阅读说明：本技术 用于压缩机和/或涡轮的电的介质间隙机、涡轮增压器和/或涡轮机 (Electric clearance machine for compressor and/or turbine, turbocharger and/or turbine ) 是由 M.瑙 H.魏斯 J.里德尔 K.埃尔特尔 M.博伊尔勒 T.弗罗伊许茨 于 2018-05-02 设计创作，主要内容包括：本发明涉及一种用于压缩机和/或涡轮机、特别是用于内燃机的废气涡轮增压器的电的介质间隙机(10),该电的介质间隙机具有：以能够旋转的方式支承在壳体(6)中的轴(5),转子(11)抗扭转地布置在该轴上；固定在壳体上的定子(12),该定子具有至少一个用于产生驱动磁场的多相的驱动绕组(16)以及多个径向向内突出的定子齿(15)；和用于对流经介质间隙机的介质进行流动优化的固定在定子上的机构(17),其中该机构(17)具有至少在上游遮盖所述转子(11)的遮挡罩(18),其中内套筒(19)邻接到所述遮挡罩(18)上,所述内套筒在圆周侧上完全地并且在轴向上至少部分地包围所述转子(11),并且其中所述机构(17)具有与内套筒(19)同轴地布置的外套筒(23),从而在内套筒(19)和外套筒(23)之间仅穿过介质间隙机的定子(12)形成用于介质的唯一流动路径。(The invention relates to an electric gap machine (10) for a compressor and/or a turbine, in particular for an exhaust gas turbocharger of an internal combustion engine, comprising: a shaft (5) rotatably mounted in the housing (6), on which shaft the rotor (11) is arranged in a rotationally fixed manner; a stator (12) fixed to the housing, the stator having at least one polyphase drive winding (16) for generating a drive magnetic field and a plurality of radially inwardly projecting stator teeth (15); and a means (17) for fixing to the stator for flow optimization of the medium flowing through the medium gap machine, wherein the means (17) has a shield (18) which covers the rotor (11) at least upstream, wherein an inner sleeve (19) adjoins the shield (18), which completely and axially surrounds the rotor (11) at least in part on the circumferential side, and wherein the means (17) has an outer sleeve (23) which is arranged coaxially to the inner sleeve (19), so that a single flow path for the medium is formed between the inner sleeve (19) and the outer sleeve (23) only through the stator (12) of the medium gap machine.)

1. An electric gap machine (10) for a compressor and/or a turbine, in particular for an exhaust gas turbocharger of an internal combustion engine, having: a shaft (5) rotatably mounted in the housing (6), on which shaft the rotor (11) is arranged in a rotationally fixed manner; a stator (12) fixed to the housing, the stator having at least one polyphase drive winding (16) for generating a drive magnetic field and a plurality of radially inwardly projecting stator teeth (15); a mechanism (17) for fixing to a stator for flow-optimizing a medium flowing through a medium gap machine, wherein the mechanism (17) has a shield (18) which covers the rotor (11) at least upstream, wherein an inner sleeve (19) adjoins the shield (18), which completely and axially surrounds the rotor (11) at least in part on the circumferential side, and wherein the mechanism (17) has an outer sleeve (23) which is arranged coaxially with respect to the inner sleeve (19), such that a single flow path for the medium is formed between the inner sleeve (19) and the outer sleeve (23) only through the stator (12) of the medium gap machine.

2. The medium gap machine as claimed in claim 1, characterized in that the shield (18) is flow-optimized, in particular configured in the form of a half-oval, and is arranged concentrically or eccentrically with respect to the axis of rotation of the rotor (11).

3. Medium gap machine according to one of the preceding claims, characterized in that a plurality of radially outwardly protruding retaining struts (20) are arranged on the inner sleeve (19), which retaining struts are in particular configured for abutting or fastening on one of the respective stator teeth (15).

4. Medium gap machine according to any of the preceding claims, characterized in that the holding struts (20) are flow-optimally designed and cover the respective stator teeth (15) at least partially upstream.

5. Medium gap machine according to one of the preceding claims, characterized in that the retaining struts (20) are connected, in particular integrally, on their ends facing away from the inner sleeve (19), with the outer sleeve (23) in each case.

6. Medium gap machine according to one of the preceding claims, characterized in that the shield (18), the inner sleeve (19), the retaining strut (20) and the outer sleeve (23) are constructed integrally with one another.

7. A medium gap machine according to any one of the preceding claims, characterized in that the inner sleeve (19) and/or the outer sleeve (23) have axial receiving recesses (25) for receiving stator teeth (15), respectively.

