WO2023078800A1

WO2023078800A1 - Stator with a reinforcing ring and electrical drive train with the stator

Info

Publication number: WO2023078800A1
Application number: PCT/EP2022/080257
Authority: WO
Inventors: Matthias Cudok
Original assignee: Zf Friedrichshafen Ag
Priority date: 2021-11-03
Filing date: 2022-10-28
Publication date: 2023-05-11
Also published as: DE102021212361A1

Abstract

The invention relates to a stator (4) for an electric machine (2) comprising a stator core (8), wherein the stator core (8) has a ring-shaped stator yoke (9), on which a plurality of radially protruding stator teeth (10) are arranged on one radial side in the circumferential direction and multiple securing sections (12) for securing the end-side of the stator (4) to a housing (7) are arranged on the other radial side. A first end side of the stator core (8) forms a securing side (25) for axially securing the stator (4) to the housing (7) and a second axial end side forms an outer side (26) of the stator (4). The stator (4) also comprises a reinforcing ring (15) for reinforcing the stator core (8), wherein the reinforcing ring (15) is mounted on the outer side (26), circumferentially on the stator yoke (9).

Description

Stator with a stiffening ring and electric drive train with the stator

The invention relates to a stator with the features of the preamble of claim 1. The invention also relates to an electric drive train with an electric machine with the stator.

Electrical machines, such as electric motors or generators, comprise a stationary part designed as a stator and a rotating part designed as a rotor. Magnetic fields that change locally and over time are generally generated in the rotor and/or in the stator to generate a rotational movement of the rotor. The rotor torque generates a corresponding counter-torque of the same amount in the stator, more precisely in its laminated core carrying the winding, which must be supported by a stator carrier receiving the stator laminated core.

Document JP 2013 215 056 A discloses a stator cooling structure having at least one cylindrical stator core and a holding cylinder having a cylindrical body with a bottom surface at an axial end, the stator core being inserted into the holding cylinder so that an end surface rests on a side of the stator core is in contact with the bottom surface in the axial direction. Furthermore, the stator cooling structure has a pressing part which is in contact with an end face on another side of the stator core in the axial direction and is fixed to a housing together with the holding cylinder to fix the stator core in the axial direction. In addition, the stator cooling structure includes cooling passages formed between the support cylinder or an inner peripheral surface of the pressing member and an outer peripheral surface of the stator core.

The object of the invention is to create a stator of the type mentioned at the outset, which is characterized by improved operating behavior. This object is achieved by a stator having the features of claim 1 and by an electric drive train having the features of claim 15. Further features and advantages as well as effects of the invention are described in the dependent claims, the description with the figures.

The subject matter of the invention is a stator which is designed and/or suitable for an electrical machine. In particular, the electrical machine is designed as an internal rotor, with a rotor being arranged radially inside the stator. Alternatively, however, the electrical machine can also be designed as an external rotor, with a rotor being arranged radially outside of the stator.

The stator has a stator core with an annular stator yoke, on which a plurality of radially projecting stator teeth are arranged in the circumferential direction. In particular, in the case of an embodiment as an internal rotor, the stator core has a plurality of stator teeth directed radially inwards. Alternatively, in the case of an embodiment as an external rotor, the stator core accordingly has a plurality of stator teeth directed radially outwards. In an intended installation situation, the stator teeth are preferably each wound around by a stator winding.

Furthermore, several, preferably more than two, in particular more than four fastening sections are arranged on the stator yoke on a side radially facing away from the stator teeth, which are designed and/or suitable for the axial fastening of the stator to a housing. In other words, the stator core can be fastened to the front side of the housing via the fastening sections. In particular, the stator core is and/or can be fastened to the housing in a rotationally fixed manner, in particular in a torque-transmitting manner, via the fastening sections. The stator core is particularly preferably non-positively mounted on the housing via the fastening sections, preferably via a screw connection. The housing can be designed as a motor housing or a transmission housing, in particular a transmission bell housing, of an electric drive train. The stator core has first and second axial faces. The first end face forms a fastening side for the axial fastening of the stator to the housing and the second end face forms an outer side of the stator facing away from the fastening side. In particular, the two end faces are to be understood in relation to a main axis of the stator, preferably a main axis of the electrical machine. Specifically, the first axial face extends in a first radial plane of the main axis of rotation and the second axial face extends in a second radial plane of the main axis.

