EP2952748B1 - Charging device for a combustion engine - Google Patents

Description

Field of the invention

The present invention relates to a charging device for an internal combustion engine, in particular in a vehicle, according to the preamble of claim 1. Such a charging device is known from US Pat. No. 6,102,672 A. or US 5 904 471 A known.

Background of the invention

Charging devices for internal combustion engines are known from the prior art, which compress the charge air of the internal combustion engine by means of a compressor. In the charging devices considered here, the compressor wheel is driven in the compressor by means of an electric motor.

Summary of the invention

It is an object of the present invention to provide a charging device for an internal combustion engine, which can be operated permanently at low cost production and low-maintenance operation. At the same time, the charging device should be very compact and lightweight.

The object is achieved by the features of claim 1. The dependent claims have advantageous embodiments of the invention the subject.

In one aspect, the charging device and the internal combustion engine are used in particular in a vehicle. The charging device comprises a compressor with a compressor housing and a compressor chamber. In the compressor room, a compressor wheel is arranged. The charging device further comprises an electric motor with a rotor and a stator. Furthermore, a motor housing is provided. In the motor housing, an engine compartment is formed. This serves to receive the stator and the rotor. A connection from the compressor room into the engine compartment allows one Pressure equalization between the compressor room and the engine compartment. This has the advantage that high pressure differences between the engine compartment and the compressor compartment can be avoided. As a result, the forces on the seals and the bearings, for example by high pressures without pressure equalization, can be avoided or reduced. This reduces the risk that lubricants or the like from the bearings and / or seals in the compressor chamber or the engine compartment are pressed and cause damage there.

The compressor housing is closed on the motor housing side facing by a rear wall, wherein the rear wall facing a wall of the motor housing, and wherein an inlet opening of the compound is arranged in the rear wall.

In addition, a power electronics circuit for controlling the electric motor is arranged in a receiving space which is arranged between the rear wall and the wall of the motor housing. The receiving space is hermetically sealed from the compressor room and the engine compartment. This has the advantage that no fluids and / or particles from the compressor chamber or the engine compartment can get into the receiving space with the power electronics circuit.

The compressor housing thus has an open side on its side facing the stator prior to assembly. This open side is located between the compressor wheel and the electric motor. The open side can be closed by means of the rear wall. To ensure the manufacturability and mountability of the charging device, this rear wall can be an independent, manufactured separately from the compressor housing component. The power electronics circuit is used to control the electric motor. This receiving space is hermetically sealed from the compressor room and opposite the engine compartment. The hermetic seal means in particular a seal both against gases and against liquids. In advantageous embodiments, the rear wall can be made of: plastic or metal, in particular thermoset, high temperature resistant Polyamide, fiber-reinforced plastic or aluminum. Furthermore, the rear wall may have a plurality of reinforcing ribs. The reinforcing ribs may extend radially outward starting from a central recess of the rear wall. In particular, the reinforcing ribs may be formed on the side of the rear wall facing the electric motor.

In one embodiment, 0.1 mm-0.6 mm, in particular 0.2 to 0.4 mm high nubs may be provided on the rear wall on a side facing the compressor, which provide a defined axial positioning of the rear wall relative to the compressor housing. The nubs may be convex in a further embodiment, so that they are easily deformable.

In embodiments, it can be provided that the direct connection from the compressor chamber into the engine compartment has a pipe socket in order to allow pressure equalization between the two chambers. This pipe socket extends in the axial direction through the rear wall, the receiving space and the wall of the motor housing in the engine compartment to form a direct fluid-conducting connection between the engine compartment and the compressor chamber. In this case, the pipe socket is designed so that only a connection between the compressor chamber and the engine compartment and no connection can be made in the receiving space. Preferably, it may be provided that the pipe socket is an integral part of the integrally manufactured rear wall. Furthermore, the pipe socket is advantageously eccentric to the shaft of the charging device.

