Rotor and electric machine

Abstract

The invention relates to a rotor (4) of an electric machine (1), in particular for use within a drivetrain of a hybrid or all-electric motor vehicle. The rotor (4) has at least one 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) can be rotated relative to each other about a common rotational axis (10) against the effect of a first torsional stiffness mechanism (9) by means of a mechanical field-attenuation mechanism (11); each rotor body (5, 7) has a two-part design and comprises an inner ring gear (28) that is torque-transmittingly connected to a rotor shaft (16) and an outer ring gear (29) that is torque-transmittingly connected to the inner ring gear (28); and the permanent magnets (6, 8) are located only in the outer ring gear (29) that is made from an electrical sheet steel.

Description

[0001] Rotor and electric machine

[0002] The present invention relates to a rotor of an electric machine, in particular for use within a drive train of a hybrid or fully electric motor vehicle. The rotor comprises 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. The first rotor body and the second rotor body are rotatable relative to one another about a common axis of rotation by means of a mechanical field weakening mechanism, counter to the effect of a first torsional stiffness. The invention further relates to an electric machine.

[0003] Electric motors are increasingly being used to power motor vehicles, creating alternatives to combustion engines that require fossil fuels. Considerable efforts have already been made to improve the everyday suitability of electric drives and also to provide users with the same level of driving comfort they are accustomed to.

[0004] A detailed description of an electric drive can be found in an article in the magazine ATZ, Volume 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 a vehicle axle that includes an electric motor arranged coaxially with a bevel gear differential. Such drive units are also referred to as e-axles or electrically operated drivetrains.

[0005] 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.

[0006] 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.

[0007] 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.

[0008] 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.

[0009] DE 102021 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.

[0010] All of the previously mentioned passive solutions, which use a torque as a sensor variable to trigger a relative rotation between two sub-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 sub-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 sub-rotor. Only then could a partial torque proportional to the total torque be readily directed against a torsional stiffness between the sub-rotors or one of the sub-rotors and the rotor shaft, and cause the desired rotation with increasing torque into the position with full magnetic field and aligned magnetic poles.However, tests and modelling by the applicant have shown that the actual circumstances are far more complicated.

[0011] 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.

[0012] 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.

[0013] For reliable adjustment behavior, it is necessary, among other things, that the adjustment characteristic of the mechanical field weakening does not change undesirably over the engine map or exhibit excessive hysteresis. However, at the speeds of today's traction motors in the automotive sector, an undesirably large shift in the adjustment characteristic toward higher torques can be observed due to centrifugal force. The increasing friction between components of a mechanical field weakening mechanism at high speeds can also lead to excessive hysteresis in the adjustment characteristic.

[0014] To provide the space required for such a mechanical field weakening mechanism between the rotor shaft and the outer ring of the rotor, where the pockets for the permanent magnets are located, corresponding recesses are typically provided in the rotor's electrical laminations. However, these recesses weaken the remaining cross-section and thus reduce the speed stability of the rotor disks. This leads to an undesirable reduction in the power density of the electric motor.

[0015] In order to represent a functional arrangement in the sense of the aforementioned passive solutions for torque-adaptive field weakening of the rotor of an electrical machine, the object of the present invention is to provide a rotor which provides improved mechanical field weakening, particularly at high speeds.

[0016] This object is achieved by a rotor of an electric machine, in particular for use within a drive train of a hybrid or fully electrically powered 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 rotor bodies are each constructed in two parts, comprising an inner annular disc connected to a rotor shaft in a torque-transmitting manner and an outer annular disc coupled to the inner annular disc in a torque-transmitting manner, wherein the permanent magnets are arranged only in the outer annular disc formed from an electrical sheet.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] According to the invention, the rotor bodies are constructed in two parts, with an inner annular disk and an outer annular disk. The inner annular disk begins radially far enough inward relative to the magnetic pockets containing the permanent magnets that it is essentially outside the magnetic flux and does not need to be made of electrical steel. Therefore, it can be made of high-strength (hardened) steel, for example, and can also accommodate and support the components for mechanical field weakening.

[0018] The connection between the inner annular disc and the outer annular disc can be positively connected, materially connected, and / or non-positively connected. Preferably, the inner annular disc is formed from a material different from a rotor lamination. Further preferably, the inner annular disc is formed from a material that has a higher strength than the electrical sheet of the outer annular disc.