In the context of the invention, it is proposed that the stator has a stiffening ring, which is mounted on the outside of the stator yoke on the peripheral side to stiffen the stator core. In particular, the stiffening ring is used to stiffen the stator yoke on the second axial end face or the outside. The stator core is inherently elastic and can deform in a large number of different natural modes, e.g. due to magnetic forces acting on it, with the stiffening ring stiffening the stator yoke, particularly in the radial direction, and thus the entire stator core, in such a way that vibration modes, particularly on the outside, is reduced. The stiffening ring is preferably supported on the outer circumference of the stator yoke in an embodiment as an internal rotor and on the inner circumference of the stator yoke in an embodiment as an external rotor.

The invention is based on the finding that during operation of the electrical machine, the geometric conditions of the stator result in natural modes that can vary in shape and natural frequency. If these natural frequencies are in an excitation-relevant frequency range of the drive components, such as the electric machine or the gearing components of the transmission, resonance events with corresponding acoustic abnormalities can occur in the drive train, which have the disadvantage, for example, of increased noise development and additional loading and the associated wear of the components connected to the stator. By stiffening the stator core, high excitation forces resulting from the (natural) vibration can be suppressed at the fastening points of the stator core and the acoustic abnormalities can thus be significantly reduced. A stator is thus proposed which is distinguished by improved operating behavior, in particular low-noise operation.

In a specific embodiment, it is provided that the stiffening ring is supported in a form-fitting and/or force-fitting manner on the stator yoke in the radial direction and/or in the circumferential direction. In particular, the stiffening ring causes a force, in particular in the radial direction and/or in the circumferential direction, on the stator yoke, so that a vibration of the stator core is damped and/or a natural frequency of the natural vibration of the stator core is specifically shifted, in particular increased, into a frequency range in which vibration excitation is not to be expected. In particular, the force counteracts the vibrations (natural modes) that occur on the outside of the stator core. The structure-borne noise of the stator core, which can occur, for example, as a result of the magnetic forces acting in the electric machine, can thus be at least partially decoupled or dampened from the drive train or the fastening sections. In this way, the acoustics of the electric motor are improved and wear that occurs as a result of the vibration is prevented.

In a specific constructive implementation, it is provided that the stator yoke has a toothing geometry at least in sections on the circumference, in particular on the radial side facing away from the stator teeth, on which the stiffening ring for damping vibrations, in particular the natural vibrations of the stator core, in the circumferential direction and/or in the radial direction Direction is resiliently supported in several contact areas on the gear geometry. In particular, the stiffening ring is supported in the circumferential direction and/or in the radial direction without play and/or under the action of a spring force in the contact areas on the toothing geometry. In particular, when the stator core vibrates, the spring force acts as the force acting on the stator yoke to dampen the vibration of the stator core. For this purpose, the stiffening ring is preferably designed to be resiliently deformable, at least in the contact areas. The The stiffening ring can be made of a resilient material, eg spring steel, and/or can be designed geometrically as a spring element. The toothing geometry is preferably formed by a plurality of grooves and/or webs running in the axial direction in relation to the main axis. The toothing geometry can be formed in sections between the fastening sections in the circumferential direction. Alternatively, however, the toothing geometry can also be formed over the entire circumference. A stiffening ring is thus proposed which, due to the resilient support, prevents the stator from oscillating by means of a spring function.

In a further specification it is provided that an elastomer layer is arranged between the toothing geometry and the stiffening ring at least in the contact areas. In particular, the stiffening ring can take on the function of a damping element through the elastomer layer, as a result of which precise tuning to the frequency to be damped can be implemented. The elastomeric layer is preferably elastically deformable, vibration damping being implemented as a result of an elastic deformation of the elastomeric layer and possibly a resilient deformation of the stiffening ring. The elastomer layer can optionally be arranged over the entire surface or partially or in certain areas, in particular in the contact areas on the stiffening ring and/or the toothing geometry. In particular, the elastomer layer is arranged in at least one, several or in all contact areas. For example, the elastomer layer is formed by a rubber coating or an elastic insert. To a large extent, tolerances can be compensated for by the elastomer layer in order to ensure a play-free assembly of the stiffening ring on the stator yoke.

In a further specific embodiment it is provided that the stiffening ring is materially connected to the stator core at least in one or more connection areas. In particular, a vibration node for the natural vibrations of the stator core can be formed by the connection areas. Viewed in the circumferential direction, at least or exactly one connection area is preferably provided between each two fastening sections. In particular, the stiffening ring is welded to the stator core in the connection areas. Through the integral connection of the stiffening ring can thus be a targeted tuning of the natural vibration and / or natural frequency of the stator core.

