IMPROVEMENTS IN ELECTRO MAGNETS AND INDUCTION COILS
Year: 1885

page_text: I, CHARLES DENTON ABEL, of N° 28 Southampton Buildings, Chancery Lane in
the County of Middlesex, Consulting Engineer and Patent Agent,. do hereby
declare the nature of my invention for "IMPROVEMENTS IN ELECTRO MAGNETS
AND INDUCTION COILS and in what manner the same is to be performed to be
particularly described and ascertained in and by the following statement :-
در
It has been discovered by my correspondent that the magnetisation of a bar of
soft iron by an electric current is effected in exactly the same manner as that in
which whirlpools, waterspouts or cyclones are produced; in consequence thereof
the soft iron core of an electro magnet or induction coil is according to the present
invention, constructed of such a configuration as to correspond with the aggregate
form assumed by the girating particles of a whirlpool &c., that is to say, it is made
in the form approximating to that of two cones or conoids meeting at their apices,
the poles of the core being consequently of considerably larger diameter than its
middle. Various geometrical forms satisfying this condition can be employed;
those employed by preference are the hyperboloid of revolution, the hyperboloid
with three axes, or of elliptical cross section, a bar whose sides are formed by the
movement of a hyperbola along a loop shaped directrix, an annulus, the inner and
outer peripheries of which are of hyperbolic configuration, &c. The windings of
copper wire upon cores of such shape will consequently gradually increase in extent
towards the outer layer, while in the direction of the length of the core they will
gradually diminish in number from the middle towards the two poles. The outer
windings at the poles are by preference retained in place by a slight flange or bead
formed round the poles of the core.
The inner end of the wire coils may either be secured to the core or it may be
placed in a longitudinal groove extending from the middle to the one pole. Such
electro magnets may consist either of a single core or of two or more cores secured
to a base which may be either flat or curved so as to constitute a horseshoe magnet;
or the poles may be united by a plate at both ends; or again, two or more such

page_text: cores may be united end to end, with or without the intervention of cylindrical
parts between them, forming either straight bars, or rings such as the Paccinotti
ring.
Instead of forming the cores as complete hyperboloids of rotation they may
consist of semi or parabolic hyperboloids, the wires being coiled round the flat faco
as well as the hollow curved face; they may be either solid or hollow and either
formed of one piece or of several flat plates secured together.
Instead of forming the cores of the exact hyperbolic configuration, they may be
of approximate form such as two abutting conical or pyramidal frustra, with or
without the intervention of a cylindrical part.
In applying such electro-magnets to the formation of dynamo-machines of the
Lontin type, an exciting electro magnet is formed of two parabolic hyperbolids,
connected at one end by a base, and having at the other ends polar extensions,
between which revolves an armature consisting of a series of hyperboloidal cores
having their axes radiating from a central axis of revolution to which they are
connected by a central boss.
In employing a plate armature in connection with two hyperboloidal cores
connected by a plate at one end, such armature, if intended to support a weight
while in contact with the electro magnet, is made prismatic and extends only to
the two centres of the hyperboloids, whereas if the armature is connected to a lever
and is to be attracted by the electromagnet, it is made as a flat plate extending
over the entire polar surface of the electromagnet.
The coiling of the wire round the cores may either be made to extend only so far
as to produce a cylindrical configuration of the electromagnet, or the coils may be
extended beyond that point, being gradually diminished in number towards the
outside. In connecting two or more such hyperboloidal cores together by means of
half round bars at each pole, the coiling may either be effected separately round
each one, or a continuous coil may be formed surrounding all the cores on the
outside only.
43 44
...
1005

