Electrical machine

Abstract

The invention relates to an electrical machine (30) comprising a stator (2) and a rotor (1) that is separated from the stator (2) by an air gap (31), wherein the rotor (1) has at least a first rotor body (3) having a first group of permanent magnets (6) and a second rotor body (4) having a second group of permanent magnets (61), wherein the first rotor body (3) and the second rotor body (4) are able to be rotated relative to one another about a common axis of rotation (7) by way of at least one mechanical field attenuation mechanism (32), wherein the mechanical field attenuation mechanism (32) has a loosely inserted, freely rotating spreading roller (8) that rests, in a manner able to roll, on a cam profile (15) able to be rotated about the axis of rotation (7), such that the spreading roller (8) is able to be moved from radially on the inside to radially on the outside via the cam profile (15) when the rotor shaft (5) is rotated about the common axis of rotation (7), and the mechanical field attenuation mechanism (32) also comprises a first needle sleeve (11) having a first outer ring (9) and a second needle sleeve (12), adjacent to said first needle sleeve in the circumferential direction, having a second outer ring (10), wherein the spreading roller (8), which is in contact with the first needle sleeve (11) and the second needle sleeve (12), is moved between the first outer ring (9) and the second outer ring (10) when the rotor shaft (5) is rotated about the common axis of rotation (7).

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 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 about a common axis of rotation by means of at least one mechanical field weakening mechanism.

[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. A disadvantage of permanent 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 is operated 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. Although there are also known ways of generating an air gap field component in permanent-magnet machines by applying a suitable current to the stator. This air gap field component counteracts the excitation field generated by the permanent magnets and thus weakens it, this type of control of the machine results in increased losses, so that the machine can only be operated with reduced efficiency in this range.

[0005] 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 A, FR 283 1345 A1 , EP 108 5644 A2, EP1867030 A1 , DE 10 2016 103 470 A1 , CN 10 460 0929 A and CN10 544 9969 A a rotor of a radial flux machine is known which is divided perpendicular to the axis of rotation into several permanent magnet-equipped, mutually rotatable rotor disks, which, 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 thereto.Active or passive mechanisms are described which claim to be able to switch between these two positions depending on the rotor speed or torque, thus enabling more efficient operation of the electric machine across the entire motor characteristic map. DE 10 12021 101 898 A1 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 in a torque-transmitting manner, while the other sub-rotor is connected via a torsional stiffness in such a way that it can rotate. The torsional stiffness is selected such that at low torque the sub-rotors are in a twisted position with a weakened magnetic field, and at high torque the sub-rotors are in a twisted position with a full magnetic field.DE 10 12021 101 904 B3 claims a structurally designed mechanical module that can be introduced into the interior of the permanent magnet-equipped rotor disks, establishes the described connections of the partial rotors to the rotor shaft, and allows an adjustment characteristic to be defined via the torsional rigidity, which is implemented with springs and roller-equipped cam gears.

[0006] DE 10 2022 106 944 A1 generally describes the principle of a mechanism that uses a lever with simultaneous contact to both partial rotors and the rotor shaft for torque transmission and adjustment.

[0007] DE 10 2022 106 945 A1 describes in detail such a rotor with a lever mechanism and the special feature of sliding friction-free, rolling lever contacts. German document 10 2023 102 105.2 shows a design with separately mounted levers, which are flat and thus inexpensive to manufacture by stamping. Such technical solutions with mounted levers require many individual parts and entail complex assembly steps, which has a negative impact on their cost-effectiveness. The radial expansion of the levers required in these designs requires a comparatively large amount of installation space between the outer diameter of the rotor shaft and the diameter defined by the radially inner end of the magnets. The radially outward expansion of the levers makes it difficult to ensure the speed stability of the stacks made of electrical steel sheet, because insufficient remaining cross-sections at their inner edges may require complex additional measures.The radially inward extension of the levers also limits the possible outer diameter of the rotor shaft. This can complicate both the stability of the rotor shaft under moment load and the realization of direct rotor cooling through a hollow shaft design. Implementing the adjustment mechanism with lever geometries that roll on rotor disk and rotor shaft geometries limits the adjustment parameter of the lever ratio to decreasing curves over the adjustment process. This complicates the optimization of the mechanism with regard to maximum achievable efficiency benefits.

[0008] When load changes between engine and generator operation, the contact areas on the levers, rotor disks, and rotor shaft that are subject to torque flux change. This can lead to noise, wear, and strength problems due to impact.

[0009] It is therefore the object of the invention to provide an electrical machine with a mechanical field weakening mechanism for its rotor that eliminates or at least reduces the aforementioned disadvantages. In particular, the object of the invention is to provide an electrical machine with a cost-effective and robust mechanical field weakening mechanism that, on the one hand, is capable of effectively and frictionally rotating the two rotor sections relative to each other against magnetic repulsion torques with the torque to be transmitted, while, on the other hand, requiring less radial installation space for this purpose.

