Stator for an electric machine

Abstract

The invention relates to a stator (2) for an electric machine (1), comprising a stator main part (3) which has at least two stator segments (4-7) arranged adjacently to one another in the circumferential direction, wherein a channel (8) is formed between the at least two stator segments (4-7), the channel being designed to guide a temperature-control medium, and a sealing device (9) is designed to seal the channel (8) radially inwards in the radial direction of the stator main part (3).

Description

[0001] ZF Friedrichshafen AG File 304717 Friedrichshafen 2025-11-04

[0002] Stator for an electric machine

[0003] The invention relates to a stator for an electric machine.

[0004] Electrical machines, in particular electric machines for motor vehicles, which have a stator and a rotor rotatably mounted relative to the stator, are generally known from the prior art. For cooling or temperature control of the stator, a temperature control medium is usually guided through at least one channel in the stator, so that heat exchange can take place between the temperature control medium and the stator, in particular a stator core or conductor elements of the stator.

[0005] To achieve the most efficient temperature control, and in particular to cool the stator core as efficiently as possible during operation, it is advantageous to direct the temperature control fluid as close as possible to the points where heat is generated, especially near the conductor elements running within the stator core. However, it is essential to ensure that the temperature control fluid cannot enter the rotor chamber of the electric machine, which is bounded by the stator core. Specifically, the temperature control fluid should not enter any gap between the rotor, which is rotatably mounted within the stator core, and the inner wall or surface of the stator core.

[0006] Specifically, stator bodies are known that are formed from a multitude of axially adjacent sheet metal laminations. A channel for guiding the temperature control fluid can run axially through the individual laminations and thus be closed. Another possibility is to form a canned tube, for example made of a composite material, and insert it into a stator opening in the stator body, so that the canned tube separates the rotor chamber from the stator chamber.

[0007] The invention is based on the objective of providing an improved stator for an electric machine, in which, in particular, the guidance of the temperature control fluid is improved. ZF Friedrichshafen AG File 304717 Friedrichshafen 2025-11-04

[0008] The problem is solved by a stator having the features of claim 1. Advantageous embodiments are the subject of the dependent claims.

[0009] The invention relates to a stator for an electric machine. The electric machine can, in particular, be configured as a drive unit for a motor vehicle. For example, the electric machine can be part of a drive train for such a motor vehicle.

[0010] The stator comprises a stator body having at least two stator segments arranged adjacent to each other in the circumferential direction. In contrast to the stator or stator body previously described with reference to the prior art, which is formed from axially adjacent sheet metal laminations, the stator body described herein is constructed from stator segments that extend axially, in particular continuously between the axial end faces of the stator body, and that are arranged adjacent to each other in the circumferential direction. The stator body can thus be understood as being made up of "individual teeth" that extend over the axial extent of the stator body and are arranged adjacent to each other in the circumferential direction, thereby forming the stator body. This means that a gap is formed between each pair of stator segments in the circumferential direction.an interface where the two stator segments touch or abut each other.

[0011] The stator described herein is designed to have a channel between at least two stator segments for guiding a temperature control fluid. In other words, the temperature control fluid can be guided in a channel formed between the two stator segments, or between each pair of stator segments. This means that the channel can be bounded, at least partially, by one stator segment and at least partially by the other stator segment. ZF Friedrichshafen AG File 304717 Friedrichshafen 2025-11-04

[0012] The stator also features a sealing device designed to seal the channel radially inwards along the stator body. Temperature control fluid can thus be guided through this channel, particularly between the two stator segments or between any two stator segments. To prevent the temperature control fluid from escaping radially inwards from the stator body, the sealing device is provided, which seals the channel radially inwards, preventing the temperature control fluid from flowing radially inwards and thus from entering the gap or the rotor chamber.