[0019] The electrical machine can in particular be designed as a rotary machine. In the case of electrical 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 in 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 electrical machine to be configured as a radial flux machine or an axial flux machine. A rotor is the rotating (rotating) part of an electrical machine. The rotor comprises in particular a rotor shaft and one or more rotor bodies formed from rotor laminated cores which are arranged rotatably on the rotor shaft.The rotor shaft can be hollow, which on the one hand results in weight savings and on the other hand 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 the 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.

[0021] 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.

[0022] The rotor has a plurality of rotor bodies. Particularly preferably, the rotor bodies are formed from substantially the same part, in particular substantially identical. It is most preferred for the rotor bodies to be formed from substantially the same part, 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, screwing, or clinching. 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.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, the inner annular disk can be made of steel, in particular hardened steel. The advantage of this embodiment is that the use of steel can contribute to a higher speed load capacity of the rotor and a longer service life of the electrical machine. A (hardened) steel is also better able to withstand high temperatures and mechanical stress, which can further improve the reliability and service life of the electrical machine. The high heat resistance of steel can also contribute to increasing the thermal load capacity of the rotor and thus permit its use in high-temperature applications.

[0024] According to a further preferred development of the invention, it can also be provided that the inner annular disk and the outer annular disk are positively connected to one another in a torque-transmitting manner. This makes it possible to use a connection method that is generally more stable and resistant to wear and vibrations than other connection methods, which increases the reliability and service life of the rotor. A positive connection can also bring advantages in terms of assembly, since a positive connection is usually easier to produce than, for example, welding the two annular disks. It is particularly preferred to design the positive connection without play in the circumferential direction in order to avoid play-related shock-like mechanical loads during operation of the rotor.

[0025] Furthermore, according to a likewise advantageous embodiment of the invention, it can be provided that the inner annular disc has external teeth on its outer surface, which engage with corresponding internal teeth on an inner surface of the outer annular disc. The technical advantage when the inner annular disc of the rotor of an electrical machine has external teeth on its outer surface, which engage with corresponding internal teeth on an inner surface of the outer annular disc, lies in particularly high connection rigidity and torque transmission efficiency. Advantages can also be realized with regard to the thermal load capacity of the rotor, since the teeth can improve heat dissipation and thus increase the thermal load capacity of the rotor.

[0026] According to another particularly preferred embodiment of the invention, the external gearing and the internal gearing can be designed as spline gearing. This allows for particularly simple assembly and disassembly of the ring discs. A spline gearing allows the two ring discs to be easily plugged together and separated without the need to loosen or unscrew the connection. This facilitates the maintenance and servicing of the rotor and enables faster and more efficient performance of these tasks. A spline gearing also allows for faster and easier replacement of the rotor bodies if they are damaged or defective.

[0027] Furthermore, the invention can also be further developed such that a plurality of the teeth of the external toothing each have a first undercut, and a plurality of the teeth of the internal toothing each have a second undercut, wherein the first undercut and the second undercut are designed such that a force can be transmitted in the radial direction between the meshing internal toothing and external toothing. Such a toothing therefore has undercuts so that not only can the torque be transmitted from the electrical sheets of the outer ring disk to the inner ring disk, but the radially directed centrifugal forces that act on the electrical sheets of the outer ring disk at high speeds are also absorbed.In a likewise preferred embodiment variant of the invention, it can also be provided that the majority of the teeth of the external toothing and / or the majority of the teeth of the internal toothing are shaped in a dovetail manner in cross-section, which has proven to be particularly advantageous for the transmission of circumferential and radial forces.

[0028] It may also be advantageous to further develop the invention such that the external toothing has a groove with a groove base between two circumferentially adjacent teeth, into which groove base a tooth of the internal toothing engages with a tooth tip, wherein the tooth tip has play relative to the groove base. This ensures, among other things, that the two annular disks only touch on the oblique flanks of the teeth, which may for example be dovetail-shaped. The high accuracy of the tooth shape for a positive connection is thus limited to the oblique flanks. In addition, the radial play can be used to heat the inner annular disk before assembly to such an extent that the teeth have play all around when the outer annular disk is assembled, and the desired play-free contact, for example on the oblique flanks of the dovetail-shaped teeth, only occurs upon cooling.This also makes it possible to preload the outer ring disc radially inwards during assembly if a corresponding overlap is provided between the oblique flanks of the dovetail-shaped teeth of the external and internal gearing.

