Rotor core

Abstract

Magnetically conductive rotor core (100) of a rotor of a permanent magnet excited electrical machine, with • three permanent magnets (101, 102, 103) for each magnetic pole of the rotor, two of which are arranged in a "V"-shaped configuration (101, 102) opening towards a rotor outer surface (104), and the third (103) is arranged tangentially along a circumferential direction (105) of the rotor core (100) at least almost centrally to the "V"-shaped configuration (101, 102), • for each magnetic pole of a group of recesses (111, 115, 116, 117, 118, 119, 120, 121; 122, 127, 128, 129, 130; 131, 136, 137, 138, 139, 140, 141; 142; 144) in the rotor core (100) arranged at least almost symmetrically to the “V”-shaped configuration (101, 102), each group comprising: ◯ a large recess (111; 122; 131; 142) located ▪ radially in a region of the rotor core (100) between a central rotor shaft opening (109) and at least nearly the radially inwardly directed ends of the “V”-shaped configuration (101, 102) and ▪ extends in the circumferential direction (105) within an angular range (107) covered by this “V”-shaped design (101, 102), and ◯ at least three small recesses (115, 116, 117, 118, 119, 120, 121; 127, 128, 129, 130; 136, 137, 138, 139, 140, 141; 144) which border in a honeycomb-like manner at least in the radial direction at least outwards on edges (112, 113; 123, 124, 125; 132, 133, 134; 143) of the large recess (111; 122; 131; 142), ◯ wherein a radial cross-sectional area of the large recess (111; 122; 131; 142) is at least twice the radial cross-sectional areas of each of the small recesses (115, 116, 117, 118, 119, 120, 121; 127, 128, 129, 130; 136, 137, 138, 139, 140, 141; 144).

Description

The invention relates to a rotor core. The invention further relates to a rotor having such a rotor core, an electric machine having such a rotor and a vehicle having such a machine.Prior ArtWO 2005 / 117 235 A1 discloses a rotor for an electric machine. The rotor comprises magnetically conductive rotor laminations on a rotor shaft. Permanent magnets are embedded in the rotor laminations, which are aligned on both sides of a magnetic pole in the direction of rotation and the radial direction of the rotor. In each magnetic pole, the permanent magnets are arranged in a "V"-shaped configuration opening toward a rotor outer surface, i.e., radially outward, in the axial direction of the rotor. In addition to a central opening for the rotor shaft, the rotor laminations have a number of further openings through which the rotor structure is intended to be lighter. These further openings are arranged along a circumferential direction of the rotor radially between the permanent magnets and the rotor shaft in such a way that a web extending in the radial direction remains in the rotor plate between each two of the further openings, which web ends radially outwards at the radially inward point of each two permanent magnets arranged in the "V"-shaped configuration.Thus, there is provided a rotor for an electric machine formed of laminated laminations substantially perpendicular to the axis of rotation of the rotor, characterised in that the rotor comprises at least one first laminated core located close to the central axis of rotor rotation and having cavities substantially the same width as the rotor poles on the side of the rotor periphery, and at least one second laminated core fitting into the cavities of the first laminated core and extending substantially up to the rotor periphery, thereby forming the outer surface of the rotor pole, and in that a space extending up to the outer periphery of the rotor is arranged between the first and second laminated cores into which permanent magnets are insertable for magnetizing the motor.DE 10 2013 219 020 A1 discloses an electric rotary machine having a rotor with internal permanent magnets, wherein it is an object to provide a low-cost electric rotary machine with high energy density that performs high-performance operation in a drive mode while reducing the use amount of the permanent magnets.Thus, an internal permanent magnet (IPM) rotary electric machine is provided, comprising: a stator configured to receive stator windings; a rotor rotatable with respect to the stator; permanent magnets in the rotor that form magnetic poles; and openings having a low permeability, each of which replaces the portion located in a predetermined range of one of the permanent magnets that would generate directional magnetic flux lines such that magnetic flux lines emanating from the stator would be cancelled near a long axis of one of the magnetic poles if the permanent magnet were located in the predetermined range. A plurality of sets of permanent magnets are embedded in the rotor, each set having a pair of permanent magnets per pole arranged in a "V" shaped configuration opening toward an outer periphery of the rotor. For the permanent magnets of each pair, the rotor is formed with a set of apertures arranged in a "V"-shaped configuration opening toward the outer periphery to firmly receive the permanent magnets each having the same rectangular cross-sectional profile along its length and extending in the axis direction along the rotor axis by allowing their corners to be inserted into the set of apertures.The apertures of each set include magnet apertures configured to receive and enclose the permanent magnets of the corresponding pair, and apertures disposed over each of the permanent magnets and separated from each other in the direction of its width and serving as flux barriers to prevent the magnetic flux from rotating about the permanent magnet. Each set of openings in a "V"-shaped configuration has a central bridge extending between the openings between the permanent magnets of each pair in a radial direction from the rotor axis to connect the inner and outer edges defining the opening to hold the permanent magnets in position against the centrifugal force upon rotation of the rotor.JP 2015-173 545 A discloses a rotor for an electric machine. In the rotor, a plurality of sets of permanent