Method for producing a squirrel-cage rotor

Abstract

The invention relates to a method for producing a squirrel-cage rotor (10) of a dynamo-electric machine (1), in particular an asynchronous machine, comprising the following steps, - positioning a cylindrical, magnetically conductive body in a rotationally-fixed manner, in particular a laminated core (22), having grooves (30) extending substantially axially on the outer circumference, on a shaft (17), - inserting conductor rods (11) into the grooves (30), in such a way as to result in axial projections (32) of the conductor rods (11) at the two end faces (31) of the cylindrical, magnetically conductive body, - coaxially positioning a short-circuit ring (12) consisting of at least two parts, in particular three parts, in the radial direction, on the shaft (17) at a pre-determinable axial distance (16) from the end face (31) of the magnetically-conductive body, - electrically contacting the short-circuit ring (12) with the axial projections (32) of the conductor rods (11) which each protrude from the end faces (31) of the magnetically conductive body.

Description

[0001] Description

[0002] Method for manufacturing a squirrel-cage rotor

[0003] The invention relates to a method for producing a squirrel-cage rotor of a dynamoelectric rotary machine, in particular an asynchronous machine, a squirrel-cage rotor, a dynamoelectric rotary machine, in particular an asynchronous machine, with such a squirrel-cage rotor, as well as the use of such a dynamoelectric rotary machine, in particular an asynchronous machine.

[0004] In dynamoelectric rotary machines, particularly squirrel-cage asynchronous machines, a so-called squirrel-cage is usually provided in a rotor that is mounted for rotation relative to a stator. The rotor of the asynchronous machine is therefore also referred to as a squirrel-cage rotor or squirrel-cage rotor. The squirrel-cage has squirrel-cage bars that are generally arranged axially parallel or slightly obliquely to the rotational axis of the squirrel-cage rotor, i.e., running in the axial direction.

[0005] The short-circuit bars are inserted into the rotor base body, which is usually formed as a lamination pack made up of a large number of laminations stacked axially one behind the other.

[0006] The short-circuit bars are positioned in recesses or grooves in the laminated core. At their ends, which protrude axially from the front sides of the laminated core, these axial projections of the short-circuit bars are electrically connected to one another by short-circuit rings located at both front ends of the rotor body.

[0007] Such a squirrel-cage rotor of an asynchronous machine is described, for example, in DE 195 42 962 CI. During operation of the dynamoelectric machine, strong currents are induced in the squirrel-cage due to varying magnetic fields. To minimize resistance losses, the squirrel-cage is generally made of a material with high electrical conductivity, such as copper and / or aluminum and / or an alloy containing these materials.

[0008] However, these materials have a relatively low mechanical strength against centrifugal forces.

[0009] At high circumferential rotor speeds, the components of the squirrel cage, especially the exposed squirrel cage rings, tend to deform radially due to centrifugal forces. This can also cause the laminations on the rotor's end faces in the area of ​​the slot slots to bend or even tear.

[0010] Due to the high temperatures frequently encountered during operation of the dynamoelectric machine, the strength of these components may be further reduced, which further increases the deformation tendencies.

[0011] In order to avoid deformation of the short-circuit rings, they are conventionally supported by circumferential cap rings.

[0012] DE 10 2014 220 267 A1 therefore proposes protecting the mechanically less stable short-circuit rings of the squirrel cage against radial deformations, for example due to strong centrifugal forces occurring at high speeds, by means of support disks which can be arranged on an end face of the disk pack in a similar way to a cover disk and which can stabilize the short-circuit ring with an area close to the edge that is bent axially away from the disk pack. EP 3 823 142 A1 discloses a squirrel cage rotor in which a support element made of high-strength material is provided radially inside the short-circuit rings to absorb the centrifugal forces and is integrally connected to the short-circuit ring, at least in sections.

[0013] In other designs of the short-circuit ring on smaller machines, the conductor bars are not soldered to the short-circuit rings. In comparatively smaller machines, the short-circuit cages, i.e., the conductor bars and the end-face short-circuit rings, are also manufactured from a single piece using the die-casting process.

[0014] The short-circuit ring not only carries out the current transfer between the individual bars, but must also absorb the centrifugal forces of the bar projections.

