IMPROVEMENTS IN THE CONSTRUCTON OF DYNAMO-ELECTRIC MACHINES
Year: 1881

page_text: LETTERS PATENT to Ernest John Harling, of Guildford Street, Farringdon
Road, and Emil Hartmann, of Compton Street, both in the County of
Middlesex, for an Invention of "IMPROVEMENTS IN THE CONSTRUCTON OF
DYNAMO-ELECTRIC MACHINES,"
PROVISIONAL SPECIFICATION left by the said Ernest John Harling and
Emil Hartmann at the Office of the Commissioners of Patents on the
11th August 1881.
"
ERNEST JOHN HARLING, of Guildford Street, Farringdon Road, and EMIL
HARTMANN, of Compton Street, both in the County of Middlesex. "IMPROVE-
MENTS IN THE CONSTRUCTION OF DYNAMO-ELECTRIC MACHINES,"
This Invention relates, first, to improvements in the construction of that class
of dynamo-electric machines in which a rotating ring armaturo is brought into
close proximity with the field magnets by means of projecting pieces, the object
of such improvements being to obtain a proper distribution of the magnetism
induced, and to ensure the magnetic polarization of the same in the proper direction
throughout the armature; secondly, to improvements in the construction and
arrangement of the field magnets of the machine, whereby the magnetisation and
de-magnetisation of the parts of the armature are effected in a more effectual
manner than is the case in similar machines as ordinarily constructed; thirdly, to
the construction and arrangement of a regulator by means whereof the currents of
electricity generated are always maintained at the same strength, any fluctuation
being counteracted by means of the said regulator; and fourthly, to the arrange-
ment and electrical connection of the coils of the rotating armatures of dynamo-
electric machines.
We will now describe the nature of the first part of our said Invention, which
consists in improvements in the construction of the armatures of dynamo-electric
machines. The ring armature is brought into close proximity with the field
magnets by means of projecting pieces, the latter being constructed and combined
with the body of the armature in the following manner:-The projecting parts
have formed on them flat plates, which plates are attached to the sides or to the
peripheries, as the case may be, that is to say, according to the arrangement of the
poles or pole-pieces of the field magnets, of a ring or a number of concentric or

page_text: parallel soft iron rings partly or entirely insulated from each other, a space being
in some cases left between the end of each plate and the outer side of the next
projection; but the plates may also be made to overlap each other, in which case
it is preferable to make them sufficiently long to extend from one pole in the
magnetic field to the opposite pole, so that when their is only one pair of field
magnets the plates will be semi-circular, but they will be decreased in length as
the number of field magnets is increased. In some cases we insulate each pro-
jection and that part of the plate which is near the same from the plate under-
neath, or the whole of the plate can be insulated from the plate underneath.
the latter case the plates should be in connection with the ring, but when they are
not entirely insulated from each other the ring can be dispensed with.
In
Each projection with its plate is constructed from one single solid piece of
wrought or soft cast-iron. Over the said plates and round the ring or rings are
wound the coils of copper wire, which may be wound and connected in the usual
manner. One side of each coil is in close proximity with the projection of the
plate on which it is wound, but a space is left between the other side of each coil
and the next projection, such space serving to lessen the injurious effect of such
projection on the coil, as the former would induce a current in the latter flowing
in an opposite direction to the general or main current induced by the body or
ring of the armature. The said spaces can when desired be filled in with an insu-
lating and non-magnetic material. The said plates must be so arranged on the
ring that the projecting pieces enter and leave the magnetic field before their
respective coils and plates. The projecting pieces when they are not formed thin
and long are split by a number of narrow grooves or recesses, this arrangement
serving to check local currents generated in the metal constituting the projection;
the same object can be attained by making the projections and plates in several
parts, and arranging the latter on the ring or rings a little distance from each
other. In some cases we connect the plates of the several projections to the pro-
jection plates which are diametrically opposite.
The improvements in the construction and arrangement of the field magnets
constituting the second part of our said Invention are as follows:-The magnetic
field is so arranged that the point of greatest magnetic intensity is not situated in
the middle of the field, as is customary in ordinary machines, but is situated at or
near one end of the same, that is to say, the end where the coils of the armature
leave the field, so that when one of the above mentioned projections and its
generating coil passes from one neutral point to the other, it remains longer (than
in arrangements at present in use) under the influence of the magnetic pole when
approaching the same, but is withdrawn suddenly from its influence when leaving.
