Rotor and electric machine

Abstract

The invention relates to a rotor (4) comprising at least a first rotor body (5) having a first group of permanent magnets (6) and a second rotor body (7) having a second group of permanent magnets (8), wherein: the first rotor body (5) and the second rotor body (7) are rotatable relative to each other about a common axis of rotation (10) against the effect of a first torsional stiffness mechanism (9) by means of a mechanical field-weakening mechanism (11); the field-weakening mechanism (11) comprises a first lever element (60), which is pivotable about a fulcrum; the first rotor body (5) is couplable to a first lever portion (61) and the second rotor body (7) is couplable to a second lever portion (62) of the lever element (60) and the first lever portion (61) and the second lever portion (62) are located on opposing sides of the lever element (60) in the circumferential direction and the lever element (60) is pivotably located on the rotor shaft (16); the lever element (60)

Description

[0001] Rotor and electric machine

[0002] The present invention relates to a rotor for an electric machine, in particular for use within a drive train of a hybrid or fully electric motor vehicle, wherein the rotor has at least a first rotor body with a first group of permanent magnets and a second rotor body with a second group of permanent magnets, wherein the first rotor body and the second rotor body are rotatable relative to one another against the effect of a first torsional stiffness about a common axis of rotation by means of a mechanical field weakening mechanism, wherein the field weakening mechanism comprises a first lever element which is pivotable about a pivot point,wherein the first rotor body is coupled to a first lever portion and the second rotor body to a second lever portion of the lever element, and the first lever portion and the second lever portion are arranged on circumferentially opposite sides of the lever element, so that the first rotor body and the second rotor body can be rotated relative to one another by tilting the lever element for a desired adjustment of the mechanical field weakening mechanism. A rotor shaft is coupled coaxially within the first rotor body and the second rotor body via the lever element in a torque-transmitting manner to the first rotor body and the second rotor body, and the lever element is pivotably arranged on the rotor shaft. The lever element is mounted on a lever shaft so as to be rotatable relative to an annular lever carrier, which is positioned coaxially to the rotor shaft. The invention further relates to an electric machine.

[0003] Electric motors are increasingly being used to power motor vehicles as an alternative to internal combustion engines that run on fossil fuels. Considerable efforts have already been made to improve the everyday suitability of electric drives and to offer users the same driving comfort they are used to. A detailed description of an electric drive can be found in an article in the magazine ATZ, Year 113, May 2011, pages 360-365 by Erik Schneider, Frank Fickl, Bernd Cebulski and Jens Liebold, entitled: Highly Integrative and Flexible Electric Drive Unit for E-Vehicles, which arguably represents the closest state of the art. This article describes a drive unit for one axle of a vehicle which includes an electric motor arranged coaxially with a bevel gear differential. Such drive units are also referred to as e-axles or electrically operated drive trains.

[0004] During operation, electrical machines are subject to losses due to magnetization reversal, which are collectively referred to as iron losses, and which reduce the machine's efficiency. In mobile applications, a low efficiency of the electric machine means a reduced vehicle range or increased battery capacity requirements. Therefore, minimizing these iron losses is a constant goal, especially in mobile applications with purely electric drive systems.

[0005] An example of such an electrical machine with iron losses, which can be used within the drivetrain of a hybrid or fully electric motor vehicle, is the so-called permanent-magnet synchronous machine. Due to its high power density compared to other machine types, it is particularly popular in the field of electromobility, where the available installation space is often a limiting factor. The machine's excitation field is usually generated by permanent magnets arranged in the machine's rotor. Slip ring contact, which is necessary in electrically excited synchronous machines to supply current to an excitation coil arranged on the rotor, can be dispensed with in the permanent-magnet synchronous machine.

