Cooling wheel for actively cooling a stator of an electric motor

Abstract

The invention relates to a cooling wheel (1) for actively cooling a stator (2) of an electric motor (3). The cooling wheel (1) can be fixed, for conjoint rotation, on a rotor (4) of the electric motor (3) such that the cooling wheel is adjacent to the stator (2), said rotor being rotatable about an axis of rotation (A). The cooling wheel has a bottom disc (10), which extends orthogonally to the axis of rotation (A) and comprises an annular radially inner portion (12) and a radially outer portion which annularly extends around said radially inner portion. The cooling wheel (1) has, adjacent to the radially outer portion of the bottom disc (10) in the axial direction, a cover disc (30), which annularly extends around the axis of rotation (A), and a plurality of blades (20), which extend from the bottom disc (10) to the cover disc (30) and radially outward. Between each pair of immediately adjacent blades (20), a flow channel is formed which is delimited by the two blades (20), by a portion (11) of the bottom disc (10) lying between the two blades, and by a portion (31) of the cover disc (30) lying between the two blades (20). Each portion (31) of the cover disc (30) is arcuate in the circumferential direction (U), and the cover disc (30) has an undulating profile on its outer circumference (32).

Description

[0001] Cooling wheel for active cooling of a stator of an electric motor

[0002] Description:

[0003] The invention relates to a cooling wheel for actively cooling a stator with stator electronics of an electric motor and to an electric motor with such a cooling wheel.

[0004] A variety of solutions for cooling stators in electric motors are known from the state of the art. Often, only a passive

[0005] Cooling is provided in which the stator, for example, provides cooling fins through which heat is dissipated to the environment without a defined fluid flow and in particular air flow being generated at these.

[0006] Since defined cooling is only possible to a limited extent without a defined flow, such solutions are subject to numerous limitations. Alternatively, concepts for active cooling are also known in the prior art, for example, from DE 10 2012 107 109 A1, in which a fluid flow, i.e., an air flow, is actively generated and used to cool the stator.

[0007] However, particularly at higher or increasing speeds, the noise development and torque requirement of such a cooling wheel can become unfavorable and lead to reduced efficiency and a high noise level.

[0008] The invention is therefore based on the object of overcoming the aforementioned disadvantages and providing a cooling wheel for actively cooling a stator of an electric motor, which has the lowest possible torque requirement and the lowest possible noise emissions even at higher speeds.

[0009] This problem is solved by the combination of features according to patent claim 1.

[0010] According to the invention, a cooling wheel is therefore proposed for actively cooling a stator of an electric motor, wherein the electric motor is, in particular, an external rotor motor. For cooling the stator, the cooling wheel can be fixed in a rotationally fixed manner adjacent to the stator on a rotor of the electric motor that can rotate about a rotation axis. Preferably, the electric motor is the motor of a fan, so that an impeller can also be provided on the rotor in addition to the cooling wheel. According to the invention, the cooling wheel has a base disk extending orthogonally to the axis of rotation, with an annular radially inner section and a radially outer section that runs around the latter in a ring-shaped manner and is correspondingly also annular. The cooling wheel also has in the axial direction, ie along the axis of rotation oran axis parallel to the axis of rotation adjacent to the radially outer section of the base disk, a cover disk running annularly around the axis of rotation and a plurality of blades extending from the base disk to the cover disk and radially outward. Viewed from the side of the cover disk, the radially outer section of the base disk preferably corresponds to the projection of the cover disk on the base disk. Between each two immediately adjacent blades, a flow channel is formed which is delimited by the two immediately adjacent blades, a section of the base disk lying between the two blades and a section of the cover disk lying between the two blades. Accordingly, the cooling wheel has a plurality of flow channels adjacent to one another in the circumferential direction, each of which is delimited by two blades, the cover disk and the base disk.In order to reduce noise emissions, especially at high speeds, each section of the cover plate is designed to be arcuate or curved in the circumferential direction, so that the cover plate has a wave-like shape on its outer circumference in the circumferential direction.

[0011] The curvature can in particular be convex, so that the sections of the cover disk which each span a space between two immediately adjacent blades and thus delimit the respective flow channel curve outwards away from the base disk or towards the stator.

[0012] The cooling wheel is preferably made of plastic and, in particular, is manufactured using an injection molding process. To avoid a complex manufacturing tool, which, for example, requires a large number of slides, it is preferably provided that the base plate and cover plate are formed separately and then joined. The blades can be manufactured integrally with the base plate or the cover plate. The cover plate and the base plate, on which the blades can each be formed, can then be joined, for example, by hot stamping, so that the cooling wheel is a single piece.

