" IN DYNAMO-ELECTRIC MACHINES a communication to me from abroad
Year: 1885

page_text: I THORSTEN NORDENFELT of 53 Parliament Street in the City of Westminster
Civil Engineer, do hereby declare the nature of my invention for " IMPROVEMENTS
"
IN DYNAMO-ELECTRIC MACHINES a communication to me from abroad' by Oscar
Fredrik Jönsson of Stockholm Sweden Engineer to be as follows:-
A good dynamo machine ought to have the following properties. First it ought
to transform into electricity as much as possible of the mechanical work consuined
on the machine shaft, further, it ought to be disposed so that the production of
extra currents sparks and friction in the bearings and contact' brushes are obviated
as much as possible. Besides the improved effect, the further advantage is attained
that the iron masses of the machine working as magnets are not heated by so
called Foncault's currents. Secondly the machine ought to deliver the greatest
quantity possible of electricity with the least possible mass of wire and magnetic
iron. Hereby, besides that the machine will be easy to be handled and that its
net cost will be reduced, the 'further advantage is obtained that the mechanical
work requisite for rotating the inductor will be diminished in consequence of the
less weight of the latter. Thirdly, the interior resistance of the machine should be
capable of variation over a wide range, whereby it is possible to employ the same
machine for almost all the purposes for which dynamo electric machines are usually
employed, for instance for arc lights in series, single arc light with variable power
of light, lighting by means of incandescent lamps of different powers, transfer of
power to variable distances and with different conductors for the same distance,
electro deposition of metals and the like. This is attained by coupling dispositions
hereinafter described, whereby. I not only can vary the interior resistance of the
machine, but also its eléctro motive power without needing however to vary the
speed of rotation. Hence one such variable dynamo machine may replace several'
machines not thus variable. All these properties are united in the continuous'
currents dynamo machine which I will now describe.
J
The machine consists of two upright brackets fixed on a base. The upper part
of one of the brackets is horizontal and the electro-magnets are fixed to it. The
latter are composed of a number of curved iron bars preferably of wrought iron,
2

page_text: These bars are
attached some to the boltom plate, and some beneath the bracket.
connected by means of two bent pieces of iron, forming the magnetic field and
receiving contrary poles.
The electro-magnet coils are applied round the legs of the bars whereby four
such coils are obtained. The inductor consists of a metallic centre attached to the
shaft and into the flanges of which are introduced a number of adjusting screws.
Round this centre several pieces of wood or other suitable material perforated in
the direction of the radius are placed, and they are pressed outwards by means of
the adjusting screws. Round the centre the inductor coils are placed. These are
wound round a great number of iron rings placed one near the other with inter-
mediate pieces of asphalted paste-board or such like, whereby the iron rings are
insulated one from another and openings are left between them. The rings have
numerous projecting points between which the wire is wound, so that the exterior
part of each bobbin is placed between two rows of points.-The extremities of the
wire from each bobbin are connected with their respective coupling pieces which by
means of screws are attached to a plate of insulating material situated at the one
end of the inductor. In this plate, there is place for as many screws as there are
bobbins in the inductor, and from every alternate screw a radial piece passes to a
bar of the collector. With the screws the inductor coils may be coupled in
different manners; thus with each screw, the exterior extremity of the one bobbin
and the interior extremity of the other bobbin may be connected, whereby all the
bobbins are connected into one continuous circuit, that is for tension. Or two
adjoining bobbins can be connected one abreast of the other, that is for quantity.
In the former case the interior end of one bobbin is connected with the exterior
end of the adjoining bobbin whilst every alternate connection is coupled with a
radial piece. In the latter case all the coupling pieces, not connected with a radial
piece are separated and of these all the coupling pieces of the interior wire ends are
placed to the radial piece to the left of it and all the coupling pieces of the exterior
wire ends to the radial piece on the right, where they are fixed beneath the screw
heads of these radial pieces. Thus every second screw becomes free. When the
machine is thus arranged, the current will meet with only the fourth part of tho
resistance existing in the first described case, when the current passes through all
the bobbins one after another. In order to increase still more, the possibility of
connecting the bobbins in parallel arc, the number of radial pieces may be
diminished by connecting only every fourth, sixth, eighth, etc screw with the
collector by means of the radial piece, and the collector must in each case, be
modified in conformity.
I sometimes place two or more inductor rings of the inductor coil one abreast of
another and connect these bobbins either for tension or for quantity. Two coupling
discs may be used, one at each end of the inductor, in which event the inductor
rings, placed one abreast of another are connected each with its coupling disc. In
this case however, two collectors and brush apparatuses must be employed. Hereby
the advantage is attained that the connections may be modified in a greater number
of modes. Thus for instance, one ring may serve all the coils of the stationary
magnets, or only half of these coils, in which latter event, the second ring serves
the remaining half. In the latter case, the different circuits may have different
resistance, and supply each circuit with currents.
The collector consists of as many metal bars as there are radial pieces which bars
are arranged without any intermediate insulating matter to form a cylinder having
interspaces between the bars. These bars are in their extremities provided with
tenons, entering into holes in two discs of ebonite or other insulating matter
carried upon the shaft. The whole is kept together by means of a nut pressing the
collector against the metal centre which abuts against a shoulder on the shaft.
With this collector there is no place where small metal particles can collect and
form conducting bridges from one piece across to another, and thus cause sparks or
short circuiting. The brush is fixed by means of screws to a metallic holder
pivotting round a spindle, within which holder is a spring tending to press the

