calibrated temperature value, below which condensate formation is known to occur and above which condensate formation is expected not to occur. The threshold temperature may be a positive non-zero temperature value (e.g., 8° C., as a non-limiting example), a negative non-zero temperature value (e.g., −8° C., as a non-limiting example), or equal to zero (e.g., 0° C.) In some examples, the threshold temperature may be adjusted based on one or more of ambient humidity and desired engine dilution.

[0066] If condensate formation is expected, then method 300 proceeds to 306 and includes determining a desired inlet air temperature based on operating conditions to reduce condensate formation. The desired inlet air temperature may be a desired temperature of air leaving the electric booster to prevent or resist condensate that may form when air leaving the electric booster mixes with the LP-EGR flow upstream of the turbocharger compressor inlet. For example, the controller may input ambient temperature, ambient humidity, and requested engine dilution (e.g., desired LP-EGR flow or rate) into one or more lookup tables, algorithms, or maps and output a desired inlet air temperature that will result in reduced condensate formation upstream of the turbocharger compressor for the input conditions. As an example, as ambient temperature decreases, ambient humidity increases, and / or requested engine dilution increases, the desired inlet temperature may increase.

[0067] At 308, method 300 includes closing the bypass valve and activating the electric booster to provide heated incoming air. For example, the bypass valve can be a shutoff element (e.g., shutoff element 9c in bypass line 9) positioned in a bypass line that bypasses the electrically drivable compressor. Thus, method 300 at 308 can include fully closing the bypass valve so that incoming air flows through the electrically drivable compressor, where the incoming air is heated via compression, but then flows to the inlet of the turbocharger compressor and does not pass through the bypass line. Activating the electric booster includes using power from a battery (e.g., Figure 2 The electrically drivable compressor is operated at a non-zero desired speed via an electric motor using power drawn from a system battery 45. The amount of power (or duty cycle of power) commanded to the electric motor can be based on the desired speed. As an example, the desired speed can be further based on the desired intake air temperature (e.g., as determined above at 306). For example, the controller can input the desired intake air temperature into a lookup table or function to determine the desired electrically drivable compressor speed. As another example, the desired speed can be a fixed pre-calibrated speed stored in the memory of the controller for providing intake air heating. Whether determined based on the desired intake air temperature or fixed, the controller can input the desired electrically drivable compressor speed into an additional lookup table or function to output a corresponding amount of power (or duty cycle of power) to provide to the electric motor to produce the desired compressor speed.

[0068] Method 300 further includes adjusting the position of a throttle upstream of the electric boost at 308 based on the desired intake air temperature and pressure, as indicated at 310. Although activating the electric boost may increase the temperature of the intake air via compression, if the air flow through the electrically drivable compressor is not regulated, the electric boost may also increase the pressure of the intake air, which may not be desirable. Thus, as an example, the controller may cause the throttle (e.g., Figure 2The opening of the throttle element 8a) is reduced by a certain amount, which is proportional to the increase in boost at the electrically drivable compressor that produces the desired intake air temperature. By throttling upstream of the electrically drivable compressor, the pressure at the inlet of the electrically drivable compressor can be reduced to below ambient pressure, and the electrically drivable compressor can then increase the intake air pressure back to ambient pressure (e.g., downstream of the electrically drivable compressor). As another example, when additional boost is required based on operating conditions (e.g., greater than ambient pressure), the throttle opening can be reduced to a lesser extent. The controller can input the desired intake air temperature, ambient pressure, desired intake air pressure, and electrically drivable compressor speed into one or more lookup tables, maps, or functions, and the output will result in the desired intake air temperature and pressure The degree of opening of the throttle. The controller can then generate a command signal, which is sent to the throttle upstream of the electric booster to adjust the throttle to the determined degree of opening.

[0069] At 312, method 300 includes delivering LP-EGR downstream of the electric booster (and upstream of the turbocharger compressor). Delivering LP-EGR downstream of the electric booster at 312 includes adjusting the downstream EGR valve (e.g., Figure 1 and Figure 2 As an example, as the desired engine dilution increases, the opening of the downstream EGR valve may increase, and as the desired engine dilution decreases, the opening of the downstream EGR valve may decrease. In addition, while providing LP-EGR downstream of the electric booster, an EGR valve (e.g., Figure 1 and Figure 2 4a" shown in the figure can be maintained fully closed. The controller can determine the desired engine dilution based on operating conditions including engine load, engine speed, engine temperature, etc. For example, the controller can refer to a lookup table having engine speed and load as inputs and a signal corresponding to the degree of opening applied to the downstream EGR valve as an output, the degree of opening providing an amount of dilution corresponding to the input engine speed-load. In still other examples, the controller can rely on a model that relates changes in engine load to changes in desired engine dilution and further relates changes in desired engine dilution to changes in downstream EGR valve position. For example, as the engine load increases from low load to medium load, the desired engine dilution can increase, and a larger downstream EGR valve opening can be requested. Subsequently, as the engine load increases from medium load to high load, the desired engine dilution can decrease, and a smaller downstream EGR valve opening can be requested.

