阅读说明：本技术 用于机动车辆的内燃机的增压装置以及用于运行这种增压装置的方法 (Supercharging device for an internal combustion engine of a motor vehicle and method for operating such a supercharging device ) 是由 J·格罗尔德 于 2018-05-02 设计创作，主要内容包括：本发明涉及一种用于机动车辆的内燃机(2)的增压装置(5),其具有至少一个废气涡轮增压器(9),所述废气涡轮增压器具有可由内燃机(2)的废气驱动的涡轮(12)和可由涡轮(12)驱动的第一压缩机叶轮(13),借助所述第一压缩机叶轮能够压缩待输送给内燃机(2)的空气；具有至少一个电动压缩机(16),所述电动压缩机具有电机(18)和可由电机(18)驱动的第二压缩机叶轮(17),借助所述第二压缩机叶轮能够压缩待输送给内燃机(2)的空气；并且具有配设给第一压缩机叶轮(13)的推力空气循环装置(21),借助所述推力空气循环装置在内燃机(2)的负载减小的情况下能够使所述借助第一压缩机叶轮(13)被压缩的空气的至少一部分在设置在第一压缩机叶轮(13)下游的第一位置(S1)处分支出来并且能够从第一位置(S1)回引至设置在第一压缩机叶轮(13)上游的第二位置(S2),其中,增压装置(5)构造用于,向第二压缩机叶轮(17)供应所述分支空气,使得第二压缩机叶轮(17)并且经由第二压缩机叶轮使得电机(18)能够由所述分支空气驱动。(The invention relates to a charging device (5) for an internal combustion engine (2) of a motor vehicle, comprising at least one exhaust-gas turbocharger (9) having a turbine (12) which can be driven by the exhaust gas of the internal combustion engine (2) and a first compressor wheel (13) which can be driven by the turbine (12) and by means of which air to be supplied to the internal combustion engine (2) can be compressed; having at least one electric compressor (16) having an electric motor (18) and a second compressor wheel (17) which can be driven by the electric motor (18) and by means of which air to be fed to the internal combustion engine (2) can be compressed; and a thrust air circulation device (21) associated with the first compressor wheel (13), by means of which at least a part of the air compressed by means of the first compressor wheel (13) can be branched off at a first location (S1) arranged downstream of the first compressor wheel (13) and can be returned from the first location (S1) to a second location (S2) arranged upstream of the first compressor wheel (13) when the load on the internal combustion engine (2) is reduced, wherein the supercharging device (5) is designed to supply the branched air to the second compressor wheel (17) in such a way that the second compressor wheel (17) and the electric motor (18) can be driven by the branched air via the second compressor wheel.)

1. Supercharging device (5) for an internal combustion engine (2) of a motor vehicle, having at least one exhaust-gas turbocharger (9) which has a turbine (12) which can be driven by the exhaust gases of the internal combustion engine (2) and a first compressor wheel (13) which can be driven by the turbine (12) and by means of which air to be fed to the internal combustion engine (2) can be compressed; the charging device comprises at least one electric compressor (16) having an electric motor (18) and a second compressor wheel (17) which can be driven by the electric motor (18) and by means of which air to be supplied to the internal combustion engine (2) can be compressed; and having a thrust air circulation device (21) assigned to the first compressor wheel (13), by means of which at least a part of the air compressed by means of the first compressor wheel (13) can be branched off at a first location (S1) arranged downstream of the first compressor wheel (13) and can be returned from the first location (S1) to a second location (S2) arranged upstream of the first compressor wheel (13) in the event of a reduction in the load of the internal combustion engine (2), characterized in that the supercharging device (5) is designed to supply branched air to the second compressor wheel (17) in such a way that the second compressor wheel (17) can be driven by the branched air and the electric motor (18) can be driven by the branched air via the second compressor wheel.

