Abstract
A method is provided for producing a rotor for an electric machine, wherein the rotor comprises a shaft and a sheet metal pack arranged on the shaft, the sheet metal pack including a plurality of individual metal sheets axially stacked in succession, wherein multiple poles are provided on the sheet metal pack, around which wires are wound to form individual windings, wherein a sheet metal pack is used having multiple axially running breaches through it, wherein a tie rod is led through each breach of the sheet metal pack prior to the winding around the poles and locked at one end for the axial tensioning of the sheet metal pack, after which the wires are wound around the poles. A rotor produced according to the described method and an electric machine comprising a rotor are also provided.
Claims
1. A method for producing a rotor for an electric machine, wherein the rotor comprises a shaft and a sheet metal pack arranged on the shaft, the method comprising: stacking axially a plurality of individual metal sheets in succession to form the sheet metal pack, wherein multiple poles are provided on the sheet metal pack, and wherein multiple axially running breaches extend through the sheet metal pack; leading a respective tie rod through each breach of the sheet metal pack; axial tensioning the sheet metal pack via the tie rods; and after the sheet metal pack is axially tensioned, winding wires around the poles to form individual windings.
2. The method according to claim 1, wherein the breaches are provided in at least part of the poles of the sheet metal pack.
3. The method according to claim 2, wherein a respective breach is provided in each pole and the respective tie rod is led through each pole.
4. The method according to claim 1, wherein the breaches are formed as boreholes in the sheet metal pack.
5. The method according to claim 1, wherein axial tensioning of the sheet metal pack includes locking of the tie rods by nuts screwed onto threaded sections at the end of the tie rods or by a form-fitting connection of the tie rod to the sheet metal pack produced by a forming process.
6. The method according to claim 5, wherein each nut or form-fitting connection is situated in a recess provided in an axial end face of the sheet metal pack.
7. The method according to claim 5, wherein prior to the locking of the tie rods, a respective star disc is placed axially on one of opposing ends of the sheet metal pack, and each nut or form-fitting connection is situated in a recess provided in an axial end face of the star disc or placed on the axial end face of the star disc.
8. The method according to claim 1, wherein, after winding the wires around the poles, the tie rods are released and removed from the sheet metal pack.
9. A rotor, produced according to the method according to claim 1.
10. An electric machine, comprising a rotor produced according to the method according to claim 1.
Description
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0018] Further benefits and details will emerge from the following explained embodiments and figures.
[0019] FIG. 1 shows a diagram of a rotor during its assembly, in an exploded view.
[0020] FIG. 2 shows an enlarged partial view of a sheet of a sheet metal pack.
[0021] FIG. 3 shows a cross sectioned representation of the rotor of FIG. 1 in the final assembled state with indicated windings.
[0022] FIG. 4 shows the rotor of FIG. 1 with star discs put in place and indicated windings.
[0023] FIG. 5 shows a second embodiment of a rotor not showing the windings.
[0024] FIG. 6 shows a third embodiment of a rotor.
DETAILED DESCRIPTION
[0025] FIG. 1 shows, to explain the method described herein, a rotor 1 during assembly in an exploded view. The rotor 1 has a hollow shaft 2, on which is arranged a sheet metal pack 3 consisting of a multitude of individual metal sheets 4, usually several hundred of them. The sheet metal pack 3 is shrink-fitted onto the shaft 2 in familiar fashion.
[0026] Air gaps 5 are present between the metal sheets 4, being shown greatly exaggerated in the drawing for representation purposes. These air gaps 5 result from punching burr remaining on the punching contour during the punching of the individual metal sheets 4 from a metal strip, with the individual adjacent metal sheets 4 lying against each other across these gaps. Because of this punching bun, they cannot be placed on the shaft 2 free of air gaps. The air gaps 5 lie in the range of a few ?m, being shown greatly exaggerated in FIG. 1, as mentioned.
[0027] Multiple poles 6 are formed on the sheet metal pack 3, for which each individual sheet 4 as in FIG. 2 has a corresponding pole section 7 showing a more or less T-shaped cross section, so that, looking from the end face of the sheet metal pack 3, the respective pole 6 is likewise T-shaped in cross section. Corresponding winding grooves 8 are formed at each pole 6, in which a subsequently applied wire winding is wound to form the respective winding.