[0013] Advantageously, it is therefore possible to guide temperature control fluid through channels between the stator segments, which are constructed from the stator segments described above. This allows for heat exchange, heat dissipation, or heat input as close as possible to the point(s) where heat is generated or to which it is to be transferred for heating. The term "temperature control" generally refers to both heating and cooling. Specifically, during operation of the electric machine, heat can be generated by the electrical conductors running within the stator core. This heat can be dissipated by the temperature control fluid. It is therefore advantageous to guide the temperature control fluid as close as possible to the electrical conductors to ensure the most efficient heat dissipation.

[0014] The individual stator segments can be connected to a stator ring, a housing, or a stator support. In this way, the channels can be sealed radially outwards, particularly by means of a stator ring, housing, or stator support. The sealing device described herein can therefore advantageously be used to provide a radial inward seal for the temperature control fluid. In particular, the sealing device can be designed exclusively for radial inward sealing.

[0015] The stator described may further be provided for in the channel that at least one electrical conductor element, or at least one hairpin conductor element, can be received or accommodated, or that the channel is separate, in particular ZF Friedrichshafen AG File 304717 Friedrichshafen 2025-11-04

[0016] The channel is arranged radially outside a conductor element receptacle that accommodates at least one electrical conductor element. In principle, it is therefore possible to design the channel as an "in-slot" or "near-slot" temperature control system, in which the electrical conductor elements to be temperature-controlled by the temperature control medium are located within the channel, allowing the temperature control medium to flow directly around them. Alternatively, the channel can run close to the conductor element receptacle in which the electrical conductor elements are held. In the second described embodiment, the electrical conductor elements, viewed radially, can be located further inward in the direction of the central axis or axis of rotation than the channel. In the first described embodiment, the electrical conductor elements are located in the same radial area as the channel, or the channel simultaneously defines the conductor element receptacle.The canal forms these.

[0017] In a further extension of the stator, a sealing element may be arranged in the channel, particularly at a radially inner channel end section. This sealing element prevents the cooling fluid from flowing radially inwards. In other words, the sealing element forms a barrier for the cooling fluid in the radial direction, which the fluid cannot overcome. Thus, the sealing element defines the boundary for the cooling fluid in the radial direction, so that the cooling fluid can only flow radially outside the sealing element. Specifically, the sealing element is arranged in or at a channel end section that is located radially further inwards relative to the rest of the channel.The sealing element can thus ensure, for both "in-slot" and "near-slot" versions, that the temperature control fluid cannot penetrate further inwards in a radial direction.

[0018] According to a further embodiment of the stator, the sealing element can be pre-tensioned or pre-tensioned in the radial direction by at least one conductor element and is designed to transmit the pre-tension force circumferentially to the stator segments. For example, in an assembled state of the stator, in which the conductor elements are in the ZF Friedrichshafen AG File 304717 Friedrichshafen 2025-11-04

[0019] The conductor elements are arranged in a channel, transmitting a preload force to the sealing element in the radial direction. This inherently preloads the sealing element in the radial direction. The sealing element is designed to redirect the force, so that the preload force introduced into the sealing element via the conductor elements is transferred circumferentially to the stator segments.

[0020] This causes the sealing element to press against the adjacent stator segments in the circumferential direction, thus exerting no force, or at least no significant force, in the radial direction on the end sections of the stator segments, which are typically designed with a delicate profile to optimize electromagnetics. Since the stator segments are usually made of a material with relatively low strength, most often a sintered material, particularly SMC (soft magnetic composite), the described force diversion or redirection provides protection for the stator segments.

[0021] The at least one sealing element has a specific shape to effect force redirection or diversion when force is applied via the at least one conductor element. The preload force is generated in particular by the radially stacked conductor elements in the same channel, since these, in their stacked state, create a preload and can transmit this preload force to the sealing element.

[0022] Specifically, the sealing element can be bent radially in the direction of at least one conductor element received in the channel, at least in an unloaded state. In other words, the sealing element is curved or bent, with the center of curvature located radially inwards. When the sealing element is installed and subjected to the preload force by the guide elements or the at least one conductor element, the sealing element deforms, thus causing the force redirection described above. ZF Friedrichshafen AG File 304717 Friedrichshafen 2025-11-04

[0023] The sealing element can further have defined contact points, wherein at least one first contact point faces the at least one conductor element and is in contact with it in the assembled state, and at least one second and third contact point are in contact with the circumferentially adjacent stator segments, so that a defined contact, in particular a defined contact surface or a line contact, is formed. The contact points can be circular in cross-section or designed as a circular segment. The sealing element can, for example, be made of an elastomer.

