Rotor for an electric machine

Abstract

The present invention relates to a rotor for an electric machine, in particular for an electric drive of an electrically or partially electrically powered motor vehicle, wherein the rotor has a laminated core, wherein the laminated core has a plurality of laminates (30) stacked in a stacking direction, wherein the stacking direction runs along a rotational axis of the rotor, wherein the respective laminate (30) has a first main extension surface (31) facing in the stacking direction and a second main extension surface opposite the first main extension surface (31) in the stacking direction, wherein the respective laminate (30) has one or more first stiffening beads (33) in the region of the first main extension surface (31), wherein the laminated core (3) forms an inner central laminated core, wherein the respective laminate (30) has a plurality of teeth (35), wherein a pole groove extending along the rotational axis is formed between each two teeth (35),wherein the respective tooth (35) has at least two stiffening beads (33), wherein the stiffening beads (33) of the respective tooth (35) form a radially outwardly tapering V-shaped arrangement with each other.,

Description

The present invention relates to a rotor for an electric machine.Electric machines, such as motors and generators, are well known from automotive engineering. These usually comprise a fixed stator and a rotor arranged in the stator. Frequently, rotors are at least partially designed in a laminated sheet and accordingly have components which are designed as laminated cores. Electric machines with a conventional rotor topology with buried magnets are generally mounted on an at least partially laminated rotor in order to minimize surface losses and eddy current losses. Frequently, rotors have an inner laminated core, outer laminated cores and magnetic units arranged between the outer laminated cores and the inner laminated core. Frequently, at least one bandage is pressed and / or wound radially on the outside onto the rotor. By such a banding of the rotor, a particularly high mechanical strength or rotational speed strength is achieved.DE 10 2022 200 563 A1 discloses a rotor, wherein the rotor comprises a laminated rotor core and a number of surface magnets which are arranged on the laminated rotor core, and a sleeve for fixing the surface magnets on the laminated rotor core, wherein the sleeve has bead-like depressions in order to avoid buckling. DE 10 2013 218 490 A1, DE 10 2022 116 139 A1, DE 10 2022 120 774 A1, EP 4 050 770 A1 and CN 220421521 U disclose further prior art. DE 10 2005 047 771 A1 discloses a rotor having the features of the preamble of claim 1.In particular when applying a bandage, high radial forces act on the laminations of the laminated core which are generally stacked perpendicularly to the radial direction. If these forces acting radially inward become too great, the sheets of the laminated core may bulge out.It is an object of the present invention to provide a novel rotor in which bulging of a laminated core of the rotor upon the action of radial forces is avoided.This object is achieved by a rotor having the features of claim 1. The dependent claims relate to advantageous further developments.The rotor according to the invention is used in an electric machine, in particular in an electric drive of an electrically or partially electrically driven motor vehicle. The rotor has a laminated core, wherein the laminated core has a multiplicity of sheets stacked in a stacking direction, wherein the stacking direction runs along a rotational axis of the rotor, wherein the respective sheet has a first main expansion surface pointing in the stacking direction and a second main expansion surface opposite the first main expansion surface in the stacking direction, wherein the respective sheet has one or more first stiffening beads in the region of the first main expansion surface.The reinforcing beads increase the laminated core, more precisely the respective sheet of the laminated core, with regard to its rigidity, in particular with regard to a radial compressive load. The laminated core can thus absorb the compressive forces in the radial direction, in particular the compressive forces resulting from the laminated core being overlapped with a bandage, much better, and bulging of the sheets and thus of the laminated core under radial compressive load is avoided.It is considered to be advantageous if the respective sheet metal has a plurality of second stiffening beads in the region of the second main expansion surface. The provision of second stiffening beads has the advantage that preferred directions in the event of any deformation are avoided, since the first stiffening beads and the second stiffening beads are formed on opposite main expansion surfaces of the respective sheet metal.It is considered to be particularly advantageous if a sheet thickness, insofar as the extension of the sheet from the first main extension surface to the second main extension surface, is from 0.1 mm to 0.4 mm, in particular from 0.2 mm to 0.3 mm. Such a configuration offers a sufficient material thickness and the stiffening beads can be produced in a simple manner, for example by embossing.It has proven advantageous if a bead depth of the respective first stiffening bead and or of the respective second stiffening bead is between 80% and 120% of a sheet thickness of the respective