2. Supercharging device (5) according to claim 1, characterized in that the electric motor (18) can be driven by the branched air via the second compressor wheel (17) and can thus be operated as a generator, by means of which the mechanical energy provided by the second compressor wheel (17) can be converted into electrical energy.

3. Supercharging device (5) according to claim 1 or 2, characterized in that the thrust air circulation device (21) has at least one return line (22) through which branched air can flow, in which a second compressor wheel (17) is arranged.

4. Supercharging device (5) according to claim 3, characterized in that in the first operating state the branch air flows through the return line (22) in a first direction.

5. Supercharging device (5) according to claim 4, characterized in that the second compressor wheel (17) compresses air to be delivered to the internal combustion engine (2) in a second operating state in which the air to be delivered to the internal combustion engine (2) flows through the return line (22) in a second direction opposite to the first direction.

6. Supercharging device (5) according to any of claims 2 to 5, characterized in that a valve device (25) is provided, by means of which a corresponding flow of air through the return line (22) can be regulated.

7. Method for operating a charging device (5) for an internal combustion engine (2) of a motor vehicle, having at least one exhaust-gas turbocharger (9) having a turbine (12) which can be driven by the exhaust gases of the internal combustion engine (2) and a first compressor wheel (13) which can be driven by the turbine (12) and by means of which air to be supplied to the internal combustion engine (2) can be compressed; the charging device comprises at least one electric compressor (16) having an electric motor (18) and a second compressor wheel (17) which can be driven by the electric motor (18) and by means of which air to be supplied to the internal combustion engine (22) can be compressed; and having a thrust air circulation device (21) associated with the first compressor wheel (13), by means of which at least a part of the air compressed by means of the first compressor wheel (13) can be branched off at a first location (S1) arranged downstream of the first compressor wheel (13) and can be returned from the first location (S1) to a second location (S2) arranged upstream of the first compressor wheel (13) in the event of a reduction in the load of the internal combustion engine (2), characterized in that in at least one operating state branched air is supplied to the second compressor wheel (17) in such a way that the second compressor wheel (17) is driven by the branched air and via the second compressor wheel the electric motor (18) is driven by the branched air.

8. Method according to claim 7, characterized in that the electric motor (18) is driven by the branched air via the second compressor wheel (17) and thereby operates as a generator which converts the mechanical energy provided by the second compressor wheel (17) into electrical energy and provides it.

Technical Field

The present invention relates to a charging device for an internal combustion engine of a motor vehicle according to the preamble of claim 1 and to a method for operating such a charging device according to the preamble of claim 7.

Background

Such a supercharging device for an internal combustion engine of a motor vehicle and such a method for operating such a supercharging device are known, for example, from DE 102015216685B 3. The charging device comprises at least one exhaust-gas turbocharger having a turbine which can be driven by the exhaust gases of the internal combustion engine and a first compressor wheel which can be driven by the turbine. By means of which the air to be fed to the internal combustion engine can be compressed. The compressed air is also referred to as charge air.

Furthermore, the supercharging device comprises at least one electric compressor, which is also referred to as an electrically driven compressor or an electrically drivable or operable compressor. The electric compressor includes an electric motor and a second compressor wheel, which may be driven by the electric motor. By driving the second compressor wheel, the air to be supplied to the internal combustion engine is compressed by means of the second compressor wheel. The electric machine can thus be operated, for example, as an electric motor, by means of which the second compressor wheel is driven or can be driven.

Furthermore, a thrust air circulation device is associated with the first compressor wheel, by means of which, in the event of a reduction in the load of the internal combustion engine, at least a portion of the air compressed by means of the first compressor wheel can be branched off at a first location arranged downstream of the first compressor wheel and can be returned from the first location to a second location arranged upstream of the first compressor wheel. In particular, the branched-off compressed air is depressurized by the thrust air circulation device and can be circulated via the first compressor wheel or can be circulated via the first compressor wheel, so that the branched-off air can be compressed again by the first compressor wheel after it has been returned to the second position.

