Rotor for a permanent magnet electric machine, electric machine and method for manufacturing such a rotor

Abstract

Rotor for a permanent magnet electric machine, comprising a laminated core (2) consisting of a plurality of individual, axially stacked laminations (3a, 3b, 3c, 3d, 3e), wherein each lamination (3a, 3b, 3c, 3d, 3e) has several openings (4a, 4b, 4c, 4d, 4e) and the laminations (3a, 3b, 3c, 3d, 3e) are positioned relative to one another such that several pockets (5) extending axially through the laminated core (2) are formed in each of which at least one magnetic element (6) is received, wherein each magnetic element (6) is embedded in a potting material (7) that completely fills the pocket (5), wherein the two terminal laminations (3a) are joined on an outer surface (12) of the respective lamination (3a) at least one edge (11a) bordering an opening (4a) The opening (4a) has a sloping edge section (10a), with the potting material (7) being flush with the outside (12) and filling the edge section (10a).

Description

[0001] The invention relates to a rotor for a permanent magnet electric machine, comprising a laminated core consisting of a plurality of individual, axially stacked laminations, each lamination having several perforations and the laminations being positioned relative to each other in such a way that several pockets axially penetrating the laminated core are formed in each of which at least one magnetic element is received, each magnetic element being embedded in a potting material that completely fills the pocket.

[0002] Such a rotor consists of numerous individual laminations stacked to form a core, each containing magnetic elements, usually permanent magnets. Balancing discs are often attached to both ends of the core to ensure the rotor's concentricity. If the outer diameter of the balancing discs matches the diameter of the core, i.e., the rotor diameter, the two axially end laminations are axially fixed by the balancing discs. However, sometimes balancing discs with a smaller outer diameter than the rotor diameter are used, or, if not required, the rotor can be built without such balancing discs.In these cases, the problem arises that the two end sheets, or even other adjacent sheets, detach axially from the laminated core at the outer edge because they are not additionally held in position axially by the balancing discs. This results in the laminated core fanning out at the edges due to the lack of radial support in the axial direction. To provide axial support for the end sheets in such cases, it is known to use so-called end caps, which, however, require an additional machining step and the use of appropriate material to injection-mold the ends of the laminated core.

[0003] The invention is based on the problem of providing an improved rotor in comparison.

[0004] To solve the problem, in a rotor of the type mentioned above, it is provided according to the invention that the two terminal sheets have at least one edge section sloping towards the opening on an outer side of the respective sheet on at least one edge bordering a perforation, wherein the potting material flush with the outer side fills the edge section.

[0005] According to the invention, at least the two end sheets have a specific edge shape on at least one edge bordering a perforation, which allows a kind of axial overlap to be achieved via the potting compound filling this specific edge geometry, thus axially fixing the respective end sheet. For this purpose, at least one edge bordering a perforation serving to form a magnetic element pocket is designed with at least one edge section sloping down towards the perforation, meaning that the edge is not quasi-sharp at a 90° angle, but has a different geometry, for example, sloping down towards the perforation.Since the potting compound in which the magnetic elements inserted into the pockets are embedded is axially flush with the outer surface and therefore inevitably also fills the specific edge section, an axial overlap of the finally cured potting compound over this edge section occurs. This ensures that the respective end sheet is held axially in position and cannot move axially from the adjacent sheet. A local positive fit is thus created between the potting compound and the end sheet in the axial direction, so that the end sheet is axially fixed by the cured potting compound and cannot detach. The potting compound serves to fix the magnetic elements in the pockets, is therefore already present in sufficient quantity, and is now, according to the invention, also used for the axial fixation of the respective end sheet due to the edge geometry provided according to the invention.Since such local positive locking anchors are provided on both terminal sheets, i.e., the opposite ends of the sheet metal stack, and both sheets are locked against movement in the axial direction, fanning out is consequently prevented on both sides.