[0015] But here, too, the short-circuit ring performs the current-transmitting and supporting functions. These functions must be combined in a single material. This would mean compromises in electrical conductivity or mechanical strength.

[0016] The measures listed increase the costs and complexity of manufacturing a rotor for a squirrel-cage asynchronous machine or are no longer economically feasible for larger power outputs or rotor shaft heights.

[0017] The invention is therefore based on the object of creating a rotor, in particular of a squirrel-cage asynchronous machine, which is suitable for high speeds of squirrel-cage asynchronous machines, especially in industrial environments, and which is comparatively easy to manufacture.

[0018] The solution to the problem is achieved by a method for producing a squirrel-cage rotor of a dynamoelectric machine, in particular an asynchronous machine, by the following steps: - Rotationally fixed positioning of a cylindrical magnetically conductive body, in particular a laminated core, with essentially axially extending grooves on the outer circumference, on a shaft,

[0019] - Inserting conductor bars into the grooves in such a way that axial projections of the conductor bars are produced on both end faces of the cylindrical magnetically conductive body,

[0020] - coaxial positioning of a short-circuit ring, which is at least three-part in the radial direction, on the shaft at a predeterminable axial distance from the front side of the magnetically conductive body,

[0021] - electrical contact of the short-circuit ring with the axial projections of the conductor bars protruding from the end faces of the magnetically conductive body.

[0022] The stated object is also achieved by a squirrel-cage rotor according to the invention of a dynamoelectric machine, in particular an asynchronous machine, wherein the short-circuit rings are axially spaced from the magnetically conductive cylindrical body, in particular the laminated core, in particular are equidistantly spaced, so that the short-circuit rings do not form a closed jacket surface with the magnetically conductive cylindrical body.

[0023] The solution to the problem is also achieved by a dynamoelectric machine, in particular an asynchronous machine with a squirrel-cage rotor manufactured according to the invention.

[0024] The solution to the problem is also achieved by using a dynamoelectric machine according to the invention, preferably in the industrial environment of the oil and gas industry, the food industry, and production machines, for example as fans, compressors, condensers and / or pumps.

[0025] According to the invention, the short-circuit ring of a dynamoelectric rotary machine, preferably a squirrel-cage asynchronous machine, is constructed in several parts. It is also referred to as a hybrid short-circuit ring. The short-circuit ring preferably has concentric rings arranged radially one above the other.

[0026] According to the invention, the functions of current conduction and centrifugal force absorption of the short-circuit ring are separated.

[0027] With two rings, one ring absorbs the centrifugal force, and the second ring carries the current. The second ring of the short-circuit ring absorbs the current exclusively, or at least predominantly. A high-strength first ring, e.g., made of steel, located concentrically beneath this second ring, supports the "current ring" (second ring) against the centrifugal force.

[0028] The first high-strength ring is arranged radially above the second ring in a different design. The centrifugal force is also absorbed by the first ring.

[0029] With three rings, the first ring (radially inner ring made of high-strength steel) absorbs the centrifugal force, while a radially outer ring (third ring) and possibly a second ring located between the first and third rings - all of which are arranged coaxially - carry the current.

[0030] Likewise, in one design, the first high-strength ring can be arranged radially above the two current-carrying rings. These three rings are also arranged coaxially.

[0031] The hybrid short-circuit rings according to the invention offer the following advantages:

[0032] According to the invention, the functions of power transmission and centrifugal force absorption are separated so that the materials required for each of these can be optimally selected. The components are firmly bonded together, ensuring reliable operation of a dynamo-electric machine. The high-strength first ring absorbs centrifugal force during operation of the dynamo-electric machine, enabling high circumferential speeds of the squirrel-cage rotor and thus also of the current ring(s). This can even eliminate the need for otherwise necessary gears, resulting in significantly more compact systems.

[0033] The first ring can be positioned directly on the shaft. In this case, the first ring has axially extending recesses to allow cooling air to enter the space between the short-circuit ring and the end face of the magnetically conductive body.

[0034] The first ring can also be arranged at a distance from the shaft.

