Improvements in Dynamo-electric Machines and Electro-motors.
Year: 1890

page_text: COMPLETE SPECIFICATION.
Improvements in Dynamo-electric Machines and Electro-motors.
I, Professor ELIHU THOMSON, of 26 Henry Avenue Lynn in the State of Massa-
chusetts, one of the United States of America, Electrician, 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 :-
My invention relates to the construction of dynamo electric machines or electro-
motors, and is particularly applicable to machines adapted for the production of
alternating currents in a circuit, such alternating currents being capable of being
commuted to a continuous current wherever necessary by the addition of a suitable
cominutator.
One of the objects of my invention is to simplify the construction of the machine
and secure at the same time high efficiency and great power and compactness with any
given size of apparatus. In my machine the induction or armature coils in which
currents are induced, (which currents are alternating in character) are preferably
fixed in position instead of revolving and may therefore have their terininals carried
out without the interposition of moving contacts to the binding posts of the machine.
While I have hereinafter described but one induction or armature circuit as existing
in the machine, it will be understood that the circuits may be divided in manners
well known in the art to secure two or more circuits. Thus, if there are twelve coils
in which currents are induced, they may be coupled into sets of six, four, three or two,
or in a set of nine and three, or otherwise. The coils may also be coupled together
with any set in series or in multiple, or in multiple series or in series multiple, care
being taken to connect only those terminals in multiple that are of the same polarity
at any one instant, and in series those that are of opposite polarity at the same instant.
The field of magnetism of my machine is provided by a set of coils, preferably
stationary and generally only two in number, though I do not restrict myself in this
respect as the field coils may be wound on a revolving portion, as will appear. Fixed
coils are preferable, as they would not require sliding contacts for making connections
with them. It will thus be seen that in the machines embodying my invention, I
propose to make both the inducing and the induced current, that is the current in the
field conductor and what corresponds to the armature conductor, traverse stationary
coils with fixed terminals, the only part of the machine which revolves being an iron
mass suitably constructed. Notwithstanding this arrangement I find it possible to
obtain a very high yield and economy from such apparatus.
I will now proceed to describe some of the forms of my invention, selecting those
which I have found successful in practice, with modifications thereof and leaving to
the electrical engineer the making of other and equivalent modifications, not departing
from the essential elements of my invention.
In the accompanying drawings.
:-
Figure 1 shows an elevation in part section, of a machine containing preferred
forms and arrangements and embodying the improvements of my present invention.
Figure 2 is a view showing the relation of the inducing poles to the coils acted on
by them.
Figure 3 shows in perspective the revolving iron structure of my invention.
Figure 3 shows a modification in the form of the pole piece of the machine.
Figure 4 illustrates a modification in the arrangement suitable for large machines.
Figure 5 shows a still further modification of the revolving iron portion for
increasing the capacity of the machine.
Figure 6 is another elevation in part section of a modification of which
Figure 7 is an end view, certain portions being removed.
Figure 8 is a diagram showing the circuit arrangements simplified as far as
Desible

page_text: Figure 10 shows the connection of such bobbins in pairs in multiple so that the
arrangement is series multiple.
Figure 11 shows the relation of the winding of the iron core or iron plates adjacent
to the induced coils or in which the successive coils are connected in series and
reversed in direction as to their winding.
Figure 12 shows the winding which consists of coils connected in series, the
direction of winding in each of the coils being the same.
Figure 13 illustrates a modification in the form of the machine.
In Figure 1, P is the driving pulley carried by the shaft which goes through the
centre of the machine in bearings preferably of brass or non-magnetic metal at B, B¹.
The shaft is either enlarged at its centre in the form of a long core or it is slipped
through a mass of iron M preferably of cylindrical form adapted to rotate therewith.