[0010] 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 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 about a common axis of rotation by means of at least one mechanical field weakening mechanism, wherein the mechanical field weakening mechanism has a loosely inserted, freely rotating spreading roller which rests on a cam profile rotatable about the axis of rotation, so that the spreading roller can be displaced from radially inward to radially outward via the cam profile when the rotor shaft is rotated about the common axis of rotation,and the mechanical field weakening mechanism further comprises a first needle sleeve with a first outer ring and a second needle sleeve with a second outer ring adjacent thereto in the circumferential direction, wherein the spreading roller in contact with the first needle sleeve and the second needle sleeve is displaced between the first outer ring and the second outer ring when the rotor shaft rotates about the common axis of rotation, wherein the first needle sleeve is rotatably mounted on a first axis that is connected to the first rotor body in a torque-transmitting manner, and the second needle sleeve is rotatably mounted on a second axis that is connected to the second rotor body in a torque-transmitting manner, so that when the rotor shaft rotates about the common axis of rotation, a radial offset of the spreading roller outwards against the first needle sleeve and the second needle sleeve can occur and due to the associated spreading apart of the two needle sleeves, including their axes, the rotor bodies,be purposefully rotated relative to each other.

[0011] The electric machine according to the invention thus offers the advantages of precise and efficient control of field weakening, even within compact radial installation space constraints. The spreader roller, which is radially adjustable from the inside to the outside, allows for sensitive adjustment of the relative position of the rotor bodies to one another, thus enabling precise control of the field strength in the machine. This feature increases efficiency, particularly in applications where variable torques and speeds are essential, as is the case with vehicle drives. The described mechanical field weakening also reduces wear, as the mechanical adjustment can be carried out smoothly and precisely.Furthermore, the described configuration enables a more compact design of the electric machine, since the mechanical field weakening can be integrated into the existing rotor body in a particularly simple and space-saving manner, which contributes to the reduction of installation space and weight.

[0012] The mechanical field weakening mechanism uses a radially displaceable spreader roller, which, when the rotor shaft rotates, moves from radially inward to radially outward via the cam profile. This is pressed between the outer rings of the two needle roller bearings. Each of these bearings is firmly connected at its inner diameter via an axis to at least one rotor disk of one or the other rotor body, thus transmitting torque. The resulting spreading apart of the two needle roller bearings and their axes causes the rotor bodies to rotate relative to each other in a torque-leading manner.

[0013] The contact between the cam profile and the expanding roller is preferably rolling, just like the contact between the expanding roller and the outer rings of the needle roller bearings, so that the mechanism operates with correspondingly low friction. The implementation of such low-friction contacts for torque transmission and adjustment with a roller that presses against the needle roller bearings, combined with their low installation height, allows for a radially very compact design compared to a lever mechanism.

[0014] By dimensioning the diameter of the spreader roller as well as the installation and outer diameter of the needle roller bearings, in conjunction with the radial position and shape of the cam profile, highly flexible curves can be set for the kinematic transmission ratio between the rotation of the rotor shaft and the relative rotation between the rotor bodies. This facilitates the optimization of the mechanism with a view to achieving maximum efficiency benefits.

[0015] During load changes between engine and generator operation, unlike with a lever mechanism, the relevant areas of the outer rings for torque transmission preferably remain in contact with the spreader roller. Preferably, there is also permanent contact between the spreader roller and the cam profile in a continuous area.

[0016] The dimensions of the expansion roller diameter as well as the installation and outer diameters of the needle roller bearings, in conjunction with the radial position and shape of the cam profile, are advantageously selected so that contact directions and corresponding forces are always generated on the expansion roller, which firmly press the expansion roller radially outward between the outer rings of the needle roller bearings. The tangents to the contact geometries of the torque transmission direction therefore always intersect radially inward.

[0017] First, the individual elements of the claimed subject matter of the invention will be explained in the order in which they appear in the set of claims, and particularly preferred embodiments of the subject matter of the invention will be described below.

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

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

[0020] For the purposes of the invention, a rotor body is understood to mean the rotor without the rotor shaft. The rotor body is therefore composed, in particular, of a rotor core and the permanent magnets incorporated into the pockets of the rotor core or fixed circumferentially to the rotor core, as well as any axial cover parts for closing the pockets.

[0021] The permanent magnets can preferably be incorporated into the pockets of the rotor core. A single larger rotor magnet designed as a bar magnet or several smaller permanent magnet elements can be provided per pocket.

[0022] The rotor 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 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 packaged one above 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.

