IMPROVEMENTS IN OR RELATING TO DYNAMO-ELECTRIC MACHINES
Year: 1883

page_text: LETTERS PATENT to Henry Harris Lake, of the firm of Haseltine, Lake,
and Co., Patent Agents, Southampton Buildings, London, for an Invention of.
"IMPROVEMENTS IN OR RELATING TO DYNAMO-ELECTRIC MACHINES com-.
municated to him from abroad by George Washington Fuller, of Norwich,
Connecticut, United States of America,
COMPLETE SPECIFICATION filed by the said Henry Harris Lake at the
Office of the Commissioners of Patents on the 30th August 1883.
HENRY HARRIS LAKE, of the firm of Haseltine, Lake & Co Patent Agents,
Southampton Buildings, London "IMPROVEMENTS IN OR RELATING TO DYNAMO-
ELECTRIC MACHINES ;"
communicated to me from abroad by George Washington
Fuller, of Norwich, Connecticut, United States of America,
This invention relates to that class of armatures for dynamo-electric machines:
in which the armature-cores, are composed of iron spirals, for the purpose of
preventing the existence in the core of any closed circuit in which currents of
electricity can be established by induction, and is especially intended for employ-
ment with the core of a cylindrical armature having induction coils which traverse
its exterior longitudinally upon opposite sides.
The said invention consists in forming the core of a comparatively thin iron
plate in the form of a spiral which is supported upon the armature shaft, but
preferably insulated therefrom, and from the heads by which it is secured in
position. By this construction the magnetic field is nearly filled with iron, and
yet does not present a continuous circle of metal capable of constituting a closed
electrical circuit in which currents of electricity can be established by induction.
Instead of employing a single spiral, I may use two or more spirals of like pitch
and diameter, and arrange them in the core with their convolutions relatively
interplaced.
A result which approximates to that attained by this improvement may be.
obtained by using for the core a cylinder of iron which is not insulated from the
armature shaft, but which has a deep spiral groove formed in its periphery. The
.

page_text: inductive influence which tends to establish currents of electricity is most
energetically exerted upon the external portion of the core, hence the usefulness of
the spiral grooving by which the existence of a closed or continuous electrical
circuit in the exterior portion of the core is prevented.
In the accompanying drawing.
Figure 1, is an end view of an armature core constructed according to this
invention.
Figure 2, is a longitudinal section on the line xx, Figure 1.
Figure 3, is an elevation showing several convolutions of the spiral detached
from the shaft.
Figure 4. is a partial longitudinal section on the line xx, Figure 1, showing a
modification of the spacing strip for separating and insulating the convolutions of
the spiral iron plate from each other.
Figure 5 is a sectional side elevation illustrating a modification of this
invention.
Figure 6, is an end elevation of the same.
Figure 7 is a perspective view of one of the sectors of which the spiral is
built up.
Figure 8 is a view hereinafter described.
The armature shaft A, is adapted to rotate in the machine in the usual manner.
Its central portion is surrounded by the sleeve of insulating material B, outside of
which is the iron spiral C.
Iminediately adjoining the sleeve B is a spiral strip D of paper, india-rubbery.
or other insulating material, the convolutions of which are interplaced with the
convolutions of the spiral plate C and are employed for the purpose of holding
apart or spacing the convolutions of the spiral O, especially when the latter is
composed of very thin plates. The spacing strip D may be narrow as shown in
Figure 2 so that the air-spaces d are established between the convolutions of the
plate O; or the strip D may be made of thin material such as paper, and may be
of the same width as the plate C, as shown in Figure 4.
The spiral plate C is secured in position between the collar E affixed to one end
of the shaft A, and the nut F screwed upon the other end of the shaft, and is
prevented from being jarred loose by the conically formed jam-nut f.
The collar E is provided with a conical hub c and the nut F has the central
portion of its inner face similarly formed, while its external face is centrally
recessed to receive the conical periphery of the jam-nut f. The latter is provided
with the holes f' f' f'f', for the reception of the driver by which it is screwed
on or off the shaft A.
+
The nut F has four holes tapped through it to receive the steady-screws G, G, G, G,
the inner portions of the shanks of which are respectively received within the
tubes g' of insulating material, which tubes are inserted respectively through holes
in two or more of the adjoining convolutions of the spiral plate C. The spiral C
is centrally counter-sunk at each end to enable its end convolutions to clear the
peripheries of the hub e and the conical projection of the nut F.
Washers H H of insulating material are introduced respectively between the
ends of the spiral C and the inner faces of the collar and the nut F.
It is not deemed necessary to show all the parts of a dynamo-electric machine,
nor to indicate the method of applying the induction-coils to such an armature
core, inasmuch as the use of cylindrical armatures in such machines, and the
method of applying induction-coils to them, are common and well known.
By this mode of construction the spiral plate which constitutes the core and by
which the magnetic field is substantially filled with a mass of iron, is insulated
from the shaft, and the terminals of the spirals of which the core is composed are
insulated from each other, so that the core does not present a continuous circle of
metal capable of constituting a close electrical circuit in which currents of électricity
can be established by induction when the armature is employed in a dynamo-
electric machine,

