Electric machine

Abstract

The invention relates to an electric machine (120), comprising a stator (2) and a rotor (1) which is separated from the stator (2) by an air gap (22). The rotor (1) comprises at least one first rotor body (3), which has a first group of permanent magnets (6), and at least one second rotor body (4), which is arranged at an axial distance from the first rotor body (3) and has a second group of permanent magnets (61), and a rotor shaft (5) is coupled to the first rotor body (3) and the second rotor body (4) coaxially within the first rotor body (3) and the second rotor body (4) so as to transmit a torque. At least the first rotor body (3) is mounted on the rotor shaft (5) so as to be rotatable relative to the second rotor body (4) against the effect of a first torsional stiffness (8) by means of a mechanical field-attenuation mechanism (7), and the lever element (10) contours (17) which are in contact with the lever contact sections (12, 13, 15, 16) are designed such that in each operating position of the mechanical field-attenuation mechanism (7) over the entire movement path thereof in sections perpendicularly to the rotational axis (18) of the rotor (1), all of the contact points (19, 20, 21) between the rotor bodies (3, 4) and the lever element (10) are arranged on a straight connection line (23) between the tilting axis (24) of the lever element (10) and the rotational axis (18) of the rotor (1).

Description

[0001] Electric machine

[0002] The present invention relates to 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 comprises at least a first rotor body with a first group of permanent magnets and at least one second rotor body axially spaced from the first rotor body with a second group of permanent magnets, and coaxially within the first rotor body and the second rotor body, a rotor shaft is coupled to the first rotor body and the second rotor body in a torque-transmitting manner, wherein at least the first rotor body is rotatably mounted on the rotor shaft by means of a mechanical field weakening mechanism against the effect of a first torsional stiffness relative to the second rotor body.

[0003] 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.

[0004] 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.

[0005] 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.

[0006] 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 US5821710, FR28131345, EP1085644, EP1867030, DE10401708670, DE104016103470, CN104600929 and CN105449969, 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. Depending on the relative rotation between the rotor disks, the rotor 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.

[0007] DE 10 4021 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 4021 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.

[0008] 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.

[0009] Even in the de-energized case, there are interactions between the

[0010] The rotor disks of the two sub-rotors exhibit 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, which increases with increasing rotation until it reaches a maximum, and then decreases again with further rotation. The progression of the repulsion moment over the angle of rotation within an electrical period, the magnitude 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 nonlinear.

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

[0012] In order to represent a functional arrangement in the sense of the aforementioned passive solutions for torque-adaptive field weakening of the rotor of an electrical machine, the object of the present invention is to provide an electrical machine with improved mechanical field weakening, which in particular also effectively converts the partial moments actually occurring on rotor bodies for a desired adjustment and transmits them to the rotor shaft.

[0013] This object is 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 comprises at least a first rotor body with a first group of permanent magnets and at least one second rotor body axially spaced from the first rotor body with a second group of permanent magnets, and coaxially within the first rotor body and the second rotor body, a rotor shaft is coupled to the first rotor body and the second rotor body in a torque-transmitting manner, wherein at least the first rotor body is rotatably mounted on the rotor shaft by means of a mechanical field weakening mechanism against the effect of a first torsional stiffness relative to the second rotor body,wherein the contours of the lever element in contact with the lever contact sections are designed such that in each operating position of the mechanical field weakening mechanism over its entire adjustment path, in sections perpendicular to the rotational axis of the rotor, all contact points between the rotor bodies and the lever element are arranged on a straight connecting line between the tilting axis of the lever element and the rotational axis of the rotor,

[0014] 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.

[0015] An essential aspect of the proposed mechanical field weakening is, among other things, the use of a lever at at least two circumferential locations within the rotor to transmit the partial moments of the two rotor bodies, e.g., to a rotor shaft, while simultaneously providing torsional stiffness between the rotor bodies.

[0016] In particular, a lever element can also be provided that exhibits no or only very slight slippage at the contact points with the rotor bodies and the rotor shaft during the adjustment movement, with correspondingly low friction. This allows for practically negligible hysteresis during the adjustment of the mechanical field weakening mechanism and only very minimal wear on the components moving relative to one another. First, the individual elements of the claimed subject matter of the invention will be explained in the order in which they appear in the claims, and particularly preferred embodiments of the subject matter of the invention will be described below.