The connection between the compressor chamber and the engine compartment to allow pressure equalization may include other components. Thus, for example, at least one membrane may be provided, for example a semi-permeable membrane, for selectively passing gases and retaining solid or liquid particles. The membrane may be mounted in the pipe socket, at the inlet opening on the rear wall and / or at an outlet of the pipe socket in the region of the engine compartment. Additionally or alternatively, a device may be provided which controls or controls the connection or the flow through the connection between the rooms. Such a device can be in shape a valve and / or a nozzle, for example a venturi, integrated. This has the advantage that over the connection between the compressor chamber and the engine compartment not only a pressure equalization is made possible, but at the same time the pressure compensation can be controlled or regulated and / or contamination by liquids or particles can be avoided.

In the compressor should be largely avoided that particles pass through the inlet opening of the connection or the pipe socket in the engine compartment. Such particles may in particular be burnt oil droplets or soot particles. In addition to the features already described, the following further different measures are provided to avoid this, which can be applied individually or in combination.

The compressor wheel has a certain diameter D1. The center of an inlet opening of the connection or the pipe socket in the rear wall can be spaced from a center M of the rear wall by a distance A1. The distance A1 is preferably between 0.2 * (D1 / 2) and 0.9 * (D1 / 2), in particular between 0.4 * (D1 / 2) and 0.8 * (D1 / 2).

In embodiments, it may be provided that at least one elevation for diverting the particles is formed on the side of the rear wall facing the compressor in the region of the inlet opening of the pipe socket. In particular, the at least one elevation extends in the circumferential direction. Furthermore, it is preferably provided that the at least one elevation is located completely around the inlet opening of the pipe socket. In particular, it is provided that one or more elevations in the circumferential direction are arranged sickle-shaped around the inlet opening. During operation of the charging device, the at least one elevation ensures that particles are at least very likely to be thrown past the inlet opening due to their inertia and, for example, are not removed with the condensate, but are fed to the combustion process in the internal combustion engine with the compressed air.

At least two elevations can be arranged. The surveys are preferably separated by a depression. An imaginary middle straight is defined passing through the center of the entrance opening and the center M of the rear wall. The depression extends along an imaginary auxiliary axis. Preferably, the auxiliary axis intersects the middle straight radially outside the inlet opening.

Preferably, there may be at least one first recess and a corresponding plurality of projections in the circumferential direction in front of and behind the inlet opening. The auxiliary axes of the first depressions then each have a first angle α1, β1 to the middle straight line and advantageously intersect the middle straight line radially outside the inlet opening.

Furthermore, second depressions and correspondingly further elevations may preferably be provided in the circumferential direction in front of and behind the first depressions. The auxiliary straight lines of the second depressions each have a second angle α 2, β 2 to the middle straight line and intersect the middle straight line radially outside the inlet opening.

The first and second angles (α1, β1, α2, β2) are each between 70 ° and 20 °, preferably between 60 ° and 25 °. Advantageously, the first angles (α1, β1) are smaller than the second angles (α2, β2). In particular, the first angles (α1, β1) are at most 95% of the second angles (α2, β2).

The compressor wheel has the diameter D1 (largest diameter of the compressor wheel). The entirety of the elevations may extend over a length L. The length L is measured perpendicular to the middle straight and parallel to a plane defined by the back wall. The length L is perpendicular to the axis of the shaft. Preferably, the length L is between 0.7 * D1 and 0.2 * D1, in particular between 0.6 * D1 and 0.3 * D1.

The entirety of the elevations may extend over a segment angle γ, measured with respect to the center point M of the rear wall and in the plane the back wall. The segment angle γ is preferably between 120 ° and 45 °, in particular between 100 ° and 60 °.

The radial inner edge of the elevations may follow an arc shape. The arcuate shape preferably has a continuously varying radius with respect to the midpoint M. In particular, a first radius R1 is defined on the middle straight, which increases to the outer ends of the elevations up to a second radius R2. Particularly preferably, the second radius R2 is at least 110% of the first radius R1.

A height H1 of the at least one elevation, measured in the axial direction, is preferably between 0.1 mm and 5 mm, in particular between 0.1 mm and 1 mm.

The edges of the at least one elevation are preferably rounded with a defined radius R3. The radius is preferably between 0.05mm and 0.1mm.

Preferably, the arrangement of the elevations and depressions is symmetrical to the middle straight, which runs through the center of the inlet opening and the center M of the rear wall.