Disclosure of Invention

The object of the present invention is to provide a charging device and a method of the type mentioned at the outset, which allow particularly efficient operation.

According to the invention, this object is achieved by a charging device having the features of claim 1 and by a method having the features of claim 7. Advantageous embodiments of the invention are the subject matter of the dependent claims.

A first aspect of the invention relates to a supercharging device for an internal combustion engine of a motor vehicle, in particular of a motor vehicle (e.g. passenger car). The charging device comprises at least one exhaust-gas turbocharger having a turbine which can be driven by the exhaust gases of the internal combustion engine and a first compressor wheel which can be driven by the turbine. The air to be supplied to at least one combustion chamber of an internal combustion engine, in particular an internal combustion engine, can be compressed by means of a first compressor wheel. The compressed air is also referred to as charge air.

Furthermore, the supercharging device comprises at least one electric compressor, which is also referred to as an electrically driven compressor, an electrically operable compressor or an electrically operable compressor. The electric compressor has an electric motor and a second compressor wheel, which can be driven by the electric motor. By driving the second compressor wheel, the air to be supplied to the internal combustion engine, in particular to at least one combustion chamber of the internal combustion engine, is compressed, for example by means of the second compressor wheel.

The charging device furthermore comprises a thrust air circulation device assigned to the first compressor wheel, by means of which, in the event of a reduced load of the internal combustion engine, at least a portion of the air compressed by means of the first compressor wheel can be branched off at a first location arranged downstream of the first compressor wheel and can be returned from the first location to a second location arranged upstream of the first compressor wheel.

The electric machine is, for example, in motor mode and can thus be operated as a motor, by means of which the second compressor wheel can be driven. The aforementioned load reduction of the internal combustion engine is also referred to as unloading, for example. In the context of such a load relief, the load provided by the internal combustion engine for driving the motor vehicle is reduced (in particular suddenly or abruptly). In other words, the load provided by the combustion engine, for example, initially has a first value. In the context of a load shedding or load reduction, the first value is reduced to a second value which is smaller than the first value, or the load is reduced from the first value to the second value. This is achieved, for example, in that: the throttle valve is at least partially closed. By means of the throttle valve, for example, the amount of air to be supplied to the internal combustion engine can be regulated. So-called compressor pumping of the first compressor wheel can be avoided by the thrust air circulation device.

In order to be able to carry out a particularly efficient and thus low-energy-consumption, in particular low-fuel-consumption operation of the internal combustion engine and thus of the motor vehicle as a whole, it is provided according to the invention that the supercharging device is designed to supply the second compressor wheel with the branched air in such a way that the second compressor wheel can be driven by the branched air and via the second compressor wheel the electric machine can be driven by the branched air. The idea according to the invention is therefore not to let the branched off air be lost unused, but instead to use it for driving the second compressor wheel and the electric motor.

In the case of conventional internal combustion engines, it is provided that the branched-off compressed air is returned by means of a thrust air circulation device and is depressurized in this case, so that the air which is first compressed by means of the first compressor wheel and is then depressurized can circulate or circulate via the first compressor wheel. The branched off air can thus be compressed again by means of the first compressor wheel after it has been returned to the second position. The energy contained in the branch air, which is contained in the branch air by compressing it by means of the first compressor impeller, is normally lost without being utilized, but this can now be avoided according to the invention.