[0023] For the purposes of this patent application, a field weakening mechanism is a sophisticated system within the rotor of an electrical machine, particularly designed for use in hybrid or fully electric vehicles, that enables the modulation of the magnetic field strength in the machine's rotor. This is achieved by a controlled adjustment of the relative positions of magnets or magnetic materials, which allows precise adjustment of the induced electrical properties and thus the machine's performance. The function of the field weakening mechanism is to dynamically adjust the magnetic flux density in the machine's rotor according to the performance requirements or operating conditions. This becomes particularly relevant in operating conditions where reduced torque is required at high speed, or when overloading the electrical system is to be avoided.The reduced magnetic field ensures more efficient operation of the machine in these conditions and thus improves the energy efficiency of the entire system.

[0024] The structure of the field weakening mechanism consists primarily of moving components that can be positioned and adjusted relative to one another to control the degree of field weakening. In the case described, the field weakening mechanism includes, among other things, a spreader roller that rolls on a cam profile and needle roller bearings with outer rings, between which the spreader roller is displaced during rotation. The axes on which the needle roller bearings are mounted are connected to the rotor bodies in a torque-transmitting manner, so that adjusting the spreader roller causes a direct rotation of the rotor bodies relative to one another. This relative rotation changes the magnetic flux density in the air gap between the rotor and stator, thus enabling the desired field weakening.

[0025] For the purposes of this patent application, a spreader roller is a mechanical component used within a field weakening mechanism of an electrical machine, particularly in the drive train of a hybrid or fully electric motor vehicle. The spreader roller is designed to roll on a rotatable cam profile and, through its movement along the profile, to enable or support a mechanical action, specifically the rotation of the rotor bodies relative to each other around a common axis of rotation.

[0026] The function of the spreader roller in the described electric machine is to perform a displacement from radially inward to radially outward on the cam profile when the rotor shaft rotates around the common axis of rotation. This displacement enables the two needle rollers in contact with the spreader roller, along with their axes, to spread apart due to the resulting radial offset against the needle roller. This causes the rotor bodies to rotate relative to each other in a targeted manner, which adjusts the magnetic properties and thus weakens the field. This mode of operation enables precise control of the field strength in the rotor, which is an essential requirement for the efficiency and adaptability of modern electric drive machines.

[0027] The structure of the spreader roller is designed to be robust enough to absorb and reliably transmit the mechanical forces and movements that occur during machine operation. The spreader roller is preferably restricted in its axial displacement by adjacent geometries of the rotor shaft or rotor disk, but is otherwise loosely inserted and freely rotating. It interacts directly with the cam profile and the needle roller bearings, which underscores its central role in the field weakening mechanism. With regard to the design of the spreader roller, various configurations, dimensions, and materials are conceivable to ensure optimal adaptation to the specific requirements of the electrical machine. Materials with high strength and toughness are preferred to counteract wear and mechanical stress.These include, for example, steel alloys, titanium, or special plastic composites, which ensure both structural integrity and a lightweight construction. The precise geometric shape and size of the spreader roller can also be adapted to the specific cam profile and spatial conditions within the machine, with both cylindrical and custom-contoured designs being considered. The design of the spreader roller can also include features such as special surface treatments or coatings to optimize service life and reliability under the machine's operating conditions.

[0028] It may also be preferable to select the mass of the spreader roller such that, during operation of the electric machine, the spreader roller causes a speed-dependent adjustment of the field weakening mechanism via the centrifugal force acting on it. This allows for improved actuation of the mechanical field weakening mechanism, as it is then based on two complementary operating principles: the radial offset of the spreader roller via the cam profile and the centrifugal force acting on the spreader roller.

[0029] The spreader roller can be designed as a hollow shaft or a solid shaft.

[0030] For the purposes of this patent application, a needle bush is a component of the mechanical field weakening mechanism that serves as a guide element for mechanical movements within the mechanism and enables or supports the transmission of torque between the spreader roller and the rotor bodies. The function of the needle bush is to act as part of the mechanical field weakening mechanism, enabling the precise and controlled rotation of the rotor bodies relative to each other. The needle bush is positioned in direct interaction with the spreader roller, thereby playing a key role in transmitting mechanical forces required to adjust the relative positioning of the rotor bodies. The needle bush thus contributes significantly to the effective control of the magnetic fields in the rotor, enabling field weakening and thus allowing adjustment of the performance characteristics of the electric machine.

[0031] The needle roller bearing structure typically includes an outer ring and an inner profile designed to enable optimal interaction with other mechanical elements, such as the spreader roller and the associated axle. The needle roller bearing is preferably mounted on an axle that is connected to one of the rotor bodies in a torque-transmitting manner. The bearing can be implemented, for example, using rolling elements, which minimizes friction and thus ensures efficient movement.