[0035] In a specific embodiment, there is a high-strength connection of an inner steel ring (first ring) with a comparatively thinner outer copper ring (second ring).

[0036] This material-tight connection was produced, for example, using the “EXP Welding (explosion welding)” process, i.e. explosive plating.

[0037] During explosive plating, a copper ring is exploded onto the high-strength steel ring.

[0038] This can be done individually for each short-circuit ring. It is also conceivable to connect a copper pipe to a stack of steel rings by blasting, and then, based on the specified axial dimensions of the steel rings, to separate the blasted copper pipe, thus obtaining a predefined number of short-circuit rings from a single blasting process.

[0039] With EXP-Welding, for example, an outer copper pipe with a specified material thickness of a few millimeters to a few centimeters, preferably a maximum material thickness of approximately 15 mm (10 mm after final processing), is explosively plated.

[0040] In explosive plating, an explosive is applied as a uniform, flat layer. The type of explosive (detonation velocity, etc.) and the degree of insulation depend on the materials being processed and their design. Explosives with detonation velocities of 2000 to 5000 m / s are typically used. The explosive charge(s) are detonated either from the center above the object or from the edge on at least two sides (exact depiction of the underside structure).

[0041] Primarily, expensive corrosion- and / or heat-resistant materials are applied in a thin layer to thicker, less expensive carbon steels on one or both sides. The advantage is the physically strong bond between the cladding partners (first ring and second ring) without structural changes and pronounced metallurgical mixing and heat-affected zones, such as those that occur with cladding by overlay welding. Explosion cladding allows metals that would otherwise be difficult to join, such as aluminum to steel, copper to steel, etc., to be securely joined. The explosion-applied cladding resists chemical corrosion and / or heat exposure, while the steel ring bears the mechanical loads, particularly centrifugal stresses during operation of the dynamoelectric rotating machine.

[0042] In this embodiment, the hybrid short-circuit ring consists of three concentric rings made of different materials, each of which has been bonded together using various known technologies.

[0043] In addition to explosive plating, other technologies for constructing a short-circuit ring with a high-strength first ring are also conceivable for producing a material-tight, high-strength connection, such as MELD (Additive Erection Stir Deposition Technology), WEBAM (Wire Electron Beam Additive Manufacturing), LMD (Laser Metal Deposition), cold spray, galvanization, gluing, soldering and welding.

[0044] For the purposes of the present invention, a material-to-material bond is defined as a bond in which the connecting partners are held together by atomic or molecular forces (i.e., intermolecular or chemical bonding forces). At the same time, they are non-detachable bonds that can only be separated by destroying the connecting elements. In some cases, a mechanical "interlock" of the connecting partners may also occur, creating an additional frictional connection.

[0045] The Gold Spray process, also known as cold gas spraying, is a well-known coating process in which a coating material in powder form is applied to a carrier material, the substrate, e.g. the first ring or second ring, at a comparatively very high particle speed. For this purpose, a process gas such as nitrogen or helium heated to a few hundred degrees is accelerated to supersonic speed by expansion and the powder particles are injected into the gas jet. These injected spray particles are accelerated to such a high speed that, in contrast to other thermal spraying processes, when they hit the substrate they form a dense and firmly adhering layer without prior melting or melting. The kinetic energy at the time of impact is not sufficient for the particles to melt completely.

[0046] Galvanization basically refers to the electrochemical deposition of metallic deposits, i.e. coatings on workpieces in an electrolytic bath.

[0047] In electroplating, a direct electric current is passed through an electrolytic bath. A metal (copper or nickel) is dissolved at the positive pole (anode) and then transferred to the negative pole (cathode). The metal ions dissolved in the electrolytic bath are deposited by chemical reduction on the workpiece, which is electrically connected to the negative pole and thus serves as the cathode.

[0048] Alternatively, the metal ions are already present in the electrolyte as a solution. The metal ions are deposited relatively evenly on the workpiece at the negative pole, and the layer thickness increases over time.

[0049] Electroplating is used to produce metallic coatings on selected substrates, e.g. second ring on first ring.

[0050] Electroforming – another area of ​​electroplating technology – also allows for the production of larger layer thicknesses, e.g. of copper on steel.

