Laminated core for an electric machine

Abstract

Laminated stack for an electric machine, comprising - a plurality of individual sheets (10), each individual sheet having at least one magnetic pocket (2) for receiving a magnetic element (3), - at least one magnetic element (3) which is arranged in the magnetic pocket (2), - at least one weld seam (4) which is provided on the magnetic pocket (3), and - a clamping connection (9) between the magnetic element (3) and the magnetic pocket (2) for fixing the magnetic element (3) in the magnetic pocket (2), - wherein the clamping connection (9) is based on a distortion of at least one wall region (21) of the magnetic pocket (2) caused by the weld (4), wherein each magnetic pocket (2) has a first and second weld (4), wherein the first weld is provided at a first corner region (11) and the second weld is provided at a second corner region (12) of the magnetic pocket, such that the two welds (4) at each magnetic pocket (2) cause a distortion when the weld cools, which clamps the magnetic element (3) between the two wall regions (21, 22) of the magnetic pockets (2) respectively.

Description

State of the art

[0001] The present invention relates to a laminated core for an electrical machine, such an electrical machine and a method for producing a laminated core with magnetic elements.

[0002] In electrical machines, stacked laminated cores are used, for example, in the rotor and / or stator. Such laminated cores often have magnetic pockets to accommodate permanent magnets, for example. The position of the permanent magnets in the magnetic pockets must be ensured over the entire service life of the electrical machine, even after balancing. The permanent magnets are fixed in place using various processes in series production. One possibility, for example, is to glue the permanent magnets into the magnetic pockets of the laminated core using an adhesive. The advantage here is that the permanent magnet can be inserted into the magnetic pocket without any force. The associated manufacturing process, however, is relatively complex, since the adhesive has to be cured in an oven and precise positioning of the magnetic elements is not possible.Alternatively, the magnetic elements can be caulked into the magnetic pockets using an additional caulking element. However, this would require an additional recess in the magnetic pocket for a caulking element, which would lead to iron loss in the laminated core. Furthermore, the caulking process results in localized stress on the magnetic elements, potentially resulting in damage. Furthermore, it is known to provide a so-called caulking seam for transporting laminated cores, which connects the multitude of individual sheets to one another in the axial direction. Such a caulking seam is provided on the outer circumference of the laminated core and is designed as a heat-conducting seam. It serves no function in the assembled electrical machine.

[0003] Weld seams or weld beads on the circumference of an IPM rotor are known, for example, from the following patent publications: JP 2002- 369 424 A, JP 2010-207 073 A or US 2011 / 0 248 596 A1. Disclosure of the invention

[0004] The laminated core according to the invention for an electrical machine with the features of claim 1 has the advantage that a permanent fixation of a magnetic element in a magnetic pocket of the laminated core is possible in a simple and cost-effective manner. The fixation is achieved according to the invention by providing a weld seam, wherein, however, the weld seam does not weld the magnetic element to the laminated core, but rather the weld seam is provided on the magnetic pocket in such a way that a clamping connection can be formed between the magnetic element and wall regions of the magnetic pocket. The clamping connection is based on a distortion of at least one wall region of the magnetic pocket caused by the weld seam, whereby the magnetic element is clamped in the magnetic pocket. This also has the advantage that no undesirable air gap or non-magnetic gap, such asIn the prior art, this is achieved by the adhesive used when gluing the magnetic element into the magnetic pocket. Furthermore, the magnetic element can be inserted into the magnetic pocket without applying force, allowing the magnetic element to be fixed in the magnetic pocket without damage. Furthermore, no additional caulking element or the like is required to secure the magnetic element in the laminated core.

[0005] The subclaims show preferred developments of the invention.

[0006] Preferably, the weld seam is provided at least in a first corner region of the magnetic pocket. Particularly preferably, at least two weld seams are provided, which are formed in a first and second corner region of the magnetic pocket. Providing two weld seams at the corner regions of the magnetic pocket enables particularly secure clamping of the magnetic element in the magnetic pocket. Alternatively, the weld seams are provided in a wall region of the magnetic pocket.

[0007] Further preferably, the weld seam is provided such that the weld seam extends in the axial direction of the laminated core across the plurality of individual laminations and connects all of the individual laminations to one another. Thus, the weld seam also has a second function as a stacking seam for the loose individual laminations. The magnetic element is held by each individual lamination by clamping wall areas of the magnetic pockets in the laminated core.

