Stator for a radial-flux double rotor machine, and radial-flux double rotor machine

Abstract

The present invention relates to a stator for a radial-flux double rotor machine, in particular for a wheel hub motor, comprising: a stator core having a through-flow cooling device for cooling the stator; a winding which is placed in the stator core, is of self-supporting design for torque support of the stator and projects beyond the stator core at a first axial end and at a second axial end opposite the first axial end; wherein torque support of the winding is provided at the first axial end, and the stator core contains stator grooves which have a course which corresponds to the course of the winding and each of which is provided for the arrangement of a single conductor bar of the winding, and the stator grooves have a groove base which lies in the stator core, has a widening with respect to the stator groove and forms a line for an axial coolant flow of the through-flow cooling device. The present invention further relates to a radial-flux rotor machine for a wheel hub drive having a stator of this type.

Description

[0001] Stator for a radial flux twin-rotor machine and radial flux twin-rotor machine

[0002] AREA OF INVENTION

[0003] The present invention relates to a stator for a radial flux twin-rotor machine, in particular for a wheel hub motor. The invention further relates to a radial flux twin-rotor machine, in particular for a wheel hub drive with such a stator.

[0004] TECHNICAL BACKGROUND

[0005] Electric machines with a stator and up to two rotationally fixed rotors, so-called radial flux rotor machines or radial flux double rotor machines (also referred to simply as double rotor, multiple rotor, or dual rotor), are suitable for increasing both the torque density and the efficiency of electric drives compared to conventional electric machines. Particularly in wheel hub drives, such radial flux rotor machines offer decisive advantages in terms of achievable efficiency and the required installation space in the vehicle.

[0006] An example of a radial flux twin-rotor machine is described in DE 10 2021 003 942 A1. These types of radial flux twin-rotor machines are characterized by high torque and power density. Radial flux twin-rotor machines utilize established and mass-producible manufacturing processes for the winding and laminated core, enabling the support of the torque generated in the stator core. Cooling the components of the electric drive machine is crucial for its efficiency. Stators of conventional electric machines are generally equipped with water or oil cooling, as these offer better thermal performance than air cooling. Cooling is achieved, for example, by cooling the stator shell, the rotor shaft, or the winding end. Coolant is supplied and discharged axially through the electric machine or the machine parts to be cooled.Cooling devices are also known in which a coolant flow is supplied to the stator via a first axial end and, after passing through channels provided in the stator, is discharged at the axially opposite end of the stator along with the heat transferred to the coolant. In twin-rotor machines, such a coolant flow cannot be implemented because the twin rotors cover the axial end of the stator, which is not used for torque support.

[0007] Up to now, cooling has therefore been achieved by one-sided conductive cooling via the conductors, the support element that receives the conductor ends and a cooling liquid channel associated with them.

[0008] SUMMARY OF THE INVENTION

[0009] Against this background, the present invention aims to provide a stator for a radial flux twin-rotor machine that offers improved cooling performance and has a cooling system integrated into the stator during manufacturing. According to the invention, this objective is achieved by a stator with the features of claim 1 and / or a radial flux twin-rotor machine with the features of claim 12.

[0010] Accordingly, the following is planned:

[0011] - A stator for a radial flux twin-rotor machine, in particular for a wheel hub motor, comprising a stator core with a flow-through cooling device for cooling the stator; a winding placed in the stator core, which is designed to be self-supporting for torque support of the stator and projects beyond the stator core at a first axial end and a second axial end arranged opposite the first axial end; wherein torque support of the winding is provided at the first axial end, and the stator core contains stator slots extending in accordance with a winding path for arranging a single conductor bar of the winding, wherein the stator slots have a groove base located in the stator core, which has a widening relative to the stator slot and forms a channel for an axial coolant flow of the flow-through cooling device.

[0012] - A radial flux twin-rotor machine, in particular for a wheel hub drive, with a mechanically fixed base and a stator according to the invention, wherein the stator is positively connected to the base or a support device supported on the base for torque support; a twin rotor with a first rotor arranged radially inside the stator core; and a second rotor arranged radially outside the stator core, wherein an introduction and a return of the coolant flow into the stator core is provided via the base and / or the support device.

[0013] - A wheel hub drive with a radial flux double rotor machine according to the invention.

[0014] The underlying insight of the present invention is that, in radial flux twin-rotor machines, improved cooling is necessary to achieve higher continuous torques and power outputs due to the higher continuous currents through the conductors. Improved cooling can be achieved by increasing the cooling surface area.

[0015] The underlying idea of ​​the present invention is to widen the base of the slots in the stator core of some or all of the slots in which the conductor bars of the windings are arranged, and to use the widened area of ​​the stator slot, i.e., the slot base widened relative to the stator slot, as a conduit for the coolant. By widening the base of some or all of the stator slots located in the stator yoke, the magnetically unused part of the stator can be used for cooling. This results in improved thermal performance and a reduction in installation space. Furthermore, additional cooling elements, such as a cooling device on the stator shell, can be completely or partially omitted, thereby reducing the complexity, installation space, and weight of the stator.Furthermore, the stator according to the invention allows an axial division of the flow direction of the coolant flow, wherein a first part of the lines in the stator is used for introducing the coolant from the torque-supported to the opposite, non-torque-supported axial end of the stator and, after redirection of the coolant flow there, a second part of the lines is used for the return flow to the torque-supported end.