[0051] In so-called electron beam welding, the beam generated in the high vacuum is released into the atmosphere through holes over several pressure stages ("threaded out"), so that a workpiece to be machined, e.g. the first ring, does not have to be placed in a vacuum chamber.

[0052] While the electron beam is scattered little or not at all by residual gas molecules in a vacuum (working distances of up to 2m are possible), the escaping electrons collide with the particles of the dense atmosphere, causing them to be strongly scattered. Depending on the distance traveled, the power density of the beam decreases. However, working distances between 5mm and 30mm are still possible, allowing deep penetration welding. Beam powers, for example, are up to 30kW.

[0053] The slightly broadened beam now makes it possible to bridge significant component and process tolerances (position, spacing, edge misalignment, joint gap, etc.), which is particularly advantageous for larger components. A torch of metal vapor plasma forms above the weld, protecting the liquid weld metal. This plasma is penetrated by the electron beam virtually unhindered (without absorption).

[0054] Electron beam welding under atmospheric pressure enables fast-moving, continuous welds.

[0055] A change in power density—at a given beam power—is possible by varying the working distance of the beam from the respective operating point. The process parameters are therefore the beam power, the working distance, and the feed rate.

[0056] According to the invention, each component (first ring, second ring, and third ring) can be selected according to the material properties optimal for its function. Materials with defined, usually high electrical conductivity, such as copper or aluminum or their alloys, are used for current transmission (third and / or second ring). Components with very high mechanical strength, such as steel or its alloys, are used for centrifugal force loading (first ring).

[0057] The conductor bars protruding from the rotor core have a height of, for example, 30 to 50 mm, depending on the machine's power. This means that an additional copper ring with a height of, for example, 20 to 40 mm may need to be placed on top of the explosion-plated copper ring (second ring) to create a highly electrically conductive connection / contact between the conductor bars and the short-circuit ring. In addition to the other connection methods listed, the EBW (electron beam welding) process is suitable for this purpose.

[0058] After the conductor bars have been inserted into the magnetically conductive body and the short-circuit rings have been prepared, the conductor bars or short-circuit bars are electrically contacted directly to the electrically conductive rings of the short-circuit ring (e.g. a short-circuit ring made of copper), in particular by soldering, using silver or phosphorus solder or welding.

[0059] The power transmission and the centrifugal force absorption during operation of the dynamo-electric rotating machine are thus compactly combined in a multi-part short-circuit ring.

[0060] Advantageously, the squirrel-cage rotor with its short-circuit rings and conductor bars has material-fit, high-strength connections between different components (rings, conductor bars and their contacts).

[0061] Embodiments of a short-circuit ring with more than two or three parts or rings are also conceivable. For example, an additional radially outer cap ring / support ring, also bonded together, or using other intermediate materials, could absorb the centrifugal force.

[0062] Likewise, a bandage on the outer circumference of the short-circuit ring to absorb the centrifugal forces is conceivable, either alone or in addition.

[0063] It is also conceivable that, using the connection technologies described above, the current-carrying copper can be added directly to the steel ring in the required dimensions - for example, radial height and / or axial extension - with a material-to-material connection.

[0064] The invention extends not only to generally known dynamoelectric rotary squirrel cage asynchronous machines, but also, for example, to synchronous machines which have a damper cage in the rotor.

[0065] The invention and further advantageous embodiments of the invention are explained in more detail using exemplary embodiments shown in principle, in which: FIG 1 shows a basic longitudinal section of a dynamo-electric machine,

[0066] FIG 2 Detailed view of a squirrel-cage rotor in the area of ​​the short-circuit ring,

[0067] FIG 3 perspective view of a cut-open squirrel-cage rotor,

[0068] FIGS 4 to 6 Detailed view of a squirrel-cage rotor in the area of ​​the short-circuit ring,

[0069] FIG 7 exemplary application of a squirrel-cage rotor,

[0070] FIGS 8 to 17 show further embodiments of the short-circuit rings.

