Rotor and electric machine

Abstract

The invention relates to a rotor (4), which 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); said field-attenuation mechanism (11) comprises a first lever element (60) which can be pivoted about a fulcrum; 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), and the first lever section (61) and second lever section (62) are arranged on opposite sides of the lever (60) relative to a circumferential direction so that by tilting the lever element (60), the first rotor body (5) and the second rotor body (7) can be deliberately rotated relative to each other in order to produce a desired adjustment of the mechanical field-attenuation mechanism (11); coaxially within the first rotor body (5) and the second rotor body (7), a rotor shaft (16) can be torque-transmittingly coupled to the first rotor body (5) and the second rotor body (7) by means of the lever element (60); and the lever element (60) is pivotably mounted on the rotor shaft (16).

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,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 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. 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 driven 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 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.

[0010] 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.

[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, 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 the guide elements of the torsional stiffnesses can also lead to excessive hysteresis in the adjustment characteristic.

[0014] 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 an electrical machine with improved mechanical field weakening.

[0015] 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 in a targeted manner 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, wherein the lever element is pivotably arranged on the rotor shaft.

[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] 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.

[0018] 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 laminated cores, which are arranged on the rotor shaft in a rotationally fixed manner. The rotor shaft can be hollow, which on the one hand results in a weight saving and on the other hand allows the supply of lubricant or coolant to the rotor body. In the sense of the invention, a rotor body is understood to be the rotor without the rotor shaft. The rotor body is therefore composed in particular of a rotor laminated core and the permanent magnets introduced into the pockets of the rotor laminated core or fixed circumferentially to the rotor laminated core, as well as any axial cover parts present for closing the pockets.

[0019] 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.

[0020] The rotor has a plurality of rotor bodies. Particularly preferably, the rotor bodies are formed from substantially the same parts, in particular substantially identical. It is most preferred for the rotor bodies to be formed from substantially the same parts, 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.

[0021] 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.It may further be preferred that 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 first torsional stiffness is designed as a first leg spring arrangement with a first leg spring which is coaxial to the axis of rotation and is arranged between the first rotor body and the second rotor body or between one of the rotor bodies and a rotor shaft in such a way that the rotation of one of the rotor bodies which begins when the field weakening mechanism is adjusted causes an opening or closing actuation of the first leg spring.

[0022] The formation of a torsional stiffness as a leg spring arrangement to define an adjustment characteristic to weaken the magnetic field by a relative rotation of the rotor bodies allows in particular the reduction of the centrifugal force influence on the adjustment characteristic and its hysteresis.

[0023] According to an advantageous embodiment of the invention, the first leg spring arrangement can have a second leg spring which is arranged coaxially to the axis of rotation of the rotor and between the first rotor body and the second rotor body, or between one of the rotor bodies and the rotor shaft, such that the rotation of one of the rotor bodies that occurs when the field weakening mechanism is adjusted causes the second leg spring to open or close. The advantage of this embodiment is that a second leg spring makes the adjustment characteristic particularly easy to model and precisely adjustable. The leg springs can be designed to be essentially identical or different from one another, depending on which application-specific requirements must be implemented by the desired adjustment characteristic. The leg springs can be connected in series or in parallel.

[0024] According to a further preferred development of the invention, it can also be provided that the first leg spring has a first spring leg extending radially into the first rotor body and / or a second spring leg extending radially into the second rotor body, and / or the first leg spring has a first spring leg extending axially into the first rotor body and / or a second spring leg extending axially into the second rotor body, and / or the second leg spring has a first spring leg extending radially into the first rotor body and / or a second spring leg extending radially into the second rotor body, and / or the second leg spring has a first spring leg extending axially into the first rotor body and / or a second spring leg extending axially into the second rotor body.This makes it possible to achieve particularly compact torsional rigidities radially or axially, depending on the given installation space situation.

[0025] According to an advantageous embodiment of the invention, it can be provided that 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 and / or the lever element is mounted on a lever shaft which in turn is mounted in at least one of the rotor bodies.

[0026] According to a further preferred development of the invention, it can also be provided that the lever element is connected to the lever shaft in a rotationally fixed manner and that the lever shaft is rotatably mounted in a bearing bush of the lever carrier and / or at least one rotor body.

[0027] Furthermore, according to a similarly advantageous embodiment of the invention, the lever shaft can be rotatably mounted in the bearing bush by means of a roller bearing. The advantageous effect of this embodiment 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, the roller bearing is particularly preferred as a needle bearing.