sheet.Preferably, a height of the respective first rib and / or of the second rib is between 80% and 120% of a sheet thickness of the respective sheet.It is quite conceivable for an insulation body to be arranged between adjacent sheets of the laminated core for electrically insulating the individual sheets of the laminated core from one another. However, it is also conceivable that instead of or in addition to the insulation body, the respective sheet is provided with an electrically insulating coating.It is considered to be particularly advantageous if the respective first stiffening bead is formed in such a way that a first rib is formed by the respective first stiffening bead on the second main expansion surface and / or wherein the respective second stiffening bead is formed in such a way that a second rib is formed by the respective second stiffening bead on the second main expansion surface. This design has the advantage that a particularly high rigidity of the respective sheet metal can be achieved by forming first ribs or second ribs. In addition, the production of the stiffening beads is possible in a particularly simple manner, for example by embossing.In a particularly preferred embodiment, it is provided that the sheets are formed in such a way that the first stiffening beads of inner sheets of the laminated core are in engagement with the first ribs of the sheet adjacent in the stacking direction and / or the second ribs of inner sheets are in engagement with the second stiffening beads of the sheet adjacent in the stacking direction. By means of such a configuration, an extension of the laminated core in the stacking direction can be advantageously kept small despite the provision of a first stiffening bead and / or a second stiffening bead and of first ribs and / or of second ribs. In addition, such a configuration offers the advantage that a fixing of the individual sheets to one another is additionally achieved, which prevents the sheets from rotating relative to one another.In a particularly preferred embodiment, it is provided that the respective first stiffening bead and / or the respective second stiffening bead is formed by an embossing. Embossing can be introduced particularly easily and cost-effectively. In addition, the rib can thereby be formed in the same process step in a simple manner.It is quite conceivable that the formation of the first stiffening beads and the first ribs takes place by an embossing die from the first main expansion surface, wherein a die for the formation of the first rib is arranged on the second main expansion surface or vice versa. The same applies to the second stiffening beads and the second ribs.It is considered to be particularly advantageous if the rotor has a bandage which radially externally spans the laminated core.The bandage is in particular a bandage which comprises fiber material. It is considered to be particularly advantageous if the material of the bandage is a fiber-reinforced plastic, in particular a carbon fiber-reinforced plastic (CFRP).It is provided that the laminated core forms an inner central laminated core, wherein the respective laminated core has a plurality of teeth, wherein a pole trench running along the axis of rotation is formed between each two teeth. Such a laminated core is also frequently referred to as a central laminated core or an inner laminated core.In this context, it is considered to be particularly advantageous if a pole laminated core is arranged in each pole trench, wherein at least one buried permanent magnet is fixed in a receiving intermediate space between the boundary surfaces of the central laminated core that delimit the pole trench and the opposing opposing opposing walls of the corresponding pole laminated core.It is quite conceivable for the pole laminated core to likewise have stiffening beads and / or stiffening ribs.With regard to the laminated core, it is considered to be advantageous if the first stiffening beads and / or the second stiffening beads are formed in the region of the teeth. It has been found that the teeth have to absorb a large part of the forces under a radial compressive load or a deformation in the form of a bulge occurs in the region of the teeth with insufficient stability. Provision of the first stiffening beads and / or the second stiffening beads in the region of the teeth is therefore to be regarded as advantageous.In a particularly preferred embodiment, it is provided that the respective first stiffening bead and / or the respective second stiffening bead run in a straight line.In a particularly preferred embodiment, it is provided that the respective first stiffening bead and / or the respective second stiffening bead extends in the radial direction.It is provided that the respective tooth has at least two stiffening beads, wherein the stiffening beads of the respective tooth form a V-shaped arrangement tapering radially outwards with one another.It is considered to be particularly advantageous if the respective sheet metal has a recess in the form of a through-opening in the region of the teeth. By providing the first stiffening beads and / or the second stiffening beads, the weakening of the sheet metal due to the through-opening can be advantageously at least partially compensated, so that the weight of the respective sheet metal can be reduced due to the through-openings without this having a negative effect on the stability, since the