8. A medium gap machine according to any one of the preceding claims, characterized in that a plurality of coil holders (27) for the coils (28) of the drive winding (16) are arranged circumferentially on the outer sleeve (23) in a particularly evenly distributed manner projecting radially outwards.

9. A medium gap machine according to any one of the preceding claims, characterized in that the coil holder (27) is constructed in one piece with the outer sleeve (23).

10. A medium gap machine according to any of the preceding claims, characterized in that there is one coil holder (27) for each stator tooth (15).

11. A medium gap machine according to any one of the preceding claims, characterized in that each coil holder (27) has a locking device (29) for fixing the coil (28) or the coil part of the drive winding (16).

12. Medium gap machine according to one of the preceding claims, characterized in that the shaft (5) or the rotor (11) has an annular projection (38) with an outer diameter which is larger than the inner diameter of the inner sleeve (19), and the inner sleeve (19) can be pushed axially onto the shaft (5) or the rotor (11) up to the annular projection.

13. A medium gap machine according to any of the preceding claims, characterized in that at least one permanent magnet (33) of the rotor (11) protrudes axially downstream beyond the stator (12) or the stator teeth (15).

14. A medium gap machine according to any of the preceding claims, characterized in that the mechanism (17) is constructed as an integral part of the stator (12) that cannot be separated from the stator (12).

15. Compressor and/or turbine, in particular exhaust gas turbocharger, having: a housing (6) and having a shaft (5) which is rotatably mounted in the housing (6) and on which at least one compressor wheel (4) or turbine wheel is arranged in a rotationally fixed manner; and having an electric gap machine (10) with a rotor (11) arranged on the shaft (5) in a rotationally fixed manner and a stator (12) fixed to the housing, wherein the stator (12) has a drive winding (16) for generating a drive magnetic field, characterized in that the gap machine (10) according to one or more of claims 1 to 14 is designed.

Technical Field

The invention relates to an electric gap machine for compressors and/or turbines, in particular exhaust gas turbocharger compressors or micro gas turbine compressors of internal combustion engines, having a shaft which is mounted in a rotatable manner in a housing and on which a rotor is arranged in a rotationally fixed manner, and having a stator which is fastened to the housing and has at least one multiphase drive winding for generating a drive magnetic field and a plurality of radially inwardly projecting stator teeth, and having means for flow optimization of a medium flowing through the gap machine.

The invention further relates to a compressor and/or turbine, in particular an exhaust gas turbocharger, having a housing and a shaft which is rotatably mounted in the housing and on which at least one compressor wheel is arranged in a rotationally fixed manner, and also having an electric gap machine which has a rotor arranged in a rotationally fixed manner on the shaft and a stator which is fastened to the housing, wherein the stator has a drive winding for generating a drive magnetic field.

Background

The above-mentioned types of clearance media machines and turbochargers are known from the prior art. Thus, for example, publication DE 102014210451 a1 discloses a turbocharger with an integrated electric gap machine. Turbochargers, in particular exhaust gas turbochargers, are used, in particular in motor vehicle construction, to increase the air charge in the cylinders of an internal combustion engine in order to boost the power of the internal combustion engine. Exhaust gas turbochargers, which are driven by the exhaust gas flow of an internal combustion engine, are generally used for this purpose. In addition, it is known to assist turbochargers by means of electric motors, so that the fresh air taken in can be compressed independently of the exhaust gas flow of the internal combustion engine and fed to the internal combustion engine at an increased charging pressure. Combinations of both variants are also known. The exhaust-gas turbocharger is provided with an electric machine in order to drive a shaft of the exhaust-gas turbocharger, on which shaft a compressor wheel and a turbine wheel are arranged in a rotationally fixed manner. This can, for example, significantly accelerate a boost pressure build-up which would otherwise be delayed in time.

The advantage of the electric-motor assistance by means of the media gap machine is that the electric-motor assistance can be integrated into the turbocharger particularly space-effectively, since the fresh air drawn in is guided through the media gap formed between the rotor and the stator of the media gap machine. This allows a space-saving integration of the media gap machine into the flow trend. In addition, the advantage results therefrom that the rotor and the stator of the medium gap machine are cooled by the air flow.

The stator usually has a circular stator yoke (Statorjoch) and stator teeth projecting radially inward from the stator yoke, which are arranged, viewed in the circumferential direction, at a uniform distance from one another. The stator teeth are usually wound by multiphase drive windings, wherein a rotating magnetic drive field, by means of which the rotor rotatably supported by the shaft is driven with a predefinable torque, is generated by energizing the phases of the drive windings by means of power electronics provided for this purpose. The rotor advantageously has at least one permanent magnet which interacts with the rotating magnetic field.