[0071] It should be noted that terms such as "axial," "radial," "tangential," etc., refer to the axis 18 used in the respective figure or in the respective example described. In other words, the directions axial, radial, and tangential always refer to an axis 18 of the rotor 10 and thus to the corresponding axis of symmetry of the stator 2. "Axial" describes a direction parallel to the axis 18, "radial" describes a direction orthogonal to the axis 18, toward it, or away from it, and "tangential" is a direction that is directed circularly around the axis 18 at a constant radial distance from the axis 18 and at a constant axial position. The term "in the circumferential direction" is synonymous with "tangential." In relation to a surface, e.g. a cross-sectional area, the terms "axial", "radial", "tangential" etc. describe the orientation of the normal vector of the surface, i.e. the vector that is perpendicular to the surface in question.

[0072] The term "coaxial components", for example coaxial components such as the rotor or squirrel-cage rotor 10 and stator 2, is understood here to mean components that have the same normal vectors, i.e. for which the planes defined by the coaxial components are parallel to one another. Furthermore, the expression should include that the centers of coaxial components lie on the same axis of rotation or symmetry. However, these centers can possibly lie at different axial positions on this axis and the said planes can therefore have a distance >0 from one another. The expression does not necessarily require that coaxial components have the same radius.

[0073] The term "complementary" in the context of two components which are "complementary" to one another means that their external shapes are designed in such a way that one component can preferably be arranged completely within its complementary component, so that the inner surface of one component and the outer surface of the other component ideally touch each other seamlessly or over their entire surface. Consequently, in the case of two objects which are complementary to one another, the external shape of one object is determined by the external shape of the other object. The term "complementary" could be replaced by the term "inverse".

[0074] For the sake of clarity, in some cases where components are present more than once, not all of the components shown are provided with reference symbols in the figures.

[0075] The described embodiments can be combined in almost any way. Individual features of the respective embodiments can also be combined without departing from the essence of the invention.

[0076] FIG. 1 shows a dynamoelectric rotary squirrel-cage asynchronous machine 1 with a stator 2 constructed from axially layered laminations 9 and having slots 8 directed toward an air gap 34. A winding system 3 is arranged in the slots 8 of the stator 2, forming winding heads 4 on the end faces of the stator 2. A squirrel-cage rotor 10 is connected in a rotationally fixed manner to a shaft 17 at a radial distance from the air gap 34. The bearing shields 6 are positioned in a housing 5.

[0077] The squirrel-cage rotor 10 comprises axially layered laminations forming a laminated core 22 having grooves 30 facing the air gap. Electrical conductors, in particular conductor bars 11, are arranged in the grooves 30, with short-circuit rings 12 being arranged on the end faces 31 of the laminated core 22 of the squirrel-cage rotor 10. Short-circuit rings 12 are electrically contacted at the axial projections 32 of the conductor bars 11.

[0078] The squirrel-cage rotor 10 is set in rotation about an axis 18 by electromagnetic interaction of the energized winding system 3 of the stator 2 with the squirrel-cage (conductor bars 11 with short-circuit rings 12) of the squirrel-cage rotor 10.

[0079] In order to be able to use the dynamoelectric rotary squirrel cage asynchronous machine 1 for higher speeds on a working machine, in particular without a gearbox, also in the higher power range above 1 MW, the short-circuit ring 12 is designed as described and shown below.

[0080] FIG 2 shows a detailed view of the squirrel-cage rotor 10 in the area of ​​the short-circuit ring 12. The short-circuit ring 12 is constructed in three parts in the radial direction. There is a first ring 13, which is designed as a steel ring, and radially adjoining this is a second ring 14. The first and the second ring are connected to one another by a first material-fit connection 20. Radially adjoining the second ring 14 is a third ring 15, which is material-fit connected to the second ring 14 by means of a second connection 21. The second and the third rings 14, 15 are preferably made of a material with comparatively good electrical conductivity, such as copper or aluminum or their alloys. The first ring 13 is designed as a steel ring in order to absorb the centrifugal forces of the squirrel-cage rotor 10, in particular the centrifugal forces acting on the short-circuit rings 12 during operation of the dynamo-electric machine.

[0081] Thus, in this embodiment, the squirrel-cage rotor 10 consists of a hybrid squirrel-cage ring comprising three rings, in particular three concentric rings 13, 14, 15 with at least two different materials, which are each bonded to one another using different or identical technologies.

