Exhaust gas turbocharged internal combustion engine comprising a radial compressor with a guide device arranged in the diffuser and a method for operating such an internal combustion engine

Abstract

A turbocharged internal combustion engine comprising an intake system (1) for supplying charge air, an exhaust system for removing exhaust gas and at least one exhaust turbocharger comprising a radial turbine arranged in the exhaust system and a compressor (2) arranged in the intake system (1), which is a radial compressor (2a), wherein - the compressor (2) is equipped with at least one impeller (2c) mounted on a rotatable shaft (2d) in a compressor housing (2b), - a diffuser (7) is formed in the compressor housing (2b) downstream of the at least one impeller (2c), - in the diffuser (7) guide vanes (5b) of a guide device (5) are arranged, and - the guide device (5) comprises an annular support (5a) which accommodates the guide vanes (5b) of the guide device (5), and - the ring-shaped support (5a) together with guide vanes (5b) is designed as a support (5a) rotating around the shaft (2d) of the compressor (2). characterized by the fact that An electric auxiliary drive (6) is provided for the on-demand drive of the annular carrier (5a), with which a rotary motion can be imposed on the annular carrier (5a) in at least one direction of rotation, wherein the auxiliary drive (6) is an electric motor comprising a stator (6a) and a rotor (6b), and wherein the stator (6a) is at least also arranged and mounted in the compressor housing (2b) and wherein the stator (6a) comprises an energizable coil (6a') for generating a magnetic field.

Description

[0001] The invention relates to a supercharged internal combustion engine having the features of the preamble of claim 1.

[0002] Furthermore, the invention relates to a method for operating such an internal combustion engine with the features of the preamble of claim 11.

[0003] A compressor according to DE 102 38 658 A1 comprises a rotatably mounted compressor wheel in a compressor housing and a diffuser arranged downstream of the compressor wheel, which is equipped with a variably adjustable diffuser geometry. The diffuser geometry comprises adjustable guide vanes, each rotatably mounted on a guide vane shaft, and a rotatable adjusting ring that acts on the guide vanes. The adjusting ring has adjusting elements that act on the guide vanes in the direction of rotation at a distance from the respective guide vane shaft.

[0004] A guide device with adjustable guide vanes according to EP 1 811 135 A1 is equipped with a drive for the adjustable guide vanes. A drive pin and an adjusting lever are each equipped with a coordinated pair of surfaces that slide against each other during operation when the guide vanes are adjusted. To adjust the guide vane, the adjusting ring is moved, causing the drive pin attached to the adjusting ring to slide in an elongated groove in the adjusting lever and exert a force on the adjusting lever.

[0005] DE 43 12 077 C1 relates to an exhaust gas turbocharger for a supercharged internal combustion engine, wherein the exhaust gas turbocharger has at least one turbine and one compressor, and the turbine comprises an inflow side and an outflow side as well as a turbine wheel, a turbine housing with a spiral flow channel and a variable guide vane ring, and the compressor has a pressure side and a suction side, and a line is led from the pressure side of the compressor into a chamber in the turbine housing that is separated from the spiral flow channel.In order to design a generic exhaust gas turbocharger in such a way that, when cooling turbine components by the charge air, it is possible to simultaneously use the energy contained in the charge air, it is proposed that a connecting line opens out of the chamber and is connected to the inlet side of the turbine, and that the flow connection between the pressure side of the compressor and the inlet side of the turbine is controllable with a part of the variable guide vane ring.

[0006] The radial compressor according to DE 41 26 907 A1 has a guide vane diffuser with a plurality of guide vanes arranged around an impeller to convert the kinetic energy of the fluid conveyed by the impeller into pressure. The diffuser has pivoting guide vanes that are unevenly distributed among the stationary guide vanes.

[0007] WO 96 / 13668 A1 describes a burst-protection-optimized casing for a radial compressor, which has a diffuser with guide vanes. The radial guide vane or the guide vanes connected to one casing wall support a shroud that is positively connected to the second casing wall. In particular, this positive connection is designed like a bayonet lock, meaning that hooks on the shroud engage tabs on the other casing wall after the two casing walls are rotated against each other. Various welded joints between the shroud and the guide vanes are also presented.

