Improvements in Cores and Armatures for Electro-Magnets, Solenoids, and the like.
Year: 1890

page_text: Date of Application, 11th Feb., 1890-Accepted, 22nd Mar., 1890
COMPLETE SPECIFICATION.
Improvements in Cores and Armatures for Electro-Magnets,
Solenoids, and the like.
I, STANLEY CHARLES CUTHBERT CURRIE, a subject of the Queen of England, but
now residing at the City of Philadelphia, in the County of Philadelphia, and State of
Pennsylvania, Electrical Engineer, do hereby declare the nature of my invention for
IMPROVEMENTS IN CORES AND ARMATURES FOR ELECTRO-MAGNETS AND OTHER
PURPOSES, and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statements:-
My invention relates to cores and armatures for electro-magnets and other
purposes.
The principal objects of the invention are first, to provide a comparatively
inexpensive and effective core or armature for an electro-magnet, for the armatures
and fields of dynamo-machines and other somewhat analogous purposes; and second,
to provide a core adapted for use in cases where the so-called "Foucault currents
are sought to be avoided, that is, where constant changes or reversals take place of the
current in the coils.
Heretofore the principal method availed of for the avoidance of said induced
currents has been to build up the cores of a considerable number of discs of iron
properly insulated from one another.
My invention consists firstly, in providing a core or armature of a compact mass
of iron in granular form such as iron chips, filings or shavings as hereinafter fully
described.
My invention consists secondly, of a core or armature formed by mixing or com-
biuing with iron filings chips or shavings an insulating substance or material in a
granular or liquid condition and then causing the same after being subjected to
pressure and drying to assume a compact mass; and
My invention consists thirdly, of a core or armature formed by mixing or com-
bining with iron filings, chips or shavings an insulating substance or material as
silicate of soda in a granulated or finely divided state or condition.
A convenient mode of carrying my invention into effect, is as follows :-
A certain quantity or percentage of iron chips, filings or shavings are mixed or
combined with a solution of silicate of soda and the mass or compound then subjected
pressure in a suitable appliance and allowed to dry.
to
The iron filings, chips or shavings previous to their admixture or combination with
the solution of silicate of soda may be subjected to a treatment to cause the surfaces of
said chips, filings or shavings of iron to become coated with a salt or salts of the
metal, which salt or salts is or are bad conductors of electricity. For example the
iron chips, filings or shavings may be oxidized in any preferred manner.
In some
cases by simply coating the iron chips, filings or shavings with a salt of the metal it
will serve to electrically insulate one chip, filing or shaving from another without the
employment of additional material or of resorting to any other treatment than that
above described.
The mass of iron chips, filings or shavings must be prepared so that each particle
will be thoroughly insulated from the other.
There are numerous applications that may be mentioned of my invention, for
instance, as the armatures of solenoids or as cores or armatures of electro-magnetic
5 devices such as are employed in electric meters or measuring instruments where
hitherto solid iron cores have been used.
In practice it has been found that by providing a core of armature formed of a mass
of fine particles of iron and with each thoroughly and electrically insulated from the
other that deeided advantageous features are obtained, for instance, in the application
0 of the invention to direct and alternating current devices.

page_text: The employment of the silicate of soda with iron chips, shavings or filings furnishes
an excellent mass for the formation of cores or armatures, due to the fact that in
instances of their heating no deteriorating effect is produced; and moreover, the
silicate of soda combined with the iron chips, shavings or filings gives a good binding
mass for the production of cores, armatures &c., for electrical appliances.
In some instances the core or armature may be constructed partially of
solid iron and partially of a compact granular mass as herein before described.
In the case of direct currents with the employment of cores or armatures constructed
in accordance with my invention, the intensity of magnetic attraction and repulsion
are both greatly diminished and as a consequence the proportionate ratios of increase
and decrease for equivalent currents. Of course where very strong magnetic effects
are required the invention cannot. well be employed, while on the other hand where
more even graduations and larger, ranges are sought it may be advantageously and
economically employed.
Having now particularly described and ascertained the nature of my "inven-
tion and in what manner the same is to be performed, 1 declare that what I
claim is:
1. A core or armature composed of a compact mass of granular iron, substantially
as and for the purposes described.
2. A core or armature composed of iron in granular form as chips, shavings or
filings coated with a salt of the metal, substantially as and for the purposes
described.
3. A core or armature composed of a mass of iron chips, filings or shavings, coated
with a salt or salts of the metal a bad conductor of electricity, substantially as and for
the purposes described.
4. A core or armature composed partially of solid iron and partially of iron chips,
shavings or filings and an insulating substance or material, substantially as and for
the purposes described.
5. A core or armature formed of a compact mass of iron filings, chips or shavings
coated with an insulating substance or material, substantially as and for the purposes
described.
6. A core or armature composed of a compact mass of iron chips, filings
or shavings and a binding insulating substance, substantially as and for the purposes
described.
7. A core or armature composed of iron chips, filings or shavings and a silicate,
substantially as and for the purposes described.
8. A core or armature composed of iron chips, filings or shavings and silicate of
soda, substantially as and for the purposes described.
9. A core or armature formed partially of iron in a granular form and an insulating
substance or materials and partially of a solid metal, substantially as and for the
purposes described.
10. A core or armaturé formed in part of iron chips, filings or shavings coated with
silicate of soda or.a salt of the metal and in part of the metal iron, substantially as and
for the purposes described.
Dated at Imiadeiphia, Pa., this Zŏth day of January A.D. 1890.
Dated at I miadeipnia, Fa., this 28th day of January A.D. 1890.
STANLEY CHARLES CUTHBERT CURRIE.!
W. P. Thompson & Boult,
Agents for the Applicant.