Rotor assembly of an electric machine, in particular for a drive system of a motor vehicle

Abstract

Rotor assembly (1) of an electric machine (10), in particular for a drive system of a motor vehicle, comprising a rotor (2) with a rotor lamination stack (12) and with a bandage (3) radially enclosing the rotor (2). Inner and outer magnet units (14, 24) are embedded in the rotor lamination stack (12). The inner magnet units (14) are each arranged between an inner lamination element (5) and an intermediate lamination element (6), and the outer magnet units (24) are each arranged between the intermediate lamination element (6) and an outer lamination element (7). The outer magnet units (24) each comprise a multi-layered magnet stack (34) with two cuboid magnets (44, 54) of different sizes arranged one above the other in a common receiving pocket (52) in the radial direction.

Description

[0001] The present invention relates to a rotor device of an electric machine, in particular for a drive system of a motor vehicle. The rotor device comprises a rotor with at least one rotor core and at least one bandage radially enclosing the rotor. Magnet units, including inner magnet units and outer magnet units, are embedded in the rotor core.

[0002] In permanently excited synchronous machines (PSMs), the magnetic field in the rotor is generated by a system of one or more magnets. The rotor's magnetic flux is usually constant. To maximize the utilization of the reluctance torque, the magnets are usually buried in the rotor laminations in a V-shaped or trough-shaped configuration. For this purpose, pockets for the buried magnets are formed in the rotor lamination stack. Depending on requirements, one or more layers of such pockets can be implemented.

[0003] In contrast to PSMs with buried magnets, there are also machines with surface magnets. These can generally deliver higher mechanical performance with the same installation space, the same magnet mass, and the same inverter. The disadvantages of this type of machine are typically their lower efficiency and poorer acoustic behavior with regard to torque ripple.

[0004] DE 10 2019 117 686 A1 discloses a PSM with a bandage, which, in addition to the buried magnets, also features surface magnets. The surface magnets are located between the laminated core and the bandage and are secured by the bandage. This utilizes the reluctance torque generated by the buried magnets, while also creating a high flux density in the air gap due to the surface magnets.

[0005] However, the production of such PSMs can be very complex, as, for example, the surface magnets must be curved to match the rotor surface. To reduce the costs associated with curved magnets, rectangular magnets can be used. However, these are limited in size due to the geometric conditions in the rotor.

[0006] In contrast, the object of the present invention is to provide a rotor for a PSM which has as many of the previously discussed advantages as possible and at the same time can be manufactured as inexpensively and economically as possible.

[0007] This object is achieved by a rotor device having the features of claim 1. Preferred developments of the invention are the subject of the subclaims. Further advantages and features of the present invention will become apparent from the general description and the description of the exemplary embodiment.

[0008] The rotor device according to the invention is provided for an electric machine and in particular for a PSM. The rotor device is provided in particular for an electric drive of a motor vehicle and preferably a passenger car. The rotor device comprises a rotor with at least one rotor laminated core and in particular with at least one bandage radially enclosing the rotor. In particular, the rotor has a plurality of rotor poles. Magnet units are embedded or buried in the rotor laminated core. The magnet units comprise inner magnet units and outer magnet units. The rotor laminated core comprises in particular at least one (star-shaped) inner laminated core element and intermediate laminated core elements and outer laminated core elements. The inner magnet units are each arranged between at least one inner laminated core element and at least one intermediate laminated core element.The outer magnet units are each arranged between the at least one intermediate sheet element and at least one outer sheet element. In particular, this results in a rotor with buried magnet units. The outer magnet units (per rotor pole) each comprise at least one multilayer magnet stack. The multilayer magnet stack comprises at least two cuboid magnets of different sizes arranged (stacked) one above the other in a common receiving pocket in the radial direction.

[0009] The rotor device according to the invention offers many advantages. The magnet packs with their two cuboid-shaped magnets offer a significant advantage. Such magnets can be manufactured particularly efficiently. This enables cost savings of around 20% compared to magnet systems with, for example, curved magnets. The special shape and arrangement in the magnet pack also allows more magnetic mass to be accommodated in the rotor, allowing higher power and torque to be achieved within the same installation space.

