Stator for an electric machine, in particular an electric drive, and electric motor with a stator

Abstract

The stator for an electric machine, particularly an electric drive, has at least one stator core mounted on a stator bushing. This bushing is provided with at least one bearing seat for a rotary bearing for a rotor shaft and has at least one winding head projecting axially beyond the stator core. To achieve effective cooling, the stator and the electric motor are designed such that at least one cooling airflow channel is provided in the area between the winding head and the stator core. This channel extends over at least a portion of the radial and / or circumferential length of the winding head. In this way, the winding head is cooled in a targeted manner, ensuring optimal cooling of the stator components. The cooling air can be directed past the winding head in the flow channel, thus providing optimal cooling.

Description

[0001] The invention relates to a stator for an electric machine, in particular an electric drive, according to the preamble of claim 1, and to an electric motor according to claim 16.

[0002] In conventional electric motors, especially external rotor motors and motors with a high IP protection rating, the winding area, including the winding heads and the rotor-side bearing, is well encapsulated to protect it from environmental influences. This also provides thermal insulation to the winding and winding heads. Heat dissipation from the stator occurs primarily through the stator bushing. Cooling wheels or fins integrated into the rotor are sometimes used to create air turbulence in the area of ​​the rotor-side winding head. This can help prevent hotspots, but targeted cooling of the rotor-side winding head or the bearing seat is either not possible or only insufficient in this way.

[0003] The invention is based on the objective of designing the generic stator and the electric motor in such a way as to achieve good cooling effect.

[0004] This problem is solved according to the invention in the generic stator with the characterizing features of claim 1 and in the electric motor according to the invention with the features of claim 16.

[0005] The stator according to the invention is designed such that the components to be cooled are surrounded or permeated by the cooling air. For this purpose, at least one flow channel is provided, which is arranged in the area between the winding head and the stator core. The flow channel extends over at least a portion of the radial and / or circumferential length of the winding head. In this way, the winding head is cooled in a targeted manner, so that optimal cooling of the stator components is reliably achieved. In the flow channel, the cooling air can be guided past the winding head and thus cool it optimally.

[0006] Advantageously, the flow channel extends radially over at least part of its length. This allows the cooling air to optimally cool the winding head.

[0007] In an advantageous embodiment, the flow channel is positioned between the winding head and an electrical insulation covering the stator core. The flowing air is thus guided directly along the underside of the winding head. The electrical insulation allows for a structurally simple integration of the flow channel into the stator.

[0008] If the electrical insulation is thin-walled, the flowing air can also cool the stator core.

[0009] Optimal cooling can be achieved if the flow channel has at least one axial intake section that is flow-connected to a radial section of the flow channel. The axial intake section can be designed so that the cooling air flows past the winding head not only radially but also axially, thus ensuring optimal cooling.

[0010] Further optimal cooling can be achieved if the flow channel has at least one axial outlet section that is flow-connected to the radial section of the flow channel. The axial outlet section, like the axial intake section, can be designed so that the cooling air also flows axially past the winding head, allowing the winding head to be cooled from at least three sides in conjunction with the radial section of the flow channel.

[0011] The outlet section is advantageously connected to a downflow section. The cooling air is discharged back into the stator or rotor via this downflow section after passing through the flow channel. The rotor can also serve as a cooling surface / heat sink.

[0012] The outflow section is advantageously located at an axial distance from the radial section of the flow channel.

[0013] The outflow section is preferably delimited by a fan wheel and a guide wall. The fan wheel draws in cooling air in such a way that it flows through the flow channel and optimally cools the components to be cooled. The fan wheel is part of a rotor that is rotatably mounted in the stator in a known manner. The fan wheel allows for adjustment of the optimal cooling airflow.

[0014] In an advantageous embodiment, the outflow section extends radially, so that the cooling air can flow in a radial direction.

[0015] Optimal cooling is achieved when the outflow section is designed so that the cooling air exiting it flows over at least part of the winding head. In this way, the winding head is cooled by the cooling air on both its top and bottom surfaces.

[0016] If the flow channel is advantageously open towards the bearing seat, the cooling air exiting the flow channel strikes the bearing seat and cools it. In this way, the cooling air can cool both the winding head and the bearing seat.

[0017] Thus, both components can be cooled to the required extent by a single cooling airflow.