It has proven to be particularly advantageous here if the electric machine can be driven by the branched air via the second compressor wheel and can thus be operated as a generator, by means of which the mechanical energy provided by the second compressor wheel can be converted into electrical energy. In other words, the electric machine is in the described generator mode and can thus be operated as a generator. Since the second compressor wheel is driven by the branched air at least in the operating state of the internal combustion engine, the second compressor wheel provides mechanical energy, in particular via a shaft which can be driven by the second compressor wheel. In this case, the generator or the electric motor is supplied with mechanical energy from the compressor wheel, wherein the generator is driven by the mechanical energy. The generator converts at least a portion of the mechanical energy to electrical energy and provides a back-up for the electrical energy obtained from the mechanical energy. It is thus possible, for example, to supply (in particular to supply at least substantially directly) at least one electrical consumer of the motor vehicle with the electrical energy provided by the generator. Alternatively or additionally, it is conceivable to feed the electrical energy provided by the generator into at least one energy storage device (in particular into a battery) and thus to store it in the energy storage device.

In this case, it has proven to be particularly advantageous if the electric machine can be supplied with electrical energy stored in the energy storage device during motor operation of the electric machine and the electric machine can be operated thereby. The energy contained in the branched-off compressed air can thus be used for operating the electric machine in motor mode and thus for compressing the air, so that a particularly energy-saving operation can be achieved.

In this way, it is possible with the supercharging device according to the invention to recover at least a part of the energy contained in the air compressed by means of the first compressor wheel and to carry out the supercharging pressure elimination particularly quickly, so that the compressor pumping of the first compressor wheel can be reliably avoided. For this purpose, in the unloaded state, the branched air flows from the high-pressure side to the low-pressure side via the second compressor wheel.

The compressor wheels are arranged, for example, in an air intake section through which air can flow, by means of which air is supplied to the internal combustion engine or the respective combustion chamber. The thrust air circulation device here comprises, for example, at least one return line which is fluidly connected to the suction section at the respective location. In this way, at least a part of the air compressed by the first compressor wheel can be branched off from the suction section and introduced into the return line in the first position. The branch air can flow through the return line and be guided by means of the return line from a first location arranged downstream of the first compressor wheel to a second location arranged upstream of the first compressor wheel. In the second position, air flowing through the return line can flow out of the return line and into the intake section. In this case, for example, a second compressor wheel is arranged in the return line, for example, in order to use the branched off air for driving the electric motor.

In a further advantageous embodiment of the invention, in the first operating state the branch air flows through the return line in the first direction, as a result of which the branch air flows back from the first position to the second position. In this way, in the first operating state, at least a portion of the air compressed by the first compressor wheel branches off from the intake section.

In a second operating state (in which the second compressor wheel compresses the air to be supplied to the internal combustion engine), the air to be supplied to the internal combustion engine flows through the return line in a second direction opposite the first direction and is compressed by the second compressor wheel. In other words, in the first operating state the second compressor wheel is driven by means of the branched air and the electric motor is driven via the second compressor wheel, so that the second compressor wheel is rotated about the axis of rotation in the first direction of rotation, for example, and the electric motor is operated in its generator mode. In the second operating state, however, the second compressor wheel is driven by the electric motor (in particular in motor-driven operation of the electric motor) and is thereby rotated about the axis of rotation in a second direction of rotation opposite the first direction of rotation, so that air is compressed by the second compressor wheel. In the first operating state, the second compressor wheel serves as a turbine or as a second turbine, by means of which the electric machine is driven.

In order to be able to achieve a particularly desired flow of air and a particularly desired change over between the first operating state and the second operating state, in a particularly advantageous embodiment a valve device is provided, by means of which the flow of air through the return line can be regulated.

A second aspect of the invention relates to a method for operating an internal combustion engine of a supercharging device for an internal combustion engine of a motor vehicle, in particular of a motor vehicle (e.g. passenger car). The charging device comprises at least one exhaust-gas turbocharger which has a turbine wheel drivable by the exhaust gas of the internal combustion engine and a first compressor wheel drivable by the turbine wheel. The air to be supplied to the internal combustion engine can be compressed by means of the first compressor wheel. Furthermore, the supercharging device comprises at least one electric compressor having an electric motor and a second compressor wheel which can be driven by the electric motor. The air to be supplied to the internal combustion engine can be compressed by means of the second compressor wheel. Furthermore, a thrust air circulation device is provided which is associated with the first compressor wheel and by means of which, in the event of a reduction in the load of the internal combustion engine, at least a part of the air compressed by means of the first compressor wheel is branched off at a first location which is arranged downstream of the first compressor wheel and recirculated from the first location to a second location which is arranged upstream of the first compressor wheel.