[0028] According to a further particularly preferred embodiment of the invention, it can be provided that the lever element has a first lever disc with the first lever section and a second lever disc with the second lever section, which is axially spaced from the first lever disc.

[0029] Furthermore, the invention can also be further developed in such a way that the rotor has a plurality of lever elements which are arranged circumferentially distributed and each pivotably arranged on the rotor shaft, wherein the lever elements each have a first lever disc and a second lever disc and two first lever discs are arranged on a first lever shaft and two second lever discs are arranged on a second lever shaft.

[0030] In a likewise preferred embodiment of the invention, it can also be provided that the first lever disc and the second lever disc are shaped essentially identically. This allows a particularly cost-efficient design of the rotor to be achieved through an increased proportion of identical parts.

[0031] It may also be advantageous to further develop the invention in such a way that the first lever disc and / or the second lever disc are / is punched from a sheet metal, which can contribute to a particularly cost-effective production of the lever discs.

[0032] According to a further preferred embodiment of the subject matter of the invention, it can be provided that the rotor bodies are each constructed in two parts, with an inner annular disc 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 and the mechanical field weakening mechanism is arranged only in and / or on the inner annular disc. The advantage resulting from this is, in particular, that the mechanical field weakening mechanism can thus be manufactured independently of the magnetic region of a rotor body, which can improve the flexibility in the design and manufacture of the electrical machine. The inner annular disc is particularly preferably made of a steel, in particular of a hardened steel.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 1-9.

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

[0034] It shows:

[0035] Figure 1 shows an electrical machine in a cross-sectional view,

[0036] Figure 2 is a schematic block diagram of a rotor with a mechanical field weakening mechanism

[0037] Figure 3 shows a rotor in a cross-sectional view,

[0038] Figure 4 shows a detailed view of a rotor in a cross-sectional view,

[0039] Figure 5 shows a first embodiment of a leg spring arrangement with two

[0040] Rotor bodies in a perspective exploded view,

[0041] Figure 6 shows a first embodiment of a leg spring arrangement with two rotor bodies in an assembled state in a perspective view,

[0042] Figure 7 shows a first embodiment of a rotor in a perspective view,

[0043] Figure 8 shows a first embodiment of the rotor in a schematic axial section, Figure 9 shows a detailed view of the bearing of the lever elements in the first embodiment of the rotor in an axial section,

[0044] Figure 10 shows a first embodiment of the rotor in a first, field-strengthened operating state in a combined cross-sectional view of the first and second rotor bodies,

[0045] Figure 11 shows a first embodiment of the rotor in a second, field-weakened operating state in a combined cross-sectional view of the first and second rotor bodies,

[0046] Figure 12 shows a first embodiment of the rotor in a third field-strengthened operating state in a combined cross-sectional view of the first and second rotor bodies,

[0047] Figure 13 shows a lever carrier in a perspective view,

[0048] Figure 14 shows a second embodiment of a rotor in a first perspective view,

[0049] Figure 15 shows a second embodiment of a rotor in a second perspective view,

[0050] Figure 16 shows a second embodiment of a rotor in a first schematic axial sectional view,

[0051] Figure 17 shows a second embodiment of a rotor in a second schematic axial section,

[0052] Figure 18 shows a third embodiment of a rotor in a perspective view,

[0053] Figure 19 shows two lever disks, each in a perspective view. Figure 1 shows an electric machine 1, in particular for use within a drive train of a hybrid or fully electric motor vehicle. The electric machine 1, configured as a radial flux machine, comprises a stator 2 and a rotor 4 separated from the stator 2 by an air gap 3, 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, which can be clearly seen from the combination of Figure 1 and Figure 2.

[0054] 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.

[0055] 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 in a targeted manner 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.

[0056] 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 rotational axis 10 and between the first rotor body 5 and the second rotor body 7 such that the rotation of one of the rotor bodies 5, 7 that occurs during the adjustment of the field weakening mechanism 11 causes an opening or closing actuation of the first leg spring 13. Even if not shown in Figures 2-3, 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] The external toothing 51 further comprises, between each two 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 80, wherein the tooth tip 80 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.

[0061] 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 81 of the V-shaped arrangement extend radially inward, and the V-shaped arrangement has a radially extending mirror axis 82 which runs coaxially to a radially extending mirror axis 83 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 84 is defined, which runs coaxially to a radially extending mirror axis 85 of a tooth 56 of the internal toothing 52 or external toothing 51. In this context, it can also be clearly seen from Figure 4 that the meshing teeth 54, 56, through which the mirror axes 82, 83 run, are wider in the circumferential direction than the circumferentially adjacent teeth 54, 56.The same applies to the meshing teeth 54,56 through which the mirror axes 84,85 pass.