[0018] Further optimal cooling of the bearing seat is possible if the axial outlet section of the flow channel runs adjacent to the bearing seat. Therefore, when the cooling air flows axially in the outlet section, it can optimally cool the bearing seat across its entire axial width.

[0019] Particularly effective cooling of the bearing seat is possible when the axial outlet section of the flow channel is limited on one side by the bearing seat. This not only results in a simple design but also in very effective cooling of the bearing seat.

[0020] The cooling effect can be advantageously improved if a flow channel and / or ribs are provided to increase the surface area in the area of ​​the bearing seat.

[0021] It is particularly advantageous if the flow channel has a macro- and / or microstructure.

[0022] The electric motor according to the invention is characterized by the fact that it is equipped with a stator according to the invention.

[0023] An advantage of this type of electric motor is an external rotor motor, in which a rotor casing surrounds the stator.

[0024] The subject matter of the application is not only defined by the subject matter of the individual patent claims, but also by all information and features disclosed in the drawings and the description. These are claimed as essential to the invention, even if they are not explicitly stated in the claims, insofar as they are novel, individually or in combination, compared to the prior art.

[0025] Further features of the invention will become apparent from the further claims, the description and the drawings.

[0026] The invention is explained in more detail with reference to two exemplary embodiments illustrated in the drawings. These show Fig. 1 in axial section an electric motor according to the invention with a stator according to the invention, Fig. 2 in enlarged and perspective view a part of the electric motor according to Fig. 1 on average, Fig. 3 a part of the electric motor according to Fig. 2 on average, Fig. 4 An axial view of an insulating disk of the stator or electric motor according to the invention with teeth arranged around the circumference without winding, Fig. 5 the insulating disc according to Fig. 4 in perspective view, Fig. 5a the insulating disc according to Fig. 4 in perspective view and in bottom view, Fig. 6 the stator package according to the invention with the electronics-side end in perspective view. Fig. 7 and Fig. 8 another insulating disk of the stator or electric motor according to the invention in perspective view from above and from below, Fig. 9 a rotor-side part of the stator according to the invention with two overlapping insulating disks, Fig. 10 in enlarged view and in axial section a part of a second embodiment of the stator according to the invention, Fig. 11 in perspective and enlarged view the underside of a tooth of the insulating disk of the stator according to Fig. 10.

[0027] Fig. Figure 1 shows an electric motor in the form of an external rotor motor with a stator 1 and a rotor 2. The stator 1 has a central stator socket 3, which transitions at one end into a stator flange 4. Advantageously, the stator flange 4 is formed integrally with the stator socket 3.

[0028] In a preferred embodiment, the stator flange 4 can form the base of an electronics housing (not shown) containing the electrical / electronic components necessary for the operation of the electric motor.

[0029] A rotor shaft 5 is located in the stator bushing 3 and is rotatably mounted in the stator bushing near both ends. Ball bearings 6 and 7 are provided as examples for this rotary mounting. Other rotary bearings, such as plain bearings, can also be used.

[0030] The stator bushing 3 is provided with a bearing seat 8, 9 in the area of ​​the ball bearings 6, 7. The rotor shaft 5 is seated at one end in a rotor bushing 10, which is embedded in the area of ​​a base 11 of the rotor. One end of the rotor shaft 5 is fixedly mounted in the rotor bushing 10, for example by press-fitting.

[0031] The base 11 of the rotor 2 transitions into a shell 12, with which it is advantageously formed integrally. The shell 12 is advantageously cylindrical and is provided on its outer surface with a circumferential radial flange 13, on which mounting points 14 are provided distributed around the circumference, via which the rotor 2 can be connected to a cooling wheel (not shown). Advantageously, the mounting points 14 are formed by material thickenings of the shell 12. The mounting points 14 are thick enough to ensure a minimum screw-in length for wheel attachment.

[0032] In another embodiment (not shown), cooling fins can be provided at this location. They can extend radially or at an angle to the radial direction. The cooling fins can be straight, wavy, or curved along their radial length. Advantageously, the radial flange 13 and the cooling fins are integrally connected to each other and to the rotor casing 12.

[0033] A return element 16 is attached to the inner side 15 of the casing 12 in a known manner. The return element 16 extends over the axial height of the casing 12 and serves to attach permanent magnets 17, which are arranged one behind the other in the circumferential direction of the return element 16.