[0006] A disadvantage of permanent magnet excitation, however, is that the excitation field cannot be easily modified. In principle, a synchronous machine can be operated beyond its rated speed by controlling the so-called field weakening range. In this range, the machine operates at its maximum rated power, with the torque output by the machine reducing as the speed increases. Electrically excited synchronous machines can be operated very easily in the field weakening range by reducing the excitation current. Even with permanent magnet machines, there are known ways of generating an air gap field component by applying a suitable current to the stator of the machine. This air gap field component counteracts the excitation field generated by the permanent magnets and thus weakens it.However, such control of the machine causes increased losses, so that the machine can only be operated with reduced efficiency in this range.

[0007] An effective method for reducing iron losses in electrical machines is the targeted weakening of the magnetic field between the stator and rotor at high-speed operating points, since losses due to high-frequency remagnetization are lower in a weaker magnetic field. In addition to electrical methods, mechanical approaches also exist for targeted field weakening. From the patent specifications US58211710, FR2831345, EP1085644, EP11867030, DE1012011708670, DE1012016103470, CN104600929 and CN 105449969 a rotor of a radial flux machine is known which is divided perpendicular to the axis of rotation into several rotor disks equipped with permanent magnets and rotatable relative to one another, which rotor disks, depending on the relative rotation between the rotor disks, provides the full magnetic field in a position with the magnetic poles aligned in the axial direction and a weakened magnetic field in a position rotated relative to it.Active or passive mechanisms are described which claim to be able to switch between these two positions depending on the rotor speed or torque and thus enable more efficient operation of the electric machine across the entire engine characteristic map.

[0008] DE 10 12021 101 898 describes an arrangement in which the rotor of a radial flux machine is divided into two sub-rotors, whose individual rotor disks alternate in the axial direction. One sub-rotor is connected directly to the rotor shaft, while the other sub-rotor is connected to the rotor shaft in a torque-transmitting manner via a torsional stiffness. The torsional stiffness is selected such that at low torques, the sub-rotors are in a torsional position with a weakened magnetic field, and at high torques, the sub-rotors are in a torsional position with a full magnetic field. DE 10 12021 101 904 claims a structurally designed mechanical module that can be inserted into the interior of the permanent-magnet-equipped rotor disks, establishes the described connections between the sub-rotors and the rotor shaft, and allows an adjustment characteristic to be defined via the torsional stiffness, which is implemented using springs and roller-equipped cam gears.

[0009] All of the previously mentioned passive solutions, which use a torque as a sensor variable to trigger a relative rotation between two partial rotors against a torsional stiffness, assume that the total electromagnetic torque generated by the stator current in the case of the initially field-weakened position with non-aligned magnetic poles is simply distributed between the two partial rotors, roughly according to their share of the total length and their respective phase position to the stator field, regardless of the presence of the other partial rotor. Only then could a partial torque proportional to the total torque be readily directed against a torsional stiffness between the partial rotors or one of the partial rotors and the rotor shaft, and cause the desired rotation with increasing torque into the position with full magnetic field with aligned magnetic poles.However, tests and modelling by the applicant have shown that the actual circumstances are far more complicated.

[0010] Even in the de-energized state, interactions occur between the rotor disks of the two sub-rotors in the form of magnetic repulsion moments. The position with the full magnetic field and aligned magnetic poles represents a fragile equilibrium with a vanishing repulsion moment. As rotation begins from this equilibrium position, a repulsion moment arises that increases with increasing rotation until it reaches a maximum, before then decreasing again with further rotation. The progression of the repulsion moment over the angle of rotation within an electrical period, the height of the maximum, and the angle of rotation at which it occurs depend heavily on the chosen arrangement of the permanent magnets within the rotor disks. The progression over an electrical period is fundamentally non-linear.

[0011] In the case of the desired efficient stator current supply for different speeds, these magnetic repulsion moments increase in different ways, sometimes several times over, depending on the speed. Overall, the resulting partial moments are in no way suitable for simply counteracting the torsional rigidity between the partial rotors or one of the partial rotors and the rotor shaft, causing the partial rotors to rotate into the position with full magnetic field, since they are not directed in the correct direction due to the high proportion of magnetic repulsion moments.

