Method for producing a rotor, rotor, and electric machine

Abstract

The invention relates to a method for producing a rotor (1) for an electric machine (2), in which - a laminated core (4), composed of individual laminations (3) and having grooves (7) which are separated from one another in the circumferential direction (5) and extend in the axial direction (6), is mounted on a rotor shaft (8) for conjoint rotation, wherein each groove (7) is delimited by two adjacent poles (9) each having a pole core (10) and a pole shoe (11), - a compensating and sealing element (13) is attached at least to a side (12) of a pole shoe (10) that faces the groove (7), - rotor windings (14) are arranged, in particular wound, on the pole cores (11) of the laminated core (4), - a groove closure wedge (15) is inserted into the associated groove (7), which wedge rests sealingly against the compensating and sealing element (13) and seals a cooling channel (16) extending in the groove (7).

Description

[0001] Method for manufacturing a rotor, rotor and electric machine

[0002] The present invention relates to a method for manufacturing a rotor for an electric machine. The invention also relates to a rotor manufactured according to this method and to an electric machine with such a rotor.

[0003] From US patent 3,766,417 A, a rotor is known with a laminated core composed of individual laminations with circumferentially separated and axially extending grooves, wherein insulating collars made of an electrically non-conductive material are arranged on the groove flanks for electrical insulation.

[0004] From EP 1 276205 B1, a rotor for an electric machine with a plurality of circumferentially arranged poles is known, wherein slots are arranged between the individual poles. Wedges with wedge covers are arranged in the slots, which bear against the rotor windings.

[0005] From EP 4 203277 A1 another rotor with slots is known, wherein the slots are lined with insulation before the rotor windings are applied.

[0006] From EP 4 203261 A1, a rotor with slots is known, wherein the slots are closed against an air gap by a slot closure wedge, which is held on pole shoes of the rotor by means of two beads engaging in corresponding receptacles. From EP 2 985 885 A1, a rotor with slots into which slot closure wedges are inserted is known.

[0007] Both rotors and stators of electrical machines, especially those of separately excited synchronous machines, are typically manufactured from stacked laminated timber elements to minimize eddy currents and magnetization losses as much as possible. However, the non-aligned stacking of the individual laminations creates a relatively rough surface on one side of the laminated core facing a slot in the rotor. This roughness makes sealing the slot difficult and also hinders the insertion of a seal, such as a slot sealing wedge, which can be damaged by the rough surface of the misaligned laminations. This is particularly important for electrical machines with directly cooled rotor or stator windings, as no cooling fluid, such as oil, should enter the air gap between the rotor and stator, as this would cause high losses and reduce the efficiency of the electrical machine.

[0008] In separately excited synchronous machines, a slot sealing wedge is typically used to seal the slot, which in this case contains a cooling channel for a cooling fluid. This wedge is inserted into the slot from one end face. However, if the wedge is pushed over the rough surface of the non-aligned stacked laminations, it can be damaged by the surface roughness of the lamination stack, preventing a complete seal. This is particularly relevant in high-speed electric machines, as the rotation generates high pressures in the cooling fluid, which can force it outwards through leakage points and into the air gap between the stator and rotor.

[0009] The present invention therefore deals with the problem of providing a method for manufacturing a rotor by means of which, in particular, a reliable sealing of cooling channels carrying cooling fluid in grooves of a rotor can be achieved.

[0010] This problem is solved according to the invention by the subject matter of independent claim 1. Advantageous embodiments are the subject matter of the dependent claims.

