Rotor and electric machine

Abstract

The invention relates to an electric machine (1), in particular for use within a drivetrain of a hybrid or all-electric motor vehicle. The machine comprises a stator (2) and a rotor (4), which is separated from the stator (2) by an air gap (3), wherein 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); the first torsional stiffness mechanism (9) is designed as a first torsion spring arrangement (12) with a first torsion spring (13), which is arranged coaxially relative to the rotational axis (10) and 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 torsion of one of the rotor bodies (5, 7) that is the result of the adjustment of the field-attenuation mechanism (11), results in an opening or closing actuation of the first torsion spring (13).

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. 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 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 first torsional stiffness is designed as a first leg spring arrangement with a first leg spring, which is arranged coaxially to the axis of rotation and thus between the first rotor body and the second rotor body or between one of the rotor bodies and a rotor shaft,that the rotation of one of the rotor bodies which occurs during the adjustment of the field weakening mechanism causes an opening or closing actuation of the first leg spring.

[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 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.

[0018] Further advantages of this design include a comparatively small number of individual components for providing torsional rigidity and the associated simplified assembly. Furthermore, the torsion spring enables a particularly compact design of the mechanical field weakening mechanism.

[0019] 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.

[0020] A rotor is the rotating part of an electrical machine. The rotor comprises, in particular, a rotor shaft and one or more rotor bodies formed from rotor cores, arranged in a rotationally fixed manner on the rotor shaft. The rotor shaft can be hollow, which not only reduces weight but also allows the supply of lubricant or coolant to the rotor body.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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 in such a way that the rotation of one of the rotor bodies which occurs during the adjustment of the field weakening mechanism causes the second leg spring to be actuated in the same way as the first leg spring. 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 parallel to each other.

[0026] 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.

[0027] Furthermore, according to a likewise advantageous embodiment of the invention, it can be provided that the first leg spring and the second leg spring are made essentially of the same part and are arranged rotated relative to one another about the axis of rotation, so that the first spring leg and the second spring leg of the first leg spring point in a common radial and / or axial direction and the first spring leg and the second spring leg of the second leg spring are oriented in an opposite radial and / or axial direction. The advantageous effect of this embodiment is that transverse forces which occur when the leg springs are actuated and a structural imbalance in the rotating rotor can be avoided or at least reduced. For example, a package of two identical opening and closing springs can then be used.Closing leg springs are formed by screwing the first and second leg springs together, enabled by a corresponding coil spacing, and then twisting them relative to each other. For this purpose, the leg springs preferably have a coil spacing that is slightly larger than the wire thickness of the leg springs in the axial direction.

[0028] The ends of the leg springs are preferably arranged opposite each other in pairs, which helps further reduce rotor imbalance. In principle, the leg springs can have any number of turns, although it is preferred that the leg springs have the same number of turns.

[0029] According to a further particularly preferred embodiment of the invention, it can be provided that the electrical machine has a second torsional stiffness, which is designed as a second leg spring arrangement with a third leg spring, which is arranged coaxially to the axis of rotation and between a third rotor body and a fourth rotor body or between one of these rotor bodies and the rotor shaft in such a way that the rotation of one of these rotor bodies which begins when the field weakening mechanism is adjusted causes an opening or closing actuation of the third leg spring, wherein the third rotor body and the second rotor body are preferably arranged axially adjacent in the rotor and the first leg spring arrangement and the second leg spring arrangement have a different actuation orientation from one another.This makes it possible, in particular, to compensate for the influence of the centrifugal force occurring during operation on the adjustment characteristic of the mechanical field weakening mechanism. Furthermore, axial force compensation can also be achieved by ensuring that the torsional stiffness opens and closes at the same rate.

[0030] It should be noted that the specified coaxiality may shift slightly during operation of the rotor, so that the specified coaxiality here always refers to the rotor at rest.

[0031] The first leg spring arrangement and the second leg spring arrangement are further preferably arranged rotated by approximately 90° relative to one another about the axis of rotation, whereby an imbalance compensation can be realized, which in particular allows the operation of the rotor at high speeds, for example >15,000 rpm.

[0032] Furthermore, the invention can also be further developed such that the leg springs of the first leg spring arrangement and the second leg spring arrangement have a similar winding direction for the two actuation orientations. In this case, it must be ensured, for example, by appropriately connecting the leg spring arrangement to the rotor body, that the two leg spring arrangements have opposite actuation orientations, so that when one leg spring arrangement opens, the other closes, and vice versa.