[0008] Particularly preferably, the weld seam is produced using a non-magnetic filler material, enabling magnetic separation of the adjacent areas of a single sheet metal sheet. Alternatively, a non-magnetic seam is created by mixing the filler material and sheet metal during the welding process. This can improve the performance of an electrical machine, since the non-magnetic weld seams enable targeted guidance of the magnetic flux. Thus, the weld seam according to the invention can perform a further additional function, namely that of magnetically separating areas of the laminated core.

[0009] The laminated core preferably has a circular outer circumference, so that the laminated core as a whole has a substantially cylindrical shape or is provided as a tubular section. The weld seam can be provided on an outer circumference and / or inner circumference of the laminated core.

[0010] More preferably, the laminated core comprises a central recess in which a shaft is arranged. Alternatively, an external rotor design without a shaft is conceivable. This allows the laminated core to be designed as the rotor of an electric machine. Alternatively, the laminated core can be designed as a stator.

[0011] The magnet further preferably has a corrosion protection layer. Since the invention allows for damage-free installation and fixation of the magnetic element in the magnet pocket, the corrosion protection layer is not damaged during installation, so that it can provide its corrosion-preventing effect throughout the entire service life of the laminated core.

[0012] The magnetic pocket preferably has a first and a second wall region, which are provided parallel to one another. Alternatively, the wall regions extend in a radial direction. More preferably, the magnetic pocket has a trapezoidal shape in plan view, with the trapezoidal shape widening radially outward. The weld seams are preferably formed at the corner regions of the widening trapezoid.

[0013] Preferably, the non-magnetic filler used to produce the weld is NiCr 22 Mon g Fe. The non-magnetic filler material preferably forms an austenitic weld seam in the remelted state.

[0014] Furthermore, the present invention relates to an electrical machine, in particular an electric motor, comprising a laminated core according to the invention. The laminated core is preferably designed as a rotor or as a stator of the electrical machine.

[0015] The present invention further relates to a method for fixing magnetic elements in magnetic pockets of a laminated core comprising a plurality of individual sheets. The method comprises the steps of positioning at least one magnetic element loosely or with slight compression or as a transition fit in mutually aligned magnetic pockets of the laminated core and producing a weld seam on a wall region of the magnetic pockets. The weld seam is produced in such a way that, upon cooling of the weld seam, distortion occurs in at least one wall region of the magnetic pocket such that the magnetic element is clamped in the magnetic pocket. This enables simple and rapid fixing of the magnetic element by clamping without damage and without the use of additional fixing aids such as adhesive, caulking elements or the like.

[0016] Particularly preferably, two welds are produced on one magnetic pocket. The welds are preferably produced simultaneously to ensure secure clamping of the magnetic element in the magnetic pocket.

[0017] The weld seams are further preferably designed such that they run in the axial direction and function as a stacking seam, i.e., all individual sheets of the laminated core are connected to one another via the weld seam. The weld seams can also be formed in shapes other than a straight line, e.g., zigzag or V-shaped, running in the axial direction.

[0018] The welds are preferably made using a non-magnetic material. drawing

[0019] A preferred embodiment of the invention will be described in detail below with reference to the accompanying drawings. In the drawing: Fig. 1 a schematic perspective view of a laminated core according to the invention with a plurality of magnetic elements, Fig. 2 a schematic plan view of the laminated core of Fig. 1, Fig. 3 to 5 are schematic views illustrating the clamping process of the magnetic element in the magnetic pocket according to the invention, and Fig. 6 and Fig. 7 schematic partial sectional views of the production of the weld seam on the magnetic pocket. Preferred embodiment of the invention

[0020] The following is based on the Fig. 1 to 7 a laminated core 1 according to a preferred embodiment of the invention is described in detail.

[0021] Fig. 1 shows a schematic perspective view of a laminated core 1 according to the invention, which in this embodiment is designed as a rotor of an electrical machine.

[0022] The laminated core 1 comprises a plurality of individual sheets 10 which are arranged in a mutually aligned manner.

[0023] Each individual sheet 10 of the laminated core is designed identically.