[0070] Additionally, delivering LP-EGR downstream of the electric boost at 312 optionally includes bypassing the EGR cooler, as indicated at 316. As an example, the EGR cooler may be bypassed during cold starts and during braking when the engine may benefit from EGR having an increased temperature (e.g., Figure 1 and Figure 2 Bypassing the EGR cooler may include fully opening a shutoff element (e.g., Figure 1 and Figure 2 The method 300 can then be terminated.

[0071] Returning to 304, if condensate formation is not expected, method 300 proceeds to 318 and includes determining whether a tip-in event exists. For example, if the torque demand has increased by more than a threshold amount and / or if the accelerator pedal has been depressed by more than a threshold amount from an undepressed condition, it may be determined that a tip-in event exists. The threshold amount may refer to a positive, non-zero amount, which may be, for example, a percentage change. As another example, a tip-in event may be confirmed in response to a sudden increase in load demand.

[0072] If there is no tip-in event, method 300 proceeds to 320 and includes opening (or maintaining open) the bypass valve and not activating the electric booster. Alternatively, if the electric booster is currently activated, the method includes deactivating the electric booster at 320. With the bypass valve open (e.g., fully open), the incoming air can flow to the turbocharger compressor without having to first flow through the electric booster. If the electric booster is currently deactivated, deactivating the electric booster includes not supplying power to the electric motor so that the electrically drivable compressor is not driven by the electric motor and remains stationary, with a speed of zero. If the electric booster is currently activated, deactivating the electric booster includes stopping the supply of power to the electric motor so that the electrically drivable compressor rotates down to a standstill.

[0073] At 322, method 300 includes providing LP-EGR downstream of the electric booster and / or upstream of the electric booster. For example, by not anticipating condensate formation and the electric booster not being used to provide additional boost pressure, LP-EGR may be provided upstream of the electric booster and the fully opened bypass valve, downstream of the electric booster and the fully opened bypass valve, or both locations, as both locations provide LP-EGR upstream of the turbocharger compressor. Method 300 further includes adjusting the position of the downstream EGR valve and / or the position of the upstream EGR valve based on the desired engine dilution, as indicated at 324. For example, the controller may determine the desired engine dilution, as described above at 314, input the desired engine dilution into a lookup table or function, determine a first signal corresponding to the degree of opening applied to the downstream EGR valve as a first output, and determine a second signal corresponding to the degree of opening applied to the upstream EGR valve as a second output. In some examples, the second signal may correspond to a fully closed position of the upstream EGR valve, while the first signal corresponds to an opening degree for providing dilution of the entire engine via the downstream EGR valve. In other examples, the first signal may correspond to a fully closed position of the downstream EGR valve, while the second signal corresponds to an opening degree for providing dilution of the entire engine via the upstream EGR valve. In still other examples, both the first signal and the second signal may correspond to a partially open position, such that the combined opening of the downstream EGR valve and the upstream EGR valve produces the desired engine dilution. As an example of providing EGR both upstream of the electric booster and downstream of the electric booster, one of the upstream and downstream EGR valves may be opened to a fixed position to provide a fixed first portion of the total EGR, and the other of the upstream and downstream EGR valves may be continuously varied based on a change in the desired engine dilution to provide a variable second portion of the total EGR. The method 300 may then end.

[0074] Returning to 318, if a tip-in event is present, method 300 proceeds to 326 and includes closing (or maintaining closed) the bypass valve and activating the electric booster (or maintaining active the electric booster if currently activated) to provide auxiliary boost pressure via the electric booster. For example, during a tip-in event, the turbocharger compressor alone may not be able to provide the desired boost pressure due to, for example, the turbocharger's turbine (e.g., Figure 1 and Figure 2The turbine 7b) is rotated and accelerated to generate turbine lag. Providing auxiliary boost pressure via the electric booster further includes fully opening the throttle upstream of the electric booster, as indicated at 328, and adjusting the electric booster compressor speed based on the desired boost pressure, as indicated at 330. For example, the bypass valve can be actuated to (or maintained in) a fully closed position so that all incoming air flows through the electric booster before reaching the turbocharger. At the same time, the throttle upstream of the electrically drivable compressor can be actuated to a fully open position so that the throttle does not reduce the incoming air pressure at the inlet of the electric booster. In an alternative embodiment, the method may include partially opening the throttle upstream of the electric booster at 328, wherein the amount of opening is based on the torque demand or the additional boost required from the electric booster. Activating the electric booster includes operating an electrically drivable compressor at a non-zero desired speed via an electric motor using power drawn from a system battery, wherein the amount of power (or duty cycle of power) commanded to the electric motor is based on the desired speed, and the desired speed is further based on the desired boost pressure to be supplied by the electric booster. For example, the controller may input the desired boost pressure into a lookup table or function to determine the desired electrically drivable compressor speed. The controller may then input the desired electrically drivable compressor speed into an additional lookup table or function to output the corresponding amount of power (or duty cycle of power) to provide to the electric motor, thereby generating the desired boost pressure. For example, adjusting the electric booster compressor speed based on the desired boost pressure may include increasing the electric booster compressor speed as the desired boost pressure increases and decreasing the electric booster compressor speed as the desired boost pressure decreases. In addition, in some examples, the electric booster may be deactivated once the turbocharger turbine spins up and is able to provide the desired boost pressure without assistance.

