Improvements in Electric Motors or Generators.
Year: 1891

page_text: Date of Application, 26th Nov., 1891-Accepted, 2nd Jan., 1892
COMPLETE SPECIFICATION.
[Communicated from abroad by WILLIAM STANLEY, Jr., of Pittsfield, in the
County of Berkshire and State of Massachusetts, and JOHN FOREST KELLY,
of 325, East 17th Street, New York, both in the United States of America,
Electricians.]
Improvements in Electric Motors or Generators.
I, HENRY HARRIS LAKE, of the firm of Haseltine Lake & Co., Patent
Agents, 45 Southampton Buildings in the County of Middlesex, do hereby
declare the nature of this invention and in what manner the same is to he
performed to be particularly described and ascertained in and by the following
statement :-
This invention relates mainly to electromagnetic motors designed or adapted to
be operated by alternating currents. The special form of motor contemplated as
within the limits of the applicability of the invention may be very widely varied,
but for purposes of illustration the invention will be described as applied to any
ordinary type of motor having a commutator and armature winding similar to
those existing in continuous current generators and motors, and a field magnet,
(which should be laminated or magnetically subdivided) energized by coils in series
with or in derivation to the armature circuit.
If an alternating current be caused to flow through the armature coils of such a
motor, it will, as is well understood, be subject to a given retardation due to the
self-induction of the armature. In fact it has been found that this retardation may
be and generally is sufficient to very seriously impair the efficiency of the machine.
It may be corrected or neutralized in its effects and the trouble due thereto avoided
by the employment in the circuit of a condenser of suitable capacity, but when the
whole of the energy to be transmitted must pass through the condenser, the latter
becomes a large and costly adjunct and the apparatus as a whole, becomes less
available for general service.
It will be understood, that if on the armature a second winding were applied,
symmetrical with the first, but in which the current passes in a direction opposite
to that of the current in the first, that no self-induction and, in consequence no lag
would result.
With both windings attached to the armature core, however, no effective torque
would be developed, as it will readily be seen that each winding or coil would be
impelled in an opposite direction.
If, however, one only of such windings be made fast to the revolving armature
core, while the other is fixed in space, the maximum torque is secured, while the
self-induction is reduced to a minimum, since the two windings, as before, will
neutralize one another, so far as self-induction is concerned while the stress due to
the field will be transmitted from but one of them to the core.
It is not necessary that the two windings should be exactly alike, if only the
magnetizing effects shall be equal and opposite. Nor is it, in general essential
that the two coils have a direct electrical connection with one another, as substan
tially the saine results will be obtained if the stationary coil or winding be closed
upon itself, in which case being acted upon inductively by the moving coils, the
mutual induction will practically neutralize the self-induction.
The invention, therefore, consists in the combination in a machine of the kind
described, with the rotating armature and coil or coils thereon, of a stationary coil
or coils adapted to produce an effect equal but opposite to that of the coil carried
by the armature whereby the self-induction and consequent retardation in the
armature will be neutralized or overcome.

page_text: The plan or means by which the invention is carried into practice 15 illustrated
in the accompanying drawings in which
Figure 1 is an end view of a motor embodying the invention.
Figure 2 is a perspective view of an armature exhibiting diagrammatically the
special winding which the invention involves.
Figure 3 is an end view of a multipolar field magnet with the improvements
applied to the same.
In Figure 1, A, A, represent the field core of any ordinary motor; B, B,
the polar projection between which the armature is mounted, and C, C, the
energizing field coils surrounding such polar projections.
D is the armature core, E the coils wound thereon and F is the usual com-
mutator.
G designates the stationary coil. This coil is wound in convolutions parallel
to those on the armature which are conveniently contained in recesses or grooves H
cut or formed in the faces of the pole pieces.
The relations of the two armature coils is better illustrated in Figure 2. The
armature D in this case is wound in the usual way with a conductor laid parallel
with its axis in coils connected with the segments of the commutator F. The
line of commutation is shown by the position of the brushes L, L and the
stationary coil G is shown as surrounding the armature, its convolutions being
in planes at right angles to the line of commutation.
In Figure I the electrical connections are as follows:
In
The current enters at a binding post P, from which it flows through the
field magnet coils, then through the armature coils, and then through the
stationary coils to the binding post S, the three coils named being in series.
Figure 2 however, the terminals of the stationary coil are shown as connected
together, the coil being thus in closed circuit.
In Figure 3 the field core is provided with a number of pole pieces, being
in fact a type of multipolar machine. The stationary coils, in this case, are
wound in grooves in adjacent pole pieces so as to produce an opposite_magnetizing
effect upon, or in the armature, to that of the armature coils. For example,
if the tendency of an armature coil is to produce a north pole in its core at
any given point as N, the corresponding stationary coil will have an equal
tendency to set up at the same point an opposite pole. So in general where
the armature coils act to establish poles N, S, the stationary coils neutralize
such action by establishing poles S', N, as indicated in the diagram.
The stationary coils G, it will be observed, do not sensibly affect the magnetic
conditions of the field, owing to their position relatively thereto, but their magnetizing
influence is manifested in the armature core, where it opposes that of the armature
coils.
In practice, the conductors of the supplemental or stationary coil or coils will be
bent aside at one or both ends of the armature to permit the latter to be introduced
in or withdrawn from the field magnets, as is indicated in Figure 1.
This invention is more particularly applicable to and useful with motors, but it
may be used to advantage when the machine is run as a generator, as where several
machines are coupled together, for the purpose of preventing one machine from
lagging behind another and more quickly correcting any tendency to displacement
of currents in such machines.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me by my
foreign correspondents, I declare that what I claim is :-
First. In an alternating current motor, the combination with the field, an
armature mounted to rotate therein, and a commutator the segments of which are
connected with the armature coil or coils, of a stationary coil adapted by its
position and direction of its winding to oppose the magnetizing effect of the

page_text: armature coil or coils and thereby neutralize the self-induction of the same, as set
forth.
Second. In an alternating current motor, the combination with a rotating
armature, and a commutator to which the armature coils are connected, of a
stationary coil or coils surrounding the armature in convolutions parallel to those of
the armature coils, and connected with the same in such manner that currents passing
in the stationary and rotating coils respectively will be of opposite direction, as set
forth.
Third. The combination, with the armature, of an alternating current motor
having a commutator to which the coils wound on the armature are connected, of a
stationary coil closed upon itself and having its conductors or convolutions substan-
tially parallel to those of the armature coil, whereby the self-induction of the
armature will be neutralized, as set forth.
Fourth. The combination with a field magnet having polar projections, of an
armature and coils wound thereon, a commutator to the segments of which said coils
are connected, and a stationary coil or coils wound parallel with the armature coils
in grooves cut or formed in the faces of the polar projections, as set forth,
nudili Deth 1 f Namamba 1001
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.