[0006] Therefore, the use of separate end caps is not required, while at the same time the end sheets are optimally fixed.

[0007] Although it is sufficient to design only the respective axially terminal sheet with a corresponding edge geometry and at least one sloping edge section, it is conceivable that at least the sheet following the respective terminal sheet stack towards the rotor interior also has, on its side facing the rotor end, at least one edge section sloping towards the opening, with the potting material filling the edge section. Accordingly, not only is the respective terminal sheet geometrically configured according to the invention, but also at least the next sheet, i.e., the sheet lying in the second sheet plane, so that the corresponding anchoring, achieved via the positive locking of the potting compound with the respective sheet, is also provided there.Of course, the next or the following sheet metal can also be provided with an edge geometry or edge section according to the invention, so that a corresponding anchoring also results in this third or fourth level.

[0008] Preferably, several or even all edges of the sheets, which have a corresponding edge geometry according to the invention, that define a perforation have at least one such edge section. This means that, preferably, corresponding positive locking areas are formed between the potting compound and the sheet at several positions distributed across the surface, so that the anchoring according to the invention can be realized at several positions across the end face of the rotor.

[0009] It is preferred that both the terminal sheets and one or more further sheets following towards the rotor interior are provided with the edge geometry according to the invention and consequently have one or more such sloping edge sections, such that the edge sections of the different sheets are axially aligned with one another. This means that, viewed axially, the individual local anchorages in the respective anchorage planes are axially aligned with one another.

[0010] As described, the edge section slopes down towards the inside of the opening. Preferably, each edge section is designed as a sloping surface. Viewed from the outside, for example, of the end sheet, the sloping surface therefore slopes diagonally towards the opening. Forming such a sloping surface is particularly easy to do during the punching of the opening on the respective sheet using the punching tool, so that no separate work step is required.

[0011] It is conceivable that each edge of a sheet metal panel that is provided with an edge section has several local edge sections. This means that several such local edge sections or inclined surfaces, i.e., small local chamfers, are provided around the opening. Therefore, with respect to the individual opening, there are several local anchoring positions between the potting compound and the sheet metal.

[0012] Alternatively, the edge section could extend along the entire edge. This means that each edge is chamfered, sloping down towards the opening along its entire length. In this case, the positive fit is ensured along the entire edge length.

[0013] In addition to the rotor itself, the invention further relates to an electric machine comprising a rotor of the type described above.

[0014] Furthermore, the invention relates to a method for manufacturing a rotor of the type described above. This method is characterized by the following steps: - Providing several sheets with punched openings, wherein at least two of these sheets have at least one edge section sloping towards the opening on an outside side of the respective sheet at at least one edge bordering an opening; - Forming a sheet metal stack from the sheets, wherein the openings complement each other to form pockets axially extending through the sheet metal stack and two sheets having an edge section are arranged at the ends of the sheet metal stack; - Inserting one or more magnetic elements into the pockets and filling the pockets with a potting material that is flush with the outer surfaces of the terminal sheets and fills the edge sections.

[0015] In this variant of the process, the sheets with the edge section(s) are pre-formed during the punching of the openings, thus creating the edge sections. After the individual sheets have been manufactured, it is only necessary to stack the sheet metal stack, whereby the end sheets must, of course, be positioned at the corresponding axial end position, and, if necessary, sheets may also be arranged in one or more subsequent layers, as described above. After the sheet metal stack has been formed, the sheets can be easily fixed together by means of a punching stacking process, after which the magnetic elements are inserted into the pockets and fixed within them by injecting the potting compound. Once cured, the potting compound also ensures the axial securing of the end sheets, as described above.

[0016] In one variant, the invention provides for a further method for manufacturing such a rotor, comprising the following steps: - Providing several sheets with punched-out perforations; - Forming a sheet metal stack from the sheets, whereby the openings complement each other to form pockets that extend axially through the sheet metal stack; - Forming at least one edge section sloping towards the pocket on an outside side of each of the two terminal sheets on at least one edge bordering a perforation; - Inserting one or more magnetic elements into the pockets and filling the pockets with a potting material that is flush with the outer surfaces of the terminal sheets and fills the edge sections.