[0010] It is preferred and advantageous for the radially outer magnet of the magnet stack (relative to the circumferential direction of the rotor) to be wider than the radially inner magnet of the magnet stack. In other words, the inner magnet is preferably narrower than the outer magnet of the magnet stack. This allows the use of economically producible magnets while simultaneously achieving a particularly high magnetic mass in the rotor. The information regarding the width refers in particular to the extent of the magnets of the magnet stack running in the circumferential direction of the rotor or perpendicular to the radius.

[0011] Preferably, the magnets of the magnet stack are arranged parallel to one another. In particular, their main planes are arranged parallel to one another. In particular, the transverse axes of the magnets (running in the circumferential direction) are arranged parallel to one another. In particular, the longitudinal axes of the magnets (running in the axial direction) are arranged parallel to one another. In particular, the vertical axes of the magnets (running in the radial direction) are arranged congruently or parallel to one another.

[0012] It is possible and advantageous for the radially outer magnet of the magnet pack to be higher than the radially inner magnet of the magnet pack in relation to the radial direction of the rotor. However, it is also possible and advantageous for the radially inner magnet of the magnet pack to be higher than the radially outer magnet of the magnet pack. In particular, the magnets of the magnet pack arranged one above the other are of different heights. It is also possible and advantageous for the magnets of the magnet pack arranged one above the other to be of the same height. The information on the height relates in particular to the extension of the magnets running in the radial direction of the rotor or transverse to the circumferential direction.

[0013] In particular, the width of the magnets of the magnet package is greater than their height. In particular, the width is at least twice and preferably three times the height.

[0014] In particular, the receiving pocket, in which the magnets of the magnet stack are arranged together, is delimited by the intermediate sheet element and the outer sheet element. In particular, no sections of the intermediate sheet element and the outer sheet element, and in particular no other sheet structures of the rotor sheet stack, are arranged between the magnets of a magnet stack. The receiving pocket can be open radially outward. It is possible for the receiving pocket to be closed radially outward by sheet structures, for example, webs or the like.

[0015] It is particularly preferred and advantageous that the stacked magnets of a magnet pack are aligned with one another such that the centers of their cross sections lie on a common axis. In particular, this axis runs in the radial direction. In particular, this axis can also be referred to as a radius. In particular, the common axis is congruent with a vertical axis of the magnets. The term vertical axis refers in particular to the extension of the magnets running in the radial direction of the rotor or transversely to the circumferential direction. In particular, the stacked magnets of the magnet pack are centered relative to the radial axis.

[0016] It is also possible and advantageous for the stacked magnets of each magnet stack to be aligned with each other such that the centers of their cross sections are circumferentially offset from the common radial axis. In particular, a so-called asymmetric rotor is then provided.

[0017] It is particularly advantageous and preferred that the stacked magnets of each magnet stack are aligned with each other such that their transverse axes run at right angles and preferably also parallel to the common radial axis. In particular, their transverse axes run at right angles to their vertical axes. The term "transverse axis" refers in particular to the extent of the magnets running in the circumferential direction of the rotor or perpendicular to the radius.

[0018] In particular, the magnets of each magnet stack are arranged one above the other in a pyramid-like manner. In particular, they are arranged one above the other in such a pyramid-like manner that an imaginary apex of the pyramid points radially inward or toward the rotational axis of the rotor. In particular, the center and apex of the pyramid lie on a radially extending axis, preferably on the radial axis on which the centers of the cross-sections of the magnets also lie.

[0019] In a particularly advantageous embodiment, the stacked magnets of the magnet stack each have a maximum height of 8 mm, preferably a maximum height of 7.5 mm, and particularly preferably 7 mm. This enables particularly inexpensive production of the magnets. In particular, the stacked magnets together have an effective height of at least 7 mm.

[0020] In particular, the outer lamination element forms part of the circumference of the rotor lamination stack. In particular, the outer lamination element has a radial outer wall that corresponds to the curvature of the circumference of the rotor lamination stack. In particular, the outer lamination element has a radial inner wall that is planar. In particular, the radial inner wall corresponds to the surface of the radially outer magnet of the magnet stack. The radial outer wall can touch the bandage or be spaced apart from it. The radial inner wall can touch the magnet or be spaced apart from it. In particular, a gap is then provided that is filled with air or potting compound.