[0082] The first ring 13 is spaced apart from the shaft 17 in order to allow, among other things, an air flow to access an intermediate space 35 between the short-circuit ring 12 and the end face of the laminated core 22.

[0083] Depending on the distance 19, for example, more or less air can flow in.

[0084] FIG. 3 shows a perspective view of the squirrel-cage rotor 10, with short-circuit rings 12 axially spaced from the laminated core 22. The laminated core 22 of the squirrel-cage rotor 10 is connected in a rotationally fixed manner to the shaft 17. Due to the axial spacing 16, the axial projections 32 of the conductor bars 11 can be comparatively easily electrically contacted with the short-circuit rings 12, in particular the second ring 14 and / or the third ring 15, for example by a soldering or welding process.

[0085] Such a squirrel cage rotor 10 (i.e. a classic squirrel cage rotor, as well as a damper cage of a synchronous rotor) has, for example, the following dimensions, which are not necessarily limiting:

[0086] Length from one short-circuit ring 12 to the other short-circuit ring 12 up to 2m, with an axial extension of the shaft of up to 6m and a diameter of up to 1.5m. The short-circuit ring 12 itself has an axial extension of up to 0.6m, in particular 0.3m.

[0087] In this case, the conductor bars on the second and / or third ring 14, 15 are electrically contacted on the end face of the short-circuit ring 10 facing the end face 31 of the laminated core 22.

[0088] During a soldering process, a circumferential groove or a contact recess 38 on the second and / or third ring 14, 15 may be helpful for contacting the short-circuit ring 12 and the respective conductor bar 11, for example as a soldering pan.

[0089] Using the EXP welding process, the second ring 14 is bonded to the first ring 13. For example, an outer copper tube (second ring) with a maximum radial material thickness of approximately 15 mm is explosively bonded to the first ring 13, i.e., the steel ring.

[0090] In explosive plating, the explosive is applied as a uniform, flat layer. The explosive charge(s) are detonated either simultaneously from the outside radially or with a minimal delay, so that a wave-like pattern runs around the outer circumference.

[0091] In any case, a strong bond between the cladding partners (first ring 13 and second ring 14) is established without any structural change in the materials (for example steel and copper) and without a pronounced metallurgical mixing and heat-affected zone occurring, as is known, for example, in build-up welding.

[0092] The blasted plating of the second ring 14 resists chemical corrosion and / or heat exposure, and the steel ring bears the mechanical loads, in particular centrifugal force loads during operation of the dynamoelectric rotary machine 1. The third ring 15 is applied to the second ring 14 at least in sections by the aforementioned further material-bonding processes in order to form the hybrid short-circuit ring in this embodiment from three concentric rings 13, 14,

[0093] 15 to receive .

[0094] Figures 4 to 6 show further detailed views of a squirrel-cage rotor 10 in the area of ​​the short-circuit ring 12. Figure 4 shows three concentric rings 13, 14, 15 with the same axial extension and an equidistant distance

[0095] 16 from the end face 31. The first ring 13 is radially spaced from the shaft 17.

[0096] FIG. 5 shows three concentric rings 13, 14, 15 with the same axial extent, with the short-circuit ring 12 directly abutting the end face 31, i.e., having no distance 16 from the end face 31. The steel ring (first ring 13) is positioned on the shaft and has axial recesses 23.

[0097] The short-circuit ring 12 according to FIG. 6 differs from the short-circuit ring according to FIG. 4 only in the design of the first ring 13, which is trapezoidal in cross-section in order to be able to absorb the centrifugal forces better.

[0098] In each case, the second ring 14 is integrally connected to the first ring 13 by means of an explosive plating process.

[0099] FIG. 7 shows another dynamoelectric machine 1 designed for higher power outputs, for example, in which both the stator 2 and the squirrel-cage rotor 10 are constructed using partial laminated cores 24, 25. Furthermore, a fan 27 is located radially beneath the winding heads 4 to provide the appropriate cooling capacity. Furthermore, various types of add-on coolers 29 in the form of tubular coolers or plate coolers can be provided on the housing 5.

