Winding head support of a rotor for an electrical machine

Description

[0001] The invention relates to a rotor for an electrical machine, in particular for a rotor-fed slip-ring rotor machine, such as those used for speed-controlled hydroelectric motor generators for pumped storage power plants.

[0002] DE 10 2010 020 415 A1 discloses a rotor suitable for a variable-speed hydroelectric motor generator. The rotor disclosed in this document comprises winding elements arranged in two layers in axially extending slots of a rotor body, a winding head arranged axially next to the rotor body, and a winding head support, wherein the winding head is connected to the winding head support via tension bolts. The tension bolts engage support bodies at their radially outer ends, which in turn rest on the winding elements of the outer layer in the region of the winding head. Each winding element is thus held in the region of a winding head by two tension bolts, one support body per tension bolt. For each winding head, the support bodies and the associated tension bolts are arranged in two rings, each ring being arranged in a plane perpendicular to the rotor axis.The planes are located in the areas where the winding elements have an axially oriented course.

[0003] DE 10 2018 124 011 B3 discloses a comparable rotor. The support bodies and the associated tension bolts are arranged in three rings per winding head, with each ring positioned in a plane perpendicular to the rotor axis. These planes lie in the areas where the winding elements have an axially oriented course. Therefore, the winding elements in the area of ​​the winding head have a complex bending pattern, requiring a total of four curvature areas per winding element per winding head.

[0004] DE 195 13 457 A1 discloses a comparable rotor. The support bodies and the associated tension bolts are arranged in a plurality of rings per winding head, with each ring positioned in a plane perpendicular to the rotor axis.

[0005] One of the planes lies in an area where the winding elements have an axially oriented course. The other planes lie in an area where the winding elements run at an angle to the axial direction.

[0006] The documents DE 19535700 A1, US 55606212 A, EP 2557663 A2 and CN 104218715 A disclose similar rotor winding heads, wherein the distances between two directly adjacent winding elements are the same and the fastening bolts are screwed in an alternative manner in or on the rotor body.

[0007] The object of the invention is to provide a rotor which has an alternative structure and is characterized by increased strength and easier assembly.

[0008] The object is achieved according to the invention by an embodiment according to the independent claim. Further advantageous embodiments of the present invention can be found in the subclaims.

[0009] The invention is explained below with reference to the figures. The figures show in detail: Fig.1 Rotor according to the prior art Fig.2 Rotors according to the invention in two embodiments Fig.3 Rotor according to the invention in a further embodiment Fig.4 Rotor according to the invention in a further embodiment Fig.5 Rotor according to the invention in a further embodiment Fig.6 Embodiments of the holding elements according to the invention Fig.7 Rotor according to the invention with representation of the holding elements

[0010] Figure 1 shows a rotor according to DE 195 13 457 A1. Figure 1is a simplified view of the winding head of the rotor. The rotor is designated 1. The rotor 1 comprises a rotor body, which is designated 2. The rotor 1 comprises winding elements which are arranged in two layers in axially extending grooves of the rotor body 2. The winding head comprises two regions, wherein in a first region the winding elements run in the axial direction, and wherein in a second region the winding elements run at an angle to the axial direction. One of the winding elements of the outer layer is designated 3. The Figure 1The dashed circles indicate the space available at various locations for the passage of tension bolts. It is clearly visible that this space is significantly larger in the area where the winding elements run axially than in the area where the winding elements run at an angle to the axial direction. The inventors have recognized that the use of bolts with a small diameter can impair the strength of the rotor 1 in the area of ​​the winding head.

[0011] Figure 2 shows a rotor according to the invention in two alternative embodiments in the same representation as Figure 1. In the rotors shown, the winding elements have different distances A 1 and A 2 from the two adjacent winding elements of the same layer in the area in which they run at an angle to the axial direction. This means that each winding element has, in the area in which it runs at an angle to the axial direction, a distance A 1 from a first directly adjacent winding element of the same layer, and a distance A 2 from a second directly adjacent winding element of the same layer, where A 2 is greater than A 1. It is clear that each winding element has exactly two directly adjacent winding elements in the same layer. The distances are measured in a direction perpendicular to the surface of the winding elements located between them (see Figure 2 ). As can be seen from Figure 2As can be seen, in the area where the winding elements run at an angle to the axial direction, gaps are created which are suitable for accommodating tension bolts with a larger diameter.

[0012] The two in Figure 2 The embodiments shown achieve this in different ways. In the case of the one shown in the upper part of Figure 2 In the embodiment shown, the winding elements have different lengths L 1 and L 2, by which they each protrude from the rotor body in the axial direction before extending at an angle to the axial direction. In each layer, the winding elements alternate with lengths L 1 and L 2 . This allows one to distinguish between two types or groups of winding elements with respect to the respective winding head. It is clear that the two groups each comprise half of the winding elements. Figure 2 One winding element of each of the two types or groups is designated 3.1 and 3.2.