It is also known from the above-mentioned publications to provide a mechanism for flow optimization and for this purpose to give a flow-optimized profile, in particular a drop-shaped profile, to stator teeth which project into the medium gap between rotor and stator and through which the medium to be conveyed flows.

Disclosure of Invention

In contrast, the advantage of the medium gap machine according to the invention with the features of claim 1 is that the flow behavior through the medium gap is further improved in such a way that intensive stator cooling is achieved and the deposition of particles, in particular magnetic or magnetizable particles, on the rotor is prevented or at least substantially avoided. The above-mentioned advantages can be achieved by simple constructional measures without a considerable increase in space requirements, so that the flow characteristics, cooling and cleaning of the rotor can also be improved while otherwise maintaining the same dimensions of the medium gap machine. For this purpose, according to the invention, the means fixed to the stator have a shield which covers the rotor at least at the end and is held in particular on the stator teeth. The arrangement of the screen upstream of the rotor or in the flow direction in front of the rotor achieves that the transport medium does not impinge on a flat or vertically opposite wall of the rotor, but is guided through the rotor in a flow-optimized manner by the screen. By arranging the shield on the stator teeth, it is achieved that the shield is arranged fixed on the housing, so that the transport medium is not exposed to a rotational movement or turbulence when flowing to the rotor, in contrast to known solutions. Thereby, the flow characteristics are further improved and turbulence of the flow is avoided, so that on the one hand the operation of the compressor is optimized and on the other hand also the cooling of the stator is improved. According to the invention, it is also provided that an inner sleeve adjoins the shield, which inner sleeve surrounds the rotor completely on the circumferential side and at least partially in the axial direction or in the flow direction. In this way, the transport medium is still prevented from directly contacting the rotor behind the screen, as seen in the flow direction, whereby contamination of the rotor is precluded to a maximum extent. By avoiding deposits on the rotor, it is ensured that no serious unbalance is created. This is avoided in a simple manner by the advantageous design of the mechanism with the inner sleeve. Furthermore, the inner sleeve preferably has a recess for receiving the tip of the stator tooth for the respective stator tooth. Thereby, lateral tangential oscillations of the stator tooth foot and corresponding noise formation are avoided. Furthermore, the mechanism has an outer sleeve arranged coaxially with respect to the inner sleeve, so that a single flow path for the medium is formed between the inner sleeve and the outer sleeve by the stator of the medium gap machine. The inner sleeve and the outer sleeve thus define the only medium gap available for the medium, which passes through the stator and is interrupted in the circumferential direction only by the stator teeth, but the stator teeth extend into or into the inner sleeve. Since the medium gap is now not limited by the stator tooth tips, the rotor or the stator winding itself, but by the outer and inner sleeves which enclose a substantially annular flow path between the stator winding or the drive winding and the stator tooth tips at the level of the stator teeth, a flow-optimized surface is provided for guiding the medium, which surface enables the medium to flow through the medium gap machine with particularly low losses, wherein, in addition, the above-mentioned advantages are achieved in terms of particle deposition.

According to a preferred further development of the invention, it is provided that the shield is flow-optimized, in particular in the form of a half-oval, and is arranged in particular in such a way that its tip is concentric or eccentric with respect to the rotational axis of the rotor. In this way, an advantageous flow diversion for the transport medium flowing into the flow path between the inner sleeve and the outer sleeve takes place. By the preferably semi-oval shape of the shroud, it is achieved that the medium flow hardly or only lightly contacts the rotor itself, thereby reducing the possibility of particle deposition on the rotor. At the same time, the medium flow is deflected outward in the direction of the stator, so that the stator is advantageously cooled. Preferably, the shield is arranged concentrically with respect to the rotational axis of the rotor such that the tip of the shield is at the level of the rotational axis. Alternatively, especially considering an elbow which is placed in front of the media gap machine and which leads the medium to be conveyed from an axis which is pivoted relative to the rotor axis to the inlet of the media gap machine, the eccentric or divergent arrangement of the screen, at least of the tip of the screen, has an advantageous flow guiding effect especially in the direction of the pipe.

The inner sleeve has at least one, preferably a plurality of, radially outwardly projecting retaining struts which are designed in particular for abutting or fastening at the end face on a respective one of the stator teeth. Thereby, the inner sleeve and thus the shield is oriented and retained by the retaining struts fastened on the stator teeth. By fastening the shield on the stator teeth with the retaining struts of the inner sleeve, a simple and space-saving integration of the retaining cap into the medium gap machine is ensured. In addition, a simple fastening of the screen to the housing is thereby achieved.