These objects we effect by extending the poles of the field magnets on one side
more than on the other, or on one side only, or when semi-circular pole pieces
attached to the field magnets are used by fixing the said pole pieces to the cores of
the field magnets in such a manner that the former will extend on one side more
than on the other, or on one side only. The field magnets with their respective
extensions or extending pole pieces are so arranged that the projections on the
armature will first come under the influence of the free ends of the said extensions
or pole-pieces, and gradually approach the pole; and when the latter is reached
they suddenly leave the magnetic field, that is to say, the projections in the first
instance come opposite that part of the pole or of the extension of the pole where
the magnetic influence is the least, and gradually approach the point where it is the
greatest.
The construction and arrangement of the regulator to which the third part of
our Invention has reference are based upon the same principle as the hand
regulator of an ordinary magnetic machine, that is to say, when two poles of
opposite polarity in the magnetic field are arranged to attract an armature of soft
iron moving in close proximity with the faces or edges of the field magnets, but
never coming in contact therewith, the more the said armature is attracted the
more the face or edge of the same will cover the face or edge of the poles or pole

page_text: pieces of the field magnets, whereby the effect of the said magnets upon the
rotating armature and the generating coils will be lessened, and if the soft iron
armature be sufficiently thick the influence of the magnets on the rotating
armature can be altogether destroyed when the said bar is caused to cover sufficient
of the surface of the said poles. If there is only one pair of field magnets the
said regulator consists of an iron bar, the centre of which is pivoted between the
poles of the field magnets, and the two ends of the said bar come respectively
opposite the extremities of the free ends of the pole-pieces. One end of the said
bar is connected to an adjustable spring, or a spring or weight is suitably arranged
for counteracting any increased attraction on the bar due to fluctuations in the
strength of the current when the machine is running.
In larger machines, although each pair of field magnets can be provided with a
separate regulator bar, as above described, we in some cases, when there are two
pairs of field magnets, make the regulator armature in the form of a cross, and
when there are more than two pairs, we in some cases make the regulator
armature in the shape of a star. In this case two neighbouring rays of the star
will form the connection between the two poles (north and south). The said cross
we arrange to move in close proximity with the inner periphery of the circle
formed by the poles or pole pieces of the field magnets. However by a slight.
modification in form the regulator armature or armatures can be arranged to move
in close, proximity with the outer periphery of the poles or pole pieces of the
field magnets. In all cases the attraction of the field magnets on the regulator
armature should be counteracted to a certain extent by means of an adjustable
weight or spring connected to the latter, as will be well understood.
It will be readily seen that the above described regulator is applicable to dynamo-
electric machines in which the current generated in the coils of the rotating
armature is made to excite the field magnets.
The improvements in the arrangement of the coils of rotating armatures and
electrical connections thereof which constitute the fourth part of our said Invention,
and which are suitable to be employed in connection with the improved rotating
armature herein before described are as follows:-The coils of the rotating armature
are arranged in such a manner that they will form two distinctly separate circuits,
one of which will embrace the coils of the field magnets whilst the other will
include the lamps; this we effect in the following manner :-Each coil of the
armature consists of two parts, that is to say, of two separate insulated wires, one of
which is of a higher resistance than the other and is wound close to the projoction,
whilst the other, of lower resistance, forms a separate coil, but is wound in close
proximity to the first mentioned coil, so that they have the appearance of one coil.
The current generated in the wire of higher resistance is taken direct to the lamp
and produces the light, whilst the current generated in the wire of lower resistance
circulates through the coils of the field magnets and excites the same.
The commutator, which is placed in connection with the coils of the armature by
means of the brushes, is so arranged that the internal resistance of each separate
generating conductor, or coil or coils of the armature varies with the relative
position of the same in the magnetic field during each half revolution, that is to
say, two diametrically opposite coils are through the commutator "coupled up to
tension" when near the neutral points, and when approaching the more intense
portions of the magnetic field the same coils will be "coupled up to quantity;" but
when approaching the other neutral point they will again enter into their former
combination, that is to say, they will form one single circuit. Instead of taking
two diametrically opposite coils, each coil can be wound with a double wire, and
when near the neutral points the two wires will be "joined for tension,” but when
in the more intense portions of the field they will be “joined for quantity.”

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Ernest John Harling and Emil Hartmann in the Great Seal Patent
Office on the 11th February 1882.
ERNEST JOHN HARLING, of Guildford Street, Farringdon Road, and EMIL
HARTMANN, of Compton Street, both in the County of Middlesex. "IMPROVE-
MENTS IN THE CONSTRUCTION OF DYNAMO-ELECTRIC MACHINES."
