Rotor lamination with a hole in an overhang section

Abstract

Rotor lamination (1) for a rotor lamination stack (50), wherein the rotor lamination (1) comprises: - a yoke section (2) with a central hole (3) through which a rotation axis (4) of the rotor lamination (1) runs, and - a plurality of pole sections (5), each having a pole core section (6) which projects radially from the yoke section (2), and a pole head section (7) which adjoins the pole core section (6) radially on the outside and forms a first overhang section (8) and a second overhang section (9) which project beyond the pole core section (6) on both sides in the circumferential direction, wherein a first hole (10) is formed in the first overhang section (8).

Description

The present invention relates to a rotor lamination for a laminated rotor core, wherein the rotor lamination has: a yoke section having a central hole through which a rotational axis of the rotor lamination runs, and a plurality of pole sections, each having a pole core section which protrudes radially from the yoke section, and a pole head section which adjoins the pole core section radially on the outside and forms a first overhang section and a second overhang section which protrude beyond the pole core section on both sides in the circumferential direction.In addition, the invention relates to a laminated rotor core for a rotor, a rotor for an electric machine, an electric machine for a vehicle and a vehicle.Rotors for externally excited synchronous machines (EESM) have, in particular in the field of automotive applications, a laminated rotor stack formed from a multiplicity of rotor laminations arranged in a stacked manner. It has already been proposed to provide these rotor laminations with holes which form an axial through opening of the rotor laminated core. These holes can be used for various purposes, in particular for passing a coolant through them for cooling the rotor or for mechanical purposes.For example, EP 4 191 839 A1 discloses a laminated core for a rotor, which is formed from stacked electric sheets. Poles of the rotor have through-openings provided as cooling channels, which are provided at least partially within a pole head.The object of the invention is to specify a possibility for improving the performance of an electric machine.This object is achieved according to the invention by a rotor plate of the type mentioned at the beginning, in which a first hole is formed in the first overhang section.The rotor lamination sheet according to the invention for a laminated rotor core has a yoke section. The yoke portion has a central hole. A rotational axis of the rotor lamination runs through the central hole. The rotor lamination according to the invention further comprises a plurality of pole sections. The pole sections each have a pole core section and a pole head section. The pole core portion protrudes radially from the yoke portion. The pole head section adjoins the pole core section radially on the outside. The pole head section forms a first overhang section and a second overhang section. The overhang portions protrude beyond the pole core portion on both sides in the circumferential direction. A first hole is formed in the first overhang portion.The invention is based on the consideration of forming the first hole in the first overhang section in a targeted manner, such that a flux barrier can be formed in the first overhang section by magnetic saturation. In addition to known advantages of a hole in the pole head section, the achievable reluctance torque during operation of an electric machine having the rotor lamination can thereby be increased. Any possible reduction in the torque generated by the rotor flux is compensated for by the increased reluctance torque. Advantageously, a corresponding electric machine can be operated in such a more efficient manner.The rotor sheet according to the invention is formed in particular from a soft magnetic metal. The central hole can be circular. Typically, the central hole is completely surrounded by the yoke portion.An even number of pole sections are typically provided. For example, four, six, eight, ten or twelve pole sections are provided. The pole sections can be arranged equidistantly in the circumferential direction around the yoke section.An edge of the pole head portion remote from the yoke portion is typically configured in an arc shape, in particular in the shape of a circular arc. Between a respective overhang portion and the yoke portion, a receiving region for a winding can be formed.The first hole is preferably located entirely in the first overhang portion. Preferably, the first hole is completely surrounded by the material of the first overhang portion. That is, an edge of the first hole is formed entirely by the first overhang portion.It is preferably provided