Improvements in Dynamo-machines and Electric Motors.
Year: 1886

page_text: Date of Application, 19th Apr., 1886.
Complete Left, 12th Jan., 1887.
Complete Accepted, 17th June, 1887.
PROVISIONAL SPECIFICATION.
Improvements in Dynamo-machines and Electric Motors.
I LOUIS BOLLMANN of 1I. Obere Donaustrasse No. 93 in Vienna in the Empire
of Austria Engineer, do hereby declare the nature of this invention to be as
follows:-
My invention, relating to improvements in dynamo-machines and electric motors,
consists in the application of iron for certain parts of the rotating armature, which
have till now been made of copper, in order that the same, while rotating between the
magnet poles of the field, are alternatingly magnetized, and thereby increase the
electromotive force of induction, by inducting in those similar parts, which lay
alongside of them, powerful electric currents of heigh tension.
To simplify this specification I will prelimilarily assume, that the armature is
constructed according to the specification of my British Letters Patent No. 14779,
granted to William Robert Lake, and dated November 8th 1884, to which I herewithi
refer in the following description.
In the annexed drawings, the figures 1, 2 and 3 are diagrams, to explain the
nature of the magnetic induction in the armature according to this system.
Figures 4, 5 and 6 refer to an improvement in collector-brushes, not belonging to
this application.
Fig. 1 is a diagram of a single group of windings, out of which the arinature is
compounded; it consists of 10 radial parts P, connected by segments R¹ R", so as to
form a fivefold flat coil, reaching from one pair of poles to the next pair. The
parts R R are however in reality situated not alongside of each other, as shown in
the figure, but one over the other, as fully explained in the specification above refered
to the Fig. 1 is only intented to show the windings better.
The armature consists of a number (say 24 to 48) of such groups, which are placep
in one another, to form a disk.
In Fig. 1 are S and N the faces of two poles, laying below the parts P ; the opposite
poles, which would cover the lower ones, are supposed to be removed.
The effective resultants of the magnetic molecular currents of the poles are indicated
by the arrows A, according to the hypothese of Ampère; they represent electric
G

page_text: currents, circulating around the poles in the direction of a clockhand in the south-
pole S, and vice versa in the nordpole N, when looked at towards the face.
When the ironparts P approach the poles in the direction of the arrow Z, they are
magnetized, and the magnetic molecular currents thereby excited in them, circulate
in the same direction as those of the poles they approach; they flow downwards on
one side of the parts P, and upwards on the other side, the same as in the poles.
These directions are indicated by the arrows C. In so far as these molecular currents
begin or grow during the approach to the poles, they act inducting on the parts laying
closely alongside.
Thus the ampèric currents on the left side of the part 1 (Fig. 1), are flowing
downwards; therefore, they will induct in part 2 a current in the downward direction,
as is indicated by the arrows D. But the part 3 is also magnetized, so that its
molecular currents on its right side, (which there flow downwards), will induct on the
part 2 in upward direction. The part 2 is therefore inducted simultaneously from two
sides in opposite directions. But as 1 is situated nearer to the pole S, than 3, its effect
is more powerful; therefore the part 2 is inducted by the difference of the electromotive
forces of the parts 1 and 3, which produces in it a current in downward direction.
A similar differential induction takes place in all radial parts P in this and all
other groups. The endparts 1 and 5 are in same manner inducted by those parts,
belonging to the next groups. The parts 6 to 10 of the same group, approach the
northpole N, and are in like manner, but in opposite direction inducted, so that the
currents from both sides will combine and strengthen each other.
These inductions grow in all parts so long, untill they reach the middle of the poles ;
then retreating again, as represented in Fig. 2, the magnetism vanishes or declines,
which causes an induction in equal directions to the molecular currents. The part 5
being now the nearest to the pole S, is the strongest magnetical, and will therefore
induct the part 4 in downward direction, which is equal to the ampèric current on its
right side next to part 4. This induction is again proportional to the difference of the
electromotive forces of 5 and 3.