[0021] In an advantageous embodiment, the intermediate lamination elements are not connected to the at least one inner lamination element by sheet metal structures of the rotor lamination stack, and in particular not by webs. In particular, the intermediate lamination elements and the inner lamination element are separate components. In particular, the intermediate lamination elements and the inner lamination element are held together (only) by the bandage. However, it is also possible and advantageous for the intermediate lamination elements to be connected to the at least one inner lamination element via sheet metal structures, and in particular via webs. In particular, the intermediate lamination elements and the inner lamination element then form a single-piece sheet metal component.

[0022] In particular, the rotor poles each have at least one outer sheet element and at least one intermediate sheet element. In particular, the outer sheet element of the rotor pole is connected to the intermediate sheet element of the same rotor pole by webs. In particular, the webs are arranged in the region of flux barriers extending along the magnets. In particular, the outer sheet element and the intermediate sheet element of each rotor pole are firmly and preferably integrally connected to one another by the webs. This can further improve handling during production.

[0023] It is also possible that the intermediate lamination elements and the outer lamination elements are not connected to each other by the lamination structures of the rotor lamination stack. In particular, the intermediate lamination elements and the outer lamination elements of each rotor pole are not connected to each other by webs. In particular, the intermediate lamination elements and the outer lamination elements are then separate components.

[0024] In particular, the rotor device comprises at least one bandage which is suitable and designed to hold at least one inner sheet element and the intermediate sheet elements and / or the intermediate sheet elements and the outer sheet elements together under the forces to be expected during normal operation of the rotor device alone (in particular without further aids) and to secure them against loosening and being thrown out (at the speeds to be expected during operation).

[0025] In particular, all magnets of a magnet stack are arranged in a common receiving pocket. In particular, there is no sheet metal structure of the rotor core between the magnets. The inner and outer magnet units are each arranged in at least one separate receiving pocket. In particular, the inner magnet units each comprise at least two (only two) cuboid-shaped magnets per rotor pole. Other magnet geometries are also possible. Flux barriers extend along the (inner and outer) magnet units, which are provided in particular by local recesses in the rotor core.

[0026] In particular, the magnet package consists of at least two, and preferably only two, cuboid-shaped magnets of different sizes arranged one above the other in the radial direction in a common receiving pocket. In particular, the outer magnet units each consist of only one multi-layer magnet package. In particular, the outer magnet units each have only one multi-layer magnet package per rotor pole. For each rotor pole, in particular, at least (only) one inner and at least (only) one outer magnet unit is provided. For each rotor pole, in particular at least (only) one magnet package with at least (only) two magnets arranged one above the other is provided. In particular, the magnet package is designed in two layers.

[0027] The magnets of the magnet packs are, in particular, rod-shaped or prismatic with a rectangular cross-section. The geometry of the magnets can also be described as rectangular-prismatic. The longitudinal axis of the rod or prism runs in the axial direction. In particular, the magnet units have a rectangular basic cross-section in the longitudinal direction and / or transverse to the longitudinal direction. It is possible for the magnets of the magnet pack to be designed as diffusion magnets.

[0028] In particular, the longitudinal axis of the cuboid magnets runs in the axial direction. In particular, their vertical axis runs in the radial direction. In particular, their transverse axis runs in the circumferential direction or transversely to the radial direction or the vertical axis. The cuboid magnets in particular have a rectangular cross-section. The rectangular cross-section can have rounded corners. The cuboid magnets can have rounded corners and / or rounded edges. In particular, the magnets are not curved or bent.

[0029] The magnets of the magnet pack can be arranged one above the other, at least in sections, in contact. The magnets of the magnet pack can be arranged one above the other, at least in sections, in spaced-apart relationship. A gap can be formed between the magnets of the magnet pack. The gap can be filled with potting compound and / or air. In particular, the magnets are in contact with one another with their side surfaces flat. In particular, the magnets of the magnet pack lie flat against one another.