[0008] The turbocharged internal combustion engine known from the utility model DE 20 2014 104 419 U1 with - an intake system for supplying charge air, - an exhaust gas removal system for removing the exhaust gas, and - at least two exhaust gas turbochargers connected in series, each comprising a turbine arranged in the exhaust gas discharge system and a compressor arranged in the intake system, of which a first exhaust gas turbocharger serves as a low-pressure stage and a second exhaust gas turbocharger as a high-pressure stage, wherein the second turbine of the second exhaust gas turbocharger is arranged upstream of the first turbine of the first exhaust gas turbocharger, is characterized by the fact that - the second turbine is a radial turbine, the outlet region of which runs coaxially to the shaft of the radial turbine and is designed so that the outflow of the exhaust gas from the radial turbine is essentially axial, and that - the first turbine is an axial turbine, the inlet region of which runs coaxially to the shaft of the axial turbine and coaxially to the outlet region of the second turbine and is designed so that the inflow of the exhaust gas to the axial turbine is essentially axial.

[0009] A turbomachine with adjustable-angle diffuser blades is presented in EP 0 719 944 A2, using a centrifugal pump. Accordingly, the performance of a diffuser is to be significantly improved by using adjustable-angle diffuser blades that can be adjusted to a wide range of blade angles to create a variable opening size between adjacent blades.

[0010] An internal combustion engine of the type mentioned above is used as a motor vehicle drive. For the purposes of the present invention, the term "internal combustion engine" encompasses diesel engines and gasoline engines, but also hybrid internal combustion engines that utilize a hybrid combustion process, as well as hybrid drives that, in addition to the internal combustion engine, comprise an electric motor that can be connected to the internal combustion engine for driving purposes, which absorbs power from the internal combustion engine or delivers additional power as a switchable auxiliary drive.

[0011] In recent years, there has been a trend toward small, highly turbocharged engines. Turbocharging is primarily a power-enhancing process that compresses the air required for the engine's combustion process. The economic importance of these engines for the automotive industry continues to grow.

[0012] An exhaust gas turbocharger is often used for charging, with a compressor and a turbine arranged on the same shaft. The hot exhaust gas flow is fed to the turbine and expands, releasing energy in the turbine, which causes the shaft to rotate. The energy transferred from the exhaust flow to the turbine and finally to the shaft is used to drive the compressor, which is also arranged on the shaft. The compressor conveys and compresses the charge air fed to it, thereby supercharging the cylinders. An intercooler is often provided downstream of the compressor in the intake system to cool the compressed charge air before it enters at least one cylinder. The cooler lowers the temperature and thus increases the density of the charge air, so that the intercooler also contributes to better filling of the cylinders, i.e. to a larger air mass. Compression occurs through cooling.

[0013] The advantage of an exhaust gas turbocharger over a mechanical supercharger is that there is no mechanical connection between the charger and the internal combustion engine for power transmission, or no connection is required. While a mechanical supercharger draws all of its power from the internal combustion engine, thus reducing the power delivered and adversely affecting efficiency, the exhaust gas turbocharger utilizes the exhaust energy from the hot exhaust gases.

[0014] As already mentioned, turbocharging serves to increase performance. The air required for the combustion process is compressed, allowing a larger air mass to be supplied to each cylinder per combustion cycle. This allows the fuel mass and thus the mean effective pressure to be increased.

[0015] Turbocharging is a suitable means of increasing the power of an internal combustion engine while maintaining the same displacement, or reducing the displacement while maintaining the same power. In either case, turbocharging leads to increased package power and a more favorable power-to-weight ratio. Reducing the displacement allows the load spectrum to shift toward higher loads, where specific fuel consumption is lower.

[0016] Turbocharging therefore supports the constant effort in the development of internal combustion engines to minimize fuel consumption, i.e. to improve the efficiency of the internal combustion engine.

[0017] Another fundamental goal is to reduce pollutant emissions. Turbocharging can also be effective in meeting this challenge. With a targeted design of the turbocharging system, advantages in efficiency and exhaust emissions can be achieved.

[0018] The design of exhaust gas turbocharging often presents difficulties, although the aim is generally to achieve a noticeable increase in performance in all speed ranges.