page_text: Instead of forming the core of a comparatively thin iron plate in the form of a
spiral, in some cases I form such core of any required number of sectors of Bat
rings or centrally-perforated discs, successively joined by lapping their radial edges'
which may be either scarfed or off-set, and which are secured together by rivets or
otherwise.
This modification is illustrated in Figures 5, 6, 7 and 8, which show a spiral
ribbon of iron composed of sectors successively united together by the lapping and
fastening of their adjoining radial edges.
The width of the said sectors, or in other words their dimensions in degrees of
the circle, may be varied according to the diameter of the core and also according
to the thickness of the iron plate of which they are composed, so that the sectors*
will be sufficiently. light to be easily handled in putting them together.
In the drawing each sector is represented as having an arc of one hundred and
twenty degrees plus the amount required for the overlapping joints.
The sectors 2 may be made of either cast or wrought iron and when thin
enough to admit of the springing apart of the convolutions of the spiral into which
they are embodied, may be united by the scarfed joints 3 secured by the rivets or
screws 4.
When thus constructed, the convolutions of the spiral may be sprung apart
sufficiently to permit a web of paper 5, or some other insulating material, to be
interposed between them, and may then be clamped together by the nuts 6, 6
applied to the armature-shaft 7 and bearing respectively upon the outer convolutions
at the opposite ends of the spiral.
In the larger convolutions it will be undesirable to make the shaft of the full
diameter of the interior of the said convolutions, as may be done in armatures of
smaller diameter, I therefore construct the shaft with longitudinal radial wings 8
which project from the body of the shaft sufficiently to form a bearing for the
convolutions of the armature. Between these wings and the armature an insulating
material 9 is introduced.
When made of plate too rigid to permit of the springing apart of the convolutions
of the spiral, or if for any reason it be desired so to do, every third joint may have
the off-set 10. If the sectors are of less width than those before mentioned, then
when a sufficient number of sectors have been united to form a circle, the offset
joint 10 may be employed to unite one circle of sectors to the next cirole of sectors,
and so on.
It will be understood that the several sectors may be either cast or otherwise
formed with the proper twist to enable them to form the desired spiral without
being sprung, but it will ordinarily be the case that the plate of which they are
composed will be thin enough to have necessary flexibility so that the sectors may
be made of flat plate.
In either case it will be seen that a spiral armature core of large size may be
built up of sectors which are easily and conveniently handled.
The spiral core, when mounted upon the shaft 7, may be wound in the ordinary
methods by the wire composing the induction-coil..
Having thus fully described the said invention as communicated to me by my
Foreign Correspondent, and the manner of performing the same, I wish it understood
that I claim
First A cylindrical armature-core composed of an iron plate or plates formed
spirally around the armature shaft, in combination with induction-coils longi-
tudinally traversing the said core upon opposite sides thereof.
Second A cylindrical armature for a dynamo-electric machine, having its core
composed of a spiral or spirals of iron plate insulated from the armature-shaft, and
having the terminals of the said spiral or spirals insulated from each other, for the
purpose of substantially filling the magnetic field with iron while preventing the
existence, in the core, of a closed electrical circuit in which currents of electricity
can be established by induction when the armature is employed in the usual
manner in a dynamo-electric machine.

page_text: Third In a cylindrical armature substantially such as described, the spacing
strip D interplaced with the convolutions of the spiral iron plate or plates of which
the core is composed, as, and for the purposes, set forth.
Fourth A spiral core for the armature of a dynamo-electric machine built up of
sectors of iron plate successively united by having their adjoining radial edges
lapped and rivetted, screwed, or otherwise fastened together, substantially as set
forth.
In witness whereof I the said Henry Harris Lake have hereunto set my hand
and seal this thirtieth day of August in the year of our Lord One thousand
eight hundred and eighty three.