The present invention relates to a rotor for a rotary electric machine.
A structure of a conventional rotor core of a wound rotor having a rotor coil for a rotary electric machine is constructed by punching a silicon steel plate in a disc shape and laminating the disc-shaped plates.
However, since the punching die used to punch the steel plate is large in size in the case of a large-sized rotary electric machine, a rotor core is constructed, due to the above mentioned restriction in the manufacture of the rotor core, for example, as shown in FIG. 4, by punching a silicon steel plate in a sector shape, then arranging sector-shaped steel plates in a circle as shown in FIGS. 6(A) and 6(B), and laminating them.
In FIGS. 4, 5, 6(A) and 6(B), reference numeral 1 denotes a rotor core, symbol la denotes rotor core pieces made of a punched silicon steel plate, numeral 2 denotes slots to which a rotor coil is inserted, numeral 3 denotes a clamping bolt hole through which a clamping bolt is penetrated, numeral 4 denotes keyways for coupling the rotor core 1, for example, to a spider boss, numeral 5 denotes a ventilation duct for ventilating to cool the rotor, numeral 6 denotes a rotor coil, numeral 7 denotes a retainer for clamping the rotor core to integrate them by clamping the rotor core pieces la, numeral 8 denotes a ventilation fan for blowing cooling air to the stator, numeral 9 denotes a spider boss, and numeral 10 denotes a rotational shaft. The slots 2 are shown only in FIG. 4 for the simplification of the illustration.
Then, a method of manufacturing the conventional rotor will be described.
The rotor core 1 having a large diameter is generally formed by punching a thin silicon steel plate in a sector shape as shown in FIG. 4 to form rotor core pieces 1a. Then, the rotor core pieces 1a are stacked in a cylindrical shape while providing the ventilation duct 5 as shown in the sectional view of FIG. 5. In other words, a plurality of the rotor core pieces 1a are disposed horizontally to form one circular shape, and then the layers each formed of the one circular-shaped thin plates made of the rotor core pieces 1a are sequentially stacked upward similarly to the above. In the case of FIG. 4, 10 sheets of the core pieces 1a are disposed horizontally in one circular shape as one layer, and the layers thus formed are sequentially stacked upward. As described above, the rotor core pieces 1a thus stacked are clamped by penetrating the clamping bolts through the clamping bolt holes 3, and the rotor core 1 is constructed by providing the retainers 7 for clamping the rotor core at the upper and lower ends of the rotor core pieces 1a thus stacked, penetrating the clamping bolts therethrough, and clamping them with the clamping bolts in the axial direction.
The slots 2 for inserting the rotor coil 6 are formed at the outer periphery of the rotor core 1. After the rotor core 1 is constructed, the rotor coil 6 is inserted into the slots 2, and fixed in the slots 2 by inserting wedges to the outer peripheral ends of the slots 2.
A torque is transmitted between the spider boss 9 and the rotor core 1 through keys inserted into the keyways 4.
As described above, the rotor core pieces 1a are arranged horizontally in one circular shape, and the layers of the circular-shaped thin plates made of the rotor core pieces 1a are sequentially stacked. FIGS. 6(A) and 6(B) show the case where the rotor core pieces 1a are lap stacked at each 1/4 of one circle. More specifically, the rotor core pieces 1a shown in FIG. 4 are aligned in one circular shape on the outer periphery of the spider boss 9. In the case of the rotor core piece shown in FIG. 4, when ten sheets of the rotor core pieces 1a are aligned horizontally, they form one circular shape, and the split positions of the sectors are as designated by thick solid lines indicated by numeral 11 in FIG. 6(A).
When the second layer of the rotor core pieces 1a shown in FIG. 6(B) is so arranged in one circular shape that the split position is disposed at the position displaced by 1/4 of one sector from the split position 1 of the first layer of the rotor core pieces 1a, the split position of the second sector is disposed at the portion designated by a fine solid line indicated by numeral 12 in FIG. 6(A).
Similarly, when the third and fourth layers of the rotor core pieces 1a are stacked by displacing them by 1/4 of one sector from the split position, the split positions of the sectors are disposed at the positions designated by a broken line indicated by numeral 13 and a dotted broken line indicated by numeral 14, respectively.
The conventional rotor core 1 is constructed in the cylindrical structure by sequentially stacking the layers of the rotor core pieces 1a arranged horizontally in one circular shape as described above, providing the ventilation ducts 5 between several layers, and stacking the layers of the rotor core pieces 1a to a predetermined core length.
The rotor core 1 is constructed by stacking the layers of the rotor core pieces 1a, and then integrally clamping the stacked rotor core pieces through the retainers 7 disposed at the upper and lower ends thereof with the clamping bolts.
Since the conventional rotor core is constructed as described above, it is necessary to disassemble the rotor coil and to disassemble all the rotor core pieces after the rotor is assembled and tested for its factory test if the entire rotor cannot be transported as a unit due to limitations in transportation. Thus, it is also needed to reassemble the rotor coil and the rotor core pieces at a site after the disassembled rotor is transported to a place where the rotor is to be installed. Therefore, it takes a long time to disassemble the rotor in the factory, to transport the disassembled rotor and to reassemble the rotor, and there may be a problem in reliability of the performance of the reassembled rotor. It is an object of this invention to overcome this problem.