[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 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.

[0019] 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.

[0020] The permanent magnets can preferably be incorporated into the pockets of the rotor laminated core. In this case, a single larger rotor magnet designed as a bar magnet or several smaller permanent magnet elements designed as rotor magnets can be provided per pocket. The rotor preferably has a plurality of rotor bodies. Particularly preferably, the rotor bodies are formed from essentially the same parts, in particular essentially identical. It is most preferred for the rotor bodies to be formed from identical, in particular essentially identical rotor laminations. The rotor bodies are therefore particularly preferably formed from a rotor laminated core, which is composed of a plurality of laminated individual laminations or rotor laminations, generally made of electrical steel sheet, which are layered and packaged one above the other to form a stack, the so-called rotor laminated core.The individual laminations can be held together in the rotor core by gluing, welding, or screwing. A rotor core can also, in particular, contain permanent magnets embedded in the pockets of the rotor core or fixed circumferentially to the rotor core.

[0021] According to an advantageous embodiment of the invention, it can be provided that the torsional stiffness is designed as a spring element, in particular as a compression spring or arc spring, which have proven to be particularly suitable.

[0022] According to a further preferred development of the invention, the lever element can also be accommodated in a radially inwardly directed groove extending axially through the rotor shaft. This allows, in particular, a simple pivoting mounting of the lever element in the rotor shaft to be realized.

[0023] Furthermore, according to a likewise advantageous embodiment of the invention, it can be provided that the groove is V-shaped, whereby a particularly low-friction pivoting of the lever element in the groove can be enabled.

[0024] According to a further, particularly preferred embodiment of the invention, the lever element can comprise an ovoidal base body positioned in the groove, which also contributes to low-friction pivoting of the lever element in the groove. Furthermore, the invention can also be further developed such that arcuate claws extending radially outward from the ovoidal base body are formed for engagement with the radially outer lever engagement sections. These claws can also provide friction-optimized engagement of the lever element with the rotor bodies.

[0025] In a likewise preferred embodiment of the invention, it can also be provided that the lever element is secured radially by a retaining ring that can rotate relative to and coaxial with the rotor. This allows for simple assembly and manufacture of the rotor, on the one hand, and a safe and controlled pivoting movement of the lever element relative to the rotor shaft, on the other hand, since the lever element can unintentionally move radially outward under the influence of centrifugal force at high speeds because, for example, the radial components of the normal and frictional forces at the contact points with the rotor disks are not sufficiently high to hold the lever element radially inward in its desired position.

[0026] It may also be advantageous to further develop the invention such that the first rotor body consists of a plurality of rotor disks arranged alternatingly in the axial direction with rotor disks of the second rotor body, wherein the rotor disks of the first rotor body are connected to form a structural unit via first connecting means extending axially parallel to the rotational axis of the rotor, and the rotor disks of the second rotor body are connected to form a structural unit via second connecting means extending axially parallel to the rotational axis of the rotor. The advantage that can be realized in this way is that with an increasing number of rotor disks for a given axial extent of the rotor, an increasingly more uniform weakened field can be formed in the axial direction.As the number of rotor disks increases, the number of contact surfaces between the rotor disks of the first and second group also increases, which likewise contributes to an increasingly more uniform weakened field. According to a further preferred embodiment of the subject matter of the invention, it can be provided that a spacer sleeve is arranged between adjacent rotor disks of the first rotor body on the first connecting means and a spacer sleeve is arranged between adjacent rotor disks of the second rotor body on the second connecting means. This makes it possible to ensure that the axial space between the adjacent rotor disks of one group can be kept free for engagement by the rotor disks of the other group when the rotor bodies are rotated against one another by the field weakening mechanism.

[0027] Finally, the invention can also be advantageously designed such that stop teeth acting in the circumferential direction are formed between the rotor disks, the rotor body, and the rotor shaft, so that the respective rotary end positions of the mechanical field weakening mechanism are defined.

