AN IMPROVED ELECTRO-MAGNET
Year: 1876

page_text: LETTERS PATENT to Paul Jablochkoff, Engineer, No. 23, Boulevard de
Strasbourg, at Paris, for the Invention of "AN IMPROVED ELECTRO-MAGNET."
PROVISIONAL SPECIFICATION left by the said Paul Jablochkoff at the
Office of the Commissioners of Patents on the 29th February 1876.
PAUL JABLOCHKOFF, Engineer, No. 23, Boulevard de Strasbourg, at Paris.
IMPROVED ELECTRO-MAGNET."
<< AN
My Invention relates to an improved construction of electro-magnets wherein the
conducting coils are brought into direct metallic contact with the soft iron core.
For this purpose I employ for the conducting coil by preference a thin metallic
band coiled upon the core in such a manner as to have one of its edges in direct
metallic contact with the core, while the flat surfaces of the successive coils are
separated from each other by an interposed band of non-conducting material such as
paper.
According to one arrangement of such electro-magnets, I make the soft iron core
in the shape of a flat disc, upon the flat surfaces of which are placed conducting coils
of thin metallic bands wound spirally round a central wood core, the one edge of the
band being in direct metallic contact with the disc, while the flat surfaces of the
successive coils are separated by a band of insulating material coiled on together
with the conducting band. In this case the poles of the magnet are at the centre
and circumference of the disc, and their combined action may be made available by
placing an iron stem in contact with the centre of the disc and an iron ring sur-
rounding the periphery thereof, such stem and ring thus constituting the poles which
The before-mentioned
are connected by an armature consisting of a flat iron disc.
disc of soft iron constituting the core may be convex or concave instead of flat.
According to another arrangement the said metallic band is coiled helically round
a soft iron core of the ordinary horseshoe form; if this is of rectangular or poly-
gonal transverse section the band is folded over on itself at every angle so as to bring
one of its edges in contact with the side of the core, and if the core is of a circular
or oval section, the conducting band is specially made of a true helical form either
by cutting a flat copper dise with central hole into a helical shaving or by immer-
sing a disc of some other suitable soft metal or material into a galvanic bath of
sulphate of copper, and as the electro deposit is formed thereon cutting the disc into
1

page_text: a helical shaving. Or the helical shaving of soft material may be first formed and
then placed in the bath.
Although it is preferred to use soft iron cores for such electro-magnets yet in
cases where the residuary magnetism is of advantage, cast iron may be used for
this purpose.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Paul Jablochkoff in the Great Seal Patent Office on the 27th July
1876.
PAUL JABLOCHкOFF, Engineer, No. 23; Boulevard de Strasbourg, at Paris.
IMPROVED ELECTRO-MAGNET."
<< AN
My Invention relates to an improved construction of electro-magnets wherein
the conducting coils are brought into direct metallic contact with the soft iron core.
For this purpose I employ for the conducting coil by preference a thin matallic band
coiled upon the core in such a manner as to have one of its edges in direct matallic
contact with the core, while the flat surfaces of the successive coils are separated
from each other by an interposed band of non-conducting material such as paper:
According to one arrangement of such electro-magnets I make the soft iron core
in the shape of a flat disc, upon the flat surfaces of which are placed conducting coils.
of thin metallic bands wound spirally round a central wood core, the one edge of
the band being in direct metallic contact with the disc while the flat surfaces of the
successive coils are separated by a band of insulating material coiled on together
with the conducting band. In this case the poles of the magnet are at the centre
and circumference of the disc, and their combined action, may be made available by
placing an iron stem in contact with the centre of the disc and an iron ring
surrounding the periphery thereof, such stem and ring thus constituting the poles
which are connected by an armature consisting of a flat iron disc. The before-
mentioned disc of soft iron constituting the core may be convex or concave instead of
flat.
According to another arrangement the said metallic band is coiled helically round
a soft iron core of the ordinary horse-shoe form; if this is of rectangular or
polygonal transverse section the band is folded over on itself at every angle so
as to bring one of its edges in contact with the side of the core, and if the core
is of a circular or oval section the conducting band is specially made of a true
helical form either by cutting a flat copper disc with a central hole into a helical
shaving, or by immersing a disc of some other suitable soft metal or material into
a galvanic bath of sulphate of copper, and as the electro deposit is formed thereon,
cutting the disc into a helical shaving. Or the helical shaving of soft material
may be first formed and then placed in the bath.
Although it is preferred to use soft iron cores for such electro-magnets yet in
cases where the residuary magnetism is of advantage cast iron may be used for
this purpose.
DESCRIPTION OF THE DRAWINGS.
Fig. 1 is a vertical section and Fig. 2 a plan of a disc electro-magnet according to
my Invention. A band or strip a of copper or other suitable conducting metal along
with a strip d of paper, cardboard, or other non-conducting material is wound
spirally round a core b of wood or other non-conducting material, so that the edge
of the conducting band or strip rests against the face of the disc c, each convolution
of a being separated from the next by the non-conducting band d which is wound
along with it. A similar arrangement may be applied to the opposite side of
the disc c, as shewn in Fig. 1. As an electro-magnet is thus produced having one
pole at the centre of the disc and the other at the circumference, I complete
the magnetic circuit and apply an armature in the manner shewn in Fig. 3, which

page_text: represents a section of a disc magnet having the coil on one side.
A central stud f
and an outer ring g form respectively polar extensions to which an armature / can
be applied. The disc instead of being circular might be of square or polygonal
form, the coil being wound on a core b of suitable form; also the surface of the disc
might be concave or covex, and the metal coil might be wound without making
absolute contact with the surface of the disc.
Fig. 4 is an elevation of a horse-shoe magnet coiled with a helical band or strip.
When the iron horse-shoe core is of rectangular section, as shewn in the plan Fig. 5,
the strip can be wound round it by folding it over at the angles. When the core is
cylindrical I prepare a helical coil in the manner shewn in the section, Fig. 6, in
which is a disc mounted on an axis and partly immersed in a bath of copper
sulphate or of a solution of other metallic salt. The disc having one of its faces
conducting is connected to a battery and turned slowly round so that the metal
base of the solution is deposited by electro-plating on the conducting face of the disc,
and, being stripped off as it is formed, produces a continued helix m that can
afterwards be wound on an iron core.
Having thus described the nature of my Invention and in what manner the same
is to be performed, I claim, the construction of an electro-magnet by winding in
spiral or helical form a band or strip of copper, or other suitable conducting metal
on the face of an iron disc or an iron core, the edge of the band or strip being
presented towards the disc or core, and its successive convolutions being separated
by a strip of non-conducting material wound along with it, substantially as herein
described.
In witness whereof, I, the said Paul Jablochkoff, have hereunto set my hand
and seal, this Eighteenth day of July, in the year of our Lord One thousand
eight hundred and seventy giv
Witness,
ARMENGAUD, Jeune,
Civil Engineer,
Boulevard de Strasbourg,
23, Paris.
P. JABLOCHKOFF. (L.S.)