[0016] Direct cooling of the conductor bars in the winding of the stator according to the invention allows for more uniform heat dissipation and reduces temperature gradients along the conductor bars, as well as the risk of critical temperature peaks occurring in individual conductor bar areas or sections and / or in the entire winding. This allows each conductor bar to bear a higher load, resulting in a higher current-carrying capacity. The electric machine can thus provide more power without reaching or exceeding thermal limits. Uniform heat dissipation across the conductor bar or winding improves the overall energy efficiency of the electric machine, as thermal losses are distributed and reduced overall.Direct cooling of the conductor bars increases the thermal stability of the winding, allowing for faster response to load changes without overheating of the winding or individual sections. Furthermore, the maximum permissible temperature of the stator potting compound is a limiting factor for the maximum possible current load. Advantageously, the reduced temperature gradient within the stator resulting from direct cooling of the conductor bars allows for higher current and continuous current loads, as the maximum permissible temperature in the potting compound is not reached, or only reached after a significant delay. A further advantage is the more efficient heat transfer achieved through direct, conductor-near cooling within the stator core.Due to the design according to the invention, heat transfer occurs directly through mass transfer, and the inertia of the cooling device is significantly reduced compared to conventional cooling systems. The flow-through cooling device in the stator according to the invention can thus react more quickly to changes in load conditions, especially during short-term high loads. Advantageously, even with an increase in the continuous current, more efficient heat dissipation from the stator core also occurs.

[0017] Advantageous designs and further developments result from the further sub-claims as well as from the description with reference to the figures in the drawings.

[0018] According to one embodiment, each of the stator slots has a widening and / or the widening extends radially and / or tangentially into the stator core. This allows for adaptation to the stator geometry, and the size or cross-section of the widening can be matched to the required thermal output of the flow-through cooling system. Furthermore, this achieves optimal utilization of the available space in the stator yoke and makes the magnetically unused portion of the stator available for cooling.

[0019] According to one embodiment, the stator core is divided into separate stator core sections, with the channels in the stator core sections being optionally designed for introducing the coolant flow from the first to the second axial end or for returning the coolant flow from the second to the first axial end. The coolant flow is thus supplied and discharged via the torque-supported axial end of the stator, and the flow-through cooling device is fully integrated into the stator or stator core.

[0020] According to one embodiment, the division is designed as a radial division of the stator core and has a radially outer stator core area and a radially inner stator core area, which contain the respective channels for the introduction or return of the coolant flow. This allows for the optimization of the coolant flow direction and the increase in the thermal performance of the flow-through cooling system. Depending on the design of the electric machine and the resulting cooling requirements, the coolant flow can be supplied via the radially outer stator area and discharged via the inner area, or vice versa. This also allows for heat dissipation from the rotors.

[0021] According to a further embodiment, the division is designed as a tangential division of the stator core. The stator core has a first and a second tangential, preferably semicircular, stator core section containing the respective lines for the inlet and outlet of the coolant flow, i.e., at least two stator halves. This simplifies the construction and connection of the stator's flow-through cooling device to a higher-level cooling system of the electric machine, since a position-defined connection of the inlet and outlet lines is possible. At the same time, it is also possible to improve cooling across the stator by changing the direction of flow.According to one embodiment, a diversion for the coolant flow is provided at the second axial end. This diversion is specifically located in a cover on a winding head arranged at the second axial end, and is fluidically connected to the respective lines of the first and second stator core regions. The available installation space at the winding head of the axial, non-torque-supporting end of the stator is used for the diversion. The cover is designed as a cap or hood that can be placed on the winding head. The diversion can be made, for example, of a particularly temperature-resistant plastic or of metal, such as aluminum or an aluminum alloy, and can include lines that are congruent with the existing lines and their positions.Manufacturing can be carried out, for example, using an injection molding or 3D printing process, enabling simple, cost-effective and low-rework production and easy assembly.

[0022] According to one embodiment, a support structure is provided, arranged axially offset from the stator core, which is designed for positive engagement with the winding at the first axial end. The respective lines open into a first region or a second region of the support structure that is substantially liquid-tight. A coolant flow is introduced from the first region and returned to the second region, and a radial or tangential separation of the first and second regions is provided. The support structure, which is designed for positive engagement with the winding at at least one axial end for torque support, can accordingly also be provided to accommodate the inlet and outlet lines of the flow-through cooling device.Since the support device is arranged axially offset from the stator core, it can also participate in heat dissipation.

