Rotor for an electric machine

Abstract

The invention relates to a rotor for an electric machine having a laminated core (1) with slots in which bottom bars (3) and top bars (4) are arranged, which bars extend in an axial direction (5) beyond the laminated core (1) to form a winding overhang, wherein in each case a bottom bar (3) of a slot is connected to a top bar (4) of another slot in the winding overhang and, in a plan view, bottom bars (3) and top bars (4) cross axially outside the laminated core (1) at crossing points (8) and gaps (9) are left between the crossing points (8), wherein a support device is provided which has a retaining element (10) arranged radially inside the winding overhang and at least one U-shaped clip (11) having two legs (12) and a connecting piece (13), the U-shaped clip (11) being connected to both the retaining element (10) and to a top bar (4) in order to radially support the top bar (4) by means of the retaining element (10). In order to also guarantee robust stabilisation of the winding overhang if there is only a small distance between the gaps (9), according to the invention the legs (12) protrude through two gaps (9) that are adjacent to different top bars (4).

Description

[0001] Rotor for an electric machine

[0002] The invention relates to a rotor for an electrical machine, comprising a laminated core with slots in which lower bars and upper bars are arranged, which extend in the axial direction beyond the laminated core to form a winding head, wherein a lower bar of a slot is connected to a upper bar of another slot in the winding head and lower bars and upper bars cross axially outside the laminated core in a plan view at intersection points and gaps remain between the intersection points, wherein a support device is provided which has a retaining body arranged radially inside the winding head and at least one bracket with two legs and a web, wherein the bracket is connected both to the retaining body and to an upper bar in order to radially support the upper bar by means of the retaining body.

[0003] Rotors of the type mentioned above are known from the state of the art and are used, for example, in asynchronous machines in pumped storage power plants, whereby the asynchronous machines are used both as motors and as generators.

[0004] During operation, centrifugal forces act on the rotor, and in particular on the upper and lower bars, due to the rotor's rotation about a rotor axis. The upper and lower bars are typically supported against these centrifugal forces by slotted wedges in the area of ​​the laminated core. Outside the laminated core, in the winding head, this is not possible, which is why a support device has become known, particularly from document US 5,606,212 A, which has a bracket that, on the one hand, is mounted on a rotating annular disk radially within the winding head and, on the other hand, encompasses an upper bar and a lower bar in order to support this upper bar and the lower bar against the centrifugal forces acting during operation. The legs of this bracket are guided through two adjacent gaps in the rotor laminated core, so that the bracket projects from an interior of the rotor winding head to a radial exterior of the rotor winding head.Depending on the specific requirements of an electrical machine, the number of pole pairs, the diameter and length of the rotor winding head, as well as the dimensions of the upper and lower bars and the angles at which the upper bars are positioned relative to the lower bars in the winding head area, can vary. It has been shown that, with the design proposed in document US 5,606,212, some rotors experience unacceptably high mechanical loads on the retaining body, the brackets, and / or the lower bars. Particularly in rotors with gaps in the winding head located close together, the design known from document US 5,606,212 results in particularly narrow and therefore highly stressed annular discs, in which deviations caused by manufacturing tolerances alone could lead to permissible mechanical limits being exceeded.

[0005] This is where the invention comes in. The object of the invention is to provide a rotor of the type mentioned above, in which the winding head can be robustly stabilized even when the gaps in the winding head are particularly close together.

[0006] This object is achieved according to the invention by a rotor of the type mentioned at the outset, in which the legs protrude through two gaps which are adjacent to different upper bars.

[0007] The inventors recognized that, with a corresponding design, a retaining body, which is usually designed as a circumferential ring, can be used with a larger cross-section, thus reducing mechanical stress. Thus, in prior art devices, the arms of the stirrups always extend between directly adjacent gaps, which thus border the same top bar, so that a stirrup always encompasses only one top bar.

[0008] In the rotor design according to the invention, the legs thus protrude through two gaps, which are usually spaced from each other by at least one further gap, and the bracket thus usually engages around at least two upper bars. This achieves a greater distance between the legs, which usually engage around the retaining body within the winding overhang and are positively connected to it in the radial direction. The legs of the brackets usually extend exclusively in the radial direction. The web, which preferably connects the brackets radially on the outside of the rotor winding overhang, usually extends approximately parallel to an axial direction or parallel to the rotor axis. Accordingly, an axial extension of the retaining body or of a retaining ring usually corresponds essentially to an axial extension of the web.

[0009] The terms axial direction, radial direction and circumferential direction are to be understood here in the sense of a cylindrical coordinate system, whereby the axial direction coincides with a rotor axis around which the rotor is arranged to rotate in a stator during normal operation, or is parallel to this rotor axis.

