Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
1999-10-18
2001-07-24
Mullins, Burton S. (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S214000, C310S216006, C310S216055, C310S061000
Reexamination Certificate
active
06265805
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to the field of synchronous electric machines and more particularly relates to a shaft for the rotor of a synchronous electric machine.
BACKGROUND
Such a shaft has two end parts and an electrically active central part with conductors, all produced by machining of a single piece.
The end parts are intended to be placed on two bearings and have an appropriate shape.
In the active central part which forms the rotor of the machine, grooves and deep notches are machined for the electrical conductors. These are coils which must be insulated and maintained in the notches by wedges. This constitutes a difference in construction between synchronous machines and asynchronous machines, in which the conductors are generally conductive bars which do not require insulation or immobilization.
Thus, the costs and time periods for manufacturing shafts for the rotors of synchronous machines are currently high. They constitute a limitation in the manufacturing of electric machines.
It has appeared to be necessary to modify the structure of the rotor shafts of synchronous machines as well as their manufacturing process in order to significantly reduce cost and time of manufacturing.
SUMMARY OF THE INVENTION
For this, the active part of the shaft is made up of a stack of metal sheets, which is maintained rigid by rods, and the metal sheets have a number of radial notches for the conductors.
Preferably, the stack is placed between two end plates, and the rods are welded on said plates.
The following characteristics can also be taken into consideration alone or in any of their technically possible combinations:
the diameter of the stack is roughly identical to that of the end plates;
each of the end plates has, on its internal surface, a recess, the stack of metal sheets being fit by each of its ends into the recesses;
the notches of each metal sheet extend towards the exterior edge of the metal sheet by a hole for the passage of the rods, these rods ensuring the immobilization of the conductors in the notches and the closing of the latter;
the rods passing through the holes which extend the notches are made of non-magnetic material;
each metal sheet has at least two zones which are devoid of notches but which have holes for the passage of the rods which preferably open on the exterior edge of the metal sheet;
the rods passing through the holes of said zones which are devoid of notches are made of magnetic material;
the metal sheets are glued together in order to improve the strength with regard to twisting of the stack;
the stack of metal sheets has cooling channels which extend, if necessary, into the end plates;
the cooling channels communicate, through the intermediary of channels made in the conductors, with ventilation ducts provided on the periphery of the stack;
the notches of each metal sheet extend, on the opposite side from the exterior edge of the metal sheet, by an opening corresponding to a cooling channel;
the holes for the rods house a free space between the metal sheet and the rods, when they are in position, so as to create ventilation ducts.
The invention also relates to a process for manufacturing of a rotor shaft of a synchronous electric machine having two end parts framing an electrically active central part and having conductors, the process consisting of machining the two end parts, of producing the central part, and of connecting the three parts together.
According to the invention, the central part is produced by the following successive steps:
manufacturing of metal sheets which have notches for the conductors and holes for the rods,
pre-gluing of said metal sheets,
stacking of said metal sheets,
insertion of the stack between two end plates,
insertion of the rods,
putting the rods in tension,
welding of the rods on the end plates,
insertion of the conductors in the notches of the stack, and
connection of the conductors.
Advantageously, the notches and the holes are formed in the metal sheets by cutting out, particularly by means of a laser beam, since the metal sheets are thin.
REFERENCES:
patent: 3870912 (1975-03-01), Kipke et al.
patent: 4562641 (1986-01-01), Mosher et al.
patent: 4739207 (1988-04-01), Ying et al.
patent: 5893205 (1999-04-01), McClelland
patent: 603312 (1934-09-01), None
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patent: 0509119 (1992-10-01), None
patent: 0609645 (1993-02-01), None
patent: 2116827 (1972-06-01), None
patent: 2166090 (1973-08-01), None
patent: 364027 (1930-09-01), None
patent: 523311 (1938-12-01), None
Jeumont Industrie
Leydig , Voit & Mayer, Ltd.
Mullins Burton S.
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