EP3456983B1 - Loading device for a combustion engine - Google Patents

Description

Field of invention

The present invention relates to a charging device for an internal combustion engine, in particular in a vehicle.

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 case of the charging devices considered here, the compressor wheel in the compressor is driven by means of an electric motor.

From the US 2004/200215 A1 is an electrically assisted turbocharger known for an internal combustion engine comprising: a rotating assembly having a turbine and a compressor wheel mounted on opposite ends of a shaft; a stationary housing with an exhaust gas diffuser with which exhaust gases from the engine can be directed through the turbine wheel in order to rotate the rotating assembly, a compressor housing for receiving compressed air from the compressor wheel and a bearing housing; and a storage system with which the rotating assembly can be stored in the stationary housing and which has an elongated bearing bracket which is removably supported with a plurality of elastic elements arranged between the long bearing bracket and the bearing housing, and a pair of ball rolling bearings.

From the US 2014/090626 A1 an electric compressor is known which has an integrated housing with a built-in electric motor and motor converter; and a ball bearing and damper sleeve structure disposed on both sides of the electric motor. The damper sleeve structure consists of a large diameter sleeve, a spring guide, a coil spring and a ball bearing. A gap is formed between the ball bearings and a sleeve and the large-sized sleeve. The inner ring or outer ring of the ball bearing is supported by various support elements arranged on both sides. On the outside of the sleeves there is an elastic O-ring which elastically supports the sleeve and a sleeve with a large diameter.

The EP 2 733 326 A1 shows an electrical charging device with a first cooling channel which is formed in a stator along a motor coil and connects a gas supply opening with a gas discharge opening in a motor housing; and a first inlet channel connecting the gas discharge opening to an inlet opening of a compressor.

Summary of the invention

It is the object of the present invention to provide a supercharging device for an internal combustion engine that can be operated permanently with low-cost manufacture 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 subclaims relate to advantageous embodiments of the invention.

According to 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 compression chamber. A compressor wheel is arranged in the compressor chamber. The charging device further comprises an electric motor with a rotor and a stator. A motor housing is also provided. An engine room is formed in the engine case. This is used to hold the stator and the rotor. A connection from the compressor compartment to the engine compartment preferably enables pressure equalization between the compressor compartment and the engine compartment. This has the The advantage is 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 due to high pressures without pressure compensation, can be avoided or reduced. This reduces the risk that lubricants or the like will be pressed by the bearings and / or seals into the compressor compartment or the engine compartment and cause damage there.

In preferred embodiments, the compressor housing can be closed by a rear wall on the side facing the motor housing, the rear wall being opposite a wall of the motor housing, and an inlet opening of the connection being 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 compression space and the engine compartment. This has the advantage that no fluids and / or particles can get from the compressor compartment or the engine compartment into the receiving compartment with the power electronics circuit.

The compressor housing thus has an open side on its side facing the stator before 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 that the charging device can be manufactured and installed, this rear wall can be an independent component manufactured separately from the compressor housing. The power electronics circuit is used to control the electric motor. This receiving space is hermetically sealed from the compressor space and from the engine compartment. The hermetic seal means, in particular, a seal against both gases and liquids. In advantageous refinements, the rear wall can be made of: plastic or metal, in particular thermoset, high temperature resistant Polyamide, fiber-reinforced plastic or aluminum. In addition, the rear wall can have several reinforcing ribs. The reinforcing ribs can extend outward in a star shape, starting from a central recess in the rear wall. In particular, the reinforcing ribs can be formed on the side of the rear wall facing the electric motor.

In one embodiment, knobs with a height of 0.1 mm to 0.6 mm, in particular 0.2 to 0.4 mm high, can 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. In a further embodiment, the knobs can be convexly shaped so that they are easily deformable.

In refinements, it can be provided that the direct connection from the compressor room to the engine room has a pipe socket in order to enable pressure equalization between the two rooms. This pipe socket extends in the axial direction through the rear wall, the receiving space and the wall of the motor housing into the motor compartment in order to form a direct fluid-conducting connection between the motor compartment and the compressor compartment. The pipe socket is designed in such a way that only a connection can be made between the compressor compartment and the engine compartment and no connection to the receiving compartment. It can preferably be provided that the pipe socket is an integral part of the one-piece rear wall. Furthermore, the pipe socket is advantageously located eccentrically to the shaft of the charging device.