[0010] Crossing points are defined here as points where a top bar and a bottom bar intersect in the area of ​​the winding head in a plan view or when viewed along the radial direction, with the top bar being arranged at a greater radial distance from the rotor axis than the bottom bar. Gaps are defined here as positions where, when viewed in the corresponding direction, neither a bottom bar nor a top bar is arranged, allowing an unhindered passage of a stirrup from the inside of the rotor winding head to the outside of the rotor winding head along the radial direction.

[0011] With appropriate design, the web usually spans at least two intersection points, so that at least two upper bars and two lower bars are kinematically coupled or positively and / or non-positively connected to the support device in the radial direction by a stirrup.

[0012] By increasing the cross-section of the retaining body accordingly, the inventive design can also be used in rotors in which gaps in the rotor winding head are very close to one another, for example because the upper and lower bars are very narrow and / or the upper and lower bars intersect at an angle of almost 90°. This is especially true since the length of the web and thus the axial extent of the retaining body is not defined by the distance between two adjacent gaps, but rather the axial extent of the retaining body can be a multiple of the distance between two adjacent gaps. Furthermore, the surface pressure of the upper and lower bars is reduced.

[0013] Furthermore, a corresponding rotor can be manufactured with a reduced number of brackets, especially since a bracket can encompass and stabilize several upper and lower bars when designed accordingly.

[0014] The retaining body preferably has an axial extension that corresponds to a multiple, in particular twice, of the distance between two gaps in the rotor winding head, which gaps are located at the same circumferential position along a circumferential direction, i.e., are only axially spaced from each other. With a correspondingly large dimension of the retaining body, deviations caused by manufacturing tolerances also have a smaller impact on mechanical stresses in the retaining body, thus ensuring ease of manufacture.

[0015] In principle, the bracket can be installed in any way to connect the retaining body to the upper bar, so that the winding head is supported by the bracket on the retaining body in the corresponding area and thus radially stabilized. The web could therefore also be arranged radially inward in the rotor winding head and connected to the retaining body there.

[0016] Preferably, however, the web is arranged radially outside the top bars and connected to at least two top bars. This achieves a simple yet robust structure in the area between the rotor winding head and the stator winding head.

[0017] The bridge can of course also encompass more than two upper bars, for example three or four upper bars.

[0018] Furthermore, the bracket can in principle be connected to the retaining body in any way, for example screwed into the retaining body or the like.

[0019] However, it is preferably provided that the retaining body is annular, with the legs extending up to an inner diameter of the retaining body, in particular to reduce pressure peaks. A radial force transmitted via the bracket into the interior of the winding head is then preferably applied to the retaining body via the inner diameter of the retaining body or an inner cylindrical surface.

[0020] Preferably, a locking element detachably connected to the legs is provided. This locking element allows the bracket to be fixed to the retaining body and the winding head.

[0021] Typically, the retaining body is connected to the bracket via the closure member. The bracket preferably rests radially on the inside of the retaining body, so that centrifugal forces transmitted from the web to the legs, which act on the rotor winding head and are absorbed by the bracket, are transferred via the closure member to an inner diameter of the preferably annular retaining body, usually via surface contact to prevent pressure peaks.

[0022] Thus, a radial force is usually transferred from the upper bars to the web, from the web to the legs, from the legs to the closure member and finally from the closure member to the retaining body, usually at an inner diameter of the retaining body.

[0023] It has proven effective for the closure element to have radial through-holes through which the legs protrude. Securing elements, particularly nuts, are provided downstream of the closure element to hold the closure element on the legs. This ensures simple assembly. A predefined tightening torque of the nuts can be used to introduce a defined preload into the legs, allowing the rotor winding head to be pressed against the retaining body with a predefined force.

[0024] In order to compensate for the effects of settling and / or creep in the area of ​​the yoke, spring elements, in particular disc springs or helical disc springs, are preferably arranged between the securing elements and the closure member. These spring elements are preferably preloaded with a predefined preload force. Settling effects that occur during long-term operation can thus be easily compensated, so that a predefined preload can be maintained over a long period of time. Manual retightening of the nuts after a running-in phase is thus no longer necessary. At the same time, undesirably high preloads in the legs are avoided during the running-in phase.

[0025] The spring elements can be formed by a serial and / or parallel combination of individual springs, in particular individual disc springs.

[0026] Furthermore, the spring elements can also be designed as flat wire coil springs screwed together, so-called helical disc springs. This results in a longer service life compared to a disc spring stack. Furthermore, compared to a disc spring stack, assembly is simplified, especially since the use of a helical disc spring of the appropriate length allows for characteristics equivalent to those of several disc springs or a disc spring stack, thus reducing the number of components.

[0027] Typically, the spring elements are pre-tensioned to a predefined level during assembly so that settlement effects can be compensated for by releasing the spring elements accordingly during operation. A defined level of pre-tension can be achieved, for example, using a sleeve or a steel sleeve arranged parallel to a disc spring stack or in a helical disc spring, in particular arranged in the disc spring stack or the helical disc spring, and serving as a stop for a nut used to tension the disc springs or the helical disc spring. The nut can therefore only be tightened to a position defined by the position of the stop or the length of the sleeve, whereby maximum deformation and thus pre-tension of the spring element can be clearly defined.

