Improvements in Disc Dynamo or Magneto Electric Machines.
Year: 1887

page_text: Improvements in Disc Dynamo or Magneto Electric Machines.
I, CHARLES DENTON ABEL, of No. 28 Southampton Buildings, Chancery Lane in
the County of Middlesex, Consulting Engineer and Patent Agent, do hereby declare
the nature of this invention to be as follows: :-
In all disc dynamo or magneto electric machines of present construction the object
is to have a very powerful magnetic field or inductor, this being obtained by placing
the magnets very close to each other. It is also endeavoured to avoid as much as
possible the heating of the armature, caused by the Foucault currents in the iron
cores. Furthermore it is endeavoured to utilise as much as possible the copper wire
of the armature by placing it entirely in the magnetic field, as distinguished from the
cylindrical armature machines in which the portion of the wire at the two ends of the
cylinder only serves to connect the other parts without in any way adding to the power
of the machine.
The present invention has for its object a novel construction of disc dynamo or
magneto electric machine which I will proceed to describe with reference to the
accompanying drawings, and which attains the above objects in a very perfect degree,
while avoiding the defects of existing machines.
According to this invention, the disc armature is formed by a series of coils grouped
round a central shaft, each coil being formed by a split copper band of which the two
This
paris are bent away from each other and are bent into polygonal form.
arrangement has the following advantages: it allows the same extent of surface to be
given to each coil, one half being on one side of the armature and the other on the
other side the several coils can thus join on to one another, so as to form a disc with
the greatest possible number of coils, while at the same time the disc armature is kept
very thin and consequently the poles of the opposite magnets can be brought very
close together and have a correspondingly powerful effect upon the armature.
Figs. 1 and 2 of the accompanying drawings shew respectively a front view and a
side view of the improved electrical generator. The disc armature A consists of coils

page_text: formed of copper bands as will be presently explained, and so arranged as to utilise
the largest possible amount of copper.
The armature is fixed upon the shaft B by means of two circular plates CC, the
parts being suitably insulated. The extremities of each coil extend to the commutator D
passing for this purpose through holes formed in the plate C.
The shaft B is carried in bearings EE' and carries in addition to the armature A
and the commutator D, the driving pulley P.
The hearings E E¹ are fixed on a base plate F which also carries the electro-
magnets M M, these being carried on zinc supports ZZ and so arranged that the
opposite poles are of a different sign, thus forming an arrangement in which the poles
are alternating.
It is well known that in existing disc machines the electromotive force is not
produced, as in the ring or cylinder machines, by the changing of the position of the
coils in an almost homogenous magnetic field, but is due to the motion of the coils in
a nonuniform magnetic field, that is to say in a magnetic field, the polarity of
which changes at regular intervals.
The electromotive force is consequently proportional: 1, to the surface of each
armature coil, 2, to the number of coils, 3, to the intensity of the magnetic field,
4, to the number of magnetic poles in one series, and 5, to the speed of the armature.
Now in all the disc machines of present construction, there are used a large number
of small electro magnets the cores of which are parallel to the axis of the armature.
According to the present invention a small number of magnets having a consider-
able mass of iron are used, these being greatly superior to those before described,
because for one and the same magnetising force, the intensity of the magnetic field
produced by two opposite magnets of large mass is greater than the sum of the
intensities of the magnetic fields produced by several pairs of electro magnets of the
same total mass as those first nanied.
Another loss of magnetism in existing disc machines is due to the parallel position
of each group of two contiguous magnets. In Fig. 3 let N and S represent the north
and south poles of two contiguous magnets. A great portion of the lines of force will
pass from the one to the other of these magnets instead of to the opposite poles of the
other series of magnets. These lines of force, although they become less dense
towards the neutral point n, produce lateral magnetic fields that are not passed
through by the armature, and that are consequently useless for the production of
electric current.
It has lately been endeavoured to increase the magnetic capacity of the system of
magnets by short circuiting the magnetic poles in a peculiar manner. For this
arrangement all the poles situated on the same side of the armature are of the same
name; the electromotive force is consequently only produced by the approach and
recession of the armature coils to and from the points where the intensity of the
simple magnetic field becomes greater or smaller, and this electromotive force is
necessarily less than if the magnetic field were alternating.