In a further development it is provided that the stiffening ring is arranged in the radial direction at a distance from a tip circle diameter and/or root circle diameter of the toothing geometry. In other words, the stiffening ring is designed in such a way that it is supported exclusively on the tooth flanks of the toothing geometry. In particular, an air gap is formed between the tip circle diameter and/or the root circle diameter, which is delimited in the circumferential direction by the contact areas. As a result, a spring-elastic deformation of the stiffening ring can be realized outside the contact areas, so that a spring function of the stiffening ring is ensured in the radial direction and in the circumferential direction.

In a constructive implementation, the stiffening ring is designed as a wavy sheet metal ring, which interacts with the toothing geometry in a form-fitting manner. In particular, the sheet metal ring is designed to form a form fit with the toothing geometry in the radial direction and/or in the circumferential direction, with the form fit preferably being produced by axially joining the stator core and reinforcing ring. The sheet metal ring preferably has a corrugated shape which is complementary to the toothing geometry. In particular, the sheet metal ring acts as a spring element via the corrugated shape and the sheet metal thickness and can therefore influence the vibrations of the stator core.

In a further specific embodiment, it is provided that the corrugated sheet metal ring, viewed in a cross section, has alternately arranged tooth gap sections and tooth tip sections, which adjoin or are connected to one another via a radius to form the corrugated shape. The stiffening ring is resiliently supported via the radii in the contact areas on the tooth flanks of the toothing geometry. In particular, the tooth space sections are formed by depressions formed radially into the tooth spaces of the toothing geometry and/or the tooth head sections are formed by elevations radially receiving the teeth of the toothing geometry. The tooth gap sections are spaced from the root circle diameter and the tooth tip sections from the addendum circle diameter to form the radial distance. The sheet metal ring is preferably produced by forming. A stiffening ring is thus proposed which is characterized by particularly simple and cost-effective production.

In a further embodiment, it is provided that the stiffening ring has a circumferential collar section, the stiffening ring being supported in the axial direction on the outside of the stator core via the collar section. In particular, the collar section forms an axial stop for the stiffening ring during assembly. The collar section preferably extends in a radial plane of the main axis and/or parallel to the first axial end face or the outside of the stator core. In particular, the collar section serves to increase the rigidity of the stiffening ring. It is thus possible to influence the rigidity of the stator core in a targeted manner by selecting or designing the collar section.

In a development it is provided that the fastening sections each have a screw means receptacle for receiving a screw means and the stiffening ring has a passage opening for each screw means receptacle for passing through the respective screw means. In particular, the screw means receptacles are designed as through bores running axially in relation to the main axis or in the same direction as the main axis. The screwing means are preferably designed with a screw head, e.g. For assembly, the screw means are guided from the outside via the lead-through openings into the respective screw means receptacle and can be screwed or screwed with their free end into corresponding threaded bores in the housing. In an intended installation situation, the screw means are preferably supported with their screw heads in the axial direction on the reinforcing ring. By guiding the screwing means via the stiffening ring, the excitation forces acting on the fastening interfaces can be influenced in a targeted manner.

In a further embodiment it is provided that the stator core and the stiffening ring are made of different materials. In particular, by a With a suitable choice of material, the mass of the stator core can be changed on the outside in such a way that the natural vibration of the stator is damped and/or the resonance frequency is influenced or shifted, in particular increased. Another embodiment provides that the stiffening ring is arranged on the outside in an edge area of the stator yoke. In particular, the stiffening ring is to be understood as a narrow ring which is supported exclusively in the edge area or on the edge side on the stator yoke. In other words, the stiffening ring extends in the axial direction over less than 10%, preferably less than 5%, of an overall axial width of the stator core. In particular, the edge area is to be understood as a circumferential outer edge. In particular, the stiffening ring is recessed at the location of the attachment section.

In a further embodiment, it is provided that the stator core is designed as a laminated stator core with a plurality of stator laminations stacked axially one on top of the other. The stator laminations can be designed in one piece or in multiple pieces, in particular in segments. The individual stator laminations are preferably joined together by means of a joining process to form an overall composite or a plurality of individual composites. For example, the connection method can include gluing (e.g. baked lacquer) and/or welding and/or stamped packeting of the stator laminations.

In a further specification, it is provided that the stator core is designed as a multi-part stator core, the stator cores being joined together to form a plurality of individual composites. In particular, the laminated stator core can be designed as a three-part laminated stator core, with the laminated stator core having three individual composites for this purpose, which stacked in the axial direction form the laminated stator core.