that the course of an edge section of the first hole close to the yoke section follows the course of an edge of the first overhang section close to the yoke section. The course of the edge section close to the yoke section is in particular parallel to the course of the edge of the first overhang section close to the yoke section. The rotor sheet can thus form the flux barrier as a web between the first hole and the receiving region.According to one embodiment variant, it can be provided that the course of an edge section of the first hole remote from the yoke section follows the course of an edge of the first overhang section remote from the yoke section. The course of the edge section remote from the yoke section is in particular concentric to the course of the edge of the first overhang section remote from the yoke section. In this way, the flux barrier can be formed as a web between the first edge of the first overhang portion remote from the yoke portion and the edge of the pole head portion remote from the yoke portion, respectively.Alternatively to the aforementioned embodiment variant, an edge section of the first hole remote from the yoke section can be formed straight.The pole head section preferably adjoins the pole core section along a center line that is radial with respect to the axis of rotation. In this case, mutually opposite edges of the pole core section can run parallel to the radial center line in the circumferential direction. A respective edge of the pole core section delimits in particular the receiving region. Lines parallel to the center line, on which the opposite edges of the pole core section lie, can form a lateral delimitation of the first and second overhang sections.Advantageously, an edge portion of the first hole facing the center line runs parallel to the center line. Alternatively or additionally, an edge section of the first hole facing away from the center line can run in the shape of a circular arc.It is also possible in addition for the first hole to be polygonal, quadrangular, triangular, circular or oval.With regard to the second overhang portion, it can be provided that it is free of a hole.Alternatively, the second overhang portion has a second hole. The second hole can be formed mirror-symmetrically to the first hole. The radial center line can form the axis of symmetry. However, the second hole may also be shaped differently from the first hole. Moreover, all the embodiments relating to the first hole and to the first overhang section can be transferred to the second hole or the second overhang sectionIt can furthermore be provided that an edge of an overhang portion opposite the center line has a cutout or shoulder for fixing a spacer.The object on which the invention is based is furthermore achieved by a laminated rotor core for a rotor, wherein the laminated rotor core has a plurality of laminated rotor cores according to the invention, which are stacked one on top of the other along the axis of rotation in such a way that the first holes of a respective pole head section form a first through-opening. Alternatively or additionally, the second holes of a respective pole head section can form a second through-opening.The through-opening can extend parallel to the rotation axis. In this case, the rotor laminations can be stacked congruently one on top of the other.It is also possible for the rotor laminations to be stacked on top of one another with an offset in the circumferential direction or angular offset about the axis of rotation. As a result, the rotor can be formed in a beveled manner.The rotor laminations may also be arranged in a layered manner such that the central holes form a hub and / or the yoke sections form a rotor yoke and / or the pole sections form a rotor pole. Within each rotor pole, the pole core sections can form a pole core and / or the pole head sections can form a pole head of the laminated rotor core.The object on which the invention is based is furthermore achieved by a rotor for an electric machine, having a laminated rotor core according to the invention, a rotor shaft on which the laminated rotor core is mounted, and a rotor winding which is wound around a pole core formed by the pole core sections.The first through-opening and / or the second through-opening can receive a bolt for axially fixing the rotor laminations. The axial fixing can be effected by bracing the rotor laminations.The first through-opening and / or the second through-opening can form a cooling channel through which a coolant, in particular liquid coolant, can be conveyed.The cut-outs in the overhang portions may further form an axial groove in each pole head. In the mutually facing grooves of a respective pair of adjacent rotor poles, a spacer can be arranged, in particular clamped, which holds the rotor winding in the receiving