[0024] The stator may further be provided with a sealing device that includes an electrical insulating element, in particular insulating paper, or is designed as an electrical insulating element. In this embodiment, a previously described sealing element is not required, although combinations of the sealing element with the insulating element are possible. The electrical insulating element can be used to provide or support the sealing effect.

[0025] The electrical insulating device, for example insulating paper, can be made of a composite material, such as paper with a specific coating or a matrix material impregnated with a resin and cured. In cross-section, the electrical insulating device can form a U-shape within the channel, which may be open radially outwards or have a feed opening for the supply of the cooling fluid. The cooling fluid can be fed into the channel from the radial outside, centrally located between the two axial end faces of the stator body. Alternatively, the cooling fluid can be fed from one axial end face and flow through the channel towards the opposite axial end face. In the second alternative, the electrical insulating device can also completely enclose the channel in cross-section, thus forming an O-shape.

[0026] In principle, the electrical insulating device can be applied to one flank of a first stator segment, for example by gluing it on, and when the stator segments are joined to the circumferentially opposite flank of the ZF Friedrichshafen AG file 304717 Friedrichshafen 2025-11-04

[0027] The electrical insulating device can be attached to the adjacent stator segment, for example by gluing. As described, a gap can remain radially outwards, or the electrical insulating device can be arranged around the entire channel.

[0028] In a further embodiment of the stator, the sealing device may include at least one sealing element, in particular a sealing ring, which surrounds a stator segment. For example, the sealing element may be designed as a sealing ring, such as an O-ring, and extend continuously around the stator segment, i.e., completely encircling the stator segment. Thus, such a sealing element can be arranged circumferentially on every second stator segment, sealing the channels formed between the stator segment on which the sealing element is arranged and the adjacent stator segments in the circumferential direction. Advantageously, the sealing element can be applied to or arranged on the stator segment, and the sealing element can be applied under preload and thus be self-locking.The sealing element itself can be a relatively simple sealing element, such as an O-ring. The sealing element can be made of or comprise an elastomer.

[0029] In the described embodiment, it can also be provided that the at least one sealing element is arranged in a circumferentially open groove in each of two circumferentially adjacent stator segments. For example, each stator segment can have a circumferential groove, such that the two grooves on each stator segment are opposite each other circumferentially. A receptacle for the sealing element is thus formed partially by the stator segment on which the sealing element is arranged and by the stator segment that is circumferentially adjacent to the stator segment containing the sealing element.When the sealing element is arranged on the stator segment, the preload force for fastening the sealing element can act circumferentially and thus not radially on the comparatively delicate end sections of the stator segment, as previously described. ZF Friedrichshafen AG File 304717 Friedrichshafen 2025-11-04.

[0030] In a further embodiment of the stator, the at least two stator segments may have circumferentially directed, and in particular electromagnetically optimized, extensions at a radially inner end region. As described, the sealing device should be designed, or the sealing element arranged on the stator segments, such that the force, for example a preload force, acts on the stator segments as far as possible in the circumferential direction and is not, in particular, exclusively in the radial direction. Specifically, the preload force should act predominantly in the circumferential direction. The extensions of the stator segments are thereby protected by the sealing device.In particular, in an embodiment where the sealing element is radially spaced from the extensions, for example in a separate design of the channel for a conductor element receptacle, the extensions can be electromagnetically optimized, since no consideration needs to be given to the arrangement of a sealing element.

[0031] In addition to the stator described above, the invention relates to an electric machine comprising such a stator. Furthermore, the invention relates to a drive train comprising such an electric machine and / or a stator described above. The invention also relates to a motor vehicle comprising such a drive train and / or an electric machine and / or a stator described above.