[0032] With regard to the design of the needle sleeve, various variations are possible to achieve optimal adaptation to the specific mechanical requirements of the electrical machine. Materials with high mechanical strength and abrasion resistance are preferred to ensure the longevity and reliability of the needle sleeve under operating conditions. Such materials can include, for example, high-quality steels, titanium alloys, or advanced plastic composites. The geometric design and size of the needle sleeve can also vary to enable optimal fit and interaction with the other components of the field weakening mechanism. Furthermore, the design of the needle sleeve can incorporate features such as special coatings or surface treatments to minimize friction and increase wear resistance.

[0033] For the purposes of this patent application, a cam profile is a contour or surface that is part of the field-weakening mechanism. It serves as a guide element that controls the movement and positioning of other mechanical elements of the field-weakening mechanism, in particular the spreader roller. The function of the cam profile is to enable controlled movement of the spreader roller through its shape, which in turn brings about a targeted adjustment of the relative positioning of the rotor bodies and thus field weakening. The cam profile is designed in such a way that it enables a radially aligned movement of the spreader roller from the inside to the outside and vice versa when the rotor bodies rotate or when the spreader roller moves.This movement translates into a rotation of the rotor bodies relative to each other around the common axis of rotation, which influences the magnetic field strength in the rotor and can thus adapt the performance of the electric machine to different operating conditions.

[0034] The design of the cam profile can vary depending on the specific requirements of the machine and the field weakening mechanism. Preferably, the cam profile is applied directly to parts of the rotor, such as the rotor shaft, or is an integral part of it. The shape and pitch of the profile can thus be used to adjust and control the correct function and efficiency of the field weakening mechanism.

[0035] With regard to the designs and materials of the cam profile, various variants are possible and useful to ensure optimal efficiency, precision, and durability. Materials with high strength and wear resistance are preferred, such as hardened steel, special alloys, or even ceramic materials, which offer high resistance to mechanical abrasion and thermal stress. The geometric shape of the cam profile can vary from simple straight or curved shapes to more complex contours that allow finely tuned, variable control of field weakening. In addition, special surface treatments or coatings can be applied to minimize friction between the cam profile and interacting components, such as the spreader roller, thus increasing the efficiency of the system and reducing wear.

[0036] According to a further preferred embodiment of the subject matter of the invention, the cam profile can be provided with a defined radially inner low point, from which the two rotor bodies begin to rotate relative to each other from a position with maximum field weakening. 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, with the spreader roller then reaching a radially outer high point along the cam profile. The dynamic, i.e., speed-dependent, field weakening or field strengthening behavior of the mechanical field weakening mechanism can be adjusted and controlled by the configuration of the cam profile between this low and high point.

[0037] According to an advantageous embodiment of the invention, the diameter of the first needle sleeve and the diameter of the second needle sleeve can be substantially identical, which supports a uniform distribution of loads and forces within the field weakening mechanism. This uniformity promotes reduced wear and a longer service life of all mechanical components involved by minimizing unwanted stress concentrations. This design represents a significant advantage, particularly at high speeds and fluctuating loads, as frequently occur in vehicle drives.

[0038] According to a further preferred development of the invention, it can also be provided that the diameter of the spreader roller is smaller than the diameter of the first needle sleeve and / or smaller than the diameter of the second needle sleeve. The configuration with a smaller diameter of the spreader roller compared to the needle sleeves allows for sensitive and highly precise adjustment of the field weakening. Since the spreader roller acts as the central element of the mechanism, its smaller size enables more efficient transmission of the mechanical movements to the two needle sleeves and thus to the rotor bodies. This constellation supports the fine-tuned adjustment of the field strength and thus improves the performance and efficiency of the machine under different operating conditions.

[0039] Furthermore, according to a likewise advantageous embodiment of the invention, it can be provided that the rotor shaft and the cam profile are formed as a single piece, in particular monolithically. The single-piece or monolithic design of the rotor shaft and cam profile contributes significantly to the structural integrity of the rotor. The single-piece construction avoids potential weak points that could arise from assembly processes or different material connections. This not only increases the mechanical strength and reliability of the system but also reduces manufacturing complexity and the associated costs.

[0040] According to another particularly preferred embodiment of the invention, the first needle sleeve can be mounted on the first axis via a first group of rolling elements and / or the second needle sleeve can be mounted on the second axis via a second group of rolling elements. Mounting the needle sleeves via groups of rolling elements offers advantages in terms of reducing friction and wear. This type of mounting enables more efficient rotary movement of the needle sleeves, which increases the energy efficiency of the electrical machine. Furthermore, distributing the mechanical loads across multiple rolling elements leads to a longer service life of the components and greater reliability of the entire field weakening mechanism.