page_text: brush against the collector. When divided pole pieces are used, whereby the
machine obtains four poles, four brushes will be necessary. The spindles of the
brushes are fixed in a plate which may be turned round a stationary centre at will,
so that the contact points of the brushes with the collector may be displaced and
adjusted to suit the speed at which the inductor is wanted to revolve.
The stationary magnets may consist of four entire core pieces the central parts of
which are bent circular. The extremities of the pieces, are surrounded by the
electro magnet bobbins, which in this case will be eight in number.
In fixing the inductor ring upon the shaft, the metal centre and the wood pieces
may be replaced by a metal cross.
"
In order to be able also to vary the resistance for the current in its passage
through the coils of the electro-magnets, the ends of these coils are joined by
means of screws on a coupling plate of ebonite or other insulating material.
By connecting the different, screws by metal strips of suitable forms all the coils
may be coupled in series, or two and two abreast, or four abreast whereby the
resistances are varied. By employing eight. magnet coils it will be possible to
vary those couplings to a greater extent.

page_text: Improvements in Dynamo Electric Machines.
I THORSTEN NORDENFELT of 53 Parliament Street in the City of Westminster
Civil Engineer, do hereby declare the nature of this invention (a communication
from abroad by Oscar Fredrik Jönsson of Stockholm Sweden Engineer) and in
what manner the same is to be performed to be particularly described and
ascertained in and by the following statement:-
A good dynamo-electric machine ought to have the following properties. First
it ought to transform into electricity as much as possible of the mechanical work
consumed on the machine shaft-further, it ought to be disposed so that the pro-
duction of extra currents, sparks and friction in the bearings and contact brushes
are obviated as much as possible. Besides the improved effect, the further
advantage is attained that the iron masses of the machine working as magnets are
not heated by so called Foncault's currents. Secondly, the machine ought to
deliver the greatest quantity possible of electricity with the least possible mass of
wire and magnetic iron. Hereby, besides that the machine will be easy to be
handled and that its net cost will be reduced, the further advantage is obtained
that the mechanical work requisite for rotating the inductor will be diminished in
consequence of the less weight of the latter. Thirdly, the interior resistance of the
machine should be capable of variation over a wide range, whereby it is possible to
employ the same machine for almost all the purposes for which dynamo-electric
machines are usually employed, for instance, for arc lights in series, single arc
light with variable power of light,-lighting by means of incandescent lamps of
different powers, transfer of power to variable distances, and with different con-
ductors for the same distance, electro deposition of metals and the like.
attained by coupling dispositions hereinafter described, whereby I not only can
vary the interior resistance of the machine, but also its electro-motive power, with-
out needing however to vary the speed of rotation. Hence one such variable
dynamo machine may replace several machines not thus variable. All these pro-
perties are united in the continuous currents dynamo-machine represented in the
annexed Drawings.
DESCRIPTION OF THE DRAWINGS.
This is
Figure 1 is a longitudinal section of a dynamo-machine constructed in accordance
with the invention. Figure 2 is a cross section on the line y in Figure 1 and
Figure 3 is a plan of the machine. Figures 4. 5 and 6 represent a modified dis-
position of the machine viewed from the side, from the end, and in plan. Figure 7
shows the foremost bracket viewed from the interior with the arrangements for
collecting the current-the collector is in section on the line. Figure 1.
Figure 8 shows the manner in which the coils in the rotating armature or
inductor are connected. Figure 9 shows an alternative construction of the
inductor. Figure 10 shows an alternative construction of the Field magnets.
Figure 11 shows a modification of the commutator. Figures 12. 13 and 14
methods of coupling the coils of the Field magnets.

