Rotor arrangement for an electrical machine and electrical machine

Abstract

Rotors of electrical machines can be cooled with a coolant. This cooling is to be improved. The invention relates to a rotor arrangement (1) for an electrical machine, comprising a rotor (3) and a rotor shaft (6) which runs along an axis of rotation of the rotor (3), wherein the rotor shaft (6) has a coolant outlet (7) which is arranged with respect to a rotor surface (8) in such a way that a coolant (9) can be guided from the coolant outlet (7) to the rotor surface (8), wherein the rotor surface (8) has at least a first partial surface (11) along a first plane and a second partial surface (12) along a second plane, wherein the first plane is different from the second plane, wherein a guide plate (13) which is fastened to the rotor (3), wherein the guide plate (13) is shaped and arranged on the rotor (3) in such a way that the coolant (9) can be guided from the first partial surface (11) to the second partial surface (12).

Description

[0001] The invention relates to a rotor arrangement for an electrical machine, comprising a rotor and a rotor shaft extending along a rotational axis of the rotor, wherein the rotor shaft has a coolant outlet arranged relative to a rotor surface such that a coolant can be guided from the coolant outlet to the rotor surface. The rotor surface has at least a first partial surface along a first plane and a second partial surface along a second plane, wherein the first plane is different from the second plane.

[0002] Electrical machines with a rotor and a stator are common. During operation, the electrical machine heats up due to losses. These can be divided into ohmic losses, iron losses, stray losses, and mechanical losses. Iron losses occur primarily in the stator and rotor and contribute significantly to the total losses. If the electrical machine heats up too much, it can be destroyed. Therefore, various cooling systems are known in the state of the art.

[0003] DE 10 2015 015 797 A1 discloses an electric machine with a rotor and a stator. The stator comprises at least one winding having a surface facing the rotor, which can be exposed to a cooling fluid sprayed radially outward from the rotor as the rotor rotates, to cool the winding. The surface extends at least in a partial region obliquely to the axial direction of the rotor.

[0004] The invention is based on the object of providing more effective cooling for an electrical machine, in particular a rotor of the electrical machine.

[0005] The object is achieved by the subject matter of the independent patent claims. Advantageous developments of the invention are described by the dependent patent claims, the following description, and the figures.

[0006] The invention is based on the idea of ​​using a guide plate to guide a coolant along a rotor surface over critical points, so that the contact time between coolant and rotor is improved and extended, thereby enabling more effective cooling of the rotor without the need for complicated cooling channel structures.

[0007] One aspect of the invention relates to a rotor arrangement for an electric machine. The rotor arrangement has a rotor and a rotor shaft that runs along a rotational axis of the rotor. The rotor shaft has a coolant outlet. The coolant outlet is arranged with respect to a rotor surface of the rotor such that a coolant can be guided from the coolant outlet to the rotor surface. The rotor surface has at least a first partial surface along a first plane and a second partial surface along a second plane. The first plane is different from the second plane. The rotor arrangement has a guide plate. The guide plate is attached to the rotor. The guide plate is shaped and arranged on the rotor such that the coolant can be guided from the first partial surface to the second partial surface.

[0008] By specifically guiding the coolant flow along the rotor surface from the first partial surface to the second partial surface using the guide vane, convective heat transfer between the rotor and the coolant can be improved. This prevents premature coolant separation from the rotor surface and enables a defined heat exchange from the rotor to the coolant. The rotor surface can also be referred to as the rotor back surface or rotor disk surface.

[0009] Without the targeted guidance of the coolant by the guide plate from the first partial surface to the second partial surface, a large portion of the coolant is discarded at the transition, so that only a significantly lower heat transfer from the rotor surface to the coolant can be achieved. By attaching the appropriately designed guide plate to the rear of the rotor, the coolant can be held on the rotor surface. This can extend the contact time between the coolant and the rotor surface. As a result, the effectiveness of rotor cooling can be significantly improved by the rotor arrangement according to the invention, which can enable an increase in the continuous power of the electrical machine and / or enable the use of more cost-effective magnetic materials or adhesives and the like.In particular, this is possible because the improved cooling of the rotor leads to a lower temperature at the rotor magnets and adhesives, which reduces the temperature requirements for the magnetic materials and adhesives.