[0033] Alternatively, the leg springs of the first leg spring arrangement and the second leg spring arrangement can also have an opposite winding direction for the two actuation orientations. In this case, too, it must be ensured, for example, by appropriately connecting the leg spring arrangement to the rotor body, that the two leg spring arrangements have an opposite actuation orientation, so that when one leg spring arrangement opens, the other closes, and vice versa. In a likewise preferred embodiment of the invention, it can also be provided that at least one, preferably all, leg springs are wound from a spring wire with a substantially rectangular cross-section.

[0034] This makes it possible to increase the energy content of the leg springs in their installation space and to facilitate the bending moment-transmitting and transverse force-free suspension of the spring ends designed as legs in recesses of discs, which form a structural unit with the partial rotors or the rotor shaft for the transmission of torque.

[0035] It may also be advantageous to further develop the invention in such a way that at least one, preferably all, leg springs are preloaded. The advantage of this is that a moment can be defined at which the adjustment process should begin. For this purpose, the leg springs in the arrangement can then be preloaded, for example, by a specific angle of rotation.

[0036] According to a further preferred embodiment of the subject matter of the invention, the leg springs can be constructed from essentially identical parts. This allows for particularly cost-efficient production of the leg springs. Furthermore, manufacturing and assembly are facilitated by a higher degree of identical parts.

[0037] Finally, the invention can also be advantageously designed such 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.

[0038] The resulting advantage is, in particular, that the mechanical field weakening mechanism can be manufactured independently of the magnetic region of a rotor body, which can improve the flexibility in the design and manufacture of the electric machine. The object of the invention is further achieved by an electric machine, in particular for use within a drive train of a hybrid or fully electric motor vehicle, 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.

[0039] The invention will be explained in more detail below with reference to figures without limiting the general inventive concept.

[0040] It shows:

[0041] Figure 1 shows an electrical machine in a cross-sectional view,

[0042] Figure 2 is a schematic block diagram of a rotor with a mechanical field weakening mechanism,

[0043] Figure 3 shows a first embodiment of a torsional stiffness in a perspective view,

[0044] Figure 4 shows a second embodiment of a torsional stiffness in a perspective view,

[0045] Figure 5 shows a rotor in a cross-sectional view,

[0046] Figure 6 shows a detailed view of the rotor in a cross-sectional view,

[0047] Figure 7 shows a first embodiment of a leg spring arrangement with two rotor bodies in a perspective exploded view,

[0048] Figure 8 shows a first embodiment of a leg spring arrangement with two rotor bodies in an assembled state in a perspective view, Figure 9 shows a rotor body with a leg spring arrangement on it in a detailed enlargement.

[0049] 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.

[0050] 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.

[0051] The field weakening mechanism 11 shown as an example in Figure 2 comprises a lever element (not further identified) that can be pivoted about a pivot point, wherein the first rotor body 5 can be coupled to a first lever section and the second rotor body 7 can be coupled to a second lever section of the lever element. The first lever section and the second lever section are arranged on opposite sides of the lever, so that the first rotor body 5 and the second rotor body 7 can be rotated relative to one another by tilting the lever element for a desired adjustment of the mechanical field weakening mechanism 11. This field weakening mechanism 11 is described in detail in DE102022106944 and DE102022106945, so that reference is made here to these documents to avoid repetition.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.

[0052] The first leg spring arrangement 12 has a second leg spring 14, which is arranged coaxially to the axis of rotation 15 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 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 1, the first leg spring 13 and the second leg spring 14 are designed essentially in the same part 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 in a common radial direction and the first spring leg 19 and the second spring leg 20 of the second leg spring 14 are oriented in an opposite radial direction.

[0053] 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.

[0054] Figure 3 further shows that the electric machine 1 in the embodiment shown has a second torsional stiffness 21, which is designed as a second leg spring arrangement 22 with a third leg spring 23, which is arranged coaxially to the axis of rotation 10 and between a third rotor body 25 and a fourth rotor body 27 in such a way that the rotation of one of these rotor bodies 25, 27 that occurs during the adjustment of the field weakening mechanism 11 causes an opening or closing actuation of the third leg spring 23. The first leg spring arrangement 12 and the second leg spring arrangement 22 are rotated by approximately 90° relative to one another about the axis of rotation 10.

