Improvements in and relating to Dynamo-electric Machines.
Year: 1888

page_text: Date of Application, 2nd Oct., 1888
Specification Accepted, 2nd Nov., 1888
RES
[Communicated from abroad by Professor ELITU THOMSON, of Lynn, Massachusetts,
United States of America.]
Improvements in and relating to Dynamo-electric Machines.
I, HENRY HARRIS LAKE, of the firm of Haseltine, Lake & Co., Patent Agents,
Southampton Buildings, in the County of Middlesex, do hereby declare the nature of
this invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:—
This invention relates to dynamo-electric machines organized to deliver alternating
or to-and-fro currents. The currents produced by my machine may be used for any
of the ordinary purposes, such, for instance, as supplying alternating currents to the
primary circuits of converters or induction coils, or for any other purpose.
The invention relates more particularly to alternating current generators of the
kind in which two sets of armature coils are employed one of which is connected
directly to the external circuit which is designed to furnish the alternating currents,
the other supplying the current by which the magnetic field of the machine is
maintained.
The object of the invention is to produce a simple and easily controlled machine
capable of generating alternating currents of high or low potential, as may be needed,
and which potential may be controlled so as to be raised or lowered or kept constant
by manual or other devices.
The invention consists in the novel manner of combining the two sets of armature
coils on the armature structure, one set being the field maintaining and the other the
working current or line set.
The said invention consists also in the special manner of constructing and
proportioning the armature and armature circuits so as to permit a regulation of the
machine to be readily obtained without destructive effects upon the commutator.
The invention further consists in details of construction and improved combinations
which will be hereinafter more particularly described.

page_text: In the accompanying drawings:
Figure 1 is an end elevation of a machine embodying the invention
Figure 2 is a side elevation of the machine and its collecting and commuting
arrangements.
Figure 3 is a transverse section of the armature body.
Figure 4 is an end view of the armature unwound.
Figure 5 is a side view of the armature unwound.
Figure 6 is a diagram showing the mode of application of the coils to the armature
body.
Figure 7 is a diagram showing one of the line feeding coils of the armature
detached.
Figure 8 is an edgewise view of the coil Figure 7.
Figure 9 is a view showing the preferred relations in the position of the field
exciting coil, and the line coils on the armature coil.
Figure 10 is a diagram of the connections of the exciting coil to its commutator
and to the field magnet coil.
Figure 11 shows a section of the commutator of the exciting coil Figure 10.
Figure 12 is a diagram showing the relation of the main circuit or line feeding
coils to the collecting rings and external circuit.
Referring to Figure 1, F, indicates a field magnet formed of a circular or polygonal
magnet from the interior of which field magnet cores project inwardly towards the
rotating armature. These field magnet cores terminate at the periphery of a circle
a little larger than the diameter of the revolving armature, which latter is mounted
on a shaft in the centre in any suitable manner, as is well understood in the art.
The armature A is wound with an exciting coil and a set of line feeding coils C,
for supplying alternating currents to the work external to the machine. The exciting
coil alone is provided with a commutator K, for commuting its currents to a current
of one direction, and passing them outward into a circuit 2, 3, 4, which circuit
includes the commutator brushes of the commutator, a variable rheostat or resistance V,
of any character, and the field magnet coils M, which latter are connected either in
series or in series multiple, or in multiple arc according to the size of tho wire forming
the coils.
Suitable standards S, carried by the base plate of the machine, are provided for
supporting the armature shaft and permitting its rapid revolution between the pole
faces of the field magnet cores. The polarity of the faces, as is usual in such
machines, is alternating, that is to say, the poles are alternately north and south
proceeding in regular rotation.
In Figure 2 P2, indicates a pulley on the driving shaft X, by which power is
applied to rotate the armature shaft.
A indicates the armature complete with coils C, C, C, C, on the exterior of the
armature corresponding in number and position to the number and position of the
field magnet coils.
Bands of wire encircle the armature as indicated at B, B, B, B, and hold the coils
in place thereon.
•
The coils C, C, C, C, which are shown as six in number in figure 3, three only
being visible in figure 2, are supposed to be connected in one circuit so that their
potentials are added one to the other in producing alternating electric waves, or
pulsations, though when wound suitably they may be connected partly in series and
partly multiple, or entirely in multiple according to the purpose designed. In any
case the terminals of the winding are carried to carefully insulated rings R, R, which
form the poles of the machine and to which are applied, in the manner usual in the
art, collecting brushes, from which brushes conductors are carried to the external
circuit.
The exciting coil E, Figures 1 and 2, is wound over the body of the armaturo and
its two terminals are connected to the segments of the commutator K, which seginents
are insulated from one another. In the case in question the commutator K contains
six segments, there being six alternations of current in the coil during a revolution,