[0023] According to one embodiment, the stator core comprises a stator lamination stack with stator slots that run along a winding path and each have a widened slot base. The stator laminations of the stator lamination stack, with recesses provided for forming the stator slots, are all identical, and / or the orientation of the stator slots and the conductors is adjustable by means of a twisted stacking of the stator laminations relative to each other. This significantly simplifies the formation of the stator slots with widened slot bases by appropriately arranging pre-fabricated, for example, stamped stator laminations. Sealing of the conductors is achieved by the baking varnish used to join the stator laminations.

[0024] According to one embodiment, the stator lamination stack comprises an inner sub-package with radially inner stator slots having a widened slot base and an outer sub-package with radially outer stator slots having a widened slot base, wherein the stator laminations of the inner sub-package and the stator laminations of the outer sub-package are designed with the same geometry and / or wherein the stator laminations of the inner sub-package and the stator laminations of the outer sub-package are stacked with opposite twisting to each other, or the stator laminations with recesses provided for forming stator slots having a widened slot base are designed differently, wherein the course of the stator slots and the conductors is adjustable by means of different distances of the recesses in the individual stator laminations.In this way, the opposing helix lines of the stator slots can be realized with minimal manufacturing effort on a widened slot base, enabling a very economical manufacturing method, since the same die can be used for all parallel or stacked stator laminations of the inner sub-package and for all parallel or stacked stator laminations of the outer sub-package. Accordingly, two adjacent stator laminations of the inner sub-package are slightly rotated relative to each other in a first direction by a predetermined angle around the central axis, and two adjacent stator laminations of the outer sub-package are slightly rotated relative to each other in a second, opposite direction by a predetermined angle around the central axis.In this way, the recesses of the stator laminations of the inner sub-package and the recesses of the stator laminations of the outer sub-package are arranged in opposite overlap to each other, corresponding to the opposite helical path. In the alternative embodiment, the stator laminations are shaped differently with respect to the first and second axial sections, with recesses provided for forming the stator grooves, including the widenings in the groove base. The helical path of the stator grooves is achieved by means of different spacings of the recesses in the individual stator laminations and thus in the respective axial sections. In this respect, an individually suitable stator lamination shape is produced for each position of a stator lamination within the stack, whereby the individual geometries can also be repeated within the stack.In this case, manufacturing can be achieved, for example, using a beam cutting process, particularly laser beam cutting, which is more flexible in terms of shape compared to a stamping process. Flexible stamping dies with variable geometries are also conceivable, or, for very high production volumes, several individual stamping dies for each of the different stator lamination shapes. It is also possible that the recesses for radially inner and radially outer stator slots, including the expansions in the first and second axial sections, are integrated into a single stator lamination, with the opposing helical orientation of the radially inner and outer stator slots being achieved by a continuous displacement of the inner and outer stator slots of the first and second axial sections relative to each other from stator lamination to stator lamination.Here too, a custom-fit stator lamination shape is produced for each position of a stator lamination within the stack, and the individual geometries can be repeated within the stack. Flexible cutting processes, such as laser beam cutting, are also used for manufacturing. The ability to produce the inner and outer recesses in one piece thus advantageously reduces the number of parts.

[0025] According to one embodiment, the stator core is provided with a substantially, but not completely, liquid-tight seal formed by a baked-on varnish and / or a coating connecting the lamination stack, in particular a coating that simultaneously provides insulation for the lamination stack or an encapsulation with a sealing material. This also ensures the tightness of the lines and allows the coolant to be introduced directly into them without the need for additional seals.

[0026] According to one embodiment, the coolant for the coolant flow is selected from the group consisting of or comprising: oil, water, a water-glycol mixture, a synthetic coolant, or mixtures thereof. The thermal performance of the flow-through cooling device can be adjusted by selecting the coolant. Preferably, the coolant is oil or an oil-based fluid.

[0027] According to one embodiment of the radial flow twin-rotor machine, the respective lines open into a first or a second outlet region of the base, which is substantially liquid-tight. The coolant flow is introduced from the first outlet region and returned to the second outlet region, with a radial or tangential separation between the first and second outlet regions. This simplifies the integration of the flow-through cooling device into the electric machine and improves the cooling performance.

[0028] According to one embodiment of the radial flux twin-rotor machine, the stator's flow-through cooling device is fluidically connected to a cooling device of the radial flux twin-rotor machine and / or the base has a heat sink designed to absorb heat dissipated from the stator, particularly from the winding, via the flow-through cooling device. This integration allows the cooling circuit of the higher-level unit to be used for more efficient cooling of the stator and thus of the electric drive motor, thereby avoiding redundancy. Equipping the base with a heat sink allows heat to be dissipated immediately after it is extracted from the stator.

[0029] According to one embodiment of the radial-flow twin-rotor machine, at least the second rotor, arranged radially outside the stator core, has at least one, and preferably several, leakage discharge openings for coolant escaping through the lamination boundaries of the stator lamination stack and / or at the end-winding support. This prevents coolant leakage from the flow-through cooling system from accumulating in the rotor and being introduced into the rotors and the rotor shaft, despite sealing measures in the stator lamination stack and at the end-winding support.