[0019] According to the state of the art, however, a torque drop when a certain speed n is undercut is mot This torque drop becomes understandable when one considers that the boost pressure ratio depends on the turbine pressure ratio. For example, if the engine speed n mot This leads to a smaller exhaust gas mass flow and thus a lower turbine pressure ratio. As a result, the boost pressure ratio and boost pressure also decrease at lower engine speeds, which translates into a drop in torque.

[0020] In principle, the drop in boost pressure can be counteracted by reducing the turbine cross-section and the associated increase in the turbine pressure ratio. However, this only shifts the torque drop further to lower engine speeds. Furthermore, this approach—i.e., reducing the turbine cross-section—has its limitations, as exhaust backpressure increases upstream of the turbine toward larger exhaust gas volumes, which adversely affects the charge cycle and increases fuel consumption.

[0021] The torque characteristics of a turbocharged internal combustion engine are attempted to be improved by various measures according to the state of the art.

[0022] For example, by designing a small turbine cross-section and simultaneously blowing off exhaust gases. This type of turbine is also known as a wastegate turbine. If the exhaust gas mass flow exceeds a critical value, a portion of the exhaust gas flow is diverted past the turbine via a bypass line as part of the so-called exhaust gas blowoff. This approach has the disadvantage that the boosting behavior is inadequate at higher speeds or with larger exhaust gas volumes.

[0023] The exhaust gas turbocharger can also be designed for high engine speeds, i.e., large exhaust gas volumes, with a large turbine cross-section. The intake system is preferably designed to achieve dynamic turbocharging through wave action at low engine speeds. The disadvantages of this approach are the high construction complexity and the sluggish response during engine speed changes.

[0024] The torque characteristics of a supercharged internal combustion engine can be further improved by several turbochargers arranged in parallel, i.e. by several turbines arranged in parallel with a smaller turbine cross-section, whereby turbines are successively switched on as the exhaust gas quantity increases - similar to a register supercharging.

[0025] The torque characteristics can also be advantageously influenced by connecting several exhaust turbochargers in series. By connecting two exhaust turbochargers in series, one of which serves as the high-pressure stage and one as the low-pressure stage, the compressor characteristic map can be advantageously expanded, both to accommodate smaller and larger compressor flows.

[0026] In particular, with the exhaust gas turbocharger serving as the high-pressure stage, it is possible to shift the surge limit towards smaller compressor flows, whereby high boost pressure ratios can be achieved even at low compressor flows, which significantly improves the torque characteristics in the lower speed range. This is achieved by designing the high-pressure turbine for small exhaust gas mass flows and providing a bypass line through which more exhaust gas is directed past the high-pressure turbine as the exhaust gas mass flow increases. For this purpose, the bypass line branches off from the exhaust gas removal system upstream of the high-pressure turbine and flows back into the exhaust gas removal system upstream of the low-pressure turbine. A shut-off element is arranged in the bypass line to control the exhaust gas flow past the high-pressure turbine.

[0027] The response of an internal combustion engine charged in this way is significantly improved compared to a comparable internal combustion engine with single-stage charging, since the smaller high-pressure stage is less sluggish and the rotor of a smaller-sized exhaust gas turbocharger can be accelerated more quickly.

[0028] To achieve cost-effective exhaust gas turbocharging, the internal combustion engine according to the invention is equipped with only one or at least one exhaust gas turbocharger. Compared to the provision of multiple exhaust gas turbochargers, the provision of a single exhaust gas turbocharger also offers weight advantages. Furthermore, the space required for the turbocharging device in the engine compartment is reduced.

[0029] The response of a single-stage turbocharged internal combustion engine suffers if the compressor is equipped with a large impeller to generate high boost pressure at full load or higher speeds, the impeller of which is slower and therefore cannot accelerate as quickly.

[0030] Such a compressor proves unsatisfactory, particularly at lower compressor flows, i.e., smaller charge air volumes. If the charge air volume decreases, the surge limit in the compressor map is reached comparatively early, i.e., compared to two-stage turbocharging. At lower compressor flows, sufficiently high boost pressure cannot be generated, which noticeably deteriorates the torque characteristics of the internal combustion engine in the lower speed range. Compressor surge is likely. At least partial flow reversal in the compressor can be observed. This is accompanied by increased noise emissions.