The connection between the compressor compartment and the engine compartment in order to enable the pressure equalization can have further components. For example, at least one membrane can be provided, for example a semipermeable membrane, in order to allow gases to pass through and to hold back solid or liquid particles. The membrane can be attached in the pipe socket, at the inlet opening on the rear wall and / or at an outlet of the pipe socket in the area of the engine compartment. Additionally or alternatively, a device can also be provided which regulates or controls the connection or the flow through the connection between the rooms. Such a device can be in the form a valve and / or a nozzle, for example a Venturi nozzle, can be integrated. This has the advantage that the connection between the compressor chamber and the engine compartment not only enables pressure equalization, but at the same time the pressure equalization can be controlled or regulated and / or contamination by liquids or particles can be avoided.

In the compressor, it should be avoided as far as possible that particles get into the engine compartment via the inlet opening of the connection or the pipe socket. Such particles can in particular be burnt oil droplets or soot particles. In addition to the features already described, the following other different measures are provided to avoid this, which can be used individually or in combination.

The compressor wheel has a certain diameter D1. The center of an inlet opening of the connection or of the pipe socket in the rear wall can be spaced from a center point 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 refinements, it can be provided that on the side of the rear wall facing the compressor in the area of the inlet opening of the pipe socket at least one elevation is formed for discharging the particles. 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 around the entire circumference of the inlet opening of the pipe socket. In particular, it is provided that one or more elevations are arranged in the circumferential direction in a sickle shape around the inlet opening. During operation of the charging device, the at least one elevation ensures that, due to their inertia, particles are at least highly likely to be thrown past the inlet opening and, for example, are not discharged 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 elevations are preferably separated from one another by a depression. An imaginary median line is defined which runs through the center of the inlet opening and the center point M of the rear wall. The recess extends along an imaginary auxiliary axis. The auxiliary axis preferably intersects the center line radially outside the inlet opening.

In the circumferential direction, there can preferably be at least one first depression and a corresponding plurality of elevations 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 central line and advantageously intersect the central line radially outside the inlet opening.

Furthermore, second recesses and correspondingly further elevations can preferably be provided in the circumferential direction in front of and behind the first recesses. The auxiliary straight lines of the second depressions each have a second angle α2, β2 to the central straight line and intersect the central straight line radially outside of the inlet opening.

The first and second angles (α1, β1, α2, β2) are each between 70 ° and 20 °, preferably between 60 ° and 25 °. The first angles (α1, β1) are advantageously 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 totality of the elevations can extend over a length L. The length L is measured perpendicular to the center line and parallel to a plane that is spanned by the rear wall. The length L is perpendicular to the axis of the shaft. The length L is preferably between 0.7 * D1 and 0.2 * D1, in particular between 0.6 * D1 and 0.3 * D1.

The totality of the elevations can 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 can follow an arc shape. The arc shape preferably has a constantly changing radius with respect to the center point M. In particular, a first radius R1 is defined on the central straight line, which increases towards the outer ends of the elevations up to a second radius R2. The second radius R2 is particularly preferably 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 0.05 mm and 0.1 mm.

The arrangement of the elevations and depressions is preferably symmetrical to the central line which runs through the center of the inlet opening and the center M of the rear wall.

These different features for the design and positioning of the inlet opening and the elevations were determined on the basis of calculations, simulations and tests and can be used individually or in a synergetic combination to prevent particles from getting into the engine compartment via the inlet opening and the connection. Contrary to the usual and logical solution, namely to seal the engine compartment, it was recognized that the provision of a connection between the compressor compartment and the engine compartment, for example in the form of a pipe socket, and the above-described elevations is much simpler and cheaper than the complete sealing of the engine compartment with the necessary pressure compensation.

As already described above, the shaft protrudes through the wall of the motor housing into the compressor. A sealing point can preferably be formed at this point in order to seal off the compressor compartment from the engine compartment. The sealing point is provided either as a contactless seal or as a dynamic seal, in particular with at least one piston ring. In a preferred variant, in particular in the case of a motor housing made of aluminum, however, a contacting seal, in particular piston rings, is deliberately omitted in order to prevent the piston rings from "seizing" (notching) in the motor housing.

In order to hermetically seal the engine compartment against the receiving space, a further seal is preferably provided between the connection, in particular in the form of a pipe socket, from the compressor compartment to the engine compartment and the wall of the motor housing.