[0012] For reliable adjustment behavior, it is necessary, among other things, that the adjustment characteristic of the mechanical field weakening neither changes undesirably nor exhibits excessive hysteresis over the engine map. However, at the speeds of today's traction motors in the automotive sector, centrifugal forces, particularly on the existing torsional stiffnesses, which can be designed as compression springs, cause an undesirably large shift in the adjustment characteristic toward higher torques. Increasing friction on guide elements of the torsional stiffnesses can also lead to excessive hysteresis in the adjustment characteristic.

[0013] In order to represent a functional arrangement in the sense of the aforementioned passive solutions for moment-adaptive field weakening of the rotor of an electrical machine, the object of the present invention is to provide a rotor and an electrical machine with improved mechanical field weakening.

[0014] This object is achieved by a rotor for an electric machine, in particular for use within a drive train of a hybrid or fully electric motor vehicle, wherein the rotor has at least a first rotor body with a first group of permanent magnets and a second rotor body with a second group of permanent magnets, wherein the first rotor body and the second rotor body are rotatable relative to one another against the effect of a first torsional stiffness about a common axis of rotation by means of a mechanical field weakening mechanism, wherein the field weakening mechanism comprises a first lever element which is pivotable about a pivot point,wherein the first rotor body is coupled to a first lever portion and the second rotor body to a second lever portion of the lever element, and the first lever portion and the second lever portion are arranged on circumferentially opposite sides of the lever element, so that the first rotor body and the second rotor body can be rotated relative to one another by tilting the lever element for a desired adjustment of the mechanical field weakening mechanism, wherein a rotor shaft can be coupled coaxially within the first rotor body and the second rotor body via the lever element in a torque-transmitting manner to the first rotor body and the second rotor body, and the lever element is pivotably arranged on the rotor shaft, wherein the lever element is mounted on a lever shaft rotatably relative to an annular lever carrier, which is positioned coaxially to the rotor shaft,wherein the lever element is rotatably mounted on the lever shaft via a rolling bearing.,

[0015] The advantageous effect of this design is that the bearing can be designed with particularly low friction, which also has a positive influence on the adjustment characteristic of the field weakening mechanism. In this context, a needle roller bearing is particularly preferred.

[0016] This provides the advantage of creating an electric machine with a purely mechanical field weakening device that reliably and cost-effectively adjusts the positions of permanent magnets within the rotor required for field weakening as required, depending on the operating conditions of torque and speed. The invention thus fundamentally eliminates the need for actuators that intervene externally on or in the rotor.

[0017] Furthermore, the hysteresis in the mechanical field weakening mechanism can be kept as low as possible by the rolling bearing.

[0018] The electric machine can, in particular, be designed as a rotary machine. In the case of electric machines designed as rotary machines, a distinction is made in particular between radial flux machines and axial flux machines. A radial flux machine is characterized by the fact that the magnetic field lines in the air gap formed between the rotor and stator extend in the radial direction, whereas in the case of an axial flux machine, the magnetic field lines in the air gap formed between the rotor and stator extend in the axial direction. In the context of this invention, it is possible for the electric machine to be configured as a radial flux machine or an axial flux machine.

[0019] A rotor is the rotating part of an electrical machine. The rotor comprises, in particular, a rotor shaft and one or more rotor bodies formed from rotor cores, arranged in a rotationally fixed manner on the rotor shaft. The rotor shaft can be hollow, which not only reduces weight but also allows the supply of lubricant or coolant to the rotor body.

[0020] For the purposes of the invention, a rotor body is understood to mean the rotor without a rotor shaft. The rotor body is therefore composed, in particular, of a rotor core and the permanent magnets incorporated into the pockets of the rotor core or fixed circumferentially to the rotor core, as well as any axial cover parts for closing the pockets. The permanent magnets can preferably be incorporated into the pockets of the rotor core. A single, larger rotor magnet designed as a bar magnet or several smaller permanent magnet elements can be provided per pocket.