regions.Between the rotor shaft and the hub, a shaft-hub connection, in particular a press fit, can be formed.The object on which the invention is based is furthermore achieved by an electric machine having a rotor according to the invention and a stator, wherein the rotor is mounted rotatably with respect to the stator.The electric machine preferably further comprises a cooling device which is configured to convey a or the coolant through the first through-opening and / or the second through-opening. In other words, the first through-opening and / or the second through-opening can form a fluid-conducting section of a cooling circuit of the electric machine comprising the cooling device.The object underlying the invention is furthermore achieved by a vehicle having an electric machine according to the invention which is configured to drive the vehicle.Further advantages and details of the present invention will become apparent from the drawings described below. These are schematic representations and show:FIG. 1 shows a plan view of an exemplary embodiment of the rotor lamination according to the invention; FIG. 2 shows a detailed view of the rotor lamination shown in FIG. 1 in the region of a pole section; FIG. 3 shows a schematic diagram of an exemplary embodiment of a laminated rotor core according to the invention in an exemplary embodiment of a rotor according to the invention; FIG. 4 is a sectional view of the rotor shown in FIG. 3; FIG. 5 shows a schematic diagram of an exemplary embodiment of a vehicle according to the invention with an exemplary embodiment of an electric machine according to the invention; and FIG. 6 shows a diagram of the torque over the electrical angle during operation of an electric machine according to the invention and during operation of comparative examples of an electric machine.FIG. 1 is a plan view of an embodiment of a rotor lamination 1.The rotor lamination 1 has a yoke portion 2 with a central hole 3 through which a rotation axis 4 of the rotor lamination 1 passes. In the present exemplary embodiment, the central hole 3 is circular and completely surrounded by the yoke section 2. In addition, the rotor lamination 1 has a plurality of pole sections 5. Each pole section 5 has a pole core section 6, which protrudes radially from the yoke section 2, and a pole head section 7, which adjoins the pole core section 6 radially on the outside. The pole head section 7 forms a first overhang section 8 and a second overhang section 9, which protrude beyond the pole core section 6 on both sides in the circumferential direction. A first hole 10 is formed in the first overhang portion 8.In the present exemplary embodiment, a second hole 11 is additionally formed in the second overhang portion 9. This second hole 11 is formed mirror-symmetrically to the first hole 10. In this respect, all the following explanations regarding the first hole 10 can be correspondingly transferred to the second hole 11.Also shown is a radial center line 12 with respect to the axis of rotation 4, along which the pole head section 7 adjoins the pole core section 6. The center line 12 also forms the axis of symmetry with respect to which the first hole 10 and the second hole 11 are mirror-symmetrical.In detail, the rotor lamination 1 is formed of a soft magnetic metal. Purely by way of example, the rotor lamination 1 has a total of six pole sections 5, which are arranged equidistantly around the yoke section 2 in the circumferential direction.FIG. 2 is a detailed view of the rotor lamination 1 shown in FIG. 1 in the region of a pole section 5.The course of an edge section 13 of the first hole 10 close to the yoke section follows the course of an edge 14 of the first overhang section 8 close to the yoke section. The edge section 13 and the edge 14 are straight here, such that the courses are parallel to one another. In detail, the yoke section-side edge 13 runs perpendicular to the radial center line 12.In addition, the course of an edge section 15 of the first hole 10 remote from the yoke section follows the course of an edge 16 of the first overhang section 8 remote from the yoke section. the edge section 15 and the edge 16 are here circular arc-shaped, so that the courses are concentric to one another.An edge section 17 of the first hole 10 facing the center line 12 runs parallel to the center line 12, and an edge section 18 of the first hole 10 facing away from the center line 12 runs in the shape of a circular arc. Transitions between the edge sections 13, 15, 17, 18 are rounded.As can also be seen from FIG. 2, mutually opposite edges 19, 20 of the pole core section 6 extend in the circumferential direction parallel to the radial center line 12; the edge 19 delimits, together with the edge 14 of the first overhang section 8 close to the yoke section, a first receiving