Our said Invention relates, first, to improvements in the construction of dynamo-
electric machines in which a rotating ring armature is brought into close proximity
with the field magnets by means of projecting pieces, the object of such improve-
ments being to obtain a proper distribution of the magnetism induced, and to
ensure the magnetic polarization of the same in the proper manner throughout the
armature; secondly, to improvements in the construction and arrangement of the
field magnets of the machine, whereby the magnetisation and de-magnetisation of
the parts of the armature are effected in a more effectual manner than is the case
in similar machines as ordinarily constructed; thirdly, to the construction and
arrangement of a regulator by means whereof the currents of electricity generated
are always maintained at the same strength, any fluctuation being counteracted by
means of the said regulator; and, fourthly, to the arrangement of electrical con-
nection between the coils of the armature through the commutator and brushes,
whereby the electro-inotive force of the armature circuit is kept constant, whatever
may be its relative position in the magnetic field.
We will now describe the nature of the first part of our said Invention, which
consists in improvements in the construction of the armatures of dynamo electric
machines. The ring armature is brought into close proximity with the field
magnets by means of projecting pieces, the latter being constructed and combined
with the body of the armature in the following manner:-The projecting parts
have formed on them flat soft iron plates, which plates are attached to the sides or
to the peripheries, as the case may be, of a ring or a number of concentric or
parallel soft iron rings, a space being in some cases left between the end of each
plate and the outer side of the next projection, but the plates may also be made to
over-lap each other, in which case it is preferable to make them sufficiently long to
extend a quarter round the ring, but when there is only one pair of field magnets
the plates will be semi-circular, and they will be decreased in length as the number
of field magnets is increased. In some cases we insulate each projection and that
part of the plate which is near the same from the plate underneath, or the whole
of the plate can be insulated from the plate underneath. We in most cases
insulate with tissue paper, and leave a small space at the end uninsulated. When
entirely insulated the plates should be in connection with a central ring, but
when they are not entirely insulated from each other the ring can be dispensed
with.
Each projection with its plate is made of wrought or soft cast iron. Over the
said plates and round the ring or rings are wound the coils of copper wire, which
may be wound and connected in the usual manner. One side of each coil is in
close proximity with the projection of the plate on which it is wound, but a space
is left between the other side of each coil and the next projection, such space serving
to lessen the injurious effect of such projection on the coil, as the former would
induce a current in the latter flowing in an opposite direction to the general or
main current induced by the body or ring of the armature. The said spaces can
when desired be filled in with an insulating and dia-magnetic material. The said
plates must be so arranged on the ring that the projecting pieces enter and leave
the magnetic field before their respective coils and plates. The projecting pieces

page_text: when they are not formed thin are split by a number of narrow grooves or recesses,
this arrangement serving to check local currents generated in the metal constituting
the projection. The same object can be attained by making the projections and
plates in several parts, and arranging the latter on the ring or rings a little distance
from each other.
The improvements in the construction and arrangement of the field magnets
constituting the second part of our said Invention are as follows:-The magnetic
field is so arranged that the point of greatest magnetic intensity is not situated in
the middle of the field, as is customary in ordinary machines, but is situated at or
near one end of the same, that is to say, the end where the coils of the armature
leave the field, so that when one of the above mentioned projections and its
generating coil passes from one neutral point to the other, it remains longer under
the influence of the magnetic pole when approaching the same, but is withdrawn
suddenly from its influence when leaving. These objects we effect by extending
the poles of the field magnets on one side more than on the other, or on one side
only, or when pole pieces attached to the field magnet cores are used, by fixing the
said pole-pieces to the cores in such a manner that the former will extend on one
side more than on the other, or on one side only. The field magnets with their
respective extensions or extending pole pieces are so arranged that the projections
on the armature will first come under the influence of the free ends of the said
extensions or pole-pieces, and gradually approach the pole, and when the latter is
reached they suddenly leave the magnetic field, that is to say, the projections, in
the first instance, come opposite that part of the pole or of the extension of the
pole where the magnetic influence is the least, and gradually approach the point
where it is the greatest.