[0013] In the present case, the stator is understood to mean in particular the stator bushing on which the cooling fins mentioned later are formed and which surrounds further components of the stator, such as in particular stator electronics, as a housing.

[0014] The stator has in particular the stator bushing with stator package and stator electronics, wherein the stator electronics is a control unit for controlling the electric motor.

[0015] To optimize the suction-side flow, it can also be provided that the radially inner section of the base plate and an adjacent area in the axial direction are free of the blades and the cover plate, and in particular also other flow obstructions. The radially inner section can be arranged axially adjacent to the stator, wherein the blades are designed to convey fluid, in particular air, from the radially inner section of the base plate as the suction side of the stator through the flow channels formed by the blades, radially outward, and in particular into a radially adjacent environment as the pressure side.

[0016] The radially inner section of the base plate can be further optimized in terms of flow technology by forming or providing a continuous transition from a section of the base plate that is essentially orthogonal to the axis of rotation, which can be the radially outer section of the base plate, to a section of the base plate that is essentially parallel to the axis of rotation. This transition forms a continuous intake contour. Viewed in a longitudinal section along the axis of rotation, the radially inner section can accordingly have a concave profile from the radially outer to the radially inner.

[0017] With respect to the sections of the cover plate that define a flow channel, their respective curvature can also increase from the radially inner to the radially outer. In the circumferential direction, the curvature can, for example, be 0 at an inner circumference of the cover plate and increase toward the radially outer.

[0018] A curvature of the sections, or generally the arcuate sections, preferably each have a maximum with respect to their course in the circumferential direction, which is preferably arranged symmetrically in the circumferential direction on the respective flow channel. Alternatively, however, multiple maxima and / or an asymmetric arrangement of the maxima(s) are also possible.

[0019] Preferably, the radially inner section of the base plate has a continuous, i.e. edge- and jump-free, course and is in particular free of flow obstacles.

[0020] To secure the cooling wheel to the rotor, fastening elements can be arranged in the radially inner section of the base plate. For example, through holes are provided in the base plate through which screws can be inserted as fastening elements. The fastening elements can be used to attach the cooling wheel or the base plate of the cooling wheel to the rotor or a flange ring that can be fixed to the rotor.

[0021] Furthermore, the fastening elements can also be provided on the inner circumference of the base plate.

[0022] The fastening elements can be, for example, screws or locking elements.

[0023] In particular, if locking elements are provided on the radially inner section of the base plate, these can be adjacent in the circumferential direction on both sides to spring elements which are designed to compensate for a tolerance and to hold the cooling wheel on the rotor or the flange ring without play.

[0024] To prevent, for example, screw heads or fastening elements in general from constituting flow obstructions in the radially inner section of the base plate, a cover element can be arranged adjacent to the fastening elements on a surface of the base plate facing the cover plate, i.e., on an electric motor, facing the stator. The cover elements are designed to cover the fastening element on the surface facing the cover plate and to provide a continuous and, in particular, a plane-to-surface flow path on the surface of the base plate that optimizes flow.

[0025] Further preferably, the cover elements or the respective cover element can be designed to be surface-integrated, so that the cover plate-side surface of the base plate merges into the cover plate-side surface of the respective cover element without a gradient jump.

[0026] Recesses can also be provided in or on the radially inner section of the base plate, forming depressions opposite one or the cover-plate-side surface of the base plate, into which the fastening elements can be arranged at least partially countersunk. For example, screw heads of screws serving as fastening elements can be countersunk into the depression. In general, the recesses or depressions allow the fastening elements to be arranged completely below the cover-plate-side surface of the radially inner section of the base plate.

[0027] Particularly when the cooling wheel is provided on a fan or the electric motor of a fan, a variant is advantageous in which the base plate has connection interfaces for connecting an impeller on a side facing away from the cover plate. The connection interfaces can be designed, in particular, as bolts extending parallel to the rotation axis or as pockets formed in the base plate for receiving insert nuts.

[0028] If the cooling wheel is not fixed directly to the rotor, but for example via an annular flange, the bolts extending parallel to the axis of rotation or in the axial direction can also be formed on the annular flange or integrated into it.

[0029] Such bolts can also be designed as threaded stud bolts.

