A MAGNETO-DYNAMO ELECTRIC MACHINE
Year: 1877

page_text: PROVISIONAL SPECIFICATION left by the said Paul Jablochkoff at the Office
of the Commissioners of Patents on the 22nd August 1877.
PAUL JABLOCHKOFF, of Paris (France), Engineer. "A MAGNETO-DYNAMO
ELECTRIC MACHINE."
My Invention relates to apparatus for the production of electrical currents by the
mechanical motion of magnetic bodies, such apparatus being known as magneto-
dynamo electric machines. A short bobbin of coiled insulated wire of diameter
greater than its length is placed between two soft iron cheeks or discs which are
fixed on a soft iron shaft that passes through the heart of the bobbin, and the shaft
and 'cheeks are caused to revolve, the coil either remaining stationary or revolving
with them as required. In order that the principle on which this machine acts may
be understood I will suppose an electric current is passed through the coil, each or
the cheeks would then become magnetic, one pole north or south being presented at
the circumference of the one and at the centre of the other disc, and the opposite
pole being presented at the centre of the former, and at the circumference of the
latter. The two discs thus magnetised being united at their centres by the soft iron
shaft, the whole would form a magnet having a north or south pole at the circum-
ference of the one disc, and the opposite pole at the circumference of the other.
Conversely when the two, cheeks are magnetised so as to have polarity of the kind
just mentioned, and when this polarity is alternated, then the central coil has currents
of alternate direction induced in it. For thus magnetising the cheeks I employ
the following arrangement :-I cut notches in their peripheries so that they present
a series of projections or teeth like those of a toothed wheel, and I fix them on their

page_text: common axis so that each tooth of the one directly faces a space between adjoining
teeth of the other. I cause them to revolve in front of the poles of stationary
magnets or electro-magnets so arranged that as the cheeks revolve their projecting
parts or teeth successively pass opposite poles of these magnets, and thus the
alternating polarity required is induced upon them, and corresponding currents are
induced in the central coil.
When I employ electro-magnets as the stationary inducing magnets I render them
active either by a separate battery or magneto-electric machine, producing alternating
currents, or by currents from the central coil itself, for which purpose I provide
suitable branches from the conductors leading to and from that coil. The machine
operating in this manner produces alternating currents, but it may by slight modifi-
cation be made to produce currents of constant direction, a commutator being for that
purpose applied to the central coil or its conductors.
When the machine is required to be of considerable power, its dimensions may be
increased, or preferably several sets of cheeks may be fixed on one driving shaft,
with their appropriate bobbins and magnets; the latter arrangement being
convenient, as it affords means of producing electricity either of considerable tension
or in considerable quantity,, as may be desired.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Paul Jablochkoff in the Great Seal Patent Office on the 14th February
1878.-
PAUL JABLOCHKOFF, of Paris (France), Engineer. "A MAGNETO-DYNAMO ELECTRIC
MACHINE."
My Invention relates to apparatus for the production of electrical currents by the
mechanical motion of magnetic bodies, such apparatus being known as magneto-
electric dynamo machines. A short bobbin of coiled insulated wire of diameter greater
than its length is placed between two soft iron cheeks or discs, which are fixed
on a soft iron shaft that passes through the heart of the bobbin, and the shaft and
cheeks are caused to revolve, the coil either remaining stationary or revolving with
them as required. In order that the principle on which this machine acts may be
understood, I will suppose an electric current is passed through the coil, each of the
cheeks would then become magnetic, one pole north or south being presented at the
circumference of the one and at the centre of the other disc, and the opposite pole
being presented at the centre of the former and at the circumference of the latter.
The two discs thus magnetised being united at their centres by the soft iron shaft,
the whole would form a magnet having a north or south pole at the circumference
of the one disc, and at the opposite pole at the circumference of the other. Conversely
when the two cheeks are magnetised so as to have polarity of the kind just
inentioned, and when this polarity is alternated, then the central coil has currents of
alternate direction induced in it. For thus magnetising the cheeks I employ the
following arrangement:-I cut notches in their peripheries so that they present a