stability is again increased by the first stiffening beads and / or the second stiffening beads. Weight can thereby be saved with nevertheless high stability.In the following figures, the invention is explained in more detail on the basis of exemplary embodiments without being restricted to these. The following are shown: FIG. 1 shows a rotor with a laminated core as is known from the prior art in a perspective view, FIG. 2 shows the rotor according to FIG. 1 in a view along a stacking direction of the laminated core, FIG. 3 shows the laminated core according to a first embodiment of the rotor not included in the scope of protection of the claims in a view along a stacking direction of the laminated core, FIG. 4 shows the laminated core in a sectional view according to the line A-A in FIG. 3, FIG. 5 shows a sheet metal of the laminated core according to FIG. 4 in a view onto a first main area of extension of the sheet metal, FIG. 6 shows a sheet metal of the laminated core according to a second embodiment of the rotor according to the invention in a view as in FIG. 5.FIGS. 1 and 2 show a rotor 1 for an electric machine of an electrically or partially electrically driven motor vehicle, as is known from the prior art. The rotor 1 has an inner central laminated core 3, wherein this inner central laminated core 3 consists of a multiplicity of identically formed sheets 30, which are stacked in a stacking direction Z of the central laminated core 3. The central laminated core 3 is connected in a rotationally fixed manner to a rotor shaft 7 of the rotor 1. The central laminated core 3 or the respective sheet 30 of the central laminated core 3 has six teeth 35, wherein a pole trench running along the axis of rotation of the rotor 1, which is identical in the present case to the stacking direction Z of the central laminated core 30, is formed between each two teeth 35. A pole laminated core 4 corresponding to the pole trench is arranged in each pole trench, which in turn is formed from a plurality of pole laminations stacked in the stacking direction Z. Between the respective pole laminated core 4 and the teeth 35 delimiting the respective pole trench, a receiving intermediate space is formed. Two permanent magnets 5 are arranged in a V-shaped manner in the respective receiving intermediate space. The rotor 1 has a radially outer bandage 6 which extends radially outwards and spans the inner components, namely the central laminated core 3, the pole laminated cores 4 and the buried permanent magnets 5. This bandage 6 is in the present case a bandage 6 made of a carbon-fiber-reinforced plastic.In the case of high forces acting radially inward, as can be exerted on the central laminated core 3 due to the bandage 6, for example, an undesired and undefined bulging of the individual sheets 30 of the central laminated core 3 can occur.Such bulging is avoided by the embodiments of the rotor 1 shown in FIGS. 3 to 6. FIGS. 3 to 5 show a first embodiment of the rotor 1 not encompassed by the scope of the claims. FIG. 6 shows a second embodiment of the rotor 1 according to the invention.The first embodiment according to FIGS. 3 to 5 will first be explained in more detail below. In contrast to the sheets 30 of the rotor 1 known from the prior art, as shown in FIGS. 1 and 2, the respective sheet 30 of the first embodiment has a first stiffening bead 33 in the region of a first main expansion surface 31 which points in the stacking direction Z, in the region of the respective tooth 35. The respective first stiffening bead 33 in the present case runs in a straight line and in the radial direction, thus perpendicular to the axis of rotation, wherein an extension of the direction of extension of the respective first stiffening bead 33 inwards would intersect the axis of rotation of the rotor 1. The respective first stiffening bead 33 is formed as an embossing in such a way that a first rib 34 is formed by the respective first stiffening bead 33 on a second main expansion surface 32 opposite the first main expansion surface 31 in the stacking direction Z. As can be seen in particular from the sectional view of FIG. 4, the metal sheets 30 are designed in such a way that the first stiffening beads 33 of the respective metal sheet 30 are in engagement with the first ribs 34 of the metal sheet 30 adjacent in the stacking direction Z.The first stiffening beads 33 achieve stiffening of the respective sheet 30 in the radial direction, whereby deformation of the respective sheet 30 and thus of the laminated core 3 in the event of radially inwardly acting forces, as are brought about, for example, by the bandage 6, is avoided.FIG. 6 shows a metal sheet 30 of the second embodiment of the rotor 1, this metal sheet 30 differs from the metal sheet 30 according to the first embodiment essentially in that two first stiffening beads 33 are formed in the region of the respective tooth 35, the first stiffening beads 33 of the respective tooth 35 forming a V-shaped arrangement with one another which tapers radially outwards. In addition, in the region of the respective tooth 35, a recess in the form of a substantially triangular through-opening 36 is formed.List of reference characters1 Rotor 3 Laminated core 4 Pole laminated core 5 Permanent magnet 6 Bandage 7 Rotor shaft 30 Sheet 31 First main expansion surface 32 Second main expansion surface 33 First stiffening bead 34 First rib 35 Tooth 36 Through-opening Z Stacking direction