[0028] The invention will be explained in more detail below with reference to figures without limiting the general inventive concept.

[0029] It shows:

[0030] Figure 1 shows an electrical machine in a cross-sectional view,

[0031] Figure 2 shows a rotor with a mechanical field weakening mechanism in a neutral position in a schematic block diagram,

[0032] Figure 3 shows a rotor with a mechanical field weakening mechanism in a first operating position in a schematic block diagram,

[0033] Figure 4 shows a rotor with a mechanical field weakening mechanism in a second operating position in a schematic block diagram, Figure 5 shows a rotor with a mechanical field weakening mechanism in a neutral position in a schematic cross-sectional view,

[0034] Figure 6 shows a rotor with a mechanical field weakening mechanism in a first operating position in a schematic cross-sectional view,

[0035] Figure 7 shows a rotor with a mechanical field weakening mechanism in a second operating position in a schematic cross-sectional view.

[0036] Figure 8 shows an electrical machine in a schematic cross-sectional view,

[0037] Figure 9 shows a rotor in a perspective partial section,

[0038] Figure 10 four operating positions of the lever element in a cross-sectional detailed view,

[0039] Figure 11 shows a lever element in two perspective views, each isolated,

[0040] Figure 12 two cross-sectional views of the rotor,

[0041] Figure 13 shows a rotor with released lever elements and retaining rings in a perspective view,

[0042] Figure 14 two axial sectional views through the rotor.

[0043] Figure 1 shows an electric machine 120 configured as a radial flux machine, in particular for use within a drive train of a hybrid or fully electric motor vehicle, comprising a stator 2 and a rotor 1 separated from the stator 2 by an air gap 22.

[0044] The rotor 1 comprises at least a first rotor body 3 with a first group of permanent magnets 6 and a second rotor body 4 with a second group of permanent magnets 61. This is particularly clearly illustrated by Figures 2-7, which show the two rotor bodies 3, 4. The two rotor bodies 3, 4 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 61 of the second group being identical in the rotor bodies 3, 4.

[0045] The first rotor body 3 and the second rotor body 4 are rotatable relative to each other about a common axis of rotation 119 by means of a mechanical field weakening mechanism 7, counter to the effect of a first torsional stiffness 8.

[0046] The field weakening mechanism 7 comprises a lever element 10 which can be pivoted about a pivot point, wherein the first rotor body 3 can be coupled to a first lever section 31 and the second rotor body 4 can be coupled to a second lever section 32 of the lever element 10 and the first lever section 31 and the second lever section 32 are arranged on opposite sides of the lever 10, so that the first rotor body 3 and the second rotor body 4 can be rotated relative to one another in a targeted manner by tilting the lever element 10 for a desired adjustment of the mechanical field weakening mechanism 7, which can also be clearly seen from the combination of Figures 2-4 and which will be explained in more detail below.

[0047] The field weakening mechanism 7 uses the lever element 10 at at least two circumferential points of the rotor bodies 3, 4 within the rotor 1, also referred to as lever contact sections 12, 13, 15, 16, to transmit the partial torques of the two rotor bodies 3, 4 to the rotor shaft 5, while simultaneously exerting a torsional rigidity 8 between the rotor bodies 3, 4, which can also be clearly seen in the block diagrams in Figures 2-4. The lever element 10 has three regions at different distances from the rotational axis 119 of the rotor 1, in which it is in contact with the two rotor bodies 3, 4 as the two inputs for the torque and the rotor shaft 5 as the output for the torque. The three regions of the lever element 10 are the first lever section 31, the second lever section 32, and the unspecified contact section at the radially inner end of the lever element 10 to the rotor shaft 5.