In order to be able to achieve a particularly efficient and therefore energy-saving operation, it is provided according to the invention that the branch air is supplied to the second compressor wheel in at least one operating state, so that the second compressor wheel is driven by the branch air and the electric motor is driven by the branch air via the second compressor wheel. The advantages and advantageous embodiments of the first aspect of the invention can be regarded as advantages and advantageous embodiments of the second aspect of the invention and vice versa.

Within the scope of the second aspect of the invention, it has proven to be particularly advantageous if the electric machine is driven by the secondary air via the second compressor wheel and thus operates as a generator which converts the mechanical energy provided by the compressor wheel into electrical energy and provides said electrical energy.

Drawings

Further details of the invention emerge from the following description of a preferred embodiment and the drawings. The attached drawings are as follows:

fig. 1 shows a schematic representation of a supercharging device for an internal combustion engine of a motor vehicle according to a first embodiment of the present invention; and

fig. 2 shows a schematic view of a supercharging device according to the invention according to a second embodiment.

Detailed Description

In the figures, identical or functionally identical elements have identical reference numerals.

Fig. 1 shows a schematic view of a first embodiment of a drive device, designated as a whole by 1, for a motor vehicle, in particular for a motor vehicle (e.g. a passenger car). The drive device comprises an internal combustion engine 2, which is designed, for example, as a reciprocating piston machine. The internal combustion engine 2 has an engine housing 3, which is designed, for example, as a cylinder housing, in particular as a cylinder crankcase, and by means of which a plurality of combustion chambers 4 in the form of blocks are formed. The drive 1 furthermore comprises a charging device 5, by means of which compressed air can be supplied to the internal combustion engine 2, in particular to the combustion chambers 4. The drive 1, in particular the charging device 5, comprises an air intake section (ansaugrakt) 6 through which air can flow, by means of which air can be conducted into the combustion chamber and in particular into the combustion chamber 4. This enables the air to be supplied to the internal combustion engine 2 via the intake section 6. The combustion chambers 4 are supplied with air compressed by means of the supercharging device 5 and with fuel, in particular liquid fuel, for operating the internal combustion engine 2, so that a fuel-air mixture is formed in the respective combustion chamber 4. The fuel-air mixture is combusted, whereby exhaust gases of the internal combustion engine 2 are produced. In this case, an exhaust gas section (Abgastrakt)7 is provided through which the exhaust gas of the internal combustion engine 2 can flow, by means of which the exhaust gas can be conducted out of the respective combustion chamber 4. An air filter 8 is provided in the intake section 6, by means of which air that has not been compressed first is filtered.

The charging device 5 comprises at least one exhaust-gas turbocharger 9 having a compressor 10 arranged in the intake section 6 and a turbine 11 arranged in the exhaust section 7. The turbine 11 comprises a turbine 12 which can be driven by the exhaust gases of the combustion engine 2. The compressor 10 comprises a first compressor wheel 13 arranged in the intake section 6, which can be driven by a turbine 12. Here, the turbine 12 and the compressor wheel 13 are components of a rotor 14 of the exhaust-gas turbocharger 9. The rotor 14 also comprises a shaft 15 to which both the compressor wheel 13 and the turbine wheel 12 are connected in a rotationally fixed manner. Thereby, the compressor impeller 13 can be driven by the turbine 12 via the shaft 15. By driving the compressor wheel 13, the air supplied to the combustion chamber 4 is compressed by means of this compressor wheel 13, wherein said compressed air is also referred to as charge air.