[0017] In this variant of the process, all sheets are simply punched with the perforations; any preparations for forming edge sections are not yet made in this step. Only after the sheet stack has been formed are the edge sections formed on the outer surfaces of the two end sheets by appropriate forming. After this processing, the magnetic elements are then inserted and the pockets are filled with injection-molded material to join the sheets together via the potting compound and to fix the magnetic elements, as well as to achieve the axial positive locking provided for in the invention.

[0018] The invention is explained below with reference to exemplary embodiments and the drawings. The drawings are schematic representations and show: Fig. 1 A schematic representation of a rotor according to the invention in axial plan view of an end face of the rotor, in a partial view, Fig. 2 a sectional view through the rotor Fig. 1 along line II - II, Fig. 3 a representation accordingly Fig. 2 of a further embodiment of a rotor according to the invention, Fig. 4 a schematic representation of the production of an undercut on the stacked sheet metal package, and Fig. 5 the arrangement from Fig. 4 after inserting the magnetic elements and applying the potting material.

[0019] Fig. Figure 1 shows a rotor 1 according to the invention for a permanent magnet electric machine. The rotor 1 comprises a laminated core 2 consisting of a plurality of individual, axially stacked laminations 3a, 3b, 3c, 3d, 3e, ... see also Figure 1. Fig. 2. Each of the sheets has a plurality of individual perforations 4a, 4b, 4c, 4d, 4e, ..., wherein the individual sheets 3a, 3b, 3c, 3d, 3e are arranged such that the perforations 4a, 4b, 4c, 4d, 4e are axially aligned with one another and form axially extending pockets 5 that penetrate the sheet stack 2. At least one magnetic element 6 is inserted into each pocket 5, which, after insertion, is embedded in a potting material 7 that is injected into the respective pocket 5. The potting material 7 completely embeds the magnetic elements 6 radially, with the potting material 7 completely filling the respective pocket 5, i.e., extending to the axially terminal sheet 3a (and, of course, also to the sheet arranged on the opposite side, which is not shown here) and being flush with it, as shown. Fig. 2 shows. How Fig. Figure 1 shows that the pockets in the actual receiving area are essentially adapted to the geometry of the magnetic elements 6, but they mostly have lateral extensions which are also filled with the potting material 7.

[0020] The openings 4a, 4b, 4c, 4d, 4e in the individual sheets 3a, 3b, 3c, 3d, 3e are each produced by punching. A suitable punching tool is used for this purpose. Typically, each opening 4a, 4b, 4c, 4d, 4e has a more or less sharp edge on both sides of the sheet, as shown in the figure. Fig. 2, for example, a die-cut indentation 8 may be present on an edge due to the manufacturing process. This leads to an edge or border geometry as described in Fig. Figure 2 shows the plates 3b, 3c and 3d. This figure shows a sectional view along line II - II in Fig. Figure 1 shows a section of a pocket 5, which in the example shown contains only potting compound. This sectional view shows five sheets 3a, 3b, 3c, 3d, and 3e, where sheet 3a is an end sheet, i.e., an outer sheet, while sheets 3b–3e follow towards the rotor's interior. Due to the stamping geometry, corresponding steps are formed, starting in the example shown at the transition from sheet 3b to sheet 3c. These steps are filled by the potting compound 7, creating corresponding areas 9 in which the potting compound 7 slightly overlaps the sheet leading towards the rotor's interior axially. This results in a localized positive fit between the hardened potting compound 7 and the individual sheets, effectively connecting them. However, such a positive fit would not be possible at the end sheet 3a if it had an edge geometry like all the other sheets.