Claims

Rotor (1) for an electric machine, wherein the rotor (1) has a laminated core (3), wherein the laminated core (3) has a multiplicity of sheets (30) stacked in a stacking direction (Z), wherein the stacking direction (Z) runs along a rotational axis of the rotor (1), wherein the respective sheet (30) has a first main expansion surface (31) pointing in the stacking direction (Z) and a second main expansion surface (32) opposite the first main expansion surface (31) in the stacking direction (Z), wherein the respective sheet (30) has one or more first stiffening beads (33) in the region of the first main expansion surface (31), wherein the laminated core (3) forms an inner central laminated core, wherein the respective sheet (30) has a plurality of teeth (35), wherein a pole trench running along the axis of rotation is formed between each two teeth (35), characterized in that the respective tooth (35) has at least two stiffening beads (33), wherein the stiffening beads (33) of the respective tooth (35) form a V-shaped arrangement tapering radially outwards with one another.Rotor according to Claim 1, wherein the respective sheet (30) has a plurality of second stiffening beads in the region of the second main expansion surface (32).The rotor according to claim 1 or 2, wherein the respective first stiffening bead (33) is formed such that a first rib (34) is formed by the respective first stiffening bead (33) on the second main expansion surface (32), and / or wherein the respective second stiffening bead is formed such that a second rib is formed by the respective second stiffening bead on the second main expansion surface (32).Rotor according to Claim 3, wherein the sheets (30) are formed in such a way that the first stiffening beads (33) of inner sheets (30) of the laminated core (3) are in engagement with the first ribs (34) of the sheet (30) adjacent in the stacking direction (Z) and / or the second ribs of inner sheets (30) are in engagement with the second stiffening beads of the sheet (30) adjacent in the stacking direction (Z).Rotor according to one of Claims 1 to 4, wherein the respective first stiffening bead (33) is formed by an embossing and / or the respective second stiffening bead is formed by an embossing.Rotor according to one of Claims 1 to 5, wherein the rotor (1) has a bandage (6) which radially externally spans the laminated core (3).Rotor according to one of Claims 1 to 6, wherein the respective first stiffening bead (33) and / or the respective second stiffening bead run in a straight line.Rotor according to one of Claims 1 to 7, wherein the first stiffening beads (33) and / or the second stiffening beads are formed in the region of the teeth (35).

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