[0100] In principle, the aforementioned processes create a stable bond between the individual rings 13, 14, 15 within the short-circuit ring 12. This stable bond significantly increases the resistance of the short-circuit ring 12 to centrifugal forces, thus enabling the use of the squirrel-cage rotor 10 in dynamoelectric machines 1 even for higher speeds with minimal material and manufacturing expenditure.

[0101] It should be noted that the invention can also be applied in the same way to a solid rotor body made of steel as a magnetically conductive body.

[0102] The high-strength first ring 13 absorbs the centrifugal force during operation of the dynamoelectric machine 1, in particular a squirrel-cage asynchronous machine, enabling high circumferential speeds of the squirrel-cage rotor 10 and thus also of the current ring(s) of the squirrel-cage rings 12. This can even eliminate the need for otherwise necessary gears, resulting in significantly more compact systems.

[0103] Figures 8 to 15 show exemplary possible embodiments of short-circuit rings 12. All embodiments show a through-opening 36 of the steel ring (first ring 13), which encompasses a shaft 17 with a radial distance 19, for example as in FIG. 2 or FIG. 3 or, as also shown in FIG. 5, the short-circuit ring 12, in particular the first ring 13, rests with its inner circumferential surface directly against the shaft 17.

[0104] Furthermore, these embodiments show that the axial extensions 39 of the individual rings 13, 14, 15 can be designed differently. Furthermore, balancing grooves 37 are provided on one end face of the squirrel-cage ring 12, in particular on the first ring 13, which are suitable for subsequent balancing of the squirrel-cage rotor 10. The balancing grooves 37 extend essentially equidistantly around the axis 18 on the side facing away from a laminated core of the squirrel-cage rotor 12.

[0105] An electrically conductive ring 14, as already explained above, is arranged on the first ring 13 (steel ring). This ring has contact recesses 38 on the side facing the laminated core of the squirrel-cage rotor 12, for electrically contacting the respective conductor bars 11 with the squirrel-cage ring 12.

[0106] The contact recesses 38 are present only on one ring 14 or - if two electrically conductive rings are present - possibly also distributed over both electrically conductive rings 14, 15, as is shown for example in FIGS. 8, 9 and 14.

[0107] Furthermore, in particular the conductive rings 14, 15 can have different radial and / or axial extensions, this then leads to a profiled course 40, especially of the outer surface of the short-circuit ring according to FIGS. 8, 9, 11, 13 and 15 and / or an end face of the short-circuit ring 12.

[0108] As FIG. 10 particularly shows, the contact surfaces of the second and third rings 14, 15 are provided with only a comparatively small contact surface 33 due to their arrangement on the first ring 13 (for example, a steel ring). The contact recesses 38 for contacting the short-circuit ring 12 and the respective conductor bar 11, for example, as a soldering pan, are therefore also assigned only to the second ring 14.

[0109] FIGS. 16 and 17 each show a short-circuit ring 12 in which the first ring 13 is arranged radially outward or radially between current-carrying rings 14, 15. The rings 13, 14, 15 are each arranged concentrically and can also be based on the previous embodiments (FIGS. 2 to 6 and FIGS. 8 to 15) in their respective implementation.

[0110] Thus, the current-carrying rings 14, 15 are arranged on the inner circumferential surface of the first ring 13 and / or its outer circumferential surface in order to withstand the centrifugal force stresses.

[0111] In the hybrid squirrel cage rings described, the functions of "current transmission" and "centrifugal force absorption" are fundamentally separated, so that the materials required for each of these can be precisely selected. The components are firmly bonded, ensuring reliable operation of a dynamoelectric machine. The high-strength first ring 13 absorbs the centrifugal force during operation of the dynamoelectric machine, enabling high circumferential speeds of the squirrel cage rotor and thus also of the current ring(s).

[0112] In addition to explosive plating, one or more of the additive manufacturing processes listed are selected for any further materially bonding processes for the rings 13, 14, 15, depending on the requirements, inter alia, for the short-circuit ring 12: processes using the "electro beam welding" method, processes using the "wire feed electron beam additive manufacturing" method, processes using the "cold spray additive manufacturing" method, processes using the "wire / powder feed laser metal deposition" method, processes using the "friction deposition additive manufacturing" method or "rotary friction welding".