These different features for configuring and positioning the entrance opening and elevations have been determined by calculations, simulations, and tests, and may be used singly or in synergistically cooperative combination to prevent particles from entering the engine compartment via the inlet and the connection. Contrary to the usual and logical solution, namely to seal the engine compartment, it has been recognized that the provision of a connection between the compressor chamber and the engine compartment, for example in the form of a raw neck, and the surveys described above is much easier and less expensive than the complete sealing of the engine compartment with appropriate pressure equalization.

As described above, the shaft protrudes through the wall of the motor housing into the compressor. At this point, a sealing point may preferably be formed in order to seal off the compressor chamber from the engine compartment. The sealing point is provided either as a non-contact seal or as a dynamic seal, in particular with at least one piston ring. However, in a preferred variant, in particular in the case of an aluminum motor housing, it is deliberately dispensed with a contacting seal, in particular with piston rings, in order to avoid "seizing" (notching) of the piston rings in the motor housing.

For hermetic sealing of the engine compartment relative to the receiving space is preferably a further seal between the compound, in particular in the form of a pipe socket, provided by the compressor chamber in the engine compartment and the wall of the motor housing.

In embodiments, a device may be provided to allow pressure equalization between the receiving space and the environment. In addition, it can be provided that extends from the power electronics circuit through the motor housing at least one electrical conductor to allow an electrically conductive connection between the power electronics circuit and the electric motor. The charging device may further include a bearing device for supporting a shaft connecting the rotor to the compressor wheel, the bearing device having a vibration damping device. By the vibration damping can be made possible, for example, a calmer and smoother and less vibration running the shaft.

Further details and features of the invention will be described with reference to the following figures.

Brief description of the figures

• FIG. 1 a sectional view of a charging device according to the invention according to an embodiment,
• FIG. 2 a detail of the first seal of the charging device according to the invention according to the embodiment,
• FIG. 3 a detail of the second seal of the charging device according to the invention according to the embodiment,
• FIG. 4 two views of a rear wall of the charging device according to the invention according to the embodiment,
• FIG. 5 a further view of the rear wall of the charging device according to the invention according to the embodiment,
• FIG. 6 a detail of the charging device according to the invention according to the embodiment with the lid removed,
• FIG. 7 Details of the configuration of the elevations on the rear wall according to an advantageous embodiment of the charging device
• FIG. 8 Details of the configuration of the elevations on the rear wall according to an advantageous embodiment of the charging device in section
• FIG. 9 View of a connector with integrated device for pressure equalization between the recording room and the surroundings
• The following is based on the FIGS. 1 to 9 a charging device 1 according to the embodiment described in detail.

FIG. 1 shows in sectional view the charging device 1 comprising a compressor 2. The compressor 2 has a compressor housing 3. In the compressor housing 3, a compressor 4 is arranged. This compressor 4 is located in the so-called compressor room.

Furthermore, the charging device 1 comprises an electric motor 5. The electric motor 5 is composed of a rotor 6 and a stator 7.

About a shaft 8, the rotor 6 rotatably connected to the compressor 4. By rotation of the electric motor 5 thus the compressor 4 is also set in rotation.

The compressor 4 and the rotor 6 are arranged coaxially, so that the shaft 8 is also the rotor shaft at the same time.

FIG. 1 shows an axial direction 18 corresponding to the shaft 8. Perpendicular to the axial direction 18 is a radial direction 19. Around the axial direction 18 around a circumferential direction 20 is defined.

Upon rotation of the electric motor 5 and thus upon rotation of the compressor impeller 4 air is sucked in the axial direction 18. About the compressor 2, the air is compressed in the radial direction 19 and fed to an internal combustion engine.

The charging device 1 further comprises a motor housing 9. In this motor housing 9, an engine compartment 10 is formed. The engine compartment 10 is closed on the side facing away from the compressor 2 by means of a cover 12. To the compressor 2 through the engine compartment 10 is limited by a wall 11 of the motor housing 9. The compressor housing 3 is open on its side facing the motor housing 9. This open side is closed by means of a rear wall 13. In particular, the rear wall 13 is made of plastic, in particular duroplastic, or of metal, in particular aluminum. In the production of plastic in particular high temperature resistant polyamide is used. Furthermore is preferably provided that the rear wall 13 is made of fiber-reinforced plastic.

