IMPROVEMENT IN DYNAMO ELECTRICAL MACHINES
Year: 1882

page_text: LETTERS PATENT to John Farquharson of Pomona House Kings Road Fulham
in the County of Middlesex England for an invention of AN IMPROVEMENT IN
DYNAMO ELECTRICAL MACHINES
PROVISIONAL SPECIFICATION left by the said John Farquharson at the
Office of the Commissioners of Patents on the 13th June 1882.
JOHN FARQUHARSON of Pomona House, Kings Road Fulham
IN DYNAMO ELECTRICAL MACHINES
IMPROVEMENTS
The object of this invention is an improved method of developing magnetic force
in soft iron by means of an electric current.
The means employed consists in placing soft iron between as well as beneath the
layers of insulated wire forming the electric circuit; by this means the second and
following layers outwards forming the Coils or bobbins are brought nearer the iron
than heretofore.
To prevent circular currents in the iron, narrow bars, wires or rods are preferred.
Fig 1 in the drawing is a Coil or bobbin with the end removed shewing in black
the ends of the soft iron bars between the layers of insulated wire. Fig 2 is an
elevation of a Dynamo Machine Fig 3 is a plan of the armature with bobbins
Fig 4 is the frame of the Machine

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Farquharson in the Great Seal Patent Office on the
5th December 1882.
JOHN FARQUHARSON of Pomona House Kings Road Fulham in the County of
Middlesex England IMPROVEMENTS IN DYNAMO ELECTRICAL MACHINES
An improved method of developing magnetic force in iron magnets and for
turning and for directing the lines of force into the field or armature path This
is effected by building up the Magnets of alternate layers of iron and wire by this
means the insulated wire in which the exciting current circulates is brought nearer
to the iron and the loss of force due to the usual distance of the outer layers of
wire is thereby saved I make the core or central portion of a form suitable for
taking two or more layers of wire its transverse section being circular or any other
form suitable for its position in the machine, on this core I place two or more layers
of insulated Copper wire. Over this another layer of iron fitting closely, and which
may consist of several bars of soft iron or of one bar of suitable form open length-
wise to prevent circular currents in the iron, in this manner the electro magnet is
built up on this two or more layers of insulated wire is placed covered by a layer
of iron as before. The outside and the inside being iron.
The armature circuit consists of a narrow ribbon of copper arranged as described
hereafter the object sought being to revolve the whole in a magnetic field of high
intensity and to cut as many lines of force as possible, for this purpose the ribbon
is covered on one side with tape or other suitable insulating material, it is then
folded backward and forward. The folds being of equal length to suit the magnetic
field, the whole of the ribbon required is thus formed into a straight bar closely
pressed together its thickness being the width of the ribbon and its length being
the same as that of the metal ring or armature periphery, this ring has a U shaped
section one side being movable. The bar of ribbon formed as described is placed
on the periphery on its edge and readily lends itself to the circular form, the folds
opening at the outer edge It is then secured on its inner edge by the moveable
ring, the insulation of the conducting ring is completed by wedge shaped pieces of
wood or other suitable material, the outer ends of which project slightly beyond
the conductor and take the inward pressure of a band for keeping the ribbon firmly
in its seating. When the machine is to be self exciting a Section of the ribbon is
separated the ends being led to a suitable commutator
Fig 1 is an elevation of a Dynamo so constructed.
Fig 2 is a plan of the armature with a portion removed shewing the ribbon in
position.
Fig. 3 is a transverse Section of the ring
Fig 4 shews the manner in which the ribbon is folded
Fig. 5 is a longitudinal Section of a Field magnet with three layers of iron and
two layers of wire
In witness
Fig 6 shews the inner end of the magnet next to the armature.
whereof, I the said John Farquharson have hereunto set my hand and seal this
fifth day of December One thousand eight hundred and eighty two