[0048] Via these defined contact areas of the first and second lever sections 31, 32, the partial moments of the two rotor bodies 3, 4 act on the lever element 10 via the lever contact sections 12, 13, 15, 16 in such a way that the sum is transmitted to the rotor shaft 5 via the contact section (not further designated) at the radially inner end of the lever element 10. At the same time, by tilting the lever element 10, the two rotor bodies 3, 4 are rotated via the lever contact sections 12, 13, 15, 16 against the torsional rigidity 8 that exists between them into the position with the full magnetic field and the magnetic poles aligned, as shown in Figures 3-4. The lever element 10 converts the partial moments, which actually point in the wrong direction for this process, into the desired direction. The torsional stiffness 8 is symbolically represented in Figures 2-4 with compression springs, which are located, for example, in spring windows of both rotor bodies 3,4.However, the torsional stiffness 8 can also be formed in any other known way.

[0049] Figure 2 initially shows the field-weakening mechanism 7 in its neutral position. The field-weakening mechanism 7 is in a field-weakened position, with the magnetic poles of the first group of permanent magnets 6 not aligned with each other relative to the second group of permanent magnets 61, which can be clearly seen from the angular position of the two rotor bodies 3, 4 in Figure 2. In this case, the total torque is lower than a minimum torque required to begin adjusting the rotor bodies 3, 4 relative to each other against the possibly prestressed torsional rigidity 8.The characteristic curve of the torsional stiffness 8 is selected such that when a specified minimum torque is exceeded, the field weakening mechanism 7 begins to adjust from the maximum field-weakened position and when a specified higher torque is reached and exceeded, the full adjustment to the position with full magnetic field has been completed, as is shown, for example, for a motor operation of the electrical machine 120 in Figure 3.

[0050] The first partial torque M1 is transmitted via the lever contact sections 12, 13 of the first rotor body 3, depending on the direction of the total torque, with the first lever contact section 12 of the first rotor body 3 being arranged radially inwardly offset from the second lever contact section 13. Analogously, the second partial torque M2 of the second rotor body 4, depending on the direction of the total torque, is transmitted to the lever element 10 via the lever contact sections 15, 16. The first lever contact section 15 of the second rotor body 4 is arranged radially inwardly offset from the second lever contact section 16.

[0051] If the direction of the total torque changes, for example by changing from motor to generator operation of the electric machine 120, the lever sections 31, 32 of the lever element 10 can change sides and in both operating states the identical relative rotation takes place between the rotor bodies 3, 4 to generate a weakened or full magnetic field, as shown in Figures 3-4.

[0052] In Figure 3, the mechanical field weakening mechanism 7 is in an operating position with a full magnetic field, with the magnetic poles of the permanent magnets 6, 61 aligned, and the lever element 10 in a tilted extreme position. In this case, for example, a total torque during motor operation is greater than a minimum torque for full adjustment against the torsional stiffness 8.

[0053] Figure 4 shows the mechanical field weakening mechanism 7 in a position with a full magnetic field, with the magnetic poles of the permanent magnets 6, 61 aligned, and the lever element 10 in an oppositely tilted extreme position with oppositely acting torque. In this case, for example, a total torque during recuperation in generator mode of the electric machine 120 is greater than a minimum torque for full adjustment against the torsional rigidity 8.

[0054] As can be seen from Figures 5-7, which outline a possible design of the principle shown in Figures 2-4, the rotor shaft 5 is coupled coaxially within the first rotor body 3 and the second rotor body 4 via the lever element 10 in a torque-transmitting manner to the first rotor body 3 and the second rotor body 4, wherein the lever element 10 is pivotably arranged on the rotor shaft 5.

[0055] As shown in Figures 5-7, the lever element 10 extends radially into a first lever window 11 of the first rotor body 3, shown in a partial sectional view. The first lever window 11 has a first lever contact section 12 and a second lever contact section 13 radially spaced therefrom, as indicated by a solid line. The lever element 10 further extends radially into a second lever window 14 of the second rotor body 3. This second lever window 14 has a first lever contact section 15 and a second lever contact section 16 radially spaced therefrom, as indicated by a dashed line.In a first operating position 117, which is shown in Figure 7, the lever element 10 rests on the first lever contact section 12 of the first lever window 11 and on the second lever contact section 16 of the second lever window 14, and in a second operating position 118, which is shown in Figure 6, on the second lever contact section 13 of the first lever window 11 and on the first lever contact section 15 of the second lever window 14.