[0030] The above embodiments and further developments can be combined with one another as appropriate. Further possible embodiments, further developments, and implementations of the invention also include combinations of features of the invention described previously or subsequently with regard to the exemplary embodiments, even if not explicitly mentioned. In particular, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the present invention.

[0031] CONTENT OF THE DRAWING

[0032] The present invention is explained in more detail below with reference to the exemplary embodiments shown in the schematic figures of the drawings. Figure 1 shows a schematic longitudinal sectional view of a section of the radial flux twin-rotor machine according to one embodiment of the invention;

[0033] Fig. 2 shows a schematic cross-sectional view of a section of a stator according to an embodiment of the invention;

[0034] Fig. 3 shows a schematic cross-sectional view of the stator in a radial flux twin-rotor machine according to an embodiment of the invention;

[0035] Fig. 4 shows a perspective sectional view of the stator in a radial flux twin-rotor machine according to an embodiment of the invention;

[0036] Fig. 5a, b Schematic representations of the coolant flow in a stator according to embodiments of the invention; and

[0037] Fig. 6a-h further schematic representations of coolant flows in a stator according to embodiments of the invention.

[0038] The accompanying figures of the drawings are intended to provide a further understanding of the embodiments of the invention. They illustrate embodiments and, in conjunction with the description, serve to explain the principles and concepts of the invention. Other embodiments and many of the aforementioned advantages become apparent with reference to the drawings. The elements of the drawings are not necessarily shown to scale. In the figures of the drawings, identical, functionally equivalent, and similarly acting elements, features, and components are—unless otherwise indicated—each designated with the same reference numerals.

[0039] DESCRIPTION OF EXAMPLES OF EXECUTION

[0040] Fig. 1 shows a highly simplified, schematic longitudinal section of the radial flux twin-rotor machine according to one embodiment of the invention. The stator 1 has a stator core 3, a winding 4, and a schematically depicted support structure 14, which is connected to the electric machine via a base 17. The winding 4 is self-supporting for torque support of the stator 1 and projects beyond the stator core 3 at a first axial end 5 and a second axial end 6. At its first axial end 5, the winding 4 is supported on the base 17 via the support structure 14. The support structure 5 is arranged axially offset from the stator core 3 and positively connected to the winding 4 at the first axial end 5 for torque support. The support structure 14 is in turn attached to the base 17, so that the torque can be supported on the base 17 via the support structure 14.The stator core 3, the winding 4 and the support device 14 are arranged rotationally symmetrically around a central axis M.

[0041] The double rotor 30, also shown schematically in Fig. 1, has a first rotor 18 and a second rotor 19. The first rotor 18 is arranged radially outside the stator core 3, and the second rotor 19 is arranged radially inside the stator core 3. As shown in more detail in the following figures, the stator core 3 contains stator slots 7, which follow the winding path, for arranging a single conductor bar 8 of the winding. Each stator slot 7 has a slot base 9 located in the stator core 3, which has a widening relative to the stator slot 7. Each widened slot base 9 forms an axially extending channel 22 in the stator core 3, following the winding path, as part of a flow-through cooling device 2 provided for cooling the stator core 3.In the numerous lines 22 formed by this arrangement, a coolant flow KS is guided axially through the stator core 3 in order to dissipate heat generated during operation of the electric machine from the stator core 3. The lines 22 are provided either for an introduction E of the coolant flow KS from the first to the second axial end 5, 6 or for a return R of the coolant flow KS from the second to the first axial end 6, 5.

[0042] At the second axial end 6, the connected conductor bars 8 form a winding head 12, on which a diversion 23 for the coolant flow KS is provided. The available installation space at the winding head 12 of the second axial, non-torque-supporting end 5 of the stator 1 is used for the diversion 23. The diversion 23 comprises a cover 13 mounted on the winding head 12. The cover 13 is designed to form a fluidic connection between the lines 22 provided in the stator core 3 for the introduction E of the coolant flow KS and the lines 22 provided in the stator core 3 for the return R of the coolant flow KS, and has a corresponding internal structure or line arrangement. The cover 13 is positively, force-, or materially connected to the stator core 3, essentially in a liquid-tight manner.A substantially liquid-tight seal 16 between the stator core 3 and the conductors 22 is achieved by a sealing material applied to the stator core 3. If the stator core 3 is formed from a stator lamination stack 26, the seal 16 can be formed by the bonding varnish connecting the lamination stack. Alternatively or additionally, a coating, in particular a coating that simultaneously provides insulation for the stator lamination stack 26, or encapsulation with a sealing material can be provided.