The invention further relates to an electrical machine with a stator designed as described above. Another subject of the invention relates to an electric drive train, in particular for a vehicle, preferably for a hybrid or electric vehicle. The drive train has a transmission and an electric machine with the stator, as has already been described above. In particular, the transmission is used to translate and/or distribute a drive torque of the electrical machine. The electrical machine has a rotor which is and/or can be connected to a transmission shaft of the transmission preferably in terms of drive technology. According to the invention it is provided that the stator, in particular the stator core, is mounted with its first axial end face or the fastening side on the housing of the transmission. The stator core is preferably screwed to the housing of the transmission via the screw means, with the stiffening ring being arranged on the outside of the stator core facing away from the housing. Thus, the high excitation forces generated by vibrations of the stator core on the screw connection of the stator core to the housing of the transmission can be suppressed.

Further features, advantages and effects of the invention result from the following description of preferred exemplary embodiments of the invention. show:

FIG. 1 shows a schematic representation of an electric drive train as an exemplary embodiment of the invention;

FIG. 2 shows a representation of natural modes of a stator core during operation of the electric drive train;

FIG. 3 shows an axial representation of a stator for an electric machine of the electric drive train;

FIG. 4 shows a detailed view of the stator of FIG. 3;

Figure 5 shows a further detailed view of the stator of Figure 3.

FIG. 1 shows, in an axial view with respect to a main axis H, an electric drive train 1 which is used, for example, to drive a vehicle. The drive train 1 has an electric machine 2 for generating a drive torque and a transmission 3 for converting the drive torque to at least one driven wheel, not shown, of the vehicle. The electrical machine 2 is designed as an internal rotor, with the electrical machine 2 having a stator 4 and a rotor 5 rotatably mounted within the stator 4 for this purpose. The rotor 5 is connected in a rotationally fixed manner to a rotor shaft 6 , the rotor shaft 6 being mounted such that it can rotate about the main axis H and being connected to the transmission 3 in terms of drive or transmission technology. The stator 4 forms a stationary or fixed part, which is firmly connected to a housing 7 of the transmission 3 in the axial direction with respect to the main axis H.

The stator 4 has a stator core 8 with a stator yoke 9 on which a plurality of stator teeth 10 directed radially inward are arranged in the circumferential direction, each carrying a stator winding 11 . The stator core 8 is formed, for example, by a plurality of stator laminations stacked one on top of the other in the axial direction, which are combined to form an overall composite by a joining method, e.g.

On its outer circumference, the stator core 8 has three attachment sections 12 for axially attaching the stator core 8 to the housing 7 . For this purpose, the fastening sections 12 each have a screw means receptacle 13 , via which a screw means 14 is guided and screwed into a corresponding threaded bore of the housing 7 . The screw means receptacles 13 are designed, for example, as through-bores which are aligned parallel to the main axis H and are arranged on a common reference circle around the main axis H, spaced evenly apart from one another. The screwing means 14 are designed, for example, as cylinder head screws, with the screwing means 14 being supported axially on the fastening sections 12 via a screw head in order to fix the stator core 8 on the housing 7 in a non-positive manner.

As shown in FIG. 2, when the stator core 8 is fixed to the housing 7 during operation, it exhibits radial natural oscillations (natural modes), which can vary in form and frequency. If these natural frequencies are in the excitation-relevant frequency range of the drive components, such as the electric machine 2 or the transmission 3, resonance events can occur with speaking acoustic abnormalities in the drive train 1 come. The schematically drawn stator teeth 10 of the stator core 8 form a perpendicular to the natural oscillation, which is not true to scale. The attachment sections 12 each form an oscillation node, with the stator core 8 behaving at least approximately statically in the oscillation nodes.

Figure 3 shows the stator 4 in an axial view with respect to the main axis H.

In order to counteract the radial natural vibrations of the stator core 3, the stator 4 has a stiffening ring 15 which is supported at least in a form-fitting manner in relation to the main axis H on an outer circumference of the stator yoke 9 in the radial direction and in the circumferential direction. By stiffening the stator core 8, the vibration modes are limited in such a way that natural vibrations cannot form in the stator yoke 9 and thus in the entire stator core 8, or at least to a much lesser extent.

