Pressure finger for lamination stack

Abstract

The invention relates to a lamination stack (10) for a stator (12) arranged about a central axis AM or a rotor of an electric machine, which rotor is rotatable about the central axis AM, wherein multiple individual laminations (14) assembled to form sub-stacks (16) are provided and each individual lamination (14) has a circumferential offset (18) in relation to the respective adjacent individual lamination (14) in an axial direction of the central axis AM in order to form a helix angle αS of the lamination stack (10), and the sub-stacks (16) are orientated relative to one another to form an axial gap (18) extending in the axial direction, and wherein multiple pressure fingers (20) sit circumferentially between sub-stacks (16). The pressure finger has a radial section (22) and a plug-in pin (24), wherein the radial section (22) and the plug-in pin (24) are set at an angle to one another in the order of the helix angle αS. Clean, flat support of the pressure finger (20) on the respective lamination stack (10) or individual stack (20) is ensured.

Description

[0001] Pressure finger for sheet metal package

[0002] Description

[0003] The invention relates to a laminated core for a stator arranged about a central axis AM or a rotor of an electric machine rotatable about the central axis AM, wherein several individual laminations are provided as sub-packages and each individual lamination has a circumferential offset to form an angle of inclination of the laminated core to the individual lamination adjacent in an axial direction of the central axis AM and the sub-packages are aligned to each other forming an axially extending axial gap and wherein several pressure fingers are inserted circumferentially between sub-packages, which have a radial section extending in a radial direction of the central axis AM and a plug pin directed in the axial direction and inserted in a plug groove formed by the individual laminations.

[0004] An electric machine, such as an electric motor, generator, or transformer, has a laminated core in the stator and / or rotor, composed of individual laminations. Within this core, spacers are used to create axial gaps between the individual laminations. These gaps act as air vents, allowing air to pass through for cooling. The spacers thus serve as dividers between the laminations. During assembly, the spacers' prongs are inserted into precisely fitting slots in the individual laminations. On one axial side of the gap, the spacers are inserted, while on the other side, they simply rest against the surface of the respective lamination stack.

[0005] The interlocking slots result from the fact that the cutouts in the individual sheets align axially to form groove-like recesses. Since the individual sheets exhibit a circumferential offset or rotation angle relative to the sheet adjacent to the central axis AM in an axial direction, forming the angle of inclination of the sheet stack, the interlocking slots are not perpendicular to the respective surface of the individual sheets. Instead, one axis of the interlocking slot is at a certain angle to the sheet surface, deviating from 90°. Due to the tight tolerance with which the pin of each pressure finger engages in the interlocking slot, the pressure fingers do not lie flat or flush against the surface of the respective sheet stack on the axial sides of the axial gap, but rather at a certain angle.Conventionally, the helix angle is achieved primarily by ensuring that the pressure fingers are seated in the slots with a certain amount of play, allowing for limited relative movement. Furthermore, the pressure finger itself is subject to a certain angular deviation during its manufacture due to the stamping process. These effects can then lead to misalignment and plastic deformation of the pressure fingers during the pressing process of the lamination stack. In subsequent operation of the lamination stack—for example, in a stator or rotor of an electric machine—the pressure fingers can loosen because the surface pressure on the plastically deformed area is very high, potentially resulting in further deformation. Therefore, there is a need to improve the seating of the pressure fingers relative to the individual laminations used in the system.

[0006] DE 10 2012 215 982 A1 discloses an electric machine with a laminated core comprising spacers, wherein the spacers have pressure fingers of different thicknesses in the tangential direction. EP 1 414 132 A1 discloses an electric machine in which windings of a stator are inserted into a stator slot via a damping element to reduce vibrations and noise emissions.

[0007] EP 2 835 889 Bl shows an electric machine with a segmented rotor having ring-shaped laminated cores, wherein recesses for the passage of a cooling fluid are formed by means of a tangentially extending asymmetrical web between the laminated cores.

[0008] DE 20 2011 107 009 Ul shows an electric machine with a rotor and a stator in which axial and radial cooling channels are formed by means of curved spacers.

[0009] The object of the invention is to demonstrate measures to improve the seating of the pressure fingers relative to individual sheets of the sheet metal stack.

[0010] The problem is solved by a laminated core for a stator arranged about a central axis AM or a rotor rotatable about the central axis AM, comprising the features of claim 1. Preferred embodiments are specified in the dependent claims and the following description, each of which, individually or in combination, may represent an aspect of the invention. Where a feature is presented in combination with another feature, this serves only to simplify the presentation of the invention and is in no way intended to imply that this feature cannot also constitute a further development of the invention without the other feature.