region 21; the edge 20 delimits, together with the edge 14' of the second overhang section 9 close to the yoke section, a second receiving region 22; moreover, with respect to the center line 12, a cutout 23, 24 pointing towards the edge 16 remote from the yoke section is provided on the outside of each overhang section 8, 9.According to a further exemplary embodiment of the rotor lamination 1, only the first hole 10 is provided in a respective pole section 5. That is, the second overhang portion 9 is free of a hole.According to further exemplary embodiments, the first hole 10 and / or the second hole 11 is circular or oval. Alternatively, the first hole 10 and / or the second hole 12 is formed polygonally, in particular triangularly or quadrangularly. According to a further exemplary embodiment, the edge section 15 remote from the yoke section is formed straight.According to further exemplary embodiments, instead of six pole sections 5, four, eight, ten or twelve pole sections 5 are provided.FIGS. 3 and 4 each show an exemplary embodiment of a laminated rotor core 50 in an exemplary embodiment of a rotor 60, wherein FIG. 3 is a schematic diagram and FIG. 4 is a cut-away view.The laminated rotor core 50 has a plurality of laminated rotor cores 1 according to one of the exemplary embodiments described above. For reasons of clarity, only the axially outer rotor lamination 1 is schematically shown in FIG. 3. The rotor laminations 1 are stacked one on top of the other along the axis of rotation 4 in such a way that the first holes 10 of a respective pole head section 7 form a first through-opening 51. If the second holes 11 are provided, the second holes 11 form a second through hole 52 (see FIG. 4 ). In the present exemplary embodiment, the rotor laminations 1 are stacked congruently and are electrically insulated from one another.Besides, the rotor laminations 1 are arranged in a layered manner such that the yoke sections 2 form a rotor yoke 53 and the pole sections 5 form a rotor pole 54. Within each rotor pole 54, the pole core sections 6 form a pole core 55 and the pole head sections 5 form a pole head 56 of the laminated rotor stack 50. The central holes 2 form a hub 57.According to a further exemplary embodiment of the laminated rotor core 50, an offset in the circumferential direction or angular offset about the axis of rotation is provided between each two axially adjacent laminated rotor cores 1, so that a beveled laminated rotor core 50 is formed.The rotor 60 has a laminated rotor core 50 according to one of the exemplary embodiments described above, a rotor shaft 61 on which the laminated rotor core 50 is mounted, and a rotor winding 62. Between the rotor shaft 61 and the hub 57 a shaft-hub connection is formed, for example in the form of a press fit. The rotor winding 62 is wound around the pole core 55 of a respective rotor pole 54.As can best be seen in FIG. 4, the rotor winding 62 is arranged in the first and second receiving regions 21, 22. The cut-outs 23, 24 of a respective pole head section 7 form a respective groove 63, 64 in the pole head 56 along the rotor 60. Inserted into the grooves 63, 64 of two directly adjacent pairs of pole heads 56 is a spacer 65, which is supported against the rotor yoke 53 and holds the rotor windings 62 in the receiving regions 21, 22.In addition, the rotor 60 has bolts 66, which are each arranged in one of the first through openings 51 for axially fixing the rotor laminations 1. Of course, the bolts 66 can alternatively or additionally be arranged in the second through-openings 52.FIG. 5 is a schematic diagram of an exemplary embodiment of a vehicle 100 having an exemplary embodiment of an electric machine 101.The electric machine 101 is a separately excited synchronous machine (EESM) and has a stator 102 and a rotor 60 according to one of the exemplary embodiments described above, which is mounted rotatably with respect to the stator 102. Optionally, the electric machine 101 has a cooling device 103, which is configured to convey a coolant through the first through-opening 51 and / or the second through-opening 52, which in this respect form a cooling channel for the coolant.The vehicle 100 further includes wheels 104. The electric machine 101 is configured to drive at least one of the wheels 104 indirectly, for example via a transmission (not shown), or directly, for example in the form of a wheel hub motor. The vehicle 100 may further include an axle (not shown) coupled to the wheel 104 that directly or indirectly drives the electric machine 101 of the vehicle 100.The vehicle 100 is a battery electric vehicle (BEV), a fuel cell powered vehicle, or a hybrid vehicle. In the latter case, the vehicle 100 further includes an internal combustion engine (not shown).FIG. 6 is a diagram of a relative torque T rel over the electrical angle