The construction and arrangement of the regulator to which the third part of our
Invention has reference are based upon the same principle as the hand regulator of
an ordinary magnetic machine, that is to say, when two poles of opposite polarity
in the magnetic field are arranged to attract a bar of soft iron moving in close
proximity with the faces or edges of the field magnets, but never coming into
actual contact therewith, the more the said regulator is attracted the more the face
or edge of the same will cover the face or edge of the poles or pole pieces of the
field magnets, whereby the effect of the said magnets upon the rotating armature
and the generating coils will be lessened. If the soft iron regulator be sufficiently
thick the influence of the magnets on the rotating armature can be altogether
destroyed when the said bar is caused to cover sufficient of the surface of the said
poles. If there is only one pair of field magnets the said regulator consists of an
iron bar, the centre of which is pivoted between the poles of the field magnets, and
the two ends of the said bar come respectively opposite the extremities of the free
ends of the pole pieces. One end of the said bar is connected to an adjustable
spring, or a spring is otherwise suitably arranged for counteracting any increased
attraction on the bar due to fluctuations in the strength of the current when the
machine is running.
In larger machines, although each pair of field magnets can be provided with a
separate regulator bar as above described, we in some cases where there are two pairs
of field magnets, make the regulator armature in the form of a cross, and when
there are more than two pairs we in some cases make the regulator armature in
the shape of a star. In this case two neighbouring rays of the star will form the
connection between two poles (north and south). The said cross we arrange to
move in close proximity with the inner periphery of the circle or similar figure
formed by the poles or pole pieces of the field magnets. However by a slight
modification in form the regulator armature or armatures can be arranged to move
in close proximity with the outer periphery of the poles or pole pieces of the field
magnets. In all cases the attraction of the field magnets on the regulator armature
should be counteracted to a certain extent by means of an adjustable weight or
spring connected to the latter, as will be well understood.
It will be readily seen that the above described regulator is applicable to dynamo-

page_text: electric machines, in which the current generated in the coils of the rotating
armature is made to excite the field magnets.
The improvement in the arrangement of the coils of rotating armatures and
electrical connections thereof which constitute the fourth part of our said Invention
and which are suitable to be employed in connection with the improved rotating
⚫armature herein before described, are as follows:-
The commutator, which is placed in connection with the coils of the armature, is
so arranged in combination with the brushes that the internal resistance of each
separate generating conductor or coil or coils of the armature varies with the
relative position of the same in the magnetic field during each half or quarter
revolution, according to the number of poles in the field, that is to say, two or four
diametrically opposite coils are through the commutator "coupled up to tension"
when near the neutral points, and when approaching the more intense portions of
the magnetic field the same coils will be "coupled up to quantity," but when
approaching the other neutral point they will again enter into their former
combination, that is to say, they will form one single circuit. Instead of taking
two diametrically opposite coils, each coil can be wound with a double wire, and
when near the neutral points the two wires will be "joined for tension," but when
in the more intense portions of the field they will be "joined for quantity."
We will now proceed to refer to the accompanying Drawings, for which the
nature of our said Invention will be more clearly understood. The same letters of
reference indicate like parts in all the Figures.
Figure 1 is a plan of a plate b with its projection p; the projections are by
preference inclined, as shown, in order to ensure the magnetic polarization of the
projections and their plates in an effective manner; this plate 6 is constructed to
extend half round the ring of the armature; Figure 2 is a similar view of a like
plate constructed to extend only a quarter round the said ring, and Figure 3 is an
edge view of the same; Figure 4 is a view of five plates lapped one over the other;
these plates extend respectively from p¹ to b¹, p³ to b³, and so on, and the layers of
non-conducting and diamagnetic material, tissue paper, for instance, which separate
the various plates, end at x², a³, and so on. An air channel is left in the centre
between the said plates b, which form the body of the rotating armature, by
attaching the rings formed by the said plates to a series of spokes or projecting
pieces extending from a central boss attached to the shaft a; the said air channel
is shown in Figure 5. By preference it is desirable to arrange the field magnets
on one side of the armature slightly in advance of those on the opposite side; this
will produce a more continuous action in the coil c; Figure 5 is a horizontal section
of a portion of the armature and two of the field magnets, in which is the before
mentioned air channel; b are the plates with the projections p and coils c; and
N, S, N, S, are the poles of the field magnets; Figure 6 is a view of a machine
with two pairs of field magnets and a regulator provided with a counteracting
weight, such regulator being more fully shown in Figure 7; K is the commutator;