[0043] Between the support structure 14 and the base 17 connected to it are the outlet areas 20a, b of the respective lines 22 for the introduction E and return R of the coolant flow KS, respectively. The respective lines 22 open into a first area 15a or a second area 15a, which is essentially liquid-tight, located between the support structure 14 and the base 17. The flow-through cooling device 2 is designed such that, during operation, an introduction E of the coolant flow KS from the first area 15a into the lines 22 running axially in the stator core 3 occurs, and a return R of the coolant flow to the second area 15b occurs via separate lines 22. The support device 14, which is designed for positive engagement with the winding 4 at the first axial end 5 for torque support, can accordingly be simultaneously provided to support the lines 22 for the inlet E as well as the return line R, i.e.The inlet and outlet lines of the flow-through cooling device 2 are to be accommodated. Heat dissipated from the stator core 3 can be dissipated via the support device 14 or the base 17 connected to it. The flow-through cooling device 2 of the stator 1 can also be connected to a higher-level cooling device of the electric machine (not shown in Fig. 1) via the support device 14 or the base 17. The base 17 can additionally have a heat sink 24 for heat dissipation, which serves to absorb heat dissipated from the stator 1, in particular from the winding 4, via the flow-through cooling device 2.

[0044] Since a complete seal of the stator core 3 against coolant leakage is not guaranteed, and coolant can therefore escape from the stator 1, the sheet boundaries of the stator lamination stack 26, the winding head 12, and / or the cover 13, an accumulation of coolant in the twin rotor 30 is prevented by the fact that at least the first rotor 18, which is arranged radially outside the stator core 3, has one or more leakage discharge openings 21 for escaping coolant. The accumulated coolant is expelled through the leakage discharge openings 21 by centrifugal forces generated when the twin rotor 30 rotates.

[0045] Fig. 2 shows a schematic cross-sectional view of a section of a stator 1 according to an embodiment of the invention. The stator core 3 is arranged between a radially outer first rotor 18 and a radially inner second rotor 19. The first and second rotors 18, 19 are provided with permanent magnets 25 in the usual manner.

[0046] The winding 4 is located in the stator core 3. In a radial flux twin-rotor machine, it is designed to be self-supporting for torque support of the stator 1 and projects beyond the stator core 3 at a first axial end 5 and a second axial end 6 located opposite the first axial end 5 (see Figs. 1 and 4). Stator slots 7, corresponding to the winding path, are provided in the stator core 3 for arranging individual conductor bars 8 of the winding 4. In the exemplary embodiment, each stator slot 7 has a slot base 9 located radially inside the stator core 3, with opposing stator slots 7 having a mirror-symmetrical arrangement of the slot base 9 relative to their position in the stator 1.To form a channel 22 for the coolant flow KS of a flow-through cooling device 2 provided in the stator core 3, each groove base 9 in the exemplary embodiment has a radially extending widening into the stator yoke 28 opposite the stator groove 7. A coolant flow KS, flowing through the stator core 3 from the first to the second axial end 5, 6 of the winding 4, can be introduced into the stator core 3 via the channels 22 thus formed and, after appropriate redirection at the winding head 12 of the second axial end 6, is returned to the first axial end 5 in order to absorb heat occurring in the stator 1 or the windings 4 and dissipate it from the stator core 3. In the exemplary embodiment of Fig. 2, the stator core 3 has a radial division into a radially inner stator core region 11a and a radially outer stator core region 11b.Each groove base 9 of the radially outer stator grooves 7 faces the corresponding groove base 9 of the radially inner stator grooves 7. The widened groove base 9 of each stator groove 7 is located in the magnetically unused part of the stator yoke 28. In the exemplary embodiment, the channels 22 formed in the radially outer stator grooves 7 are provided for an introduction E of the coolant flow KS, while a return flow R occurs via the channels 22 in the radially inner stator grooves 7. Of course, a reverse configuration is also possible, i.e., with an introduction E via the radially inner channels 22 and a return flow R via the radially outer channels 22.

[0047] The stator core 3 is formed from a stator lamination stack 26, which has a seal 16 to prevent coolant from escaping across the lamination boundaries of the stator lamination stack 26. The stator laminations of the stator lamination stack 26 have recesses 27 of identical shape to form the stator slots 7 and the widenings of the slot base 9 of each stator slot 7. The orientation of the stator slots 7 is adjustable by means of a twisted stacking of the stator laminations relative to each other. The radial division of the stator core 3 into a radially inner stator core region 11a and a radially outer stator core region 11b can also be formed by constructing the stator lamination stack 26 with an inner sub-stack 31 having radially inner stator slots 7 with widened slot base 9 and an outer sub-stack 32 with radially outer stator slots 7 with widened slot base 9.The stator laminations of the inner subpackage 31 and the stator laminations of the outer subpackage 32 are designed with the same geometry and provided with recesses in order to form the stator slots 7 in a mirror-symmetrical arrangement on a widened slot base 9 when the stator laminations are stacked.

[0048] Fig. 3 shows a schematic cross-sectional view of the stator 1 in a radial flux twin-rotor machine according to an embodiment of the invention. The stator 1 has the elements described in connection with Fig. 2, and the stator core 3 is again arranged between a radially outer first rotor 18 and a radially inner second rotor 19 and is provided with a seal 16 against the rotors 18 and 19. To avoid repetition, a further description of these elements is omitted with reference to Fig. 2. In contrast to the embodiment shown in Fig. 2, the embodiment shown in Fig. 3 provides a tangential division 10 of the stator core 3 into two stator halves with a first stator core region 11a and a second stator core region 11b, each of which is semicircular. The stator core regions 11a and 11b are separated from each other in a liquid-tight manner.The lines 22 formed by the widened groove base 9 of the respective stator grooves 7 are part of the flow-through cooling device 2 in the stator core 3. In contrast to the embodiment according to Fig. 2, in the embodiment shown in Fig. 3, the introduction E of the coolant flow KS takes place via the lines 22 provided in the first stator half, i.e. in the first stator core area 11a, while the return R takes place via the lines 22 provided in the second stator half, i.e. in the second stator core area 11b, or vice versa.