In addition, some parts of the coiling are rendered inactive either, as at Fig. 4,
where two iron cores X Y having the same polarity are placed closely side by side;
the current being made to pass in the same direction through both coils, it results
that in the contiguous parts thereof the currents pass in opposite direction, producing
at a a a neutralisation of the magnetising forces. This effect will also be produced in
machines where multiple magnets are used, that is to say a group of two or more
magnets of the same polarity in place of only one.
The arrangement of electro magnets employed according to this invention avoids
all these defects.
Figs. 2 and 5 of the drawings show a construction in which four electro magnets
are placed on each side of the armature, being so arranged that the like-named poles
of two contiguous magnets come together thus forming two north and two south
poles, those of the same name being diagonally opposite each other.
This combination of four magnets is placed so that the cores K lie parallel to the
plane of the armature disc, and at right angles to its axis, the relative arrangement of

page_text: the two sets of electro-magnets being such that the north and south poles of the one
set lie respectively opposite the south and north poles of the other set.
These two sets of magnets contain a considerable mass of iron and produce an
alternating magnetic field of great strength and density, while the armature moves
through all parts of the magnetic field. The cores K wound with the coils M, are
connected at their ends to polar pieces L, which may be of one piece of cast iron, and
which have the form shewn more clearly at Fig. 6, being made with flat enlargements b
that face the armature, while the other parts are all of rounded form with the
exception of the flat circular faces cd against which abut the corresponding circular
ends of the cores K, being secured thereto by any suitable means.
In making the surfaces rounded, where possible, the escape of magnetic lines of
force is prevented, as this always takes place at angles, as is well known.
Instead of arranging four electromagnets as described, any greater or less number
may be used, thus six or eight may be grouped together to form hexagons or octagons,
the poles being either at the angles, as at Fig. 7, or at intermediate points, as at
Fig. 8, or they may be arranged to form a ring, as at Fig. 9, or a single massive and
powerful magnet having two segmental polar extensions inay be used, as at Fig. 10.
In disc armature machines of present construction, the armature is formed by a
band of copper either of zig zag or of coiled shape, coiled round the centre of the
armature. In these cases the armature presents a considerable space where there is
no copper, or if in the one case the elementary coils are formed of several convolutions,
these become gradually smaller so that the electromotive force due to these additional
convolutions is insignificant, and moreover, the internal resistance is increased.
In the coils constructed according to this invention, each convolution is divided so
that one half thereof is situated on one side and the other on the other side of the
disc, the several convolutions being made to form bobbins having the same surface.
This is effected by dividing the copper band longitudinally into two as before
described, and bending the two lengths into various shapes, as shewn by way of
example at Figs. 11 to 20.
For producing a simple convolution a split copper band is used of the form shewn
at Fig. 11. This band is coiled on a mould so as to impart to it the shape shewn at
Fig. 12, and its ends are then secured by soldering or otherwise respectively to the
ends of the two contiguous coils, so that the right hand end of each coil is secured
to the left hand end of the next one.
The connection of the said ends is by preference effected by means of caps such as
shewn at Figs. 13 and 14, these being soldered thereto.
The form of coil shewn on the drawing has been chosen by preference because it
affords the greatest extent of surface and, at the same time, facilitates the junction of
the several coils with each other.
The coils formed as described and extending all round the armature, are divided
into a certain number of separate groups, each of which is put in contact with the
commutator by means of extensions to the end e of the first and last convolutions, as
shewn at Fig. 15.
The convolutions are of course insulated from each other by any suitable known
means. At the parts where the convolutions are farthest apart from each other it is
preferred to effect the insulation by means of small caoutchouc rings g Fig. 12,
whereby the armature is rendered less heavy than if the entire conductor were coated
with an insulator. If the copper bands for forming the coils have the configuration
shewn at Fig. 16, several convolutions can be made of one and the same piece of
metal. Fig. 17, 18 and 19 shew a construction in which the copper band, having the
configuration shewn at Fig. 17 imparted to it, is bent into the shape shewn at Fig. 18,
the long limb being connected by a cap with the short limb j of the contiguous
convolution. The limbs are for this purpose formed with several bands as shewn.