[0029] According to a further preferred embodiment of the subject matter of the invention, the external toothing and / or the internal toothing can be provided with a chamfer. This can facilitate joining or axial insertion of the annular discs into one another.

[0030] Finally, the invention can also be advantageously designed such that the permanent magnets are arranged in pairs in a V-shape in cross section distributed over the circumference of an outer annular disc, wherein the free legs of the V-shaped arrangement extend radially inwards, and the V-shaped arrangement has a radially extending mirror axis which runs coaxially to a radially extending mirror axis of a tooth of the internal toothing or external toothing and / or the permanent magnets are arranged in pairs in a V-shape in cross section distributed over the circumference of an outer annular disc, wherein the free legs of the V-shaped arrangement extend radially inwards, and between two circumferentially adjacent V-shaped arrangements a radially extending mirror axis is defined which runs coaxially to a radially extending mirror axis of a tooth of the internal toothing or external toothing.It has been shown that such an arrangement of teeth to permanent magnets can contribute to a particularly advantageous and high torsional strength of the connection between the inner and outer ring disc.

[0031] The object of the invention is further achieved by an electrical machine comprising a stator and a rotor separated from the stator by an air gap, wherein the rotor is designed according to one of claims 1-10.

[0032] The object of the invention is also achieved by a kit of parts for producing a mechanical field weakening mechanism for a rotor of an electric machine, in particular for use within a drive train of a hybrid or fully electric motor vehicle, comprising

[0033] • a first rotor body with a first receiving pocket and a second rotor body, wherein the first rotor body and the second rotor body are rotatable relative to each other about a common axis of rotation against the effect of a first torsional stiffness,

[0034] • a first torsional stiffness, which is designed as a first leg spring arrangement with a first leg spring, which is coaxial to the axis of rotation and can be positioned between the first rotor body and the second rotor body or between one of the rotor bodies and a rotor shaft, such that the rotation of one of the rotor bodies which begins when the field weakening mechanism is adjusted can cause an opening or closing actuation of the first leg spring, and the first leg spring has at least one first spring leg,

[0035] • a first receiving shoe in which the first spring leg can be positioned and the receiving shoe can in turn be received in the first receiving pocket of the first rotor body and can be fixed to the first rotor body in such a way that the first spring leg of the first leg spring can be coupled to the first rotor body in the axial and circumferential directions without play relative to the first rotor body.

[0036] One advantage of the kit of parts is that it offers a simple and flexible solution for the manufacture and assembly of a mechanical field weakening mechanism. Using preconfigured and pre-assembled parts makes installation and maintenance easier and faster. The kit of parts is also more flexible and adaptable to different applications and vehicle types. It can also reduce costs by simplifying the supply chain and reducing inventory levels. The kit of parts can, for example, be a single packaging unit. Furthermore, it is possible to design the kit of parts as a collection of separate storage containers for storing the individual components or the respective component groups of the kit of parts.

[0037] The invention will be explained in more detail below with reference to figures without limiting the general inventive concept.

[0038] It shows:

[0039] Figure 1 shows an electrical machine in a cross-sectional view,

[0040] Figure 2 is a schematic block diagram of a rotor with a mechanical field weakening mechanism, Figure 3 is a rotor in a cross-sectional view,

[0041] Figure 4 shows a detailed view of the rotor in a cross-sectional view,

[0042] Figure 5 shows a first embodiment of a leg spring arrangement with two rotor bodies in a perspective exploded view,

[0043] Figure 6 shows a first embodiment of a leg spring arrangement with two rotor bodies in an assembled state in a perspective view,

[0044] Figure 7 shows a rotor body with a leg spring arrangement on it in a detailed enlarged section,

[0045] Figure 8 shows a kit of parts in a schematic representation.

[0046] 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.