page_text: The machine see figure 1 consists of two brackets B and C. fixed on a base of
which the latter is at the top bent to an angle in order to retain the electro-
magnets. The latter are composed of a number of curved iron bars D preferably
of wrought iron, attached some to the bottom plate, and some beneath the
bracket C. These bars are connected by means of two bent pieces E of iron,
forming the magnetic field and receiving contrary poles-F are non-magnetic
metallic plates, interposed between the ends of the bars D and screwed to the
pieces E in order to keep them stayed. The electro-magnet coils G are as will be
seen, applied round the legs of the bars D whereby four such coils are obtained.
The inductor consists of a metallic center I attached to the shaft H and into the
flanges of which are introduced a number of adjusting screws K. Round this
center several pieces L of wood or other suitable material perforated in the direction
of the radius are placed, and they are pressed outwards by means of the adjusting
screws Round the pieces L the inductor coils M are placed These are wound
round a great number of iron rings N placed one near the other with intermediate
pieces of asphalted pasteboard or such like, whereby the iron rings are insulated
one from another, and openings are left between them. The rings are made (see
fig. 2) with numerous projecting points, between which the wire is wound in the.
manner shown by figure 1, so that the exterior part of each bobbin is placed
between two rows of points. In order to prevent the centrifugal force from dis-.
placing the wire from its position in the groove, the inductor is surrounded with
ties. Tho extremities of the wire from each bobbin are connected with their
respective coupling pieces which by means of screws are attached to a plate P of
insulating material situated at the one end of the inductor. In this plate, there is
place for as many screws as there are bobbins in the inductor, and with each screw,
the exterior extremity of the one bobbin and the interior extremity of the other
bobbin may be connected-Figure 8 represents the half inductor viewed from the
end, where the connecting plate P is placed. The left and the right half of the
figure represents two different modes of connecting the inductor bobbins. The right
half of the figure represents the above disposition where two adjoining bobbins are
connected one after the other, whereby all the bobbins are connected into one
continuous circuit, that is for tension. The left side of the same figure represents
two adjoining bobbins connected one abreast of the other, that is for quantity. In
the former case the interior end of ene bobbin is connected with the exterior end
of the adjoining bobbin whilst every alternate connection is coupled with one of
the radial pieces Q. In the latter case, all the coupling pieces, not connected with
a radial piece, are separated, and of these all the coupling pieces of the interior.
wire ends are placed to the radial piece to the left of it and all the coupling pieces
of the exterior wire ends to the radial piece on the right; where they are fixed
beneath the screw heads of these radial pieces. Thus every second screw becomes
free. When the machine is thus arranged, the current will meet with only the
fourth part of the resistance existing in the first described case, when the current
passes through all the bobbins one after another. In order to increase still more,
the possibility of connecting the bobbins in parallel arc the number of radial
pieces may be diminished, by connecting only every fourth, sixth, eighth, etc, screw
with the collector by meaus of the radial piece, and the collector must in each case,
be modified in conformity.
Figure 9 represents a modified mode of disposing the inductor coil by placing
two or more inductor rings one abreast. of another and connecting these bobbins
either for tension or for quantity Another modification is that two coupling discs
may be used, one at each end of the inductor, in which event the inductor rings,
placed one abreast of another, are connected each with its coupling disc. In this
case however, two collectors and brush apparatuses must be employed. Hereby the
advantage is attained that the connections may be modified in a greater number of
modes. Thus for instance, one ring may serve all the coils of the stationary
magnets, or only half of these coils, in which latter event, the second ring serves

