IMPROVEMENTS IN ELECTRO MAGNETIC ENGINES ELECTRO MOTORS OR ELECTRO GENERATORS
Year: 1883

page_text: LETTERS PATENT to Robert Walter Macleod Fraser of the United Service
Club Pall Mall in the County of Middlesex, General in Her Majesty's Army
for an Invention of "IMPROVEMENTS IN ELECTRO MAGNETIC ENGINES ELECTRO
MOTORS OR ELECTRO GENERATORS communicated to him from abroad by
"
PROVISIONAL SPECIFICATION left by the said Robert Walter Macleod
Fraser at the Office of the Commissioners of Patents on the 1st June 1883.
ROBERT WALTER MACLEOD FRASER, of the United Service Club Pall Mall, in the
County of Middlesex General in Her Majesty's Army. "IMPROVEMENTS IN ELECTRO
MAGNETIC ENGINES, ELECTRO MOTORS OR ELECTRO GENERATORS," (a communication
to me from abroad by John Randal Fraser, of Gibraltar, Lieutenant in Her
Majesty's Army)
This Invention consists of two Siemens or other armatures having their centres
of rotation in the same straight line or in any other position, and revolving
together, their magnetic faces being set at suitable angles to each other.
These armatures are partly encircled by field magnets, having their poles
concentric with the faces of the armatures, and about the same size as the faces of
the armatures
The current passes into these armatures and through their field magnets
alternately. The current passes through the field magnets and armatures only at
the time when the armatures and magnets will attract each other.-This is effected
by cutting the current off when it would cause the armatures to be repelled by
the magnets.
I. 1.
2.
This current which is cut off one set, is sent through the other, which is at
attraction, thus greatly increasing the current in that armature, and thereby
materially increasing the power.
This principle is applicable to all electro magnetic engines, electro-motors or
electric generators, especially of the Siemens type, but also of any other.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Robert Walter Macleod Fraser in the Great Seal Patent Office on
the 27th November 1883.
ROBERT WALTER MACLEOD FRASER of the United Service Club Pall Mall in the
County of Middlesex General in Her Majesty's Service IMPROVEMENTS IN ELECTRO
MAGNETIC ENGINES, ELECTRO MOTORS-OR-ELECTRO GENERATORS, A communi-
cation to me by John Randal Fraser of Gibraltar-Lieutenant in her Majesty's
Army
This Invention relates to dynamo electric, and electro dynamic machines; and
to the use of two armatures, having their centre of rotation on the same, or on
connected armature spindles and revolving together, their magnetic Faces being set
at suitable angles to each other, namely in the case of the Siemens type of
armature at 90 degrees apart, or within one, or a few degrees of that angle; or
stated more generally, the contact surfaces of the commutator must each have
such a circumferential length, and their respective brushes must be so placed, that
there shall be no assignable time interval, between the breaking of contact between
one commutator surface and its brush or brushes, and the making of contact
between the surface and the brush or brushes of the other commutator. This is
done to prevent the occurrence of any dead point in the rotation of the Armatures.
These armatures are partly encircled by Field Magnets, having their poles concentric
with the faces of the armatures, and about the same size as the faces of the
armatures.
The whole current passes into each armature and through its field magnets,
alternately with the other armature and its field magnets, half the time in one set
or couple, and half the time in the other set or couple. The current passes through
the field magnets and armatures only at the time, when by every alternate
quadrant of the commutator being insulated, by a space between their approaching
edges, which may be filled with insulating material; the armatures and magnets
will attract each other. This is effected by cutting the current off, when it would
cause the armatures to be repelled by the magnets. This current which is cut off
one set, namely the set in which the armature is receding from its field magnets,
is put through the other, in which the armature is approaching the magnets, or
which is at attraction; thus greatly increasing the current available for that
armature, and thereby materially increasing the power.
This principle is applicable to all electro magnetic engines, electro motors, and
electro generators, especially of the Siemen's type, but also of many others.
Having thus far described the nature of my Invention, I will now proceed to
describe the same, by reference to the accompanying drawings.
Fig 1. Shows diagram of Commutators.
Fig 2. Isometrical view of an elementary form of Siemen's armature, as herein
referred to.
Figs 3 and 4. Are respectively plan, and perspective elevation of a simple form of
machine with Siemen's armatures and fitted with commutators according to
my invention.
The armatures are of the ordinary (H) pattern Siemen's type wound with
conveniently sized insulated copper or other suitable wire.
The ends of the wires are fixed to the commutator on the spindle, and are made
up as shown in Fig 2.

page_text: A. and B. are two quadrants, or segments of a circle; the word quadrant being
here used, as is common amongst machinists, as signyfying a true quadrant of
90 degrees, or a part of a circular arc which may be rather less or more than
90 degrees; and are of a metal non-magnetic, such as brass.
C is an insulator. and D the spindle of the armature.
The current from a battery or any other source of electricity, passes through the
electro-magnets of one set, thence to the commutator spring or brush X-from X
through the armature, out at Y-and back to the source.
From the diagram it will be seen, that no current can pass unless the spring
brushes X and Y. - are on the faces A and B-because C is an insulator. The
commutators are so set on the spindle D that their four quadrants, or segments
make up the circle within the limits above mentioned, that is to say they may for
instance slightly overlap, so that the current is always passing in one or other of
the set, that is one armature or its field magnets.
The commutators are so adjusted, and put on with regard to the armatures, that
the current passes, only when the armatures and field magnets will attract one
another.
Having thus particularly described, and ascertained the nature of my said
Invention, and in what manner the same is to be performed; I would have it
understood, that I do not confine myself, to the precise form, or proportions of the
parts of the machine as here shewn and described; and I do not claim the
armatures and machine here shewn; but I hereby declare that I claim as my said
Invention the Improvements in electro magnetic engines, electro motors, or electro
generators, substantially as set forth and described, wherein the peculiar and
important feature, is the arrangement and relation of the commutator to the field
magnets and armature poles, by which the whole electric current, is shunted
through each armature and its field magnets, when the poles will attract each
other, and shunted from them when they would repel each other, substantially as
herein set forth and described.
In Witness whereof, I, the said Robert Walter Macleod Fraser, have hereunto
set my hand and seal, this twenty seventh day of November in the year of our
Lord, One thousand eight hundred and eighty three.
D
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