Furthermore, a motor-driven compressor 16 is provided, which has a second compressor wheel 17 and an electric motor 18. The electric machine 18 has a stator, which is not visible in fig. 1, and a rotor, which is rotatable relative to the stator about a rotational axis 19. The rotor comprises a shaft 20 which is rotatable about an axis of rotation and to which the second compressor wheel 17 is connected in a rotationally fixed manner. The second compressor wheel 17 can be driven electrically by the electric motor 18 via the shaft 20. The compressor wheel 17 is rotated about an axis of rotation 19 by driving the compressor wheel 17, and the air supplied to the respective combustion chambers 4 is compressed by means of the compressor wheel 17. For example, the compressor wheels 13 and 17 are connected or arranged parallel to one another, so that the compressor wheels 13 and 17 can be operated parallel to one another, for example. In particular, it is conceivable to supply compressed air by means of the compressor wheel 13 to at least one first combustion chamber of the combustion chambers 4 and in parallel by means of the compressor wheel 17 to at least one second combustion chamber of the combustion chambers 4, which is different from the first combustion chamber.

In order to be able to avoid so-called compressor pumping of the compressor wheel 13 or of the compressor 10, the first compressor wheel 13 or of the compressor 10 is assigned a thrust air circulation device (Schub-umlufeinrichtung) 21, by means of which at least a part of the air compressed by means of the compressor wheel 13 can branch off from the intake section 6 at a first position S1 arranged downstream of the first compressor wheel 13 and can be returned from the first position S1 to a second position S2 arranged upstream of the first compressor wheel 13 in the event of a reduction in the load of the internal combustion engine 2. In other words, for example, if a load reduction of the internal combustion engine 2 occurs (wherein a load reduction is also referred to as unloading), the air compressed by the compressor wheel 13 is branched off from the intake section 6 at the first position S1 and is introduced, for example, into the return line 22 of the thrust air circulation device 21. The return line 22 is fluidly connected to the intake section 6 at positions S1 and S2, in particular to the air line 23 of the intake section 6, so that air compressed, for example, at position S1 by means of the compressor wheel 13 can flow out of the intake section 6 or of the air line 23 and into the return line 22. The air which branches off and flows through the return line 22 is returned by the return line 22 from the first position S1 to the second position S2 and can flow out of the return line 22 at the second position S2 and into the intake section 6 or into the air line 23. This allows, for example, a branch air to circulate or to circulate, since the branch air can flow from the point S2 to the compressor wheel 13 and can be compressed again by means of the compressor wheel 13.

For example, the air is compressed to a boost pressure by the compressor wheel 13. By branching off and returning the air compressed by means of the compressor wheel 13, a removal of the boost pressure can be achieved, so that a compressor pumping of the compressor 10 can be avoided. The elimination of boost pressure is also referred to as boost pressure elimination. In the case of a boost pressure elimination, for example, the air which branches off and flows through the return line 22 is depressurized.

Since the internal combustion engine 2 is equipped with the supercharging device 5, the internal combustion engine 2 is also referred to as a turbine engine. In the case of such a turbine engine, it is desirable to reduce the air supply into the combustion chamber 4 as quickly as possible when unloading and thus to carry out the aforementioned charge pressure elimination particularly quickly. The unloading and thus the reduction of the air transport is achieved, for example, by: the throttle 24 arranged in the intake section 6 is at least partially closed. In this case, a throttle 24 is arranged downstream of the compressor wheels 13 and 17 and upstream of the combustion chamber 4 and serves to regulate the quantity or quality of the air to be supplied to the combustion chamber 4. In this case, the charge pressure is eliminated upstream or upstream of the throttle 24 and in particular by the return flow of the air compressed by the compressor wheel 13, for example via the compressor wheel 13, in the opposite direction to the intake flow direction.