[0013] In the lower part of Figure 2 In the embodiment shown, the winding elements have different radii of curvature R 1 and R 2, at which the winding elements bend from the axial direction to the direction at an angle to the axis after exiting the rotor body. In this case, too, two types or groups of winding elements can be distinguished with respect to the respective winding head.

[0014] The further embodiments are described below only for the variant according to the upper part of Figure 2 However, they can easily be used analogously for the variant according to the lower part of Figure 2 be implemented.

[0015] Figure 3 shows an exemplary embodiment of the invention with regard to a first possibility of how the winding elements can continue in the opposite winding head. In the upper part of the Figure 3the winding head is as in Figure 2 The lower part of Figure 3shows the other winding overhang, whereby for the sake of clarity only four of the winding elements shown above are shown below. In the embodiment shown, each winding element in both winding overhangs protrudes axially from the rotor body by the same length. This means that a winding element 3.1 that protrudes axially from the rotor body by the length L 1 in one winding overhang, also protrudes by the length L 1 in the other winding overhang. And a winding element 3.2 that protrudes axially from the rotor body by the length L 2 in one winding overhang, also protrudes by the length L 2 in the other winding overhang. This means that the two types of winding elements 3.1 and 3.2 are not only distinguishable from one another with regard to a winding overhang, but are also each designed differently. For production purposes, two batches of winding elements with different designs must therefore be manufactured.

[0016] Figure 4 shows an exemplary embodiment of the invention with respect to a second possibility of how the winding elements can continue in the opposite winding head. The representation is analogous to Figure 3 . In the illustrated embodiment, each winding element in both winding overhangs projects axially out of the rotor body by different lengths. This means that a winding element 3.1, which projects axially out of the rotor body by the length L 1 in one winding overhang, projects by the length L 2 in the other winding overhang. And a winding element 3.2, which projects axially out of the rotor body by the length L 2 in one winding overhang, projects by the length L 1 in the other winding overhang. This means that the two types of winding elements 3.1 and 3.2 can only be distinguished from one another with regard to one winding overhang when viewed separately. Absolutely, i.e. before installation in the rotor, they do not differ from one another, since, as can be seen from Figure 4As can be seen, each winding element 3.1 transitions into a winding element 3.2 by rotating it 180° perpendicular to the plane of the drawing. This means that the winding elements differ only in their installation position. From a manufacturing perspective, a single batch of winding elements with an identical design can be produced.

[0017] It should be noted that the winding elements of the individual layers generally differ slightly from one another in terms of design, although this is not apparent in the figures due to the way they are presented. This means that, strictly speaking, what was said in the preceding sections only applies to the winding elements of one and the same layer.

[0018] In the following, further advantageous embodiments of the present invention are described with regard to the design of the holding elements with which the winding elements are held in the region of the winding head.

[0019] Figure 5shows a rotor according to the invention in a schematic representation. Figure 5 Only a section of the rotor is shown. The rotor is designated 1. The rotor 1 comprises a rotor body, designated 2, and a plurality of winding elements arranged in axially extending grooves of the rotor body 2. The winding elements form two layers in the radial direction. The winding elements protrude in the axial direction beyond the rotor body 2 and thus form a so-called winding head, which is arranged axially next to the rotor body 2. In each case, a winding element of one layer is connected at its end to the end of a winding element of the other layer. Figure 5 A winding element is designated 3.

[0020] To prevent the winding elements 3 from being bent radially outwards due to the enormous centrifugal forces that act during operation of the electrical machine, they must be held in position in the area of ​​the winding head. For this purpose, the winding head comprises a winding head carrier, which Figure 5 designated 4 and a plurality of holding elements, one of which is Figure 5 is designated 5. Each holding element 5 comprises a tension bolt and a support body. Figure 5One of the tension bolts is designated 6, and one of the support bodies is designated 7. The support bodies 7 are arranged radially outside the winding elements 3. The tension bolts 6 each penetrate the corresponding support body 7 and are screwed into the winding head support 4 with a thread. The winding head support 4 can also consist of several parts, so that the tension bolts 6 are screwed, for example, into profile strips arranged in corresponding grooves in the winding head support body. The profile strips and winding head support bodies are then parts of the winding head support 4.