[0010] There is a transition between the first partial surface and the second partial surface. The transition forms, for example, a projection and / or has at least one kink. The first partial surface is radially closer to the axis of rotation than the second partial surface. In particular, the first partial surface and the second partial surface are arranged perpendicular to the axis of rotation. Thus, a normal direction on the first partial surface is parallel to a normal direction on the second partial surface and parallel to the axis of rotation.

[0011] Preferably, the guide plate completely covers the transition. Additionally, the guide plate at least partially covers the first partial surface and the second partial surface, particularly in areas adjacent to the transition. In particular, the guide plate covers a maximum of 50%, particularly a maximum of 30%, and particularly a maximum of 20%, of the rotor surface. Preferably, an edge region of the second partial surface is not covered by the guide plate. This allows for savings in installation space and material.

[0012] In the areas of the rotor surface not covered by the guide vane, the coolant is carried radially outward, for example, by centrifugal force. Thus, the rotor surface is cooled, not necessarily a peripheral surface of the rotor. This is particularly advantageous for electrical machines where most of the heat is generated at the rotor surface, such as axial-flow machines.

[0013] For example, the guide plate guides the majority of the escaping coolant, in particular more than 90%, in particular more than 95%, from the first partial surface to the second partial surface. During operation of the electric machine, rotational forces carry the coolant outward, away from a rotational axis of the rotor, across the first partial surface. The guide plate holds the coolant to the rotor surface and guides it across the transition to the second partial surface. When the coolant reaches the outer edge of the rotor, it can, for example, be thrown off and fed into a cooling circuit.

[0014] In particular, the guide vane ensures that the majority of the rotor surface, in particular more than 80%, in particular more than 90%, and in particular more than 95%, is wetted with the coolant. This results in particularly effective and efficient cooling of the rotor, as the rotor can be cooled very well and, for example, with less coolant. This also offers the advantage that effective cooling is possible without the need for complex cooling channels in or on the rotor.

[0015] When referring to an axial or radial direction, this is always to be understood above and below in relation to the rotor's axis of rotation, unless otherwise stated. The coolant is, in particular, a lubricating oil for the bearings of the electric machine. Optionally, the coolant is a specific cooling oil.

[0016] If necessary, the coolant can be introduced into the rotor shaft and guided within the rotor shaft. It is possible for the coolant, particularly as lubricating oil, to pass through the bearings onto the first part of the rotor surface due to centrifugal force. However, it is also possible for the coolant outlet to be part of a spray device of a spray cooling system, which, in addition to the coolant outlet, has a coolant supply and a pump.

[0017] In one embodiment, the guide plate follows the shape of the rotor surface, particularly radially. This improves contact between the coolant, which is guided between the guide plate and the rotor surface, so that heat generated at the rotor is dissipated more effectively.

[0018] In one embodiment, the guide plate has a Z-shape in cross-section. The cross-section of the guide plate, and in particular also the cross-section of the rotor, therefore optionally forms a stepped shape. For example, internal angles of the Z-shape are equal, for example between 70° and 120°, in particular between 80 and 100°, in particular between 85° and 95°. The internal angles of the Z-shape are preferably rounded. However, it is also possible for the internal angles to have pointed edges. The guide plate is particularly advantageous in areas of the internal angles, since here the coolant may tend to leave the rotor surface without a guide plate. The guide plate guides a large part of the coolant along the rotor surface via the areas of the internal angles.

[0019] In one embodiment, the rotor has a plurality of Z-shaped stages in cross-section. The guide plate preferably extends radially across all stages. However, it is also possible for the rotor arrangement to have a plurality of radially spaced guide plates, each of which covers the areas of the interior angles.