[0011] The present invention is based on the general idea of ​​providing a sheet metal stack with a rough surface, which is composed of individual sheets, with a leveling and sealing element, which has two essential advantages: Firstly, a rough surface facing a groove, which is due to a non-aligned arrangement of the individual sheets of the sheet metal stack, can be leveled, whereby a groove sealing wedge, which serves to seal a cooling channel running in the groove and carrying cooling fluid, no longer has to be pushed over the rough surface, but is guided along the smooth leveling and sealing element and therefore cannot be damaged.Secondly, the compensating and sealing element arranged on at least one side facing the groove provides a flat sealing surface against which the groove closure wedge can fit tightly, unlike on the rough surface of the laminated stacks assembled from individual laminations. In the inventive method for manufacturing a rotor for an electric machine, a laminated stack composed of individual laminations with circumferentially separated and axially extending grooves is first mounted rotationally on a rotor shaft, with poles with pole cores and pole shoes arranged between the grooves.Manufacturing tolerances, as well as imperfect axial alignment of the individual plates, can result in a rough surface, particularly on the side of a pole shoe facing the groove. This roughness can damage a groove-closing wedge when inserted and, more importantly, hinders a reliable seal. Therefore, a compensating and sealing element is attached to at least one side of the pole shoe facing its corresponding groove. This element smooths the rough surface of the groove-facing side of the pole shoe, allowing the groove-closing wedge to be inserted without damage, and also provides a smooth sealing surface.The smooth sealing surface not only facilitates sealing but also prevents damage that can occur when the slot sealing wedge is inserted over its rough surface. After attaching the compensating and sealing element to at least one side of a pole shoe facing the groove, the corresponding rotor windings are arranged, in particular wound, on the pole cores of the laminated core. A slot sealing wedge is then inserted into the corresponding groove, with the wedge sliding along the smooth compensating and sealing element during insertion, thus preventing damage. Furthermore, the slot sealing wedge rests tightly against the compensating and sealing element, sealing a cooling channel running within the groove. This cooling channel is bounded by the slot sealing wedge, the rotor windings or pole cores, and the rotor shaft.With the method according to the invention, it is thus possible for the first time to achieve a simple and reliable sealing of cooling channels running in grooves of a rotor of an electric machine, since the compensating and sealing elements used for this purpose enable both damage-free insertion of a groove closure wedge and a reliable seal between the groove closure wedge and the compensating and sealing element.

[0012] In an advantageous embodiment of the method according to the invention, a compensating and sealing element is used that extends over a side of a pole core facing the groove. In this case, the compensating and sealing element is preferably designed at right angles, with a first leg bearing against the side of the pole shoe facing the groove and a second leg bearing against the side of the pole core facing the groove. Such a compensating and sealing element thus runs between the rotor windings and the pole shoe or the pole core.

[0013] In a further advantageous embodiment of the method according to the invention, a compensating and sealing element is used that additionally extends over a side of the rotor shaft facing the groove. In this case, the compensating and sealing element has an almost closed shape, with the exception of the groove sealing wedge, and extends over the side of a first pole shoe facing the groove, the side of a first pole core facing the groove, the side of the rotor shaft facing the groove, the side of the second pole core directly adjacent to the first pole core in the circumferential direction, and the side of the second pole shoe adjacent to the first pole shoe facing the groove. This simplifies manufacturing because only a single compensating and sealing element is required.Furthermore, this seals the entire groove, particularly the radially inner area on the rotor shaft, against the passage of cooling fluid. In another advantageous embodiment of the method according to the invention, a magnetically conductive element, in particular a sheet metal element, is used as the compensating and sealing element. A magnetically conductive element as a compensating and sealing element offers the significant advantage of not reducing the width of a pole core, since a magnetic flux can also be conducted through the compensating and sealing element. Alternatively, it is of course also conceivable that a magnetically non-conductive element, for example made of plastic, is used as the compensating and sealing element. Such a plastic can, for example, be formed as an injection-molded part or as a potting compound, or applied by overmolding, transfer molding, or potting.Such a potting compound can, for example, be applied to the laminated core in the area of ​​the grooves. It is also conceivable that the compensating and sealing element, designed as a magnetically non-conductive element, is only arranged, and in particular applied, to the side of the pole shoe facing the groove, so that the magnetic flux through the pole core is not affected due to the absence of the compensating and sealing element there.

[0014] The present invention is further based on the general concept of providing a rotor for an electric machine manufactured using the method described above. This allows the advantages described for the inventive method to also be transferred to the inventive rotor manufactured using the inventive method. Specifically, the advantages lie in a reliable seal of a cooling channel located in the groove, thereby preventing the undesired leakage of cooling fluid from the cooling channel into an air gap between the rotor and the stator, which would lead to a reduction in efficiency.Furthermore, the rotor according to the invention reliably prevents damage to a groove locking wedge during insertion, since it is not pushed along the comparatively rough surface of the sheet metal stack composed of individual sheets, as before, but rather on the comparatively smooth and low-friction surface of the compensating and sealing element.