[0021] The rotor has a plurality of rotor bodies. Particularly preferably, the rotor bodies are formed from substantially identical parts, in particular substantially identical. It is most preferred for the rotor bodies to be formed from identical, in particular substantially identical rotor laminations. The rotor bodies are therefore particularly preferably formed from a rotor lamination stack, which is composed of a plurality of laminated individual laminations or rotor laminations, generally made of electrical steel sheet, which are layered and stacked one on top of the other to form a stack, the so-called rotor lamination stack. The individual laminations can be held together in the rotor lamination stack by gluing, welding, or screwing. A rotor lamination stack can, in particular, also have permanent magnets introduced into the pockets of the rotor lamination stack or fixed circumferentially to the rotor lamination stack.

[0022] Mechanical field weakening mechanisms are generally known from the prior art. Particularly preferred mechanical field weakening mechanisms in connection with this invention are described in the as yet unpublished DE102022106944 and DE102022106945, as well as in the patent publications DE102021101904B3, DE102021101898A1, and DE102021101900A1, and are hereby incorporated by reference into the disclosure of this application.

[0023] According to an advantageous embodiment of the invention, it can be provided that the rolling bearing is designed as a needle bearing. The advantage of this embodiment is that the needle bearing allows a particularly compact field weakening mechanism to be provided. In this context, it is particularly preferred that the rolling bearing is lubricated and sealed. According to a further preferred development of the invention, it can also be provided that the lever element has a cam-like flange, the cam tip of which rests on the rotor shaft and which has a bearing receptacle in which the rolling bearing is arranged, wherein a first lever inlay and a second lever inlay are further fixedly attached to the cam-like flange, wherein the first lever inlay has the first lever section and the second lever inlay has the second lever section of the lever element.

[0024] This allows the field weakening mechanism to be designed particularly compactly in both the radial and axial directions. Furthermore, in this design variant, the inactive lever inlay can be controlled.

[0025] In a likewise preferred embodiment of the invention, it can also be provided that the first lever inlay and the second lever inlay are shaped essentially identically. This allows for a particularly cost-effective design of the rotor through an increased proportion of identical parts. It can also be advantageous to further develop the invention such that the first lever inlay and / or the second lever inlay are / is stamped from a single sheet metal, which can contribute to particularly cost-effective production of the lever inlays.

[0026] Furthermore, according to a likewise advantageous embodiment of the invention, it can be provided that the lever support is designed in two parts, with a first lever support ring and a second lever support ring, which can simplify the assembly of the field weakening mechanism. According to another particularly preferred embodiment of the invention, it can be provided that the first lever support ring and the second lever support ring are designed in essentially the same part, which can have a particularly positive effect on the manufacturing costs of the field weakening mechanism.

[0027] Furthermore, the invention can also be further developed such that the lever shaft is connected in a rotationally fixed manner to the first lever support ring and the second lever support ring. The advantage of this configuration is, in particular, that the lever shaft can be made comparatively short, thus achieving minimal deformation of the lever shaft under torque and at high speeds (up to 18,000 rpm).

[0028] In a likewise preferred embodiment variant of the invention, it can also be provided that the first lever inlay is connected to a first pin which is received in or on the cam-like flange and / or the second lever inlay is connected to a second pin which is received in or on the cam-like flange.

[0029] It is further preferred that the lever inlays be hardened. It is also preferable that the cam-like flange be formed from an unhardened metallic material.

[0030] At the same time, it may be advantageous to further develop the invention such that the cam-like flange has a connecting section extending radially above the bearing mount, against which the first lever inlay and the second lever inlay are supported. Overall, this allows for a cost-effective connection of the lever inlays to the flange and a compact field weakening mechanism.

[0031] According to a further preferred embodiment of the subject matter of the invention, the connecting section can be arranged axially centrally to the axial extension of the rolling bearing. This ensures that the rolling bearing is evenly loaded, which can contribute to an improved bearing service life.

[0032] Finally, the object of the invention can also be achieved by an electrical machine comprising a rotor according to one of claims 1-9.