The directions of the currents, inducted during the approach and retreat, are equal,
and in all positions of the parts in relation to the poles the same as those, which would
be produced, if the parts P were made of copper. Both systems of induction can
therefore be used simultaneously, and will then support and strengthen each other.
When the group arrives at the middle of the line xy, the magnetism of its parts
has vanished, and the induction is at an end, because they are then at an equal distance
from the poles S N, which both tend to magnetize in opposite sense. Going on
further, the parts approach then the next poles, which causes the same inductions in
opposite directions.
In regard to the circumstance, that these inductions are produced by the differences
of the opposite magnetic actions on both sides of each part P, it is to be remarked,
that in the sense of the hypothese of Ampère, magnetic inductions do always depend
on similar differential actions.
The ampèric currents, circulating around the poles, are in reality the resultants of
the effect of all molecular currents within the mass of the iron, where they cross and
annul each other to a great extent. These opposite magnetic influences do not produce
two currents, which then combine and equlize or annul each other, but they are like
opposite forces, tending to move a body; there will then be only one motion in one
direction, and the energy thereby consumed is proportional only to the difference of
the forces, multiplied by the distance of the motion.
We know of two. kinds of magnetic induction, viz. : a, an induction caused by a
motion of a conductor in a magnetic field, with application and consumtion of
mechanical energy; b, an induction caused through the beginning or vanishing
of magnetism in iron, situated near a conductor, without mutual motion between the
inducting and inducted parts; hereby the energy of the inducting magnetism is
consumed.
The induction, which takes place in the copperparts P, according to the system
described in the specification above refered to, is in accordance to the action a;

page_text: but the magnetic induction of the present system is produced according to b, because
the ironparts do not move mutually, and the current is inducted only by the alternations
of the magnetism.
Suppose the opposite poles of a horse-shoe magnet to be closed by an ironpiece,
laying across them; if this piece is pulled off, its magnetism will vanish, and thereby
induct within a coil surrounding it, a current, whose energy corresponds to that of the
vanishing magnotism. An equal powerful but opposite current is produced, when
the iron is replaced again.
The work consumed, corresponds to the force required for the removal of the iron
from the poles being greater than that, which attracts it during the approach. If for
example, these motions are very slow, the iron is fully saturated so far, as at every
moment corresponds to its distance from the poles ; no work is then consumed, and
consequently no induction can take place. But if the iron is quickly removed, its
magnetism cannot vanish so rapidetly; therefore the force of attraction is stronger
than the distance of the iron from the poles requires. Again, during tho quick
approach, the magnetism of the ironpieco cannot be developed so quickly, therefore
the force of attraction remains weaker, and less work will be generated during the
approach, than is consumed during the removal.
Now in this armature, each radial piece P represents one of such closing ironpieces,
and there are constantly retreating and approaching a number of them from or towards
each pair of poles, so that the attractions of approach are counterbalanced by the
attraction of retreat; there remains therefore only that amount of working energy to
be supplied for the rotation of the armature, which corresponds to the difference of
attractive forces.
The rapid change of the magnetism is opposed by the current inducted within the
parts P, which during the magnetisation of the latter, flows in opposite direction to
the growing magnetic-molecular currents, and thereby restarts the magnetizing, by
tending to magnetize the iron in the contrary sense. During the demagnetisation of
these parts, the currents flow in equal direction to the ampèric-currents, and tend to
maintain the magnetism.
While each part P is getting magnetized or demagnetized, secondary currents are
inducted in the next. There being no mutual motion between these parts, the energy
of the inducted current must be produced at the cost of the energy of the magnetism,
which however is instantaneously regenerated by the fieldmagnets, whereby motive-
power is consumed.
Although the iron has more resistance than copper, the entire resistance will be still
less, than in most other armatures, because the entire length of the conductors, through
which the current must flow, is less, and its sectional area larger. The ironpieces P,
passing closely between the opposite poles, are most intensively magnetized, therefore
the disk can be made thicker, so that the parts P will get more broad than such of
copper, which lessens their resistance.