The retaining struts are preferably flow-optimized and cover the respective stator tooth at least partially upstream. Like the shield in front of the rotor, the retaining struts in front of the stator teeth are therefore located in the media gap and therefore offer a possible solution for a flow-optimized design of the media gap, irrespective of the shape of the stator teeth themselves. By the upstream arrangement of the holding struts, a simple mounting is ensured, and furthermore, by pressing the holding struts against the stator teeth, the holding force is increased during operation by the conveying medium. Thus, a reliable fastening of the inner sleeve and the screen on the stator teeth is reliably ensured. By means of the flow-optimized design of the holding struts, in particular in the form of drops or drop-like or partially drop-like shapes, which are formed together with the stator teeth, the flow behavior of the transport medium in the medium gap is also optimized, in particular by avoiding turbulence and forming or ensuring an advantageous medium flow for cooling the stator. In the simplest case, the separation of the droplet-like profile between the respective retaining strut and its associated stator tooth takes place at the location of maximum profile thickness.

According to a preferred further development of the invention, it is provided that the retaining struts are each connected, in particular in one piece, at their end facing away from the inner sleeve to an outer sleeve arranged coaxially with respect to the inner sleeve. A particularly annular media gap for conveying the medium is thus provided between the inner sleeve and the outer sleeve, which media gap is interrupted only by the retaining struts viewed in the circumferential direction. Since the holding struts are fastened to the stator teeth, this also means that the stator teeth project into the medium gap and thus ensure an advantageous and high-performance operation of the medium gap machine. By means of the retaining struts, which are designed in a flow-optimized manner, the influence of the conveying medium can be kept low by the stator teeth. The inner sleeve and the outer sleeve thus provide an advantageous flow path for the transport medium flowing through the medium gap machine.

Particularly preferably, the shield, the inner sleeve, the retaining strut, the outer sleeve and the shield are constructed integrally with one another. This results in an advantageous mounting component which is easy to handle and which can be mounted in/on the media gap machine. The aforementioned means are at least substantially formed by the mounting part. The mounting part is designed in such a way that a simple mounting on the stator and an arrangement relative to the rotor are ensured. Thus, for example, according to one specific embodiment, it is provided that the mounting part is designed to be pushed axially onto the stator or the stator teeth of the stator. In particular, for this purpose, the inner sleeve and/or the outer sleeve have axial receiving recesses for receiving the stator teeth, respectively. In this way, the mounting component can be easily fastened to the stator teeth by pushing the mounting component onto the mounting teeth in the axial direction with the receiving recess. Preferably, the receiving recess has an insertion bevel to facilitate the arrangement and orientation of the mounting component with respect to the media gap machine and to ensure a reliable mounting. In order to fasten the mounting part to the stator, provision is made, in particular, for the holding force to be realized by press fitting, clamping and/or by additional fastening means, such as, for example, an adhesive or the like. According to an alternative embodiment, it is preferably provided that the inner sleeve and/or the outer sleeve have radial receiving recesses for receiving the stator teeth, respectively. Since in this case axial displacement is not possible, the stator in this case preferably consists of a plurality of stator parts. The stator is thus interrupted, for example, at a plurality of points along the stator yoke, so that one stator tooth is located on each individual stator yoke section, so that the stator teeth can be inserted radially into a respective one of the radial receiving recesses until the stator yoke sections bear against one another in the circumferential direction and are connected to one another there, in particular welded to one another. The unit consisting of the stator and the mechanism can then no longer be released without damage and simple handling of the unit is achieved.

Furthermore, it is preferably provided that a plurality of coil holders for the coils of the drive winding are arranged on the outer sleeve in a radially outwardly projecting manner and are in particular constructed in one piece with the outer sleeve. The drive winding is advantageously formed here by a plurality of coils which can be operated. The coil holder is configured to enable the coil to be simply fastened and mounted thereon. In particular, it is provided that the coil can be pushed radially onto the coil holder in order to fasten it to the mounting part. The mounting part is thus not only used for flow optimization, but at the same time also serves as a carrier for the drive windings, which are then not arranged directly on the stator, but on the mounting part. The mounting part is preferably made of plastic, so that the mounting part simultaneously creates an electrical insulation between the different coils and the stator. In addition, the production from plastic is cost-effective and also allows complex shapes of the mounting parts. Preferably, the coil holders are constructed such that they have radial notches through which the stator teeth of the stator protrude. According to a first embodiment, the recess is also preferably configured to be open at the axial upper edge, so that the stator tooth can be inserted axially into the coil holder, so that the coil can subsequently be mounted on the coil holder. The stator teeth are then connected to one another by a common stator yoke, wherein for this purpose the stator teeth are preferably permanently connected to the stator yoke, in particular welded. According to an alternative embodiment, it is preferably provided that the coil holders have only one radial recess, so that the stator teeth are inserted radially into the coil holders for mounting, the coils are then mounted on the respective coil holders and the stator teeth are subsequently connected to the stator yoke as described above.