[0113] A dynamoelectric machine 1 with a squirrel-cage rotor 10 equipped according to the invention is used in a wide variety of applications, particularly in the megawatt range. Preferably, it is used in industrial environments such as the oil and gas industry, the food industry, and in production machines, for example, as fans, compressors, condensers, and / or pumps—especially in the high-speed range n > 3000 rpm.

Claims

Patent claims 1. Method for producing a squirrel-cage rotor (10) of a dynamoelectric machine (1), in particular an asynchronous machine, by the following steps: - Rotationally fixed positioning of a cylindrical magnetically conductive body, in particular a laminated core (22), with substantially axially extending grooves (30) provided on the outer circumference, on a shaft (17), - inserting conductor bars (11) into the grooves (30) in such a way that axial projections (32) of the conductor bars (11) are produced on the two end faces (31) of the cylindrical magnetically conductive body, - coaxial positioning of a short-circuit ring (12) which is at least two-part, in particular three-part, in the radial direction on the shaft (17) at a predeterminable axial distance (16) from the end face (31) of the magnetically conductive body, - electrical contacting of the short-circuit ring (12) with the axial projections (32) of the conductor bars (11) projecting from the end faces (31) of the magnetically conductive body.

2. Method according to claim 1, characterized in that the multi-part short-circuit ring (12) has a first ring (13) made of high-strength material, in particular a steel ring, a second ring (14) made of a first electrically conductive material, in particular copper, and optionally a third ring (15) made of a second electrically conductive material, wherein the second ring (14) is materially connected, in particular in sections, to the inner and / or outer circumferential surface of the first ring (13) by means of a first materially bonding method, in particular by means of explosive plating.

3. Method according to claim 2, characterized in that the second ring (14) is further materially connecting process with the third ring (15), in particular in sections, materially connected.

4. Method according to one of the preceding claims, characterized in that the second and third rings (14, 15) are made of the same electrically conductive material.

5. Method according to one of the preceding claims, characterized in that the materially bonding methods (20, 21) are different.

6. Method according to one of the preceding claims, characterized in that the material-locking method for connecting the second and third rings (14, 15) is carried out as at least one one-sided I-seam.

7. Method according to one of the preceding claims, characterized in that the three rings (13, 14, 15) are designed as concentric rings with approximately the same axial extent.

8. Method according to one of the preceding claims, characterized in that at least the electrically conductive rings (14, 15), in particular the two electrically conductive rings of the short-circuit ring (12), are spaced equidistantly from the end face (31) of the cylindrical magnetically conductive body.

9. Method according to one of the preceding claims, characterized in that the first ring (13) of the multi-part short-circuit ring (12) is arranged radially inward and optionally has axially extending recesses (23) in the region of the shaft (17).

10. Method according to one of the preceding claims, characterized in that for the materially bonding method, one or more of the following additive manufacturing methods are selected depending on the requirements, inter alia, for the short-circuit ring (12): "electro beam welding" method, "wire feed electron beam additive manufacturing" method, "cold spray additive manufacturing" method, "wire / powder feed laser metal deposition" method, "friction deposition additive manufacturing" method or "rotary friction welding".

11. Method according to one of the preceding claims, characterized in that copper or aluminum or their alloys are provided as the conductive material for the short-circuit rings (12).

12. Squirrel-cage rotor (10) of a dynamoelectric machine (1), in particular an asynchronous machine manufactured according to one of claims 1 to 11, characterized in that the short-circuit rings (12) are axially spaced from the magnetically conductive cylindrical body, in particular the laminated core (22), in particular are equidistantly spaced, so that the short-circuit rings (12) do not form a closed jacket surface with the magnetically conductive cylindrical body.

13. Dynamoelectric machine (1), in particular an asynchronous machine with a squirrel-cage rotor (10) according to claim 12, characterized in that the dynamoelectric machine (1) is suitable for speeds greater than 5000 rpm.

14. Use of a dynamoelectric machine (1) according to claim 13, preferably in the industrial environment of the oil and gas industry, the food industry, production machines, for example as fans, compressors, compressors and / or pumps, especially for speeds greater than 3000 rpm.

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