[0047] The first rotor body 5 and the second rotor body 7 are rotatable 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. The two rotor bodies 5, 7 are formed essentially from identical rotor laminations, wherein the position and number of the permanent magnets 6 of the first group and the number of permanent magnets 8 of the second group in the rotor bodies 5, 7 are identical. The field weakening mechanism 11 shown as an example in Figure 2 comprises a lever element (not further designated) 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 each other 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 reference is made here to avoid repetition.

[0048] 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.

[0049] Figure 3 shows an embodiment in which the inner annular disc 28 and the outer annular disc 29 are positively connected to one another in a torque-transmitting manner. For this purpose, the inner annular disc 28 has an external toothing 51 on its outer circumferential surface 50, which engages with a corresponding internal toothing 52 on an inner circumferential surface 53 of the outer annular disc 29. In this exemplary embodiment, the external toothing 51 and the internal toothing 52 are designed as plug-in toothing. To facilitate the joining of this plug-in toothing, the external toothing 51 and / or the internal toothing 52 can have a chamfer.

[0050] From the detailed illustration in Figure 4, it can be seen that the teeth 54 of the external toothing 51 each have a first undercut 55. The teeth 56 of the internal toothing 52 also have a second undercut 57, wherein the first undercut 55 and the second undercut 57 are designed such that a force can be transmitted in the radial direction between the meshing internal toothing 52 and external toothing 51. To achieve this, the teeth 54 of the external toothing 51 and the teeth 56 of the internal toothing 52 have a dovetail shape in cross-section. The two annular disks 28, 29 only touch on the oblique flanks of the dovetail-shaped teeth 54, 56. The high accuracy of the tooth shape for a positive connection is therefore limited to the oblique flanks. In addition, larger radii can be used in the tooth base of the ring disks 28,29.This reduces local stresses and enables faster, more cost-effective production of the gears 51, 52, e.g., by selecting a milling cutter with a larger diameter. The undercut 55, 57 is thus created by the inclined lateral flanks of the teeth 54, 56. With this shape, the openings of the tooth gaps in the annular discs 28, 29 are wider, which enables simpler and more cost-effective production of the gears, e.g., by broaching, shaping, or milling.

[0051] The external toothing 51 further comprises, between each pair of circumferentially adjacent teeth 54, a groove 58 having a groove base 59 into which a tooth 56 of the internal toothing 52 engages with a tooth tip 60, wherein the tooth tip 60 has a clearance relative to the groove base 59, which can be clearly seen from the gap shown in Figure 4. With this design, an overlap can be deliberately provided in the tooth flanks of the meshing teeth 54, 56, which, during assembly, leads to an inward preload of the inner annular disc 28 with the outer annular disc 29 and thus further reduces the stresses in the annular discs 28, 29 under rotational speed.

[0052] The permanent magnets 6, 8 are arranged in pairs in a V-shape in cross-section distributed over the circumference of an outer annular disk 29, wherein the free legs 61 of the V-shaped arrangement extend radially inward, and the V-shaped arrangement has a radially extending mirror axis 62 which runs coaxially to a radially extending mirror axis 63 of a tooth 54, 56 of the internal toothing 52 or external toothing 51. At the same time, between two circumferentially adjacent V-shaped arrangements, a radially extending mirror axis 64 is defined, which runs coaxially to a radially extending mirror axis 65 of a tooth 56 of the internal toothing 52 or external toothing 51.In this context, it is also clearly evident from Figure 4 that the meshing teeth 54 of the external toothing 51, through which the mirror axes 62, 63 extend, are wider in the circumferential direction than the circumferentially adjacent teeth 54 of the external toothing 51. The same applies to the meshing teeth 56 of the internal toothing 52, through which the mirror axes 64, 65 extend. This allows the high centrifugal forces caused in these areas by the V-shaped arrangement of the permanent magnets 6, 8 to be better absorbed.

[0053] The first rotor body 5 and the second rotor body 7 are rotatable 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. This is explained in more detail below with reference to Figure 5. As can be seen from Figure 5, the first torsional stiffness 9 is designed as a first leg spring arrangement 12 with a first leg spring 13, which is arranged coaxially to the axis of rotation 10 and between the first rotor body 5 and the second rotor body 7 in such a way that the rotation of one of the rotor bodies 5, 7 that occurs when the field weakening mechanism 11 is adjusted causes the first leg spring 13 to open or close. Even if it is not shown in the figures, it is nevertheless possible for the first leg spring 13 to be arranged between one of the rotor bodies 5, 7 and the rotor shaft 16 in a torque-transmitting manner.