[0032] All the advantages, details and features described in relation to the stator are fully transferable to the electric machine, the drive train and the motor vehicle.

[0033] The invention is explained below with reference to exemplary embodiments and the figures. The figures are schematic representations and show: ZF Friedrichshafen AG File 304717 Friedrichshafen 2025-11-04

[0034] Fig. 1 shows a schematic representation of a sectional view of an electrical machine according to a first embodiment;

[0035] Fig. 2 shows a detail of Fig. 1;

[0036] Fig. 3 shows a schematic representation of a sectional view of an electrical machine according to a second embodiment;

[0037] Fig. 4 shows a schematic representation of a stator segment from Fig. 3 in perspective view;

[0038] Fig. 5 shows a schematic representation of a stator segment from Fig. 3 in perspective view;

[0039] Fig. 6 shows a schematic representation of a first sectional view of an electrical machine according to a third embodiment;

[0040] Fig. 7 shows the electric machine of Fig. 6 in a second sectional view;

[0041] Fig. 8 shows a schematic representation of a stator segment from Fig. 6, 7 in perspective view;

[0042] Fig. 9 shows a schematic representation of a stator segment from Fig. 6, 7 in perspective view;

[0043] Fig. 10 shows a schematic representation of a first sectional view of an electrical machine according to a fourth embodiment;

[0044] Fig. 11 shows the electric machine of Fig. 10 in a second sectional view;

[0045] Fig. 12 shows a schematic representation of a stator segment from Figs. 10, 11 in perspective view; and

[0046] Fig. 13 shows a schematic representation of a stator segment from Figs. 10 and 11 in perspective. ZF Friedrichshafen AG File 304717 Friedrichshafen 2025-11-04

[0047] Fig. 1 shows a section of a cross-sectional view of an electric machine 1, which comprises a stator 2 with a stator body 3. The stator body 3 has several stator segments 4-7, of which only four are shown by way of example. The stator segments 4-7 extend axially, i.e., in Fig. 1, into the plane of the drawing or out of it from one axial end face of the stator body 3 to the opposite one. The stator segments 4-7 are adjacent to each other circumferentially, i.e., arranged circumferentially with respect to a central axis or axis of rotation of the electric machine 1, and thus form the stator body 3.

[0048] A channel 8 is formed between each pair of stator segments 4-7, designed to guide a temperature control fluid. Furthermore, the electric machine 1, in particular the stator 2, has a sealing device 9 that provides a sealing element 10 for the channel 8. The sealing device 9 is designed to seal the channel 8 radially inwards, i.e., in the direction of the central axis or axis of rotation of the electric machine 1 or the stator body 3. This means that the temperature control fluid cannot escape radially inwards from the space between the stator segments 4-7. Instead, the temperature control fluid is guided in a defined axial direction through the channel 8. The foregoing description is applicable to all subsequent embodiments.

[0049] Fig. 2 shows a detail of the representation in Fig. 1, illustrating that electrical conductor elements 11 are arranged in the channel 8. These conductor elements 11 are, for example, copper wires surrounded by an insulating layer, such as a plastic layer. The conductor elements 11 are radially stacked in the channel 8, thus exerting a preload force on the sealing element 10, as indicated by arrow 12. The sealing element 10 is pre-bent in the direction of the conductor elements 11 and, due to the preload force, causes a force redirection, as indicated by arrow 13. This means that the force with which the sealing element 10 is preloaded against the stator segments 4-7 acts essentially circumferentially and not radially, thus protecting the extensions 14 of the stator segments 4-7, as these are not subjected to radial stress.The sealing device 9 thus seals the channel 8 at a channel end section 15 ZF Friedrichshafen AG File 304717 Friedrichshafen 2025-11-04.

[0050] sealed, which channel end section 15 is radially internal, for example with respect to a center of the channel 8 in the radial direction.

[0051] Fig. 3 shows a section of a sectional view of an electric machine 1 according to a third embodiment. The electric machine 1 of Figs. 3-6 is fundamentally constructed analogously to the electric machine 1 of Figs. 1, 2, so that the same reference numerals are used for the same components. The stator body 3 of the electric machine 1 thus also has a plurality of stator segments 4-7, between which channels 8 are formed in which conductor elements 11 are arranged.