This cylinder M is provided at one or more points with a laterally projecting mass or
enlargement of iron divided circumferentially into separate polar pieces. In the formi
of machine shown in Figure 1 this projecting mass is situated preferably midway
between the extremities of the portion M. Such laterally projecting or enlarged
portion of the iron mass or core piece M may consist of a number of iron plates or
lamine, which when combined produce a body of the form shown in Figure 3 some-
what resembling a pinion of laminated or subdivided iron. The polar projections N
marked in Figure 3 are preferably provided with additional laminations. Six of these
polar projections are shown though the machine may be provided with any suitable
number thereof above two. The laminated central mass is bolted together firmly and
forms a magnetically good connection with the core which it surrounds or upon which
it is carried. The core M, might if desired, be divided in planes parallel to its length,
especially near its centre, but in ordinary cases such division will not be necessary.
The laminated portion may consist of punched pieces slipped over the part M, or
sections holted therein and the laminæ may be insulated laterally one from the other.
It is well to have them magnetically separated near their polar extremities N, N, and
substantially electrically insulated not necessarily so at the centre where they meet
the core M, but particularly at their outer extremities. The ordinary black oxide on
sheet iron will be found generally sufficient for the electrical insulation of the sheets
laterally. Where special economy of action is not desired the lamination of the core
pieces or projections may be entirely dispensed with and the structure may be inade
solid with the projections N integral with the portion M, and forming extensions of
the same.
This is particularly the case where the induction coils are "pancake" coils
without iron cores as in Figure 4, to be afterwards referred to. Surrounding the core
piece M, Figure 1 and partially enclosing the same at the outer ends are end plates
marked E supported on the base of the machine and fitted to the outline of the
core M, and separated therefrom by a slight space. On the plates E alongside and
surrounding the core piece M, are wound the field energizing coils E' shown in section
supported by such plates. The plates E serve the double purpose of a support for the
energizing coils and a part of a magnetic circuit extending from the ends of the core
piece, as will be presently described. It is therefore apparent that the annular portions
of the plates should be of iron. The cylindrical portion E2 of the plate is preferably
also of iron and integral with the other portion, though this is not essential inasmuch
as it serves mainly as a bobbin or support for the field coils, by which the said coils
may be supported in close proximity to the core piece M, so as not to interfere with
the rotation of the same, but yet to act strongly in magnetizing the same. These coils
around M, may be connected into any convenient circuit carrying continuous currents
for magnetizing the machine. They are wound in opposite directions relatively to
one another so that they tend to form a region of strong consequent polarity at the
middle of the bar or core M the magnetism from which is conducted outward by the
aforesaid lateral extension and produces strong poles of north or south polarity
according to the direction of the current, at the pole pieces N.
The end plates E are joined at their outer portions by an iron framework or
casing F, shown as consisting of a simple tube or cylinder surrounding the machine
7

page_text: but it may be made of divided sections, and in large machines would be preferably
so made. It is simply designed to connect the outer edges of the end plates E, E,
magnetically with the stationary ring A of iron preferably laminated, shown more
distinctly in Figure 2 as surrounding the core M, at or about the central portion of
the same or so as to embrace the laterally or centrally projecting portion of the core
or mass M.
To the inner side of the structure A and when preferred upon projections extending
radially inwards are applied, in the ordinary and well known way, other coils the said
rings and coils thus being made to resemble a multipolar ring or cylindrical shaped
magnet whose poles are on the inside.
The structure A is built up of a number of ring shaped plates or sections of rings
bolted together to form practically a compound laminated ring. It might be made of
iron wire or otherwise subdivided, provided the subdivisions were made in a direction
It
to cut off Foucault currents which might otherwise be induced in the mass.
corresponds in a measure to a fixed laminated armature and is supported in the
interior of the outside casing or frame, being firmly secured in place. This outer
frame while shown entire, might be perforated with openings at a, a, as indicated in
dotted lines so as to allow a measurable ventilation of the interior of the machine,
such perforations only requiring to be placed so as not to interrupt the magnetic con-
tinuity to too great an extent. Perforations might also be made in end plates E, E
outside of the field winding, as indicated in the dotted lines at b', 6', and the
bearings B, B' may as shown be supported on gibs which allow the entrance of air at
the ends of the machine: which air would, if perforations were made near the exterior,
circulate through the machine and be discharged. It may be pointed out also that
wherever laminated pieces are united by bolting or otherwise, if the bolts connect
sheets situated at points of different potential the bolts themselves should be insulated.