[0031] In order to counteract the effects described above and to improve the torque characteristics in the lower speed range, radial compressors according to the state of the art are equipped with a guide device which comprises guide vanes and is arranged downstream of the at least one impeller in the housing diffuser.

[0032] Such a guide device is described, for example, in DE 603 ​​07 571 T2, whose guide device comprises a - preferably rotatable - ring that accommodates a plurality of pivotable guide elements. The ring can only be rotated within a limited angular range and, in addition to providing movable support for the guide elements, serves, in particular, to coordinate the adjustment of the guide elements.

[0033] The guide device as such serves to convert the kinetic energy of the compressed charge air into a higher static pressure and thus to increase the boost pressure ratio of the compressor, especially with small charge air quantities.

[0034] In contrast to the rotor blades of at least one rotating impeller, the guide vanes of the guide vane system do not rotate. This means that the guide vanes are stationary, but not completely immobile, but rather rotatable, allowing the outflowing charge air to be influenced. The guide vane system of DE 603 ​​07 571 T2 is an adjustable guide vane system.

[0035] Against the background of the above, it is an object of the present invention to provide a supercharged internal combustion engine according to the preamble of claim 1, the exhaust gas turbocharging of which is further improved.

[0036] A further sub-object of the present invention is to provide a method for operating such an internal combustion engine.

[0037] The first sub-task is achieved by a supercharged internal combustion engine with an intake system for supplying charge air, an exhaust gas discharge system for discharging exhaust gas and at least one exhaust gas turbocharger, which comprises a radial turbine arranged in the exhaust gas discharge system and a radial compressor arranged in the intake system, wherein - the compressor is equipped with at least one impeller mounted on a rotatable shaft in a compressor housing, - a diffuser is formed in the compressor housing downstream of the at least one impeller, - guide vanes of a guide device are arranged in the diffuser, and - the guide device comprises an annular support which receives the guide vanes of the guide device, and - the annular support together with guide vanes is designed as a support rotating around the shaft of the compressor, which is characterized in that an auxiliary electric drive is provided for driving the carrier as required, with which an orbital movement in at least one direction of rotation can be imposed on the annular carrier, wherein the auxiliary drive is an electric motor which comprises a stator and a rotor, and wherein the stator is at least also arranged and mounted in the compressor housing and wherein the stator comprises an energizable coil for building up a magnetic field.

[0038] In contrast to the ring of DE 603 ​​07 571 T2, which can only be rotated within a limited angular range in order to adjust the guide elements in unison, the annular carrier of the internal combustion engine according to the invention is a rotating carrier, so that the carrier, including the guide vanes, like the at least one rotating impeller, rotates or can rotate around the compressor shaft as soon as an auxiliary electric drive provides the required drive power. However, in contrast to the impeller, which is rotationally fixed to the compressor shaft, the carrier is rotatable relative to the compressor shaft.

[0039] The control device according to the invention can be used to advantageously influence the compressor characteristic map or the operating behavior of the compressor.

[0040] For small charge air quantities, when there is a risk of the compressor over-surging and a sufficiently high boost pressure is not available upstream of the cylinders, the guide device according to the invention can be used as a radial fan to convey the charge air flow through the compressor. In this way, backflow in the compressor, i.e., flow reversal, and the associated noise emissions can be prevented. The torque characteristics of the internal combustion engine in the lower speed range are noticeably improved. The bladed carrier is driven by an auxiliary drive, preferably in the opposite direction to the at least one impeller of the compressor.

[0041] With the guide device according to the invention, the compressed charge air flow can be influenced in general, and not only when there is a risk of surge. Thus, by means of a suitable rotational movement of the bladed carrier, the angle of attack of the charge air flow exiting the rotor assembly upon entering the guide device can be influenced. The conversion of the kinetic energy of the compressed charge air into static pressure can be optimized in this way. This allows the boost pressure ratio of the compressor to be increased, particularly with small charge air volumes. The bladed carrier is driven by an auxiliary drive, preferably in the same direction as at least one impeller of the compressor.

