Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
1999-08-12
2001-04-10
Nguyen, Tran (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S058000, C310S06000A, C310S061000, C310S062000, C310S063000
Reexamination Certificate
active
06215212
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to dynamoelectric machines, and more particularly, to a shaftless rotor construction for use in such machines.
BACKGROUND OF THE INVENTION
Dynamoelectric machines come in widely varying shapes, sizes and capacities. Some are employed as motors while others are employed as generators. And some are employed as combination motors-generators, meaning that they can be operated either as a motor or as a generator, depending upon exactly what function is desired of the machine at a given point in time.
In some cases, volume and weight constraints are minimal, while in others they are critical. For example, in aerospace applications, weight is always a concern. Volume constraints are also a concern lest the machine occupy too much space on an aircraft or even contribute to a less efficient aerodynamic shape as a result of its bulk.
Most such machines have a shafted rotor which is to say that a single shaft extends through the rotor body to journal the same for rotation about an axis within a stator. This is, however, not always desirable. For example, in some machines, the presence of a shaft extending through the rotor body may interfere with the magnetic flux path of the machine and thus contribute to magnetic inefficiency which in turn may lower the capacity of a machine having a given size. This is particularly true in dynamoelectric machines having a relatively small number of poles on the rotor. In such cases, it may be desirable to provide a shaftless rotor. See, for example, commonly assigned U.S. Pat. No. 4,562,641 issued Jan. 7, 1986 to Mosher et al. In other cases, the presence of a single shaft may contribute to weight and/or dictate enlargement of the rotor for a given application in that rotor components cannot be located in the area of the rotor occupied by the shaft. This in turn requires that such components be located elsewhere in the rotor which may increase its size in order to house the components and/or may decrease magnetic efficiency as a result of locating such components radially outward of the shaft. In such cases it would be desirable to provide a shaftless rotor for the purpose of reducing weight and/or allowing the part of the rotor that would otherwise be occupied by the shaft to be used for housing other rotor components to thereby reduce overall rotor size. It would also be desirable from the standpoint of reducing the mass of the rotating components of the dynamoelectric machine to enhance the ability of the dynamoelectric machine to operate at high speed.
The present invention is directed to providing such a shaftless rotor for a dynamoelectric machine.
SUMMARY OF THE INVENTION
It is the principal object of the invention to provide a new and improved shaftless rotor for use in a dynamoelectric machine. It is also an object of the invention to provide a dynamoelectric machine having a new and improved shaftless rotor.
The invention, according to an exemplary embodiment and one feature thereof, achieves the foregoing object in a shaftless rotor that includes a stack of ferrous laminations. A central opening extends through the stack and is adapted to be located on an axis of rotation for the rotor. A sleeve extends through the stack through the central opening and orients the laminations with respect to one another. Clamping pieces are disposed on opposite ends of the stack and engage the end most laminations in the stack and the sleeve. A pair of spaced shaft elements, one at each end of the stack, are provided to engage respective ones of the clamp pieces. The shaft segments are located on the rotational axis of the rotor. A single tie bolt extends through the sleeve between the shaft segments and interconnects the same. The tie bolt is in tension to apply clamping force to the shaft segments for transmittal through the clamp pieces to the laminations in the stack.
In one embodiment of the invention, the sleeve is cylindrical and includes an inner diameter substantially larger than the tie bolt so that an annular coolant passage exists between the sleeve inner diameter and the tie bolt and which extends from end to end of the lamination stack.
Preferably, the clamping pieces include fluid passages in fluid communication with the annular coolant passage.
In a preferred embodiment, the fluid passages include vanes for pumping coolant from the annular coolant passage to both ends of the stack.
In one embodiment of the invention, the tie bolt is enlarged and includes a chamber. The chamber has an inlet end adapted to be in fluid communication with a source of coolant and openings are located in the tie bolt to extend from the chamber to the exterior of the tie bolt for establishing fluid communication between the inlet end and the annular coolant passage.
In a highly preferred embodiment, the tie bolt has a reduced diameter central section that is connected to the enlarged end by a frusto-conical section. The openings are located in the frusto-conical section.
According to another facet of the invention, a shaftless rotor for a dynamoelectric machine is provided and includes a stack of ferrous laminations having opposed ends. Means are provided to align the laminations in the stack to define a rotor body. A central opening extends through the stack and has a first size. A tie bolt, having a central section extending through the central opening is provided. The tie bolt central section has a second size less than the first size to define an annular coolant passage between the tie bolt central section and the central opening. The rotor includes a pair of spaced shaft segments, one at each end of the opposed ends of the stack which are interconnected by the tie bolt. The tie bolt is in tension to provide a clamping force for the shaft segments for transmission to the opposed ends of the stack to clamp the laminations in the stack in assembled relation.
A preferred embodiment envisions a dynamoelectric machine including a stator having a rotor receiving opening and a rotor construction such as set forth above disposed in the rotor receiving opening. Means are provided for journalling the shaft segments to journal the rotor within the stator.
Other objects and advantages will become apparent from the following specification taken in connection with the accompanying drawings.
REFERENCES:
patent: 1193897 (1916-08-01), Holbech
patent: 1577303 (1926-03-01), Schurch
patent: 1877904 (1932-09-01), Laffoon
patent: 3716732 (1973-02-01), Tillma
patent: 3737988 (1973-06-01), Bednarski
patent: 3867655 (1975-02-01), Stengel et al.
patent: 3882336 (1975-05-01), Boyd et al.
patent: 3932778 (1976-01-01), Watanbe
patent: 4286183 (1981-08-01), Montgomery
patent: 4383191 (1983-05-01), Mizuyama et al.
patent: 4469970 (1984-09-01), Neumann
patent: 4614888 (1986-09-01), Mosher et al.
patent: 4864176 (1989-09-01), Miller et al.
patent: 5086246 (1992-02-01), Dymond et al.
patent: 5703421 (1997-12-01), Durkin
patent: 5898246 (1999-04-01), Hoffman
patent: 5994804 (1999-11-01), Grennan et al.
Greenlee William
Grennan Robert
Halsey David
Smith W. Glen
Hamilton Sundstrand Corporation
Nguyen Tran
Wood Phillips VanSanten Clark & Mortimer
LandOfFree
Shaftless rotor construction does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Shaftless rotor construction, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Shaftless rotor construction will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2537037