[0062] 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.

[0063] 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 which occurs during the adjustment of the field weakening mechanism 11 causes an opening or closing actuation of the second leg spring 14. As shown in Figure 3, the first leg spring 13 and the second leg spring 14 are designed essentially in the same part and are arranged rotated by approximately 180° about the axis of rotation 10 relative to one another, 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.

[0064] 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.

[0065] 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.

[0066] 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. 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.

[0067] 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.

[0068] It is also shown in Figure 5 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 axially and circumferentially

[0069] Direction is coupled to the second rotor body 7 without play.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] Figure 6 shows the arrangement known from Figure 5 in an assembled state.

[0075] The mechanical field weakening mechanism 11 will now be explained in more detail below with reference to Figures 7-17.

[0076] Figure 7 shows a rotor 4 for an electrical machine 1 having a first rotor body 5 with a first group of permanent magnets 6. The axially adjacent second rotor body 7 is not shown in order to allow a better view of the field weakening mechanism 11.

[0077] 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 the mechanical field weakening mechanism 11, counter to the effect of a first torsional stiffness 9. 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, 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 by tilting the lever element 60 for a desired adjustment of the mechanical field weakening mechanism 11.

[0078] Here, a rotor shaft 16 can be coupled coaxially within the first rotor body 5 and the second rotor body 7 via the lever element 60 in a torque-transmitting manner to the first rotor body 5 and the second rotor body 7. The lever element 60 is further pivotally arranged on the rotor shaft 16. The lever element 60 is mounted on a lever shaft 63 so as to be rotatable relative to an annular lever carrier 64, which is positioned coaxially to the rotor shaft 16. In the embodiment shown, the lever element 60 is connected in a rotationally fixed manner to the lever shaft 63, and the lever shaft 63 is in turn rotatably mounted by means of a rolling bearing 66 in a bearing bush 65 of the lever carrier 64.

[0079] Figure 7 further shows that the lever element 60 has a first lever disc 67 with the first lever section 61 and a second lever disc 68 with the second lever section 62, axially spaced from the first lever disc 67. The first lever disc 67 and the second lever disc 68 are essentially identical in shape, but are arranged rotated by 180° relative to each other about their radial axis.

[0080] In the embodiment of the invention shown, the rotor 4 has a plurality of lever elements 60, which are arranged circumferentially distributed and pivotable on the rotor shaft 16, wherein the lever elements 60 each have a first lever disc 67 and a second lever disc 68

[0081] Thus, there is a contact point from the lever element 60 (inside) to the rotor shaft 16 and a contact point from the lever element 60 radially outward to one of the two rotor bodies 5, 7. These radially outer contact points are contact points of a still rolling contact and move radially outward during adjustment with increasing tilting of the lever element 60. The inner contact point, on the other hand, does not change its radial position, since it remains at the same radial distance from the axis of rotation of the rotor shaft 16 as the centers of rotation of the lever shafts 63, which form the tilting axis of the lever elements 60.

[0082] The lever elements 60 are designed as stampable sheet metal parts that provide the lever sections 61, 62, 71, 72 for the contact points to the rotor shaft 16 or to the rotor bodies 5, 7 in the shape of the sheet thickness at their cut surface and have an opening 69 for the insertion of a lever shaft 63. Since the contact areas are thereby quite narrow and accordingly have higher pressures during operation, the lever element 60 and the area of ​​the rotor bodies 5, 7 in contact with the lever element 60 are preferably made of a hardenable or tempered material and no longer of electrical sheet.

[0083] The radially acting centrifugal forces of the lever elements 60 are supported in the rotor bodies 5, 7 via the lever shaft 63 and the roller bearing 66. The lever elements 60 experience only minimal stresses. The lever shaft 63 can be supported by a plain bearing, although not shown in the figures.

[0084] The lever elements 60 are thus mounted on the lever shafts 63, wherein the lever shafts 63 are in contact via the lever elements 60 in a first operating state exclusively with the first rotor body 5 and in a second operating state exclusively with the second rotor body 7 in a torque-transmitting manner in the circumferential direction.

[0085] In the following, three design variants are described in which the transfer of the contact points during transitions between the operating states of the rotor is realized differently from one another.

