Patent Application
20120146336
The present application claims priority from Japanese patent application serial no. 2010-273121, filed on Dec. 8, 2010, the content of which is hereby incorporated by reference into this application.
The present invention relates to a permanent magnet rotating electrical machine, and a method for manufacturing a rotor of the same, and in particular, to a permanent magnet rotating electrical machine mounted in a wind turbine generator, or a rail car, suitable for use as one with a magnetized permanent magnet embedded in a rotor core, and a method for manufacturing a rotor of the same.
As progress has lately been made in miniaturization, and higher efficiency of rotating electrical machines, a permanent magnet rotating electrical machine has come to be used in a variety of fields.
Problems with application of a permanent magnet include manufacturing of a rotor. In the case of a rotating electrical machine in a several MW output class, such as a rail car generator, a wind turbine generator, and so forth, in particular, if an attempt is made to cause a magnet to be magnetized after formation of a rotor (a state in which a rotor core, and end plates are fixed to a rotating shaft), a magnetization device for use in magnetization will increase in size, so that it is considered more appropriate to manufacture a rotating electrical machine by use of a magnetized permanent magnet.
However, if an attempt is made to insert a magnetized permanent magnet into the rotor core at the time of manufacturing a rotor using a magnetized permanent magnet, there is a possibility that magnetic steel sheets making up the rotor core will come apart by the agency of an attractive force of the magnetized permanent magnet, thereby raising a risk that it becomes difficult to secure laminated magnetic steel sheets. Further, it is known that the characteristics of a permanent magnet undergo deterioration at a high temperature due to irreversible degaussing, and if the rotor core is fixed to the rotating shaft by shrinkage fit, this will cause the permanent magnet to be at high temperature, rendering it impossible to adopt the shrinkage fit for fixing of the rotor core to the rotating shaft.
Accordingly, in Japanese Unexamined Patent Application Publication No. 2010-142038, as a conventional technology, there is described a method for inserting a magnetized permanent magnet into a rotor core after formation of a rotor.
In Japanese Unexamined Patent Application Publication No. 2010-142038, it is described that an end plate is formed of a resin material, thereby rendering it possible to insert a permanent magnet into a rotor core after formation of a rotor, and further, to aim at reduction in weight, and enhancement in production efficiency.
However, if the end plate is formed of the resin material as described in Patent Document 1, this will cause the resin material to undergo deterioration in strength due to aging degradation, thereby raising a problem in that, in case the permanent magnet is broken, it will be impossible to prevent the permanent magnet from popping out, so that long-term reliability cannot be ensured.
The present invention has been developed in view of the problem described as above, and it is an object of the invention to provide a permanent magnet rotating electrical machine capable of preventing a magnetized permanent magnet from popping out even though the magnetized permanent magnet is inserted after a rotor is formed, thereby ensuring long-term reliability, and a method for manufacturing a rotor of the same.
In order to attain the object of the invention, the invention provides in its one aspect a permanent magnet rotating electrical machine comprising a stator provided with a stator coil applied in a plurality of slots provided in a stator core, respectively, and a rotor disposed opposite to the stator with a predetermined gap interposed therebetween, the rotor including a permanent magnet embedded in each of magnet-insertion holes provided in a rotor core of the rotor while polarity of the permanent magnet being varied on a pole-by-pole basis, and end plates disposed at ends of the rotor core, in the axial direction thereof, respectively, wherein one end plate of the end plates disposed at the ends of the rotor core, in the axial direction thereof, respectively, is provided with magnet-insertion holes, and each of the magnet-insertion holes provided in the one end plate is filled up with a non-magnetic material, thereby stopping up the magnet-insertion holes.