[0015] In a preferred embodiment of the rotor according to the invention, a recess for a compensating and sealing element is provided on at least one side of a pole shoe facing the associated groove. Additionally or alternatively, a recess for a compensating and sealing element can also be provided on at least one side of a pole core facing the groove. These recesses make it possible to position the compensating and sealing element, particularly if it is made of a magnetically conductive material, within the recess and thereby not only reliably, and especially positively, fix it in place, but also ensure that the cross-section of the pole shoe or pole core available for magnetic flux is not reduced. Thus, the material removed from the pole core or pole shoe is replaced by the compensating and sealing element.

[0016] In a further advantageous embodiment of the rotor according to the invention, the compensating and sealing element extends over a side of the pole core facing the groove and, in particular, even over a side of the rotor shaft facing the groove. This allows for a further improved lining of the groove, especially in the latter case.

[0017] In a further preferred embodiment of the rotor according to the invention, the compensating and sealing element is designed as a magnetically conductive element, in particular as a sheet metal element, or as a magnetically non-conductive element, in particular made of plastic. Such a plastic can, for example, be designed as an injection-molded part or as a potting compound, or applied by overmolding, transfer molding, or potting. If the compensating and sealing element is designed as a magnetically conductive element, the maintenance of the magnetic flux in the poles, i.e., the pole shoe and the pole core, can be reliably ensured. If the compensating and sealing element is designed as a magnetically non-conductive element, a reliable seal can be achieved with a comparatively thin coating without significantly impairing the magnetic flux.

[0018] The present invention is further based on the general concept of equipping an electric machine with a rotor described in the preceding paragraphs and thereby transferring the advantages described with respect to the rotor to the electric machine. Specifically, these advantages include a reliable seal for a cooling channel running in the groove of the rotor by means of a groove sealing wedge, which, according to the invention, rests tightly on a surface of the compensating and sealing element. Furthermore, when the groove sealing wedge is inserted into the groove, damage to the wedge during insertion can be reliably prevented by sliding it on the comparatively smooth and low-friction surface of the compensating and sealing element. This not only facilitates insertion but also increases the sealing effect in this case.

[0019] In a further advantageous development of the electric machine, it is designed as a separately excited synchronous machine. Separately excited synchronous machines offer the advantages of high efficiency across the entire operating range, high power density, and the elimination of permanent magnets, the production of which often requires expensive raw materials such as rare earth metals.

[0020] Further important features and advantages of the invention will become apparent from the dependent claims, the drawings and the associated description of the figures based on the drawings.

[0021] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the present invention. The components of a higher-level unit, such as a device, apparatus, or arrangement, mentioned above and those to be mentioned below, which are designated separately, can form separate parts or components of this unit or be integral areas or sections of this unit, even if this is depicted differently in the drawings.

[0022] Preferred embodiments of the invention are shown in the drawings and are explained in more detail in the following description, wherein identical reference numerals refer to identical or similar or functionally identical components.

[0023] They show, each schematically

[0024] Figure 1 shows a flowchart of a process according to the invention for manufacturing a rotor according to the invention, Figure 2 shows a cross-sectional view through a rotor according to the invention of an electrical machine according to a first embodiment,

[0025] Figure 3 shows a representation as in Figure 2, but according to a second embodiment.

[0026] Figure 4 shows a representation similar to Figure 2, but in a further embodiment.

[0027] Figure 5 shows a sectional view through one pole of the rotor according to the invention with recesses for receiving a compensating and sealing element,

[0028] Figure 6 shows a representation as in Figure 5, but with an inserted leveling and sealing element.

[0029] Figure 7 shows a longitudinal section through a rotor according to the invention with a laminated core of individual laminations without a compensating and sealing element.

[0030] Figure 8 shows a longitudinal section through a rotor according to the invention with a laminated core comprising individual laminations and a compensating and sealing element designed as a sheet metal element.

[0031] Figure 9 shows a longitudinal section through a rotor according to the invention, comprising a laminated core with individual laminations and a plastic compensating and sealing element. According to Figure 1, a method according to the invention for manufacturing a rotor 1 (see also Figures 2 to 6) for an electric machine 2 has a total of four process steps, A to D.

[0032] In process step A, a laminated core 4, composed of individual laminations 3, is first mounted non-rotatably on a rotor shaft 8. The core has grooves 7 separated from each other in the circumferential direction 5 and extending in the axial direction 6, which, according to Figures 2 to 6, runs orthogonally to the plane of the image. Between the grooves 7, 5 poles 9 with pole shoes 10 and pole cores 11 are arranged in the circumferential direction. The pole shoes 10 and pole cores 11 are usually integral, i.e., formed, for example, as a single piece, and in particular as a single unit.