[0086] In the embodiment shown in Figures 7-12, a first lever disc 67 and a second lever disc 68 are each arranged on a first lever shaft 63. Here, the lever discs 67, 68 of a lever element 60 are each seated on a common lever shaft 63 for adjustment into the two operating states, which are mounted in an annular lever carrier 64. For one operating state, the lever carrier 64 is supported in a torque-transmitting manner in the circumferential direction via a toothing or axially extending fingers on an inner annular disc 28 of one of the rotor bodies 5, 7; for the other operating state, it is supported on an inner annular disc 28 of the other rotor body 5, 7. The annular discs 28, each driven by the lever elements 60, can move relative to the fingers or toothing of the lever carrier 64 over a sufficiently large angle of rotation without collisions thanks to recesses provided for this purpose.During transitions between motor and generator operation, the contact points are transferred to the gearing or fingers at another location on the lever carrier 64. The radially acting centrifugal forces of the lever elements 60 are supported in the lever carrier 64 via the lever shafts 63. Figures 10-12 show this embodiment in three different operating states. Figure 10 shows the position of the lever disks 67, 68 in a first, field-strengthened, shear-loaded operating state in a combined cross-sectional view of the first and second rotor bodies 5, 7. Figure 11 shows the same configuration in a field-weakened operating state. Figure 12 shows a field-strengthened, tensile-loaded operating state.

[0087] Figures 14-17 show a variant embodiment in which two first lever disks 67 are arranged on a first lever shaft 63 and two second lever disks 68 are arranged on a second lever shaft 63. In these figures, two longitudinal sections of the rotor 4 rotated by 90° to each other about the axis of rotation of the rotor shaft 16 show a variant embodiment in which the lever elements 60 for adjustment for both operating states are seated on separate lever shafts 63. In Figure 16, for an operating state with two centrally seated rolling bearings 66, one part of the lever shafts 63 is mounted in bearing seats of the inner annular disks 28 of the first rotor body 5 and is thus supported in a torque-transmitting manner in the circumferential direction via contact points on the corresponding lever shafts 63.In Figure 17, for the other operating state with two axially spaced roller bearings 66, the other part of the lever shafts 63 is mounted in bearing seats of the two adjacent inner annular discs 28 of the second rotor body 7 and is thus supported in a torque-transmitting manner in the circumferential direction via other contact points.

[0088] The inner ring disks 28, each driven by the lever elements 60, can move through recesses provided for this purpose relative to the lever shafts 63 supported in the other ring disks 28, together with the lever elements 60, over a sufficiently large angle of rotation without collisions. During transitions between motor and generator operation, the contact points are transferred to the bearings of the other lever shafts 63.

[0089] Figure 14 shows a perspective view of the mechanical

[0090] Field weakening mechanism 11 inside the rotor 4, as known from Figures 16-17. This shows a deflected position of one operating state, where the lever discs 67 of the lever elements 60 rotate the first rotor body 5 clockwise when the rotor shaft 16 is rotated counterclockwise. The lever discs 68 of the lever elements 60 are free. Figure 15 shows a deflected position of the other operating state, where the lever discs 68 of the lever elements 60—mounted in the axially adjacent inner annular discs 28—rotate the second rotor body 7 counterclockwise when the rotor shaft 16 is rotated clockwise. The lever discs 67 of the lever element 60 are free.

[0091] Figure 18 shows a longitudinal section through rotor 4 of a variant embodiment in which the lever elements 60 for adjusting the rotor bodies 5, 7 into the two operating states (field weakening / field strengthening) are mounted on a common lever shaft 63. For one operating state, these lever shafts 63 are supported on the left over a short axial distance and on the right over a longer axial distance in the inner annular disk 28 of the first rotor body 5, transmitting torque in the circumferential direction at the corresponding contact points; for the other operating state, they are supported on the left over a longer axial distance and on the right over a short axial distance in the inner annular disks 28 of the second rotor body 7. In the opposite circumferential direction, the lever shafts 63 can move freely relative to the non-supporting rotor body 5, 7 through recesses provided for this purpose over a sufficiently large angle of rotation relative to the axis of rotation of the rotor shaft 16.During transitions between motor and generator operation, the contact points of the other side are transferred on the circumference of the lever shafts 63 at the other axial distances.

