IMPROVEMENTS IN ELECTRO MOTORS PROVISIONAL SPATION
Year: 1882

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LETTERS PATENT to Leonard Milne of 115 St. Georges Road Pimlico in the
County of Middlesex Civil Engineer and Leslie Bradley Miller of 34 Darnley
Road in the County of Middlesex Electrical Engineer for an Invention of
IMPROVEMENTS IN ELECTRO MOTORS
PROVISIONAL SPECIFICATION left by the said Leonard Milne & Leslie
Bradley Miller at the Office of the Commissioners of Patents on the
20th December 1882.
LEONARD MILNE of 115 St Georges Road Pimlico in the county of Middlesex
civil engineer & LESLIE BRADLEY MILLER of 34 Darnley Road Hackney in the
County of Middlesex Electrical Engineer "IMPROVEMENTS IN ELECTRO-MOTORS
;
Our invention relates to electro-motors or machines for generating electricity,
whereby we obtain efficiency combined with simplicity in construction. In our inven-
tion the armature consists of two coils of wire wound longitudinally on a X shaped
frame, of iron, brass or other material, at right angles to each other.
Or we may
wind the two coils on an iron core, with projections to separate them. The com
mutator is divided into four sections & the ends of each coil are brought to sections
diametrically opposite. By this means each of the coils is brought into action in
turn when approaching the most advantageous position in the magnetic field &
cut out to be replaced by the other when receding from it. We also make use of
two small springs on the commutator or other simple device by which if desired
the sections may be connected in pairs, & both coils brought into action at once."
With this armature we prefer to use field magnets with narrow pole pieces with
the object of concentrating the magnetic field on the coil which is in action.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Leonard Milne-and-Leslie Bradley Miller in the Great Seal Patent
Office on the 20th June 1883.
I lige
'
LEONARD MILNE of 115 St George's Road, Pimlico, in the County of Middlesex
Civil Engineer, and LESLIE BRADLEY MILLER of 34 Darnley Road in the County
of Middlesex, Electrical Engineer IMPROVEMENTS IN ELECTRO-MOTORS"
“
Our invention relates to Improvements in Electro-Motors whereby we obtain
efficiency combined with simplicity in construction.
Small Electro-Motors as heretofore constructed. have generally possessed the
serious defect of having a dead point so that if the electric current is switched on to
the Motor and its armature be at such dead point it will not move until it has been
partly turned round by an external mechanical force. Moreover the armatures of
small Electro-Motors are usually wound with only one coil & during that part of
a revolution in which this coil is nearly at right angles to the lines of force of the
magnetic field in which it is revolving the lines of force passing through or
threading it are only very slightly changed in number. When the coil is nearly
parallel with the lines of force threading the armature the greatest change of
number takes place for a given angular movement and since the work given out is
proportional to the product of this change into the current passing through the said
circuit the return or work given out differs widely during different parts of a
revolution.
'
The object of our invention is therefore to devise a motor whose construction,
whilst being exceedingly simple shall have no dead, point, shall give out more useful
work in proportion to the electric energy expended in driving it, & more uniformly
throughout an entire revolution, than is the case in any other similar machine.
For this purpose we wind the armature of our improved electro-motor with two
distinct and independent coils of wire. These coils are. wound longitudinally on
the armature at right angles to each other, and cross each other at the ends of the
said armature the core of which we construct of a cross shaped frame of iron, brass,
or other suitable material. Or the two coils may be longitudinally wound on a
-core provided with end pieces having projections arranged in the form of a cross,
the projections serving to retain the coils in position. Or instead: of winding the
wire between the arms of the cross or frame we may wind it on the arms them-
selves, but in this latter case the coils will not cross each other at the ends. The
commutator we employ is formed of four sections of copper or other suitable metal
and the ends of each coil are connected to sections diametrically opposite. The
brushes are placed parallel to each other bearing upon opposite sides of the com-
mutator which is so arranged that each armature coil is brought into action in turn
when in a position midway or nearly so between the neutral line and the line
joining the centres of the two poles of the field magnet, that is when approaching
the most efficient or advantageous position in the magnetic field, & cut out to
be replaced by the other coil when in a similar position in receding from the
said poles.
1 .
We prefer to employ with our improved form of armature a field magnet with
narrow pole pieces, extending the whole length of the armature or nearly so, so as
to concentrate the magnetic field as much as possible on the armature coil in circuit
for the time being
In order that our invention may be better understood we will more particularly
describe the same with reference to the accompanying drawing in which Figure 1.
is an end view of the said improved motor with the journal bracket supporting the

page_text: commutator brushes removed. Figure 2 is a horizontal section of the same on the
linex of Figure 1. Figure 3 is a transverse section of the said electro-motor.
Figure 4 represents in side elevation the form of armature core or frame which we
prefer to employ. Similar letters of reference represent corresponding parts in all
the figures
In these figures A represents the armature of our improved electro-motor
composed of a cross-shaped frame or core B of iron or other suitable material upon
which we wind two independent coils D, E, at right angles to each other as shown.
The two ends of the wire forming the armature coil D are joined to the two
diametrically opposite sections 1 and 3 of the 'commutator F and the two ends of
the coil E to the commutator sections 2 and 4 as shown in Figure 1. It will be
thus readily seen that each coil with its commutator sections is independent so that
they are not in circuit at the same time. The armature frame B is hollowed out at
its ends as shown at a, b, Figure 4, in order that the thickness of the two coils D
and E which cross each other at the ends of the said frame may not cause the wire
to project much beyond the end projections c of the frame. We prefer to wind the
two coils so that they may lie in alternate layers at the ends of the frame as shown
in Figure 2 where the coil E is shown in section by the small circles. The com-
mutator brushes are arranged parallel to each other and supported by a journal
bracket or in any other suitable manner. For the purpose of concentrating the
magnetic field upon the armature coil in circuit for the time being we may employ
a field magnet as shown in the accompanying drawing having two separate narrow
internal projections L, L' forming the poles on which the field magnet coils M M¹
are placed as shown. By this form of construction we obtain the concentrated
magnetic field desired for the purpose herein before mentioned.
It is obvious that we may vary the form of field magnet to be used with the
armature above described but we consider that it will always be advantageous
to employ a form of field magnet having narrow pole pieces for the purpose before
mentioned.
Having now fully described our invention and indicated what we consider the
best manner of carrying the same into effect, we claim
1st In an electro-motor the combination of an armature having two distinct coils
wound longitudinally at right angles to each other with a commutator having four
sections to which the ends of the coils are connected and so arranged that each coil
is brought alternately into and cut out of circuit substantially as hereinbefore
described and for the purposes specified
2nd In an electro-motor the combination of the armature and commutator above
referred to with field-magnet poles as hereinbefore described and for the purpose
specified.
In Witness whereof I the said Leslie Bradley Miller on behalf of myself
and the said Leonard Milne have hereunto set my hand and seal this
nineteenth day of June in the year of our Lord eighteen hundred and