[0020] In one embodiment, the guide plate has a catching part. The catching part is raised from the rotor surface in the axial direction. The axial distance from the first partial surface increases with decreasing radius with respect to the axis of rotation. The catching part is open towards the axis of rotation in order to catch the coolant. The catching part is a part of the guide plate arranged closest to the axis of rotation in the radial direction. In particular, the catching part is further away from the axis of rotation in the radial direction than the coolant outlet, since the coolant is carried radially outwards by the centrifugal forces.

[0021] In particular, the catch part is designed to be completely circumferential with respect to the axis of rotation in order to prevent the coolant from flowing past the outside of the catch part instead of between the catch part and the rotor surface.

[0022] In one embodiment, the catching part is funnel-shaped and / or truncated cone-shaped. This means, in particular, that the catching part protrudes from the first partial surface in the longitudinal section through the axis of rotation. This shape is particularly suitable for catching the coolant and guiding it further to the rotor surface due to its wide opening angle. In particular, the opening angle relative to the rotor surface is between 10° and 60°.

[0023] In one embodiment, the guide vane is segmented circumferentially with respect to the axis of rotation, particularly azimuthally. A first segment of the segmentation is attached directly to the rotor surface. This allows the guide vane to be attached to the rotor surface in a particularly stable manner.

[0024] In particular, the guide vane has a second segment arranged at a distance from the rotor surface. A distance between the second segment and the rotor surface may result from an axial height difference between the first segment and the second segment in the direction of the rotor surface. The coolant flows within this distance. Thus, the first segment also serves as a spacer.

[0025] It is possible for the guide plate to have additional first segments and / or additional second segments. Preferably, the first segments and the second segments are arranged such that the guide plate is balanced and, in particular, enables a particularly uniform coolant distribution. This is preferably achieved by a symmetrical arrangement of the first and second segments. In particular, at least two first segments and at least two second segments are arranged circumferentially, alternating symmetrically.

[0026] In one embodiment, the first segment is bonded to the rotor surface. Due to the surface-to-surface force transmission, a uniform distribution of forces is achieved across the entire bonded surface, in particular the entire first segment. Alternatively or additionally, the first segment is pressed and / or screwed to the rotor surface, for example.

[0027] In one embodiment, the guide plate is designed as a completely circumferential ring. In particular, the guide plate is designed as a completely circumferential, in particular azimuthally circumferential, ring, in particular as a single piece. For example, the guide plate can also be referred to as an oil guide ring. This results in the advantage that the coolant is distributed particularly evenly on the rotor surface circumferentially relative to the axis of rotation.

[0028] In one embodiment, the rotor arrangement comprises a sensor unit. A first sensor element of the sensor unit is arranged, in particular directly, on and / or in the guide plate. For example, the rotor or the guide plate is movable or rotatable relative to a second sensor element of the sensor arrangement. The sensor unit is designed, for example, as a speed, angle of rotation, or rotational position sensor. In particular, the sensor unit is configured to determine a speed and a position of the rotor.

[0029] Another aspect of the invention relates to an electric machine with a rotor arrangement. The electric machine is designed to drive a vehicle as part of an electric drive train.

[0030] In one embodiment, the electrical machine is designed as an axial flux machine.

[0031] In particular, the rotor arrangement is a rotor arrangement for an axial flux machine.

[0032] In an axial flux machine, the electrical machine is constructed axially, for example by sandwiching a stator disk between two rotor disks.

[0033] In particular, the stator disk is arranged on only one rotor disk. In the axial flux machine, the magnetic flux flows parallel to the rotor's axis of rotation. Therefore, the heat development in the axial flux machine on the rotor surface that is perpendicular to the axis of rotation is greater than in a radial flux machine. In a radial flux machine, more heat is generated on a lateral surface of the rotor. Therefore, the rotor arrangement according to the invention is particularly advantageous for axial flux machines. In particular, the rotor surface is a side of the rotor facing away from the stator. If there are two rotor disks, then in particular there are exactly two rotor surfaces, each located on a rotor disk.