[0030] To optimize the flow generated by the blades, the blades preferably have a sickle-shaped blade geometry and are curved in the circumferential direction from the radially inner to the radially outer. The blades are preferably forward-curved. A sickle-shaped blade geometry is particularly advantageous when the rotor or cooling wheel has a single, predetermined direction of rotation.

[0031] If, however, it is intended that the rotor or cooling wheel can be driven in both directions of rotation, so that the cooling wheel is designed for both clockwise and counterclockwise rotation, the blades preferably have a straight or only slightly curved blade geometry.

[0032] One aspect of the invention also relates to an electric motor with a stator, a rotor rotatable about a rotational axis, and a cooling wheel according to the invention arranged on the rotor for cooling the stator. The stator and rotor are preferably arranged one after the other in the axial direction, the electric motor being in particular an external rotor motor. More preferably, the electric motor can also be the motor of a fan, which can have an impeller connected to the rotor. The cooling wheel is arranged on an end section of the rotor on the stator side in the axial direction and, with the radially inner section of the base plate, directly adjoins the stator, so that upon rotation of the rotor, a fluid flow is generated radially outward through the flow channels from a section of the stator adjacent to the radially inner section of the base plate in the axial direction.

[0033] Furthermore, the cooling wheel can be fixed directly to the rotor with its base plate. Alternatively, the cooling wheel can be fixed with its base plate to a flange ring, which is fixed to the rotor. If such a flange ring is provided, bolts, in particular threaded stud bolts, can be provided on it, pointing away from the cooling wheel for fixing, for example, an impeller to the flange ring. Alternatively, recesses corresponding to the connection interfaces of the base plate can also be provided in the flange ring, so that a fastening means for fixing, for example, the impeller, can be screwed through the recesses into the connection interfaces of the base plate of the cooling wheel.

[0034] To improve cooling, the stator and in particular the stator bushing of the stator can have cooling fins distributed in the circumferential direction around the axis of rotation, which are arranged in the axial direction directly adjacent to the radially inner section of the cooling wheel and extend in particular in the radial direction.

[0035] The cooling wheel also preferably defines, on the radially inner section of the base disc, a suction chamber which is delimited by the base disc, the blades and the cover disc, runs annularly around the axis of rotation and is open to the stator, wherein the cooling fins extend into the suction chamber.

[0036] An advantageous further development also provides that the cooling wheel and in particular the base plate forms a labyrinth seal with the stator on a radially inner circumference.

[0037] The features disclosed above can be combined as desired, as long as this is technically possible and they do not contradict each other.

[0038] Other advantageous developments of the invention are characterized in the subclaims or are presented in more detail below, together with the description of the preferred embodiment of the invention, with reference to the figures. They show:

[0039] Fig. 1 An electric motor for a fan with cooling wheel;

[0040] Fig. 2a-c different views of a first variant of a cooling wheel;

[0041] Fig. 3a-d different views of a second variant of a cooling wheel;

[0042] Fig. 4a-d different views of a third variant of a cooling wheel;

[0043] Fig. 5a-c different views of a fourth variant of a cooling wheel;

[0044] Fig. 6 is a perspective view with cutaway of a fifth variant of a cooling wheel;

[0045] Fig. 7 is a side view with cutout and detailed view of a first variant of an electric motor;

[0046] Fig. 8 shows a side view with a cutaway and a detailed view of a second variant of an electric motor. The figures are schematic examples. Like reference numerals in the figures indicate like functional and / or structural features.

[0047] Figure 1 shows an electric motor 3, in particular for a fan, in its entirety, so that its stator 2, the rotor 4 and the cooling wheel 1 are visible. The rotor 4 can rotate about the axis of rotation A, wherein the cooling wheel 1, which is arranged in the axial direction, ie along the axis of rotation A between the rotor 4 and stator 2, is fixed to the rotor 4 and thus rotates together with the rotor 4 about the axis of rotation A. The cooling wheel 1 actively generates an air flow from the radial inside to the radial outside. Accordingly, the cooling wheel 1 has a suction side radially inside and adjacent to the stator 2 and a pressure side radially outside or on the outer circumference of the cooling wheel 1. Air is therefore actively sucked in via the stator 2 and blown out radially outwards.

[0048] The stator 2 has in particular a housed stator electronics 7 and a stator bushing 8, wherein the cooling fins 60 are formed on the stator bushing 8, which extend on or into the suction chamber of the cooling wheel 1.