On the rear wall 13, 0.1 mm-0.6 mm, in particular 0.2 to 0.4 mm high studs (not shown in the figures) may be provided on a side facing the compressor 2, which defines a defined axial positioning of the rear wall 13 provide relative to the compressor housing. The knobs may be convex so that they are easily deformable.

The motor housing 9 is connected with its wall 11 fixed to the compressor housing 3, in particular screwed. In this case, a receiving space 14 is formed between the rear wall 13 and the wall 11. In this receiving space 14 is a power electronics circuit 15 for power supply and control of the electric motor 5. The receiving space 14 is hermetically sealed against the compressor chamber and the engine compartment 10. A device 40 may be provided which allows a pressure equalization between the receiving space 14 and the environment. Further details of the device 40 for pressure equalization will be discussed below FIG. 9 described.

The shaft 8 is mounted with respect to the wall 11 of the motor housing 9 with a first bearing 16. Between the shaft 8 and the cover 12 is a second bearing 17th FIG. 3 shows between the outer ring of the first bearing 16 and the adjacent motor housing 9, two O-rings 38. These O-rings 38 are used inter alia as a device for vibration damping. The O-rings 38 can, as shown in a groove in the outer ring of the bearings 16 and 17 (see FIGS. 1 and 3 ) to sit. Additionally or alternatively, a groove in the motor housing 9 and the cover 12 may be provided. The O-rings 38 are preferably made of HNBR, rubber or rubber. The motor housing 9 and / or the lid 12 may be made of aluminum, for example. The outer ring of the bearings 16, 17 is usually made of steel. On the one hand, the O-rings 38 can avoid an unfavorable, chemically active combination of materials. On the other hand, the O-rings damped mechanical vibrations. The O-rings 38 thus ensure a chemical and mechanical decoupling. Additionally or alternatively, the device for Vibration damping at least one spring element (not shown). The spring element can be arranged, for example, in the axial direction 18 between the bearing 16 and the motor housing 9 and / or the bearing 17 and the cover 12 (for example, in the space between the bearing 17 and cover 12 to see FIG. 1 ).

The wall 11 of the motor housing 9 has an axially extending portion 37. Radial within this section 37 is the power electronics circuit 15 and corresponding to the receiving space 14th

For the hermetic sealing of the receiving space 14, at least a first seal 21 and a second seal 22 are provided. These seals 21, 22 are based on the detailed representations in the Figures 2 and 3 explained. FIG. 2 shows in detail the first seal 21. The compressor housing 3 has a first inner peripheral surface 24. The wall 11 has a first radial surface 25. On the rear wall 13, a first outer peripheral surface 23 is defined. The first seal 21 is disposed between the first radial surface 25 of the wall 11 and a second radial surface 26 of the compressor housing 3. Thus, the first seal 21 is subjected to force only in the axial direction 18. The compressor housing 3 has a second radial surface 26. The first seal 21 is fully disposed between the first outer peripheral surface 23, the first inner peripheral surface 24, the first radial surface 25, and the second radial surface 26 and clamped between the first radial surface 25 and the second radial surface 26 in the axial direction 18, thereby generating the sealing effect. The seal between the first radial surface 25 and the first seal 21 is not as pronounced as between the second radial surface 26 and the first seal 21 in order to position the rear wall 13 on the motor housing 9 during the compression.

In FIG. 3 are recesses in the rear wall 13 and the wall 11 can be seen, which serve to pass the shaft 8 from the engine compartment 10 into the compressor chamber. Further shows FIG. 3 in detail, the arrangement of the second seal 22. The second seal 22 is fully on a second outer peripheral surface 28 of Wall 11 arranged. Furthermore, a second inner circumferential surface 27 of the rear wall 13 rests against this second seal 22.