These are matters well understood in the art.
The ring structure A, A, Figure 2 may have interior projections of double the
number of the aforesaid poles Ň. On these projections are firmly secured coils of
wire in which currents are to be induced, three of such coils being indicated in dotted
lines as being placed over the three upper projections Figure 2. Such coils are also
shown in section, as secured in place both above and below, in Figure 1.
Figure 3 shows how the form of the projection may be modified to be a rounded
interior projection p opposite which the moving poles N, of the core piece M pass, the
induction coil conductor being slipped over these rounded projections as indicated
at C.
"
In large machines it will be preferable to dispense with projections, and to make,
the ring A a plain laminated ring on the interior surface of which flat "pancake
coils are placed and properly secured as shown in Figure 4. These coils are wound
in alternately reverse direction proceeding around the interior of the ring and should
be double in number of pole pieces N which project towards them and revolving on
the core structure M, but if the coils are all wound in the same direction or connected
so that the current flows through them in the same direction relatively they should be
of equal number to the number of pole projections and spaced accordingly. Where
several circuits or sets of coils are to be used they may be otherwise placed or con-
nected and two sets of coils may be even superposed on each other in such an
arrangement as Figure 4, where the coils are flat and there are no iron projections,
and if connected into different circuits may even be displaced relatively one set to the
other in the interior of the ring.
1
In some cases there may be several rings surrounding the same core structure and
shaft, as indicated in Figure 13, in which case a polar extension will be sufficient to
act upon the whole interior surface of the rings. Or, as indicated in Figure 5, the
core structure may be extended from M to M and may carry on it three sets of polar
extensions of consequent poles like three laminated pinions, or where the laminations
are not necessary as in case shown in Figure 4 where no interior projections on the
ring A exist, the poles may be made solid with the core shaft M M¹ or of pieces of

page_text: metal secured thereto. The field energizing coils in the case shown in Figure 5 are
mounted so as to surround the core.piece M M both outside of and between the sets
of projections, the coils either being carried independently of the revolution of the
piece or wound directly thereon, while the end plates resembling those indicated in
Figure 1, carry an outer casing for three rings, structures like A A corresponding to
the three sets of polar projections Figure 5. The polarities which the windings on M
must give are alternate. Thus, those to the left may be all of north magnetic polarity
while the middle section is south, and those to the right are all north again. These
are indicated by the letters N, S, N₁ indicating the positions of the polar projections
or series of consequent poles on the inner core piece M, M'.
It will readily be seen that in this manner the machine may be extended and its
capacity greatly increased for the reason that the coils on each ring may become a
separate source of current or may be coupled with the coils of other rings, or the coils
on each core ring may be divided into sets and coupled or not.
Figure 6 shows a modification in which the inner core piece, revolving as before,
carries on it a star shaped set of poles or pinion shaped piece, more distinctly seen
at N, N Figure 7. This piece is shown in Figuro 6 as situated between coils C, C¹
two ranges of such coils existing whose planes are at right angles to the axis, and
which are seen in position in Figure 7, one range there being indicated. The end
plates E E in this case simply carry on their inner faces and on their outer edges a
laminated ring constructed so that the divisions between the sheet are concentric, as
shown. The edges of the sheets are shown in Figure 7, while in Figure 6 they are
shown in part section. This portion of the machine may be made of hoop iron wound
up into the form of a ring. Alongside this compound hoop or band are situated the
field energizing coils El corresponding with those shown in Figure 1 carried by the
end plates and magnetizing the core piece M to produce strong consequent polarity in
its pinion shaped pole pieces, the polarity of the projections being alike. In this case
the magnetic inductions are exerted laterally from the revolving set of consequent
poles to the coils C, C instead of directly and radially outward, as in the previous
figures. The end plates E E may be held at their proper distance apart by bolts of
brass or non-magnetic metal as shown in Figure 6.