If the segments R R are also made of iron, there will be an alteration of
magnetism and a useful induction in these parts also; the latter is however weak in
proportion to that in the parts P, therefore I believe it may in some cases be better, to
make them of copper, to lessen the resistance.
This system can be modified in various ways. To increase their conductive
capability, the ironparts may be covered with copper; or insulated strips of copper
or wire may be run lengthways between the ironparts, in which the current is inducted
by the magnetism of the ironparts, whereby very high tension currents
produced.
may be
If the armature is constructed in the form of a drum, the parts P and R' R¹
may be made of copper, and mounted on a hollow drum of iron, fastened to the main-
shaft. The poles may then be situated only on the outside of the drum. Fig. 3 is a
diagram, explaining the nature of such an arrangement. S, N, S, are magnets,
standing side by side; K is a plate of iron, to which are fastened the insulated copper-
armature parts P.
The plate K forms an iron connection of the poles S³, N¹, S¹, which are south (S')

page_text: and north (N¹). The directions of the amperic molecular currents formed in the poles
and ironplate, are indicated by arrows in the figure, which is a plane view, showing
the molecular rotations at right angle to the axis of motion. These directions change
from one pole to the next at an angle of 180 degrees, and if the plate K moves
towards the right or left, the motion of cacli molecule must change its direction to that
amount. This causes a magnetic induction in the parts P, situated between the poles
and the plate K, and moving with the latter. These parts P are also inducted directly
by their motion before the poles; both of these inductions correspond in directions,
and will therefore strengthen the inducted current.
Now if the bar K and the armature P are supposed to be in form of a drum, and
the magnets placed arround them, we have the drum armature above mentioned. It
is obvious, that these parts K and P may be as well made in form of a disk or
ring. Two armatures, each formed unilateral may be placed one on each side of the
ironplate K, and then magnetpoles arranged on each side; but in this case the poles
opposite to one another would have to be of equal polarity.
To prevent Foucault currents, the ironplate K, be it in form of a drum, disk or ring,
may be made of insulated wire or strips of iron."
For machines of small dimensions, I prefer to arrange the parts in the following
manner The armature, with the parts P of iron, is made in the form of a holow
drum, one end of which is connected to a hub fastened to the shaft, and the other end
oppen, so that the ends of the parts P are freely suspended.
In front of the open end of this drum-armature stands a large electromagnet with a
hollow ironcore, through which the mainshaft passes. The ends of this core towards
the drum is prolongated, and reaches into the inside of the drum; it has there several
(say 6) narrow radial projections, like the cogs of a pinion, which reach to the inner
edges of the ironparts P of the armature, and serve as inside magnetic poles.
On the other end of the core, farthest away from the drum, there are fastened as
many arms, as there are inner poles (say 6), which reach forewards over the outside of
the drum in such a way, as to form opposite poles to the inner ones, a free space being
between the inner and outer poles, for the drumarmature to rotate freely. All inner
poles are here of equal polarity, and so are all outer ones, but these standing opposite
one another, are of different polarity. The principle of action of such arrangement
of poles
similar to that, explained in the above mentioned specification and illustrated
by the Figures 19 and 20 of the same.
The disposition of the segments R₁ R" must be somewhat different, so as to leave
the inside of the open end of the drum free. The space between the end of the
drum and the beginning of the arms forming the outside poles, is fully wound with
insulated copper wire, to form the magnet. The shaft bears on one end in the core,
and on the other end (which also carries the collector), in a seperate bearing.
Although I have refered herein to my patent No. 14779 above mentioned, I wish it
to be understood that this system of magnetic induction may also be applied to other
forms and constructions of the armature.
Dated this
day of AD 1886

page_text: Improvements in Dynamo-machines and Electric Motors.
I LOUIS BOLLMANN an Engineer of 93 Obere Donaustrasse in the city of Vienna,
in the Empire of Austria-Hungary, do hereby declare the nature of my invention for
IMPROVEMENTS IN DYNAMO-MACHINES AND ELECTRO-MOTORS, and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following statement :-
This invention consists in the application of iron for certain parts of particular
kinds of rotating armatures, which have till now been made of copper, in order that
the same, while rotating between the poles of the fieldmagnets, are alternatingly
magnetized and thereby induct in those similar parts, which lay closely alongside of
them, powerful electric currents of high tension.