[0041] The rolling bearing arrangement of a needle roller bushing formed by the rolling elements on the corresponding axle can be single-row or multi-row. The rolling bearing arrangement is preferably configured as a needle roller bearing.

[0042] The rolling bearing preferably has an inner ring raceway, which is advantageously formed integrally, preferably monolithically, with an axle. The inner ring raceway is arranged on the outer surface of the axle and can be made of a metallic and / or ceramic material. It is generally conceivable for the inner ring raceway to be formed in one piece or in multiple pieces, in particular in two pieces.

[0043] The rolling bearing preferably further comprises an outer ring raceway, which is preferably formed integrally, in particular monolithically, with a needle roller bushing. The outer ring raceway is arranged on the inner circumferential surface of a needle roller bushing and can be formed from a metallic and / or ceramic material. It is generally conceivable for the outer ring raceway to be formed in one piece or in multiple pieces, in particular in two pieces. The rolling elements of the rolling bearing are in the shape of a ball or a roller. They roll on the raceways of the rolling bearing and have the task of transferring the force acting, for example, on a radial rolling bearing, from the outer ring to the inner ring and vice versa. Roller-shaped rolling elements can, for example, be selected from the group of symmetrical spherical rollers, asymmetrical spherical rollers, cylindrical rollers, needle rollers, and / or tapered rollers. The rolling elements can be guided in a cage and spaced apart from one another.The cage can be made in one piece or in multiple pieces.

[0044] The rolling elements can roll on the inner ring raceway. For this purpose, the surface of the inner ring raceway can advantageously be designed to be abrasion-resistant, for example, through an appropriate surface treatment process and / or by applying an appropriate additional material layer. The inner ring raceway can be flat or profiled. A profiled design of the inner ring raceway can, for example, serve to guide the rolling elements on the inner ring raceway. A flat design of the inner ring raceway, on the other hand, can, for example, allow a certain degree of axial displacement of the rolling elements on the inner ring raceway.

[0045] The rolling elements can roll on the outer ring raceway. For this purpose, the surface of the outer ring raceway can advantageously be designed to be abrasion-resistant, for example, through an appropriate surface treatment process and / or by applying an appropriate additional material layer. The outer ring raceway can be flat or profiled. A profiled design of the outer ring raceway can, for example, serve to guide the rolling elements on the outer ring raceway. A flat design of the outer ring raceway, on the other hand, can, for example, allow a certain degree of axial displacement of the rolling elements on the outer ring raceway.

[0046] A roller bearing of a needle roller bushing relative to the associated axle can have a seal to prevent lubricant from escaping from the roller bearing or dirt or moisture from entering the roller bearing. It is particularly preferred that the seal be formed from an elastic, particularly preferably rubber-elastic material. The elastic material can preferably consist entirely or partially of an elastomer, with the elastomers again preferably being selected from the group of vulcanizates of natural rubber and silicone rubber.

[0047] In principle, it would also be conceivable for the first needle sleeve and / or the second needle sleeve to be mounted on the respective axes via a plain bearing.

[0048] In a likewise preferred embodiment of the invention, it can also be provided that a plurality of mechanical field weakening mechanisms are provided, which are preferably designed essentially identically. To reduce the pressure in the contacts, further mechanical field weakening mechanisms can be arranged both circumferentially between selected rotor disks and axially between further rotor disks. The provision of a plurality of mechanical field weakening mechanisms, which are preferably designed identically, further enables scaling of the field weakening capability according to the individual requirements of the application of the electrical machine. This modularity and scalability favor application-specific adaptation and optimization of the field weakening performance, whereby the efficiency and performance of the machine can be optimized in different operating modes.

[0049] It may also be advantageous to further develop the invention such that the first rotor body and the second rotor body can be rotated relative to one another about a common axis of rotation, counteracting the effect of a first torsional rigidity. This can contribute to further optimizing the dynamic adaptability of the electric machine. This promotes greater efficiency during operation by adapting to variable load and speed requirements and increases the flexibility of the machine with respect to different operating conditions.

[0050] In a likewise preferred embodiment of the invention, the torsional stiffness can also be provided as a spring element, in particular as a leg spring, leaf spring, compression spring, or arc spring. A leg spring arrangement of the applicant that is particularly preferred in connection with this invention is described in German application 10 2023 102 102.8 and is hereby incorporated by reference into the disclosure of this application.

[0051] According to a further preferred embodiment of the subject matter of the invention, the torsional rigidity characteristic curve can be selected such that, upon exceeding a specified minimum torque, the first rotor body and the second rotor body 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. In this context, it may also be advantageous to further develop the invention such that the torsional rigidity characteristic curve includes a preload torque.