This can often lead to acoustic anomalies, whereby the corresponding vehicle requirements can no longer be met. Furthermore, the energy contained in the compressed branched air is usually lost unused. In the unloaded case, the higher the boost pressure, the longer the boost pressure cancellation lasts and the more likely the sound abnormality occurs. For this reason, a thrust air circulation device 21 is used, which thrust air circulation device 21 usually has a thrust air circulation valve. A backflow of the air compressed by means of the compressor wheel 13, which backflow is provided for the purpose of removing the boost pressure and is directed counter to the suction flow direction via the compressor wheel 13, can be avoided by the thrust air circulation device 21, since the compressed air can be returned via the return line 22. In this case, the branched and recirculated air bypasses the compressor wheel 13, so that the branched air recirculated to the point S2 does not flow through the compressor wheel 13 or through the compressor wheel 13. However, in the case of a conventional supercharging apparatus, when a thrust air circulation device is used, energy contained in branched compressed air is lost without being utilized. However, this can now be avoided in the case of the charging device 5.

In order to achieve a particularly efficient and energy-saving operation, the charging device 5 is designed to supply the second compressor wheel 17 with the branched-off air, so that the second compressor wheel 17 and, via the second compressor wheel 17, the electric motor 18 can be driven by the branched-off air flowing through the return line 22. In other words, in at least one first operating state, the second compressor wheel 17 is supplied with the air compressed by the compressor wheel 13, so that the second compressor wheel 17 and, via the second compressor wheel 17, the electric motor 18 are driven by the branched-off air compressed by the compressor wheel 13.

In the case of a commonly used thrust air circulation valve, said boost pressure cancellation is achieved by recirculating the boost air via the compressor 10. For this purpose, the compressed charge air is returned via the thrust air recirculation valve to position S2, and is expanded there, position S2 being provided in the low-pressure region of the intake section 6. In contrast, the position S1 is arranged in the high-pressure region of the intake section 6, since at the position S1 there is a higher pressure than at the position S2. After returning the compressed air to position S2, the air is recompressed by compressor 10. In this case, the charge pressure reduction takes place relatively slowly, and the energy contained in the air compressed by the compressor wheel 13 is no longer used and is converted primarily into heat.

In contrast, an energy recovery device is provided in the supercharging device 5. Within the framework of energy recovery, the compressor wheel 17 and, via the compressor wheel, the electric motor 18 are driven by the branched-off air flowing through the return line 22.

In at least one second operating state, which is different from the first operating state, the electric machine 18 is operated, for example, in motor mode operation and thus as an electric motor. For this purpose, the electric machine 18 is supplied, for example, with electrical energy or current, which is stored in an energy storage device, not shown in fig. 1. By operating the electric motor 18 in motor mode, the compressor wheel 17 is driven by the electric motor 18 and thereby rotates about the axis of rotation 19 in a first direction of rotation, whereby the air flowing through the return line 22 is compressed and fed to the combustion chamber 4.

In the first operating state described above, however, the compressor wheel 17 is driven by air which is compressed or compressed by means of the compressor wheel 13 and flows through the return line 22. Thereby, the energy contained in the branched air is converted into mechanical energy provided by the compressor wheel 17. Thereby causing the motor 18 to be driven by the compressor wheel 17 via the shaft 20. In a first operating state, the electric machine 18 is operated in generator mode and thus as a generator, which converts at least part of the mechanical energy provided by the compressor wheel 17 into electrical energy and provides said electrical energy. In this case, the compressor wheel 17 rotates about the axis of rotation 19 in a second direction of rotation opposite the first direction of rotation in the first operating state. In the first operating state, the compressor wheel 17 thus functions as a turbine or turbine, by means of which the electric motor 18, in particular the rotor of the electric motor 18, is driven. The branched air is depressurized by the compressor wheel 17, and can then flow into the air line 23 at the second position S2 and finally again to the compressor wheel 13.