[0034] In particular, the axial flux machine is a drive torque-providing component of an electric drive train, for example, of a motor vehicle. This means that the axial flux machine, also known as a disc rotor machine, can be used for a drive train of a motor vehicle, so that the motor vehicle can be driven, in particular purely electrically, by means of the axial flux machine. Thus, the axial flux machine is in particular a traction machine by means of which the motor vehicle can be driven, in particular purely electrically. The motor vehicle is thus, for example, a hybrid vehicle or an electric vehicle, in particular a battery electric vehicle (BEV).

[0035] In particular, the rotor arrangement according to the invention also makes it possible to cool a radial flux machine.

[0036] In one embodiment, the rotor comprises a first rotor disk and a second rotor disk, which are connected in a rotationally fixed manner via an axle, so that the rotor has an H-shape in longitudinal section. The guide plate is arranged at least on the first rotor disk. However, it is also possible for a guide plate to be arranged on both the first rotor disk and the second rotor disk.

[0037] For example, the respective rotor disk is a magnet carrier. This means in particular that respective magnets, in particular permanent magnets, can be held on the respective rotor disk, so that the respective magnets are carried by the respective rotor disk. The respective magnets can thus rotate with the respective rotor disk, on which the respective magnets are held, about the axis of rotation relative to the stator. Furthermore, it is conceivable that at least one or more coils are held on the stator. The coil can be energized. This means that an electric current can flow through the coil. Thus, for example, the stator carries the coil. In particular, the axial flux machine can have a housing, wherein the rotor disks can be rotated about the machine axis of rotation relative to the housing. In this case, it is provided in particular that the stator is fixed to the housing. This means that the stator is connected to the housing in a rotationally fixed manner.Since the stator is arranged between the rotor disks in the axial direction of the axial flux machine, the stator is also referred to as the central stator. In particular, by energizing the coil, i.e., by conducting an electric current through the coil(s), the rotor disks can be driven and thus rotated, in particular about the rotational axis, relative to the stator and preferably also relative to the housing.

[0038] Furthermore, it is preferably provided that a first air gap is arranged in the axial direction of the axial flux machine between the stator and a first of the rotor disks. Furthermore, it is preferably provided that a second air gap is arranged in the axial direction of the axial flux machine between the stator and a second of the rotor disks. In particular, the respective air gap can be at least substantially disk-shaped.

[0039] Further embodiments of the electrical machine according to the invention follow directly from the various embodiments of the rotor assembly according to the invention, and vice versa. In particular, individual features and corresponding explanations as well as advantages relating to the various embodiments of the rotor assembly according to the invention can be transferred analogously to corresponding embodiments of the electrical machine according to the invention, and vice versa.

[0040] Yet another aspect of the invention relates to a vehicle having an electric machine according to the invention. Embodiments of the electric machine may be embodiments of the vehicle.

[0041] Further advantages, features, and details of the invention will become apparent from the following description of preferred embodiments and from the drawings. The features and combinations of features mentioned above in the description, as well as the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures, can be used not only in the respective combinations specified, but also in other combinations or on their own, without departing from the scope of the invention.

[0042] Showing: Fig. 1 shows a partial schematic longitudinal sectional view of an axial flow machine with an embodiment of a rotor arrangement according to the invention; Fig. 2 shows a partial schematic longitudinal sectional view of an axial flow machine with an embodiment of a rotor arrangement according to the invention; Fig. 3 a schematic representation of an embodiment of a guide plate of a rotor arrangement according to the invention; Fig. 4 a schematic representation of an embodiment of a guide plate of a rotor arrangement according to the invention;

[0043] In the illustrations, identical elements or elements with the same function are identified by the same reference symbols.

[0044] Fig. 1 shows a detail of a schematic longitudinal sectional view of an exemplary embodiment of a rotor arrangement 1, in particular for an axial flux machine 2. The axial flux machine 2 can also be referred to as a disc rotor machine. In particular, the axial flux machine 2 is an axial flux machine for a motor vehicle. This means, for example, that the motor vehicle, preferably designed as a motor vehicle, in particular as a passenger car, can have the axial flux machine 2 in its fully manufactured state. The axial flux machine 2 is an electrical machine that can provide torque. In particular, vehicle wheels of an axle of the motor vehicle can be driven by means of the respective torque provided by the axial flux machine 2, whereby the motor vehicle can be driven, in particular purely electrically.