page_text: and every other segment is attached to one terminal of the exciting coil E, and the
remaining alternate segments to the remaining terminal of the exciting coil E, after
the well known principle.
The positions and relations of the windings will be better understood by reference
to succeeding figures.
In Figure 3, the armature is shown in cross section. The wires C, C, on the
exterior are those of the coils which feed the main circuit and those at E, E, passing
longitudinally along the armature and over its ends are those of the exciting coil for
furnishing the current which, when commuted, energizes the field magnets of the
machine.
The armature itself is built up, by preference, of thin sheets or discs of iron piled
laterally and encircling the shaft of the machine, and carried by or attached to said
shaft by any suitable means, as by keying or otherwise.
An end view of the armature body unwound is seen in Figure 4. The end plates
of the sheet metal portion constituting the mass of the armature consist of thicker
iron plates, preferably ribbed, as shown in both Figures 4 and 5. These plates are
marked P, P, and serve to support the ends of the armature core.
It is preferred
also to mount upon the ends of the armature rings G, G, of thin metal, such as cast
iron, brass or German silver, separated by a small space from the main body of the
core and mounted on pins or projecting screws, as shown. Wooden rings not
separated may also suffice.
The object of the rings G, G, is to furnish guides which shall assist in holding the
external coils C, C, C, C, or which assist in providing a seat for the ends of the
externally placed coils C, C, C, C.
In the laminated or sheet iron body of the armature are placed at suitable intervals,
small projections or pins of steel or other tough and strong material. It is preferred
to use steel, however, on account of its strength, and also on account of its magnetic
power. These pins are shown in Figure 5, at p, p, arranged in pairs around the
periphery of the armature. They are used as shown in Figure 6, to hold in place
pieces of wood or fibre W, W, which fit over the pius and steady or support the
coils C, C, as shown in dotted lines in the said figure. They also furnish the means
of preventing the said coil from slipping around the armature.
The pieces W, W, are made to fit the interior of the coil as wound. The
coils C, C, are preferably wound on a mold and are flat, almost rectangular coils, as
seen in Figures 7 and 8. They may be wound flat and afterwards bent to fit the
exterior of the armature surface. They are laid on the exterior with the pieces W, W,
and the whole is then insulated carefully and well bound with a strong binding of
German silver wire. The coils are thus secured from displacement during revolution,
either longitudinally or peripherally.
When the exciting coil E is used as described it is preferably wound over the
armature body longitudinally as seen in Figure 9, and through the space existing in
the centre of the coils C, C, (one only of which is seen in Figure 9). In this case
the pieces W, W, and pins corresponding thereto are omitted at the positions in which
the coil E passes over the periphery longitudinally.
An important point in connection with the coil E is that it is made of a very few
turns of wire, so that the currents generated in it are of quite low potential. I make
the turns so few that the potential of the currents of the generating coil E shall be
below that which would sustain an arc between metal pieces separated a very small
interval, and by this means secure in the commutator used to commute or change
the direction of the currents developed in E for supplying the field, a remarkable
freedom from sparking, burning or other irregularities, even though the brushes be
displaced from their proper positions for commuting the entire current. This is an
important feature in the construction of the machine. Otherwise, with high potentials,
such as surpass 40 or 50 volts, developed in the exciting coil E, considerable difficulty
will be found in keeping the commutator K, adjusted so as to be free from sparking,
and if so adjusted, in preventing sparking on slight changes of position.
The position of the exciting coil E also conduces to the control of the machine..