[0030] In particular, an intermediate lamination element and an outer lamination element are provided for each rotor pole. In particular, the star-shaped inner lamination element has a star point for each rotor pole. In particular, the inner lamination element is non-rotatably mounted on a rotor shaft. The rotor device can comprise at least one rotor shaft. In particular, the inner lamination element and the intermediate lamination elements and the outer lamination elements form parts of the circumference of the rotor lamination stack. In particular, they have curvatures on their outer sides that correspond to the curvature of the circumference of the rotor lamination stack.

[0031] In particular, the outer magnet units are the radially outermost magnet units. In particular, the magnets of the magnet stack are the radially outermost magnets and preferably also the only magnets of the outer magnet unit. In particular, only the outer sheet element and in particular no further sheet structures of the rotor sheet stack are located between the bandage and the radially outer magnet of the magnet stack. In particular, the magnet units do not extend to the outside of the rotor. In particular, the magnet units are separated from the outside of the rotor by the outer sheet element. In particular, all provided (inner and outer) magnet units are buried in the rotor sheet stack. In particular, the rotor does not comprise any magnet units that are not arranged beneath a section of the rotor sheet stack. In particular, the rotor does not comprise any surface magnet units.

[0032] It is possible and advantageous for the inner magnet units of each rotor pole to have magnets that are arranged at least partially in a V-shape relative to one another. In particular, the intermediate sheet elements and the outer magnet units and the outer sheet elements of each rotor pole are arranged at least partially between the V-shaped magnets and / or the imaginary extension axes emanating from them. In particular, the magnets of the inner magnet units (with their main plane) are arranged obliquely or inclined to an imaginary radial axis that intersects a rotational axis of the rotor.

[0033] In particular, the rotor has a (maximum) diameter of between 85 mm and 200 mm in the fully assembled state. The features described in the context of the present invention can be particularly advantageously applied to a rotor dimensioned in this way. Other diameters are also possible. In particular, the electric machine is intended as a drive for an electric vehicle and / or hybrid vehicle.

[0034] In particular, the at least one inner lamination element extends further radially outward than the intermediate lamination elements and the outer lamination elements. In particular, the intermediate lamination elements extend further radially inward than the outer lamination elements. In particular, the at least one inner lamination element and the intermediate lamination elements and the outer lamination elements each extend to the radial outer side of the rotor lamination stack. In particular, the at least one inner lamination element and the intermediate lamination elements and the outer lamination elements are arranged flush with one another on the radial outer side. Within the scope of the present invention, the rotor lamination stack does not necessarily have to consist of stacked laminations. In particular, a rotor lamination stack is also understood to mean a rotor body with another suitable structure.

[0035] In particular, the rotor comprises a plurality of rotor poles. In particular, a defined section of the rotor core (with a circular segment-like cross-section) is assigned to each rotor pole. In particular, at least one inner lamination element, at least one intermediate lamination element, and at least one outer lamination element are assigned to each rotor pole. It is possible for the rotor poles to share a common inner lamination element. In particular, the inner magnet units of each rotor pole are separated from one another by the flux barriers. The flux barrier serves, in particular, to inhibit the magnetic flux in the rotor lamination stack.

[0036] Further advantages and features of the present invention will become apparent from the embodiments which are explained below with reference to the accompanying figures.

[0037] The figures show: Fig. 1 a purely schematic representation of a rotor device according to the invention in a sectional view; Fig. 2 a purely schematic detailed representation of a rotor device according to the invention in a sectional view; and Fig. 3 a further purely schematic detailed representation of a rotor device according to the invention in a sectional view.

[0038] The Fig. Figure 1 shows a rotor device 1 according to the invention, such as can be used, for example, in an electric machine 10 (not shown in detail here) designed as a PSM. The rotor device 1 shown here can, for example, be part of a vehicle drive or traction motor of a battery-electric car. The rotor 2 shown here has, for example, a diameter between 100 mm and 170 mm.

[0039] The rotor device 1 comprises a rotor 2, which is only partially shown here for clarity. The rotor 2 is shown here in a sectional view looking in the direction of the intended rotational axis 32 of the rotor device 1. The rotor 2 comprises, for example, six or eight or ten or even more rotor poles 42, of which a single rotor pole 42 is shown in more detail here.