[0049] Fig. 4 shows a perspective sectional view of the stator 1 of a radial flux twin-rotor machine according to an embodiment of the invention. The stator 1 comprises a stator core 3, a winding 4, and a support structure 14, which is connected to the electrical machine via a base 17. The winding 4 extends beyond the stator core 3 at both axial ends 5, 6, and at its first axial end 5 it is positively connected to the support structure 14, which is arranged axially offset from the stator core 3, for torque support. The embodiment shown in Fig. 4 corresponds in essential parts to the embodiment shown in Fig. 1 and described there in detail, except for the twin rotor 30. Therefore, identical parts are not described again.Figure 4 shows the path of the coolant flow KS, which is guided axially through the channels 22 formed in the stator core 3 by widening the slot base 9 of each stator slot 7, in order to dissipate the heat generated during operation. The stator core 3 can be divided radially or tangentially into stator core regions 11a, b. The coolant flow KS is introduced E from the first axial end 5 of the windings via channels 22 in the first stator core region 11a to the second axial end 6. The introduction E is indicated in Figure 4 by the arrows shown in the upper section, pointing towards the second axial end 6.

[0050] In the area of ​​the winding head 12 at the second axial end 6, the coolant flow KS is diverted and returned to the first axial end 5 via lines 22 in the second stator core area 11b. The return line R is indicated in Fig. 4 by the arrows shown in the lower section, pointing towards the first axial end 5. The central axis M shown in Fig. 4 represents the separation of the flow direction.

[0051] Figures 5a and 5b schematically illustrate possible flow directions of the coolant flow KS in the stator core 3. In Figure 5a, the introduction E and the return R occur via the lines 22 of a pair of lines in each of the radially opposite stator slots 7 in the stator core 3, which are widened at the bottom of the slot 9. The introduction E and the return R, in opposite axial directions, thus take place in the same stator core segment 29. In Figure 5b, the stator core 3, in contrast, has a radial division 10 into a radially inner stator core region 11a and a radially outer stator core region 11b. The introduction E of the coolant flow KS occurs simultaneously via all lines 22 in the radially inner stator core region 11a, while the return R occurs simultaneously via all lines 22 in the radially outer stator core region 11b, in opposite axial directions.

[0052] To divert the coolant flow KS, the cover 13 on the winding head 12 of the second axial end 6 has in both cases a configuration that establishes a fluidic connection of the lines 22 for the introduction E with the corresponding lines for the return line R of the coolant flow KS and thus forms a cooling circuit with inlet and outlet via the first axial end 5.

[0053] Figures 6a to 6h illustrate possible coolant flow paths in the stator core 3. These illustrations are highly schematic and limited to the elements essential for the axial passage of the coolant flow KS through the stator core 3. As can be seen, for example, in Figure 3, the stator core 3 can have significantly more stator slots 7 than shown schematically and in a highly simplified manner here. Figures 6a to 6h also only show the stator core 3, which has a radial division 10 into a radially inner and a radially outer stator core region 11a, b. A stator 1 having the illustrated stator cores 3 can be used in the embodiments shown in Figures 1 to 5a, b. In both the radially inner and radially outer stator core regions 11a, b, lines 22 run, which are formed by widening the groove base 9 of the respective stator grooves 7 and are shown in detail in connection with Fig. 2 , Fig.Figure 3 and Figures 5a and 5b are shown and described. The number of lines 22 for the inlet E preferably corresponds to the number of lines 22 for the return line R, assuming the same line cross-section, in order to ensure a uniform coolant flow KS. However, embodiments with different line cross-sections for the inlet and return lines E and R are also possible and encompassed by the invention. The line cross-section is defined by the radial or tangential widening of the groove base 9 and its corresponding extension in the stator yoke 28.

[0054] In Figures 6a to 6h, the lines 22 that have the same flow direction of the coolant flow KS are marked identically. Thus, the lines 22 marked with a cross K in the exemplary embodiments are intended for the introduction E of the coolant flow KS from a first axial end 5 to the second axial end 6, while after the coolant flow KS is redirected in the region of the winding head 12 at the second axial end 6, the unmarked lines are intended for the return R of the coolant flow KS from the second axial end 6 to the first axial end 5. Reversed flow directions are, of course, also possible. In all embodiments, the coolant flow KS enters and exits via the first axial end 5, i.e., the axial end where the torque support of the winding 3 is also located.