Fig. 19 shews a side view of the upper part of one of the convolutions. This figure
also shews the poles N and S of an electromagnet connected by a transverse bar of
soft iron, having for its object to emit lines of magnetic force acting upon the upper
parts of the coils, which have an oblique position relatively to the other part of the

page_text: disc. The tail of each convolution has a notch o or a projection p on each side serving
to keep them in place by fitting on a corresponding projection or in a corresponding
groove in the plates C.
In order to enable a greater number of convolutions to be employed the arrangement
shewn at Fig. 20 may be used, in which the lower part of each copper band is cut
away and replaced by a thinner and wider band k, so as to give the same amount of
surface. By this means the convolutions will be made to fit closer together.
The same construction of a split band may also be employed for forming an
armature of zig zag conductors, so as to fill out the entire area of the disc armature.
Fig. 21 shews an arrangement of this kind. Fig. 22 shews another form of
convolutions.
In this case the single convolutions do not all offer the same surface, as in the
preceding cases, but by using two or more sets of coils, those of the one set cover the
dead spaces of the other set; this arrangement is useful for small machines.
To prevent the coils from becoming deformed, there may be introduced between the
tops thereof, pieces of wood, and the whole may then be bound together by brass wires
soldered together; in this case there should be introduced between this wire and the
conducting parts of the armature a layer of mica or other insulating material, as at
Fig. 15.
In the arrangement shown at Fig. 23, two wheels Q, of which one is shewn, are
formed with spokes or arms Q and, the one wheel being placed on a flat surface, the
copper coils are introduced into the spaces between the spokes, whereupon the other
wheel is placed over it and is fixed thereto.
For collecting the currents from the coils by the commutator various arrangements
may be employed for grouping them in quantity or in series. If the number of
convolutions forming an elementary coil is divisible by four (the number of magnetic
fields) they may be directly connected to the blocks of the commutator, in employing
four brushes grouped in pairs diametrically opposite each other; in this case the
arrangement is for quantity. The same result might be obtained in using only two
brushes, by connecting together in pairs the ends of the diametrically opposite coils.
If the number of convolutions is not divisible by two, there being still four magnetic
fields, the connections are made as shewn at Fig. 24. In this case all the coils are in
tension the electromotive force obtained by this means will be about double that
obtained in the previous case, but the intensity of current will be about one half.
If the number of convolutions is divisible by two but not by four, the connections
can be made as at Fig. 25. The coils are then in tension and as the diametrically
opposite blocks of the commutator are connected together, those blocks that do not
appear to be connected with a certain coil are in reality in connection with the opposite
coil. In consequence of there being four pairs of magnetic poles arranged at right
angles, the current is in the same direction in the diametrically opposite parts of the
armature there are, therefore, four different circuits in the armature, the difference
f potential being always greatest at right angles.
The currents can therefore be taken up by four brushes arranged at right angles,
if the coils are directly connected to the blocks of the commutator; or by only two
brushes placed at right angles, if the diametrically opposite coils are connected either
directly or by the blocks of the commutator.
As the armature operates as a fan it is always kept cool by the currents of air
produced.
DJ 31
ד י.
1303
ABEL & IMRAY,
Agents for the Applicant.

page_text: COMPLETE SPECIFICATION.
Improvements in Disc Dynamo or Magneto Electric Machines.
1, CHARLES DENTON ABEL of No. 28 Southampton Buildings Chancery Lane
in the County of Middlesex Consulting Engineer and Patent Agent 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
In all disc dynamo or magneto electric machines of present construction the object
is to have a very powerful magnetic field or inductor, this being obtained by placing
the magnets very close to each other. It is also endeavoured to avoid as much as
possible the heating of the armature, caused by the Foucault currents in the iron cores.
Furthermore, it is endeavoured to utilise as much as possible the copper wire of the
armature by placing it entirely in the magnetic field, as distinguished from the
cylindrical armature machines in which the portion of the wire at the two ends of the
cylinder serves only to connect the other parts in circuit without in any way adding to
the power of the machine.