[0021] It is advantageous if the holding elements 5 comprise a stop surface 8 which is designed such that it can come into contact with the winding head carrier 4 when the tension bolts 6 are screwed in, in order to set the radial length by which the tension bolts 6 protrude from the winding head carrier 4 to a predefined dimension. The predefined dimension is dimensioned such that the support bodies 7 are not pressed against the winding elements 3 when the rotor 1 is at rest. This means that when the rotor 1 is at rest, the support bodies 7 ideally just touch the winding elements 3 when the tension bolts 6 are screwed into the winding head carrier 4 far enough that the stop surface 8 comes into contact with the winding head carrier 4. Alternatively, a (small) gap can also be present between the support body 7 and the winding elements 3 in the aforementioned position.

[0022] The feature "that the support bodies 7 are not pressed against the winding elements 3 when the rotor 1 is at rest" is to be understood as meaning that the compressive force transmitted to the winding elements 3 by the tightened tie bolts 6 when the rotor 1 is at rest is negligibly small compared to the tensile force acting in the tightened tie bolts 6. This is the case when the compressive force transmitted to the winding elements 3 by a tightened tie bolt 6 is less than 15% of the tensile force acting in the respective tie bolt 6.

[0023] The stop surfaces 8 thus formed, on the one hand, prevent the winding elements 3 from being deformed when the tension bolts 6 are screwed in. On the other hand, they ensure that the screw connection between the tension bolts 6 and the winding head support 4 is clamped, so that the screw connection cannot come loose during operation of the rotor 1. A high preload of the tension bolts 6 also ensures that the additional force acting on the tension bolts 6 during operation is small compared to the preload force, thereby extending the service life of the tension bolts 6.

[0024] Optionally, the holding elements 5 may comprise an elastic element which is arranged in the space between the associated support body 7 and the winding elements 3 held by the respective holding element 5. In Figure 5Such an elastic element is designated 9. The elastic elements 9 are designed such that they are slightly compressed in the radial direction when the tension bolts 6 are screwed in until the associated stop surfaces 8 come into contact with the winding head carrier 4. The modulus of elasticity of the elastic elements 9 is to be selected such that the aforementioned compression of the elastic elements 9 does not lead to any significant deformation of the winding elements 3. In other words: the elastic elements 9 are designed such that no significant deformation of the winding elements 3 can occur when the tension bolts 6 are screwed in until the associated stop surfaces 8 come into contact with the winding head carrier 4.

[0025] Figure 6shows various embodiments of holding elements 5 according to the invention. In the embodiment shown above, the stop surface 8 is formed by a shoulder of the tension bolt 6. In the second embodiment from above, the holding element 5 comprises a sleeve, which is designated 10. The tension bolt 6 penetrates the sleeve 10, and the stop surface 8 is formed by the end of the sleeve 10, which is oriented towards the winding head carrier 4. In the third embodiment from above, the support body 7 comprises a sleeve-like protuberance, wherein the stop surface 8 is arranged at the end of the protuberance. In the latter embodiment, the support bodies 7 are only partially arranged radially outside the winding elements 3, since the sleeve-shaped protuberance thereof protrudes between the winding elements 3. This protuberance can also serve to support the winding elements held by the respective holding element in the lateral direction.A further embodiment results from a combination of the last two embodiments, in which a shorter sleeve 10 is combined with a correspondingly shorter protrusion of the support body 7. The stop surface 8 is formed by the end of the sleeve 10. In the lower in . Figure 6 In the embodiment shown, the tension bolt 6 comprises a shoulder, designated 11, which presses against a sleeve 10 when screwed in. The stop surface 8 is also formed here by the end of the sleeve 10. This embodiment has the advantage that the support body 7 is largely relieved of stress. Further embodiments result from the use of several sleeves 10 per tension bolt 6, wherein the sleeves 10 are pressed against one another when the associated tension bolt 6 is screwed in.

[0026] As from Figure 6As can be seen, the holding elements 5, which comprise a stop surface 8, have a larger diameter in the section with which they penetrate the winding head. Because a winding head according to the invention has larger passages compared to the known winding heads, even in the area in which the winding elements run at an angle to the axial direction, holding elements 5 according to Figure 6 can also be used in this area. Alternatively, conventional retaining elements without stop surface 8 can be used. The space gained can then be used for a larger diameter of the tension bolts 6.