[0033] In the subsequent process step B, a compensating and sealing element 13 is attached to at least one side 12 of a pole shoe 10 facing the groove 7. In the next process step C, rotor windings 14 are wound onto the pole cores 11. In other embodiments, the rotor windings 14 can also be attached to the pole cores 11 in other ways, such as by inserting prefabricated conductor elements, e.g., hairpin conductors. In process step D, a groove sealing wedge 15 is inserted into the corresponding groove 7. This wedge rests tightly on the compensating and sealing element 13, and of course on two adjacent compensating and sealing elements 13, and seals a cooling channel 16 running in the groove 7, through which a cooling fluid 17 flows to cool the rotor 1. The cooling channel 16 is thus closed by the groove closure wedge 15 and the compensating and sealing elements 13 (see figure).Figure 2) and, if the compensating and sealing elements 13 also extend over a side 18 of the pole cores 11 facing the groove 7 or a side 19 of the rotor shaft 8 facing the groove 7, also over the pole cores 11 or the rotor shaft 8, as shown in Figures 3 and 4. The compensating and sealing element 13 is made of a cooling fluid-resistant material.

[0034] In the embodiment of the rotor according to the invention shown in Figure 3, compensating and sealing elements 13 are used which extend over the side 18 facing the groove 7 of two adjacent pole cores 11. In the embodiment of the rotor 1 according to the invention shown in Figure 4, a compensating and sealing element 13 is used which additionally extends over the side 19 of the rotor shaft 8 facing the groove 7.

[0035] The inventive method makes it possible to significantly improve the sealing effect of the groove closure wedge 15 and to reliably seal the cooling channel 16 in the groove 7 to the outside, in particular against an air gap 20 between the rotor 1 and a stator 21 (see Figure 2), thereby reliably preventing unintentional and, in particular, centrifugal force-induced escape of cooling fluid 17 into the air gap 20. Escape of cooling fluid 17 between the individual laminations 3 or the lamination stacks 4 is prevented by the compensating and sealing element 13. The groove closure wedge 15 serves to close a groove opening. This reduces losses that would be generated by the cooling fluid 17 entering the air gap 20 and significantly increases the efficiency of the electric machine 2.

[0036] The compensating and sealing element 13 can be used in particular to equalize a rough surface 25 (see figures 7 to 9) in a sheet metal package 4 composed of individual sheets 3, especially on side 12, thereby reliably preventing damage to the groove locking wedge 15 when it is inserted into the groove 7 in the axial direction 6. The individual sheets 3 of the sheet metal stack 4 are usually not always aligned with each other in the axial direction 6, particularly due to manufacturing and dimensional tolerances, so that a rough surface 25 is created on the sides 18 and 12, i.e. on the side 18 of the pole cores 11 facing the groove 7 and the side 12 of the pole shoes 10 facing the groove 7 (compare figure 7), which could damage the groove locking wedge 15 when it is slid over it in the axial direction 6 and thus impair the sealing effect.Furthermore, even in an undamaged state, the groove locking wedge 15 cannot provide a reliable seal due to its comparatively rough surface 25, as cooling fluid 17 from the cooling channel 16 can enter the spaces between the groove locking wedge 15 and the surface 25 of the sheet metal stack 4, as well as between the individual sheets 3, and can reach the air gap 20. The compensating and sealing element 13, arranged at least on the side 12 of the pole shoes 10 facing the groove 7, also creates a smooth surface 26 (see Figures 8 and 9) on which the groove locking wedge 15 slides with low friction during insertion and also fits tightly.

[0037] Looking at Figures 5 and 6, it can be seen that a recess 22, 23 is arranged on the side 12 of the pole shoe 10 facing the groove 7, as well as on the side 18 of the pole core 11 facing the groove 7, in which the associated compensating and sealing element 13 is received. This is particularly advantageous if the compensating and sealing element 13 is made of a magnetically conductive material, especially a sheet metal element 27, since in this case the cross-section of the pole core 11 required for a magnetic flux 24 (compare Figures 5 and 6), in particular its width b, is not reduced.If the compensating and sealing element 13 is made of a magnetically non-conductive material / element, for example a potting compound (see Figure 9), then such recesses 22, 23 can be omitted, and a compensating and sealing element 13 made of potting compound can be applied directly and in a thin layer to side 12 of the pole shoe 10 or side 18 of the pole core 11, thereby smoothing the rough surface 25. In general, the compensating and sealing element 13 made of a magnetically non-conductive material / element, for example plastic 28, can also be formed as an injection-molded part or applied by overmolding, transfer molding, or potting.