The present invention has for its object a novel construction of disc dynamo or
magneto electric machine which I will proceed to describe with reference to the
drawings accompanying my Provisional Specification and which attains the above
objects in a very perfect degree, while avoiding the defects of existing machines.
According to this invention, the disc armature is formed by a series of coils grouped
round a central shaft, each coil being formed by a split copper band of which the two
parts are bent away from each other and are bent into polygonal form. This arrange-
ment has the following advantages:-it allows the same extent of surface to be given
to each coil, one half being on one side of the armature and the other on the other
side the several coils can thus join on to one another, so as to form a disc with the
greatest possible number of coils, while at the same time the disc armature is kept
very thin and consequently the poles of the magnets can be brought very close together
with correspondingly powerful effect upon the armature.
Figs. 1 and 2 of the drawings accompanying my Provisional Specification shew
respectively a front view and a side view of the improved electrical generator. The
disc armature A consists of coils formed of copper bands as will be presently explained,
and so arranged as to utilise the largest possible amount of copper.
The armature is fixed upon the shaft B by means of two circular plates CC, the
parts being suitably insulated. From the extremities of each coil wires extend to the
commutator D passing for this purpose through holes formed in the plate C.
The shaft B is carried in bearings EE and carries in addition to the armature A
and the commutator D the driving pulley P.
The bearings E E' are fixed on a base plate F which also carries the electro
magnets MM; these are carried on zinc supports ZZ which insulate them
magnetically and are so arranged that the opposite poles are of a different sign thus
forming an arrangement in which the poles are alternating.

page_text: It is well known that in existing disc machines the electro motive force is not
produced, as in the ring or cylinder machines, by the changing of the position of the
coils in an almost hemogeneous magnetic field, but is due to the motion of the coils in
a non-uniform magnetic field, that is to say in a magnetic field, the polarity of which
changes at regular intervals.
The electro motive force is in this case proportional: 1st, to the surface of each
armature coil; 2dly, to the number of coils; 3dly, to the intensity of the magnetic
field; 4thly, to the number of magnetic poles in one series; and 5thly, to the speed
of the armature.
Now in all the disc machines of present construction, there is used a large number
of small electro magnets the cores of which are parallel to the axis of the armature.
According to the present invention, on the other hand, a small number of magnets
having a considerable mass of iron is used, these magnets being greatly superior to
those before described, because for a given magnetising force, the intensity of the
magnetic field produced by two single opposite magnets of large mass is greater than
the sum of the intensities of the magnetic fields produced by several pairs of electro
magnets of the same total mass as the two larger magnets.
Another loss of magnetism in existing disc machines is due to the parallel position
of each group of two contiguous magnets. In Fig. let N and S represent
respectively the north and south poles of two contiguous magnets. A great portion of
the lines of force passes from the one to the other of these magnets instead of to the
opposite poles of the other series of magnets. These lines of force, although they
become less dense towards the neutral point n, produce lateral magnetic fields that
are not passed through by the armature, and that are consequently useless for the
production of electric currents.
It has lately been endeavoured to increase the magnetic capacity of the system of
magnets by short circuiting the magnetic poles in a peculiar manner by bridging.
For this arrangement all the poles situated on the same side of the armature are of
the same name; the electromotive force is consequently only produced by the approach
and recession of the armature coils to and from the points where the intensity of the
simple magnetic field becomes greater or smaller, and this electromotive force is
necessarily less than if the magnetic field were alternating.
Besides, some parts of the coiling are rendered inactive, as at Fig. 4, where two iron
cores XY having the same polarity are placed closely side by side; the current being
made to pass in the same direction through both coils, it results that in their contiguous
parts the currents pass in opposite directions producing at a a neutralisation of the
magnetising forces. This effect is also produced in machines where multiple magnets
are used that is to say several cores for one polarity.
The arrangement of electro magnets employed according to this invention avoids all
these defects.
Figs. 2 and 5 of the drawings shew a construction in which four electro magnets
are placed on each side of the armature, being so arranged that the like nained poles
of two contiguous magnets come together, thus forming two north and two south poles,
those of the same name being diagonally opposite each other.