[0056] The first lever contact section 12 is arranged radially below the second lever contact section 13 of the first lever window 11, and the first lever contact section 15 is arranged radially below the second lever contact section 16 of the second lever window 14. The first lever contact section 12 of the first lever window 11 and the first lever contact section 15 of the second lever window 14 are subject to a greater magnitude of torque transmitted via the first lever element 10 than the second lever contact section 13 of the first lever window 11 and the second lever contact section 16 of the second lever window 14.

[0057] The torsional stiffness 8 is designed in Figures 5-7 as a spring element, in particular as a compression spring or arc spring, whose characteristic curve exhibits a preload torque. Here, too, the characteristic curve of the torsional stiffness 8 is selected such that, upon exceeding a specified minimum torque, the first rotor body 3 and the second rotor body 4 begin to rotate relative to each other from a position with maximally weakened magnetic field. Upon reaching and / or exceeding a specified maximum torque, they have completed a rotation relative to each other into a position with full magnetic field.

[0058] In Figures 5-7, the field weakening mechanism 7 has two opposing, essentially identical lever elements 10, each of which is arranged pivotably distributed over the circumference of the rotor shaft 5.

[0059] Figure 8 shows an electric machine 120, in particular for use within a drive train of a hybrid or fully electric motor vehicle, comprising a stator 2 and a rotor 1 separated from the stator 2 by an air gap 22. The rotor 1 has a first rotor body 3 with a first group of permanent magnets 6 and a second rotor body 4, axially spaced from the first rotor body 3, with a second group of permanent magnets 61, as can be clearly seen in Figure 9.

[0060] Coaxially within the first rotor body 3 and the second rotor body 4, a rotor shaft 5 is coupled to the first rotor body 3 and the second rotor body 4 in a torque-transmitting manner. The first rotor body 3 is rotatably mounted on the rotor shaft 5 by means of a mechanical field weakening mechanism 7, counter to the action of a first torsional stiffness 8, which is designed as a compression spring or arc spring, relative to the second rotor body 4. To transmit the partial moments of the two rotor bodies 3, 4 to the rotor shaft 5, a lever element 10 is used at at least two circumferential points within the rotor 1, with the simultaneous action of the torsional stiffness 8 between the rotor bodies 3, 4. The mechanical field weakening mechanism 7 is explained in more detail below with reference to Figure 10.

[0061] It can be seen from Figure 10 that the contours 17 of the lever element 10 which are in contact with the lever contact sections 12, 13, 15, 16 are designed such that in each operating position of the mechanical field weakening mechanism 7 over its complete adjustment path in sections perpendicular to the rotational axis 18 of the rotor 1, all contact points 19, 20, 21 between the rotor bodies 3, 4 and the lever element 10 are arranged on a straight connecting line 23 between the tilting axis 24 of the lever element 10 and the rotational axis 18 of the rotor 1.

[0062] The lever element 10, comprising an ovoidal base body 26, is received in a radially inwardly directed V-shaped groove 25 extending axially through the rotor shaft 5. The ovoidal, i.e. egg-shaped, shape of the base body 26 can also be clearly seen in Figure 4. The ovoidal base body 26 rolls in the V-shaped groove 25 during operation of the mechanical field weakening mechanism 7. To illustrate this kinematics, Figure 3 shows four operating positions of the lever element 10, with the rotor shaft 5 moving counterclockwise relative to the rotor body 3. For better visibility of the kinematic process when adjusting the field weakening mechanism 7, the reference numerals in the illustrations labeled b, c, d in Figure 11 have been omitted.

[0063] It can be clearly seen from the illustrations in Figure 11 that the corresponding design of the lever element 10, the lever contact sections 12, 13, 15, 16, and the V-shaped groove 25 results in slip-free contact between the lever element 10, the rotor bodies 3, 4, and the rotor shaft 5. The lever element 10, the lever contact sections 12, 13, 15, 16, and the V-shaped groove are geometrically designed such that their contours roll against one another during the tilting of the lever element 10 about a tilting axis 24 and the rotation of the rotor bodies 3, 4 or the rotor shaft 5 about the rotation axis 18 of the rotor 1.For this purpose, the contours 17 of the lever element 10 are designed such that in every position of the mechanical field weakening mechanism over the entire intended movement, viewed in sections perpendicular to the rotation axis 18, all contact points 19, 20, 21 between the rotor bodies 3, 4 and the lever element 10 lie on a straight connecting line 23 between the tilt axis 24 of the lever element 10 and the rotation axis 18 of the rotor 1.