According to the invention, a device is provided to enable pressure equalization between the receiving space and the environment. It can also be provided that at least one electrical conductor extends from the power electronics circuit through the motor housing, in order to enable an electrically conductive connection between the power electronics circuit and the electric motor. According to the invention, the charging device has a bearing device for supporting a shaft which connects the rotor to the compressor wheel, the bearing device having a device for vibration damping. The vibration damping can, for example, enable the shaft to run quieter and more evenly, as well as with less vibration.

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

Brief description of the figures

• Figure 1 a sectional view of a charging device according to the invention according to an embodiment,
• Figure 2 a detail of the first seal of the charging device according to the invention according to the embodiment,
• Figure 3 a detail of the second seal of the charging device according to the invention according to the embodiment,
• Figure 4 two views of a rear wall of the charging device according to the invention according to the embodiment,
• Figure 5 another view of the rear wall of the charging device according to the invention according to the embodiment,
• Figure 6 a detail of the charging device according to the invention according to the embodiment with the cover removed,
• Figure 7 Details of the design of the elevations on the rear wall according to an advantageous embodiment of the charging device
• Figure 8 Details of the design of the elevations on the rear wall according to an advantageous embodiment of the charging device in section
• Figure 9 View of a plug with an integrated device for pressure equalization between the receiving space and the environment

In the following, the Figures 1 to 9 a charging device 1 according to the embodiment is described in detail.

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

The charging device 1 also includes an electric motor 5. The electric motor 5 is composed of a rotor 6 and a stator 7.

The rotor 6 is connected to the compressor wheel 4 in a rotationally fixed manner via a shaft 8. By rotating the electric motor 5, the compressor wheel 4 is thus also set in rotation.

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

Figure 1 shows an axial direction 18 corresponding to the shaft 8. A radial direction 19 is perpendicular to the axial direction 18. A circumferential direction 20 is defined around the axial direction 18.

When the electric motor 5 rotates and therefore the compressor wheel 4 rotates, air is sucked in in the axial direction 18. The air is compressed in the radial direction 19 via the compressor 2 and fed to an internal combustion engine.

The charging device 1 further comprises an engine housing 9. An engine compartment 10 is formed in this engine housing 9. The engine compartment 10 is closed by means of a cover 12 on the side facing away from the compressor 2. The engine compartment 10 is delimited towards the compressor 2 by a wall 11 of the engine 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 thermoset, or of metal, in particular aluminum. In the manufacture of plastic, high temperature-resistant polyamide is used in particular. Furthermore is preferably it is provided that the rear wall 13 is made of fiber-reinforced plastic.

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

The wall 11 of the motor housing 9 is firmly connected to the compressor housing 3, in particular screwed. A receiving space 14 is formed between the rear wall 13 and the wall 11. In this receiving space 14 there is a power electronics circuit 15 for the power supply and control of the electric motor 5. The receiving space 14 is hermetically sealed from the compressor space and from the engine compartment 10. A device 40 is provided which enables pressure equalization between the receiving space 14 and the environment. Further details on device 40 for pressure equalization are given below in connection with Figure 9 described.

The shaft 8 is supported by a first bearing 16 opposite the wall 11 of the motor housing 9. A second bearing 17 is located between the shaft 8 and the cover 12. Figure 3 shows two O-rings 38 between the outer ring of the first bearing 16 and the adjoining motor housing 9. These O-rings 38 serve, among other things, as a device for damping vibrations. As shown, the O-rings 38 can be inserted into a groove in the outer ring of the bearings 16 and 17 (see Figures 1 and 3 ) sit. Additionally or alternatively, a groove can also be provided in the motor housing 9 or the cover 12. The O-rings 38 are preferably made of HNBR, rubber or rubber. The motor housing 9 and / or the cover 12 can 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 material pairing. On the other hand, the O-rings 38 dampened mechanical vibrations. The O-rings 38 thus ensure chemical and mechanical decoupling. Additionally or alternatively, the device for Have 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, as seen in the free space between the bearing 17 and the cover 12 in FIG Figure 1 ).

The wall 11 of the motor housing 9 has an axially extending section 37. The power electronics circuit 15 and, accordingly, the receiving space 14 are located radially within this section 37.