[0033] The invention will be explained in more detail below with reference to figures without limiting the general inventive concept. It shows:

[0034] Figure 1 shows an electrical machine in a cross-sectional view,

[0035] Figure 2 is a schematic block diagram of a rotor with a mechanical field weakening mechanism,

[0036] Figure 3 shows a rotor with a mechanical field weakening mechanism in an axial section view,

[0037] Figure 4 Lever carrier with lever elements in a perspective view,

[0038] Figure 5 Lever carrier with lever elements in an exploded view,

[0039] Figure 6 Lever element in an exploded view,

[0040] Figure 7 Lever element in a perspective view.

[0041] Figure 1 shows an electric machine 1, in particular for use within a drive train of a hybrid or fully electric motor vehicle. Configured as a radial flux machine, the electric machine 1 comprises a stator 2 and a rotor 4 separated from the stator 2 by an air gap 3. The rotor 4 has at least a first rotor body 5 with a first group of permanent magnets 6 and a second rotor body 7 with a second group of permanent magnets 8, which can be clearly seen from the combination of Figure 1 and Figure 2.

[0042] The first rotor body 5 and the second rotor body 7 are rotatable relative to each other about a common rotational axis 10 by means of a mechanical field weakening mechanism 11, counter to the effect of a first torsional stiffness 9. The two rotor bodies 5, 7 are formed essentially from identical rotor laminations, with the position and number of permanent magnets 6 of the first group and the number of permanent magnets 8 of the second group in the rotor bodies 5, 7 being identical.

[0043] The field weakening mechanism 11 shown as an example in Figure 2 comprises a lever element (not further identified) that can be pivoted about a pivot point, wherein the first rotor body 5 can be coupled to a first lever section and the second rotor body 7 can be coupled to a second lever section of the lever element. The first lever section and the second lever section are arranged on opposite sides of the lever, so that the first rotor body 5 and the second rotor body 7 can be rotated relative to one another by tilting the lever element for a desired adjustment of the mechanical field weakening mechanism 11. This field weakening mechanism 11 is described in detail in DE102022106944 and DE102022106945, so that reference is made here to these documents to avoid repetition.

[0044] As already indicated in Figure 1, the rotor bodies 5, 7 are each constructed in two parts, comprising an inner annular disc 28 connected to a rotor shaft 16 in a torque-transmitting manner, and an outer annular disc 29 coupled to the inner annular disc 28 in a torque-transmitting manner. The permanent magnets 6, 8 are arranged only in the outer annular disc 29 formed from an electrical sheet. The inner annular disc 28 is made of a steel, in particular a hardened steel.

[0045] Figure 3 shows a rotor 4 according to the invention for an electrical machine 1, wherein the rotor 4 has at least a first rotor body 5 with a first group of permanent magnets 6 and a second rotor body 7 with a second group of permanent magnets 8. The first rotor body 5 and the second rotor body 7 can be rotated relative to one another about a common axis of rotation 10 by means of a mechanical field weakening mechanism 11, counter to the effect of a first torsional stiffness 9 - which is not shown in Figure 3.The field weakening mechanism 11 comprises a first lever element 60 that can be pivoted about a pivot point, wherein the first rotor body 5 can be coupled to a first lever section 61 and the second rotor body 7 can be coupled to a second lever section 62 of the lever element 60. The first lever section 61 and the second lever section 62 are arranged on circumferentially opposite sides of the lever element 60, so that the first rotor body 5 and the second rotor body 7 can be rotated relative to one another by tilting the lever element 60 for a desired adjustment of the mechanical field weakening mechanism 11. As a result, the lever element 60 can then be coupled to the two rotor bodies 5, 6 in one direction of rotation each.

[0046] Coaxially within the first rotor body 5 and the second rotor body 7, a rotor shaft 16 can be coupled to the first rotor body 5 and the second rotor body 7 via the lever element 60 in a torque-transmitting manner. The lever element 60 is pivotally mounted on the rotor shaft 16, wherein the lever element 60 is rotatably mounted on a lever shaft 63 relative to an annular lever carrier 64, which is positioned coaxially to the rotor shaft 16. The lever carrier is shown in isolated views in Figures 4-5 and is explained in more detail below.