To simplify this specification, I will preliminarily assume, that the armature is
constructed according to the specification of my British Letters Patents No. 14779
granted to William Robert Lake and dated November 8th 1884, to which I herewith
refer in the following description.
In the annexed drawings (which are like those of the provisional specification)
Figs. 1, 2 and 3 are diagrams to explain the nature of the magnetic induction in the
armature according to this system. The other Figures refer to an improvement in
collector brushes, which does not belong to this application.
Fig. 1 is a diagram of a single group of windings, out of which the armature is
compounded; it consists of 10 radial parts P, connected by segments R₁R", so as to
form a fivefold flat coil, reaching from one pair of poles to the next pair. The
parts R R are however in reality not situated alongside of each other, as shown in
this figure, but one over the other, as is fully explained in the specification above
refered to, the Fig. 1 being only intented to show the windings more clearly.
The armature consists of a number (from 24 to 48) of such groups, placed one in
another to form a disk.
S and N are the faces of two poles of the fieldmagnets, laying below the parts P ;
the opposite poles of the fieldmagnets above, which would cover the lower ones, aro
supposed to be removed.
The effective resultants of the magnetic molecular currents of the poles, according
to the hypothese of Ampère, are indicated by the arrows A; they represent electric
currents, circulating around the poles in the direction of the motion of a clockhand
around the southpole S, and vice versa around the northpole N, when looked at
towards their faces.
When the ironparts P approach the poles in the direction of the arrows Z, they are
magnetized and the magnetic molecular currents thereby excited in them, circulate in
the same direction as those of the poles they approach; they flow on one side of the
parts P downwards, and upwards on the other side, the same as in the poles. These
directions are indicated by the arrows C.
In so far as these molecular currents begin or grow during the approach to the
poles, they act inducting on those parts, laying closely alongside of them; thus the
Ampère-currents on the left side of the part 1 (Fig. 1) are flowing upwards; therefore
they induct in part 2 a current in the downward direction, as is indicated by the
arrows D. But the part 3 is also magnetized, so that its molecular currents on its
right side (which there flow downwards) induct in the part 2 a current in upward

page_text: direction. The part 2 is therefore simultaneously, inducted from two sides in
opposite directions; but as 1 is situated nearer to the pole S than 3, its effect is more
intense; the part 2 is therefore inducted by the difference of the electro-motive forces
of the parts 1 and 3, which produces in it a current in downward direction.
Similar differential inductions are produced in all radial parts P in this and all other
groups. The parts 1 and 5 at the ends, are in the same manner inducted by those
parts, belonging to the next groups. The parts 6 to 10 of the same group approach
the northpole N, and are inducted in like manner, but in the opposite direction, so that
the currents from both sides of the coil will combine and strengthen each other.
These inductions grow so long, until the parts P reach the middle of the poles ;
then they retreat again from the latter, as is shown in Fig. 2. The magnetism declines
or vanishes now, which produces an induction in equal direction to the molecular
currents. The part 5 being now the nearest to the pole S, is the strongest magnetic
one, and inducts therefore the part 4 in downward direction, which is equal to the
ampèric currents on its right side next to part 4. This induction is again proportional
to the difference of the electromotive forces of 5 and 3.
The directions of the currents, inducted during the approach and retreat, are equal and
in relation to the poles in all positions of the parts the same as those, which would be
produced, if the parts P were made of copper. Both systems of induction can
therefore be used simultaneously, and will then support and strengthen each other.
When the group arrives at the middle of the line xy, the magnetism of its parts
has vanished, and the induction is ended, because they are then at an equal distanco
from the poles S N, both of which tend to magnetize in opposite sense.
As the parts
go on further, they approach then the next poles, which causes the same inductions in
opposite directions.