At least one first seal 21 and one second seal 22 are provided for the hermetic sealing of the receiving space 14. These seals 21, 22 are based on the detailed representations in Figures 2 and 3 explained. Figure 2 shows the first seal 21 in detail. The compressor housing 3 has a first inner circumferential surface 24. The wall 11 has a first radial surface 25. A first outer circumferential surface 23 is defined on the rear wall 13. The first seal 21 is arranged 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 acted upon by force only in the axial direction 18. The compressor housing 3 has a second radial surface 26. The first seal 21 is arranged completely between the first outer circumferential surface 23, the first inner circumferential surface 24, the first radial surface 25 and the second radial surface 26 and is braced between the first radial surface 25 and the second radial surface 26 in the axial direction 18, whereby the sealing effect is generated. 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 pressing.

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

Figure 1 shows an electrical conductor 29 in the form of a bolt. The electrical conductor 29 makes electrically conductive contact between the power electronics circuit 15 and 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 area of the wall 11. The third seal 30 is a seal applied to the electrical conductor 29 in the form of a hose. In order to avoid any short circuits in the area of the electrical conductors, provision can be made for the third seal to extend in the axial direction over at least half the length of the stator, preferably over at least two thirds of the length of the stator. The third seal preferably has circumferential elevations, in particular in the area of the through hole through the wall 11, in order to locally generate a greater contact pressure relative to 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 area of the cover 12. That is, the electrical conductors 29 advantageously extend over the entire length of the stator in the axial direction 18. The contact between the stator 7 and the electrical conductor 29 can therefore take place on the side of the stator 7 facing away from the compressor 2 for reasons of assembly. In particular, the electrical conductors 29 and the stator 7 can be electrically connected to one another, 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, assembly damage caused by the crimping process on the power electronics circuit 15 can be avoided. On the side of the stator 7 facing away from the compressor 2, the motor housing has a cover 12. Before this cover 12 is installed, the electrical conductors 29 with the windings on the stator 7 can be installed on this side be electrically connected, as described, for example, by crimping. Only then is the cover 12 mounted accordingly. This arrangement enables simple assembly of the very compact charging device 1. Overall, the design and arrangement of the electrical conductors 29 thus has the advantages of quick and simple assembly with little risk of assembly damage and without having to accept major losses in performance for the electrical connection.

Figure 6 shows a side of the motor housing 9 facing away from the compressor 2, with the cover 12 removed. This illustration clearly shows that the ends of the electrical conductors 29 and the stator 7 are accessible when the cover 12 is removed. Before assembly of the cover 12, the ends of the electrical conductors 29 can thus be connected to the stator 7 in an electrically conductive manner, as described above.

As Figures 1 and 3 show in detail, there is a contactless fourth sealing point 31 between the wall 11 and the shaft 8. This fourth sealing point 31 is in particular located radially inside the second seal 22.

Figure 4 shows in an isometric view and in a sectional view the exact design of the rear wall 13. The rear wall 13 is a one-piece component.

Figure 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 glued or vulcanized seals that are arranged over their entire circumference. Alternatively or in addition, the first seal 21 and / or the second seal 22 can be arranged in a groove in the rear wall 13 or a corresponding extension can be formed on the rear wall 13, which is inserted into a corresponding groove in the first seal 21 or second seal 22 protrudes.

Furthermore, the illustrations in Figure 4 several reinforcement ribs 32 which are an integral part of the rear wall 13. The reinforcement ribs 32 are arranged in a star shape in the radial direction 19 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 compartment and the engine compartment 10. This is located at a geodetically lower position, that is, below the shaft 8. As in particular Figure 1 shows, the connection or the pipe socket 33 forms a fluid-conducting connection between the compressor chamber and the engine compartment 10. The pipe socket 33 is sealed off from the wall 11 via a fifth seal 35. The pipe socket 33 enables pressure equalization between the compression chamber and the engine compartment 10. The pipe socket 33 is designed such that there is only a connection between the compressor room and the engine compartment 10 and no connection to the receiving space 14. It can be provided that the pipe socket 33 is an integral part of the one-piece rear wall 13. The pipe socket 33 is eccentric to the shaft 8 of the supercharging device 1. The direct connection from the compressor compartment to the engine compartment 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 due to high pressures without pressure compensation, can be avoided or reduced. This reduces the risk that lubricants or the like will be pressed by the bearings and / or seals into the compressor compartment or the engine compartment and cause damage there.

The connection between the compressor compartment and the engine compartment 10 in order to enable the pressure equalization can have further components. For example, a membrane can be provided, in particular a semipermeable membrane, in order to allow gases to pass through and to hold back solid or liquid particles. Such a membrane can be attached 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 area of the engine compartment 10. Additionally or alternatively, a device can also be provided that regulates or controls the connection or the 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 the connection between the compressor chamber and the engine compartment not only enables pressure equalization, but at the same time the pressure equalization can be controlled or regulated and / or contamination by liquids or particles can be avoided.