magnets are embedded in corresponding slots. One set comprises three permanent magnets. Two of these permanent magnets are arranged in a "V"-shaped configuration which opens toward the outer periphery of the rotor. In the open end of the "V"-shaped configuration, i.e. radially on the outside, a third permanent magnet is arranged. This is arranged on or parallel to a line extending between the radially outer ends of the "V"-shaped configuration of the two permanent magnets. The three permanent magnets thus form a triangle open at the corners. Within this triangle, a number of recesses are provided. These recesses serve for guiding and conducting a coolant. The distance of the recesses from the magnets is described with regard to a loss of torque.JP H10-51 984 A likewise has a rotor of an electric machine as prior art from JP 2015-173 545 A. An arrangement of three permanent magnets is also known as shown in JP 2015-173 545 A, but without recesses in the interior of the triangle open at its corners.Efforts are directed to keeping the outer diameter of the rotor shaft small or to further reduce it. However, this means that the central opening for the rotor shaft in the rotor laminations is to be reduced to the same extent and the volume of the rotor laminations is therefore to be increased. If the rotor laminations and thus a rotor core formed with these rotor laminations are manufactured from a material having a greater density than the rotor shaft, the reduction in the outer diameter of the rotor shaft results in an increase in the mass and the moment of inertia of the rotor, which is undesirable.Presentation of the Invention: Object, Solution, AdvantagesThe present invention has an object of preventing such undesirable increase in mass and inertia moment of the rotor, particularly, forming the rotor core so that mass and inertia moment of the rotor are further reduced as much as possible.This object is achieved by a rotor core having the features of claim 1.Accordingly, the invention provides a magnetically conductive rotor core of a rotor of a permanent magnet-excited electric machine, comprising• For each magnetic pole of the rotor, three permanent magnets, two of which are arranged in a "V"-shaped configuration opening towards an outer surface of the rotor, i.e. radially outwards, and the third permanent magnet arranged tangentially along a circumferential direction of the rotor core at least nearly centrally to the "V"-shaped configuration, the third permanent magnet being arranged tangentially along the circumference of the rotor core in the opening of the "V"-shaped configuration, so that all three permanent magnets are arranged towards one magnetic pole in a triangular configuration;• A group of recesses in the rotor core arranged in a radial direction, each group comprising: a large recess which is formed.▪ radially in a region of the rotor core between a central rotor shaft opening, i.e. a central opening of the rotor core for a rotor shaft, and at least almost the radially inwardly directed ends of the "V"-shaped configuration, i.e. of the two permanent magnets of the magnetic pole arranged in a "V"-shaped configuration, and▪ extend in the circumferential direction within an angular range covered by this "V"-shaped configuration, and◯ at least three small recesses which adjoin boundary areas of the large recess in a honeycomb manner at least outwards at least in the radial direction, wherein this boundary area is formed according to the invention in such a way that the boundary areas of the recesses adjoining one another are separated from one another by, preferably magnetically conductive, webs, i.e. wherein these webs form the boundary areas of the recesses adjoining one another;◯ wherein a radial cross-sectional area of the large recess is at least twice the radial cross-sectional area of each of the small recesses.In this embodiment of the rotor core according to the invention, all three permanent magnets arranged in the triangular arrangement with respect to one of the magnetic poles each are moved outwards at least almost as far as the immediate vicinity of the circumference, as seen in the radial direction, i.e. are arranged radially as far outwards as possible in the rotor, wherein as little rotor core material remains between a circumferential surface of the rotor core and radially outward-pointing sections of the permanent magnets as is required to maintain the mechanical strength of the rotor with respect to torques and / or centrifugal forces during normal operation. As a result, leakage magnetic fluxes are reduced and high torque is obtained.It has been found that, by this magnet arrangement, the magnetic fluxes for generating the torque of an electric machine equipped with a rotor having a rotor core thus formed extend substantially in a space surrounded by the three permanent magnets arranged to each of the magnetic poles in the triangular arrangement. Furthermore, radially radiating magnetic flux regions extend from the periphery of the rotor core toward the rotor shaft in the radial direction along the transitions of each of two adjacent angular regions assigned to two adjacent magnetic poles and covered in the circumferential direction by the "V"-shaped configuration, i.e. where each of two of the triangular arrangements of permanent magnets adjoin in the circumferential direction of the rotor core, and furthermore there is a magnetic flux region which extends at least largely in the circumferential direction of the rotor core along the central rotor shaft opening, i.e. the central opening of the rotor core for the rotor shaft. In contrast, in a space portion of the rotor core between the three permanent magnets arranged to each of the magnetic poles in the triangular arrangement, the radiation-shaped magnetic flux portions, and the magnetic flux portion along the central rotor shaft opening, small magnetic fluxes occur in operation.Following this finding, magnetically non-conductive recesses are now arranged in this spatial region of the rotor core surrounded by the flux regions mentioned, in