FIG. 1 shows an electrical conductor 29 in the form of a bolt. The electrical conductor 29 electrically conductively contacts the power electronics circuit 15 with the coils of the stator 7. For this purpose, the electrical conductor 29 protrudes through the wall 11. At this point, a third seal 30 is provided in the region of the wall 11. The third seal 30 is a seal applied to the electrical conductor 29 in a tubular manner. In order to avoid possible short circuits in the region of the electrical conductors, it can be provided that the third seal extends over at least half the length of the stator, preferably over at least two thirds of the length of the stator, in the axial direction. Preferably, the third seal has circumferential projections, in particular in the region of the through hole through the wall 11, to locally generate a greater contact pressure against the through hole in the wall 11. Thus, the third seal 30 serves not only to seal the through-hole in the wall 11, but also to electrically insulate the electrical conductor 29 from the stator 7.

In particular, three such electrical conductors 29 distributed along the circumference are used. The electrical conductors 29 extend over the entire axial length of the stator 7, so that the electrical conductors 29 can be contacted with the stator 7 in the region of the cover 12. That is, the electrical conductors 29 extend advantageously over the entire length of the stator in the axial direction 18. The contact between the stator 7 and electrical conductor 29 can thus, due to mounting reasons, on the side facing away from the compressor 2 of the stator 7. In particular, the electrical conductors 29 and the stator 7 can be electrically connected to each other, for example via a crimp connection. Due to the length of the electrical line 29 and the crimping on the side facing away from the power electronics circuit 15 mounting damage can be avoided by the crimping on the power electronics circuit 15. On the side facing away from the compressor 2 of the stator 7, the motor housing has a cover 12. Before mounting this cover 12 can on this page, the electrical conductors 29 with the windings on the stator. 7 be electrically connected, as described for example by crimping. Only then the lid 12 is mounted accordingly. Overall, the configuration and arrangement of the electrical conductors 29 thus has to take the advantages of a quick and easy installation with low risk for damage and without major losses in performance for the electrical connection in purchasing.

FIG. 6 shows a side facing away from the compressor 2 side of the motor housing 9 with disassembled lid 12. From this illustration, it can be clearly seen that with disassembled cover 12, the ends of the electrical conductors 29 and the stator 7 are accessible. Thus, prior to assembly of the lid 12, the ends of the electrical conductors 29 may be electrically conductively connected to the stator 7 as described above.

As FIGS. 1 and 3 show in detail, there is a non-contact fourth sealing point 31 between the wall 11 and the shaft 8. This fourth sealing point 31 is located in particular radially within the second seal 22nd

FIG. 4 shows in an isometric view and in a sectional view of the exact configuration of the rear wall 13. The rear wall 13 is an integrally manufactured component.

FIG. 4 shows in particular the exact arrangement of the first and second seals 21, 22 on the rear wall 13. The two seals 21, 22 are in particular adhesively bonded or vulcanized seals, which are arranged fully. Alternatively or additionally, the first seal 21 and / or the second seal 22 may be arranged in a groove in the rear wall 13 or a corresponding extension may be formed on the rear wall 13 which fits into a corresponding groove in the first seal 21 or second seal 22 sticks out.

Furthermore, the illustrations in FIG. 4 a plurality of reinforcing ribs 32, which are an integral part of the rear wall 13. The reinforcing ribs 32 are arranged in the radial direction 19 in a star shape and are located on the side facing the receiving space 14.

Another component of the rear wall 13 is a pipe socket 33, which serves as a connection between the compressor chamber and the engine compartment 10. This is located at a geodetic down position, ie below the shaft 8. As in particular FIG. 1 shows, the compound or the pipe socket 33 forms a fluid-conducting connection between the compressor chamber and the engine compartment 10. Via a fifth seal 35 of the pipe socket 33 is sealed against the wall 11. The pipe socket 33 allows pressure equalization between the compressor chamber and the engine compartment 10. In this case, the pipe socket 33 is formed so that only a connection between the compressor chamber and the engine compartment 10 and no connection takes place in the receiving space 14. It can be provided that the pipe socket 33 is an integral part of the integrally manufactured rear wall 13. The pipe socket 33 is located eccentrically to the shaft 8 of the charging device 1. The direct connection of the compressor chamber in the engine compartment has the advantage that high pressure differences between the engine compartment and the compressor chamber can be avoided. As a result, the forces on the seals and the bearings, for example by high pressures without pressure equalization, can be avoided or reduced. This reduces the risk that lubricants or the like from the bearings and / or seals in the compressor chamber or the engine compartment are pressed and cause damage there.