[0075] At 332, method 300 includes providing LP-EGR upstream of the electric booster. By providing LP-EGR upstream of the electric booster, the LP-EGR can be mixed with fresh intake air and then compressed by the electrically drivable compressor. Providing LP-EGR upstream of the electric booster further includes adjusting the position of the upstream EGR valve based on the desired engine dilution, as indicated at 334. As an example, as the desired engine dilution increases, the opening of the upstream EGR valve can be increased, and as the desired engine dilution decreases, the opening of the upstream EGR valve can be reduced. In addition, while providing LP-EGR upstream of the electric booster, the positioned downstream EGR valve can be maintained fully closed. The controller can determine the desired engine dilution based on operating conditions including engine load, engine speed, engine temperature, etc. For example, the controller can refer to a lookup table having engine speed and load as inputs and a signal corresponding to the degree of opening applied to the upstream EGR valve as an output, the degree of opening providing an amount of dilution corresponding to the input engine speed-load. In yet other examples, the controller may rely on a model that relates changes in engine load to changes in desired engine dilution and further relates changes in desired engine dilution to changes in upstream EGR valve position. For example, as engine load increases from low load to medium load, desired engine dilution may increase, and a larger upstream EGR valve opening may be requested. Subsequently, as engine load increases from medium load to high load, desired engine dilution may decrease, and a smaller upstream EGR valve opening may be requested. Method 300 may then end.

[0076] therefore, Figure 3 Provided for operation of the above Figure 1 and Figure 2 A method for supercharging an internal combustion engine of the type described, wherein an electrically drivable compressor is operated when an exhaust gas recirculation system is active in order to introduce heat into the fresh air, the exhaust gas is recirculated via a second recirculation branch (e.g., second recirculation branch 4b), and the heated fresh air is introduced into the intake system at a second junction (e.g., second junction 4b'). An embodiment of the method is provided, wherein a bypass line of the electrically drivable compressor is closed by closing a shut-off element when the electrically drivable compressor is operated. An embodiment of the method is provided, wherein the fresh air is compressed to an ambient pressure p using the electrically drivable compressor atm , the fresh air temperature achieved by compression is set using a compressor-specific throttling element.

[0077] It should be understood that the Figure 3Method 300 is provided so that operation of the electric boost and LP-EGR system can be adjusted as operating conditions change. In this way, LP-EGR can be provided over an extended ambient temperature range including extremely low ambient temperatures (e.g., -8°C) while reducing condensate formation by utilizing the electric boost for inlet air heating. By providing LP-EGR during a larger ambient temperature range, vehicle emissions can be reduced while increasing fuel economy. In addition, by using the electric boost to heat the cold inlet air, condensate-induced degradation of the turbocharger compressor can be avoided. Still further, turbo lag can be reduced by using the electric boost as a fast-acting auxiliary boost device.

[0078] Next, Figure 4 For example, according to Figure 3 The method adjusts the electrically drivable compressor (e.g., Figure 1 and Figure 2 An electrically drivable compressor 8) and an LP-EGR system (e.g., Figure 1 and Figure 2 4 . An example timeline 400 of the operation of an LP-EGR system 3) of FIG. 402 is shown in FIG. 404 , the ambient temperature is shown in FIG. 406 , the bypass valve position is shown in FIG. 408 , the electrically drivable compressor speed is shown in FIG. 409 , the throttle element position is shown in FIG. 410 , the downstream EGR valve position is shown in FIG. 411 , and the upstream EGR valve position is shown in FIG. 412 . For all of the above graphs, the horizontal axis represents time, where time increases from left to right along the horizontal axis. The vertical axis represents each marked parameter. For graphs 402 , 404 , and 408 , the value of the marked parameter increases from bottom to top along the vertical axis. For graphs 406 , 410 , 412 , and 414 , the position of each marked parameter is shown from “closed” (e.g., fully closed) to “open” (e.g., fully open). Additionally, a threshold ambient temperature, below which condensate formation is expected at the inlet of the turbocharger turbine downstream of the electrically drivable compressor when LP-EGR is in use, is indicated by dashed line 416. While the threshold ambient temperature is shown as a fixed value in the example of timeline 400, it should be appreciated that in other examples, the threshold ambient temperature may vary based on operating conditions (e.g., ambient humidity and / or the amount of EGR provided).