[0055] Fig. 6a shows an embodiment with an intermittent arrangement of the respective lines 22 running axially in the stator core 3. Here, the coolant flow KS is introduced via lines 22 that are offset in the radial direction RR and in the circumferential direction UR, and is returned via the lines 22 located between them. In the embodiment of Fig. 6b, the lines 22 for the introduction E and the return R are each grouped in sets of four, which are arranged alternately in the circumferential direction UR. Lines 22 for the introduction E and the return R are arranged opposite each other in the radially inner stator core region 11a and in the radially outer stator core region 11b, respectively. The invention is, of course, not limited to the embodiment with sets of four shown here; it can also be implemented, for example, in the embodiment of Fig.6e also shows groups of two or groups with more than four respective lines 22 .

[0056] In the embodiment according to Fig. 6c, the stator core 3 has at least an imaginary division into two halves 33a, b, indicated by the tangential dividing line TL. While in one of the halves 33a the lines 22 for the inlet E run in the radially outer stator core region 11b and the lines 22 for the return R run in the radially inner stator core region 11a, the flow direction in the second half 33b is oriented in the opposite direction, i.e. the lines 22 for the return R lie in the radially outer stator core region 11b while the lines 22 for the inlet E run in the radially inner stator core region 11a.

[0057] Another embodiment is shown in Fig. 6d. Here, in the radially inner and radially outer stator core regions 11a, b, three lines 22 for the axial input E and three lines 22 for the axial return R are provided alternately, wherein the lines 22 are arranged in circumferential direction UR such that the three inner lines 22 for the input E are opposite three outer lines 22 for the return R and vice versa.

[0058] In the embodiment shown in Fig. 6f, the lines 22 for the introduction E of the coolant flow KS run in the radially inner stator core region 11a, while the lines 22 for the return flow R run axially in the radially outer stator core region 11b. The embodiment shown in Fig. 6g shows the reverse arrangement, i.e., the lines 22 for the introduction E of the coolant flow KS run axially in the radially outer stator core region 11b, while the lines 22 for the return flow R run in the radially inner stator core region 11a. The embodiment shown in Fig. 6g shows an irregular distribution of the lines 22 in the inner and outer stator core regions 11a, b.

[0059] The arrangement of the lines 22 and the flow patterns of the coolant flow KS adjustable therewith in the flow-through cooling device 2 in the stator 1 according to the invention are not limited to the embodiments shown in Figs. 6a to 6h but can be adapted and modified in various ways depending on the required thermal power and the geometry of the stator 1 and the electrical machine equipped therewith.

[0060] Although the present invention has been fully described above with reference to preferred embodiments, it is not limited thereto, but can be applied in many different ways and

[0061] Moderately modifiable. Reference symbol list.

[0062] 1 Stator

[0063] 2. Flow cooling system

[0064] 3 Stator core

[0065] 4 windings

[0066] 5 first axial end

[0067] 6 second axial end

[0068] 7 Stator slot

[0069] 8 ladder rod

[0070] 9 Groove

[0071] 10 division

[0072] Ila, b Stator core area

[0073] 12 winding head

[0074] 13 Cover

[0075] 14 Supporting institution

[0076] 15a, b area

[0077] 16 Sealing

[0078] 17 Base

[0079] 18 first rotor

[0080] 19 second rotor

[0081] 20a, b Mouth area

[0082] 21 Leakage drain opening

[0083] 22 Management

[0084] 23 Detour

[0085] 24 heat sinks

[0086] 25 permanent magnets

[0087] 26 Stator lamination stack

[0088] 27 Exclusion

[0089] 28 Stator yoke

[0090] 29 State Core segment

[0091] 30 twin rotor

[0092] 31 inner subpackage 32 outer subpackage

[0093] 33a, b half

[0094] E Introduction K Cross

[0095] KS coolant flow

[0096] M Central axis

[0097] R Return line

[0098] RR radial direction UR circumferential direction

Claims

PATENT CLAIMS 1. Stator (1) for a radial flux twin-rotor machine, in particular for a wheel hub motor, comprising: a stator core (3) having a flow-through cooling device (2) for cooling the stator (1); a winding (4) placed in the stator core (3), which is designed to be self-supporting for torque support of the stator (1) and projects beyond the stator core (3) at a first axial end (5) and a second axial end (6) arranged opposite the first axial end (5);wherein a torque support of the winding (4) is provided at the first axial end (5), and the stator core (3) contains stator slots (7) extending in accordance with a winding path for arranging a single conductor bar (8) of the winding (4), wherein the stator slots (7) have a slot base (9) located in the stator core (3) which has a widening relative to the stator slot (7) and which forms a channel (22) for an axial coolant flow (KS) of the flow-through cooling device (2).

2. Stator (1) according to claim 1, characterized in that each of the stator slots (7) has the widening and / or the widening extends in the radial and / or tangential direction of the stator slot (7) into the stator core (3).

3. Stator (1) according to claim 1 or 2 characterized in that the stator core (3) has a division (10) into separate stator core regions (11a, b), wherein the lines (22) in the stator core regions (11a, b) are optionally provided for an introduction (E) of the coolant flow (KS) into the lines (22) from the first to the second axial end (5, 6) or for a return flow (R) of the coolant flow (KS) from the second to the first axial end (5, 6).