[0064] The lever element thus has three contact areas spaced apart from one another radially by the contact points 19, 20, 21, which are located at different distances from the rotational axis 18 of the rotor 1, with which it is in axial contact with the two rotor bodies 3, 4 as the two inputs for the torque and the rotor shaft 5 as the output for the torque.

[0065] The partial moments of the two rotor bodies 3, 4 act on the lever element 10 via the defined contact areas of the contact points 20, 21 in such a way that the sum is transferred to the rotor shaft 5 via the contact area of ​​the contact point 19 and at the same time, by tilting the lever element, the two rotor bodies 3, 4 are rotated against the torsional rigidity 8 that exists between them into the position with full magnetic field with aligned magnetic poles of the permanent magnets 6, 61, which can be easily understood from the various operating positions as shown in Figure 11.

[0066] Lever element 10 converts the partial moments, which are normally directed in the wrong direction for this process, into the desired direction. The key to this is that the larger of the two partial moments, which determines the direction of the total moment, acts radially further inward on the lever element than the smaller of the two partial moments.

[0067] The rotor bodies 3, 4 each offer lever contact sections 12, 13, 15, 16 at the contact points 20, 21 for contact with the lever element 10 at both distances from the rotation axis 18, which can be clearly seen in Figure 5. When the direction of the total torque changes in motor and generator operation, the contact of the contact points 20, 21 on the lever element 10 can change sides, and in both operating states, the identical relative rotation between the rotor bodies 4, 4 takes place to generate a weakened or full magnetic field.

[0068] The characteristic curve of the torsional stiffness 8 is selected such that when a specified minimum torque is exceeded, the mechanical field weakening mechanism 7 begins to adjust from the position with the maximum weakened magnetic field. Upon reaching and exceeding a specified higher torque, the mechanical field weakening mechanism 7 completes the adjustment to the position with the full magnetic field. The characteristic curve of the torsional stiffness 8 can have a preload torque for this purpose.

[0069] In its non-tilted neutral position, shown in illustration a of Figure 10, the lever element 10, with its bilateral contacts at the contact points 20, 21 with the rotor bodies 3, 4 at their lever contact sections 12, 13, 15, 16, forms a stop for the position with the maximum weakened magnetic field against a magnetic repulsion moment between the rotor bodies 3, 4 and against a preload moment of the torsional rigidity 8. As shown in Figure 5, stop teeth 35, 36 acting in the circumferential direction are formed between the rotor disks 29, 30 of the rotor bodies 3, 4 and the rotor shaft 5, which define the rotational end positions of the rotor shaft relative to the rotor disks 29, 30 and the rotor bodies 3, 4, respectively. If the torque for this position is exceeded, the lever mechanism is bridged by means of the stop teeth and the increased torque is transmitted directly from the rotor bodies 3, 4 to the rotor shaft 5.

[0070] The lever element 10 is shown in two isolated perspective views in Figure 11. These representations clearly show that arcuate claws 27 extending radially outwards are formed on the ovoidal base body 26 for engagement with the radially outer lever engagement sections 13, 16. The circumferential orientations of the arcuate claws 27 alternate in the axial direction. The base body 26 is hollow and has convex arcuate sections 38, 39 arranged alternately in the axial direction, with one group of arcuate sections 38 being assigned to the first rotor body 3 and the other group of arcuate sections 39 being assigned to the second rotor body 4. The radially inner contact point 19 with the lever engagement section 12, 15 of the rotor bodies 3, 4 is located on the radially inner engagement surfaces 41, 42 of the arcuate sections 38, 39 of the lever element 10.The radially outer contact surfaces 43, 44 on the arcuate claws 27 of the lever element 10 provide the contact point 21 with the rotor bodies 3, 4. Radially between them are the contact surfaces 45, 46 on the ovoid base body 26, which form the contact point 20 with the rotor bodies 3, 4. This can also be clearly seen from the combination of Figure 4 and Figure 10.