The stator core 8 has a toothing geometry 16 in sections on its outer circumference between the fastening sections 12 . The stiffening ring 15 is designed as a wavy sheet metal ring, which interacts with the toothing geometry 16 in a form-fitting manner in the radial direction and in the circumferential direction. For this purpose, the stiffening ring 15 has a corrugated shape which is geometrically similar to the toothing geometry 16 and is in positive engagement with it. For this purpose, the stiffening ring 15 is pushed onto the stator yoke 9 in the axial direction in relation to the main axis H in order to form the form fit.

FIG. 4 shows a detailed illustration of the stator 4. The stiffening ring 15 has tooth space sections 17 and tooth tip sections 18 arranged alternately in the circumferential direction, which are connected to one another via a radius 19 in order to form the waveform. The tooth space sections 17 are formed as indentations molded into the tooth spaces 20 of the toothing geometry 16 and the tooth tip sections 18 are formed as the teeth 21 of the toothing geometry 16 receiving elevations. The tooth gap sections 17 are arranged spaced apart in the radial direction at a distance A1 from a root circle diameter, in particular of the tooth gaps 20 . The tooth tip sections 18 are in the radial direction a distance A2 from a tip circle diameter, in particular of the teeth 21 . The stiffening ring 15 is resiliently supported in the radial direction and in the circumferential direction via the radii 19 on the tooth flanks 22 .

For this purpose, the stiffening ring 15 rests without play via the radii 19 in a contact area 22 on the tooth flanks 23 and is resiliently deformable in the region of the tooth gap sections 17 and the tooth tip sections 18, with a metal-to-metal connection of the stiffening ring 15 via the shape of the Wave shape and the sheet thickness acts as a spring element and can thus influence the vibrations of the stator core 8 . For this purpose, the stiffening ring 15 causes a force in the radial direction and/or in the circumferential direction, in particular a spring force, which counteracts the natural mode of the stator core, so that the natural vibration of the stator core is damped and/or a natural frequency of the natural vibration of the stator core is specifically shifted into a frequency range in which no vibration excitation is to be expected.

To improve the system further, an elastomer layer 24 is arranged in the contact areas 22 between the stiffening ring 15 and the toothing geometry 16 . The elastomer layer 24 can be formed, for example, by rubber coating the tooth flanks 23 and/or rubber coating the radii 19 . Alternatively, however, the elastomer layer 19 can also be formed by an elastic insert. As a result, the stiffening ring 15 can act as a spring-damper element on the stator core 8, with the stiffening ring 15 taking on a spring function due to the wave shape and the elastomer layer 24 taking on a damping function. Thus, an exact tuning of the stiffening ring 15 to the frequency of the stator core 8 to be damped is possible. Thus, a disruptive natural vibration or natural frequency can be damped by means of the stiffening ring 15 in order to avoid unwanted resonance effects.

FIG. 5 shows the stator 4 in a three-dimensional representation. The stator 4 is fastened in the axial direction in relation to the main axis H with a first axial end face on the housing 7, as shown in FIG. Thus, the first axial end face forms a fastening side 25 of the stator core 8. The Stiffening ring 15 is arranged on a second axial end face of stator core 8 , which forms an outer side 26 of stator core 8 facing away from fastening side 25 .

As can be seen from FIG. 5, the stiffening ring 15 is arranged on the outside in an edge area 27 of the stator core 8 . The stiffening ring 15 is cut out in the area of the fastening sections 12 so that the stiffening ring bears exclusively or at least for the most part in the area of the toothing geometry 16 on the outer circumference of the stator core 8 .

The stiffening ring 15 has a circumferential collar section 28 via which the stiffening ring 15 is supported in the axial direction in relation to the main axis H on the outside 26 of the stator core 8 . The collar section 28 serves on the one hand as an axial end stop and on the other hand to increase the rigidity of the stiffening ring 15.

The stiffening ring 15 has a feed-through opening 29 for each screw means 14, via which the screw means 14 are guided into the respectively associated screw means receptacle 13, as described in FIG. The lead-through openings 29 are in the form of through-holes made in the collar section 28 , the screw means 14 being supported with the screw head on the collar section 28 in an assembled state in order to clamp the stator core 8 to the housing 7 .