[0055] Here, the third rotor body 25 and the second rotor body 7 are arranged axially adjacent in the rotor 4. It would also be conceivable for the second rotor body 7 and the third rotor body 25 to be constructed in one piece. This variant is shown in Figure 4. In the configuration shown, the first leg spring arrangement 12 and the second leg spring arrangement 22 have different actuation orientations from one another, which is also indicated by the arrows in Figure 3. The first leg spring arrangement 12 is actuated to close, while the second leg spring arrangement 22 is actuated to open, which contributes to speed neutrality with respect to the torque.

[0056] The spring ends of the leg springs 13, 14, 23 can be formed as radially or axially extending legs by appropriate bending. Figure 3 shows an embodiment with radially extending legs, and Figure 4 shows an embodiment with axially extending legs.

[0057] In the embodiment of Figure 3, the ends of the leg springs engage in radial grooves 26 provided for this purpose in a form-fitting manner and essentially without play.

[0058] Unlike in Figure 3, the first leg spring 13 in the embodiment of Figure 4 has a first spring leg 17 extending axially into the first rotor body 5 and a second spring leg 18 extending axially into the second rotor body 7. Analogously, the second leg spring 14 also has a first spring leg 19 extending axially into the first rotor body 5 and a second spring leg 20 extending axially into the second rotor body 7. In the embodiment of Figure 4, the ends of the leg springs then engage in axial grooves 24 provided for them in a form-fitting manner and essentially without play. The essentially identical rotor bodies 5, 7, 25, 27 have a total of four identical axial grooves 24 distributed equidistantly around the circumference.

[0059] What can also be seen from Figures 3-4 is that all leg springs 13, 14, and 23 are wound from a spring wire with a substantially rectangular cross-section and are constructed of essentially the same parts. Furthermore, all leg springs 13, 14, and 23 are preloaded.

[0060] Finally, it is also clear from the combination of Figures 1-4 that the rotor bodies 5, 7, 25, 27 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.

[0061] 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.

[0062] Figure 5 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.

[0063] From the detailed illustration in Figure 6 it can be seen that the teeth 54 of the

[0064] The external toothing 51 each has a first undercut 55. The teeth 56 of the internal toothing 52 also have a second undercut 57, the first undercut 55 and the second undercut 57 being designed such that a force can be transmitted in the radial direction between the meshing internal toothing 52 and the 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-like 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, this allows larger radii to be used in the tooth base of the annular disks 28, 29. This reduces the local stresses and enables faster and more cost-effective production of the gears 51 ,52 e.g.by selecting a cutter with a larger diameter. The undercut 55, 57 is thus created by the slanted lateral flanks of teeth 54, 56. With this shape, the openings of the tooth gaps in the annular discs 28, 29 are wider, which allows for simpler and more cost-effective tooth production, e.g., by broaching, shaping, or milling.

[0065] 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 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.

[0066] 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.

[0067] 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 7. As can be seen from Figure 7, 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] Figure 7 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 9. 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 9 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.

[0072] Figure 7 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.

[0073] 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.

[0074] 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.

[0075] It is also evident from Figure 7 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.

[0076] 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.

[0077] Figure 8 shows the arrangement known from Figure 7 in an assembled state.

[0078] 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.