[0040] The rotor 2 comprises a rotor lamination stack 12 and a bandage 3 surrounding the rotor lamination stack 12. The rotor lamination stack 12 comprises an inner lamination element 5 and several intermediate lamination elements 6 as well as outer lamination elements 7. A detailed illustration of the rotor lamination stack 12 of the rotor device 1 shown here is shown in the Fig. 2 shown.

[0041] The rotor 2 is equipped with buried magnet units 4, comprising inner magnet units 14 and outer magnet units 24. The magnet units 4 are here rod-shaped or prismatic and have a cuboid-shaped basic geometry.

[0042] The individual rotor poles 42 here, for example, each have an inner magnet unit 14 with two magnets arranged in a V-shape relative to one another. In addition, the individual rotor poles 42 each comprise an outer magnet unit 24, each with a magnet pack 34. The magnet packs 34 are formed in two layers here and each comprise two cuboid-shaped magnets 44, 54 arranged one above the other in the radial direction. The magnets 44, 54 are housed in a common receiving pocket 52. The receiving pocket 52 is delimited here by the intermediate sheet element 6 and the outer sheet element 7.

[0043] The radially inner magnet 44 of the magnet pack 34 is narrower here than the radially outer magnet 54. The magnets 44, 54 are arranged parallel to one another here. In addition, they are aligned such that the centers of their cross sections lie on a common radial axis 64. Furthermore, the magnets 44, 54 are aligned such that their transverse axes 74 run at right angles to the common radial axis 64. In addition, their transverse axes 74 run parallel to one another. Overall, this results in the pyramid-like arrangement shown here, in which an imaginary tip of the pyramid points radially inward and the center and tip of the pyramid lie on the axis 64. In this way, the geometric conditions of the rotor 2 can be optimally used to accommodate the economically producible magnets 44, 54.

[0044] The radially outer magnet 54 is designed higher than the radially inner magnet 44. Depending on the design of the rotor device 1, the radially inner magnet 44 can also have the same height as the radially outer magnet 54 or be higher than it. The magnets 44, 54 used here each have a maximum height of 7 mm. This enables particularly economical production and allows the use of diffusion magnets, for example. The two-layer arrangement achieves an effective magnet thickness of greater than 7 mm.

[0045] In the variant shown here, the magnets 44, 54 are arranged at a distance from one another in the receiving pocket 52. Depending on the design of the rotor device 1, however, it can also be provided that the magnets 44, 54 lie touching one another on their side surfaces. For this purpose, for example, the height of the radially inner magnet 44 can be adjusted. It is also possible to adjust the size of the receiving pocket 52 accordingly.

[0046] The sheet metal elements shown here (inner sheet metal element 5, intermediate sheet metal element 6, outer sheet metal element 7) are each designed separately and are not connected to each other by webs 8 or comparable sheet metal structures of the rotor core 12. A total of three sheet metal elements are thus provided per rotor pole 42. This results in particularly effective flux barriers 22, which extend along the magnet units 4 and serve to inhibit the magnetic flux. The bandage 3 is provided to ensure the mechanical cohesion of the rotor 2 even at high speeds.

[0047] To prevent kinking or other excessive mechanical stress in the bandage 3 despite the cuboid-shaped, radially outer magnet 54, the outer sheet element 7 is designed here with a curved outer wall 17. The outer wall 17 represents part of the circumference of the rotor core 12 and follows its curvature. The inner wall 27 of the outer sheet element 7 is adapted to the planar surface of the magnet 54. This securely fixes the magnet core 34 in the receiving pocket 52.

[0048] The Fig.Figure 3 shows an embodiment of the previously described rotor device 1. Here, the outer sheet element 7 is connected to the intermediate sheet element 6 by webs 8. The magnets 44, 54 are then inserted, for example, from an axial end face into the receiving pocket 52. Thus, only two separate sheet elements are required per rotor pole 42, namely the inner sheet element 5 and a component composed of the intermediate sheet element 6 and the outer sheet element 7 integrally connected thereto. The bandage 3 is again used to secure the individual components.