[0042] This solves the first problem underlying the invention, namely providing a supercharged internal combustion engine whose exhaust gas turbocharging is further improved.

[0043] According to the invention, the compressor of the at least one exhaust gas turbocharger is a radial compressor. A radial compressor is a compressor whose outflow from the rotor blades is essentially radial. In the context of the present invention, "essentially radial" means that the velocity component in the radial direction is greater than the axial velocity component. This design allows for tight packaging of the exhaust gas turbocharger and thus of the charging system as a whole. The compressor housing can be designed as a spiral or helical housing, whereby the deflection of the charge air flow in the compressor of the exhaust gas turbocharger is advantageously used to guide the compressed charge air via the shortest path from the outlet side, on which the turbine of the exhaust gas turbocharger is often arranged, to the inlet side.

[0044] According to the invention, the turbine of the at least one exhaust gas turbocharger is a radial turbine. This embodiment also allows for a tight packaging of the exhaust gas turbocharger and thus the turbocharging system as a whole. A radial turbine is a turbine whose inflow is essentially radial.

[0045] Advantageous embodiments are those in which the compressor of the at least one exhaust gas turbocharger has an inlet region that runs coaxially to the compressor shaft and is configured such that the charge air flows to the compressor essentially axially. With an axial flow to the compressor, a deflection of the charge air flow in the intake system upstream of the at least one impeller is often eliminated, thereby avoiding unnecessary pressure losses in the charge air flow due to flow deflection and increasing the pressure of the charge air at the inlet to the compressor of the exhaust gas turbocharger.

[0046] Further advantageous embodiments of the supercharged internal combustion engine are discussed in connection with the subclaims.

[0047] Embodiments of the supercharged internal combustion engine are advantageous in which the annular carrier can be rotated in the opposite direction to the at least one impeller of the compressor by means of an auxiliary drive.

[0048] A rotational movement of the bladed carrier in the opposite direction to that of at least one impeller proves to be advantageous, especially with small charge air volumes, to counteract compressor surge. The guide device according to the invention is used as a radial fan to draw the charge air flow through the compressor. Flow reversal in the compressor is thus prevented.

[0049] Also advantageous are embodiments of the supercharged internal combustion engine in which the annular carrier can be rotated in the same direction as at least one impeller of the compressor by means of an auxiliary drive.

[0050] A rotational movement of the bladed carrier in the same direction as at least one impeller proves advantageous in converting the kinetic energy of the charge air flow into static pressure. The pressure at the compressor outlet and thus the boost pressure ratio of the compressor can be increased.

[0051] By means of a suitable rotational movement of the bladed carrier, the angle of attack of the charge air flow when entering the guide device can be influenced.

[0052] According to the invention, the auxiliary drive is an electric motor comprising a stator and a rotor. The electric motor allows for the bladed carrier to be driven as needed, independent of the current operating state of the internal combustion engine. An electric motor also provides a simple way to impose a circular motion on the annular carrier in different directions of rotation. For example, by reversing the direction of the electric current, it is possible to switch from a counter-rotational motion to a co-rotational motion.

[0053] According to the invention, the stator is at least also arranged and mounted in the compressor housing.

[0054] The stationary stator of a DC motor can be designed as a permanent magnet. In the inventive design, external excitation is achieved via an excitation coil, as in an AC motor. When current is passed through the coil, a magnetic field is generated.

[0055] According to the invention, the stator comprises an energizable coil for generating a magnetic field.

[0056] In this context, embodiments of the supercharged internal combustion engine in which the rotor is connected to the annular carrier are advantageous.

[0057] Inside the stator is a rotor, which is mounted and rotatable within the stator's magnetic field. The rotor can also have a coil with an iron core acting as an armature. When the rotor is energized, a magnetic field is also created in the rotor, which interacts with the stator's magnetic field, causing the rotor to rotate. In this way, electrical energy can be converted into kinetic energy, or movement of the rotor and thus of the carrier. The magnetic field in the rotor is fixed relative to the stator.

[0058] Embodiments of the supercharged internal combustion engine in which the rotor comprises an energizable coil for generating a magnetic field can therefore be advantageous.