particular configured as air cavities. According to the invention, a group of recesses is provided in each of these spatial regions, i.e. to each of the magnetic poles, and furthermore these recesses of each group are arranged at least almost symmetrically to the central axis of the "V"-shaped configuration extending radially from the axis of rotation of the rotor, i.e. to the axis of symmetry of the "V"-shaped pair of permanent magnets. In this case, within each of the groups of recesses, three or more recesses, referred to here as small recesses, are grouped around a recess, referred to here as a large recess, which in this respect forms a central recess of the group. The small recesses are arranged in honeycomb form around the large recess, wherein the small recesses are arranged adjacent to the large recess radially outwards and / or inwards. The webs between the recesses form, as a result of the honeycomb arrangement of the recesses, a mechanically particularly stable and at the same time lightweight honeycomb construction which enables a high mechanical strength of the rotor core with a low rotor mass.The dimensions of the large and the small recesses are defined according to the invention in that each of the small recesses has a cross-sectional area, determined in a radial plane of the rotor core, which corresponds at most to half the cross-sectional area of the large recess determined in this radial plane.In this case, the large recess furthermore extends from the "V"-shaped configuration, i.e. from the "V"-shaped arranged pair of permanent magnets of the magnetic pole, starting at least substantially, advantageously completely, radially inward in the direction of the rotor shaft opening. At least one of the small recesses can extend in the radial direction between the permanent magnets of the "V"-shaped configuration or be arranged there.In the rotor core formed according to the invention, a radially extending support and flux-conducting structure made of rotor core material is thus provided between each two magnetic poles, i.e. between each two "V"-shaped configurations. Between each two of these support and flow guiding structures, one of the honeycomb structures is arranged. Depending on the desired load on the rotor core, in particular the honeycomb structure can be dimensioned differently. For example, for an embodiment designed for high rotational speeds, the recesses can be kept smaller and positioned closer to the "V"-shaped configuration, i.e. radially further outwards, than for a lightweight embodiment which has larger recesses in comparison therewith; in particular, in a lightweight embodiment, the large recess extends radially very much further towards the rotor shaft opening.The invention enables a rotor core to be formed with a low mass and a low moment of inertia with high strength. Thus, for example, high-speed electric machines with high torque, high power and high acceleration capacity can be formed. In particular when using such electric machines in vehicles, preferably road vehicles, with an electric traction drive, increased driving powers can be achieved with lower energy consumption and thus a longer range in particular in battery-operated vehicles.Advantageous embodiments of the invention are characterized in the dependent claims.According to a preferred development of the rotor core according to the invention, the large recess adjoins the radially inwardly directed ends of the permanent magnets of the "V"-shaped configuration with two radially outwardly directed edges thereof. This enables good utilization of the space area provided for the large recess in the rotor core with good mechanical strength, wherein the extension of the large recess towards the rotor shaft opening is selected depending on the strength required, in particular against centrifugal forces.In a further preferred embodiment of the rotor core according to the invention, the large recess is formed with at least approximately square-shaped, at least approximately straight-line borders arranged at least approximately in the form of a hexagon, and small recesses adjoin at least four of these borders. This hexagonal honeycomb construction enables a particularly high strength against centrifugal forces and is therefore preferred for high-speed drives. For such high-speed drives, the size ratio of the cross-sectional areas of the small recesses to the cross-sectional area of the large recess is advantageously selected to be relatively large, i.e. for at least some of the small recesses, preferably close to a factor of 0.3 to 0.5.In a further preferred embodiment of the rotor core according to the invention, at least one of the small recesses also adjoins the large recess radially inward.According to another embodiment of the rotor core according to the invention, the large recess is formed with at least sectionally rounded rims, and at least the radially inwardly directed ends of the permanent magnets of the "V"-shaped configuration adjoin at least one of these at least sectionally rounded rims. This embodiment is preferably selected for achieving the smallest possible rotor masses in a lightweight construction, wherein a particularly balanced force transmission is obtained through the fillets. It should be added that, even in the case of a honeycomb construction with straight borders at their transition regions from one border to the other, i.e. at nodes of the webs, fillets-preferably with a small dimension compared to the length of the borders-can be provided for improved force transmission and avoidance of excessively high stresses in the material.In a further preferred embodiment of the rotor core according to the invention, a small recess is arranged at the transition of two adjacent angular ranges assigned to two adjacent angular ranges of the magnetic poles and covered in the circumferential direction by the "V"-shaped configuration, preferably with a rounded, particularly preferably circular boundary. Advantageously, such a small recess, which is provided in the space region between two magnetic poles each, i.e. between