The cores K lie parallel to the plane of the armature disc, and at right angles to
its axis, the relative arrangement of the two sets of electro-magnets being such that
the north and south poles of the one set lie respectively opposite the south and north
poles of the other set.
These two sets of magnets contain a considerable mass of iron and produce an
alternating magnetic field of great strength and density and the armature moves
through all parts of it. The massive soft iron cores K wound with the coils M, are
connected at their ends to pole pieces L, which may be of one piece of cast iron, of
the form shewn at Fig. 6 being made with enlargements that face the armature,
while the other parts are of rounded form except the flat faces cd to which are fixed
the ends of the cores K.
By making all the parts except bed rounded, escape of magnetic lines of force is
prevented, as this always takes place at angles and edges, as is well known,

page_text: Instead of arranging two pairs of electro magnets as described, any greater or less
number of pairs may be used, thus six or eight may be grouped together to forni
hexagons or octagons, the poles being either at the angles, as at Fig. 7 or at
intermediate points, as at Fig. 8, or they may be arranged to form a ring, as at
Fig. 9, or a single massive and powerful magnet having two segmental polar extensions
may be used, as at Fig. 10.
In
In disc armature machines of present construction, the armature is formed by a
band of copper either of zig-zag form or coiled round the centre of the armature.
these cases the armature presents a considerable space where there is no copper, or if,
in the one case, the elementary coils are formed of several convolutions, these become
gradually smaller so that the electro motive force due to these additional convolutions
is insignificant, and moreover, the internal resistance is increased.
In the coils constructed according to this invention, each convolution is divided
so, that one half thereof is situated on one side and the other on the other side of the
disc, the several convolutions being made to form bobbins having the same surface.
This is effected by dividing the copper band longitudinally into two as before
described, and bending these two lengths into various shapes, as shewn by way of
examples at Figs. 11 to 20.
In producing a single convolution a split copper band is used of the form shewn
at Fig. 11. This band is coiled on a mould so as to impart to it the shape shewn at
Fig. 12 and its ends are then secured by soldering or otherwise respectively to the
ends of the two contiguous coils, so that the right hand end of each coil is secured to
the left hand end of the next one.
The connection of the said ends is by preference effected by means of caps such as
shewn at Figs. 13 and 14 these being soldered thereto.
The form of coil shown on the drawing has been chosen by preference because it
affords the greatest extent of surface and, at the same time, facilitates junction of the
several coils with each other.
The coils formed as described and extending all round the armature are divided
into a certain number of separate groups, each of which is connected to the commutator
by means of extensions f to the ends e of the first and last convolution as shown at
Fig. 15.
The convolutions are of course insulated from each other by any suitable known
means. At the parts where the convolutions are farthest apart from each other it is
preferred to effect the insulation by means of small caoutchouc rings Fig. 12
whereby the armature is rendered less heavy than if the coils were bedded in a massive
insulator. If the copper bands for forming the coils have the configuration shewn at
Fig. 16 several convolutions might be made of one piece of metal. Figs. 17, 18
and 19 shew a construction in which the copper band cut to the shape Figure 17 is
bent to the shape shown at Fig. 18, the long limb h being connected by a cap i with
the short limbj of the continuous convolution. The limbs are bent several times as
shewn. Fig. 19 is a side view of the upper part of one of these convolutions. This
figure also shows the poles N and S of an electromagnet and a piece F of soft iron,
having for its object to emit lines of magnetic force to act upon the upper parts h of
the coils, which have an oblique position on the armature. The tail of each convolu-
tion has a notch o or a projection p on each side serving to keep the coils in position
by fitting on a corresponding projection or in a corresponding groove in the
plates c.
In order to enable a greater number of convolutions to be employed the arrangement
shewn at Figure 20 may be used in which the lower part of each copper band is cut
away and replaced by a band k thinner but wider so as to give the same section.
Thus the convolutions can be made closer together.
The same construction of a split band may also be employed for forming an
armature of zig zag arrangement so as to fill the entire area of the disc. Fig. 21
shews an arrangement of this kind. Fig. 22 shews another form of convolutions.
In this case the single convolutions do not all offer the same surface, as in
the preceding cases, but by using two or mere sets of these coils, those of the

page_text: one set cover the dead spaces of the other set; this arrangement is useful for
small machines.