According to a preferred further development of the invention, it is provided that a coil holder is present for each stator tooth. Thereby, it is ensured that the coil of the winding can be arranged on each stator tooth. The coils can be designed separately from one another or also continuously. By having the coil holder present radially outside the outer ring, the coil or the drive winding is also outside the outer ring, so that the flow channel between the inner sleeve and the outer sleeve is configured coil-free, so that the transport medium flowing through the transport channel is not influenced by the coil and is optimally guided through the inner ring, the outer ring and the fixing struts and the screen.

Each coil holder preferably has a locking device for fastening the coil or coil part of the drive winding. The coils or coil sections of the drive winding can thus be locked in a simple manner on the respective coil holder by means of the locking device. The locking device acts in particular radially, so that a simple pulling-down of the coil is prevented by the respective coil holder. The locking device interacts here in particular in a form-fitting manner with a coil arranged on the respective coil holder. Advantageously, the respective locking device is furthermore designed to be releasable in order to remove the coil or coil part when required.

Furthermore, it is preferably provided that the respective locking device has at least one laterally projecting locking projection of the coil holder, which locking projection springs back elastically when the coil is pushed radially onto the respective coil holder. The locking device prevents the respective coil from being released from the respective coil holder during operation of the medium gap machine. Instead, a form-fitting locking of the coil on the respective coil holder is ensured by the locking projection. Upon installation, the locking projection resiliently springs back, thereby ensuring simple installation. For this purpose, the locking projection preferably has an actuating ramp which presses the locking projection back elastically when the coil is pushed, and a stop facing away from the actuating ramp, which can be moved radially outward toward the stop without overcoming the stop. In order to release or replace the coil, the locking projection merely has to be manually sprung or moved into its release position. This ensures a simple and reliable mounting of the coil on the mounting part.

Furthermore, it is preferably provided that the rotor is fastened to the shaft or is fastened to the shaft by a screw connection at a shaft end of the shaft. In particular, the rotor can be mounted in a simple manner on the shaft of an existing turbocharger, in particular an exhaust gas turbocharger, by means of a screw connection. For this purpose, only the free end (stirling ende) of the shaft has to be threaded, which interacts with a corresponding mating thread of the rotor in order to be able to fasten the rotor to the shaft at the end with its rotor shaft having the mating thread. If the rotor is arranged directly on the shaft, the advantage of saving space in the axial direction results.

Preferably, the shaft or the rotor has an annular projection, the outer diameter of which is greater than the inner diameter of the inner sleeve, and the inner sleeve can be pushed onto the shaft or the rotor in the axial direction up to the annular projection. The annular projection thus forms an axial closure for the inner sleeve, by means of which the rotor is completely enclosed by the mounting part or the inner sleeve and the shield. The inner sleeve, which axially adjoins the annular projection, seals the rotor against the environment with a narrow tolerance air gap, so that a reliable protection of the rotor, in particular against dirt particles, is ensured.

In particular, it is preferably provided that the at least one permanent magnet of the rotor projects axially downstream beyond the stator or the stator teeth. As a result, an axial force is generated by the magnetic drag force, which is opposite to the flow direction of the conveying medium and leads to a stabilization of the rotor movement in the turbocharger. The rotor preferably has at least one permanent magnet, thereby ensuring a particularly compact design. Alternatively, however, the rotor may also have more than one permanent magnet.

Furthermore, it is preferably provided that the mechanism is designed as a component of the stator that is not separable from the stator. In particular, the mechanism has an inner sleeve, a shield, a retaining strut, an outer sleeve and a coil retainer, which are integrally formed with one another and are arranged on the stator in such a way that they cannot be released from the stator without being damaged. In other words, the mechanism forms a stator or the stator forms the mechanism.

The turbocharger according to the invention with the features of claim 15 is characterized by the inventive design of the medium gap machine. This results in the already mentioned advantages.

Drawings

Further advantages and preferred features and combinations of features emerge in particular from the description made above and the claims. The invention shall be further elucidated with the aid of the drawing. For this purpose, it is shown that:

figure 1 shows an exhaust-gas turbocharger with a medium gap machine in a simplified longitudinal section,

figure 2 shows a perspective view of a media gap machine,

figures 3A and 3B show the mounting components of the media gap machine in perspective front and rear views,

figures 4A and 4B show another perspective front and back view of the media gap machine,

FIG. 5 shows a longitudinal section through the medium gap machine in the region of the rotor, and

fig. 6 shows a detailed view of the media gap machine.