[0034] In the exemplary embodiment, the magnets 17 are arranged in two axially adjacent magnet rows 17a, 17b, the magnets of which are advantageously located one behind the other with a small distance between them in the magnet rows 17a, 17b.

[0035] Instead of the individual magnets 17, a magnetic ring can also be provided which extends over the circumference of the return part 16.

[0036] The magnets 17 are attached in a known manner to the inside 18 of the return part 16.

[0037] The magnets 17 of the rotor 2 surround a stator core 20, which is mounted on the stator bushing 3, forming an annular gap 19. The stator core 20 consists of overlapping laminations 21, which are firmly connected to one another, for example by a positive-locking connection, an adhesive bond, a welded connection, or the like.

[0038] The stator core 20 is surrounded by a winding 22 in a known manner. Its winding heads 23, 24 project axially beyond the stator core 20.

[0039] In smaller electric motors, the stator core 20 consists of one-piece ring-shaped laminations that are stacked on top of each other in a known manner. If the electric motors have larger diameters, then the stator core 20 is formed from individual teeth that are stacked on top of each other in a known manner in the circumferential direction to form the stator core.

[0040] The stator package 20 has a central circular through-hole 51 ( Fig. 6), which the stator bushing 3 ( Fig. 1) records.

[0041] The stator package 20 has a cylindrical inner ring 52, from which arms 53 (teeth) extend radially outwards ( Fig. 6).

[0042] They are arranged evenly distributed around the circumference of the stator core 20 and each is provided at its free, radially outer end with a circumferentially extending web 54. The webs 54 and the arms 53 extend over the height of the stator core 20. Advantageously, the webs 54 project the same distance circumferentially beyond both sides of the arms 53.

[0043] The arms 53 and webs 54 are spaced 1 apart in the circumferential direction of the stator.

[0044] The arms 53 and the bridges 54 each form teeth 1 to 12 of the stator 1, which are wrapped with winding wire.

[0045] Adjacent arms 53 define slots 55 through which the winding of the stator 1 runs.

[0046] Insulating washers 25 and 26 are placed on both end faces of the stator pack 20 ( Fig. 6) The insulating discs electrically insulate the stator core 20 from the winding. The insulating discs 25, 26 are designed in a known manner to cover the end faces of the arms 53 and the webs 54.

[0047] The insulating washers 25, 26 are located between the winding head 23, 24 and the stator pack 20.

[0048] On the side of the insulating disc 25 facing away from the stator pack 20 there is another insulating disc 27, to which a winding head guard 28 is attached.

[0049] The insulating disc 25 ( Fig. 7 and Fig. 8) is designed as a flat disk that rests on the rotor-side end face of the stator stack 20. The insulating disk 25 has, in top view ( Fig. 7) approximately the same shape as the stator stack 20. Arms 71 extend radially outwards from a cylindrical inner ring 70, each provided at its free end with a circumferentially extending web 72. The webs 72 advantageously project the same distance circumferentially beyond the arms 71. The arms and the webs 72 are spaced apart from each other circumferentially.

[0050] The arms 71 extend, in the installed position of the insulating disc 25, viewed from above, from the radially outer outer surface 29 ( Fig. 2) of the stator stack 20 radially inwards. As can be seen from the Fig. 2, Fig. 3 and Fig. As can be seen from 7, the radial inner surface 30 of the inner ring 70 of the insulating washer 25 has a radial distance from the rotor bushing 10 and from the bearing seat 8. The radial distance to the bearing seat 8 forms a flow channel for the cooling air.

[0051] The arms 71 and the webs 72 define slots 73, which are congruent with the slots 55 of the stator stack 20.

[0052] The edges 74 of the grooves 73 extend perpendicular to the plane of the insulating disc 25 and are advantageously of the same height and preferably abut each other.

[0053] Each arm 71 is provided at the level of its web 72 with a projection 31 at half its width, which forms a positive locking part for the insulating washer 27 ( Fig. 2, Fig. 3 and Fig. 7).

[0054] The insulating washer 27 has a cylindrical inner ring 80 ( Fig. 4 and Fig. 5), from which radially outwardly extending arms 81 project. At their free ends, they are each provided with a circumferentially extending web 82. The webs 82 advantageously project the same distance circumferentially beyond the arms 81.