To prevent the coils from becoming deformed, there may be introduced between
the tops thereof, pieces of wood, and the whole may then be bound together by brass
wires soldered together; in this case there should be introduced between this wire and
the conducting parts of the armature a layer of mica or other insulating material,
as at Fig. 15.
In the arrangement shown at Figure 23, two wheels Q, of which one is shewn, are
formed with spokes or arms Q and, the one wheel being placed on a flat surface, the
copper coils previously prepared are introduced into the spaces between the spokes,
whereupon the other wheel is placed over it and is fixed thereto.
For collecting the currents from the coils by the commutator, various arrangements
may be employed for grouping them in quantity or in series. If the number of
convolutions forming an elementary coil is divisible by four (the number of magnetic
fields) they may be directly connected to the plates of the commutator which has
four brushes grouped in pairs diametrically opposite; this is the arrangement for
quantity. The same result might be obtained with only two brushes, by connecting
together in pairs the ends of the diametrically opposite coils. If the number of
convolutions is not divisible by two, there being still four magnetic fields, the connec-
tions are made as shown at Fig. 24. In this case all the coils being in tension, the
electro motive force is about double that obtained in the previous case, but the current
will be about one half.
In
If the number of convolutions is divisible by two but not by four, the connection
can be made as at Fig. 25. The coils are then in tension and as the diametrically
opposite plates of the commutator are connected together those plates that do not
appear to be connected to a coil are in reality in connection with the opposite coil.
consequence of there being four pairs of magnetic poles arranged at right angles, the
current is in the same direction in the diametrically opposite parts of the armature;
there are, therefore, four different circuits in the armature, the difference of potential
being always greatest at right angles.
The currents can therefore be taken up by four brushes arranged at right angles, if
the coils are directly connected to the plates of the commutator; or by only two
brushes placed at right angles, if the diametrically opposite coils are connected either
directly or by the commutator plates.
As the armature operates as a fan it is always kept cool by the currents
of air.
Having now particularly described and ascertained the nature of my said invention
and in what manner the same is to be performed I declare that what I claim is :-
1. For an electro machine, a disc armature formed by bands of copper separated
from one another, bent to a polygonal profile, each convolution having the same
surface, half on each side of the armature, and the different convolutions being
connected substantially as described with reference to Figs. 12, 13, 14 and 15.
2. Forming each convolution of a band of copper split lengthwise to near one end,
half turned on each side of the armature in opposite directions, substantially as described
with reference to Figures 11 to 20 inclusive.
3. For the convolutions applied as in the preceding claim, bands formed as shewn
in Figs. 11, 16, and 17.
4. Forming zig-zag coils as shown in Figs. 21 and 22.
5. Connecting the coils formed as above described to the commutator in several
groupings, the currents of which are collected by brushes as shewn in Figure 15.
6. Forming the connections of groups of coils to the commutator as shown in
Figs. 24 and 25.
7. Connecting each convolution to the next by a cap as shewn in Figs. 12, 13
and 1.
8. Fixing the coils in position by notches and projections engaging with each other
as shewn in Figs. 11, 12, 17 and 18.

page_text: 9. The construction of armature having its coil beld between two wheels as shewn
in Fig. 23.
10. The construction of the electro magnets each of a mass of iron in one piece
wound with wire, these magnets presenting at equal distances alternate poles facing
opposite poles of similar magnets on the other side of the revolving armature as shewn
in Figs. 1, 2, and 5.
11. The arrangement of the electro magnets with their pole pieces relatively to the
armature as shewn in Figs. 1, 5 and 6.
12. Constructing and arranging a pair of electromagnets each of a single piece of
iron, straight, polygonal or circular, with pole pieces at the angles or the middle, and
with wire coiled on to it so as to develop alternate poles, between which pair the
armature revolves as described with reference to Figs. 2, 5, 7, 8, 9 and 10.
13. The use as described with reference to Fig. 19 of a supplementary magnetic
piece connecting the two poles and acting on the upper part of the convolutions shewn
in Fig. 18.
14. The general construction of electro machine, as described with reference to
Figs. 1 and 2.
11:
1712
1007