[0011] One embodiment relates to a laminated core for a stator arranged about a central axis AM or a rotor of an electric machine rotatable about the central axis AM, wherein several individual laminations are provided, assembled into sub-cores, and each individual lamination has a circumferential offset to form a helix angle of the laminated core relative to the individual lamination adjacent in an axial direction of the central axis AM, and the sub-cores are aligned with each other forming an axially extending axial gap, and wherein several pressure fingers are inserted circumferentially between sub-cores, the pressure fingers having a radial section extending in a radial direction of the central axis AM and a plug pin directed in the axial direction and inserted in a plug groove formed by the individual laminations. The plug pin is angled relative to the radial section about an axis described by the radial direction.

[0012] In the laminated core described here, it is possible to compensate for the angle of the slot axis to the plane of the sheet metal surface, which deviates from 90° when the laminated core has a larger helical angle than 90°, by means of a pressure finger angled between the radial section and the locating pin. The angled pressure fingers allow for precise alignment within the axial gap and full contact with the surface of the individual sheets. The angled pressure fingers enable tighter tolerances for the locating slots, as the helical angle of the laminated core does not have to be completely accommodated by the play of the pressure fingers within the slots. This also allows for more precise rotational alignment of the pressure fingers in the sheet metal plane and more consistent axial gap spacing.A clean contact of the pressure finger with the sheet metal surface at an angle of less than 90° can be achieved, and in particular, potential plastic deformation during operation of the sheet metal stack is avoided. This largely prevents the pressure fingers from loosening or detaching. In turn, this offers increased resistance to twisting of the sheet metal stack, as torsional loads caused by misalignment are significantly reduced. A further advantage is that the embossing process only needs to be adapted to also emboss the angle between the radial section and the stud. No further modification of the embossing process is required. However, it is also possible to integrate the angle between the radial section and the stud into a stamping process without any further embossing.In one possible embodiment, the plug pin is angled relative to the radial section by a dimension that corresponds in magnitude to the angle of the helix. This ensures that the angle of the plug groove axis to the plane of the sheet metal surface, which deviates from 90° due to the helix angle, is at least largely compensated for, and that the pressure fingers make clean contact with the respective sheet metal surface.

[0013] In a further preferred embodiment, the angle by which the plug pin is bent relative to the radial section deviates from the helix angle by + / - 0.2°. To advantageously achieve the adjustment of the pressure fingers to the helix angle of the lamination stack via the angling of the pressure fingers, the plug pins are inserted into the slot with a clearance that allows a defined circumferential movement of the pressure finger relative to the respective individual lamination. This clearance is expediently designed such that the resulting mobility allows the pressure fingers to tilt by up to 0.05°. The clearance is significantly reduced compared to the conventional design, so that the pressure fingers can now only rotate to a small extent in the plane of the lamination around the slots, thus preventing collisions with adjacent pressure fingers.

[0014] In a preferred specific embodiment of the pressure finger, it can be provided that the plug pin is angled relative to the radial section by a dimension between 1.8° and 2.2°, preferably between 1.9° and 2.1°.

[0015] In a further preferred embodiment, the plug pin has an embossed surface structure. This surface structure can extend into the radial section. In a specific embodiment, the surface structure can have at least one ridge embossed on one axial side and a rib projecting on the other. The problem is also solved by a stator for an electric machine, wherein the stator has a laminated core that can be designed and further developed as described above.

[0016] The problem is also solved by a rotor for an electric machine, wherein the rotor has a laminated core that can be designed and further developed as above.

[0017] Furthermore, the task is solved by an electric machine comprising a stator, which can be designed and further developed as above, and / or a rotor, which can be designed and further developed as above.

[0018] Furthermore, the task is solved by a generator for an industrial wind turbine with an electric machine, which can be designed and further developed as above, for generating electrical energy for a wind power grid.

[0019] Furthermore, the task is solved by a wind power plant for generating electrical energy for a wind power grid with a generator, which can be designed and further developed as above, for converting mechanical energy provided from a wind rotor into electrical energy.

[0020] The wind turbine is specifically designed as an industrial wind turbine. Industrial wind turbines are primarily designed for generating energy from wind power, whereby the electrical energy generated from wind power can be fed into a public power grid to supply energy consumers with regeneratively generated energy. A wind turbine gearbox designed for an industrial wind turbine is specifically designed for a power output exceeding 1.0 MW, preferably exceeding 5.0 MW, and most preferably exceeding 7.5 MW, and is correspondingly robust and large-volume. The invention is explained below by way of example with reference to the accompanying drawings and preferred embodiments, whereby the features shown below can represent an aspect of the invention, either individually or in combination. The drawings show:

[0021] Figs. 1 and 2: a sheet metal package in perspective view and in top view;

[0022] Fig. 3: a pressure finger for a sheet metal stack according to Fig. 1, 2 as a detail;

[0023] Fig. 4: a representation of two adjacent sub-packages of a sheet metal package with an inserted pressure finger;

[0024] Fig. 5: further illustration of two adjacent sub-packages of a sheet metal package with an inserted pressure finger;

[0025] Fig. 6: a possible embodiment of a pressure finger according to the invention;

[0026] Fig. 7: a representation of two adjacent sub-packages of a sheet metal stack with an embedded pressure finger according to Fig. 6 and

[0027] Fig. 8: a partial top view of a single sheet with exemplary inserted pressure fingers.

