IMPROVEMENTS IN DYNAMO-ELECTRIC OR MAGNETO-ELECTRIC AND ELECTRO-DYNAMIC MACHINES.
Year: 1881

page_text: LETTERS PATENT to Charles William Siemens, of No. 12, Queen Anne's Gate,
Westminster, in the County of Middlesex, for an Invention of "IMPROVEMENTS
IN DYNAMO-ELECTRIC OR MAGNETO-ELECTRIC AND ELECTRO-DYNAMIC
MACHINES.' A communication from abroad by Messrs. Siemens and
Halske, of Berlin, in the German Empire.
PROVISIONAL SPECIFICATION left by the said Charles William Siemens
at the Office of the Commissioners of Patents on the 1st April 1881.
+ .66
CHARLES WILLIAM SIEMENS, of No. 12, Queen Anne's Gate, Westminster, in
the County of Middlesex. IMPROVEMENTS IN DYNAMO-ELECTRIC OR MAGNETO-
ELECTRIC AND ELECTRO-DYNAMIC MACHINES." [A communication from abroad by
Messrs: Siemens and Halske, of Berlin, in the German Empire.]
This Invention has for its object the construction of dynamo-electric or
magneto-electric or electro-dynamic machines in such manner as to afford a
continuous electrical current both as regards direction and practically also as
regards strength.
The essential feature of the Invention consists in combining together to form a
continuous current separate electrical impulses that are generated immediately
after one another at different parts of the machine, whereas in machines of present
construction such combination can only be effected in impulses generated in
consecutive magnetic fields.
For this purpose an even number of magnets or electro-magnets are arranged
uniformly round a circle presenting an even number of successive fields of
alternating polarity. A number of coils of insulated wire, which may be wound
either on iron cores or on wooden or other non-magnetic cores, are mounted on an
axis by the revolution of which these coils are caused to pass through the successive
polar, fields above mentioned. The number of coils is less or greater than the
number of fields by two or any other even number, and the coils have their wires
so connected to each other and to a commutator that when an electrical current
passes through one in one direction, a current passes through the next in order in

page_text: the opposite direction. Thus during the revolution of the coils there is always
about half their number, by their approach to magnetic fields, having set up in
them by induction currents of one sign and about half the number by their
receding from magnetic fields having set up in them currents of opposite sign.
Instead however of the currents in each of the coils of the two series changing
their direction or sign and attaining their maximum strength simultaneously as is
the case in such machines of present construction, where the number of coils and
magnetic fields is equal, the result of the above arrangement is that the currents
generated in two successive coils attain their maximum strength the one after the
other. The ends of the several coils are so connected together that the whole of
the coils form a closed circuit and that in this circuit each coil is wound in the
contrary direction to the preceding one. Consequently the current impulses
generated in two successive coils will be added to each other as the coils
successively approach the successive polar fields of opposite sign. The currents
thus set up may be collected and commutated in various known ways so as to
produce at the terminals of the machine either alternating positive and negative
currents, or intermittent, or by preference continuous currents of one sign at each
terminal. The machine may also be employed as an electro-dynamic machine,
being supplied with electricity from any source, the attraction and repulsion of the
magnetic fields on the coils causing rotation of the axis which carries them. The
following construction may serve as an example of how a machine may be arranged
in the manner above described. From a base project upwards two circular frames
having fixed on each of them 10 electro magnets projecting inwards, these magnets
being such that opposite poles in each case face each other with a space between
them constituting a magnetic field, and that these successive poles of each circle
have alternate polarity. On a central axis is fixed a disc or wheel which carries
8 coils wound on oval wooden cores, which coils are connected together as before
described; the axis also carries a commutator cylinder similar in construction to
those employed in ordinary dynamo-electric machines and having in the present
instance 40 insulated contacts. These contacts are so arranged and connected in
8 groups that each group contains 5 contacts, which are separated from each other
by.7 intervening contacts of the several other groups. From the wires connecting
two successive coils a connecting wire passes to one of the groups of the
commutator, in such manner that the connecting wires to successive coils are also
connected to successive contacts and consequently to successive contact groups of
the commutator.
The currents are taken off at two diametrically opposite points of the
commutator, or it may be at certain other points, by means of contact springs or
brushes in a similar manner to ordinary dynamo-electric machines. The action of
the machine will take place as follows:-
On rotating the disc with its coils and commutator, there will be generated in all
the coils that are approaching magnetic fields of like polarity currents of like sign
while in the coils that are approaching magnetic fields of opposite polarity there
will be generated currents of the opposite sign. If now the ring of coils and
magnetic fields be divided by a line passing diametrically through the axis into
two halves, it will be found that, no matter in what position the coils may be, it
will always be possible to make this division so that all the coils in the half circle
on one side thereof will be approaching magnetic fields of the same sign as
themselves and all those in the other half circle will be approaching fields of a
dissimilar sign. In one point of each half circle there must consequently be an
accumulation respectively of positive and of negative electricity. The diametrically
opposite connecting wires of the coils situated for the time being at the said
division line being connected with the contacts that are at the same moment under
the contact brushes, the accumulated currents of opposite sign produced as above
described will be led off by these into the circuit, and as this condition of things
will exist continuously owing to the position of the said dividing line shifting
continuously in precisely the same manner as the commutator contacts change