[0059] However, embodiments of the supercharged internal combustion engine in which the rotor comprises at least one permanent magnet for generating a magnetic field are also advantageous. However, the stator must then comprise an energizable coil for generating a magnetic field.

[0060] In contrast to the previously described embodiment involving an energizable rotor coil, which requires a clocked current supply to the rotating rotor coil, this variant does not require current reversal and therefore no brushes. This type of electric motor is less complex, requires less space, and is therefore suitable for applications with limited installation space. A further advantage of the permanent magnet is the higher cogging torque when the electric motor is deactivated, i.e., when the stator coil, i.e., the excitation coil, is not energized.

[0061] In internal combustion engines with a bearing housing for accommodating the rotatable shaft of the compressor, embodiments in which the rotor is rotatably mounted on the bearing housing are advantageous.

[0062] Embodiments of the supercharged internal combustion engine are advantageous in which a collecting line for the compressed charge air is provided in the compressor housing downstream of the diffuser.

[0063] Advantageous embodiments of the turbocharged internal combustion engine include an intercooler located downstream of the compressor in the intake system. The advantages of intercooling have already been discussed.

[0064] In multi-stage turbocharging, designs in which an intercooler is arranged between the compressors in the intake system can be advantageous. The intercooler lowers the temperature of the charge air compressed in the low-pressure stage and thus also increases the density of the charge air, which improves compression in the high-pressure stage and allows the outlet temperature of the high-pressure stage to be lowered while maintaining the same overall pressure ratio of the turbocharging system. This also provides protection against thermal overload.

[0065] Advantageous embodiments of the supercharged internal combustion engine are those in which the guide vanes are designed to be movable relative to the annular support, so that the guide device is an adjustable guide device. The angle of the charge air flow upon entering the guide device can be optimized using adjustable guide vanes.

[0066] The second sub-task underlying the invention, namely to provide a method for operating a supercharged internal combustion engine of the type described above, is achieved by a method which is characterized in that the annular carrier is provided with a rotor below a first predeterminable speed n mot, 1 the internal combustion engine is forced to rotate in the opposite direction to the direction of rotation of at least one impeller of the compressor by means of an auxiliary drive.

[0067] What has been said in connection with the internal combustion engine according to the invention also applies to the method according to the invention.

[0068] Especially at low speeds n mot Due to the small amounts of charge air then present, there is a risk of pumping. According to the invention, the guide device is then preferably used as a radial fan to draw the charge air flow through the compressor.

[0069] Advantageous are process variants in which the annular carrier is subjected to a rotational speed above a second predeterminable speed n mot, 2 the internal combustion engine is forced to rotate in the same direction as the direction of rotation of at least one impeller of the compressor by means of an auxiliary drive.

[0070] At higher speeds n mot and larger charge air quantities, it is not necessary to promote the charge air flow through the compressor by means of a radial fan, so that the bladed carrier can be used to optimize the angle of attack or to convert the kinetic energy of the charge air flow into static pressure as effectively as possible.

[0071] Therefore, process variants are also advantageous in which, starting from an opposite rotational movement of the carrier when a third preset speed n is exceeded, mot, 3the internal combustion engine, the rotational movement of the carrier is reversed, so that the annular carrier is forced by means of an auxiliary drive to rotate in the same direction as the direction of rotation of at least one impeller of the compressor.

[0072] Process variants in which the auxiliary drive is switched off, allowing the guide system to be used as a non-rotating static guide system, are generally advantageous. In this case, the guide system is a static guide system, with the cogging torque of the electric drive ensuring sufficient stationary fixation.

[0073] In the following, the invention is explained using an embodiment according to the Fig. 1 and Fig. 2 is described in more detail. Here: Fig. 1 schematically shows the compressor arranged in the intake system of a first embodiment of the internal combustion engine together with the guide device, partly in half section, and Fig. 2 schematically shows in side view the impeller of the compressor of the Fig. 1 illustrated embodiment including guidance device.

[0074] Fig. 1 shows schematically the compressor 2 arranged in the intake system 1 of a first embodiment of the internal combustion engine together with the guide device 5, partly in half section.