two "V"-shaped configurations each, in which support and flux-guiding structure of rotor core material extending radially there is provided, is combined with the embodiment of the rotor core according to the invention, in which the large recess is formed with at least sectionally rounded-off rims; in particular, these at least sectionally rounded-off rims are arranged adjacent to the large recess of said small recess. The weakening of the radial support and flux guiding structure made of rotor core material by the small recess is thus counteracted insofar as the forces in the support and flux guiding structure are guided particularly uniformly around the small recess by the rounded borders.In a further preferred embodiment of the rotor core according to the invention, the radial cross-sectional area of the large recess is at least three times, preferably at least five times, particularly preferably at least seven times, the radial cross-sectional areas of each of the small recesses. This dimensioning is selected in particular in the case of the lightweight construction if a design for the highest rotational speeds and centrifugal forces is not required. This makes it possible to save a particularly large amount of rotor material.For a further mass reduction of the rotor material, apart from the small recesses described above, further small recesses can be provided which advantageously do not directly adjoin the large recess, but rather one or more of the small recesses described above directly adjoining the large recess. By such an expansion of the honeycomb construction, a further saving of rotor material and thus weight and moment of inertia is achieved with at least substantially the same strength. Preferably, these further small recesses extend radially outwards as viewed from the above-described small recesses and the large recess. These further small recesses can be provided both in the case of dimensioning for high rotational speed and in the case of the lightweight construction.The above-mentioned object is furthermore achieved by a rotor of a permanent magnet-excited electric machine, characterized by a rotor core of the above-described configuration. Such a rotor is light in weight, has a low moment of inertia and is advantageously usable for high-performance drives with high acceleration capacity.The object mentioned above is furthermore achieved by a permanent magnet-excited electric machine which is characterized by a rotor of the type specified above and / or by a rotor core of the above-described design. Such a machine is preferably usable for traction drives of vehicles, in particular road vehicles with electric drives, preferably battery-powered drives. The machine according to the invention allows a drive with high rotational speed with high acceleration capacity, high torque and low weight, so that by a possible reduction of the electrical power consumption with unchanged or increased mechanical power output, a better utilization of the energy stored in a traction battery is possible. In a vehicle which likewise achieves the object mentioned above, in particular a road vehicle which is equipped with a permanent-magnet-excited electric machine of this type and / or a machine having a rotor of the type described above and / or having a rotor core of the type described above, it is thus possible to achieve an increased acceleration capacity and a longer range with a battery charge.Brief Description of the DrawingsIn the drawing, in which corresponding elements are provided with the same reference numerals in all figures and in which a repeated description of these elements is omitted, the following are shown: FIG. 1 shows a representation of a rotor core in a roughly schematic axial view with three permanent magnets per magnetic pole, FIG. 2 shows a detail, roughly schematic illustration of the rotor core according to FIG. 1 with a group of recesses according to a first embodiment of the invention, FIG. 3 shows a detail, roughly schematic illustration of the rotor core according to FIG. 1 with a group of recesses according to a modification of the first embodiment of the invention according to FIG. 2, FIG. 4 shows a detail, roughly schematic illustration of the rotor core according to FIG. 1 with a group of recesses according to a second embodiment of the invention, FIG. 5 shows a detail, roughly schematic illustration of the rotor core according to FIG. 1 with a group of recesses according to a third embodiment of the invention, and FIG. 6 shows a detail, roughly schematic illustration of the rotor core according to FIG. 1 with a group of recesses according to a fourth embodiment of the invention.The exemplary embodiments of the invention illustrated in the drawing are described in more detail below.Preferred Embodiment of the InventionIn FIG. 1, reference numeral 100 denotes a rotor core as used as a basis for the embodiments of the invention explained below. The rotor core 100 is shown in an axial view, i.e. a view in the direction of a rotation axis 110 of the rotor core 100 and thus of a rotor of a permanent magnet-excited electric machine constructed therewith. Here, the rotor core 100 has, for example, ten magnetic poles. Three permanent magnets 101, 102, 103 are provided for each magnetic pole of the rotor core 100 or of the rotor constructed therewith, two of which 101, 102 are arranged in a "V"-shaped configuration 101, 102 which opens toward a rotor outer surface 104, i.e. radially outwards, and the third 103 is arranged tangentially along a circumferential direction 105 and therefore along the rotor outer surface 104 of the rotor core 100 at least approximately centrally with respect to a radial central axis 106 of the "V"-shaped configuration 101, 102. All permanent magnets 101, 102, 103 are placed close to the rotor outer surface 104 as far as the mechanical stability of the rotor core 100 makes possible. In the circumferential direction 105 of the rotor core 100, the "V"-shaped configuration 101, 102, i.e. the configuration of the two permanent magnets 101, 102, covers an angular range 