[0049] Both for the cooling wheel 1 shown in Figure 1 and for all cooling wheels shown in the other figures, they each have a base plate 10, a plurality of blades 20 and a cover plate 30. The blades 20 are, as can be seen in particular in Figures 2a, 2c, 3a, 3c, 3d, 4a, 4c, 5a, 5c and 6 to 8, arranged exclusively in a radially outer, ie, in the radial direction R, outside section of the base plate 10, which runs annularly around the rotation axis A, and are covered in the axial direction or towards the stator by the cover plate 30. In this case, it is provided in each case that a radially inner, iein the radial direction R inside and the rotation axis A annularly encircling section 12 is free of blades 20, the cover plate 30 and in particular free of further flow obstacles, so that on the radially inner section 12, in the state arranged on the stator 2, a suction chamber is formed which is open to the stator 2 and through which air can be sucked in by the stator 2 in a flow-optimized manner.

[0050] To generate optimized flow, the blades 20 each have a sickle-shaped geometry and are preferably inclined counter to the intended direction of rotation. Two blades 20 arranged directly next to each other form a flow channel between them, which is delimited in the circumferential direction U by the blades 20 and in the axial direction by a section 11 of the base plate 10 and a section 31 of the cover plate 30. Accordingly, the flow channel is open in the radial direction R.

[0051] Tests have shown that, particularly at high speeds, a significant reduction in the noise generated by the cooling wheel 1 is achieved if the cover plate 30 is not flat, but rather has a wave-like shape in the circumferential direction U. Accordingly, each of the sections 31 of the cover plate 30 that delimit a flow channel, i.e., those located between two immediately adjacent blades 20, is arcuate or curved. This results in a continuous alternation between maxima and minima in the circumferential direction, thus creating the wave shape.

[0052] As shown in the corresponding figures, the cover disk 30 or its sections 31 have no or only a minimal curvature on the inner circumference, which becomes larger towards the radial outside, ie in the radial direction R away from the axis of rotation A.

[0053] Although the transition between two sections 31 or between the two arcs determined by the sections 31 can also be abrupt, it is preferably provided that the transition is continuous, so that between two sections 31 or the two arcs determined by them, no edge but a smooth transition is formed.

[0054] Figures 2a to 2c show a first variant of a cooling wheel 1. Figure 2a shows a perspective view of a side of the cooling wheel 1 facing the stator 2 in the assembled state, and Figure 2b shows a side of the cooling wheel 1 facing the rotor 4 or facing away from the stator 2. Figure 2c shows a section of a longitudinal section along the rotation axis A through the cooling wheel 1.

[0055] The variant according to these figures is characterized in particular by the fact that the cooling wheel 1 can be fixed to the rotor 4 via an annular flange 5, as shown in Figure 2c. For this purpose, a plurality of recesses 44 distributed in the circumferential direction are shown on the radially inner section 12, through which screws as fastening elements 40 can be screwed to the annular flange 5. The recesses 44 are designed as countersunk or stepped through holes, so that the screw heads of the screws are at least partially countersunk in the base plate 10 and represent a smaller flow obstacle, as is particularly visible in Figure 2c.

[0056] To optimize flow, it is further provided that the base plate 10 has a flow-optimized profile from the radially outer section to the radially inward or in the radially inner section 12 towards the rotation axis A. This is formed by a continuous transition from a section of the base plate 10 orthogonal to the rotation axis A, which in this case essentially corresponds to the radially outer section, to a section 13 of the base plate 10 parallel to the rotation axis A, resulting in a concave profile. Along this transition, the air sucked in via the stator 2 is deflected in the direction of the flow channels and accordingly radially outward.

[0057] Adjacent to the radial inside there is also an annular circumferential groove 14 and an annular circumferential projection 15, which form a labyrinth seal 6 with corresponding elements of the stator.

[0058] Figures 3a to 3d show an alternative variant, with Figure 3a again showing a stator-side view and Figure 3b showing a rotor-side view.

[0059] As shown in particular in Figures 3a, 3c and 3d, screws are again provided as fastening elements 40, wherein the recesses 44 are formed so deep that the screw heads are completely countersunk and lie below the surface defining the stator side of the base plate 10. To further optimize the flow along this surface, cover elements 43 are also provided, wherein each cover element 43 closes a recess 44 and covers a screw or a fastening element 40. The cover elements 43 are, as shown in Figure 3c, integrated flush with the stator-side surface of the base plate 10, so that this surface or the radially inner section 12 of the base plate 10 is free of flow obstructions.