[0047] The lever element 60 is rotatably mounted on the lever shaft 63 via a roller bearing 90 designed as a needle bearing. To further minimize hysteresis in the field weakening mechanism 11, the use of lubricated and sealed needle bearings is advantageous. By using the combination of the flange 91 and the lever inlays 94, 95 arranged on it, the lever element 60 can be designed to save space despite the use of the roller bearing 90, since only one axial plane with the corresponding lever inlays 94, 95 is required. Furthermore, a uniform pressure distribution on the roller bearing 90 is ensured, since the flange 91, the lever inlays 94, 95, and the connecting section 101 are located essentially centrally above the roller bearing 90.The lever element is thus rotatably mounted on the lever shaft 63 via the rolling bearing 90 relative to the annular lever support 64, which is positioned coaxially to the rotor shaft 16 and can be coupled to the two rotor bodies 5, 7 in one direction of rotation each.

[0048] The lever inlays 94,95, which are each responsible for the pulling or pushing torque, are located on the same lever shaft 63 and are both connected to the same flange 91, whereby the lever inlay 94,95, which is inactive for one operating mode (pulling / pushing), can always be well controlled.

[0049] In the embodiment shown in Figures 4-5, the lever system comprises a total of four lever elements 60 arranged equidistantly around the circumference of the lever support 64. In total, this embodiment comprises two lever support rings 96, 97, four roller bearings 90, four lever shafts 63, four flanges 91, and eight lever inlays 94, 95.

[0050] The lever element 60 can be assembled as follows, which is particularly easy to understand from the illustration in Figure 5. The roller bearings 90 are each pressed into one of the flanges 91. The lever inlays 94, 95 are each connected to the flange 91 with a pin 99, 100. The flange 91 with the roller bearing 90 and the lever inlays 94, 95 is then pulled onto the lever shaft 63. The lever shaft 63 is then pressed into the two lever support rings 96, 97 on both sides, so that the lever shaft 63 is rotationally connected to the first lever support ring 96 and the second lever support ring 97.

[0051] The lever support 64 is thus constructed in two parts, with a first lever support ring 96 and a second lever support ring 97. With the help of the two lever support rings 96, 97, the deformation of the lever shaft 63 under torque and at high speeds can be minimized. The first lever support ring 96 and the second lever support ring 97 are constructed essentially in the same part. As can be clearly seen in Figure 7, the lever element 60 has a cam-like flange 91, the cam tip 92 of which rests against the rotor shaft 16 and which has a hollow cylindrical bearing receptacle 93 in which the rolling bearing 90 is arranged. Furthermore, a first lever inlay 94 and a second lever inlay 95 are firmly attached to the cam-like flange 91, the first lever inlay 94 comprising the first lever section 61 and the second lever inlay 95 comprising the second lever section 62 of the lever element 60.

[0052] As can be clearly seen in Figure 6, the first lever inlay 94 is connected to a first pin 99, which is received in or on the cam-like flange 91. Similarly, the second lever inlay 95 is also connected to a second pin 100, which is received in or on the cam-like flange 91.

[0053] The cam-like flange 91 has a connecting section 101 extending radially above the bearing mount 93, to which the first lever inlay 94 and the second lever inlay 95 are firmly attached via the pins 99, 100 and an inner contour that is positively connected to the outer diameter of the bearing. To accommodate the pins 99, 100, the connecting section 101 has corresponding openings into which the pins 99, 100 are received.

[0054] Figure 7 shows that the connecting section 101 is arranged axially centrally to the axial extension of the rolling bearing 90.