[0024] As is particularly evident from Fig. As can be seen in Figure 2, each individual sheet 10 comprises several magnetic pockets 2, which are arranged along the outer circumference of the individual sheet 10. Furthermore, a central recess 5 is provided in each sheet. The central recess 5 of the individual sheets 10 serves to accommodate a shaft 6, as can be seen from Fig. 1 is evident.

[0025] The magnetic pockets 2 essentially have a trapezoidal shape with a first wall region 21 and a second wall region 22. The two wall regions 21, 22 run parallel to each other.

[0026] The magnetic pockets 2 of the individual sheets 10 form in the laminated core 1 a receiving space extending in the axial direction XX for receiving a magnetic element 3. The magnetic element 3 is shown schematically from the Fig. 1 and Fig. 2. The magnetic elements 3 are cuboid-shaped components and can be made of a permanent magnetic material or a magnetizable material. The length of the magnetic elements 3 in the axial direction XX of the laminated core 1 corresponds to the axial length of the laminated core.

[0027] The magnetic elements 3 are fixed in the magnetic pockets 2 of the laminated core 1 by a clamping connection 9. The clamping connection 9 is implemented on each magnetic pocket 2 in such a way that, by providing two weld seams 4 on each magnetic pocket 2, a distortion occurs during cooling of the weld seam, so that the magnetic element 3 is clamped between the two wall areas 21, 22 of the magnetic pockets 2. This results in a clamping force F, as shown in Fig. 5 shown schematically.

[0028] Fig. 3 shows the initial state in which a magnetic element 3 is loosely arranged in a magnetic pocket 2 of the laminated core. Fig. 3, the reference numeral 8' shows an outer circumference of the laminated core 1 before the welding process. The reference numeral 21' denotes the first wall area of ​​the magnetic pocket 2, also before the welding process. Furthermore, Fig. 3 shows the shape of the outer circumference 8 and the first wall area 21 after the welding process in dashed lines.

[0029] As from Fig. 4, two weld seams 4 are provided at the two corner areas 11, 12 of the magnetic pocket 2. The weld seams 4 are provided in such a way that a non-magnetic filler material 40 is applied to the outer circumference 8' and then welded to the material of the laminated core by means of a welding process, e.g., by means of laser welding ( Fig. 6). This results in a weld seam 4, which runs parallel to the axial direction XX (compare Fig. 1). The application of the filler material 40 and the subsequent weld seam 4 are described in detail in the Fig. 6 and Fig. 7 shown.

[0030] The provision of the weld seam 4 results in a distortion of a partial area 13 of each individual sheet 10 in the area between the two weld seams 4. This is in Fig. 4 by the arrows A and B. This distortion of the partial area 13 causes in particular a change in shape of the first wall area 21 such that the first wall area 21 is deformed in the direction of the second wall area 22 (arrow B in Fig. 4). This allows the clamping connection between the magnetic element 3 and the plurality of magnetic pockets 2 of the individual sheets 10 to be realized. The magnetic elements 3 are thus clamped by means of a clamping force F (compare Fig. 5) between the first wall area 21 and the second wall area 22.

[0031] Thus, according to the invention, magnetic elements 3 can be fixed in magnetic pockets 2 of a laminated core 1 without the need for additional adhesive or caulking or the like. The magnetic elements 3 are fixed while the weld seams 4 are cooling. Preferably, two weld seams are provided per magnetic pocket 2, particularly at the corner regions 11, 12. The weld seams 4 extend over the entire axial length of the laminated core 1. As a result, the weld seams 4 also serve as stacking seams, so that the plurality of individual sheets 10 are connected to one another by the weld seams 4.

[0032] The weld seams 4 are designed such that they do not come into contact with the magnetic element 3. This prevents damage to the magnetic elements 3. Furthermore, since the weld seams 4 are made of a non-magnetic material, a targeted guidance of the magnetic flux in the laminated core is possible. For this purpose, the weld seams 4 are designed in the form of austenitic seams, making it possible to create a locally present, austenitic structure with low magnetic flux. This makes it possible, in particular, to reduce unwanted stray flux.