page_text: since it possesses a considerable length of inactive wire besides the active portion
which traverses the space in front of the field poles. This inactive wire is found in
the portion of the coil which passes over the ends of the armature, and which may be
regarded as dead wire, but which is useful as possessing a certain amount of self-
induction interposed in the exciting coil. This self-induction tends to eliminate the
irregular actions at the commutator which commutes the currents of said coil.
In practice I find that the exciting coil, if its potential be kept below 30 or 40 volts,
answers sufficiently well for the purpose of my invention, the coil C, C, at the same
time furnishing a current of 1,000 volts, or whatever the windings and connections
should give.
Figure 10 is a diagram of the connections of the exciting coil E to commutator
segments K, and from the brushes of said commutator to the variable resistance V
and field magnet coils. The brushes in passing the slots of the commutator (which
are preferably filled with an insulating substance and made rather narrow) are not
subject to burning produced by spark at the slots of the commutator when the
potential of the exciting coil E is below that at which an arc or spark can be easily
originated between metal surfaces, and the brushes themselves can be displaced
considerably from the exact neutral line of position of the exciting coil without
producing damaging actions at the commutator. I am also enabled by so displacing
the brushes forwards and backwards to regulate the potentials of the currents passing
outward from the exciting coil to the rest of its circuit, and in some cases to dispense
altogether with the variable resistance V, using simply the movement of the brushes
around the commutator to effect the same result.
The field magnet coils M, M, M, M, in circuit with the commutator K, and coil E,
require, of course, to be wound with coarse wire, of such low resistance that a
sufficiently strong exciting current may flow with the low electromotive force
developed by the coil E.
The preferred construction of the commutator K, of the machine is to make its
segments with fect f, projecting radially inward and tapering or spreading at the end
as shown in Figure 11, so that they may be grasped between sleeves in the form of
hollow cones as at Y, Y, with interposed insulating material between the feet f, and
the hollow, conical surfaces. In this manner I am able to secure a large diameter in
the commutator such as is required when the commutator contains a number of
alternating positive and negative segments, and at the same time at a very small
expense of materials to hold the parts in position and insulate them from one another.
The form of a single segment is shown at K¹.
In Figure 12, the coils Care shown connected in series and to the rings R, R,
from which by suitable brushes or collectors D, D, connection is made to the external
circuit of the machine.
During the operation of the machine adjustments of the excitation of the field
magnets may readily be made so as to secure a given potential at the armature
terminals which are connected to the rings R, R, by varying the amount of .current
generated in the exciting coil E, either by shifting its commutator brushes or by
introducing more or less of the variable resistance V, into the circuit. of the exciting
coil and the armature.coils.
Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed as communicated to
me 'by my foreign Correspondent I declare that what I claim is
:-
First. In a dynamo-electric machine, an armature provided with two coils as
described, one applied to the exterior or periphery thereof and furnishing the working
or line current and the other being wound longitudinally over the same armature
structure and supplying the exciting current for said machine, as and for the purpose
described.
Second. The combination for an alternating current dynamo, of a high tension
alternating current coil connecting directly with the work, a low tension coil, as
described, applied to the same armature, a field magnet.coil, and an intermediate

page_text: adjustable commutator between said low tension coil and field magnet coil for varying
the action of the machine.
Third. The combination with flat armature coils applied to the periphery of the
armature, of independent coils wound over the armature body and in the spaces in
the centre of the first-named coils.
Fourth. In a dynamo machine, an armature core body of discs of iron piled
laterally and secured so as to rotate with the shaft, and lieavier end plates for same
in combination with coil-supporting or seating rings of wood or metal at the ends of
armature as described.
Fifth. The combination with the armature core body of the projecting pins, in
combination with the pieces of insulating material strung on said pins and adapted to
fit the interior of the coils lying upon the surface of the armature.
Sixth. The combination with the multipolar field magnet and a series of armature
coils corresponding in number thereto, of a single independent coil wound on the
same armature and connected at its terminals to a commutator, the number of whose
segments correspond to the field magnet poles.
Seventh. The combination with the armature of a dynamo machine having
alternating current coils connected to the working circuit, and another set of coils
adapted to deliver a current kept below thirty or forty volts and connected through
a commutator with the field circuit, of a variable resistance in the latter connection
for adjusting the action of the machine.
Eighth. A dynamo electric machine having high tension armature coils connected
with the work, a low tension coil, as described, revolving in the field of the machine
and supplying current to a field sustaining coil, and an intermediate current adjusting
commutator between such low tension coil and the field magnet coil for adjusting or
varying the output of the machine.
Dated this 2nd day of October 1888.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London,
Agents for the Applicant.