[0028] A defined preload can thus be achieved, in particular, without the use of a hydraulic clamping cylinder, for which there is often not enough space available.

[0029] Particularly preferably, the preload is selected such that the rotor winding head, i.e., the upper and lower bars, only lift off the retaining element above a rated speed. Thus, even with a relatively high number of start-stop cycles, a low stress amplitude is achieved in an area of ​​the threads of the brackets, via which the nuts are connected to the brackets. In the event of a malfunction, the machine can exceed the rated speed to load shedding speed or run-through speed. In these cases, the stop acts as overload protection for the spring.

[0030] In addition, the stop can prevent excessive deformation of the winding head in the case of particularly high speeds.

[0031] The legs of the bracket are typically subject to high mechanical stress, especially since they are subject to the centrifugal forces of the rotor winding head. It has therefore proven effective to provide the legs with threads, preferably formed by thread rolling. This allows the securing elements, which can particularly be designed as nuts, to be robustly mounted on the bracket.

[0032] It has proven effective to make the bracket from an austenitic material, particularly austenitic steel. This is advantageous, on the one hand, due to the magnetic field prevailing in the rotor winding head. On the other hand, an austenitic material has also proven very advantageous for this application in terms of mechanical properties.

[0033] In order to ensure robust support of the rotor winding head even at high speeds, it is preferably provided that the bracket is formed from a cold-formed metal, in particular a cold-drawn steel.

[0034] Advantageously, the retaining body comprises a ferritic material, in particular a ferritic steel, or is formed from such a material. This allows mechanical requirements to be met in a particularly reliable manner.

[0035] For this purpose, it is particularly preferred that the retaining body comprises a fine-grain steel, in particular S460, or a tempered fine-grain steel, in particular S550Q. In order to ensure particularly low magnetic losses in the winding head area, it is preferably provided that the retaining body has a ferritic inner part and a non-magnetic outer part, which consists in particular of aluminum, a fiber composite material or a hard fabric, for example epoxy resin glass fiber fabric (EPGC). The retaining body can, for example, have a ferritic inner ring and a non-magnetic outer ring, which can, for example, consist of aluminum, a fiber composite material or a hard fabric, for example EPGC. The inner ring and outer ring can also be movable relative to one another. In this case, the outer ring can be coupled to the lower bars in the axial direction and the inner ring can be rigidly coupled to the laminated core in the axial direction.It can also be provided that a contact surface between the inner ring and the outer ring is made of a material with a particularly low coefficient of friction in order to minimize wear.

[0036] A particularly robust design is achieved when the retaining body is rigidly connected to the laminated core in the axial direction. For this purpose, the retaining body can be connected, for example, by screws to a pressure plate, which in turn is rigidly connected to the laminated core.

[0037] To prevent centrifugal forces acting on the winding head from leading to additional mechanical stress on the laminated core, it is preferably provided that the retaining body is connected to the laminated core so that it can move in the radial direction, in particular by means of a radial guide. This ensures that centrifugal forces in the winding head area only lead to deformation of the winding head and the retaining body, but not to radial deformation of the laminated core, especially since the retaining body is then decoupled from the laminated core in the radial direction. The guide can, for example, comprise grooves in the retaining body or in the pressure plate as well as corresponding guide pins in the pressure plate or in the retaining body.

[0038] It is preferably provided that a component rigidly connected to the rotor laminated core, in particular a pressure plate, has first guide means extending in the radial direction, in particular radial grooves, and the retaining body has corresponding second guide means, in particular guide pins, which engage in the first guide means, so that the retaining body is movable in the radial direction by the cooperating guide means and is rigidly connected to the laminated core in the circumferential direction.

[0039] Depending on the dimensions of the rotor winding overhang, a single, usually circumferential, retaining body may be sufficient, which is usually coupled to the rotor winding overhang in the radial direction by means of brackets distributed over a circumference. Particularly in the case of very large winding overhangs, it is preferred that several, in particular three, retaining bodies are provided in the axial direction, which are kinematically coupled in the circumferential direction via radial guide means and are movable relative to one another in the radial direction, wherein the radial guide means are preferably formed by radial grooves and corresponding guide pins which engage in the radial grooves. Thus, the individual retaining bodies can be supported on one another or on the rotor laminated core in the axial and circumferential directions, while still being movable relative to one another in the radial direction.This is particularly advantageous because the rotor winding head can have a greater radial deformation at one axial end than in the area close to the laminated core.