[0045] The axial flux machine 2 has a rotor 3 and a stator 4. The rotor 3 has, in particular, a first rotor disk 5 and a second rotor disk (not shown). The rotor disks 5 are rotatable, in particular jointly or simultaneously, relative to the stator 4 about a machine rotation axis, also simply referred to as the rotation axis A. In particular, the axial flux machine 2 can provide the aforementioned torques via the rotor 3. The rotation axis A is, for example, an axis of symmetry, with respect to which, for example, the respective rotor disk 5 and / or the stator 4 is rotationally symmetrical. In addition, the rotation axis A is also referred to as the rotation axis, since the rotor disks 5 and the rotation axis are rotatable relative to the stator 4. In particular, the stator 4 is arranged between the rotor disks 5 in the axial direction of the axial flux machine 2.

[0046] The rotor assembly 1 comprises the rotor 3 and a rotor shaft 6, which runs along the axis of rotation A of the rotor 3. The rotor shaft 6 has a coolant outlet 7. The coolant outlet 7 is arranged relative to a rotor surface 8 of the rotor 3 such that a coolant 9 can be guided from the coolant outlet 7 to the rotor surface 8. The coolant outlet 7 is, for example, a bearing of the rotor 3 through which the coolant 9 exits. The rotor 3 has the rotor surface 8, which can also be referred to as the rotor rear side, and a rotor outer surface 10. The rotor surface 8 has at least a first partial surface 11 along a first plane and a second partial surface 12 along a second plane. The first plane is different from the second plane. Optionally, the first partial surface 11 is radially closer to the axis of rotation A than the second partial surface 12. In particular, the first plane and the second plane are perpendicular to the axis of rotation A.The rotor surface 10 is optionally parallel to the rotational axis A. The rotor assembly 1 has a guide plate 13. The guide plate 13 is attached to the rotor 3. The guide plate 13 is shaped and arranged on the rotor 3 such that the coolant 9 can be guided from the first partial surface 11 to the second partial surface 12.

[0047] In particular, the rotor surface 8 has a particularly step-shaped transition 14 between the first partial surface 11 and the second partial surface 12. The transition 14 has, for example, a first bend 15 and a second bend 16, wherein the first bend 15 borders the first partial surface 11 and is radially closer to the axis of rotation A than the second bend, which borders the second partial surface 12. The first bend 15 and / or the second bend 16 can optionally be rounded or designed as an edge. Preferably, the guide plate 13, as in Fig. 1, at least the second bend 16. For example, the guide plate 13 is designed as a ring, which can also be referred to as an oil guide ring, the rotor surface 8 in a direction of rotation P ( Fig. 3) with respect to the axis of rotation A completely.

[0048] In one exemplary embodiment, the rotor assembly 1 comprises a sensor unit. A first sensor element 21 of the sensor unit is arranged, in particular directly, on and / or in the guide plate 13. For example, the rotor 3 or the guide plate 13 is movable or rotatable relative to a second sensor element 22 of the sensor assembly.

[0049] Fig. 2 shows a further embodiment of the rotor arrangement 1. In this embodiment, the guide plate 13 also covers the first bend 15 and the second bend 16. The guide plate 13 has, in particular, a catch part 17. For example, the catch part 17 completely covers the rotor surface 8 in the direction of rotation P. An opening remains radially around the axis of rotation A, into which opening the coolant 9 can be introduced. Due to the shape, in particular a truncated cone shape, of the catch part 17, the coolant 9, in particular the majority of the coolant 9, in particular more than 90% of the coolant 9, is caught and brought onto the rotor surface 8. An opening angle of the catch part 17 to the rotor surface 8 is less than 90°, in particular between 10° and 60°.A gap height 18 of the portion of the guide plate 13 that is not part of the catch part 17 is sufficient so that the coolant 9 is guided radially outward through this portion of the guide plate 13 by centrifugal forces prevailing during operation, leaves the guide plate 13, and is carried further outward by the centrifugal forces. At an outer edge of the rotor surface 8 or at the rotor surface 10, the coolant is thrown radially outward, in particular over the entire circumference of the rotor 3.