[0060] If the cooling wheel 1 is to be used, as shown in Figures 3a to 3d, preferably on an electric motor 3 of a fan, an impeller can also be fixed to the rotor 4 via the flange ring 5 (not shown). For this purpose, connection interfaces and, in this case, pockets 50 are provided in the base plate 10, in which insert nuts are held. Corresponding openings are provided in the flange ring 5 so that an impeller can be arranged on the flange ring 5 and screwed to the insert nuts held in the pockets 50. Alternatively, screws or screw heads can also be inserted into the pockets so that the thread of the screws runs through the ring flange 5.

[0061] The variant of the cooling wheel 1 shown in Figures 4a to 4d is particularly characterized by the fact that locking elements 41 are provided as fastening elements for attachment to an annular flange 5. These are formed integrally with the base plate 10 in the present case, but can also be provided separately.

[0062] As shown in Figure 4c, the locking elements 41 penetrate the annular flange 5 and are connected to it by means of spring-loaded arms. To prevent any play that would allow movement from remaining between the annular flange 5 and the base plate 10, it is also provided that the locking element 41 is adjacent to a spring element 45 on both sides in the circumferential direction U, as shown in the sectional view of Figure 4d. The spring elements 45 are each supported on the annular flange 5 and thus keep the connection between the base plate 10 and the annular flange 5 free of play via the locking element 41.

[0063] As shown in Figure 4c, this variant also provides a transition from the radially outer section orthogonal to the rotation axis A to the section 13 parallel to the rotation axis A, as well as a groove 14 and a projection 15 for producing a labyrinth seal 6.

[0064] In the variant illustrated in Figures 5a to 5d, the cooling wheel 1 is not mounted or fixed to an annular flange 5, but directly to a stator-side end face of the rotor 4. For this purpose, fastening elements designed as locking hooks 42 are provided on the inner circumference of the cooling wheel 1, which extend into the rotor 4 and rust thereto, as can be seen in Figure 5c. A particular advantage here is that no fastening elements 40 need to be concealed or aerodynamically optimized in the radially inner region 12, and the region 12 is therefore free of flow obstructions.

[0065] Figure 6 shows a partially sectioned cooling wheel 1 and an enlarged section of this cooling wheel 1. Unlike the variant shown in Figures 3a to 3d, the base plate 10 also forms pockets 50 for receiving insert nuts, which, however, are not recessed below the stator-side surface of the base plate 10, but rather protrude beyond it.

[0066] Through the section and the enlargement of the section, in particular the sickle-shaped shape of the blades 20, which is inclined counter to the direction of rotation, is visible, as the blades 20 can have in each of the embodiments shown.

[0067] Figures 7 and 8 each show a side view of an electric motor 3 and a partial enlargement in the area of ​​the cooling wheel 1.

[0068] In particular, in the enlarged section, the labyrinth seal 6 is shown, which is formed by the groove 14 and the projection 15 of the base plate 10 as well as a circumferential projection 61 of the stator, so that penetration of foreign particles into the interior of the motor 3 can be prevented.

[0069] Furthermore, it is shown in both figures that the stator 2 forms a plurality of cooling fins 60 adjacent to the cooling wheel 1, which are arranged distributed in the circumferential direction around the rotation axis A and extend along the radial direction R.

[0070] In Figure 7, the cooling fins 60 border the suction chamber, which is formed in the region of the radially inner section 12 of the base plate 10 and is open in the axial direction toward the stator 2, so that air can be sucked between the cooling fins 60 into the suction chamber, with the air flowing along the cooling fins 60 cooling the stator 2. The variant shown in Figure 7 is preferably the electric motor 3 according to Figure 1.

[0071] In the embodiment according to Figure 8, the cooling fins 60 do not merely border the suction chamber, but extend into it.

[0072] The invention is not limited to the preferred embodiments described above. Rather, a number of variants are conceivable that utilize the presented solution even in fundamentally different embodiments.

Claims

Patent claims 1. Cooling wheel (1) for actively cooling a stator (2) of an electric motor (3), wherein the cooling wheel (1) is rotatably fixed adjacent to the stator (2) on a rotor (4) of the electric motor (3) rotatable about an axis of rotation (A) and has a base disk (10) extending orthogonally to the axis of rotation (A) with an annular radially inner section (12) and a radially outer section circumscribing this annularly, wherein the cooling wheel (1) has, in the axial direction adjacent to the radially outer section of the base disk (10), a cover disk (30) circumscribing the axis of rotation (A) annularly and a plurality of blades (20) extending from the base disk (10) to the cover disk (30) and radially outwards, wherein a flow channel is formed between each pair of immediately adjacent blades (20), which is formed by the two blades (20),a section (11) of the bottom disk (10) located between the two blades and a section (31) of the cover disk (30) located between the two blades (20) is bounded, wherein the respective section (31) of the cover disk (30) is formed in an arc-shaped manner in the circumferential direction (U) and the cover disk (30) has a wave-like shape on its outer circumference (32).