107 which is equal to the pole pitch of the rotor core 100. The transitions of each two adjacent angular ranges 107 assigned to two adjacent ones of the magnetic poles and covered in the circumferential direction 105 by the "V"-shaped configuration 101, 102, i.e. the locations where each two of the triangular arrangements of permanent magnets 101, 102, 103 adjoin one another in the circumferential direction 105 of the rotor core 100, are denoted in FIG. 1 by section lines 108. The representation of structural details of the rotor core 100 is omitted in FIG. 1 and only the arrangement of the permanent magnets 101, 102, 103 relative to the outer circumference of the rotor core 100, i.e. to the rotor outer surface 104, and to the rotor shaft opening 109 is reproduced.FIG. 2 shows a part of the rotor core 100 cut out along the section lines 108 according to FIG. 1, i.e. one of the angular ranges 107 with the three permanent magnets 101, 102, 103, enlarged in a roughly schematic illustration. In this angular range 107 of the rotor core 100, a group of recesses according to a first embodiment of the invention is arranged.The group comprises a large recess 111 which is formed hexagonally with at least predominantly rectilinear rims and is arranged symmetrically with respect to the radial central axis 106; i.e. the rims 112 pointing in the circumferential direction 105 are rectilinear, the rims 113 pointing radially inward or outward are slightly curved following the rotor outer surface 104, in particular their curvature is smaller, i.e. has a larger radius than that of the rotor outer surface 104. The large recess 111 extends radially in a region of the rotor core 100 between the central rotor shaft opening 109 and at least nearly the radially inward ends of the "V"-shaped configuration, i.e., the permanent magnets 101, 102. In particular, the permanent magnets 101, 102 abut with their radially inwardly directed narrow sides on the radially outwardly directed edges 112 facing in the circumferential direction 105 via webs 114, which are dimensioned as thin as possible, taking into account a required mechanical strength, in order here to avoid or keep a magnetic short circuit low. In the circumferential direction 105, the large recess 111 extends within an angular range covered by the "V"-shaped configuration 101, 102, i.e. within the angular range 107, in particular within an angular range narrower than the latter, bounded by the radially innermost corners of the permanent magnets 101, 102.The group of recesses further comprises a total of five small recesses 115, 116, 117, 118, 119 which adjoin the borders 112 and 113 of the large recess 111 in honeycomb form in the radial direction inward and outward and also in the circumferential direction 105 here. Each of the recesses is separated from an adjacent one of the other by webs which are likewise not separately designated here. All these webs are dimensioned as thin as possible, taking into account a required mechanical strength.A first 115 of these small recesses adjoins the large recess 111 along the radially inwardly facing boundary 113, and a second 116 of these small recesses adjoins the large recess 111 along the radially outwardly facing boundary 113. While the second small recess 116 is at least substantially rectangular, the contour of the first small recess 115 fits with an arc shape-also known as a "banana shape"-of a curvature of the radially inwardly pointing boundary 113 of the large recess 111. The first and second small recesses 115, 116 are configured symmetrically with respect to the radial center axis 106.A third 117 and a fourth 118 of the small recesses adjoin the radially inward-facing ones of the borders 112 of the large recess 111 facing in the circumferential direction 105; they are designed and aligned at least substantially square and symmetrically with respect to the radial center axis 106.A fifth 119 of the small recesses adjoins the second small recess 116 radially outwards and is likewise of rectangular configuration, but its cross-sectional area in the radial plane is a quarter or less of the cross-sectional area of the second small recess 116. Further, the radial cross-sectional area of the large recess 111 is at least twice the radial cross-sectional area of each of the small recesses 115, 116, 117, 118, 119.The rotor core 100 according to FIG. 2 is designed for a high-speed drive with high centrifugal forces. In this case, the arrangement of the recesses 111, 115, 116, 117, 118, 119 concentrates in a radially central spatial region of the rotor core 100 close to the radially inwardly directed corners of the "V"-shaped configuration 101, 102, whereas a region of solid rotor core material is provided along the rotor shaft opening 109, the dimension of which region in the radial direction is equal to or virtually equal to the radial extent of the group of recesses 111, 115, 116, 117, 118, 119. In the example according to FIG. 2, these dimensions correspond to one another.FIG. 3 shows the angular range 107 cut out along the section lines 108 according to FIG. 1 with the three permanent magnets 101, 102, 103, enlarged in a roughly schematic illustration, wherein a group of recesses 111, 115, 116, 117, 118, 119, 120, 121 according to a modification of the first embodiment of the invention shown in FIG. 2 is arranged in this angular range 107. Compared to the embodiment according to FIG. 2, the group of recesses 111, 115, 116, 117, 118, 119, 120, 121 is extended by a sixth 120 and a seventh 121 recess, which are triangular and are arranged symmetrically with respect to one another with respect to the radial center axis 106 at acute-angle corners between one of the permanent magnets 101 and 102 each and the narrow sides, i.e. short borders pointing in the circumferential direction 105, of the second small border 116. This allows a further reduction in mass.FIG. 4 shows the angular range 107 with the three permanent magnets 101, 102, 103 enlarged in a roughly schematic illustration, wherein a group of recesses according to a second embodiment of the