Improvements in Dynamo Electric Machines.
Year: 1890

page_text: Date of Application, 23rd July, 1890
Complete Specification Left, 17th Apr., 1891-Accepted, 30th May, 1891
PROVISIONAL SPECIFICATION.
Improvements in Dynamo Electric Machines.
I, ARTHUR ERNEST WADLEY of Winchcombe in the County of Gloucester
& Brixton in the County of Surrey, Electrician do hereby declare the nature of this
invention to be as follows:-
In most dynamo electric machines hitherto invented, an armature overwound with
wire revolves between the poles of an electro-magnet and in the magnetic system
thus formed, the magnetic circuit encounters in its path two distinct spaces or gaps
which are occupied partly by copper wire & partly by air-one space on each side
of the armature. Such spaces offer great resistance to magnetic induction and
prevent the armature being magnetised to its utmost extent and hence lessens the
electro-motive force produced by the machine. The object of my invention is to
construct a machine wherein one, at least, of these spaces is suppressed and the lines
of force, after entering the armature upon one side, are diverted out of its centre
instead of passing completely across it.
According to my invention I construct an armature of a cylindrical or spherical
shape built up of iron discs suitably insulated from each other and having iron
cheeks or extension pieces protruding from its centre at one or both ends of the
said armature along its axis of revolution in such a manner that the said cheeks or
extension pieces are capable of being brought into direct contact with, or close
proximity to, the pole or poles of one sign of the field magnets hereafter to be
described and thereby communicate magnetism to the said armature.
The body of this armature is wound with insulated wire in coils in a direction
parallel to its axis in order to induce electric currents therein,-the above described
cheeks or extension pieces being left bare for the purpose above described tiz. :-
bringing them into contact with the pole or poles of one sign of the field
magnets.
The armature above described revolves in or between the poles of field magnets
of the peculiar form hereinafter to be described in order to induce electric currents
in the coils of wire wound upon it. These field magnets are constructed in an
improved manner whereby greater solidity & compactness of form are attained than
heretofore. For this purpose I construct a compound field magnet consisting of
three cores placed side by side in a vertical position and in the same plane with
each other, joined together at the top by a yoke in the usual manner and upon the
base of each core I fit iron pole-pieces as described hereafter. The centre pole
is magnetised with an opposite polarity to the outside ones that is to say, the
centre pole is magnetised with a N polarity and the outside ones of a S polarity, or
I usually connect the outside poles together by a suitable mass of iron
in order to form a base for the entire machine.
vice versa.
The centre pole piece of the field magnets is a mass of iron bored out into a
semi-cylindrical shape to embrace the upper half of the face of the armature and
the two outside pole-pieces consist of blocks of iron of considerable mass bored out
to enable the above described cheeks or extension pieces of the armature to
revolve within them either with or without actual contact with the said outside
pole-pieces in order to magnetise the said armature and so induce electric currents
in the wire wound thereon.
Dated this Twenty-second day of July 1890.

page_text: COMPLETE SPECIFICATION.
Improvements in. Dynamo Electric Machines.
I, ARTHUR ERNEST WADLEY of Winchcombe in the County of Gloucester,
Electrician, 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:-
In most dynamo electric generators hitherto invented an armature overwound
with wire revolves between the poles of an electro magnet and in the magnetic
system thus formed the magnetic circuit encounters in its path two distinct spaces
or gaps which are occupied by copper wire, namely, one on each side of the
Such spaces or gaps being occupied by non-magnetic material offer
considerable resistance to magnetic induction and prevent the complete magnetisa-
tion of the armature and thereby lessen the electro motive force produced by such
machine.
armature.
The object of my invention is to construct a machine wherein one at least of
these spaces or gaps is suppressed and the lines of force after leaving one pole of
the field magnet and entering upon one side of the armature are diverted wholly,
or nearly so, out of its centre and pass uninterruptedly to the other pole of the
field magnet.
In carrying out my invention I construct an armature of a cylindrical or spherical
shape, built up of iron dises suitably insulated or separated from each other, having
iron cheeks or extension pieces protruding from its centre at one or both ends of
the said armature along its axis of revolution in such a manner that the said iron
cheeks or extension pieces are brought into direct contact with, or close proximity
to, the pole or poles of one sign of the field magnet of the machine as hereinafter
to be described and thereby induce magnetism in the body of the said armature.
The body of this armature is wound with insulated wire in coils in a direction
parallel to its axis in order to induce currents of electricity therein; the above
described cheeks or extension pieces being left bare for the purpose above described,
namely, bringing them into contact (or close proximity) with the pole or poles of one
sign of the field magnet.
My invention also relates to the construction of a compound field magnet of the
peculiar form hereinafter to be described for the purpose of magnetising the said
armature revolving therein and so induce electric currents in the coils of wire wound
on the said armature.
These field magnets are constructed in an improved manner whereby greater
solidity and compactness of form are attained than heretofore.
For this purpose I construct a compound field magnet consisting of three iron cores
or poles, placed side by side in a vertical position and in the same plane, joined
together at the top by a yoke or suitable mass of iron, and upon the base of each
coil I fit iron pole pieces as hereafter described.
The centre pole of the three is magnetised with an opposite polarity to the
outside poles, that is to say, the centre pole is magnetised with a N polarity and the
outside ones with a S polarity or vice versa. I usually connect these outside poles
by a suitable mass of iron to form a base for the entire machine. The centre pole
piece of the field magnet is a mass of iron bored out into a semi-cylindrical shape
to embrace the upper half of the face of the armature and I construct the two
outside pole pieces of blocks of iron of considerable mass bored out to enable
the above described cheeks or extension pieces of the armature to revolve therein
and so magnetise the same and induce electric currents in the wire wound on the
body of the said armature.
I usually magnetise the said field magnets by means of suitable coils of wire
wound on each of the above described vertical cores or poles or, alternatively, I
wind the two spaces on the yoke between the above described cores or poles with