[0079] Prior to time t1, the engine is operating at a relatively low engine load (graph 402). The ambient temperature (graph 404) is greater than a threshold temperature (dashed line 416). Therefore, condensate formation at the inlet of the turbocharger turbine is not expected. In addition, there is no tip-in event, and therefore the electrically-actuable compressor is not activated, with the compressor speed being zero (graph 408). Because the electrically-actuable compressor is not utilized, a bypass valve (e.g., Figure 1 and Figure 2 The cut-off element 9c shown in FIG. 4 is completely closed (graph 406) so that the intake air does not flow through the electrically drivable compressor before reaching the turbocharger compressor. In the example of timeline 400, a throttle element (e.g., Figure 1 and Figure 2 The throttling element 8a) is completely closed (graph 410). In addition, upstream and downstream of the electrically drivable compressor (e.g., via Figure 1 and Figure 2 The first recirculation branch 4a and the second recirculation branch 4b of the embodiment of the present invention provide LP-EGR. The upstream EGR valve (e.g., Figure 1 and Figure 2 The EGR valve 4a”) is held in a fixed partially open position to provide a first portion of LP-EGR (graph 414). And the downstream EGR valve (e.g., Figure 1 and Figure 2 The opening of the EGR valve 4b") varies with engine load and, therefore, desired engine dilution (graph 412). However, in other examples, both the upstream EGR valve and the downstream EGR valve may be actively varied with engine load, the downstream EGR valve may be maintained in a fixed partially open position while the position of the upstream EGR valve is actively varied, or EGR may be provided via only the upstream EGR valve or the downstream EGR valve.

[0080] At time t1, the ambient temperature (graph 404) decreases to below the threshold ambient temperature (dashed line 416). In response, the bypass valve is actuated to a fully closed position (graph 406) so that intake air is directed to the inlet of the electrically drivable compressor for heating via the electrically drivable compressor. In addition, the electrically drivable compressor is activated, for example, by supplying power to a motor that drives the electrically drivable compressor so that the electrically drivable compressor rotates to a non-zero speed (graph 408). In addition, the upstream EGR valve is adjusted to a fully closed position (graph 414) so ​​that LP-EGR is not provided upstream of the electrically drivable compressor. In fact, the downstream EGR valve (graph 412) is further opened, and the amount of further opening corresponds to the amount of closure of the upstream EGR valve so that all requested EGR is provided via the downstream EGR valve. Still further, a throttle element upstream of the electrically-drivable compressor is adjusted to a partially open position (graph 410), which is adjusted based on a desired amount of heat output by the electrically-drivable compressor to reduce condensate formation downstream of the electrically-drivable compressor and upstream of the turbocharger compressor.

[0081] At time t2, the ambient temperature (graph 404) increases to above the threshold ambient temperature (dashed line 416). In addition, there is no accelerator pedal event. In response, the electrically drivable compressor is deactivated, for example, by stopping the supply of power to the motor driving the electrically drivable compressor, and the electrically drivable compressor rotation is decelerated to a standstill (graph 408). In addition, the bypass valve and the throttle element are both fully closed (graphs 406 and 410, respectively), so that the intake air flows directly to the turbocharger inlet and bypasses the deactivated electrically drivable turbocharger. Further, LP-EGR is provided between time t2 and time t3 by a combination of upstream and downstream positions. The upstream EGR valve is maintained in a fixed partially open position (graph 414), and the position of the downstream EGR valve is adjusted in response to the engine load (graph 412).

[0082] Shortly before time t3, the engine load (graph 402) begins to increase rapidly due to the accelerator pedal tip-in event. In response to the accelerator pedal tip-in event, at time t3, the electrically drivable compressor is activated to briefly provide boost pressure while the turbocharger spins up. Therefore, at time t3, the bypass valve is actuated to a fully closed position (graph 406) so that intake air is directed to the inlet of the electrically drivable compressor, the throttle element is actuated to a fully open position (graph 410) so that air flow through the electrically drivable compressor is unrestricted, and power is supplied to the electric motor driving the electrically drivable compressor so that the electrically drivable compressor spins up quickly to a non-zero speed (graph 408). As described above with respect to Figure 3As described, the non-zero speed may be determined based on the desired boost pressure. In addition, all LP-EGR is supplied upstream of the electric booster. Therefore, the downstream EGR valve is fully closed (graph 412), and the upstream EGR valve is further opened (graph 414), and the degree of further opening of the upstream EGR valve corresponds to the amount of closure of the downstream EGR valve. Between time t3 and time t4, when LP-EGR is provided via the upstream EGR valve, the position of the upstream EGR valve is adjusted as the engine load changes.