[0092] Figure 19 shows the lever disks 67, 68, which can be produced as simple stamped parts, with their respective lever sections 61, 62 for the rotor shaft 16 and the lever sections 71, 72 for the rotor bodies 5, 7, as well as the openings 69 for receiving the lever shaft 63. The first lever disk 67 and the second lever disk 68 are stamped from a single sheet metal. The invention is not limited to the embodiments shown in the figures. The above description is therefore not to be regarded as limiting, but as explanatory. The following patent claims are to be understood in such a way that a named feature is present in at least one embodiment of the invention. This does not exclude the presence of further features. If the patent claims and the above description define 'first' and 'second' features, this designation serves to distinguish between two similar features without establishing a priority.

[0093] List of reference symbols

[0094] 1 electric machine

[0095] 2 Stator

[0096] 3 Air gap

[0097] 4 Rotor

[0098] 5 rotor body

[0099] 6 permanent magnets

[0100] 7 Rotor body

[0101] 8 permanent magnets

[0102] 9 Torsional stiffness

[0103] 10 axis of rotation

[0104] 11 Field weakening mechanism

[0105] 12 Leg spring arrangement

[0106] 13 torsion spring

[0107] 14 torsion spring

[0108] 16 Rotor shaft

[0109] 17 spring legs

[0110] 18 spring legs

[0111] 19 spring legs

[0112] 20 spring legs

[0113] 28 Ring disc

[0114] 29 Ring disc

[0115] 28 Ring disc

[0116] 29 Ring disc

[0117] 30 Mounting shoe

[0118] 31 Recording pocket

[0119] 32 mounting groove

[0120] Section 33

[0121] 34 wall

[0122] 35 Opening 36 Fasteners

[0123] 37 Mounting shoe

[0124] 38 Recording pocket

[0125] 39 Mounting shoe

[0126] 41 Mounting shoe

[0127] 42 Recording pocket

[0128] 50 lateral surface

[0129] 51 external gearing

[0130] 52 internal gearing

[0131] 53 lateral surface

[0132] 54 teeth

[0133] 55 undercut

[0134] 56 teeth

[0135] 57 undercut

[0136] 58 grooves

[0137] 59 groove base

[0138] 60 lever element

[0139] 61 Lever section

[0140] 62 lever section

[0141] 63 Lever shaft

[0142] 64 lever carriers

[0143] 65 bearing bush

[0144] 66 Rolling bearings

[0145] 67 lever disc

[0146] 68 lever disc

[0147] 69 Opening

[0148] 71 Lever section

[0149] 72 lever section

[0150] 80 tooth head

[0151] 81 legs

[0152] 82 Mirror axis Mirror axis Mirror axis Mirror axis

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) can be coupled coaxially within the first rotor body (5) and the second rotor body (7) via the lever element (60) in a torque-transmitting manner, characterized in that the lever element (60) is pivotally arranged on the rotor shaft (16).

2. Rotor (4) according to claim 1, characterized in that the lever element (60) is mounted on a lever shaft (63) rotatably relative to an annular lever carrier (64) which is positioned coaxially to the rotor shaft (16) and / or the lever element (60) is mounted on a lever shaft (63) which in turn is mounted in at least one of the rotor bodies (5, 7).

3. Rotor (4) according to claim 2, characterized in that the lever element (60) is rotationally connected to the lever shaft (63) and the lever shaft (63) is rotatably mounted in a bearing bush (65) of the lever carrier (64) and / or at least one rotor body (5, 7) 4. Rotor (4) according to claim 3, characterized in that the lever shaft (63) is rotatably mounted in the bearing bush (65) by means of a rolling bearing (66).

5. Rotor (4) according to one of the preceding claims, characterized in that the lever element (60) has a first lever disc (67) with the first lever section (61) and a second lever disc (68) with the second lever section (62) axially spaced from the first lever disc (67).

6. Rotor (4) according to one of the preceding claims, characterized in that the rotor (4) has a plurality of lever elements (60) which are arranged in a circumferentially distributed manner in each case pivotably on the rotor shaft (16), wherein the lever elements (60) each have a first lever disc (67) and a second lever disc (68) and each have two first lever discs (67) on a first lever shaft (63) and two second lever discs (68) are arranged on a second lever shaft (63).

7. Rotor (4) according to one of the preceding claims 5-6, characterized in that the first lever disc (67) and the second lever disc (68) are shaped substantially identically.

8. Rotor (4) according to one of the preceding claims 5-7, characterized in that the first lever disc (67) and / or the second lever disc (68) are / is punched from a sheet metal.

9. Rotor (4) according to one of the preceding claims, characterized in that the rotor bodies (5, 7) are each constructed in two parts, with an inner annular disc (28) 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) and the mechanical field weakening mechanism (11) is arranged only in and / or on the inner annular disc (28).

10. 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.

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