[0021] In order to anchor sheet 3a axially in a simple manner and, in particular, to fix it in a radially outer area, so that fanning out or detachment of sheet 3a from sheet 3b is avoided, the edge geometry of the edges bordering the respective openings 4a, 4b, 4c, 4d, 4e in the terminal sheet 3a is selected differently or designed differently during the punching process of the respective openings 4a, 4b, 4c, 4d, 4e. Fig. As shown in Figure 2, the opening 4a in the sheet 3a is provided with an edge section 10a that slopes down towards the opening 4a and is designed in the form of a beveled surface. This results in a kind of chamfer on this side of the sheet, with this chamfer opening towards the outer surface 12 of the sheet 3a, as shown. Fig. Figure 2 clearly shows this. This sloping edge geometry, i.e., edge section 10a, is preferably formed all around the entire edge 11, resulting in a circumferential chamfer. Since, as described, the potting compound 7 is injected into the respective pocket 5 to such an extent that it is flush with the outer surface 12, the potting compound 7 consequently also fills edge section 10a, as shown. Fig. Figure 2 shows that, in the hardened state, a section of potting material 13a is formed, which positively fills the edge section 10a and consequently forms an overlap. The end sheet 3a is locally fixed to this side via this axial overlap, and the sheet metal assembly is maintained by this potting material 7. The end sheet on the other side of the rotor 1 is anchored in the same way, meaning that it also has an edge section opening outwards towards the outer surface of the sheet, which is filled in the same way with a corresponding section of potting material, thus achieving axial anchoring, but in the opposite direction. Fig. 3 is shown directed.

[0022] Such an edge geometry is particularly necessary for pockets 5 located in the radially outer region of the rotor 1 in order to achieve radially external axial anchorage. Radially internal axial anchorage can be achieved using balancing discs or pressure discs, usually mounted axially at the ends, which have a smaller outer diameter than the rotor 1. If no balancing discs or pressure discs are provided, the pockets 5 located further inwards, or even radially inwards extending sections of individual pockets 5, can of course also be equipped with corresponding edge sections, as shown in Fig. 2 shown, provided so that anchoring zones also lie radially further inwards.

[0023] It is not necessary for an edge segment 10a to always extend around the entire edge 11a, i.e., to be designed as a continuous chamfer. Instead, it is also conceivable that an edge segment 10a is only provided locally on one edge 11a, and that, for example, several local edge segments are provided along the length of the entire edge 11a. Even in such a case, optimal axial anchorage is ensured.

[0024] In the embodiment according to Fig. 2. Only the terminal sheet 3a (and of course also the terminal sheet on the other side of the rotor) is designed with a corresponding edge geometry comprising a sloping edge section 10a, which is designed as an inclined surface. However, it is also conceivable to design one or more further sheets towards the inside of the rotor in the same way. An example of this is shown. Fig. 3. There, too, a section is shown in accordance with the view shown. Fig. Figure 2 shows a cross-sectional view through the rotor 1 in the area of ​​a pocket 5, again with the sheets 3a, 3b, 3c, 3d, and 3e. In the example shown, the sheets 3a, 3b, and 3c are all identical and each has an edge section 10a, 10b, 10c that slopes down towards the respective opening 4a, 4b, 4c. This inevitably results in the potting material 7 having corresponding potting material sections 13a, 13b, 13c that form-fittingly fill the respective edge section 10a, 10b, 10c. Consequently, a kind of Christmas tree structure results, as in Fig. Figure 3 shows that this structure achieves anchoring in several, here three, planes. Naturally, a corresponding configuration is also present on the opposite side of the rotor. The orientation of the corresponding edge sections 10a, 10b, 10c is, of course, reversed there compared to Figure 3. Fig. 3 shown, so that an axial fixation towards the interior of the rotor is achieved on both sides.