[0083] At time t4, there is no longer an accelerator pedal event, and the turbocharger turbine has reached the desired speed (not shown) for providing the desired boost pressure. In addition, the ambient temperature (graph 404) remains above the threshold ambient temperature (dashed line 416). In response, the electrically drivable compressor is deactivated, for example, by stopping the supply of power to the motor driving the electrically drivable compressor, and the electrically drivable compressor rotation is decelerated to a standstill (graph 408). In addition, the bypass valve and the throttle element are both fully closed (graphs 406 and 410, respectively), so that the intake air flows directly to the turbocharger inlet and bypasses the deactivated electrically drivable turbocharger. Further, LP-EGR is provided after time t4 by a combination of upstream and downstream positions. The upstream EGR valve is maintained in a fixed partially open position (graph 414), and the position of the downstream EGR valve is adjusted in response to the engine load (graph 412). In addition, due to the higher engine load (graph 402), the amount of EGR provided is smaller than when the engine load is lower, such as before time t1.

[0084] In this way, an electrically drivable compressor may be used to provide heated intake air and / or boost pressure in an engine system. Specifically, by providing heated intake air downstream of an electrically drivable compressor and upstream of a turbocharger compressor, LP-EGR may be delivered at the inlet of the turbocharger compressor during low ambient temperatures with reduced condensate formation at the inlet of the turbocharger compressor. By providing LP-EGR during low ambient temperatures, vehicle emissions may be reduced while increasing engine efficiency. Additionally, by reducing condensate formation at the inlet of the turbocharger compressor, degradation of the turbocharger compressor due to condensate droplets may be reduced. Still further, by providing boost pressure via an electrically drivable compressor, turbo lag may be reduced, thereby increasing transient response of the engine system.

[0085] A technical effect of using an electrically drivable compressor arranged upstream of a turbocharger compressor to provide heated intake air downstream of the electrically drivable compressor is that low-pressure exhaust gas recirculation can be used at lower ambient temperatures with reduced condensate formation at the inlet of the turbocharger compressor.

[0086] As an example, a supercharged internal combustion engine comprises: an intake system for supplying pressurized air; an exhaust exhaust system for exhausting exhaust gas; a turbocharger comprising a turbine arranged in the exhaust exhaust system and a compressor arranged in the intake system; an electrically drivable compressor arranged in the intake system upstream of the compressor of the turbocharger; a compressor-specific throttling element arranged upstream of the electrically drivable compressor; a bypass line for bypassing the electrically drivable compressor, which branches off from the intake system upstream of the electrically drivable compressor to form a third junction and is connected between the electrically drivable compressor and the turbine The invention relates to an exhaust gas recirculation system, which includes a recirculation line branching from the exhaust gas discharge system downstream of the turbine of the turbocharger, and a second recirculation line forking into a first recirculation branch and a second recirculation branch, wherein the first recirculation branch includes a first EGR valve and leads to the intake system upstream of the third junction to form a first junction, and the second recirculation branch includes a second EGR valve and leads to the intake system between the fourth junction and the compressor of the turbocharger to form a second junction. In the previous examples, additionally or optionally, the compressor-specific throttling element is arranged between the first junction and the electrically drivable compressor. In any one or all of the previous examples, additionally or optionally, the compressor-specific throttling element is arranged between the third junction and the electrically drivable compressor. In any one or all of the previous examples, additionally or optionally, the compressor-specific throttling element is a pivotable baffle. In any one or all of the previous examples, the supercharged internal combustion engine additionally or optionally further includes a cooler arranged in the recirculation line. In any one or all of the previous examples, additionally or optionally, the first and second EGR valves are arranged downstream of the cooler and are arranged at the first junction and the second junction, respectively. In any one or all of the previous examples, the supercharged internal combustion engine additionally or optionally further includes a bypass line for the cooler. In any one or all of the previous examples, the supercharged internal combustion engine additionally or optionally further includes an exhaust aftertreatment system arranged in the exhaust gas discharge system between the turbine of the turbocharger and the exhaust gas recirculation system, the exhaust aftertreatment system including a particulate filter, and a charge air cooler arranged in the intake system downstream of the compressor of the turbocharger.