[0040] For a robust axial connection of the retaining elements to the rotor core, it has proven effective to connect the retaining elements axially to the pressure plate using screws. The screws extend continuously from an axially outermost retaining element to the pressure plate and, in particular, are subject to a defined preload. To still ensure radial mobility between the individual retaining elements, the screws can, for example, be guided through holes in the retaining elements that are larger than the screws.

[0041] Electrical machines with rotor laminations are often manufactured by shrink-fitting the rotor laminations onto a rotor body. Openings extending axially from the inside of the rotor laminations may be provided on the rotor body to ventilate the rotor laminations. Shrink-fitting the rotor laminations thus leads to a deformation of the rotor laminations, which corresponds to the openings or arms onto which the rotor laminations are shrunk.In order to nevertheless ensure particularly reliable guidance of the retaining body in the radial direction even when the rotor is designed with a shrink fit, and to prevent movement of the retaining body relative to the rotor laminated core in the circumferential direction, a design has proven successful in which the rotor has a rotor body with arms arranged in a distributed manner along a circumferential direction and openings arranged between the arms, through which openings cooling air can be supplied to the rotor laminated core, the laminated core being shrunk onto the rotor body, the first guide means extending radially being arranged along a circumferential direction at positions which correspond to positions of the arms in the region of a pressure plate and / or to positions centrally between the arms in the region of the pressure plate. In this way, the pressure plate orThe rotor core is also only deformed radially at these positions during shrink-fitting, and no localized twisting occurs in these areas, which would bend the guides and no longer ensure proper function under all operating conditions. These positions in the center of the arms and in the center between the arms can therefore also be referred to as twist-free areas.

[0042] Typically, the bars are oriented approximately parallel to the axial direction. Furthermore, the stirrup legs are usually oriented approximately radially. This essentially only subjected the legs to tensile stress, and in particular, bending and torsional stress on the legs are largely avoided.

[0043] Depending on the size of the winding head, several brackets may be arranged along a circumferential direction. The brackets are typically positioned evenly distributed over the entire circumference of the rotor winding head.

[0044] Furthermore, depending on the size of the winding head, it may be advantageous to provide several brackets in the axial direction. Thus, brackets are preferably arranged both circumferentially and axially distributed over the rotor winding head in order to stabilize the rotor winding head evenly at several positions by means of the internal retaining body. Typically, the retaining body encloses the rotor axis and is particularly plate-shaped, preferably annular, and particularly preferably an annular disk. Centrifugal forces acting on the retaining body can then be absorbed particularly well, resulting in good stabilization of the winding head.

[0045] As designed, it can be advantageous if the legs of the bracket are prestressed, so that the retaining element is pressed against one or more lower bars of the rotor winding head. During operation, the upper and lower bars of the rotor winding head, which are usually made of copper or contain copper, heat up and therefore also expand in the axial direction. As designed, the retaining element can be rigidly connected to the laminated core axially, in particular via screws, and be subject to a different, in particular smaller, expansion in the axial direction than that of the winding head.To avoid damage during relative movement between the retaining body and the lower rods in the axial direction, as well as thermal stresses, it is preferably provided that a sliding device is arranged between the retaining body and the lower rods. This sliding device has a surface on at least one side formed by a material with a low coefficient of friction, in particular a Teflon-carbon plate. The sliding device is advantageously also designed as a component that encloses the rotor axis.

[0046] Advantageously, the sliding device is rigidly connected to the lower rods and axially movable to the retaining body. The sliding device thus generally slides with the surface formed by a material with a low coefficient of friction on the retaining body or a component rigidly connected to it.

[0047] Preferably, the sliding device has a sliding layer which is formed from a material with a low coefficient of friction, in particular by a Teflon-carbon plate with a radial height of 1 mm to 20 mm, in particular 2 mm to 10 mm.

[0048] Furthermore, it may be advantageous if the sliding device has a layer formed from a paramagnetic material, in particular aluminum or an epoxy resin-glass fabric, wherein holes are preferably provided penetrating the layer in the axial direction. The holes can thus also improve ventilation of the rotor winding head in this area. The layer typically extends completely around the rotor axis in the circumferential direction and thus separates the retaining body, which may consist of a ferromagnetic material or comprise such a material, from the lower rods over its entire circumference.

[0049] To avoid leakage currents, it may be advantageous if the sliding device has a metallic layer which is separated from the lower bars by an insulating layer rigidly connected to the metallic layer, wherein the insulating layer comprises, in particular, epoxy resin glass fiber fabric.

[0050] This insulating layer also allows the sliding device to be supported on the lower bars.

[0051] Further features, advantages, and effects of the invention will become apparent from the following exemplary embodiments. Reference is made to the drawings, which show:

[0052] Fig. 1 and 2 details of a rotor according to the invention;

[0053] Fig. 3 shows a bracket; Fig. 4 shows part of a rotor;

[0054] Fig. 5 shows another detail of a rotor;

[0055] Fig. 6 shows a detail of a sliding device;

[0056] Fig. 7 shows another detail of a rotor in exploded view;

[0057] Fig. 8 is a plan view of a rotor; Fig. 9 is a detail of another rotor;

[0058] Fig. 10 and 11 a detail of another rotor.