page_text: wire, in either case the coils being joined up so as to magnetise the centre pole of
opposite sign to the outside ones.
I will now describe my invention by means of the drawings filed herewith.
Figure I shews a machine constructed according to my invention.
Figure II shews the method of construction of the armature thereof partly in
section and partly in elevation.
Figure III shews an alternative method of magnetising the three pole pieces of
the machine.
Referring to Fig. I, A is the armature as hereafter described with polar
extensions B. B. mounted on the spindle C. C. revolving in bearings D. D. This
armature revolves in or between the poles S. N. S. of the field magnet, the centre
pole N being hollowed out into a semi-cylindrical shape in the usual manner to
embrace the upper half of the armature and the polar extensions of the
armature, B, B pass through borings in the outside pole pieces S. S. of slightly
larger diameter than the said polar extensions so as to allow the said armature to
revolve freely and without friction in the said borings of the pole pieces and at the
same time to communicate magnetism to the body of the armature through the
medium thereof.
It is not necessary for the purpose of my invention that the polar extension of
the armature should pass through the pole pieces and alternatively I bring the end
of the extension pieces close up to the inner face of the said outside pole pieces and
so communicate magnetism to the body of the armature.
I usually magnetise the poles S. N. S. of the field magnets by the vertical cores
wound with coils E, F, G, and joined together by the yoke H in the usual manner
or alternatively I construct a modification of the field magnet illustrated in
Figure III in which the pole pieces S, N. S. are magnetised by the two cores
wound with magnetising coils J. K. placed horizontally between them, the centre
core N in either case being of a sectional area equal to that of the outside cores S. S.
The pole pieces are magnetised with the centre pole N of opposite sign to the
outside ones S. S. as herein before stated.
I construct the outside pole pieces of the field magnet in two parts divided
through the centre of the boring above described and bolted together by nuts n. n.
so that the nuts may be unscrewed and the upper half of the field magnet lifted
bodily off and the armature released and I cast the lower half of the said
outside pole pieces on the base of the machine L in order to ensure greater solidity of
construction.
I construct the armature as illustrated in Fig. II of a cylindrical shape built up
of a convenient number of soft iron discs d, d, &c. rigidly keyed or strung
through their centre upon a soft iron bar or cylinder c, c, c, e mounted upon the
spindle
8. 8.
These discs are separated or insulated from one another but are in magnetic
contact with the bar or cylinder c, c, c, c. I construct this bar or cylinder of
considerable mass, the sectional area thereof being preferably as nearly as possible
equal to that of the outside field magnet cores above described. The ends of this
bar or cylinder protrude from the body of the armature and the wire wound
thereon and form the polar extensions B, B, (Fig. 1) long enough to reach to the
side pole pieces S. S. (Fig. 1) above described when the armature is placed
in position, and so communicate magnetism to the discs forming the body of the
armature.
The body of this armature is suitably overwound with wire coils w (Fig. 2) joined
up to the commutator h in the usual manner, the current produced being collected
as usual by brushes not shewn in the drawings.
In order to place the commutator or collector in a convenient position outside the
field magnets I cut suitable channels or slots in the end of the polar extension next
the commutator and pass the conducting bars or wires from the armature to the
commutator segments through the said channels or slots and I fit over the said
channels or slots a tightly fitting collar of soft iron as illustrated to hold the said

page_text: conducting wires or bars in place and also make a good magnetic connection between
the said polar extension of the armature and the outside field magnet through the
medium of the sides of the said channels or slots.
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. An armature of a cylindrical or spherical shape either hollow or solid in
section suitably wound with wire and having central iron projections or polar
extensions from one or both ends of the said armature along its axis of revolution
for communicating magnetism from the pole or poles of one sign of the field magnet
to the body of the said armature substantially as herein before described and
illustrated.
2. A field magnet having three separate poles arranged in the same straight line
the outside poles being magnetised of a similar sign and bored to receive the polar
extensions of the armature and communicate magnetism thereto, either by actual
contact therewith, or close proximity thereto, the centre pole being magnetised of
an opposite sign to the outside poles and hollowed out to allow the upper half of the
body of the said armature to revolve therein in the usual manner substantially as
hereinbefore described and illustrated.
3. The combination of armature with field magnet as described, arranged so that
the polar extensions of the said armature revolve in, and are magnetised by, actual
contact with, or close proximity to, the outside poles of the field magnet and so
communicate magnetism to the body of the said armature revolving within the
centre pole piece of the field magnet for the purpose of generating electric currents
in the coils of wire wound upon the body of the said armature substantially as
hereinbefore described and illustrated.
Dated this Sixteenth day of Anmil 1001