invention is arranged in this angular range 107. This second embodiment is a lightweight construction of the rotor core 100, which has larger recesses compared to the constructions according to FIGS. 2 and 3 for a high-speed drive; in particular, in this lightweight construction a large recess 122 extends radially further both towards the rotor shaft opening 109 and in the circumferential direction 105 towards the cutting lines 108 and thereby projects in the circumferential direction 105 beyond the radially inwardly directed corners of the permanent magnets 101, 102.The large recess 122 is again formed hexagonally with at least predominantly rectilinear borders and is arranged symmetrically with respect to the radial central axis 106. Here, the borders 123 pointing in the circumferential direction 105 and the border 124 pointing radially outwards are straight, whereas the border 125 pointing radially inwards is slightly curved in the opposite direction to the rotor outer surface 104; in particular, its curvature is smaller, i.e. has a larger radius than that of the rotor outer surface 104. The permanent magnets 101, 102 abut with their radially inwardly directed narrow sides against the radially outwardly directed edges 123 facing in the circumferential direction 105 via webs 126, which are again dimensioned as thin as possible, taking into account the required mechanical strength, in order here to avoid or keep a magnetic short circuit low.The large recess 122 is part of a group of recesses which furthermore has a total of four small recesses 127, 128, 129, 130, which adjoin the rims 123 and 124 of the large recess 122 in a honeycomb shape in the radially outward direction and here also in the circumferential direction 105. Each of the recesses is separated from an adjacent one of the other by webs which are likewise not separately designated here. All these webs are dimensioned as thin as possible, taking into account a required mechanical strength. A first 127 of these small recesses adjoins the large recess 122 along the radially outwardly facing boundary 124. The first small recess 127 is at least substantially rectangular and is configured symmetrically with respect to the radial center axis 106.A second 128 and a third 129 of the small recesses adjoin the radially outward facing of the circumferentially 105 facing edges 123 of the large recess 122. They are arranged in the spatial region between the permanent magnets 101 and 102, respectively, and the cutting lines 108. The second 128 and the third small recess 129 are aligned with the extension direction of the cutting lines 108 and the rims 123 with straight rims, but have a curved rim pointing radially outwards with a radius which is smaller, preferably by a multiple smaller, than the radius of the rotor outer surface 104. The second 128 and third 129 small recesses are configured and aligned symmetrically with the radial center axis 106.A fourth 130 of the small recesses adjoins the first small recess 127 radially outwards and is likewise of rectangular configuration, but its cross-sectional area in the radial plane is a quarter or less of the cross-sectional area of the first small recess 127. Further, the radial cross-sectional area of the large recess 122 is at least five times the radial cross-sectional area of each of the small recesses 127, 128, 129, 130.FIG. 5 shows the angular range 107 with the three permanent magnets 101, 102, 103 enlarged in a roughly schematic illustration, wherein a group of recesses according to a third embodiment of the invention is reproduced in this angular range 107. This second embodiment is likewise a lightweight construction of the rotor core 100, which however has again enlarged recesses compared to the lightweight construction of FIG. 4. In particular, in this lightweight construction, a large recess 131 extends radially even further toward the rotor shaft opening 109; it also protrudes in the circumferential direction 105 beyond the radially inwardly directed corners of the permanent magnets 101, 102.The large recess 131 is also formed here in a hexagonal manner with straight-line borders and is arranged symmetrically with respect to the radial central axis 106. Here, only transitions between the borders 132 pointing in the circumferential direction 105 and transitions between the borders 132 pointing radially inward of the borders pointing in the circumferential direction 105 and a border 134 pointing radially inward are rounded. The transitions between the radially outward-pointing one of the rims 132 pointing in the circumferential direction 105 and a radially outward-pointing rim 133, on the other hand, are formed at an acute angle, i.e. at an angle. The permanent magnets 101, 102 abut with their radially inwardly directed narrow sides against the radially outwardly directed edges 132 facing in the circumferential direction 105 via webs 135, which are again dimensioned as thin as possible, taking into account the required mechanical strength, in order here to avoid or keep a magnetic short circuit low.The large recess 131 is part of a group of recesses which furthermore has a total of six small recesses 136, 137, 138, 139, 140, 141 which adjoin the rims 132 and 133 of the large recess 131 in a honeycomb manner outwards in the radial direction and here also in the circumferential direction 105. Each of the recesses is separated from an adjacent one of the other by webs which are likewise not separately designated here. All these webs are again dimensioned as thin as possible, taking into account a required mechanical strength. A first 136 of these small recesses adjoins the large recess 131 along the radially outwardly pointing boundary 133. The first small recess 136 is trapezoidal and is configured symmetrically with respect to the radial center axis 106.A second 137 and a third 138 of the small recesses adjoin the radially outward facing edges 132 of the large recess 131 facing in the circumferential direction 105 and are arranged in the spatial region between the permanent magnets 101 and 102, respectively, and