[0059] 1 to 3 show a portion of a winding head of a rotor according to the invention, also showing a portion of a laminated core 1 including a pressure plate 30 arranged at the end of the laminated core 1. As can be seen, the rotor comprises upper bars 4 and lower bars 3, which are arranged in slots 2 in the laminated core 1 and connected outside the laminated core 1. As is customary in such machines, which may be designed as asynchronous machines, a lower bar 3 of one slot 2 is always connected to an upper bar 4 of another slot 2, here by bar connectors 29 arranged axially at the ends of the upper bars 4 and lower bars 3.

[0060] While the upper bars 4 and lower bars 3 extend only in the axial direction 5 in the laminated core area, the upper bars 4 and lower bars 3 extend axially outside the laminated core 1 or, in the winding head area, also along a circumferential direction 7 in order to create a connection between an upper bar 4 and a lower bar 3 of two slots 2 spaced apart in the circumferential direction 7. In the illustrated embodiment, the upper bars 4 extend at an angle of approximately 45° to the rotor axis 23 or to the axial direction 5, which is parallel to the rotor axis 23, in the circumferential direction 7, while the lower bars 3 extend approximately in the opposite direction at an angle of approximately -45° to the rotor axis 23 in the circumferential direction 7.

[0061] As can be seen in Fig. 2, the upper bars 4 therefore cross the lower bars 3 at an angle of approximately 90° at crossing points 8. In the plan view shown in Fig. 2 or when viewed in the radial direction, 6 gaps 9 remain between the crossing points 8. Legs 12 of stirrups 11 protrude through some of these gaps 9 and support the winding head radially by a web 13 connecting the legs 12 of the stirrups 11 on the outside, as shown, spanning two upper bars 4 and thus radially coupling them to a retaining body 10 arranged inside the winding head. In Fig. 2, one of these stirrups 11 together with a spacer 28 is hidden, so that it can be seen that the individual stirrups 11 each overlap two upper bars 4 and two lower bars 3 as well as a gap 9 arranged between them.

[0062] For radial support of the brackets 11, a closure member 15 is provided radially inside the winding head on the legs 12 of each bracket 11. The closure member 15 has two through-bores through which the legs 12 protrude. This closure member 15 rests against an inner diameter 14 of the retaining body 10, which is annular in shape here, in order to mechanically couple the retaining body 10 to the upper bars 4 via the closure member 15 and the bracket 11. The closure member 15 is secured to the legs 12 by nuts 16. The webs 13 are mechanically coupled to the upper bars 4, which span them, here indirectly via a spacer 28, which serves to prevent pressure peaks on the upper bars 4.Thus, a radial stiffness of the winding head is increased by the brackets 11, which connect the annular retaining body 10 to the upper bars 4 and indirectly via the upper bars 4 also to the lower bars 3, which is why the brackets 11 together with the retaining body 10 form support devices for the winding head.

[0063] In the illustrated embodiment, three retaining bodies 10 are arranged in the axial direction 5 and, correspondingly, three rows of stirrups 11 are provided along the axial direction 5, each row having stirrups 11 distributed over a circumferential direction 7. The webs 13 of the stirrups 11 extend here in the axial direction 5. As shown, the webs 13 each span two upper bars 4, so that the legs 12 of the stirrups 11 are arranged in gaps 9 which border on different upper bars 4. Of course, the stirrups 11 can also span more than two upper bars 4 or more than one gap 9.

[0064] As a result, despite the intersection angle of the upper bars 4 and lower bars 3 of approximately 90°, which, in conjunction with the comparatively narrow upper bars 4 and lower bars 3, results in a small axial distance between the gaps 9, a large leg spacing 31 is achieved between the legs 12 of the stirrups 11. This thus corresponds to at least twice the distance between two axially adjacent gaps 9.

[0065] As shown, the legs 12 extend exclusively in the radial direction 6 in order to achieve essentially exclusive tensile stress on the legs 12. The retaining body 10 is arranged between two legs 12 of a bracket 11, which is why a large leg spacing 31 results in a correspondingly large retaining body 10 that can absorb corresponding forces.

[0066] The three retaining bodies 10, arranged at different axial positions, are designed as circumferential rings and can thus prevent undue deformation of the rotor winding head through the coupling via the brackets 11 and absorb any centrifugal forces that may occur. For this purpose, the legs 12 of the brackets 11 are coupled radially inward to the retaining bodies 10 via a closure member 15.