[0054] The first leg spring arrangement 12 has a second leg spring 14, which is arranged coaxially to the axis of rotation 10 of the rotor 4 and between the first rotor body 5 and the second rotor body 7 in such a way that the rotation of one of the rotor bodies 5, 7 that occurs when the field weakening mechanism 11 is adjusted causes the second leg spring 14 to open or close. As shown in Figures 5 and 7, the first leg spring 13 and the second leg spring 14 are essentially of the same construction and are arranged rotated relative to one another about the axis of rotation 10, so that the first spring leg 17 and the second spring leg 18 of the first leg spring 13 point radially outwards, offset by 90° in the circumferential direction, and the first spring leg 19 and the second spring leg 20 of the second leg spring 14 are also oriented radially outwards, offset by 90° in the circumferential direction.

[0055] Here, the first leg spring 13 has a first spring leg 17 extending radially into the first rotor body 5 and a second spring leg 18 extending radially into the second rotor body 7. Analogously, the second leg spring 14 also has a first spring leg 19 extending radially into the first rotor body 5 and a second spring leg 20 extending radially into the second rotor body 7.

[0056] The first spring leg 17 of the first leg spring 13 is held in a first receiving shoe 30, which in turn is received in a first receiving pocket 31 of the first rotor body 5 and fixed to the first rotor body 5 such that the first spring leg 17 of the first leg spring 13 is coupled to the first rotor body 5 without play in both the axial and circumferential directions. The first receiving shoe 30 can be inserted into the first receiving pocket 31 with some play.

[0057] Figure 5 further shows that the first receiving shoe 30 has a first receiving groove 32, in which the first spring leg 17 of the first leg spring 13 is arranged without play, for example by a press fit. The first spring leg 17 of the first leg spring 13 protrudes from the first receiving groove 32, with the section 33 protruding from the first receiving groove 32 resting against a wall 34 of the first receiving pocket 31, which can also be clearly seen when viewed together with Figure 7. In this way, part of the shoe load can be absorbed by the rotor body 5. The wall 34 of the first receiving pocket 31 has a convex contour protruding into the first receiving pocket 31, which can also be clearly seen from the detailed illustration in Figure 7. This can ensure, for example, that the position of the spring leg 17 can also be adjusted in the direction of rotation.Figure 5 further shows that the first receiving shoe 30 has a first opening 35 through which a first fastening means 36 passes, by means of which the first receiving shoe 30 is fixed to the first rotor body 5.

[0058] Figure 5 also shows that the second spring leg 18 of the first leg spring 13 is held in a second receiving shoe 37, which in turn is received in a second receiving pocket 38 of the second rotor body 7 and is fixed to the first rotor body 7 in such a way that the second spring leg 18 of the first leg spring 13 is coupled to the second rotor body 7 without play in the axial and circumferential directions.

[0059] The first spring leg 19 of the second leg spring 14 is also held in an analogous manner in a third receiving shoe 39, which in turn is received in a third receiving pocket of the first rotor body 5 and is fixed to the first rotor body 5 in such a way that the first spring leg 19 of the second leg spring 14 is coupled to the first rotor body 5 without play in the axial and circumferential directions.

[0060] Finally, the second spring leg 20 of the second leg spring 14 is also held in a fourth receiving shoe 41, which in turn is received in a fourth receiving pocket 42 of the second rotor body 7 and is fixed to the second rotor body 7 in such a way that the second spring leg 20 of the second leg spring 14 is coupled to the second rotor body 7 without play in the axial and circumferential directions.

[0061] It is also evident from Figure 5 that the first receiving shoe 30, the second receiving shoe 37, the third receiving shoe 39 and the fourth receiving shoe 41 are of identical design.