the cutting lines 108. The second 137 and the third small recess 138 are almost aligned with the extension direction of the cutting lines 108 with straight borders and with the borders 132, i.e. their borders extend parallel to the borders 132, but with a slight, radially outward tapering to the cutting lines 108, whereby the force flow in the transitions of each two adjacent angular ranges 107 is even better matched. Here too, the second 137 and the third small recess 138 are configured and aligned symmetrically with respect to the radial center axis 106.A fourth 139 of the small recesses adjoins the first small recess 136 radially outwards and is of rectangular configuration, but its cross-sectional area in the radial plane is one third or less of the cross-sectional area of the first small recess 136.Comparable to the embodiment according to FIG. 3, in FIG. 5, the group of recesses 136, 137, 138, 139, 140, 141 is extended by a fifth 140 and a sixth 141 recess, which are triangular and are arranged symmetrically with respect to each other with respect to the radial center axis 106 at acute-angle corners between one of the permanent magnets 101 and 102 each and the narrow sides, i.e. short borders, pointing in the circumferential direction 105, of the fourth small border 139. This also allows a further reduction in mass.In the third embodiment of FIG. 5, the radial cross-sectional area of the large recess 131 is at least seven times the radial cross-sectional area of each of the small recesses 136, 137, 138, 139, 140, 141.FIG. 6 shows the angular range 107 with the three permanent magnets 101, 102, 103 in enlarged form in a roughly schematic illustration, wherein a group of recesses according to a fourth embodiment of the invention is arranged in this angular range 107. The features of this fourth embodiment largely correspond to those of the third embodiment, so that reference can be made in this respect to FIG. 5 together with the description.Differences in the fourth embodiment from the third are as follows:• The fourth embodiment according to FIG. 6 has a large recess 142 with a basic configuration again based on the hexagonal shape, but radially outward-pointing sections are formed rounded on both sides of the rims 143 pointing in the circumferential direction 105, and the radially inward-pointing ends of the permanent magnets 101, 102 of the "V"-shaped configuration adjoin the rounded sections of the rims 143;• the radially inward-pointing corners of the first small recess 136 are rounded with a radius which is preferably small with respect to the extension of the first small recess in the circumferential direction 105;• The second and third small recesses of Fig. 5 are omitted. At each transition of two adjacent angular regions 107, which are assigned to two adjacent magnetic poles and are covered in the circumferential direction 105 by the "V"-shaped configuration 101, 102, i.e. on and centrally with respect to the cutting lines 108, a small recess 144 with a circular boundary is arranged in each case at its location.The invention makes it possible to reduce the rotor mass and thereby increase the performance of an electric machine equipped with a rotor designed according to the invention. In particular, the invention also enables mass compensation in the case of a reduction in the rotor shaft diameter, which would otherwise lead to an increase in the mass of the rotor core and thus of the rotor. The solution consists in an arrangement of a plurality of recesses of different size and configuration in the rotor core, in particular along its so-called d-axis. An inductance of the rotor in this d-axis can thus also be reduced, which leads to an advantageously dimensioned reluctance component in the torque of the electric machine. This is very important for high speed applications.The honeycomb structure of the rotor core according to the invention-also referred to as a lattice structure-enables a particularly good distribution and thus a particularly good compensation of the mechanical loads of the rotor core, in particular due to centrifugal forces, over the individual webs between the recesses. The invention enables both a design for particularly high loads, in particular at high rotational speeds, and a lightweight construction with a particularly low mass and, as a result, particularly low mass inertia and low rotor weight and thus ultimately vehicle weight. The energy consumption of a vehicle drive equipped according to the invention can be reduced and the range of a battery-electrically operated vehicle provided with this drive can thus be increased. The high-speed variant enables in particular an increased vehicle speed.In summary, the invention provides a magnetically conductive rotor core of a rotor of a permanent magnet-excited electric machine, having three permanent magnets each magnetic pole, two of which are arranged in a "V"-shaped configuration opening toward a rotor outer surface and the third of which are arranged tangentially along a circumferential direction of the rotor core. One group of recesses is provided in the rotor core for each magnetic pole. Each group comprises a large recess and at least three small recesses which adjoin honeycomb edges of the large recess. A radial cross-sectional area of the large recess is at least twice the radial cross-sectional area of each of the small recesses. This enables a saving of mass with simultaneously high mechanical strength.List of reference characters100 Rotor core 101 permanent magnet of the "V"-shaped configuration 101, 102 102 permanent magnet of the "V"-shaped configuration 101, 102 103 permanent magnet 104 rotor outer surface, i.e. outer circumference of 100 105 circumferential direction of 100 106 radial center axis of the "V"-shaped configuration 101, 102 107 angular range 107 covered by the "V"-shaped configuration 101, 102 along 105 angular range 107, equal to the pole pitch of 100 108 intersecting lines, Transitions of two adjacent angular ranges 107 designate 109 rotor shaft opening of 100 110 rotational axis of 100 111 large recess in 100 (FIGS. 2 and 3 ) 112 in circumferential direction 105 designate borders of 111 113 radially inwardly and outwardly directed borders of 111 114 webs between 111 and 101 and 102 115, respectively, designate first small recess in 100 (FIGS. 2 and 3 ) 116 designate second small recess in 100 (FIGS. 2 and 3 ) 117 designate third small recess in 100 (FIGS. 2 and 3 ) 118 designate fourth small recess in 100 (FIGS. 2 and 3 ) 119 designate fifth small recess in 100 (FIGS. 2 and 3 ) designate 120 designate sixth small recess in 100 (FIG. 3 ) designate 121 designates seventh small recess in 100 (FIG. 3 ). 