[0087] In another example, a method includes: operating the electrically drivable compressor to provide heated inlet air in response to a determination of expected condensate formation downstream of the electrically drivable compressor and upstream of a turbocharger compressor; and operating the electrically drivable compressor to provide auxiliary boost pressure in response to a tip-in event. In the previous example, additionally or optionally, the determination of the expected condensate formation downstream of the electrically drivable compressor and upstream of the turbocharger compressor is based on at least one of ambient temperature, ambient humidity, and an amount of low-pressure exhaust gas recirculation provided downstream of the electrically drivable compressor and upstream of the turbocharger compressor. In any or all of the previous examples, additionally or optionally, operating the electrically drivable compressor to provide heated inlet air includes: completely closing a shutoff element in a passage bypassing the electrically drivable compressor; rotating the electrically drivable compressor at a non-zero speed via an electric motor; and adjusting a throttling element positioned upstream of the electrically drivable compressor based on a desired temperature of the heated inlet air and a desired pressure downstream of the electrically drivable compressor. In any or all of the previous examples, additionally or optionally, the desired temperature of the heated inlet air is determined based on at least one of the ambient temperature, the ambient humidity, and the amount of low-pressure exhaust gas recirculation provided downstream of the electrically drivable compressor and upstream of the turbocharger compressor. In any or all of the previous examples, additionally or optionally, the desired pressure downstream of the electrically drivable compressor is equal to ambient pressure. In any or all of the previous examples, additionally or optionally, operating the electrically drivable compressor to provide auxiliary boost pressure in response to the accelerator pedal event includes: fully closing a shutoff element in a passage bypassing the electrically drivable compressor; fully opening a throttling element positioned upstream of the electrically drivable compressor; rotating the electrically drivable compressor at a non-zero speed via an electric motor; and adjusting the non-zero speed based on the desired pressure downstream of the electrically drivable compressor. In any or all of the previous examples, the method additionally or optionally further includes: providing low-pressure exhaust gas recirculation (LP-EGR) downstream of the electrically-drivable compressor and not upstream of the electrically-drivable compressor during the operation of the electrically-drivable compressor to provide heated intake air; providing the LP-EGR upstream of the electrically-drivable compressor and not downstream of the electrically-drivable compressor during the operation of the electrically-drivable compressor to provide auxiliary boost pressure; and providing the LP-EGR downstream and / or upstream of the electrically-drivable compressor when the electrically-drivable compressor is not operating.In any or all of the previous examples, additionally or optionally, the amount of LP-EGR provided upstream of the electrically-drivable compressor is adjusted by adjusting the position of a first EGR valve positioned upstream of the electrically-drivable compressor, and the amount of LP-EGR provided downstream of the electrically-drivable compressor is adjusted by adjusting the position of a second EGR valve positioned downstream of the electrically-drivable compressor.

[0088] As another example, a system includes: an engine coupled to an intake system for receiving pressurized air and an exhaust system for discharging exhaust gas; a compound boost system including an electrically driven compressor and a turbocharger compressor driven by an exhaust turbine, the turbocharger compressor being positioned downstream of the electrically driven compressor in the intake system; a throttle valve disposed at an inlet of the electrically driven compressor; an exhaust gas recirculation (EGR) system coupling the exhaust system downstream of the exhaust turbine to the intake system upstream of the electrically driven compressor via a first recirculation branch and coupling between the electrically driven compressor and the turbocharger compressor via a second recirculation branch; and a controller storing executable instructions in a non-transitory memory, the executable instructions, when executed, causing the controller to: activate the electrically-driven compressor and provide recirculated exhaust gas via the second recirculation branch in response to expected condensate formation at the inlet of the turbocharger compressor; activate the electrically-driven compressor and provide recirculated exhaust gas via the first recirculation branch in response to a tip-in event; and deactivate the electrically-driven compressor and provide recirculated exhaust gas via one or both of the first recirculation branch and the second recirculation branch in response to no expected condensate formation at the inlet of the turbocharger compressor and the absence of the tip-in event. In the previous example, the system additionally or optionally further includes a first EGR valve positioned at the junction of the first recirculation branch and the intake system and a second EGR valve positioned at the junction of the second recirculation branch and the intake system, and wherein: the first EGR valve is fully closed and the second EGR valve is at least partially opened to provide recirculated exhaust gas via the second recirculation branch; the first EGR valve is at least partially opened and the second EGR valve is fully closed to provide recirculated exhaust gas via the first recirculation branch; and the first EGR valve and the second EGR valve are both at least partially opened to provide recirculated exhaust gas via both the first recirculation branch and the second recirculation branch.In any or all of the previous examples, the system additionally or optionally further includes a bypass line including a bypass valve, coupled across the electrically driven compressor, and wherein the instructions causing the controller to activate the electrically driven compressor and provide recirculated exhaust gas via the second recirculation branch in response to expected condensate formation at the inlet of the turbocharger compressor include further instructions stored in a non-transitory memory, which, when executed, cause the controller to: completely close the bypass valve in the bypass line coupled across the electrically driven compressor; supply power from a system battery to an electric motor to drive the electrically driven compressor at a desired speed; and adjust a position of a throttle arranged at the inlet of the electrically driven compressor based on a desired intake air temperature at the outlet of the electrically driven compressor and a first desired pressure at the outlet of the electrically driven compressor, the desired intake air temperature at the outlet of the electrically driven compressor being based on an ambient temperature measured by an ambient temperature sensor and an amount of the recirculated exhaust gas provided via the second recirculation branch. In any or all of the previous examples, additionally or optionally, the instructions causing the controller to activate the electrically driven compressor and provide recirculated exhaust gas via the first recirculation branch in response to the accelerator pedal event include further instructions stored in a non-volatile memory, which, when executed, cause the controller to: completely close the bypass valve in the bypass line connected across the electrically driven compressor; completely open the throttle arranged at the inlet of the electrically driven compressor; and supply power from the system battery to the electric motor to drive the electrically driven compressor at a second desired speed, the second desired speed being adjusted based on a second desired pressure at the outlet of the electrically driven compressor.