Further, in order to attain another object of the invention, the invention provides in its another aspect a method for manufacturing a rotor of a permanent magnet rotating electrical machine, comprising the steps of laminating a plurality of magnetic steel sheets in the axial direction of the rotor, thereby forming a rotor core with magnet-insertion holes provided therein, disposing one end plate with magnet-insertion holes formed therein, at one end of the rotor core, in the axial direction thereof while disposing the other end plate without the magnet-insertion hole formed therein, at the other end of the rotor core, in the axial direction thereof, inserting a magnetized permanent magnet into each of the magnet-insertion holes of the rotor core via each of the magnet-insertion holes provided in the end plate after fixedly attaching the rotor core, and both of the end plates to a rotating shaft, and filling up each of the magnet-insertion holes provided in the end plate with a non-magnetic material after the magnetized permanent magnet is inserted, thereby stopping up each of the magnet-insertion holes provided in the end plate. With the permanent magnet rotating electrical machine according to the invention, it is possible to prevent a magnetized permanent magnet from popping out even though the magnetized permanent magnet is inserted after a rotor is formed, so that the invention can provide a permanent magnet rotating electrical machine with its long-term reliability ensured.
There is described in detail hereinafter a permanent magnet rotating electrical machine on the basis of embodiments of the invention with reference to the accompanied drawings. In respective figures, identical parts are described by use of like reference numerals.
As shown in the figure, a rotating shaft 3 is fixedly attached to a rotor core 2 of a rotor 1, and the rotor 1 is disposed opposite to a stator 5 with a predetermined gap interposed therebetween, the stator 5 including a stator coil 4 applied in a plurality of slots provided in a stator core, respectively, by distributed winding, and lap winding. The rotor core 2 is provided with a plurality of magnet-insertion holes 6, each of the magnet-insertion holes 6 being for use in insertion of a permanent magnet 7, and the permanent magnet 7 is embedded in each of the magnet-insertion holes 6. As to the plurality of magnet-insertion holes 6, two pieces of the magnet-insertion holes 6, making up a pair, are formed in a shape resembling the letter V, as seen in cross section, and plural pairs thereof are disposed in the circumferential direction of the rotor core 2, and are extended in a straight line in the axial direction thereof, the permanent magnet 7 being inserted in each of these magnet-insertion holes 6 to be disposed therein.
In order to enable the permanent magnet 7 to be inserted into the magnet-insertion hole 6, the magnet-insertion hole 6 is formed to be larger in size than the permanent magnet 7. Further, respective ends 8 of the magnet-insertion hole 6 need not be similar in shape to respective ends of the permanent magnet 7. In
Further, the end 8 of the magnet-insertion hole 6, in cross section, may be substantially in a triangle-like shape, or a shape in parallel with the outside diameter of the rotor.
Further, the end plates 9, 10 disposed at the ends of the rotor core 2, respectively, differ in shape from each other.
The end plates 9, 10 are shown in
As the end plate 9 is provided with the magnet-insertion holes 11, the rotor core 2, together with the end plates 9, 10, can be fitted onto the rotating shaft 3 by shrinkage fit, and the permanent magnet 7 that has already been magnetized can be inserted into each of the magnet-insertion holes 6 of the rotor core 2 via each of the magnet-insertion holes 11 of the end plate 9.
Accordingly, the magnetic steel sheets are firmly secured by the end plates 9, 10, so that it is possible to prevent the magnetic steel sheets laminated with each other in the axial direction of the rotor core 2 in order to make up the rotor core 2 from coming apart, thereby facilitating insertion of the permanent magnet 7 into each of the magnet-insertion hole 6.
Further, the end plates 9, 10 each are preferably made of a non-magnetic metal. With the use of the end plates 9, made of the non-magnetic metal, respectively, an amount of magnetic fluxes of the permanent magnet 7 to be shorted via the respective end plates 9, 10 will be reduced as compared with the case of the end plates made of a magnetic metal, so that reduction in the amount of effective magnetic fluxes can be prevented.
Further, as shown in
By so doing, when the permanent magnet 7 is broken, broken pieces of the permanent magnet 7 can be prevented from flying out of the magnet-insertion hole 11, so that long-term reliability can be provided.
