Motor counter weight attachment

Details Motor counter weight attachment Motor counter weight attachment

2000-06-15

2001-09-18

Mullins, Burton S. (Department: 2834)

Electrical generator or motor structure

Dynamoelectric

Rotary

C310S051000, C074S573110, C073S468000

Reexamination Certificate

active

06291920

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to counter weights for electric motors, specifically rotor and shaft counter weights and how they are attached to electric motor rotors and shafts.
BACKGROUND OF THE INVENTION
In prior art methods of attaching a counter weight to a rotor of an electric motor, the counter weight can be either installed in a receptacle in the rotor end ring, or mechanically attached to the end ring. A shaft counter weight is typically mechanically attached to the motor shaft in a spaced-apart relation from the rotor by heating the counter weight and placing it over a cold rotor shaft. When the shaft counter weight cools, a pressure bond is formed between the shaft counter weight and the rotor shaft, thus yielding a rotor in which the shaft counter weight is mechanically attached to the rotor shaft.
SUMMARY OF THE INVENTION
Using such a prior art method of attaching a counter weight to a rotor and a rotor shaft, the counter weights may loosen upon starting and stopping the motor. In addition, such an arrangement occupies valuable space between the motor and whatever mechanics the motor is driving, requiring a longer, more expensive shaft.
The invention provides a counter weight attachment in which the rotor counter weight and the shaft counter weight interlock to form a more solid unit that occupies less space.
The invention provides a counter weight system for an electric motor having a rotor with an end ring, the end ring having an outer surface, and at least one deformable lug extending axially from and a plurality of projections extending radially across the outer surface. The counter weight system includes a rotor counter weight having an inner surface abutting the end ring end surface; an outer surface opposite the inner surface; at least one bore through the rotor counter weight and receiving a lug, the lug being deformed to axially fix the rotor counter weight; a plurality of recesses in the inner surface, each recess receiving an end ring projection so as to prevent rotational movement of the rotor counter weight with respect to the end ring; and a plurality of rotor counter weight projections extending radially across the outer surface. The counter weight system also includes a generally circular shad counter weight having an inner surface abutting the rotor counter weight outer surface, and a plurality of recesses in the shaft counter weight inner surface, each recess receiving a respective a rotor counter weight projection so as to prevent rotational movement of the shaft counter weight with respect to the rotor counter weight.
The invention solves both the rigidity and space problems by allowing for interaction between the rotor and shaft counter weights and the use of a shorter shaft. As a result, the rotor and thus the motor experience fewer vibration problems. In addition, the amount of shaft material needed is also reduced because the shaft counter weight requires less space between the motor and the mechanics being driven.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings.


REFERENCES:
patent: 4642886 (1987-02-01), Muck et al.
patent: 4893044 (1990-01-01), Bush et al.
patent: 4933583 (1990-06-01), Ripplinger
patent: 5373208 (1994-12-01), Ichimura et al.
patent: 5386163 (1995-01-01), Heilman
patent: 5831358 (1998-11-01), Bobay
patent: 57-83146 (1982-05-01), None

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