3 ) 122 Large recess in 100 (FIG. 4 ) 123 Circumferentially 105 Facing rims of 122 124 Radially outward facing rim of 122 125 Radially inward facing rim of 122 126 Webs between 122 and 101 and 102 127, respectively, First small recess (FIG. 4 ) 128 Second small recess (FIG. 4 ) 129 Third small recess (FIG. 4 ) 130 Fourth small recess (FIG. 4 ) 131 Large recess in 100 (FIG. 5 ) 132 Circumferentially 105 Facing rims of 131 133 Radially outward facing rim of 131, 142 134 Radially inward facing rim of 131, 142 135 webs between 131 and 142 and 101 and 102 136 first small recess (FIGS. 5 and 6 ) 137 second small recess (FIG. 5 ) 138 third small recess (FIG. 5 ) 139 fourth small recess (FIGS. 5 and 6 ) 140 fifth small recess (FIGS. 5 and 6 ) 141 sixth small recess (FIGS. 5 and 6 ) 142 large recess in 100 (FIG. 6 ) 143 circumferentially 105 facing margins of 142 144 small recess with a circular margin (FIG. 6 )

Claims

Magnetically conductive rotor core (100) of a rotor of a permanent magnet excited electric machine, with • three permanent magnets (101, 102, 103) per magnetic pole of the rotor, of which two are arranged in a "V"-shaped configuration (101, 102) which opens toward a rotor outer surface (104), and the third (103) are arranged tangentially along a circumferential direction (105) of the rotor core (100) at least approximately centrally with respect to the "V"-shaped configuration (101, 102), • each magnetic pole of a group of recesses (111, 115, 116, 117, 118, 119, 120, 121; 122, 127, 128, 129, 130; 131, 136, 137, 138, 139, 140, 141; 142; 144) in the rotor core (100), each group comprising: ◯ a large recess (111; 122; 131; arranged at least approximately symmetrically with respect to the "V"-shaped configuration (101, 102); 142) which extends radially in a region of the rotor core (100) between a central rotor shaft opening (109) and at least almost the radially inwardly directed ends of the "V"-shaped configuration (101, 102) and ▪ in the circumferential direction (105) within an angular range (107) covered by this "V"-shaped configuration (101, 102), and ◯ at least three small recesses (115, 116, 117, 118, 119, 120, 121; 127, 128, 129, 130; 136, 137, 138, 139, 140, 141; 144) which adjoin, in a honeycomb manner at least outwards in the radial direction, rims (112, 113; 123, 124, 125; 132, 133, 134; 143) of the large recess (111; 122; 131; 142), ◯ wherein a radial cross-sectional area of the large recess (111; 122; 131; 142); 142) is at least twice the radial cross-sectional area of each of the small recesses (115, 116, 117, 118, 119, 120, 121; 127, 128, 129, 130; 136, 137, 138, 139, 140, 141; 144).Rotor core (100) according to claim 1, characterised in thatthe large recess (111; 122; 131; 142) with two radially outwards directed (112; 123; 132; 143) of its borders (112, 113; 123, 124, 125; 132, 133, 134; 143) adjoins the radially inward directed ends of the permanent magnets (101, 102) of the "V"-shaped configuration (101, 102).Rotor core (100) according to Claim 1 or 2, characterized in that the large cutout (111; 122; 131; 142) is formed with at least virtually rectilinear borders (112, 113; 123, 124, 125; 132, 133, 134; 143) arranged at least virtually hexagon-shaped, and in that at least four of these borders (112, 113; 123, 124, 125; 132, 133, 134; 143) are adjoined by small cutouts (115, 116, 117, 118, 119, 120, 121; 127, 128, 129, 130; 136, 137, 138, 139, 140, 141; 144).Rotor core (100) according to Claim 1 or 2, characterized in that the large recess (142) is formed with at least sectionally rounded borders (143), and in that at least the radially inwardly directed ends of the permanent magnets (101, 102) of the "V"-shaped configuration (101, 102) adjoin at least one of these at least sectionally rounded borders (143).Rotor core (100) according to one or more of the preceding claims, characterized in that a small recess (144) is arranged in each case at the transition (108) between two adjacent angular ranges (107), which are assigned to two adjacent angular fields of the magnetic poles and are covered in the circumferential direction (105) by the "V"-shaped configuration (101, 102), preferably with a rounded, particularly preferably circular boundary.Rotor core (100) according to one or more of the preceding claims, characterized in that at least one (115) of the small recesses (115, 116, 117, 118, 119, 120, 121; 127, 128, 129, 130; 136, 137, 138, 139, 140, 141; 144) radially inwards adjoins the large recess (111).Rotor core (100) according to one or more of the preceding claims, characterized in that the radial cross-sectional area of the large recess (111; 122; 131; 142) is at least three times, preferably at least five times, particularly preferably at least seven times, the radial cross-sectional areas of each of the small recesses (115, 116, 117, 118, 119, 120, 121; 127, 128, 129, 130; 136, 137, 138, 139, 140, 141; 144).Rotor of a permanent magnet excited electric machine, characterized bya rotor core (100) according to one or more of the preceding claims.Permanent magnet excited electric machine, characterized bya rotor according to claim 8 and / or a rotor core (100) according to one or more of claims 1 to 7.Vehicle, in particular road vehicle, characterized bya permanent magnet excited electric machine according to claim 9 and / or a machine with a rotor according to claim 8 and / or with a rotor core (100) according to one or more of claims 1 to 7.

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