[0052] In contrast to the embodiment shown in Figures 1 and 2, the sealing device 9 is formed by an electrical insulating device 16, for example, insulating paper. The insulating paper or the electrical insulating device 16 can, for example, be a composite material, i.e., a matrix material impregnated with a resin material and cured. The insulating device 16 thus forms a sealing element of the sealing device 9 and seals the channel 8 radially inwards. In cross-section, the insulating device 16 forms an LI shape, which can be open radially outwards, or an O shape, which completely encloses the channel 8.

[0053] Figure 4 shows that the insulating device 16 can be arranged on a flank of a stator segment 4-7, for example, by gluing it in place. The insulating device 16 is folded accordingly and thus, as shown for example in Figure 5, arranged with its opposite side against a flank of the circumferentially adjacent stator segment 4-7, for example, by gluing it in place. The insulating device 16 can have at least a radially outer opening 17 through which a temperature control medium can be introduced through the stator segments 4-7, for example, centrally, into the channel 8. Alternatively, the insulating device 16 can also be completely open radially outwards, for example, in a U-shape. Alternatively, it is also possible to supply the temperature control medium at an axial end face of the stator base body 3 and to allow the temperature control medium to flow through the channel 8 in the direction of the opposite axial end face of the stator base body 3.ZF Friedrichshafen AG File 304717 Friedrichshafen 2025-11-04.

[0054] Fig. 6 shows an electric machine 1 according to a third embodiment. The same reference numerals are again used for the same components. In contrast to the embodiments described above, a sealing device 9 with sealing elements 10 is provided. These sealing elements 10 are annular and are arranged circumferentially around the channel end sections 15, in particular the extensions 14, of every second stator segment 4-7. This means that a section of a sealing element 10 is located between two stator segments 4-7, for example, between two extensions 14.

[0055] Fig. 7 shows a further section in which the sealing device 9 is shown in cutaway view. It can be seen that, for example, the extensions 14 have grooves in which the sections of the sealing elements 10 are partially received, for example, semicircular grooves. Advantageously, such a sealing element 10, for example as an O-ring, can be manufactured relatively easily and mounted on the stator segments 4-7.

[0056] Figure 8 shows that the extensions 14 have the corresponding grooves in the circumferential direction. For example, a sealing element 10 can be arranged around the extension 14 or the channel end section 15 of the stator segment 4-7 shown, resulting in the state shown in Figure 9. Subsequently, a stator segment 4-7 according to Figure 8 can be arranged circumferentially, on which no sealing element 10 is arranged. This is followed by another stator segment 4-7 on which a sealing element 10 is arranged, i.e., a stator segment 4-7 in the state shown in Figure 9. This process is continued until the stator body 3 is completed. Figure 9 shows, for example, the stator segment 4-7 from Figure 8 on which the sealing element 10 is arranged. In other words, the stator base body 3 is alternately composed of stator segments 4-7 according to Fig. 9 and stator segments 4-7 according to Fig. 8 in the circumferential direction.

[0057] Fig. 10 shows an electric machine 1 according to a fourth embodiment. In contrast to the embodiments described above, in Figs. 10-13 the channel 8 is not designed such that the conductor elements 11 are located in the channel 8. ZF Friedrichshafen AG File 304717 Friedrichshafen 2025-11-04

[0058] Instead of being located within the stator body, the channel 8 is designed separately as a conductor element receptacle 18. The embodiment according to Figs. 10-13 can therefore also be described as "near-slot" temperature control, whereas the previously described embodiments can be described as "in-slot" temperature control. In principle, the temperature control is analogous to the previously described embodiments, namely by supplying a temperature control medium into the channel 8, which flows axially through the stator body 3 via the channel 8.

