Abstract
A squirrel-cage rotor has at least one laminated rotor core that has grooves and the squirrel-cage rotor has at least one rotor cage with electrically conductive rotor bars that are embedded in the grooves of the laminated rotor core in such a manner that the rotor bars have at their two end regions an overlap beyond the laminated rotor core, and the rotor cage has short-circuit rings that are attached at the end face to the laminated rotor core and have slots that are arranged in the region of their outer periphery and the end regions of the rotor bars protrude into said slots.
Claims
1. A method of manufacturing a squirrel-cage rotor for an asynchronous machine, the squirrel-cage rotor having at least one laminated rotor core that comprises a plurality of grooves, at least one rotor cage comprising electrically conductive rotor bars that are embedded in the grooves of the laminated rotor core in such a manner that the rotor bars comprise at their two end regions an overlap beyond the laminated rotor core and short-circuit rings that comprise a plurality of slots that are arranged in the region of their outer periphery, said method comprising the steps of: providing each of the short-circuit rings with at least two metal composite discs that comprise at least a first metal disc and a second metal disc connected to the first metal disc in a planar method through a plating process, the second metal discs being made of a different material from the first metal discs; arranging at least some of adjacent metal composite discs in such a manner that the first metal discs face one another; attaching the short-circuit rings at the end face to the laminated rotor core, the end regions of the rotor bars protruding into said slots, and bonding the rotor bars to the first metal disc in the region of the slots, two adjacent metal composite discs be connected to a rotor bar through a single connection process.
2. The method according to claim 1, characterized in that the rotor bars are made at least in part from a material that can be easily welded to the material of the first metal disc.
3. The method according to claim 2, characterized in that the rotor bars are made at least in part from a material whose base material is identical to the base material of the first metal discs.
4. The method according to claim 1, characterized in that the first metal discs comprise on their outer periphery at least one bevel.
5. The method according to claim 1, characterized in that the first metal discs are made from aluminum or an aluminum alloy.
6. The method according to claim 5, characterized in that the thickness s.sub.1 of the first metal discs is at least 60% of the thickness s of the metal composite discs.
7. The method according to claim 1, characterized in that the first metal discs are made from copper or a copper alloy.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The invention is further explained with reference to the following exemplary embodiments and with reference to the schematic drawings, in which:
[0018] FIG. 1 illustrates a sectional view of a squirrel-cage rotor,
[0019] FIG. 2 illustrates an enlarged view of the view in FIG. 1 in the region of the connection between the rotor bar and a short-circuit ring,
[0020] FIG. 3 illustrates an enlarged view of a further embodiment of a squirrel-cage rotor in accordance with the invention in the region of the connection between the rotor bar and a short-circuit ring.
[0021] Mutually corresponding parts are provided with the same reference numeral in all figures.
DETAILED DESCRIPTION OF THE INVENTION
[0022] FIG. 1 illustrates a sectional view of a squirrel-cage rotor 1 in accordance with the invention. The squirrel-cage rotor 1 has an essentially cylindrical shape with an axis A and a centrally arranged bore hole 4 for receiving a shaft, not illustrated. Said squirrel-cage rotor comprises a laminated rotor core 11 that is constructed in a manner known per se from individual metal sheets. The laminated rotor core 11 comprises a plurality of grooves 12, two of which are visible in the sectional view. Furthermore, the squirrel-cage rotor 1 comprises a plurality of electrically conductive rotor bars 2, two of which are visible in the sectional view, and also two short-circuit rings 3. The rotor bars 2 and the short-circuit rings 3 together essentially form the squirrel cage. The rotor bars 2 are embedded in the grooves 12 of the laminated rotor core 11 in such a manner that they comprise at their two end regions 21 an overlap beyond the laminated rotor core 11. Generally, the rotor bars 2 are not arranged in parallel to the axis A of the cage rotor 1 but rather are arranged inclined by a defined angle of twist with respect to the axis A. However, for reasons of clarity, this feature is not shown in the schematic illustrate in FIG. 1. The rotor bars 2 are embodied in the illustrated exemplary embodiment as solid mono-metal bars. However, it is also possible to use bi-metal bars and/or hollow bars. The short-circuit rings 3 are attached to the end faces of the laminated rotor core 11. The short-circuit rings 3 comprise in the region of their outer periphery a plurality of slots 31. The number and position of the slots 31 are to be selected such that said slots can be brought into alignment with the grooves 12 of the laminated rotor core 11. The end regions 21 of the rotor bars 2 protrude into the slots 31 of the short-circuit rings 3.
