Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2000-08-21
2002-10-01
Nguyen, Tran (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S201000, C174S015600, C174S016200
Reexamination Certificate
active
06459180
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a rotary power generator such as an electric power generator. In particular, the present invention relates to a cooling structure of a gas direct cooling type of rotary electric power generator having a large capacity.
An electric power generator, in particular, a turbine electric power generator has a plurality of rotor windings or winding slots formed in an axial direction in which the windings are disposed. These winding slots are disposed with intervals on a peripheral face of a rotor main body at both sides of a magnetic pole part of the rotor main body, and a plurality of windings configuring the same magnetic poles are disposed coaxially around the magnetic poles. These windings are formed by superimposing a winding conductor by a plurality of turns in a radial direction, and insulation layers are provided between the turns. When electric power is supplied from the outside to these windings, a required electromagnetic field is generated at a respective one of the magnetic poles. The windings are rigidly fixed to the inside of the winding slots by means of wedges in the rotor so as not to be flied in the winding outer diameter direction by a strong centrifugal acceleration caused by rotation of the rotor. In addition, the windings are fixed by a cylindrical retaining ring provided so as to be in contact with the winding peripheral part.
The winding conductor is Joule-heated by supplying electric power to the windings. The insulation layers of the windings use a material having its high heat resistance such as mica; however, the limit of the allowable temperature of the insulation is 130° C. (B type of insulation material) or 155° C. (F type of insulation material). In addition, heat expansion of the winding conductor due to a temperature rise imparts large distortion to the windings and rotor, and causes rotational vibration. For this reason, as described in JP-A-9-285052 specification, a structure called a radial flow cooling system has been adopted to cool the windings by cooling fluid so as not to increase the winding temperature. In this structure, a sub-slot that is a ventilation flow passage from an end of the windings is provided at the bottom of the winding slot, and a number of flow passages are provided in a radial direction while electrical insulation between the turns is maintained. A hole is provided at a wedge so that this flow passage communicates with the rotor outer diameter side. When occasion demands, an axial flow cooling flow passage having a cooling flow passage provided in the longitudinal direction of the conductor may be combined with a radial flow passage. In this manner, the cooling fluid can be supplied from the sub-slot to the cooling flow passage formed at the rotor windings, and the winding temperature can be restricted to a predetermined temperature or less by forcibly cooling the rotor windings. Air or hydrogen is generally employed for the cooling fluid. Any fluid other than these can be principally used, but these two gases are frequently employed in view of safety or easiness of handling.
However, in the above prior art, there has been a problem that a divergent ventilation resistance caused when the cooling fluid diverges from the sub-slot in each radial flow passage is non-uniform at the axial position of each sub-slot, thus causing non-uniformity at air distribution and causing non-uniformity at the axial position of the rotor. Therefore, in recent years, with an increase in heat load due to compactness of electric power generators, the temperature of the entire rotor windings increases, and a margin for the temperature limit is reduced. For this reason, it is required to provide means for providing a temperature rise at this part while the winding strength of the slot end is fully maintained. However, conventionally, there is no consideration of means for solving this problem, and there has been only one way to achieve a large capacity by means for educing an output per electric power generator volume, that is, increasing the size of the electric power generator and reducing a heat load in order to ensure the output.
The cooling fluid is changed from air to hydrogen, thereby the temperature of the rotor windings can be satisfactorily reduced even in the conventional structure. However, the entire electric power generator must be structured to be fully closed, thus requiring special technique for a sealing structure. In addition, in air cooling, a peripheral device for managing the purity of hydrogen is also required. Thus, there is a disadvantage that the entire cost of the electric power generator plant is increased. Further, there has been a problem that hydrogen is a gas with its extremely high explosiveness, and extreme care must be taken in flammable environment including a turbine.
As described above, there has been a problem that, although the above prior art can cope with a large capacity of electric power generator, a unit price per electric power output cannot be reduced.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a rotary electric power generator with its high reliability at a low cost for an air cooling mechanism y improving a cooling performance of the rotary electric power generator without increasing its manufacturing cost.
In order to attain the foregoing object, according to the present invention, there is provided a structure of a rotary electric power generator comprising: a rotor; axial winding slots on the peripheral face of the rotor disposed with intervals in the circumferential direction at both sides of the magnetic pole parts of the rotor; sub-slots opening at the bottom of the winding slots; rotor windings arranged coaxially with respect to the magnetic pole, extending at and outside of the winding slots, and having conductor insulation materials laminated alternately thereon; wedges in which the rotor windings are fixed to the rotor in the winding slots; a retaining ring on the rotary shaft peripheral side of the rotary windings extending outside of the winding slots at both ends of the rotor; and insulation blocks interposed between wedges or retaining rings, wherein the rotor windings have a number of radial ventilation flow passages passing from the sub-slots to the insulation blocks and wedges, and a projection or rib is provided at the inner face of the radial flow passage.
There is provided another configuration in which a flow passage area for the radial flow passage is changed with a predetermined pitch, and a ratio of the maximum area to the minimum area is 2 or less.
There is provided a still another configuration in which a projection is provided at the inner face of a hole configuring the radial flow passage of the above conductor.
Further, there is provided a further configuration in which the longitudinal flow passage having a protrusive projection is provided with respect to the flow direction of the cooling fluid.
Furthermore, there is provided a still further configuration in which a protrusive projection having a V shaped tip end is provided with respect to the upstream direction of the cooling fluid of the conductor longitudinal flow passage.
REFERENCES:
patent: 2755395 (1956-07-01), Kilner
patent: 5685063 (1997-11-01), Prole et al.
patent: 5886434 (1999-03-01), Nygard
Hattori Ken-ichi
Kaiho Masayuki
Kieda Shigekazu
Mori Hideaki
Shiobara Ryoichi
Antonelli Terry Stout & Kraus LLP
Hitachi , Ltd.
Nguyen Tran
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