Detailed Description

Fig. 1 shows an exhaust-gas turbocharger 1 with a compressor 2 and a turbine 3 in a simplified longitudinal section. The compressor 2 has a compressor wheel 4, which is arranged on a shaft 5 in a rotationally fixed manner. The shaft 5 is itself rotatably mounted in a housing 6 of the exhaust-gas turbocharger 1. Furthermore, a turbine wheel 7 of the turbine 3 is connected in a rotationally fixed manner to the shaft 5 at the end of the shaft 5 facing away from the compressor wheel 4. When the exhaust gas of the internal combustion engine flows to the turbine wheel 7 and thus drives it, the compressor wheel 4 is likewise brought into rotational motion, so that the fresh air supplied to the compressor wheel 4 is compressed and supplied to the internal combustion engine.

The rotatable mounting of the shaft 5 in the housing 6 can be realized in different ways. According to a first exemplary embodiment, the shaft 5 is rotatably mounted in the housing 6 by means of at least two bearings 8 and 9. Preferably, two rolling bearings are present as bearings 8, 9. For axial support of the shaft 5, it can also be provided that one of the rolling bearings is designed as an axial rolling bearing.

Alternatively and according to the exemplary embodiment shown in fig. 1, it is provided that the bearing 8 is designed as a magnetic bearing and the bearing 9 serving as an axial bearing is designed as a rolling bearing.

In order to be able to drive the compressor 2 in particular independently of the exhaust gas flow of the internal combustion engine, so that a high cylinder air charge can be achieved at any time in the cylinders of the internal combustion engine, it is also provided in this context that the exhaust gas turbocharger 1 has an electric gap machine 10. In this context, the medium gap machine is integrated into the compressor 2, wherein the rotor 11 of the medium gap machine 10 is arranged in a rotationally fixed manner on the end of the shaft 5 facing away from the turbine wheel 7. A stator 12, which interacts with the rotor 11, is arranged coaxially with respect to the rotor 11 in a housing-fixed manner in a flow channel 13 of the exhaust gas turbocharger 1, which flow channel is directed toward the compressor wheel 4.

Fig. 2 shows a simplified perspective view of the media gap machine 10. Here, in particular, the stator 12 and the rotor 11 of the medium gap machine 10 are shown. The stator 12 has a circular-ring-shaped stator yoke 14, from which a plurality of stator teeth 15, which are arranged uniformly distributed over the circumference of the stator yoke 14, project radially inward and point in the direction of the rotor 11 or the axis of rotation of the shaft 5. The stator teeth 15 end radially spaced from the rotor 12, so that there is a corresponding air gap between the stator teeth 15 and the rotor 12.

The stator 12 is provided with drive windings 16, in particular of multiple phases, as shown for example in fig. 1. The drive winding 16 can be formed as a winding wound on the stator or radially plugged onto the stator teeth 15 from a plurality of coils, at least one of which is pushed onto each stator tooth. This will be discussed in detail later.

The medium gap machine 10 also has a mechanism 17 which is designed to optimize the flow behavior of the conveying medium, i.e. fresh air, which is conveyed by the exhaust gas turbocharger 1 through the medium gap machine 10. For this purpose, the mechanism 17 has a shield 18 associated with the rotor 11. The screen 18 is arranged upstream of the rotor 11 when used as intended and is associated with or arranged upstream of the upstream end side of the rotor 11. The shield 18 has a half-oval shape, wherein the tip of the shield 18 is preferably at the height of the axis of rotation of the shaft 5 or of the rotor 11. Alternatively, in particular when the medium gap machine is preceded by a bend, the screen 18 is not arranged concentrically, but eccentrically or offset with respect to the axis of rotation of the shaft 8 or of the rotor 11.

The shield 18 merges at the axial end facing away from the tip into an inner sleeve 19, which has a larger inner diameter than the rotor 11 and is accommodated in the inner sleeve 19, as shown, for example, in fig. 5.

A plurality of radially outwardly extending retaining struts 20 start from the inner sleeve 19, wherein one retaining strut 20 is provided in each case in correspondence with a stator tooth 15. In this case, the retaining struts 20 are arranged according to the distribution of the stator teeth 15 such that in the final mounting position, each retaining strut 20 is located upstream of a stator tooth 15. In this case, the retaining struts 20 likewise have a flow-optimized contour in order to guide the conveying medium as far as possible without losses through the stator teeth 15.

Fig. 6 shows the stator teeth 15 and the holding webs 20 associated with the stator teeth 15 for this purpose in a simplified detail view. The retaining webs 20 have a drop-shaped contour and merge flush on their side into the stator teeth 15 or into the side of the stator teeth 15, so that no turbulence is generated in the transition. In particular, as shown in fig. 6, the respective retaining web 20 forms a drop or wing shape with the associated stator tooth 15.