[0033] According to the invention, the heat input and shrinkage of the weld seam 4 thus lead to residual welding stresses, resulting in distortion of the component. These consequences of the welding process are usually undesirable, but are specifically used according to the invention for the provision of a clamping connection 9 between the magnetic element 3 and the magnetic pockets 2. The weld seams 4 on the outer circumference of the laminated core 1 generate, in particular, tangential shrinkage stresses (arrows A), from which the welding distortion (arrows B in Fig. 4). The magnetic elements 3 can be inserted into the magnetic pockets 2 without force or with slight pre-compression or with a transition fit, thus preventing damage to the magnetic elements 3, especially if they also have a corrosion protection layer. Fig.To illustrate the forceless insertion, an air gap 7 is shown as an example in Figure 3, which is no longer present after the weld seams 4 have been provided. Furthermore, according to the invention, a high magnet utilization rate can be achieved because, after the weld seams 4 have been provided, there is no gap between the magnetic element 3 and the laminated core 1. The laminated core according to the invention is also particularly suitable for mass production, since the provision of the weld seam can be automated relatively easily and all weld seams 4 can be produced, in particular, simultaneously or sequentially.

Claims

[1] Laminated core for an electrical machine, comprising - a plurality of individual sheets (10), each individual sheet having at least one magnetic pocket (2) for receiving a magnetic element (3), - at least one magnetic element (3) which is arranged in the magnetic pocket (2), - at least one weld seam (4) provided on the magnetic pocket (3), and - a clamping connection (9) between the magnetic element (3) and the magnetic pocket (2) for fixing the magnetic element (3) in the magnetic pocket (2), - wherein the clamping connection (9) is based on a distortion of at least one wall region (21) of the magnetic pocket (2) caused by the weld seam (4), wherein each magnetic pocket (2) has a first and a second weld seam (4), wherein the first weld seam is provided at a first corner region (11) and the second weld seam is provided at a second corner region (12) of the magnetic pocket, so that the two weld seams (4) on each magnetic pocket (2) cause a distortion when the weld seam cools, which clamps the magnetic element (3) between the two wall regions (21, 22) of the magnetic pockets (2). [2] Laminated core according to one of the preceding claims, characterized by that the weld seam (4) runs in the axial direction (XX) of the laminated core over the plurality of individual sheets (10) and connects all individual sheets (10) to one another. [3] Laminated core according to one of the preceding claims, characterized bythat the weld seam (4) is produced by means of a non-magnetic additive (40) and the weld seam (4) effects a magnetic separation of areas of the laminated core adjacent to the weld seam. [4] Laminated core according to one of the preceding claims, characterized by that the weld seam (4) is provided on an outer circumference (8) of the laminated core and / or an inner circumference of the laminated core. [5] Laminated core according to one of the preceding claims, characterized by a central recess (5) in which a shaft (6) is arranged. [6] Electrical machine comprising a laminated core according to one of the preceding claims. [7] Method for fixing magnetic elements (3) in magnetic pockets (2) of a laminated core (1) made from a plurality of individual sheets (10), comprising the steps: - loose or with slight pre-compression or with transition fit, positioning of a magnetic element (3) in the magnetic pocket (2) of the laminated core (1) and - Producing a weld seam (4) on a wall region (21) of the magnetic pocket (2) in such a way that the weld seam causes a distortion of the wall region (21) of the magnetic pocket (2) in such a way that the magnetic element (3) is clamped in the magnetic pocket (2), wherein each magnetic pocket (2) has a first and a second weld seam (4), wherein the first weld seam is provided on a first corner region (11) and the second weld seam is provided on a second corner region (12) of the magnetic pocket, so that the two weld seams (4) on each magnetic pocket (2) cause a distortion when the weld seam cools, which clamps the magnetic element (3) between the two wall regions (21, 22) of the magnetic pockets (2). [8] Method according to claim 7, characterized by that exactly two weld seams are produced on one magnetic pocket (2). [9] Method according to claim 7 or 8, characterized by that several weld seams (4) are produced on a sheet stack at the same time. [10] Method according to one of claims 7 to 9, characterized by that the weld seams (4) are provided at corner areas (11, 12) of the magnetic pocket (2). [11] Method according to one of claims 7 to 10, characterized by that the weld seams (4) run in the axial direction (XX) of the laminated core on an outer side of the laminated core. [12] Method according to one of claims 7 to 11, characterized by that the welds are made using a non-magnetic material.

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