[0028] Figures 1 and 2 show a laminated core 10 that, when arranged in a housing, can function as the stator 12 of an electric machine. Neither the housing nor the electric machine is shown here. Figure 1 shows a perspective view and Figure 2 shows a top view of the laminated core 10.

[0029] The sheet metal stack 10 is arranged centrally around a central axis AM and is composed of several individual sheets 14 to form sub-stacks 16. Adjacent sub-stacks 16 form an axially extending gap 18 between them. Several pressure fingers 20 are seated in the axial gaps 18. The multiple pressure fingers 20 are arranged uniformly around the circumference of the axial gaps 18, and each pressure finger 20 is oriented radially. The pressure fingers 20 are described in detail below with reference to Figures 3 and 4.

[0030] The individual sheets 14 are arranged circumferentially relative to one another such that a helix angle as results for the laminated core 10. The helix angle as is formed by each individual sheet 14 having a circumferential offset, i.e., a twist angle or helix angle, relative to the individual sheet 14 adjacent to it in an axial direction of the central axis AM. The magnitude of this offset is always the same, so that it accumulates over the axial length of the laminated core 10 and results in a twist of the laminated core 10.

[0031] The helix angle as is shown in Figure 2. Reference numeral 34 denotes a line parallel to the central axis AM, which would result from joining identical circumferential points of all individual sheets 14 if they were aligned without any axial offset. In contrast, reference numeral 36 denotes the line that would result from joining identical circumferential points of all individual sheets 14 if they had a continuous circumferential offset from each other. The angle between the two lines 34 and 36 is the helix angle as of the sheet stack 10.

[0032] Figure 3 shows a push finger 20 in detail. The push finger 20 forms a radial section 22 and a plug pin 24 projecting orthogonally to it. When the push finger 20 is installed, the radial section 22 is oriented radially with respect to the central axis AM, whereas the plug pin 24 is oriented axially with respect to the central axis AM. The plug pin 24 has an embossed surface structure 28, which in this case extends into the radial section 22. The surface structure 28 has, for example, a sequence of beads 30 and ridges 32, wherein in this case the surface structure 28 rises as a ridge 32 on one side of the plug pin 24 and this ridge 32 is embossed as a bead 30 on the other side of the plug pin 24.Figure 4 shows a representation of two adjacent sub-assemblies 16 of the sheet metal stack, an axial gap 18 between the sub-assemblies 16, and a pressure finger 20 seated in the axial gap 18. The representation in Figure 4 shows a tangential section through the sheet metal stack 10 and through the pin 24 of the pressure finger 20, so that a radial direction points into the plane of the drawing. For clarity, a conventional pressure finger 20 is also shown in Figure 4. The radial section 22 of the pressure finger 20 is positioned between the sub-assemblies 16 in the axial gap 18 and rests against the sub-assemblies 16 or the corresponding individual sheet metal 14. The sub-assembly 16 shown below forms a slot 26 for receiving the pin 24 of the pressure finger 20. As previously described, the individual sheets 14 are arranged circumferentially relative to each other in such a way that the angle of inclination as is obtained.The arrangement results in the angle of inclination as also being reflected in the orientation of the slot 26, such that one axis of the slot 26 is at an angle of inclination as to the surface of the individual sheets 14. Consequently, the pressure finger 20 is also seated in the slot 26 at an angle of inclination as via the plug pin 24. The pressure finger 20 is therefore tilted at a certain angle in the circumferential direction. This, in turn, leads to the radial section 22 of the pressure finger 20 also having an angled position relative to the corresponding individual sheets 14 of the sub-assemblies 16 and not lying flat. As already explained, this applies to a conventional pressure finger 20 and is shown in further detail in Figure 5.

[0033] Figure 6 shows a possible embodiment of a pressure finger 20 according to the invention in a single view. Figure 6 shows the same view as Figures 4 and 5 with respect to the directions. The pressure finger 30 is fundamentally unchanged in its structural design; however, the plug pin 24 is angled relative to the radial section 22 about an axis 38 defined by the radial direction. This results in the radial plane 40 of the radial section 22 and the radial plane 42 of the plug pin 24 intersecting at the axis 38 and being at an angle to each other, which can be the angle of inclination aS. Structurally, it may be sufficient if the plug pin 24 is angled relative to the radial section 22 by a dimension that is on the order of magnitude of the angle of inclination aS.The dimension by which the plug pin 24 is angled relative to the radial section 22 can deviate by + / - 0.2° from the dimension of the helix angle as.