[0023] In accordance with the invention, the short-circuit rings 3 comprise in each case four metal composite discs 32 that for their part comprise in each case a first metal disc 33 and a second metal disc 34 that is connected in a planar manner to said first metal disc and is embodied from a different material thereto. In each case, two adjacent metal composite discs 32 are arranged in such a manner that the first metal disc 33 or second metal disc 34 that are embodied from an identical material are facing one another. If you count for each of the two short-circuit rings 3 the metal composite discs 32 commencing at the front face of the laminated rotor core, then in each case the second and the fourth metal composite discs 32 are arranged in a mirror-inverted manner with respect to the first and third metal composite disc 32. As a consequence, in each case between the first and the second and also between the third and the fourth metal composite disc 32, the first metal discs 33 that are embodied from an identical material are facing one another. Likewise, in each case between the second and the third metal composite disc 32, the second metal discs 34 that are embodied from an identical material are facing one another. In the schematic illustration of FIG. 1, adjacent metal composite discs 32 are illustrated for reasons of clarity in each case slightly spaced apart from one another. In reality, the metal composite discs 32 are generally positioned without a spacing with respect to one another. Furthermore, it is possible that a spacing is provided between the laminated rotor core 11 and the two metal composite discs 32 that are positioned directly adjacent to the laminated rotor core 11. The first metal discs 33 comprise on their outer periphery a circumferential bevel 35 that extends in the radial direction as far as the slots 31 of the short-circuit rings 3.
[0024] By virtue of the identical hatchings of the elements that represent the rotor bars 2 or rather the first metal discs 33 in FIGS. 1, 2 and 3, it is to be clarified that the rotor bars 2 and the first metal discs 33 are preferably embodied from identical or similar materials. It is particularly preferred that the rotor bars 2 and the first metal discs 33 are embodied from aluminum or an aluminum alloy. As illustrated in FIG. 1, in this case the thickness s.sub.1 of the first metal discs 33 is at least 60% of the total thickness s of the metal composite disc 32. In the case of an alternative embodiment, the rotor bars 2 and the first metal discs 33 can be embodied from copper or a copper alloy.
[0025] The rotor bars 21 are bonded, preferably welded, to the first metal discs 33 in the region of the slots 31. This is further explained in connection with FIG. 2.
[0026] FIG. 2 illustrates an enlarged section from FIG. 1 in the region of the connection between a rotor bar 2 and the first metal discs 33 of a short-circuit ring. A bonded connection 36 is produced in each case in the region of the slots 31 between the first metal discs 33 and the end region 21 of the rotor bar 2, illustrated in this case in a shortened manner. In the case of a solder connection, the connection 36 can be a solder material that fills a solder gap. In the case of a weld connection, the connection 36 can be formed by means of a molten material of the mutually connected partners or by means of a weld filler material. The two metal discs 34 and the rotor bar 2 are not bonded together, which is illustrated in FIG. 2 in each case by means of a gap between these components.
[0027] FIG. 3 illustrates an enlarged section of a further embodiment of a squirrel-cage rotor in accordance with the invention 1 in the region of the connection between a rotor bar 2 and a short-circuit ring 3. In the case of this embodiment, the short-circuit ring 3 comprises two metal composite discs 32 that are arranged in a mirror-inverted manner with respect to one another and comprise in each case a first metal disc 33 and a second metal disc 34, and also metal composite discs 321 that are positioned between said metal composite discs and comprise two first metal discs 33 and a second metal disc 34 that is arranged between two said first metal discs. In each case, a bonded connection 36 is provided in the region of the slots 31 between the first metal discs 33 of the metal composite discs 32 and 321 and the end region 21 of the rotor bar 2, illustrated in this case in a shortened manner. Although the outlay for producing metal composite discs 321 that comprise more than two metal discs 33, 34 is greater than when producing straightforward bi-metal discs, the outlay involved in assembling the short-circuit ring 3 is considerably reduced as a result of using this type of multi-layer metal composite discs 321. The embodiment in accordance with FIG. 3 can be modified to the extent that more than one metal composite disc 321 is used, said one metal composite disc comprising two first metal discs 33 and a second metal disc 34 that is arranged between the two first metal discs 33.
LIST OF REFERENCE NUMERALS
[0028] 1 Squirrel-cage rotor [0029] 11 Laminated rotor core [0030] 12 Groove [0031] 2 Rotor bar [0032] 21 End region [0033] 3 Short-circuit ring [0034] 31 Slot [0035] 32 Metal composite disc [0036] 321 Metal composite disc [0037] 33 First metal disc [0038] 34 Second metal disc [0039] 35 Bevel [0040] 36 Connection [0041] 4 Bore hole [0042] A Axis [0043] s Thickness of a metal composite disc [0044] s.sub.1 Thickness of the first metal disc
