IMPROVEMENTS IN MAGNETO OR DYNAMO ELECTRIC MACHINES OR ELECTRIC ENGINES
Year: 1881

page_text: LETTERS PATENT to Peter Jensen, of 33, Chancery Lane, in the County of
"
Middlesex, for an Invention of IMPROVEMENTS IN MAGNETO OR DYNAMO
ELECTRIC MACHINES OR ELECTRIC ENGINES." A communication from abroad
by Thomas Alva Edison, of Menlo Park, in the State of New Jersey, United
States of America.
PROVISIONAL SPECIFICATION left by the said Peter Jensen at the Office
of the Commissioners of Patents on the 6th July 1881.
PETER JENSEN, of 33, Chancery Lane, in the County of Middlesex. " IMPROVE-
MENTS IN MAGNETO OR DYNAMO ELECTRIC MACHINES OR ELECTRIC ENGINES."
(A communication from abroad by Thomas Alva Edison, of Menlo Park, in the
State of New Jersey, United States of America.)
The object of the first part of this Invention is to produce a dynamo or magneto
electric machine, in which the iron core of the armature will not be necessary, and
the loss of power caused by the heating of the same will be avoided, only the
inductive portion of the armature being passed between the polar extensions of the
exciting magnet or magnets, which polar extensions can consequently be brought
close together so as to produce an intense magnetic field. And the object is further
to construct a machine of this character so that it will generate a continuous current
of high electro motive force in the same direction without the use of pole changers,
all the inductive portions of the armature boing constantly in circuit, and the
internal resistance of the machine being exceedingly small.
This is accomplished by constructing the armature in the shape of a disc or plate
like that used by Arago in his experiments, but divided into radial sections. These
radial sections which form the inductive portion of the armature are preferably
naked copper bars joined edgewise by a non-conducting material, so that they form
a rigid disc or plate, and attached rigidly to the driving shaft by means of an
insulating hub; the radial bars are turned outwardly at their inner ends and con-

page_text: nected thereby, or by rods, with circular plates, surrounding the driving shaft or
the hub of the armature, and insulated from each other.
Each plate has a tongue which is turned outwardly and secured in a groove of
the insulating commutator cylinder. The bars nearest to diametrically opposite
positions are in this manner connected together in pairs, and with a commutator
bar midway between them.
The radial bars revolve between the polar extensions of an electro-magnet or
magnets (two electro-magnets being preferred for the purpose) and outside of such
polar extensions the disc formed of radial bars and insulating material is surrounded
by concentric metal rings (preferably of copper) which are insulated from each
other and the radial bars (except as hereinafter explained).
The number of the exterior concentric rings, as well as of the plates of the hub,
is one half that of the radial bars.
The radial bars at their outer ends have arms made integral therewith or
secured to them which extend to the proper rings and are insulated from all
others.
Each ring connects two radial bars, the terminal bar of one opposite pair being
connected thereby with the initial bar of another pair so as to make a continually
closed circuit through all the bars. The connections between the bars being all
multiple are connections the internal resistance of the machine is reduced to the
minimum. The plates and rings make the connections symmetrical at every
point.
For illustration I will suppose the disc to be composed of sixteen radial bars,
The disc would be
which I will refer to by numbers, as bars 1 to 16 inclusive.
surrounded by eight rings, which I will call rings 1 to 8 inclusive, ring 1 being
the inner ring and ring 8 the outside ring. Eight plates and commutator bars
would also be used. Now to ring 1 would be connected the outer ends of bars 1
and 11 to ring 2 bars 8 and 15; to ring 3 bars 6 and 13; to ring 4 bars 4 and 10;
to ring 5 bars 3 and 9; to rings 6 bars 7 and 16; to ring 7 bars 5 and 14; and to
ring 8 bars 2 and 12.
The bars would be connected together at their inner ends and to commutators
midway between them in pairs, as follows:-Bars 1 and 8, 2 and 11, 3 and 10,
4 and 13, 5 and 12, 6 and 15, 7 and 14, and 9 and 16.
This arrangement can be extended as may be desired, and arinatures made with
a large number of bars.
The current commencing at the negative commutator brush or spring is divided
into two parts, each of which parts passes through one half of the radial bars, and
combines with the other part at the positive commutator brush or spring.
In this manner all the bars are continually kept in circuit, and a current is
generated having an electro motive force due to one half the length of all
the bars.
The concentric rings are arranged outside of the polar extensions of the exciting
magnets, so that such extensions can be brought close up to the inductive bars,
while the rings are nearly outside the magnetic field, and do not cut the lines of
force at right angles, and consequently exert no counter effect upon the electro
motive force of the current.