[0050] Fig. 3 shows an embodiment of the guide plate 13 as a plan view of a side of the guide plate 13 facing the rotor surface 8. For example, the guide plate 13 has first segments 19 and second segments 20. If appropriate, the first segments 19 are attached directly to the rotor surface 8, in particular glued. For example, the first segments 19 are raised relative to the second segments 20 in the direction of the rotor surface 8 by a height difference that corresponds in particular to the gap height 18. Preferably, the first segments 19 and the second segments 20 are arranged symmetrically with respect to the axis of rotation A.

[0051] Fig. 4 shows an embodiment of the guide plate 13 as a plan view of a side of the guide plate 13 facing away from the rotor surface 8. For example, the guide plate 13 has first sensor elements 21 on this side facing away from the rotor surface 8.

[0052] Preferably, the first sensor elements 21 are metal elements embedded in the guide plate 13, and the sensor unit is an inductive sensor. Alternatively or additionally, the sensor unit can be designed as an optical encoder and the first sensor elements 21 as colored markings. List of reference symbols 1 Rotor arrangement 2 axial flux machine 3 Rotor 4 Stator 5 Rotor disc 6 Rotor shaft 7 Coolant outlet 8 rotor area 9 Coolant 10 Rotor surface 11 First sub-area 12 Second sub-area 13 Baffle 14 Transition 15 First bend 16 Second bend 17 Catch part 18 gap height 19 First segment 20 Second Segment 21 First sensor element 22 Second sensor element QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2015 015 797 A1

[0003]

Claims

[1] Rotor arrangement (1) for an electrical machine, comprising a rotor (3) and a rotor shaft (6) which runs along an axis of rotation of the rotor (3), wherein the rotor shaft (6) has a coolant outlet (7) which is arranged with respect to a rotor surface (8) in such a way that a coolant (9) can be guided from the coolant outlet (7) to the rotor surface (8), wherein the rotor surface (8) has at least a first partial surface (11) along a first plane and a second partial surface (12) along a second plane, wherein the first plane is different from the second plane, characterized by a guide plate (13) which is fastened to the rotor (3), wherein the guide plate (13) is shaped and arranged on the rotor (3) in such a way that the coolant (9) can be guided from the first partial surface (11) to the second partial surface (12). [2] Rotor arrangement (1) according to claim 1, wherein the guide plate (13) follows a shape of the rotor surface (8). [3] Rotor arrangement (1) according to claim 1 or 2, wherein the guide plate (13) has a Z-shape in cross section. [4] Rotor arrangement (1) according to one of the preceding claims, wherein the guide plate (13) has a catch part (17), wherein the catch part (17): - is raised in the axial direction from the rotor surface (8), wherein an axial distance from the first partial surface (11) increases with decreasing radius with respect to the axis of rotation, - is open towards the axis of rotation, - a part of the guide plate (13) arranged closest to the axis of rotation in the radial direction, and - is further away from the axis of rotation in the radial direction than the coolant outlet (7). [5] Rotor arrangement (1) according to claim 4, wherein the catching part (17) is funnel-shaped. [6] Rotor arrangement (1) according to one of the preceding claims, wherein the guide plate (13) is circumferentially segmented with respect to the axis of rotation, wherein a first segment is attached directly to the rotor surface (8). [7] Rotor arrangement (1) according to one of the preceding claims, wherein the first segment is glued to the rotor surface (8). [8] Rotor arrangement (1) according to one of the preceding claims, wherein the guide plate (13) is designed as a completely circumferential ring. [9] Rotor arrangement (1) according to one of the preceding claims, wherein the rotor arrangement (1) has a sensor unit, wherein a first sensor element (21, 22) of the sensor unit is arranged, in particular directly, on and / or in the guide plate (13). [10] An electric machine having a rotor arrangement (1) according to any one of the preceding claims, wherein the electric machine is designed to drive a vehicle as part of an electric drive train.

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