[0055] The arms 81 and the webs 82 are spaced apart from each other in the circumferential direction and define grooves 83, which are essentially congruent with the grooves 73 of the insulating disk 25 and the grooves 55 of the stator core 20. The webs 82 are each provided on their side facing the rotor base 11 with a projecting wall 32, which has a recess 33 on its underside facing the insulating disk 25, into which the projections 31 of the insulating disk 25 engage. Fig. 5a). The recess 33 is designed to be complementary to the projection 31. These positive-locking connections 31, 33 allow the two insulating discs 25 and 27 to be easily and precisely positioned relative to each other in the radial and circumferential directions.

[0056] The arms 81 of the insulating disc 27 have a flat, planar cover part 34 which rests on the insulating disc 25. On its side facing the rotor base 11, it is provided with a recess 35 which extends longitudinally along half the width of the arms 81.

[0057] The recess 35 is surrounded by a frame that extends from the wall 32 almost the entire length of the arms 81. The recesses 35 have a base 35a with which the arms 81 are connected on the end face 71a facing the rotor base 11 ( Fig. 7) the arms 71 of the insulating disc 25 rest on the insulating disc. In addition, the arms 81 of the insulating disc 27 with radially extending frame parts 36, 37, which laterally define the recesses 35, rest on the insulating disc 25 or its arms 71.

[0058] The frame parts 36, 37 connect radially inwards to cams 38 extending towards the rotor base 11, which project further axially towards the rotor base 10 than the radially opposite walls 32 of the insulating disk 27.

[0059] The cams 38 extend one behind the other in the circumferential direction of the insulating disk 27 and have a radial distance from the rotor bushing 10 and from the bearing seat 8.

[0060] The bottom 35a of the recesses 35 ends at a distance from the cams 38, thus forming a passage opening 39. This opening is covered, in the direction of the stator stack 20, by the radially inner area of ​​the insulating disk 25, as seen from above.

[0061] Support elements 40 are provided on an end-face wall section 44 of the winding head guard 28, distributed around the circumference of the winding head guard 28. Instead of individual support elements 40, a ring wall extending around the circumference can also be used.

[0062] The support elements 40 are advantageously formed integrally with the winding head guard 28 and rest on the insulating disc 27. The support elements 40 advantageously extend axially on the side of the cams 28 facing away from the walls 32 of the insulating disc ( Fig. 3) and extend at a short distance from the scenery 38.

[0063] The wall section 44 of the winding head guard 28 lies in the area between the rotor base 11 and the winding head 23 and extends radially outwards transversely to the stator bushing, in the exemplary embodiment approximately over half the radial width of the stator core 20. The wall section 44 lies axially above the winding head 23 and forms a side wall of an air guide duct 45 facing the stator core 20.

[0064] The air duct 45 is bounded on its side facing the rotor base 11 by a fan wheel 46, which is non-rotatably connected to the rotor 2. The fan wheel 46 is located axially opposite the winding head guard 28 and extends radially by the same distance as the winding head guard 28.

[0065] The wall section 44 of the winding head guard 44 overlaps the cams 28 from radially inside to radially outside, advantageously with a small distance.

[0066] The cams 38 and the support elements 40 of the winding head guard 28 are located radially opposite the bearing seat 8 for the ball bearing 6. This creates a passage 47 between the bearing seat 8 and the cams 38 or the winding head guard 28, which is in flow communication with the passage opening 39 and the air guide channel 45.

[0067] The fan wheel 46 is located in the area of ​​the rotor base 11. The rotor shaft 5 carries another fan wheel 48 at its end located in the area of ​​the stator flange 4 ( Fig. 1), which serves to cool the components in the electronics housing (not shown).

[0068] The fan wheel 46 is a radial fan wheel that draws in air axially within the rotor and expels it radially outwards. In the Fig. 2 and Fig. Figure 3 shows the corresponding airflow arrows. The air flows radially inwards between the winding heads 23 and the insulating disc 27. The air flows over the base 35a of the recess 35. The cover parts 34 of the insulating disc 27 form the lateral boundary and serve as a support for the winding 23. The cooling air continues to flow radially inwards through the opening 39 until it reaches the area of ​​the axial passage 47. The cooling air then enters the air guide duct 45, where it is again conveyed radially outwards. This creates a circular flow of cooling air that reaches the surface of the winding head 23 and reliably cools it. The cooling air also reaches the wall of the rotor 2. Since it is generally cooler than the winding head 23, the cooling airflow can be cooled to a small extent as it flows along the rotor wall, thus easily increasing the overall cooling capacity.