page_text: COMPLETE SPECIFICATION.
Improvements in Electro-magnets and Induction Coils.
I, CHARLES DENTON ABEL, of N° 28 Southampton Buildings, Chancery Lane in
the County of Middlesex, Consulting Engineer and Patent Agent, do hereby
declare the nature of this invention and in what manner the same is to be
performed to be particularly described and ascertained in and by the following
statement
It has been discovered by my correspondent that the magnetisation of a bar of
soft iron by an electric current is effected in exactly the same inanner as that in
which whirlpools, waterspouts or cyclones are produced; in consequence thereof
the soft iron core of an electro magnet or induction coil is, according to the present
invention, constructed of such a configuration as to correspond with the aggregate
form assumed by the gyrating particles of a whirlpool &c., that is to say, it is
made in the form approximately to that of two cones or conoids meeting at their
apices, the poles of the core being consequently of considerably larger diameter
than its middle. Various geometrical forms satisfying this condition can be
employed; those employed by preference are the hyperboloid of revolution, the
hyperboloid with three axes or of elliptical cross section, a bar whose sides are
formed by the movement of a hyperbola along a loop shaped directrix, an annulus,
the inner and outer peripheries of which are of hyperbolic configuration, &c. The
winding of copper wire upon cores of such shape will consequently gradually
increase in extent towards the outer layer, while in the direction of the length of
the core they will gradually diminish in number from the middle towards the two
poles. The outer windings at the poles are by preference retained in place by a
slight flange or bead formed round the poles of the core.
The improved construction of electromagnets and induction coils will be readily
understood on reference to the accompanying drawings. Figs. 1 and 2 shew
respectively an elevation and a plan of a hyperboloid shaped core, being formed by
the revolution of a hyperboloid round a central axis, the equatorial diameter being
about equal to one sixth of the height, from which it follows that the diameter at
the ends or poles of the core is about equal to the height thereof. Figs. 3 and 4
shew an elevation and plan of a hyperboloid core with three axes, the polar
surfaces being of greater length than width. By fixing two cores similar to that
shewn at Figs. 1 and 2 upon a common base a very powerful electromagnet will
be obtained as shewn at Fig. 5. The base will have a weight that will. vary
according to its length from a weight equal to that of one of the cores of the
electromagnet to three times that weight.
According to the use to which the electromagnet is to be applied the base may
be variously formed. Thus, it may have the form of a plate having a width equal
to the polar diameter of the cores and a length equal to somewhat more than twice
that diameter as shown at Fig. 6.
"

page_text: Fig. 5 shews a vertical section of an electro magnet with two cores a a connected
by the base screwed thereto which is shown in plan at Fig. 6. The edge of the
base is bevilled off so as to form a continuation of the hyperbolic surfaces of the
cores a a. When an electromagnet is required to support a weight a prismatic
armature c is employed having a small thickness and the maximum length of
which is exactly equal to the distance between the two axes of the cores as shewn
at Fig. 5; but when it is desired to attract an armature fixed at the end of a lever,
such armature is made similar in shape to that of the base, its weight being
regulated according to the purposes for which it is employed.
For facilitating the coiling of the copper wires d d on the cores a a the following
precautions should be observed.
1. The polar surface of each core is provided with a projecting bead or flange e
made as small as possible and just sufficient to afford a point of suppor to the
last coil of the wire.
2. If it is not desired to solder upon the core the inner end of the wire coil,
a groove i is formed in the direction from the equator to the pole next to the base,
such groove being sufficiently wide and deep for containing the end of the wire as
shewn at Fig. 5. In winding the wire upon these hyperbolical cores the lengths
of the successive layers of wire will gradually increase. At Fig. 5 the coiling of
the left hand core is shewn carried out to the point where the coiling assumes a
cylindrical form.
Fig. 7 shews a hyperbolical core produced by causing a hyperboloid to follow a
given directrix, producing a configuration of core as shewn in plan at Fig. 8, which
also shews the form of base for connecting together two cores of the construction
shewn at Fig. 7. Instead of forming these cores of a single piece they might be
built up of a number of separate sections as indicated in elevation and plan at
Figs. 14 and 15.
When it is desired to obtain an induction coil having long polar faces, a core is
formed of a certain number of hyperboloids with three axes such as is represented
at Figs. 3 and 4. Each core a is coiled with wire d d and they are connected
together by their poles by means of two soft iron bars of half round shape f f
screwed thereto as shewn in elevation and longitudinal and transverse sections at
Figs. 9 and 10.
Fig. 11 shews a form of electro-magnet in which the hyperbolic cores with three
axes are first fixed between two half round bars of soft iron ff and are then
coiled simultaneously with wire d, the successive layers of which surround all
three cores. At Figs. 9, 10 and 11, the coiling instead of being stopped when it
attains a cylindrical form is continued in gradually diminishing the length of the
coils.
Figs. 12 and 13 shew an elevation and plan of a hyperbolic core having a
parabolic cross section. For obtaining flat electromagnets with very large polar
surfaces the cores receive the form of crowns or rings of hyperbolic section as
shewn at cross section and plan at Figs. 16 and 17. Two similar electromagnets
may be connected by a base such as is shewn in plan at Fig. 18 which is fixed
thereto by screws. The coiling is effected upon the external groove of the core.
The annular cores might also be formed with a semi-hyperboloid section as shewn
at Fig. 19.
In certain cases, by sacrificing more or less useful effect, the exact geometrical
forms and characteristics hereinbefore referred to may be more or less departed
from, the cores receiving a form that satisfies to a greater or less degree of
approximation the conditions upon which the construction of these cores is based.
Various examples of such modifications are shewn in Figs. 20 to 23.
Fig. 20 shews a magnetic core formed of two conic frustra .connected together
at their smaller ends, Fig. 21 shews a core formed of two conic frustra connected
by a column having a slightly curved surface, Fig. 22 shews a core formed of
two conic frustra connected by a cylinder and Fig. 23 shews a core formed of two