page_text: the remaining half. In the latter case, the different circuits may have different
resistance, and supply each circuit with currents.
The collector consists of as many metal bars R as there are radial pieces Q,
which bars are arranged without any intermediate insulating matter to a cylinder
having interspaces between the bars. These bars are in their extremities provided
with tenons, entering into holes in two discs.S and T of ebonite or other insulating
matter carried upon the shaft H. The whole is kept together by means of a nut Ů
pressing the collector against the metal centre I which abuts against a shoulder on
the shaft. With this collector there is no place where small metal particles can
collect and form conducting bridges from one piece across to another, and thus
cause sparks or short circuiting. The brush V is fixed by means of screws to a
metallic holder X pivotting round a spindle, within which holder is a spring Y
tending to press the brush against the collector. When two whole pole pieces E are
used, two brushes are employed, as shown in figures 1. 3 and 7, but if on the
contrary, such pole pieces as represented in figure 10 are used, in which are placed
pieces of non magnetic metal, a, whereby the machine obtains four poles, four
brushes will be necessary, (see figure 11). The spindles of the brushes are fixed in
a plateb which may be turned round a stationary centre at will, so that the contact
points of the brushes with the collector may be displaced and adjusted to suit the
speed at which the inductor is wanted to revolve.
A modification of the magnetic field is represented in figures 4, 5 and 6, where the
stationary magnets consist of four entire pieces c the central parts of which are bent
circular. The extremities of the pieces c are round, and surrounded by the electro-
magnet bobbins & which in this case will be eight in number. These stationary
magnets are fixed by means of screws at their top and bottom to the base A and
the bracket C Figure 5 represents also a modification of the mode of fixing the
inductor ring upon the shaft. Here the metal centre and the wood pieces are
replaced by a metal cross e. fare metallic plates fixed by means of screws outside
the magnet pieces c in order to retain them in position.
In order to be able also to vary the resistance for the current in its passage
through the coils of the electro magnets, the ends of these coils are joined by means
of screws on a coupling plate g of ebonite or other insulating material.
By connecting the different screws by metal strips h of suitable forms in the
manner shown by figures 12. 13, and 14 all the coils may be coupled in series, or
two and two abreast, or four abreast, whereby the resistances are varied. By
employing eight magnet coils it will be possible to vary these couplings to a greater
extent.
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. Constructing the revolving inductor of a dynamo-electric machine of a metal
centre provided with adjusting screws and surrounded by pieces of wood or other
material perforated and supporting inductor bobbins, wound up about a number of
thin iron rings separated one from another by slips of pasteboard or such like, the
exterior edges of these rings having points between which the bobbins are wound,
substantially as represented and described.
2. Constructing the revolving inductor of a dynamo-electric machine with iron
rings on a metallic cross piece on the shaft of the inductor-the said rings being
separated the one from the other by strips of pasteboard or such like and the
inductor bobbins being wound about these rings substantially as shown and
described with reference to Figure 5.
3. The mode of connecting the bobbins of the inductor of a dynamo-electric
machine, the exterior and interior ends of the bobbins being furnished with
_ coupling pieces, which may in different manners be connected up or upon a
coupling plate, placed at one of the ends of the inductor by means of screws or

page_text: equivalent parts, every second, every fourth, or every sixth screw, being also con-
nected with a radial piece leading to the collector, substantially as shown and
described with reference to figure 8.
4. The combination in the inductor of a dynamo-electric machine of two or more
insulator rings, with a coupling plate or plates, whereby the interior resistance of
the machine may be varied substantially as shown and represented with reference
to Figure 9.
5. The improved collector of a dynamo-electric machine, having bars of copper
or other metal, connected with radial pieces, such bars at their ends being provided
with tenons entering holes in plates of ebonite upon the machine shaft, those bars
having interspaces for the free passage of the air substantially as and for the
purpose stated above.
6. In a dynamo-electric machine, connecting the wire ends from the brush
supporters and the coils of the stationary electro magnets by means of screws on a
coupling plate, and of placing between those screws differently shaped connecting
strips, whereby it is possible to vary the resistance substantially as shown and
described with reference to Figures 12. 13 and 14.