In order to achieve the first operating state, the accumulated charge air is conducted to the low-pressure region and expanded via the compressor wheel 17 and thus via the electric compressor 16 in the unloaded state. This is achieved, for example, via a corresponding valve circuit in the intake section 6. In other words, a valve arrangement 25 is preferably provided, by means of which the respective flows of air through the return line 22 and through the air line 23 can be regulated. In other words, for example, the valve device 25 can be used to switch between the operating states, which are also referred to as operating modes.

Overall, it can be seen that, in the unloaded state, energy in the form of current can be obtained from the charge air compressed by means of the compressor wheel 13. Furthermore, acoustic interference noise can be avoided or kept particularly low compared to conventional thrust air circulation valves, since, for example, the charge pressure cancellation can be carried out particularly quickly and advantageously. In particular, the charge pressure compensation can be controlled or regulated better than in conventional thrust air circulation valves, so that undesirable noise can be avoided. It is thus possible in the case of the charging device 5 to achieve a particularly advantageous recovery of the air compressed by means of the compressor wheel 13 and a particularly rapid charging pressure drop elimination in the case of unloading.

Fig. 2 shows a second embodiment of the supercharging device 5. In the case of the first embodiment, at least a portion of the air flowing through the intake section 6 is branched off in front of the first compressor wheel 13 or upstream of the first compressor wheel 13. Instead of being compressed by means of the compressor wheel 13, the branched off air or the branched off portion is supplied to the second compressor wheel 17 and compressed by means of the compressor wheel 17 or by means of the electric compressor 16, so that, for example, the compressors 10 and 16 work in parallel.

In the case of the second embodiment, however, for example, a series operation of the compressors 10 and 16 is provided. For this purpose, the air flowing through the intake section 6 is first compressed by the compressor wheel 13 (in particular in the supercharging mode shown by the arrow 28 in fig. 2). At least a portion of the air compressed by means of the compressor wheel 13 is supplied via a line 30 to the compressor wheel 17 and is compressed again or further by means of the compressor wheel 17. The check valve 26 ensures that the air compressed by the compressor wheel 17 cannot flow back to the first compressor wheel 13. Here, the line 30 is fluidly connected with a first air line leaving the compressor wheel 13 at a location disposed downstream of the compressor wheel 13. Furthermore, the conduit 30 is fluidly connected with a second air conduit leading to the compressor wheel 17 at a location disposed downstream of the compressor wheel 13. At least the part of the air compressed by the compressor wheel 13 can thereby be branched off from the first air line by means of the line 30 and introduced into the second air line or into the second air line. The branch portion is then led to the compressor wheel 17 by means of a second air line. In this case, in particular during the charging operation, the valve 27 arranged in the line 30 is open.

In fig. 2, the arrow 29 shows the above-described boost pressure cancellation. With the elimination of the charge pressure, the flow cross section of the air intake section 6 through which air can flow is at least reduced or at least partially blocked by the throttle 24 in that: the throttle 24 is at least partially closed. Thereby reducing the air supply to the combustion chamber 4 (in particular compared to a supercharging operation carried out before the boost pressure is eliminated). In addition, the thrust air circulation device 21, in particular its thrust air circulation valve, is then opened and the valve 27 arranged in the line 30 is closed, as a result of which air flows through the compressor wheel 17 and thus through the electric compressor 16, so that the electric motor 18 of the electric compressor 16 can be operated in the described manner in generator mode.

List of reference numerals

1 drive device

2 internal combustion engine

3 Engine casing

4 combustion chamber

5 supercharging device

6 air suction section

7 off-gas section

8 air filter

9 exhaust gas turbocharger

10 compressor

11 turbine

12 turbine

13 first compressor impeller

14 rotor

15 shaft

16 electric compressor

17 second compressor impeller

18 electric machine

19 axis of rotation

20 shaft

21 thrust air circulation device

22 return line

23 air pipeline

24 air throttle

25 valve device

26 check valve

27 valve

28 arrow head

29 arrow head

30 pipeline

S1 first position

S2 second position