[0038] Particularly in the illustrations of Figures 7 to 9, the initially rough surface 25 (compare Figure 7) of the lamination stack 4 can be seen, which could lead to damage to the compensating and sealing element 13 if it is slid over it. Figure 8 shows a compensating and sealing element 13 designed as a sheet metal element 27, which rests on the tips of the individual laminations 3. Figure 9 shows a compensating and sealing element 13 made of plastic 28, here as a potting compound, into which the ends 30 of the individual laminations 3 facing away from the rotor shaft 8 are embedded.

[0039] The cooling channel 16 is limited by the compensating and sealing elements 13, the slot closure wedge 15, and optionally the pole cores 11 and the rotor shaft 8. The latter applies if the compensating and sealing element 13 does not extend over the side 18 of the pole core 11 facing the slot 7 (see Figure 3) or over the side 19 of the rotor shaft 8 facing the slot 7 (see Figure 4). The advantage of the method and the rotor 1 according to the invention lies particularly in the creation of a smooth surface 26 compared to the relatively rough surface 25 of the individual laminations 3 of the lamination stack 4. This smooth surface allows the slot closure wedge 15 to be inserted into the slot 7 without damage and ensures a tight seal.

[0040] In general, to realize the invention, a compensating and sealing element 13 arranged on the side 12 of the pole shoe 10 facing the groove 7 is sufficient, since the groove closure wedge 15 only comes into contact with the compensating and sealing element 13 in this area.

Claims

Claims 1. Method for manufacturing a rotor (1 ) for an electric machine (2), wherein - a laminated core (4) composed of individual laminations (3) with grooves (7) separated from each other in the circumferential direction (5) and extending in the axial direction (6) is mounted non-rotatably on a rotor shaft (8), wherein each groove (7) is bounded by two adjacent poles (9) each with a pole core (10) and a pole shoe (11), - at least on one side (12) of a pole shoe (10) facing the groove (7) a compensating and sealing element (13) is attached, - rotor windings (14) are arranged, in particular wound, on the pole cores (11) of the laminated core (4), - a groove closure wedge (15) is inserted into the corresponding groove (7), which rests tightly on the compensating and sealing element (13) and seals a cooling channel (16) running in the groove (7).

2. Method according to claim 1, characterized in that a compensating and sealing element (13) is used which extends over a side (18) of a pole core (11) facing the associated groove (7).

3. Method according to claim 2, characterized in that a compensating and sealing element (13) is used which extends over a side (19) of the rotor shaft (8) facing the associated groove (7).

4. Method according to one of the preceding claims, characterized in that a magnetically conductive element, in particular a sheet metal element (27), is used as the compensating and sealing element (13).

5. Method according to one of claims 1 to 3, characterized in that a magnetically non-conductive element, in particular a plastic (28), is used as the compensating and sealing element (13).

6. Rotor (1 ) for an electric machine (2), manufactured according to the method of one of the preceding claims.

7. Rotor (1 ) according to claim 6, characterized in that at least on one side (12) of a pole shoe (10) facing the associated groove (7) a recess (22) for a compensating and sealing element (13) is provided.

8. Rotor (1 ) according to claim 6 or 7, characterized in that at least on one side (18) of a pole core (11 ) facing the associated groove (7) a recess (23) for a compensating and sealing element (13) is provided.

9. Rotor (1 ) according to one of claims 6 to 8, characterized in that the compensating and sealing element (13) extends over a side (18) of a pole core (11 ) facing the associated groove (7).

10. Rotor (1 ) according to claim 9, characterized in that the compensating and sealing element (13) extends over a side (19) of the rotor shaft (8) facing the associated groove (7).

11. Rotor (1) according to one of claims 6 to 10, characterized in that, - that the compensating and sealing element (13) is designed as a magnetically conductive element, in particular as a sheet metal element (27), or - that the compensating and sealing element (13) is designed as a magnetically non-conductive element, in particular made of plastic (28).

12. Electric machine (2) with a rotor (1 ) according to one of claims 6 to 11.

13. Electrical machine (2) according to claim 12, characterized in that the electrical machine (2) is designed as a separately excited synchronous machine.

Images