L, L, L, L, are the brushes, which are by preference set in one straight line;
Figure 7 is a side elevation of the magnets (two pairs at each side), and a cross-
shaped regulator; N, S, N, S, are the poles of the magnets, and P¹, P², P³, P₁, the
pole pieces; & is the regulating armature. It will be observed that any further
attraction of d in the direction of the arrow will lessen the space between d and P,
such attraction being counteracted by the weight & which is suspended from the
periphery of the eccentric f. The latter is attached to the segment g, and both
are pivoted at ; the more the weight is lifted by the increased attraction of P
on d, the greater will be the leverage by which the weight a acts on x; a is the
shaft of the machine which revolves within the stationary bush i attached to the
frame of the machine. The regulator d is so fitted on i as to revolve easily, and is
connected through the raised semi-circular ridge j and the flexible connecting
strap (rope or chain) with the segment g; o and y are two fixed abutments to
limit the movements of d; Figures 8 and 9 show one method of connecting the
coils and commutator. Four diametrically opposite coils are connected in the

page_text: following manner:-The first end of coil 1 to the first end of coil 2, the last end of
the latter to the last end of coil 3, and the first end of coil 3 to the first end
of coil 4; the last ends of coils 1 and 4 are connected to their respective segments
of the commutator in such a manner that each end is in contact with four
diametrically opposite segments, which however do not form part of the same
cylinder, as shown in Figure 9. The segments numbered 1, 3, 5, and 7 of the
commutator are all connected with coil 1, whilst the segments between the same
are connected to coil 4. When the coil is under the influence of the beginning of
the pole-pieces P, its current is conducted through the field magnet coils; but as
soon however as it approaches the cores of the magnets N, S, and N, S, the current
is sent through the working circuit. The inner edges of the pole-pieces P do not
form a circle. The dotted line, shown in Figure 7, indicates the circle struck from
the centre; Figure 10 shows a regulator as applied to a machine having a pair of
magnets at each side, the action of such regulator being controlled by a spring.
This Figure shews the regulator, which consists of a bar d of soft iron so arranged
as to turn about its centre and sliding over the pole pieces P, P', not touching the
same but being in close proximity with them. When the machine starts and the
field magnets are excited, the bar d is attracted towards the position shewn dotted,
such attraction being counteracted by spiral spring 8, the tension of which can be
regulated by stud y. As the current tends to increase, the bar is further attracted
from its position, and consequently covers more of the surface of the poles or pole-
pieces, thereby, as is well known, lessening the effect of the latter on the armature,
consequently the current and the field magnets become too weak to retain the bar
in its advanced position through the increased tension of the spring. The latter
therefore will cause the bar to go back and free more or less of the surface of the
pole pieces, thereby increasing the inductive effect of the field magnets on the
armature. In this manner any fluctuation in the strength of the currents will be
duly counteracted, as will be well understood. In some cases we substitute weights
at one end of the bar for the said spring; o is a stop to prevent the bar moving in
the wrong direction.
Having thus described and ascertained the nature of our said Invention, and the
manner in which it is to be performed, we would observe in conclusion that we are
aware that projections on ring armatures have previously been employed, and that
in some cases the said projections have been slotted or grooved, and also that the
rings of the said armatures have been constructed of parallel and concentric rings;
we do not therefore claim such employment of projections generally, neither do we
claim the said last mentioned methods of constructing the rings of annular armatures,
but what we consider novel and original, and therefore clain as constituting the
Invention secured to us by the said hereinbefore in part recited Letters Patent
are,-
First. The construction of the combined projections and plates, and the arrange-
ment of the same, and of the coils in connection with the ring or rings in amular
armatures of dynamo-electric machines, substantially as and for the purposes
hereinbefore described and set forth and illustrated in the Drawings hereunto
annexed.
Secondly. The construction and arrangement of the poles and pole pieces of
the magnets constituting the magnetic field employed in connection with the
revolving armatures of dynamo-electric machines, substantially as and for the
purposes hereinbefore described and set forth and illustrated in the Drawings
hereunto annexed.
Thirdly. The arrangement of electrical connection between the coils of the
armature through the commutator and brushes, whereby the electro-motive force
of the coils is kept constant during their passage through the magnetic field,
substantially as hereinbefore set forth and described.
And, Fourthly. The construction and arrangement of the regulator to be employed
in connection with the field magnets of dynamo-electric machines, substantially as

page_text: and for the purposes herein before described and set forth and illustrated in the
Drawings hereunto annexed.
In witness whereof, we, the said Ernest John Harling and Emil Hartmann,
have hereunto set our hands and seals, this Tenth day of February, in
the year of our Lord Eighteen hundred and eighty two.