page_text: truncated pyramids connected together at their smaller ends. These truncated
pyramids might also be connected as shewn at Figs. 21 and 22. If it is desired to
obtain an electromagnet having one or more poles greater in intensity than in
extent of surface, two or more such cores may be connected end to end, being
formed of a single piece of iron, either with or without the interposition of
cylindrical columns as shewn in Figs. 24 and 25.
The above described cores of hyperboloid form or of hyperbolic paraboloid form
may be either solid or hollow.
Fig. 26 shews the section of a hollow paraboloid core, Fig. 27 shews the
combination of two hyperboloid cores a a to form a horse shoe magnet by con-
nection with a looped piece b1, Fig. 28 shews the application of the hyperboloid
cores to a Lontin dynamo electric machine, Fig. 29 shews them applied to a
Paccinotti ring.
The exciting electro magnet of the Lontin machine modified according to the
present invention as shewn at Fig. 28 is formed of two cores having the shape of
paraboloids of hyperbolic cross section a¹ a¹ while the bobbins of the revolving
armature are formed with cores of hyperboloid shape a² arranged perpendicularly
to the axis of rotation. Lastly, at Fig. 29, the coiling of the bobbins of the
Paccinotti ring is effected upon grooves of hyperboloid shape a³ formed in the ring A.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is
1. Constructing electromagnets or induction coils such as are used for electrical
machines, or motors, telephones and the like, with soft iron solid or hollow cores
of such a geometrical configuration that their mass increases from the middle
towards the two poles, substantially as herein described with reference to the
accompanying drawings.
2. Constructing electro magnets such as are referred to in the preceding claim
of the form of a hyperboloid of revolution, or of a hyperboloid of three axes, or of
a hyperbolic paraboloid, or of a bar of hyperbolic or semi hyperbolic section, or of
two conic or pyramidal frustra, connected together at their smaller diameters, or
with the intervention of a cylindrical or other shaped part, substantially as herein
described with reference to Figs. 1, 2, 3, 4, 7, 8, 12, 13, 14, 15, 16, 17, 19, 20, 21,
22, 23 and 26 of the drawings.
3. The method of coiling the cores of electromagnets such as are referred to in
the preceding claims, so that the length of the successive layers of wire gradually
increase, the coiling being continued until the hollow of the core is filled out, a
fillet or bead being provided on the polar ends for retaining the outer coil of wire,
substantially as described with reference to Fig. 5 of the drawings.
4. In coiling cores of electromagnets as described in the preceding claim, the
method of continuing the coiling in layers of decreasing length beyond the point
at which the hollow of the core is filled out, substantially as herein described, with
reference to Figs. 9, 10 and 11 of the drawings.
5. The method of coiling several cores with a single coiling of wire and of
connecting the poles of the cores with soft iron bars, substantially as described with
reference to Fig. 11 of the drawings.
6. The combination of two electro magnet cores increasing in diameter from the
middle to the poles, with a base connecting them at one end, such base being either
a flat plate or of curved shape substantially as described with reference to Figs. 5 6
and 27 of the drawings.
7. Constructing the electromagnet cores of hyperboloid or of hyperbolic para-
boloid shape substantially as herein described with reference to Figs. 24 and 25.
8. Constructing Paccinotti rings with hollows of hyperboloid or hyperbolic
paraboloid shape, in which the conducting wire is coiled substantially as herein
described with reference to Fig. 29.

page_text: 9. In a Lontin electrical machine, the combination of an exciting electro-
magnet having a core of hyperbolic paraboloid shape with a rotating armature
having bobbins with hyperboloid shaped cores, arranged radially round the axis
of rotation substantially as herein described with reference to Fig. 28 of the
drawings.