[0052] According to a further preferred embodiment of the subject matter of the invention, the electric machine can be configured as a radial flux machine. Due to the described mechanical field weakening mechanism, the radial flux machine can have a compact design while simultaneously meeting high performance requirements, as required, for example, in modern electric vehicle drives.

[0053] Finally, the object of the invention can also be 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 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 about a common axis of rotation by means of at least one mechanical field weakening mechanism, wherein the mechanical field weakening mechanism has a spreading roller and the mass of the spreading roller is selected such that the spreading roller, during operation of the electric machine, effects a speed-dependent adjustment of the field weakening mechanism via the centrifugal force acting on it,and the mechanical field weakening mechanism further comprises a first needle sleeve with a first outer ring and a circumferentially adjacent second needle sleeve with a second outer ring, wherein the spreader roller in contact with the first needle sleeve and the second needle sleeve is displaced between the first outer ring and the second outer ring, wherein the first needle sleeve is rotatably mounted on a first axis which is connected to the first rotor body in a torque-transmitting manner, and the second needle sleeve is rotatably mounted on a second axis which is connected to the second rotor body in a torque-transmitting manner, so that when a radial displacement of the spreader roller outwards against the first needle sleeve and the second needle sleeve occurs,The resulting spreading of the two needle roller bearings and their axes allows the rotor bodies to be rotated relative to each other in a targeted manner. The rotor shaft is directly connected to the first and / or second rotor body, transmitting torque, particularly for the two operating modes "motor" and "generator."

[0054] This design alternative has the advantage that profiling of the rotor shaft is unnecessary, and the adjustment of the field weakening mechanism can be achieved solely by the centrifugal force acting on the spreader roller during operation of the electric machine. The only requirement is that the rotor shaft, for both motor and generator modes, must be directly connected to the first and second rotor bodies, respectively, in a torque-transmitting manner. This can contribute to a particularly cost-effective electric machine by allowing the use of a rotor shaft that is easier to manufacture.

[0055] The invention will be explained in more detail below with reference to figures without limiting the general inventive concept.

[0056] It shows:

[0057] Figure 1 shows an electrical machine in a cross-sectional view,

[0058] Figure 2 shows a rotor of an electrical machine in a perspective view, Figure 3 shows the rotor known from Figure 2 in a side view,

[0059] Figure 4 shows a cross-sectional view of the mechanical field weakening mechanism of the rotor and a perspective axial section view of the mechanical field weakening mechanism of the rotor in a comparison

[0060] Figure 5 is a cross-sectional view of the mechanical field weakening mechanism of the rotor in a first deflected operating position,

[0061] Figure 6 is a cross-sectional view of the mechanical field weakening mechanism of the rotor in a second deflected operating position.

[0062] Figure 1 shows an electric machine 30 configured as a radial flux machine, in particular for use within a drive train of a hybrid or fully electric motor vehicle, comprising a cylindrical ring-like stator 2 and a cylindrical rotor 1 separated from the stator 2 by an air gap 31, wherein the rotor 1 has 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, and the first rotor body 3 and the second rotor body 4 are rotatable relative to one another about a common axis of rotation 7 by means of at least one mechanical field weakening mechanism 32. This mechanical field weakening mechanism 32 will be explained in more detail with reference to Figures 4-6.

[0063] Figure 2 shows a perspective view of a rotor 1 that is axially divided into rotor bodies 3, 4. These consist of individual rotor disks that alternate in their axial position within the rotor bodies 3, 4. Figure 3 shows a side view of the rotor 1 already known from Figure 2. This shows the cross-sectional view for Figure 4, as well as the diameter 17, which marks the radially inner end of the stacks of electrical sheet metal with the permanent magnets 6, 61.

[0064] Figures 4-6 clearly show that the mechanical field weakening mechanism 32 has a loosely inserted, freely rotating spreading roller 8, which rolls on a cam profile 15 that can rotate about the axis of rotation 7, so that the spreading roller 8 can be displaced from radially inward to radially outward via the cam profile 15 when the rotor shaft 5 rotates about the common axis of rotation 7. The mechanical field weakening mechanism 32 further has a first needle sleeve 11 with a first outer ring 9 and a second needle sleeve 12 adjacent thereto in the circumferential direction with a second outer ring 10, wherein the spreading roller 8, which is in contact with the first needle sleeve 11 and the second needle sleeve 12, is displaced between the first outer ring 9 and the second outer ring 10 when the rotor shaft 5 rotates about the common axis of rotation 7.Here, the first needle sleeve 11 is rotatably mounted on a first axis 13, which is connected to the first rotor body 3 in a torque-transmitting manner, and the second needle sleeve 12 is rotatably mounted on a second axis 14, which is connected to the second rotor body 4 in a torque-transmitting manner. Such that when the rotor shaft 5 rotates about the common axis of rotation 7, a radial offset of the spreading roller 8 outwards against the first needle sleeve 11 and the second needle sleeve 12 can occur. The associated spreading apart of the two needle sleeves 11, 12, including their axes 13, 14, causes the rotor bodies 3, 4 to be purposefully rotated relative to one another. These rotated operating positions of the mechanical field weakening mechanism 32 can be seen in Figures 5-6.