[0075] To supply the charge air to the cylinders, the internal combustion engine has an intake system 1. For charging the cylinders, an exhaust gas turbocharger is provided, which comprises a turbine (not shown) arranged in the exhaust gas discharge system and a compressor 2 arranged in the intake system 1.

[0076] The compressor 2 is a radial compressor 2a, in whose housing 2b an impeller 2c comprising rotor blades 2e is mounted on a rotatable shaft 2d. The shaft 2d of the compressor 2 is rotatably mounted in a bearing housing 3. The compressor 2 of the exhaust gas turbocharger has an inlet region that runs coaxially to the shaft 2d of the compressor 2 and is designed so that the charge air flows essentially axially to the compressor 2 of the exhaust gas turbocharger. The compressor housing 2b is designed as a spiral housing, with the charge air flowing downstream of the impeller 2c through a diffuser 7, the flow cross-section of which increases in the flow direction due to the increasing distance from the shaft 2d. The diffuser 7 opens into a collecting line 4 for the compressed charge air, which spirals around the diffuser 7.

[0077] A guide device 5 is provided, which comprises an annular carrier 5a, which receives, i.e. carries, the guide vanes 5b of the guide device 5. The annular carrier 5a together with the guide vanes 5b is designed as a carrier 5a rotating around the shaft 2d of the compressor 2, wherein an auxiliary electric drive 6 is provided for the demand-driven drive of the carrier 5a, with which the annular carrier 5a can be forced to rotate in different, i.e. both, directions of rotation (see also Fig. 2).

[0078] In this case, the auxiliary drive 6 is an electric motor 6 comprising a stator 6a and a rotor 6b. The stator 6a is arranged and mounted in the compressor housing 2b and has an energizable coil 6a' for generating a magnetic field. When current is passed through this excitation coil 6a', an externally excited magnetic field is generated. The rotor 6b has a permanent magnet 6b' for generating a magnetic field, with the rotor 6b being arranged inside the stator 6a and rotatably mounted in the magnetic field of the stator 6a. The bearing 6c of the rotor 6b and thus the bearing 5c ​​of the annular carrier 5a connected to the rotor 6b is provided by the bearing housing 3.

[0079] If the stator 6a is energized, a magnetic field builds up in the stator 6a, which interacts with the magnetic field of the permanent magnet 6b', so that the rotor 6b and the annular carrier 5a connected to the rotor 6b rotate.

[0080] Fig. 2 shows schematically in side view the impeller 2c of the compressor 2 of the Fig. 1 illustrated embodiment including guide device 5. It is intended only as a supplement to Fig. 1, which is why reference is made to Fig. 1. The same reference numerals were used for the same components.

[0081] The annular support 5a together with guide vanes 5b can be rotated by means of an auxiliary drive in the opposite direction to the impeller 2c of the compressor 2 and in the same direction as the impeller 2c of the compressor 2, ie rotate (see double arrow on the outer circumference).

[0082] A counter-directional rotational movement of the bladed carrier 5a proves to be advantageous for avoiding pumping, wherein the guide device 5 is operated as a radial fan in order to suck the small quantities of charge air through the compressor.

[0083] A unidirectional rotation of the bladed carrier 5 supports the conversion of the kinetic energy of the charge air flow into static pressure. The boost pressure ratio of the compressor can be increased, thus improving the torque characteristics of the internal combustion engine.

[0084] By means of a suitable rotational movement of the bladed carrier 5a, the angle of attack of the charge air flow when entering the guide device 5 can be influenced. Reference symbol 1 intake system 2 compressors of the exhaust gas turbocharger 2a Radial compressor 2b Compressor housing of the exhaust gas turbocharger 2c wheel 2d compressor shaft 2nd blade 3 bearing housings 4 Collective line 5 Guidance device 5a ring-shaped support 5b Guide vane 5c Storage of the carrier 6 Electric auxiliary drive, electric motor 6a Stator 6a' coil of the stator, excitation coil 6b Rotor 6b' permanent magnet 6c Rotor bearing 7 Diffuser n mot Speed ​​of the internal combustion engine n mot, 1 first preset speed for an opposite direction of rotation n mot, 2 second preset speed for a same direction of rotation n mot, 3 third preset speed for reversing the direction of rotation