[0067] The terms axial direction 5, radial direction 6, and circumferential direction 7 are to be understood here in the sense of a cylindrical coordinate system, wherein the axial direction 5 coincides with a rotor axis 23, around which the rotor is arranged to rotate in a stator during normal operation, or is parallel to this rotor axis 23. Consequently, the circumferential direction 7 corresponds to a direction of rotation along which the rotor rotates in the stator during normal operation.

[0068] Fig. 3 shows a bracket 11 of a corresponding support device in detail, which here is U-shaped. As can be seen, the bracket 11 has two approximately parallel legs 12, which are connected by a web 13 that is aligned perpendicular to the legs 12. Threads are usually arranged on the ends of the legs 12 so that the closure member 15 can be fastened to the bracket 11 by means of two nuts 16. The threads are preferably produced by thread rolling or thread rolling in order to ensure high strength even in the thread area. The bracket 11 is generally made of austenitic, cold-drawn steel, which achieves favorable magnetic properties for use in the winding head area and, at the same time, high strength.

[0069] Between the legs 12 of the winding head, the preferably annular retaining body 10 is usually arranged within the winding head, which is why an axial extension of the retaining body 10 (not shown in Fig. 3), which can be designed, for example, as a retaining ring, or a cross-section thereof can be defined by a leg spacing 31. In the design of a corresponding rotor according to the invention, a comparatively large leg spacing 31 is achieved even with gaps 9 located closely next to one another, especially since the legs 12 protrude through gaps 9 which border different upper bars 4 or lower bars 3, so that between the gaps 9 through which the legs 12 protrude, there is usually at least one further gap 9 which is spanned by the web 13. Fig. 4 shows a rotor in an isometric view.As can be seen, the rotor has a rotor body with arms 21 distributed around a rotor axis 23, between which openings 22 are positioned. Air can be transported through these openings 22 to an inner radius of the laminated core to ventilate or cool it. The laminated core 1 is shrunk onto the arms 21 of the rotor body to form a stable connection between the laminated core 1 and the rotor body.

[0070] Fig. 5 shows a detail of a rotor in a broader view. The retaining bodies 10 are typically connected essentially rigidly to the rotor core in the axial direction 5 by screws (not shown). During operation, the lower bars 3 and upper bars 4 are subject to heating and thus thermal expansion, which causes a relative movement in the axial direction 5 between the lower bars 3 and upper bars 4 on the one hand and the retaining bodies 10 on the other. To prevent this relative movement from leading to damage, in particular to the insulation of the lower bars 3, sliding devices 24 are arranged between the retaining bodies 10 and the lower bars 3.

[0071] Fig. 6 shows a detail of such a sliding device 24, which can be rigidly connected to the lower bars 3. The sliding device 24 has a surface on the radial inside, which is formed by a material with a low coefficient of friction, usually a Teflon-carbon plate 25, which can bear against the retaining body 10. This Teflon-carbon plate 25 thus enables a low-friction relative movement between the lower bars 3, to which the sliding device 24 is usually coupled in the axial direction 5, and the correspondingly adjacent retaining body 10.

[0072] The retaining bodies 10 typically comprise a magnetic material or can be made of fine-grain steel or the like. In order to minimize magnetic losses in the winding head area, it is preferably provided that the sliding device 24 has a layer 26 formed from a paramagnetic material, in particular aluminum or epoxy resin glass fiber fabric. This layer 26 thus ensures a distance between the magnetic retaining body 10 or a magnetic part of the retaining body 10 and the lower bars 3. To prevent leakage currents, an insulating layer 27 is arranged on the outside of the sliding device 24, which can be made, for example, of epoxy resin glass fiber fabric. If the layer 26 is made of an insulating material, the insulating layer 27 can also be formed integrally with the layer 26 and, for example, be made of epoxy resin glass fiber fabric.

[0073] The fine-grained steel can thus form an inner ring of the retaining body 10, while the layer 26 made of aluminum or the sliding device can form an outer ring, wherein the outer ring ensures a distance between the lower bars 3 and the inner ring and at the same time connects the inner ring to the lower bars 3 in the radial direction.

[0074] Fig. 7 shows an exploded view of a section of three retaining bodies 10 and a part of the laminated core 1. The retaining bodies 10 each have guide pins 19 and radial grooves 18, which each extend along the radial direction 6, so that radial guides are provided and the individual retaining bodies 10 are radially movable relative to one another due to the radial guides, but are kinematically coupled to one another in the circumferential direction 7. Corresponding radial grooves 18 are also provided on the pressure plate 30 (not shown here), so that the retaining bodies 10 are also radially movable relative to the pressure plate 30, but are positively connected to the pressure plate 30 in the circumferential direction 7.In the axial direction 5, the retaining bodies 10 are, as explained, usually rigidly coupled to the laminated core 1 by screws (not shown), wherein these screws can extend from the pressure plate 30 to an axially outermost retaining body 10.