[0071] The claws 27 and a section of the ovoidal base body 26 engage radially in pockets 37 provided for contacting the rotor bodies 3, 4, which is particularly well understood from Figure 12. The pockets 37 have a mushroom-shaped contour with opening shoulders 47 circumferentially directed inward on the radially inner section. The lever contact sections 12, 15 of the rotor bodies 3, 4 are formed on these opening shoulders 47 of the pockets 37. The radially outer lever contact sections 13, 16 are formed in the pockets 37.

[0072] The lever element 10 is secured radially by a retaining ring 28 which rotates relative to and coaxial with the rotor 1, as shown in Figure 13. This supports the centrifugal force of the lever element 10 in the rotor 1 and secures its radial position. To minimize friction at the support points, the contours of the contacting surfaces between the lever element 10 and the retaining ring 28 can also be designed such that they roll against one another. For this purpose, the axially outer claws of the lever element 10 (not designated in more detail) are provided, which have a design different from the claws 27, as can also be clearly seen in Figure 11. These axially outer claws (not designated in more detail) engage in pockets provided for this purpose in the retaining rings 28.

[0073] The first rotor body 3 consists of a plurality of rotor disks 29, which are arranged alternating in the axial direction with rotor disks 30 of the second rotor body 4. The rotor disks 29 of the first rotor body 3 are connected to form a structural unit via first connecting means 131 extending axially parallel to the rotational axis 18 of the rotor 1, and the rotor disks 30 of the second rotor body 4 are connected to form a structural unit via second connecting means 132 extending axially parallel to the rotational axis 18 of the rotor 1, as can be clearly seen from Figure 14. A spacer sleeve 33 is arranged on the first connecting means 131 between adjacent rotor disks 29 of the first rotor body 3, and a spacer sleeve 34 is arranged on the second connecting means 132 between adjacent rotor disks 30 of the second rotor body 4.

[0074] The connecting means 131, 132 carry guide elements 48 on associated spacer sleeves 33, 34 for one end of a torsional stiffener 8 acting in the circumferential direction. The other end of said stiffener rests in a recess (not further designated) in the respective rotor disk of the rotor body 3, 4. Via the torsional stiffener 8, the guide elements 48, the spacer sleeves 33, 34 and finally the connecting means 131, 132, a torsional stiffener 8 is formed from the two rotor bodies 3, 4 to the respective other rotor body 3, 4, preferably such that the two torsional stiffeners 8 interact in a parallel circuit in the direction of relative rotation, which means a stronger magnetic field. The two rotor bodies 3, 4 are each mounted on the rotor shaft 5 at the end rotor disks with rolling or plain bearings. The rotor 1 can be balanced on two frontal balancing discs 49, which are part of the first rotor body 3

[0075] The invention is not limited to the embodiments illustrated in the figures. The above description is therefore not to be considered restrictive, but rather explanatory. The following claims are to be understood as meaning that a stated feature is present in at least one embodiment of the invention. This does not exclude the presence of further features. Where the claims and the above description define 'first' and 'second' features, this designation serves to distinguish between two similar features without establishing a priority. List of reference symbols