Further, the non-magnetic material 12 with which each of the magnet-insertion holes 11 provided in the end plate 9 is filled up is preferably a resin material. This is because the resin material is inexpensive, and is easily worked on. Furthermore, because the resin material is lower in specific gravity than metal, centrifugal force can be lowered, so that strength of the end plate 9 can be enhanced. In
Next, there is described hereinafter a method for manufacturing the rotor 1 of the permanent magnet rotating electrical machine according to the invention with reference to
First, the rotor core 2 made up of the magnetic steel sheets laminated in the axial direction of the rotating shaft 3, together with the end plates 9, 10, is fixedly attached to the rotating shaft 3 by fitting in shrinkage fit, or by welding, and so forth, as shown in
With the present embodiment, as for a layout of the permanent magnets 7, there is adopted a V-shaped layout whereby two pieces of flat-plate magnets are disposed within one magnetic pole such that the opener to the outside diameter of the rotor 1 respective ends of the flat plate magnets are, the further away in distance from each other are the respective ends of the flat plate magnets, however, the number of the permanent magnets is not limited thereto, and there may be adopted other magnet layouts including a straight-line shaped layout (in a flat-plate-like state), a pair of the permanent magnets formed in a shape resembling an inverted letter V, as seen in cross section, such that the closer to the outside diameter of the rotor 1 respective ends of the flat plate magnets are, the closer in distance to each other are the respective ends of the flat plate magnets, and so forth, or use may be made of a permanent magnet formed in the shape of an arc, as seen in cross section. Further, as for the number of magnetic poles of the rotor 1, six magnetic poles are provided, however, needless to say, the invention can be similarly carried out even with the number of magnetic poles, other than that. Furthermore, the respective coils fitted in the stator are applied by distributed winding, and lap winding, however, a similar advantageous effect can be obtained by use of other winding method.
With the first embodiment described as above, there is described an example in which the permanent magnet is one body. However, for the permanent magnets to be inserted into the rotor core 2, use may be made of permanent magnets 14 formed by splitting the permanent magnet into a plurality of pieces, in the axial direction of the rotor core 2, as shown in
Splitting of a permanent magnet enables dimensions of each of split permanent magnets to be reduced, so that it becomes easier to manufacture the permanent magnet. Further, the splitting renders it possible to reduce eddy current occurring to the permanent magnets at the time of operation, so that eddy-current loss as well can be reduced, thereby rendering it possible to achieve high efficiency, and reduction in magnet temperature.
In
In
If the holes 21 are provided in the rotor core 22, as is the case with the present embodiment, this will render it possible to reduce mass of a rotor, and further, if similar holes are provided in each of the end plates 23, and the closing plate 24, respectively, this will permit a cooling wind to pass through the rotor via these holes, so that the rotor can be effectively cooled.
Thus, even though the permanent magnet rotating electrical machine according the fourth embodiment includes the axial duct 29, and the duct space 27, the same advantageous effect as described in the first to third embodiments, respectively, can be expected.
Further, in
Further, use may be made of a permanent magnet rotating electrical machine 33 of a cantilevered structure, in which a bearing 32 for supporting a rotating shaft 31 is provided only at one spot, as shown in
By providing the shaft arms 38 between the rotor core 36, and the rotating shaft 37, as is the case with the present embodiment, it is not only possible to secure strength equivalent to that in the case where the shaft arm 38 is not in use, but also possible to scale down the outside diameter of the rotating shaft 37, so that mass of the permanent magnet rotating electrical machine in whole can be reduced. With the present embodiment, the number of the shaft arms 38 is depicted as four lengths, however, the invention is not limited thereto in respect of the number of the shaft arms 38.
As shown in
The permanent magnet rotating electrical machine according to the invention has long-term reliability, and therefore, in the case of the hybrid-drive rail car system that have adopted the same, a rail car system as a whole can have a longer service life.
Further, it is also possible to provide a hybrid-drive rail car system capable of operating the permanent magnet rotating electrical machine 39 by use of the engine 40 without the battery chopper 43, and the battery 44, for the purpose of hybrid-driving, mounted therein, while operating by supplying the electric power system 41 with power generated by the permanent magnet rotating electrical machine 39.
As shown in
The permanent magnet rotating electrical machine according to the invention has long-term reliability, and therefore, in the case of the wind turbine system that has adopted the same, a wind system as a whole can have a longer service life. With the present embodiment, wind force is used as a power source, however, the invention is satisfactorily able to cope with the case of using, for example, a waterwheel, an engine, a turbine, and so forth as a power source.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010-273121 | Dec 2010 | JP | national |