The connection between the compressor chamber and the engine compartment 10 to allow pressure equalization may include other components. Thus, for example, a membrane may be provided, in particular a semipermeable membrane in order to selectively pass gases and to retain solid or liquid particles. Such a membrane may be mounted in the embodiment shown in the figures in the pipe socket 33, at the inlet opening 34 on the rear wall 13 and / or at an outlet of the pipe socket 33 in the region of the engine compartment 10. Additionally or alternatively, a device may be provided which regulates or controls the connection or flow through the connection between the rooms. Such a device can be integrated in the form of a valve and / or a nozzle, for example a Venturi nozzle. This has the advantage that over the connection between the compressor chamber and the engine compartment not only a pressure equalization is made possible, but at the same time the pressure compensation can be controlled or regulated and / or contamination by liquids or particles can be avoided.

FIG. 5 shows a plan view of the compressor 2 facing side of the rear wall 13. Good to see that around the inlet opening 34 of the pipe socket 33 a plurality of elevations 36 are arranged. These elevations 36 extend in the circumferential direction 20 sickle-shaped around the inlet opening 34. By means of these elevations 36 particles are derived so that they are not likely to penetrate into the inlet opening 34 and thus into the pipe socket 33. It should be largely avoided that particles pass through the inlet opening 34 of the pipe socket 33 in the engine compartment 10. Such particles may in particular be burnt oil droplets or soot particles. An embodiment of the elevations 36 will be described below with reference to FIG FIGS. 1 . 4 . 5 . 7 and 8 described in more detail.

The compressor wheel has a certain diameter D1 (see FIG. 1 ). The center of an inlet opening 34 of the pipe socket 33 in the rear wall 13 is spaced from a center M of the rear wall by a distance A1. The distance A1 is preferably in a range of 0.2 * (D1 / 2) and 0.9 * (D1 / 2), in particular between 0.4 * (D1 / 2) and 0.8 * (D1 / 2) ,

As in FIG. 5 To see, a plurality of the elevations 36 extend in the circumferential direction on the rear wall 13. In this case, a survey 36 fully encloses the inlet opening 34 of the pipe socket 33rd Die Figures 5 and 7 show a crescent-shaped arrangement of the elevations 36 in the circumferential direction around the inlet opening 34. The survey or the surveys 36 provide during operation of the charging device that particles due to their inertia at least with high probability at the inlet opening 34 are thrown past and not be discharged with the condensate, but with the compressed air to the combustion process in the internal combustion engine are supplied.

As in FIG. 7 the elevations 36 are shown separated by a depression. Furthermore, in FIG. 7 to see an imaginary middle line passing through the center of the inlet opening 34 and the center M of the rear wall 13. The recesses extend along imaginary auxiliary axes which are also in FIG. 7 are shown. The auxiliary axes of the recesses intersect the middle straight radially outside the inlet opening 34.

As in FIG. 7 There are circumferentially in front of and behind the inlet opening 34 depending on a first recess and a corresponding plurality of elevations 36. The auxiliary axes of the first wells then have the middle straight ever a first angle α1, β1. Furthermore, second depressions and correspondingly further elevations 36 are provided in the circumferential direction in front of and behind the first depressions. The auxiliary straight lines of the second depressions each have a second angle α2, β2 relative to the middle straight line. The first and second angles (α1, β1, α2, β2) are each between 70 ° and 20 °, in particular between 60 ° and 25 °. The first angles (α1, β1) are preferably smaller than the second angles (α2, β2). In particular, the first angles (α1, β1) are at most 95% of the second angles (α2, β2).

As described above and in FIG. 1 to see the compressor wheel 4 has the diameter D1 (largest diameter of the compressor wheel 4). The entirety of the projections 36 may extend over a length L (see FIG. 7 ). The length L is measured perpendicular to the middle straight line and parallel to a plane which is spanned by the rear wall 13. The length L is thus perpendicular to the axis of the shaft 8. Preferably, the length L is between 0.7 * D1 and 0.2 * D1, in particular between 0.6 * D1 and 0.3 * D1.