Claims

[1] Supercharged internal combustion engine with an intake system (1) for supplying charge air, an exhaust gas discharge system for discharging exhaust gas and at least one exhaust gas turbocharger, which comprises a radial turbine arranged in the exhaust gas discharge system and a compressor (2) arranged in the intake system (1), which is a radial compressor (2a), wherein - the compressor (2) is equipped with at least one impeller (2c) mounted on a rotatable shaft (2d) in a compressor housing (2b), - a diffuser (7) is formed in the compressor housing (2b) downstream of the at least one impeller (2c), - guide vanes (5b) of a guide device (5) are arranged in the diffuser (7), and - the guide device (5) comprises an annular support (5a) which receives the guide vanes (5b) of the guide device (5), and - the annular support (5a) together with guide vanes (5b) is designed as a support (5a) rotating around the shaft (2d) of the compressor (2) characterized by , that an auxiliary electric drive (6) is provided for driving the annular carrier (5a) as required, with which an orbital movement in at least one direction of rotation can be imposed on the annular carrier (5a), wherein the auxiliary drive (6) is an electric motor which comprises a stator (6a) and a rotor (6b), and wherein the stator (6a) is arranged and mounted at least also in the compressor housing (2b) and wherein the stator (6a) comprises an energizable coil (6a') for building up a magnetic field. [2] Supercharged internal combustion engine according to claim 1, characterized by that the annular carrier (5a) can be rotated in the opposite direction to the at least one impeller (2c) of the compressor (2) by means of an auxiliary drive (6). [3] Supercharged internal combustion engine according to claim 1 or 2, characterized bythat the annular carrier (5a) is rotatable in the same direction as the at least one impeller (2c) of the compressor (2) by means of an auxiliary drive (6). [4] Supercharged internal combustion engine according to one of the preceding claims, characterized by that the rotor (6b) is connected to the annular carrier (5a). [5] Supercharged internal combustion engine according to one of the preceding claims, characterized by that the rotor (6b) comprises an energizable coil for generating a magnetic field. [6] Supercharged internal combustion engine according to one of claims 1 to 4, characterized by that the rotor (6b) comprises at least one permanent magnet (6b') for building up a magnetic field. [7] Supercharged internal combustion engine according to one of the preceding claims, comprising a bearing housing (3) for receiving the rotatable shaft (2d) of the compressor (2), characterized by that the rotor (6b) is rotatably mounted on the bearing housing (3). [8] Supercharged internal combustion engine according to one of the preceding claims, characterized by that a collecting line (4) for the compressed charge air is provided in the compressor housing (2b) downstream of the diffuser (7). [9] Supercharged internal combustion engine according to one of the preceding claims, characterized by that a charge air cooler is arranged in the intake system (1) downstream of the compressor (2). [10] Supercharged internal combustion engine according to one of the preceding claims, characterized by that the guide vanes (5b) are designed to be movable relative to the annular support (5a), so that the guide device (5) is an adjustable guide device (5). [11] Method for operating a supercharged internal combustion engine according to one of the preceding claims, characterized by that the annular carrier (5a) below a first predeterminable speed n mot, 1the internal combustion engine is forced into a circular movement counter to the direction of rotation of at least one impeller (2c) of the compressor (2) by means of a connected auxiliary drive (6). [12] Method according to claim 11, characterized by that the annular carrier (5a) above a second predeterminable speed n mot, 2 the internal combustion engine is forced to perform a circular movement in the same direction as the direction of rotation of at least one impeller (2c) of the compressor (2) by means of a connected auxiliary drive (6). [13] Method according to claim 11 or 12, characterized by that, starting from an opposite rotational movement of the annular carrier (5a) when a third predeterminable speed n mot, 3the internal combustion engine, a rotational movement of the annular carrier (5a) is reversed, so that the annular carrier (5a) is forced by means of an auxiliary drive (6) to perform an orbital movement in the same direction as the direction of rotation of at least one impeller (2c) of the compressor (2). [14] Method according to one of claims 11 to 13, characterized by that the auxiliary drive (6) is switched off in order to use the guide device (5) as a non-rotating static guide device (5).

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