[0075] Fig. 8 shows a plan view of the rotor, wherein torsion-free regions 20 of the rotor are schematically indicated by dash-dotted lines, along which the radial guide devices, usually radial grooves 18 and corresponding guide pins 19, are arranged. These torsion-free regions 20 of the laminated core 1 and the pressure plate 30 are arranged at positions centrally on the arms 21 of the rotor body and centrally between these arms 21. By arranging the radial guides, which can be formed by grooves 2 and corresponding guide pins 19 or the like, torsion of the guides when the shrink fit is partially opened or closed during operation is easily avoided, especially since the rotor laminated core and the pressure plate 30 of the rotor are only radially deformed in these regions.

[0076] Fig. 9 shows a detail of a further exemplary embodiment, wherein a radially inner end of support devices is illustrated. Here, too, a closure member 15 is provided radially on the inside of the bracket 11, by means of which the bracket 11 is closed and coupled to the retaining body 10. Here, too, the legs 12 of the brackets 11 are guided through the closure member 15 and nuts 16 are screwed onto the ends of the legs 12 in order to fix the closure member 15 to the brackets 11. In addition, spring elements designed as disc springs 17 are provided between the nuts 16 and the closure members 15, with three disc springs 17 being positioned in series between the nuts 16 and the closure member 15. This allows a predefined preload to be introduced into the legs 12, which can be maintained via the spring elements even during settlement processes.This avoids the need to readjust the nuts 16 after the rotor has been run in.

[0077] Figs. 10 and 11 show a further embodiment in detail, again illustrating a radially inner end of a support device. Here, too, the legs 12 of the brackets 11 are guided through the closure member 15, and nuts 16 are screwed onto the ends of the legs 12 to fix the closure member 15 to the brackets 11. Furthermore, spring elements are also provided here, which connect the brackets 11 to the closure member 15 via the nuts 16, with additional steel disks 33 being arranged between the spring elements and the nuts 16. Fig. 10 shows the detail in an isometric view, while Fig. 11 shows a sectional view.

[0078] As can be seen in Fig. 11, the spring elements, which here are designed as helical disc springs 34, are arranged concentrically to the brackets 11, and a sleeve 35, which serves as a stop, is arranged parallel to the helical disc springs 34, here within the helical disc springs 34. By means of the sleeve 35, the spring elements can thus be easily preloaded to a defined deformation or a defined preload, at which deformation of the helical disc springs 34 the steel disks 33 each rest against the sleeves 35. The selected preload, in conjunction with the spring elements, thus defines the dimensions of the sleeves 35 and can, for example, be selected such that lifting of the winding head from the support device is reliably prevented up to the rated speed of the machine.In the event of a speed exceeding the rated speed, which can occur, for example, in the event of a fault, the sleeves 35 reliably prevent damage to the spring elements, especially since the sleeves 35 act as a stop and then prevent excessive deformation of the spring elements. Figs. 10 and 11 also show an anti-rotation device 32 for the nuts 16, which is positively connected to both nuts 16 to prevent accidental loosening of the nuts 16 during operation. In the illustrated embodiment, both the anti-rotation device 32 and the support device are made of EPGC, although other materials are also possible.

[0079] A rotor according to the invention enables the robust stiffening of winding heads in corresponding machines, even when the distance between gaps 9 in the winding head area is very small due to the design. Such machines can be used in particular in pumped-storage power plants.

Claims

Patent claims 1. Rotor for an electric machine, comprising a laminated core (1) with slots (2) in which lower bars (3) and upper bars (4) are arranged, which extend in the axial direction (5) beyond the laminated core (1) to form a winding head, wherein a lower bar (3) of one slot (2) is connected to an upper bar (4) of another slot (2) in the winding head, and the lower bars (3) and upper bars (4) intersect axially outside the laminated core (1) at intersection points (8) in a top view, and gaps (9) remain between the intersection points (8), wherein a support device is provided which has a retaining body (10) arranged radially inside the winding head and at least one bracket (11) with two legs (12) and a web (13), wherein the bracket (11) is connected to both the retaining body (10) and an upper bar (4) in order to support the upper bar (4) by means of the retaining body (10). radially supported, characterized by,that the legs (12) protrude through two gaps (9) which adjoin different upper bars (4).

2. Rotor according to claim 1, characterized in that the web (13) is arranged radially outside the upper bars (4) and is connected to at least two upper bars (4).

3. Rotor according to claim 1 or 2, characterized in that the retaining body (10) is ring-shaped and the legs (12) extend to an inner diameter (14) of the retaining body (10).

4. Rotor according to one of claims 1 to 3, characterized in that a locking element (15) is provided which is detachably connected to the legs (12).

5. Rotor according to claim 4, characterized in that the retaining body (10) is connected to the bracket (11) via the locking element (15).

6. Rotor according to claim 4 or 5, characterized in that the locking element (15) has radial through-holes through which the legs (12) protrude, wherein the legs (12) are located downstream of the locking element (15). Securing elements, in particular nuts (16), are provided which hold the locking member (15) on the legs (12).