[0079] List of reference symbols

[0080] 1 electric machine

[0081] 2 Stator

[0082] 3 Air gap

[0083] 4 Rotor

[0084] 5 rotor bodies

[0085] 6 permanent magnets

[0086] 7 Rotor body

[0087] 8 permanent magnets

[0088] 9 Torsional rigidity

[0089] 10 axis of rotation

[0090] 11 Field weakening mechanism

[0091] 12 Leg spring arrangement

[0092] 13 torsion spring

[0093] 14 torsion spring

[0094] 15 Rotation axis

[0095] 16 Rotor shaft

[0096] 17 spring legs

[0097] 18 spring legs

[0098] 19 spring legs

[0099] 20 spring legs

[0100] 21 Torsional stiffness

[0101] 22 Leg spring arrangement

[0102] 23 torsion spring

[0103] 24 axial grooves

[0104] 25 rotor bodies

[0105] 26 radial grooves

[0106] 27 Rotor body

[0107] 28 Ring disc

[0108] 29 Ring disc

[0109] 30 Mounting shoe

[0110] 31 Receiving pocket 32 ​​Receiving groove

[0111] Section 33

[0112] 34 wall

[0113] 35 Opening

[0114] 36 fasteners

[0115] 37 Mounting shoe

[0116] 38 Recording pocket

[0117] 39 Mounting shoe

[0118] 41 Mounting shoe

[0119] 42 Recording pocket

[0120] 50 lateral surface

[0121] 51 external gearing

[0122] 52 internal gearing

[0123] 53 lateral surface

[0124] 54 teeth

[0125] 55 undercut

[0126] 56 teeth

[0127] 57 undercut

[0128] 58 grooves

[0129] 59 groove base

[0130] 60 tooth head

[0131] 61 legs

[0132] 62 Mirror axis

[0133] 63 Mirror axis

[0134] 64 Mirror axis

[0135] 65 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 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 first torsional stiffness (9) 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 is arranged 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) in such a way that the field weakening mechanism (11) incipient rotation of one of the rotor bodies (5,7) causes an opening or closing actuation of the first leg spring (13).

2. Rotor (4) according to claim 1, characterized in that the first leg spring arrangement (12) has a second leg spring (14) which is arranged coaxially to the axis of rotation (15) of the rotor (4) and between the first rotor body (5) and the second rotor body (7) or between one of the rotor bodies (5, 7) and the rotor shaft (16) in such a way that the rotation of one of the rotor bodies (5, 7) which begins when the field weakening mechanism (11) is adjusted causes the second leg spring (14) to be actuated in the same way as the first leg spring (13).

3. Rotor (4) according to claim 1 or 2, characterized in that the first leg spring (13) has a first spring leg (17) extending radially into the first rotor body (5) and / or a second spring leg (18) extending radially into the second rotor body (7), and / or the first leg spring (13) has a first spring leg (17) extending axially into the first rotor body (5) and / or a second spring leg (18) extending axially into the second rotor body (7), and / or the second leg spring (14) has a first spring leg (19) extending radially into the first rotor body (5) and / or a second spring leg (20) extending radially into the second rotor body (7),and / or the second leg spring (14) has a first spring leg (19) extending axially into the first rotor body (5) and / or a second spring leg (20) extending axially into the second rotor body (7).

4. Rotor (4) according to claim 2 or 3, characterized in that the first leg spring (13) and the second leg spring (14) are designed essentially in the same part 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 legs (18) of the first leg spring (13) point in a common radial and / or axial direction and the first spring leg (19) and the second spring leg (20) of the second leg spring (14) are oriented in a radial and / or axial direction opposite thereto.

5. Rotor (4) according to one of the preceding claims, characterized in that the electrical machine (1) has a second torsional stiffness (21), which is designed as a second leg spring arrangement (22) with a third leg spring (23), which is arranged coaxially to the axis of rotation (10) and between a third rotor body (25) and a fourth rotor body (27) or between one of these rotor bodies (25, 27) and the rotor shaft (16) in such a way that the rotation of one of these rotor bodies (25, 27) which begins during the adjustment of the field weakening mechanism (11) causes an opening or closing actuation of the third leg spring (23), wherein the third rotor body (25) and the second rotor body (7) are preferably arranged axially adjacent in the rotor (4) and the first leg spring arrangement (12) and the second leg spring arrangement (22) have a different actuation orientation.

6. Rotor (4) according to claim 5, characterized in that the leg springs (13, 14, 23) of the first leg spring arrangement (12) and the second leg spring arrangement (22) have a similar winding direction for the two actuation orientations, or the leg springs (13, 14, 23) of the first leg spring arrangement (12) and the second leg spring arrangement (22) have an opposite winding direction for the two actuation orientations, 7. Rotor (4) according to one of the preceding claims, characterized in that at least one, preferably all, leg springs (13, 14, 23) are wound from a spring wire with a substantially rectangular cross-section.

8. Rotor (4) according to one of the preceding claims, characterized in that at least one, preferably all leg springs (13, 14, 23) are installed prestressed.

9. Rotor (4) according to one of the preceding claims 5-8, characterized in that the leg springs (13, 14, 23) are designed essentially in the same part 10. Rotor (4) according to one of the preceding claims, characterized in that the rotor bodies (5, 7, 25, 27) 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).

11. Electrical machine (1), in particular for use within a drive train of a hybrid or fully electric motor vehicle, 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.

Images