[0027] In Figure 7 is a rotor according to the invention according to the embodiment of Figure 2upper part, showing the position of the support bodies 7 in the two different regions of the winding head. At least some of the tension bolts penetrate the winding head in the radial direction in the region where the winding elements extend at an angle to the axial direction. List of reference symbols

[0028] 1 Rotor 2 Rotor body 3 Winding element 3.1 Winding element 3.2 Winding element 4 Winding head support 5 Holding elements 6 Tension bolt 7 Support body 8 Stop surface 9 Elastic element 10 Sleeve 11 Shoulder

Claims

1. Rotor (1) for an electrical machine with a rotor body (2), a plurality of winding elements (3, 3.1, 3.2) and a winding head arranged axially next to the rotor body (2), wherein the winding elements (3, 3.1, 3.2) are arranged in two layers in axially extending grooves of the rotor body (2), and wherein the winding head comprises two regions, wherein in a first region the winding elements (3, 3.1, 3.2) extend in the axial direction, and wherein in a second region the winding elements (3, 3.1, 3.2) extend at an angle to the axial direction, and wherein the winding head comprises a winding head (3, 3.1, 3.2) extending in the axial direction.2) extend in an axial direction, and wherein in a second region the winding elements (3, 3.1, 3.2) extend at an angle to the axial direction, and wherein the winding head comprises a winding head carrier (4) and a plurality of retaining elements (5), and wherein each retaining element (5) comprises a respective tension bolt (6) and a supporting body (7), and wherein the supporting bodies (7) are arranged at least partially in the radial direction outside the winding elements (3, 3.1, 3.2), and wherein the tension bolts (6) each penetrate the associated supporting body (7) and are screwed into the winding head carrier (4) with a thread, and wherein at least some of the tension bolts (6) penetrate the winding head in the radial direction in the second region, characterised in that each winding element (3, 3.1, 3.2) in the second region, in which it extends at an angle to the axial direction, has a distance A1 from a first directly adjacent winding element (3, 3.1, 3.2) of the same position, and has a distance A2 from a second directly adjacent winding element (3, 3.1, 3.2) of the same position, A2 being greater than A12. Rotor (1) according to claim 1, wherein half of the winding elements (3.1) form a first group, and wherein the other half of the winding elements (3.2) form a second group, and wherein the winding elements (3.1) of the first group protrude by a length L1 from the rotor body (2) in the axial direction before they extend at an angle to the axial direction, and wherein the winding elements (3.2) of the second group protrude by a length L2 from the rotor body (2) in the axial direction before they extend at an angle to the axial direction, and wherein L1 is greater than L(2).

3. Rotor (1) according to claim 1, wherein half of the winding elements (3.1) form a first group, and wherein the other half of the winding elements (3.2) form a second group, and wherein the winding elements (3.1) of the first group have a radius of curvature R1 below which the same bend from the axial direction in the direction extending at an angle to the axis after emerging from the rotor body (2), and wherein the winding elements (3.2) of the second group have a radius of curvature R(2)below which the same bend from the axial direction in the direction extending at an angle to the axis after emerging from the rotor body (2).2) of the second group have a radius of curvature R2, below which they bend from the axial direction in the direction extending at an angle to the axis after emerging from the rotor body (2), and wherein R1 is greater than R24. Rotor (1) according to claim 2 or 3, wherein the winding elements (3.1) of the first group and the winding elements (3.2) of the second group differ in terms of their design with respect to the layers.

5. Rotor (1) according to claim 2 or 3, wherein the winding elements (3.1) of the first group and the winding elements (3.2) of the second group do not differ with regard to the design with respect to the layers.

6. Rotor (1) according to one of claims 1 to 5, wherein the retaining elements (5) each comprise a stop surface (8) which is designed in such a way that it can come to bear against the winding head carrier (4) when the tension bolts (7) are screwed in, in order to set the radial length with which the tension bolts (6) protrude from the winding head carrier (4) to a predefined dimension, wherein the predefined dimension is dimensioned in such a way that the supporting bodies (7) are thereby adjusted to a predefined dimension, with which the tension bolts (6) protrude from the winding head carrier (4) to a predefined dimension, the predefined dimension being dimensioned such that the supporting bodies (7) are not pressed against the winding elements (3) when the rotor (1) is at rest.

7. Rotor (1) according to claim 6, and wherein a retaining element (5) comprises an elastic element (9) which is arranged in an intermediate space between the associated supporting body (7) and the winding elements (3) held by the retaining element.

8. Rotor (1) according to claim 6 or 7, and wherein a stop surface (8) is formed by a shoulder of the tension bolt (6).

9. Rotor (1) according to claim 6 or 7, and wherein a retaining element (5) comprises a sleeve (10), and wherein the tension bolt (6) penetrates the sleeve (10), and wherein the stop surface (8) is formed by the end of the sleeve (10), which is orientated towards the winding head support (4).

10. Rotor (1) according to claim 9, wherein the tension bolt (6) comprises a shoulder (11) which can be pressed against the sleeve (10) when the tension bolt (6) is tightened.

11. Rotor (1) according to claim 6 or 7, and wherein a supporting body (7) comprises a sleeve-like protuberance, and wherein the stop surface (8) is arranged at the end of the protuberance.