page_text: their position relative to the contact brushes, it follows that approximately
continuous currents will be thereby conveyed into the line.
As before stated the above described arrangement only serves as an example, as
the construction of the machine is capable of considerable variation, according to
the number of rotating coils and magnetic fields employed; thus instead of having
a greater number of magnetic fields than coils the reverse arrangement can be
employed, and the difference between their number need not necessarily be two.
There may also be several sets of coils and magnetic fields combined in one
machine, thus there may be two sets of coils arranged side by side on the same
axis, in which case the coils of the one set may occupy intermediate positions
relatively to those of the other set.
In this case as the sequence of the current impulses would be different from
that above described, the connection of the coils in the circuit would also he
different.
Instead of collecting the current impulses generated at different parts of the
machine by means of a commutator with numerous contacts and connections as
described, the separate consecutive currents of opposite sign generated in each coil
may be commutated by means of a commutator of known construction into
intermittent currents of like sign, all of which are then combined into a practically
continuous current by the connections of the several coils with their several
commutators and of the contact springs or brushes to the latter.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Charles William Siemens in the Great Seal Patent Office on
the 30th September 1881.
CHARLES WILLIAM SIEMENS, of No. 12, Queen Anne's Gate, Westminster, in
the County of Middlesex. IMPROVEMENTS IN DYNAMO-ELECTRIC OR MAGNETO-
A communication from abroad 'by
"
ELECTRIC AND ELECTRO-DYNAMIC MACHINES.'
Messrs. Siemens and Halske, of Berlin, in the German Empire.
This Invention has for its object the construction of dynamo-electric or magneto
electric or electro-dynamic machines in such manner as to afford a continuous
electrical current both as regards direction and practically also as regards strength.
The essential feature of the Invention consists in combining together to form a
continuous current separate electrical impulses that are generated immediately
after one another at different parts of the machine, whereas in machines of present
construction such combination can only be effected in impulses generated in
consecutive magnetic fields.
As an example of the application of this Invention 1 will first describe a machine
for the production of intermittent currents of like or of alternate direction referring
to Fig. 1 which is a longitudinal section and Fig. 2 which is a front or end view,
The machine shewn in these Figures resembles in many respects machines already
known, it is to be taken merely as a type illustrating the present Invention as I
will now describe. On the base A are fixed two parallel sideframes B B of
circular form. On the inner faces of these frames are fixed projecting inwards
from them an even number (in this case ten) of electro-magnets C. The inner
ends of these magnets facing each other have polar extensions of suitable segmental
form, and the polarity of each is opposite that of the pole of the magnet facing it
and of the poles of the magnets on each side of it, so that between each pair of
facing poles there is a powerful magnetic field of polarity opposite to that of the
field on each side of it. Through these magnetic fields are caused to revolve
bobbins S S of insulated wire wound on wooden cores of elongated shape these
bobbins being fixed on a wheel on the axis E and being of such width as almost
to touch the poles of the magnets C on each side of them. If when the number of
coils S is the same as that of the magnets C as in machines hitherto employed
then all the coils have currents induced in them simultaneously as they approach
and leave the successive polar fields. According to the present Invention however
the number of coils S is made to differ by an even number from that of the fields G
through which they pass; in the example given in Figs. 1 and 2 there are
coils passing through 10 fields. The effect of this is that every pair of diametrically
opposite coils is always in the same phase of induction, each successive pair being
subject to a greater or less inductive influence as the case may be. Thus the
current does not, as in previous machines, attain its maximum or minimum strength
in all the coils simultaneously but successively in each pair of diametrically opposite
coils. The wires of all the coils being so connected as to form a continuous circuit
whilst they are wound on the coils alternately in opposite directions, the impulses
in all the coils become added together. The axis of the machine carries a com-
mutator t of ordinary construction, consisting in the example given of 40 insulated
plates divided into five groups cach consisting of slight commutator plates each
plate separated from the next of its own group by seven intermediate plates. This
grouping is effected by means of eight insulated rings fixed on the axis to each
of which five of the commutator plates are connected by five wires d, and the
rings being connected each to the wire connecting two successive coils the
successive groups of commutator plates correspond in order with the successive