[0062] By means of the receiving shoes 30, 37, 39, 41, elements are arranged between the spring legs 17, 18, 19, 20 and the rotor bodies 5, whose position can be adjusted and fixed within a receiving pocket 31, 38, 42. The receiving shoes 30, 37, 39, 41 are pressed onto the spring legs 17, 18, 19, 20, for example, by means of a corresponding oversize, so that they are fixed to one another without play. The spring legs 17, 18, 19, 20 with the pre-assembled receiving shoes 30, 37, 39, 41 can be positioned in the rotor bodies 5, 7 using an assembly tool (not shown). Since a gap is formed between the receiving pockets 31, 38, 42 and the receiving shoes 30, 37, 39, 41, and the receiving shoes 30, 37, 39, 41 therefore engage in the receiving pockets 31, 38, 42 with some play, the location or position of the receiving shoes 30, 37, 39, 41 in the receiving pockets 31, 38, 42 is adjustable.The receiving shoes 30, 37, 39, 41, positioned in the receiving pockets 31, 38, 42, can then be secured by the fastening means 36. These are shown as screws in the figures. However, they can also be designed as rivets, or the fastening means 36 can be a soldered or welded joint.

[0063] Figure 6 shows the arrangement known from Figure 5 in an assembled state.

[0064] Figure 8 shows a kit of parts 43 for producing a mechanical field weakening mechanism 11 for a rotor 4 of an electric machine 1, in particular for use within a drive train of a hybrid or fully electric motor vehicle, comprising

[0065] • a first rotor body 5 with a first receiving pocket 31 and a second rotor body 7, wherein the first rotor body 5 and the second rotor body 7 are rotatable relative to each other against the effect of a first torsional stiffness 9 about a common axis of rotation 10,

[0066] • a first torsional stiffness 9, which is designed as a first leg spring arrangement 12 with a first leg spring 13, which is coaxial to the axis of rotation 10 and can be positioned between the first rotor body 5 and the second rotor body 7 or between one of the rotor bodies 5, 7 and a rotor shaft 16, such that the rotation of one of the rotor bodies 5, 7 that occurs during the adjustment of the field weakening mechanism 11 can cause an opening or closing actuation of the first leg spring 13, and the first leg spring 13 has at least one first spring leg 17,

[0067] • a first receiving shoe 30 in which the first spring leg 17 can be positioned and the receiving shoe 30 can in turn be received in the first receiving pocket 31 of the first rotor body 5 and can be fixed to the first rotor body 5 in such a way that the first spring leg 17 of the first leg spring 13 can be coupled to the first rotor body 5 without play in the axial and circumferential directions.

[0068] As shown, the kit of parts 43 can provide a receiving shoe 30, 37, 39, 41 for all spring legs 17, 18, 19, 20 of the leg spring arrangement 12, wherein these receiving shoes 30, 37, 39, 41 are designed essentially identically.

[0069] 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 in such a way 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.

[0070] List of reference symbols

[0071] 1 electric machine

[0072] 2 Stator

[0073] 3 Air gap

[0074] 4 Rotor

[0075] 5 rotor body

[0076] 6 permanent magnets

[0077] 7 Rotor body

[0078] 8 permanent magnets

[0079] 9 Torsional rigidity

[0080] 10 axis of rotation

[0081] 11 Field weakening mechanism

[0082] 12 Leg spring arrangement

[0083] 13 torsion spring

[0084] 14 torsion spring

[0085] 16 Rotor shaft

[0086] 17 spring legs

[0087] 18 spring legs

[0088] 19 spring legs

[0089] 20 spring legs

[0090] 28 Ring disc

[0091] 29 Ring disc

[0092] 30 Mounting shoe

[0093] 31 Recording pocket

[0094] 32 mounting groove

[0095] Section 33

[0096] 34 wall

[0097] 35 Opening

[0098] 36 Fasteners 37 Mounting shoe

[0099] 38 Recording pocket

[0100] 39 Mounting shoe

[0101] 41 Mounting shoe

[0102] 42 Recording pocket

[0103] 43 kit of parts

[0104] 50 lateral surface

[0105] 51 external gearing

[0106] 52 internal gearing

[0107] 53 lateral surface

[0108] 54 teeth

[0109] 55 undercut

[0110] 56 teeth

[0111] 57 undercut

[0112] 58 grooves

[0113] 59 groove base

[0114] 60 tooth head

[0115] 61 legs

[0116] 62 Mirror axis

[0117] 63 Mirror axis

[0118] 64 Mirror axis

[0119] 65 Mirror axis

Claims

Claims 1. Rotor (4) of 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), characterized in that 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, wherein the permanent magnets (6,8) are arranged only in the outer annular disc (29) formed from an electrical sheet., 2. Rotor (4) according to claim 1, characterized in that the inner annular disc (28) is made of a steel, in particular a hardened steel.