In regard to the circumstance, that these inductions are produced by the differences
of the opposite magnetic actions on both sides of each part P, it is to be remarked,
that in the sense of the hypothese of Ampère, magnetic inductions do always depend
on similar differential actions. The Ampèric currents supposed to circulate around
the poles, are in reality only the resultants of the effects of all molecular currents
within the ironmass, where they cross and annul each other to a great extent. These
opposite magnetic influences must be supposed not to produce two currents, which then
combine and annul each other, but to act like opposite forces, tending to move a body,
which produces only one motion in one direction.
We know of two methods of producing magnetic induction, viz.: a, by a motion
of a conductor in a magnetic field with application and consumption of mechanical
energy; and b, by the beginning or vanishing of magnetism in iron, situated near a
conductor, without mutual motion between the inducting and inducted parts, whereby
the energy of the inducting magnetism is consumed.
The induction in the copper parts P, according to the system described in the
specification above refered to, takes place according to the method a; but that of
the present system is produced according to method b, because the ironparts P do not
move mutually to each other, and the current is only inducted by the alternations of
the magnetism.
;
Suppose the poles of a horseshoe magnet to be closed by an ironpiece, laying across
them if this piece is pulled off, its magnetism vanishes, and inducts a current within
a coil, surrounding it, whose energy corresponds to the energy of the vanishing
magnetism. An equal but opposite current is inducted, when the iron is replaced.
The work thereby consumed corresponds to the difference of forces, which are required
to remove the ironpiece, and which is gained by replacing it, and depends on the speed
of the motions. If the notion is very slow, the iron will be fully saturated so far, as
at every moment corresponds to its distance from the poles; no work is then consumed,
because the attration is the same during removal and approach of the piece;
consequently no induction can then take place.
But if the piece is quickly removed, its magnetism cannot vanish so rapidetly,
therefor the force of attraction is stronger than the distance from the poles requires.
Again, during the quick approach, the magnetism of the ironpiece cannot be developed

page_text: so quickly, therefore the attraction remains weaker, and less work will be generated
during the approach, than has been consumed during the removal.
Now in this armature each radial piece P represents such a closing ironpiece, and
there are constantly approaching and retreating an equal number towards and from
each pole; the attractions of approach counterbalance to a great extent those of retreat,
there remaining only that amount of work to be supplied for the rotation of the
armature, which corresponds to the difference of attractive forces. The rapid change
of magnetism is opposed by the current inducted within the parts P, which, during
the magnetisation of the latter, flows in opposite direction to the growing molecular
currents, and thereby retards the magnetizing, by tending to magnetize the iron in
the contrary sense; and during demagnetisation of these parts flows in equal direction
to the vanishing molecular currents, which tends to maintain the magnetism. While
each part P is getting magnetized or demagnetized, currents are inducted in the next;
there being no mutual motion between them, the energy of the inducted current must
be produced at the cost of the energy of the magnetism, which however is
simultaneously regenerated by the field magnets, whereby motive power is consumed,
which corresponds with the dynamical energy of the current produced.
Although the iron has more resistance than copper, the entire resistance will be less,
than in most other constructions of armatures, because the entire length of the
conductors, through which the current must flow, is less, and their sectional areas are
larger. The ironpieces P, passing closely between the opposite poles of the field-
magnets, are most intensively magnetized; the armature disk can therefore be made
thicker, so that the parts P will get broader than such of copper, which lessens their
resistance.
If the segments R R are also made of iron, there will be an alternation of
magnetism and a useful induction in them also; such induction is however weak in
proportion to that in the parts P; therefore it will be in most cases better, to make
them of copper, to lessen the resistance.
This system can be modified in various ways. The ironparts may be covered or
connected with copper, to increase their conductive capability; or insulated strips of
copper or wire may be led lengthways between the ironparts P, in which the current
is inducted by the alternating magnetism of the ironparts, whereby a very high-
tension-current can be produced.
If the armature is constructed in the form of a drum, the parts P and R' R
may be made of copper, and mounted on a hollow drum of iron, fastened to the
mainshaft. The poles may then be situated only on the outside of the drum.