Figure 8 is a diagram illustrating the action produced when the core structure is
energized and is revolved, and shows the ring piece A A with the core piece M
centred and revolving therein, which latter is as shown provided with two polar
projections N N diametrically placed. In the interior of the ring A are indicated
four coils C, the direction of the winding of each in this instance being reversed
alternately. They are connected as shown in series and joined to an external work
circuit L the field energizing coils E¹ being supplied from a suitable source of current
for excitation S. In case only two coils CC are used they would be placed
diametrically opposite as to their centres. They would extend over a larger area of
the interior of the ring than when four are used and would be connected in the same
relative direction. The coils in Figure 8 to utilize all the space, should be large
enough to meet edgewise in their position in the interior of the ring, but are shown
in that figure widely separated as it is merely a diagram.
Figure 9 simply indicates the successive connections of a range of coils laid flat
against the interior of the ring structure A A or slipped on projections extending
inwardly from the same. Here the coils are supposed to be double in number to
the field projections and are therefore wound reversely or connected alternately
reversed. In Figure 10 the same set of coils is otherwise connected into a sèries
multiple arrangement with two coils in series and each of these coils put in
multiple.
Figure 11 shows the laminated projections over which the coils C C have been slipped
when wound reversely as in Figure 9.
Figure 12 shows a similar set of projections which are provided with coils not
wound or connected reversely but in the same direction, every alternate projection
.only being in this case provided with a coil. This same arrangement may be used

page_text: when no projections from the ring structure A A exist and the coils are then equal
in number to the polar projections from the field and spaced apart accordingly.
The action of the machine, or its modifications is as follows:-
The moving field poles N, etc. carried around on the revolution of the core piece M
pass in front of the coils in which the currents are to be induced. The lines of
magnetic force projecting from these pole pieces cut across the wire on the coils
transversely, since the coils lie in the proper direction to be so cut, or at least the
sides of the coils parallel to the axis so lie and generate in the coils impulses of current.
The direction of the winding and the connection is such as to make the effects
accumulative in the coils, that is so that if a polar projection N passes as in Figure 2
over the centre of one coil to that of the next its lines are caused to cut the wire lying
between those centres half of which would belong to that coil, the centre of which is
being left by the travelling pole, and half to the coil towards the centre of which the
travelling pole is moving. An impulse of current would thus be set up in both coils
and if the direction of connection is like Figure 9, each impulse will be superadded,
or in case the connection of the coil is made such that the impulses developed are
carried to the external circuit L L, Figure 8 in the same direction, a similar result
will follow. Were the number of coils equal the number of projections, as in Figure 12
then the action is the simple cutting in succession by the lines emanating from the
pole projections, of one side of a coil or of one side of all the coils taken together and
immediately thereafter the other side of the same coil or set of coils taken together,
the winding being all in the same direction and the impulses therefore being directed
in the same way in each coil. These actions of cutting by the lines emanating from
the poles will be repeated in the coils every time the polar projection passes the wire
or either side of a coil so that if there be six poles as indicated in Figures 1, 2, 3, 6
and 7 and the revolution of the machine be made at the rate of one thousand turns
per minute the alterations of current or impulses will number six thousand positive
and six thousand negative, or a total of twelve thousand alternations during one
minute. These actions of induction repeatedly following one another will be accom-
plished without a reversal of magnetism in the core piece or even in the laminated
ring structure supporting the coils in which the currents are induced but on the
contrary the lines of force will simply be carried rapidly past the wire whose virtual
direction of winding is opposite alternately, and this will generate impulses without
the necessity of magnetic changes of polarity taking place in any of the core pieces.
