Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1991-09-20
1993-07-20
Stephan, Steven L.
Electrical generator or motor structure
Dynamoelectric
Rotary
310 90, 384559, H02K 1600, H02K 516
Patent
active
052296768
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to an electric machine, comprising two or more rotors arranged coaxially on a common shaft at a distance from each other, each of which is disposed inside a respective stator, a ball or roller or magnetic bearing being disposed between each two adjacent rotors in order to support the rotary parts relative to the stationary part of the machine, both rotors and stators being excitable simultaneously or in succession.
BACKGROUND OF THE INVENTION
Such a machine is in fact known in practice, for instance from U.S. Pat. No. 1,654,774. In that case, for example, a number of electric motors are, as it were, connected in series.
The use of a number of smaller motors or generators instead of one large motor has many advantages.
By, for example, starting the motors after one another, the very high starting currents used in large motors, which would require a very large transformer and generator, are avoided.
Moreover, smaller motors can be supplied as standard models and are therefore much cheaper than a specially manufactured larger motor.
The machine made up of several motors or generators also takes up much less space than one large machine.
The rotors of the various machines are in practice fixed by means of hollow shafts or the like on the common shaft, in order to permit fitting and removal.
Ball or roller bearings are provided between the rotors. Although these currently have a long service life, they still have a limited one. The use of hollow shafts means that it is possible to remove them after wear and replace them with new bearings. The design with hollow shafts is, however, complex.
SUMMARY OF THE INVENTION
The electric machine according to the invention is characterized in that the inner ring of each bearing is fixed on a respective shaft bush which can be slid along the shaft during repairs and which can be fixed relative to the shaft, and in that one or more bearings for use as spares are located on each, shaft bush.
Although roller bearings made up of two halves do exist, they cannot be used here, on account of the very limited maximum speeds of rotation permitted for them, which do not correspond to those of electric motors and generators.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be explained in greater detail with reference to the sole drawing, in which a longitudinal section through an electric machine according to the invention, in particular a motor, is shown, said machine being made up of three smaller machines.
DETAILED DESCRIPTION OF THE INVENTION
The common shaft, consisting of one piece, is indicated by 1, the specially manufactured intermediate cover by 2, the stators by 3, the rotors by 4, said rotors being shrunk on the shaft 1, the shaft bush by 5, the working ball bearing by 6, one of the spare bearings by 7, the bearing housing by 8, the end bearing cover by 9, the cooling air fan by 10, the stator housing by 11, and one of the cooling fins by 12.
After the first rotor 4 has been pressed onto the shaft 1, a shaft bush 5 is slid over the shaft 1 with two or more ball bearings on it.
This thus slidable shaft bush 5 is retained on the shaft 1 by means of an adjusting screw 13 or the like in such a way that one of the bearings on the outer ring is enclosed by the non-rotating housing part.
Only then is the next rotor pressed onto the shaft, and so on.
When in due course the above-mentioned ball bearing is ready for replacement, the shaft bush 5 with the other not yet loaded, spare, bearings on it is slid along the shaft to the position previously occupied by the worn bearing. The latter then remains sitting uselessly on the shaft bush, but cannot cause any further harm.
It is theoretically possible to calculate the service life of a ball bearing, but the wear phenomens are generally noticeable from an increasingly loud hum. In this way, the bearings can be slid along in time.
An electric machine according to the invention can be made up of standard parts (see, for example, IEC Standards DIN 42673/42677). No special meas
REFERENCES:
patent: 1654774 (1928-01-01), Arutunoff
patent: 3407680 (1968-10-01), Westmoreland
patent: 3917363 (1975-11-01), Korting
patent: 4425010 (1984-01-01), Bryant et al.
patent: 4690574 (1987-09-01), Green
patent: 5040907 (1991-08-01), Harvey
2 pages of International Search Report (Jul. 1990).
Stephan Steven L.
To Ed
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