[0076] 1 rotor

[0077] 2 Stator

[0078] 3 rotor bodies

[0079] 4 rotor bodies

[0080] 5 Rotor shaft

[0081] 6 permanent magnets

[0082] 7 Field weakening mechanism

[0083] 8 Torsional rigidity

[0084] 10 Lever element

[0085] 11 lever windows

[0086] 12 Lever system section

[0087] 13 Lever system section

[0088] 14 second lever window

[0089] 15 Lever system section

[0090] 16 Lever system section

[0091] 17 contours

[0092] 18 Rotation axis

[0093] 19 Contact point

[0094] 20 touch points

[0095] 21 Point of contact

[0096] 22 Air gap

[0097] 23 connecting line

[0098] 24 tilt axis

[0099] 25 grooves

[0100] 26 basic bodies

[0101] 27 claws

[0102] 28 Retaining ring

[0103] 29 rotor discs

[0104] 30 rotor discs

[0105] 31 first lever section

[0106] 32 second lever section 33 spacer sleeve

[0107] 34 spacer sleeve

[0108] 35 Stop teeth

[0109] 36 Stop teeth

[0110] 37 pockets

[0111] 38 arch section

[0112] 39 arch section

[0113] 41 contact surface

[0114] 42 contact surface

[0115] 43 contact surface

[0116] 44 contact surface

[0117] 45 contact surface

[0118] 46 contact surface

[0119] 47 Opening shoulder

[0120] 48 guide elements

[0121] 49 balancing discs

[0122] 61 permanent magnets

[0123] 117 Operating position

[0124] 118 Operating position

[0125] 119 axis of rotation

[0126] 120 electric machine

[0127] 131 lanyards

[0128] 132 lanyards

Claims

Claims: Electric machine (120), in particular for use within a powertrain of a hybrid or fully electric motor vehicle, comprising a stator (2) and a rotor (1) separated from the stator (2) by an air gap (22), wherein the rotor (1) comprises at least a first rotor body (3) with a first group of permanent magnets (6) and at least a second rotor body (4) axially spaced from the first rotor body (3) with a second group of permanent magnets (61), and a rotor shaft (5) is coaxially coupled within the first rotor body (3) and the second rotor body (4) in a torque-transmitting manner, wherein at least the first rotor body (3) is rotatably mounted on the rotor shaft (5) against the effect of a first torsional stiffness (8) relative to the second rotor body (4) by means of a mechanical field weakening mechanism (7).characterized in that the contours in contact with lever mounting sections (12, 13, 15, 16), (17) of a lever element (10) are designed such that in every operating position of the mechanical field weakening mechanism (7) over its complete adjustment range in sections perpendicular to the axis of rotation (18) of the rotor (1) all contact points (19, 20, 21) between the rotor bodies (3, 4) and the lever element (10) are arranged on a straight connecting line (23) between a tilting axis (24) of the lever element (10) and the rotation axis (18) of the rotor (1) Electric machine (120) according to claim 1 , characterized in that the torsional stiffness (8) is designed as a spring element, in particular as a compression spring or arc spring. An electric machine (120) according to any one of the preceding claims, characterized in that the lever element (10) is received in a radially inwardly directed groove (25) extending axially through the rotor shaft (5). An electric machine (120) according to claim 3, characterized in that the groove (25) is V-shaped. An electric machine (120) according to any one of the preceding claims, characterized in that the lever element (10) comprises an ovoid base body (26) which is positioned in the groove (25). An electric machine (120) according to claim 5, characterized in that arc-like claws (27) extending radially outward from the ovoid base body (26) are formed for bearing against the radially outer lever contact sections (13, 16).An electric machine (120) according to one of the preceding claims, characterized in that the lever element (10) is secured radially by a retaining ring (28) rotatable relative to the rotor (1) and coaxially to the rotor (1). An electric machine (120) according to one of the preceding claims, characterized in that. the first rotor body (3) consists of a plurality of rotor disks (29) which are arranged in an axial direction alternately with rotor disks (30) of the second rotor body (4), wherein the rotor disks (29) of the first rotor body (3) are connected to form a structural unit via first connecting means (131) extending axially parallel to the axis of rotation (18) of the rotor (1) and the rotor disks (30) of the second rotor body (4) are connected to form a structural unit via second connecting means (132) extending axially parallel to the axis of rotation (18) of the rotor (1). Electric machine (120) according to claim 8, characterized in that a spacer sleeve (33) is arranged between adjacent rotor disks (29) of the first rotor body (3) at the first connecting means (131) and a spacer sleeve (34) is arranged between adjacent rotor disks (30) of the second rotor body (4) at the second connecting means (132).Electric machine (120) according to claim 8 or 9, characterized in that circumferentially acting stop teeth (35, 36) are formed between the rotor disks (29, 30) of the rotor body (3, 4) and the rotor shaft (5).

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