The stiffening ring 15 can also be cohesively connected to the stator core 8 in one or more connection areas 30 . For example, the stiffening ring 15 is welded to the stator core 8 in the connection areas 30 . Due to the integral connection of the stiffening ring 15, additional vibration nodes for the natural modes of the stator core 8 can be formed, as in FIG. This allows the natural vibration and / or natural frequency of the stator core 7 and thus the noise during operation electrical machine 2 are specifically influenced. For example, a connection area 30 is formed in each case, viewed in the circumferential direction, by the two contact areas 22 that are adjacent or closest to the fastening sections 12 . A solution for suppressing high excitation forces due to vibrations on the screw means 14 is thus proposed.

reference sign

Drive train electric machine

transmission

stator

rotor

rotor shaft

Housing

stator core

stator yoke

stator teeth

stator winding

attachment sections

screw mounts

screw means

stiffening ring

gear geometry

tooth gap sections

Tooth Head Sections

radius

tooth gap

Tooth

contact area

tooth flank

elastomer layer

mounting side

outside

edge area

waistband section

feedthrough opening

connection area A1 , A2 distances

H major axis

Claims

patent claims

1 . Stator (4) for an electrical machine (2), with a stator core (8), the stator core (8) having an annular stator yoke (9) on which a plurality of radially protruding stator teeth (10) are mounted on one radial side in the circumferential direction. and on the other radial side, a plurality of fastening sections (12) for fastening the stator (4) to the end face of a housing (7) are arranged, a first end face of the stator core (8) having a fastening side (25) for fastening the stator (4) axially on the housing (7) and a second axial end face forms an outside (26) of the stator (4), characterized by a stiffening ring (15) for stiffening the stator core (8), the stiffening ring (15) on the outside (26) is mounted peripherally on the stator yoke (9).

2. Stator (4) according to claim 1, characterized in that the stiffening ring (15) with respect to a main axis (H) in the radial direction and / or in the circumferential direction is positively and / or non-positively supported on the stator yoke (9).

3. Stator (4) according to Claim 1 or 2, characterized in that the stator yoke (9) has a toothing geometry (16) at least in sections on its outer circumference, the stiffening ring (15) for damping vibrations in the radial direction and/or in Circumferentially resiliently supported in several contact areas on the toothing geometry (16).

4. Stator (4) according to claim 3, characterized in that an elastomer layer (22) is arranged at least in the contact areas between the stiffening ring (15) and the toothing geometry (16).

5. Stator (4) according to any one of claims 1 to 4, characterized in that the stiffening ring (15) is materially connected to the stator core (9) at least in a connection area (30).

6. Stator (4) according to one of claims 3 to 5, characterized in that the stiffening ring (15) in the radial direction at a distance (A1) to a tip circle diameter and / or in the radial direction at a distance (A2) to a root circle diameter the gear geometry (16) is arranged.

7. Stator (4) according to one of claims 3 to 6, characterized in that the stiffening ring (15) is designed as a wavy sheet metal ring, the sheet metal ring interacting with the tooth geometry (16) in a form-fitting manner.

8. Stator (4) according to claim 7, characterized in that the stiffening ring (15), viewed in a cross section, has tooth space sections (17) and tooth head sections (18) arranged alternately, the tooth space sections (17) and the tooth head sections (18) each connect to one another via a radius (19), the stiffening ring (15) being resiliently supported via the radii (19) in the contact areas (22) on the tooth flanks (23) of the toothing geometry (16).

9. The stator (4) according to any one of the preceding claims, characterized in that the stiffening ring (15) has a peripheral collar section (28), the stiffening ring (15) via the collar section (28) in the axial direction on the outside (26) of the stator core (8) is supported.

10. Stator (4) according to one of the preceding claims, characterized in that the fastening sections (12) each have a screw means receptacle (13) for receiving a screw means (14) and the stiffening ring (15) each screw means receptacle (13) has a feedthrough opening (29 ) for carrying out the respective screw means (14).

11 . Stator (4) according to one of the preceding claims, characterized in that the stator core (8) and the stiffening ring (15) are made of a different material.

12. Stator (4) according to one of the preceding claims, characterized in that the stiffening ring (15) is arranged in an edge region (27) of the stator yoke (9).

13. Stator (4) according to any one of the preceding claims, characterized in that the stator core (8) is designed as a stator core with a plurality of axially stacked stator laminations.

14. Stator (4) according to claim 13, characterized in that the stator core is designed as a multi-part stator core, wherein the stator cores are joined together to form a plurality of individual composites.

15. Electrical machine (2) with a stator (4), which is designed according to one of the preceding claims.

16. Electric drive train (1), comprising, a transmission (3) and an electric machine (2) with a stator (4) according to claim 15, wherein the stator (4) with its attachment side (25) on a housing (7) of the gearbox (3) is mounted in a torque-transmitting manner.

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