In FIG. 7 is shown that the entirety of the projections 36 extends over a segment angle γ, with respect to the center point M of the rear wall 13 and is measured in the plane of the rear wall 13. The segment angle γ is between 120 ° and 45 °, in particular between 100 ° and 60 °.

As in FIG. 7 to see the radial inner edge of the projections 36 follows an arc shape. The arc shape has a steadily changing radius with respect to the midpoint M. On the middle straight, the arc shape has a first radius R1. The radius increases towards the outer ends of the elevations 36 as far as a second radius R2. The second radius R2 is at least 110% of the first radius R1.

FIG. 8 shows a sectional view (along the section line AA in FIG. 7 ) through one of the elevations 36. A height H1 of the elevation 36, measured in the axial direction, is between 0.1 mm and 5 mm, in particular between 0.1 mm and 1 mm.

Likewise in FIG. 8 The edges of the elevation 36 can be seen. The edges of the elevation 36 are rounded off with a defined radius R3. The radius is preferably between 0.05mm and 0.1mm.

As in FIG. 7 to recognize the arrangement of the elevations 36 and the corresponding wells symmetrical to the middle straight, which extends through the center of the inlet opening 34 and the center M of the rear wall 13.

The various features described in detail for the design and positioning of the inlet opening 34 and the elevations 36 were determined on the basis of calculations, simulations and tests and can be used individually or in synergetically cooperating combination in order to prevent particles from entering through the inlet opening 34 and the Enter connection in the engine compartment 10. Contrary to the usual and logical solution, namely to seal the engine compartment 10, it was recognized that the provision of a connection for the pressure balance, for example in the form of a raw nozzle 33, and the projections 36 in the region of the inlet opening 34 is much simpler and less expensive than the complete Sealing the engine compartment with appropriate pressure equalization.

FIG. 9 shows an option of the embodiment for a device 40 to allow pressure equalization between the receiving space 14 and the environment. In general, the pressure compensation device 40 may be any type of connection, for example, one or more holes or bores that allow pressure equalization between the receiving space 14 and the environment. The device 40 for pressure compensation may comprise a membrane, in particular a semipermeable membrane. This membrane can thus be liquid-impermeable and gas-permeable, so that the pressure equalization between the receiving space 14 and the environment is possible. The membrane may, for example, be mounted in the region of the connection in the form of one or more holes or bores above / below or in these. For electrical contacting of the power electronics circuit 15 in the receiving space 14, a connection, for example via a plug 39, of the receiving space 14 with respect to the environment may be provided. In particular, the means 40 for pressure compensation in such a plug 39 may be integrated, as in FIG. 9 is shown. The plug 39 may be suitable for the control of the power electronics circuit 15 and / or the power supply of the electric motor 5. For example, the device 40 may be integrated for pressure equalization in a collar 41 of the plug 39. This has the advantage that a single component can be used both for the electrical contacting of the power electronic circuit 15 and for enabling a pressure equalization. In addition, the pressure compensation device 40 may also include a valve and / or a nozzle, for example in the form of a Venturi nozzle. This allows a controlled and regulated pressure equalization.

LIST OF REFERENCE NUMBERS

1

charging

2

compressor

3

compressor housing

4

compressor

5

electric motor

6

rotor

7

stator

8th

wave

9

motor housing

10

engine compartment

11

wall

12

cover

13

rear wall

14

accommodation space

15

Power electronics circuit

16

first camp

17

second camp

18

axially

19

radial direction

20

circumferentially

21

first seal

22

second seal

23

first outer peripheral surface (the back wall)

24

first inner circumferential surface (of the compressor housing)

25

first radial surface (the wall)

26

second radial surface (of the compressor housing)

27

second inner peripheral surface (the back wall)

28

second outer peripheral surface (the wall)

29

electrical conductor

30

third seal

31

fourth sealing point

32

reinforcing ribs

33

Compound / pipe stub

34

inlet opening

35

fifth seal

36

surveys

37

axially extending section

38

O-rings

39

plug

40

Device for pressure equalization between recording room and environment

41

Collar of the plug

Claims (14)