The radial bars could be cut away or removed at three or more points to make
room for metallic arms projecting from the hub in order to strengthen the armature
without seriously detracting from the efficiency of the machine.
It is important that a disc armature of this kind should be made exceedingly
stiff and strong, especially when the machine is connected up for use as an electric
engine.
For this purpose I have designed two constructions as follows:-
First. The polar extensions on one side of the armature can be set further back
leaving a space for the reception of a strengthening disc, to which the inductive
bars will be secured. This disc will be formed by winding a thin strip of iron
round the hub, with a strip of paper, which will separate the spiral convolutions

page_text: of the iron. Around this disc will be shrunk an iron ring, and radial bolts will be
passed through holes in the disc and screwed into the hub. The copper rings will
then be added, and then another iron ring may be shrunk on.
This last ring may also be used with all or any one of the constructions herein
described.
This strengthening disk having its conducting portion in the shape of spiral
convolutions, said conducting portion does not cut the lines of force, but becomes a
detached portion of the magnet, which revolves with the armature.
Second. The radial bars of the first construction can be made forked, or in two
parallel parts connected at their inner ends, and between these parts can be inter-
polated a core made of spiral convolutions of iron and paper as just described.
The inductive copper bars of the last two constructions are connected in the
manner already described of the first construction.
Another part of this Invention relates to the application of concentric rings for
making the multiple are connections of the copper bars in a dynamo or magneto
electric machine or electric engine having an armature of cylindrical form.
At each end of the cylindrical armature is arranged a series of insulated con-
centric copper rings placed outside of the polar extensions of the exciting magnet.
Each ring is provided with two projecting fingers on the outside edge, which are
turned inwardly, and connected with the ends of the proper longitudinal bars.
Midway between the connection of each ring with two bars at the commutator
end of the machine, such ring is connected with a bar of the commutator cylinder,..
This is preferably done by means of an angular bar connected with the ring, and
connected with or forming a bar of the commutator cylinder.
In this machine the bars may be connected in opposite pairs, and midway to
commutators in the same manner that the radial bars before described are connected
at their inner ends, while at the opposite end of this last machine the bars may
have their connections arranged like those at the outer ends of the radial bars
before described.
The novel features of all these machines are equally well applicable to electric
engines and motors, and this description is intended to be understood as covering
the same.
For electric engines the disc armatures possess the advantage of great lateral
compactness, permitting the use of the engine on a narrow railway car without
having it project over the sides of the same, or in other locations where lateral
space is limited.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Peter Jensen in the Great Seal Patent Office on the 6th January
1882.
PETER JENSEN, of 33, Chancery Lane, in the County of Middlesex. "IMPROVE
MENTS IN MAGNETO OR DYNAMO ELECTRIC MACHINES OR ELECTRIC ENGINES."
A communication from abroad by Thomas Alva Edison, of Menlo Park, in the
State of New Jersey, United States of America.
The object of the first part of this Invention is to produce a dynamo or magneto
electric machine in which the iron core of the armature will not be necessary, and
the loss of power caused by the heating of the same will be avoided, only the
inductive portion of the armature being passed between the polar extensions of the
exciting magnet or magnets, which polar extensions can consequently be brought
close together so as to produce an intense magnetic field. And another object is
to construct a machine of this character so that it will generate a continuous
current of high electro-motive force in the same direction without the use of pole
changers, all the inductive portions of the armature being constantly in circuit,
and the internal resistance of the machine being exceedingly small.
This object is accomplished by constructing the armature in the shape of a disk
or plate, like that used by Arago in his experiments, but divided into radial
sections. These radial sections, which form the inductive portion of the armature,
are preferably naked. copper bars joined edge wise by a non-conducting material,
so that they form a rigid disk or plate, and attached rigidly to the driving shaft
by means of an insulating hub. The radial bars are turned outwardly at their
inner ends, and connected thereby or by reds with circular plates surrounding the
driving shaft or the hub of the armature, and insulated from each other. Each
plate has a tongue, which is turned outwardly and secured in a groove of the
insulating commutator cylinder. The bars nearest to diametrically opposite
positions are in this manner connected together in pairs, and with a commutator
bar midway between them. The radial bars revolve between the polar extensions
of an electro-magnet or magnets (two electro-magnets being preferred for this
purpose), and outside of such polar extensions, the disk formed of radial bars and
insulating material is surrounded by concentric metal rings (preferably of copper),
which are insulated from cach other and the radial bars (except as hereinafter
explained).
The number of the exterior concentric rings, as well as of the plates of the hub,
is one-half that of the radial bars. The radial bars at their outer ends have arms
made integral therewith or secured to them, which extend to the proper rings and
are insulated from all others. Each ring connects two radial bars, the terminal
bar of one opposite pair being connected thereby with the initial bar of another
pair, so as to make a continually closed circuit through all the bars.