φ el during the operation of an electric machine 101 according to the exemplary embodiment shown in FIG. 1 and during the operation of comparative examples of an electric machine. In addition, FIG. 6 shows the configurations of the rotor laminations 1', 1" in the comparative examples which differ from the exemplary embodiment.In the first comparative example, the rotor sheet 1' has no holes in the pole head portion 7'. In the second comparative example, the rotor sheet 1" has two holes 10'', 11'' in the pole head section 7''. These holes are, however, not located in the overhang portions 8", 9", but instead in between.As can be seen from the graph in FIG. 6, the torque curve 200' in the first comparative example in which no holes are provided has a relative peak value of 100.0%. In the second comparative example, in which the holes 10'', 11'' are not provided in the overhang portions 8'', 9'', the curve 200'' has a relative peak value of the torque of 96.8%. The relative peak value of the curve 200 of the electric machine 101 according to the exemplary embodiment has the highest value at 102.0%.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedEP 4 191 839 A1

[0004]

Claims

Rotor lamination (1) for a laminated rotor core (50), wherein the rotor lamination (1) has: - a yoke section (2) with a central hole (3) through which a rotational axis (4) of the rotor lamination (1) runs, and - a plurality of pole sections (5) each having a pole core section (6) which protrudes radially from the yoke section (2), and a pole head section (7) which adjoins the pole core section (6) radially on the outside and forms a first overhang section (8) and a second overhang section (9) which protrude beyond the pole core section (6) on both sides in the circumferential direction, characterized in that a first hole (10) is formed in the first overhang section (8).Rotor lamination according to Claim 1, wherein the course of an edge section (13) of the first hole (10) close to the yoke section follows the course of an edge (14) of the first overhang section (8) close to the yoke section, in particular is parallel to the course of the edge (14) close to the yoke section.Rotor lamination according to Claim 1 or 2, wherein the course of an edge section (15) of the first hole (10), which edge section is remote from the yoke section, follows the course of an edge (16) of the first overhang section (8) remote from the yoke section, in particular is concentric with the course of the edge (16) remote from the yoke section.The rotor lamination according to claim 1 or 2, wherein a yoke portion-remote edge portion (15) of the first hole (10) is formed straight.Rotor lamination according to one of the preceding claims, wherein the pole head section (7) adjoins the pole core section (6) along a centre line (12) which is radial with respect to the axis of rotation (4).The rotor lamination according to claim 5, wherein an edge portion (17) of the first hole (10) facing the center line (12) is parallel to the center line (12).Rotor lamination according to Claim 5 or 6, wherein an edge section (18) of the first hole (10) facing away from the centre line (12) runs in the form of a circular arc.Rotor lamination according to one of the preceding claims, wherein the first hole (10) is formed in the shape of a polygon, quadrilateral, triangle, circle or oval.Rotor lamination according to one of the preceding claims, wherein the second overhang section (9) is free of a hole or has a second hole (11) which is formed mirror-symmetrically with respect to the first hole (10).A laminated rotor core (50) for a rotor (60), wherein the laminated rotor core (50) has a plurality of laminated rotor cores (1) according to one of the preceding claims, which are stacked one on top of the other along the axis of rotation (4) in such a way that the first holes (10) of a respective pole head section (7) form a first through-opening (51).Rotor (60) for an electric machine (101), comprising - a laminated rotor core (50) according to Claim 10, - a rotor shaft (61) on which the laminated rotor core (50) is mounted, and - a rotor winding (62) which is wound around a pole core (55) formed by the pole core sections (6).The rotor according to claim 11, wherein the first through hole (51) receives a bolt (66) for axially fixing the rotor laminations (1).Electric machine (101) having a rotor (60) according to Claim 11 or 12 and a stator (102), wherein the rotor (60) is mounted rotatably with respect to the stator (102).Electric machine according to Claim 13, further comprising a cooling device (103) which is configured to convey a coolant through the first through-opening (51).Vehicle (100) comprising an electric machine (101) according to claim 14, configured to propel the vehicle (100).

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