[0069] In the radially outer region, the cooling air flows axially towards the stator core 20 between the winding head 23 and the wall 32 of the insulating disc 27. A flow channel 49 is formed between the winding head 23 and the walls 32 of the insulating disc 27, through which the cooling air flows into a flow channel 50 between the winding head 23 and the insulating disc 27. In this way, the winding head 23 is cooled very effectively.

[0070] The fan wheel 46 draws in cooling air axially from the radially inner area of ​​the insulating disc 27, deflects it, and blows it radially outwards. The area between the cams 38 and the bearing seat 8 forms the passage 47 through which the fan wheel 46 draws in the cooling air axially.

[0071] The electric motor can also be designed so that the cooling air does not flow radially between the winding head 23 and the insulating disc 27, but between the insulating disc 25 and the stator stack 20.

[0072] Furthermore, it is possible to design the flow channels according to the embodiment as described in the Fig. 1 to 3 are formed, and an additional flow channel is provided between the insulating disc 25 and the stator assembly 20. The air flowing through these different, radially extending flow channels enters the passage 47, through which the cooling air is drawn in axially by the fan wheel 46.

[0073] The fan wheel 46 can also be positioned in the electric motor such that it draws in the cooling air in the radially outer region of the stator 1. In this case, the flow direction of the cooling air is reversed compared to the embodiment according to the Fig. 1 to 3.

[0074] The cooling air can, for example, be drawn in axially via the annular gap 19 between the stator 1 and the rotor 2.

[0075] The axially extending flow channels 47, 49 have the advantage that a larger portion of the winding surface of the stator 1 is cooled by the cooling air. This air flows past the winding wires of the stator 1, which are laid transversely across the insulating discs 25, 27 and the radially extending cooling channels, thereby cooling them. The cooling airflow exiting radially inwards from the flow channel 50 impinges on the stator-side bearing seat 8 for the ball bearing 6, thus also cooling these components and consequently the rotor-side bearing 6.

[0076] In the illustrated and described embodiment, the cooling channels 50 run below the winding head 23, i.e. in the insulating discs 25, 27. These radially extending cooling channels can also be incorporated in an overmolding of the stator stack 20.

[0077] In another embodiment, the cooling channels 50 can be arranged between the stator core 20 and the end-face insulation, e.g., the insulating disk 25, 27. In this case, the airflow through the cooling channel primarily cools the stator core 20. In this embodiment, the cooling channels 50 are arranged in the insulating disk 25, 27 on the side facing the stator core 20.

[0078] It is also possible to cool both the winding head 23 and the stator stack 20. In this case, the two designs described above are used in combination to form the flow channels.

[0079] In the illustrated embodiment, the insulation between the stator core 20 and the winding head 23 is formed by two insulating discs 25, 27. Due to this axially divided insulation, the cooling channels 50 can run at least partially between the two insulating discs 25, 27, thus facilitating the manufacturing of these insulating discs 25, 27 without undercuts. This also ensures electrical insulation between the winding and the stator core 20.

[0080] Insulation can also be provided by an insulating film or insulating paper that covers an axial hole in the insulating disk and thus enables compliance with the air creepage distances between the stator stack 20 and the winding head 23.

[0081] At their radially outer ends, the arms 81 are provided with walls 32, which serve to delimit the winding space and to support the winding on the stator 1. The walls 32 lie, in the axial direction according to Fig. 4 seen, perpendicular to the arms 81 of the insulating disc 27.

[0082] The walls 32 project the same distance circumferentially beyond the arms 81. As can be seen from the Fig. 4 and Fig. If 5 results, the walls 32 are essentially identical to each other.

[0083] The arms 81 are provided with webs 57 at radial distances from the walls 32, extending in the axial and circumferential direction of the stator stack 20 or the insulating disk 27.

[0084] The webs 57 of each arm 81 are spaced apart from each other in the circumferential direction of the stator 1 or the insulating disk 27. This creates openings 58 between the webs 57 for a (not shown) winding wire of the stator 1 winding.

[0085] Advantageously, the webs 57 of the arms 81 are each located at the same radial height of the arms 81.

