IMPROVEMENTS IN DYNAMO ELECTRIC AND MAGNETO ELECTRIC MACHINES
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by Ernest de Pass at the Office of the
Commissioners of Patents on the 19th September 1881. A communication.
from abroad by La Société anonyme des Câbles électriques, système Berthoud,
Borel, et Compagnie, of Paris, France.
C
ERNEST DE PASS, of the Office for British and Foreign Patents, 68, Fleet Street,
in the City of London, Patent Agent. "IMPROVEMENTS IN DYNAMO ELECTRIC
AND MAGNETO ELECTRIC MACHINES." A communication from abroad by La
Société anonyme des Câbles électriques, système Berthoud, Borel, et Compagnie, of
Paris, France.
The electric motor which forms the subject of the present application for Patent
is based on the deflection or deviation produced by a current on a magnet or
electro-magnet placed within a circuit. It consists substantially of a fixed circuit,
within which a Siemens coil or an electro-magnet is arranged, the wires of which
always receive a current in the same direction, whilst the surrounding coil is
traversed at each half revolution by reverse currents.
Such is the principle on which this motor is based, it is that of the galvanometer.
It consists of three essential parts, viz., a movable electro-magnet, a fixed coil
placed around the magnet, and a commutator.
The electro magnet is formed of a rectangular bar of iron, on which two bands
of the same metal are fixed, so that it represents in section a double T with curved
flanges or shoes. One end of the wire of the coil is fixed to the core itself, and the
other end is attached by means of a screw to the.commutator.
Around this electro magnet and parallel with its axis is placed the fixed outer
coil, which consists of copper wires carefully insulated from each other and from
the frame work of the machine. The two ends of the wire of the fixed outer coil
terminate at the commutator in two friction devices mounted on terminals. The
commutator is composed of two parts mounted on an insulating bush or sleeve
fixed on the shaft of the machine.
The operation of this improved machine is.as follows:-
One of the poles of a source of electricity is brought into communication with
the frame of the machine by a terminal, the current passing into the coils of the
electro magnet at the end fixed to the core, and leaving it at the other end, attached
Pris 31

page_text: to one of the parts of the commutator. The current then passes into the fixed coil
through one of the friction devices, and leaves it by the other to pass to the
terminal, where the current from the other pole of the electric source reaches it.
The commutator, producing a reversing of the current in the fixed coil at each
half revolution of the electro magnet, it will be clear that this magnet has a
continuous motion which will always be in the same direction, whatever may be
the arrangement of the wires which connect the electric source to the machine.
It must be remarked that in this system the coil of the electro magnet being
always traversed by the current in the same direction, no electricity is required for
producing the successive magnetizations and demagnetizations as in other motors,
consequently the heating of the machine is reduced, and the electricity is more
fully utilized.
It must also be remarked that in certain cases, and particularly in that in which
the machine is to serve for converting power into electricity, it will be advan-
tageous to substitute a permanent magnet for the electro magnet, which will
convert this dynamo electric machine into a magneto electric machine.
Where alternating currents are to be collected, one of the wires of the fixed coil
must be connected to a supplementary bar, and two bars then collect the alter-
nating currents.
In certain special cases the machine just described having a dead point might
present inconveniences.
Several very simple arrangements may be used for obviating these defects; for
instance, it would be sufficient to place two machines end to end, giving to them a
common axis, the wires of one of the electro magnets being coiled at a right angle
to those of the other.
The same effect may be attained by connecting two machines placed side by side
by means of suitable gearing.
Lastly, a single coil may be employed, on which the wire is wound in several
sections connected to an ordinary commutator, like those in the machines of
Gramme, Siemens, and others. This last arrangement is preferable for very
powerful motors.