[0059] In the embodiment shown in Figures 10-13, a sealing device 9 is also provided. This device again has sealing elements 10, for example, designed according to the third embodiment shown in Figures 6-9. The sealing elements 10 each engage a stator segment 4-7 in grooves that are open in the circumferential direction. Thus, the sealing device 19 also prevents the temperature control fluid from leaving the channel 8 in a radial direction. Advantageously, the extensions 14 of the stator segments 4-7 can be designed with electromagnetic optimization and do not need to have receptacles for the sealing elements 10.

[0060] As described, the stator 2 or the electric machine 1 can be part of a drivetrain. The electric machine 1 can thus be designed to generate or provide torque for driving the drivetrain. Such a stator 2 or electric machine 1, or such a drivetrain, can be part of a motor vehicle. Such a motor vehicle can therefore include the drivetrain, the electric machine 1, or the stator 2.

[0061] All the designs described with regard to the electric machine 1 and the stator 2 are fully transferable to the motor vehicle and the drive train.

[0062] All advantages, details, and features described in relation to the individual embodiments can be combined, interchanged, and transferred to one another as desired. ZF Friedrichshafen AG File 304717

[0063] Friedrichshafen 2025-11-04

[0064] Reference sign

[0065] 1 electric machine

[0066] 2 Stator

[0067] 3 Stator base bodies

[0068] 4-7 Stator segment

[0069] 8-channel

[0070] 9 Sealing device

[0071] 10 sealing element

[0072] 11 ladder element

[0073] 12, 13 Arrow

[0074] 14. Extension

[0075] 15 Channel end section

[0076] 16 Insulation device

[0077] 17 Opening

[0078] 18 conductor element recording

Claims

ZF Friedrichshafen AG File 304717 Friedrichshafen 2025-11-04 Patent claims 1. Stator (2) for an electric machine (1), comprising a stator base body (3) having at least two stator segments (4-7) arranged adjacent to each other in the circumferential direction, wherein a channel (8) is formed between the at least two stator segments (4-7) which is designed to guide temperature control medium, wherein a sealing device (9) is designed to seal the channel (8) radially inwards in the radial direction of the stator base body (3).

2. Stator (2) according to claim 1 , characterized in that at least one electrical conductor element (11), in particular at least one hairpin conductor element (11), can be received or accommodated in the channel (8) or that the channel (8) is arranged separately, in particular radially outside to a conductor element receptacle (18) accommodating at least one electrical conductor element (11).

3. Stator (2) according to claim 1 or 2, characterized in that a sealing element (10) is arranged in the channel (8), in particular at a radially inner channel end section (15).

4. Stator (2) according to claim 3, characterized in that the sealing element (10) can be prestressed or prestressed in the radial direction by at least one conductor element (11) and is designed to transmit the prestress force in the circumferential direction to the stator segments (4-7).

5. Stator (2) according to claim 3 or 4, characterized in that the sealing element (10) is bent in the radial direction in the direction of at least one conductor element (11) received in the channel (8), at least in an unloaded state.

6. Stator (2) according to one of the preceding claims, characterized in that the sealing device (9) is an electrical insulating device (16), ZF Friedrichshafen AG File 304717 Friedrichshafen 2025-11-04 in particular insulating paper, or is designed as an electrical insulating device (16).

7. Stator (2) according to one of the preceding claims, characterized in that the sealing device (9) comprises at least one sealing element (10), in particular a sealing ring, which surrounds a stator segment (4-7).

8. Stator (2) according to claim 7, characterized in that the at least one sealing element (10) is arranged in a circumferentially open groove in two circumferentially adjacent stator segments (4-7).

9. Stator (2) according to one of the preceding claims, characterized in that the at least two stator segments (4-7) have circumferentially directed, in particular electromagnetically optimized, extensions (14) at a radially inner end region.

10. Electrical machine (1) comprising at least one stator (2) according to one of the preceding claims.

11. Drive train comprising at least one electric machine (1) according to the preceding claim and / or at least one stator (2) according to any one of claims 1 to 9.

12. Motor vehicle comprising a drive train according to the preceding claim and / or at least one electric machine (1) according to claim 10 and / or at least one stator (2) according to any one of claims 1 to 9.

Images