[0034] Figure 7 shows a representation in which the pressure finger 20, as described in Figure 6, is seated in the axial gap 18 between two adjacent sub-packs 16 of the sheet metal stack 10. It can be seen that the radial section 22 of the pressure finger 20 now lies flat against the corresponding individual sheets 14 of the sub-packs 16 and is no longer angled, as described for a conventional pressure finger in Figure 5. This design of the pressure finger 20 ensures a clean, flat contact with the respective sheet metal stack 10 or individual stack 20. Tilting of the pressure finger 20 is effectively prevented or at least reduced to a minimum. The flat contact of the pressure finger 20 with the sheet metal surface prevents plastic deformation of the contact surfaces of the pressure finger 20 during assembly and operation, thus preventing the pressure finger 20 from loosening.In addition, torsional restoring forces are minimized, so that further twisting of the sheet metal stack 10 beyond the helix angle as is prevented during operation.

[0035] Figure 8 shows a partial top view of a single sheet 14 with two inserted pressure fingers 20. Of the pressure fingers 20, the one shown on the left is fully radially aligned, while the one shown on the right is rotated in the axial plane by a certain angle in the insertion groove 26. The insertion clearance, with which the insertion pin 24 of the pressure finger 20 sits in the insertion groove 26, is dimensioned such that the possible rotation of the pressure finger 20 – due to the insertion clearance – prevents any collision with an adjacent pressure finger. Reference numeral list

[0036] 10 sheet metal packages

[0037] 12 Stator

[0038] 14 individual sheets

[0039] 16 sub-packages

[0040] 18 Axial gap

[0041] 20 pressure receivers

[0042] 22 Radial section

[0043] 24 plug pins

[0044] 26 slot

[0045] 28 Surface structure

[0046] 30 groove

[0047] 32 Bridge

[0048] Line 34

[0049] Line 36

[0050] 38 axle

[0051] 40 Radial plane

[0052] 42 Radial plane

Claims

P a t e n t a n s p r ü c h e 1. Laminated core (10) for a stator (12) arranged about a central axis (AM) or a rotor of an electric machine rotatable about the central axis (AM), wherein several individual laminations (14) are provided, assembled into sub-cores (16), and each individual lamination (14) has a circumferential offset to form an angle of inclination (as) of the laminated core (10) to the individual lamination (14) adjacent in an axial direction of the central axis (AM), and the sub-cores (16) are aligned to each other forming an axially extending axial gap (18), and wherein several pressure fingers (20) are inserted circumferentially between sub-cores (16), the pressure fingers having a radial section (22) extending in a radial direction of the central axis (AM) and a plug pin (24) directed in the axial direction and inserted in a plug groove (26) formed by the individual laminations (14), characterized in thatthat the plug pin (24) is angled relative to the radial section (22) about an axis described by the radial direction.

2. Sheet metal package (10) according to claim 1, characterized in that the plug pin (24) is angled relative to the radial section (22) by a dimension which corresponds in magnitude to the dimension of the helix angle (as).

3. Sheet metal package (10) according to claim 1 or 2, characterized in that the dimension by which the plug pin (24) is angled relative to the radial section (22) deviates by + / - 0.2° from the dimension of the helix angle (as).

4. Sheet metal stack (10) according to one of claims 1 to 3, characterized in that the plug pin (24) is angled relative to the radial section (22) by a degree between 1.8° and 2.2°, preferably between 1.9° and 2.1°.

5. Sheet metal package (10) according to one of claims 1 to 4, characterized in that the plug pin (24) has an embossed surface structure (28).

6. Sheet metal package (10) according to claim 5, characterized in that the surface structure (28) extends into the radial section (22).

7. Sheet metal package (10) according to claim 5 or 6, characterized in that the surface structure (28) has at least one groove (30) embossed on one axial side as a web (32) projecting on the other side.

8. Sheet metal package (10) according to one of claims 1 to 7, characterized in that the plug pins (24) are inserted into the plug groove (26) with an insertion clearance that allows a defined circumferential movement of the pressure finger (20) relative to the respective individual sheet metal (14).

9. Stator for an electric machine, wherein the stator comprises a laminated core (10) according to any one of claims 1 to 8.

10. Rotor for an electric machine, wherein the rotor has a laminated core (10) according to any one of claims 1 to 8.

11. Electric machine comprising a stator (12) according to claim 9 and / or a rotor according to claim 10.

12. Generator for an industrial wind turbine with an electric machine according to claim 11 for generating electrical energy for a wind power grid.

13. Wind power plant for generating electrical energy for a wind power grid with a generator according to claim 12 for converting mechanical energy provided from a wind rotor into electrical energy.

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