[0028] The sheet metal pack 3, or each sheet 4, has a breach 9 in the form of a circular round borehole in the region of the pole 6 or the pole section 7, while a few of the end-positioned metal sheets 4 in the embodiment shown also have an enlarged breach 10, as shown by dotted line in FIG. 2, serving for the countersunk receiving of a nut, as will be further described below. The metal sheets 4 are arranged such that the breaches 9 or 10 are all aligned with each other, so that a breach 11 running through the sheet metal pack 3 is formed. This breach 11 serves for the axial tensioning of the sheet metal pack 3, not yet free of air gaps, as shown in FIG. 1. The tie rods 12 are used for this, as shown in FIG. 1. The tie rods, likewise round in cross section, are provided with a thread 13 on their end, so that a corresponding nut 14 can be screwed onto them. After the shrink-fitting of the sheet metal pack 3 (but also possibly already before the shrink-fitting of the sheet metal pack 3 in one variant of the method), i.e., when the individual metal sheets 4 have been stacked in succession, the tie rods 12 are shoved into the respective breaches 11 and the nuts 14 are screwed onto the ends. The nuts 14 are tightened so that the entire sheet metal pack 3 is axially tensioned, as shown in FIG. 3. This means that the metal sheets 4, at least in the area of the poles 6, have been axially pressed against each other almost or entirely free of air gaps, i.e., the sheet metal pack 3 has been axially tensioned. This has the effect that a geometry change of the sheet metal pack 3 in the area of the pole 6 is no longer possible during the subsequent winding of the poles with a wire to form the respective pole-side winding 15, i.e., after this axial tensioning, and consequently the wire tension in each wire winding also remains unchanged as the winding process proceeds. In FIG. 3, two wrapped windings 15 are shown by dashed lines. The individual wire windings or winding layers run in the respective winding grooves 8. Since the axial pretensioning which is exerted by the screwed-in tie rods 12 on the sheet metal pack 3 is at least equal to, but in some embodiments greater than the entire axial pretensioning which is applied through the individual windings 15 or the entirety of the individual winding layers of a winding 15 on the respective pole 6, it is ensured that this winding-side pre-clamping force does not result in a further compaction of the already tensioned pole 6 due to the winding process.
[0029] FIG. 4 shows the rotor 1 of the preceding figures, but here in addition there are shown two star discs 16 placed on the axial end faces, being wound into the respective windings 15 as shown in FIG. 3. Due to the countersunk arrangement of the nuts 14, the respective star disc 16 can be placed flat on the end face of the sheet metal pack 3, i.e., they are braced axially as much as possible against the sheet metal pack 3. During the winding process to form the winding 15, no further geometry change that might adversely affect the tensioning of the winding layers in any way will occur in the area of the star discs 16 and their bracing.
[0030] FIG. 5 shows a second embodiment of a rotor 1, the layout of which corresponds to that of the preceding figure. In this embodiment, however, all of the metal sheets 4 are identical in form and all of them have only the small breach 9 or borehole in which the tie rod 12 is inserted. However, the tie rod 12 in this embodiment is longer, also extending through corresponding boreholes in the end-positioned star discs 16. The respective nuts 14 are received in corresponding indentations 17 on the respective star discs, i.e., once again they are countersunk and braced axially against the star discs 16. In terms of mounting technique, this means that the star discs 16 are positioned before placing the tie rods 12 and screwing them tight with the nuts 14, unlike in the embodiment described above where the star discs 16 are positioned only after the tensioning of the sheet metal pack. Even so, in this embodiment as well, an almost complete or a complete compacting of the sheet metal pack 3 free of air gaps is achieved, since the star discs 16 are braced axially directly and flat against the axial end faces of the sheet metal pack 3.
[0031] Basically, the possibility exists of leaving the tie rods 12 along with the nuts 14 in the rotor even after applying the windings 15, which is necessary if the nuts 14 have been axially wound over. But it would also be conceivable to loosen the nuts 14 once more and remove the tie rods 12 if the breaches 11 lie radially outward and are not in the wound region of the poles 6. This changes nothing about the geometry of the sheet metal pack 3 since the sheet metal pack 3 is axially tensioned and fixed by the respective tightly wound windings 15.
[0032] An embodiment of a rotor is shown in FIG. 6, next to the embodiment of FIG. 1. The breaches 11 and thus the tie rods 12 here lie further to the outside against the poles, so that they are not wound over. The nuts 14 here are also arranged, for example, at the end face, lying against the respective star discs 16. A recessed arrangement would also be conceivable. In any case, the nuts are accessible even after the winding process and can therefore be loosened afterwards, so that the tie rods 12 can be removed, thus reducing the weight of the rotor 1.
[0033] German patent application no. 10 2022 129147.2, filed Nov. 4, 2022, to which this application claims priority, is hereby incorporated herein by reference, in its entirety.
[0034] Aspects of the various embodiments described above can be combined to provide further embodiments. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled.