2. Cooling wheel according to claim 1, wherein the radially inner section (12) of the base disk (10) and an axially adjacent area is free from the blades (20) and the cover disk (30), can be arranged adjacent to the stator (2) and the blades (20) are designed to allow fluid from the radially inner section (12) of the base disk (10) conveys the fluid from the stator (2) through the flow channels formed by it to the radial outwards. Cooling impeller according to claim 1 or 2, wherein a continuous transition from a section of the base disk (10) orthogonal to the axis of rotation (A) to a section of the base disk (10) parallel to the axis of rotation (A) is formed on the radially inner section (12) of the base disk (10), such that a continuous intake contour is formed by the transition. Cooling impeller according to one of the preceding claims, wherein the curvature of the respective arcuate section (31) of the cover disk (30) increases from radially inner to radially outer. Cooling impeller according to one of the preceding claims, wherein the radially inner section (12) of the base disk (10) has a continuous profile and is, in particular, free of flow obstructions.Cooling wheel according to one of the preceding sections, wherein fastening elements (40, 41, 42) for fastening the base plate to the rotor (4) or a flange ring (5) fixable to the rotor (4) are formed or can be arranged in the radially inner section (12) of the base plate (10). Cooling wheel according to the preceding claim, wherein a cover element (43) can be arranged on a cover plate-side surface of the base plate (10) adjacent to the fastening elements (40), which is designed to cover the fastening element (40) and to be attached to the cover plate-side surface. The surface of the base plate (10) is to provide a continuous and, in particular, a surface-level profile relative to the surface of the base plate (10). Cooling wheel according to one of the two preceding claims, wherein in the radially inner section (12) of the base plate (10) Recesses (44) are provided which form depressions opposite a cover plate-side surface of the base plate (10) into which the fastening elements (40) can be recessed. Cooling wheel according to one of the preceding claims, wherein the base plate (10) is mounted on a surface separated from the cover plate. (30) has connection interfaces on the opposite side for connecting an impeller, wherein the connection interfaces are in particular designed as bolts extending parallel to the axis of rotation or as pockets (50) for receiving insert nuts. Cooling impeller according to one of the preceding claims, wherein the blades (20) have a sickle-shaped blade geometry and curve circumferentially from radially inside to radially outside. Electric motor (3) with a stator (2), a rotor (4) rotatable about an axis of rotation (A) and a cooling impeller (1) arranged on the rotor (4) according to one of the preceding claims for cooling the stator (2), wherein the electric motor (3) is in particular designed as an external rotor motor and wherein the cooling impeller (1) is arranged on an end section of the rotor (4) on the axial side facing the stator and is directly connected to the stator (2) with the radially inner section of the base disk (10). adjacent, so that when the rotor (4) rotates, a fluid flow is generated from a section of the stator (2) adjacent in the axial direction to the radially inner section (12) of the base disk (10) through the flow channels to the radial outside.

12. Electric motor according to the preceding claim, wherein the cooling wheel (1 ) with its base disk (10) is fixed directly to the rotor (4) or wherein the cooling wheel (1 ) with its base disk (10) is fixed to a flange ring (5) which is fixed to the rotor (4).

13. Electric motor according to one of the two preceding claims, wherein the stator (2) has cooling fins (60) arranged circumferentially around the axis of rotation (A), which are arranged in the axial direction directly adjacent to the radially inner section (12) of the cooling wheel (1) and extend in particular in the radial direction (R).

14. Electric motor according to the preceding claim, wherein the cooling wheel (1 ) on the radially inner section (12) of the base disk (10) defines a suction chamber bounded by the base disk (10), the blades (20) and the cover disk (30), the axis of rotation (A) running annularly around and open to the stator (2), and the cooling fins (60) extend into the suction chamber.

15. Electric motor according to one of claims 11 to 14, wherein the cooling wheel (1 ) and in particular the base disk (10) forms a labyrinth seal (6) with the stator (2) on a radial inner circumference. * * * * *

Images