page_text: series of projections or teeth like those of a toothed wheel, and I fix them on their
common axis so that each tooth of the one directly faces a space between
adjoining teeth of the other. I cause them to revolve in front of the poles of
stationary magnets or electro-magnets so arranged that as the cheeks revolve their
projecting parts or teeth successively pass opposite poles of these magnets, and thus
the alternating polarity required is induced upon them, and corresponding currents
are induced in the central coil.
When I employ electro-magnets as the stationary inducing magnets, I render them
active either by a separate battery or magneto-electric machine producing alternating
currents, or by currents from the central coil itself, for which purpose I provide
suitable branches from the conductors leading to and from that coil. The machine
operating in this manner produces alternating currents, but it may by slight modifi-
cation be made to produce currents of constant direction, a commutator being for
that purpose applied to the central coil or its conductors.
When the machine is required to be of considerable power its dimensions may be
increased, or preferably several sets of cheeks may be fixed on one driving shaft
with their appropriate bobbins and magnets, the latter arrangement being convenient
as it affords means of producing electricity either of considerable tension or in
considerable quantity, as may be desired.
Fig. 1 represents a longitudinal section, and Fig. 2 a front view of a magneto-dynamo
electric machine according to my Invention for producing alternating currents. A, B,
and C, D, are two powerful electro-magnets having cast-iron cores. Their poles are
separated by pieces K, K, of brass or copper; ff, are soft iron armatures; b is the
bobbin of coiled insulated wire which is kept stationary; and M, M, are the two
notched cheeks or discs, which revolve with the shaft, one on each side of the
bobbin. In order to excite the magnets A, B, and C, D, any known source of
electric power may be employed, or a small machine producing alternating currents;
or I can apply the alternating currents produced from the machine itself, in which
case the cores of the electro-magnets are preferably made of iron or steel, or hardened
iron. These magnets are in the first place excited by a strong current giving the
extremities A and D of the same polarity, and B and C the opposite polarity, and
being in hard iron or steel they retain the magnetism. On causing the shaft with
the cheeks M, M, to revolve, alternating currents are produced in the coil of b, which,
being led through the coils of the magnets, as shewn by the diagram, Figure 3,
produce the following results :-The current in flowing from X to Y divides into the
two branches u, u¹, z, z¹. Half the current, say z, z', would increase the force of the
poles A, B, and the other half u, u', would diminish that of C, D. But this
diminution is searcely sensible, the previous magnetic force being retained by
induction from the opposite poles A and B, and this magnetism causing resistance in
the line u, u', so as to reduce the amount of electrical force passing by that line.
When the current passes from Y to Z the conditions are inverted.
Thus I am
enabled to re-inforce both magnets by means of the alternating currents without
changing their polarity. The alternating currents produced by the machine above
described may be deviated by any known commutator so as to give currents of one
direction at each terminal. Also by means of such commutator continuous currents
may be transmitted through the coils of the electro-magnets, which in this case
should have soft iron cores.
Having thus described the nature of my Invention, and in what manner the same
is to be performed, I claim the use of a magneto-dynamo electric machine, constructed
and operating substantially as herein described, wherein to alternately notched iron
discs, one on each side of a coiled bobbin of insulated conducting wire, are caused to
revolve in the opposite polar fields of two magnets, the discs becoming thus alternately

page_text: magnetised by induction, and causing alternating electric currents in the coil of the,
bobbin.
In witness whereof, I, the said Paul Jablochkoff, have hereunto set my hand.
and seal, this Twenty-eighth day of January, in the year of our Lord One
thousand eight hundred and seventy-eight.
:
Witness.
CHARLES ARMENGAUD,
Civil Engineer,
Bd. de Strasbourg, 23,
á Paris.
PAUL JABLOCHKOFF. (L.S.)