The con-
nections between the bars being all multiple arc connections, the internal resistance
of the machine is reduced to the minimum. The plates and rings make the con-
nections symmetrical at every point.
For illustration, suppose the disk to be composed of sixteen radial bars, which
will be referred to by numbers as bars 1 to 16 inclusive. The disk would be
surrounded by eight rings, which will be called rings 1 to 8 inclusive, ring 1 being
the inner ring and ring & the outside ring. Eight plates and commutator bars
would also be used. Now to ring 1 would be connected the outer ends of bars 1
and 11; to ring 2, bars 8 and 15; to ring 3, bars 6 and 13; to ring 4, bars 4
and 10; to ring 5, bars 3 and 9; to ring 6, bars 7 and 16; to ring 7, bars 5 and 14;
and to ring S, bars 2 and 12.

page_text: The bars would be connected together at their inner ends, and to commutators'
midway between them in pairs as follows:-Bars 1 and 8, 2 and 11, 3 and 10,
4 and 13, 5 and 12, 6 and 15, 7 and 14, 9 and 16.
This arrangement can be extended as may be desired, and armatures made with'
a large number of bars.
The current commencing at the negative commutator brush or spring is divided
into two parts, each of which parts passes through one half of the radial bars,
and combines with the other part at the positive commutator brush or spring.
In this manner all the bars are continually kept in circuit, and a current
is generated having an electro-motive force due to one half the length of all the
bars.
The concentric rings are arranged outside of the polar extensions of the exciting
magnets, so that such extensions can be brought close up to the inductive bars,
while the rings are nearly outside the magnetic field and do not cut the lines of force
at right angles, and consequently exert no counter effect upon the electro-motive
force of the current.
The radial bars could be cut away or removed at three or more points to make
room for metallic arms projecting from the hub, in order to strengthen the armature
without seriously detracting from the efficiency of the machine.
It is important that a disk armature of this kind should be made exceedingly
stiff and strong, especially when the machine is connected up for use as an electric.
engine.
For this purpose two constructions have been designed as follows:-
First. The polar extensions on one side of the armature can be set further back,
leaving a space for the reception of the strengthening disk to which the inductive
bars will be secured. This disk will be formed by winding a thin strip of iron
around the hub with a strip of paper, which will separate the spiral convolutions
of the iron. Around this disk will be shrunk an iron ring, and radial bolts will
be passed through holes in the disk and screwed into the hub. The copper rings
will then be added, and then another iron ring may be shrunk on.
This last ring
may also be used with all or any one of the constructions herein described.
This strengthening disk having its conducting portion in the shape of spiral con-
volutions, said conducting portion does not cut the lines of force but becomes a
detached portion of the magnet which revolve with the armature.
Second. The radial bars of the first construction can be made forked, or in two
parallel parts connected at their inner ends, and between these parts can be inter-
polated a core made of spiral convolutions of iron and paper, as just described.
The inductive copper bars of the last two constructions are connected in the
manner already described of the first construction.
Another part of this Invention relates to the application of concentric rings
for making the multiple are connections of the copper bars in a dynamo or
magneto electric machine or electric engine, having an armature of cylindrical
form.
At each end of the cylindrical armature is arranged a series of insulated con-
centric copper rings, placed outside of the polar extensions of the exciting magnet..
Each ring is provided with two projecting fingers on the outside edge, which
are turned. inwardly and connected with the ends of the proper longitudinal bars.
Midway between the connection of each ring with two bars at the commutator
end of the machine, such ring is connected with a bar of the commutator cylinder.
This is preferably done by means of an angular bar connected with the ring, and
connected with or forming a bar of the commutator cylinder. In this machine
the bars may be connected in opposite pairs, and midway to commutators in the
same manner that the radial bars before described are connected at their inner
ends, while at the opposite end of this last machine the bars may have their
connections arranged like those at the outer ends of the radial bars before
described.
The novel features of all these machines are equally well applicable-to-electric

page_text: engines and motors, and this description is intended to be understood as covering
the same.
For electric engines, the disk armatures possess the advantage of great lateral
compactness, permitting the use of the engine on a narrow railway car without
having it project over the sides of the same, or in other locations where latera!
space is limited.
:
The foregoing will be better understood by reference to the Drawings, in which
Figure 1 is an elevation of the simplest form of disk armature with the com-
mutator cylinder in section, the connections of the radial bars with the commutator
bars being shown diagramatically.
Figure 2, a central horizontal section, and
Figure 3, a perspective view of this machine.
Figure 4 is a horizontal section of the machine, having disk armature with
strengthening core.
Figure 5, a vertical section of the armature of this machine.
Figure 6, a separate perspective view of one of the double inductive bars and its
commutator connection.