[0049] The invention, with its special two-layer magnet stacks 34, allows for significantly more magnetic mass to be accommodated in the rotor 2. This allows for higher power and torque to be achieved with the same installation space requirements. At the same time, the complex manufacturing of curved magnets can be eliminated. List of reference symbols: 1 rotor device 2 rotors 3 Bandage 4 Magnet unit 5 inner sheet element 6 Intermediate sheet element 7 Outer sheet element 8 bridge 10 machines 12 rotor lamination pack 14 Magnet unit 17 Exterior wall 22 River barrier 24 Magnet unit 27 Interior wall 32 axis of rotation 34 Magnet package 42 rotor pole 44 Magnet 52 Recording pocket 54 Magnet 64 Axis 74 Transverse axis QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2019 117 686 A1

[0004]

Claims

[1] Rotor device (1) of an electric machine (10), in particular for a drive of a motor vehicle, comprising a rotor (2) with a plurality of rotor poles (42), with at least one rotor laminated core (12), and with at least one bandage (3) radially enclosing the rotor (2), wherein magnet units (4), comprising inner magnet units (14) and outer magnet units (24), are embedded in the rotor laminated core (12), and wherein the inner magnet units (14) are each arranged between at least one inner plate element (5) and at least one intermediate plate element (6), and wherein the outer magnet units (24) are each arranged between the at least one intermediate plate element (6) and at least one outer plate element (7), characterized bythat the outer magnet units (24) each comprise at least one multi-layer magnet package (34) with at least two cuboid-shaped magnets (44, 54) of different sizes arranged one above the other in the radial direction in a common receiving pocket (52). [2] Rotor device (1) according to the preceding claim, wherein the radially outer magnet (54) of the magnet pack (34) is wider than the radially inner magnet (44) of the magnet pack with respect to the circumferential direction of the rotor (2). [3] Rotor device (1) according to one of the preceding claims, wherein the magnets (44, 54) of the magnet package (34) are arranged parallel to one another. [4] Rotor device (1) according to one of the preceding claims, wherein the magnets (44, 54) of the magnet package (34) are of equal height or unequal height. [5] Rotor device (1) according to one of the preceding claims, wherein the receiving pocket (52) is delimited by the intermediate sheet element (6) and the outer sheet element (7). [6] Rotor device (1) according to one of the preceding claims, wherein the magnets (44, 54) of a respective magnet packet (34) are aligned with one another such that the centers of their cross sections lie on a common radially extending axis (64) or such that the centers of their cross sections are offset in the circumferential direction relative to a common radially extending axis (64). [7] Rotor device (1) according to the preceding claim, wherein the magnets (44, 54) of each magnet package (34) are aligned with each other such that their transverse axes (74) are perpendicular to the common radially extending axis (64). [8] Rotor device (1) according to one of the preceding claims, wherein the magnets (44, 54) of each magnet package (34) are arranged one above the other in a pyramid-like manner such that an imaginary tip of the pyramid points radially inwards. [9] Rotor device (1) according to one of the preceding claims, wherein the magnets (44, 54) of the magnet package (34) each have a height of a maximum of 8 mm and preferably a maximum of 7.5 mm. [10] Rotor device (1) according to one of the preceding claims, wherein the outer sheet element (7) forms part of the circumference of the rotor laminated core (12) and has a radial outer wall (17) which corresponds to the curvature of the circumference of the rotor laminated core (12), and wherein the outer sheet element (7) has a radial inner wall (27) which is planar and corresponds to the surface of the radially outer magnet (54) of the magnet core (34). [11] Rotor device (1) according to one of the preceding claims, wherein the intermediate sheet metal elements (6) are not connected to the at least one inner sheet metal element (5) via sheet metal structures. [12] Rotor device (1) according to one of the preceding claims, wherein the rotor poles (42) each have at least one outer sheet element (7) and at least one intermediate sheet element (6) and wherein the outer sheet element (7) of the rotor pole (42) is connected to the intermediate sheet element (6) of the same rotor pole (42) by webs (8) or wherein the intermediate sheet elements (6) and the outer sheet elements (7) are not connected to one another by sheet structures.

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