[0089] It should be noted that the example control and estimation routines included in this article can be used with a variety of engine and / or vehicle system configurations. The control methods and routines disclosed herein can be stored as executable instructions in a non-transitory memory and can be performed by a control system including a controller in combination with various sensors, actuators, and other engine hardware. The dedicated routines described herein can represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. Thus, the various actions, operations, or functions described can be performed simultaneously in the order described, or they can be omitted in some cases. Similarly, the processing order is not necessary to obtain the features and advantages of the example embodiments described herein, but is provided for ease of description and description. Depending on the specific strategy used, one or more of the actions, operations, and / or functions described can be repeatedly performed. In addition, the described actions, operations, and / or functions can be graphically represented as codes in a non-transitory memory of a computer-readable storage medium to be programmed into an engine control system, wherein the described actions are performed by executing instructions in a system including various engine hardware components in combination with an electronic controller.

[0090] It will be appreciated that the configurations and routines disclosed herein are exemplary in nature, and the specific embodiments are not to be construed as limiting, as numerous variations are possible. For example, the above techniques may be used in V-6, I-4, I-6, V-12, opposed 4, and other engine types. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations and other features, functions, and / or properties disclosed herein.

[0091] As used herein, the term "approximately" is interpreted to mean plus or minus five percent of a range, unless otherwise specified.

[0092] The appended claims specifically point out certain combinations and sub-combinations that are considered novel and non-obvious. These claims may refer to "an" element or a "first" element or the equivalent thereof. Such claims should be understood to include the incorporation of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and sub-combinations of the disclosed features, functions, elements and / or properties may be claimed by amendment of the claims of the present invention or by the presentation of new claims in this or a related application. Such claims, whether broader, narrower, the same or different in scope than the original claims, are also deemed to be included in the subject matter of the present disclosure.

Claims

1. A supercharged internal combustion engine, comprising: an air intake system for supplying charge air; an exhaust gas removal system for removing exhaust gas; a turbocharger comprising a turbine arranged in the exhaust gas discharge system and a compressor arranged in the intake system; an electrically drivable compressor arranged in the intake system upstream of the compressor of the turbocharger; a compressor-specific throttling element, which is arranged upstream of the electrically drivable compressor; a bypass line for bypassing the electrically drivable compressor, which branches off from the intake system upstream of the electrically drivable compressor to form a third junction and opens into the intake system between the electrically drivable compressor and the compressor of the turbocharger to form a fourth junction; a cut-off element, which is arranged in the bypass line; as well as An exhaust gas recirculation system includes a recirculation line branching off from the exhaust gas discharge system downstream of the turbine of the turbocharger, the recirculation line bifurcating into a first recirculation branch and a second recirculation branch, the first recirculation branch including a first EGR valve and leading to the intake system upstream of the third junction to form a first junction, and the second recirculation branch including a second EGR valve and leading to the intake system between the fourth junction and the compressor of the turbocharger to form a second junction. 2 . The supercharged internal combustion engine according to claim 1 , wherein the compressor-specific throttle element is arranged between the first joint and the electrically drivable compressor. 3 . The supercharged internal combustion engine according to claim 1 , wherein the compressor-specific throttle element is arranged between the third joint and the electrically drivable compressor.

4. The supercharged internal combustion engine according to claim 1, wherein the compressor-specific throttle element is a pivotable flap.

5. The supercharged internal combustion engine according to claim 1, further comprising a cooler arranged in the recirculation line. 6 . The supercharged internal combustion engine according to claim 5 , wherein the first EGR valve and the second EGR valve are arranged downstream of the cooler and at the first joint portion and the second joint portion, respectively.

7. The supercharged internal combustion engine of claim 5, further comprising a bypass line for the cooler.

8. The supercharged internal combustion engine according to claim 1 , further comprising an exhaust gas aftertreatment system arranged in the exhaust gas discharge system between the turbine of the turbocharger and the exhaust gas recirculation system, the exhaust gas aftertreatment system comprising a particle filter, and a charge air cooler arranged in the intake system downstream of the compressor of the turbocharger.

9. A method comprising: responsive to a determination of expected condensate formation downstream of the electrically drivable compressor and upstream of the turbocharger compressor, operating the electrically drivable compressor to provide heated inlet air; as well as In response to a tip-in event, the electrically drivable compressor is operated to provide auxiliary boost pressure.

10. The method of claim 9, wherein the determination of the expected condensate formation downstream of the electrically drivable compressor and upstream of the turbocharger compressor is based on at least one of ambient temperature, ambient humidity, and an amount of low-pressure exhaust gas recirculation provided downstream of the electrically drivable compressor and upstream of the turbocharger compressor.

11. The method of claim 10, wherein operating the electrically drivable compressor to provide heated intake air comprises: completely closing a cutoff element in a passage bypassing the electrically drivable compressor; rotating the electrically drivable compressor at a non-zero speed via an electric motor; as well as Based on a desired temperature of the heated intake air and a desired pressure downstream of the electrically drivable compressor, a throttling element positioned upstream of the electrically drivable compressor is adjusted.