In order to mount the composite of the sleeves 19, 23, the retaining struts 20 and the shield 18 on the stator teeth 15, it is preferably provided that the stator teeth 15 each have a recess 21 into which the retaining struts 20 can be inserted with a projection 22 corresponding to the recess 21, as shown, for example, in fig. 6. Alternatively, the reverse design can also be implemented, in which the stator teeth 15 are partially inserted into the respective retaining webs 20.

The retaining struts 20 terminate radially outside of an outer ring 23, which has an outer diameter smaller than the outer diameter of the stator yoke 14, so that the drive windings 16 can be arranged between the outer ring 23 and the stator yoke 14. The outer ring 23 is arranged coaxially with the inner ring 19 and, likewise like the inner ring, extends axially through the medium gap machine 10 in such a way that it projects axially on both sides from the stator teeth 15, as can be seen in particular in fig. 2.

Fig. 3A and 3B show a perspective rear view (fig. 3A) and a perspective top view (fig. 3B), respectively, of an advantageous mounting part 24, which is formed by the inner ring 19, the retaining struts 20 and the outer ring 23. The inner ring 19, the retaining struts 20 and the outer ring 23 are advantageously constructed in one piece with one another and are made of plastic. Thereby, an advantageous mounting component 24 is obtained which can be mounted in the medium gap machine 10 in a simple manner. In this case, at least the inner sleeve 19 is slotted so that it has a plurality of axial receiving recesses 25 for each stator tooth 15. Thus, the inner sleeve 25 can be axially plugged onto the rotor and the stator. The arrangement of the axial receptacles 25 corresponds here to the arrangement of the retaining struts 23, so that, as shown in fig. 2, a correct orientation of the retaining struts 20 relative to the stator teeth 15 can be achieved. According to the first embodiment, the outer sleeve 23 has recesses corresponding to the axial recesses 25, so that the outer ring 23 can also be pushed onto the stator teeth.

Alternatively and however according to the embodiment shown in fig. 3A and 3B herein, it is provided that the stator teeth 15 are mounted radially. For this purpose, the outer sleeve 23 has a plurality of radial receiving recesses or radial recesses 26, through which the stator teeth 15 can be inserted radially in the direction of the rotor 11. In particular, the stator is divided into a plurality of stator segments, wherein each stator segment has one stator yoke segment on which only one stator tooth 15 is arranged or configured. The stator teeth 15 are inserted radially into the radial recesses 26 of the outer sleeve 23 until they reach the inner sleeve 19 or project into the radial receiving recesses or recesses provided there until the stator yoke sections abut against one another in the circumferential direction and are connected to one another. In particular, the stator yoke segments are welded to each other. Thereby, an inseparable unit consisting of the stator 12 and the mechanism 17 is obtained.

According to the present exemplary embodiment, it is furthermore provided that a coil holder 27 is assigned to each recess 26. The respective coil holders 27 respectively project radially outward from the outer ring 23 and respectively have an oval profile with a stepwise flat face in the circumferential direction. As shown in fig. 3A and 3B or fig. 4A and 4B, on each of the coil holders 27, the coils 28 of the drive winding 16 are radially displaceable. Advantageously, the coil holders 27 each have a locking device 29 which is formed by two elastically displaceable locking lugs which are arranged or formed on the end of the coil holder 27 facing away from the outer ring 23. The locking projection 30 is in particular formed integrally with the coil holder 27, which is preferably also formed integrally with the outer ring 23. The locking projections 30 of the coil holder 27 are configured to spring (federn) onto each other when the coil 28 is pushed radially over the coil holder 27. Once the coils 28 have reached their final mounting position, the locking projections 30 spring back and thus hold the respective coil 28 on the respective coil holder 27 in a form-fitting manner, as shown in fig. 3A and 3B.

The advantageous mounting component 24 therefore has an inner sleeve 19, an outer sleeve 23, a retaining strut 20 and a coil holder 27 and is preferably constructed in one piece. Advantageously, the mounting is carried out such that the coils 28 are first fastened to the coil holders 27 before the stator teeth 15 are guided through the respective notches 26 and connected to the stator yoke 14.

Fig. 4A and 4B respectively show the mounting component 24 with the mounted stator 12 and the plurality of coils 28 in a perspective rear view (fig. 4A) and a perspective top view (fig. 4B). Preferably, the coils 28 are arranged on the coil holder 27 evenly distributed over the circumference of the mounting part 24. Particularly preferably, at least one coil 28 is arranged on each coil holder 27 in each case. According to the current embodiment of fig. 4A and 4B, coil holders 27 without coils 28 are provided, respectively, for the purpose of illustration. Alternatively, however, it is also conceivable for a plurality of coils 28 to be arranged on the coil holder 27 in an irregularly distributed manner over the circumference of the mounting part 24, as shown, for example, in fig. 4A and 4B.