[0065] From Figures 4-6 it can also be seen that the diameter of the first needle sleeve 11 and the diameter of the second needle sleeve 12 are essentially identical, while the diameter of the spreading roller 8 is smaller than the diameter of the first needle sleeve 11 and the second needle sleeve 12. The cam profile 15 is configured such that the radial axis of movement of the spreading roller 8 runs linearly and centrally between the needle sleeves 11, 12. In the embodiment shown, the rotor shaft 5 and the cam profile 15 are formed integrally, in particular monolithically. The first needle sleeve 11 is mounted on the first axis 13 via a first group of rolling elements 33 and the second needle sleeve 12 is mounted on the second axis 14 via a second group of rolling elements 34.

[0066] Figure 4 shows a section perpendicular to the axis of rotation 7 or an axial section through one of the inner rotor disks 18, which belongs to the second rotor body 4. Only the area radially inside the diameter 17 is shown, not the stack of electrical steel with the permanent magnets 6, 61, which is carried by the rotor disk 18. The rotor disk 18 has large recesses 19, which provide space for the installation of the first needle bushing 11 and for the installation and movement of the second needle bushing 12. For the movement of the second axis 14 of the second needle bushing 12, the rotor disk 18 contains elongated holes 20 running in the circumferential direction. In addition, the sectional shape for the axial sectional view is given on the right-hand side of Figure 4.

[0067] The right-hand image of Figure 4 shows a perspective view of a radial stepped section through the axes 13, 14 of the needle sleeves 11, 12. Shown are the inner rotor disk 18, the two axially adjacent rotor disks 21, which are associated with the first rotor bodies 3, and the second rotor disk 4. The short first axis 13 of the first needle sleeve 11 is received in bores 22 of the rotor disk 18, and the long second axis 14 of the second needle sleeve 12 is received in bores 23 of the rotor disks 21.

[0068] Figure 5 shows the mechanical field weakening mechanism 32 in a deflected position of the rotor shaft 5, which corresponds to a load during adjustment in motor operation. The spreading roller 8 was guided radially outward via the cam profile 15 as the rotor shaft 5 rotated. The rolling movement that occurred was transmitted to the outer rings 9, 10 of the needle bushings 11, 12. The forces transmitted to the axes 13, 14 in the rolling contacts cause corresponding moments on the rotor disks 18, 21 and thus on the rotor bodies 3, 4 connected to the rotor disks 18, 21, which are thereby rotated relative to one another against the effect of torsional stiffness and / or magnetic repulsion moments. Figure 6 shows the same, but for a deflected position of the rotor shaft 5, which corresponds to a load during adjustment in generator operation.The relative movement between the rotor bodies 3, 4 remains identical, as do the rolling contacts between the spreader roller 8 and the outer rings 9, 10. Only the area on the cam profile 15, via which torque is transmitted, and the direction of rotation of the rolling movements have changed.

[0069] As can be seen from Figures 5-6, during load changes between engine and generator operation, the relevant areas of the outer rings 9, 10 for torque transmission always remain in contact with the spreader roller 8. There is also permanent contact between the spreader roller 8 and the cam profile 15 in a continuous area. The dimensions of the diameter of the spreader roller 8 as well as the installation and outer diameters of the needle roller bearings 11, 12, in conjunction with the radial position and shape of the cam profile 15, are selected such that contact directions and corresponding forces always result on the spreader roller 8, which stably press the spreader roller 8 radially outwards between the outer rings 9, 10 of the needle roller bearings 11, 12. The tangents to the contact geometries of the torque transmission direction therefore always intersect radially inwards, which is sketched accordingly in Figures 5-6.