Fig. 3 is a diagram explaining the nature of such an arrangement. SNS are
magnets, standing side by side; K is a plate of iron, to which are fastened the
insulated copper armature-parts P.
This plate K forms an iron connection of the poles S₁ N' S¹; S₁ being southpoles
and N northpoles. The directions of the Ampère molecular currents, formed in the
iron and poles, are indicated by arrows in the Fig. 3, which is a plane view, showing
the molecular rotations at right angles to the axes of motions. These dirrections
change from one pole to the next at an angle of 180 degrees, and if the plate K moves
to the right or left, the motion of each molecule must change its direction to that
amount. This causes a magnetic induction in the parts P, situated between the poles
and the plate K, and moving with the latter.
The parts P are hereby also inducted directly, in consequence of their motions
between the poles; both of these systems of induction produce, in every position of
the parts, currents of equal direction, and will therefore support each other and
increase the tension of the current.
Supposing the bar K, and the armature P, of Fig. 3, to be arranged circular in
form of a drum, and the magnets placed around them, we have the drumarmature
above mentioned; it is obvious, that these parts may as well be made in the form of a
disk or ring.
Two armatures, each formed unilateral, may be placed on each side of the iron-
plate K (supposed to be then in form of a disk) and fieldmagnet poles arranged on each

page_text: side; but in this case, the poles opposite to one another would have to be of equal
polarity.
To prevent Foucaults currents, the ironplate K (be the same in form of a drum,
disk or ring) may be made of insulated wire or strips of iron.
For machines of small dimensions I prefer to arrange the parts in the following
manner: The armature with the parts P of iron, is constructed in the form of a drum,
one end of which is connected to a hub, fastened to the shaft, and the other end is
open, so that the ends of the parts P are at the open end freely suspended. The
connections or segments R¹ R" are arranged in four rows on each end of the drum, on
the principle explained in the specification above refered to.
In front of the open end stands a large electromagnet, having a hollow ironcore
through which the main shaft passes; its one end is prolongated, to reach into the
inside of the drum, and has there several (say 6) projections, like the cogs of a pinion,
which reach closely to the inner surface of the drum; formed by the narrow edges of
the ironparts P, and serve as so many inside magnetpoles.
On the other end of the large core, fartherst away from the drum, thero are as many
ironarms fastened, as there are innerpoles (say 6); they reach forewards over the
outside surface of the druin in such a way, as to form opposite poles to the inner ones,
leaving a free space between the inner and outer poles, within which the projecting
parts P, forming the drum, rotate freely. All inner poles are here of equal polarity,
and so are all outer ones; but those standing opposite one another are of different
polarity. The principle of action of this arrangement of the poles is similar to that,
explained in the above refered specification and illustrated by the diagrams Figs. 19
and 20 of the same.
The disposition of the segments R' R" requires to be somewhat different, so as to
leave the inside of the open end of the drum without projections, in order that the
inside poles can enter freely. I make therefore the four rows of R¹ all on the outside
of the drum. That part of the ironcore, situated between the open end of the drum
and the beginning of the 6 arms, which form the outside poles, is fully wound with
insulated copperwire to form the fieldmagnet (which is a bellmagnet according to the
system of Nickles. The shaft bears at one end in the core, and at the other end,
which carries the collector, in separate bearings.
Although I have herein refered to my specification of the patent above mentioned,
I wish it to be understood that this improvement may be applied also to other similar
armatures, having the conductors of the current bent zigzag or in the form of flat
spirals, as herein described.
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:
I. In an armature of the above description,-viz.: such with conductors of the
current shaped zigzag or in the form of flat spirals, to make the said conductors
partly or entirely of iron, in order that they, while moving through the magnetic field
of the stationary fieldmagnets, are alternatingly magnetized, and thereby induct
electric currents within those like or similar conductors, which lay closely and parallel
to them, as herein set forth.
II. An armature of the said description, having the conductors made. of copper,
connected to an iron drum or disk in such a manner, that they are situated between
the fieldmagnet poles and the said iron drum or disk, the copper not being wound
around the iron, but laying on one side of it, as herein set forth.
011 1
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