1. Supercharging device (1) for an internal combustion engine, in particular for a vehicle, wherein the supercharging device has:

   a compressor (2) having a compressor housing (3) and having a compressor space in which a compressor wheel (4) is arranged,

   an electric motor (5) having a motor housing (9) which defines a motor space (10) in which a rotor (6) and a stator (7) are arranged, and

   a connection (33) from the compressor space into the motor space (10) for the purposes of permitting pressure equalization between the compressor space and the motor space (10),

   wherein the compressor housing (3) is closed on the side facing toward the motor housing (9) by a rear wall (13), in which an inlet opening (34) of the connection (33) is arranged,

   characterized in that

   the rear wall (13) is situated opposite a wall (11) of the motor housing (9), wherein the rear wall (13) and

   the wall (11) form a receiving space (14) in which a power electronics circuit (15) for controlling the electric motor (5) is arranged, and wherein the receiving space (14) is hermetically sealed with respect to the compressor space and the motor space (10) .
2. Supercharging device according to Claim 1, characterized in that the centre of the inlet opening (34) of the connection in the rear wall (13) is spaced apart from a central point (M) of the rear wall by a distance (A1).
3. Supercharging device according to Claim 2, characterized in that the compressor wheel has a diameter D1, and wherein the distance (A1) is between 0.4*(D1/2) and 0.8*(D1/2).
4. Supercharging device according to any of Claims 1 to 3, characterized in that at least one elevation (36) for channelling away particles is formed, in the region of the inlet opening (34) of the connection (33), on that side of the rear wall (13) which faces toward the compressor (2).
5. Supercharging device according to Claim 4, characterized in that the at least one elevation (36) extends in a circumferential direction, wherein in particular, the at least one elevation (36) is arranged over the full circumference around the inlet opening (34) .
6. Supercharging device according to either of Claims 4 and 5, characterized in that at least two elevations are provided, wherein the elevations are preferably separated from one another by a depression.
7. Supercharging device according to Claim 6, characterized in that a line of centres connects the centre of the inlet opening and the central point (M) of the rear wall, and wherein the depression extends along an auxiliary axis, and wherein the line of centres intersects the auxiliary axis radially outside the inlet opening (34).
8. Supercharging device according to Claim 7, characterized in that in each case at least one first depression and a corresponding multiplicity of elevations (36) are provided in front of and behind the inlet opening (34) as viewed in the circumferential direction, and wherein corresponding auxiliary axes along which the first depressions extend enclose a first angle (α1, β1) respectively with the line of centres, and the auxiliary axes intersect the line of centres radially outside the inlet opening (34).
9. Supercharging device according to Claim 8, characterized in that in each case at least one second depression and corresponding further elevations (36) are provided in front of and behind the first depressions as viewed in the circumferential direction, and wherein corresponding auxiliary axes of the second depressions enclose a second angle (α2, β2) respectively with the line of centres.
10. Supercharging device according to Claim 9, characterized in that the first and second angles (α1, β1, α2, β2) each lie between 70° and 20°, preferably between 60° and 25°.
11. Supercharging device according to Claim 9 or Claim 10, characterized in that the first angles (α1, β1) are smaller than the second angles (α2, β2), wherein in particular, the first angles (α1, β1) amount to at most 95% of the second angles (α2, β2).
12. Supercharging device according to any of Claims 4 to 11, characterized in that the totality of the elevations (36) extends over a length (L) measured perpendicular to the line of centres and parallel to a plane spanned by the rear wall (13), wherein in particular, the compressor wheel has a diameter D1, and wherein the length (L) amounts to between 0.7*D1 and 0.2*D1, particularly preferably between 0.6*D1 and 0.3*D1.
13. Supercharging device according to any of Claims 4 to 12, characterized in that the totality of the elevations extends over a segment angle (γ) measured with respect to the central point (M), wherein the segment angle lies between 120° and 45°, in particular between 100° and 60°.
14. Supercharging device according to any of Claims 4 to 13, characterized in that radially inner edges of the elevations extend along an arc, wherein in particular, the arc has a continuously varying radius with respect to the central point (M) of the rear wall (13), and wherein the arc defines a first radius (R1) on the line of centres, and wherein the radius increases along the arc up to a second radius (R2) at the outer ends of the elevations, wherein in particular, the second radius (R2) amounts to at least 110% of the first radius (R1).

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