7. Rotor according to claim 6, characterized in that spring elements, in particular disc springs (17), are arranged between the locking elements and the locking member (15), which are preferably preloaded with a predefined preload force.

8. Rotor according to one of claims 1 to 7, characterized in that the legs (12) have threads which are preferably formed by thread rolling.

9. Rotor according to any one of claims 1 to 8, characterized in that the bracket (11) is made of an austenitic material.

10. Rotor according to any one of claims 1 to 9, characterized in that the The bracket (11) is made of a cold-formed metal, in particular a cold-drawn steel.

11. Rotor according to one of claims 1 to 10, characterized in that the retaining body (10) comprises a ferritic material, in particular a ferritic steel, or is formed from such a material.

12. Rotor according to one of claims 1 to 11, characterized in that the retaining body (10) comprises a fine-grained steel.

13. Rotor according to one of claims 1 to 12, characterized in that the retaining body (10) has a ferritic inner part and a non-magnetic outer part, which in particular consists of aluminium, a fiber composite material or a hard fabric, for example epoxy resin-glass hard fabric.

14. Rotor according to one of claims 1 to 13, characterized in that the retaining body (10) is rigidly connected to the laminated core (1) in the axial direction (5).

15. Rotor according to one of claims 1 to 14, characterized in that the retaining body (10) is movably connected to the laminated core (1) in the radial direction (6), in particular by means of a radial guide.

16. Rotor according to one of claims 1 to 15, characterized in that a component rigidly connected to the rotor lamination stack, in particular a pressure plate (30), has first guide means extending in the radial direction (6), in particular radial grooves (18), and the retaining body (10) has corresponding second guide means, in particular guide pins (19), which engage in the first guide means, so that the retaining body (10) is movable in the radial direction (6) by the cooperating guide means and is rigidly connected to the lamination stack (1) in the circumferential direction (7).

17. Rotor according to claim 16, characterized in that several, in particular three, retaining bodies (10) are provided in the axial direction (5), which are kinematically coupled in the circumferential direction (7) via radial guide means and are movable relative to each other in the radial direction (6), wherein the radial guide means are preferably formed by radial grooves (18) and corresponding guide pins (19) which engage in the radial grooves (18).

18. Rotor according to claim 17, characterized in that the retaining bodies (10) are axially connected to the pressure plate (30) by screws, wherein the screws extend continuously from an axially outermost retaining body (10) to the pressure plate (30) and are in particular subject to a defined preload.

19. Rotor according to one of claims 16 to 18, characterized in that the rotor has a rotor body with arms (21) distributed along a circumferential direction (7) and openings (22) arranged between the arms (21) through which cooling air can be supplied to the rotor lamination stack, wherein the lamination stack (1) is shrunk onto the rotor body, wherein the first guide means, which extend radially, are arranged along a circumferential direction (7) at positions which correspond to positions of the arms (21) in the area of ​​a pressure plate (30) and / or to positions centrally between the arms (21) in the area of ​​the pressure plate (30).

20. Rotor according to one of claims 1 to 19, characterized in that the webs (13) are oriented approximately parallel to the axial direction (5).

21. Rotor according to one of claims 1 to 20, characterized in that several brackets (11) are arranged distributed along a circumferential direction (7).

22. Rotor according to any one of claims 1 to 21, characterized in that several brackets (11) are provided in the axial direction (5).

23. Rotor according to any one of claims 1 to 22, characterized in that the Retaining body (10) encloses a rotor axis (23) and is in particular plate-shaped.

24. Rotor according to any one of claims 1 to 23, characterized in that a sliding device (24) is arranged between the retaining body (10) and the lower rods (3), the sliding device having a surface on at least one side formed by a material with a low coefficient of friction, in particular by a Teflon-carbon plate (25).

25. Rotor according to claim 24, characterized in that the sliding device (24) is rigidly connected to the lower rods (3) and axially movably connected to the retaining body (10).

26. Rotor according to claim 24 or 25, characterized in that the sliding device (24) has a sliding layer which is formed from a material with a low coefficient of friction, in particular by a Teflon-carbon plate (25) with a radial height of 1 mm to 20 mm, in particular 2 mm to 10 mm.

27. Rotor according to one of claims 24 to 26, characterized in that the sliding device (24) has a layer (26) which is defined by a paramagnetic material, in particular aluminium or an epoxy resin glass fiber hard fabric, wherein preferably bores are provided in the position (26) penetrating in the axial direction (5).

28. Rotor according to one of claims 24 to 27, characterized in that the sliding device (24) has a metallic layer (26) which is separated from the lower bars (3) by an insulating layer (27) rigidly connected to the metallic layer (26), wherein the insulating layer (27) in particular comprises epoxy resin glass fabric.

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