3. Rotor (4) according to claim 1 or 2, characterized in that the inner annular disc (28) and the outer annular disc (29) are positively connected to one another in a torque-transmitting manner.

4. Rotor (4) according to claim 3, characterized in that the inner annular disc (28) has on its outer surface (50) an external toothing (51) which engages in a corresponding internal toothing (52) on an inner surface (53) of the outer annular disc (29).

5. Rotor (4) according to claim 4, characterized in that the external toothing (51) and the internal toothing (52) are designed as plug-in toothing.

6. Rotor (4) according to claim 4 or 5, characterized in that a plurality of the teeth (54) of the external toothing (51) each have a first undercut (55) and a plurality of the teeth (56) of the internal toothing (52) each have a second undercut (57), wherein the first undercut (55) and the second undercut (57) are designed such that a force can be transmitted in the radial direction between the meshing internal toothing (52) and external toothing (51).

7. Rotor (4) according to claim 6, characterized in that the majority of the teeth (54) of the external toothing (51) and / or the majority of the teeth (56) of the internal toothing (52) are dovetail-shaped in cross section.

8. Rotor (4) according to claim 6 or 7, characterized in that the external toothing (51) between two circumferentially adjacent teeth (54) each has a groove (58) with a groove base (59), into which a tooth (56) of the internal toothing (52) engages with a tooth head (60), wherein the tooth head (60) has a play with respect to the groove base (59).

9. Rotor (4) according to one of claims 4-8, characterized in that the external toothing (51) and / or the internal toothing (52) have a chamfer.

10. Rotor (4) according to one of claims 4-9, characterized in that the permanent magnets (6, 8) are arranged in pairs in a V-shape in cross-section distributed over the circumference of an outer annular disc (29), wherein the free legs (61) of the V-shaped arrangement extend radially inward, and the V-shaped arrangement has a radially extending mirror axis (62) which runs coaxially to a radially extending mirror axis (63) of a tooth (54, 56) of the internal toothing (52) or external toothing (51) and / or the permanent magnets (6, 8) are arranged in pairs in a V-shape in cross-section distributed over the circumference of an outer annular disc (29), wherein the free legs (61) of the V-shaped arrangement extend radially inward, and a radially extending mirror axis (64) is defined between two circumferentially adjacent V-shaped arrangements,which runs coaxially to a radially extending mirror axis (65) of a tooth (56) of the internal toothing (52) or external toothing (51).

11. Electrical machine (1) comprising a stator (2) and a rotor (4) separated from the stator (2) by an air gap (3), characterized in that the rotor (4) is designed according to one of the preceding claims.

12. Kit-of-parts (43) for producing a mechanical field weakening mechanism (11) for a rotor (4) of an electric machine (1), in particular for use within a drive train of a hybrid or fully electric motor vehicle, comprising • a first rotor body (5) with a first receiving pocket (31) and a second rotor body (7), wherein the first rotor body (5) and the second rotor bodies (7) are rotatable relative to one another about a common axis of rotation (10) against the effect of a first torsional stiffness (9), • a first torsional stiffness (9), which is designed as a first leg spring arrangement (12) with a first leg spring (13) which is coaxial with the axis of rotation (10) and can be positioned between the first rotor body (5) and the second rotor body (7) or between one of the rotor bodies (5, 7) and a rotor shaft (16) such that the rotation of one of the rotor bodies (5, 7) which begins when the field weakening mechanism (11) is adjusted can cause an opening or closing actuation of the first leg spring (13), and the first leg spring (13) has at least one first spring leg (17), • a first receiving shoe (30) in which the first spring leg (17) can be positioned and the receiving shoe (30) can in turn be received in the first receiving pocket (31) of the first rotor body (5) and can be fixed to the first rotor body (5) in such a way that the first spring leg (17) of the first leg spring (13) can be coupled to the first rotor body (5) without play in the axial and circumferential directions.

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