[0086] In the exemplary design of the insulating disc 27, the webs 57 are arranged such that their radial distance from the walls 32 is smaller than from the inner ring 80.

[0087] The arms 81 are provided on their longitudinal sides 59, 60 with a groove 61 which advantageously extends over the entire radial length of the arms 81. The groove 61 serves to guide the winding wires cleanly during the winding process.

[0088] The design of the insulating disc 27 according to the Fig. 4, Fig. 5 and Fig. Figure 5a is to be understood as an exemplary embodiment only. Depending on the design of the stator assembly 20 or the stator 1, the insulating disc 27 may also have a different design.

[0089] To improve the cooling effect, the inner ring 80 and / or the bearing seat 8 can be designed to have the largest possible surface area exposed to the cooling airflow.

[0090] The cooling channels 47, 49, 50 can have a macro- or microstructure to increase the flow velocity of the cooling air. Such macro- or microstructures can be, for example, ribs, knobs, channels, bores, riblets, fins, etc. To further increase the flow velocity, it is also possible to partially narrow the cross-section of the respective flow channel 47, 49, 50.

[0091] Another possibility to increase the cooling effect is to design the flow channels 47, 49, 50 in a meandering shape in order to increase the surface area over which the components of the stator 1 are cooled.

[0092] It is also possible to direct the cooling air via the axial slots 55 ( Fig. 6) between the adjacent teeth of the stator stack 20 or, if the stator stack 20 is formed by disk-shaped fins, via axially penetrating grooves in the stator stack 20. In this case, the cooling air is drawn in from the electronics-side end of the stator stack 20, which is shown in the illustration according to Fig. 1 is the lower end of the stator package 20.

[0093] Slots can be provided in the radially inner recesses 38 so that cooling air can be drawn in from the area of ​​the winding heads 23 and the cooling air flows over the outer surface of the winding.

[0094] To achieve additional airflow around the winding heads 23, a cover can be arranged over the winding heads or the intake area on the walls 32. This directs the intake air over a larger surface area of ​​the winding heads 23 and improves cooling.

[0095] The cover can also be designed as an inlet nozzle in the intake area of ​​the fan wheel 46, thereby improving the flow.

[0096] The insulating washer 26 on the stator or electronics side is similarly designed to the insulating washer 27 on the rotor side. How Fig. As shown in Figure 6, the insulating disc 26 differs from the insulating disc 27 primarily in that, instead of the cams 38 on the inner ring 80, contact pockets 84 are arranged side by side along the circumference of the inner ring 80. The contact pockets 84 project axially from the inner ring 80 on the side facing away from the stator 1.

[0097] The contact pockets 84 accommodate (not shown) contact elements for the winding wires in a known manner.

[0098] Unlike the insulating washer 27, the arms 81 have no openings, but are closed along their radial length. Otherwise, the arms 81 are designed in the same way as those of the insulating washer 27.

[0099] Since the insulating disc 26 is advantageously designed in one piece, this allows for simple and cost-effective manufacturing and easy assembly on the stator 1.

[0100] The Fig. 10 and Fig. Figure 11 shows a further embodiment of an insulating disc 27. The basic structure of this insulating disc 27 corresponds to the embodiment according to the Fig. 3 to 5. The stator 1 and the rotor 2 are designed identically to the previous embodiment. In contrast to this embodiment, only one insulating disk 27 is provided on the rotor side of the stator assembly 20. It has the inner ring 80, from which the cams 38 project axially towards the base 11 of the rotor 2.

[0101] The arms 81 extend radially from the inner ring 80 as described. At their free ends, they have transverse webs 82 on which transversely, preferably vertically, projecting walls 32 are provided. Radially spaced from these are the webs 57, which project transversely from the frame parts 36, 37 of the arms 81.

[0102] The frame parts 36, 37 are provided with grooves 61 along their length.

[0103] On the underside of the arms 81 ( Fig. 11) Each arm 81 has a recess 85 that extends almost the entire length of the arms 81. The recess 85 has a rectangular outline and advantageously a uniform height along its length. The recess 85 is open radially outwards and inwards and connects radially inwards to a recess 89. This allows air to flow from the radial outside to the inside of the passage 47.

[0104] As from Fig. As can be seen from Figure 10, the insulating disc 27, unlike in the previous embodiment, rests directly on the stator core 20. A second insulating disc is not provided.