[0055] The invention is not limited to the embodiments illustrated in the figures. The above description is therefore not to be considered restrictive, but rather explanatory. The following claims are to be understood as meaning that a stated feature is present in at least one embodiment of the invention. This does not exclude the presence of further features. Where the claims and the above description define 'first' and 'second' features, this designation serves to distinguish between two similar features without establishing a priority. List of reference symbols

[0056] 1 electric machine

[0057] 2 Stator

[0058] 3 Air gap

[0059] 4 Rotor

[0060] 5 rotor body

[0061] 6 permanent magnets

[0062] 7 Rotor body

[0063] 8 permanent magnets

[0064] 9 Torsional stiffness

[0065] 10 axis of rotation

[0066] 11 Field weakening mechanism

[0067] 16 Rotor shaft

[0068] 28 Ring disc

[0069] 29 Ring disc

[0070] 60 lever element

[0071] 61 Lever section

[0072] 62 lever section

[0073] 63 Lever shaft

[0074] 64 lever carriers

[0075] 90 rolling bearings

[0076] 91 flange

[0077] 92 cam tip

[0078] 93 Stocktake

[0079] 94 lever inlay

[0080] 95 lever inlay

[0081] 96 lever support ring

[0082] 97 Lever support ring pin pin connection section

Claims

Claims 1. Rotor (4) for an electric machine (1), in particular for use within a drive train of a hybrid- or fully electric-powered motor vehicle, wherein the rotor (4) has at least a first rotor body (5) with a first group of permanent magnets (6) and a second rotor body (7) with a second group of permanent magnets (8), wherein the first rotor body (5) and the second rotor body (7) are rotatable relative to one another against the effect of a first torsional stiffness (9) about a common axis of rotation (10) by means of a mechanical field weakening mechanism (11), wherein the field weakening mechanism (11) comprises a first lever element (60) which is pivotable about a pivot point,wherein the first rotor body (5) is coupled to a first lever section (61) and the second rotor body (7) is coupled to a second lever section (62) of the lever element (60), and the first lever section (61) and the second lever section (62) are arranged on circumferentially opposite sides of the lever element (60), so that the first rotor body (5) and the second rotor body (7) can be rotated relative to one another in a targeted manner by tilting the lever element (60) for a desired adjustment of the mechanical field weakening mechanism (11), wherein a rotor shaft (16) is coaxially coupled to the first rotor body (5) and the second rotor body (7) via the lever element (60) in a torque-transmitting manner, and the lever element (60) is pivotably arranged on the rotor shaft (16), wherein the lever element (60) is mounted on a lever shaft (63) is rotatably mounted relative to an annular lever support (64),which is positioned coaxially to the rotor shaft (16), characterized in that, the lever element (60) is rotatably mounted on the lever shaft (63) via a rolling bearing (90).

2. Rotor (4) according to claim 1, characterized in that the rolling bearing (90) is designed as a needle bearing.

3. Rotor (4) according to claim 1 or 2, characterized in that the lever element (60) has a cam-like flange (91), the cam tip (92) of which rests on the rotor shaft (16) and which has a bearing receptacle (93) in which the rolling bearing (90) is arranged, wherein a first lever inlay (94) and a second lever inlay (95) are further fixedly attached to the cam-like flange (91), wherein the first lever inlay (94) has the first lever section (61) and the second lever inlay (95) has the second lever section (62) of the lever element (60).

4. Rotor (4) according to one of the preceding claims, characterized in that the lever carrier (64) is designed in two parts with a first lever carrier ring (96) and a second lever carrier ring (97).

5. Rotor (4) according to one of the preceding claims, characterized in that the first lever support ring (96) and the second lever support ring (97) are designed essentially in the same part.

6. Rotor (4) according to claim 5, characterized in that the lever shaft (63) is rotationally connected to the first lever support ring (96) and the second lever support ring (97).

7. Rotor (4) according to one of the preceding claims, characterized in that the first lever inlay (94) is connected to a first pin (99) which is received in or on the cam-like flange (91) and / or the second lever inlay (95) is connected to a second pin (100) which is received in or on the cam-like flange (91).

8. Rotor (4) according to one of the preceding claims 3-6, characterized in that the cam-like flange (91) has a connecting section (101) extending radially above the bearing holder (93), to which the first lever inlay (94) and the second lever inlay (95) are firmly attached.

9. Rotor (4) according to claim 8, characterized in that the connecting section (101) is arranged axially centrally to the axial extension of the rolling bearing (90).

10. Electrical machine (1) comprising a rotor (4) according to one of the preceding claims.

Images