[0070] 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

[0071] 1 rotor

[0072] 2 Stator

[0073] 3 rotor bodies

[0074] 4 rotor bodies

[0075] 5 Rotor shaft

[0076] 6 permanent magnets

[0077] 7 axis of rotation

[0078] 8 Spreader roller

[0079] 9 Outer ring

[0080] 10 Outer ring

[0081] 11 Needle sleeve

[0082] 12 needle sleeve

[0083] 13 Axis

[0084] 14 Axis

[0085] 15 cam profile

[0086] 17 diameters

[0087] 18 Rotor disc

[0088] 19 recesses

[0089] 20 elongated holes

[0090] 21 Rotor disc

[0091] 22 Hole

[0092] 23 Hole

[0093] 30 electric machine

[0094] 31 Air gap

[0095] 32 Field weakening mechanism

[0096] 33 rolling elements

[0097] 34 rolling elements

[0098] 61 permanent magnets

Claims

Claims 1. An electric machine (30), 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 (31), wherein the rotor (1) has 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), wherein the first rotor body (3) and the second rotor body (4) are rotatable relative to one another about a common axis of rotation (7) by means of at least one mechanical field weakening mechanism (32), characterized in that the mechanical field weakening mechanism (32) has a loosely inserted, freely rotating spreading roller (8) which rests on a cam profile (15) rotatable about the axis of rotation (7).such that the spreading roller (8) can be displaced from radially inward to radially outward via the cam profile (15) upon rotation of the rotor shaft (5) about the common axis of rotation (7), and the mechanical field weakening mechanism (32) further comprises a first needle sleeve (11) with a first outer ring (9) and a second needle sleeve (12) adjacent thereto in the circumferential direction with a second outer ring (10), wherein the spreading roller (8) in contact with the first needle sleeve (11) and the second needle sleeve (12) is displaced between the first outer ring (9) and the second outer ring (10) upon rotation of the rotor shaft (5) about the common axis of rotation (7), wherein the first needle sleeve (11) is rotatable about a first axis (13) which is connected to the first rotor body (3) in a torque-transmitting manner, and the second needle sleeve (12) is rotatable about a second axis (14) which is connected to the second rotor body (4) in a torque-transmitting manner connected, stored, so that when the rotor shaft (5) is rotated about the common axis of rotation (7), a radial offset of the spreading roller (8) outwards against the first needle sleeve (11) and the second needle sleeve (12) can take place and, as a result of the associated spreading apart of the two needle sleeves (11, 12) together with their axes (13, 14), the rotor bodies (3, 4) are rotated relative to one another in a targeted manner.

2. Electrical machine according to claim 1, characterized in that the diameter of the first needle sleeve (11) and the diameter of the second needle sleeve (12) are substantially identical.

3. Electrical machine according to claim 1 or 2, characterized in that the diameter of the spreading roller (8) is smaller than the diameter of the first needle sleeve (11) and / or smaller than the diameter of the second needle sleeve (12) 4. Electrical machine according to one of the preceding claims, characterized in that the rotor shaft (5) and the cam profile (15) are formed in one piece, in particular monolithically.

5. Electrical machine according to one of the preceding claims, characterized in that the first needle sleeve (11) is mounted on the first axis (13) via a first group of rolling elements (33) and / or the second needle sleeve (12) is mounted on the second axis (14) via a second group of rolling elements (34).

6. Electrical machine according to one of the preceding claims, characterized in that the mass of the spreading roller (8) is selected such that the spreading roller (8) causes a speed-dependent adjustment of the field weakening mechanism (32) during operation of the electrical machine (30) via the centrifugal force acting on it.

7. Electrical machine according to one of the preceding claims, characterized in that a plurality of mechanical field weakening mechanisms (32) are provided, which are preferably designed to be substantially identical.

8. Electrical machine according to one of the preceding claims, characterized in that the first rotor body (3) and the second rotor body (4) are rotatable relative to one another about a common axis of rotation (7) against the effect of a first torsional rigidity.

9. Electrical machine according to one of the preceding claims, characterized in that the electrical machine (30) is configured as a radial flux machine.

10. An electric machine (30), 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 (31), wherein the rotor (1) has 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), wherein the first rotor body (3) and the second rotor body (4) are rotatable relative to one another about a common axis of rotation (7) by means of at least one mechanical field weakening mechanism (32), characterized in that the mechanical field weakening mechanism (32) has a spreading roller (8) and the mass of the spreading roller (8) is selected such thatthat the spreading roller (8) causes a speed-dependent adjustment of the field weakening mechanism (32) during operation of the electrical machine (30) via the centrifugal force acting on it, and the mechanical field weakening mechanism (32) further comprises a first needle sleeve (11) with a first outer ring (9) and a circumferentially adjacent second needle sleeve (12) with a second outer ring (10), wherein the spreading roller (8) is in contact with the first needle sleeve (11) and the second needle sleeve (12) and can be displaced radially between the first outer ring (9) and the second outer ring (10), wherein the first needle sleeve (11) is rotatably mounted on a first axis (13) which is connected to the first rotor body (3) in a torque-transmitting manner, and the second needle sleeve (12) is rotatably mounted on a second axis (14) which is connected to the second rotor body (4) in a torque-transmitting manner, so that when a radial displacement of the spreading roller (8) outwards against the first needle sleeve (11) and the second needle sleeve (12) takes place due to the associated spreading apart of the two needle sleeves (11 , 12) together with their axes (13, 14) the rotor bodies (3,4) be purposefully rotated relative to each other.

Images