[0025] Fig. Figure 4 shows one way in which a local deformation can be created on the finished stacked sheet metal package to form an undercut. Here, after stacking the sheets, of which only sheets 3a - e are shown here, a depression 15 is locally introduced, i.e., pressed in, in the area of ​​edge 11a using a suitable tool 14. The sheets are plastically deformed on the edge side, so that a Fig. 4 forms the deformation geometry shown, which, when filled with the potting material 7, locally overlaps the potting material section 13a, as Fig. Figure 5 shows that several such local depressions 15 can be formed along the edge 11a, resulting in several such local deformation geometries and corresponding overhangs of the casting material 7. Reference symbol list 1 Rotor 2 sheet metal packages 3a - 3e Sheet metal 4a - 4e breakthrough 5 bags 6 magnetic elements 7 Potting compound 8 Punch feed 9 area 10a - 10c edge section 11 edge 12 Outside 13a - 13c potting material section

Claims

[1] Rotor for a permanent magnet electric machine, comprising a laminated core (2) consisting of a plurality of individual axially stacked laminations (3a, 3b, 3c, 3d, 3e), wherein each lamination (3a, 3b, 3c, 3d, 3e) has several openings (4a, 4b, 4c, 4d, 4e) and the laminations (3a, 3b, 3c, 3d, 3e) are positioned relative to each other such that several pockets (5) extending axially through the laminated core (2) are formed in each of which at least one magnetic element (6) is received, wherein each magnetic element (6) is embedded in a potting material (7) that completely fills the pocket (5), characterized by , that the two terminal sheets (3a) have at least one edge section (10a) sloping down towards the opening (4a) on at least one edge (11a) bordering a perforation (4a) on an outer side (12) of the respective sheet (3a), wherein the potting material (7) flush with the outer side (12) fills the edge section (10a). [2] Rotor according to claim 1, characterized by , that at least the sheet (3b) following the respective terminal sheet (3a) towards the rotor interior also has at least one edge section (10b) sloping down towards the opening (4b) on its side facing the rotor end on at least one edge bordering an opening (4b), wherein the potting material (7) fills the edge section (10b). [3] Rotor according to claim 1 or 2, characterized by , that several or all edges bounding a gap (4a, 4b, 4c) have at least one edge segment (10a, 10b, 10c). [4] Rotor according to claim 2 or claim 2 and 3, characterized by , that the edge sections (10a, 10b, 10c) of the different sheets (3a, 3b, 3c) are axially aligned with each other. [5] Rotor according to any one of the preceding claims, characterized by , that the or each edge segment (10a, 10b, 10c) is designed as an inclined surface. [6] Rotor according to any one of the preceding claims, characterized by , that on the or each edge of a sheet (3a, 3b, 3c) several local edge sections (10a, 10b, 10c) are provided. [7] Rotor according to any one of claims 1 to 6, characterized by , that the edge segment (10a, 10b, 10c) extends along the entire edge. [8] Electric machine comprising a rotor (1) according to any of the preceding claims. [9] Method for manufacturing a rotor according to any one of claims 1 to 7, comprising the following steps: - Providing several sheets with punched openings, wherein at least two of these sheets have at least one edge section sloping towards the opening on an outside side of the respective sheet at at least one edge bordering an opening; - Forming a sheet metal stack from the sheets, wherein the openings complement each other to form pockets axially extending through the sheet metal stack and two sheets having an edge section are arranged at the ends of the sheet metal stack; - Inserting one or more magnetic elements into the pockets and filling the pockets with a potting material that is flush with the outer surfaces of the terminal sheets and fills the edge sections. [10] Method for manufacturing a rotor according to any one of claims 1 to 7, comprising the following steps: - Providing several sheets with punched-out perforations; - Forming a sheet metal stack from the sheets, whereby the openings complement each other to form pockets that extend axially through the sheet metal stack; - Forming at least one edge section sloping towards the pocket on an outside side of each of the two terminal sheets on at least one edge bordering a perforation; - Inserting one or more magnetic elements into the pockets and filling the pockets with a potting material that is flush with the outer surfaces of the terminal sheets and fills the edge sections.

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