Figure 5 shows a plan view of the side of the rear wall 13 facing the compressor 2. It can be clearly seen that a plurality of elevations 36 are arranged around the inlet opening 34 of the pipe socket 33. These elevations 36 extend crescent-shaped around the inlet opening 34 in the circumferential direction 20. By means of these elevations 36, particles are diverted so that there is a high probability that they will not penetrate into the inlet opening 34 and thus into the pipe socket 33. It should be avoided as far as possible that particles get into the engine compartment 10 via the inlet opening 34 of the pipe socket 33. Such particles can in particular be burnt oil droplets or soot particles. An embodiment of the elevations 36 is described below with reference to FIG Figures 1 , 4th , 5 , 7 and 8 described in more detail.

The compressor wheel has a certain diameter D1 (see Figure 1 ). The center of an inlet opening 34 of the pipe socket 33 in the rear wall 13 is spaced from a center point 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 Figure 5 To see, a large number of the elevations 36 extend in the circumferential direction on the rear wall 13. In this case, an elevation 36 completely surrounds the inlet opening 34 of the pipe socket 33. The Figures 5 and 7th show a crescent-shaped arrangement of the elevations 36 in the circumferential direction around the inlet opening 34. The elevation or the elevations 36 ensure during operation of the charging device that, due to their inertia, particles are at least highly likely to be thrown past the inlet opening 34 and not are removed with the condensate, but are fed to the combustion process in the internal combustion engine with the compressed air.

As in Figure 7 the elevations 36 are shown separated from one another by a depression. Furthermore, in Figure 7 to see an imaginary center line running through the center of the inlet opening 34 and the center point M of the rear wall 13. The depressions extend along imaginary auxiliary axes which are also in Figure 7 are shown. The auxiliary axes of the depressions intersect the center line radially outside of the inlet opening 34.

As in Figure 7 it can be seen in the circumferential direction in front of and behind the inlet opening 34 a first depression and a corresponding plurality of elevations 36. The auxiliary axes of the first depressions then each have a first angle α1, β1 to the center line. Furthermore, in the circumferential direction in front of and behind the first depressions, second depressions and correspondingly further elevations 36 are provided. The auxiliary straight lines of the second depressions each have a second angle α2, β2 to the central 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 Figure 1 the compressor wheel 4 can be seen to have the diameter D1 (largest diameter of the compressor wheel 4). The entirety of the elevations 36 can extend over a length L (see FIG Figure 7 ). The length L is measured perpendicular to the straight line and parallel to a plane spanned by the rear wall 13. The length L is thus perpendicular to the axis of the shaft 8. The length L is preferably between 0.7 * D1 and 0.2 * D1, in particular between 0.6 * D1 and 0.3 * D1.

In Figure 7 it is shown that the entirety of the elevations 36 extends over a segment angle γ which is relative 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 Figure 7 the radial inner edge of the elevations 36 can be seen following an arc shape. The arc shape has a constantly changing radius with respect to the center point M. The arc shape has a first radius R1 on the central straight line. The radius increases towards the outer ends of the elevations 36 up to a second radius R2. The second radius R2 is at least 110% of the first radius R1.

Figure 8 shows a sectional view (along the section line AA in Figure 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 Figure 8 the edges of the elevation 36 can be seen. The edges of the elevation 36 are rounded with a defined radius R3. The radius is preferably between 0.05 mm and 0.1 mm.

As in Figure 7 The arrangement of the elevations 36 and the corresponding depressions can be seen symmetrically to the central straight line which runs through the center of the inlet opening 34 and the center M of the rear wall 13.

The different 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 synergetic combination to prevent particles from flowing through the inlet opening 34 and the Connection to 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 pressure equalization, for example in the form of a pipe socket 33, and the elevations 36 in the area of the inlet opening 34 is significantly simpler and cheaper than the complete one Sealing of the engine compartment with the necessary pressure compensation.