I am thus enabled to save a large portion of the loss due to magnetic changes of
hysteresis, as it is called in the iron of the machine while still utilizing the iron to the
best advantage in the construction of the magnetic bodies subject to the magnetizing
actions of the field energizing coils. I also secure a strong magnetic field by the
expenditure of a minimum of energy in sustaining the same, besides which none of
the wire of the machine need revolve, and I therefore dispense with rubbing surfaces
or sliding contacts when the machine is used for the generation of alternating impulses
or alternating currents.
The construction of the machine itself is comparatively easy as the parts are of
simple form and easily mounted in a substantial manner. The constructions Figures 6
and 7 do not even require that the revolving magnetic mass shall be laminated and
subdivided, and the laminated ring pieces A A, of Figures 6 and 7 upon the faces
of which the coils CC are mounted opposite the revolving poles, can be as before
indicated wound up out of a strip sheet metal, a procedure very easily practised and
not requiring special machinery. The revolving core piece with its star shaped centre
may be made of one solid piece of cast iron if desired or- better of cast soft iron, such
as Mitis iron. The end plates E E¹ may in like manner be so constructed, and the
revolving portions of the machine are enclosed in such manner as not to be liable to
cause injury or to be injured.
While I have described my invention as particularly useful for machines when
employed for developing electricity from power, it will be readily understood by
electricians that the same general features of construction are also of utility in electric

page_text: motors in which the action and reactions produced by the influence of alternizing
electric currents set up a motive influence or torque as is now well understood in
the art.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is:-
First. In a dynamo electric machine or motor the combination of a magnet
structure having consequent pole and extensions therefrom at its position of such
developed polarity such extensions being separated into separated polar projections
constituting a series of like poles, iron masses surrounding and in proximity to the
said magnet structure at an opposite polar portion thereof and forming magnetic
extensions of such opposite polarity to a laminated ring for closing the magnetic
circuit exteriorly and electric coils on the face of said ring said poles and coils being
one or both movable with relation to one another.
Second. A dynamo electric machine containing the following elements the com-
bination A revolving field core with a consequent pole or poles at an intermediate
portion of its axial length and extending outwardly into a number of separate polar
projections, stationary energizing coils surrounding the axially projecting ends of the
core plates or magnetic carriers in close relation to the revolving core but dis-
connecte: therefrom and extended to support a laminated ring or coil carrier, and
induced coils supported upon the face of said ring and presented to the revolving
field poles.
Third. In a dynaino electric machine or motor a fixed armature coil and field
system having a revolving magnetic core provided with a number of like poles
presented to the armature coils or induced coils and consisting of separate polar
extensions from a consequent pole produced in the common field core, in combination
with two coils or sets of coils wound or applied reversely as described at opposite
sides of the consequent polar portion so as to produce a consequent pole in said
magnetic core.
Fourth. In a dynamo electric machine or motor the combination of two or more
oppositely wound or connected field magnetizing coils, a revolving field magnet core
centreing therein carrying between each pair of oppositely wound coils extensions of
its consequent pole into a number of polar projections, a laminated ring surrounding
such polar projections bearing on its face a series of coils laid flat against such face,
and magnetic casings or extensions of magnetic material serving to convey magnetism
from the other portion or outer face of the laminated ring to those ends of the field
core, which project into and through the field cores outwardly.
Fifth. In a dynamo electric machine or motor a field core mounted on an axis
parallel to its magnetic axis and bearing at its middle portion a series of polar
extensions of like polarity iron shells surrounding that portion of the core which
projects through the field coils and a laminated ring bearing the induced coils outside
or adjacent to the polar projections.
Sixth. In a dynamo electric machine or motor an induced coil system consisting of
a laminated ring bearing on its inner surface face a system of coils in which the
windings are successively reversed and connected as described into one or more
circuits in combination with a revolving field structure having polar extensions
equal in number to half the number of coils or coil positions. existing on the inner
surface of the ring.