12. The method of claim 11, wherein the desired temperature of the heated inlet air is determined based on at least one of the ambient temperature, the ambient humidity, and the amount of low-pressure exhaust gas recirculation provided downstream of the electrically drivable compressor and upstream of the turbocharger compressor.

13. The method of claim 11, wherein the desired pressure downstream of the electrically drivable compressor is equal to ambient pressure.

14. The method of claim 9, wherein in response to the tip-in event, operating the electrically drivable compressor to provide auxiliary boost pressure comprises: completely closing a cutoff element in a passage bypassing the electrically drivable compressor; fully opening a throttle element located upstream of the electrically drivable compressor; rotating the electrically drivable compressor at a non-zero speed via an electric motor; as well as The non-zero speed is adjusted based on a desired pressure downstream of the electrically-drivable compressor.

15. The method according to claim 9, further comprising: providing low pressure exhaust gas recirculation (LP-EGR) downstream of the electrically drivable compressor and not upstream of the electrically drivable compressor during said operating the electrically drivable compressor to provide heated inlet air; providing the LP-EGR upstream of the electrically drivable compressor and not downstream of the electrically drivable compressor during said operating the electrically drivable compressor to provide auxiliary boost pressure; as well as The LP-EGR is provided downstream and / or upstream of the electrically drivable compressor when the electrically drivable compressor is not operating.

16. The method of claim 15, wherein the amount of LP-EGR provided upstream of the electrically-actuable compressor is adjusted by adjusting the position of a first EGR valve positioned upstream of the electrically-actuable compressor, and the amount of LP-EGR provided downstream of the electrically-actuable compressor is adjusted by adjusting the position of a second EGR valve positioned downstream of the electrically-actuable compressor.

17. A system comprising: an engine coupled to an intake system for receiving charge air and an exhaust system for discharging exhaust gas; a compound boost system comprising an electrically driven compressor and a turbocharger compressor driven by an exhaust turbine, the turbocharger compressor being positioned downstream of the electrically driven compressor in the intake system; a throttle valve disposed at the inlet of the electrically driven compressor; an exhaust gas recirculation system, or EGR system, coupling the exhaust system downstream of the exhaust turbine to the intake system upstream of the electrically driven compressor via a first recirculation branch and between the electrically driven compressor and the turbocharger compressor via a second recirculation branch; as well as A controller storing executable instructions in a non-transitory memory that, when executed, cause the controller to: activating the electrically driven compressor and providing recirculated exhaust gas via the second recirculation branch in response to expected condensate formation at an inlet of the turbocharger compressor; activating the electrically driven compressor and providing recirculated exhaust gas via the first recirculation branch in response to a tip-in event; as well as In response to no expected condensate formation at the inlet of the turbocharger compressor and the absence of the tip-in event, the electrically driven compressor is deactivated and recirculated exhaust gas is provided via one or both of the first and second recirculation branches.

18. The system of claim 17, further comprising a first EGR valve positioned at a junction of the first recirculation branch and the intake system and a second EGR valve positioned at a junction of the second recirculation branch and the intake system, and wherein: the first EGR valve is fully closed and the second EGR valve is at least partially opened to provide recirculated exhaust gas via the second recirculation branch; the first EGR valve being at least partially opened and the second EGR valve being fully closed to provide recirculated exhaust gas via the first recirculation branch; as well as The first EGR valve and the second EGR valve are each at least partially opened to provide recirculated exhaust gas via both the first recirculation branch and the second recirculation branch.

19. The system of claim 17, further comprising a bypass line including a bypass valve coupled across the electrically driven compressor, and wherein the instructions causing the controller to activate the electrically driven compressor and provide recirculated exhaust gas via the second recirculation branch in response to expected condensate formation at the inlet of the turbocharger compressor include: further instructions stored in non-transitory memory that, when executed, cause the controller to: Completely closing the bypass valve in the bypass line connected to both ends of the electrically driven compressor; supplying power from a system battery to the electric motor to drive the electrically driven compressor at a first desired speed; and Based on a desired intake air temperature at the outlet of the electrically driven compressor and a first desired pressure at the outlet of the electrically driven compressor, the position of the throttle valve arranged at the inlet of the electrically driven compressor is adjusted, wherein the desired intake air temperature at the outlet of the electrically driven compressor is based on the ambient temperature measured by an ambient temperature sensor and the amount of recirculated exhaust gas provided via the second recirculation branch.

20. The system of claim 19, wherein the instructions that cause the controller to activate the electrically driven compressor and provide recirculated exhaust gas via the first recirculation branch in response to the tip-in event include further instructions stored in non-transitory memory that, when executed, cause the controller to: Completely closing the bypass valve in the bypass line connected to both ends of the electrically driven compressor; fully opening the throttle valve disposed at the inlet of the electrically driven compressor; and Power is supplied from the system battery to the electric motor to drive the electrically-driven compressor at a second desired speed that is adjusted based on a second desired pressure at the outlet of the electrically-driven compressor.

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