4. Stator (1) according to claim 3, characterized in that the division (10) is designed as a radial division (10) of the stator core (3) and has a radially outer stator core area (11a) and a radially inner stator core area (11b) in the stator core (3), which contain the respective lines (22) for the introduction (E) or the return line (R) of the coolant flow (KS).

5. Stator (1) according to claim 3, characterized in that the division (10) is designed as a tangential division (10) of the stator core (3) and has a first and a second tangential stator core area (11a, b) containing the respective lines (22) for the introduction (E) and return (R) of the coolant flow (KS).

6. Stator (1) according to one of the preceding claims, characterized in that a diversion (23) for the coolant flow is provided at the second axial end (6), wherein the diversion (23) in particular is provided in a cover (13) arranged on a winding head (12) arranged at the second axial end (6) and the diversion (23) is fluidically connected to the respective lines (22) of the first stator core area (11a) and the second stator core area (11b).

7. Stator (1) according to one of the preceding claims, characterized in that a support device (14) is provided which is arranged axially offset to the stator core (3) and which is designed to engage positively with the winding (4) at the first axial end (5), wherein the respective lines (22) open into a first region (15a) or a second region (15b) of the support device (14) which is substantially liquid-tight separated from it, and wherein an introduction (E) of the coolant flow (KS) from the first region (15a) and a return line (R) of the coolant flow (KS) into the second region (15b) is provided, wherein a radial or tangential separation of the first and second regions (15a, b) is provided.

8. Stator (1) according to one of the preceding claims, characterized in that the stator core (3) comprises a stator lamination stack (26) with stator slots (7) extending in accordance with a winding path and each having a widened slot base (9), wherein the stator laminations of the stator lamination stack (26) with recesses (27) provided for forming the stator slots (7) are each identical and / or wherein the orientation of the stator slots (7) and the conductors (22) is adjustable by means of a stacking of the stator laminations rotated relative to each other.

9. Stator (1) according to claim 8, characterized in that the stator lamination stack (26) comprises an inner sub-stack (31) with radially inner stator slots (7) having widened slot bases (9) and an outer sub-stack (32) with radially outer stator slots (7) having widened slot bases (9), wherein the stator laminations of the inner sub-stack (31) and the stator laminations of the outer sub-stack (32) are designed with the same geometry and / or wherein the stator laminations of the inner sub-stack (31) and the stator laminations of the outer sub-stack (32) are stacked in a twisted orientation relative to each other, or the stator laminations with recesses (27) provided for forming stator slots (7) having widened slot bases (9) are each designed differently.wherein the course of the stator slots (7) and conductors (22) can be adjusted by means of different spacings of the recesses (27) in the individual stator laminations.

10. Stator (1) according to one of the preceding claims, characterized in that the stator core (3) has a substantially but not completely liquid-tight seal (16) connecting the stator lamination stack (26) with a baking varnish and / or a coating, in particular a coating providing insulation of the stator lamination stack (26) or an encapsulation with a sealing material.

11. Stator (1) according to one of the preceding claims, characterized in that a coolant of the coolant stream (KS) is selected from the group consisting of or comprising: oil, water, Water-glycol mixture, synthetic coolant or mixtures thereof.

12. Radial flux twin-rotor machine, in particular for a wheel hub drive, comprising: a mechanically fixed base (17); a stator (1) according to one of the preceding claims, wherein the stator (1) is positively connected to the base (17) or a support device (14) supported on the base (17) for torque support; a twin rotor (30) with a first rotor (18) arranged radially inside the stator core (3); and a second rotor (19) arranged radially outside the stator core (3), wherein an introduction (E) and a return (R) of a coolant flow (KS) into the stator core (3) via the base (17) and / or the support device (14) is provided.

13. Radial flux twin-rotor machine according to claim 12, characterized in that the respective lines (22) open into a first or a second outlet area (20a, b) of the base (17) which is substantially liquid-tight, and an inlet (E) of the coolant flow (KS) from the first outlet area (20a) and a return line (R) of the coolant flow into the second outlet area (20b) are provided. is, wherein a radial or tangential separation of the first from the second mouth area (20a, b) is provided.

14. Radial flux twin-rotor machine according to one of claims 12 or 13, characterized in that the flow-through cooling device (2) of the stator (1) is fluidically connected to a cooling device of the radial flux twin-rotor machine and / or the base (17) has a cooling body (24) which is designed to absorb heat dissipated from the stator (1) via the flow-through cooling device (2), in particular from the winding (4).

15. Radial flux twin-rotor machine according to one of claims 12 to 14, characterized in that at least the first rotor (18) arranged radially outside the stator core (3) has at least one leakage discharge opening (21), preferably several leakage discharge openings (21), for coolant escaping through the lamination boundaries of the stator lamination stack (26) and / or at the winding head (12).

16. Wheel hub drive with a radial flux double rotor machine according to one of claims 12 to 15.

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