page_text: connections of the coils. The currents are collected in the usual way by two
opposite brushes which can be shifted more or less round the periphery of the
commutator. The action of the machine may be more clearly understood on
reference to the diagram Fig. 3 in which the outer squares a b represent the 10
stationary fields of alternating polarity, and the inner ellipses a represent the
8 coils that revolve through them.
The divided circle between these represents
the commutator having its 40 plates arranged in 5 groups each containing 8 plates
numbered respectively from 1 to 8. The numbers 1, 2, 3 etc. between the ellipses
indicate the wires that lead from the connecting wire of each pair of adjoining coils
to the rings and thence to the commutator plates. Thus the wire 1 is connected
through its ring with all the five commutator plates marked 3, wire 2 with all the
five plates marked 8, and so on. The arrows marked respectively and indicate
the commutator brushes. It will now be understood that all the coils which are
approaching fields marked with the same letters, a approaching a, and approach-
ing b, have currents set up in them in one direction which may be indicated by
the arrows and that all the coils approaching fields marked by different letters,
a approaching, or approaching a, have currents set up of opposite direction
which may be indicated by the arrows y. There will always therefore be in every
situation of the coils as they revolve, a diametrically dividing line such as p, m,
towards one end of which there is an accumulation of positive and towards the
other of negative electricity. This line in the position shewn in Fig. 3 passes
through the junctions 4 and 8 and as the brushes rub on the corresponding plates
4 and 8 of the commutator they take off the accumulated electricity. The
imaginary line pm always moves round in a direction opposite to that of the
commutator and with greater velocity. For example when the coils and com-
mutator have moved 1/4th of a revolution the line pm will pass through the
junctions 3 and 7 and thus the brushes are always in the proper position to receive
the currents, which will obviously be the more nearly uniform the greater the
number of fields and coils employed. Assuming to be the number of coils
and +2 the number of fields, then (n+2) or (+1) will be the number
of commutator plates, such that there is always a pair of opposite plates corre
sponding to an opposite pair of connections between two successive coils. The
number of fields might be less than the number of coils, that is to say if the coils
number the fields might number n-2. Again the number of coils might be
doubled by arranging them in two planes overlapping each other as shewn by
Figs. 6 and 7 the connections being in that case arranged as shewn by the
diagram Fig. 5 in which the arrows indicate the directions of the currents to and
from the several coils and the numbers marked on the lines connecting the coils
indicate the connections through the rings to the respective commutator plates
which in this case number 80 divided into 5.groups each containing 16.
n
2
n
Instead of collecting the currents from a number of coils together as described,
cach separate coil might be arranged to deliver its current and these currents
which would be alternating might by means of known commutators be directed
as successive currents and collected into currents of constant direction. Fig. 4
shews in perspective a single coil with a commutator arranged for this purpose.
A number of such commutators might be arranged on the axis of the machine and
their respective brushes f f connected as desired.
Machines of known forms other than that to which as an example the above
description refers might have their polar fields and coils arranged so as to operate
according to this Invention, which, as will be understood from the foregoing
description, does not relate to any particular construction or position of the field
magnets or coils or any particular method of producing the currents in any one
coil, but in the arrangement and connection of the coils so as to produce the
cumulative effect resulting from the induction in the successive coils. A like
arrangement and connection applies also to magneto-electric machines and to

page_text: electro-dynamic machines in which electricity is applied to produce motive
power.
Having thus described the nature of the said Invention and in what manner
the same is to be performed as communicated to me by my foreign correspondents;
I claim in respect of dynamo-electric, magneto-electric, and electro-dynamic
machines:
'
First. Combining with an even number of stationary magnetic fields of
alternating polarity a number of revolving alternately wound coils differing by
two or other even number from the number of fields, the wires of the coils being
all connected to one another and to a commutator substantially as and for the
purposes herein set forth.
Second. In a machine arranged in the manner referred to in the preceding
claim, the use of a commutator the plates of which are combined in groups each
containing as many plates as there are revolving coils, substantially as and for the
purposes herein set forth.
In witness whereof I the said Charles William Siemens have hereunto set
my hand and seal this Twenty eighth day of September in the year of
our Lord One thousand eight hundred and eighty one.
C. W. SIEMENS. (L.S.)