Figure 9 shows an embodiment according to the invention for a device 40 to enable pressure equalization between the receiving space 14 and the environment. In general, the device 40 for the pressure equalization can be any type of connection, for example one or more holes or bores, which allow a pressure equalization between the receiving space 14 and the environment. The device 40 for pressure equalization can have a membrane, in particular a semipermeable membrane. This membrane can thus be impermeable to liquid and gas-permeable, so that pressure equalization between the receiving space 14 and the environment is possible. The membrane can, for example, be attached in the area 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 can be provided. In particular, the device 40 for pressure compensation can be integrated in such a plug 39, as shown in FIG Figure 9 is shown. The plug 39 can be suitable for controlling the power electronics circuit 15 and / or the power supply of the electric motor 5. For example, the device 40 for pressure equalization can be integrated in a collar 41 of the plug 39. This has the advantage that a single component can be used both for making electrical contact with the power electronics circuit 15 and for enabling pressure compensation. In addition, the device 40 for pressure equalization can also comprise a valve and / or a nozzle, for example in the form of a Venturi nozzle. This enables a controlled and regulated pressure equalization.

List of reference symbols

1

Charging device

2

compressor

3

Compressor housing

4th

Compressor wheel

5

Electric motor

6th

rotor

7th

stator

8th

wave

9

Motor housing

10

Engine compartment

11

wall

12

cover

13

Back wall

14th

Recording room

15th

Power electronic circuit

16

first camp

17th

second camp

18th

Axial direction

19th

Radial direction

20th

Circumferential direction

21st

first seal

22nd

second seal

23

first outer peripheral surface (of the rear wall)

24

first inner circumferential surface (of the compressor housing)

25th

first radial surface (of the wall)

26th

second radial surface (of the compressor casing)

27

second inner peripheral surface (the rear wall)

28

second outer peripheral surface (of the wall)

29

electrical conductor

30th

third seal

31

fourth sealing point

32

Reinforcement ribs

33

Connection / pipe socket

34

Inlet opening

35

fifth seal

36

Surveys

37

axially extending portion

38

O-rings

39

plug

40

Device for pressure equalization between the recording room and the environment

41

Collar of the plug

Claims (12)

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

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

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

   a shaft (8) which connects the rotor (6) rotationally conjointly to the compressor wheel (4),

   a bearing device for the mounting of the shaft (8), wherein the bearing device has a means for vibration damping,

   a receiving space (14), wherein a power electronics circuit (15) for the control of the electric motor (5) is arranged in the receiving space (14), and wherein the receiving space (14) is hermetically sealed off with respect to the compressor space and the motor space (10),

   characterized in that the receiving space (14) is arranged between motor housing (9) and compressor housing (3), and furthermore by a means (40) for allowing a pressure equalization between the receiving space (14) and the surroundings.
2. Supercharging device according to Claim 1, characterized in that at least one electrical conductor (29) extends from the power electronics circuit (15) through the motor housing (9) in order to allow an electrically conductive connection between the power electronics circuit (15) and the electric motor (5).
3. Supercharging device according to either of Claims 1 and 2, characterized by a connection from the compressor space into the motor space (10) in order to allow a pressure equalization between the compressor space and the motor space (10).
4. Supercharging device according to any of the preceding claims, characterized in that the means for the pressure equalization (40) is a connection, in particular a bore.
5. Supercharging device according to any of the preceding claims, characterized in that the means for the pressure equalization (40) has a diaphragm, in particular a semipermeable diaphragm.
6. Supercharging device according to any of the preceding claims, characterized in that the means for the pressure equalization (40) is integrated into a plug connector (39), wherein, in particular, the plug connector is suitable for the control of the power electronics circuit (15) and/or the supply of electricity to the electric motor (5).
7. Supercharging device according to Claim 6, characterized in that the means for the pressure equalization (40) is integrated in a collar (41) of the plug connector (39).
8. Supercharging device according to any of the preceding claims, characterized in that the bearing device for the mounting of the shaft (8) has at least two bearings (16, 17), in particular rolling bearings, in order to mount the shaft (8) relative to the motor housing (9) or the motor housing (9) and a cover (12) of the motor housing (9).
9. Supercharging device according to Claim 8, characterized in that the means for vibration damping has at least one O-ring, wherein the at least one O-ring is arranged between the bearing (16, 17) and the adjacent motor housing (9) or cover (12).
10. Supercharging device according to Claim 9, characterized in that the at least one O-ring is arranged in a groove in an outer ring of the bearing.
11. Supercharging device according to any of the preceding Claims 8 to 10, characterized in that the means for vibration damping has at least one spring element.
12. Supercharging device according to Claim 11, characterized in that the spring element is arranged in an axial direction between the bearing (16, 17) and the motor housing and/or the bearing (16, 17) and the cover (12) .

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