[0105] The flow channels 50 are formed by the recesses 85 of the arms 81, which are bounded towards the rotor base 11 by a base 86 of the recesses 85 and on the opposite side by the top of the stator stack 20. In the circumferential direction, the flow channels 50 are bounded, as in the previous embodiment, by the radially extending side walls 87, 88 ( Fig. 11) limited.

[0106] The flow channels 50 serve to guide the cooling air, which in this embodiment primarily cools the stator core 20. The winding head 23 is also cooled, but not to the same extent as the stator core 20.

[0107] In Fig. Figure 10 shows the flow path of the cooling air, indicated by the flow arrows. Air is drawn in radially from the outside in the area of ​​the air gap 19 and enters the flow channels 50. The cooling air flows radially inwards and, according to the previous design, enters the air guide channel 45 of the fan wheel 46 via the through openings 39 and the passage 47.

[0108] The described variant of the intake area in the exemplary embodiment according to the Fig. 10 and Fig. 11 can also be combined with the previous embodiment, in which the flow channels 50 are arranged on the top side of the insulating disc 25. In this case, cooling is provided to both the winding heads 23, 24 and the stator core 20.

[0109] In the described embodiments, the insulating washer 27 is only provided at the rotor-side end of the stator stack. However, it can also be arranged at the electronics-side end of the stator stack.

[0110] The cover can also be designed as an inlet nozzle in the intake area of ​​the fan wheel 46, thereby improving the flow.

Claims

[1] Stator for an electric machine, in particular an electric drive, with at least one stator stack (20) which sits on a stator bushing (3) which is provided with at least one bearing seat (8, 9) for a rotary bearing (6, 7) for a rotor shaft (5) and with at least one winding head (23, 24) which projects axially beyond the stator stack (20), characterized by , that in the area between the winding head (23, 24) and the stator stack (20) at least one flow channel (47, 49, 50) for cooling air is provided, which extends over at least a part of the radial and / or circumferential length of the winding head (23, 24). [2] Stator according to claim 1, characterized by , that the flow channel (47, 49, 50) extends radially at least over part of its length. [3] Stator according to claim 1 or 2, characterized by, that the flow channel (49, 50) runs between the winding head (23, 24) and an electrical insulation (25, 26) covering the stator stack (20). [4] Stator according to any one of claims 1 to 3, characterized by , that the flow channel has at least one axial intake section (49) which is flow-connected to a radial section (50) of the flow channel. [5] Stator according to any one of claims 1 to 4, characterized by , that the flow channel has at least one axial outlet section (47) which is flow-connected to the radial section (50) of the flow channel. [6] Stator according to claim 5, characterized by , that the outlet section (47) is flow-connected to an outflow section (45). [7] Stator according to claim 6, characterized by , that the outflow section (45) is located at an axial distance from the radial section (50) of the flow channel. [8] Stator according to claim 6 or 7, characterized by, that the outflow section (45) is limited by a fan wheel (46) and a guide wall (44). [9] Stator according to claim 8, characterized by , that the fan wheel (46) is part of a rotor (2) and serves to adjust an optimal cooling air flow. [10] Stator according to any one of claims 6 to 9, characterized by , that the outflow section (45) extends radially. [11] Stator according to any one of claims 6 to 10, characterized by , that the outflow section (45) is designed such that the cooling air exiting it flows over at least part of the winding head (23, 24). [12] Stator according to any one of claims 1 to 11, characterized by , that the flow channel (47, 49, 50) is open in the direction of the bearing seat (8, 9). [13] Stator according to any one of claims 5 to 12, characterized by , that the axial section (47) of the flow channel (47, 49, 50) runs adjacent to the bearing seat (8, 9). [14] Stator according to any one of claims 5 to 13. characterized by , that the axial outlet section (47) of the flow channel (47, 49, 50) is limited on one side by the bearing seat (8, 9). [15] Stator according to any one of claims 1 to 14, characterized by , that to increase the surface area in the area of ​​the bearing seat (8, 9) the flow channel (47, 49, 50) and / or ribs are provided. [16] Stator according to any one of claims 1 to 15, characterized by , that the flow channel (47, 49, 50) has a macro- or microstructure. [17] Electric motor with a stator according to any one of claims 1 to 16. [18] Electric motor according to claim 17, characterized by that the electric motor is an external rotor motor.

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