Figure 7 is a perspective view of a cylindrical armature, having the longitudinal
bars connected by concentric rings.
Figure 8, a longitudinal section through this last armature, the commutator
cylinder being shown in elevation, and
Figure 9, a separate view of one of the concentric rings.
With reference to Figures 1, 2, and 3,
A, B, are the electro-magnets, and A1, A2, B1, B2, the polar extensions of same;
C, is the driving shaft. The radial copper bars are numbered from 1 to 16
inclusive. D is the hub to which the radial bars are secured, the bars being
insulated properly therefrom. Sixteen radial bars are shown for purpose of
illustration, but the number might be more or less, according to the size of the
machine. E represents the circular insulated plates with which the radial bars are
connected, and these plates have tongues e connected with the bars of commutator
cylinder F. Two radial bars are connected with each plate E, and by it with the
nearest central commutator bar.
The concentric copper rings surrounding the radial bars are lettered from G¹
to G inclusive. They are connected with the radial bars by bands, straps, or
rods H, or the radial bars may be forked and inclose the rings partly, in which
case H would be integral with such radial bars. The neutral line extends vertically
through the center of the armature, while the commutator brushes or springs P, N,
make contact with the sides of the commutator cylinder at the ends of the
horizontal diameter, the bars next to the neutral line being connected with the
central side commutator bars as shown. On the left hand side of the neutral line
the currents in the radial bars, as shown in Figure 1, all run inwardly, while those
on the right hand side flow outwardly. In the position shown, one portion of the
current would pass from the negative to the positive commutator brush, via
1. G. 11.2.G.12.5. G7.14.7. G. and 16, and the other portion via 8. G³. 15.
6. G.13.4. G. 10.3. G. and 9, the proper plates E and straps H being included
in the circuits.
The first means set forth in the general description for strengthening the disk
armature (by using an extru disk on one side of the radial bars) is not shown in
the Drawings, the general description being sufficiently full to enable those skilled
in the art to understand that construction.
The second construction for that purpose is illustrated in Figures 4, 5, and 6.
In those Figures A is the shaft; B, the hub; C, the double naked copper bars;
D, the copper disk connected by extensions a with C, and by rods or strips b with
bars of commutator cylinder E; F is the core of the armature. H represents the
concentric copper rings connected with C by the offset arms d.
I, K, are the electro-magnits, of which N, S, are polar extensions.

page_text: '
The application of the concentric rings to the cylindrical armature is shown in
Figures 7, 8, and 9.
A is the core of the armature built up of disks or rings of iron separated by
paper. B represents the longitudinal naked copper bars; C, C, are the two series
of concentric copper rings at the ends of the armature. Each ring has two
fingers c for making connection with the inductive bars. D is the commutator
cylinder, the bars of which are connected with the concentric rings at one end of
the armature by angular bars d.
What is claimed is,―
First. A dynamo or magneto electric machine or electric engine having an
armature provided with radial inductive bars revolving in the magnetic field,
substantially as set forth.
Second. The armature of a dynamo or magneto electric machine or electric
engine constructed in the form of a metal disk divided into radial sections, con-
nected together and insulated from each other so as to produce a rigid disk,
substantially as set forth.
Third. In a dynamo or magneto electric machine or electric engine, the armature
formed of radial bars symmetrically connected together, and with commutator bars,
so that all the radial bars will be kept continually in circuit, substantially as set
forth.
+
Fourth. A magneto or dynamo electric machine or electric engine, having in
combination the armature constructed of radial bars connected in pairs at their
inner ends with the commutator bars and suitable connections of different pairs at
the outer ends of the radial bars, whereby the radial bars will all be kept con-
tinually in circuit, substantially as set forth.
Fifth. In a dynamo or magneto electric machine or electric engine, the concentric
rings for connecting the armature bars, substantially as set forth.
Sixth. In a dynamo or magneto electric machine or electric engine, the com-
bination with the armature of the concentric rings for connecting the armature
bars revolving outside of the polar extensions of the magnet or magnets, substan-
tially as set forth.
Seventh. The method or means for strengthening a disk armature, consisting in
attaching a core or disk to one side of the same, substantially as described.
Eighth. The method or means for strengthening a disk armature, consisting in
providing the same with a central core, substantially as described.
Ninth. A strengthening core or disk for disk armatures made of spirally wound
iron and an insulating material, substantially as described. -
Tenth. The combination with the cylindrical armature, of the concentric rings
for connecting the inductive bars, substantially as set forth.
In witness whereof, I, the said Peter Jensen, have hereunto set my hand and
seal, this Fifth day of January, in the year of our Lord One thousand eight
hundred and eighty two.
PETER JENSEN. (L.S.)