Seventh. In a dynamo electric machine or motor the combination of a magnet
structure having a consequent pole divided into separate polar projections or extensions
a series of coils carried on a suitable support, and having their same sides or poles
presented to all of said polar projections and iron masses in proximity to the said iron
magnet structure for closing the magnetic circuit exteriorly from the opposite pole
thereof through all of said coils as and for the purpose described.
k
Eighth. In a dynamo electric machine or motor a revolving magnetic, core piece

page_text: mounted on an axis parallel with its magnetic axis and having a consequent polar
portion subdivided into several polar projections which are constantly magnetized a
coil or coils surrounding said core piece at opposite sides of said polar portion and
traversed continually by exciting current and another set of coils inductively
presented to the polar projections and applied to a magnetic extension from said
core piece.
Ninth. In a dynamo electric machine the combination with a revolvable pole piece
mounted to turn on its magnetic axis, of two exciting coils or sections of coil com-
bined to produce a consequent pole in such core piece between them a series of
separate polar projections at such consequent polar portions of the core piece, and
a series of coils having their same poles or sides inductively presented to the said
polar projections.
Tenth. In a dynamo machine or motor, the combination of a revolvable core piece
having a consequent polar portion subdivided into a set of separate radial arms, a
magnetic extension from an opposite pole of said core piece and a series of fixed
coils presented to the sides of said polar arms and mounted on said magnetic exten-
sion so as to be in a magnetic circuit from the consequent polar portion closed
exteriorly by said extensions.
Eleventh. The combination, substantially as described of an electro magnet having
a series of polar projections from a consequent pole, two energizing coils at opposite
sides of said pole, and a series of separate coils inductively related to said consequent
poles and applied to iron masses forming magnetic extensions from the core having
such consequent pole.
Twelfth. In a dynamo electric machine or motor a moving element consisting of a
core having a consequent polar portion extending transversely outward into a number
of separate poles of the same name, in combination with a fixed coil for said core
and another set of fixed coils mounted on a magnetic extension of the core presented
to said poles.
Thirteenth. The combination with the iron core (M) mounted on its longitudinal
axis, of energizing coils combining to produce a consequent pole in said core piece
between them, a bundle of iron plates secured to the consequent polar portion of the
core piece and each divided at its periphery into a series of polar projections and a
second set of coils mounted on a magnetic extension from said core piece presented to
the end of said projections.
Fourteenth. In a dynamo machine or motor a revolvable iron core piece mounted
on its longitudinal axis, and having a laminated mass of iron secured to it and
divided peripherally into separate poles, in combination with fixed energizing
coils for developing polarity at the portion of said core piece where the laminated
mass is located and a series of fixed coils presented to the ends of said separate
poles.
Fifteenth. In a dynamo machine or motor, the combination with an iron core having
fixed energizing coil or coils, continually traversed by exciting current of a series of
projections extending radially outward from a central revolvable polar portion of the
mass of iron energized by such coils all such projections being of the same polarity
and continually polarized and a fixed magnetic extension from an opposite pole of
said core carrying a series of fixed coils arranged in the periphery of a circle around
said polar projections and presented to the same as and for the purpose described.
Sixteenth. In a dynamo machine or motor the combination with an iron core having
an energizing coil or coils of a series of projections from the polar portion of said
core and all of the same polarity and a magnetic extension from an opposite pole of
said core carrying a series of coils presented to said projections the said coils or
projections being one or both movable."
Seventeenth. In a dynamo machine or motor, the combination with an iron core
having an energizing coil or coils of a series of projections from a polar portion of
said core and all of the same polarity a series of coils having their same sides or poles
only presented to said projections and magnetic extensions from an opposite pole of

page_text: said core carrying magnetism through all of said coils in the same direction or of the
same polarity to the series of polar projections the said series of coils and polar
projections being one or both movable as and for the purposes described.
Dated this 22nd day of July 1890.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.