According to the present embodiment, the stator teeth 15 are formed by a base section 31 and a through-flow guide element 32, respectively. In the present case, the flow guide element 32 is narrower than the base part 31 and is assigned to the rotor 11. In particular, the flow-through guide element 32 ends in the inner sleeve 19, so that the inner sleeve has a flush or continuous cylindrical outer circumferential surface on its inner side, as can be seen in particular in fig. 4A.

Fig. 5 shows the rotor 11 of the medium gap machine 10 in a simplified longitudinal section. The rotor 11 has permanent magnets 33 which are accommodated in axial receiving recesses 34 of a rotor shaft 35. Alternatively, the receiving recess 34 can also be formed directly in the shaft 5. By means of the axial recesses 34, a jacket wall is formed which surrounds the permanent magnets 33 on the circumferential side and thus forms a reinforcement which can protect the permanent magnets 33 from damage which may be caused by the centrifugal forces acting even at high rotational speeds. In the present case, the rotor shaft 35 is connected at its end-side end to the shaft 5 by a screw connection 36. In order to ensure that the rotor shaft 35 is securely screwed onto the shaft 5, the rotor shaft 35 has, on its end section facing the shaft 5, a polygonal contour which forms a locking surface 37 on which a tool wrench for applying a tightening torque during the installation of the rotor 11 can act on the shaft 5. Furthermore, the rotor shaft 35 has, spaced apart from the locking surface 37, an annular projection 38 extending over the entire circumference, the outer diameter of which is greater than the inner diameter of the inner sleeve 19. As shown in fig. 5, the mounting part 24 together with the screen 18 and the inner sleeve 19 is pushed until it is adjacent to the annular projection 38 on the rotor shaft 35. The permanent magnet 33 is thereby reliably protected from magnetic or magnetizable dirt particles on the inside. Advantageously, a minimum axial and radial spacing is left between the inner sleeve 19 and the annular projection 38, so that during operation no friction is generated between the mounting part 24 and the rotor 11 as a result of the relative movement of the rotor 11 with respect to the mounting part 24.

An advantageous embodiment of the medium gap machine 10 has the advantage that an advantageous and flow-optimized flow channel 39 for the medium or charge air to be conveyed is formed between the inner sleeve 19 and the outer sleeve 23, which channel is guided only through the stator 12 or the intermediate spaces of the stator 12 between the stator teeth of the stator 12, wherein the medium is guided through the outer sleeve 23 on the drive winding 16 and through the inner sleeve 19 on the rotor 11. Since the stator teeth 15 project into the inner sleeve 19, no medium can enter the gap between the rotor 11 and the stator 12. By means of the advantageous design of the screen 18, it is achieved that the inflowing conveying medium is substantially deflected past the rotor and is more inclined to travel in the direction of the stator 12, so that it is cooled advantageously and dirt particles are prevented from depositing on the rotor. Since the stator teeth 15 as a whole still end close to the rotor and thus only a small air gap exists between the stator teeth 15 and the rotor 11, the electromagnetic properties are improved due to the smaller magnetic resistance. When the rotor 11 and the flow guide element 32 are in the lee side (Windschatten) of the mounting part 24, turbulence in the air flow is reduced and the inflow of the compressor wheel 4 axially behind the rotor 11 is improved. Although according to the present embodiment the number of retaining struts 20 corresponds to the number of through-flow guides 23, according to another embodiment a different number than this may be provided. In particular, more retaining struts can be present as through-flow guides. Advantageously, at least the outer sleeve 23 is configured conically in order to increase the flow speed of the compressor wheel 4.

The flow-optimized configuration of the retaining struts 20 makes it possible to improve the geometry of the through-flow guide 23. As can be seen in fig. 6, the retaining struts 20 form the upstream portion of the flow profile up to the maximum profile width. The through-flow guide 23 is geometrically shaped in the shape of the outflow profile. By forming the upstream portion of the streamline profile by the retaining struts 20, the expenditure in shaping the through-flow guide 32 is reduced, so that the production costs are reduced. In addition, the average cross section of the through-flow guide 32 is increased, so that a larger cross section is available for it in this region in terms of magnetic flux. Thereby, the electromagnetic characteristics of the machine 10 are also improved in terms of its maximum power.

Advantageously, the permanent magnet 33 is arranged and constructed such that it projects axially beyond the stator 12 on the side facing away from the shield 18. Due to the resulting reluctance forces, axial forces are generated which react to the flow and thereby ensure an increased smoothness of operation of the rotor 11.